Wikipedia:Reference desk/Archives/Science/2013 January 11

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January 11

Bonus question: the Mola Mola 'Niche'?

The more I think about it, the greater it seems that as grazers of the ever-abundant jellyfish, sea turtles and the Mola Mola have converged on a r-selected niche with bodies adapted for low-energy stability in the water column. Is there any mention of such a niche, and would there be any mesozoic creatures, perhaps reptiles or cephalopods that fit it? Thanks. μηδείς (talk) 01:38, 11 January 2013 (UTC)

Plesiosauria? --Jayron32 01:44, 11 January 2013 (UTC)

Along those lines, but the elasmosaurs are usually portrayed as darting after fish and the pliosaurs are more like carnivorous whales. I'll have to get a good illustrated book on the marine reptiles from the library, anybody have suggestions? μηδείς (talk) 03:55, 11 January 2013 (UTC)

If I understand your question correctly, the nautilus seems to fit all your criteria: lays lots of eggs, neutrally buoyant, around since before the Mesozoic, and a cephalopod.--Wikimedes (talk) 10:51, 11 January 2013 (UTC)

Yes, it was thinking or the nautilus that made me mention cephalopods, but they eat carrion. Still, similar in several ways. I am not sure if there's an easy way to tell exactly whether mesozoic forms ate jellyfish or not though.

Some species of jellyfish may also fit the bill (see Jellyfish#Predation). The other predators mentioned (except sea turtles) are pretty active.--Wikimedes (talk) 21:06, 11 January 2013 (UTC)

Last grenade question, I promise

If a grenade detonates inside a concrete pillbox, is it plausible for the blast wave to reflect off a wall and travel around a corner to hurt/stun or even kill an occupant despite him not having a direct line of sight to the point of the explosion? (No, I haven't changed my mind about bouncing the thing off the walls and around the corner -- I'm pretty sure that can be done with no more than two bounces -- but if it lands short, would it still be capable of hurting or even killing the gunner?) 24.23.196.85 (talk) 04:35, 11 January 2013 (UTC)

http://www.fema.gov/library/file?type=publishedFile&file=fema426_ch4.pdf&fileid=45ea8a10-65bb-11db-8645-000bdba87d5b

(Search on "Reflect")

Also see: Blast wave --Guy Macon (talk) 06:37, 11 January 2013 (UTC)

(ec)

I'd say it's even more effective than relying on fragments to ricochet at the angle needed to hit the victim. Concrete walls will probably be as close to perfect mirrors WRT sound as they come on a WWII battlefield. With fragments, you need to get lucky. With pressure shock, it's just cold hard mathematics (followed by quite messy forensics). I'd really hate to get caught in the focus of some concave wall... - ¡Ouch! (^{hurt me} / _{more pain}) 07:20, 11 January 2013 (UTC)

The next one to ask a grenade question will have it thrown back at them! Just kidding.

Think of the pressure wave as if it were sound (which, it technically is!) - sound would bounce ("echo") from a concrete wall very well - and so will the blast wave. Sound has very long wavelengths and will also refract through doorways and outwards as it leaves your short corridor. SteveBaker (talk) 07:30, 11 January 2013 (UTC)

Concrete walls are pretty good acoustic mirrors, sure - but explosive shock waves are often supersonic - hence shock wave - so intuition may not lead to the correct conclusion. In shock, pressure waves do not superimpose in a straightforward way. So, while I agree with Steve, the pressure-front will expand, and will reflect; but we need to tread carefully if we use any simplifying assumptions about exactly where the reflections go, or how strong they will be. For example, an explosive front doesn't propagate at the sound speed. And the intensity doesn't fall off with the square of the distance. (Both are pretty good equations for modeling sound waves). There's an incredibly huge volume of published research - entire text-books - on the subject. The interested readers can start browsing articles and links from, e.g., detonation; deflagration to detonation transition.

Now, as far as a reliable source specific to warfare, I recently read through most of 'Sharpening the Combat Edge', "THE USE OF ANALYSIS TO REINFORCE MILITARY JUDGMENT", written by the commander of the 9th Infantry Division in southern Vietnam in 1968 and 1969. This takes a totally different, but equally-analytic approach: instead of trying to derive blast-radius from first principles of physics, the authors statistically studied the actual effects of the explosives they encountered during combat: and then performed fact-based and statistics-based analysis to determine things like blast-radius. There's a chapter on mines and booby-traps: " approximately three-fourths of all devices were trip-wires attached to a grenade..." As the commander of the infantry division notes, it's important to know this simple fact: how far away from a grenade is "safe"? "The advantages of an analytical approach are demonstrated by setting optimum distances between men based on simple field tests with the most frequent types of traps. If this distance was maintained, multiple casualties were infrequent. ...The 25th Division elaborated upon this type of analysis by placing the data on their computer, thus giving them the capability to present and study the problem with minimum clerical effort." As a computer-enthusiast, I am absolutely astonished that a combat infantry division, staffed primarily by conscripted riflemen, was operating a computer in the field ... in Viet Nam ... in 1967. Forward-thinking! Innovation manifests itself in the most unexpected places... Nimur (talk) 15:49, 11 January 2013 (UTC)

Another way to look at the lethality is that 7oz of TNT produces about 0.6 MJoule of explosive energy and about 3MJoules of heat. The resulting shockwave leaves the surface of the explosive at about 15,000 mph. In a very enclosed space (and a pillbox is about the most enclosed space imaginable!) with efficient reflectors (reinforced concrete!) - where will all of that energy end up? An easily deformable/compressible human body will end up collecting a good proportion of it one way or another. SteveBaker (talk) 16:51, 11 January 2013 (UTC)

