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August 31

DNA and heredity

Hello. Perhaps this is a simple question and I'm just not seeing an answer anywhere, but I'm trying to understand if (for example) I, as a male, could have inherited any traits from my paternal grandmother. In this scenario, my father would have inherited a Y chromosome from his dad and an X chromosome from his mom. He would have passed the Y chromosome (i.e. only his father's genetic material, not his mother's) on to me and my X chromosome would come from my mother. Is this right? Or is there some other process whereby I would have inherited genetic material from my father's mother?--William Thweatt ^TalkContribs 01:04, 31 August 2013 (UTC)

You have another 22 chromosome pairs besides X and Y, which come from both of your parents, and are constructed from DNA passed on by all four of your grandparents. See the introduction of Human genome. Someguy1221 (talk) 01:23, 31 August 2013 (UTC)

More specifically, you've inherited 25% of your genetics from your paternal grandmother. As you have from your other three genetic grandparents. --Jayron32 01:29, 31 August 2013 (UTC)

Ah, yes. It's all coming back to me now. Thanks all. It's been a long time since Biology 101 for me. :) --William Thweatt ^TalkContribs 01:42, 31 August 2013 (UTC)

The 25% is a good approximation, but you might actually inherit slightly more from your paternal grandfather than your paternal grandmother, since you definitely have his Y and have only a 50% chance of having that grandmother's X. Also, sometimes genes can jump from one chromosome to another. StuRat (talk) 02:43, 31 August 2013 (UTC)

Presuming that William is male, he has zero chance of having that grandmother's X. A man's X always comes from his mother. (A woman gets one from her mother and one from her father.) Looie496 (talk) 02:58, 31 August 2013 (UTC)

Good point. Correcting for that, with 46 chromosomes, a male should, on average get 1 (Y) + 44/4 chromosomes from his paternal grandfather, 44/4 chromosomes from his paternal grandmother (no sex chromosome), and 1/2 + 44/4 chromosomes from the additional two maternal grandparents, as either might contribute the X. So, that's 12 + 11 + 11.5 + 11.5 = 46. As a percentage, that works out to be 26%, 24%, 25%, and 25%. StuRat (talk) 10:10, 31 August 2013 (UTC)

There's no either, just as with autosomes both maternal grandparent will contribute to the X chromosome a male inherits as recombination will almost definitely occur (if it does not, this generally means major problems so the whole calculation may be out of wack). In case this is still confusing, this means the X chromosome the male inherits from his mother is not her father's X chromosome nor her mother's X chromosome but a chromosome combining their two (maternal grandparents) chromosomes in some way. (The X chromosome the maternal grandmother contributes is likewise a combination of the two X chromosomes she has. In fact even the X chromosome from the father is not simply the X chromosome he inherits from his mother but a combination of his X and Y chromosomes although the Pseudoautosomal regions are small enough that it doesn't really screw up your statistics to assume it is.) Also I question the usefulness of counting percentages in terms of number of chromosomes, it makes much more sense to either use base pairs or perhaps genes (the former is of course far simpler than the later), and the differing size of the chromosomes means the values you will get will be sufficiently different. Nil Einne (talk) 16:05, 31 August 2013 (UTC)

Erm, StuRat, you're confusing people. Barring aneuploidy of some sort, no matter what the pedigree, you get one of each pair of chromosomes from each parent. If you look at the person you can figure out which sex chromosome he got from his father, and thus from successive ancestors, but he or she always traces one or another of them back that far! Though you might say the X chromosome is bigger and better, so inheriting a Y doesn't count for as much. But you can't really quantify that absolutely in a particularly meaningful way. (you could count basepairs, but does the "junkiness" of a Y make it count for even less?) Wnt (talk) 22:46, 3 September 2013 (UTC)

If we're just talking about autosomal DNA here, the 25% has to be understood as a statistical average. When germ cells (sperm and eggs) are made, genetic recombination causes the paternal and maternal copies of each pair of chromosomes to exchange some DNA. This means that while you carry 22 autosomes that are entirely paternal and 22 that are entirely maternal, your germ cells carry autosomes that each contain a mix of paternal and maternal DNA. So your children do not carry the exact same chromosomes as you. Since this process is totally random, you may inherit more or less than 25% from each particular grandparent, but the average will be 25%. Someguy1221 (talk) 03:56, 31 August 2013 (UTC)

weathern pattern significance

Back in the early-to-mid 1980s, when I was a kid, I heard a foghorn sounding off at night during a rainstorm in San Francisco. Why would an authority need to turn on the foghorn during rainy weather at night?142.255.103.121 (talk) 04:09, 31 August 2013 (UTC)

Two reasons: (1) On a rainy night, it IS harder to see than on a clear day (anyone who's ever flown a small plane on a rainy night can appreciate just how much); and (2) even more importantly, along seashores (especially in the area around Frisco), such weather can often cause the cloud base to sink and ground fog to form -- hence the need for the foghorn. 24.23.196.85 (talk) 04:51, 31 August 2013 (UTC)

Same thing for a rainstorm during the day, right?142.255.103.121 (talk) 19:17, 31 August 2013 (UTC)

Calling it a "fog" horn is a bit of a misnomer - it's really a "poor visibility" horn. Hence it's gotta be sounded in heavy rain or snow as well as in fog. Also in an era before weather satellites and weather radar - nobody knew what the visibility would be like further from shore - so you'd definitely want to err on the side of caution. SteveBaker (talk) 21:56, 31 August 2013 (UTC)

Are dogs born in winter less smelly than dogs born in summer?

Just heard one of my friends say so--朝鲜的轮子 (talk) 04:57, 31 August 2013 (UTC)

I wouldn't think so, although an outdoor poo will smell less in winter, as it will rapidly cool and freeze. Of course, if you don't pick them up, you're in for a rude surprise in spring. :-) StuRat (talk) 09:59, 31 August 2013 (UTC)

If you live in a hot, dry climate the quick drying of the deposits makes them less offensive and problematic than being somewhere where they stay damp and squishable. But all if this has nothing to do with when the dog was born. Had dogs all my life, Never heard of that, and can't think of any reason why that would make a difference. HiLo48 (talk) 22:26, 31 August 2013 (UTC)

I think my friend mean a dog's skin odor. Looked up Dog odor, but found nothing about skin odor except "Dogs only produce sweat on areas not covered with fur, such as the nose and paw pads, unlike humans who sweat almost everywhere. However, they do have sweat glands, called apocrine glands, associated with every hair follicle on their body. The exact function of these glands is not known, but they may produce pheromones or chemical signals for communication with other dogs.".--朝鲜的轮子 (talk) 01:29, 1 September 2013 (UTC)

Polonium hydride

Is it PoH₂ or H₂Po? Double sharp (talk) 15:15, 31 August 2013 (UTC)

There is an article about it Polonium hydride Widneymanor (talk) 16:39, 31 August 2013 (UTC)

Which unfortunately wavers on the issue:( (I suspect Ds knows this, but for others...) The same formula written one way or the other suggests which atom is more cationic vs anionic. Naming it "[some-metal] hydride" (meaning Po is more metallic and has "hydride" anions) contradicts comments about it having chemical analogs to chalcogenides where the Po has anionic forms. So to respond to the question sort-of..."what's really the goal of your question? To understand the nature of the chemical, or to decide how to write it in some [as yet unstated] context?" DMacks (talk) 20:04, 31 August 2013 (UTC)

Yup, the sources I've seen tend to disagree on this! Bagnall calls it polonium hydride with PoH₂ (IIRC), while Thayer (a ref at element 117, talks about heavy main group elements) calls it H₂Po! Po has a slightly lower EN (2.0) than H (2.20); that would imply that Po is the cation, but is there something else at work here? (And should we list it in the Po compounds template under Po(II) or Po(−II)?) It's more of understanding the nature of the compound than writing it.

(Hydrogen astatide has a similar issue with HAt vs AtH...) Double sharp (talk) 03:25, 1 September 2013 (UTC)

...much as which we habitually write "H₂O" rather than "OH₂" or "HOH" or even "HHO". SteveBaker (talk) 21:24, 31 August 2013 (UTC)

For the molecular compound, it should always be written as H₂Po. IUPAC determines the order in empirical formulae to be row 7→ row 2; group 18 → group 1 → group 2 → Actinium → Lawrencium → Lanthanum → Lutetium → group 3 → group 15 → Hydrogen → group 16 → group 17. Plasmic Physics (talk) 21:37, 31 August 2013 (UTC)

But if it really is a hydride rather than a polonide, this would be misleading, which is why I asked the question, albeit not that clearly (I've tried to remedy that now!) Double sharp (talk) 03:27, 1 September 2013 (UTC)

It would not matter, compositional formulae are ignorant of bond-type. Plasmic Physics (talk) 08:40, 1 September 2013 (UTC)

...And in case you were, wondering, hydrogen poonide is a molecular compound. Plasmic Physics (talk) 00:25, 4 September 2013 (UTC)

I was too lazy to look up the electronegativity of polonium, but it turns out that that article has two nice little tables, both of which put it as a little less than hydrogen. Does that clinch it as PoH2? Wnt (talk) 22:51, 3 September 2013 (UTC)

According to who? This is a reference desk. Plasmic Physics (talk) 23:15, 3 September 2013 (UTC)

Need help with Calculating the slope of the best fit line from a data table?

Basically we had to calculate the circumference and the diameter of several round objects and convert that into a number closest to PI...

Now we are supposed to Calculate the slope with it but our teacher made no attempt to explain to us how to do it and our textbooks provide no easy to understand way to coincides with the assignment.

Diameter/Independent    Circumference/Dependent  Ratio C/D

     4.5 cm                  10   cm               2.22
     2   cm                   7   cm               3.5
     2.5 cm                   8   cm               3.2
     6.8 cm                  21.8 cm               3.205
     2.9 cm                   8.8 cm               3.034

He was supposed to post a video on Blackboard but he is so computer illiterate that it is sad. He never explains stuff and makes the assignment difficult but does not really teach us how to complete it. I have spent two days on youtube trying to understand this but i feel he pulled this whoel thing out of his @$$! Sorry! — Preceding unsigned comment added by Jheckman1986 (talk • contribs) 20:38, 31 August 2013 (UTC)

The slope of a Simple linear regression without an intercept term is ${\hat {\beta }}=({\overline {xy}})/({\overline {x^{2}}})$, where the overline indicates the mean, y in this case is circumference and x is diameter. However, just calculating the simpler ${\hat {\beta }}=({\overline {y/x}})$ would give you pretty much the same answer in this case. Red Act (talk) 21:20, 31 August 2013 (UTC)

I suspect that the intent here is that you plot a graph of diameter versus circumference. If diameter is the "independent" variable - then it should be plotted along the horizontal X axis and the circumference being "dependent" goes up the vertical Y axis.

Next, you can (hopefully) observe that those points lie close to a straight line...so you can calculate the slope of a best-fit straight line through those data points and thereby deduce the equation for the circumference of a circle, knowing it's diameter. This is a very valid and scientific way to deduce such a relationship. Mathematicians will of course cringe at this because they have ways to prove beyond doubt that that relationship is...but I'm guessing that this experiment is to help you to understand how scientific relationships are deduced from experimental data.

The way to calculate the slope of a straight line is described in our slope article (look at the first equation).

SteveBaker (talk) 21:22, 31 August 2013 (UTC)

(I fixed the OP's chart.) I think what Steve is saying is to just plot the points and draw in what looks like a good line, then measure it's slope off the graph. There are many mathematical ways you could calculate the best fit line, instead, but each will give a slightly different answer. So, if your teacher didn't specify what to do, I'd take the easy way out and just draw in a line by hand (using a ruler, of course). StuRat (talk) 10:30, 1 September 2013 (UTC)

Note that most decent scientific calculators will have a linear regression feature built in, which can provide the slope for a given set of data.--Srleffler (talk) 07:11, 2 September 2013 (UTC)

Throwing away contact lenses

Is there a reason that monthly contact lenses need to be disposed of after a month of use (other than to enable the manufacturer to sell more contact lenses)? — Preceding unsigned comment added by 89.241.229.123 (talk) 21:01, 31 August 2013 (UTC)

Contact_lens#Replacement_schedule says that "Lenses replaced frequently gather fewer deposits of allergens and germs". By allowing gasses and liquids to flow through the lens, it's also possible for germs and allergens to lodge deep inside them where cleaning fluids may not penetrate. The article does also mention that "Quarterly or annual lenses, which used to be very common, have been discontinued by manufacturers who argue they are less comfortable but also can make more profit by forcing consumers over to more frequent replacement schedules." - which kinda backs up your theory that it's to enable them to sell more lenses. HOWEVER: What that sentence neither says nor implies is that you could wear 4-week lenses for months. It's quite possible that 4 week lenses really are only good for 4 weeks - and they the manufacturers simply stopped making the kind that last longer...do not assume that it's safe to use a 4 week lens for many months on the basis of this information...that might be very dangerous. SteveBaker (talk) 21:13, 31 August 2013 (UTC)

Why not sterilize contact lenses using UV radiation or ionizing radiation? Count Iblis (talk) 23:17, 31 August 2013 (UTC)

UV will destroy the polymers in the lens in a matter of hours [1]. 68.0.135.117 (talk) 23:20, 31 August 2013 (UTC)

The protein deposits are what I find to be the worst problem. You can sterilize them with hydrogen peroxide, but the protein deposits don't come off. I tried using bleach on them, but that also damaged the lenses. The original hard contact lenses could probably be cleaned indefinitely, but those really were uncomfortable, and, in my opinion, dangerous (they can cut your eyes). StuRat (talk) 10:21, 1 September 2013 (UTC)

herbicide for vines?

vine on the tree near the azaleas

vine in azaleas

About 2 months ago, vines were taking over our azaleas so bad that I had someone cut them out. It was so bad that they had to cut back most of the azaleas. Now the vines are coming back. Is there a herbicide or something that will get rid of the vines but not hurt the azaleas? Bubba73 ^{You talkin' to me?} 23:46, 31 August 2013 (UTC)

No, not to my knowledge. We have Roundup-ready corn, but not Azaleas. You can also get herbicides that selectively target grasses, but that won't help here either. The best removal tactics may depend in part on what type of vine. Does it have a woody stem? Is it English ivy or virginia creeper or porcelain berry or kudzu (all common and invasiv across much of the USA)? Anyway, for most woody vines, you can paint a small amount of Roundup on the stumps, directly after you cut the vines back. The vines will most likely resprout, but you can repeat the process over the course of a season or two, and the plant will get weaker and weaker each time. There is also some risk to the Azaleas, but if you don't spill any and only directly apply glyphosate to unwanted stumps (ideally on a hot day), you should be ok. SemanticMantis (talk) 00:22, 1 September 2013 (UTC)

(There is something wrong with the sections right now.) Thanks - I don't know what kind of vine it is, but I think it looks like the porcelain berry. I'll try to get a photo tomorrow. Bubba73 ^{You talkin' to me?} 00:42, 1 September 2013 (UTC)

