Wikipedia:Reference desk/Science

March 6

Some help with thermal fuses?

Well, my coffee roaster packed it in yesterday. After some futzing around online and getting help from various places, I've figured out that the problem is (99%, unless there are concurrent problems) a thermal fuse. I need to replace it via mail-order, as I live far from any major cities.

The fuse is rated 193 degrees C, 10A, 250v. There is a site that I've seen that sells thermal fuses, and they rate them all with three values: Tf degrees C, Tc degrees C, and Tm degrees C. I don't know which one is the actual cut-off value (I suspect Tf). They further say "It is also critical that the Tc (continuous temperature) not be exceeded as it could cause deterioration of the link or pellet and lead to eventual failure of the device."

So now I'm not sure what I need. I'm assuming a fuse with a Tf around 193, but I have no idea what the "continuous temperature" of the machine is, or whether that's really a factor. Is anyone on here a thermal fuse expert? --MattShepherd 00:21, 6 March 2007 (UTC)

Are you sure it's not better just to replace the whole unit ? After all, if one component has failed, it's likely at it's designed life span, meaning you can expect other components to fail soon. StuRat 00:24, 6 March 2007 (UTC)

I would say no. Yes we live in a disposable culture but FUSES were designed to be user serviceable. If you replace the fuse and it quickly blows again then I'd consider chucking it, but fuses can blow for a variety of reasons, not least of which can be as random as a power spike. I would suggest send a quick email to the company you want to buy the fuse from, they should be the experts. Thermal fuses, and fuses in general, aren't really a fine science, but fall within a tolerance, not all the time but getting it roughly right is good enough a lot of the time.. Vespine 02:50, 6 March 2007 (UTC) can be as random as a power spike. Does the old fuse have any other info on it?

This page (look waaaaay down at the bottom] has a brief description of the three values. As you've correctly surmised, T_f is the temperature that the thermal fuse 'blows'; that is, exceeding this temperature will cause the fuse to open the circuit. T_c is the continuous operating temperature; if the fuse is regularly exposed to temperatures exceeding this value, it is apt to degrade. (I'm not sure precisely what the test conditions are to determine this value; I suspect that several hours above this temperature may toast the fuse.) T_m is the maximum operating temperature for the fuse. If the fuse is rapidly brought to a temperature that exceeds this value (note that this temperature is above T_f), it is apt to function incorrectly. TenOfAllTrades(talk) 04:04, 6 March 2007 (UTC)

Thanks to all. I have lots of (anecdotal) evidence that these units last for years and years, and mine has punked out after less than 24 months (but after warranty, bah). After talking to a repairperson, I'm very confident that the fuse fix will be fine.--MattShepherd 20:12, 6 March 2007 (UTC)

peripheral nervous system

How are are affernt/ efferent divisions related to the autonomic/somatic subdivisions of the PNS?

My understanding is that effernt/afferent division is based on fiber directionality (towards/away from CNS). I'm not clear on the somatic nervous system (voluntary/involuntary/both?) and the autonomic nervous system (glandular/internal?)

If we take the somatic/autonomic divsions individually, does that only refer to the motor/efferent fibers (to make the distinction), after which the corresponding sensory/efferent fibers are also in the same somatic/autonomic subdivision?

Is this complicated by the fact that there are many more interactions involved, for example more than one efferent fiber for the motor neuron/efferent fiber?

Lastly, is the manner in which I interchangeable use motor/efferent and sensory/afferent correct? [maybe i should have asked this first ;)]

Thanks for any help in advance.

Aren't you going beyond the scope of the research avalaible as of yet? But I like neuroscience and the study of the brain. :) --Parker007 08:02, 6 March 2007 (UTC)

I'll try and make my point clearer:

Is it...

1. PNS -> divided into somatic/autonomic only [autonomic into sympathetic/parasympathetic] OR

2. PNS -> afferent/efferent + somatic/autonomic [there are afferent and efferent components to both somatic and autonomic] OR

3. PNS -> afferent/efferent -> efferent into somatic/autonomic [sensory neurons JUST afferent; no somatic/autonomic distinction]?

To answer your initial question, there is no one-to-one mapping between afferent/efferent and autonomic/somatic. Like you said, afferent & efferent strictly define the (relative) directionality of transmission in a neuron. The term "relative" is important here, because while the CNS is generally the default reference point, it's not always the case. For example, you can speak about afferent and efferent with respect to an autonomic ganglion, in which the preganglionic neuron is afferent and the postganglionic neuron is efferent to the ganglion. Alternatively, you can consider that two-neuron pathway with respect to the CNS, in which case both pre- and postganglionic neurons would be considered efferent. However, you're right that, in general the terms "motor" and "efferent" tend to get used interchangeably just as "sensory" and "afferent", even though they're not strictly equivalent. The pairs of terms also tend to get used in combination, leading to a sense of redundancy (ie, "motor efferent" and "sensory afferent"). Hope that helps, David Iberri (talk) 22:02, 6 March 2007 (UTC)

Muscle repair and calories

Does my body burn a lot of calories when it repairs itself after my workout? I know my heart rate and metabolism are up after a workout, but not counting those factors. Does anyone know the approximate calories burned in the next few days after a workout from muscles repairing themself? —The preceding unsigned comment was added by 76.167.136.84 (talk) 04:03, 6 March 2007 (UTC).

I think this would be a hard number to identify. The body is constantly creating new cells and repairing itself. The additional calories necessary to heal wounds (or muscle damage from excercise) is probably very difficult to isolate from the normal operation of the body. It may even be insignificant. Caloric burn through excercise is usally calculated as a function of the amount of work done so it's much easier to estimate (and even that isn't very accurate). --Tbeatty 06:12, 6 March 2007 (UTC)

Electrically conductive fluid

I can't seem to find information on this. I need an electrically conductive fluid that is not a liquid metal. I've tried using salt water but it doesn't conduct well enough to produce a high current. Any ideas? —The preceding unsigned comment was added by 24.231.205.94 (talk) 04:33, 6 March 2007 (UTC).

Try electrolyte? --Wirbelwindヴィルヴェルヴィント (talk) 04:41, 6 March 2007 (UTC)

Please provide more information so that people can make appropriate suggestions. What volume or area? How much current is desired at what voltage drop? AC or DC? What is it powering? There are conductive fluids which might work in some applications but might be too toxic or corrosive for others, or which might produce hazards from the gasses they give off. Salt water can conduct an amazing amount of current, by the way, such that it boils rapidly. A "salt bucket" was an early, primitive and hazardous current control device used in electrical testing applications, with obvious electrocution hazards. Edison 20:43, 6 March 2007 (UTC)

I'm looking to conduct around 5-10 amps of DC current across about a 1 cm gap. I've been trying salt water, and salt water + vinegar but they will not conduct even 1 amp. I've been using tungsten rods but only the sides of them, they are 1/8 in diameter. Perhaps my electrodes are too small? I seemed to get better current when I tried large pieces of tin foil as electrodes in a bowl of salt water, but they managed to corrode very fast.

We cannot give you detailed advice without details of the requirements and the limitations. Does the gadget have to have low voltage and a small surface area? What is the application? What is the source voltage? What is the allowable voltage drop in the liquid? Why can't you increase the area to, say, 32 square inches, so that each each square inch only has to carry 1/3 ampere or less? Why can't you increase the voltage? Early experimenters used mercury, not that I would suggest that now because it is highly toxic. Salt water will carry 10 amperes if the area and the voltage and the salt concentration are sufficient. A weak solution of sulphuric acid in water carries a huge current in car batteries. Other electrolytes carry currents as large as you want in other battery chemistries, or in electroplating. Chemists out there- any other suggestions? (edit) Study the Material Safety Data Sheets for any substances you experiment with and avoid possible harm from shock, explosion, or toxic effects of chemicals used. Many electrolyte solutions emit gases which may be toxic or explosive when current is passed through them, requiring ample ventilation. Edison 05:06, 7 March 2007 (UTC)

Memory relationship to the Brain (More and more information)

• How can the brain keep storing more and more information? I mean it never runs out of space even as you grow older.

I believe you forget old things to make room for new things. The brain is pretty good about having you forget unimportant things (things you don't access often) and remember the important stuff, usually. Thus, you are more likely to forget the plot of a movie you saw many years ago than how to walk. StuRat 13:11, 6 March 2007 (UTC)

Memories are stored in synapses, which are highly dynamic structures that join neurons. Existing synapses can be strengthened and weakened on a whim and new synapses are made all the time. I don't know if the literature supports the idea that memories need to be forgotten to make way for new ones. In fact, "forgetting" often involves the formation of new synapses, which runs contrary to that hypothesis. --David Iberri (talk) 02:43, 7 March 2007 (UTC)

Well, the brain certainly doesn't have an infinite capacity, so can't store everything we ever see in full detail. The only option then is to forget old things to make room for new things. We also all have fuzzier memories of things that happened decades ago than things that happened yesterday, which seems to support this idea. You might be able to recall what you had for lunch yesterday, but can you recall what you had for lunch on March 7, 1997 ? As for forgetting being caused by the formation of new synapses, this also supports this concept, as the new synapses (containing new memories) are formed at the expense of the old ones synapses (containing old memories). The one issue I'm not clear on, is whether things are constantly being forgotten to make room for anticipated new memories, or if this forgetting only happens when a new memory forms. There might also be a feedback mechanism ("Warning: Brain is at 99% capacity, begin forgetting lowest priority memories immediately to make room !"). StuRat 12:46, 7 March 2007 (UTC)

I have to state the the lunch you ate on March 7, 1997 would be a short term memory due to its lack of importance. But how long does short term memory last? Regarding the plot of a movie you saw years ago, when we are able to make connections we can usually recollect all information. That's my theory. For example, if I want to know what I ate last week, I will have to make several connections, in order to get that particular piece of information. For example, what happened during that day etc. --Parker007 20:18, 7 March 2007 (UTC)

But the meal info is long gone, and lots of other memories, and no hypnotherapy will ever be able to recall them. StuRat 21:26, 7 March 2007 (UTC)

Memory relationship to the Brain (location)

• Where exactly is the memory stored in the brain? --Parker007 07:32, 6 March 2007 (UTC)

In the CPU =P nah but i heard that we only use 10% of our brains. im not sure if this is still true today.Maverick423 16:22, 6 March 2007 (UTC)

How could you store memory in the CPU? Put it in your RAM, hard disk, or keydrive. − Twas Now ( talk • contribs • e-mail ) 17:08, 6 March 2007 (UTC)

There are 10 times more glia than neurons in our brain, that's where the term we use 10% of our brain comes from, and it is false. --Parker007 17:28, 6 March 2007 (UTC)

Neat now i can throw that old rumor out and learn something new =) the process of memory in progress Maverick423 17:35, 6 March 2007 (UTC)

Karl Lashley did some early studies to find the locus of memory storage, but came up relatively empty handed. In his experiments, he trained mice (rats?) to navigate a maze, then lesioned parts of their cortex and tested their ability to navigate the maze again. Despite the location of the lesion, the mice were able to navigate the maze relatively well. It was only with broad lesions of multiple cortical areas that memory impairment began to show. This led Lashley to believe that memories were arbitrarily scattered across the cortex, which is contrary to modern belief. IIRC, current thinking is that memories are distributed throughout the brain, particularly in the cortex. For example, a mouse's memory of navigating a maze may involve visual, auditory, olfactory stimuli, etc. These distinct aspects of the spatial memory would be scattered in an organized way throughout the different cortices of the brain (visual cortex, auditory cortex, etc.), and recalled in concert when the memory was required. An explanation for Lashley's results is that when one part of the cortex is lesioned, a piece of the memory is lost, but others remain and are able to compensate for the lesion. --David Iberri (talk) 02:43, 7 March 2007 (UTC)

“ brain activity related to a spatial memory task was shifted from the hippocampus to the striatum after participants slept... ”

This is a quote from a recent study paper: http://parker0007.googlepages.com/SleepReorganizesMemoryRepresentation.pdf and specifically they have a diagram showing which parts of the brain was activated during finger tapping experiment via the use of fMRI. --Parker007 20:32, 7 March 2007 (UTC)

Special Drug for LTP? (brain)

• long-term potentiation (LTP) is an increase in the chemical strength of a synapse that lasts from minutes to several days

• Is there a special drug that can iduce Long-term potentiation in the brain? --Parker007 07:46, 6 March 2007 (UTC)

Induce or enhance? Long-lasting cognitive improvement with nicotinic receptor agonists: mechanisms of pharmacokinetic-pharmacodynamic discordance <-- this article reviews the idea that drugs acting on nicotinic acetylcholine receptors might be able to enhance LTP. This might be relevant to acetylcholinesterase inhibitors that are used to treat Alzheimer disease. There are similar articles ([1],[2] , [3]) about Levodopa that have implications for treating Parkinson disease. Drugs acting at AMPA receptors are a third class of drugs that can enhance LTP; AMPA receptor potentiators for the treatment of CNS disorders. --JWSchmidt 21:41, 6 March 2007 (UTC)

Neuron, glia, and the Brain

• The brain is composed of two broad classes of cells, neurons and glia, both of which contain several different cell types which perform different functions.

• If this is so, then why do scientist say Brain areas such as the hippocampus, the amygdala, or the mammillary bodies are thought to be involved in specific types of memory.? --Parker007 07:52, 6 March 2007 (UTC)

These statements don't appear to be contradictory, but perhaps you could explain why you think the first statement negates the second? − Twas Now ( talk • contribs • e-mail ) 17:05, 6 March 2007 (UTC)

Why do these statements seem contradictory to you? One is about the basic classes of building blocks, the other is about how different large assemblies of these building blocks perform different functions. A basic set of building blocks, such as the LEGO blocks, can be assembled into a large variety of different things. Would you have a problem with statements like CPU chips are composed of two broad classes of elements: transistors and interconnects and Different areas of CPU chips perform different functions, such as arithmetic calculations, short-term data storage, and interpretation of instructions both being true? --mglg_(talk) 17:19, 6 March 2007 (UTC)

You are misrepresenting this relationship—they aren't performing functions as distinct from one another as arithmetic calculation and storage. Parker007 says all these areas are memory-related. Secondly, there are two different classes of brain cell, but each class contains different types (or subclasses) of brain cell. This leaves a lot of room for variation. Analogously, there are several different types of epithelial cell (see Image:Illu epithelium.jpg), and they all have different functions. − Twas Now ( talk • contribs • e-mail ) 17:51, 6 March 2007 (UTC)

What is pseudophrene?

• What is pseudophrene?

