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February 27

Does mild sleep apnea boost athletic performance?

Russia is now suspected of having let its athletes use Xenon gas to boost atheletic perforamance of endurance athletes for about a decade. Apparently, if you inhale Xenon gas some time after exercise, then the shortage of oxygen will lead the body to produce more EPO and perhaps there are other effects that will boost the body's ability to transport oxygen better to the muscles. When I read about this, I was thinking that perhaps sleep apnea exists because it actually has similar beneficial effects. Of course, the severe sleep apnea is not going to be beneficial. But many people who in later life become sleep apnea patients would already have had mild sleep apnea when they were much younger without having had symptoms. Count Iblis (talk) 14:05, 27 February 2014 (UTC)[reply]

Well, sleep apnea is highly concentrated in people who are severely overweight. That fact doesn't seem to accord very well with your ideas. Looie496 (talk) 14:41, 27 February 2014 (UTC)[reply]
It has nothing whatsoever to do with sleep apea. Since xenon is an inert gas, it cannot participate in any body metabolism process, and breathing it is the same as reducing the oxygen and nitrogen partial pressure - the same as living at high altitude, which is well known to give improved oxygen delivery to tissues when you return to low altitudes. An interesting solution, as no test can be devised for something that cannot participate in chemical/enzymatic reactions, and living/training at altitude is a perfectly legal way to improve athletic performance. And done at reasonable concentrations, at cannot harm you, not in the short term and not in the long term, very different to performance boosting drugs, which are banned partly due to their adverse effects on long term health. 121.221.210.239 (talk) 14:50, 27 February 2014 (UTC)[reply]
But the trainers who are partial to this training method will feel the pressure to constantly improve, increasing the amount of xenon, until they cause brain damage or death in the athletes. StuRat (talk) 15:02, 27 February 2014 (UTC)[reply]
Come on guys! At least look it up first! The protocol described involves breathing a 50-50 oxygen-xenon mixture for minutes before going to sleep. [1] Besides, if xenon's action were just as an inert gas, you'd expect they'd use argon, which is cheaper and more common. Xenon is the least "inert" of the inert gases, and so I wouldn't rule out a drug-like effect... it'll be worth looking into further. Wnt (talk) 16:03, 27 February 2014 (UTC)[reply]
Note that the sources (including your one) also mention that effects may also last 48-72 hours and that such treatment may be better than a low oxygen environment (although it's not clear to me how well tested this is in humans) which as the sources mention, is also used to basically simulate a high altitude environment. Nil Einne (talk) 17:50, 27 February 2014 (UTC)[reply]
Would mild sleep apnea have a similar effect? Count Iblis (talk) 18:26, 27 February 2014 (UTC)[reply]
Dunno. The body actually produces more RBC's at altitude and is why Mt. Everest climbers spend a few weeks at base camp prior to climbing. RBC's can double in a few weeks at altitude. Is there any RBC studies of apnea patients? Apnea seems to be only a sleep related issue so I kind of doubt it would have a measurable effect on RBC count. Xenon/oxygen therapy seems more like what scuba divers would use to extend dive times. Is it also hyper- or hypo-baric? Divers use specialty gases to extend dive times and avoid the bends. See Breathing gas. I suspect the high concentration of oxygen relative to xenon is done in a pressure chamber and the relatively high molecular weight of Xenon prevents it from turning into bubbles at low pressure (and the bends). Oxygen helps the athlete recover faster. Just guessing though from my experience with Scuba and the "1 hour 50/50 mix" answer. Too much oxygen is toxic so that often limits dive depths (the pressure in the lungs equals the depth pressure, but that increases the amount of oxygen molecules - specialty gas mixes usually don't increase depth but do increase time at a shallower depth before the bends are an issue). It sounds like they are increasing the amount of O2 without overloading the system with gasses that will outgas at low pressure. --DHeyward (talk) 04:55, 28 February 2014 (UTC)[reply]
A similar effect to what? An oyxgen tent aka stimulating a high altitude environment or breathing a mixture of xenon and oxygen? As we have established, there's some evidence these don't seem to be the same thing. BTW, I was reminded yesterday of something else, I researched euthanasia before for the RD (mentioned twice, look in the archives) and seem to recall coming across xenon or argon or both. Some more quick searches now find [2] which discusses the anaesthetic and neuroprotective effects of xenon. [3] suggests it may also have cardioprotective effects. This discusses other effects [4]. If you look at the links and refs, it sounds like there are lot more recent studies like [5]. This [6] interestingly suggests that argon and xenon are different under normobaric conditions with argon lacking such an anaesthetic effects. Some more here [7] [8] [9] (this BTW suggests argon may also be useful for enhancing athletic performance). Most of these are not in humans (although some of them were) and they may not necessarily be relevant to how xenon or argon may improve athletic performance. But they do IMO further emphasise it's likely a mistake to simply treat is as equivalent to a lower oxygen concentration.
Nil Einne (talk) 16:17, 28 February 2014 (UTC)[reply]
A sidetrack about using this mixture therapeutically finds [10][11][12][13]. Most of these applications are very recent, so I am indeed intrigued by the possibility that this means it could be used even for cases like the optic nerve degeneration that was discussed a week or so ago,[14] to reduce ischemic damage even after the fact. What makes xenon special is that it is an inhalational anaesthetic, which is still as they say "a great mystery". There are some really peculiar results on the topic if you look into it. Wnt (talk) 16:34, 28 February 2014 (UTC)[reply]
Edit: I belatedly found [15] which also looks useful. Note that from what I saw (I didn't read that well), I don't think there's much of a suggestion of any chemical reactions. However it sounds like some of them may bind to active sites (including I think myoglobin) or otherwise have effects in biological systems, sometimes resulting in upregulation or downregulation in living systems. Stuff such as lipid solubility, permeability, molecular weight and other factors seem to play a part in their effects. Nil Einne (talk) 16:53, 28 February 2014 (UTC)[reply]
Just spotted [16] which suggest (obstructive) sleep apnea increases the red blood cell distribution width, which is a sign of ineffective red blood cell production. It appears more or less unrelated to erythropoietin. [17] Erythropoietin may be useful to treat it. [18] Then again, erythropoietin does seem to be involved in the less common central sleep apnea [19] where it can have a pathological effect on heart failure. Using apnea while awake for sports training was an idea in Med Hypothesis [20], which in my book puts the odds against it! Basically, because if a hypothesis has any support, or any way of getting support, it doesn't get published in Med Hypothesis... :) Wnt (talk) 16:44, 28 February 2014 (UTC)[reply]

Thanks everyone for your information/comments! Count Iblis (talk) 01:38, 3 March 2014 (UTC)[reply]

Alkalizing foods question

Below is a quote from the webpage: http://www.alkalizingforlife.com/page/page/5128908.htm

"The following lists go over the acid or alkaline values of the foods we eat. The accurate way to measure the alkalinity of food is how the food changes the pH value of the tissues of the body. Once food is digested, an "ash" is formed. The pH of this ash is different than the pH value of the actual food itself. Lemons for example are very acidic by themselves however when digested they have an alkalizing effect in the body!"

This is accompanied by a list of dozens of foods in the seven categories: highly alkalizing, moderately alkalizing, low alkalizing, neutral, low acidic, moderately acid, highly acidic.

Just to give a few examples, sea salt is rated as "highly alkalizing" and table salt as "highly acidic". Celery as "highly alkalizing". Bacon as "highly acidic".

My questions:

1) Is an "ash" formed when a food is digested by a human?

2) Is there any possible way that the pH of such ash could be measured in the human body? or after elimination from the body?