Thanks, everyone! So I take it as a yes. 24.23.196.85 (talk) 01:40, 12 January 2013 (UTC)

Death

When do children know that humans are mortal? When do they know that they will eventually die, and never live again? I've found two unreliable websites that claim children begin to appreciate the finality of death when they're around 10 years old. I'm young enough to remember some of my childhood, and that seems extremely implausible--I remember thinking about murder and suicide around that age, and definitely didn't believe either was temporary. --140.180.240.178 (talk) 04:36, 11 January 2013 (UTC)

It will depend greatly on culture, the attitude of parents, and the child's environment. I grew up on a farm and definitely understood death and that life doesn't go forever as far back as I can remember particular animals dying, at about 5 years of age. Children who have fragile pets such ginea pigs will certainly understand it. What might be harder to figure out is at what age children assign a level of distress to people, mammals and birds they know dying, as distinct from merely accepting that the dead person/mammal/bird/etc has had life extinguished and won't be back.

In management training, I was taught that there are 5 distinct stages of grief that people go though whn receiving bad news, always in the same order. Depending on which book you read, they are something like denial, anger, bargaining, acceptance, conversion. See http://en.wikipedia.org/wiki/Five_stages_of_grief. Some people pass thru one or more stages almost immediately - some people stay in one stage for a long time - even months or years. It may be of greater value to ascertain how children at various ages go thru the 5 stages, rather than over-simplifying it to understanding/not understanding the finality, as I would think that a child old enough to talk fluently can understand simple concepts like life extinguishing of life - that can be a young as age 3. But I would not expect a 3 year old to easily cope with the death of a parent or sister and readily understand they have gone for good.

I have known an 8 year old, upon the death of a pet rabit, to cry and suffer considerable distress - she certainly understood that rabit was gone. But the following day she was fine.

The concepts of life after death, reincarnation, and going to heaven/paradise in almost all major religions indicates that even mature intelligent adults can have difficulty with accepting death as the end - it isn't meraly a matter of consoling the bereaved.

Wickwack 120.145.137.176 (talk) 05:06, 11 January 2013 (UTC)

• Pure OR, but my nephews started asking about death when they were three, and the elder announced at four he wanted to be a fossil when he died, which let him be okay with the subject. (I had given him a fossil trilobite and explained it was a real animal that had lived very long ago. He concluded that meant it was dead without me having to tell him.) They still ask questions at five and seven but they certainly seem to have realistic views for their ages, despite the scary, pernicious, age-inappropriate, believe-or-you-will-go-to-hell religious comments of one of their grandparents μηδείς (talk) 05:34, 11 January 2013 (UTC).
• Pure OR again: I understood the permanence of the death of an animal (a lamb that I saw die) at the age of 31⁄2. I have only the faintest recollection of the event, but I was subsequently reminded of it several times and thus renewed my memory. I don't think I'd have coped easily with the death of a human at that age -- fortunately no-one close to me died until I was 10, and I can still recall the shock, but I coped because I'd been prepared for the event. I think it also helps if people around you are coping. Dbfirs 13:09, 11 January 2013 (UTC)
• Yet more OR. My daughter is ten and has had her family tree pruned repeatedly since her birth. Before three or four, she had no concept that the other person was gone - not sad at the funeral, doesn't ask where they are, has no current memory of them. By around five, she began to worry about her mortality and that of her parents, but it was somewhat disorganized (What happens to my toys if you and mommy die? What do you see when you're dead? How do you know if someone else is dead?) By seven, she had the full response that you'd expect an adult to have: anger, sadness, disappointment, grief, etc. Having gone through it so often, though, I sometimes wonder how much of her grief was just mimicking those around around her to better fit in. For that matter, how would anyone react to death if their culture hadn't already told them how such things get expressed? Matt Deres (talk) 15:01, 11 January 2013 (UTC)

This preview of The Concept of Death in Early Childhood gives an overview of previous studies on this subject. It appears to support the 10 year-old age quoted by the OP, but it seems to depend on the definition of "the awareness of the universality and irrevocability of death". Alansplodge (talk) 19:01, 11 January 2013 (UTC)

I was aware of the universality and irrevocability of death at 7 or 6, and was terrified of nonexistance. (though also realizing that, after nonexisting, you won't be scared anymore). I also estimated that, since world population rapidly increases, assuming most people don't die young (not true in real life), and barring an unbelievably late year that humans hadn't existed yet (cause people would probably be telling me about it, like "3 lifetimes ago there were no lifetimes before that") at least a half to 2 trillion years of human life have happened (cumulative), including all living persons' future lives. Finally I decided, God would provide a Heaven. That lasted about one year, till I thought that there's no absolute 100.00000000000000000000000...% guarantee that I won't be in Hell starting this very second, and burn in fire for all eternity, so this reality could be like a false-vacuum (though I had never heard of that). And that since the downside is infinite, even with only an infintessimal chance, even less likely than everything false-vacuum transitioning to a non-hell reality this second and staying for all of eternity, this is something to worry about. Sagittarian Milky Way (talk) 06:27, 13 January 2013 (UTC)

When I was 7 I was afraid I would die soon, because I found it odd that I was only 7 while most people I knew were much older. Later in life I changed my view about death. Once you accept that time doesn't really exist, you are led to the view that death is relative. You won't die, you can only see other people die. There are people in the year 2300 who are reading this very thread from an ancient Wikipedia database. From their perspective we are all long dead, but from our perspective they don't exist. Count Iblis (talk) 22:09, 14 January 2013 (UTC)