• Does it have a more common name (or trade name)?
• What is it used for? Robbielatchford 11:35, 6 March 2007 (UTC)

Do you mean Pseudoephedrine? --Kainaw ^(talk) 13:03, 6 March 2007 (UTC)

A cheap knock-off "phrene" ? :-) StuRat 13:06, 6 March 2007 (UTC)

Reckon thats the one, I did wonder why Google only pulled 9 hits, and most of them were about frogs. Thanks for the help. Robbielatchford 00:00, 7 March 2007 (UTC)

blucat: Do you mean Psuedoephedrine? A patentable version of Ephedrine, the active ingredient of Epherda, the name of the plant? Drug Class Sympathomimetic, Bronchilator, used clinically for asthma ,broncholitus, and hay-fever. (trade names Sudafed, Sinutab). Used by many to delay ejaculation, and generally used/abused by most party goers for increased sexual satisfaction? Much better than Viagra -- (no citation -- oops ..)

Agronomy/Crop Science

What are the minimum and maximum limits of nitrogen (N) contents in the ear leaf and grain of maize crop? Please include the references or source. —The preceding unsigned comment was added by 212.85.201.250 (talk) 14:07, 6 March 2007 (UTC).

an explanation for the variation of boiling points in hydrides of group 15 elements

The group 15 elements are N, P, As, Sb, Bi. These elements combine with H to form the hydrides. If a graph is plotted for the variation of the boiling points, the graph will keep on increasing and then suddnly will decrease. The reason for this is because N been an electronegative element, when combined with H will result in gaining a partial negative charge and H will get a partial positive charge. Due to this dipole interaction, the atoms are tightly bound, therefore resulting in a high boiling point. But P is not as electronegative as N and so the atoms are not as tightly bound, resulting in a low boiling point and the sudden reversal of the graph. —The preceding unsigned comment was added by 124.43.210.121 (talk) 14:59, 6 March 2007 (UTC).

• Is that a question or a statement? --Shanedidona 15:38, 6 March 2007 (UTC)

Differntiate between "Metal Scrap" and "Metal Waste"

I want help to differntiate between Metal Scrap and Metal Waste.

Scrap metal can be used for other things, and waste metal cannot? − Twas Now ( talk • contribs • e-mail ) 17:02, 6 March 2007 (UTC)

Our scrap article suggests that they are synonymous. There may be localized distinctions, such as the terminology used by a given company, but there does not appear to be a standardized distinction. Note also that the American Heritage Dictionary includes Discarded waste material, especially metal suitable for reprocessing. as a definition of "scrap". — Lomn 18:35, 6 March 2007 (UTC)

In the context of recycling, metal waste is leftovers from manufacturing (roll trimmings, casting sprues, and the like) while metal scrap (or scrap metal) is metal from broken machinery and the like. It's like the difference between pre-consumer and post-consumer waste in paper recycling. --Carnildo 00:11, 7 March 2007 (UTC)

Magnets and heat

Hey i recall going to the Museum of Science and Industry in Chicago and in it they stated that magnets can also loose their magnitisem with heat temporarly. but in the article it doesnt state that the magnet can regain its magnetism or if it can permenatly lose it. so i ask what is the max tempreture (if any) that a powerful permenate magnet can endure before losing its magnetism completly.Maverick423 16:32, 6 March 2007 (UTC)

Well, it rather depends on the material in question. Ferromagnetic materials (those that can maintain aligned magnetic domains, that is, can be "turned into a magnet") become paramagnetic above their Curie temperature. This means that they can still become magnetized in the presence of external magnetic field (in other words, a magnet would attract them), but they cannot maintain the magnetic alignment once the external field is removed. So yes, a ferromagnetic material would "permanently" lose its magnetic alignment if raised above its Curie temperature. However, if it were cooled down it could be re-magnetized. I think the situation is similar for ferrimagnetic materials. -- mattb @ 2007-03-06T16:52Z

Ferromagnets (normal magnets) lose their ability permanently, although it can be remagnetized. The critical temperature is the Cure point. [Mαc Δαvιs] X (How's my driving?) ❖ 16:54, 6 March 2007 (UTC)

Mac Davis probably meant the Curie point. Nimur 19:08, 6 March 2007 (UTC)

Passing two magnets at similar or opposite positions for prolonged periods (days weeks years) will this cause loss of magnitismMaverick423 17:22, 6 March 2007 (UTC)

In fact, Tesla even patented a motor based on this effect; [4] --BenBurch 19:43, 6 March 2007 (UTC)

An iron nail, heated red hot with a torch, falls off a permanent magnet. When it cools a bit, the magnet attracts it again. As Ben said, Tesla worked with this and so did Thomas Edison. Reciprocating motion is very easy to devise and implement, rotary motion a bit harder. There is the issue of energy lost getting an keeping the apparatus near red hot, but I have wondered about possibilities for such a motor using substances with a lower Curie point than iron, or used near a hot environment (a foundary or blacksmith shop, the planet Mercury, near blast furnaces or other furnaces, or in chimneys). It could use an electromagnet or a permanent magnet to provide the magnetic flux which produces the attraction, then modulate that force by the temperature variation in the metal from just above to just below the Curie point. Edison 20:51, 6 March 2007 (UTC)

Death Mimicry?

I recently heard about a crystal like chemical that can be absorbed through the skin and drastically slows down the body's processes. I was going to use this as an example for a discussion coming up in one of my classes but could not remember the name of it, I have looked for it on google and as I do not know the name of it could not find it on Wiki. Please help me as I really want to be able to bring this up, I do belive it starts with an "a".

thanx,maxx. 66.99.49.226 18:13, 6 March 2007 (UTC)

That sounds REALLY unlikely - I'd look for something else to talk about in class. SteveBaker 18:54, 6 March 2007 (UTC)

Asbestos and arsenic can lead to illness and death. Nimur 19:09, 6 March 2007 (UTC)

no, it only mimics death, not actually causing it, also I understand that it is sometimes used to stop a heart in hospitals when there is a need to regulate an abnormal heart beat. -maxx- 66.99.49.226 19:46, 6 March 2007 (UTC)

So, a paralytic agent then?--VectorPotential^Talk 20:45, 6 March 2007 (UTC)

Sounds like you mean Curare? --BenBurch 22:07, 6 March 2007 (UTC)

Except it doesn't start with an "a" (: The only way I can think of to reconcile this is that both of our answers are acetylcholine inhibitors, and that does start with an "a" --VectorPotential^Talk 23:28, 6 March 2007 (UTC)

How about atropine? Don't know that it would absorb through skin, though... --Ocarinacavegirl 03:31, 7 March 2007 (UTC)

YAY!!!!! we found it!!!! i didnt know if it could be absorbed through the skin, i just thought it might be possible if you mix it with some other agent/ dissolvant.

Mysterious fog

Hi. Again, I usually help out, but I'm hoping that you could help me again. One day, when it was very cold (about -20°C), with winds of about 30 km/h, and very few clouds, I witnessed a thick fog gliding over the ground, staying only about 10cm over the ashphalt road. The snow was thick, and most of it was loose. I had no idea what the fog was, was it snow, condensation, chimney smoke, furnace vapour, evaporation, latent heat, car exaust, washer fluid, greenhouse gas,or something else? Thanks. AstroHurricane001^{(Talk+Contribs+Ubx)} 18:23, 6 March 2007 (UTC)

• Depending on your location, might I suggest smog?--VectorPotential^Talk 18:28, 6 March 2007 (UTC)

Well, I don't really think it was smog, for several reasons. I live in Canada, and smog usually isn't that problematic on cold winter days. I saw it on an ashphalt road, and practically nowhere else. Also, I've never seen smog drift along the ground slowly in a mistlike manner. In some areas the fog drifted as high as one metre (about 4 ft), and smog usually goes higher than that. I'm thinking it was probably mist or exaust, or something like that. Thanks. AstroHurricane001^{(Talk+Contribs+Ubx)} 18:38, 6 March 2007 (UTC)

its possable someone forgot to turn off the automatic watering on their yard? they ussally form steam in colder weather conditions and if its under the snow it can appear to come out of nowhere as the vapors escape.Maverick423 18:40, 6 March 2007 (UTC)

Well, in such cold conditions, evaporation from a warmer body of water would produce nice drifting ground-fog - so maybe there was a warmer pool of water nearby - the outflow from somekind of drain that might contain warmer water perhaps? As for why it stayed 10cm above the asphalt - asphalt is dark and absorbs heat from the sun during the day - and will stay quite a bit warmer than the ambient air for hours after sunset. So there might well be a thin (10cm) layer of warmer air just above it - which would eliminate the visible water vapor in the fog for a short distance. I don't think there is anything too surprising going on here. SteveBaker 18:52, 6 March 2007 (UTC)

very cold air, very black asphalt very bright day. Sun heats asphalt enough to evaporate/sublimate ice from cracks on road surface raising relative humidity of near-surface air, which rises, and cools to produce near-surface fog. I would susped that this rapidly reaches an equilibrium condition as the fog cuts off the sunlight. -Arch dude 19:55, 6 March 2007 (UTC)

If you look at Fog you will find an entry for "ice fog" which is likely what you saw. --BenBurch 20:10, 6 March 2007 (UTC)

Hi. I think you might be right. There was snow on the ground, and it melted into water. However, I think the most probable causes are snow, condensation, or car gas exaust. It could have been snow because the snow may have been blown onto the streets and since the air is cold, the snow might have been trapped between the snowbanks with cold air pressing it down, warm air from the road pushing it up, and winds moving it. However, I usually don't expect snow to remain afloat in air for minutes, even hours. It might have been condensation, because some of the water may have evaporated, forming a thick fog on the road. It might also have been gas, because condensation might have formed on the relatively warm gas, which might have stayed. I saw the car gas rapidly fade at first, but the fog from the cars lingered, probably for several minutes. Later in the day, some of the road was dry, and the fog dissapeared. Car gas dissapeared in seconds. Also, I don't think it was a sprinkler, because most people don'tleave out their sprinklers after weeks of sub-zero temperatures under a foot of snow, ice, and more snow. So, does this sound plausible? Thanks. AstroHurricane001^{(Talk+Contribs+Ubx)} 21:55, 6 March 2007 (UTC)

Hi. I saw the same effect when the snow was melting and the water was being heated by the sun. Thanks wikipedia. AstroHurricane001^{(Talk+Contribs+Ubx)} 21:13, 8 March 2007 (UTC)

Underwater flatus increases odor?

Just curious why flatus released underwater (like in a bathtub, pool or even shower) always smell so much worse then ones released in air? --24.249.108.133 21:15, 6 March 2007 (UTC)

Answers from when the question was asked before. Anchoress 21:18, 6 March 2007 (UTC)

Muscle question

Could someone please tell me what the most sensitive muscle in the human body from fingers(included) to elbow is. Thanks a lot.Question101 22:10, 6 March 2007 (UTC)

i dont know but i find jabbing someone (with little or no force) on the sides above the hips about a hand lenght from the belly button shows very powerful results. =) but i think this is just a pressure point as to being a acctual muscle.Maverick423 22:47, 6 March 2007 (UTC)

What exactly do you mean by "sensitive muscle"? Physiologically, muscle sensitivity is related to the number of motor neurons innervating it. Is that what you're referring to? --David Iberri (talk) 02:29, 7 March 2007 (UTC)

My prof just said "whats the finnest muscle from elbow to hand"? I would really appreciate an answer cause I really need a bonus right now. Thanks Question101 12:50, 7 March 2007 (UTC)

hmm... i dont know that there is anything sensitive in the arm, the only thing that hurts when i push on it is my broken wrist from last week >.< but try the solar plexus, right inbetween the bottoms of the ribs and right below the long thing from the neck bone extending down to connect the ribs (forgot what its called). -maxx- 66.99.49.226 13:43, 7 March 2007 (UTC)

From the phrasing, It seems that you are looking for either the thinnest muscle that extends from the elbow to the hand, or the smallest muscle in the forearm. I take "finnest" to mean finest. Well, there is one muscle, the palmaris longus which is basically just a strip of tendon with a tiny little muscle attached at the end, which goes from the elbow to the palm of the hand. It is indeed very dainty. Overall the smallest muscle in the forearm is probably the third palmar interosseous muscle, which is attached to the root of your pinkie finger on the ring finger side. ^tucker/_rekcut 16:45, 7 March 2007 (UTC)

Maybe they were asking for the one with the finest control, a muscle that can provide a huge or a tiny force or anything inbetween :) HS7 19:57, 8 March 2007 (UTC)

I don't know but getting punched in the upper arm hurts like hell. --Candy-Panda 06:12, 9 March 2007 (UTC)

Bad guts last night - physical symptoms

I was out on the town last night and I ate a very dodgy pizza. It wasn't so much that I got food poisoning from it - but it was very, very greasy. I woke up in the middle of the night (maybe four hours after eating it) with stomach cramps and had to evacuate my bowels several times in rapid succession (not exactly diarrhoea, just nasty-smelling, sloppy, greasy poop). Accompanying my intestinal distress was a feeling of extreme dizziness and my whole body felt ice-cold, despite being soaked in sweat.

I'm not asking for medical advice here (I'm fine now, once I cleared it all out of my system) but does anyone have an explanation for the dizziness and cold sweats I experienced? Never had anything like that before. FYI, alcohol was not involved. --Kurt Shaped Box 22:42, 6 March 2007 (UTC)

Food poison?? hmmm or maybe an excess of grease. it sounds more like food poison to me though. (trust me i know) but i didnt exactly get the ummm same results as you did with the rushing to the bathroom. maybe it was a mixture of both?Maverick423 22:49, 6 March 2007 (UTC)

I don't think it was food poisoning - it came on way too quickly for that, in my experience (I've had food poisoning before). I think that it was just a case of the bulk and grease pushing out everything before it... --Kurt Shaped Box 23:21, 6 March 2007 (UTC)

Maybe you're becoming lactose intolerant? Clarityfiend 00:24, 7 March 2007 (UTC)

I doubt it. I eat takeaway pizza all the time with no problems. This one was a *bad* pizza (topped with doner meat) from a place I don't normally go to - the sort that makes you think "why am I even eating this crap?" as you're eating it. My excuse? I was really hungry, it was late and I'd paid for it... :) --Kurt Shaped Box 00:46, 7 March 2007 (UTC)

A gastrointestinal doc explained it to me like this: Inside your intestines are tons of little fingers. They like to grab the poop and pull it along. When it gets all soupy in there, they can't grab on to anything. So, they grab each other and start to twist and pull at your insides. Coincidentally, moving the intestines around was once a popular form of torture because it causes such extreme pain that the body goes into shock and you end up with hot/cold flashes, sweat, numbness, dizziness, ringing in the ears, and seeing spots (among many other symptoms of shock). So, the doc said, eat plenty of fiber. --Kainaw ^(talk) 01:44, 7 March 2007 (UTC)

I suspect you had an immune system response to your food. It's not uncommon. You'd have to see a doctor to figure out why but you probably wouldn't get an exact answer. People with irritable bowel syndrome often have the same response but to different triggers. Fever often is accompanied by dizziness/delirium and the fever is part of the immune response. --Tbeatty 04:39, 7 March 2007 (UTC)

It sounds rather like dumping syndrome. --DrGaellon (talk | contribs) 17:45, 8 March 2007 (UTC)

the grease sounds like the pizza was very fattening--Lerdthenerd 10:53, 9 March 2007 (UTC)

Easy Terminology Question

Hello, I have been searching for terminology for the following concepts:

1. One thing to multiple things. 2. Multiple things to one thing.

The concept in 1. is also that the first one thing is not altered when it expands to multiple things. It just leads to them, like one idea leading to further multiple ideas for example.

