:Technically you need http://www.soils.wisc.edu/~barak/soilscience326/listofel.htm essential plant elements unless you want to starve.
:Technically you need http://www.soils.wisc.edu/~barak/soilscience326/listofel.htm essential plant elements unless you want to starve.
:See also [[Dietary mineral]] which I hope is a complete list.01:44, 20 July 2010 (UTC) <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/178.78.65.223|178.78.65.223]] ([[User talk:178.78.65.223|talk]]) </span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
:See also [[Dietary mineral]] which I hope is a complete list.01:44, 20 July 2010 (UTC) <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/178.78.65.223|178.78.65.223]] ([[User talk:178.78.65.223|talk]]) </span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
::We need salt, and that has Chlorine in it. Maybe. I'm not a scientist, though. [[Special:Contributions/142.104.215.130|142.104.215.130]] ([[User talk:142.104.215.130|talk]]) 01:45, 20 July 2010 (UTC)
Revision as of 01:45, 20 July 2010
Welcome to the science section of the Wikipedia reference desk.
The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
How is it like diving 600 feet underwater? what kind of marine life is down there? Are there coral reefs, sea slugs, moray eels, stonefish, or dolphins? I'd go scuba diving now if i could.--Diver62 (talk) 00:06, 14 July 2010 (UTC)[reply]
Me, too. You picked an interesting depth because the Photic zone goes down to a maximum of around 200 meters, or around 660 feet — below this, it is very very dark, and photosynthesis cannot occur; bioluminescence is essentially the only light available. So, in addition to the fact you're an technical diver at this point because of the crushing pressure, you're going to be carrying around a lot of flashlight gear. Comet Tuttle (talk) 00:26, 14 July 2010 (UTC)[reply]
did u ever go diving before? i'm just a highschool teen and i'm interested in going for cetology and marine biology in college. i also want to go diving as a profesional and be diver in caverns and wrecks. do u have similiar interests? i even wrote a 6-page short story of my future life of diving in the red sea. the beautiful creation of God underwater, diving in a cavern, almost killed by an octopus, and losing our air and rope. it is also about wreck diving and finding treasures and seeing squid crushing fish in the window of a sunken ship. that's my type of life! —Preceding unsigned comment added by Diver62 (talk • contribs) 00:59, 14 July 2010 (UTC)[reply]
I've seen on the internet of an octopus taking someone's underwater camera from them and swimming away with it. I just wrote it in the story for excitement, even though it may not be true. I like octopuses and dolphins especially.I also like police, detectives, and karate. Even though I want to do karate, I don't do it. I'll hopefully do it when I'm grownup. —Preceding unsigned comment added by Diver62 (talk • contribs) 11:12, 14 July 2010 (UTC)[reply]
People have dived 1,083 feet being the record on scuba gear! Isn't that amazing! All that pressure is upon you in such a deep, dark,area full of lantern-fish! —Preceding unsigned comment added by Diver62 (talk • contribs) 15:19, 14 July 2010 (UTC)[reply]
Trevor Jackson dived 600 feet and explored a ship wreck. That is a deep dive and maybe the deepest I would dive. there is also a danger of the bends, nitrogen narcosis, oxygen toxity, and related troubles down there i wouldn't ever want to deal with. —Preceding unsigned comment added by Diver62 (talk • contribs) 15:34, 14 July 2010 (UTC)[reply]
Worth noting is that those really deep dives are interesting as technical accomplishments, rather than as exploration or entertainment. Under those pressures, one incurs tremendous amounts of time in decompression (up to twelve hours) at multiple depths and with multiple gas mixtures, in exchange for at most a few minutes of bottom time. It's also an extraordinarily risky pursuit — of the nine people (all men) who have made dives to at least 800 feet, at least three have subsequently been killed in diving mishaps. Even 600-foot dives are quite risky, costly, and time-consuming.
Truth be told, if you're just hoping to see interesting underwater sights – including coral reefs, sea slugs, moray eels, stonefish, or dolphins – you're probably better off staying within a hundred feet of the surface. You save all the technical mucking about and can spend hours exploring the sea. TenOfAllTrades(talk) 15:55, 14 July 2010 (UTC)[reply]
Sure thing. That is a good point you brought out. I like to see all the paraphernalia of the sea, but also like to explore the caves, caverns, shipwrecks, and just go deep for the fun of it. I might even be a police diver someday, since i like police,or live in a submarine. Whatever God has for my life is the best thing, and that's what i'll do. —Preceding unsigned comment added by Diver62 (talk • contribs) 16:39, 14 July 2010 (UTC)[reply]
Can you see coral forming? Like, one year its small, and the next year it is 1/2 inch bigger. i thought it grows slow, but some trained divers maybe check the coral. what's the answer? PLEASE, I NEED AN ANSWER!!!!!!!!!!!!!!!!Diver62 (talk) 10:44, 15 July 2010 (UTC)[reply]
There are many, many different kinds of coral, and they all grow at different rates. But the answer to your question is yes, for some corals. I try to spend a week diving in Tenerife each year, and there's a bay with volcanic rock sticking out of the sand at about 30 feet of depth. Each year since about 2000, I've seen a few small patches of coral there getting a little bit bigger. Tenerife is geographically near the extreme of where you might expect to find that sort of coral, but it does seem to suggest that its average water temperature is getting very slightly warmer. But no more shouting, please :) --RexxS (talk) 21:48, 15 July 2010 (UTC)[reply]
THanks. I finally got my question answered. Wow! You're fortunate you can go diving every year. Can I come with you? I hope no El Nino's come with warm currents and kill all the precious coral. How much bigger and what color is the coral???Diver62 (talk) 00:43, 16 July 2010 (UTC) —Preceding unsigned comment added by Diver62 (talk • contribs) 00:43, 16 July 2010 (UTC)[reply]
M998 (the most common military vehicle called a HMMWV, "Humm-Vee", or "Hummer") is not at all like a commercial "Hummer", "H2" or "H3." The M998 is a sort of pipe-framed chassis supporting a canvas buggy powered by an eight-cylinder diesel engine; it has four-wheel independent suspension, four-wheel independent drive, a water-proof, bullet-resistant engine block, and for the most part would not be considered "safe" by NTSB standards as a civilian vehicle. The Hummer as it was commercially sold was a Chevy Tahoe with a customized fibreglass hull that marginally "looked like" an M998 (in my opinion, they are not even close, especially not in profile view: M998 vs. H3). It is not fair to call them the same vehicle at all. Nowadays, the need for a light troop transport has been largely replaced by the need for armored vehicles and MRAP, so it is probable that the HMMWV and its brethren will see very limited use on the next generation battlefield. They were never intended as "combat vehicles" (though many models did have light armament, they were intended as transports), and one of the great controversies during the early stages of the Iraq War was that American soldiers were being ferried into combat zones in unarmored HMMWVs. Nimur (talk) 22:30, 14 July 2010 (UTC)[reply]
Its completely unfair to compare the H3 to the M998. The H3 was not intended to resemble the military version, except perhaps in the grille. The H1 compares much more favorably in styling and build to its military cousin. See this pic instead of the H3 one you placed above. --Jayron3222:53, 14 July 2010 (UTC)[reply]
The Hummer H1 was a street-legal version of the HMMWV -- same frame, same drivetrain, same lousy suspension, same major body panels, and some of the same special features, and they both came off the same assembly line. The Hummer H2 was a standard GM SUV frame styled to look somewhat like the H1. The Hummer H3 was a SUV that bears a passing resemblance to an H1. --Carnildo (talk) 23:57, 14 July 2010 (UTC)[reply]
Yeah - the H2 is a Chevvy Tahoe with different body panels - and not much else! The H1 is the only one that bears any resemblance to the military vehicle - and even then, they dumbed it down a lot. SteveBaker (talk) 19:33, 15 July 2010 (UTC)[reply]
poor bees
around the hottest time of the summer, the bumble bees start acting very wierd. they stay on the plants at night and dont fly back to their nests. sometimes they dont eat too. then the other day i saw about 7 of them lying dead in the stones by our house. are they dehydrated perhaps???? or tired?? i cant find an answer anywhere else. thanks for answering--98.221.179.18 (talk) 00:59, 14 July 2010 (UTC)[reply]
Contact your local university. Maybe they would be interesting in analyzing one of the dead ones. I doubt they would be dehydrated unless there were no flowers. Tired is unlikely too. Is it possible it's mating season, and you are seeing the dead drones, and the new queens who didn't make a hive? Ariel. (talk) 09:19, 14 July 2010 (UTC)[reply]
On a similar topic, I occasionally see bumble bees apparently trying to burrow into the lawn. What are they seeking? Dbfirs09:10, 16 July 2010 (UTC)[reply]
we have these bees that are like bumblebees but theyre much bigger like three times the size and they have shiny black abdomens, not furry like bumblebees. we thouught they are carpenter bees but they gather pollen like other bees and i never see them chew wood. most books say they are carpenter bees but i dont think so. are they queen bees of some sort??? then there's some very, very tiny bumblebees that are half the normal size of a bee. i dont know!!!!--98.221.179.18 (talk) 01:03, 14 July 2010 (UTC)[reply]
Carpenter bees do collect pollen and nectar, and they fit the description; so your "big bumblebees" are probably carpenter bees indeed. You need to find where they make their tunnels in order to see or hear them "chew wood" (they can't digest wood, really, AFAIK. They just burrow in it). It is much easier to find wasps that gnaw on wood than carpenter bees that do this. The reason, I am guessing, is that the carpenter bees have no interest in openly advertising the location of their largely defenseless larvae and of the food supply, whereas wasps gnaw on wood to build their nests elsewhere. --Dr Dima (talk) 01:58, 14 July 2010 (UTC)[reply]
it is mating season for bees but i thought the drones cant fly. and i dont know why they dont go to the flowers we have in abundance in our garden instead of dying--98.221.179.18 (talk) 10:57, 14 July 2010 (UTC)[reply]
Of course drones can fly. That's pretty much the whole evolutionary point of having them :) . In most social bees the drones are basically flying insemination devices. Carpenter bees are not really social, so drones also protect the tunnels, at least in some species. --Dr Dima (talk) 11:17, 14 July 2010 (UTC)[reply]
Huge bees with shiny abdomens could be the Eastern cicada killer, which are actually wasps, not bees, but they have a more bee-like shape than a wasp-like shape. Carpenter bees are of similar size to a bumblebee, while cicada killers can be shockingly huge. The "three times the size of a bumblebee" indicates that the OP may be noticing a cicada killer instead of a Carpenter bee. --Jayron3222:43, 14 July 2010 (UTC)[reply]
Possible, but I'd be very surprised. Cicada-killers look like hornets, not like bumblebees at all; and they nest in the ground, not in wood. A picture would be the best, of course, even a low-res one. --Dr Dima (talk) 02:43, 15 July 2010 (UTC)[reply]
The simplest ink you can make would be from 'lamp black' - the fine-grained carbon that's deposited onto a surface from a smokey candle or some other kind of yellow-burning flame - mixed with a small amount of either water or alcohol (alcohol would help it dry faster on the page). Since you're going 'retro' here, you'll presumably be writing by the light of a tallow candle or an oil lamp...so this stuff will be easy to find! The mixture would probably be ground together in a pestle and mortar to ensure that the result is a smooth liquid. This stuff is bad for your lungs - and you should probably wear a face-mask while you're collecting the dry ingredient (although it should be safe once you've mixed in some liquid to stop the dust flying into the air). I wouldn't make a large batch of the stuff (at least not to start with) because it will settle out from the liquid and have to be re-ground when you need it again. This kind of ink is inconvenient, and doesn't produce great results...but that's why we now have ballpoint pens! SteveBaker (talk) 13:05, 14 July 2010 (UTC)[reply]
"One great beauty of lampblack, especially for ink-making, is that it is extremely fine in grain, and does not need to be made finer by grinding. It may be used just as it is found deposited on the cold surface of metal or earthenware, and needs only to be mixed with a little gum water to make a black ink corresponding to what we call India ink." -- The Materials and Techniques of Medieval Painting, Daniel V. Thompson, Dover Books. You'll need to stir it again before using it, is all. Gum arabic is commonly found in art shops next to the watercolours, by the way. 213.122.25.117 (talk) 14:06, 14 July 2010 (UTC)[reply]
Then there must be some kind of subtelty about how the carbon is deposited. I did this (many years ago) with the soot from a candle made from a dried grass 'wick' and animal fat - condensing out onto a large, smooth river-rock, scraping it off with a slice of flint and mixing it with rainwater (yes, it was one of those "back to nature - how well can you survive with no tools or modern conveniences" kind of things). As I recall, the stuff I wound up with was maybe about the grain size of table-salt. It clearly wasn't going to be useful as ink - so I ground it up (more rocks!) - and then it worked reasonably OK so long as you didn't try to use it on really shiney paper (it wrote OK on dried leaves though...so that was OK). Maybe it matters what the smoke condenses onto - or perhaps for some reason the nature of the fuel you're burning matters? Anyway - this works. You can do it fairly easily and a crude quill pen works just great with it. SteveBaker (talk) 19:30, 15 July 2010 (UTC)[reply]
Yes, the book does say that the source of the flame makes some difference, because "there is apt to be a certain amount of unburnt or partly burnt material ... which may affect both the colour and the working properties of the pigment". I can't see how animal fat is different from tallow, though (both beeswax and tallow are suggested, those being what candles were made of)... well, I suppose tallow is purified, so there you are, unpurified fat makes lumpy ink, perhaps. Beeswax is likely better. (And where are you going to find a tallow candle anyway?) 213.122.43.197 (talk) 01:53, 16 July 2010 (UTC)[reply]
Resistor calculation
I would like to power some LEDs while stationary on my bike and here is part of a circuit that I hope might work. I'm trying to calculate what resistor, if any, is needed between the battery and the LEDs. I don't know yet, whether I want it before or after the transistor.
My LED's have a max rated forward voltage of 3.8 V (and normal forward voltage of 3.3 V) and each needs 20 mA (I'm not certain whether I want eight LEDs or even more, but assuming it's eight, that's 160 mA total) and I need to use a PNP transistor but I don't know which one; is there a difference? I read somewhere that 0.7 V is a typical loss over a t
ransistor? My battery is 4.8 V, consisting of 4 NiCd cells.
The circuit you show won't work because the pnp transistor needs a current flowing between its base and the negative rail. Frankly, I don't see the need for a transistor there at all; you're turning on and off with a SPST switch. You're right that you can treat the LEDs as being in parallel, but you run the risk of uneven lighting because you can't guarantee that their characteristics are matched when the same voltage is across them, Some may be brighter or dimmer than others. If each of the eight LEDS actually does drop 3.3 V at 20 mA, and your battery actually is 4.8 V, then a single resistor of (4.8 − 3.3) / 0.16 = 9.35 (use 9.1 or 10) ohms would do the trick - you'd be dissipating 1.5 x 0.16 = 0.24 watts in it (a bit close to the maximum rating for some small resistors). Personally, if space wasn't a problem, I'd use one 75 ohm resistor in series with each LED. That would likely lead to more uniform brightness if the LEDs weren't perfectly matched and reduce the dissipation in each resistor to a negligible wattage. --RexxS (talk) 02:12, 14 July 2010 (UTC)[reply]
Even the diode D5 is not needed. Remove the transistor and the diode D5, reverse the polarity of the batteries such that the positive terminal connects to the anode and the negative terminal connects to the cathode. See the article LED if you need details. The article says that a typical voltage drop is about 2V for a red LED. In this case, you can even put two LEDs and a suitable resistor in series and use four such combinations in parallel. This will bring down the current. -- WikiCheng | Talk05:12, 14 July 2010 (UTC)[reply]
Refer to the circuit diagram shown Resistor calculations. With this, assuming the voltage across each LED is 2V, the voltage across each resistor would be 4.8 - 2 * 2 = 0.8. If you need a current of 20 mA (0.02 A), then you will need to use the resistor of value 0.8 / 0.02 = 40 ohms. It will consume about 0.8 * 0.02 = 0.016 W and hence a 47 ohm quarter watt resistor would do.
If you use a single LED instead of two, then the calculations would change. The current through each resistor will increase and hence you may need a resistor of higher wattage. WikiCheng | Talk10:47, 14 July 2010 (UTC)[reply]
Here is the full circuit. I corrected the batteries (thanks!!) but the D5 diode and the T1 transistor are needed. The idea behind the SPST switch is that I can switch off the circuit when the bike is parked/locked up, so I don't drain the batteries. When on the road, I want the transistor to switch on the LEDs when I stop at lights. Does the transistor work, now that the orientation of the batteries has changed (just a careless mistake)?
The LEDs which I'm looking at buying (taking into account their brightness) have a forward voltage of 3.3 V but can tolerate a max of 3.8. I don't want to use a resistor to bring the voltage down to 3.3 V because the LEDs will quickly loose full brightness as the batteries drain. This way, each battery has to loose 0.15 V (=at least a few minutes?) before the brightness starts to decrease. 89.243.130.113 (talk) 10:56, 14 July 2010 (UTC)[reply]
Ok, so what you want to do is monitor the voltage across the two series LEDs 'XPG' and switch on the other LEDs when it drops below a certain voltage? The thing you have to realise is that semiconductor junctions have an approximately exponential relationship between voltage and current, so you cannot simply apply a voltage to them and expect to be able to predict the current. You always need a current limiting mechanism (usually a resistor), particularly as the junctions have a negative temperature coefficient of voltage - which means as they get hotter, they pass more current and get even hotter. You will always need some series resistance. Looking at your full diagram, when the alternator is stopped, you are clamping the battery with the E-B junction of the transistor and the two 'XPG' junctions. There's no limit to the current, so you will need a resistor in series with the base of the transistor. That will have to be calculated from a knowledge of the forward drop of the LEDs marked 'XPG' and the fact that to turn on the transistor fully, you should plan to have a B-E current of 16 mA, about one-tenth of the C-E current (160 mA). Then you still need to limit the current through your LEDs 1–8 to 20 mA each. A fully saturated power transistor can drop as little as 0.2 V (look for VCEsat in the data sheet). That would give a voltage of about 4.6 V at the collector, so the resistor(s) have to now drop about 1.3 V while passing the current (160 mA for one or 20 mA for eight individual ones). That gives a single resistor of 8.2 ohms or eight individual series resistors of 63 ohms. I'd prefer the latter, to allow for individual variations in the LEDs 1–8. I suspect you're also trying to use the transistor to provide a constant current as the battery voltage reduces, but you really don't have enough voltage headroom to do that with simple circuitry, although FET-based ICs that provide constant current are available with relatively low voltage drops, but that would make it a lot more complex and expensive. However, you are using NiCd batteries which have a low internal resistance and a remarkably small voltage drop as they discharge, so that would compensate to some extent for your fears of the light dimming as the batteries discharge. Finally, I should warn that you're clamping the LEDs 'XPG' to about 0.7 V above the charging voltage of the batteries – please ensure this will give the results you want, or again use a resistor in series with diode D5 to limit the charging current to the NiCds if the voltage across the 'XPG' LEDs should be more than that when the alternator is running. --RexxS (talk) 14:20, 14 July 2010 (UTC)[reply]
This is my modified circuit but I'm pretty confused. My understanding is that when the bike is in motion, the 6 V will charge the batteries (1.4 V are needed to fully charge each NiCd cell so if I put a resistor there, I prevent them from fully charging and reaching 4.8 V?) I don't know how to figure what current will pass through the batteries relative to the LEDs.
When stationary, the potential difference that normally exists between the emitter and the base reverses from <-0.7 to +4.8 and current flows through the emitter to the base and collector but to return to the batteries from the base, it must pass through the XP-G LEDs which have a forward voltage of 3.0 V and therefore wont allow a current to pass? How will any current be able to pass through the base? Surely the LEDs themselves offer plenty of resistance to only 4.8V? --SeansPotato Business20:07, 14 July 2010 (UTC)[reply]
Now that we know the voltage drop across the 'XPG' LEDs (around 6 V) when conducting, we can do a little more working out. You can see that the return path for current from the base of the transistor in your new circuit has to pass through the XPG LEDs. But you should be reckoning on around 16 mA for the base current and the base of the transistor needs to be at about 4.1 V (battery voltage &minus 0.7) for it to conduct. With the diodes requiring about 6 V to conduct, you don't have enough voltage to sink 16 mA through them, so the transistor won't switch on - that is, the LEDs will offer a huge resistance to 4.8 V as you say. Here comes the next problem: you could put a resistor across the two diodes to provide a return path, but a low value resistor would waste energy when the alternator was working. The other problem is that there is C3 which has to discharge below 4.1 V for the transistor to switch on, but once the XPG diodes have switched off, it has no effective discharge path other than leakage. If C3 really is 3.3 farads (please check), a super-capacitor, then the discharge time constant for even a 100 ohm resistor is 330 seconds (and 100 ohms would waste 60 mA when peddling). I doubt you want to wait five minutes at the lights for the transistor to switch on. Have another look at C3 and see if it's actually a smaller value that we could discharge within sensible times.
R11 will limit the charging current into your NiCds - you have to drop around 0.5–1.1 V across it when the XPG LEDs are on (using Vf=3.0–3.3 V as indicated). The additional current you are asking the alternator to supply ought really to be a 'trickle' current, as NiCds don't like continuous charging above a certain value, usually rated around "N/10" – that means for example a 1200 mAH NiCd will tolerate up to 120 mA continuous charging - for such batteries, R11 would be 9.1 ohms (6.6 &minus 4.8 &minus 0.7)/0.120.
R10 will be calculated to give a base current sufficient to saturate the transistor when it is supplying 160 mA collector current, but we need to know what value of discharge resistor for C3 will be used for us to work that out. It's worth noting that a normal transistor will usually guarantee saturation if IB is one tenth of IC, but a high-gain/darlington power transistor would allow much smaller base currents, while a power FET would need virtually no current, but would require other design considerations. --RexxS (talk) 00:01, 15 July 2010 (UTC)[reply]
The capacitor was a mistake! I got the units wrong! I was 3.3mF! Now it's 4.7mF, 'cause I found a better value option.
What if I just added another cell to the battery? Then current could flow through the LEDs (I estimate 50mA at 2.6V each - the graph is at the top of page 4 on this datasheet) - it ends before it touches either axis. With the extra cell in the battery, I wouldn't need a resistor to limit current during charging, although I will never get them fully charged.
Here is my circuit now. The capacitor can discharge through the LEDs to below 5.4V, during which time, the battery-powered lights take over. With 5.4V over the XP-Gs, the 12 ohm resistor limits the current to 50mA, with 0.6V across it. What do you think?