When I was five or six years old, watching Superman on the "tube" as it then was, I understood about actors but not stunts; so I wondered about all the actors who got "killed": how did they get paid if they were dead? —Tamfang (talk) 06:29, 2 July 2013 (UTC)

hydraulics question

This concerns my previous question about infinite-tensile-strength containers. Can we use this principle:

http://www.dynamicscience.com.au/tester/solutions/hydraulicus/hydraulicsforceandwork2.htm

To keep being able to add pressure at an ever slower rate, but without having to push ever harder? Assume you have access to materials of infinite strength, tensile strength, brittleness, whatever you want. I am just interested in whether in theory you can always convert a reasonable force into increasing pressure. Is the limitation only the materials at hand? --91.120.48.242 (talk) 13:28, 11 January 2013 (UTC)

Let's suppose you can push your finger on the piston with about 1kPa of pressure (that's like lifting a can of soda with your fingertip) and with a fingertip area of 1 square centimeter. Let's suppose you need to get up to 1000MPa - which is what you'd need to fill your hypothetical pneumatic tank the size of a regular car gas tank and with the capacity of some hypothetical non-liquifying gas that would give your pneumatic car roughly the same range as a regular car.

Well, to get from 1kPa to 1000Mpa - you'd need a million-fold increase in pressure. You suggested to me on my talk page (please don't use that for ref desk-related questions!) that you had in mind some number of pistons connected end to end, each with a cross-sectional area 10x larger than the one before it. So let's go with that - and let's be generous and neglect thinks like leaks and friction and temperature changes and such like. Hence, to get from 1kPa to 1000Mpa, there would need to be six pistons, each 10x thinner in cross-section than the previous one...well, if the low pressure cylinder has the same area as your fingertip (let's say 1cm x 1cm) then the second is ~0.3mm, the third 1mm, then 0.3mm, then 0.1mm, and the last high pressure cylinder would be 0.03mm in diameter. So in pushing that cylinder in a distance that your finger can comfortably move (let's say 5cm?) then pushing on the lowest pressure cylinder once - you'd have produced an amount of compressed gas in the highest pressure cylinder that would be around 5cm long by 0.03mm wide by 0.03mm deep...a total volume of 0.05x0.00003x0.00003 cubic meters. That's 0.000000000045 cubic meters. That's a remarkably small amount of gas!

So to fill your gas-tank-sized container (let's say it's 1/10th of a cubic meter), at a rate of 0.000000000045 cubic meters per push - you'll need to push that first cylinder in and out 2.2 billion times. At one push per second, it would take you about 70 years to fill your tank. If you tried to do it with one pump of a very long cylinder, then the cylinder would be about 7,000 miles long.

You don't get something for nothing...that's the First law of thermodynamics...and it's a fundamental unbreakable law of nature. Because of that, we don't even need to look at the design of some hypothetical machine to tell you that it won't work. It quite simply cannot work - no matter how cleverly you design it because it is a fundamental part of the very fabric of the universe that we live in that "There ain't no such thing as a free lunch"! SteveBaker (talk) 15:10, 11 January 2013 (UTC)

Steve, thank you - this is a remarkable analysis! Remarkable particularly because of your first paragraph, which correctly summarizes the constraints we're doing away with! You then make very good conclusions logically. But I wonder if you miss the point of the remarkable contraption we now are hypothetically talking about. We goal isn't really to pressurize the gas - it doesn't matter how small the amount of extra volume we add by pushing with 0.1 newtons (which you called 1 kPa over 1cm * 1 cm = https://www.google.com/search?q=1kPa+in+newtons) over 5 cm we get https://www.google.com/q=0.1+newtons+*+5+cm+in+joules 0.005 joules or 0.00138888889 milliwatt hours. If you push the last piston, you get to add 0.005 joules. If you push the next piston directly (using whatever source of torque you want) you get to add 0.05 joules; if you push the next piston down 5 cm you get to add 0.5 joules, and so forth. So, I would say your "70 years" to fill the tank is misleading: you can fill the tank at whatever rate your power source can output torque at! (To the nearest power of ten).

Secondly, I find it very easy to use a finger to push down on a square area that is a lot larger than a single square centimeter: this is my whole point. By making the final area slightly larger, or by playing with the number of differential pumps and their power factors, under the HYPOTHETICAL situation you have first described, can't we continue to fill a gas tank to any point?

Thirdly, when we want that power back OUT again, again under the hypothetical situation we have described, can't we simply open the appropriate valves and let the frictionless pistons (should have mentioned this as well :) push up with whatever force we need, to the nearest power of ten?

Basically, I am asking whether, indeed, this idealized hypothetical solution would not indeed let you store energy by inputing it at whatever torque you want and getting it back out again at whatever torque you want (to the nearest realized piston)? Without (under your hypothetical limits) any constraints other than the weight of the gas and its growing ever hotter as you pump it in?

Thanks again for your great response! 91.120.48.242 (talk) 15:49, 11 January 2013 (UTC)

If you allow yourself to use unobtainium materials with infinite strength, zero elasticity, ignore friction, allow unobtainium infinitely compressible gasses and so forth - then obviously there are all manner of ways to store energy, to input it slowly and extract it slowly - but this is all quite utterly pointless because none of those conditions is even close to being practically realizable.

If you have magical materials then why not build a clockwork car and power it by winding up a giant spring made of unobtainium - or by twisting other unobtainium materials like a rubber band and powering the car like that - or just imagining an ultracapacitor that can store infinite electrical charge - or if you're going to ignore friction and air resistance then a car can be driven any distance (at a constant speed) with no engine at all!

Well, enough - it's trivial to come up with fifty new car power sources that are theoretically viable if you ignore all of the important details. It's all complete B.S though because you're ignoring 100% of the engineering difficulties that make it all quite utterly impossible in practice. Sure, there are theoretical ways to do all sorts of crazy things - but you can't do them for real - so why put so much effort into designing them?