In 2. the concept is also that the multiple things are not altered when added together, like multiple ideas converging into one conclusion. Obviously the "thing(s)" could be any noun.

Is there a simple terminology, perhaps in physics? The closest I've gotten is inductive/deductive (specific to general and vice versa), but that's not the same thing.

Thank you!

Chuck

216.38.138.162 23:04, 6 March 2007 (UTC)

This is a database concept. You are referring to "one-to-many" and "many-to-one" relationships. There's also the "one-to-one" and "many-to-many" relationships. Every few years, some guy comes along and tries to coin a terminology for the concepts, but they've used the words "one" and "many" for far too long for some new term to come along and take over. --Kainaw ^(talk) 00:09, 7 March 2007 (UTC)

Removed the email address from this question, as it is practically asking for spam. Nimur

I don't think he means the database concept — he is not necessarily proposing a system of correspondence, which is all database relationships are. --24.147.86.187 02:29, 7 March 2007 (UTC)

And don't forget "The needs of the many outweigh the needs of the few, or the one." - Spock. StuRat 12:39, 7 March 2007 (UTC)

1. Reduction ? Analysis ?

2. Emergence ? Synthesis ? Gandalf61 17:26, 7 March 2007 (UTC)

March 7

Why do White Castles disagree with so many people?

Hello. I personally love White Castle, but all I hear from everybody is how they give everybody gas and make everybody feel awful and things like that. I'm asking this cause I've never had a problem with them before, but today I had 8 of them for lunch and I feel absolutely awful. Why does it seem like they cause this reaction more than any other fast food place? NIRVANA2764 02:49, 7 March 2007 (UTC)

I'm not sure (don't have any references to cite about any of this), but they're pretty greasy, aren't they? Some people can't tolerate much grease at all. Others of us, we can usually eat lots of it comfortably, but sometimes, depending on metabolic cycles or mood, or what else there is in the stomach, or whatever, too much grease is definitely gross. —Steve Summit (talk) 04:05, 7 March 2007 (UTC)

Here's the nutrition info for a single White Castle hamburger (I had to go to a third party site, since White Castle's own site has the nutrition info conveniently "under construction"): [5]. I'm assuming you mean you had 8 regular single hamburgers. In this case, you had 56% of your daily calories, 64% of your daily fiber, 88% of your daily fat, 120% of your daily saturated fat, 96% of your daily protein allowance, and 48% of your daily sodium allowance. This is a lot to digest at once, especially the saturated fat. The onions also really do me in. While a hamburger is definitely healthier than a double cheeseburger [6], this benefit disappears when you eat eight of them. What makes the WC hamburger "junk food" is that it doesn't fill you up and you need to eat eight to feel full. You would have to eat about 14 WC hamburgers to get your daily calorie requirements, at which point you would have eaten 210% of your daily saturated fat allowance. And, if you are like many people who eat twice their daily calorie requirements, that would give you 28 WC hamburgers and a whopping 420% of your daily saturated fat allowance. And, despite all that bad fat, you still would be lacking many of the vitamins, minerals, amino acids, etc., your body needs. StuRat 12:27, 7 March 2007 (UTC)

well my wife said she saw how white castle burgers are made. they say they steam them and cook them from one side and dont bother to flip it. let me just say that is very nasty XD as one side remains a bit raw. if you look closly to your burger you will see 4 little imprints on one side only that is where they steam them. the other side is just left to cook that way. one side is well done while the other is not so well done which gives you problems with your stomich =) but i got to admit those little burgers are very tasty!Maverick423 14:24, 7 March 2007 (UTC)

I am pretty sure they don't start out with 'raw' material in the first place, i think those little postage stamps are actually soybeans and sawdust, with some fryer grease mixed in to give it a beefy taste. So in terms of done-ness, I really don't think you have anything to worry about. --66.195.232.121 15:10, 7 March 2007 (UTC)

plasma to electricity

This phenomenon requires energy, in the form of applied high voltage, to get started, but probably cannot be used as a supply of energy. Nimur

is there a way to turn plasma to electricity or to create plasma in a circuit between 2 electrodes and than mix in a third source energie (plasma ,light or other)?

Not sure what you mean. A plasma is an electrically neutral collection of charged particles. In that sense it is more like a conductor with interesting properties associated with drift and diffusion current and the large difference in velocities between electrons and ions. Inserting an electrode into a plasma will charge it up negatively due the larger amount of electrons that will impact it per second (due to velocity differences). equilibrium will be reached at some voltage that allows for equal impacts. This is very similiar to a diode. --Tbeatty 04:27, 7 March 2007 (UTC)

im not talking about puting an alectrode in the plasma, i mean creating flow of plasma between a positive an a negative electrode put in a closed circut and than mixing another kind of plasma in the flow for it to go trough the electrodes along with the current , if the system is strong enough the idea would be to extract energy from lightning or maybe from sunlight if it is compatible , would this be possible? clockwork fromage

No. --Tbeatty 05:08, 7 March 2007 (UTC)

is it that far fetched?

It looks like some have tried to extract energy from a moving plasma in a magentic field: from magnetohydrodynamics:

MHD power generation fueled by potassium-seeded coal combustion gas showed potential for more efficient energy conversion (the absence of solid moving parts allows operation at higher temperatures), but failed due to cost prohibitive technical difficulties. ref=# ^ [7] GB 05:48, 7 March 2007 (UTC)

so basically it would be possible to capture lightning this way but extremely hard and if magnetic reconnection occurred it would make a huge explosion , correct ?

Fluorescent light or neon light? I still can't decipher exactly what the original questioner means. You cannot extract energy from lightning (electric sparks) that you induce in your device; you have to supply energy to create them. Nimur 07:01, 7 March 2007 (UTC)

lightning from storms not man made , why coudnt that be considered as an alternative energie source ? clean , renewable and great potential clockwork fromage

Lightning is hard to predict and hard to collect. It doesn't offer a constant, predictable, or reliable energy source for mass power generation. -- mattb @ 2007-03-07T15:08Z

its predictable is you use lightning rods and you seed the clouds

Quntam energy compulsion cycle?

I read in an article that quantam energy compulsion is caused by the diminutive release of the particle decobodification through homosapions and large values of hydrocronic electric plasums but acourding to theoritical quantum sulfur theory almost all mast produced hydrocronic electricity is by far indeginable.Intectuell homospions such as myself find this humerous because of the inditable facts.because of that mistake I knew the rest would be "mumbo jumbo" so thats why I posted my question.Anyway my question is how does the hydrocronic Quantum theory prove that all protons have quantum energy???ALSO I think that Milad is really cool!!! —The preceding unsigned comment was added by 74.102.217.142 (talk) 04:33, 7 March 2007 (UTC).

I believe this will answer all of your questions. --BenBurch 14

07, 7 March 2007 (UTC)

Am I missing something? Capuchin 14:32, 7 March 2007 (UTC)

About 500 mg. ;-) --BenBurch 16:55, 7 March 2007 (UTC)

membranes freely permeable to K+ (Na+?)

"if a membrane were freely permeable to K+ but impermeable to other positively charged ions, K+ ions..." continue moving until equilibrium potential (K) is reached.

why is there a constraint that it be impermeable to other positive ions? why not also include negatively charged ions?

what about the conditions if the equilibrium potential for Na were desired to be reached? should the membrane be permeable to Na+ only?

note: RMP assumed at -70mV for standard 'excitable cell'

Take a look at Reversal potential. --JWSchmidt 15:38, 7 March 2007 (UTC)

The equilibrium potential (aka reversal potential) of an ion assumes that the membrane is permeable only to that ion, and impermeable to all other ions, not just ions of the same charge. So the constraint would include both positively and negatively charged ions. To reach sodium's equilibrium potential, the membrane must be permeable to sodium only, as you said. --David Iberri (talk) 17:12, 7 March 2007 (UTC)

SHARE ME THESE IDEAS

idea#1:Does the time behave like avector? Moving with aconstant velocity, ds1=vdt1,ds2=vdt2 ds=SQR(ds1^2+ds2^2), vdt=SQR{(vdt1)^2+(vdt2)^2}, hence, dt=SQR(dt1^2+dt2^2). Moving with acceleration and velocity is zero, ds1=gt1dt1,ds1=gt2dt2, dt=SQR[{(t1/t)dt1}^2+{(t2/t)dt2}^2]. it looks like the time behaves lik avector here,but it doesn`t when, ds=ds(v)+ds(g)=vdt+gtdt.the question is why is that?

idea#2:can we use the phenomenon of MIRAGE and LOOMING to explain why the planets of the solar system rotate in one direction while venus rotates in the opposite direction???

See Retrograde_motion#Retrograde_rotation for current theory. StuRat 12:03, 7 March 2007 (UTC)

idea#3:LOGICAL OBSERVATION FUNCTION. i think it is better to redefine th concept of velocity,because v=ds/dt,it means that the derivative of (s)with respect to astraight line which is (t).now, let`s put,

v=[(ds/dt-df/dt)/SQR{1+(df/dt)^2}], f(t)= constant if (s) as avector<0, f(t)=it,i=SQR(-1) if (s) as avector>0, we will call f,the logical observation function. it helps us to understand the relativistic concepts of motion.it helps us for instance to understand and solve the twin paradox.

80.255.40.168 10:15, 7 March 2007 (UTC)ARTHER.

For one analysis see [8]. Edison 14:50, 7 March 2007 (UTC)

Edison brings up an excellent point. Nimur 20:17, 7 March 2007 (UTC)

Burglarizing snot from my nose

Get that booger outta there!

A while back (about two years), I recall in the news a study about nose-picking. The findings—at least those reported in the news—were that people who pick their noses are more in touch with their bodies than those who do not pick their noses. However, the article on nose-picking only mentions a bunch of risks associated with nose-picking—all of which seem highly improbable.

Getting to the point, I was wondering if anyone else had heard about the study? Was the science behind the study credible? I think this would make a nice addition to such a lovely topic. − Twas Now ( talk • contribs • e-mail ) 12:39, 7 March 2007 (UTC)

what good is digging for gold if you cant share it with the towns people! but honestly nah i havent heard of such a study. however i did hear that people that masturbate are more intouch with there bodies (gee wonder why) Maverick423 14:31, 7 March 2007 (UTC)

What makes paper sticky when damp?

At one point or another, I'm sure everyone has received a wet newspaper in the driveway. Or has stepped on a sheet of paper after taking a shower. What makes wet newsprint cling to itself so tightly? And what makes paper stick to damp skin so steadfastly? --72.202.150.92 14:30, 7 March 2007 (UTC)

well paper starts off as a goo or something like that that is dried repeatly. when its a goo it sticks alot however when it drys you can write on it and all that good stuff. that is why people use wet paper to make art works.Maverick423 14:42, 7 March 2007 (UTC)

I think Maverick is on the right track. It starts off as a thick, fibrous and gluey pulp. The addition of water probably makes the paper wet, and bothers the glue, which would make it go back towards the pulp stage of it's development? [Mαc Δαvιs] X (How's my driving?) ❖ 01:15, 8 March 2007 (UTC)

Maybe it's to do with the fact that the hydrogen bonds continue through the fibrous material. Seans Potato Business 20:44, 8 March 2007 (UTC)

Seagulls as game birds?

Why don't people shoot seagulls for food? They're big, they're fat, there's lots of them but as far as I know, people don't eat them. Considering that people shoot ducks, pheasants, pigeons, etc (all smaller birds), why not the seagulls too? --84.65.223.136 15:55, 7 March 2007 (UTC)

because they live in rural/semi-rural/populated areas, that is the same reason why people cant shoot geese >.< it would be good if we could because all the local fields and parks by me are absolutely covered in goose droppings. -maxx- 66.99.49.226 15:58, 7 March 2007 (UTC)

Local by-laws in most areas say you can't kill animals without special permits. They're also more likely to have harmful chemicals in their body, more so than birds who live in rural areas or on farms. -- Zanimum 16:27, 7 March 2007 (UTC)

And their leader, User:Kurt Shaped Box, would have them attack and wipe out mankind. StuRat 18:36, 7 March 2007 (UTC)

We actually eat very few carniverous animals in our daily diet - and there is a good reason for that. Biomagnification. Toxins in the environment are taken up at the bottom of the food chain and concentrated at each subsequent link of the chain. Seabirds are towards the top of the marine food chain - we are better off eating fish instead. SteveBaker 19:02, 7 March 2007 (UTC)

My grandmother actually dined on gull stew with her family during WWII. According to her recollections, her father once shot two black-headed gulls and brought them home for the pot (he'd eaten them himself as a child, so I guess he thought "why not?") to supplement the rations. The meat was apparently quite strong-tasting, tough, dark and stringy but it 'wasn't awful'. --Kurt Shaped Box 00:02, 8 March 2007 (UTC)

Seagulls are scavengers: they eat things like garbage and carrion. This means they pick up the flavor of whatever they eat (seagull meat, like most carnivore meat, doesn't taste very good), and they tend to pick up whatever diseases and internal parasites their food had. --Carnildo 20:15, 7 March 2007 (UTC)

Gulls are also generally very scrawny. The bulk you see is mostly feathers. --Kurt Shaped Box 23:27, 7 March 2007 (UTC)

If seaguls, then why not pidgeons, foxes, cats, &c :] HS7 19:20, 8 March 2007 (UTC)

Pigeons are frequently eaten, although they're not the feathered rats we see in urban areas. Corvus cornix 22:29, 8 March 2007 (UTC)

Birds have very little fat on them, with up to half of their weight being made up of muscles, mostly in the wings, and the rest divided roughly equally between feathers and bones :) HS7 19:53, 8 March 2007 (UTC)

AFAIK, most of a bird's muscle mass is in the breast - those muscles are the ones that power flight, not the ones in the wings (take the feathers off the wings themselves and there's not much there). Birds that do a lot of walking/running also have muscular legs (i.e. the 'drumstick'). --Kurt Shaped Box 20:32, 8 March 2007 (UTC)

sorry, that should have been for the wings :( HS7 20:19, 9 March 2007 (UTC)

Oil sands vs. Tar sands

A reporter has asked why we use tar sands as the title for the article, not oil sands. Based on the talk page, this is what I could guess, and I'd like confirmation.