Whoever found they had to cut back your azaleas to get at the vines is grossly negligent. You simply cut the vine stem (species is irrelevant unless it's dodder) at soil level, allow it to die, and then remove it later. There's absolutely no need to harm the plant on which the vine is growing. μηδείς (talk) 03:24, 1 September 2013 (UTC)

You're right - we aren't using them again. My wife was furious. He cleaned out the vines but cost at least a couple of years of growth. My wife and I planted them ourselves a few years ago. The vines are threatening to take over again. Bubba73 ^{You talkin' to me?} 04:25, 1 September 2013 (UTC)

Exactly what is being referred to by "vines" here? In my part of the world the word vine immediately brings up images of grape vines. Those in this section are being described as if they are some sort of weed. Is that the case? HiLo48 (talk) 04:30, 1 September 2013 (UTC)

I was wondering that, too! Whatever the type of weed, applying an appropriate weedkiller with a paintbrush (as described by SemanticMantis above) instead of a spray should stop the regrowth (after cutting down), though this method will require some patience. Make sure that the weedkiller is one rendered harmless by soil so that it doesn't affect the azalea. I've got rid of ground elder amongst other low-growing plants by this method (even though some "experts" claim that this is impossible without digging out). For some woody weeds, a selective hormonal weedkiller such as "SBK" (formerly containing 2,4-Dichlorophenoxyacetic acid and 2,4,5-Trichlorophenoxyacetic acid in the UK) might be quicker, but availability might be restricted by law. I think this has been replaced by Triclopyr for domestic use. Be careful, though, because azaleas are shallow-rooting, so any soil contamination might affect them. The really environmentally friendly method is to regularly remove new growth by hand as it appears, but that's very time-consuming. Dbfirs 08:35, 1 September 2013 (UTC)

See liana. In AU, e.g. cat's claw creeper is considered a weed of national significance [2]. Due to their extensive root systems, and growth of rhizomes and stolons, vines can be very challenging to remove. If you've never had to deal with aggressive, undesirable vines, consider yourself lucky! SemanticMantis (talk) 13:22, 1 September 2013 (UTC)

I've added two photos. Bubba73 ^{You talkin' to me?} 14:38, 1 September 2013 (UTC)

Yeah, that's grape (see leaf here. Contrary to HiLo's response above, grape is very much a weed, at least where I live (SW Ontario). I never tried herbicide in my war against it, but pulling it physically was an unending task. Good luck. :) Matt Deres (talk) 14:56, 1 September 2013 (UTC)

It doesn't produce Grapes, at least it hasn't so far. (Maybe it takes many years to do that.) Bubba73 ^{You talkin' to me?} 15:25, 1 September 2013 (UTC)

Those vines look like muscadine/scuppernong, which is a New World native grape, and yes, is a weed insofar as the wild varieties can choke out desired garden plants. The grapes tend to not grow in large bunches, but rather as small individual grapes along the vine, perhaps in small bunches, but not in the traditional pyramidal grape bunches you expect from European wine grapes. We have them all over the edge of the woods along our property in North Carolina. I've been successful, so far, at keeping them out of my gardens. --Jayron32 19:00, 1 September 2013 (UTC)

Habits

I forgot the name of a condition where sufferers act in odd ways; such as excessively cleaning your hands, a need to position objects in a very specific way, etc. I think its obsessively compulsive disorder or something like that. Pass a Method talk 23:49, 31 August 2013 (UTC)

Obsessive-compulsive disorder. 86.141.185.189 (talk) 23:54, 31 August 2013 (UTC)

September 1

Can it be proven that people dream?

Can it be proven that people dream while they are asleep? Bubba73 ^{You talkin' to me?} 01:06, 1 September 2013 (UTC)

You mean apart from the evidence of their own mouths? Can it be proven that people are merely hallucinating when they relate the details of an alleged "dream" they just had? -- Jack of Oz ^{[pleasantries]} 01:12, 1 September 2013 (UTC)

I have a friend who keeps quoting some unnamed scientist who (according to my friend) says that people just make it up when they wake up. Bubba73 ^{You talkin' to me?} 01:27, 1 September 2013 (UTC)

So why are you asking us, rather than your friend? What would constitute a proof? Has neither of you ever slept next to someone and noticed them dreaming? Maybe your friend is a zombie, and not having a consciousness, finds it impossible to imagine others having mental states? μηδείς (talk) 01:37, 1 September 2013 (UTC)

Because I think he is using it as a way to criticize the scientist. I'm pretty sure that he doesn't doubt that there are dreams, but he criticizes the person who said that they can't be proven (and empiricism - or Positivism). Bubba73 ^{You talkin' to me?} 02:57, 1 September 2013 (UTC)

Oh, well, thank God for that! There are all sorts of problems with naive and traditional empiricism. David Kelley's Evidence of the Senses is a good graduate/upper class-level treatment of some of the problems with and solutions to empiricist problems--although he deals with perception, rather than dreams. μηδείς (talk) 03:18, 1 September 2013 (UTC)

Take two witnesses and you have proof81.218.91.170 (talk) 03:27, 1 September 2013 (UTC)

Naturally we have an article, Dream. There's a lot of content there on neurological aspects of dreams that must go pretty close to proof. HiLo48 (talk) 01:23, 1 September 2013 (UTC)

The OP's friend may very well be thinking of Freud's distinction between the manifest and latent content of dreams - it's not actually mentioned in our article on The Interpretation of Dreams, but see Dream#Dynamic psychiatry. Tevildo (talk) 01:49, 1 September 2013 (UTC)

I should think sleep-walking, talking in one's sleep, etc., show that some type of dreaming occurs, unless you think that's all faked, too. Then there's brain scans which show activity in the part of the brain we associate with dreaming. StuRat (talk) 10:15, 1 September 2013 (UTC)

And the visual part of the brain starts working, even though there is no input from the eyes. Bubba73 ^{You talkin' to me?} 15:51, 1 September 2013 (UTC)

Exercise and blood sugar control in diabetes

I just finished reading the novel One Second After. One of the characters has (type 1) diabetes, and eventually dies from hyperglycemia. I am curious why a lack of insulin would necessarily prove fatal if she were fasting (it's a disaster novel) and exercised. Do diabetics reach some sort of wall that prevents their lowering their blood sugar below a certain point, even with fasting and exercise. I always though exercise necessarily lowered one's blood sugar. (Searches on google lead to a bunch of quackery, and if we have a relevant article, I haven't found it.) Thanks. μηδείς (talk) 04:57, 1 September 2013 (UTC)

Yes, exercise should lower blood sugar. Are you sure the character didn't die from low blood sugar ? That tends to cause immediate death, whereas high blood sugar causes organ damage that leads to eventual death. StuRat (talk) 10:12, 1 September 2013 (UTC)

I don't see how exercise would lower blood sugar unless you were to use more insulin. People with diabetes who do exercise use more insulin to be able to exercise at a high intensity. Count Iblis (talk) 14:27, 1 September 2013 (UTC)

The character died of distinct hyperglycemia, and a doctor explained to her family what to expect. What confuses me is that if one exercises, one's blood sugar drops, although the body will still produce sugar in the liver from fat. So I am wondering, if one were trim and exercising, wouldn't it be possible to lower the blood sugar to 100 and at that point not have to use insulin, just a balance of exercise and diet?

As our insulin article explains, insulin controls the ability of glucose to get into muscle cells. Without insulin, exercise will not be possible unless blood sugar levels are extremely high, because otherwise the muscles won't get enough sugar to function. Looie496 (talk) 18:10, 1 September 2013 (UTC)

I guess the difference must be between type 1 and type 2, then. My father has type two, and he is fully controlled by having lost 50 lbs and from exercise, and removing rice, carrots and potatoes from his diet. He doesn't have any metabolic issues like muscle weekness. I have only known one person with type one, and I found it weird he was always eating carrots. There seems to be a radical difference between the two types. μηδείς (talk) 18:31, 1 September 2013 (UTC)

If a Type 1 diabetic has no insulin production by the pancreas, exercise alone may not be able to keep blood sugar down to an acceptable level, since insulin is needed for muscles to use the sugar in the blood as fuel. In the novel cited, the Type 1 daughter died after 131 days. In the real world, Elizabeth Hughes Gossett developed type 1 diabetes before insulin was available. Her doctor and a full-time nurse were hired by her rich and powerful father, New York Governor, and later Supreme Court Justice, Secretary of State and Presidential candidate politician Charles Evans Hughes. Her blood sugar was monitored frequently, which would have been quite possible in the novel's scenario, and her diet was restricted to keep blood sugar down to a safe level. This was at the cost of slow starvation, and she eventually after 3 years her weight had decreased from 75 pounds at (34kg) age 11 to 45 pounds (20.4kg) at age 14. She stayed alive and avoided common consequences of high blood sugar (blindness, amputations) had no energy to do any exercise or other activities by then. Then along came insulin, and she, as one of the first patients, lived another 59 years of healthy life. So survival beyond to 131 days in the novel might be possible, and was documented out to 3 years, at the cost of severe starvation, which can also be fatal as well as debilitating. But in an apocalypse novel, someone might be able to get generators etc running in a year or so and bring back some technology, with the production of medicines getting some priority. Edison (talk) 00:53, 2 September 2013 (UTC)

Wow, excellent, one of the best answers I have gotten or seen at the ref desk! μηδείς (talk) 01:55, 2 September 2013 (UTC)

The thing is, I doubt if any diabetics have zero insulin production, they just have an abnormally low level (if they had zero then their hearts would stop beating from lack of blood sugar in the cells). So, some exercise is still possible, and still burns blood sugar. StuRat (talk) 00:58, 2 September 2013 (UTC)

But can't the heart use fat as energy? Count Iblis (talk) 02:21, 3 September 2013 (UTC)

Not directly. It must first be converted into blood sugar. StuRat (talk) 08:34, 3 September 2013 (UTC)

But doesn't the breakdown of fatty acids happen inside the cells via Beta oxidation? Count Iblis (talk) 14:02, 3 September 2013 (UTC)

Good point. StuRat (talk) 07:41, 4 September 2013 (UTC)

Orchids

There are orchids in all climate zones. But the orchids on sale in western Europe are a smaller choice. Some orchids don't give flowers anymore after one year at home. Are they any tricks? Thx --Chris.urs-o (talk) 08:36, 1 September 2013 (UTC)

This site is probably the best you can get, and here is what they recommend. --TammyMoet (talk) 11:14, 1 September 2013 (UTC)

Thank you --Chris.urs-o (talk) 11:52, 1 September 2013 (UTC)

Orchids in all climate zones? Is this a joke? CambridgeBayWeather, could you pls. verify? 24.23.196.85 (talk) 00:43, 2 September 2013 (UTC)

I know, I'm often surprised by my own lack of knowledge. Isn't nature amazing! Richard Avery (talk) 06:44, 2 September 2013 (UTC)

Coupled atoms

Consider a chain of identical atoms (with mass M) that are connected by springs with alternating spring constants K1 and K2 and nearest neighbour separations of a/2.

Write down an expression for the force experienced the atoms, considering longitudinal motion only and construct a pair of differential equations describing the system.

I find this question puzzling. Is it even solvable, given that there are infinitely many atoms? In the finite case, you have a differential equation for each mass. Why do you only get two differential equations, rather than an infinite number?

150.203.188.147 (talk) 14:11, 1 September 2013 (UTC)

You need to number your atoms (atom 1, atom 2, atom 3... along the chain), then you can write an equation for the force on (and hence the acceleration of) atom n in terms of the positions of atom n - 1, atom n itself and atom n + 1 (you could the positions x_n-1, x_n, and x_n+1). This looks like one equation, but it can be regarded as an infinite number of equations, one for each integer value of n. Actually, since the spring properties alternate, there will be two such equations, one for odd n and one for even n. --catslash (talk) 15:21, 1 September 2013 (UTC)

Wikipedia does not seem to have an article on waves in periodic structures (which is an unfortunate omission). However Léon Brillouin wrote a famous book on the subject, which covers exactly the problem you describe. --catslash (talk) 15:45, 1 September 2013 (UTC)

It's easier to solve when you impose periodic boundary conditions, because then the system is invariant under translations. It is helpful to denote position of the atoms by x_1, y_1, x_2, y_2 etc. so that all the atoms at the positions x_j interact in the same way with their nearest neighbors and also the atoms at the positions y_j interact in the same way with their nearest neighbors. If there are 2N atoms, then the periodic boundary conditions imply that x_{j+N} = x_j and y_{j+N} = y_j. The two sets of differential equations that Catslash mentions can then be solved by performing a Fourier transform, you put:

$x_{j}=\sum _{q=1}^{N}v_{q}\exp \left({\frac {2\pi iqj}{N}}\right)$

$y_{j}=\sum _{q=1}^{N}w_{q}\exp \left({\frac {2\pi iqj}{N}}\right)$

If you substitute this in the differential equations you obtain a decoupled set of differential equations for the v_q and w_q. Count Iblis (talk) 16:29, 1 September 2013 (UTC)

OK, Thanks. I get

$-K_{1}(x_{j}-y_{j-1})+K_{2}(y_{j}-x_{j})=M{\frac {d^{2}x_{j}}{dt^{2}}}$

$-K_{2}(y_{j}-x_{j})+K_{1}(x_{j+1}-y_{j})=M{\frac {d^{2}y_{j}}{dt^{2}}}$

Assuming the atomic motions can be described by periodic functions of the form $u_{n}=Ae^{i(kx-\omega t)}$, derive

$\omega ^{2}(k)={\frac {K_{1}+K_{2}}{M}}\left(1\pm \left(1-{\frac {4K_{1}K_{2}\sin ^{2}\left({\frac {1}{2}}ka\right)}{(K_{1}+K_{2})^{2}}}\right)^{\frac {1}{2}}\right)$

How do you do this?