3) Is the webpage pure nonsense or is there some truth to what it says?

Thanks, CBHA (talk) 23:37, 27 February 2014 (UTC)[reply]

Complete nonsense. See Alkaline diet or http://rationalwiki.org/wiki/Alkaline_diet --Carnildo (talk) 02:44, 28 February 2014 (UTC)[reply]
The article makes a clear case that there is some pseudo-science about it, but the main confusion concerns whether it is the blood or the urine one is trying to alkalize. I think it's pretty mainstream science that acidic urine is a recipe for specific troubles in the excretory system, and herbalists cannot be blamed for viewing a diet that might avoid the need for a specific medication to alter pH as being a generally desirable thing. Using it to treat cancer, of course, sounds like very wishful thinking. But anyone who has ever seriously thought about what getting a kidney stone is going to feel like should have a keen appreciation of alkalinity. Wnt (talk) 02:59, 28 February 2014 (UTC)[reply]
(ec) Alkalizing foods are most relevant to gout and many kidney stones, in which the goal is to raise urine pH to increase the solubility of uric acid and clear it from the body. [21][22] Studies like this show that urine pH can be manipulated by this means. It is more common to prevent problems with potassium citrate, a commonly prescribed drug that is also a GRAS food component, which may benefit some unexpected populations. [23] In a pinch, magnesium citrate ought to have a similar effect and is an easily found nutritional supplement. However, of course, one can imagine that the healthy vegetables on the list have many benefits. I do have a hard time seeing how salt enters or leaves as anything but Na+ and Cl-; however, the network of ion pumps in the kidney is quite complex, and I'd really have to think carefully about whether there is a way that changing the overall amount of these ions passing through would affect the net flux of bicarbonate (versus exhalation of carbon dioxide) Wnt (talk) 02:51, 28 February 2014 (UTC)[reply]
Hmmm, just searching, it looks like KCl can actually raise urine pH [24] The relationship between salts and urine pH is complex -- see [25]. sodium and hydrogen, chloride and bicarbonate, they are all tied together in a network of exchanges that is also actually regulated by the body with paracrine associations between the distal and the proximal loop of the kidney.
I still think the bottom line, though, is that the body has the same potential control over pH as limestone. When raw limestone is dumped in water, it has only a very mild alkalizing effect against acid rain, but when it is heated to drive off the CO2, it turns into a caustic calcium oxide. The body has the same sort of range of opportunities -- it can process food to CO2 that is exhaled, or allow that CO2 to remain part of the overall composition of the urinary fluid as (in net composition) carbonic acid. (see [26] for an overview) So this is a regulated phenomenon that has to be studied empirically; the body isn't a test tube that can be counted on to passively reflect an average of what is dumped into it. Wnt (talk) 03:19, 28 February 2014 (UTC)[reply]
"I think it's pretty mainstream science that acidic urine is a recipe for specific troubles in the excretory system," - this is incorrect. Acid urine prevents urinary tract infection (UTI) and acidification of the urine is one of the major ways of preventing it. Typically accomplished with aspirin. — Preceding unsigned comment added by AboutFace 22 (talk • contribs) 00:02, 3 March 2014 (UTC)[reply]
Well, alright, I should have mentioned that alkaline urine is a recipe for specific other troubles in the excretory system!  :) After all, the range of values urinary pH can have should be a fair reflection of what values just plain work out best. And I am not accepting that an alkalizing diet is a desirable food choice for anyone - just for some people. Wnt (talk) 19:55, 3 March 2014 (UTC)[reply]

February 28

Great Heck train wreck

If both engineers in the Great Heck train wreck (What the Heck, no article?! This can't be -- it's on the main page!) were killed in the collision, then how did Andrew Hill, the instructor who was riding in the cab of the freight train, manage to survive? 24.5.122.13 (talk) 06:08, 28 February 2014 (UTC)[reply]

The article is Great Heck rail crash. HiLo48 (talk) 06:11, 28 February 2014 (UTC)[reply]
Fixed it for you. Don't know if anyone can answer "who lives/who dies" question. There were fatalities and injuries. He wasn't the "sole survivor" nor were the drivers the only fatalities so it seems it's random/speculation. --DHeyward (talk) 06:33, 28 February 2014 (UTC)[reply]
He survived because he didn't sustain fatal injuries - what more is there to say? Richerman (talk) 10:10, 28 February 2014 (UTC)[reply]
It could be instructive to find out how someone survives or doesn't, for the purpose of making safety recommendations for the future. ←Baseball Bugs What's up, Doc? carrots→ 12:58, 28 February 2014 (UTC)[reply]
As a writer of disaster novels, I find it very instructive to learn how a person can survive an otherwise fatal event. How did Shadrach, Meshach, and Abednego survive being burned alive in a furnace? How did Vesna Vulovic survive falling from a plane without a parachute (assuming, of course, that her story is true)? How did Joe Simpson survive falling down the mountainside? All these things naturally pique my curiosity -- and with luck, maybe discovering the secret and telling the world about it might save a life or two down the road... 24.5.122.13 (talk) 01:43, 1 March 2014 (UTC)[reply]
As was the case for all serious rail accidents in the UK, this crash was undoubtably investigated closely by Her Majesty's Railway Inspectorate, whose official Railway Accident Report will likely elucidate the matter. (I say "was" because this function has latterly been taken over by the Rail Accident Investigation Branch.) {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 14:40, 28 February 2014 (UTC)[reply]
Indeed, the full report is linked from the article in question. Incidentally, "train wreck" is too colloquial for an article title. I hope not all rail crash articles will be made redirects from the equivalent "train wreck" pages.--Shantavira|feed me 15:09, 28 February 2014 (UTC)[reply]
"Train wreck" is the standard American nomenclature for events of this type -- "rail crash" is AFAIK an exclusively British term. And what, may I ask, is wrong with providing a redirect, as long as the article's actual title remains the same? 24.5.122.13 (talk) 01:29, 1 March 2014 (UTC)[reply]
"It could be instructive to find out how someone survives or doesn't" It certainly would be instructive for the the crash investigators, but my point is that editors who contribute to this page are unlikely to have access to that information. Richerman (talk) 19:04, 28 February 2014 (UTC)[reply]
Are British accident reports made available to the public? ←Baseball Bugs What's up, Doc? carrots→ 19:53, 28 February 2014 (UTC)[reply]
All the RAIB's reports are public, they're on http://www.raib.gov.uk 20:21, 28 February 2014 (UTC)

(edit conflict) Yes it's linked to the article, as Shantavira says above. I've just scanned through The track obstruction by a road vehicle and subsequent train collisions at Great Heck 28 February 2001: A report of the Health and Safety Executive investigation and although it states that the instructor survived (p. 30), it doesn't say why specifically. It does say "It [the freight locomotive] was heavily damaged on the front and right side, and below the cab in the vicinity of the missing right buffer, with part of the DVT [the passenger loco] embedded below the right front window. The interior of the leading cab was mainly intact, but all the windows were broken. The two drivers seats were undamaged and fixed to the floor. The survival space about the right-hand seat had been reduced below waist level" (p. 28). It goes on to say that "The exit for drivers from the locomotive cab is not easy. The driver has to move forward, around the control pedestal, before gaining access to the inward opening door in the rear wall of the cab. This opens into a cross passage that could be used as a refuge during a collision" (p. 29) It seems to me that the damage was all on the driver's side (the right) and the instructor on the left was saved by not being directly involved in the impact. An alternative is that the instructor got up and ran back into the "refuge", but I think that they would have mentioned this were it the case. Alansplodge (talk) 20:31, 28 February 2014 (UTC)[reply]