Also, one thing stands in the way of my full comprehension of the circuit and I've highlighted it in yellow. It's taken from circuit 6 on this page, where it's described as "increasing power at moderate speeds". I've asked elsewhere and one person said they think it smooths out the fluctuations while another said it was a voltage doubler. I think the capacitors are too small to smooth. --SeansPotato Business21:16, 15 July 2010 (UTC)[reply]
Ideas for scientific imagery
I am considering some post grad studies, specifically a new course offered at a local art university entitled "Visualizing Science and Art". To be accepted by the institute, a portfolio and an admission test is required.
I possess adequate (?) skills in computing and graphics, but am widely illiterate in scientific disciplines beyond the level of secondary education. Fortunately, some tests indicate that, given time, dedication and curiosity, one can learn new tricks in advanced canine years.
So, the question: Can you suggest some (maybe six to eight) "smallish" projects for this portfolio, preferably from different disciplines, where I could test my skills, both at researching and visualising scientific ideas?
Of course, images / short movies will be made available to the WP and can be linked to relevant articles if expert editors deem them to be constructive didactic tools. Feel free to post to my talk-page, if required.
Thank you. --Cookatoo.ergo.ZooM (talk) 09:01, 14 July 2010 (UTC)[reply]
Go to American Scientist and look through their current and past issues, paying special attention to the column called "Sightings". It's devoted to scientific visualizations, and many of the articles and images are online. If you know how to use Google to find what you want, do a site search for "sightings" and/or "visualizations". There is enough material there to keep you busy for years. Good luck. Viriditas (talk) 12:29, 14 July 2010 (UTC)[reply]
The obvious one to me would be wildlife photography. Sow about finding a species article on here that can be found where you live but is currently very short and lacks images and trying to improve it? You could also look at some microscopic stuff - try looking at this site for some ideas. There are also some cool books filled with scientific pictures of varying scales - similar to the power of ten video. I can't remember what they are called but maybe someone else can. Smartse (talk) 14:34, 14 July 2010 (UTC)[reply]
I guess the question we should ask you is, what type of scientific visualization are you hoping to generate? Is it photographs and photo-like images (microscope images, computed tomography, astrophotography, etc.)? Is it quantitative information (for numerical data presented effectively and honestly, see Edward Tufte's gold-standard works, especially The Visual Display of Quantitative Information)? Is it processes, project outlines, or flowcharts? Is it diagrams or explanatory illustrations? Is your target audience scientific specialists, university students, the general public, or high schoolers? Do you have some examples of what type of work you're considering? Finally, what access do you have to original data/material which might guide your chioces? TenOfAllTrades(talk) 18:25, 14 July 2010 (UTC)[reply]
Without knowing your skills, it's hard to know what's possible. In my opinion working to make clear graphics that explain complicated things—like, say, quantum mechanics—would probably be a fairly good project and be impressive to anyone reading them, and there are plenty of existing models to look at, think about, copy, improve upon, etc. E.g. imagine you are illustrating an article in Scientific American which discusses: quantum leap, uncertainty principle, double-slit experiment, EPR paradox, Bell's inequality, and Wheeler's delayed choice experiment. Try to come up with images that both look better and explain better—at a glance—than do the ones in Wikipedia articles. (Which frankly won't be very hard!)
That's one approach. The other is to take a look at the work of Edward Tufte, which is basically the Alpha and the Omega for thinking clever thoughts about visualizing data. I see TenOfAllTrades had this same idea... if you haven't seen Tufte's work, give it a glance. --Mr.98 (talk) 23:09, 14 July 2010 (UTC)[reply]
Am I the only person who doesn't like Edward Tufte? I mean, at all? I think his diagrams are hideous and do at best an average job of communicating information. Designing effective diagrams is not all that difficult, and the world is full of people who do it better than Tufte. I can't be the only person who feels this way. -- BenRG (talk) 07:55, 15 July 2010 (UTC)[reply]
I think his diagrams are generally fine, but more important is his overall methodological approach. I think it's hard to argue with his general arguments—diagrams should be clear, devoid of chartjunk, should take care not to unintentionally mislead, and should be rich in interpretation (and he gives lots of examples pro and con of each)—whether one likes his own aesthetic implementations of them. In a world where most popular forms of representation of quantitative data are limited to the horrors of Microsoft Excel, I think he does a lot of good... --Mr.98 (talk) 12:28, 15 July 2010 (UTC)[reply]
Phone connectors in the UK
I know that phones in the UK have a different type connectors than those in the US, but form factors aside, are the two interfaces electrically compatible? Also, do the phones in the UK have different handset connectors than those in the US? Will a headset amplifier made for US phones work with a UK phone, assuming no connector issues? —Preceding unsigned comment added by 173.49.10.26 (talk) 11:14, 14 July 2010 (UTC)[reply]
Yes they are electrically compatible - you can buy simple mechanical adapters between the two. As for headset amplifiers it should work, but I'm not sure if there's even a standard on the headset connector for phones. --antilivedT | C | G02:05, 15 July 2010 (UTC)[reply]
While Antilived's comment is mostly accurate, bear in mind BT jacks used in NZ and from reading the article in the UK very occasionally have a third wire used for the ringer. I'm not sure if there is a standard way for this on RJ11, or if it was even used (there article isn't that clear). Nowadays since all phones have their own ringers, and most houses have moved to 2 wire configs (which is the current standard) but in the unlikely event you have a very old phone which doesn't have a ringer it may not work with an adapter (of course it also won't work with the vast majority of NZ sockets and I'm guessing UK sockets by far). I think this is only one way so plugging a phone with a ringer even if it has an RJ11 plug into a 3 wire BT socket with appropriate adapter should be fine. Nil Einne (talk) 13:52, 15 July 2010 (UTC)[reply]
Exoplanetary systems in Sagittarius
How many stars in Sagittarius are known to have planets? (The Wikipedia article says 16 and 19, so that needs to be fixed) Also, where can I find a list of these particular stars? Finally, is it true that "Sagittarius has more planetary host stars than any other constellation"? Viriditas (talk) 12:10, 14 July 2010 (UTC)[reply]
1. regarding 16 vs 19. "Number of stars known to have planets" is a (usually increasing) function of time, so it simply needs a date and a reference. 2. Regarding "more planetary hosts". Sagittarius is a constellation, that is, a group of stars that look close for the Earth-based observer but are not necessarily close to each-other (indeed, distance from Earth to different stars in the same constellation is often very different). The farther is the star from Earth, the harder it is to detect a planet orbiting it. Besides, we do not even know how many stars there are in the Sagittarius. This being said, it is indeed possible that Sagittarius houses more Milky Way stars (and therefore maybe more stars with planets) than any other constellation. That is because the center of the Milky Way galaxy (our galaxy) happens for the Earth-based observer to lie within the bounds of Sagittarius constellation. Does this help? --Dr Dima (talk) 21:31, 14 July 2010 (UTC)[reply]
Lately, more and more of my friends have been buying head massagers (like the ones seen here: http://www.rolostore.com/images/medium/kk_headm.jpg). I've noticed that these things have interesting, differing and sometimes hilarious effects on people. For instance a friend of mine is immune to the effects, another finds them overly tickelish and yet another just becomes totally relaxed. I myself get goosebumps. What could explain the effect of these simple devices? —Preceding unsigned comment added by 137.224.252.10 (talk) 12:13, 14 July 2010 (UTC)[reply]
They obviously don't have any meaningful effect but reflect the expectation of the purchaser. Different strokes for different folks, but they all pay. 86.4.183.90 (talk) 13:28, 14 July 2010 (UTC)[reply]
Not a good answer in my opinion, 86.4. People have varying degrees of sensitivity to stimulation. Complete OR, but I had no expectations when one of those devices was used on me, and the experience was quite noticeable. 10draftsdeep (talk) 20:03, 14 July 2010 (UTC)[reply]
Methyl 1 d - muscle growth drug
This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. TenOfAllTrades(talk) 13:30, 14 July 2010 (UTC)[reply]
whenever I eat watermellon I am struck by the fact that it resembles flesh somewhat. has anyone tried implanting it to see what happens? what does the body have to say about it? —Preceding unsigned comment added by 92.224.207.86 (talk) 13:26, 14 July 2010 (UTC)[reply]
(EC) Doctors don't randomly implant tissues into people to see what would happen. That would be very, very unethical and most likely, illegal. In any case, as watermelon flesh is 92% water, and most of the rest seems to be sugar, it would be very surprising indeed if the human body was able to use watermelon flesh for anything (other then eating it). Googlemeister (talk) 14:24, 14 July 2010 (UTC)[reply]
whenever I eat jelly I am struck by the fact that it resembles vitreous humour somewhat. has anyone tried gouging out someones eyes and replacing it with jelly to see what happens? —Preceding unsigned comment added by 92.19.107.38 (talk) 15:04, 14 July 2010 (UTC)[reply]
Whenever I eat human flesh, I am struck by the fact that it resembles watermelon. Has anyone tried grafting arms and legs onto a watermelon to see what happens? 213.122.25.117 (talk) 15:14, 14 July 2010 (UTC)[reply]
As a serious response to what seems to have been a serious question, watermelon will likely cause a foreign body reaction that would initiate a granuloma. Because watermelon is very soft and easily compressible, it would not fit into the category of space-maintaining graft material, such as calcium sulfate, silicon dioxide or allograft/xenograft bone particles such as would be used in a bone graft. In fact, calcium sulfate is not very firm and resorbs quite quickly (few weeks) and so is also not good if one would like to maintain space. Everything I've said above applied primarily to intraoral grafting and can be found in any advanced-level dentistry text. DRosenbach(Talk | Contribs)15:18, 14 July 2010 (UTC)[reply]
I notice that the skin on the backs of my arms (where the triceps are) is noticeably colder than other places on my body. Why is that? It doesn't matter if I have had a workout and my metabolism is elevated, or if I am otherwise fairly warm, the backs of the arms always feel cool. Hemoroid Agastordoff (talk) 16:36, 14 July 2010 (UTC)[reply]
why are baby birds less scared of humans than the adult birds????? there is a mockingbird and it has about three babies hidden around our yard. the adults fly away at first sight of humans, but the babies even let us pick them up. some people say the parents teach the baby birds to be scared --98.221.179.18 (talk) 17:42, 14 July 2010 (UTC)[reply]
1. You're not supposed to pick up baby birds. The parents may abandon them because they will smell different after coming into contact with your skin. 2. Our fear article is about humans, but it notes that although a capacity to fear seems to be part of human nature, "people develop specific fears as a result of learning". Human babies fear nothing, either; it's through learning that they develop fear. Comet Tuttle (talk) 18:07, 14 July 2010 (UTC)[reply]
Moving them is a problem. Just touching them is usually ok. I still wouldn't advise doing it without a good reason - you may interfere with the bird's usual development even if it isn't abandoned. The adult won't feed it while you are holding it, for instance, so it may not get as much food as it would otherwise get. --Tango (talk) 20:59, 14 July 2010 (UTC)[reply]
thats what it did around my house. the baby called an alarm because a cat was near and the mother attacked the cat, pecking its head and tail--Horseluv10 (talk) 21:36, 14 July 2010 (UTC)[reply]
I don't know whether baby birds feel fear or not - but just because they don't have a use for the emotion (yet), doesn't mean that they don't feel it. Evolution is a harsh mistress. If fear-when-young doesn't actually worsen their chances of survival then they might very well develop the fear response very early on just because it's an 'easier' way for the mechanism to form in the growing brain. Emotions such as fear, stress, anger and pain are often horribly counter-productive - but so long as (on average) they help more often than they hinder - those emotions will be there. What benefit is there for a zebra to feel horrible pain as its living body is ripped to shreds by a lion? Zero - but having that terminal pain doesn't in any way decrease their ability to pass on their genes because death is the next thing to happen. There is no drive whatever for a zebra to evolve the ability to die peacefully under those circumstances - so the pain is there regardless. Nature is horrifyingly cruel. SteveBaker (talk) 22:51, 14 July 2010 (UTC)[reply]
The suffix "-osis" just means "condition", but usually a diseased condition of some kind.
"-itis" means "inflammation", which is just one kind of pathological condition.
"Dissecans" means "dissected" or "split".
So putting all that together:
"Osteochondrosis" is any disease of the bone and cartilage.
"Osteochondritis" is when the bone and/or cartilage are inflamed, and kind of osteochondrosis.
"Osteochondritis dissecans" is a condition of the bone and cartilage where there is inflammation and where the bone and/or cartilage has split. It is a kind of osteochondritis, and therefore also a kind of osteochondrosis.
Medical terminology does not always match the things described, as many usages evolve past their roots, but reading osteochondritis dissecans indicates that the above is correct: "[[Osteochondritis dissecans]] is a type of osteochondrosis in which a lesion has formed within the cartilage layer itself, giving rise to secondary inflammation.". --Sean19:09, 14 July 2010 (UTC)[reply]
I'm not sure. People are only fed by IV if their digestive system is not working (people that are just in a coma are fed by a tube into the stomach, rather than into a vein), so it may depend on what is wrong with their digestive system. You can't get stomach contractions if the muscles around the stomach don't work, for example. --Tango (talk) 20:56, 14 July 2010 (UTC)[reply]
Yes. Intravenous hookups supplies only ion-balanced fluid but no nutrients. People who are, for instance, in a coma, are also provided with a gastrointestinal tube through which they are fed a mush of necessary nutrients (protein, carbohydrate, etc.) DRosenbach(Talk | Contribs)22:32, 14 July 2010 (UTC)[reply]
Short answer (from reading around a bit) is that I think they feel hunger for at least the first few days - but that feeling then subsides. However I have only indirect evidence of that:
Hunger_(motivational_state)#Biological_mechanisms says that "The fluctuation of leptin and ghrelin hormone levels results in the motivation of an organism to consume food. When an organism eats, adipocytes trigger the release of leptin into the body. Increasing levels of leptin results in a reduction of one's motivation to eat. After hours of non-consumption, leptin levels drop significantly. These low levels of leptin cause the release of secondary hormone, ghrelin, which in turn reinitiates the feeling of hunger." - which suggests that so long as those hormones are kept at the correct level, you won't get hungry.
Our Leptin article says that "Leptin has also been discovered to be synthesised from gastric chief cells and P/D1 cells in the stomach." - so it seems likely that without the stomach being stimulated in appropriate ways, you'd not have much leptin - and you'd be hungry no matter how well your intravenous feeding works. It also explains that administering leptin by injection doesn't work well at supressing hunger - for all sorts of complicated reasons.
Our Ghrelin article says similar things: "Ghrelin is a hormone produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas that stimulates hunger." - so, again, if there is no stomach stimulation, you'll feel hungry.
Hunger_(motivational_state)#Hunger_pangs also says that hunger pangs disappear after 3 to 4 days without food...so there is clearly something more complex going on.
Tentative conclusion: You'll be OK for the first 12 to 24 hours - then you'll feel starving hungry for a few days - then you'll be OK again.
That is incorrect, there are people who live their entire life on IV nutrition. Intestinal cancer for example, and certain birth defects. Ariel. (talk) 06:21, 15 July 2010 (UTC)[reply]
The article? Total parenteral nutrition: "Long-term PN is occasionally used to treat people suffering the extended consequences of an accident, surgery, or digestive disorder. PN has extended the life of children born with nonexistent or severely deformed organs. People have survived on total parenteral nutrition for more than 35 years, living fully productive lives." Ariel. (talk) 10:10, 15 July 2010 (UTC)[reply]
My two bits. I was once (three years ago) hooked up to an IV for about 24 hours. Normally I eat quite a lot (though a good metabolism doesn't let this be seen)), but when I was fed through the tube, I did not feel hunger, which was very, very weird. It was more like missing tastes of things (I was forbidden to eat because it was duodenal ulcer treatment). --Ouro (blah blah) 21:26, 15 July 2010 (UTC)[reply]
I have been told personally ( first hand info) from several of my patients in the ICU ( who have been on total parenteral nutrition) that they were very hungry, one particular patient was on life support for 68 days and he used to tell me specifically ( by writing on paper) that he wanted coffee and that he craved for home cooked food. he specifically told me he was hungry- ravenously!!! Fragrantforever 07:55, 17 July 2010 (UTC)
Your brain would explode. Well, not really, but a field strong enough to do that would cause massive epileptic seizures, probably paralyze the lungs, and very likely cause the heart to go into fibrillation. Looie496 (talk) 02:57, 15 July 2010 (UTC)[reply]
Says who? Neither the frog nor the cricket "exploded" when levitated [1]. They both remained active while levitating, and while there is no way to know the internal quality of their experience, neither seemed harmed after wards. Keep in mind that it is a static field (albeit a spatially varying one), so there isn't a large electrical component which seems to be what you are basing your response on. Also, the field strength in the levitation example is only about 12 times larger than is routinely used in magnetic resonance imaging with no substantial ill effects. There probably would be some strange sensations, but it is not obvious to me that it would be fatal or even dangerous to humans. (Though anyone wanting to try it should certainly run many safety tests first.) Dragons flight (talk) 03:56, 15 July 2010 (UTC)[reply]
I do not think one would "explode" or have any substantial ill effects, maybe if you were to move in the magnetic field. Magnetic levitation of water on earth (approx. humans) needs a gradient in the magnetic field of 1400 T^2/m, since a lying human is at least 25 cm high levitation of a human needs at least 19 T while levitation of a frog that moves in any direction and is 2 cm needs at least 5 T. even stronger field are probably needed in order to get stability and uniform levitation in all parts of the body. A lying human will probably need 50 T and a standing human will need 150 T. This is far stronger than the strogest magnets on earth. —Preceding unsigned comment added by Gr8xoz (talk • contribs) 05:22, 15 July 2010 (UTC)[reply]
It would feel like free fall (like in the space station), free fall is commonly (but incorrectly) referred to as no gravity. Note: Free fall (and no gravity) does not feel like floating, it feels like falling. It takes a while to get used to that. It does not feel like floating in water. Ariel. (talk) 06:19, 15 July 2010 (UTC)[reply]
I'm skeptical that it would feel like free fall -- specifically, you're not falling. You're stationary in a grav field, just as you are when you're standing on the ground, only you're not standing on the ground. Gravitational effects should be unchanged. A skydiving simulator (with the giant fans in the floor) would be the easier-to-access analogue; has anybody played with one? — Lomn11:50, 15 July 2010 (UTC)[reply]
I agree with Ariel. As far as the magnetic force per kg is uniformly equal and opposite to gravity, it is like free fall, unlike a force of wind acting on the surface.--Patrick (talk) 13:26, 15 July 2010 (UTC)[reply]
It would feel like free fall, because the forces that act on your body do so without causing much deformation; they act approximately uniformly per unit mass. The reason why standing on the ground does not feel like being in free fall is because the normal force only acts on the boundary of the ground and your body. This force only causes the atoms that touch the ground not to accelerate through the floor. But the next layer of atoms in your feet also don't accelerate, and this is due to the fact that they move a bit closer to the atoms on the boundary and then experience a force exerted by the atoms on the boundary. So, the normal force is transferred to the whole body via deformations. You can feel the internal stresses that this causes. Count Iblis (talk) 14:36, 15 July 2010 (UTC)[reply]
It should be noted that free fall (as used in this context) is not the same situation as one might experience in (for example) those skydiving simulators with the giant fans. (It's rather an awkward problem of terminology — physicists tend to talk about free fall as meaning a situation where a body is not significantly affected by drag, whereas skydivers use it to mean all the time before they deploy their parachutes.) In a skydiving simulator, one is experiencing the equivalent of a fall through air at terminal velocity, where the gravitational force on your body (indeed, on all of the infinitesimal parts of your body) is evenly matched by the drag force applied to your lower surface by the upward blowing air. As Count Iblis describes above, in the skydiving simulation the forces are actually quite similar to what you would experience lying on the ground. Force is applied to whatever part of you is 'down', and then conveyed through the body. It's not 'free fall' in the physicist's sense, because each part of your body can tell that force is being applied from its underside to lift it, and in turn applies upward force to support the parts above. When at terminal velocity while skydiving, your body can readily sense which direction is 'down', by much the same mechanisms by which you know which way is 'down' when you're lying in bed.
In contrast, the diamagnetic levitation effect acts on the entire body, fairly evenly. (At least, this is my understanding.) Instead of applying a countergravitational force to the bottom surface of the levitated body, it provides a small, uniform lift to every bit of mass throughout. Bits of matter on the 'bottom' don't have to support the weight of bits of matter on the 'top' — and that makes a huge difference to the sensations of the individual being so levitated. It's really a free fall as far as the body is concerned. (Actually, I've cheated a bit in my definitions here, too. Usually 'free fall' for physicists means that a body is only being acted on by gravitational force. In a sense, what we're doing here is applying a bit of 'antigravity' through electromagnetic means to null out the effects of gravity. What an object experiences here is probably functionally close to real zero gravity — locally flat spacetime, with no gravitational force acting.) TenOfAllTrades(talk) 15:06, 15 July 2010 (UTC)[reply]
And now I'm going to respond to myself, and note that the perception of weightlessness or freefall is going to be even more complicated than we'd like in this situation, because the diamagnetic levitation effect is going to affect different materials slightly differently. The magnetic permeability of bone is going to differ from that of soft tissue, for instance, which means that the amount of levitation force felt by each type of tissue will also be slightly different. What effect this will have on the perceptions experienced by the vestibular system I couldn't guess. TenOfAllTrades(talk) 20:14, 15 July 2010 (UTC)[reply]
The strongest magnetic field that you are ever likely to encounter personally is about 10^4 Gauss if you have Magnetic Resonance Imaging (MRI) scan for medical diagnosis. Such fields pose no threat to your health, hardly affecting the atoms in your body. Fields in excess of 10^9 Gauss, however, would be instantly lethal. Such fields strongly distort atoms, compressing atomic electron clouds into cigar shapes, with the long axis aligned with the field, thus rendering the chemistry of life impossible. A magnetar within 1000 kilometers would thus kill you via pure static magnetism -- if it didn't already get you with X-rays, gamma rays, high energy particles, extreme gravity, bursts and flares...