150.203.188.147 (talk) 03:05, 2 September 2013 (UTC)

The second derivative w.r.t. t brings down a factor omega^2, and you also have that x_{j+1} = exp(i k a) x_{j}, and similarly for the y_j, so you get two ordinary equations for the two amplitudes of x_j and y_j (the factor "A" should be taken differently for y and x). If you write this in matrix form, then the determinant should be zero. If the determinant is not equal to zero, then you have a unique solution, which is the trivial solution where both amplitudes are zero. If the determinant is zero, then there is no unique solution to the linear equations which means that the amplitudes are not fixed, which means that the system has a vibrational degree of freedom when choosing the omega and the value for k in that way. Count Iblis (talk) 14:00, 2 September 2013 (UTC)

Gravitational time dilation in black holes

If around a black hole the time stops to us external viewers, a black hole to us would never collapse into a singularity but the matter would stop around event horizon and (to us) would never form a singularity! So the idea of a nude singularity would be wrong (becuse to us would not even form a singularity) and a a black hole would never evaporate (the famous stephen hawking radiation) to us (and to all external universe) because the negative energy's particle would never enter (to us) the black hole! Can someone explain to me this paradox? 80.117.238.25 (talk) 16:48, 1 September 2013 (UTC)

There are two possible answers here, explained in detail in this article. Count Iblis (talk) 16:59, 1 September 2013 (UTC)

That doesn't matter in the least. Hawking radiation actually comes from the neighborhood of the B-hole, not the B-hole itself and the negative energy particle will add negative energy to the B-hole even if it never reaches it because from the external point of view all the mass surrounding the B-hole must be added to the B-hole's mass in order to calculate the total gravitational effect. In effect, from the external observer point of view, the mass of the B-hole itself is always zero since nothing ever reaches it. Dauto (talk) 01:20, 2 September 2013 (UTC)

That's true - but all of the mass would arrive within a tiny fraction of a millimeter in short order - so the gravitational difference between it all being at the singularity and it all being frozen into a perfect spherical shell just above the event horizon is pretty minimal. Especially since any observer getting close enough to tell the difference would be in more or less the same reference frame as all of the frozen material. SteveBaker (talk) 15:24, 2 September 2013 (UTC)

And why is written that all black hole's mass is concentred into a singularity?95.239.233.27 (talk) 21:58, 2 September 2013 (UTC)

Because General Relativity is not a compulsory school subject. Count Iblis (talk) 23:35, 2 September 2013 (UTC)

Because from the point of view of an object falling in a B-hole matter does indeed reach the singularity after a finite amount of time. Dauto (talk)

And (perhaps more importantly), from the perspective of the black hole itself. SteveBaker (talk) 01:04, 3 September 2013 (UTC)

Sending probes to other systems

Do we currently have the technology necessary to send a satellite to another star system and put it in orbit around an exoplanet? I'm not looking into whether we have the exact parts necessary but more the knowledge and know-how to do it. (Yes, I know it would take hundreds of years to get there.) Dismas|^(talk) 18:40, 1 September 2013 (UTC)

Not even close. The current farthest man-made object from Earth is the Voyager 1 probe, which is currently 18,700,000,000 kilometers from Earth, and has taken about 36 years to get there. At that speed, if it were actually aimed at the nearest star system to Earth (Proxima Centauri), which is a distance of 40,000,000,000,000 kilometers from Earth (give or take), which, if my calculations are correct, is roughly 2,100 times farther than Voyager 1 has yet traveled, and thus it would take such a probe 75,600 years. While some technology has improved in the 36 years since voyager has left Earth, there hasn't been enough changes to make a significant dent in sending an object that far. Even if we could cut that down by an order of magnitude, that would still leave us with a 7,500 year voyage. For comparison, going back in the past 7,500 years is older than the oldest known writing, back to the dawn of civilization. If you were to go back 75,600 years, humans were still living in caves trying to kill mammoths with pointy rocks and outrun sabre-toothed tigers. So, no, such a voyage, even by an unmanned probe, is outside our current practical technology to do within a reasonable amount of time. --Jayron32 18:53, 1 September 2013 (UTC)

That's not a fair assessment. Voyager wasn't designed to do that. It was launched on a Titan III rocket - nowhere close to the most powerful rocket we've ever made - the Saturn V can launch almost 10 times the payload to LEO. Also, those are all-in-one launches. If we made a dozen Saturn V launches - and using the orbital assembly technologies we now have - we could assemble a garganutan booster stage in orbit. Voyager is also a LARGE device by modern standards. Miniaturization could shrink the weight considerably. Besides, our OP clearly doesn't care if it takes time to get there.

There are really two big problems:

• Communications. The multi-year communications delay would require a much more autonomous device...and having the power to transmit a signal from orbit around another star back to earth and the receiver sensitivity to detect our commands to it are beyond what we can currently do. So we could get the probe out there - but getting any information back from it would probably be impossible.
• Slowing down at the destination to get into orbit. Carrying enough fuel to do that deceleration would be extremely problematic - and using tricks like atmospheric braking would be insanely difficult given how little we know about the atmosphere (or even the existance) of planets that we might use for that! Autonomously deciding those things would be very tough indeed.

SteveBaker (talk) 19:22, 1 September 2013 (UTC)

If you have the 80,000 years you need a space craft which has a propulsion system which can be restarted after 80,000years I would go for ion engine where you only have to store gas. It has to produce energy for this propulsion best with solar panels because RTGs go only for a few half-lives. The ageing of the material by cosmic rays especially the computer chips might be the most challenging thing. I have no clue what the ageing is like but voyager is still working. The only thing will be sending back the data you collect. A signal strong enough might be a little complicated, but I think even this you might get to work. I would think it would be a very costly but with the 50b$ it might be a funny project.--Stone (talk) 19:25, 1 September 2013 (UTC)

Yes, that's certainly another problem. Most electronics have some minimum storage temperature, and if they are allowed to get colder than that, they'll stop working even if they are warmed up again. If the craft has to drift through deep space for tens of thousands of years then it's hard to imagine any power source that would keep the electronics warm enough to prevent them from dying. Voyager is kept warm by RTG's - so it'll certainly get cold and die before it reaches a few light years from here.

The NASA Innovative Interstellar Explorer (IIE) project could get a probe to the nearest star in 25,000 years - but that's engineered for a particular cost - and in particular, a cheap rocket launch. If our OP doesn't have cash restrictions, then I think we can do much better.

We clearly need two orders of magnitude of speed improvement over Voyager or one and a half orders over IIE, so we can get there in under a thousand years. One order of magnitude can certainly be had by using a bigger rocket and assembling it in orbit - and we know how to do that. A Saturn V rocket, assembled in LEO would give us vastly more delta-V than the Titan III (launched from earth's surface) did for Voyager. Another order of magnitude can probably be had by shrinking the size of the satellite and using a small ion motor in the final stage - a device like that needs a tiny amount of propellant and can be powered by solar panels or from a large laser in earth orbit...and we know how to do that too. We also know how to get more speed using various slingshot maneuvers that were not tried for Voyager.

So I don't think it's impossible to get the craft there in under 1,000 years - and a sufficiently large RTG could keep everything warm for that long. Our Radioisotope thermoelectric generator article suggests that Americium-241 (with a half-life of 430 years) could possibly do the job - but that issues with shielding would make it difficult to use. Radioisotope_thermoelectric_generator#RTG_for_interstellar_probes says that NASA have been working on exactly that in their Innovative Interstellar Explorer project. In our case, we only need to shield the sensitive electronics - and whatever heavy lead shielding was needed while close to the Earth could

be ejected in the acceleration phase of the mission.

In the end, money is the single limiting factor to doing what the OP wants.

I believe that all of the technologies we need are there...although communications with the satellite when it gets there will likely be impossible...and if that's the case then I can't see anyone wanting to spend the money to do it. But that's not what we're being asked here.

SteveBaker (talk) 15:18, 2 September 2013 (UTC)

Years ago I read an article in one of the technical journals devoted to rocket science. The article probably was published in the fifties. The author analyzed a possibility of reaching other stars in a reasonable time span of roughly 80 years. His assumption was that the craft (with people) will accelerate half of the way and decelerate during the other half. He came to the conclusion that the only (theoretical) option was to use antimatter/matter annihilation and the mass of the fuel (antimatter/matter) required would be equal to the mass of the earth. He clearly showed that it is impractical.

- Alex174.52.14.15 (talk) 03:44, 3 September 2013 (UTC)

That might be about right - the amount of energy if the earth was annihilated in a matter/antimatter reaction would be 5.4×10⁴¹ Joules (see Orders of magnitude (energy))- if the craft weighed more or less what the Earth weighs (assuming the craft itself weighed almost nothing compared to the fuel) then it would be 5x10²⁴ kg. To accelerate (and decelerate) it at 1g would require (F=ma) a force of 5x10²⁵ newtons to be applied over the whole 4 light-years (4x10¹⁶ meters) - which is (Work=force x distance) 2x10⁴²...about five times the amount of energy you'd get from annihilating the earth in that matter/anti-matter explosion. However, that's not quite right because as you use up fuel, the craft gets lighter - so you'd save a lot of energy towards the end as the mass gets used up - so I could believe that one-earth-mass is enough to keep us going at 1g.

HOWEVER: Applying a constant force of 1g only makes sense if you want to take people there. What you really want to do to take a satellite there is to apply a very brief, intense acceleration at the beginning and end of the trip. If some variation of atmospheric braking can be used to slow you down at the end - then you just need one gargantuan kaboom to achive solar escape velocity - and then you can coast to the destination.

By accelerating much faster at the beginning, your peak velocity can be much lower but your average velocity be exactly the same - and still get there in the same amount of time - but using a lot less energy. Hence you need less fuel...and less fuel means less mass...which means less force...less energy...and less fuel. We also have a vastly smaller craft because we're not taking people, food, water, oxygen, etc.

So with an initial big push, you can get places with vastly less energy than if people are on board and demand 1g acceleration all the way.

That means that what you read wasn't so far from the truth - but it's not applicable to our OP's problem.

SteveBaker (talk) 17:56, 3 September 2013 (UTC)

That seems like the perfect job for an Orion drive for the initial 12% c acceleration and then eject the Orion drive and (hopefully because of Oberth effect the efficiency will increase) use the beamed core antimatter drive to accelerate to 70% c. Then, at the destination star system, use their star to do reverse gravity assist (and even aerobraking using the star atmosphere) No one will be interested to fund a too long mission 202.137.25.53 (talk) 04:31, 5 September 2013 (UTC)

SteveBaker, you are very knowledgeable, it is interesting to read what you wrote but overall I believe humankind will never try to reach other worlds manned or unmanned way. It will be just too expensive and too risky. Half of missions to Mars have failed historically. And they cost so much that even the United States had to wiggle to make them less expensive. Without calculations just on intuition it seems the cost to build a probe for interstellar travel will be three orders of magnitude higher. And the risks will be three orders of magnitude higher as well. No, this is a totally absurd idea in my opinion. Nobody will give a dime to make it happen if they are in their sound mind.

- Alex174.52.14.15 (talk) 02:33, 4 September 2013 (UTC) — Preceding unsigned comment added by 174.52.14.15 (talk) 02:32, 4 September 2013 (UTC)

Oh - absolutely! I don't think it'll happen anytime soon - perhaps never. Clearly humanity's quest into space has already peaked and is in sharp decline. It's technologically feasible - but the scientific merit and economic benefits seem to be utterly overwhelmed by the cost.

IMHO, (and I've spoken about this idea in detail in the past) - the only way to explore the universe is with robotic craft. Perhaps we can find a way to encode our brains onto silicon neural-networks and treat our psyche's as a bunch of software - and then we can fire a probe off to the nearest star - and with the CPU clock ticking once a year, experience the trip to the next star system in a few hours. When we get there, we can transmit our thoughts and findings back to Earth and tell our friends what happened.

This may happen by scanning brains and emulating the wet-ware using software - or it might be that in enough generations, Artificial Intelligences are accepted as first class citizens and treated as sentient beings. With acceptance of those "people" as our equals, we can send an AI human to the stars much more easily than a wetware human. Software minds can be transmitted via radio or laser links at the speed of light - we can slow them down to avoid boredom and resource utilization on thousand year space trips and speed them up when we need to put the world into slow-motion. We can have immortality if that's what we wish and we can archive our minds to be awoken ten thousand years into the future.

I think that's the future of humankind...and it solves nearly all the issues of spreading throughout the universe and over all of time. I give it a hundred years to happen. SteveBaker (talk) 14:52, 4 September 2013 (UTC)

"Element analyser"

In a TV programme I watched, they had a hand-held gadget that they called, I think, an "element analyser", or something like that. When held against a metallic sample, this displayed the percentages of each element in the sample (e.g. 75% Ag, 23% Cu, 2% Pb). It seemed pretty neat. How might it have worked? Would it be able to detect any element, or only a few common ones? How accurate might it have been? 81.159.109.215 (talk) 19:16, 1 September 2013 (UTC)

Some of the sensors used on (for example) the mars probes can do things like that. They use the principles of a spectrometer to look for spectral lines in the light emitted when the target material is heated with a laser.

The Curiosity (rover) does this exact thing with four different instruments: See Alpha particle X-ray spectrometer, CheMin, Sample Analysis at Mars and so forth. I don't know whether hand-held versions of these things exist (or are even possible given radiation hazards, etc) - but they are small, light and don't use much power - so I suppose it's possible. SteveBaker (talk) 19:30, 1 September 2013 (UTC)

(ec) Energy-dispersive X-ray spectroscopy is one way to do it, as is laser-induced breakdown spectroscopy (used by the Curiosity rover) and alpha particle X-ray spectrometer (used by Curiosity, Spirit and Opportunity). There's also various mass spectroscopy based methods, if you don't mind volatilizing the surface of the sample. You can also take a look at List of materials analysis methods for other possibilities. -- 71.35.99.22 (talk) 19:31, 1 September 2013 (UTC)

None of the mentioned with the exception of the APXS is a hand held device. Some use vacuum some use high voltage others use large optical systems. But you can not buy APXS it because it has a little curium inside.--Stone (talk) 19:41, 1 September 2013 (UTC)

An ICP-AES spectroscope could be used as an "element analyzer" for ALL of the currently known elements, but it's not handheld -- the smallest of these instruments is the size of a large briefcase. Also, this instrument requires you to dissolve the sample before analyzing. 24.23.196.85 (talk) 00:39, 2 September 2013 (UTC)

• Thanks, I think it may have been something like these, which apparently work using X-ray fluorescence. 81.159.109.215 (talk) 00:48, 2 September 2013 (UTC)

Correct Location for "Ethno" Medicines

I'm wondering where the correct place for mentioning "ethno" medicines would be. Would it be under the organism that is used, the illness it is believed to treat or under the tribe which believes in this practice? I wasn't really sure where to ask this question as it concerns often religious views towards biological organisms which may be based on facts already established by other societies. CensoredScribe (talk) 02:48, 2 September 2013 (UTC)

Traditional medicine is our main article. I'm not really sure what you're asking, though. As an example, the use of rhino horn in traditional medicine is covered in our Rhinoceros article, and (provided you can provide reliable sources for the information), you can add similar information to any other animal's article. Is there a specific animal/disease/tribe you're interested in? Tevildo (talk) 23:14, 1 September 2013 (UTC)

There is this Chilean Rose tarantula used by the Chola Maya to make a tea to treat atrial fibrilation and cardiac arythmia. So basically the only animals and plants that wouldn't have an established traditional medicine usage by at least one tribe; would be those deep under ground, in the deep sea and at the poles; places no humans have ever lived?