Thanks! This last comment pretty much answers my question -- the instructor probably survived because he was sitting in the left (fireman's) seat, and the express train hit the freight train on the right side. 24.5.122.13 (talk) 01:25, 1 March 2014 (UTC)[reply]
You're welcome. Alansplodge (talk) 01:33, 1 March 2014 (UTC)[reply]

Anxiety Symptoms From Different Sources Cause Anxiety

This is not a request for medical advice, it's a request for information about something I'm curious about from personal observation. That said: at one point in time, I had an anxiety disorder, I've noticed that now, years later, various anxiety attack effects can sometimes trigger a small anxiety attack. For example, I'd feel cold and a bit shaky when I had an episode, if I go outside and there is an extreme temperature differential, I get cold and shaky, which sometimes makes me feel like I'm having an anxiety attack. The same thing can happen if I purposely hyperventilate. Etc. This is not a constant thing, and when it does trigger anything, it's relatively minor; I'd be curious if any research has ever been done on this, the mechanisms for it, etc. Thank you for any help:-) *And, again: I'm not looking for a diagnosis, cure, etc. I'm quite fine; just curious about how it all works under the hood.Phoenixia1177 (talk) 10:54, 28 February 2014 (UTC)[reply]

Clarification: I realize that having anxiety in a situation can cause a link with that situation and anxiety. My curiosity is that this is directly linked to replication of symptoms, is not consistent, generally milder, and rather obvious - making it seem like it might be a separate type of thing/association.Phoenixia1177 (talk) 11:01, 28 February 2014 (UTC)[reply]
Our article on panic disorder does describe a mechanism of that type: "Another mediator is hypochondriacal concerns, which mediate the relationship between anxiety sensitivity and panic symptomatology; thus, anxiety sensitivity affects hypochondriacal concerns which, in turn, affect panic symptomatology". The reference given for that statement is Berrocal C, Moreno FR, Cano J (2007). "Anxiety sensitivity and panic symptomology: the mediator role of hypochondriacal concerns". Span J Psychol. 10 (1): 159–66. PMID 17549889.{{cite journal}}: CS1 maint: multiple names: authors list (link). Looie496 (talk) 14:28, 28 February 2014 (UTC)[reply]
We can answer medical questions, but we can't give medical advice. Looie496 (talk) 14:45, 1 March 2014 (UTC)[reply]
The following discussion has been closed. Please do not modify it.

This type of generalisation of symptomology is common in anxiety problems. Your reaction to the sensation of shivering is recalling a time when such shivering was a part of panic/anxiety. This is a learned behaviour and will take some time to unlearn. Recognise what is happening and allow yourself to feel the reaction while keeping calm. Self analysis of your reaction sometimes helps. If however the reaction triggers real panic it may be advisable to seek some support with a professional. Think clearly about what occurs, try to acknowledge to yourself that it is a memory of anxiety not actual anxiety. After encountering the stimulus several time without getting badly anxious the stimulus should stop being so worrying. Try looking for reports on controlled breathing and positive visualisation to provide techniques to sooth anxiety reactions.

shad darra---- — Preceding unsigned comment added by Shaddarra (talk • contribs) 05:27 1 Mar 2014

Sump pumps that work better

I would like to use a sump pump to drain water off my sidewalk where it accumulates during snow melt. However, it doesn't seem to work unless I have several inches of water there. It sucks in air instead. So I have to find other ways to clear the water. I know that digging a pit off the edge of the sidewalk on the lowest spot and putting the sump pump down there would work, but is there any way to get one to work short of excavations ? Do they make any designed for this situation ? StuRat (talk) 14:45, 28 February 2014 (UTC)[reply]

A sump pump needs a sump (which on its own will help to drain the sidewalk), but it only needs to be a few inches deep. Otherwise you would need a wet vac.--Shantavira|feed me 15:17, 28 February 2014 (UTC)[reply]
Yes, I've used a wet vac there before, but that's rather painful. Seems like a version of a sump pump that can pump down to a mm of water ought to exist. StuRat (talk) 16:19, 28 February 2014 (UTC)[reply]
Hmmm, that reminds me: what is the theoretical limit of capillary action given a specified volume to work in? I assume that if you completely lined the sidewalk with towels with their lower edges in the water, they would take it up. But assuming someone wants to pound a few poles into the ground up and down the length of the sidewalk, how do you calculate the theoretical maximum of the water they could take up and evaporate? Trees, of course, are good but not necessarily good enough for this; then again they aren't really designed to maximize water loss at all costs, and besides, wooden poles just don't seem to do it. I look at the brick in capillary action and think... if you could just make that work better, and have better surface area to evaporate from... is there theoretically (or even practically) a way, with the right marvel material? Wnt (talk) 16:24, 28 February 2014 (UTC)[reply]
That's what I was going to recommend too. A photo would help with the geometry, but all he should really need to do is dig a trench, fill it with gravel, and let gravity do its work. Probably no pump required! SemanticMantis (talk) 19:31, 28 February 2014 (UTC)[reply]
That rather depends on the geology. Here in London, we have London clay which is "relatively impermeable to water" according to our clay article. But then, we haven't had any snow at all this year. Alansplodge (talk) 20:36, 28 February 2014 (UTC)[reply]
You might be able to attach some sort of tube with a small bore on one end to your existing sump pump. Ensuring you keep any air out of the system might allow the pump to work as desired. There do seem to be some pumps designed to work with low water levels, fountain pumps, or surface water pumps[27].--Salix alba (talk): 06:32, 1 March 2014 (UTC)[reply]

The sidewalk has several low spots, and I'd like to be able to pump water out of those before it freezes into ice. I suppose I could dig several trenches, one by each low spot, and put a sump pump into each, but that doesn't seem very practical. Same with connecting the various low spots with a long trench. The low spots all tend to be at seams between slabs of cement, so there is a "micro-trench" between each seam, and a small enough tube sucking in water slowly enough might work there, although it would take hours at that rate, especially if more melt-water was pouring in.

So far I've just been pouring salt on the ice when it forms, but that kills the adjacent plants. StuRat (talk) 23:24, 1 March 2014 (UTC)[reply]

Hiv virus

Why are used needles such a large risk for HIV if the only method of transmission, during sexual activity is direct contact between blood, Semen or vaginal fluid or a mucous membrane. Surely the risk is lower for needles as the virus is unlikely to have survived on it. — Preceding unsigned comment added by 94.13.141.182 (talk • contribs)

Not on it, but in it. IV drug users usually shoot into a vein and draw in a little blood before injecting to make sure they have it one. μηδείς (talk) 21:23, 28 February 2014 (UTC)[reply]
Read also about mass Hepatitis C infections in healthcare settings. here's one[28]. There have been other cases where a contaminated syringe is used to draw medication from a vial and the vial becomes contaminated. Here is another one [29]. I don't know if hepatitis C is more or less resilient than HIV but they have common pathways for transmission (they are also very different in mechanism). The flu virus can live on hands and surfaces so viruses can have a lifetime outside the body (flu virus seems obviously more hardy than either hep C or HIV, though). HIV can survive longer than 6 weeks in a syringe.[30] --DHeyward (talk) 07:48, 1 March 2014 (UTC)[reply]
Now there's a statistic that we should hear more often in public service announcements. I thought about this, and my guess was that because syringes have a rubber plunger, when you finish injecting a drug, there will be some resilience pulling blood back up. I would imagine that opiate addicts might be particularly avid about pressing out every last microliter... looking this up led me to low dead space syringe, which actually does seem to reduce transmission risk considerably. [31] It is amazing that so many people have died over such a tiny issue in careless design (though of course primary blame goes to the foolishness of drug prohibition to begin with). Wnt (talk) 11:40, 2 March 2014 (UTC)[reply]