It seems that they were originally known by scientists, geographers as tar sands. The name oil sands only came about when technology advanced enough to make extraction easy enough for the public to pay attention, and eventually oil corporations started making investments in the projects. As a result, oil sands became the popular name.

Is this interpretation of the discussion correct? -- Zanimum 16:26, 7 March 2007 (UTC)

yes I do belive that it is, as you can get tar from oil and oil from tar but amongst the commonfolks the preferred term is oil sands, just like they say concrete not cement. -maxx- 66.99.49.226 18:23, 7 March 2007 (UTC)

I imagine the oil companies prefer the term "oil sands" because that doesn't bring to mind all the sludge in "tar sands", which then has to be disposed of. Thus, this euphemism makes it seem like a cleaner energy source than it really is. StuRat 18:34, 7 March 2007 (UTC)

Coefficient of friction between wheel bore and axle

How might someone determine the coefficient of friction between a wheel bore and axle given a setup like the one pictured here? Given that you know the mass and radius of the wheel, the radius of the wheel bore, the radius of the axle, the width of the wheel/axle contact, the mass of the weight on the string and the time for the weight to fall a given height, what equation(s) would give the coefficient of friction? dryguy 17:37, 7 March 2007 (UTC)

Do you really need to know the coefficient of friction, or do you just need to know which is best out of a series of wheels ? StuRat 18:31, 7 March 2007 (UTC)

I want to be able to compare different lubricants and be able to compare data with others using similar, but possibly not identical setups. The latter requirement gives rise to the desire to be able to compute the coefficient of friction in order to separate out differences in wheel mass, axle/bore diameter, height of drop, etc. dryguy 18:40, 7 March 2007 (UTC)

If the wheel is not slipping, then the only friction is between wheel-bore and axle. You could try to apply a force and measure the acceleration, but I imagine the coefficient-of-friction is so low (close to zero) that you will not be able to practically apply this technique. You might also try spinning the wheel at high rate of speed (perhaps use a power-drill with a known RPM rate), and determine the slow-down time of the wheel. Then you can determine the torque due to friction. I'll see if I can find simple equations to determine "mu-k" (kinetic friction coefficient) from the slow-down time. Nimur 20:22, 7 March 2007 (UTC)

I agree that wheel-bore/axle friction is the only friction. I just meant that the time for the weight to drop a given height will depend on other factors besides the friction, so it will be nice to have a way to ferret out the coefficient of friction in order to compare set-ups that have differences in wheel mass, height, etc.

The drill sounds like a good idea; the main difficulty will be selecting the right rpm to approximate what a car experiences on the track. Thanks for offering looking up the equations - it should be a big help. dryguy 21:13, 7 March 2007 (UTC)

indigestible edible muffins

Jim said that "they" used to manufacture and sell "edible muffins" that were indigestible. The muffins could be chewed and swallowed like regular food, but the chemical structure prevented the body from metabolizing the nutrients (or it contained no nutrients) resulting in complete elimination from the body with zero calorie absorption.

Is this true? What was this product called and how did it work chemically? Who was "they"? Why was it discontinued? NoClutter 17:49, 7 March 2007 (UTC)

I imagine it would be very rough on your digestive system. Everyone needs some fiber, but 100% non-nutritive fiber in that quantity would be overkill. StuRat 18:28, 7 March 2007 (UTC)

You could certainly bake something like that using artificial sweeteners in place of sugar and Olestra as a cooking oil. That would result in something with almost zero nutrients - yet which would be tasty and not do terrible things to your digestive system. SteveBaker 18:54, 7 March 2007 (UTC)

Tasty is a matter of perspective. Some people can distinguish between natural and artificial ingredients such as {sugar vs. saccharine or sucralose}, or {fat vs. olean}. Nimur 20:33, 7 March 2007 (UTC)

I certainly can, and Olestra causes "anal leakage", so I wouldn't call it free of side effects. If a delicious calorie-free muffin really could be created which had no adverse side effects, it would be a runaway success. If they canceled production, we can be reasonably sure it didn't meet all those requirements. StuRat 21:21, 7 March 2007 (UTC)

Full Moon Madness

I need help with the following issue. Please do not tell me I need psychological help or meds. I have noticed that everytime there is a full moon, I am anxious, short-tempered and have a general feeling of nervousness/anger. Does anyone experience this? Is there a scientific reason for this? Does anyone know of how I could curb these symptoms?

Are you female? If so, perhaps your monthly period simply happens to coincide with the full moon (give or take a few days)? SteveBaker 20:11, 7 March 2007 (UTC)

Are you a werewolf? If so, perhaps your monthly period simply happens to coincide with the full moon (give or take a few days)? Nimur 20:23, 7 March 2007 (UTC)

(You didn't sign your message - but looking at the edit history, I deduce that you are indeed female). I did some further research. Menstrual cycles typically happen on a 28 day cycle - but anywhere between 21 and 35 days is considered normal. The moon is full every 29.5 days - so it's very possible that your body might happen to be in sync with the full moon just by pure coincidence. It would be surprising if you were so perfectly in sync that this would be the case forever - but over a period of years, I bet you find that the relationship between the phase of the moon and these times of unease gradually drifts out of sync. Your symptoms seem quite believable - we married guys know only too well that we need to keep a low profile at "certain times of the month". Generalized grouchiness/anxiousness is certainly an absolutely typical symptom. You can certainly talk to your doctor (you might not want to start off by claiming to be a lunatic though! See Lunar effect) - I believe there are treatments relating to birth control pills that can tame the worst of the symptoms - but we aren't allowed to offer medical advice here - so "See your doctor" is as far as we can go. SteveBaker 20:29, 7 March 2007 (UTC)

Barring the possibility of some menstrual cycle coincidence, you should be aware that there is absolutely no scientific reason why a full moon should have an effect on anyone's mood. Your problem may just be your own superstition; I would recommend learning more of the real facts about the Moon— and try looking at it through binoculars sometime, and you'll see it's just a beautiful piece of geology.--Pharos 21:03, 7 March 2007 (UTC)

Also, maybe you spend a lot of time at the full moon thinking about the psychological effects of the full moon, which could make you nervous and jittery. --18.214.1.72 22:16, 7 March 2007 (UTC)

Not true i have heard of psychological studies that state that the full moon effects a person by drawing more blood to the head which can cause some of the symptoms that juliet mentioned. i will look for a source for this to back this up give me a bit Maverick423 22:19, 7 March 2007 (UTC)

No need to look it up - let's do the calculation. Let's say the gravitational pull of the full moon could result in blood being "pulled to the head". What is the gravitational pull of the non-full moon? It is the same. The amount of light reflecting from the moon to the earth should not affect the gravitational pull of the moon. --Bmk 22:27, 7 March 2007 (UTC)

heh it appears you are correct i revisited the place i found it on and it states that it does not effect the human body lol i guess i forgot to read that one word Maverick423 22:38, 7 March 2007 (UTC)

I also think women's periods can come to coincide with recurrent events. I forget where I heard this. But that would explain the regularity. 70.108.199.130 23:37, 7 March 2007 (UTC)

Well, it's a cycle, and it can be easily coordinated with other women. Depending on the intensity of the "problem," the questioner could be recommended to see a doctor to refer her/him to a psychiatrist. It could just be the menstrual cycle or a perceived effect coming from local superstition. [Mαc Δαvιs] X (How's my driving?) ❖ 01:08, 8 March 2007 (UTC)

If the two intervals coincide by chance - which is really likely if at typical human cycle is 28 days and the moon cycles over 29.5 days - there must be a huge percentage of women who's menstrual cycles just happen by pure coincidence to be 29.5 days. Since this feeling lasts several days, and the moon looks full for several days there is maybe a one in ten chance of it happening to coincide with the full moon. There must be literally millions of women who hit this point in their cycle on a full moon. It's not just likely - it's nearly certain that a large slice of the population hit the exact frequency and phase to match the moon. It means nothing - it's just a coincidence. SteveBaker 03:25, 8 March 2007 (UTC)

Stuttering and the neurotransmitter Dopamine

• I believe there is a featured article Stuttering, and the article states, Dopamine Antagonists are used to treat stuttering.

• My question is, what is the actual relationship with stuttering and the neurotransmitter dopamine?

• Secondly, the featured article states, stuttering can be caused by anxiety.

• Dopamine is the neurotransmitter involved with happiness. So anatagonizing dopamine will make the person depressed? --Parker007 20:21, 7 March 2007 (UTC)

Changing dopamine levels can have dramatic side-effects. Levodopa is a drug used to combat everything from schizophrenia to Parkinson's disease by elevating the dopamine levels. Yet, it sometimes has unwanted psychological side-effects worse than the original condition. I am not an expert, but I think there is not a direct one-to-one correlation between dopamine level and correct synapse function, let alone mental health. Nimur 20:27, 7 March 2007 (UTC)

i am trying to think

what give rise to thought?

what i mean is, if the brain works on the same physical and chemical laws that govern non living things, then thought generation should be an entirely random phenomenon. then how is it that as an individual i am able to think about what i want to think about?

59.180.16.107 20:53, 7 March 2007 (UTC)

Not knowing anything scientific, logically I would guess that the mind has set things to 'think' that will help keep you alive. This could be awareness of others, memory of past events, automatic responses. Self-awareness and [Consciousness]] are supposed to be two of humanities biggest 'divides us from the animals' characteristics. I suspect this ability to understand/realise ourselves and others gives us the ability to think beyond simplistic survival towards more advanced survival. I risk being 100% wrong here, but that's how I would think of it. How you choose what to think will be sparked by things you see, things you hear, smells, sounds, situations, taste any of the senses really. Great question though - hopefully someone with half a brain gives you an actual answer rather than just, well, drivel like me! ny156uk 22:01, 7 March 2007 (UTC)

Nope, you pretty much nailed it… I think, therefore I am. It's one of the olders questions to confound man, the oldest is "how can I get that girl's attention" ;). Vespine 02:26, 8 March 2007 (UTC)

But what about "we think, therefore we am?" Better instead say "thinking exists, therefore thinker(s) exist. Let me answer your original question with a question: if earlier conditions in an object must entirely determine the later conditions, plus perhaps some random noise, then how can "freedom of choice" exist? When you get right down to it, what is free will? What does it mean to have selective intent, to be able to make decisions? Or in other words, is freedom of choice just an illusion? If not, then it's outside of known physics, since modern physics only includes the pure determinism of Classical Mechanics and the statistical randomness of QM. Where does our apparent freedom to make decisions come into contemporary physics? Perhaps self-awareness isn't the mystery of consciousness, since a purely deterministic computer program could concievably observe its own operation yet remain deterministic. On the other hand, how could a computer program ever have the ability to observe the factors affecting a decision, then choose to ignore them and instead make the wrong decision intentionally, because it wanted to? --Wjbeaty 03:47, 8 March 2007 (UTC)

The questioner contends that physical and chemical laws yield an "entirely random phenomenon." I think this is fundamentally incorrect. If you drop an apple, there is no randomness about the direction it will fall. If you mix vinegar with baking soda there is no randomness as to what will happen. These are structured events governed by physical laws, which scientists can study and uncover. This is quite the opposite of your question. Perhaps you might ask whether our thoughts are entirely deterministic, or if there is enough complexity in the system to yield complicated behavior. Or perhaps you subscribe to the notion that quantum mechanics and its sub-atomic uncertainty propagates up to macroscopic events like chemical reactions (this is a disputable issue, depending on how you interpret the statistics and how you choose to define random). Nimur 17:53, 8 March 2007 (UTC)

Aerodynamics

Why are some things that need to be aerodynamic not pointy in the front? Wouldn't hand gun bullets travel farther and faster if they were sharp instead of round at the front? Wouldn't airline jets have less drag and be more efficient if they had pointy noses like fighter jets instead of those round bubbly nose cones?
For the first example someone told me they're meant to be that way so they don't pierce right through the victim and hit someone else. Which is just silly because you can still make them aerodynamic and use less gun powder. What about the airplanes example? Is there any harm in making the nose too aerodynamic? —The preceding unsigned comment was added by 209.53.181.32 (talk) 22:24, 7 March 2007 (UTC).

Believe it or not, there is at least one article dedicated to that exact question - you can read all about it at nose cone design, and also some in nose cone. It appears that simply making the nose slimmer is not sufficient - there are more complicated aerodynamic considerations to take into account. And also, don't forget that the sharper the nose cone, the longer it must be to connect to a body of given width, so there is much more metal-air frictional interface. But I know very little about aerodynamics. --User:bmk

I've corrected bmk's links. To summarize, however, a pointy nose is not necessarily aerodynamically ideal. The first article specifically notes that for velocities below Mach 0.8 (such as airliners), blunted nose cones are ideal. — Lomn 22:36, 7 March 2007 (UTC) (after edit conflict)

Also note that bullets from rifles have a spin, so air isn't just moving straight along them. Thus, if you were to add a nose cone, it would need to be more of a corkscrew shape. Also, I believe any point on a bullet would cause the bullet to tumble once the point got slightly off center, and a tumbling bullet is much less aerodynamic. This is a basic stability issue. While passenger planes are designed to be stable, which makes them easy to fly, fighter planes are designed to be aerodynamically unstable, which allows for quicker turns and maneuvers, and a round nose is more aerodynamically stable than a pointy one. StuRat 23:19, 7 March 2007 (UTC)

I've coma across this same question in model rocket circles, those guys know a lot about nose cones. This site has some great info and here is even a piece of software to design nose cones. Vespine 02:23, 8 March 2007 (UTC)

One critical concept involving pointy-fronts on non-supersonic aircraft: if the nose is pointy, and if it hits the air at an angle, then there will be flow-separation on one side and sideways-directed frictional forces which lead to tumbling. Or if a wing has a sharp leading edge, and it hits the air with a positive attack-angle, then there will be major flow-separation above the wing, and major turbulent friction. It's called a "stall." Sharp leading edges cause the air-flow to peel loose from the object's sides. To avoid this situation, eliminate the sharp front parts and make them smoothly rounded. Pointy parts are only good for supersonic objects, and for objects having guide-fins which prevent it from tilting with respect to oncoming air. --Wjbeaty 03:30, 8 March 2007 (UTC)

Bullet noses are only pointed in the case that you want it to go really really far. See .223 for an example of a rifle bullet designed for distance, and 9mm Luger for a handgun bullet designed for stopping power. The idea that you can simply use less powder in a handgun bullet is erroneous, the purpose of the bullet is to hit one target and do as much damage as possible, to do this you need lots of acceleration AND lots of mass. --66.195.232.121 15:01, 8 March 2007 (UTC)

Waking up from a bad dream

This may seem kind of bizzare--I don't know if anyone else experiencces this. When I have a bad dream, usually I realize it's a dream near the end (just before something realy bad happens to me or someone else, like getting attacked by the beast or what not). The wierd thing is, I'm still terrified and I feel literally stuck in the dream. At this point, I must be consious because I'm trying to "get out" of the dream. Then I try to wake myself up by "jerking" by neck or torso... and the strangest thing is that it always works by the second or third try. A couple of questions: Why on earth don't I ever think "Who cares, it's just a dream, so why don't I try to enjoy it like a horror movie". The second question is, why do I need to physcially shake my body to wake up, why can't I just open my eyes and wake up?
This is not just one incident, it's happened to me so many times. Does this all sound bizzare or does anyone here know what I'm talking about? —The preceding unsigned comment was added by 209.53.181.32 (talk) 22:40, 7 March 2007 (UTC).