Frankly, your line of questioning has become tiresome - you can't do this, it won't work. Period.

SteveBaker (talk) 16:11, 11 January 2013 (UTC)

Steve, I apologize. I tried to make it 100% clear from opening with "Imagine a sheet of zero weight and infinite tensile strength" in this question and "Imagine a sheet of zero weight and infinite tensile strength, and you make a container out of this....Basically, I am trying to imagine what happens at the limit of a 'perfect container' for storing compressed air" that I had zero practical interest but was trying to understand something fundamental. The fact that I didn't know a snail is at uniform pressure should also show you that I am not serious but a curious student. I am not very interested in springs, tensile energy storage, vacuum tunnels, supercapacitors or battery technologies at present. This is why I didn't mention them. I wish you would take a slightly better attempt to see the source of my questions, since, in point of fact, compressed air is a currently used form of energy storage. I'm trying to understand it. 178.48.114.143 (talk) 19:00, 11 January 2013 (UTC)

I don't have a problem with thought experiments, and I am assuming that you knew that we aren't talking about things that can actually happen the moment you mentioned an infinite strength container. That being said, there are fundamental limits even with the assumptions. Let me try an analogy:

Assume that you can achieve any speed you want or take as much time as you want. Given those assumptions, can a snail go from Los Angeles to New York? Of course. It can reach NYC at 0.0001 MPH if you give it enough time. It can reach NYC in 0.0001 seconds if you give it enough speed. But is cannot reach NYC in 0.0001 seconds at a speed of 0.0001 MPH no matter what assumptions you make. That is a more fundamental limit than the real-world limits associated with actual snails. This is an important distinction to learn. It's the difference between "can't do it with a real snail" and "can't do it, period". It's the difference between "can't reach that goal with existing technology, but if we work very hard at it we might be able to get closer to the goal" and "don't bother trying. It's impossible." --Guy Macon (talk) 19:53, 11 January 2013 (UTC)

I like your analogy. It is a way to understand the relationship between speed, time, and distance. I similarly want to understand the relationship between pressure, energy stored, and force needed to be able to either store that amount of energy, or how much of it you can recover. The intermediate "snail" itself doesn't interest me nearly as much. So it is QUITE like the the speed/distance relationship which is linear, until it curves up exponentially at relativisit speeds and asymptotically to C which it can only approach. Would you feel that I should not be given this curve if I ask for it?

Likewise, I have heard vague mention made to the "pressure/energy stored" relationship NOT being linear (specifically, you guys are vaguely alluding to a diagram where at each phase stage - gas to liquid, liquid to solid - it suddenly spikes same as extra energy spikes as you want to accelerate at high fractions of c).

But beyond that vague 'reference' I still have not been given specifics as to how. This would be akin to saying "In point of fact the energy needed to keep accelerating starts going up exponentially as you reach relativistic speeds but even though the whole point of the thought experiment was to ask abut this diagram, we won't give it to you - we will just say it goes up, and that you're dumb for asking." 178.48.114.143 (talk) 21:45, 11 January 2013 (UTC)

Leave relativity out of it. Not needed to get an answer abd confuses the issue. As for gas to liquid, liquid to solid and energy, here are the numbers:

http://www.barr-rosin.com/images/applications/fig10_relationship_enthalpy_water.gif

Or, (and I highly advise doing this yourself) get a metal pan and a thermometer that goes below 0 degrees C and above 100 degrees C, fill the pan with water and freeze it with the thermometer in the same freezer. That's your starting temperature. Put it on a stove burner until it starts to melt. Verify that it does what the chart says -- you pour in more heat and the temperature of the water doesn't change. After the last of the ice melts watch as the water gets warmer as you pour in heat. Then watch as it hits 100 degrees C and once again it does what the chart says -- you pour in more heat and the temperature of the water doesn't change.

In theory you could do the same thing with, say, pressure and propane, but heat and water gets the point across. --Guy Macon (talk) 23:59, 11 January 2013 (UTC)

Hi, what I meant is that if you read the first thread on this topic above, people suggest that the reason we can't pump more air into a compressed air tank is because after the blue stuff is liquid it hardly compresses, it becomes a lot harder to compress. So, let's see this on a diagram - amount of compression achieved versus amount of force required to achieve it. Relativism is not needed but is a good proxy for an easy, linear relationship that starts behaving strangely. Well, by the time air is a metal if you pump it full enough (high enough pressure) that would be just as strange and non-linear. SteveBakr didn't address this point at all, for example. I don't know what these pressure curves look like... 178.48.114.143 (talk) 00:37, 12 January 2013 (UTC)

ImageJ macro for batch merge of images

I have image files named in the format:

Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 2 ul Lipofectamine 2000 - 15x - Field 1 - Brightfield - 2012-12-16.tif

Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 2 ul Lipofectamine 2000 - 15x - Field 1 - UV red - 2012-12-16.tif

Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 2 ul Lipofectamine 2000 - 15x - Field 2 - Brightfield - 2012-12-16.tif

Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 2 ul Lipofectamine 2000 - 15x - Field 2 - UV red - 2012-12-16.tif

etc

I would like to merge each "Brightfield" image with its associated "UV red" image using ImageJ. Can anyone help me put together a macro to do this?