March 1

Caterpillars

Does a catterpillar have bones — Preceding unsigned comment added by 117.206.155.229 (talk) 02:30, 1 March 2014 (UTC)[reply]

Bones are unique to fish and higher vertebrates, although Echinoderms, which are related to Chordates, do have calcified plates. Caterpillars are softbodied larva of certain types of insects, which have chitin to harden or support their exoskeletons. They aren't even closely related to us. What makes you ask the question? μηδείς (talk) 02:43, 1 March 2014 (UTC)[reply]

  • Caterpillars certainly don't have bones ... yet, it's interesting to consider the blurry edge of the concept. Bones are a sort of calcified cartilage found in bony fishes and their descendents, but not sharks. Yet sharks are certainly capable of impressive swimming! So how essential is the calcification to the idea we might really have in mind when we talk about a bone? Now... when we speak simply of cartilage in invertebrates, we find things like molluscs and horseshoe crabs have it. [32] For insects, it's not so clear ... but put it this way: fruit flies need a protein called osteonectin or SPARC which binds calcium and has a role in membranes that can define bones [33] to assemble their ventral nerve cords with collagen [34], which are the equivalent of vertebrate dorsal nerve cords i.e. spinal columns, which also need it for this purpose. [35] Now this doesn't mean that caterpillars have a spine, but it gives us a hint that the differences aren't really as big as we might imagine when we just look at their outer structure.

Predation question

What bird species (if any) are natural predators of the swallowtail butterfly? 24.5.122.13 (talk) 09:19, 1 March 2014 (UTC)[reply]

Our article on swallowtail butterfly gives an example, the red-winged blackbird. — Preceding unsigned comment added by BbBrock (talk • contribs) 10:27, 1 March 2014 (UTC)[reply]
And presumably any other insectivorous birds in the locality that are large enough to catch one. Richerman (talk) 12:53, 1 March 2014 (UTC)[reply]
Doesn't it taste awful, like the monarch butterfly? 24.5.122.13 (talk) 19:54, 1 March 2014 (UTC)[reply]
No, they pretend to taste awful, like the viceroy. --jpgordon::==( o ) 22:18, 3 March 2014 (UTC)[reply]

Bending moments

Why do physicists talk about pivots when referring to bending moments, while engineers never seem to mention pivots? Using this pivot theory, would the pivots on , for example, a beam with 3 simple supports evenly spaced and a uniformly distributed load applied, just be where the bending moment is 0? It wouldn't be where the simple supports are because the bending moment is maximum at the middle support. Clover345 (talk) 12:58, 1 March 2014 (UTC)[reply]
Also in this case, why is the shear force from the central support double the shear force from the end supports according to the shear force diagram? Clover345 (talk) 13:14, 1 March 2014 (UTC)[reply]

(1) Please define pivot, because I'm not familiar with pivot theory. (2) Each of the end columns takes half the load from the half of the beam that it supports -- in other words, a quarter of the total load -- but the central column takes the other half of the load from BOTH halves of the beam, which is twice the load on either of the end columns. 24.5.122.13 (talk) 20:00, 1 March 2014 (UTC)[reply]
A rigid beam resting on three or more supports is statically indeterminate - it cannot be analysed using nothing more than Newton's first law, Newton's third law and the principle of moments. In practice, a beam with three or more supports must be considered flexible and its deflection properties must be taken into account in order to obtain sufficient extra information to render the problem amenable to analysis. Dolphin (t) 04:23, 2 March 2014 (UTC)[reply]
I think Clover345 specifically stated that the load is uniformly distributed along the beam, which is an additional constraint on the system. Are you saying that it will still be statistically indeterminate even under this condition? 24.5.122.13 (talk) 05:18, 3 March 2014 (UTC)[reply]
Yes. Newton's laws of motion (the first and the third) and the principle of moments yield a maximum of two independent equations. These can be used to solve two unknowns, such as the reaction at two supports. If the beam sits on three or more supports, Newton's laws of motion and the principle of moments are not sufficient - extra information must be supplied and used. The extra information usually used in the case of a flexible beam resting on three or more supports, is information about the deflection characteristics of the beam. Information about the load on the beam (whether the beam carries a uniformly distributed load, or not) does not provide the sort of information necessary to obtain a third independent equation and so solve for the load at three supports. (Note that the expression is statically indeterminate, not statistically indeterminate. Dolphin (t) 11:38, 3 March 2014 (UTC)[reply]
  • @Clover345: I've never used the term "pivot" in a situation like this, but from a little googling, it appears to just be another term for simple support, i.e. a support that can rotate but not translate. So no, the pivots would not be at the points of zero bending moment, they would be at the supports. There is no reason to think that the bending moment must be zero at an interior pivot.
For your second question, Dolphin51 is correct; you can't know the reactions without more information about the deformation characteristics of the beam material. But if you assume Euler-Bernoulli beam theory (ignoring shear deformation), you can calculate shears and reactions. You need to be careful with your wording; "shear force from the central support" could be interpreted two ways. The shear in the beam at the end support is (3/8)wL, and the shear in the beam on each side of the interior support is (5/8)wL. But the reaction at the interior support is the sum of those shears, or (5/4)wL. So the central support carries 62.5% of the load, and each end support carries 18.75% of the load. One way to think about "why" this happens is that the beam at the interior support can resist rotation, while the end support can't. It's therefore stiffer, and attracts more of the load. --Floquenbeam (talk) 20:55, 3 March 2014 (UTC)[reply]

Digestive enzymes have anything to do with Obesity?

Anything it all in the etiological sense? thanks. Ben-Natan (talk) 13:32, 1 March 2014 (UTC)[reply]

Enzymes have everything to do with pretty much everything that happens in biological systems - without the appropriate enzymes, we'd be unable to digest food at all - and pretty soon, we wouldn't be obese anymore! So "in the etiological sense" (meaning a direct causative link), yes of course. But if you're asking whether some specific enzyme deficiency, excess or malformation could be the specific cause of obesity, then that's a very different question. There are many causes of obesity - and because close to half of the people in the USA and parts of Europe are obese, it's hard to argue that faulty enzymes are to blame. Check out Obesity#Causes for a list of the likely and known causes. SteveBaker (talk) 14:37, 1 March 2014 (UTC)[reply]
You should consider whose digestive enzymes are at issue. Gut microbiota have been implicated in obesity, and they have a very important role in digesting food. Not only do you depend on them for production of some vitamins -- there's actually a potentially deadly pathogen Bacteroides fragilis, which appears to be very important to prevent autism.[36] Indeed, when I read that, it occurred to me that if bacteria have such a significant role on the human consciousness, it may not really even be truly accurate for us to say we are "human". We are, I suppose, colonial organisms, a community which includes human cells, but also the microbes that live within us. Wnt (talk) 19:56, 1 March 2014 (UTC)[reply]

Alloy with electrical resistivity sharply increasing over a certain temperature

Is there a metal alloy that undergoes a solid to solid phase change at some elevated temperature, say several hundred centigrade, whereupon electrical resistivity significantly or dramatically increases? 121.221.210.239 (talk) 15:09, 1 March 2014 (UTC)[reply]