Why would you assume that every plant and animal that people could access would have a "traditional medicine use"? Falconus^{p t c} 14:06, 2 September 2013 (UTC)

This is the reference cited above. (And it's the Mexican red rump tarantula, Brachypelma vagans, not the Chilean rose tarantula, Grammostola rosea, incidentally). This certainly could be added to the article. I'm not sure the second question can be answered. Tevildo (talk) 01:15, 2 September 2013 (UTC)

James Wong describes himself as an "ethnobotanist" so presumably ethnobotany would be the scientific field for this. --TammyMoet (talk) 08:33, 2 September 2013 (UTC)

With respect to a major medical disorder, one needs a proper secondary source to justify inclusion. In general secondary sources are required. Doc James (talk · contribs · email) (if I write on your page reply on mine) 00:36, 3 September 2013 (UTC)

Describing traditional practices is not a medical claim of efficacy and no such depth of sourcing is required. Wnt (talk) 14:20, 3 September 2013 (UTC)

Black and white races in sports and science

This is not a discussion forum
The following discussion has been closed. Please do not modify it.
Seems like black people are better than white in most athletic sports. I've been told by several people that black people have more advanced muscles, but that their brains are smaller and thats why very few of them are successful scientists. I tried googling and "black supremacy in sports" gives a lot of results, while "brain size difference between whites and blacks" mostly gives links to different racist websites, so I was wondering if it is true that blacks are better at athletic activities than us because of the muscle differences and is it true that we have bigger brains? And if these thesis are racist, as some people suggest, then why are black so much faster and why are white people so much better at scientific achievements, fine literature, arts and so on? Thanks. — Preceding unsigned comment added by 109.121.18.183 (talk) 22:14, 1 September 2013 (UTC) Who is "us"? I would delete this post. Bus stop (talk) 22:21, 1 September 2013 (UTC) There are so many things that can be commented on here that I'm not going to start. Instead, I'll just direct you to Race and sports and you can explore from there. Dismas|(talk) 00:08, 2 September 2013 (UTC) The question should be deleted. It contains "...so I was wondering if it is true that blacks are better at athletic activities than us because of the muscle differences and is it true that we have bigger brains?" Who is us and who is we? Is this the Reference-desk/Science for white people? Bus stop (talk) 00:27, 2 September 2013 (UTC) The bottom line is, while blacks do in fact have more physical strength and endurance, and whites and Asians do in fact have a higher IQ (on average, of course), nobody at this time knows for sure what causes these discrepancies -- whether genetics, upbringing, or whatever else. And no, this question SHOULD NOT be deleted -- it is a legitimate question (although poorly phrased), and deleting it would serve no purpose except for advancing the same politically correct agenda that is currently preventing any meaningful research on this subject. 24.23.196.85 (talk) 00:32, 2 September 2013 (UTC)

September 2

The power of intention? How does modern neuroscience explain this bit of ancient wisdom?

Although my spiritual side is content with simply accepting the power of intention as a given, and even celebrating its mysterious nature, the scientist in me is convinced that at least some of the mystery can be associated (without necessarily establishing causality) with detectable, measurable brain activity. I have a deep need to study this further. Where should I begin? Agiftagain (talk) 02:51, 2 September 2013 (UTC)

Begin by recognising that it has little or nothing to do with neuroscience and nothing to do with anything mystical or of some ancient wisdom, but instead is a matter of personal discipline, clear thinking, and commitment. Then, consider carefully the following truism, often taught in management classes in the last few decades:-

Whatever you Vividly Imagine,

Ardently Desire,

Sincerely Believe and

Enthusiastically Act Upon

Must inevitably come to pass.

and if that doesn't help, remember that an effective man has the energy to change what he can, and the wisdom to not waste time on what he cannot change.

Then, and only then, read books on effective living and achieving one's goals.

1.122.55.179 (talk) 07:01, 2 September 2013 (UTC)

"Vividly" and "ardently" remind me of another truism: that if you pray hard enough, you can make water run uphill. How hard? Hard enough to make water run uphill... Wnt (talk) 08:07, 2 September 2013 (UTC)

Well it's possible, and maybe someone with the right accesses to the right articles can check this out. Here is an article that quotes various papers saying that attitude and/or visualisation contribute as much to health and fitness as actual physical activity. --TammyMoet (talk) 08:31, 2 September 2013 (UTC)

What do you mean by "power of intention" exactly ? Are you referring to Wayne W. Dyer's book (ISBN 9781401902162) where he claims that intention is "a force in the universe that allows the act of creation to take place" ? Sean.hoyland - talk 08:55, 2 September 2013 (UTC)

Isn't Dyer some motivational speaker? so that would be just guff to get people off their backsides. As to it being a real physical force one might as well believe Block Transfer Computations underly reality. This sounds to me like the Cowardly Lion saying 'I do believe in spooks, I do I do I do! This is the Science desk and really something better than being happy with an idea and celebrating its mysterious nature is needed before something gains any acceptance. If this had gained some experimental evidence as a physical force it would be very big news, but all we get for psychic powers is people offering money for some sort of demonstration and charlatans refusing to be tested. Dmcq (talk) 12:03, 2 September 2013 (UTC)

It's demonstrably not true - plenty of people have done that whole set of things and failed.

EXAMPLE: Consider Einstein's efforts to come up with a "Theory of Everything" - he clearly believed that such a theory existed, he believed it was possible for him to discover it, he spent a good fraction of his life seeking it, so he clearly both desired and believed it, he worked on it until literally his dying day - and it didn't happen. Bzzzztttt!!! Fail!!!

I could come up with any number of other examples where this idea has simply failed to be correct.

So it's busted - it's a great idea to encourage people to pursue an idea enthusiastically - but promising them that if they do that, they'll definitely succeed is new-age bullshit. The "theory of intention" is a false hypothesis - and we (and our OP) can stop worrying about it.

QED. SteveBaker (talk) 14:37, 2 September 2013 (UTC)

Einstein belived in it, he ardently desired it, and he enthusiastically worked on it maybe, but he failed to vividly imagine it. 144.138.223.100 (talk) 15:35, 2 September 2013 (UTC)

First time I've heard Einstein associated with a lack of imagination! Dmcq (talk) 18:02, 2 September 2013 (UTC)

I don't know how you came up with that one - but it's flat out untrue. He had imagined it since the very beginning of his work on the subject. He's known for having that very imagination. You can't squirm out of this one. When a man knows he's dying and on the last day of his life, he's still frantically scribbling equations in the hope beyond hope that he'll somehow come up with the answers with his last living breath - you can't imagine anyone who had all of those attributes that motivational speakers claim will - with 100% certainty - get what they want. Sorry - but this is so busted. SteveBaker (talk) 01:02, 3 September 2013 (UTC)

Nope, not busted at all. Nowhere did I claim that Einstein did not have an imagination. Nowhere did I (or anyone else here) claim that having all the attributes spoken about gets 100% success. There is an important difference between "imagining" one can solve a problem (ie having faith without knowing how) and vividly imagining a solution (ie visuallising/conceptualising the steps so that a proof or solution is rendered a mechanical process). Biographies on Einstein make it clear he had faith that there is a theory of everything, as that has much emotional and personal achievement appeal, but he had little idea on how to go about elucidating it, and was reduced to the "Edison" method - just keep trying every silly darn thing. I can "imagine" I'll win the State lottery, and enthusiastically buy vast numbers of lottery tickets. Most likely, a fat lot of good that will do. Or I could imagine the steps, risks, and challenges involved in corrupting the person who built and maintains the machine that selects the numbered balls in the draw. Yeah! I can vividly imagine that working a treat! 120.145.73.63 (talk) 05:13, 3 September 2013 (UTC)

So what you're saying is that because Einstein hadn't completely visualised the solution and every step leading up to it, he couldn't find the solution? So if I want a new car, then if I can visualise how I can train for a job, apply for the job, work at the job, earn more money, take it to the car dealership and visualise how to sign on the dotted line, then I can get a car? That's just saying that if you've correctly worked out all of the steps to do something in exacting detail with no possibility of any of the steps failing - and you didn't make any mistakes and if you follow those steps exactly...then you can make it happen...that's hardly any great insight! It boils down to "If you know exactly all of the steps to do something and you do all of those steps then you can do something"...not really something anyone needs a motivational speaker to tell them! It's definitely not what was quoted above:

Whatever you Vividly Imagine,

Ardently Desire,

Sincerely Believe and

Enthusiastically Act Upon

Must inevitably come to pass.

The words "must" and "inevitably" in the last sentence do indeed provide a 100% guarantee...and there is no requirement to vividly imagine all of the intermediate steps - it says that whatever I vividly imagine (eg: Walking on Mars), yadda,yadda...must inevitably come to pass. That's nonsense. It's not enough to vividly imagine/desire/believe/act-upon an end result - which is most definitely what these people promise. Instead, I have to vividly imagine/desire/believe/act-upon every tiny step along the way - from applying to NASA for astronaut training to lobbying congress for the money to fund it...and every teeny-tiny micro-step along the way. In fact, even that isn't enough because there are going to be a bunch of conditional steps there too.

Many other things - like wanting to go on a picnic in Hyde park on my birthday - will not "inevitably" come true no matter what I do because the weather might turn out to be terrible and there is nothing I can do to prevent that. I can't even visualize it correctly because chaos theory prevents me from predicting the weather ten months from now.

This is just prime new-age wishful thinking bullshit. You wish your kid didn't have a strictly median IQ and behavioral problems in school - so you vividly imagine it and lo and behold, it turns out that he has a purple aura - so it's all OK. SteveBaker (talk) 17:15, 3 September 2013 (UTC)

Now you are being silly, Steve. The Whatever you Vividly Imagine thing is a truism - an easily remembered menomic that offers guidance. If you think it contains a large element of truth, you are on the right track, as you may then be willing to persue things that are hard - but you will not persue things that are beyond control just because you know this truism - if you do then clearly you are silly. In appying the truism, you don't have to know the details right away.

If whoever originaly wrote these words had instead tried hard to make it accurate, it would be wordy and not have a nice ring to it and be easily remembered. Like "People who live in glass houses shouldn't throw stones" - another truism that is a lot of good sense and isn't meant to be taken literally, and doesn't mean that anyone who does throw a metaphoric stone at someone else cannot ever profit from it - some do. Mud sticks.

60.230.217.174 (talk) 00:19, 4 September 2013 (UTC)

If that's what is being said here (and I don't believe that it is because then our OP wouldn't need all of the mysticism, neuroscience and ancient wisdom), then here is a better version:

If you want something to happen,

Research what it takes,

Plan it in detail,

Follow through on your plan,

...and the odds of it happening improve somewhat..

Not exactly the kind of thing that'll pack a motivational speaker's auditorium with converts at $200 a head - but the actual truth. Please feel free to write a 500 page book about "The mantra of Steve" and sell it at your seminars. SteveBaker (talk) 14:39, 4 September 2013 (UTC)

I'm glad you are finally close to what it is about, Steve. But you're right, your version won't inspire many. It won't because it doesn't have two things that the Vidily Imagine version does: a) a nice ring to it, and b) by its language, conveyance of the concept that you can take on something that is a real stiff challenge, and yet a real chance you will succeed. Incidentally, I didn't here the Vividly imagine thing at a $200 a head motivational seminar run by a guru. I heard it first nearly 40 years ago in an internal training course on project management run by a government department. I've seen it quoted many times since. It has worked for me. 60.230.217.174 (talk) 15:44, 4 September 2013 (UTC)

• There is actually an important and non-mystical question embedded in here somewhere. I form an intention to move my arm, and presto, my arm moves. How does that come about? The connection between intention and action is so consistent that it is difficult to grasp until people encounter cases where it breaks down, as in sleep paralysis. Looie496 (talk) 18:13, 2 September 2013 (UTC)

It tests where people are asked to decide at some random point to do something and then do it quickly it seems it is more like the decision is made and committed before we are aware of thinking about making any decision. Neuroscience of free will discusses this. Dmcq (talk) 18:52, 2 September 2013 (UTC)

Thank you for all the responses! I feel compelled to clarify what I mean by "power of intention." I haven't read any of Dyer's material, but I'm familiar with it; I've studied spiritual psychology, which attempts to bring soul back to the study of the psyche. Regardless of how 'unscientific' it is from the standpoint of hard science, spiritual experience is real, albeit in a different sense from 'physical reality.' Is it really so far-fetched to imagine that intention may be a type of brain circuitry that functions to set the stage for detecting and selecting sensory input that is relevant to the objective of the intention -- thereby making it more likely that the objective can be achieved? That's the sort of connection I'm curious about. Agiftagain (talk) 22:47, 2 September 2013 (UTC)

The idea of starting a study to attempt to "bring the soul back into psychology" is a classical pseudo-scientific enterprise. Science doesn't work by pre-supposing the answer and then striving to find evidence to back it up. Doing that leads to horrific systemic bias where you'll tend to push aside or ignore evidence that's contrary to you initial supposition. This is religion or pseudoscience or quackery of one kind or another. SteveBaker (talk) 00:58, 3 September 2013 (UTC)

And another clarification: The practice of setting conscious intentions (similar to creative visualization) is part of the puzzle. But unconscious intentions -- the mental soup that swishes wildly and makes most of us wish we could tame it -- are also part of the puzzle. It seems to me that the type of brain circuitry is the same for both conscious and unconscious intention. Practices (such as creative visualization) aimed at harnessing the 'power of intention' are a way of rewiring the circuitry. If I have a conscious intention to do A (something desirable) but my existing circuitry contains unconscious intentions to do B (bad habits, for instance), then practicing the conscious intention may strengthen the neural connections for A and weaken the ones for B. This way of conceptualizing 'intention' and its 'power' begs for a strong connection between this elusive concept and modern neuroscience. No? Agiftagain (talk) 23:08, 2 September 2013 (UTC)

here is a reference that might be relevant. Vespine (talk) 23:45, 2 September 2013 (UTC)

It's a grey area, for sure. But sportsmen and women, encouraged by sports scientists, do what they call "psyching themselves up" before an event, which is no more than "Vividly Imagining, Ardently Desiring, Sincerely Believing and Enthusiastically Acting Upon" their goal. They must feel this gives them some advantage over not doing this. -- Jack of Oz ^{[pleasantries]} 00:02, 3 September 2013 (UTC)

There are all sorts of tricks for improving concentration and removing distractions that may well help the person to perform better - and we know that effects like placebo's in medicine depend on the patient believing that the placebo will work. However, it's a gigantic (and unwarranted, unsupported) leap to say that merely wanting something badly enough is enough to make it happen and that if you hope hard enough that some paranormal mechanism would step in and make it happen. People desperately want things all the time (more money, a fast car, whatever) and most of them fail. Obviously, once in a while someone will succeed - but that's either a matter of chance or because (like those atheletes) they did a lot of actual work to make it happen alongside the "hope" part of it. The hope and the wanting is what keeps you working, training, whatever when distractions come by. SteveBaker (talk) 00:58, 3 September 2013 (UTC)

Yes. Preparation is key. Branch Rickey used to say, "Luck is residue of Design". Working harder will not guarantee victory - nothing can do that, short of fixing the contest - but it improves your chances of winning. And part of that preparation is psychological. Positive thinking cannot guarantee defeat of a disease, but it can improve your odds. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:11, 3 September 2013 (UTC)

Actually, no - at least not in the case of cancer patients. SteveBaker (talk) 17:15, 3 September 2013 (UTC)