MRIS give me headaches though. I don't know whether it was the placebo effect but I actually believed there were induced currents and depolarisations running through my brain. John Riemann Soong (talk) 15:03, 15 July 2010 (UTC)[reply]
I don't think it's a placebo effect, it's well documented that many individuals feel "weird" a bit while around the large MRI devices. I personally feel a bit nauseated and dizzy when I have to stick my head in the bore. -- Sjschen (talk) 21:19, 15 July 2010 (UTC)[reply]
On safety, it's worth noting that clinical MRI instruments now regularly reach fields of up to about 7 tesla ([2]), and there are some small-bore instruments (for wrists and knees and such, rather than the whole body) which have fields up to 9.4 tesla or more. There has been some fairly extensive testing on the effects of these high fields on the human body. You can start here or here and work back through their references. Meanwhile, the levitating frog demo was done at a field of 16 tesla. In other words, we're actually not that far from exposing humans to sufficiently high field strengths for this sort of levitation — though generating a full-human-sized 16 T field represents a non-trivial engineering challenge. TenOfAllTrades(talk) 15:17, 15 July 2010 (UTC)[reply]
I'll be looking at the literature, but can anyone suggest to me a safe threshold for electric fields to induce excitement in cells (especially constitutive exocytosis). Preferably protocols that minimises any membrane depolarisation, and definitely minimises the risk of apoptosis and mass cell death. I want to stimulate the cells, not stress them.
I'm trying to track nanoparticles for several hours within *live* cells being observed under a (very expensive) microscope for several hours. What voltages and currents should I use? We do have batteries and various apparatuses (but we normally use them in vitro rather than to induce anything in vivo). I am working with lung cancer epithelial cells, not nervous or neuroendocrine cells. John Riemann Soong (talk) 03:36, 15 July 2010 (UTC)[reply]
Membrane depolarization is the signal that transmutes an electric field into a cellular response, so asking for excitement without depolarization is a contradiction. In any case, generally tissue destructive effects are determined more directly by current than by voltage, and more by how long a current is sustained than by how strong the current is. Figuring out how strong a field you are creating with a given stimulus protocol is likely to be very difficult. If you want to apply electric fields, I advise getting hold of a device called a "stimulus isolator", if you don't already have one. They are standard equipment in electrophysiology labs. Looie496 (talk) 23:47, 15 July 2010 (UTC)[reply]
Recently I discovered a yellow glass marble in the street and brought it home, and noticed that it glows a bright yellow-orange under blacklight. I also noticed that a red glass paperweight was glowing yellow as well, but only around the edges (where it appears yellow in ordinary light). What causes these glass items to glow this way? 68.123.238.146 (talk) 03:58, 15 July 2010 (UTC)[reply]
And just in case you're worried - these objects are not especially radioactive. We're not talking about the isotopes of uranium that produce the most radiation - and anything they do produce will mostly be absorbed by the surrounding glass. What is interesting is that uranium glass hasn't been made in any quantity for 60 or more years - so these objects could be rather old. SteveBaker (talk) 12:33, 15 July 2010 (UTC)[reply]
Backing up a moment, I re-read the OP: he said that it fluoresces "yellow-orange", which isn't a characteristic of uranium glass (it was late, I mis-read). Perhaps I was wrong about this particular marble. Apparently manganese can produce an orange fluorescence [3].Acroterion(talk)15:34, 15 July 2010 (UTC)[reply]
Heisenberg quote on quantum mechanics and Indian philosophy
I have seen in many places the quote "After the conversations about Indian philosophy, some of the ideas of Quantum Physics that had seemed so crazy suddenly made much more sense" attributed to Heisenberg. Wikiquote says it is a comment made by Fritjof Capra about Heisenberg. Did Heisenberg actually share this position ( quantum mechanics and Indian philosophy)? Is it fare to attribute this quote to Heisenberg? 220.227.207.32 (talk) 04:11, 15 July 2010 (UTC)[reply]
About this quote Fritjof said "he (Heisenberg) told me something that I think is not known publicly because he never published it" in an interview (see The Tao of Physics). I could not find any other reference of Heisenberg saying this specific quote but there are several references indicating Indian philosophy had some influence on Heisenberg . - manya (talk) 05:07, 15 July 2010 (UTC)[reply]
One should be very careful about the interpretation of this. People get inspiration from a wide range of sources - but that's not the same thing as saying (for example) that quantum theory is 'based on' Indian philosophy - or that proof of quantum theory somehow validates that philosophy as being true. Inspiration is a complicated thing - often it's just an unrelated topic that provides a mental jolt that unfreezes the brain to look at different approaches to a previously difficult topic. Richard Feynman always said that his interest in bongo playing inspired some of the ideas in his quantum electrodynamics work...he definitely didn't mean that quantum electrodynamics has anything whatever to do with bongo drums or the sounds they make! Analogy is a powerful tool for understanding one topic based on an easier understanding of an unrelated topic...but an analogy isn't a causal or consequential connection between two topics, it's nothing more than some kind of vague structural similarity - and that's an important thing to bear in mind. SteveBaker (talk) 12:30, 15 July 2010 (UTC)[reply]
For that matter, Heisenberg might have been making a joke in the vein of "quantum mechanics makes a lot more sense when I'm drunk" which Capra mistakenly took seriously. -- BenRG (talk) 18:29, 15 July 2010 (UTC)[reply]
Thank you all for the replies. Ignoring these remarks, what was Heisenberg's (own) position on this Capra-type "theory"; that is on the "theory" that quantum mechanics justifies Indian ( which Indian is another question) view of the world. 220.227.207.32 (talk) 04:29, 16 July 2010 (UTC)[reply]
Bearing in mind that Heisenberg died only the year following the publication of Capra's The Tao of Physics, he might not have been very aware of it, or may not have made any recorded pronouncement of any opinion he did have. However, he did give an address in 1973 titled (in translation) "Scientific and Religious Truth", as mentioned in our article on him (last paragraph of the Post 1945 section) which also mentions a couple of books by others that cover his views in this area: these publications, if you can access them, might be of interest to you. 87.81.230.195 (talk) 07:04, 16 July 2010 (UTC)[reply]
TToP was specifically based on the bootstrap model, which was an attempt to understand hadron physics by abandoning the notion of elementary particles. The bootstrap model attracted a lot of interest for a few years, especially at Berkeley, where Capra was at the time, but it was never predictive, and it was abandoned around 1973–5 after asymptotic freedom was discovered and it became clear that the quark model was the correct model of hadrons. So any opinion a physicist might have had about the material in TToP in 1972 would probably need updating by 1976. -- BenRG (talk) 19:43, 16 July 2010 (UTC)[reply]
I happen to know that there will be a very interesting book coming out in the next year or so regarding the Capra book and other similar works that came out in the 1970s and how they were received by the physics community at that time. If you're interested in details I'd be happy to give them to you over e-mail—just use the Wikipedia e-mail function. --Mr.98 (talk) 20:27, 17 July 2010 (UTC)[reply]
whats the best way to kill a tick? yesterday we found 4 ticks around our house and on people. my brother made a contraption that electorcutes them and thats what we do now. we used to burn them with matches. whats your way to get rid of them???--Horseluv10 (talk) 11:31, 15 July 2010 (UTC)[reply]
If they are just wondering around then I would simply crush them with something. If they have latched onto a person or animal then you need to be very careful when removing them. I would suggest purchasing a specialised tick removal tool (basically a piece of plastic with a notch in it that you slide around and under the tick to remove it). It is very important to make sure you remove the whole tick and do not leave the mouthparts in the skin, where they could cause an infection. You should also monitor anyone bitten by a tick for several weeks for signs of Lyme disease. If you have any concerns, I suggest contacting a doctor. --Tango (talk) 11:40, 15 July 2010 (UTC)[reply]
If someone has been bitten by a tick, it is recommended to keep the thing in the freezer in a bag for a few weeks. If the victim in question does show symptoms, the frozen tick can be useful for doctors to analyze later. And if they are fine, there's nothing better than finding a frozen tick in your freezer months later! --Mr.98 (talk) 12:19, 15 July 2010 (UTC)[reply]
talking about crushing them, ticks have VERY hard exoskeletons and that would make them very difficult to crush. we've tried that already with unsuccessful results. but freezing a tick might be a good idea.--Horseluv10 (talk) 12:35, 15 July 2010 (UTC)[reply]
We use an old country remedy: rub some Vaseline all over the little buggers. As they breathe through pores on the side, they will suffocate and fall off. --TammyMoet (talk) 13:28, 15 July 2010 (UTC)[reply]
Listen, and understand. That tick is out there. It can't be bargained with. It can't be reasoned with. It doesn't feel pity, or remorse, or fear. And it absolutely will not stop, ever, until you are dead.
But seriously, all the advice above is good, except that the tick is nothing magical like above - any way to kill it will do the job and won't leave toxins unless possibly if you use some concentrated acid. SamuelRiv (talk) 02:59, 16 July 2010 (UTC)[reply]
On the other hand, there are people who have reported hiccups lasting for years, and that nothing could stop them. ~AH1(TCU)18:43, 16 July 2010 (UTC)[reply]
I have recently finished my High school equivalent studies (A-levels) and am applying for undergraduate medicine in several universities. A local university is offering a Bachelor of Science in Speech Language Therapy (BSc. SLT). I want to know the future potential of such a qualification and the pay grade of Speech Therapists compared to other medical qualifications. Thanks. --119.155.0.198 (talk) 12:26, 15 July 2010 (UTC)[reply]
which, it being illegal to practice without the entirety of that training (with no alternative), artificially limits supply as De Beers does with its diamonds. As for demand, obviously it is almost totally inelastic: I want my finger sewn back on whether it costs $80, $800, $8,000, or, if I can take that much debt on, $80,000. The resulting price is charged in the U.S.; Britain, being "commie bastards" when it comes to health care, do not obey the rules of economics, and you do not have to pay $80,000 (if you could repay that in your lifetime) to get your finger sewn back on. 84.153.255.139 (talk) 16:17, 15 July 2010 (UTC)[reply]
p.s.: if I would pay $80,000, why isn't that the price in the U.S.? (it is in fact less). It is because although I can put aside $80,000 over the next, say, fifteen years, repaying the loan, not everyone could, and so the price is lower. If nearly everyone who needed a finger sewn back on in the United States were a billionaire, with myself being the sole exception, you could rest assured that I would be asked for, say, $13 mil for the operation (if not more). I could not afford that, but the price is not set by me, but by the billionaires, since we're talking about a monopoly situation -- it is illegal for my Uncle Fred to read up on the operation overnight and do it for me for a few hundred. 84.153.255.139 (talk) 16:21, 15 July 2010 (UTC)[reply]
Part of that is because if you let your Uncle Fred do it, at best you would lose your finger anyways, and at worst you would get gangrene, or a nasty infection and die. Googlemeister (talk) 16:49, 15 July 2010 (UTC)[reply]
The US health care system isn't a free market either, though, because of the laws you mention about practising without a license. The US has regulation on one side of the market while the UK has regulation on both. That is why the UK has better healthcare than the US (there are plenty of statistics to back up that claim). --Tango (talk) 16:56, 15 July 2010 (UTC)[reply]
Well, to get that result you have to pick a definition of better and use the statistics that correspond to it. The US has "better" health care in the sense of what you can get immediately if price is no object. At least I would be quite surprised if you have statistics refuting that. --Trovatore (talk) 18:51, 15 July 2010 (UTC)[reply]
The UK has plenty of private health care that you can get immediate access to if you are willing and able to pay (or have insurance). It is no different from the US in that respect. --Tango (talk) 19:17, 15 July 2010 (UTC)[reply]
I know you can get it in the UK (though admittedly I probably wasn't thinking about it; I'm more familiar with Canada, where privately paid health care is essentially unavailable even though not technically illegal). But the question is, is it as good? My understanding is that it is not, at least at the top end. --Trovatore (talk) 21:25, 15 July 2010 (UTC)[reply]
My mother did this track, and hated the dull repetitiveness of therapy. Get a good academic background if you're interested in the subject such that you can always combine research with therapy, or teaching with therapy. SamuelRiv (talk) 03:00, 16 July 2010 (UTC)[reply]
Starting masturbation at a very young age
How do some people learn to do it when they are as young as 5 years old (in my case) while others don't know about it until or after puberty? For me, I wasn't even taught about it but as long as I can remember, I started doing it since I was like 5 years old. I remember getting the exact same sensation of orgasm even though I hadn't ejaculated any semen then (which interestingly suggests that the ability to feel orgasm is developed much early in life, way before puberty, separately from the ability to make sperms/eggs for sexual reproduction). I'd like to know how and why people drastically differ in terms of the time period at which they self-teach masturbation (ranging from as young as 5 years old to 20 or older). —Preceding unsigned comment added by 142.58.43.84 (talk) 18:15, 15 July 2010 (UTC)[reply]
I'm not sure there will be any particular reason for it. I guess most people discover the pleasure of masturbation by chance, which means it is entirely expected that different people will discover it at different times. --Tango (talk) 18:33, 15 July 2010 (UTC)[reply]
It is perfectly normal to discover it at a young age. As a child explores the world that surrounds it, it also explores its own body, what it is composed of, what abilities it has (walking, etc.). It's natural to also discover masturbation in this way. --Ouro (blah blah) 21:22, 15 July 2010 (UTC)[reply]
I'm not sure that this really fits within the Science category, so I apologize if this needs to be moved.
I remember reading a Wikipedia article a while ago, but I've completely forgotten the name of it. It was about a type of wind burst, for lack of a better term. I think it had an Arabic or Persian name. There was only one recorded instance of it occurring in the United States, in the 1800s -- the heat rose to shocking levels, and intense wind blew red-hot sand across California, to the point where hanging fruits were burnt and damaged on the side exposed to the wind. It drove everyone inside, where they were safe because of their adobe-walled houses (and "adobe-walled" was specifically mentioned in the article), but a man on a small ship off coast was either killed, or extremely badly burnt.
Does anyone know what I'm talking about? If someone could tell me the term so I can tell someone about the article, it'd be fantastic. If not, sorry for wasting the reference desk's time. 202.10.88.115 (talk) 20:36, 15 July 2010 (UTC)[reply]
I think that I was taught that the proper way to mix a solution in a volumetric flask is to put in the stopper, hold the stopper and then swirl it around while holding it upside down. Every time I do that, though, at least when I'm using a ground glass stopper, a little bit of the solution leaks out. Is there some way to prevent this or am I doing something wrong? I've noticed that the plastic stoppers don't seem to have this problem, but I've mostly got glass stoppers and I'm sure chemists didn't just let their flasks leak before plastic stoppers came along. ike9898 (talk) 20:40, 15 July 2010 (UTC)[reply]
A ground glass stopper should not leak! You obviously have the wrong size stopper. A common error is to use a stopper marked with a single size number (e.g. 19) in a joint where there are two numbers marked (e.g. 19/22) – a 19 stopper will go into a 19/22 joint and look like it fits, but it will not be watertight. Check that the ground part of the stopper fits the whole of the ground part of the joint – you might have to search around lab drawers for stoppers that actually fit! Physchim62(talk)21:23, 15 July 2010 (UTC)[reply]
Rubber stoppers aren't really a good answer anyway - rubber (or even plastic "rubber substitute") reacts with too many things. Glass is fairly inert. SteveBaker (talk) 23:15, 15 July 2010 (UTC)[reply]
The plastic stoppers for volumetric flasks are usually hard PTFE, which is usually inert enough for anything you would usually use a volumetric flask for. They do have a tendency to get stained by permanganate though. Physchim62(talk)00:34, 16 July 2010 (UTC)[reply]
Well, I'm pretty sure I'm using the correct size stoppers, but what about the mixing technique? I've always tried to do what I was shown in an O Chem lab 18 years ago - invert and sort of swirl the bulb around. Doing it this way the flask has to stay upside down for at least several seconds. Since asking this question, I've Googled around and failed to find any mention of this mixing technique. A few sources mention inverting the flask very briefly, several times. ike9898 (talk) 00:52, 16 July 2010 (UTC)[reply]
I've heard of that technique – I was probably taught it at some point or other – but I've never used it myself and I didn't teach it when it was me doing the teaching. A little trick to remember is that it is virtually never necessary to dissolve anything in a volumetric flask, so you only need enough mixing to get a homogenous solution. That you can acheive by briefly inverting the flask a couple of times. Physchim62(talk)01:06, 16 July 2010 (UTC)[reply]
Makes sense, except that the more I learn about mixing, the more I believe that it takes more effort to achieve homogeneity that intuition would tell me. I think I'll just make it a practice to briefly invert, but do it many times. ike9898 (talk) 13:29, 16 July 2010 (UTC)[reply]
Why not? If one particle collapses into a certain state, the other particle instantly collapses into the corresponding state, regardless of the distance between them. --138.110.206.100 (talk) 21:27, 15 July 2010 (UTC)[reply]
Isn't that precisely, exactly, why quantum entanglement is so exciting? Because it allows for faster-than-light information transfer, and hence potentially faster-than-light communication? At the least, I'd expect a reference or elaborated answer from some giving such a categorical answer on the science desk. 86.163.212.254 (talk) 21:52, 15 July 2010 (UTC)[reply]
See our article on quantum entanglement. While there is apparently a FTL state change, no useful information can be transferred without some kind of separate key, which must be transmitted normally. — Lomn21:59, 15 July 2010 (UTC)[reply]
The collapse of the wavefunction chooses randomly among the possible states, so even though the measurement at one end allows you to predict the properties of the partner particle, the individual states presented are essentially random. Consequently, we don't know of any way to control the process, even in principle, that could convey non-random information to the other observer. There are subtleties about why different communication strategies fail, but so far we don't know any way to exploit quantum entanglement to send usable information faster than light. Dragons flight (talk) 22:19, 15 July 2010 (UTC)[reply]
Couldn't you collapse multiple particles until the number of particles with the intended state is greater than the number of particles with the other state? The other person would count the number of particles with each state and determine which is greater. --138.110.206.102 (talk) 23:11, 15 July 2010 (UTC)[reply]
(ec) Consider the classical equivalent: make some red/black playing card pairs (to use Steve's suggestion) and then look at your cards until you've seen more red than black (or more black than red). The other person, looking at their cards, can't tell when you stopped looking. The quantum case is the same. In fact, the quantum version of this experiment is the classical version. To get any peculiarly quantum predictions you need to have a choice of noncommuting bases for your measurement. That aspect of entanglement is often omitted from popularizations, even though it's the only part of the thing that's actually quantum. Instead they give you plain old classical correlation—Steve's red and black cards—presented as though it were new and amazing.
Communication via entanglement is provably impossible in mathematically rigorous formulations of quantum mechanics. The Standard Model has no mathematically rigorous formulation and it's not technically possible to prove anything about it, so maybe one could try to argue that it's an open question there. But any obvious way to do it would also work in rigorous quantum theories, and hence is already ruled out. -- BenRG (talk) 00:09, 16 July 2010 (UTC)[reply]
For some reason, this confuses a lot of people. Perhaps it's wishful thinking or willful misunderstanding - but FTL communication it ain't. If you actually read Quantum_entanglement#Concept and the following section Quantum_entanglement#Other_Interpretations, this is all spelled out very clearly - with the conclusion: "However, because the method involves uncontrollable observation rather than controllable changing of state, no actual information is transmitted in this process. Therefore, the speed of light remains the communication speed limit".
So you and a friend both have one of the two entangled particles. You measure the state of yours and the answer is "A" - and if your friend examines his, it'll be "B". He knows the state of your particle and you know the state of his. But that's no different than if you'd taken two playing cards - one red and one black, mixed them up and sealed them into two envelopes before you moved away from each other. When you opened yours and found it was red - you'd know the state of your friend's card is black...but that information doesn't allow you to communicate any new information. Since the act of examining the particle forces the entanglement to collapse - you can't even tell when the other person examined their particle. There really is no way for information (or mass or energy) to exceed the speed of light. SteveBaker (talk) 23:12, 15 July 2010 (UTC)[reply]
Read my above post. You can't control the state of each particle, but you can control whether you collapse another one or stop. Once the majority are collapsed to the state you want, stop. --138.110.206.102 (talk) 23:21, 15 July 2010 (UTC)[reply]
Yes, but the supposed recipient of the message has no way of telling how many particles you ended up collapsing -- unless you send him a message to tell him, which sort of defeats the purpose. Looie496 (talk) 23:26, 15 July 2010 (UTC)[reply]
No. All you can do is make a measurement. If the particle is entangled it will collapse, but you have no way of knowing whether the result you get occurs because you collapsed the wavefunction or if the wavefunction had already been collapsed from the other end. Dragons flight (talk) 23:46, 15 July 2010 (UTC)[reply]
That's not quite accurate, DF. @138: The act of measuring the state "collapses" the uncertainty, but since the particles are entangled, the friend could tell the state of his particle without observing it by ... asking the first person what the measured state of his/her particle was! Of course, the question and answer are limited to light speed communication, so that's a dead end as well. --RexxS (talk) 00:00, 16 July 2010 (UTC)[reply]
Yeah, I'd guess some sort of lens effect. Note that it doesn't match the contours of the lunar terrain that it's superimposed on. — Lomn21:58, 15 July 2010 (UTC)[reply]
This page says "Note that the blue coloration at the top right is undoubtedly an artifact." - which isn't exactly helpful. On this page you can read what Bean and Conrad were saying to each other when the photo was taken. Pretty boring stuff, definitely not: "OMG! That alien spaceship is firing at us with it's high power blue space-laser! <bzzzzttttt>"! In this wider shot (which was two shots before that one on the same roll of film: [5] you can see that the sun was shining from above and to the right - so the odds are good that this is some kind of reflection from inside the camera or a lens flare of some kind. SteveBaker (talk) 22:37, 15 July 2010 (UTC)[reply]
The official NASA Apollo Lunar Surface Journal website indicates that for the image in question, AS12-47-6922: "The blue 'fog' is do to a dust smudge which first shows up on 6813." In fact this smudge shows up in several of the preceding and following images. AS12-47-6922 was also converted into an anaglyph with photograph AS12-47-6923: [6] You can see from the overlay that the artifact is not actually on the surface. Also, SteveBaker's dialog link is a mirror of the official listing from NASA ALSJ website. Nimur (talk) 23:11, 15 July 2010 (UTC)[reply]
Sorry - we're not allowed to answer that - you're asking for a medical diagnosis and we're specifically not allowed to provide one (see the note at the top of the page). If you are worried about it, you should consult a doctor. SteveBaker (talk) 22:21, 15 July 2010 (UTC)[reply]
Yeh, it took awhile to figure out what the OP was asking about. It would require a doctor to figure out if it's a bunion or just her natural boniness. The best bet is for the OP to read that article and take his own best guess. Or he could write a fan letter and ask. I'm sure such a letter would get a quick reaction. ←Baseball BugsWhat's up, Doc?carrots→ 23:45, 15 July 2010 (UTC)[reply]
Steve, why should I consult my doctor? Do you really think that it's me on this photo? That I posted picture of myself with my tits almost out? 83.31.97.1 (talk) 23:56, 15 July 2010 (UTC)[reply]
Because: (a) You use an anonymous IP address, so we don't know whether you are this person or not (b) you can ask a doctor for a medical opinion - it doesn't have to be you that you're talking about (c) our policy about not diagnosing medical conditions requires that we suggest consulting a doctor and (d) if you're looking at that picture and you're worrying about bunions...you might need to see a doctor! :-) Either way, it doesn't matter. We aren't allowed to diagnose medical conditions - period. SteveBaker (talk) 12:13, 16 July 2010 (UTC)[reply]
(Not a diagnosis, and not medical advice:)When my feet looked like that, the podiatrist did surgery for bunions. Fortunately, my boobs never looked like that. (See Gynecomastia (Not medical advice)) Edison (talk) 04:27, 16 July 2010 (UTC)[reply]
My understanding is that when the beans are taken from the tree, the are left to dry, and undergo fermentation. So, (believing that fermentation always results in ethanol) it would be logical to presume that chocolate naturally contains alcohol, without any being added. So if anybody can enlighten me to whether the alcohol is removed, or maybe even if there is a brand of alcoholic beverage from chocolate (without being added). 99.114.94.169 (talk) 23:23, 15 July 2010 (UTC)[reply]
Fermentation does not always result in ethanol. Fermentation merely means the action of microbes (yeasts, molds, and bacteria) on a foodstuff. There can be any number of products of fermentation; sometimes it is ethanol but it could be vinegar or cheese or any of a number of other compounds. In cocoa fermentation specifically, there is a two stage fermentation. Yeasts produce ethanol, which is consumed by bacteria and further modified to produce lactic and acetic acids. Coincidentally, this was covered in some detail earlier today in the "Candy" episode of Modern Marvels on History Channel, which is why I remembered it. --Jayron3223:54, 15 July 2010 (UTC)[reply]
Funny, because I saw it too, and while I was reading your response, I noticed how similar it was to the episode... well I must of missed that part, but thank you. So, are there any alcoholic beverages using chocolate? 99.114.94.169 (talk) 23:58, 15 July 2010 (UTC)[reply]
Not only does fermentation not always produce alcohol, it also doesn't always require microbes. Black tea and salami are two examples of foods produced by non-microbial fermentation. Looie496 (talk) 03:29, 16 July 2010 (UTC)[reply]
This may be controversial. Our article on Black tea states: 'This process is also called "fermentation", which is a misnomer since no actual fermentation takes place.' My impression of salami production suggests to me that at least historically, they were certainly not sterile during their "fermentation". -- Scray (talk) 03:41, 16 July 2010 (UTC)[reply]
Foods that are "air dried" or "air cured" most certainly have access to wild yeasts and other microbes, and absolutely could be fermented. Sourdough bread is one classic example. But salamis which are hung to dry and ferment would be another. --Jayron3204:47, 16 July 2010 (UTC)[reply]
Is there an easy way to estimate genes in genetics?