I was trying to find the resistance of some metals at different temperatures a while back and couldn't ind anything very useful so good luck, I'd be interested too. Dmcq (talk) 18:50, 1 March 2014 (UTC)[reply]
Plutonium undergoes several phase changes, but IDK about whether this affects its electrical resistivity. 24.5.122.13 (talk) 20:02, 1 March 2014 (UTC)[reply]
Correction: I do know now that it does affect its resistivity at low temperatures. From the article: "The resistivity of plutonium at room temperature is very high for a metal, and it gets even higher with lower temperatures, which is unusual for metals.[10] This trend continues down to 100 K, below which resistivity rapidly decreases for fresh samples.[10] Resistivity then begins to increase with time at around 20 K due to radiation damage, with the rate dictated by the isotopic composition of the sample.[10]" So as the temperature decreases, the resistivity of plutonium first goes up, then down quickly, then back up again -- VERY unusual behavior indeed! 24.5.122.13 (talk) 20:08, 1 March 2014 (UTC)[reply]
Gee, thanks, but as I am not a terroist with military connections, I'm not likely to come across any plutonium. Is there any metal alloy that is not radioactive that undergoes an electrically significant solid-to-solid phase change at elevated temperatures? With regard to Dmcq, were you interested in the normal continuous change in resistance of metals as temperature is increased? For metals commonly used in engineering, this is well documented. Any particular metal you are interested in? 121.221.210.239 (talk) 00:26, 2 March 2014 (UTC)[reply]
One I found was GeSbTe by googling for [alloy "phase change" resistivity]. DMacks (talk) 04:15, 2 March 2014 (UTC)[reply]
Thanks. There are several alloys in this class. They show a decrease in resistivity with increase in temperature though. I'm looking for alloys that show an easilly reversible increase. 121.221.210.239 (talk) 07:54, 2 March 2014 (UTC)[reply]
Not a metal, but you might be interested in PTC thermistors, based on materials such as Barium titanate--Srleffler (talk) 07:57, 2 March 2014 (UTC)[reply]
Thanks. But, again, I'm interested in materials that show a significant or dramatic increase in resistivity within a small temperature change (at an elevated temperature), not the gradual continuous change over a wide temperature range such as displayed by thermistors. And it must be a metal or metal alloy - or at least something that is not brittle like a ceramic. All essentially pure metals do, of course, show a more or less linear relationship between resistivity and temperature, whilst no phase change occurs. And alloys are available that show a sensibly constant resistance over a limited temperature range, such as those used to make resistors for the electronics industry. 121.221.210.239 (talk) 09:12, 2 March 2014 (UTC)[reply]
Look at these chiselers holding onto a paper from 1929 about this. Anybody with access want to post a copy of some of this stuff to Commons "for Aaron"? [37] Wnt (talk) 14:24, 2 March 2014 (UTC)[reply]
Let's back up a step here...is there some actual application or higher-level goal you have in mind? DMacks (talk)
Yes. I'm trying to work out how certain types of current-regulating barretters might work. Note that the wikipedia article on barretters is crap, but it does mention the iron-hydrogen barretter. These comprise a pure iron wire in a low pressure hydrogen atmosphere. They work because at a temperature around 1500 K the hydrogen atoms migrate into between the iron atoms, dramatically increasing the electrical resistance. This increases the power dissipation, increasing the temperature, absorbing more hydrogen, causing increased resistance and more heating ..... Because of this positive feedback situation above 1500 K, iron-hydrogen barretters show a characteristic dip (a negative resistance region) in current as voltage is increased beyond that needed to get 1500 K, and a section of the iron wire that has gone into hydrogen absorption visibly glows. As voltage is further increased, more of the wire length begins to glow, until the entire length is saturated with hydrogen and is glowing, whereupon with further increase in voltage the current increases again. There is thus three distinct regions in iron-hydrogen barretter operation - 1) at low voltage (typically zero to about 5 volts, current increases with voltage, 2) at moderate voltages (typically 5 to 12 V) voltages current falls slightly with voltage, & 3) a region at high voltages (typically above 12 V) where curent again increases with voltage. I already know all about this type as it is well covered in the literature.
There is another type of current regulating barretter that is a high vacuum type - no hydrogen. This type has no distinct operating regions and shows no current dip as voltage increases - current merely assymtotes toward a certain value, until voltage is high enough to blow the wire. Good current regulation occurs above about 12 V. It's manufacture seems to have been a trade secret. This type operates at a much lower temperature and does not glow. How might it work? Some folk think it works due to the positive temperature coefficient of resistance with temperature (as occurs in any pure or nearly pure metal), but it is easy to show both by laboratory measurement and simple theory that this cannot account for the very good current regulation - vastly better than any metal filament lamp - that such barretters provide. 138.217.246.250 (talk) 02:12, 3 March 2014 (UTC)[reply]
I don't get it. Why wouldn't the laboratories do a basic elemental analysis to find out what kinds of atoms are available to play with? It would certainly provide some useful search terms. Wnt (talk) 13:25, 3 March 2014 (UTC)[reply]
In mentioning laboratory measurement, I meant electrical behaviour measurements done by laboratories equipped as electrical/electronic laboratories, not chemistry laboratories. 138.217.246.250 (talk) 14:48, 3 March 2014 (UTC)[reply]
Wnt is right. If you're trying to bust the identity of a "secret" material, especially if there is real (especially commercial, or lots of especially motivated for itellectual) value to be had in knowing, a key thing to do is do every analysis of every aspect of the device you can. That means also studying each piece of the device itself rather than just the device as a whole in the manner intended to be used. Companies will do elemental analysis for a small fee for virtually any given element, and the actual "cost" is negligible and process fairly easy if you have the instruments in-house. DMacks (talk) 16:54, 3 March 2014 (UTC)[reply]
DMacks, if you don't know the answer to the question, then don't keep posting. You are not helping, you are just wasting your own time. Leave it for someone who can answer it. The cost is not neglible, and necessitates destruction of the museum quality device. I just want to know how they work, there is no commercial gain in busting the secrets of something that was rendered obsolete 50 years ago. 138.217.246.250 (talk) 00:53, 4 March 2014 (UTC)[reply]

Does anyone believe that dinosaurs still existed at the time of Jesus?

Question as topic. Just something I vaguely half-remember hearing once. I'm not talking about the belief that dinosaurs could be found in the Garden Of Eden, or that there were dinosaurs on the Ark - I know that some people definitely believe those... --Kurt Shaped Box (talk) 22:44, 1 March 2014 (UTC)[reply]