Name for the medical trauma caused by having the skin flayed

Trolling
The following discussion has been closed. Please do not modify it.
I was wondering what the proper term for the medical trauma of not having skin due to flaying would be, Hypatia's Syndrome? It would be survivable if only some of the skin was flayed. I am going to reference this condition on the page for circumcision and female genital cutting, unless adding information on a related condition would somehow constitute soap boxing. CensoredScribe (talk) 03:04, 2 September 2013 (UTC) How, pray tell, is circumcision related to flaying? --Jayron32 03:21, 2 September 2013 (UTC) Maybe if there's no scalpel handy, and they have to resort to a bullwhip. ←Baseball Bugs What's up, Doc? carrots→ 08:40, 2 September 2013 (UTC) Well the term for the condition of not having skin by definition would apply to any place where the skin has been removed. What's the last part of the word foreskin, skin; how many skins does one have, one. Also bugs you seem to be confusing flaying with flagellation; though you should actually be proud of not having an encyclopedic knowledge of torture, as it is far less creepy than having one and trying to explain it's to reverse the damage. — Preceding unsigned comment added by CensoredScribe (talk • contribs) 15:03, 2 September 2013 (UTC) Maybe you could tell us exactly what point you're trying to make with your original question. And speaking of confusing things, there is a world of difference between typical male circumcision and clitoral removal. ←Baseball Bugs What's up, Doc? carrots→ 15:36, 2 September 2013 (UTC) No one has answered my question yet as to the proper name of the medical condition of not having skin due to removal by a sharp object; be that object scalpel, sea shell or anything else. It's not dermabrasion, as that removes scars, so what is it called? Also Baseball Bugs, do you mean to say that technically speaking that only removing the clitoral hood should not be considered female genital mutilation? Than there should there not be an article for female circumcision to differentiate it from female genital mutilation where in the entire clitoris is removed? CensoredScribe (talk) 17:23, 2 September 2013 (UTC) It's called "surgery". And if you don't understand the practical difference and effect of the two female surgeries you're referring to, you might want to take up another field of study. ←Baseball Bugs What's up, Doc? carrots→ 21:25, 2 September 2013 (UTC) Avulsion injury? BbBrock (talk) 21:21, 2 September 2013 (UTC)

hunting, foraging and the grandmother hypothesis

The menopause article’s description of the grandmother hypothesis says Some evidence suggests that hunters contribute less than half the total food budget of most hunter-gatherer societies, and often much less than half, so that foraging grandmothers can contribute substantially to the survival of grandchildren at times when mothers and fathers are unable to gather enough food for all of their children. (This information is not repeated in the full grandmother hypothesis article.) What I don’t understand is why a society on the edge of survival would continue to hunt if hunting made such a small contribution. You’d expect groups that had all adults forage would bring in more food and have a survival advantage, which has nothing to do whether the foragers were grandmothers or other people. Please clarify how this argument works? Thanks. 184.147.119.141 (talk) 04:02, 2 September 2013 (UTC)

I would suspect that it's not a matter of having enough food, but having enough variety of food. Hunting/fishing oftentimes provides the necessary fats and proteins that are difficult to find by simply gathering wild edibles or when certain wild edibles are out of season. Also, in many such societies, hunting has a cultural component as well. A boy's first hunt can be his initiation into manhood and skills learned while stalking and taking game translate into skills needed for warfare and defense of the group.--William Thweatt ^TalkContribs 05:36, 2 September 2013 (UTC)

My guess is that there's an upper limit on the amount of food that can be obtained by foraging. Once you've cleaned out an area of roots and berries, it doesn't matter how many people are searching. Hunting adds an extra source of food, which due to its higher calorie density, can be brought in from larger distances. I don't believe that primitive societies paid much attention to the concept of a healthy, varied diet, but survived on whatever was available; and hunting-related cultural activities would only have evolved if the underlying practice was of benefit to the community. However, both William and I are speculating without any references to back us up. Rojomoke (talk) 06:47, 2 September 2013 (UTC)

Thanks William Thweatt and Rojomoke. Does this mean, then, that you think the mention of hunting really doesn’t play a part in the grandmother hypothesis (the sentence I quoted says grandmothers increase the amount of food in total), but you seem to think they really couldn’t add much. Perhaps I should delete it from the article? It’s not sourced in the article. 184.147.119.141 (talk) 13:52, 2 September 2013 (UTC)

There is a hypothesis in Evolutionary psychology that male hunters are gambling for status. The average payoff for hunting activities is low, but the lucky ones who bag a large kill will gain reproductive advantage with females. Something grandmothers aren't seeking. --Digrpat (talk) 13:11, 2 September 2013 (UTC)

Thanks Digrpat. I understand there are other pressures for continuing to hunt. Perhaps the sentence needs to go? The argument is not so much about hunting but about having adults bringing in food solely, rather than both bringing in food and increasing the number of mouths to feed (as reproducing adults do)? 184.147.119.141 (talk) 13:52, 2 September 2013 (UTC)

Yea, I'd say it should go. What does it have to do with menopause, anyway ? But I agree that calories alone are not enough to keep people alive. Pretty much everything we crave and get way too much of now was scarce then, like protein, fat, cholesterol, salt, and sugar. Sugar is the only one of those you are more likely to find in fruit. You can get protein from beans and nuts, and a bit from grain, but you get a lot more from an animal. Fats you can get only in small quantities from most plant sources, with a few exceptions like avocados and macadamia nuts. I'm not sure if any plant source provides cholesterol. For salt you would need something like seaweed, which wasn't an option if they didn't live near the sea. So, while vegetarians today can have a healthy diet, this is only because we can get produce from around the world, allowing us to fill in all the gaps in a vegetarian diet. StuRat (talk) 08:32, 3 September 2013 (UTC)

Why do we get dizzy when we rotate rapidly?

WHY DOES DIZZINESS OCCUR WHEN WE ROTATE OURSELVES? — Preceding unsigned comment added by SREELEKSHMI SREE (talk • contribs) 14:14, 2 September 2013 (UTC)

(I added a title to this question) SteveBaker (talk) 14:27, 2 September 2013 (UTC)

The short answer is probably that dizziness is due to a mismatch between our vestibular, somatosensory and visual systems. In particular, our vestibular (balance) system hasn't evolved to handle rapid rotation well, and tends to give confusing results. This is apparent when you stop rotating, as you then get a distinct sensation of rotating in the opposite direction. As our article on the vestibular system explains, the balance organs work by detecting motion of fluid in three 'canals' in each of the two inner ears. Rapid rotation will cause the fluid to rotate in unison with the canals - and when the rotation stops, the fluid continues to rotate. AndyTheGrump (talk) 14:40, 2 September 2013 (UTC)

This explains the causes: http://en.wikipedia.org/wiki/Dizziness#Mechanism 217.158.236.14 (talk) 14:42, 2 September 2013 (UTC)

The section you have linked says nothing about dizziness caused by rotation. AndyTheGrump (talk) 14:47, 2 September 2013 (UTC)

Physiologic vertigo, you mean? There is a bit about it in equilibrioception, but not much. Illusions of self-motion might be related...Ssscienccce (talk) 17:13, 2 September 2013 (UTC)

My guess is that turning the head briefly leaves the vestibular fluid largely stationary as the Ampullary cupula is turned, but doing so for a long period allows friction to bring the fluid up to speed. When it stops, the fluid then continues moving for some time until friction finally brings it to rest. My prediction, therefore, is that Doppler measurement of the fluid in the ear of a just-stopped person will observe physical motion within it until their dizziness ceases. I found the article I linked in a web search because it says the same thing (minus the proposed experiment), but it isn't sourced. I didn't see quite the experiment I wanted in NCBI, but there was somewhat similar work and it might turn up with a more careful search. Wnt (talk) 17:22, 2 September 2013 (UTC)

Semicircular canal seems to decribe it: "The bending of these cilia alters an electric signal that is transmitted to the brain. Within approximately 25–30 seconds of constant motion, the endolymph catches up to the movement of the duct and the cupula is no longer affected, stopping the sensation of acceleration." Ssscienccce (talk) 17:29, 2 September 2013 (UTC)

• Because distant stars are the inertial frame of reference and such spinning puts one at odds with the entire universe. μηδείς (talk) 02:27, 4 September 2013 (UTC)

Comparing antimuscarinic effects of chlorpromazine and trihexyphenidyl.

I am wondering if there is anywhere in the literature comparison between anticholinergic effects of those two drugs. The question has practical significance. If the anticholinergic action of chlorpromazine is sufficiently strong, "side effect medications" like trihexyphenidyl should not be used on the same person, correct?

Thanks, - Alex174.52.14.15 (talk) 22:08, 2 September 2013 (UTC)

This seems like an odd question. Trihexyphenidyl is used entirely because of its antimuscarinic effects, so if chlorpromazine had such strong anticholinergic effects by itself, there would be no need for a drug like trihexyphenidyl. Anyway, chlorpromazine (aka Thorazine) is very rarely used nowadays, so it is probably a moot point for practical purposes. Looie496 (talk) 01:58, 3 September 2013 (UTC)

Rarely used eh? Someone should tell our local Government operated nut house. One of their customers escaped recently, and they notified the police. The cops brought back to them a chap they found in a gutter somewhere, but nobody realised it was the wrong chap. The shrinks gave him a good dose of chlorpromazine. Then he left. They then had to call the cops again because it scrambles the brain and induces diabetes. Cops couldn't find him. Now there's two nutters out loose and at risk. 58.170.175.173 (talk) 02:21, 3 September 2013 (UTC)

The question does make sense. First the chlorpromazine is still used in certain practices especially where cost cutting is an issue. Secondly, although both are anticholinergic there is a chance that the anticholinergic effect of chlorpromazine is much too weak as compared with trihexyphenidyl and thus the latter must be used to counteract the antidopaminergic effects of Thorazine. Of course trihexyphenidyl is not the only medication that can be used for this purpose but I am particularly interested in the latter.

- Alex174.52.14.15 (talk) 03:32, 3 September 2013 (UTC)

Gravity affects Time

Is anyone checking gravity affects on reaction rates? Seems to me gravity affects the rate at which the clocks work, not Time itself. — Preceding unsigned comment added by 202.173.169.3 (talk) 23:53, 2 September 2013 (UTC)

No - gravity most certainly affects "time itself" - you can see the effect in atomic clocks (which measure the speed that atoms do their thing), and since human brains are made of atoms, our perception of time (and our reaction times and so forth) is indeed affected by gravity. SteveBaker (talk) 00:14, 3 September 2013 (UTC)

But isn't gravity affecting rate at which atoms decay, not TIME itself but the instruments used, the clocks. And yes our own chemistry. — Preceding unsigned comment added by 202.173.169.3 (talk) 00:38, 3 September 2013 (UTC)

How do you know that 'TIME itself' exists except by measuring it using instruments? AndyTheGrump (talk) 02:02, 3 September 2013 (UTC)

If you measure your reaction with the clock at the same gravitational potential you should get consistent results. If you try to measure with extreme accuracy then you will have to consider this. But even for the sun the gravitational time dilation will not be much, only about 1 part in 100,000,000. Graeme Bartlett (talk) 08:39, 3 September 2013 (UTC)

Time dilation, from both speed (in special relativity) and gravity (in general relativity) affects everything, not just clocks. This is a common misunderstanding. The clock does not run slower due to some bizarre relativistic effect that only impacts clocks. Or, you could think of everything as a clock. Your brain trying to count the seconds, will run slower. The chemical reaction proceeding at a certain rate, will run slower. So you could declare that only clocks run slower, but everything is a clock :) Someguy1221 (talk) 10:10, 3 September 2013 (UTC)

Yep, exactly. If you do the classic thing of climbing into a rocketship and accelerating up to somewhere close to the speed of light, the person inside the rocket would look at their wristwatch and see nothing at all surprising. Despite (let's say) time running 100 times faster than it does back on Earth, the inside of the spacecraft, the clocks and everything else would seem entirely normal to anyone inside the ship.

The whole "relativity" thing is based on the idea that when two objects are moving apart (the rocketship and the earth) at a uniform speed, there is no concievable experiment that will tell you which one is "moving" and which one is "staying still"...because there is no absolute frame of reference to measure against. It's not that clocks behave strangely in your spaceship and "normally" on earth - it's that from your perspective, time outside of your spacecraft is running at a different rate from your time.

Gravitational time dilation is caused by a different thing - but the net result is exactly the same kind of time dilation. In this case, you can't tell whether you're in a gravitational field or whether you're accelerating - no experiment can tell the difference between those two situations either.

So the rate at which atoms decay, the speed at which a pendulum swings or a spring unwinds, the time it takes a beam of laser light to bounce back and forth between two mirrors - or the amount of time it takes for an influx of sodium ions to cause the polarity of the plasma membrane in your brain cell to reverse...all of those things are going to seem to happen at an accelerated rate to an outside observer. To you, in your spacecraft, in some gravitational field - all of those things are in perfect synchrony. It most definitely is time itself that's being distorted. It's not just some process relating to atoms because it affects photons and everything else too.

This all comes about because the speed of light is exactly the same for all observers - and for that to be true, both time and distances have to be distorted in order for two different observers to measure the time to be the same, no matter how they are moving or what gravitational field they are in. SteveBaker (talk) 16:50, 3 September 2013 (UTC)

Gravitational time dilation is really not that difficult to understand. In fact it is just a form of glorified Doppler effect and I much prefer the term "gravitational Doppler shift" to describe it. To understand how it works, just remember that by the principle of equivalence gravity is indistinguishable from being inside an accelerated frame of reference - say a rocket. Now imagine yourself at the top end of a rocket. If somebody at the bottom of the rocket sends you a light signal, it will take it some time to reach you. During that time you will be accelerating away from the light source creating a minute relative motion between you and the source. There will be a miniscule Doppler effect associated with that relative motion. There you go, that is the gravitational Doppler shift AKA gravitational time dilation. By the way, if you accelerate fast enough, that light signal might never catch up with you, creating an event horizon. Dauto (talk) 21:28, 3 September 2013 (UTC)

For some reason that made no sense to me in college, but it did just now. Thanks, Dauto! Someguy1221 (talk) 23:14, 3 September 2013 (UTC)

September 3

Power Plant Efficiency

Consider a power plant running on petroleum. The fuel has a certain amount of chemical energy and it produces a certain amount of electrical energy. How would I find an estimate for its efficiency? (It doesn't have to be very accurate, I just want to compare it to the efficiency of a car's engine... which I also haven't estimated yet. All I've got so far is the thermodynamic efficiency based on temperature of the furnace versus ambient temperature and I don't think that is going to be a good estimate.) Thank you. RJFJR (talk) 00:32, 3 September 2013 (UTC)

Typical diesel engine generator sets run at about 42 to 45% overall thermodynamic efficiency. You can verify this by going to manufacturer's or dealer's websites (eg Caterpillar) and downloading data sheets for any model of your choice. This applies over the range for small portable gensets to huge power stations. Coal fired and oil fired steam turbine power stations run at somewhat less efficiency, especially older power stations, but the fuel (coal or heavy bunker oil) is much cheaper.