Let me explain. Say a man marries a woman and they have kids. The man has black hair and the woman has brown hair. For this we'll say black (B) is dominant over brown (b). Say the man has Bb and the woman has bb. Is there an easy way to figure out what hair color their children would have? I'm fairly new to genetics, so I need some help. Thanks! RaptorLet's talk/My mistakes; I mean, er, contributions00:43, 16 July 2010 (UTC)[reply]
In your example (assuming the false genetic determination of hair colour, but that's unimportant), each of the couple's children would have a 50% chance of having black hair (Bb) and a 50% chance of having brown hair (bb). That's because all the woman's eggs will carry the b gene, while half the man's sperm will carry the b gene and the other half the B gene. So the couple could have three brown haired children or three black haired children: the probability of either of those cases happening is 12.5% (50%×50%×50%). Physchim62(talk)01:36, 16 July 2010 (UTC)[reply]
Any combination thereof would be possible (i.e. 2 brown haired, one black haired, two black haired, one brown haired). Falconusptc04:20, 16 July 2010 (UTC)[reply]
When you are in your car and the person in the car next to you blasts their rock music, your car vibrates in your ears. Is that sound waves? Please answer me!!Diver62 (talk) 00:49, 16 July 2010 (UTC)[reply]
Is this a blast furnace or some other sort of furnace?
Is this pictured object a blast furnace? According to sources I have on it (I'll be adding an article once I know whether it's a blast furnace), this furnace was used to produce iron, using coal and charcoal for fuel. Our article on blast furnace doesn't show any furnaces like this one, but I've found pictures of many more, such as this one. Nyttend (talk) 03:36, 16 July 2010 (UTC)[reply]
It could be some type of Bloomery. The designs of blast furnaces are VERY varied from culture to culture and time to time. Depending on the age and location, it could very well be a smelting furnace of some sort. Just about any metal-using culture would need a furnace of some sort for smelting purposes. --Jayron3204:44, 16 July 2010 (UTC)[reply]
The other day I was looking at Venus with my 6.25" reflector. I was hoping to see it as a crescent. All I could see was a very bright spot, with all three eyepieces. Is Venus just too bright for that? Bubba73(You talkin' to me?), 04:11, 16 July 2010 (UTC)[reply]
Venus is very bright at present. Aspects of Venus shows that the next time of greatest brilliancy is on 27 September 2010, less than three months away. Venus will continue to get brighter and remain very bright from August to January, and then fade after that. Dolphin(t)04:18, 16 July 2010 (UTC)[reply]
Over the next few months Venus will be visible with the naked eye during the day. It appears much less bright during the day. Try viewing Venus through your telescope during the day and you might be able to see the exact outline, crescent or whatever. Dolphin(t)04:26, 16 July 2010 (UTC)[reply]
As of now Venus is slightly gibbous, i.e. slightly more than half full (which is harder to see clearly than when it's a crescent), but in your telescope you should be able to see the shape: it will soon (mid-August) go through 'half' phase and then become an increasingly larger but thinner crescent over the following two months. Likely the brightness will be causing you some problem; also, if you're looking when Venus is quite near the horizon, atmospheric distortion will blur the shape, so Dolphin's suggestion of daylight viewing, which reduces the contrast and places the planet further from the horizon, will help - but be very careful not to let your telescope point at the Sun - even an accidental glimpse could permanently damage your eyesight! It's also possible that your telescope may have slipped out of good collimation and not be focussing accurately - have you tried checking that it's still showing stars as good point images? How well is it showing Mars, which is only about 15 degrees to the east of Venus (but which is very near (92%) full) right now? 87.81.230.195 (talk) 06:23, 16 July 2010 (UTC)[reply]
Maybe it is just too bright right now. I may try putting in the Barlow lens and see if that helps cut down the brightness. I'll try before it gets completely dark too. Bubba73(You talkin' to me?), 15:58, 16 July 2010 (UTC)[reply]
The Barlow lens might indeed work, in that increasing the magnification (on the same aperture) decreases the brightness. On the other hand, it will also magnify any atmospheric distortions, telescopic aberrations and telescope/mount vibrations. Something you might also try is stopping off some of your aperture by putting a partial mask on the front end of your tube (typically, a cover with a small - say 2-inch diameter - hole, off-centre to avoid the secondary mirror of what I'm guessing is a reflecting 'scope). This also reduces the image brightness, and may reduce some optical aberrations if they're part of the problem. Good luck!87.81.230.195 (talk) 18:13, 16 July 2010 (UTC)[reply]
I saw Venus in my 4.5" telescope recently, and was able to observe the cresent quite well. My telescope also has a mask that reduces the frontal aperture to a mere 2", and this is useful for brighter objects. If your telescope doesn't have that, you can try a telescope filter that blocks most of the light so the image will be darker and easier to see, or it could be poor atmospheric seeing disrupting your view. ~AH1(TCU)18:27, 16 July 2010 (UTC)[reply]
How do fish drink?
The question just popped into my head. Do they every once in a while just take a gulp? Do their bodies simply absorb a certain autonomically regulated amount through their skin? their gills?--162.83.139.249 (talk) 04:34, 16 July 2010 (UTC)[reply]
Fish do not drink; they get all the moisture they need through their food, but they can also absorb water through their skin. (This applies to freshwater fish as well as to saltwater fish.)--Shantavira|feed me05:38, 16 July 2010 (UTC)[reply]
You can etch it, with either conventional tools, laser etching, or a solvent. We used to CNC a lot of HDPE and we would always put in a mark or ID on each piece with the tool. A dremel will do the trick, or even a razor or screwdriver (depending on how nice you want it to look). You should be able to make a thin enough etch that it won't puncture the bottle. Nimur (talk) 15:29, 16 July 2010 (UTC)[reply]
is there something wrong in the way I've corresponded to scientists?
I've written to at least a dozen different researchers concerning various inquiries or leads, often asking them if they know any suitable colleagues if they're not suitable or too busy. I was wondering if there's something wrong in the way I craft my emails. Too direct? Not distinctive enough? Do they not take emails from rising third year undergrads seriously?
For example, yesterday I was supposed to get some algae samples from another researcher, along with their species names, to do some plasmodesmata / cytoplasmic channel experiments. So on Thursday afternoon I wrote something like this:
subj: Just a small inquiry =)
Hi,
I was wondering about news if the algae samples were ready yet; or just their biological classifications. Perhaps I could come over to your lab or office when they are ready?
Thanks so much!
--
John Riemann Soong Lüwen
Biochem, Cogsci UVA '12
The e-mail is extremely informal to the point of rudeness for people you don't know who are professionals, and it sounds like you are an undergrad who expects them to drop everything they are doing to interpret and act upon your e-mail, which you have spent very little time working on. You are writing to them as if they are another undergraduate; it's very inappropriate for an academic setting. Here is a more appropriate e-mail:
subj: Algae samples
Dear Dr. [Name],
I am a third-year undergraduate in the biochemistry program here at [wherever]. I recently heard that your algae samples had been prepared, though there was some ambiguity for me over whether the samples themselves were ready, or just their biological classifications. Can you confirm this for me? If they are ready for pickup, would it be possible for me to pick them up at some time that was convenient to you?
Thank you for your time,
John
--
John Riemann Soong Lüwen
Biochem, Cogsci UVA '12
Notice that I have written this as if it were from one professional to another, not a kid to another kid. Smiley faces, exclamation points, lack of a name or title -- these are not appropriate for professional correspondence with people you don't know fairly well. If you look like you just dashed off the e-mail without thinking about it, they are likely to ignore it without thinking about it. --Mr.98 (talk) 16:12, 16 July 2010 (UTC)[reply]
Professional communication - we have an article on everything. Bear in mind the difference between an inquiry to somebody you don't know; a technical report / technical request to somebody you work with; and an informal communication unrelated to work with your professional colleagues. Nimur (talk) 16:30, 16 July 2010 (UTC)[reply]
Whatever you do, don't use silly smilies when talking with "adults." Things like =) just say "this person does not take this seriously" to basically anyone older than 22, as far as I can tell. If your e-mail screams "I do not take this seriously," don't expect them to take it seriously, either. I will note, anecdotally, that this is something that many people of "current undergraduate age" seem to not understand. A lot of the older academics and so on blame it on the "kids" never learning how to write formal letters (which used to be taught about a million years ago) or being extremely used to e-mail as an informal means of communication, and not ever being taught how to modulate their formality according to circumstance. I don't know how much I buy the "these kids today" types of arguments, but there is probably some merit to it. You should generally err on the side of formality in situations where you need something from someone who has more stature than you (whether "stature" is measured by age, position, education, power, what have you). If you go too far into formality, they will say, "oh, just call me Bob," and you'll have some idea where you stand. But you won't go bad treating people with respect, as if your communication to them is important, and as if their time was valuable to you. You can go very wrong with being too informal—it is an insult and an irritation to have someone demand something of you without treating you with a modicum of respect, at least in the USA. --Mr.98 (talk) 17:50, 16 July 2010 (UTC)[reply]
Speaking as a nominal adult, I find this tragic and would much rather receive the first version with the silly smiley than the long-winded and stuffy second version, regardless of how important a person I might be. I wonder if maybe you are falling foul of heavily restrictive spam filters, the kind which put all emails in the trash if they don't come from a whitelist of addresses and domains. This has happened to me in the past when sending emails to a scientist friend at his lab address; took me a while of feeling snubbed before it became clear what was going on. 81.131.47.121 (talk) 19:30, 16 July 2010 (UTC)[reply]
I don't know about that. When emailing someone (as with any form of communication) you should use the appropriate "tone" (not sure if that's the right word.). If you were actually chatting to the guy, you wouldn't be the same way you are when you're chatting to your friend over a beer - why would you treat them the same over email? Zain Ebrahim (talk) 20:32, 16 July 2010 (UTC)[reply]
But if I did talk to him face-to-face in an informal manner, would be completely blank me and walk away? If so, well, he's a very special individual. 81.131.47.121 (talk) 20:53, 16 July 2010 (UTC)[reply]
He probably wouldn't completely blank you, but he might just say "Sorry, I'm busy at the moment. Please come back later." and then walk off. With email, there isn't the same assumption that you should get some kind of immediate response. If you don't want to respond straight away you can just ignore the email until you get around to dealing with it. If you talk to someone in person, social norms require them to respond immediately in some way. --Tango (talk) 21:09, 16 July 2010 (UTC)[reply]
Writing and face-to-face are very different forms of communication and have very different social norms attached to them. Additionally, academia is a place that is based on hierarchies, hierarchies which take a lot of time and effort to get to higher rungs of. It doesn't really matter whether one likes this or not — this is how it is, and if you want to communicate with academics, much less be one, you have to learn how to navigate the system on its own terms. There are some individual academics who obviously are different about such a thing, but you never err by being overly respectful. Personally I have found this to be true in general, 81.131's sentiments to the contrary. People like to be treated as if they are important, 99% of the time. They might not always dislike being treated as a friend or an equal, but it can be jarring and often inappropriate. (One always knows when a con is going down if you are on the street and someone you don't know walks up with a friendly face and says, "My man! How are you doin'! Let me talk to you for just a second...") --Mr.98 (talk) 21:55, 16 July 2010 (UTC)[reply]
But the algae samples ... you don't ignore the serious part of a message like that just because it began "Hi!" and you didn't like it. That would be extremely petty. Perhaps he is one of those people who is averse to emails of all kinds and functions by phone calls only. 81.131.47.112 (talk) 23:53, 16 July 2010 (UTC)[reply]
Even the serious part does not reflect seriousness. The entire e-mail stinks of informality. It does not give respect, and does not recognize that there is zero reason for this person to do what they are asking (they are not, for example, selling a service). If you are asking someone to do something for you that they do not need to do, you should be respectful. The e-mail for an academic would be perceived as rude and disrespectful. --Mr.98 (talk) 20:23, 17 July 2010 (UTC)[reply]
Keep in mind that among academic scientists you will encounter a relatively high proportion of people with sub-average communication skills. You might encounter those that don't seem to understand the subtext of something that is said. Just try to be professional and explain your self as well as you can. ike9898 (talk) 17:14, 16 July 2010 (UTC)[reply]
I don't think it has anything to do with that. If you were writing to academic historians you'd have the same (lack of) response if you sent that e-mail. It is just heavily outside the norms of communication that academics are used to in a professional setting, and it confirms any doubts they might have that undergraduates don't take them seriously. (And academics are a sensitive bunch.) --Mr.98 (talk) 17:56, 16 July 2010 (UTC)[reply]
Actually, in my experience, American academics still tend to go for commas much more often than colons, though the reverse might be the case overseas (foreign academics often communicate more formally in general). That's just my personal experience so take it with the appropriate grain of salt. Dragons flight (talk) 18:37, 16 July 2010 (UTC)[reply]
I don't know its ultimate origins, but the use of the colon is fairly common in business and legal correspondence. The comma is seen as less formal. Dragons flight (talk) 21:20, 16 July 2010 (UTC)[reply]
I don't think that kind of minor Miss Manners stuff is really what is at issue here. What matters is the overall tone and extremely colloquialisms (like smileys). Your academics in question probably don't know the Miss Manners stuff, but they do know when they are being talked to like a peer, which is inappropriate unless you have been invited to do so (either explicitly or implicitly). --Mr.98 (talk) 21:55, 16 July 2010 (UTC)[reply]
It's not really an issue of formality. You're asking somebody to take some trouble to help you, but you haven't put any effort into it, and you're not offering anything in return, not even gratitude. People are often willing to help when it is treated as a special favor, but nobody likes to be treated as though it's their job to help you. The same thing applies to people who answer questions on Wikipedia, by the way. Looie496 (talk) 23:17, 16 July 2010 (UTC)[reply]
You can also just pick up the phone and call the person who can help you. If you need to communicate some details via email, you can always do that after you've spoken to the person on the phone. Count Iblis (talk) 23:23, 16 July 2010 (UTC)[reply]
Formality aside, I would point out that even for informal communication 'just a small inquiry' is inherently a bad subject line. Just as with the RD or any forum you should generally aim for informative subjects lines in e-mails no matter who you're communicating with and how well you know them or how informal you're being Nil Einne (talk) 12:16, 17 July 2010 (UTC)[reply]
Well, it's worse than that really. To me, "just a small inquiry :-)" immediately translates as "you have promised me something and you haven't done it, so I am politely reminding you". It's informative, only in the wrong direction. Looie496 (talk) 16:50, 17 July 2010 (UTC)[reply]
"Regards," is a good way to sign off. In the place of "Yours truly," or "Thank you for your time," I like the simpler "Regards."Bus stop (talk) 12:57, 18 July 2010 (UTC)[reply]
replacing and changing cell media while under a microscope
I want to change the cell media of observed human cells on a microscope slide while still on the microscope )we want to track particles at the same time so we don't want to lose our positions too much).
Trying to insert even a tiny syringe needle underneath the slip lifts it. And its an inverted microscope, so this makes it even more difficult.
Does anyone know how I could drill a hole in the cover slip or the glass slide maybe? Or how to work with extremely narrow capillary tubes? (They are so thin they are like 100 microns thick.) I don't know how to draw or pump fluid up or down them. John Riemann Soong (talk) 16:03, 16 July 2010 (UTC)[reply]
You'll probably need some type of microscrope flow chamber, which are specially made to allow you to mount a coverslip with your cells and apply different solutions. Some of these set-ups get quite fancy, with multiple ports, stage heaters, etc. You can buy them commercially or DIY. --- Medical geneticist (talk) 16:26, 16 July 2010 (UTC)[reply]
Depending on what type of experiment you're doing (and your budget), you can readily purchase virtually any type of fluid-handling slide you might need. If you don't need a coverslip above the cells, then you can use a chambered coverslip product like these ones. It's a slide-sized piece of coverslip glass (#1 or #1.5) with plastic wells sealed to the top, and a removable plastic lid. They come in a number of chamber sizes, and you grow the cells in the chambers right on the coverslip glass. Since it's a coverslip on the bottom, you can observe the live cells at an inverted microscope while they're still bathed in medium. In a similar vein, this company sells small petri dishes (35 and 50 mm diameter) with a small circular hole cut in the bottom. The hole is sealed with a coverslip glued to the bottom of the plate; again, you can image living cells (and add and remove medium!) right at the inverted microscope. In a pinch (if your funding doesn't allow you to purchase these dishes) then it should be possible to construct workable substitutes using your own petri dishes, coverslips, and waterproof non-toxic adhesive.