Birds are descended from theropod branch of dinosaurs. So yes dinosaurs about now, so they were about at the time of Jesus. Dja1979 (talk) 23:45, 1 March 2014 (UTC)[reply]
We both know that's not what Kurt means. Yes, many scientists like the idea of using cladistic nomenclature and adopting the point of view that as long as descendants of the Dinosauria clade exist then "dinosaurs" still exist, but Kurt is obviously using the term "dinosaur" in the colloquial, non-avian sense to refer to all the giant reptiles that, scientifically speaking, went extinct about 65 million years ago. Dragons flight (talk) 00:04, 2 March 2014 (UTC)[reply]
Does anybody accept the claim of a flying dinosaur that it was the father of Jesus? Hcobb (talk) 00:08, 2 March 2014 (UTC)[reply]
There is in fact a legend that a small flying dinosaur was a witness to Jesus's crucification and sang to comfort him as he was dying. 24.5.122.13 (talk) 06:20, 2 March 2014 (UTC)[reply]
Certainly, given that some people believe that dinosaurs still exist today (and I'm not just talking about the origin of birds). See Young Earth creationism#Paleontology and dinosaurs and Living dinosaur#In cryptozoology. Red Act (talk) 00:11, 2 March 2014 (UTC)[reply]
Certainly, someone believes anything you can think of. I would imagine if you've conceived of it, there's someone crazy enough to earnestly think it is true. Sort of a G-rated version of Rule 34. --Jayron32 02:09, 2 March 2014 (UTC)[reply]
At some level, you have to wonder how sincerely anyone could believe something like Grendel being a Tyrannosaurus, but there are indeed people who make such claims - and apparently "J.R." Tolkein proved it. Matt Deres (talk) 02:28, 2 March 2014 (UTC)[reply]
A group of Homo floresiensis taking on a Moa (or with less taxonomic accuracy, a Megalania) would be the equal of any fable. Wnt (talk) 04:22, 2 March 2014 (UTC)[reply]
Most questions that begin, "Does anyone believe…" probably need a "yes" answer. I'd rephrase slightly: Can anyone be identified that seriously believes Jesus rode a dinosaur? Certainly there are illustrations (and t-shirts) depicting such scenes. And there are those who maintain that Jesus's pet dinosaur was named "Skippy". But every one of these I have seen has their (you should pardon the term) genesis in well-deserved mockery of Young Earth Creationism rather than belief in the reality of the event depicted. Jesus and his apatosaurus or brontosaurus, Beginner's Bible Coloring Book. Often these illustrations are attributed on the Internet to sources, such as AIG or the Creationism Museum that would make them seem as if they represented sincere beliefs, but I haven't seen a case where the attribution was actually true. - Nunh-huh 08:17, 2 March 2014 (UTC) (Also, for those seeking devotional images, see here.)[reply]
Thanks for the answers so far, guys. I had also seen depictions of Jesus riding/feeding/holding dinosaurs and wondered whether they were parody or not. Poe's law time, maybe? --Kurt Shaped Box (talk) 12:33, 2 March 2014 (UTC)[reply]

Thing is, if you really believe in God, then all bets are off. The historical record doesn't need to be consistent anymore, anything is possible. God could have created the entire universe two seconds ago including all your memories as false memories about a World that has never actually existed. Count Iblis (talk) 16:18, 2 March 2014 (UTC)[reply]

Well yes, Iblis, if you assume an evil, deceiving God, unable to have conceived of evolution, since he's no smarter than his televangelists and money changers. μηδείς (talk) 16:36, 2 March 2014 (UTC)[reply]
It depends on whether you believe in the Bible-based God and the literal interpretation of the creation of the universe. I have also seen depictions of Jesus riding dinosaurs, I hope this is just to parody Creationists, because if they believe that kind of thing, who knows what's next. The Rambling Man (talk) 16:41, 2 March 2014 (UTC)[reply]
Well, if God created the universe with some effort, it might stand to reason that there was more than one draft involved -- I mean, we're only talking God, not Jack Kerouac. Maybe after the first day's editing it was enough to see the sun and the moon rise over the ocean and flat Earth for "all time", but then everything got revised to another version with some more backstory about how things got started, before long wacky ideas like round planets and excretion came in, and at some point, just for fun, the crazy notion of organisms just spontaneously coming out the way they're supposed to look because that just "works best" was invented. And it's perfectly conceivable that an omnipotent being could rewrite all of history from Big Bang to final heat death to be even more outlandish and clever and beautiful on the next draft... and wonder what the odds are it'll include a character somewhat based on mine. Wnt (talk) 21:10, 2 March 2014 (UTC)[reply]
Perhaps in the next revision, some population self-limiting mechanism will be "invented" that does not ultimately rely on the Malthusian self-limiting, in which case the population might be small enough that the chances of any recognizable resemblance for any of us would be remote. However, I sort of like Jarred Diamond's depiction of societies competing and overwhelming each other of the the ages, not dissimilarly from bacterial colonies competing in a Petri dish. —Quondum 02:49, 3 March 2014 (UTC)[reply]
Well, this is why religion isn't science. An omnipotent Creator can do anything -- entirely change the laws of logic and mathematics, revise history so that the bad things never even happened, even find a way to keep the plot elements he or she likes intact throughout such massive revisions. Even within a Ten Commandments (the movie) view of Christianity, Jesus could say "Lazasaurus, come forth" and pose with him for the camera. :) Wnt (talk) 04:01, 3 March 2014 (UTC)[reply]
That's not "religion", it's textual fundamentalism, the texts being rather poorly limited unscientific cartoons. There are philosophically serious religions which don't accept such silly reliance on human texts as if they were experimental evidence. It's rather insulting to Stoics, Buddhists, most Rabbinical Jews, and Catholics, for example, to insist religion is the same as literal faith in a text and only a text. μηδείς (talk) 05:18, 3 March 2014 (UTC)[reply]
There are many who think it IS religion. HiLo48 (talk) 07:52, 3 March 2014 (UTC)[reply]
I didn't suggest that literal faith in a text was the definition of "religion"; only that religion encompasses a larger sphere of philosophical inquiry in which people can question whether reality is real. To the scientific mindset this seems absurd (and I've been there - I was a Dawkins 20 years ago) but the scientific mindset doesn't have answers for everything e.g. why people "really" feel things rather than merely responding, like robots, to what they sense without being "consciously aware" of doing so. Because our perspective is that of the difficult-to-define consciousness rather than that of one or more atoms with a defined and ongoing existence whether they pass into the body and brain or out of it, our "reality" need not follow the material trajectory of those atoms, and may not correspond to physical law. And (like a Holodeck) the universe we perceive may simply not accurately reflect in its internal history all of the changes that have been or could be made to it. Wnt (talk) 09:03, 3 March 2014 (UTC)[reply]

Tidally locked planet rotation?

Sorry if this has already been asked.

Wouldn't a tidally locked planet with significant amounts of water flip as the ice built up on one side, making the planet heavier on one side than the other? If it would rotate because of ice buildup at all, would it flip, or would it rotate gradually to continually melt the glacier "twilight" zone? Be——Critical 22:47, 1 March 2014 (UTC)[reply]

No to both -- tidal locking is due to the gravitational distortion of the planet's lithosphere itself, compared to which the mass of the ice is insignificant. 24.5.122.13 (talk) 23:04, 1 March 2014 (UTC)[reply]
And that's because the planet is flattened into a disk instead of a sphere? So that flipping would turn it on edge first, and that would take a huge imbalance to accomplish? Why wouldn't the lithosphere deform over time even under minor amounts of pressure from ice? So you might have one rotation over millions of years? Be——Critical 23:37, 1 March 2014 (UTC)[reply]
The planet is elongated, not flattened, by the tidal effects. And the ice forms part of the mass of the planet, so it would not be correct to describe it as "heavier on the one side". —Quondum 04:32, 2 March 2014 (UTC)[reply]
Okay got it thanks, I was thinking of it wrong but elongation explains it and why it wouldn't flip (: Be——Critical 05:22, 2 March 2014 (UTC)[reply]
One could say that a tide-locked satellite is elongated and flattened: typically the diameter in the direction of the primary is longer than the diameter along the orbit, which in turn is longer than the axis of rotation (the diameter perpendicular to the orbital plane). —Tamfang (talk) 00:42, 3 March 2014 (UTC)[reply]
The planets are elongated not by tidal effects but the centrifugal forces. Tidal effects are created by another celestial body in "close" enough proximity, and they are not stationary but moving around the planet like the tides on the earth surface created by the moon and to less extent by the sun. --AboutFace 22 (talk) 16:46, 2 March 2014 (UTC)[reply]
AboutFace, you may wish to read Tidal force – your interpretation of "tidal effects" is far narrower than the sense in which we are using it here. —Quondum 20:48, 2 March 2014 (UTC)[reply]

March 2

Geography of glioblastoma multiforme.