What you are describing is so common that it has a name: a hypnic jerk. Take a look at our article on hypnagogia, which basically applies (though strictly speaking, because you're waking up rather than falling asleep, you're in a hypnopompic rather than a hypnagogic state). - Nunh-huh 23:06, 7 March 2007 (UTC)

(1) If you thought this, that is the best possible thing you can do in a dream. See lucid dreaming. It is really cool :) (2) Normally I just take my fingers and pull my eyelids off of contact with my eyes a few times, kind of "popping" them, or just "opening" them past where they would normally physically be able to fold up. If you are lucid, I would recommend trying your best to stay in the dream. The most effective technique for this, is mysteriously, spinning around on your vertical axis. I'm really not sure hypnic jerk has anything at all to do with this, since it is a physical muscle spasm that happens when you are falling into sleep, could that be clarified if I'm missing something? I recommend you do your best to become lucid, and know, accept, and understand that you are in a dream and you can do anything you want. :) What would you like to be able to do in normal life but is often constrained by social or physical limitation? Favorites are flying and sex. You may be on your way to becoming a lucid dreamer! Good luck, hope I helped any. [Mαc Δαvιs] X (How's my driving?) ❖ 01:03, 8 March 2007 (UTC)

If I have a lucid dream I usually have to fight to stay asleep :( Vitriol 01:37, 8 March 2007 (UTC)

Long ago I've had similar eperiences with nightmares, but in order to escape, I used my voice to break out of the dream. If I could use my real-world vocal chords to say "raaaahhh," then I broke out and awakened. (I think I was awakened by the sound.) But after years of nightmares, today I can usually just watch the events without fear. As for being able to enjoy nightmares, I don't think most awake-state skills are available when sleeping. "States of consciousness" are weird things in that all of the skills developed during one state aren't available during another state. Classic example: if you study for an exam while drunk or while very sleepy, then the learned material won't all be available if well rested or sober during the exam! So, recall how scary a horror movie was during your early childhood. Toleration of horror movies is usually a learned skill. Since we learned that skill when awake, it's not necessarily available during sleep. So... we react to nightmares as if we were little kids confronting a horror movie. Learning to enjoy nightmares takes time, and unfortunately it's a *separate* process from learning to enjoy horror movies. For more info search on "state-dependant memory" google search--Wjbeaty 03:18, 8 March 2007 (UTC)

As for "Why on earth don't I ever think "Who cares, it's just a dream, so why don't I try to enjoy it like a horror movie", it's probably a good thing that you don't think that. I've always believed that dreams are not "just dreams". They are messages from the unconscious to the sub-conscious. They mean something. What they mean, or whether any particular dream is significant or not, is not my or anyone else's place to say. Only you can work that out, if it's important enough for you to know. JackofOz 03:53, 8 March 2007 (UTC)

I am a skeptic and I am not sure there is much scientific evidence, if any evidence at all. "Evidence is not the plural of anecdote." In my opinion, it seems logically fallacious since I can completely control any of my dreams. So my unconscious and sub-conscious is taking a break while my conscious takes over driving for a while? It's a personal belief thing. Since we're on the subject, I'd like to ask what compelling evidence there is for an unconscious and sub-conscious? We usually assume a conscious. [Mαc Δαvιs] X (How's my driving?) ❖ 07:55, 8 March 2007 (UTC)

Well, if you remember that your 'conscious' and 'subconscious' are both just you, there isn't really a problem. Have you never sort-of known something that you haven't properly thought about consciously? As in, something bothers you about a situation, then you have a proper think why, and you realise through conscious thought? Subconscious is just a name for the process that is doing that first thinking, but that doesn't mean there are two seperate people in your head. It's all you. It's just useful semantics. Dreams seem to me to be a way of sorting out the thoughts in your head. Since you don't tend to think about everything consciously all the time, while it might be 'at the back of your mind', they can bring up things you didn't realise you were thinking about. You could call this 'messages from your subconscious to your conscious', because that is a convenient way of putting it. An example (although anecdotes are not reliable evidence, it serves to explain what I mean): Every so often, when I'm living away from my family, I get a dream where some natural disaster sweeps in and I'm trying to get them all safely out. I wake up, thinking about the dream, and realise that I'm missing my family and worrying about them, having not seen them for a while. I visit home. It's only my own thoughts, no outside intervention, but it is a useful way of picking up the thoughts and feelings that I don't have time to think about, or don't want to think about, when I'm awake.

On to lucid dreams. In lucid dreams you are aware of dreaming and appear to have conscious control over the dream, yes? However, studies (damn, where are they?) have shown that when questioned shortly after waking, lucid dreamers report not retaining constant lucidity throughout the whole dream. So they have moments when they act as if it is real, or they do/think something that makes no lucid sense. So your actual lucidity may not be as total as you'd think. Another way of looking at it is that you have exchanged one valuable function of sleep for the excitement of lucid dreaming. However, I imagine you end up doing most of the thought-sorting you'd normally do in a dream, just with the impression of more control. If not, I would expect your memory to be shot to pieces :-P

Finally, everyone is in complete control of all their dreams, because dreams are all in the head. Just because it is what we are calling the 'subconscious' doesn't make it any less you, in your brain. Although scans have shown that dreamers usually have sections of their brains less active in such a way as to render them functionally mentally handicapped in the dream. Which explains some of the odd reasoning. (And if you want proof of unconsciousness, let me find you a general anaesthetic.....) (Possibly all this is ranting and should be removed?)

As to the jerking, I get that too sometimes. It seems to be related to the hypnogogic jerk, in me at least. It's like my muscles get hooked back up to my 'dream muscles', so a dream motion causes an actual motion, and that movement is enough to jerk me awake. I used to find realising I was asleep woke me straight up, unless I tricked myself into not fully realising (by pretending it was a film or book I was watching/reading/writing), but in recent years I've had to claw my way awake if I don't like it. I think it's just one of those things. You're not alone :-) Skittle 01:49, 9 March 2007 (UTC)

I guess I'm lucky because all of my dreams are "lucid" dreams (I know I'm dreaming) and I'm fully able to just open my eyes at any time and wake up.. as long as I'm dreaming. --froth^T 09:11, 8 March 2007 (UTC)

The "dream producer" can in my experience work amazingly fast. If the phone starts ringing, your mind may try to keep your sleep going by incorporating its sound into the dream, by creating an instantaneous "backstory" which leads up to you hearing the ringing as part of the dream action, like you pressing a doorbell in the dream. Similarly if the clock radio is giving the news, the words of the announcer may be incorporated into the dream. The point of this in the extreme is that your body may be about to give a big movement and the dream creator provides an instant nightmare to "explain" it. We do not provide medical advice, but if this causes problems for you or a bed partner, you might wish to discuss it with your doctor. You might be interested in Sleep , Dream , Sleep paralysis , Lucid Dreaming , Sleep disorder , Night terror , Restless legs syndrome , Sleep paralysis , False awakening , and Polysomnography . Edison 22:54, 8 March 2007 (UTC)

So that time when I had a dream where people decided to start ringing a bell just before my alarmclock started ringing, I made all of that up after I heard the alarm? A bit worrying if I did, messing up my own memory deliberately, and it didn't even work as I still woke up :( HS7 20:15, 9 March 2007 (UTC)

Actually I just realised, it didn't do it deliberately as I was asleep and therefore couldn't deliberate it, so I must have just done it on purpose :] HS7 20:16, 9 March 2007 (UTC)

Homework (but it's only a small part of a question in a series)

So. AP Physics C. We're working on circuits and we've got this big packet of questions. There are diagrams I can't reproduce, but the question I'm asking is basically theoretical. I've got an idea, and I just want to make sure it's right. So the circuit in question is roughly symmetrical. A wire runs off the positive end, forks into a resistor and a bulb of unknown size, then rejoins and forks again, this time into two bulbs (of unknown size) and two resistors of a different resistivity (if that's the right word) from the first one. The four wires then go back into another fork into a bulb and a resistor, the same as the first two. In other words, to simplify it, the positive and negative charges follow the same path until they meet at those four middle obstacles (2 equal resistors and two questionably equal bulbs). The question is whether, for those two questionably equal-in-size-and-thus-resistivity bulbs, the CURRENT FLOW in one is equal to that in the other regardless of any size difference. My feeling is that since the same net flow flows regardless, the same current will flow over each bulb, just slower (this is clearly the wrong term, but I think the gist comes across) depending on bulb size. In other words, the ratio of flow between the two would be a simple 1:1 regardless of size, and the ratio of that current flow to the flow of current through the battery would be 1:4 because the charge is equally distributed through the four "obstacles" in that equal level of charge, so to speak. Correct? Hopelessly wrong? Thanks for any feedback, 70.108.199.130 22:36, 7 March 2007 (UTC)

I learned about resistors and stuff like this when i was in highschool however i cannot give you a conclusion unless i see a diagram as that is how i solved all problems like this. as far as the flow you got to realise that you placed resistors in the circit which in turn would reduce the voltage of the power going through your wires. and with out exact resistence stated we cant know how much of that power is taken by the resistors. try to make a diagram or something so i can check it out unless someone else can solve this before you do.Maverick423 22:45, 7 March 2007 (UTC)

also realise that the size of the bulbs dont effect the flow of power unless they too have some sort of resistave material inside them to do so. Maverick423 22:48, 7 March 2007 (UTC)

acctually i think i may have something for you to think of for what you are trying to do. this is my rough diagram ( 120 v source)====B===B===B===B (back to 120 v source) the wires here are connecting in a perallel fashion which means 120v are distributed equally however if they were connected something like this (let me try) (120)==<B}==<B}==<B}==<B}==(120) the power is spread out into the bulbs so 120v becomes 30v per bulb because the power is spread within the bulbs. really this is alot simpler to explain in a diagram but im trying my best to help you with what i got Maverick423 22:57, 7 March 2007 (UTC)

Here's my attempt at a diagram. None of the bulbs are necessarily equal, though I think the top and bottom ones have to be. And the large/small bulb convention is based on bulbs he's had us use in experiments, which do have different resistivities.

   ________________ _______
   |               |       |
   |               |       |
--------         bulb     1.6V resistor 
4V battery         |       |
  ---              |       |
   |        -----------------------      
   |        |      |       |      |
   |      .8V R   bulb    bulb   .8V R
   |        |      |       |      |
   |        -----------------------
   |               |       |
   |             bulb     1.6V R
   |               |       |
   -------------------------

70.108.199.130 22:58, 7 March 2007 (UTC)

the energy is reduced each time the power passed a bulb or resistor unless the (hot) wire is perrallel to the neutral one. but since your trying to reduce the volts this would be pretty much wasteful. however the volts if connected from the resistor to the bulb will be reduced and you can still maintain 4.5 v by bypassing the resistor with a parallel wire. ill see if i can make you a diagram

Yeah. I get that. The question is whether the flow of charge through those two middle bulbs is equal regardless of any difference the two might have in resistivity. 70.108.199.130 23:07, 7 March 2007 (UTC) Oh, and it isn't 4.5. I copied that down wrong and that may have thrown you, cause then the numbers wouldn't have worked.

sorry for the late response i had a emergancy. well according to what you provided it seems that the bulbs assuming they use about 1v each will not be equal. but seeing as how there are 2 diffrent sizes i would assume that the smaller of them is .4v and the bigger about .8v which would mean that both the center bulbs should have more then enough energy to be powered but they wont be equal seeing as how the small bulbs will only use .4v and the resistor next to the small bulb blocks off 1.6v. this is of course assuming that this is the voltage usage of the bulbs either way the bulb next to the resistor will have to use 1.6v to allow both bulbs in the middle to be equal to each other. the .8v resistors will not seem to have a effect since they are not in the direct current of the power source they are well out of the way. Maverick423 02:21, 8 March 2007 (UTC)

What's a bulb? If you mean a traditional Incandescent light bulb, then we need to decide if you have a theoretical bulb or a real bulb. A theoretical bulb has a fixed resistance and no inductance. For this, you can create an equation that describes this circuit exactly as a pure series/parallel resistive circuit: simply assign resistances (B1, B2, B3, and B4) to each bulb and plug them in. Real bulbs are very different, however, for two reasons. First, A real light bulb filament is a coil,and a coil is an inductor. This is means that current cannot change instantaneously. Second, a real bulb has a change in resistance with temperature, and therefore a change of temperature with time*current. This means that when you flip the switch (i.e., when the voltage changes instantaneously from 0 to 4v) you initiate a complicated time-varying set of changes in the current through each bulb. If we characterize each bulb as having a fixed inductance L, a fixed coefficient of resistance/temperature C, and a fixed dissipation of power P, then each bulb is (L,C,P). With four bulbs, you have twelve numbers and a whole lot of calculus. I would speculate that for some valid sets of bulbs, your circuit will exhibit chaotic behavior. -Arch dude 02:38, 8 March 2007 (UTC)

The homework question is somewhat of a "trick question" because it tests you for the "sequential" misconception, the "current sharing" misconception, the "absolute voltages" misconception, etc. Many beginners incorrectly believe that batteries supply a (constant) current which then divides itself as it hits branch points. To avoid all these mistakes, base your reasoning entirely upon Ohm's law: the current through a particular resistance is only determined by the voltage measured between the two resistor terminals, divided by the resistor's ohm value. Ask yourself this: will you ever measure two different voltage values across the terminals of two separate lightbulbs if the two bulbs' wires are connected to each other? Also ask: do you *know* that the ohms value of those two bulbs is equal? --Wjbeaty 02:48, 8 March 2007 (UTC)

Voltage will be the same across parallel elements. BTW, what are those resistors with voltage? Resistors don't directly regulate voltage. Let me read this question over before I answer in more detail. --Wirbelwindヴィルヴェルヴィント (talk) 03:00, 8 March 2007 (UTC)

Ok, you're thinking if the two bulbs parallel to the (magically) 0.8 V resistors have the same resistance, and we're assuming light bulbs to be a resistor and not an RL circuit, then yes, you're correct in thinking that the current through each of those two bulbs will be the same. However, they do not move slower, just that you have less current (amperage). For the other part, current going through each of those middle bulbs are the same through each of the four branches... That part is the wrong assumption, unless the resistors and the bulbs have the exact same value. Then yes, the current through each bulb will be 1/4 of the total. But if it's not: If the 0.8 V resistors have less resistance than the bulbs, then less current will blow through the bulbs than the 2 resistors, and vice versa. I'll draw a diagram right now to show you more clearly. --Wirbelwindヴィルヴェルヴィント (talk) 03:11, 8 March 2007 (UTC)

Ok, I uploaded an image to help demonstrate. Assuming those are not 1.6V resistors and 0.8V resistors, but that there is a voltage drop across them of those values, that means everything parallel to them has the same voltage. That means both Bulb A, Resistor A, Resistor D and Bulb D have the same 1.6V drop. This also means that Bulbs B, C, and Resistors B, and C have the same 0.8V drop. So the question (I think) is, do Bulbs B and C always have the same current. The answer is no, because the current through those is dependent on the resistance of Bulb B and Bulb C, which is given by dividing the voltage by the resistance, or 0.8V divided by the resistance of Bulb B and 0.8V diided by the resistance in Bulb C. So from that, you can see that they will have different current if the resistances vary.