I tried using the built-in macro recorder but it doesn't pay attention to how much I increased the contrast of the red images and it also uses specfic file names which is useless when each file is named differently (obviously; you can't have two files with the exact same path!) 129.215.47.59 (talk) 14:23, 11 January 2013 (UTC)

Maybe better to ask this at the Computing Desk. - Lindert (talk) 14:39, 11 January 2013 (UTC)

Computing people probably don't deal with ImageJ. ImageJ is an NIH application. 72.229.155.79 (talk) 19:21, 11 January 2013 (UTC)

One can always try, and most people here on the science desk don't work for the NIH either (if there are any at all). Also ImageJ is open-source and has many useful functions, so maybe some 'computing people' have used it. Anyway, if you still think this is the best place, just forget I said anything. I'm afraid I can't be of much help, but good luck finding an answer. - Lindert (talk) 20:38, 11 January 2013 (UTC)

It would help if you could upload the actual images. What exactly would this merge do ? Are you talking about combining the red from one image with the blue and green from another ? Are the images of the same size and already properly aligned ? StuRat (talk) 23:16, 11 January 2013 (UTC)

Hi. The images look like this.

Bright field

UV red

Merged

Precedure to merge one pair of images

Open brightfield image. Image>Type>8-bit

Open UV/red image. Image>Adjust>Brightness/Contrast and increase contrast five clicks

Image>Type>8-bit

Merge channels - set C1 (red) as UV/red image and set C4 (gray) as brightfield image.

Save new image with name: Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 2 ul Lipofectamine 2000 - 15x - Field 1 - Merged - 2012-12-16.tif

Macro as recorded by ImageJ during above procedure

open("B:\\Sean Smith\\M\\DF1\\Ex.SS.4.4.170 - 2012-12-13\\Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 4 ul Lipofectamine 2000 - 15x - Field 1 - Brightfield - 2012-12-13.tif");

run("8-bit");

open("B:\\Sean Smith\\M\\DF1\\Ex.SS.4.4.170 - 2012-12-13\\Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 4 ul Lipofectamine 2000 - 15x - Field 1 - UV red - 2012-12-13.tif");

//run("Brightness/Contrast...");

//run("Brightness/Contrast...");

run("8-bit");

run("Merge Channels...", "c1=[Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 4 ul Lipofectamine 2000 - 15x - Field 1 - UV red - 2012-12-13.tif] c4=[Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 4 ul Lipofectamine 2000 - 15x - Field 1 - Brightfield - 2012-12-13.tif]");

saveAs("Tiff", ""B:\\Sean Smith\\M\\DF1\\Ex.SS.4.4.170 - 2012-12-13\\Exp.SS.4.4.170 - DF1 - MSTN HDR donor candidate 1 - 4 ul Lipofectamine 2000 - 15x - Field 1 - Merged - 2012-12-13.tif");

129.215.47.59 (talk) 14:42, 14 January 2013 (UTC)

is Asian male facial hair easier to wax than Caucasian facial hair?

I wonder if women's facial waxing products would work on Asian male facial hair. Thanks. 72.229.155.79 (talk) 18:07, 11 January 2013 (UTC)

I see no reason why not as they work on Caucasian male facial hair too! --TammyMoet (talk) 12:27, 12 January 2013 (UTC)

I am pretty sure there was an episode of 24 where they did this. I can tell you from personal experience that the black hair care product "snap back" and protein hair gels work admirably on us whitefolk. Back in college we even had get-togethers where the black and white people fondled each other's (unremoved) hair. Shame there weren't any asian students in college. μηδείς (talk) 03:57, 13 January 2013 (UTC)

Laser harp making

I have been interested for a while in acquiring and learning to play one of these new laser harps, but they are rather expensive. However, I recently learnt that one of my housemates plans to build his own musical tesla coil and so, not to be outdone (or at least not by as much) I thought I could at least look into the possibility of making my own laser harp, which might well also work out cheaper, and allow me to modify it to exactly suit my needs. So, is it possible, and where might I go to find instructions on how to do so, and to buy the parts I would need?

86.15.83.223 (talk) 21:25, 11 January 2013 (UTC)

You might get decent results with just Kinect; that article links to various development resources. With a little software you could probably build something that played when a hand was held in front of it, and which changed the frequency as the hand moved around - it might sound a bit like a Theremin. Or you could use rangerfinders - Googling for Arduino rangefinder projects finds several people working on those kind of things. -- Finlay McWalterჷTalk 22:01, 11 January 2013 (UTC)

Although it seems the spacial resolution of the current Kinect, and their relatively high latency, limits the technology's current use for musical input. -- Finlay McWalterჷTalk 22:06, 11 January 2013 (UTC)

and it doesn't have pretty colour lights around it 86.15.83.223 (talk) 22:20, 11 January 2013 (UTC)

so, no actual ideas on where to find this information? 86.15.83.223 (talk) 23:08, 12 January 2013 (UTC)

The clock's onomatopoeia

This is possibly a silly question, but does a clock really do tick tock ? If so, what is the "tick" and what's the "tock"? My ears are used to hear a clear tick-tock, but if I decide so, I can even hear "tick-tick" or even a Waltz-like "tick tock tock, tick tock tock..." Therefore, I think it should just do a series of indistinguishable "tick"; but why do we believe to hear, and say, tick-tock, then. --pma 23:14, 11 January 2013 (UTC)

I would guess this comes from a pendulum clock, which may do different things, and therefore make different sounds, during the right-to-left and left-to-right passes. StuRat (talk) 23:19, 11 January 2013 (UTC)

The tick-tock is the back and forth movement of the escapement. -- Finlay McWalterჷTalk 23:23, 11 January 2013 (UTC)