Typical gasoline car engines run at around 22 to 27% thermodynamic efficiency at best throttle setting. Diesel engines in power generation service are considerably more efficient than car engines because 1) they operate at higher compression ratios (typically 15:1 vs 9:1), they do not thottle the intake air, and because they operate at a constant RPM, the design can be optimised for that RPM. Also, turbo charging, which can only be applied to a limitted extent set by detonation on a gasoline engine, can be applied to a diesel engine to a much larger degree limitted only by mechanical and thermal stresses. By recovering heat energy from the exhaust and putting it to use, turbocharging raises thermodynamic efficiency as well as power output. A minor factor: The combustion temperatures in a gasoline engine are higher, especially at part throttle, because the combustion is stochiometric. A diesel engine operates with excess air. The higher combustion temperatures in gasoline engines mean a higher proportion of heat lost to the coolant, lowering efficiency.

On light loads, the efficiency of a diesel engine falls off not as bad as it does for a gasoline engine (because the intake air is not throttled, and because combustion tempertures go down).

However, if a large gasoline engine is designed to run only at a specific optimum RPM, no expense is spared, and is operated by trained personell, its efficiency can approach that of a diesel engine. For example Word War 2 vintage Merlin and Pratt & Witney aircraft engines.

58.170.175.173 (talk) 01:41, 3 September 2013 (UTC)

45% efficiency for a diesel generator sounds high, but are you only looking as far as the output terminals of the generator, and neglecting losses in transformers and transmission and distribution? Edison (talk) 02:16, 3 September 2013 (UTC)

Correct, the figure applies only to the extent of the generator terminals. Losses in transmission and distribution can be any sort of value and I assumed the OP didn't want it included. For example, a genset in use at a mine site will have only simple local distribution, and distribution losses may be only 1% or less. But a municipal power station feeding a state-wide grid will encounter transmission and dustribution losses very much greater. For this reason, electric automobiles recharged from the electricity mains are rarely a global carbon advantage, even though their internal efficiency may be 90% or better, or 80% if you include the losses in the charger. For the figure for gasoline engines I gave, it applies to to mechnical output at the flywheel, and does not include losses in the gearbox and differential. 58.170.175.173 (talk) 02:29, 3 September 2013 (UTC)

Yes, I always cringe when I hear somebody claim that electric cars are pollution free. It's unlikely they have a solar or wind source for the electricity, more likely they are burning coal, with all the pollution that creates. It's similar to how people who buy a baked chicken don't seem to think they are responsible for that animal's death. StuRat (talk) 08:19, 3 September 2013 (UTC)

And even if they do have photovoltaic power, over the lifetime of the car and the solar panels, you should include the energy used to make the solar panels, which is quite substantial, and generally coming from coal fired power stations. Those solar power greenie freaks definitely belong to the same club as your baked chicken friends.1.122.244.100 (talk) 08:34, 3 September 2013 (UTC)

That depends very much on where they are driving (or at least, charging). If they are driving in France, then virtually none is from coal. (About 75% is from nuclear – and I don't think it's useful to repeat the debate about nuclear here – and about half the remainder comes from hydroelectric and other renewables.) If they are driving in Canada, then about 13% is from coal (all fossil fuels together make up about 20% of the electricity mix); nearly two thirds (63%) comes from hydroelectricity. If they are driving in Iceland, then nothing comes from coal, and 99.9% comes from a completely renewable mix of hydroelectric and geothermal power. Not every country in the world is the United States or China. And if one can persuade one's government to be responsible in its choices for new and replacement power plant construction, the electric vehicle can become 'greener' over time—something that can't happen with a fossil-fuel vehicle. TenOfAllTrades(talk) 13:22, 3 September 2013 (UTC)

Regarding hydropower, few countries are lucky enough to use this as a major source. Regarding nuclear, leaving aside the debate about accident safety and waste storage risks, which is largely political/emotional, the problem is economics. For instance, various Australian State power authorities, especially NSW and WA, looked seriously into nuclear power in the 1960's and 1970's. The trouble is, when amortising the costs over the life of the power station and waste management facilities, you need a power station so huge, one power station generates more power than the entire market, or it just isn't economic. The West Australian power authority got creative, and looked at buying essentially a US submarine engine room - that was small enough, albiet not able in standard form to meet civilian land locked radiation leakage standards, but they still coudn't make it pay. So no Australian state went ahead with it. Countries like France, USA, and Japan are fortunate in having a population and thus power market much larger and able to make it pay. In the case of the USA, Britain, and France, making bomb fuel as a "sideline" helps justify the nuclear industry. 1.122.244.100 (talk) 15:59, 3 September 2013 (UTC)

That's a false claim. "Making it pay" depends entirely on how you tax the waste products. The nuclear industry is expected to include the cost of total, 100% cleanup of all of its operating waste and decommissioning costs into the price of the electricity. If the coal/oil/gas powered power plants were required to do the exact same thing (implying capturing 100% of the CO2 and scrubbing out the acid-rain-causing materials - and also returning slag heaps, open-cast mines, water retention dams and flattened mountains to usable land, preventing damage to water tables and earthquakes from fracking and so forth) then they'd be completely priced out of the market and nuclear would look cheap by comparison.

If we had invented nuclear before coal powered plants, there is no way that coal would be able to enter the electricity market. It's purely an historical accident that we allow one industry to do more or less what the heck they like while the other has to be regulated out the wazoo.

SteveBaker (talk) 16:28, 3 September 2013 (UTC)

Indeed, and then you also have the fine dust emissions from coal fired powerstations and from cars with combustion engines which kill large numbers of people. So, while one worries about big nuclear accidents, the largest recent one the Fukushima disaster in which zero people died, worldwide hundreds of thousands of people die prematurely each year from lung diseases made worse by air polution. Count Iblis (talk) 01:19, 4 September 2013 (UTC)

Quibble: If you are going to count premature deaths caused by air pollution in the case of coal, then you also need to count premature deaths due to radiation exposure in the case of nuclear plants. Since many of the emergency workers were exposed to high levels of radiation in Fukushima, presumably some will die sooner than they otherwise would have. I do agree that coal pollution kills more people than nuclear plant emissions, though. StuRat (talk) 07:35, 4 September 2013 (UTC)

Chernobyl caused 31 deaths immediately and added a 2% to risk of cancer for a few thousand more. 10 children died from thyroid cancer and 700 more were affected by it - perhaps 4,000 people will die prematurely (but mostly not VERY prematurely) because of the fallout.

But that's comparable to the 30 deaths per year amongst coal miners in the USA and 4,000 new cases of "black lung" each year in coal mine workers - a quarter of whom will die prematurely because of it. Figures on the number of people who die from shipping the coal and at the power plant itself are not available - but they aren't zero. People outside of the immediate workforce have also died from landslides in the spoil tips (Aberfan disaster for example - where the children of an entire village were engulfed and died) and from waste water dams failing (The Buffalo Creek Flood, for example - where 125 civilians died).

The huge difference is that the mine-workers and people living near to coal mines suffer this death toll every single year - and we most certainly don't have accidents on the scale of Chernobyl even once per decade - so far we've really only had two within first 50 years of the industry.

Worse still, comparing US mining death rates (US coal mines are probably the safest in the world) with a Russian nuclear accident isn't fair. The Chinese death toll due to below-ground mining accidents alone is over 6,000 per year...and the Fukushima accident has yet to kill a single person.

But in any case, the world has more than enough people - but we only have just one atmosphere. SteveBaker (talk) 14:24, 4 September 2013 (UTC)

Scanimation

I'd like to make an article on this.

I don't think it's the same as Scanimate, but maybe is similar to Parallax barrier. It may have another name. Does this article exist already? Are there enough sources? Thoughts and suggestions would be most welcome. Thanks, Anna Frodesiak (talk) 02:42, 3 September 2013 (UTC)

Definitely not Scanimate. I think it is only similar to Parallax barrier in that only certain parts of the horizontal row of the image are seen (but sequenced in time rather than for one or the other eye). This trick is conventional animation with parts of successive frames interlaced and then selectively displayed by the sliding grid-card. Closer maybe to Lenticular printing, except using a screen to control which part is seen rather than diffeent angles around a lens (and relying on visual processing to "fill in the blanks" where the screen is blocking out the image entirely). DMacks (talk) 02:58, 3 September 2013 (UTC)

Your brain is at least 4 times bigger than mine. :) Okay, Lenticular printing is maybe a see also item. So, the next thing is about whether or not it can stand on it's own two feet as an article, or should be a section somewhere. And the other thing is about sufficient sources. Anything non-spammy is about the video scanimate. Thoughts? Anna Frodesiak (talk) 03:12, 3 September 2013 (UTC)

I would call it a Moiré_pattern animation. /slit animation/ also gets several relevant hits on Google, and that search also led me to Zoetrope. So I guess it's a Moiré Zoetrope :) SemanticMantis (talk) 03:25, 3 September 2013 (UTC)

It's not Moire because that implies that the lines in the image and the foreground object are not parallel - and that's not the case here. (And it's definitely nothing to do with Scanimate). It's really just a flattened out Zoetrope. The video says that it's an "optical illusion" - but it isn't that either. It's nothing more than a three frame movie. The images contain three frames of animation (the least you can get away with to generate unambiguous rotation directions) - with the three frames interleaved. The overlaid screen just selects one of the three frames to view while occluding the other two. Nothing particularly special about it. SteveBaker (talk) 16:09, 3 September 2013 (UTC)

US Patent 7151541 is the mother ship, associated with several published books/toys using it (see patents citing it, and work up the tree; there you also have the inventor's name if this item is notable). DMacks (talk) 03:36, 3 September 2013 (UTC)

I think this deserves a small section at Moiré_pattern but not a separate article. Does that sound right? Anna Frodesiak (talk) 05:14, 3 September 2013 (UTC)

For what it's worth, that sounds good to me. It's a very interesting trick, but probably doesn't warrant a whole article. You could ref the patent, and perhaps one of the books that uses it. SemanticMantis (talk) 14:47, 3 September 2013 (UTC)

I disagree. This is nothing whatever to do with Morie fringes. That implies that the two sets of lines (in the image and the overlay sheet) are at some angle to one-another - and they aren't (or at least don't have to be) for this effect to work. SteveBaker (talk) 16:09, 3 September 2013 (UTC)

It has the similarity of using a striped screen moved across another image, with the effect of creating an animation, wherein the perceived image seems to move. In the classic Moiré pattern, the underlying image is usually a regular geometric pattern. This case is not the same as the classic demonstration, in that the underlying image need not be regular or repeating. So, while it not be a Moiré pattern under some (nonexistent) strict definition, that is the closest place. There may be other choices, but nobody has yet made a case for a better place to include information on this technique. SemanticMantis (talk) 16:17, 3 September 2013 (UTC)

Zoetrope already has information about "linear zoetropes" (and the Masstransiscope!) - which are precisely what this is. Putting the information into the Moire article confuses and muddies what that is all about (which is interference patterns). The whole idea of an encyclopedia isn't to just wedge the information in there someplace to avoid "losing" it - but to carefully consider where it belongs. SteveBaker (talk) 18:19, 3 September 2013 (UTC)

I suppose this thing could be added to Zoetrope. But the video linked by the OP is not a linear Zoetrope. In a Zoetrope, each "frame" of the image is viewable on its own, as a complete image. In the OP's video (and the patent, etc), the screen is necessary to fill in the gaps. That is, the "image" underneath doesn't make any sense without the screen. As far as I can tell, that is not the way the masstransiscope works either. It looks to me that in the masstransiscope, each frame is a full image, and the slits just control which image you see at which time. Maybe we do need a new article after all! SemanticMantis (talk) 18:47, 3 September 2013 (UTC)

And here's [3] a picture of the Masstransicope frames. As you can see, they don't require a screen to complete (and also mask) the image, as our current device does. SemanticMantis (talk) 18:53, 3 September 2013 (UTC)

I suppose you have a point about the multiple slits...but it's still nothing remotely to do with Moire fringes. SteveBaker (talk) 19:01, 3 September 2013 (UTC)

Nothing remotely? Have a look at Shape_moiré :) I see no substantive difference between the animations there, and the video that the OP links. Contrary to what you seem to think, moiré patterns aren't required to be made from parallel lines, or even be geometrically regular. It is a generally-used term to describe how the combination of two different layers can occlude and interfere, and give rise to a new pattern that was not present in either layer alone. But, thanks for this discussion, it forced me to dig deeper into WP, and learn a few new things (they apparently use this type of "shape" moiré in marine navigation, to make arrows that change direction, and always point toward the obstacle (our ref at Moiré pattern is sadly broken))! And there's no reason we can't have links to zoetrope and other related concepts. SemanticMantis (talk) 19:44, 3 September 2013 (UTC)

Yep! Nothing remotely. That article you linked to is indeed related to moire fringing - it's resampling the data at a different frequency...not at all the same thing as the animation technique referred to here - even though it appears superficially similar. Mathematically, it's not remotely the same...I'm sorry if you don't understand the distinction - but it's truly not the same. SteveBaker (talk) 20:29, 3 September 2013 (UTC)

You really think the animations at shape moiré and the what the OP linked are completely different? The video the OP links could also be described as sampling at different spatial frequencies, with the phase controlled by position of the screen. Both there, and at shape moiré, we have a striped screen moved across an image. In both cases, the filtering out of some frequencies allows a different image to be seen, that is partially made up of bands from the screen, and partially made up of the underlying image. When the screen is moved, the combined image appears to move, due to changes in phase. For me, that is more than enough similarity to consider them the same, for the purposes of WP classification. The only difference I can see is that, in shape moiré, the underlying image is periodic in one direction. So, if your argument is that, to be a "true" moiré pattern, the base layer has to be periodic in one direction, then I can concede that difference, even if I don't agree with the definition. I As for the rest of the math, you are aware that all the math on our articles is ad-hoc, and developed to illustrate how specific examples work out, right? There is no canonical set of equations that can in general model any given moiré pattern. The whole notion of moiré patterns is a bit subjective, so I suppose it's a bit pointless to argue about what does and doesn't qualify. Still, if you care to show us what you mean by "Mathematically, it's not remotely the same", I'll be all ears (er... eyes :) SemanticMantis (talk) 20:57, 3 September 2013 (UTC)

So what's the verdict? Shall I stub it and see how it develops? Anna Frodesiak (talk) 12:43, 4 September 2013 (UTC)

Your call. Thanks for the interesting post! I tried to explain my perspective as clearly as I could, and in my view, it's a sub-class of a wide variety of moiré patterns. It could go in a section at the main article, or as a stub, maybe moiré animation. I actually only skimmed the patent, maybe there's a better name there? Also, if you can find info on any of the books that use they patent, they may call it something specific like "magic screen" or something. If so, that would be a good redirect. I'm traveling for a few days, but I can work on it next week if you contact me on my talk page with the stub link. SemanticMantis (talk) 14:33, 4 September 2013 (UTC)