As for the total current through Bulb B + Bulb C + Resistor B + Resistor C, it is the same as the current through Bulb A + Resistor A, which is the same as the current through Bulb D + Resistor D. The actual value is computed by finding the equivalent resistance of all 8 elements, and then dividing 4V by that total resistance. But that only gives you the current through each set of parallel elements. Hope this helps. If not, ask here or you can reach me on my talk page. --Wirbelwindヴィルヴェルヴィント (talk) 03:50, 8 March 2007 (UTC)

. When exact circuits are specified, exact answers can be given. Circuit equivalents can be determined and circuits can often be simplified and solved, using such tools as Ohm's Law, and rules for parallel resistances, series resistances, current divider. "The question is whether, for those two questionably equal-in-size-and-thus-resistivity bulbs, the CURRENT FLOW in one is equal to that in the other regardless of any size difference. My feeling is that since the same net flow flows regardless, the same current will flow over each bulb, just slower" I know of no electrical principle that" the same net flow flows regardless." When you say "the same current will flow over each bulb, just slower" that implies a misunderstanding of what electrical current is compared to what electrical charge is. One might say "the same charge will flow through a circuit element, just slower" which would be less current, but it is quite incorrect to say the same current could flow but more slowly. Re-read in your textbook the difference between charge (coulombs) and current (amperes, or coulombs per second) and abandon attempts to analyze circuits based on motivation of charges to do this or that. Look at an example in your text of circuit reduction, or provide exact circuits to be analyzed. In my sad experience, attempts to analyze complex circuits qualitatively and verbally fail utterly. I agree with Wjbeatty and Wirbelwind. The key question appears to be if the two unknown bulbs identified by Wirbelwind as Bulb B and Bulb C which are connected in parallel will carry the same current. As the question is interpreted, they each have the same voltage applied across them from the nodes shown above and below. As stated, they do not necessarily have the same wattage and thus can have different resistances. What if Bulb B was a 10 watt bulb and Bulb C was a 1 watt bulb? Then Bulb C would have far less current flowing through it. Circuit elements in parallel need not have the same current flowing through them at all, and often have vastly different currents. All the rest of the circuit has no relevance to this question. Edison 16:17, 8 March 2007 (UTC)

Energy / momentum / mass

The relativistic energy-momentum equation is E² = (mp)² + (mc²)². For a stationary object (p=0), this can be reduced to E = mc². Which of these relations / equations was discovered / derived first? →Ollie (talk • contribs) 23:18, 7 March 2007 (UTC)

Aren't they essentially the same equation? E=mc² is the famous one but it may be because it rolls of the tongue so much nicer ;) Einstein may have gone through the 1st one to arrive at the simpler one but there is no way someone else came up with the 1st for Einstein to just reduce it into his famous equation. Once you have one the other seems arbitrary, chicken or the egg? Vespine 01:06, 8 March 2007 (UTC)

Einstein derived the first equation from the mathematics of Lorentz transformations when he was creating the Special Theory of Relativity. After that, he did what any mathematical physicist would do and set p=0.MisterCDE 06:13, 8 March 2007 (UTC)

March 8

Magnetic field formula derivation

I am curious as to how the equation shown here is derived, specifically, the inverse cube relationship, and with a minimum of calculus, if that's possible. If anyone could point me to a proof/explanation on the Internet or give me some tips as to how to go about deriving it, it would be much appreciated. -Elmer Clark 03:07, 8 March 2007 (UTC)

If you're just interested in where the inverse cube part comes from, it's pretty straightforward. First of all, for a the electric field of a charged particle, or a light source, or a gravitational field, the intensity of the field falls off as the inverse of the square of distance. Conceptually, you might think of a hollow sphere as a model—the field originates with the object at the centre, and the intensity of the field gets 'spread out' over the surface area of the sphere at any given radius. Since surface area increases with the square of radius, the field strength falls of by an inverse square relationship.

Now think about a magnetic field. Magnetic dipoles are just that – dipoles – there's so far never been discovered a magnetic monopole (though there are physicists who hunt for them). Think of each pole of a magnet as having its own field, where each field is equal in strength but the two are opposite in magnitude. Any point around the magnet influenced by one field will see that influence weakened by the effect of the other field.

Treat the net magnetic field, then, as the sum of two fields following an inverse square relation. The first field will be at a distance x, the second at a distance of x + a, where a is some small number relative to x. The total field will then be proportional to 1/x² - 1/(x+a)². Add those up (expand the brackets and bring everything over a common denominator) and...and you'll have a mess of terms. What you do then is make the 'far field' approximation; that is, assume that the distance x is much larger than a, so you need only keep the terms of the highest order in x as terms with fewer xs and more as will tend to be negligibly small. Presto! The inverse cube relationship comes out.

The rest of the terms in the dipole formula come from various physical constants, or from dealing with the effect of 'viewing' the magnet from an orientation other than directly end-on. TenOfAllTrades(talk) 03:41, 8 March 2007 (UTC)

If you look at the electric dipole, the gradient of the potential also kicks out an r^3 term, along with the 4 pi. you might pick up a book on electromagnetics for engineers, cause they are easier to read.172.161.102.213 12:30, 8 March 2007 (UTC)

I took emag centuries ago, and I wish I had bought Div, Grad, Curl, and All That or some other book to supplement that main text. I never understood it very well, but I know EE/physics gets a ton easier if you force yourself to learn the mathematics part.172.161.102.213 12:39, 8 March 2007 (UTC)

Thanks fellas. -Elmer Clark 23:27, 8 March 2007 (UTC)

Ptolematic system

Did retrograde motion inspire the idea of epicycles in the Ptolematic system? Thanks very much for responding. 208.72.125.187 03:32, 8 March 2007 (UTC)

I don't believe that apparent retrograde motion was observed until Tycho Brahe, or at least we have no record of it being observed prior to him. However, I believe the ancient Greeks did notice that the paths the planets traced in the sky were not followed at a constant speed. That is, if an object takes X days to complete an apparent orbit around earth, it's not necessarily 1/4th of the way around the Earth in X/4 days. This discrepancy needed some explanation. The real explanations are that those planets don't orbit the Earth (so the Earth isn't in the center of their orbits), and they follow elliptical orbits, not circular, with the object they orbit at one of the two focus points, not the center. StuRat 08:05, 8 March 2007 (UTC)

Really? That seems to contradict Deferent and epicycle. And if retrograde motion hadn't been observed before, then what was the point of epicycles? --Allen 08:09, 8 March 2007 (UTC) [I left this comment after StuRat had written only the first sentence of his response above. --Allen 08:23, 8 March 2007 (UTC)]

Okay; that explains why we would have had epicycles before. But what you're saying still contradicts our two articles you and I linked to. Why do you say we have no evidence that retrograde motion had been observed before? If you're right, and a source can be found, we ought to change the articles. --Allen 08:23, 8 March 2007 (UTC)

That article states that retrograde motion was used to develop the epicycles system. In that case, Tycho Brahe must have rediscovered retrograde motion and/or documented it to a new level of accuracy. StuRat 08:19, 8 March 2007 (UTC)

Thanks. I don't know why I didn't get an edit conflict warning when I posted my last question. --Allen 08:25, 8 March 2007 (UTC)

More precisely, it is quite easy to observe retrograde motion because the two inner planets, Mercury and Venus, never have a greater distance from the sun than 60 degrees. So, they move one direction, and after that (some months later), back. --Rwst 15:21, 8 March 2007 (UTC)

I wasn't really counting that as retrograde motion, although I suppose technically it is. I was thinking of the more subtle retrograde motion of Mars, etc. StuRat 17:03, 8 March 2007 (UTC)

Retrograde motion was long understood (it is easily observable in Mars) and was exactly the stimulus for epicycles, yes. Epicycles existed before the Ptolemaic system, though. And they were not discovered by Brahe, who came long after Ptolemy. --140.247.252.156 17:41, 8 March 2007 (UTC)

I believe that retrograde motion of planets has been known for a very long time - in fact, the word "planet" means "wanderer" because the ancients noticed that some of those little bright dots wandered about (forward AND backwards) where the majority of the stars only travel in one direction. SteveBaker 22:54, 8 March 2007 (UTC)

Surely "wandered" is because they wandered with respect to the stars, not specifically because they changed direction. --Anon, March 9, 00:44 (UTC).

Energy Supplements

Ive been doing a lot of weight training lately and running and I was wondering if there was anything good out there to give me energy. I'm taking my vitamins and everything, but I'm still always tired. I sleep for about 8 hours. Has anyone used hydroxycut or something else that worked well for them? —The preceding unsigned comment was added by 76.167.159.75 (talk) 04:04, 8 March 2007 (UTC).

Go see a doctor. Ocarina Cave Girl 04:58, 8 March 2007 (UTC)

I don't think many people are going to spend money on an appointment to ask about wanting to feel like you have more energy. I am rather skeptical of any energy-producing or fat-burning pills on television commercials, personally. Vitamins are good for you, don't let anybody tell you they aren't, but you can drop the fish oil and chondroitin sulfate if you have it. I'm sure somebody else can help you more than me. [Mαc Δαvιs] X (How's my driving?) ❖ 07:49, 8 March 2007 (UTC)

It might be a glycemic index problem. Sugars are turned quickly into energy, protein and starches are turned into energy over a moderate period, and fats are turned into energy over a long period. So, ideally each meal should be a combo of those sources of energy. Eating primarily sugar would guarantee a sugar crash when that energy quickly runs out, while eating only fats would leave you low on energy for hours until that energy started to kick in. Also, while not exactly healthy for you, caffeine can help to keep you awake. Just avoid consuming it in the afternoon or evening, or it may interfere with your sleep. StuRat 08:02, 8 March 2007 (UTC)

Sometimes the simple answer is the one we miss quickly. Eat more. This might sound like too quick an answer but you will find it works out very well. Try to eat alot of complex carbohydrates like those found in whole wheat bread and breakfast cereal. It's often a smart idea to have a small meal before a workout. A piece of fruit,some slices of bread and about a glas worth of skimmed/low fat milk can work wonders. Don't overdo it though, a heavy workout on a full stomach is asking for a sore stomach.

I would like to stress that a lot of people tend to forget to increase their nutrient intake when they start an exercise routine. Depending on how often you go to the gym or jog this could mean that you might have to almost double your caloric intake in the span of about a month. Though most of us won't need to increase our daily intake by that amount it might be a good idea to compare what you are taking in to what you are burning off. There are quite a few tables online which list the caloric value of many food stuffs. (which I can't be bothered to look up for you right now because I'm lazy)

Don't forget that it's not all about calories. It all depends where you get it from, most of it will come from complex carbs. You'll need plenty of protein to keep those muscles in tip top shape and a bit of (mainly unsaturated) fat because well we just need fat for alot of body processes. Besides, a diet completely devoid of fat is most likely hell on the tastebuds. You might also want to check out this website http://www.exrx.net .Good luck PvT 09:32, 8 March 2007 (UTC)

I find that occasional small snacks between meals help, especially if they have a lot of sugar :) Or you could just do slightly less each day :] HS7 19:16, 8 March 2007 (UTC)

Inductive Heating

We know that resistive components dissipate heat. Any idea why do we say that domestic electrical water heaters and iron boxes are inductive? Is it because of their design?Can it be eliminated?210.212.194.209

I would assume that it's because to save space, the resistance is looped back and forth so you don't get a super long piece of metal, but a coil like an electric stove etc. However, when you do that, it has induction. --Wirbelwindヴィルヴェルヴィント (talk) 05:41, 8 March 2007 (UTC)

See also the Inductive heating article. DMacks 16:31, 8 March 2007 (UTC)

Plasma TVs always have to be right side up or broken.