Actually, this is a great question. I've seen a lot of clock mechanisms - pendulum clocks, sprung wrist-watches with all sorts of movements; weight-driven grandfather clocks; true analog cuckoo clocks... and I can't actually recall ever hearing a "tock" sound. Especially with the weight-drop systems, there's a lot of other assorted noise - sort of gear-like grinding noises - in addition to the ticking of the ratchet. And of course, now that everything's gone quartz, there's usually just one ticking ratchet, with very little else to the mechanism at all. I'm surprised that we don't have history of clockwork; but we do have movement (clockwork). Given that ticking clocks are only a few centuries old, the first recorded usage of the "tick-tock" can't yet have disappeared into obscurity! Maybe posting on the language desk will help you track down how this description became so commonplace. Nimur (talk) 02:17, 12 January 2013 (UTC)

We have an article on exactly that, but it's fairly short. The study of timekeeping devices is called Horology. --Jayron32 02:36, 12 January 2013 (UTC)

French clocks don't go "tick tock", mais ils faisent "tic tac"[1]. Alansplodge (talk) 02:55, 12 January 2013 (UTC)

And do they all have a refreshing cinnamon, orange, or mint flavor ? :-) StuRat (talk) 03:01, 12 January 2013 (UTC)

Anyway, "Tick, meaning "sound made by a clock" is probably first recorded 1540s; tick-tock is recorded from 1848."[2] Alansplodge (talk) 03:07, 12 January 2013 (UTC)

I once trained as an instrument mechanic. Not a lot to do with clocks, but the skills enable an instrument mechanic to repair clocks and watches, and a lot of us including me did so. I still do occaisonally. Virtually all mechanical clocks and watches have a degree of tick assymetry, however a good quality mechanism correctly adjusted will have so little assymetry the ear should not be able to detect it. Note I said "should" - more on that below.

There are a great variety of clock mechanisms, so I'll just cover a typical balance wheel mechanism. In such movements what determines the rate is oscillation of a spring (the spiral hairsping) loaded balance wheel. The mass of the wheel together with the spring elasticity sets the rate. The spring is at rest (no tension) when the wheel is in the centre position. The wheel has a pin a small distance from the axis which engages with a fork. The fork supplies energy from the escape cog. The cycle is as follows: Wheel turns turns forward, until at about 30 degrees or so until the pin hits the fork, making a sound. Initially the wheel inertia moves the fork until the escape gog trips (another sound) then the fork looses contact with the pin on one tyne and hits it with the other tyne - a relatively loud sound, and imparts energy to the wheel to keep it going. The wheel continues and the pin moves out of the fork until increasing spring tension overcomes wheel inertia - the wheel is then at maximum rotation, and starts to turn in the opposite direction. Continuing to turn, the pin again contacts the fork, making a sound, the escape cog trip, etc, in the opposite direction.

We thus see that the wheel oscillates back and forth through (typically) about 230 to 300 degrees or so. Each "tick" (correct term is "beat") actually consists of three sounds: pin hits fork, escape trip, fork hits pin. The time between the three sounds of each tick are too close together for the ear to resolve as separate impacts, but are clearly resolved in electronic clock & watch analysers. If the wheel centre position as set by the rest (zero tension) position of the hairspring is different to the centre position as determined by the position of the fork tynes, the energy imparted by the fork will be different for each rotation direction. This makes (1) the loudness of the sounds different in each direction, (2) the relative loudness of the three impacts in each "tick" different to the subsequent "tock", which affects the perceived sound quality, and 3) the degree of rotation different in each direction, which makes the time interval between "tick" and "tock" different to between the "tock" and the tick".

So, yes, especially in a worn, cheaply made, or poorly adjusted clock, the tick does sound different to the tock. And the timing assymetry is detectable by the ear, but persons not trained in clock repair tend to just perceive it as tick sounding different to tock.

The ear is very susceptable to assigning patterns to sounds, even when no pattern exists. Even with a good perfectly adjusted clock, many people will perceive every second tick to be different. This phemomena is easily demonstrated by moving you finger in time to the tocks (ie each second tick) - your brain will lock into percieving that the ticks are different to the tocks. Get a second person to, after a while, force you to change finger timing forward one tick. Many people will then re-assign what is a tick sound and what is a tock sound. Another way is to set an electronic metronome going at a fast rate without beat accentuation. Many people will, especially if told it is so, percieve ticks different to tocks, even though in an electronic metronome (don't use a traditional mechanical metronome) that is impossible.

Wickwack 120.145.74.148 (talk) 03:09, 12 January 2013 (UTC)

Antique pendulum clocks do tick-tock. They aren't symmetrical. They have a wheel with teeth that is turning in one direction. On the tick, there is this U-shaped thing that goes between the teeth at one point. On the tock it is lifted and the other side goes down in another place. I'm not sure if this accounts for the difference in sound. Bubba73 ^{You talkin' to me?} 04:06, 12 January 2013 (UTC)

Yes, that u-shaped thing interacting with the toothed wheel is the escape - not essentially different to the escape in an oscillating wheel & spring type clock. In a wheel & spring clock or watch, the escape sound is normally much quieter than the impacts of the pin and fork, so assymetry in the escape is not easily heard. However in many antique pendulum clocks, the escape is coupled to the pendulum via a flexible strip in such as way as to be silent, so the escape is the only thing you hear. In other clocks a rod arrangment was used, which makes a slight click. However, a well adjusted and correctly lubricated antique pendulum clock should still make very even ticks - don't overlook the tendency of the ear to assign a pattern as I said above. Correct adjustment and even ticking is confirmed with an analyser - essentially a clamp microphone, amplifier, and paper strip recorder - the instant of each sound (pin impacts, escape trips) is marked on a moving strip of paper, and usually the amplified sounds can be listened to in headphones. This lets you set the amplitude, symmetry, and rate very quickly and enables one to diagnose all sorts of troubles that lead to inaccuracy. Wickwack 58.170.182.38 (talk) 06:05, 12 January 2013 (UTC)