Now, if you're doing some sort of more complex fluidics, or you need the liquid to be confined to a narrow space, then those chambers I've described won't work. I've seen premanufactured coverslips with all sorts of interesting fluidics on them, but my mind is blanking on the names of manufacturers. TenOfAllTrades(talk) 21:06, 16 July 2010 (UTC)[reply]
A friendly grad student drilled two small holes each, in several glass slides for me, that would fit within the cover slip. I might use them today and tell you guys how it goes. but thanks for all the links -- they are interesting should I ever proceed beyond hacks -- to something more intense for example. John Riemann Soong (talk) 16
21, 19 July 2010 (UTC)
DOLPHINS
How can dolphins dive so deep? Some dive even deeper than the photic zone and dolphins withstand all that pressure upon them. Why aren't people like them? Is their skin tougher or their body denser or what? I know dolphins are friendly and one of the most intelligent. I love dolphins!!!!!!!:)—Preceding unsigned comment added by Diver62 (talk • contribs) 16:37, 16 July 2010 (UTC)[reply]
It seems that with your overt obsession with dolphins :), you've overlooked that a number of organisms can dive much deeper and much longer -- such as the sperm whale. I'd suggest reading up on the sperm whale, as you might find more info relating to them on this topic, as it seems it's a much bigger deal regarding these organisms. DRosenbach(Talk | Contribs)16:43, 16 July 2010 (UTC)[reply]
Shame on you,DRosenbach. I know the sperm whale is a wonder, but i decided to ask about dolphins. Please answer my original question. You know, I love marine biology and cetolgy. that is everything in the sea.Diver62 (talk) 16:49, 16 July 2010 (UTC)[reply]
Shame on me?! What does that even mean? Being somehwhat similar creatures, it is exceedingly likely that whatever permits the sperm whale to accomplish such tasks similarly permit dolphins. Now cut being a clown. DRosenbach(Talk | Contribs)19:06, 16 July 2010 (UTC)[reply]
The deer in our back yard come out of the woods even in the day and eat up all the pansies outside the vegetable garden in the back. If you put human hair on the ground will they not come by or eat anything, or is that just an old wives tale?? Answer requested immediately?'Bold text'—Preceding unsigned comment added by Diver62 (talk • contribs) 16:46, 16 July 2010 (UTC)[reply]
No
This is not a science question, and the Reference Desk is not a chat room for opinions like this. --Sean17:00, 16 July 2010 (UTC)[reply]
I think the Science desk is as good a place as any for this question, as it deals with animal behavior. This site claims that the only guaranteed way to keep deer out is to build an 8 foot high (!) fence. It has other suggestions that sound like less work (although "get a dog" is actually probably more work). Comet Tuttle (talk) 17:43, 16 July 2010 (UTC)[reply]
The question I was responding to was "What is your opinion on police?", by the same user as this one, who later deleted part of that section. --Sean17:58, 16 July 2010 (UTC)[reply]
(It's really pointless to say things like "Answer requested immediately" and "PLEASE, I NEED AN ANSWER!!!!!!!!!!!!!!!!". This service is supported by volunteers - we answer when we have time, when we feel like it, when we have a good answer, when there's nothing good on TV, when the question is particularly interesting, whenever. Demanding answers on particular timescales or in particular ways (eg saying "Shame on you,DRosenbach" - when this was actually a highly relevant answer) just pisses people off and results in worse service - not better! You might also want to ration yourself to the number of questions you ask - you've been asking a lot recently, and that upsets people: particularly when the answer can easily be found with just a couple of minutes searching. Your questions below about sea snakes and jellyfish could easily have been answered just by typing those words into the Wikipedia search box and reading what comes up as a result. This service is really here for answering questions that are too difficult to answer that way - or which require tricky interpretation of hard-to-understand articles. Either way, being overly demanding and upsetting the volunteers never ends well!) SteveBaker (talk) 19:04, 16 July 2010 (UTC)[reply]
Cactus
How long does it take for a cactus to mature? I know some of them can live 300 years. I wondered since i have a cactus garden!!Diver62 (talk) 17:23, 16 July 2010 (UTC)[reply]
Wow! Does cactus still look the same even when its dead? because i think part of my cactus is dead, but it looks alive.Diver62 (talk) 18:21, 16 July 2010 (UTC)[reply]
It depends on what type of cactus. Green ones will generally turn brown. The more succulent the cactus, the more obvious it will be when it loses moisture. -- kainaw™18:30, 16 July 2010 (UTC)[reply]
it is green on the top of the plant, and brown on the bottom! it gets fertilized once a month in the summer, and water once a month the rest of the year. Help!Diver62 (talk) 18:33, 16 July 2010 (UTC)[reply]
That's not a good sign. I had a cactus that died on the bottom, but the top stayed alive for a very long time. The roots were dead and it fell out of the soil, but it stayed green on top for quite a while (since they can live without water for a long time). Are you sure water once a month is the right plan for them? You should check. Ariel. (talk) 23:24, 16 July 2010 (UTC)[reply]
I have a minor molecular biology dilemma. I've created a mutant construct based on the HPV type 16 genome with specific point mutations (two silent mutations that create restriction sites, and a non-sense+frameshift in the L1 major capsid open reading frame that renders the virus non-infectious). Here's the problem: what do I name this thing? I can't seem to find any documented nomenclature for DNA constructs that are minor modifications of naturally existing episomes, so I figured I would try to tap the collective wiki-wisdom. – ClockworkSoul18:06, 16 July 2010 (UTC)[reply]
I don't think there is any specific nomenclature. An example that came to my mind was the "synthetic genome" that the J. Craig Venter Institute created (covered here). They named one of their genomes JCVI-1.0, so perhaps you should just name your construct with initials and a number? Something like HPV16-CwS1.0. For smaller constructs, most people try to make up a name that is short but includes some important information. Maybe you could convey that L1 is disrupted: HPV16-L1X. --- Medical geneticist (talk) 11:47, 17 July 2010 (UTC)[reply]
This site is semi-official, but doesn't even come close to your nomenclature problem. After all, "HPV type 16" is only a conventional name, not one that the powers-that-be have got around to approving. Physchim62(talk)15:39, 17 July 2010 (UTC)[reply]
Jelly fish are not active predators - they will sting anything that swims into their tendrils, but don't go seeking prey out. --Ludwigs218:38, 16 July 2010 (UTC)[reply]
i didn't know that.It isn't tendrils. That's reserved for plants. It's tentacles. what if everything avoids them and doesn't swim into their tentacles? Diver62 (talk) 18:44, 16 July 2010 (UTC)[reply]
Lacking either brain or central nervous systems, jellyfish don't "think". When their tentacles contact something, it acts by itself - the stinging cells (nematocysts) will automatically sting anything they touch - but they aren't "thinking" about it. Furthermore, not all jellyfish can sting. Many that can sting produce toxins that humans are completely immune to. On the other hand, some produce toxins so powerful that they can easily kill us. Our jellyfish article is really good - you should read it. SteveBaker (talk) 18:54, 16 July 2010 (UTC)[reply]
Box jellyfish and especially Irukandji jellyfish can be very dangerous. Their tenticles can activate venom that attacks every system in the body and even ruptures the blood cells it comes into contact with. Also, research shows that jellyfish do have "eyes" that can see, but no central nervous system to process the information. ~AH1(TCU)18:57, 16 July 2010 (UTC)[reply]
When I went on a tour of Boeing's Everett, Washington facility, the tour guide at one point mentioned that one warm and humid summer day before the ventilation system was installed, somehow enough heat and moisture rose to the top of the 11-story tall factory (which is many, many acres as well...I believe the tour guide also said you could fit all of Disneyland inside the building) that clouds formed and it actually rained inside the facility. Is this even possible, and if so, what goes into making the building create it's own weather system? I was under the impression that it took more depth to an atmosphere than that to create clouds/rain, but I could be mistaken. Ks0stm(T•C•G)18:58, 16 July 2010 (UTC)[reply]
It has been reported that NASA's Vehicle Assembly Building (originally called the "Vertical Assembly Building") is tall enough to develop internal weather, as you will see at that article. But the Boeing Everett Factory, although huge, is not so high, and they didn't say anything like that about it when I took the tour. I think you're right to be skeptical. --Anonymous, 19:29 UTC, July 16, 2010.
I could imagine that some activities created hot humid air that condensed on a colder roof. That could have an effect similar to rain but wouldn't involve any clouds. I could easily imagine something like that happening and then being exaggerated in the retelling over the years. It does seem unlikely that one would see clouds after only 11 stories. Dragons flight (talk) 19:52, 16 July 2010 (UTC)[reply]
It would merely require the right temperature, humidity and air movements, which might well arise in such an unusual structure. It's entirely possible to do this deliberately in even a small enclosed space: for example, at the interactive science centre INTECH I visited a few months ago an open-fronted cabinet no more than a couple of metres square and maybe three high with these parameters actively controlled is used to create a mini-cyclone made visible by a mini-cloud*. Ordinarily, of course, buildings are designed to requirements that, deliberately or as a by-product, preclude the necessary conditions, but with the VAB other requirements, particularly a very large and high open space, are overriding so it might just stray across the boundaries permitting them. Given NASA's scientific ethos, it would be regrettable if such a long-standing claim was baseless. I do however agree that a reliable source statement should be sought for citation. 87.81.230.195 (talk) 22:37, 16 July 2010 (UTC)[reply]
Warm, moist air entering a cold building could condense on the structure and then drip, possibly in large amounts. It wouldn't be rain, exactly, but its effects would be the same. Acroterion(talk)19:24, 17 July 2010 (UTC)[reply]
fundamental forces
i have read the most basic of the standard model. i understood it well. the only doubt i have is that why does the effect of all the fundamental forces decrease over distance if force carrying particles like photons are involved? someone please throw some light.
--Lightfreak (talk) 19:49, 16 July 2010 (UTC)[reply]
First of all, they don't all decrease over distance. Electromagnetism and gravity both decrease by an inverse square law. The strong force has constant strength at all distances, although it always cancels out over any distance larger than an atomic nucleus - if you have two strongly interacting particles a larger distance apart the potential energy is great enough that two more particles will be created inbetween them and they'll cancel out the force. The weak force does something odd that I don't really understand (see fundamental force for some details). The reason electromagnetism, when considered in terms of photons, decays over distance is because you can think of it like lots of photons being emitted in all directions at all times. The number of photons at each distance will be the same, but they'll be more spread out at greater distances. That's exactly what happens for electromagnetic radiation. For electric or magnetic forces it's a little different, since you are dealing with virtual photons, but the principle is the same. --Tango (talk) 21:17, 16 July 2010 (UTC)[reply]
I don't think that argument can be made to work. An expanding shell of W or Z bosons or pions would fall off as 1/r² in density for the same reason as light (conservation of energy), but the forces mediated by those bosons don't fall off as 1/r².
Mathematically, the electric potential satisfies the Laplace equation, ∇²Φ = 0, and the spherically symmetric static solutions to that in three dimensions look like Φ(r) ∝ 1/r. Taking the gradient of that gives a 1/r² central force. Massive fields instead satisfy ∇²Φ = m²Φ where m is a nonzero constant, and the solutions to that look like Φ(r) ∝ (1/r) e−mr (a Yukawa potential). Taking the gradient gives a central force that dies off like 1/r² for small r but exponentially for large r. The quantity (ħ/c)m has units of mass, and is called the mass of the field. That interpretation doesn't work classically because of the ħ in there, but the rest of what I just said does work classically. Classically m has length units and can be thought of as an intrinsic curvature of the field, kind of like the cosmological constant in general relativity. (I'm not sure how close that analogy is, but it's not too far.)
The Laplace equation can be interpreted as "conservation of field lines": field lines can only start or end on charges, so as you get farther from the charge they thin out like 1/r², and the field line density is proportional to the strength of the force. Probably that picture can be extended to massive fields somehow. But I'm not sure whether to count it as an "explanation". -- BenRG (talk) 00:54, 18 July 2010 (UTC)[reply]
shellac
I have a bathroom sink with a wood cabinet below it. I am not sure what type of wood it is. There are certain small sections where the stain has come off. Can I touch these up with shellac? I do not want to use petroleum based stain. Can the shellac be applied to these sections? I can only assume the existing stain is polyurethane. If the shellac gets on areas of existing stain, will the shellac adhere to the existing stain or will it not adhere?
I do not want to have to sand off any existing finish or use paint stripper. Will the shallac work? How long does shellac take to dry? —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 20:30, 16 July 2010 (UTC)[reply]
human body aging - what's happening when things begin to sag/stretch downwards?
A particularly old woman sat next to me on the bus yesterday who was not wearing a bra. She had the classic waistline breasts which had stretched and sagged over time far, far down her chest. Thinking about the internal anatomy of the breast, it occurred to me that this process was actually rather fascinating. How, exactly, does the body cope with this sort of thing? Clearly many things must get gradually longer over time, yes? Blood vessels, connective tissue, etc. Or are the cell counts remaining the same and the cells themselves actually lengthening? 61.189.63.171 (talk) 22:39, 16 July 2010 (UTC)[reply]
RoHS states in the criticism section Another criticism is that less than 4% of lead in landfills is due to electronic components or circuit boards, while approximately 36% is due to leaded glass in monitors and televisions (RoHS removed lead from most circuit boards but not leaded glass).
My question is - what are the comparitive dangers of lead solder (lead tin alloy), and leaded glass (lead oxide in silicate/lead silicate) - specifically in landfills or other waste disposal - or more specifically does leaded glass leach lead to any extent? (refs please if possible). Thank you.87.102.32.76 (talk) 00:02, 17 July 2010 (UTC)[reply]
Encasing in glass (vitrification) is one way of isolating hazardous materials from the environment. I wouldn't expect leaching of leaded glass to be a significant problem. --Carnildo (talk) 01:14, 17 July 2010 (UTC)[reply]
According to this link butterflies usually sleep in trees. And if memory serves me, butterflies don't really "sleep." They need sunlight to be active, and when there's a lack of sunlight, they go into a sort of resting state that's not exactly sleeping. They don't move around, but they can if they need to. The RaptorLet's talk/My mistakes; I mean, er, contributions01:41, 17 July 2010 (UTC)[reply]
Insects have a 24-hour rhythm of activity, see circadian rhythm. Specifically regarding sleep in insects: for bees, see this Nature paper. So bees clearly do sleep. I'd be surprised if lepidoptera don't. --Dr Dima (talk) 04:29, 17 July 2010 (UTC)[reply]
Moths in the daytime will probably be similar to butterflies at night. They just sit and rest. If you knock into them, they might fly for a little distance, but they land quickly and go back into their dormant stage. --Chemicalinterest (talk) 11:03, 17 July 2010 (UTC)[reply]
There is a very nice 1916 (!) paper by Rau and Rau, here, describing rest / sleep in insects. Very enjoyable to read, closer in style to J.-H. Fabre than to modern biology papers --Dr Dima (talk) 17:03, 17 July 2010 (UTC)[reply]
Getting peanut out of your body faster
I am mildly allergic to peanuts. If I eat them I don't swell up and die. But I do feel slightly out of breath and my joints ache (actually quite painful). Strangely, this only started about two years ago. Anyway, as you can imagine I do avoid peanuts. So I've been having my normal reaction to peanuts for the last few hours but I didn't eat any peanuts today. I was wondering what the hell was going on when I realized that maybe the fried chicken I had for dinner might have been fried in peanut oil. Sure enough, I looked up the restaurant online and, yup, peanut oil only. Anyway, I was wondering if there was anything I could do to make it get out of my body faster. Any suggestions? I've been drinking quite heavily (water that is).--162.83.139.249 (talk) 04:52, 17 July 2010 (UTC)[reply]
Yikes, we're just a bunch of semi-anonymous dopes with nothing better to do than answer questions from strangers. It sounds to me like you need some advice from an actual doctor who's examined you in person. If you're concerned about anaphylaxis, you should probably take your epi-pen and/or call 911/go to the hospital. Water wouldn't seem to be very helpful; oil and water don't mix, but don't take my word for it - ask the attending physician. Matt Deres (talk) 04:58, 17 July 2010 (UTC)[reply]
Nah, It'll pass in a few hours. Just really quite unpleasant. The worst part about it all is that I am in love with peanuts (mainly peanut butter). I used to eat PB&J sandwiches all the time. Maybe I developed the allergy from overexposure. Anyway, a really neat thing: I just read in Wikipedia's article on peanut allergy that they have developed peanut butter that has 100% of the allergen removed, though it isn't being marketed yet. I can't wait.--162.83.139.249 (talk) 05:03, 17 July 2010 (UTC)[reply]
I'm glad you're alright. If peas aren't a problem, you might want to see if your local grocer carries "pea butter". I've heard it's almost indistinguishable from peanut butter; you can even use it for making peanut butter cookies and the like. Matt Deres (talk) 16:35, 17 July 2010 (UTC)[reply]
Excuse me for ranting a bit, but this hits on one of my pet peeves. We don't give medical advice, but that doesn't mean we have to advise people to consult a doctor on every occasion. "Dear Wikipedians, I stubbed my toe and it hurts, what should I do?" "We can't give medical advice, consult a doctor." Nuts. It's sufficient to say that we don't give medical advice -- advising people to consult a doctor is in itself medical advice. And very often it's bad advice -- doctors are an extremely expensive resource, at least in the USA. And -- and -- okay, enough, sorry. Looie496 (talk) 19:31, 17 July 2010 (UTC)[reply]
We are actually supposed to say "If you are concerned about it - consult a doctor". Nobody who just stubbed their toe is still going to be complaining about it for long enough to ask for a diagnosis or treatment here on the Wikipedia ref desk. They will use several useful four letter words...hop around for a few minutes - and then recover completely - long before they can reach a keyboard. But if the pain has lasted long enough to ask a question here - perhaps they have actually broken a toe. We don't know that - we can't diagnose it - so we have to defer to a doctor. If someone asks about a stubbed toe and it's really broken - we absolutely shouldn't laugh it off and tell them not to worry or to take an asperin. So IF you are concerned about it - see a doctor (and if you aren't concerned about it and know it's so trivial that you don't need to see a doctor - then please stop wasting our time with stupid questions!) SteveBaker (talk) 15:27, 18 July 2010 (UTC)[reply]
It's not the health care system, it's the people, unfortunately. Even if you save a person's life that does not mean that the said person will not proceed to sue you for physical and/or emotional distress. Doctors are at least to some extent protected by the system, Wikipedians are not at all. BTW why are we even discussing this? This has no relation to the OP question whatsoever. --Dr Dima (talk) 22:04, 17 July 2010 (UTC)[reply]
Ignoring the asides, and regarding pea butter, yeah I've tried pea butter and the soy crap and many others. Yes you'll hear people say "it's almost like it; you can't tell the difference." Well let me tell you that it's not terrible but... not even close, not even in the same country of the same city of the same ballpark. It's about as close to real peanut butter as say, a tofu dog is compared to a Nathan's all beef hot dog, Armour domestic prosciutto is to Prosciutto de Parma; canned olives are to oil cured...--162.83.139.249 (talk) 01:53, 18 July 2010 (UTC)[reply]
Peppermint tea relaxes the spinchters and thus helps things remove more quickly from your rear end. By the way your diet sounds very unhealthy, I would never eat any of the things you favour. 92.24.178.184 (talk) 09:37, 18 July 2010 (UTC)[reply]
Almond butter is also out there - we had some in our kitchen at work. I can just about tell the difference between that and "JIF extra-crunchy" - but it's not more different than JIF than JIF is from (say) an up-market organic peanut butter. Since the difference is less than the difference between two different brands of peanut butter - that ought to be "good enough"...especially if you're going to despoil it with grape jelly (or ketchup...and don't say "yuck" until you've tried it!). SteveBaker (talk) 15:33, 18 July 2010 (UTC)[reply]
Trimming macaw toenails
Just been clipping my hyacinth macaw's toenails today. When you do it, you have to be careful not to knick the vein that runs all the way down the middle of the nail, apart from the last few mililmetres. What exactly is the purpose of this vein anyway? --95.148.107.17 (talk) 11:48, 17 July 2010 (UTC)[reply]
Your macaw's claws are not a solid keratin cone all the way through; they have a narrowing core of living tissue most of the way down, though it runs out before the extreme tip, from which the keratin grows, just as your own finger- and toe-nails grow from a nail bed of living tissue - human and other primates' nails are merely a specialized flattened form of claw. This living tissue needs a blood supply just like all such tissue. Apart from having a blood supply, this tissue will also have sensitive nerves (as you'll know if you've ever had a splinter under a nail), so cutting into this area may not only cause blood loss and damage that could result in future growth malformation of the claw, it will also hurt. 87.81.230.195 (talk) 16:35, 17 July 2010 (UTC)[reply]
Dementia.
Three years ago, my wife (now 64 years of age) was diagnosed as a Dementia patient. Her memory and motor co-ordination were affected. She now has no sense of balance and is confined to a wheel chair.Three months ago, she developed what I consider to be a unique problem. She constantly feels the urge to visit the toilet for a bowel movement. She has always been extremely regular, going to the toilet first thing in the morning, so that this latest development is extremely frustrating for both her and myself. To give some indication of the severity of the problem, I have been monitoring the number of times that I have to help her to the toilet on a daily basis. At present, the record stands at 51 times in a 24 hour period, with only one successful bowel movement. This has obviously affected our sleep pattern, so that we are now averaging a mere 3-4 hours sleep a night over the past two weeks.
I have used medication prescribed by my GP, neurologist and a psychiatrist, as I was informed that the problem was caused by a short-circuit in the brain. No medication has had the slightest positive effect.
I would like to know whether this problem has been encountered before and been successfully treated. If so, what medication or treatment was employed. —Preceding unsigned comment added by 196.30.31.182 (talk) 16:09, 17 July 2010 (UTC)[reply]
Given the OP is talking about such a serious problem and how past medication has failed, it's safe to assume that they have already spoken to a doctor. The best option is to continue seeing the doctor who has the best knowledge of your wife's case and talk about extending your current treatment arrangement or starting a new one. There's lots of information on the internet about dementia and it's treatment, but I must say that most forms of deteriorating dementia are not curable and are usually treated to sustain memory for as long as possible. I don't feel comfortable going into any more detail I'm afraid, so please go talk to your doctor. Regards, --—Cyclonenim | Chat 16:48, 17 July 2010 (UTC)[reply]
Besides, Draco, he wasn't even asking for medical advice, but medical information. Medicine is still a scientific topic that can be discussed. Even if the question is anecdotally phrased. —Preceding unsigned comment added by 92.19.107.38 (talk) 20:24, 17 July 2010 (UTC)[reply]
But it's so confusing with all the different prefixes and stuff. And the units are different magnitude than the regular units. 1 m isn't even close to 1 ft. --138.110.206.102 (talk) 17:22, 17 July 2010 (UTC)[reply]
Metric system units are easier to remember, as for example one metre is 100 centimetres, one tonne is 1,000 kg, and so on. It's also much easier to calculate than Imperial units, as it's difficult to remember how many feet there are in a mile but not so difficult to memorize the number of metres in a kilometre (1,000). ~AH1(TCU)17:27, 17 July 2010 (UTC)[reply]
Yes, but that's not easier to remember than the metric units. All names within this system are based on the main unit, and are in base ten. For example, there's nanometre, mircron (or "micrometre", that's an exception), millimetre, centimetre, decimetre, decametre, kilometre, etc. In Imperial, you have to remember the number of fluid ounces in a pint, pints in a quart, quarts in a gallon, and so on. You don't have to remember these confusing conversions in metric. Instead of using actual full names, all you really have to remember in a series of metric units is one name, and the prefixes. ~AH1(TCU)17:38, 17 July 2010 (UTC)[reply]
You may be able to remember how many feet there are in a mile, but many people can't. Without looking it up, can you recall the conversion factor between fl. oz. and cubic in., both of which are units of volume? If you made a calculation and the result came out to be 1,023,514 in., would you be able to convert it to miles (a more familiar unit for lengths of that magnitude) in your head? Do you remember the conversion factor between avoirdupois oz. and troy oz.? With the metric system, there are many fewer redundant units for the same types of quantities, and the system of prefixes is uniform for all types of units. --173.49.11.154 (talk) 18:17, 17 July 2010 (UTC)[reply]
(ec)It's interesting that you say "1 m not close to 1 ft"--somehow you've chosen the foot as the standard, and you have to memorize arbitrary conversion factors from it to everything else (12 inches, 1/5280th mile, 1/3th yard). And a whole different set of conversion factors for other types of measurements (for pounds, 16 ounces and 1/2000th ton). And another set for volume (quick! how many drams in a gallon?). With metric, it's the same conversions for everything...less to know. And doing powes-of-ten conversions is easy because it matches our whole numbering system (just shift the decimal point) rather than multiplying or dividing by "less round" values.
OTOH, the whole idea of a "comfortable/recognizeable" unit is important when you're trying to use both--you just chose the wrong correspondence. A meter is about a yard (so a meter is 3 feet, rather than a 1:1 for your natural base unit, and an inch is 2.5 cm). A liter is about a quart (so a gallon is 4 liters). A kilogram is about 2 pounds. DMacks (talk) 18:24, 17 July 2010 (UTC)[reply]
The metric system is an international decimalised system of measurement used by most of the world except only Burma, Liberia, and the United States. Did you read the article Metric system ? Cuddlyable3 (talk) 18:35, 17 July 2010 (UTC)[reply]
However, 1 metre is approx. 1.1 yards (or 1yard and 3⅓inch). If you are used to the metric system then the US customary system and the British Imperial system (they are slightly different) are inconsistent and awkward to use. Now let me see. There are 12 inches to the foot, 3 feet to yard, 2 yards to the fathom, 110 fathoms to the furlong, 8 furlongs to the mile. There are 16 ounces to the pound, 14 pounds to the stone, 8 stones to the hundredweight, 20 hundredweight to the ton. There are 1000 millimetres to the metre, 1000 metres to the kilometre. There are 1000g to the kilogram, 1000kilogram to the metric ton. Now which is simpler? CS Miller (talk) 20:09, 17 July 2010 (UTC)[reply]
Out of the units you mentioned, the only ones that are commonly used are inches, feet, yards (in football), and miles for length and ounces, pounds, and tons for weight. Fathoms, furlongs, stones, and hundredweights are only used very rarely. --138.110.206.102 (talk) 21:21, 17 July 2010 (UTC)[reply]
Oh - but it's much worse than that. Csmiller says that there are 14lbs to the stone and 8 stones to the hundredweight. That means that there are 112 lbs in a hundredweight...but hold on...aren't there 100 lbs in a hundredweight? Well - it depends which side of the atlantic you happen to live on - it's 112lbs in the UK and 100lbs in the US.