I am wondering if this information exists somewhere. Thanks.--AboutFace 22 (talk) 03:34, 2 March 2014 (UTC)[reply]

"Coffin corner" flight ops

Is it true that as an aircraft approaches its service ceiling, its V(x) increases? And as for V(y), does it decrease as the plane climbs toward its service ceiling, or does it stay the same? (Just to clarify, my question is in terms of indicated airspeed, not true airspeed.) 24.5.122.13 (talk) 04:48, 2 March 2014 (UTC)[reply]

Well, air gets thinner up higher, which will allow planes to move horizontally faster (V(x)), but provides less lift at a given speed, limiting the climb rate (V(y)). Of course, V(y) could also describe the descent rate, and the flight speed is dependent on many other factors, as well, such as engine speed, flap and aileron configurations, etc. StuRat (talk) 17:44, 2 March 2014 (UTC)[reply]
No, V(y) cannot describe the descent rate, because it represents the best rate-of-climb speed, and V(x) describes the best angle-of-climb speed -- see V speeds for the definitions of V(x) and V(y). 24.5.122.13 (talk) 01:03, 3 March 2014 (UTC)[reply]
Have you tried Flight envelope article yet? 71.20.250.51 (talk) 03:31, 3 March 2014 (UTC)[reply]
Sure I did, but it does NOT address how V(x) or V(y) change with altitude. 24.5.122.13 (talk) 05:13, 3 March 2014 (UTC)[reply]
I haven't had any luck either, but conjecture suggests the answer is "yes" to your original query; however, we need to find facts from reliable source(s). If found, "somebody" (hint, hint) should clarify this in the appropriate article(s). ~E:71.20.250.51 (talk) 07:34, 3 March 2014 (UTC)[reply]
I'm pretty sure that my original conjecture was correct as far as V(x) is concerned (I can tell as much from power curve data), but I'm not quite sure what happens to V(y). 24.5.122.13 (talk) 07:47, 3 March 2014 (UTC)[reply]
I suspect the V(y) question largely depends on aircraft type. For example, a commercial heavy still requires lift vector from wings as it approaches ceiling, but in general, for fighters that is less important; in effect, they rely on the thrust vector. At altitude, the wings are essentially control surfaces; the 100-series fighters had a reputation of dropping like a brick if power was lost. — Preceding conjecture added by 71.20.250.51 (talk) modified:18:02, 3 March 2014 (UTC)[reply]

Immune system and infectious disease

It has been known that some people's immune systems can clear infectious diseases before they cause symptoms or while it is only causing mild symptoms. This tends to be for infectious diseases transmitted through the air, surfaces or food but what about for those which are transmitted sexually? Can the same happen for these? Clover345 (talk) 11:14, 2 March 2014 (UTC)[reply]

Here is a list of asymptomatic STDs, which may go some way to answering your question.
Different diseases have different thresholds for exposure to create a self-sustaining infection. Many of our individual articles on diseases make mention of these. I don't know if there's a consensus about why. But some diseases require a rather large number of antigen exposure, while others require very little. This isn't the same, but it's similar to the OP question. Shadowjams (talk) 18:28, 2 March 2014 (UTC)[reply]

Hi

Please see Talk:Resistant_starch#As_functional_fiber. Good day. Ben-Natan (talk) 12:26, 2 March 2014 (UTC)[reply]

The relevance of that to this reference desk is......? The Rambling Man (talk) 16:41, 2 March 2014 (UTC)[reply]

Sound of freezing rain

My house has been getting freezing rain at a rate that's taken my car (parked; I'm not typing while driving :-) from clean to thoroughly covered in half an hour. I knew that it had arrived when I first heard the "clicking" sound typical of freezing rain — but why? Why does freezing rain produce this sound? No answer in glaze ice, ice storm, or freezing rain. Nyttend (talk) 13:45, 2 March 2014 (UTC)[reply]

If it's making a clicking sound, I'd say it was already partially frozen when it hits (sleet). Freezing rain normally means it's all liquid when it hits, but then freezes when it hits objects below freezing temperature. Of course, during one storm you often get both. StuRat (talk) 17:31, 2 March 2014 (UTC)[reply]

According to ice storm, Most ice storms are in the northeastern US, but damaging storms have occurred farther south. Is this really true? I can't imagine why it would be a primarily American thing, i.e. why "most" of them would be in a tiny part of the world. Should it perhaps read most American ice storms are in the northeastern US...? Nyttend (talk) 13:45, 2 March 2014 (UTC)[reply]

What is this thing you call the world? Is it near Amarillo? μηδείς (talk) 16:33, 2 March 2014 (UTC)[reply]
It's most likely an indication that most of our articles are US-centric, something we're all used to but can't seem to fix. The Rambling Man (talk) 16:35, 2 March 2014 (UTC)[reply]
And you reported here rather than fixing it because.... --Jayron32 03:26, 3 March 2014 (UTC)[reply]

BeFeC

Why isn't beryllium-steel alloy in the Alloy steel article? It's the lightest usable metallic material, isn't it? Usable for being in air and stuff. Sagittarian Milky Way (talk) 17:28, 2 March 2014 (UTC)[reply]

Find a source, then be bold and add it yourself. StuRat (talk) 17:37, 2 March 2014 (UTC)[reply]
I've never heard of it. According to [38], beryllium is not very soluble in iron at temperatures < 600 C. I doubt you'd be able to add more than a couple percent without it forming other compounds. Beryllium is light, but it's also expensive (2x as much as Mg and 10x as much as Al) and toxic. Mr.Z-man 20:20, 2 March 2014 (UTC)[reply]
It's been over a decade, I might've misremembered the combination with Al or even Ti or Mg. And the article on the element states that it's unreactive enough to be used pure in rocket nozzles, so maybe /that's/ the lightest metallic material that's been used in air. (Yes, I was aware that you've got a demanding application if you need something this toxic, fire hazardous and expensive to save a little weight) Sagittarian Milky Way (talk) 00:36, 3 March 2014 (UTC)[reply]

Is the ARKYD Kickstarter satellite telescope in orbit now?

If so, whose rocket launched it into orbit? 75.75.42.89 (talk) 19:06, 2 March 2014 (UTC)[reply]

Please, see Planetary Resources. Ruslik_Zero 19:27, 2 March 2014 (UTC)[reply]
I saw a lot about their satellites in that article, but didn't see anything stating who puts them into orbit for them. 75.75.42.89 (talk) 19:38, 2 March 2014 (UTC)[reply]
According to this it's not due to launch until 2015. Richerman (talk) 21:22, 2 March 2014 (UTC)[reply]
So the answer from that source is "Virgin Galactic and Planetary Resources have a previously established relationship, with Planetary planning to launch Arkyd-100 space telescopes into orbit using the to-be-built LauncherOne air launched booster when it becomes available." 75.75.42.89 (talk) 23:13, 2 March 2014 (UTC)[reply]
Which is also the answer given in our article which hasn't been modified since 7 February "In July 2012, Planetary Resources announced an agreement with Virgin Galactic to enable multiple launch opportunities for its series of spacecraft on LauncherOne starting with the Arkyd-100 series of space telescopes." The 2015 date is also given in our article "The near-term attempt to validate and mature the technology is planned to launch in April 2014, before launch and flight test of the Arkyd-100 in 2015.[24]" Our article also covers other details of their current and future plans e.g. "company is contracting with NanoRacks to take the A3 to the International Space Station, where it would be released from the airlock in the Kibo module" Nil Einne (talk) 12:44, 3 March 2014 (UTC)[reply]