I'm not doubting Wickwack's excellent analysis, but all of the grandfather clocks I've ever heard have had a tock very different from their tick! (Sometimes a different frequency of sound, with the tock lower than the tick, as well as a different interval between them.) They probably were all old and worn and not recently adjusted. I agree that perfectly-adjusted mechanisms should have tocks identical to ticks. Dbfirs 08:58, 12 January 2013 (UTC)

If the interval between tock and tick is perceptively quite different from tick to tock, as distinct from being heard as tock sounding different to tick, your clock is very badly worn. In many antique grandfather clocks, the bearing for the U-arm is fibre. I've seen them worn down so the hole for the shaft is no longer round, but a more or less straight track several mm long. It takes 60 to 80 years of running without any clean-and-oil servicing to get that bad. I suggest locating a reputable clock repairer, as your clock is about to stop. Wickwack 60.230.222.99 (talk) 10:12, 12 January 2013 (UTC)

Yes, you are correct about the age and lack of servicing of the clock (not mine, it belonged to my uncle who oiled it occasionally -- it now belongs to my cousin who has probably had it serviced properly). And it did tend to become irregular just before it stopped. You obviously have experience of better-serviced clocks than the ones I've seen. Dbfirs 13:15, 12 January 2013 (UTC)

What is the technical name of the perceptual phenomenon that Wickwack mentioned where, hearing a series of identical even-spaced sounds, people still tend to group them metrically into pairs? μηδείς (talk) 06:50, 12 January 2013 (UTC)

It is called clustering illusion. See http://en.wikipedia.org/wiki/Clustering_illusion. Check also apophenia. Wickwack 60.230.222.99 (talk) 10:30, 12 January 2013 (UTC)

That's the phenomenon broadly, but I thought there was a specifically musical or perceptual term related to rhythmic phrasing. μηδείς (talk) 20:33, 12 January 2013 (UTC)

If I had time right now, I would record an antique clock's tick tock and upload it, but I don't think I will be able to for several days. Bubba73 ^{You talkin' to me?} 22:13, 12 January 2013 (UTC)

I found "grandfather clock ticking" on youtube, captured the sound, imported into sound editing software, and did a screenshot: File:Screenshot of a grandfather clock tick tock.jpg. The one on the left is the tick and the one on the right is the tock. Bubba73 ^{You talkin' to me?} 22:38, 12 January 2013 (UTC)

And File:Grandfather clock tick tock 2.jpg shows how the ticks are generally louder than the tocks. Bubba73 ^{You talkin' to me?} 03:55, 13 January 2013 (UTC)

On that one, the sound is louder about every 10th beat. It shouldn't be like that. Could be a drive train gearwheel damaged, or a badly worn bearing. Wickwack 120.145.32.87 (talk) 10:48, 13 January 2013 (UTC)

The current flu going around

Subject: The current flu going around. Question...Is there any data which indicates what the odds are of getting this current flu if one does not get vaccinated?

Thank you — Preceding unsigned comment added by 24.62.161.254 (talk) 23:35, 11 January 2013 (UTC)

It depends on how isolated you are. But it really points once again to the extreme shallowness of the modern human gene pool. Sic semper Monocultures. Hcobb (talk) 23:46, 11 January 2013 (UTC)

is the vaccine effective against this strain?--Jonharley667 (talk) 02:23, 12 January 2013 (UTC)

A very good Q. I got the flu myself, about a week before Xmas. Fortunately, I was over it by the holiday. But I want to know if the vaccine would have spared me the trouble, had I been vaccinated. StuRat (talk) 02:31, 12 January 2013 (UTC)

I was reading recently that the vaccine is believed to be 60-70% effective this year. Dragons flight (talk) 02:39, 12 January 2013 (UTC)

Thanks, but let's break it down by strain. Is the flu that's going around in the US a single strain, or multiples ? Are each of those strains included in the vaccine ? What is the chance that the vaccine will prevent you from getting each strain ? And, also, how does that 60-70% compare with previous years ? StuRat (talk) 02:47, 12 January 2013 (UTC)

As usual, there are multiple strains, but they're covered well by the vaccine as noted here: So far this season, most (91%) of the influenza viruses that have been analyzed at CDC are like the viruses included in the 2012-2013 influenza vaccine. There are graphics here on CDC's flu dashboard, showing that it's mostly influenza A/H3 (consistent with H3N2). Effectiveness of the vaccine in adults in preventing significant disease ranges from 50-70% (PMID 22252003 & PMID 22032844). -- Scray (talk) 03:25, 12 January 2013 (UTC)

serependitiously, I was just reading up on this. So: flu vaccine currently consists of an H1N1, a H3N2, and a B strain (starting in a couple of years, it will have 2 B strains). According to the CDC, the dominant strain this year can be seen to be H3N2, which has the highest mortality (most years, H1N1 is the most numerous). However, the vaccine has a pretty good fit this year:

2009 H1N1 [17]:

• All 17 2009 H1N1 viruses tested were characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2012-2013 influenza vaccine for the Northern Hemisphere.

Influenza A (H3N2) [327]:

• 325 (99.4%) of the 327 H3N2 influenza viruses tested have been characterized as A/Victoria/361/2011-like, the influenza A (H3N2) component of the 2012-2013 Northern Hemisphere influenza vaccine.
• 2 (0.6%) of the 327 H3N2 viruses tested showed reduced titers with antiserum produced against A/Victoria/361/2011.