There was a time when that didn't matter much unless you were shipping stuff from the US to the UK or vice-versa. But in this era of universal communications where we don't even know that Csmiller is a Brit (I presume), we can easily be talking at cross-purposes. If someone asks "How many pounds are there in a hundredweight", the answer is quite complicated.
Then 138.110.206.102 comes along and tells us that the imperial system isn't so complicated because such-and-such units are not used anymore because (presumably) (s)he is an American - and is unaware that many British people still very commonly use the 'stone' when talking about human bodyweight and hardly use the gallon much at all anymore when it's really common in the US.
This "imperial system of measurements" that everyone is talking about isn't any kind of standard at all - it's a complete mess that causes immense amounts of confusion when used on the Internet where people are too stupid to realize that when an American says "My car does 35 miles per gallon" that a Brit is likely to think "Well, that's not so terrible - I thought Americans all drove gas-guzzlers"...but that's because a car that does 35 miles per UK gallon would be doing an impressive 42 miles per US gallon because US gallons are much smaller. A 35mpg car in the US is really a gas-guzzling 29mpg car in the UK.
As a final note: My wife was a nurse in the UK and France - where drug dosages are measured in grams (g). When she studied to get her license to practice in the US, she was horrified to discover that over here, drugs are measured in 'grains' - and also use the abbreviation 'g'!!! When US drug companies ship overseas, they are required (of course) to label them in grams ('g'). When drugs are imported from overseas, they have to be re-labelled because of that, but the standard for doing that is change the abbreviation for 'grams' to 'gr' so as not to confuse medical people who are used to using grains! Now - how many people in the US buy cheap drugs over the Internet from Canada, Mexico and elsewhere? It would be really interesting to discover how many people have died because of that incredible piece of stupidity! SteveBaker (talk) 14:44, 18 July 2010 (UTC)[reply]
Wow, what a mess! Before I read this I've always thought that when dealing with mass measurements, "gr" was ambiguously the abbreviation of "grain" and that "g" could always be unambiguously interpreted as "gram". I, too, now wonder how many people have been killed by that confusion! --173.49.11.154 (talk) 16:15, 18 July 2010 (UTC)[reply]
As it happens, most tablets are marked in milligrams (mg) - even if the amount is 1000mg (ie, one gram). Since people don't mark things in 'milligrains' - this doubtless lessens the confusion. However, liquid drugs (where the quantities involved are much larger) do still have this confusion. But they don't label tablets with 'mgr' - so who knows what horrible messes are still possible! SteveBaker (talk) 16:49, 18 July 2010 (UTC)[reply]
Yes, I was using the UK system, not the US system. BTW, yards are still used in the UK. Normally in sports - pitch lengths and golf green lengths, and road distances under about 1/4 mile. CS Miller (talk) 22:28, 18 July 2010 (UTC)[reply]
My original point with that list is that there is with the traditional systems no way of inferring how to go from one unit, say 'foo', to the next unit up, 'baz', without consulting a reference book, or remembering the conversion factor. With the metric system there is one base unit of measurement for any quantity, say 'foo'. With the metric system I know that, without knowing what a 'foo' measures, that 1000 milli-foo will be 1 foo, and that 1000 foo is 1 kilo-foo. CS Miller (talk) 22:53, 18 July 2010 (UTC)[reply]
The idea behind the metric system was, as Looie points out, twofold. First was to develop a universal standard, so that the US and the UK and France and Japan all knew that if you said something was a given length or weight, it was. This is in contrast to systems that were sometimes quite localized, and a "pound" or a "foot" could mean different things in different places. Second was to develop a system that was decimalized, because it is easier to do many calculations with decimalized systems than non-decimalized. 12 inches to a foot, three feet to a yard, dividing inches into 1/16ths, 5280 feet to a mile... this is a pain, quite arbitrary, and makes it hard to covert between units (how many 1/16ths of an inch are there in a mile? Not the easiest calculation to do in your head). Decimalization lets you just change prefixes and do things in orders of 10. That's pretty easy to do. As for what feels "intuitive" to you—it's entirely what you grow accustomed to using. I find miles intuitive but that's just because I've grown accustomed to thinking in terms of them. It's entirely arbitrary. Which is not to say that in all fields decimalization is easier; in time, for example, there is a strong argument that decimalization doesn't actually save much effort on calculations, and in fact impedes certain types of calculations. --Mr.98 (talk) 20:20, 17 July 2010 (UTC)[reply]
Nobody seems to have mentioned that it incorporates (not by chance) conversion factors of 1. eg 1 cubic meter of water weighs 1 metric tonne, or 1 cubic centimetre of water weights 1 gram (ie based on water of density 1 unit). Extensions of the metric system ie SI units do similar things, Centigrade is based on the properties of pure water: melting and boiling point 100 divisions. Kelvins retain the same scale but are offset. also Move a force of 1 newton through 1 meter and you've done 1 joule of work. Compare with the various conversion factors for 1 footpound.87.102.32.76 (talk) 20:36, 17 July 2010 (UTC)[reply]
Indeed. Consider a dam, 100metres high, 1km wide, with a water-pool 10km long. It is 300 metres above sea-level. How much energy is stored in it? The answer is - the volume of water is 100m*1km*10km. That is 1 km3 or 1 million m3. 1m3 is one ton or 1000kg, so there is 109kg of water. Energy [ Joules ] = mass * gravity * height, or E = mgh. g is 9.83 m·s-2, which is normally approximated as 10. Therefore, there are 109 * 10 * 300 Joules, or 3 PetaJoules, or 833 million kWhr.
Consider a dam, 100 yards high, 1mile wide, with a water-pool 10 miles long. It is 300 yards above sea-level. How much energy is stored in it? The answer is the volume of water is 100yards * 1 mile * 10 miles. That is 3.1 billion cubic yards. 1 cubic yard of water weighs 1685.5 lb, so there is 5.2 trillion pounds. E (BTU) = m (pounds) * g * h (yards), where g = 0.003855 BTU/yard/foot. So E = 5.2 trillion * 0.003855 * 300, or 6 trillion BTU.
This point is often overstated. Yes, the nice value for the density of water under standard conditions is a timesaver when doing mental arithmetic (mental arithmetic specifically; it hardly matters to a computer) on problems that involve water.
But while water is pretty important, it's not the only substance we want to know about. Suppose you want to estimate how fast air pressure goes down with increasing elevation? The density of water won't help you at all; you need to memorize something if you're going to do it in your head. (What I remember is the volume of one mole of an ideal gas at standard temperature and pressure; 22.4 liters).
Similarly, sure, the conversion factor between meters and kilometers is easier to do mental arithmetic with than the one between feet and miles. But if you're doing anything more complicated than just multiplying or squaring them (say, if you want to know the surface area of a sphere rather than the volume of a cube) there's a good chance you're going to be reaching for the calculator anyway. Summary — sure, it's true that certain common calculations are easier to do in your head in the metric system, but this was more important when more of them had to be done in our heads. --Trovatore (talk) 21:54, 17 July 2010 (UTC)[reply]
Okay, okay. So the metric system makes immeasurable (he-he) sense. No wonder then that the US and UK are reluctant. hydnjo (talk) 20:52, 17 July 2010 (UTC)[reply]
We use pints for milk and beer (they aren't the same size as US pints, though) and feet for the height of people (and stone and pounds for the weight of people, never just pounds like in the US). I've never seen someone use BTU. Yards are used for some things (the signs warning you of an approaching junction on a motorway are 100, 200 and 300 yards from the junction, for example), but they are pretty rare. Miles are used for large distances, especially on roads. The size of anything being sold will always have the metric equivalent on the label, under EU law. --Tango (talk) 23:05, 17 July 2010 (UTC)[reply]
Well, it is not uncommon for people to use non-metric system units even in countries that have a metric system tradition. For instance, in Brazil it is common to use cups, tea spoons and table spoons for culinary situations. The point is that the metric system is used in the UK and people there don't find themselves confused about how big a metre is. Dauto (talk) 23:10, 17 July 2010 (UTC)[reply]
I find it amusing that there are people who defend imperial units with almost religious fervor.. "I'll give you my inches when you pry them from my cold dead hand!". lol Vespine (talk) 23:50, 17 July 2010 (UTC)[reply]
Indeed. What I find most ironic is that those same people are likely the ones who would roll their eyes when hearing a Brit describe the old pound system ("12 pence to a shilling, twenty shillings to a pound... that's nuts! How do they ever make change?") Matt Deres (talk) 03:24, 18 July 2010 (UTC)[reply]
Actually (although I'm first to defend the switch to metric currency), there were aspects of the old system that made sense. With 240 pennies in a pound, you could easily and exactly have 1/2, 1/3rd, 1/4th, 1/5th. 1/6th, 1/8th, 1/10th, 1/12th, 1/16th. 1/20th, 1/24th, 1/30th, 1/50th, 1/60th, 1/80th, 1/120th and 1/240th of a pound. With 100 pennies in a pound (or cents a dollar), you only have 1/2, 1/4th, 1/5th, 1/10th, 1/20th, 1/25th, 1/50th and 1/100th. In an era before calculators, this was a useful thing. SteveBaker (talk) 04:35, 18 July 2010 (UTC)[reply]
Consistency: If I mention a unit you don't know (maybe a 'Henry' - the SI unit of inductance) - you still immediately know that 1000 millihenry is 1 henry, and you'd expect that in the equation for inductance (which involves volts, amps and seconds) that there wouldn't be any funny constants in there (1 henry is one volt times one second divided by one amp). But in non-metric units, you have no idea how many ounces there are in a hundredweight unless you also know how many pounds there are in a hundredweight and how many ounces in a pound. You know that the imperial unit of 'power' is the horsepower, and that power is energy divided by time...but you can't take imperial units of energy (btu's) and imperial units of time (seconds) and immediately know how many btu's per second makes a horsepower. But with metric units, you know that a watt is one joule per second.
Memorable Ratios: With imperial you have to memorize an immense number of arbitary names and conversion factors - with metric, there are base units and multipliers and they are all simply related by powers of 10 or 1000. Do you know the number of millibars in a psi?
Abbreviations: The SI units have standard abbreviations (m,g,s etc) that are completely unambiguous and uniform across all different languages - where in imperial units, there are all sorts of confusing collisions - and 'pound' in English abbreviated 'lb' - but is 'livre' in France and abbreviated 'l'. Within the US alone, 'mi', 'ml', 'm' and 'M' are all used as abbreviations for 'mile'. But no matter where you go in the world, a kilometer is always 'km'.
Standardization: All SI users agree on how big a meter a kilogram and a second are. But in imperial, there are lots of different miles, tons, hundredweights, ounces, pints and gallons. If I tell you that my car does 35 miles per gallon - you can't tell what that means without first asking whether I'm talking US gallons or UK gallons.
Comprehensiveness: There are no imperial units for oddball things like inductance. The Henry is defined by the kilogram, meter and second...but there is no unit of inductance that's specified in terms of pound, foot and second. This is also true for volts, ohms, amps and watts. All electrical units that are used in the imperial-unit world are metric.
Lack of ambiguity: If I tell you that one person measured the pressure in a vessel as 1at - and someone else measured it at 0.96784atm, you could easily assume that the pressure had changed between those two measurements - but an 'at' is a 'technical atmosphere' and an 'atm' is an 'atmosphere' - they are different units for pressure - both present in the imperial system. But 10Pa is 10 pascals...no matter what. Since there are no other units of pressure, it's utterly unambiguous and (so long as you've learned the system), incapable of confusion.
Rigor: There is confusion in the imperial system between 'pound' and 'pound-force' - and between 'ounce' and 'fluid ounce' and (most egregious) between 'calorie' and 'Calorie'. In the super-formal SI system, kilograms and newtons are clearly different units - and kilogram and liter are also cleanly distinguished and 'cal' and 'kcal' are hard to confuse.
Steve makes an excellent case for the superiority of SI units, but I'm still happy to use my Imperial units here in the UK alongside and in preference to the imposed metric system (with which I am also conversant). Perhaps I'm a dinosaur, but my species hasn't died out yet. Dbfirs09:24, 18 July 2010 (UTC)[reply]
Imperial units are also imposed on people in many situations. For example, in the UK, street signs are still marked in miles and miles-per-hour because the cost to replace all of those millions of signs (and to do it all on the same day!) would be immense. Also, if you are an aircraft pilot - even in a country that is 100% switched over to the metric system - you are forced to think of aircraft altitudes in feet because that's the international standard and aircraft altimeters have a scale that shows thousands of feet with no metric equivalent. Ships are a similar deal - with speeds almost always being measured in nautical miles per hour (knots) instead of km/hr. A nautical mile is one arc-second in latitude - so if you are figuring out your latitude in degrees, then - in an age before calculators - it was simplest to use nautical miles - and hence, knots for speed. The cost and effort of converting aircraft over to the metric system would be spectacularly high right now - with minimal benefits. However, as aircraft transition from mechanical/pneumatic instruments over to computer screens - and paper charts are replaced by GPS, the cost of transitioning will decline sharply. However, it would still require international agreement and that would be virtually impossible to obtain. This kind of 'lock-in' effect makes a complete transition to the metric system almost impossible in countries that have not already been using it for a couple of hundred years.
I just have to respond to some nonsense there. Road signs won't all be changed on the same day. Signs with both units are installed over a longer period, then gradually replaced with simply metric signs as needed after the change. Every major nation involved in aviation is already metric except the USA. Why would the USA make it impossible to obtain agreement? Australia and Canada made total transitions from Imperial to metric in the latter half of the 20th century, so it can be done. HiLo48 (talk) 21:20, 18 July 2010 (UTC)[reply]
I don't think the cost is the main thing preventing changing to kilometres on UK roads. Bigger factors are: the public resistance to any kind of change, drivers not being familiar with the new units and the change it would require to speed limits (you could put up signs saying 48.3 km/h, but it would be pretty silly. More likely would be increasing the speed limit to 50 km/h, which will result in protests from people concerned about road safety. The alternative is reducing it to 45 km/h, which would result in protests from people that think it's just a way of getting more money from speeding fines). --Tango (talk) 15:41, 18 July 2010 (UTC)[reply]
I somewhat object to US customary units being referred to as Imperial. Going "meta" for a moment, I have to wonder why it is that refdesk discussions so often seem to be Brits discussing amongst themselves. There are many many fewer British citizens than Americans, but somehow there seem to be more of them represented on the refdesk (and perhaps as WP editors in general). Is there something about the endeavor that specifically appeals to the British character? --Trovatore (talk) 20:08, 18 July 2010 (UTC)[reply]
Imperial units are the non-metric units used in the (former) British Empire. US customary units are the non-metric units used in the US. They are different units and it is completely wrong to use one name to refer to the other set of units. As for Brits being overrepresented on the ref desks: I believe we are overrepresented on Wikipedia in general. I don't know why. --Tango (talk) 23:28, 18 July 2010 (UTC)[reply]
How portions of the brain are identified
In the left hemisphere of the brain are located Broca's and Wernicke's regions. Are the corresponding regions in the right hemisphere similarly named -- i.e. right hemisphere Broca's, etc. -- or are these right hemisphere regions referred to with specific designations. —Preceding unsigned comment added by 216.106.212.60 (talk) 19:53, 17 July 2010 (UTC)[reply]
My understanding is that usually only the regions in the hemisphere that is dominant for language (Usually, but not always, the right) are referred to as Broca's area and Wernicke's area -- our article on Wernicke's area seems to confirm this. I suspect that if you were to look through the literature, you'd find some inconsistencies, though. Looie496 (talk) 01:13, 18 July 2010 (UTC)[reply]
They are almost always in the left hemisphere in right-handed people. In people who are left-handed, they can be on either side, or you can even get mixed dominance in rare cases. Looie496 (talk) 02:18, 18 July 2010 (UTC)[reply]
Fast neutron reactor meltdowns
One can endlessly find statements that reactors cannot detonate "like nuclear bombs", because they use slow-neutron chain reactions, and for a weapon-sized explosion you need a fast-neutron chain reaction. With a slow-neutron reactor, the worst you can get is fuel that heats to the point of melting (meltdown), or in some scenarios the production of flammable hydrogen gas (which, if ignited, could cause trouble).
My question is whether fast neutron reactors would act differently in this regard, in terms of becoming supercritical with a fast neutron chain reaction. Obviously the lack of material and tamping, etc., is not going to get you kiloton-range nuclear reaction even in the worst case scenario. But could you get 10-100 ton TNT equivalent from a fast neutron chain reaction in a reactor that had, say, 20%-90% enriched U-235?
My gut feeling is "no", because the assembly time would be too slow even if there was enough material, but I don't really know how low of a fizzle it would be. If the goal is only 10-100 tons of TNT equivalent, that doesn't require exactly perfect conditions.
See: Delayed neutron, and also this section, in particular: "Thermal expansion of the fuel itself at increased power can provide quick negative feedback." Basically if it started to heat up it would shut itself down. Ariel. (talk) 05:01, 18 July 2010 (UTC)[reply]
I'm not sure I buy that? I mean there are a lot of conditions where it is imaginable that the increased heat would not necessarily cause the fuel to move apart. And if the supercriticality happened too quickly (e.g. all control rods immediately removed, or some kind of reflector was put into place), it would still be a fizzle, which could be quite a large boom (in human terms), yes? --Mr.98 (talk) 18:05, 18 July 2010 (UTC)[reply]
I am not familiar with the fast neutron reactor type, but your typical nuclear fuel rod is only enriched to around 5-10% U235, not 20-90%. Is that highly enriched fuel something specific to a fast neutron reactor? Googlemeister (talk) 13:13, 19 July 2010 (UTC)[reply]
Animal Allergies
I was wondering, are there any records of animals having allergies to such things as dust, pollen or shed hair like some humans? And if so, how would this affect their behavior? I'm talking about allergies like hay fever, with symptoms like itchy eyes, runny noses and headaches. Are humans the only animals to have these problems? Thanks! Stripey the crab (talk) 23:04, 17 July 2010 (UTC)[reply]
Well this is just an anecdote but my friend had a beagle with really bad hay fever, she used to have to give it antihistamines every day or else it's eyes would get all sore and weepy. I can't see why allergies would be a purely "human" condition. Vespine (talk) 23:33, 17 July 2010 (UTC)[reply]
The mechanisms underlying allergies are universal across animals (or at least vertebrates; not sure about others). But allergies happen when the mechanism is hyperactive. There's a fine line: the weaker the response, the higher the susceptibility to infection; the stronger the response, the higher the incidence of allergy. Different species face different infection risks and therefore have different levels of immune response. Just about any animal will show an allergic response if you provoke it strongly enough, though -- for example by injecting some sort of foreign protein into its bloodstream. Looie496 (talk) 02:25, 18 July 2010 (UTC)[reply]
My dog was at one point referred to a dog allergist by our vet. On the other hand I'm not fully convinced it wasn't an elaborate scam. Rckrone (talk) 16:49, 18 July 2010 (UTC)[reply]
Assuming that allergies are mostly caused by the lack of exposure to stuff in childhood thanks to sterilized environments...animals eat dirt and chew on dead animals. Might not be as big a problem with them....right? --mboverload@23:13, 18 July 2010 (UTC)[reply]
Distortion is measured in total harmonic distortion, that article says anything below 1% is considered "High Fidelity" so depends what you mean by "typical". THD is calculated based on a standardized test which does not consider frequency however I do believe the frequency would effect distortion, especially if the sound falls out side the "sweet spot" in the speaker's frequency response. Vespine (talk) 23:43, 17 July 2010 (UTC)[reply]
Essentially all loudspeakers produce more distortion than electronics, and 1–5% distortion is not unheard of at moderately loud listening levels. Human ears are less sensitive to distortion in the bass frequencies, and levels are usually expected to be under 10% at loud playback. Distortion which creates only even-order harmonics for a sine wave input is sometimes considered less bothersome than odd-order distortion. See the article Audio system measurements. Cuddlyable3 (talk) 11:15, 18 July 2010 (UTC)[reply]
July 18
Nasal passages
Hi. This is not a request for medical advice. Let's say a person suffers a broken nose, leading to a nosebleed. Might the damage cause parts of the brain to be accessible from the nasal passages? The person subsequently develops a common cold. Could sneezing or nose blowing (No article?!) cause parts of the brain to be liquefied and excreted via the nose, or could 'sniffling' result in nasal mucus entering the brain? I am aware of the danger triangle of the face, but this mostly applies to surface cutaneous infections. Might an infection in the nasal cavity, under these circumstances, spread to the brain? Thanks. ~AH1(TCU)02:04, 18 July 2010 (UTC)[reply]
The brain is encased in a tough leathery membrane called the dura mater, and there's a large area of sinuses between nose and brain -- also the front part of the brain lies almost entirely above the level of the nose, in fact above the eyes. To expose the brain by hitting the nose, you'd pretty much have to smash the whole face in. Looie496 (talk) 02:33, 18 July 2010 (UTC)[reply]
The danger triangle of the face relates to the very front of the face and relies heavily upon the anterior venous plexi (bilaterally) and ultimately the cavernous sinuses, bilaterally. Because maxillary posterior teeth exist inferior to the maxillary sinus, a spread of infection will either break into one of these sinuses, or more often, through the buccal plate of the alevolar ridge and into the soft tissue of the vestibule (area between teeth and cheek). Certainly, if an infection is allowed to remain untampered with for long enough, it can spread pretty much anywhere -- but there are also certain common pathways that are way more likely than others. Dental schools teach that abscesses of the maxillary anterior teeth (that would be incisors and canines) may lead to spread of infection into the danger triangle, but I'd say that even that is pretty uncommon. DRosenbach(Talk | Contribs)13:54, 18 July 2010 (UTC)[reply]
So there is no danger of the passage between the brain and nose being broken and punctured like the ancient Egyptians did to their mummies to remove their brains? ~AH1(TCU)14:53, 18 July 2010 (UTC)[reply]
If you follow the Egyptians and you're doing it to someone already dead? No. If they're still alive, I'm not sure but I wouldn't worry about it, I'd worry more about the danger of removing their brain...