Teabags and Toothaches

Upfront: I do not have a toothache and am not looking for medical advice, just curious about a folk remedy that I can't seem to find a discussion of. I've seen/heard that if you put a tea bag in your mouth, over a tooth that is infected, that it will draw out the infection- I've heard a number of variations too: it has to be a black tea, needs to be warm and wet, needs to be dry, etc.. At any rate, no matter how much I look, I've never come across anyone debunking this claim, or even discussing it beyond the recommendation, most other common folk remedies are debated/discussed elsewhere. So, does this work and, if so, by what mechanism, and if not, why does it seem to get a free pass. (Note: I'm sleepy and wording poorly, I don't mean to suggest that I think it works because nobody debunked it- I doubt it would do anything but give you a foul taste in your mouth.)Phoenixia1177 (talk) 10:09, 3 September 2013 (UTC)

I would consider that "treatment" a Poultice - "used to treat abscess wounds, where a build-up of pus needs to be drawn out." Also, the caffeine may bring some pain relief. http://www.telegraph.co.uk/news/uknews/1360756/Why-a-cup-of-tea-can-ease-the-pain.html. I personally have never heard of this remedy. 196.214.78.114 (talk) 10:48, 3 September 2013 (UTC)

I'd suggest that one reason this hasn't been aggressively debunked is that, unlike many old wives tales, it's not that old. Many old wives have been around for longer than tea bags. HiLo48 (talk) 11:02, 3 September 2013 (UTC)

(JK) They'd be really really old. At least 110. Teabag#History (Lacks citations.) 196.214.78.114 (talk) 12:29, 3 September 2013 (UTC)

Although not in popular use in the UK until the 1970s (purely my personal recollection but I'm fairly certain). Alansplodge (talk) 12:43, 3 September 2013 (UTC)

FWIW I remember Tetley teabags being available in the UK in the mid-1960s. According to this page they sold 5000 tonnes of them in 1968. AndrewWTaylor (talk) 14:36, 3 September 2013 (UTC)

Well I stand a little corrected, however "In the early 1960s, tea bags made up less than 3 per cent of the British market, but this has been growing steadily ever since. By 2007 tea bags made up a phenomenal 96 per cent of the British market..." [4] This page says that we use 130,000 tons of tea per annum, so assuming a similar consumtion in the 1960s, 5,000 tons would be nearly 4%. Alansplodge (talk) 20:14, 3 September 2013 (UTC)

There could be other interpretations of the story or your question, but I'm taking the brass-tacks question here to be: does Camellia sinensis interfere with damage to teeth by Streptococcus mutans? Looking these two things up online, it looks like this is a question pursued by good students around the world, and classes have actually done some good work with it, summarizing the literature and testing on their own. [5] [6] (though the notion of schoolkids growing up isolates of decay-causing bacteria is slightly worrisome...) The latter experiment makes it clear that ordinary mouthwash is generally more potent against bacteria in vitro, but that first student wiki puts forward an interesting hypothesis that tea catechins could have another effect in toxin secretion. Searching NCBI turns up a number of similar studies from throughout the Middle East. [7] My feeling is that the practice is based in science, but the effectiveness of this specific procedure, or little variations in it, has not really been demonstrated. Wnt (talk) 13:54, 3 September 2013 (UTC)

The reason that these things are not always well debunked (or even shown to be true) is that it takes no more than 20 seconds for someone to come up with a semi-plausible idea like this. Let's say: "Soaking your feet in warm diet cherry coke every night before bedtime is a sure-fire cure for male pattern baldness"...that only took me 10 seconds to think up - and I could spam it to the world and a bunch of people would repeat it as truth...before you know it, it would be on The Dr. Oz Show. But it takes years of careful and expensive scientific study with hundreds of human test subjects to show whether it's true or not. It follows that most of these "old wives tales" will go forever untested.

Imagine a test for the teabag hypothesis. You'd need to take 100 people with toothache and have a third of them use the teabag, another third use placebo bag filled with inert, fake, tea-leaves and another third do nothing. Wait for a week and have them all examined for signs of infection. This is kinda unethical - that's 100 people who really should have seen a dentist who didn't. With all of the statistical work, the coming up with a really good placebo bag, double-blinding the experimenters, crunching the numbers, deciding whether there might be something in it - which might require some follow-up work, and publication - with more people duplicating your experiment to verify the results...the whole thing might easily cost a half million dollars to run just to debunk the myth.

So you cannot use the lack of a complete debunking as some kind of evidence that something fairly obscure like this is untrue.

NOTE: Neither this author nor the WikiMedia foundation either promote or endorse soaking your feet in warm diet soda of any kind - do so at your own risk! :-)

SteveBaker (talk) 15:51, 3 September 2013 (UTC)

The difference though is that folk remedies generally spread when they are found to be effective by a user. Of course, they can spread for wrong reasons - political salesmanship like for the King's evil (though some pricey meat wouldn't hurt there), mnemonic convenience like for the doctrine of signatures. They can also spread because they have some sensible science behind them... even though they don't actually work! But not infrequently they spread because they do work. The world is full of traditional medicines that actually contain useful compounds. It is useful in such instances to keep an open mind either way, neither saying yes nor no as a default. Even placebo is sometimes prescribed by physicians, so why discourage using something with a chance? Wnt (talk) 16:41, 3 September 2013 (UTC)

But most folk remedies don't work - and things like Homeopathy spread like wildfire despite that. Some folk remedies are really dangerous - such as Rasa shastra which purports to cure diseases with helpful metals like mercury and lead - that didn't stop it from becoming popular. Others that are growing in popularity in the US include gold and silver therapies - which can cause Chrysiasis and Argyria. All it takes is for some random idiot to read that silver has antimicrobial properties and to extrapolate from this true fact to the entirely unwarranted conclusion that consuming colloidal silver will cure what ails you - and you may soon find that your skin turns permenantly and irreversably purple. SteveBaker (talk) 18:14, 3 September 2013 (UTC)

The problem is in what "found to be effective" really means. With a single self-diagnosing patient, self-prescribing a preferred folk remedy, there's a whole bunch of problems. It's a condition where straight up placebo effect should be expected to be strong (often bolstered by a good bit of spurious argument from authority, whether from grandma, the internet, or a fringe publisher who mistakenly believes that sharks are immune to cancer). There's also the post hoc ergo propter hoc problem—a lot of symptoms targeted by home remedies will go away (or lessen, or be perceived to lessen) by themselves, purely by time or chance. It's an almost ideal incubator for random psychological reinforcement. TenOfAllTrades(talk) 20:34, 3 September 2013 (UTC)

Homeopathy and colloidal silver aren't folk remedies - they're well promoted modern scams with organized backing, and in the case of the former, formal legal authority to offer "diagnoses" and "medications" and "treatments" not allowed to the average wise-woman. Of course, I recognize that there are plenty of ideas from traditional medicines that are completely wrong, but it doesn't deserve credit for these. (Traditional medicine tends to be particularly good for purposes such as immediate pain relief where the user knows whether a clove or a beaver testicle helped his toothache or not a minute later; and particularly bad at long-term uses like for cancer treatment (I don't remember seeing a single traditional treatment for cancer that worked, and they actually missed treatments like yew bark that they had in their pharmacopoeias) Wnt (talk) 22:25, 3 September 2013 (UTC)

I picked those two examples precisely because they are popular enough to have been carefully tested, so we know for sure whether they are effective or not and can therefore discuss them rationally. Things that a very few people believe are not gonna get carefully examined (for the reasons I explained above) so it's hard to find examples of major screwups. But there is no particular reason to assume that an untested treatment from a modern scammer is any more or less effective than something from the proverbial "old wife". Without research, either one of them could be effective, ineffective, provoke a placebo reaction or could be downright dangerous.

The idea that sticking a clove against a painful tooth will make the pain go away might work well for one person but badly for another. It could have nasty side-effects - maybe the tooth falls out three months after treatment or the patient gets a fatal form of cancer ten years down the line because of it. How would anyone notice that the clove was the problem? Without using modern research methods, you have no idea what you're really doing to the patient - even if it seems to work every time. SteveBaker (talk) 13:33, 4 September 2013 (UTC)

OK - how about this as an example. 20 years ago, grapefruit was a "herbal remedy" for all sorts of maladies. It actually did seem to work - but modern science has since discovered that what's really going on is that this fruit interacts with all sorts of biochemical mechanisms and has truly horrendous drug-interaction effects - magnifying the potential of otherwise harmless doses of other chemicals to do serious damage. (See Grapefruit–drug interactions). If your grandma tells you that grapefruit is good for your allergies - and you happen to take it within an hour of taking some Benadryl...well, let's just say "Don't Do That!". SteveBaker (talk) 13:44, 4 September 2013 (UTC)

molecular mass and formula mass

I need 5 differences between molecular mass and formula mass .... can anyone help me (139.190.171.116 (talk) 13:08, 3 September 2013 (UTC))

You can read our article on molecular mass (which also discusses formula mass) if you do not feel like, or are confused by, the materials provided by your teacher in class or as assigned for you to read in your textbook. Your teacher is obviously asking something based on what you are learning in class, so it's best for you to use its resources to give the answer the teacher wants. DMacks (talk) 13:24, 3 September 2013 (UTC)

I don't see the mass of the empirical formula (which is, according to google, the definition of formula mass) being mentioned in that article... Ssscienccce (talk) 14:25, 3 September 2013 (UTC)

Is why I softened my statement to focus on whatever terminology and ideas the teacher/textbook used. Without knowing what facts and definitions were given, we're stuck saying "google it, here's what I found" or "our formula mass is a redirect to molecular mass and we don't have a distinct definition according to a reliable source". Neither of those would earn passing marks. If there is a difference according to IUPAC, please add it with cite to the article. If this is just a fuzzy or obsolete distinction, then maybe it's best we don't propagate it at all. FWIW, there are bunches of google hits that formula mass is actually what it means in lay language: sum of masses of atoms in the "formula" (either molecular or not explicitly empirical). DMacks (talk) 14:33, 3 September 2013 (UTC)

Good to know the vagueness of the term wasn't just in my head. ;-) IP seems to originate from Pakistan, maybe it has a more precise definition in the original language... Ssscienccce (talk) 15:17, 3 September 2013 (UTC)

help identify this bug

Hi, can you please tell me what is this creature? found dead in Haifa, Israel

unknown bug

Thanks --Golan's mom (talk) 13:15, 3 September 2013 (UTC)

Upon further examination, I have observed the creature to be a member of a species of insect which may be found in parts of Israel, including Haifa. ☯ Bonkers The Clown \(^_^)/ Nonsensical Babble ☯ 13:29, 3 September 2013 (UTC)

Intelligence tells me that it is a bug-shaped bug manufactured by the Israeli government. Capable of storing 3.72 terabytes of info. ☯ Bonkers The Clown \(^_^)/ Nonsensical Babble ☯ 13:29, 3 September 2013 (UTC)

Please refrain from posting jokes, especially before the question has a legitimate answer. Nimur (talk) 14:40, 3 September 2013 (UTC)

Dubious humor aside, my wild guess is it looks like some species of longhorn beetle, but even if that's right it leaves a large field of possibilities... Wnt (talk) 13:58, 3 September 2013 (UTC)

Because of complex politics, Wikipedia's articles about nature, wildlife, and ecology in the Levant are particularly fragmented. I watched passively as our article currently known as Biodiversity in Israel, the West Bank, and the Gaza Strip changed hands between Fauna of Palestine and Fauna of Israel multiple times over the last few years. Personally, I was too embroiled in the war in South Lebanon for me to divert any of my encyclopedic energy to the more noble pursuit of natural science, Everyone suffers when senseless conflict erodes our ability to share and categorize our knowledge freely. Anyway, that page links to a few online databases that might be helpful, but I'm unable to reach any of the servers linked - they may be inoperable, or simply very slow. Still, despite the fragmentary organization, there are dozens of Palestine and Israel "lists of fauna" categories and lists that you can peruse by following the category links on the bottom of that page, e.g. Category:Environment of Israel and Category:Environment of Palestine.

Before we jump to wild guessing about the specimen, we should aim for the kind of procedural study that a proper entomologist would use. Here's a guide to arthropod morphology from the American Museum of Natural History that points out the key features that we should focus on, to aid in classification and taxonomy identification. For example, the lack of a visible external ootheca almost categorically rules out any type of cockroach.

With luck, one of our better bug enthusiasts can help us out narrowing down the species. Nimur (talk) 15:07, 3 September 2013 (UTC)

I appreciate your request to refrain from jokes. Refraining from soapboxing is also good advice. --Onorem (talk) 15:14, 3 September 2013 (UTC)

Sorry. I am attempting to sincerely express that our encyclopedia coverage of this topic is actually degraded by the ongoing political conflict, and despite my intimate familiarity with the region and its biodiversity, I am not able to find great internet links about the insects of Haifa. Nimur (talk) 15:18, 3 September 2013 (UTC)

I went to the MNH site suitably chastened, to see what the professional guide would recommend... actually, it links to a group of articles like this which says first to look at the wings, which we can't see, then "Basically, you're eyeballing your specimens, looking at the differences and similarities. Sort your specimens according to shape, color, number of legs, and any other differences you can discover ... If you are able, for example, sort all the things that appear to be beetles. Next separate the long, narrow beetles from the round beetles. Then take a closer look at the long, narrow beetles and see characteristics that some share, like the same type of antennae or the shape of their wing covers." Which actually more or less matches the ad hoc thought process I'd used here, so now I don't feel so bad. Still a poor substitute for a taxonomic key. But looking one up I get [8] saying that there is no accepted taxonomic key - besides, with no way to properly examine either the wings or the genitals, our possibilities are limited. Wnt (talk) 16:34, 3 September 2013 (UTC)

Additionally, we can rule out true bugs by the mouthparts, and see that there are complete elytra. Together, those suggest a beetle, and the long antennae make longhorn beetle a pretty good pick. Still, it is worth mentioning that very few insects can be identified to species level via a single photo, even with a key and training. SemanticMantis (talk) 16:54, 3 September 2013 (UTC)

Thank you for pointing me in the right direction - before I could just tell Golan that it's a bug ... Looking up the longhorn beetle in the English Wikipedia as well as in the in the Hebrew Wikipeida I have arrived at this great site with pictures of Cerambycidae of Israel, see here to insects of Israel. Thank you! --Golan's mom (talk) 17:59, 3 September 2013 (UTC)

And if I would have to take a guess, I would say that the closest to what we found would be Niphona-picticornis --Golan's mom (talk) 18:12, 3 September 2013 (UTC)

semi permiable membrane

semi permeable membrane (talking in context to osmosis) dont allow solvent molecules to pass through it even if the spm has pores of bit larger size than it is of the solute particles.