At Best Buy, they told me that Plasma TVs had to always be up and if it tilts too far to the right, lays down, etc. (you know when moving it and it's off) that it is broken for good because the plasma gets out of alignment and your entire TV gets permanent burn marks the next time you turn it on. I was told that for some models where if you wait 48 hours, the plasma will straighten out by then. Well I found nothing on google or Wikipedia about Plasma TVs always having to be upright or it breaks them. Anyone know anything about this or even heard of it? SakotGrimshine 06:01, 8 March 2007 (UTC)

Best Buy employees really seem to enjoy BSing, or generally making stuff up when they don't know something. According to the vast interwebs, the reason for transporting plasma TVs vertically is that the fragile screen is easy to break when they're horizontal (due to the weight of the glass pressing against it). [9] [10], etc. It's definitely something to keep in mind, but not for the reasons you were told. The plasma in a plasma TV consists of ionized (when the TV is on) xenon/neon gas. Turning the TV isn't going to have an effect on it. -- Consumed Crustacean (talk) 06:24, 8 March 2007 (UTC)

When we were setting up our 46-inch plasma part of the set up involved laying it face down on the glass. [Mαc Δαvιs] X (How's my driving?) ❖ 07:44, 8 March 2007 (UTC)

And I just read a shirt that said you know you're an engineer when... people at Best Buy can't answer any of your questions. --Wirbelwindヴィルヴェルヴィント (talk) 16:29, 8 March 2007 (UTC)

Missed periods

How many missed periods are usually taken as "nothing to be worried about" in an adult female? What are the causes and effects? I don't see a part in any of our articles on this! Am I missing it? [Mαc Δαvιs] X (How's my driving?) ❖ 07:41, 8 March 2007 (UTC)

I believe it varies by woman; some have very regular periods, while others have highly irregular periods. Also, athletic women can have their periods stop due to insufficient body fat, and some birth control pills are designed to interfere with the normal cycle. StuRat 07:52, 8 March 2007 (UTC)

do keep in mind that some women go into denial when they miss periods so that is why they start saying "its nothing to worry about" if anything i suggest a test =) also like sturat says maybe shes just to skinny. however most birth controls are ment to stableize the menstral cycle. the pills at the start stop her period while the pills at the bottom allow her to ovulate. but then again it depends on what kind you get (or since i assume your a guy what kind your girl gets)Maverick423 14:37, 8 March 2007 (UTC)

In this era of accurate home testing for pregnancy women don't just wait for their "friend" to arrive to confirm non-pregnancy after they have cause to think they might have become pregnant. Edison 15:47, 8 March 2007 (UTC)

yes true the test are very fast and can give peace of mind however they arnt always accurate. in a well personal issue we went through 4 test just to confirm that she wasnt pregnant. the first one didnt show any lines but see through imprints of them so we didnt know the result of that one. the second showed that she was. the third and forth showed she wasnt. over all outcome of all this. no kid =)Maverick423 15:56, 8 March 2007 (UTC)

I'm so..congr.... I give up. I never know which one people would rather have =P Is she just rather slender or taking birth control then? Don't worry if it's too personal or whatnot, but I'm curious about it for my future. --Wirbelwindヴィルヴェルヴィント (talk) 16:27, 8 March 2007 (UTC)

At the other end of the age range, it's apparently pretty difficult for a perimenopausal woman (or her doctor) to assess her fertility and her periods can become sporadic. Because ordinary birth control pills simulate normal hormonal cycles, they can mask some aspects of menopause and make it difficult to assess the true state of affairs.

Atlant 16:56, 8 March 2007 (UTC)

Weight Training and Fat Loss

I'm trying to lose weight and my trainer has me do a lot of cardio and weight training. Does the weight training reduce the amount of muscle loss while I am losing weight? —The preceding unsigned comment was added by 76.167.136.84 (talk) 08:02, 8 March 2007 (UTC).

Weight training increases your muscle mass. Muscle weights more then fat (it also burns fat for energy, basically). So if you're adding muscle and decreasing your body fat you may gain weight. You will want to keep a log of your body fat percentage if you're trying to lose weight (and by weight I assume you mean fat and not raw weight).--droptone 08:38, 8 March 2007 (UTC)

I can give you a quick answer on that question. Yes he's trying to reduce muscle loss due to all the cardio you are doing. The body becomes catabolic when it's glycogen stores are depleted and will start to break down and burn off the protein in your muscles. This is a bad thing, since you need those muscles to burn of fat. Largers muscles require more energy when active but also when in rest (see basal metabolic rate). Depending on how fast you wish to lose body fat you might be able to actually gain muscle mass, but this requires you to lose body fat very slowly. PvT 09:10, 8 March 2007 (UTC)

I like Richard Muller's articles on the subject.[11][12]. [Mαc Δαvιs] X (How's my driving?) ❖ 17:56, 8 March 2007 (UTC)

Spiriling Mathematical Vortex Phenomenom - name??

Hello, and thank you for your time.

I am trying to find information about including the name of a naturally occurring phenomenon which I saw once and I know it is somewhat well known. This is a mathematically related phenomenom, nothing to do with drugs, spiritulality etc.

It is a kind of spiriling vortex, cone shaped, made up of geometrical shapes.

It's size is not fixed, but imagine an ice-cream cone with the bottom chopped off, except the 'cone', the solid part was made up of non-connected geometrical/mathematical shapes, with spaces in between. It was spinning slowly, and was transparent in that the geometrical shapes seemed to be made of yellow light.

There is a name for this thing, other people have seen it, (I even saw it in a VISA card TV commercial but didn't manage to record it in time) but if you go looking for "spiriling mathematical vortex" on the net you get a million hits about scientists discussing the movement of particles in vortexes, I can't find it in the mess, hence asking you guys who might know about it.

What I mean by geometrical/Mathematical shapes was something like the 3d blocks in the game 'block-out', like 3d tetris blocks, all different, but they all had some relationship with each other, so the whole thing gave the impression of forming a completed mathematical formula, sort of like if you represented the equasions of relativity geometrically.

If anyone knows the name of this thing or anything about it could you please email me at (email removed)

Thank you. (Email removed) (David J Ritter) P.S. I don't care if my email address is public, I'm open, please publish it. —The preceding unsigned comment was added by 198.142.40.245 (talk) 08:54, 8 March 2007 (UTC).

is it based on the golden mean or similar?172.161.102.213 10:47, 8 March 2007 (UTC)

I'm going to go ahead and remove your email anyway, I'm pretty sure the rule here is not just if you 'care or not', we care:). Feel free to have your email on your user page, but not here please:). As for your answer, it's not some sort mandlebrot set ? Vespine 21:54, 8 March 2007 (UTC)

Animal species: how do they self identify for mating?

I'm wondering how animals know what species to mate with? They don't know what species they are, so how do they recognise their own species to mate with? Thanks.Mjm1964 09:31, 8 March 2007 (UTC)

Phermones is related. How do they know what species to mate with? Well, how do you know what species to mate with? Would you mistake an orangutan for a sexy woman? Perhaps this is also related. [Mαc Δαvιs] X (How's my driving?) ❖ 10:13, 8 March 2007 (UTC)

Davis has a point. Humans are wired for facial recognition. I assume a dog is hard-wired to tell if a mammal is a dog, and which dog it is.

There are examples of subviral agents which transfer via conjugation of host and potential host.[13]172.161.102.213 13:12, 8 March 2007 (UTC)

Most animals use pheromone cues. For example, rodents have proteins in their urine (called Major Urinary Proteins or MUPS), saliva and tears that bind tightly to small volatile chemicals. The proteins are thought to stablise the chemicals so that their "smell" is held in urine (and the other excretions) much longer, allowing them to be sniffed by members of their own (and other) species. These chemicals and the proteins are sexually dimorphic, in that different sexes have different combinations (as do different species, obviously). Therefore by detecting and interpreting the "code" of chemicals and/or proteins from the urine, tears or saliva of other conspecifics, males can distinguish between other males (which they are genetically hardwired to fight) and females (which they are genetically hardwired to mate). Interestingly, the organ that detects pheromones, called the vomeronasal organ, is essentially missing in most Catarrhini, including humans. Its likely the evolution of trichromatic vision superceded the use of chemical cues to detect mates, and that is why we watch porn these days instead of smelling it. Rockpocket 04:41, 9 March 2007 (UTC)

Ductility of Uranium

See above...--Howzat11 11:18, 8 March 2007 (UTC)

Googling Ductility of uranium seems to suggest it has high hardness and low ductility making it difficult to roll out into foil. If you want more specific metrics, searching through some of those sites may yield an answer. Vespine 21:46, 8 March 2007 (UTC)

Look mum! No hands!

Is it possible to masturbate without laying my hands on my manhood. Please do not answer back with "get someone else to lay their hand on your manhood." Prehaps I should change the question to Is it possible to ejaculate without touching your manhood. 220.239.111.36 11:47, 8 March 2007 (UTC)

• It depends on how sensitive you are and how much time you are willing spend. For example dry humping can be done without using your hands and there are people who can masturbate and ejaculate with thought alone. A Google search turned up this site for more information on different techniques. - Mgm|^(talk) 11:54, 8 March 2007 (UTC)

Some women can orgasm just by thinking about sex. I don't think men are that lucky.172.161.102.213 12:43, 8 March 2007 (UTC)

• This is known as Psycholagny, although WP doesn't have much of a page for it. —The preceding unsigned comment was added by 130.184.111.192 (talk) 13:13, 8 March 2007 (UTC).

• see masturbation "A less common technique is to lie face down on a comfortable surface such as a mattress or pillow and rub the penis against it until orgasm is achieved"

It is possible to have an orgasm without any external movement or friction, by pulling on the muscle that controls urination and contracts during orgasm. I won't embarrass myself by trying to identify its proper name, but you probably get the idea. For this method, you will need lots of mental stimulation (usually your preferred type of pornography), lots of time (up to an hour) and lots of energy. Age is a factor as well. Mjm1964 13:27, 8 March 2007 (UTC)

Kegel exercises ? StuRat 16:55, 8 March 2007 (UTC)

There was a scene in American Pie I believe where it happened twice. Around that time someone claimed the same thing when meeting Brittney Spears in real life (this was back when she was 17). SakotGrimshine 15:32, 8 March 2007 (UTC)

It is theoretically possible for a man to orgasm strictly from direct prostate stimulation. --DrGaellon (talk | contribs) 17:35, 8 March 2007 (UTC)

See Frottage. Corvus cornix 22:31, 8 March 2007 (UTC)

I am skeptical of being able to orgasm at will without any stimulation. I don't think so. I'd like to see scientific evidence on that first! Ways to masturbate without "laying your hands on your manhood" would include: prostate milking/prostate massage, water pressure (say, from a showerhead, friction against other objects, and... I had a few more but this window was minimized for 5 hours and I forgot. Whoops! :) [Mαc Δαvιs] X (How's my driving?) ❖ 01:16, 9 March 2007 (UTC)

A wet dream would appear to meet the criteria (plus kudos for the question title, best in a while). Rockpocket 04:23, 9 March 2007 (UTC)

Aerosol Deodorant Cans

Are these still harmfull to the ozone? I usually refrain from buying them but a friend recently said that most companies "fixed the problem up".

I believe they have removed the CFCs, yes. But aerosol cans still aren't that good for the environment because they still release the propellant gas into the environment. Other types of deodorant are better, and pumps can be used for hair spray, etc. StuRat 13:22, 8 March 2007 (UTC) StuRat 13:20, 8 March 2007 (UTC)

Correct, no CFCs in anything now! They even changed my asthma inhaler recently so that it no longer used CFCs as a propellant. It was one of the few uses of CFCs left. --BenBurch 14:41, 8 March 2007 (UTC)

Most of the CFC's have been replace with HFC's which are still "global warming gases" but the mechansism that was proposed to explain ozone depletion only has chlorine as the destructuve chemical. There is still some concern however as the "ozone hole" has not reduced as expected since the reduction of CFC's and the models all had a very fast predicted recovery (it should have been very noticeable by now). --Tbeatty 14:58, 8 March 2007 (UTC)

There has also been studies that show ozone levels have rebounded, there being more than before, although that may have been me just looking at the certificate of stability[14]. Atmospheric ozone is measured in Dobson units, named for Gordan Miller Bourne Dobson, who invented the spectrophotometer, which was used to measure atmospheric ozone from the ground. There was a significant increase in the number of devices in 1956, when the Halley Bay anomaly in Antarctica was discovered. The anomaly however, was a November increase, in ozone levels over antarctica, this was three years before the big scare. To quote G. M. B. Dobson, "Forty years' research on atmospheric ozone at Oxford: a history," Appl. Opt. 7, 387- (1968) "the values in September and October 1956 were about 150 [Dobson] units lower than expected. ... In November the ozone values suddenly jumped up to those expected." Research is disputed over which bands of UV are more or less carcinogenic. De Fabo et al, Eureakalert, conflict for melanoma, and the 320-400 nm band UV is not blocked by the ozone layer, therefore, many would argue if we should even care at all, since it is all seasonal. Every instance of a visible ozone hole in the TOMS monthly average, has been in September. If that's not seasonal what is? [15][16][17][18][19][20][21] We also find exactly as much ozone that was missing in an "anti-hole," in, guess when? March! This reminds me of solstices and equinoxes[22][23][24][25][26][27][28]. The line looks pretty constant[29][30], although sometimes I wonder where the data went, with 2004 to 2005 changes like this[31][32]. So, there's the other side of the whole thing for you.

Spray Deoderant also has the problem of getting everywhere, probably costing more, and taking up more space than a stick. I heard to avoid stick deoderants with aluminum because it causes breast cancer even in men (and it happened to Isaac Hayes) -- this later may be incorrect at least as there's nothing in Isaac's wikipedia article, just something in the deoderant article about aluminum being a neurotoxin. SakotGrimshine 15:29, 8 March 2007 (UTC)

Oh please, when one study comes out that says something is carcinogenic that hasn't even gone through any peer review, that's called scaremongering. People love to share juicy scary stories and urban legends, and that's why this myth was perpetuated on the Internet so much. NCI [Mαc Δαvιs] X (How's my driving?) ❖ 17:40, 8 March 2007 (UTC)

Aluminium is carcinogenic? But most modern things are made from aluminium :) Althought there is a lot more cancer around recently :( HS7 19:15, 8 March 2007 (UTC)

Physiology Videos

Just wondering if anyone could help by suggesting an sites/places(torrents) to get medical physiology videos? If they cover such topics as respiratory/nerve/muscle physiology etc.?

Much appreciated.

If there is a science torrent tracker site... *twitch* I want it! For text and audio, you can just type in "physiology torrent" in Google, Yahoo, The Pirate Bay[33] and Torrent Locomotive. But I actually have been searching for medical science videos recently, and found nothing. Any help would be doubly appreciated.[Mαc Δαvιs] X (How's my driving?) ❖ 17:50, 8 March 2007 (UTC)

I would suggest you do a search for Opencourseware looking for physiology courses. For example, Berkeley University have done an excellent videoed general human anatomy course that includes some physiology, although probably not in enough depth for you. But other universities are also videoing lectures and putting then on the internet. Hexane2000 06:50, 9 March 2007 (UTC)

A moon of a moon

Would it be theoretically possible for a moon to have a moon of its own? Say, something the size of Phobos orbiting something the size of Ganymede orbiting soemthing the size of Jupiter? Battle Ape 14:11, 8 March 2007 (UTC)

• When the Apollo crafts orbited the moon, they were satellites of a satellite. Just imagine a rock the same size as one of those ships. — BRIAN0918 • 2007-03-08 14:13Z

Entirely possible. The question is how stable are those orbits over millions of years? And the answer is "not very". This is why we don't see any moon-on-moon action here in our solar system though I would venture a guess that there HAVE been moons of moons during its history, and will be again. --BenBurch 14:40, 8 March 2007 (UTC)

It's worth noting that this isn't a terribly different scenario than a Sun-planet-moon system. The key consideration (discussed at n-body problem) is that the smallest body must have a mass insignificant with regards to the largest body. It's also worth noting, while we're on the subject, that the Sun-Earth-Moon system doesn't meet this criteria. Isaac Asimov notes (I believe in The Double Planet) that the Moon's orbit, observed from the Sun, is always concave about the Sun, a characteristic not shared by any other moon but shared by every other planet / minor planet. Some basic discussion of this can be found at [34], [35]. It's not directly relevant, but it may be interesting. — Lomn 16:19, 8 March 2007 (UTC)

Did you mean "the Moon's orbit, observed from the Sun, is always concave about the Sun"? Have I misunderstood what you mean by 'concave'? Surely what is special is that the Moon's orbit never doubles back on itself. It still has to be convex (if I understand how you're using concave) sometimes, as the Earth and the Moon orbit the sun with their paths 'weaving'. Both the Earth and the moon have to have a 'convex' orbit sometimes. Skittle 01:13, 9 March 2007 (UTC)

Moon on moon action. Nice. —The preceding unsigned comment was added by 199.197.124.144 (talk) 16:57, 8 March 2007 (UTC).