AH1 -- the diagram above may not be the best to use to visualize the relationship of the nose to the brain. I added another that may better suit you. The "nose" is not really what or where it seems and the term may be confusing. The nostrils become the nasal cavity as they ascend and it is split in the midsagittal line by the nasal septum. There is certainly a possiblity of the nasal cavity communicating with not only the inside of the braincase but even of cerebrospinal fluid leaking out of both the ears and the nose after serious trauma like a motor vehicle accident. But it's way more unlikely for a communication to form between the two areas from a broken nose related to a trip and fall. Then there are all of the various levels of trauma in between, such as getting smacked in the face by a baseball bat in full swing, etc. So there's no real way to determine the odds of such a thing happening, but it's certainly possible, as it's listed in BLS texts as a sign of potential brain damage (that is, the leaking of CSF from the ears/nose). DRosenbach(Talk | Contribs)16:43, 18 July 2010 (UTC)[reply]
Reading anything about diseases and related stuff on Wikipedia makes it seem like everything is life-threatening and that we are in peril of dying from a number of problems every second. Scary. Rimush (talk) 17:15, 18 July 2010 (UTC)[reply]
Wikipedia does have an obsession over listing the most serious possible causes of any physical symptoms. ~AH1(TCU)23:59, 18 July 2010 (UTC)[reply]
Yes, I only meant to explain how difficult it would be for physical damage to the nose to get through to the brain, not to deny the possibility of interaction between sinuses and brain. As an additional note, there is a well-known case in the amnesia literature, of a patient called R.B. who had a fencing accident in which the point of the foil went up his nose and into his brain, causing damage localized to a small midbrain area which nevertheless produced a severe memory impairment. That's about the only way a blow to the nose can get through to the brain, as far as I can see -- short of a gunshot wound. Looie496 (talk) 17:34, 18 July 2010 (UTC)[reply]
A woman was killed in Italy by a pointy umbrella that went through her eye and into her brain (someone "stabbed" her on purpose). Rimush (talk) 18:17, 18 July 2010 (UTC)[reply]
Even without any mechanical trauma, an opening can spontaneously develop which allows cerebrospinal fluid to drain from the region outside the dura mater into the sinuses. I have known of such a case, which resulted in meningitis, and which was later closed by endoscopic microsurgery. Edison (talk) 18:48, 18 July 2010 (UTC)[reply]
Tippe top
http://www.xs4all.nl/~fabilsen/tippe-top.pdf
I had a question about the explanation given here. It says that L has a constant orientation, but if there's a torque due to friction, then wouldn't L change direction? The only thing I can think of is that the torque due to friction traces a cone during one revolution, so the net torque will just be in the (opposite) direction of L. Is this right? 74.15.137.192 (talk) 03:31, 18 July 2010 (UTC)[reply]
I'm not familiar with the 'tippe-top' - but I think it's a variant of something called "Tesla's Egg". We had a detailed discussion about that a few months ago Spinning Tesla egg and stability - which I think applies to the tippe-top also. As I explained at the time - you can get the exact same effect by spinning a regular hard-boiled egg. Our article: Tesla's Egg of Columbus refers to some very complicated experiment with coils and a copper egg that winds up with the egg standing up on it's tip - but all of that fancy stuff just gets the egg to spin - the standing up on one end part is nothing to do with that (which you can prove by doing the same thing with a tippe-top or a hard boiled egg). SteveBaker (talk) 13:44, 18 July 2010 (UTC)[reply]
Is this cable modem fried from lightning or not? (2 pictures, Cisco EPC2607)
Two pictures: With flash, without flash (click "Visa i full storlek" to show full size, which is blurry 5 MP).
It doesn't power up whatsoever. I can't check the transformer simply because the multimeter doesn't fit, and I can't try another transformer because the connector on the only other one I have won't fit into the modem (and also is 12V/1A when the modem wants 15V/1A).
Anyway... Is this the result of lightning or not? The connection went down at a time I was awake but still in bed, according to ping logs; local weather reports haven't reported any lightning nor have I heard any.
Oh, and the copper-colored spots in the pictures are a) located right around a ~5x5mm IC on the other side and b) extremely conductive. Also, everything on the other side looks brand-new - I haven't checked the two ICs that are on top in the pictures though; all three were shielded under metal casings, and I only removed the first (the one closest to the coax connector). -- Aeluwas (talk) 08:07, 18 July 2010 (UTC)[reply]
When lightning struck our network a few years ago, the router had a burn pattern like the twigs on a branch, so based on that I'd say no. --TammyMoet (talk) 08:16, 18 July 2010 (UTC)[reply]
Lightning can produce many different effects, but I agree with Tammy that component failure is a more likely cause. How far into the unit does your 15v supply reach, or is there no 15v coming in? Dbfirs09:06, 18 July 2010 (UTC)[reply]
Those copper area don't look broken to me, they seem deliberate. In any case by far the most common failure is a loose or cracked solder joint caused by motion (for example where you plug something in, or where there is a button, or where there is a wire going to the outside world), or less often by heat. If you can find it you should be able to resolder it. If it's a high power connector you will often see burn marks. But for a signal line you won't, and you'll have to look for a cracks. Ariel. (talk) 13:42, 18 July 2010 (UTC)[reply]
Thanks everyone. As it turns out, the modem might not be broken after all. The power supply, on the other hand, definitely is. Y'know, the thing that's supposed to supply 15 volts... I measured it to 0.01 V, which is way within the margin of error of a cheap multimeter, so it's rather a question whether it simply died, or died and took the modem with it (e.g. due to lightning). Since I'll be getting a new modem (of a different make and model) anyhow, it doesn't really matter; the main reason I asked was to see if those copper areas are normal or not (for future reference :). Judging by the above responses, how pristine everything else looks and the shapes of those areas (no burns or such in the corners, or what have you), I can only assume they're supposed to be there. -- Aeluwas (talk) 14:44, 18 July 2010 (UTC)[reply]
Those bare areas may have been deliberately left that way in order that they may radiate heat better. Since you said that the components on the other side had metal covers over them - that seems quite plausible. If the problem happened during a storm, it's possible that a power spike induced by the nearby lightning took out the power supply without anything actually getting struck or damaged. If your cable had been struck by lightning, there would be all sorts of other signs - scorch marks on the case, damage to the cable itself, etc. SteveBaker (talk) 15:13, 18 July 2010 (UTC)[reply]
High-friction coating for bike rims to improve braking efficiency?
I'm going to try new brake pads for my caliper brakes, but I wondered whether the rims (apparently steel rims are poor braking surfaces) could also be coated with something to increase the coefficient of friction, ideally without unduly wearing-out the brake pads or quickly being destroyed in use? ----SeansPotato Business11:24, 18 July 2010 (UTC)[reply]
Is this a pedal-powered bike or a motorbike? I'm guessing pedal-powered because of the rims. New brakes, or recently adjusted old brakes, will stop you very abruptly. This can be moderated by applying the brakes gently. High-friction rims would give you no choice in the matter, causing a stomach-wrenching halt every time, so I think it's a bad idea. 213.122.67.124 (talk) 12:14, 18 July 2010 (UTC)[reply]
Caliper breaks seems to indicate bicycle. It's probably possible to go with surface coating, but for modern (aluminium) rims and decent quality brake pads (I use CoolStop on my mountain bike with Shimano LX V Brakes, and Magura brake pads with the HS11 the on my commuting bike), there is no need. Both braking performance and brake pad lifetime are excellent in dry weather and plenty good enough if it rains. For more extreme needs, check out disk brakes. --Stephan Schulz (talk) 12:24, 18 July 2010 (UTC)[reply]
Steel rims are actually excellent. That's what cars use. For brakes you don't want too much sticktion - you want friction. It needs to be very smooth, and non sticky. Ariel. (talk) 13:46, 18 July 2010 (UTC)[reply]
Yes, exactly. You want to be able to use your brakes gradually to slow yourself down at a reasonable rate. Correctly set up bike brakes (even on a smooth steel rim) are more than able to throw you over the handlebars and/or lock up the wheels and put you into a skid. What you need is a controllable amount of friction that allows you to apply anything from the most gentle slowdown to a full-scale lock-up-the-wheels skid. Having an unnecessarily large amount of friction will make the bike harder to control because the slightest touch on the brakes could result in a skid or an over-the-handlebars event. Also (as Ariel points out), there is an important difference between 'sticktion' (static friction) and dynamic friction. If the material has a high coefficient of static friction then it's much easier to lock up the wheels. If all you needed for really good bike brakes was the maximum amount of friction - then you could just shove a stick between wheel spokes and frame! What you need is (a) good pads - which you must change when they wear down and (b) correct adjustment of the cable from the brake lever to the caliper so that the lever cannot be pulled all the way back to the end-stop, no matter how much force you apply. This second thing is the most common problem with bike brakes (especially the back ones) because the cables gradually stretch with use leading to a situation where the brakes would be perfectly able to stop you if only you could apply enough pressure to them without hitting the end-stop first. The back wheel brakes suffer the most from that because the cable is longer. SteveBaker (talk) 15:05, 18 July 2010 (UTC)[reply]
That's a little bit oversimplified. If you're riding downhill or at high speed, the main braking force should be applied to the rear wheel, to avoid flipping you over the front. In my experience, it's really hard to apply enough force to the rear brake to lock it up when you're going fast, even with new brakes. But I definitely agree that roughening the rim is a bad idea. If nothing else, it will grind away the rubber in the brake in no time. Looie496 (talk) 18:00, 18 July 2010 (UTC)[reply]
Well, no, I'm not so sure I agree about the rear-v-front thing. You have to keep the front braking light enough to avoid an endo, yes, that's true. But short of that, front braking pushes your front tire downwards into the roadway and improves your grip on the road. They tell me that the best balance is around 70-30 with the heavier braking in front.
Now I can't really claim experience on this, even though I bike a lot on hills, because I'm cautious and don't really let the bike get very close to losing traction (at least on the downhills). So if you have any pointers to studies on this, I'd be interested in seeing them. --Trovatore (talk) 21:19, 18 July 2010 (UTC)[reply]
The best thing to do would be to replace the rims with aluminium ones - an expensive proposition, but possibly worthwhile. Bicycling Science by D. G. Wilson quotes this paper from 1971: steel rims lost 90+% of braking power when wet. If your bike is anything like the ancient contraption I use at university, and you often ride in rain, I'd put serious thought into upgrading for safety reasons: if it rains during the course of a lecture, I have to use "sneaker brakes" on the way back. If your bike is newer, modern brake pads might have improved the situation, but it's up to you to judge. Brammers (talk/c) 20:48, 18 July 2010 (UTC)[reply]
Disc brakes — bikes
Why are the discs not a simple circular configuration? They follow a path that diverges from the plain circular form that one might expect. The divergence is regularly corrected, so that the overall configuration is circular. But why the periodic squiggles out of simple circularity? Click on the pic to enlarge it. It's a very nice photograph. Bus stop (talk) 15:25, 18 July 2010 (UTC)[reply]
Personally I think it's simply to make it look cool. Same for the holes. (If you are trying to save weight, there are better ways, like an internal grid, layered with thin smooth metal.) Ariel. (talk) 15:44, 18 July 2010 (UTC)[reply]
The holes do not dissipate heat. They put them in cars not to dissipate heat but to release outgassing from the pads. Ariel. (talk) 15:52, 18 July 2010 (UTC)[reply]
Is there a way to measure the room temperature / ambient temperature with an infrared thermometer? It seems that they must always measure the temperature of the surface of some object. --Yanwen (talk) 20:28, 18 July 2010 (UTC)[reply]
Infrared thermometer relies on the infrared being reflected back into the sensor, that's why you can't measure the actual temperature of the air, because it doesn't reflect. But depending on the situation, you can make some reasonable assumptions. In a room, most soft furnishings and other objects IN the room will be pretty close to the air temperature in the room. Stay away from windows and doors and anything that has been in or near direct sunlight.. Even if you can get just a piece of paper and let it rest in the room for a few minutes, I don't see why that wouldn't work.. Vespine (talk) 23:09, 18 July 2010 (UTC)[reply]
I'm afraid that is completely incorrect. It's not reflected IR that is used, it is emitted IR. It's the thermal radiation of the object (which, for objects at everyday temperatures, will be predominantly IR) that is being detected. Reflected light doesn't tell you anything about the temperature of the object, it just tells you about its colour and the colour of the light it is reflecting. The air does emit thermal radiation in exactly the same way as any other matter, however there really isn't very much air (about 1.2kg/m3, compared to around 1800kg/m3 for brick), which is why it doesn't emit a noticeable amount (this is also why the flame produced by complete combustion is almost invisible: red-hot air doesn't emit a significant amount of radiation, even though it is visible radiation, it is only when there are soot particles in the air that you get a visible flame, since the soot particles at the same temperature emit much more light, since there is much more matter there). --Tango (talk) 00:17, 19 July 2010 (UTC)[reply]
I admit you are right Tango however I don't think i'm "completely wrong". If anything i'm half wrong ;) . I'm wrong about how the IR thermometer worked, fair enough, but that's not even what the OP was actually asking, you didn't even address that. I think i still came to the right conclusions about that.. Vespine (talk) 01:21, 19 July 2010 (UTC)[reply]
Just to be clear, the little red light on the infrared thermometers is for targeting purposes only. The thermometer would work fine without it, but you wouldn't be able to accurately know what you were measuring the temperature of... Hense the little red laser to know where you are aiming. --Jayron3203:30, 19 July 2010 (UTC)[reply]
why is corn very small and scarce around the edges of corn fields?--Horseluv10 00:09, 19 July 2010 (UTC) —Preceding unsigned comment added by Horseluv10 (talk • contribs)
The use of fertilizer is sometimes by purpose lower at the edge to meet the law that a undisturbed rim has to grow around the fields.--Stone (talk) 04:58, 19 July 2010 (UTC)[reply]
i mean where it is intentionally planted.--Horseluv10 12:04, 19 July 2010 (UTC) —Preceding unsigned comment added by Horseluv10 (talk • contribs)
You can think of lots of reasons - that the farmer didn't fertilize the edges of the field as well as the center because of the need to turn the tractor around...or maybe there are trees around the edges of the field that are sucking up the ground water...or if the field is irrigated, that the irrigation system doesn't extend all the way to the edges...or maybe that insecticides aren't being sprayed out to the edges (again, for the tractor-turning-around reason). Perhaps the plants in the center of the field are better shielded from the wind than the ones that only have neighbors on one side. It's hard to know which of those things it might be. I couldn't find any online information about such a phenomena. SteveBaker (talk) 14:54, 19 July 2010 (UTC)[reply]
The phenomenon is observed in this paper, but sadly it's behind a paywall so I can read anything but the abstract. The Google description says "For all crops, crop height was significantly greater in the field centre than in the sprayed edges", although the paper refers to pesticides and herbicides rather than fertiliser. SteveBaker's ideas sound good though. Brammers (talk/c) 15:45, 19 July 2010 (UTC)[reply]
I was also thinking that if some kind of flying pest arrived at random in or around the field, all of the plants in the center of the field would have about an equal chance of getting infested - but if a pest arrived just outside the boundary of the field, it would presumably make its way to the plants at the outer edge. That would make any given plant at the edge of the field much more likely to get pest infestations than one in the main part of the field.
Also, some plants exude chemicals that supress plants from other species from growing nearby - and again, this would benefit the plants in the center of the field to a greater extent than the ones at the edge because the combined contributions of greater numbers of plants would build up a higher concentration of the chemical. SteveBaker (talk) 22:57, 19 July 2010 (UTC)[reply]
solar cells, photovoltaic, photosynthesis
I'd like some boffins to create a (short) entry that answers;
1. What are the best solar cells (for electricity) (then for heating).
1a. Explain why UV solar cells aren't worth producing. Doesn't the higher energy of UV make up for the lower frequency range (compared to visible light) [implied NOT in Solar Cell entry]
1b. Explain why IR solar cells aren't worth producing. Doesn't the much greater frequency range make up for the lower energy (compared to visible light) [also implied NOT in Solar Cell entry]
2. Why aren't countries - especially Japan and Australia - investing more in solar cell research than in oil exploration - when Australia has so much sun - and Japan is so dependent on oil, and so strong in technical stuff
3. Why can't plant photosynthesis be mimicked in an artificial photosynthesis, to produce a 100% efficient solar cell.
No, the tilde is in the upper left corner of my keyboard. It shows a key with ` and ~ in it. Shift that key and it should work. or click the signature with pen button on the top of the edit window. --Chemicalinterest (talk) 11:01, 19 July 2010 (UTC)[reply]
This looks a bit homeworky but anyway on "Why aren't countries investing more in solar cell research than in oil exploration" obvious reasons include (1) because you cannot be granted "concessions" for research into areas of intellectual property whereas you can for oil fields (2) because oil exists and technology to improve solar cells may not exist (3) because of these reasons the rates of return on investment are lower in solar technology than in oil exploration. --BozMotalk11:34, 19 July 2010 (UTC)[reply]
1: Best changes all the time, and by application, so just take a look at the solar cell article and this this image. For heating don't use any solar cell, use solar thermal.
1a, 1b: There isn't enough energy to make it worthwhile. The way it works is this: The higher the frequency you work with the more energy you gain from each photon - but this also means that all photons below the frequency are ignored, so you have less photons. If instead you use a lower frequency, you gain energy from more photons, but each photon gives you less energy, and the rest of the energy is wasted as heat. So there is a perfect frequency where multiplying energy*number of photons is maximized. (I could not immediately find what that number is for the sun.) There is also a Multijunction solar cell which layers the cells, each layer collects from a different frequency. But it's too expensive to be practical except is specialized applications.
2: I can't answer about countries, but solar cells are hard. We've been researching them for something like 40 years. There is another problem: Solar cells cost too much, and it's not just cost - there simply isn't enough rare earth elements on this earth for everyone to switch to solar cells. Unless someone comes up with a technology that uses more common elements solar cells will never be widespread for bulk power. Every time solar cells come out people make an estimate: Once oil goes up in price this much these cells will be cost effective, then you look at a graph of oil prices, predict when that will happen, and declare a date. But one thing is forgotten: When the price of oil goes up, the price of everything goes up right along with it - energy is the prime component of everything we build. If energy cost goes up the price of everything goes up - including those solar cells. So they never actually pass oil, they constantly stay tantalizingly just out of reach. Personally I do not favor photovoltaics for energy. I favor solar thermal. That we can build, and we can build it cheap. It's just not very exciting.
3: Why do you think plants are 100% efficient? They are not. According to the article on it (yes we have one) Photosynthetic efficiency is 11%. But anyway, why bother mimicking it?
In response to your second point, the prices have been declining for solar PV. A US government study found a decrease of an average 3.5% per year from 1998 to 2007. Mostly in non-panel costs[8]. Also solar PV replaces electricity, not oil unless you are one of the few using your panels to charge your electric car. Very little oil is used to produce electricity (except in a few island nations). Mostly it is a mix of coal, hydro, nuclear, and natural gas. Worldwide only about 6% of electricity is generated from oil but in the US and France for examples it is only around 2%[9]Rmhermen (talk) 16:50, 19 July 2010 (UTC)[reply]
In the future, but specifically handheld plasma weapons. It's obvious that vehicle-mounted plasma weapons will probably be developed somewhat soon. --138.110.206.101 (talk) 03:25, 19 July 2010 (UTC)[reply]
Do you mean a weapon that shoots a jet of plasma? That seems pretty impractical to me. The air would cool the jet very fast, limiting its range to less than ten feet. I don't think they will ever build one. --TheHighFinSpermWhale04:51, 19 July 2010 (UTC)[reply]
The laws of physics are the same at both sizes. If one is possible, then so is the other, it's just an engineering problem. I suspect neither is possible. What would prevent the jet of plasma from rapidly spreading out and cooling down? --Tango (talk) 13:49, 19 July 2010 (UTC)[reply]
I don't think it works that way. I think it will spread out at roughly the same angle regardless of the speed. --Tango (talk) 15:14, 19 July 2010 (UTC)[reply]
The flamethrower has largely been replaced by the shoulder-mounted rocket-launcher as a heavy infantry weapon. The rocket is considered more accurate, more effective, more humane, safer to operate, and suitable in a wider array of tactical conditions, including anti-personnel, anti-vehicle, and anti-bunker. It seems unlikely that a plasma weapon serve a significantly different tactical role than a flame-thrower, except that it would be harder to construct, more complicated, more expensive, and more susceptible to environmental conditions. As such, I would not bet money that any plasma-weapons are going to be in use in the near future. Most plasma physics research is more related to the effects of nuclear weapon detonation; occasionally, by bureaucratic accident, some of that plasma-physics budget trickles into a tactical research group; but that doesn't mean that there is either a practical use or a real need to develop such weapons. Nimur (talk) 16:32, 19 July 2010 (UTC)[reply]
It depends alot on what you mean by plasma weapon, according to our plasma weapon article, a plasma weapon is any device that uses plasma as a weapon so there are many different devices that could fall under the catagory of plasma weapon. The pulsed energy projectile uses a laser that ablates part of the targets creating a burst of plasma strong enough to knock a person over or even kill them. This is currently being tested by the military. However, for a device that shoots out a beam of plasma like a flame thrower, the plasma woul most likely disipate and cool to quickly to cause damage.--74.67.89.61 (talk) 23:53, 19 July 2010 (UTC)[reply]
Would plasma cause electrocution in addition to burns?