The fact mentioned is 100% authentic just i need a satisfactory explanation — Preceding unsigned comment added by Shubhamagrawal1996 (talk • contribs) 15:25, 3 September 2013 (UTC)

There are many biochemical mechanisms that exist to help explain how flow against a concentration gradient is possible; this includes selective permeability and active transport. I wonder how "pore size" is being defined... if we were using molecular physics terminology, we could talk about the atomic radii at the periphery of the pores, and we could describe active transport as a selective mechanism to open and close the pores by converting chemical energy (from adenosine triphosphate, usually) into other forms of molecular potential energy. That energy can be used to apply an electrostatic potential to the periphery of the pore, essentially altering the collisional cross section of the pore in a specific way for each solute molecule. As a physicist, I would now say "the pore aperture is smaller than the solute particle cross-section" - but as a biologist, I can see an equally coherent justification for saying "the pore aperture did not change size, but it no longer permits the solute to pass through it." Nimur (talk) 15:59, 3 September 2013 (UTC)

Biochemical? My interpretation of the question was membranes used in reverse osmosis, like for desalination of seawater. Haven't find an answer though. Reading the question again, I see it says not allowing solvent molecules to pass, not sure if that is what he means, in that case nothing passes?Ssscienccce (talk) 22:55, 3 September 2013 (UTC)

Biology

When there is acidity, why the colour of urine become deep yellow?Is due to high level of urochrome? — Preceding unsigned comment added by Titunsam (talk • contribs) 17:26, 3 September 2013 (UTC)

I don't know the answer, but here are a couple related observations:

1) When I drink lots of water, my urine is clear, presumably because it is quite dilute. This would also tend to make it less acidic.

2) When I take lots of vitamin C (ascorbic acid), my urine is bright yellow. StuRat (talk) 07:26, 4 September 2013 (UTC)

Osmosis, diabetes mellitus, and osmosis

Pick the correct answer to the following question. Write a brief statement explaining why each choice of answers is correct or incorrect.

In diabetes mellitus, because of insufficient insulin production, glucose cannot enter cells. instead it accumulates in the blood plasma. which of the following statements would be true under these conditions?

A. The concentration of the plasma would decrease. B. the osmotic pressure of the plasma would remain the same. C. Water would move out of the tissues into the plasma. D. Tissue cells would swell. — Preceding unsigned comment added by 98.214.102.79 (talk) 17:46, 3 September 2013 (UTC)

Or E. Do you own homework. 82.21.7.184 (talk) 18:23, 3 September 2013 (UTC)

You may want to read the article Osmotic Pressure, as well as Tonicity. Knowledge of those concepts should be sufficient to answer at least B-C. I'm not quite sure how to answer A, as the phrase "concentration of the plasma" is vague and confusing. -- 205.175.124.72 (talk) 00:52, 4 September 2013 (UTC)

The speed of light versus the speed of sound. Which has more for the buck?

Years ago a did an experiment utilizing two multiple speed tape recorders. I read the entire front page of the local newspaper on one recorder, rewound it then replayed, put it on the fastest speed to re-record it. I repeated that process three times. Lo and behold the entire paper was a mere BEEP. That being said leads to the question if you could speed it up say a hundred times it might be possible to fit the entire library of congress into a mere beep? If the science is there/here maybe those beeps I've heard that certain astronomers are listening to,,, actually mean something? Origiman (talk) 21:12, 3 September 2013 (UTC)

Your experiment with tape recorders was employing Lossy compression. Many of the people involved with SETI have PHD's in information technology and related fields. Surely they examine their data with every known compression algorithm in mind.--Digrpat (talk) 22:35, 3 September 2013 (UTC)

Speaking of which, using quantum computing with superposition of states, how much information can you put into a single photon shot out into space? Wnt (talk) 23:03, 3 September 2013 (UTC)

You can store a lot of information in the momentum of the photon, the total amount depends on the distance between transmitter and receiver. This follows from the total number of available quantum satates in a volume V; for a single photon this is 2 V W/h^3, where W is the volume in momentum space, the factor 2 is the spin degree of freedom. To measure the photon momentum with an accuracy delta P requires the measurement apparatus to have a size of hbar/(2 Delta p), so the more information is stored in the photon momentum, the larger the detector needs to be to extract that information. And then we've not taken into account the noise that one has to average out. Count Iblis (talk) 23:27, 3 September 2013 (UTC)

I read that this is actually a problem for SETI, because an ideal compression algorithm renders data indistinguishable from white noise. If we assume that any sufficiently advanced civilization actually encrypts and compresses its communication, which is not a stretch, it makes it very unlikely that we'll even recognize the signal as "intelligent", let alone figure out what anything in the signal means. Vespine (talk) 23:34, 3 September 2013 (UTC)

That is in fact a real conundrum. A similar conundrum existed during the cold war: SIGINT, the interception of enemy signals, was a persistent topic of very advanced research. In many cases, the order to launch (or not launch) nuclear missiles was intentionally meant to appear as white noise, and transmitted at all times, because any other type of signal broadcast to the numerous submarines that were necessarily dispersed across the entire globe would clearly indicate the plan to strike (or equivalently, the absence of a command not to strike). I am still astonished that we survived so many decades without more accidental nuclear launches. The existence of these radio signals may seem like fringe-theory pseudoscience, until you build your own very-long-wavelength, extremely low frequency radio and hear the constant, droning, almost-tonal hissing that's always hovering just below the very-well-studied completely natural noise floor. Nimur (talk) 00:37, 4 September 2013 (UTC)

I doubt it's really that much of a problem for SETI, because SETI isn't likely to be able to detect anything that's not shot pretty directly at us in a narrow beam. Why an ET civilization would go to the trouble to do that, and then encrypt it so we couldn't understand it or even distinguish it from noise, would need explanation. --Trovatore (talk) 02:13, 4 September 2013 (UTC)

I inherited a fantastic book, formerly owned by Ronald Bracewell, called The Search for Life In the Universe, by Goldsmith and Owen (from UC Berkeley and SUNY Stony Brook). It is an excellent, very rigorously scientific analysis of this problem. There are two entire chapters on the motivation and practicality of using photons to encode information, including a brief section on the encoding of meaningful information as "bits" stored among the various physical properties of the photon (using the terminology of 1980-era physics and information theory, which is still pretty current, and I'm happy to say is totally bereft of the more recently popular term "qubit"). Anyway, anybody who is interested in squishing lots of information into a radio photon may find this book an interesting read - whether your goals are the academic pursuit of SETI or if you are more involved in the more worldly engineering practicalities of optical or radio communication. Nimur (talk) 14:38, 4 September 2013 (UTC)

This is not, as suggested above, "lossy compression" per se. That is, there is no theoretical issue with compressing audio like this indefinitely. You're just frequency shifting the data up into increasingly high frequencies, and frequencies can potentially rise infinitely high. To that end, you can in principle encode the whole Library of Congress into a single sub-second audio pulse. Where the problems enter is in practical engineering -- no real device will handle those absurdly high frequencies, and so you won't be able to losslessly reverse the process. CDs, for instance, are engineered for about 22 kHz signals. Any signal above that frequency is fundamentally unidentifiable (and any digital implementation will share a similar hard upper bound). Analog equipment doesn't have that hard ceiling, but practical tolerances will still impose themselves before the audio compression idea gets very far. The end result, then, resembles lossy compression (because you certainly have lost data), but it shouldn't be confused with what is meant by "lossy compression", where even in the ideal case data is voluntarily destroyed. — Lomn 01:43, 4 September 2013 (UTC)

Agree with your analysis with a small quibble. The process as described is not just frequency-shifting; rather the time compression leads to frequency expansion. For example, if the original sound occupied frequency range 20Hz-20kHz,after being recorded at twice the speed, the signal will occupy frequency range 40Hz-40KHz. Thus the analog tape used to record the speeded up sound (and the equipment used to record/read the sound) will require higher physical tolerances to maintain fidelity, as you say. Abecedare (talk) 02:41, 4 September 2013 (UTC)

That's the real issue here. If you had an utterly perfect tape recorder - you could do what the OP suggests without loss. But there is no possibility of ever building anything that perfect. All practical tape recorders (and voice recorders of any kind) have limited bandwidth and limited dynamic range - so at every recording, some of the speeded up information is too high in frequency for the tape recorder to record. When you slow down one of those 2x speeded up recordings to retrieve the original text, it'll sound muddy - when you slow down the 4x, 8x and 16x recordings, that'll get worse and worse - to the point where you won't be able to understand what's said anymore. SteveBaker (talk) 13:23, 4 September 2013 (UTC)

September 4

Question about atomic repulsion.

If electrons are what repulse atoms, what happens if the atom has no electrons? Sincerly, camerontregan^talk 08:02, 4 September 2013 (UTC)

Then the positive charge of the naked nucleus would cause the atoms to be repulsed; or if you believe that the free neutron stands in as element number zero, then a neutron gas would be near impossible to contain, as temperatures anything higher than a few pico-Kelvin, it would simply diffuse through the walls of any containment vessel. Plasmic Physics (talk) 08:31, 4 September 2013 (UTC)

In a neutron star, that's what happens. Without the repulsive force of the electrons, the material collapses in on itself. If there is enough mass, you get a black hole - but for more sane objects, you'd get a solid material. An effect called quantum degeneracy pressure stops it from collapsing any further - and that's due to the Pauli exclusion principle which basically (very basically) stops identical things from being at the same place. SteveBaker (talk) 16:05, 4 September 2013 (UTC)

Flat feet

Is there any situation where flat feet/fallen arches would be an advantage? Thanks ツ Jenova20 ^(email) 10:21, 4 September 2013 (UTC)

Yes. You would be rightfully exempt from most physical exercises, e.g. running, because the lack of friction between the feet and the ground for you would be unfair so that's that. That is, if your flat feet were that serious. ☯ Bonkers The Clown \(^_^)/ Nonsensical Babble ☯ 10:40, 4 September 2013 (UTC)

Back in World Wars I and II, it could have gotten you out of army service. Nowadays, it appears that "flat feet are perfectly functional and may even be an advantage in sports", and among US Army recruits, the flat-footed suffer fewer training injuries than those with high arches, according to the New York Times article "The Maligned Flat Foot: Some See an Advantage". Clarityfiend (talk) 12:20, 4 September 2013 (UTC)

That's strange...I'd always heard the opposite, that flat feet affected balance, carrying loads, walking distances, and increased injuries overall, disqualifying people from the army. Thanks ツ Jenova20 ^(email) 12:55, 4 September 2013 (UTC)

A lot of the problem for the army back when that was an issue was that they only had one design of boot - and it didn't suit flat-footed people. Since they did a lot of marching around back then - it was a huge issue. (Sorry - I don't recall where I read that). SteveBaker (talk) 13:18, 4 September 2013 (UTC)

Perhaps you read it in our amazingly-well-cited section on toe anatomy and physiology, which references U.S. Army studies of comparative foot sizes - including the seminal post-war work, "Foot Dimensions of Soldiers" (1946) that distilled all knowledge learned about flat-footed American GIs of the second World War? It's almost encyclopedic, the amount of information available here!' Nimur (talk) 14:51, 4 September 2013 (UTC)

On a related topic, is this the top view of the left foot, or the under view of the right foot? The article toe anatomy and physiology says right...Thanks ツ Jenova20 ^(email) 16:23, 4 September 2013 (UTC)

Projects that cannot complete during the life of the people who started it.

We were talking (above) about a space mission to the nearest star...how it would certainly take hundreds of years to get there.

This made me think about the problem that whoever designed and launched this hypothetical probe - and (importantly) whoever came up with the funding for it - would never see their project do much more than disappear from our solar system.

This makes be think that it would be very hard to get funding for a long-term project that would produce no results until after everyone who had anything to do with it was dead.

Are there any projects like that underway right now that will eventually come to a definite conclusion - but not within the lifespan of anyone who was involved with making it happen? I'm having a hard time thinking of even a single one!

SteveBaker (talk) 18:08, 4 September 2013 (UTC)

Not a science project, but John Cage's As Slow as Possible is currently being performed in Halberstadt, Germany, and that will last until around 2640. More scientifically, one of the motivations for archiving astronomical data, including data from crappy old photographic plates, is to permit detection of changes that occur over long periods of time. This is, however, not a concrete experiment with a definite expected conclusion. --Wrongfilter (talk) 18:23, 4 September 2013 (UTC)

A while ago someone here mentioned Beal's seed germination experiment [9]. Currently running; the guy who started it is long dead. Several other candidates at that "longest running experiment" thread from a few months ago. SemanticMantis (talk) 18:38, 4 September 2013 (UTC)

Yes - but both of those examples produce benefits to the instigator from day one. I'm trying to come up with something where the original people who started the project have to do it entirely altruistically because they know for sure that they won't live long enough to see any of the results. SteveBaker (talk) 18:58, 4 September 2013 (UTC)

The Cologne Cathedral was started in 1248, suspended in 1473, and finally completed in 1880. The first usable part (AFAIK) was consecrated in 1322, 74 years after construction started. The people who constructed it may, of course, have drawn spiritual satisfaction from the mere act of building. --Stephan Schulz (talk) 19:07, 4 September 2013 (UTC)

Why doesn't Wikipedia provide medical advice?

Need a short answer, can't really read the long text about it, because of health problems. Is it because Wikipedia isn't qualified? This applies to the whole world. 78.156.109.166 (talk) 18:10, 4 September 2013 (UTC)

There is a pretty short disclaimer at WP:Medical about why Wikipedia does not offer medical advice. An even shorter answer is that your assumption is correct. There isn't a very good way to verify who is actually qualified to dispense medical advice so we just don't. 146.145.80.218 (talk) 18:37, 4 September 2013 (UTC)

There are really several underlying reasons - but probably the most important ones are:

• There are places in the world where it's illegal to practice medicine without a license - so we don't.
• Bad medical advice could easily kill or seriously harm someone - and we don't want to bear that responsibility.
• We recognize that text on a page hardly ever provides sufficient information to deliver a diagnosis - so we couldn't do a good job - even if we wanted to.

SteveBaker (talk) 18:55, 4 September 2013 (UTC)

I think you forgot the most important one of all, "we're covering our asses". The WMF doesn't want to get sued. --Trovatore (talk) 19:05, 4 September 2013 (UTC)

We don't, not because we couldn't do so in a responsible way addressing the above concerns, but because of opposition from some contributors here who will defend the current policy come what may. I participate on other forums where medical advice is given without any problems. In fact, quite a number of medical disasters have been prevented by us there. Count Iblis (talk) 19:16, 4 September 2013 (UTC)

what hormone is responsible for the facial fat sexual dimorphism in prepubertal children?

Is it progesterone or some form of progestin? Estrone or estriol? 64.134.65.22 (talk) 19:09, 4 September 2013 (UTC)

I mean, girls have more facial fat at 6-8 yo, way before puberty. Is this due to adrenarche? 64.134.65.22 (talk) 19:10, 4 September 2013 (UTC)

Ionized water - is there any truth to this claim?

Hi. I recently came across this article detailing an Irish technology involving treating water with nitrogen that supposedly increases yields by up to 30%. I find it a bit suspect because of its fantastic claims and the fact that none of the people mentioned have Wikipedia articles. Is there any truth to the science behind the claim? Thanks. ~AH1 ^(discuss!) 19:24, 4 September 2013 (UTC)