A similar situation may be where the smallest object is in a Lagrange point relative to the two larger objects, specifically Lagrange points 1 and 2. StuRat 16:34, 8 March 2007 (UTC)

This question came up not so long ago... You might want to check the archives for the past couple of weeks. SteveBaker 16:54, 8 March 2007 (UTC)

That was the question I asked :) Don't bother looking in the archives, I got the same answers as those above :( HS7 19:13, 8 March 2007 (UTC)

about the PTSD

what this the risk factor of this post traumatic Stress Disorder?how about the clinical picture of it? —The preceding unsigned comment was added by 196.218.135.2 (talk) 15:59, 8 March 2007 (UTC).

The Wikipedia page conveniently titled Post Traumatic Stress Disorder is a good place to start. I assume you searched the website before asking on the Reference Desk, right? DMacks 16:05, 8 March 2007 (UTC)

Looking for source

I've found there's an entry for Paul L. Kirk in volume 56 of the "National Cyclopedia of American Biography", but unfortunately my local academic library doesn't cary it. Can someone who has access send me a copy of the text and the info I need to properly cite the book? On a side note, I know of the existence of Wikipedia:Newspapers and magazines request service. Is there a similar service for books? - Mgm|^(talk) 16:56, 8 March 2007 (UTC)

Calculating errors

I've got several sets of experimental data, and am trying to find the total error inherent in reading this. I've found the pressure acting on an area using a millimetre-graded ruler and an accurate forcemeter, so the error inherent in the ruler is ±0.0005 m, while the error measuring the force is ±0.005 N. However, when I find the confidence in the pressure readings by the formula p=F/A, I get ±20000 Nm^-2, which is way larger than any readings taken! Surely the experiment cannot be this inaccurate, given that all the results form a good line of best fit. Laïka 17:29, 8 March 2007 (UTC)

[36] might be useful, specifically the final formulas at the bottom of the Multiplication and Division sections. It's the same way I've been taught to do it in my first-year Physics course. -- Consumed Crustacean (talk) 17:40, 8 March 2007 (UTC)

[37] would be my recommendation. Basically if C = A / B and you know the error in A is eA and the error in B is eB then the error in C (eC) is given by: (eC/C)² = (eA/A)² + (eB/B)² - so the magnitude of the error depends on the magnitude of the data. This means that strictly you need to calculate the error bounds for each data value - although in a lot of scientific endeavors, it's enough to plug in 'typical' values for A, B and C to get an idea of the 'typical' amount of error - since your error terms are somewhat estimated anyway. (eg: If your millimeter ruler is not temperature-compensated then the result you got using it depends on the temperature when you used it - that adds more error that you hadn't included in your estimate). SteveBaker 17:53, 8 March 2007 (UTC)

Thanks for those links; they've helped a lot! Laïka 21:01, 8 March 2007 (UTC)

Broken solar water heaters

Does anyone here know of a way to find cheap broken flat plate collectors to use for an experiment/project? I have already tried eBay. -User: Nightvid

Maybe you can build one from scratch. It should just be a hose, some plexiglass, and a bunch of insulation, in a box. Or you can look at Froogle. Nimur 18:54, 8 March 2007 (UTC)

The experiment I am working on is about the potential for modified low-tech (non-evacuated, non-concentrating) solar collectors to reach temperatures in excess of 200 or 220 degrees Celsius (with no water of course). I need something like at least the parts or pieces of parts (fragments) for a commercial collector, but on a two-digit (USD) budget. Plexiglass and most other plastics melt at too low a temperature for my purpose. -User: Nightvid

First commercial portable data projector?

Middle school teacher (and his student) getting lost in too many types of data projector for research project, having trouble figuring out when the first portable data projectors hit the market, and related ideas -- cost, etc. Anyone help us find our way to the relevant article? Thanks... Jfarber 18:49, 8 March 2007 (UTC)

Overhead projector? Perhaps you mean projector...? Nimur 19:05, 8 March 2007 (UTC)

We do indeed mean the latter -- the computer projector. Sadly, however, there is no HISTORY section in that disambiguation page, and there's no single page about the type of thing we're looking at, as there would be in articles about other objects / object types which have evolved over time. The closest I can find is this section of the LCD Projector page -- but while the section is labeled "history", there are no real dates here. The article needs to be overhauled, I'd say -- I'd even vote for a page about computer/digital data projectors instead of the disambig page -- but in the short term, the student would like some help finding the relevant historical/timeline-esque information. When did the first data projector that was NOT for use with Overheads hit the market? When did they become portable? Who was first? Heck, even a google search of "first data projector" only finds company-specific examples...is this really so rare a tpic that there's no good history out there? Jfarber 19:10, 8 March 2007 (UTC)

I fear you will need to do original research on this one. Go to a library and look at back issues of PC Week or a similar magazine and check the advertizements. Step back in one-year increments (e.g., look at the first issue each year.) You may get lucky and find a feature article in PC Week also. -Arch dude 21:37, 8 March 2007 (UTC)

It would be easier, in my opinion, to find the patent of a current projector and then step through the patents it references on Google Patents. --140.247.252.156 21:58, 8 March 2007 (UTC)

Last call...Really? No one? Interesting that such an obvious and ubiquitous object in modern culture would have none of the information usually associated with other evolving technologies in its Wiki-presence. The topic isn't that obscure -- every business or educational setting I've encountered in the last decade knows what these things are, and covets more.

I don't think it's 7th grade-level work to ask my student to sift through old magazine archives, nor do I think she'd make much sense of Google Patent, though that was a great idea, and thanks for it. I guess if no one else steps forward, we'll make the teachable moment work for us. In the long run, maybe I'll do the research and write the entry -- I can't be the only one out there who would find this information useful. Jfarber 00:45, 9 March 2007 (UTC)

Does size matter?

My friend says that larger bananas have been forced to grow to that size and therby spread their nutritional value through a larger mass. Thus she says a smaller banana is better value since it contains the same quantity of vitamins but weights less and therefore is cheaper. Is this true? --Seans Potato Business 19:24, 8 March 2007 (UTC)

• It's true smaller bananas are generally cheaper, but to grow larger a banana needs more nutrients, so it wouldn't be spreading the same amount of nutrients through a larger mass. - Mgm|^(talk) 19:51, 8 March 2007 (UTC)

Experiment time: if sugar is considered a nutrient, then the smaller banana should taste sweeter than the larger one. Does it? --Bowlhover 21:33, 8 March 2007 (UTC)

I wouldn't say "larger bananas are forced to grow to that size." That sounds like "baby ducks, bunnies, and pandas are forced to.." jeez! The bananas got to their size and taste through genetic engineering and selective breeding. There are also, different kinds of bananas that taste different. [Mαc Δαvιs] X (How's my driving?) ❖ 22:02, 8 March 2007 (UTC)

Also, a larger banana has a greater ratio of flesh to peel, so I would say that larger bananas are a better value, if they are sold by weight. ^tucker/_rekcut 22:32, 8 March 2007 (UTC)

I've heard the phrase 'force-grown' quite a lot in newspapers, etc. It seems to be used to mean 'grown artificially out of season' - at least, that's what a quick google and our force (disambiguation) page say. I can't find a good source to lend some authority and detail, though. I'd assume that it means that the food is grown with fertilizer for its size and appearance, rather than in good soil for taste and nutrition. I don't think it's a rigorously defined term. --HughCharlesParker (talk - contribs) 22:49, 8 March 2007 (UTC)

Ah, I see. Thanks for that. [Mαc Δαvιs] X (How's my driving?) ❖ 23:55, 8 March 2007 (UTC)

separate populations and species

i am look for information that can help me answer a question. Factors can separate population and species —The preceding unsigned comment was added by 208.233.37.66 (talk) 20:41, 8 March 2007 (UTC).

Well, it sounds more like a statement more then a question but the answer is definitely "Yes", factors can indeed separate population and species. Information that can help answer that 'question' can most likely be found in the speciation article. If you mean What factors can separate population and species", then that article will still help.Vespine 21:26, 8 March 2007 (UTC)

March 9

info photocopiers

Where can I find out how to construct a primitive photocopier? Nate Bernhardt 00:32, 9 March 2007 (UTC)

Here is one built out of Lego...it's pretty darned primitive! http://mindstorms.lego.com/eng/inventions/image.asp?img=14155image1.jpg

But it doesn't work anything like a real photocopier does. These days you might as well use a computer scanner and a printer. SteveBaker 01:26, 9 March 2007 (UTC)

Plane refuelling

File:Flight.JPG

When you have two planes of different size that have just refuelled, with a photo taken from above, and the planes no longer overlap, how can you tell which was the source of fuel? Is it always the larger plane providing fuel for the smaller one? Or is the one in front always providing the fuel? (that would mean there is a rule that you cannot directly "overtake" your refueller, only veer away from it sideways) Thanks for answers. Samsara (talk • contribs) 00:47, 9 March 2007 (UTC)

USAF C-5 approaches a KC-135R

You mean with in-flight refuelling? Generally the larger one is the tanker - and the small one is a fighter or a smaller bomber or even a helicopter - but (as you can see from the photo) they refuel C-5 Galaxies (the largest American military transport and one of the largest military aircraft in the world) from a KC-135. The Galaxy has a wingspan of 222 feet and a length of 247 feet - the KC-135 is just 136 feet long with a wingspan of 131 feet. So you certainly can't go by size if both aircraft are bigger than maybe 100 feet across. When they are transferring fuel, the plane in front is always the one supplying the fuel - but you said that you needed to know this after they have separated. Generally the aircraft that just refuelled falls behind and does a diving turn away from the tanker - but if the aircraft that just got a fill up is a fighter - it might well dive below and then out-accellerate the tanker - so once they are safely separated, it could easily wind up in front. Is there a particular reason for your question? Maybe I can offer more help. I design flight simulators for a living - we do a lot of training of US and other airforce pilots - and that includes in-flight refuelling exercises. I've actually done the manouver several times in our simulators - it's pretty scarey. SteveBaker 01:06, 9 March 2007 (UTC)

I'm not much of a virtual pilot but I've tried to do the manouver in Falcon 4.0 a couple of times, haven't managed to nail it yet. Even a simulator gives you a good appreciation of the surgical like precision with which fighter pilots must control their multi ton multi million dollar super sonic vehicles... As to the question, the one with the dangly thing is usually the source of the fuel. ;)Vespine 01:17, 9 March 2007 (UTC)

Yes, I can get a screenshot. Hang in there. Samsara (talk • contribs) 01:17, 9 March 2007 (UTC)

See above. Samsara (talk • contribs) 01:23, 9 March 2007 (UTC)

If you think it's tough in a fighter - you should try it in a helicopter! (Hint - you really don't want to hit the boom with your rotors - and the tanker is flying so slowly it's about to stall out and your poor helicopter is going absolutely flat out...which isn't good when you are low on fuel!) The manouver is actually quite a bit harder in a simulator than in reality because you don't have the depth-perception cues to get you accurately aligned with the refuelling probe - and on a PC-based simulator, your lack of peripheral vision is kinda annoying. The main hint I would give you is to pay attention to the 'director lights' underneath the tanker - they guide you into the right flight path and speed - then you just have to use a light touch on the stick to get the probe into the drogue. SteveBaker 01:32, 9 March 2007 (UTC)

Actually, that's just reminded me of this great video I saw ages ago, didn't take a lot of looking to find it. Pretty amazing and I bet a little scary! Vespine 03:29, 9 March 2007 (UTC)

Artificial life

I was watching a lecture by Peter Ward (The Undesigned Universe: Part 3: The Construction of the Cosmos) here [38] and at 33:34 into it, Ward mentions something about a scientist who is trying to build artificial life and got a grant from Princeton University to do it. I can't make out his name when it's mentioned from the video. Does anyone know who he mentioned? Imaninjapirate^{talk to me} 03:11, 9 March 2007 (UTC)

This [39] artificial virus (a bacteriophage) was made in 2003. There is some debate about whether viruses should be considered 'alive' - but this one does reproduce. The same guy is trying to do the same thing with a bacterium [40] SteveBaker 03:25, 9 March 2007 (UTC)

Question regarding bacteria.

I have heard somewhere that simple celled animals (like, say, amoeba) can't grow larger than a quarter than starving themselves. Does this apply to bacteria? Raptor Jesus 04:08, 9 March 2007 (UTC)

Yes, because bacteria only have one cell. Unicellular organisms can, however, grow much larger than you might expect by becoming extremely skinny. --Bowlhover 05:22, 9 March 2007 (UTC)

Hmm... then how could bacteria evolve into an organism, if the theory is correct? Raptor Jesus 06:03, 9 March 2007 (UTC)

Bacterial colonies, very likely.--Pharos 06:23, 9 March 2007 (UTC)

Bindeez

How do Bindeez work (the colourful beads that join together with a spray of water, sold as a kids art toy)? The websites I go to don't give me any explanation for their joining-together-with-water abilities other than "magic". --Candy-Panda 05:59, 9 March 2007 (UTC)

Well, that's because it is magic; what more did you expect? [Mαc Δαvιs] X (How's my driving?) ❖ 07:04, 9 March 2007 (UTC)

Rise in temperature

Why is there a rise in body temperature after keeping small onions under the armpit for sometime??? —The preceding unsigned comment was added by 59.92.19.220 (talk) 09:25, 9 March 2007 (UTC).

Hole punch things

What are the pieces of paper that are punched out using a hole punch called? Thanks, Bioarchie1234 10:27, 9 March 2007 (UTC)