Plasma are locally neutral, so there wouldn't be any significant voltage differences over your body. But even a cold plasma could give a chemical-like burn via the free ions. --Tardis (talk) 04:09, 19 July 2010 (UTC)[reply]
The phrase "cold plasma" does not mean "plasma at room temperature". It is a measure of the average electron energy. It can only exist in vacuum conditions, or else recombination will neutralize the plasma. Bittencourt has a chapter on the cold plasma model: "This simple model encompasses only the equations of conservation of mass and of momentum." It says nothing about the thermodynamic temperature, nor the effects of sticking your hand into it. Again, for these cold-plasma considerations to be valid, it is almost always a requirement that the density are very low; e.g. such that the thermal velocities are much smaller than the electromagnetic wave speed (not the speed of light - the speed of the plasma oscillation). This is easier to accomplish by changing ionization rates and pressures than by changing the gas temperature. To address the original question: plasmas are often created by conditions (like highly ionizing incident electromagnetic radiation, and a sparse gas) that would be harmful to humans. With or without the ionization, those conditions would be harmful anyway. Direct effects attributable to the plasma would be enhanced chemical reactivity with the free radicals and ions. Everything else - the electromagnetic radiation, the temperature, the pressure, and so on - would be just as harmful as if there were no ionization present. Nimur (talk) 16:43, 19 July 2010 (UTC)[reply]
Most silver compounds (with the notable exception of the nitrate) are insoluble, so its likely that silver phosphate would be insoluble. If you have access to even a basic high school chemistry laboratory, they are usually stocked with both of those chemicals, so you could ask a teacher to do the experiment yourself. Silver phosphate undoubtedly exists, however not everything that exists merits a Wikipedia aticle. A compound that exists, but which has no practical applications would likely not merit one. --Jayron3204:34, 19 July 2010 (UTC)[reply]
I would think that it is needed. I read in a science kit that one way to test for the aqueous phosphate ion would be to add silver ion, which would precipitate yellow silver phosphate. --Chemicalinterest (talk) 10:55, 19 July 2010 (UTC)[reply]
What's the minimum air pressure required to carry sound at a detectable volume? Since outer space isn't a complete vacuum, would it be theoretically possible to create a microphone sensitive enough to pick up sound in space? NeonMerlin04:54, 19 July 2010 (UTC)[reply]
That's a very good question. Sound is a pressure and density wave. My first guess would be therefore that for the sound wave to propagate, you need the mean free path of the air molecule, with respect to collisions with other air molecules, to be much shorter than the sound-wave wavelength. The mean free path increases as density decreases, so the longer is the sound wavelength the lower is the lowest air density at which it would still propagate adequately. So I think the wavelength (that is, the frequency) may be more important than the sound volume. Of course, the higher is the sound volume at the source the farther is the distance at which the sound is still detectable; that is also true. --Dr Dima (talk) 05:26, 19 July 2010 (UTC)[reply]
According to our Interstellar_space article there are only "a few hydrogen atoms per cubic meter". Far too little for a physical wave to transfer between this. However, this fascinating article has more information - it looks like they have detected "sound" in space, but nothing you would ever be able to hear. You'll need to read it to understand [12] --mboverload@05:32, 19 July 2010 (UTC)[reply]
More than mean free distance, you'd also need there to be enough collisions between particles to propagate the sound over noise level. As particles spread out, the signal-to-noise ratio grows significantly worse until no meaningful information can be propagated via sound waves. --Jayron3205:44, 19 July 2010 (UTC)[reply]
Not quite what you asked, but density wave theory is relevant. It explains the formation and evolution of galactic spiral arms as a kind of sound wave propagating around the galaxy. The wave leads to episodes of local compression of the interstellar medium, which in turn triggers star formation and gives the appearance of concentrations of bright stars near and immediately after the compression maxima. This explains why the stars in these spiral bands don't actually move at the same apparent velocity as the spiral arms themselves, i.e. the individual stars in the arm that we observe today are only the current generation of stars created by a deeper process propagating through the interstellar medium. In this case the wavelength of the "sound" would be ~10-100 thousand light years. As Dima suggested above, if you make the wavelength long enough even the dilute medium of interstellar space can carry it. Of course, at this scale it isn't "sound" in any sense that humans would be able to directly measure or listen to. Dragons flight (talk) 07:04, 19 July 2010 (UTC)[reply]
So you're saying that in space, someone can hear you scream, if you scream at a low enough pitch and the other person's eardrums are really really big? --Trovatore (talk) 07:06, 19 July 2010 (UTC)[reply]
An analogy would be trying to transmit the details of a picture by a few bytes of information; the information is not enough to get the details. --Chemicalinterest (talk) 11:05, 19 July 2010 (UTC)[reply]
And since we were talking about plasmas above, here: magneto-acoustic waves. Plasmas, being electrically conductive and therefore responsive to electromagnetic effects, can sustain acoustic longitudinal compression waves at much lower density, because ions can "collide" (interact electromagnetically) at greater distance than a neutral atom (which must only interact electrostatically). Naturally, there is a difference between ordinary sound waves and these effects; and it would be hard to put a regular acoustic transducer microphone to pick up the pressure fronts; but these are definitely compression waves at much lower gas density than ordinary sound. They are observed experimentally, usually by deducing the effective gas density from electromagnetic/radio signatures, and exist in the earth's magnetosphere, on the sun, and in the solar wind. Nimur (talk) 16:53, 19 July 2010 (UTC)[reply]
Maps for streams
Where can I get maps for streams? I know Microsoft MapPoint, Google Maps, and Bing Maps do not like copying. Is there any other place to get maps? --Chemicalinterest (talk) 11:51, 19 July 2010 (UTC)[reply]
"...do not like copying." Copying to what end? Maps are basically always intended for use as maps; it's not a problem to print one off and use it as such. On the other hand, copying to resell is going to be breaking the copyright of virtually any map provider, not just online ones. Can you more clearly describe your purpose? — Lomn12:25, 19 July 2010 (UTC)[reply]
Is there a relationship between catnip exposure and increased REM sleep time in cats? Also, can anyone speculate as to what cats dream about? My cat refuses to respond to my questions but insists on being scratched behind the ears. Viriditas (talk) 12:07, 19 July 2010 (UTC)[reply]
I can't provide a source, but I do recall seeing a program on TV in Australia some time back in which a cat appeared to stalk prey while asleep. ("Asleep" as determined by measuring brainwave activity.) Presumably the cat was dreaming about stalking prey. Mitch Ames (talk) 13:46, 19 July 2010 (UTC)[reply]
I don't know about cats - but dogs certainly dream and I'm as sure as it's reasonably possible to be that they are dreaming of chasing and hunting and such. Dogs seem less able than humans to shut off the connection between brain and muscles when dreaming (Atony). Some people who suffer from Rapid eye movement behavior disorder have the same problem. In dogs, you can see their feet making small movements that start out sequenced alternately like they are walking, then switch to front-feet-together/back-feet-together like they are running. You can see their breathing speed up - sometimes you can hear tiny little barks. Then, suddenly you might see their jaws making little movements - one of my dogs would salivate at this point in the dream. It's hard to believe we aren't watching the dog dream of walking around in the park, seeing a squirrel, chasing it and probably catching and maybe eating it. If cats suffer the same lack of atonia that dogs do, then carefully watching your cat sleep might well give you some kind of insight as to what's going on in their furry little brains. SteveBaker (talk) 14:41, 19 July 2010 (UTC)[reply]
In my experience, cats do not engage in the same kind of thing, or at least don't do it as regularly. I've owned cats all my life and have only seen the occasional twitch or two - nothing like the drama Steve mentions above. Perhaps there's some kind of tie in to hunting styles; dogs chase down their prey, so it makes sense they dream about running. Perhaps my cat is dreaming intently about lying in ambush and I'm mistaken in thinking it's sleeping like a log (in much the same way my math teacher misinterpreted my attempts at afternoon meditation). Matt Deres (talk) 17:29, 19 July 2010 (UTC)[reply]
Yes, exactly. My experience is that cats just don't have REM as much as dogs. However, after leaving approximately 1 gram of dried, ground, organic catnip for my cat to play with every day for a month, I noticed that he began to have REM every day in the late evening, and I've never seen a cat do it that much, leading me to conclude that the catnip was influencing his dream state. His legs move as if he's running and jumping, his whiskers twitch like he's poking his face through a bush, etc. That's why I'm asking. Viriditas (talk) 18:27, 19 July 2010 (UTC)[reply]
Well, if you're going to dose your pet to the eyeballs with a strong (for a cat) hallucinogenic drug...you're bound to get some odd side-effects! What's strange about this is that in humans, the active ingredient in catnip is a mild sedative and an antispasmodic - which I'd naively imagine would help to dampen down atonia rather than enhance it...but then cats aren't humans...so all bets are off. SteveBaker (talk) 22:49, 19 July 2010 (UTC)[reply]
Apparently the main active ingredient in catnip, nepetalactone, or its metabolic byproduct nepetalic acid, is a mild sedative and hallucinogen. However I haven't been able to spot any studies that discuss its neural mechanism of action, so I don't think it is possible to say anything about its effects on REM sleep. Looie496 (talk) 23:23, 19 July 2010 (UTC)[reply]
Alcubierre drive
Would an Alcubierre drive require large quantities of some sort of chemical compound (like the dilithium used in Star Trek's warp drives)? --138.110.206.101 (talk) 12:52, 19 July 2010 (UTC)[reply]
I meant, is there a single specific substance would be required in large quantities, which would play a role in the future similar to dilithium in Star Trek? --138.110.206.101 (talk) 13:12, 19 July 2010 (UTC)[reply]
Indeed, although I would guess (and guessing is all we can really do) that if exotic matter is possible then it would need to be made synthetically, rather than mined. --Tango (talk) 21:57, 19 July 2010 (UTC)[reply]
Scientific name of Clown Dorid
Hi, I am attempting to find the scientific name of the Clown Dorid so that I can make a mention of the Clown Dorid name in the appropriate wikipedia article, or make a new article if this animal doesn't have a page already. I found this picture which is described as a Clown Dorid in Victoria, B.C., Canada. At wikipedia, the closest picture I can find is the Triopha catalinae (sea clown Triopha). But the pictures don't look exactly the same, and I kind of doubt it is the same animal. Can you help me figure this out? Thanks. Fallendarling (talk) 14:22, 19 July 2010 (UTC)[reply]
The instinct to scratch is very strong and spreads through all of the mammal and apparently into at least some fish. Conventional medical advice is always that you must not scratch. However, behavior which is very widely distributed in the animal kingdom normally has some survival benefit. I am surprised to find no postings on the survival benefit of scratching.
With skin parasites such as tics and fleas, I can see that scratching would be a benefit, in that it has a real chance of physically eliminating the parasite. I would also suggest that scratching can help with mosquito bites and poison ivy etc., because causing the lymph and blood to leak from the skin would help purge locally concentrated toxins.
Searching the web shows lots of references to scratching being an indication of parasite infection but does not suggest that scratching helps it. I found nothing on the concept of eliminating locally concentrated toxins, as I mention above.
The usual theory, as you say, is that the reflex to scratch is intended to remove insects. Scratching at other times is probably just the body making a mistake. Evolution doesn't result in optimal solutions, just "good enough" solutions. The harm from scratching when you don't have an insect on you is minimal, so the evolutionary pressure to develop more refined itch sensations is very small. --Tango (talk) 15:51, 19 July 2010 (UTC)[reply]
Yup, I'd go with "mistake" because other situations produce same/similar sensation to the presumed evolutionarily-good trigger. If it's really conserved mechanistically across species, then it's gotta be something low-level like a reflex arc or something else that doesn't require substantial advanced sensing or processing (i.e., easy to trigger false-positive). But still, seems easy to co-opt existing sensory input (a certain level/location/size of touch?)...not sure what more specific sign one could have that didn't require substantially more/more-advanced sensing. DMacks (talk) 17:17, 19 July 2010 (UTC)[reply]
I'm pretty sure the general understanding is that scratching serves to remove irritants of every sort from the skin, including contaminants, skin damaged by sunburn, etc. If you Google around for "pruritis" (the medical term for itching), you should be able to get some leads into the literature. Looie496 (talk) 19:31, 19 July 2010 (UTC)[reply]
Dragons using chemicals to generate fire?
It seems to have become a trend now to describe fantasy dragons that use chemical compounds to create flames--as in the movie Reign Of Fire. Supposedly "if a beetle can do it a dragon can too", except that the bombardier beetle doesn't create sparks/flames, just boiling liquid. Are there really chemical mixtures an animal could use to create a flame, or is the whole concept just bunk? 75.200.39.63 (talk) 16:31, 19 July 2010 (UTC)[reply]
Sure. We have evidence that at least one animal can learn to use chemicals to produce fire. See also, fossil record of fire. Lots of chemical mixtures will work, so long as the mixture completes the fire triangle. I would think that any other animals that wanted to create flame would have to use similar approaches - naturally-occurring materials, like wood, sulfur, and phosphates, plus air, plus an ignition source. Nimur (talk) 16:58, 19 July 2010 (UTC)[reply]
There are many chemical mixtures that catch fire when mixted eg potassium permanganate/glycerin - do animals produce such mixtures, or the components is sufficiently concentrated form - no. It's bunk.
The oft mentioned Bombardier beetle produces hydrogen peroxide at only 10% [17] that's nothing like enough to produce a fire .. if the concentration was high enough the beetle would have burned its ass off thousands of years ago in a spontaneous beetle combustion evolutionary dead end !
Living organisms can produce hydrogen and methane, both of which are flammable - a mixture that is known to combust is flatus, as many videos on Youtube will testify. No doubt a bit of fantasy digestive tract re-plumbing could occur to make a fire-breathing dragon. Brammers (talk/c) 17:51, 19 July 2010 (UTC)[reply]
You'd still need an ignition system. After all, human fire breathers can blow dragon-like flames with an external source of ignition (and fuel, but the fuel is relatively easy from a biological point of view). Natural selection hasn't delivered us with fire-breathing dragons, probably because it's easier to use the required energy simply to grow bigger and/or cleverer. Physchim62(talk)22:41, 19 July 2010 (UTC)[reply]
Von Kossa Stain
Von Kossa Stain on the web makes no sense eg [18]the calcium is reduced by the strong light and replaced with silver deposits
It is about the GEOLOGICAL changes, how it is formed and its reasons.
eg:1. Formation of mountains,rivers,valleys etc
2. Information about the tectonic plates.
Please check about it in WIKEPEDIA or any other information giving websites188.135.2.50 (talk) 17:16, 19 July 2010 (UTC)[reply]
And orogeny - learn the meaning of this word and impress your teacher! Personally, I've always been interested in comparative orogeny on extraterrestrial worlds, as it provides one of the best scientific justifications for planetary explanation of solid-surface planets and moons. It's very strange that mountains and valleys can develop on worlds that do not have seismic or tectonic activity, nor water or air to erode them. But, mountains and valleys do exist up there.... Nimur (talk) 23:41, 19 July 2010 (UTC)[reply]
Teeth
Hello
Why is it that teeth do not attempt to repair themselves? Surely in primitave man, broken damaged teeth would have been a threat to survival. This seems the only part of the body without the will to try and heal. Thanks Ossiee (talk) 17:21, 19 July 2010 (UTC)[reply]
We discussed a related question last April. The real issue is not so much why they don't repair themselves, as to why we only have two sets of teeth, rather than having a continuously replenishing number. Primates can't do this, but rodents can, but they sacrifice having teeth that fit well together, which humans kind of rely on. Keep in mind that this is not an evolutionary question limited to primitive man—this is a trait that evolved more generally with primates and probably even earlier than that. --Mr.98 (talk) 17:33, 19 July 2010 (UTC)[reply]
Probably mid way on the Y axis and pretty low on the X axis (depending on dose). As an opioid derivative it's going to be pretty addictive (at least in the long term) but, given it's wide availability as a drug to treat (and not to abuse), it's going to be fairly low on the physical harm side. Regards, --—Cyclonenim | Chat 19:07, 19 July 2010 (UTC)[reply]
That graph was put together by an expert following lots of research. We aren't experts and don't have the time or resources to do lots of research, so we can't work out where any other drugs would appear on that graph. --Tango (talk) 19:25, 19 July 2010 (UTC)[reply]
And in any case, as has been discussed here a few times, it's unclear how literally one should take that particular graph, as it doesn't account for the fact that numerous drugs come in different forms that have different propensities for harm and addictiveness (e.g. the difference between chewing coca leaf or smoking crack cocaine, both of which are technically the same drug). --Mr.98 (talk) 19:39, 19 July 2010 (UTC)[reply]
We can't work out exactly where a drug can go on that graph, but we can speculate based on it's properties that we do know. If a drug is an opiate, it's going to have a high risk of dependency. Regards, --—Cyclonenim | Chat 19:41, 19 July 2010 (UTC)[reply]
Note that the harm figure is an average of acute, chronic and injected harm - mostly chronic harm roughly mirrors dependance (with expceptions), also this means that drugs that are not injected score 2/3 of other similarly 'harmful drugs'. 178.78.65.223 (talk) 19:53, 19 July 2010 (UTC)[reply]
I mentioned this earlier. I object to using average as a measure of harm on this graph. I think they should have used max. Ariel. (talk) 21:23, 19 July 2010 (UTC)[reply]
The problem with using the maximum known harm is that one person could have reacted badly to a drug due to all sorts of reasons, even genetic defects. If a random drug kills one person because of a defect, but causes only mild harm in the others, do you use the maximum harm? Of course not. That's why you have to use averages. Regards, --—Cyclonenim | Chat 21:48, 19 July 2010 (UTC)[reply]
I don't mean maximum harm among various people, I mean maximum from the three types of harm listed in the accompanying table: Acute, Chronic, Intravenous Ariel. (talk) 22:14, 19 July 2010 (UTC)[reply]
The article on tailless aircraft is not much help. It is mostly about aircraft lacking horizontal stabilizers. AS for the first comment, I don't see how I could have missed that! Thanks anyways. --TheHighFinSpermWhale20:32, 19 July 2010 (UTC)[reply]
At the expense of providing an unhelpful answer, "anything can be designed with any parameters you want." More importantly, if you made such a design, would the tradeoff involved be worth the effort? Removing a stabilizer can be done on any aircraft - the result is obviously a less stable aircraft. It will cost more money to design an active control system than a passive one with the same control characteristics and specs. You can look at the specs for a thrust-vectoring system to determine the force, velocity, and time-constant regimes that it can operate over - but I strongly suspect that complete removal of such a major, critical part of the stability and control system of the aircraft would render the airframe virtually uncontrollable. In fact, the advent of the vertical stabilizer is often credited as one of the crucial technologies that made the first heavier-than-air flight possible. Who would have thought that the most important "wing" on the aircraft was the one that didn't provide any lift! The Wright brothers' flyer is more a feat of control than of propulsion, lightweight materials, or any other characteristic - the majority of their innovation was that they could actually steer because they had rudders and wing-warping control. Since control is such an important part of design, it is heavily studied in the design of an airframe. MDATCOM is an aerodynamics program used to design these sorts of things and test them numerically before building models and running them through the wind tunnels. As you begin removing "pieces" from the airframe, you start approaching a missile-like aircraft; you can usually spin stabilize such airframes, but that would be unmanageable if you intended to put a human inside it. Needless to say, this is definitely an ongoing effort in modern defense research - efforts to replace 100% of our aircraft fleet with unmanned aerial vehicles are under way, because removing the human from the flight control equation results in relaxation of many other design constraints. (E.g., instead of a fighter, you could have a highly-maneuverable, spin-stabilized, steerable cruise missile for all of our air-to-air and air-to-ground combat needs). This would be cheaper to build, could operate more stealthily, could be more fuel-efficient/longer-range; could turn faster (without a pilot, there is virtually no restriction on turning radius, maximum G-force, and so on). Nimur (talk) 20:55, 19 July 2010 (UTC)[reply]
Also keep in mind that an aircraft which relies on thrust vectoring to control yaw requires thrust, so there would be no control without thrust. This situation could occur after engine failure, and would occur on every flight when the throttles are at idle during approach and landing. anonymous649421:54, 19 July 2010 (UTC)[reply]
For this reason, spacecraft (including the Space Shuttle orbiter, which is not very aerodynamic, despite its superficial "airplane" shape) have a primary propulsion system and a separate reaction control system. An RCS is easier to build and is more reliable than a vectored thrust nozzle; and it can be designed to provide 6-degree-of-freedom maneuverability. Nimur (talk) 23:44, 19 July 2010 (UTC)[reply]
Currently? I'm sure some people are still trying it - but you are aware that studies have shown conclusively that it doesn't work...right? SteveBaker (talk) 22:23, 19 July 2010 (UTC)[reply]
It certainly has its fans. Its crazy, irrational, fans. If a popular blog makes a post about glasses or LASIK, there's a reasonable chance someone who's never posted a comment on that blog before will show up and post a diatribe about it. If you search Instructables you'll find many howtos covering simplified versions of the Bates method. I'm not sure why Instructables doesn't make an effort to remove such nonsense.
Another related bit of crazy is pinhole glasses. (Pin-hole glasses really do work as a primitive replacement for corrective lenses. But they're always sold as a cure-all that will magically fix your eyes. Which is proven to be nonsense.) APL (talk) 23:07, 19 July 2010 (UTC)[reply]
Can probiotics develop antibiotic resistance?
After watching my toddler endure violent diarrhea resulting from his intestinal flora being completely wiped out by the amoxicillin he had to take for cellulitis, I began to wonder: Is it possible for probiotics to develop antibiotic resistance, so that when you need to take antibiotics, the beneficial organisms that normally live in your intestines won't be harmed?
I'm curious if there have ever been any studies conducted wherein healthy people take deliberately incomplete antibiotic doses, to kill off some of the beneficial bacteria, leaving the remainder to breed stronger. And if so, how long would the effect last? ~Amatulić (talk) 23:01, 19 July 2010 (UTC)[reply]
In principle I don't see anything against it. But I have a feeling it would not develop in humans. Harmful bacteria have a strong "motivation" to develop resistance - if they don't they are wiped out. The probiotic ones however, while they might be killed temporarily they will come back (from other people), so they don't really need resistance so badly. I bet it could be done in a lab though - grow cultures with low level doses of antibiotics. But it has a downside: bacteria are able to share genes (Horizontal gene transfer), so if the "good" bacteria had the genes for resistance, it's possible for "bad" ones to copy them. Ariel. (talk) 01:08, 20 July 2010 (UTC)[reply]
July 20
Unidentified Insect
Hi. I was hoping for some help from anybody with knowledge of British entomology.
Earlier today, I had an insect fly into my house in Devon that I don’t believe I’ve ever seen before. It appeared bigger than a common wasp but rather smaller than a hornet. It had a round but, perhaps, slightly flat yellow body with two extremely well defined stripes circling the abdomen (this was the most immediately striking thing about it – the stripes were not blotchy and poorly defined as on most bees and wasps but perfectly defined, like you’d expect to see on a T-shirt and there were definitely only two stripes) and very big, bulbous grey eyes just above and either side of a bright yellow wasp-like mouthpart. Its thorax looked to be a dark brown colour (perhaps with a hint of red) and its legs (which seemed very long for a wasp) were most definitely reddish. It was so wasp-like that I assume it’s a member of hymenoptera but, given my lack of insect knowledge, I suppose it could conceivably be something else indulging in a bit of mimicry, although I doubt it. Any ideas?
(edit conflict) I think that most "like a wasp but not a wasp" sightings turn out to be hoverflies, but there are so many different species of the critters that identifying the one that visited your house may be difficult. Do any of the ones pictured here look at all like your visitor? Deor (talk) 01:35, 20 July 2010 (UTC)[reply]
Resolved
Facepalm And I didn't even notice Gandalf61's answer above. Deor (talk) 13:02, 16 July 2010 (UTC)
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