Influenza B (B/Yamagata/16/88 and B/Victoria/02/87 lineages) [177]:

• Yamagata Lineage [118]: 118 (66.7%) of the 177 influenza B viruses tested so far this season have been characterized as B/Wisconsin/1/2010-like, the influenza B component of the 2012-2013 Northern Hemisphere influenza vaccine.
• Victoria Lineage [59]: 59 (33.3%) of 177 influenza B viruses tested have been from the B/Victoria lineage of viruses.

Gzuckier (talk) 03:29, 12 January 2013 (UTC)

StuRat's question, about whether he himself would be better off getting vaccinated cannot be answered, for the following reasons: 1) you need to account for herd immunity (http://en.wikipedia.org/wiki/Herd_immunity) - if most of the folk you come into contact with are immunised, you are protected as well. 2) your immune system can deal with almost all flu viruses even ones it hasn't seen before, if exposed at low level but not a high level. I've noticed many times if my wife comes home from work sniffly at the beginning of flu season, she may come down the next day with full symptoms, but I will remain healthy. But if I have to spend a lot of time with someone at work who is already quite sick, I'll often be sniffly a couple of days later, then get sick too - and my wife will stay healthy. 3) The flu virus currently going round may be one that your immune system has seen before. For example, a swine flu strain that caused the authorities in various counties to be very concerned a couple of years ago had little impact in Australia, mostly folk who got sick were young children. Research showed that we had been exposed to it about 10 years before. 4) the vaccine may not cover the particular virus going round. Each year the authorities make a calculated gamble on what viruses are likely to be a problem - they cannot always get it right.

A study was done by Telstra (the main phone, cable TV, and internet company in Australia) some years ago, comparing the number of days off work for vaccinated staff and non-vaccinated staff, to see if it was worthwhile to pay for the cost. It turned out there was no significant difference - however, not all staff who take sick leave are geniunely sick, also you can take time off to look after a sick wife or child, obscuring the data.

Wickwack 120.145.74.148 (talk) 03:45, 12 January 2013 (UTC)

Answering the original question, I know someone who went went for a holiday in the US and got the flu in the last days they were there, but on the whole, I expect the odds of most New Zealanders getting it in the next four months or so is quite low and I'm reasonably sure most health authorities don't recommend the vaccine in general for us. Now once our influenza season starts things will start to change (although whether it can be called 'The current flu going around' may be debatable). Nil Einne (talk) 13:06, 12 January 2013 (UTC)

Is there any benefit to getting the same flu shot twice? I am looking for real statistics or sources, thanks. μηδείς (talk) 06:46, 12 January 2013 (UTC)

I know you asked for stats or sources, but I'll be surprised if there are any, for the following reason: Whenever I have had a flu shot, the nurse asks 3 questions: 1) Are you allergic to chickens? 2)have you already had a flu shot this year? and, 3) do you currently have flu symptoms or suspect you may be coming down with flu? If you answer is yes to any one, you don't get a shot. This is how it works in Australia, I assume other countries are the same. Wickwack 60.230.222.99 (talk) 10:02, 12 January 2013 (UTC)

Lack of substantial benefit from repeated influenza vaccination was established in adults a long time ago, e.g. 1977, 1987 and compelling evidence for multiple-dose vaccination of older adults has not emerged. The situation is different for children (6 months to 8 years) who have never been vaccinated previously - for them, two doses are recommended (by the US ACIP) to establish immunity PMID 14986252 (thereafter, annual vaccination is adequate). -- Scray (talk)

To answer the OP's OQ, the Examiner website (which I can't link to because WP thinks it's spam) has an article on the new strain which is sweeping America. One of the links on the page may have the exact statistics for him. --TammyMoet (talk) 12:26, 12 January 2013 (UTC)

To get past that spam blocking here, do a google search for the title of the article you are looking to link to, let's say "Flu outbreak worsens, causing vaccine shortage in some areas". Then cut out the address location that shows your google results, of which the article you want should be the first hit and post it like this. (Open this up in the edit box to see what I have done. μηδείς (talk) 19:06, 12 January 2013 (UTC)

UPDATE: I seem to have contracted the flu again. I assume I'm now immune to the strain I caught before Xmas, so this must be a new strain, right ? I was fully recovered for a couple weeks, so it seems unlikely it's the original strain making a comeback. I guess I need to get a flu shot next year. StuRat (talk) 00:43, 13 January 2013 (UTC)

There's multiple shit going around, Stu. I have had the same bacterial sinus infection since Halloween with three courses of antiobiotics, a few days respite each time, and the same symptoms over and over, the worst being a post-nasal drip that causes me to be nauseous from the phlegm. All my intimates have caught this from me, my lover and mother (not the same person) having gotten over it, my father having had it worse than I did (and now taking a very heavy round of mopsiflopsicin to cure it), and my nephews having developed it after they left my parentses after Christmas. It's thoroughly miserable, with some vomitting by me, dad, and one of the boys. But it's not the flu, which I haven't had in over a decade. Are you sure you have had the flu and the same flu twice? μηδείς (talk) 03:49, 13 January 2013 (UTC)

This is getting a little too personal - please remember that this desk is for science questions (not discussion of personal medical maladies). -- Scray (talk) 04:12, 13 January 2013 (UTC)

LOL @ "parentses". The 2nd bout might actually be food poisoning, as it occurred right after a meal from Booger King, and only lasted a couple days. However, the symptoms were identical. StuRat (talk) 17:19, 13 January 2013 (UTC)

Purely anecdotal here, but my understanding is that the formulation for the flu vaccine this year basically predicted the wrong strain of Flu A would be prevalent. So, the shot might have helped folks get over it quicker, but many people still got the flu because of that. Flu vaccines aren't an exact science, since there's no way to be sure which strain is going to be most common this year. — The Hand That Feeds You:^Bite 16:47, 15 January 2013 (UTC)