Aquifers

Where can I find out exactly which aquifers supply Lebanon, CT? — Preceding unsigned comment added by 99.146.126.108 (talk) 19:37, 2 March 2014 (UTC)[reply]

The only major groundwater supply in Connecticut is known as the "Early Mesozoic basin aquifer", see here, it's the turquoise colored streaks along the east coast of the U.S.; said aquifer seems to lie mostly in the Connecticut River Valley. Lebanon, Connecticut lies outside this area, so there does not appear to be large groundwater supplies in that area. Water supplies from that town are likely from resevoirs, see here for a list of reservoirs in the state of Connecticut. Perhaps find one near Lebanon. --Jayron32 03:25, 3 March 2014 (UTC)[reply]
I am not sure what aquifer or aquifers serve Lebanon, CT< jayron, but the map you have provided is a very general source which shows the three main aquifers in CT, the turqouise one being one of those three. There are plenty of smaller separate aquifers the size of municipalities or so. Any search for "connecticut aquifer map" will show this. For example, see this map. μηδείς (talk) 05:12, 3 March 2014 (UTC)[reply]
Good find! It should be noted that all of that map labeled "crystalline rock" is basically non-Aquifer rock. --Jayron32 13:16, 3 March 2014 (UTC)[reply]
You could check with the town government, who operate a Water Pollution Control Authority. It sounds like drinking water supply is authorized and maintained by a different level of government, presumably by your state or county or regional water authority. For example, the Regional Water Authority (of South Central Connecticutt) looks like its distribution ends west of your county; the South East Water Authority might cover you. If you use municipal supply, to whom do you pay a water bill? If you use well-water, you might have to ask around a little more - which contractors drilled or maintenanced your well? Which county or other government (if any) performs safety or health checks on your well? Nimur (talk) 15:58, 3 March 2014 (UTC)[reply]
  • Since 9/11, inquiries like this made by people with no legitimate reason are looked into as possible signs of scouting for terrorist goals. People have been investigated for taking pictures of, or on reservoirs. μηδείς (talk) 18:24, 3 March 2014 (UTC)[reply]
I hope you're wrong about this, but in this spy-crazy world... I can't swear to that. Though it beats me why a terrorist would care where the aquifer water ends up, as long as he can contaminate it. By contrast, a keen awareness by townspeople of where their water comes from could be very useful for protecting life and property. Wnt (talk) 20:05, 3 March 2014 (UTC)[reply]
I spent a minute googling for investigations of people at aquifers expecting to get his on NYC's upstate reservoirs, but got hits mostly on the Squabbin reservoir.

March 3

Blood donation risk factors

Why do different countries, even with similar statistics for HIV risk etc have different eligibility criteria for donating blood? For example, in the US those who have had tattoos in a licensed state, are not barred from donating blood but in the uk, they are barred for 4 months despite licensing for tattoo parlours existing across the uk. Similarly, men who have sex with men have a lifetime ban in the US, whilst only a 12 month ban in the UK. Other risk factors such as those who pay for sex are not even considered a risk factor in the us, whilst there is a 12 month ban in the uk. Why are these restrictions so different? — Preceding unsigned comment added by 2.126.193.17 (talk) 11:09, 3 March 2014 (UTC)[reply]

Because different people in different places are making different decisions. --Jayron32 13:14, 3 March 2014 (UTC)[reply]
As a regular donor I can tell you it's because of the Window_period for various infectious diseases. The ban is an attempt to screen donors in that period where the disease is not detectable in a blood/serum test. This relies on people telling the truth about their sexual activities. Both systems (US and UK - and even South Africa) have risks to the recipient. When my father went for his prostate op my brother and myself donated and "banked" our blood for him. The blood is still tested but dad knows we would not lie about the screening questions. 196.214.78.114 (talk) 13:49, 3 March 2014 (UTC)[reply]

Human body parts that we have more than 2 of?

What is the body part that we have the fewest of but we have more than 2 of?

Besides fingers and toes.

And not general body parts like "facial orifices" or "bones in the forearm". They should be discrete body parts like kidneys or femurs or hairs on the head. — Preceding unsigned comment added by 24.228.94.244 (talk) 15:40, 3 March 2014 (UTC)[reply]

Wisdom teeth? --109.189.65.217 (talk) 17:53, 3 March 2014 (UTC)[reply]
The pineal gland is historically a third eye, and was active as a light sensor in early fish. The liver usually has three lobes, but that is not vital to its function. There are all sorts of nerves, muscles and bones that come in small sets, like cranial nerves. The inner ear has three canals for balance in the three dimensions. μηδείς (talk) 18:18, 3 March 2014 (UTC)[reply]
Hmmm, that's good... except you have two ears, making it 6. :) Getting to 3 is difficult, but I'll go with ... the tricuspid valve. Except, that is, sometimes it doesn't have 3. :) For 4 there are more choices, such as canine teeth. Wnt (talk) 19:59, 3 March 2014 (UTC)[reply]
That valve is a part of the heart. The OP would need to clarify just what he means by "body part". Does a portion of a larger organ count? ←Baseball Bugs What's up, Doc? carrots→ 21:35, 3 March 2014 (UTC)[reply]
Most people have two nipples. Some have three. A case could be made that the average person has two-point-something nipples. Also apparently applies to kidneys. (Other than that, an internet search for "people have three" finds little, other than "three brains" which probably doesn't qualify.) 88.112.50.121 (talk) 21:32, 3 March 2014 (UTC)[reply]
Veins and arteries. All connected, but many tributaries. Fewest and most. InedibleHulk (talk) 23:47, March 3, 2014 (UTC)

Oxygen

What's the lowest level of oxygen humans can tolerate? Is 2% enough to guarantee death? I heard some people can tolerate like 1%, which I find bull. Money is tight (talk) 23:21, 3 March 2014 (UTC)[reply]

It's not the percentage of oxygen, it is the partial pressure of the oxygen that matters. That is, lowering the percent oxygen by raising the overall pressure (such as adding an inert gas to the breathing gas) shouldn't have a significant effect. The actual amount of oxygen you need to survive is more complex than just a single number, it can be found most easily using the Oxygen–haemoglobin dissociation curve which depends on many factors, including blood pH, partial pressure of O2 in the air, partial pressure of CO2, etc. --Jayron32 23:26, 3 March 2014 (UTC)[reply]

Trumpet mouthpiece discolored?

Hey everyone, this may be a chemistry-related question. So, I play a Vincent Bach 1.5C mouthpiece, and lately I've noticed the inside is beginning to turn a light shade of bronze or gold, it seems, from the normal silver. A similar incident has happened before, where the inside of another mouthpiece had actually turned blue/purple/black. What's caused this? And I've heard that something can be done about the color change by using aluminum foil, baking soda, and hot water. Someone else said to use toothpaste. Can this work? Thanks. 64.229.204.125 (talk) 00:02, 4 March 2014 (UTC)[reply]

DNA testing and meiosis

How does making a match in a DNA test work when one of the samples is haploid? For example, if testing sperm from a crime scene, how does one prove it matches to a suspect if the sperm is meiotic/haploid/gametic, while presumably a DNA sample obtained from a suspect is mitotic/diploid/somatic. (Pardon all the slashes there, but I'm not 100% on which is the best terminology.) Thanks in advance, 76.168.226.134 (talk) 00:47, 4 March 2014 (UTC)[reply]

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