This is an old revision of this page, as edited by Mr.Z-man (talk | contribs) at 03:40, 8 April 2015 (→Material for heaviest bat possible: re). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

• WP:RD/S

Main page: Help searching Misplaced Pages

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

How do I answer a question?

Main page: Misplaced Pages:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

• Teahouse
• Help desk
• Village pump
• Help manual

April 4

Hit my head, unconscious for 1 minute, half of which was spent snoring

Blunt trauma and delayed death

When someone suffers an accident but survives and dies 24, 48 or 72 hours after the accident, what has deteriorated during this period that caused death? If someone has not died right away, but some days after the accident, something would be deteriorating during this period, right?. --Noopolo (talk) 15:27, 4 April 2015 (UTC)

See Major trauma. Dmcq (talk) 15:46, 4 April 2015 (UTC)

It takes some time to die even if some organs are completely nonfunctional. The kidneys, for example, remove waste from the blood, and it would take several days for the waste to build up to a fatal level (assuming no dialysis is done).

Also, if slowly bleeding internally, it may take that long to die from loss of blood. Then there could be a burst intestine, which could take that long to kill the patient due to infection. So, there's lots of ways it could happen. StuRat (talk) 17:45, 4 April 2015 (UTC)

• There are probably dozens of ways to answer this but what I can think of as the major categories would be internal bleeding, especially in the brain or body cavity, massive tissue damage leading to necrosis, and specific damage to organs like the kidneys or liver as mentioned above which don't kill you right away. Add clots leading to thrombosis to that list. My sister's uncle-in-law was hit in the head by a football on a post-thanksgiving game, felt fine, then fell into a coma two days later and died just after new years without ever waking up. See a doctor is the only advice we can give. μηδείς (talk) 22:31, 4 April 2015 (UTC)

Is sexual attractiveness distinctly physiologically and phenotypically different from physical attractiveness?

Although sexual attractiveness in non-human species seems to be more predictable and observable, which contributes to the sexual dimorphism of a species, the human species seems to be less predictable and observable. How does a human being distinguish between physical attractiveness and sexual attractiveness? Is sexual attractiveness really just physical attractiveness, plus sexual arousal? There is a well-known study in the field of psychology, in which men were placed on a suspension bridge and were held there until an attractive woman came along. The conclusion was that the fear and arousal of being on the bridge triggered the misattribution of arousal. In other words, the men were afraid about being on top of the bridge, but seeing the attractive woman made them divert their arousal and fear to the woman, thinking that the woman caused sexual arousal and hence sexually attractive. Does sexual attractiveness involve the erection of the penis in men? What about women? How do women experience sexual attraction? 66.213.29.17 (talk) 15:49, 4 April 2015 (UTC)

Think your referring to the Arthur Aron and Donald Dutton experiments. There is more than one way to explain these observations. Something that they did not mention is that Birds of a feather flock together. So if the male meets a woman in this situation, it suggest she would make a good mate who will bring up confident self-assured children -who therefore have more chance of survival. One has to be careful with psychologists, as they can design experiments to ensure the results match their own peccadilloes. So explaining why someone else, does the same experiment years later and comes up with different results. --Aspro (talk) 16:14, 4 April 2015 (UTC)

Thinking about it, this came up in conversation a while ago. Sigourney Weaver in Alien and Linda Hamiltonin in Terminator came over as a bit flumpsy in the first films but then their caricature evolved in to two females mothers that would go to the ends of the earth to protect. That is what a male wants (a subconscious drive that he's gene line will continue) and that takes two. Trophy wives are two- a-penny and can be divorced as soon as a better one comes along (and their offspring often end up as drug addicts and privileged children that strayed from the path into depravity). So meeting a female on a swinging bridge or abseiling down a cliff rather than in Mac Donald's or Starbucks makes complete sense to me.--Aspro (talk) 16:56, 4 April 2015 (UTC)

I'll suggest reading the subsequent life of Matthias Rust as a counterpoint to Aspro's approval of thrill seekers. μηδείς (talk) 23:17, 4 April 2015 (UTC)

???!!! Mathias Rust didn't meet a female on the whole fight! This above post is mixing animal/human instincts/psychological problems/ and pure absolute twaddle. It is no counter point at all in that example. Counter point is – oh, let a musician explain how two tunes move in and out. Counter-point can happen in lives too. Thats why, and as to why: two people, who started out living different lives, find they can blend together into a very happy life together and make beautiful music together – in a way that science still can't define. They don't have to be adrenaline thrill seekers – they might find they a both have an instinctive insight to Claude Monet and good food. Some couples can – and some couples can't counterpoint. So me thinks that is a very wrong example above. Disclaimer: Due to a confused and misspent youth, I have ended up with an appreciation of both with a foot in both camps (and being a tripod, I appear to have an other foot in another place).--Aspro (talk) 15:45, 6 April 2015 (UTC)

Feeding variac with 240 VAC at 110 VAC point

So my variac has 2 input, one is for 240 VAC and the other is for 110 VAC. If I connect the 240 VAC power cable to the 110 VAC input, will it double the output voltage? Is it safe for me and the variac? 118.137.229.147 (talk) 15:54, 4 April 2015 (UTC)

Most people do not need 480 volts. When they need more than 240v they use three phase. So your variac probably comes with instructions to use it only in the way way that it was designed for. The insulation may brake down at higher voltages and quite apart from the smell you might find the results electrifying.--Aspro (talk) 17:09, 4 April 2015 (UTC)

No, it is not safe, it will probably burn it out, and it is not safe to try this out. The power drawn might be more than four times that for which it was designed (because the current might be more than doubled, as well as the voltage). Dbfirs 17:11, 4 April 2015 (UTC)

This equipment was not designed for this use. It is dangerous! If it is automatically regulated, never feed the output. It will cause a damage due unable to control this output. If it is a transformer only, never operate it out of specified voltage range. Transformers have a energy conversion efficiency, causing in reverse operation, the voltage output unregulated is higher without load, dropping under load due unregulated less than expected and dangerous due circuit brakers, fuses, thermal fuses and other savety equipment, if installed, are locaded on the other coil and will have no functionality when neccessary! The reverse operation, even in range of specified voltages is dangerous if not clear specified for such use! --Hans Haase (有问题吗) 19:11, 4 April 2015 (UTC)

There goes my plan for overvolting stuff to get more power from it. So is it safer to put a step up transformer after the variac? 118.137.229.147 (talk) 23:46, 4 April 2015 (UTC)

Yes, and remember that if you double the voltage, you can draw only half the current to avoid overloading your variac. Unless you really know what you are doing, "overvolting stuff" is more likely to produce burnout than more power for any length of time. Dbfirs 07:46, 5 April 2015 (UTC)

The Rotation of the Voyager Space Probe

www.youtube.com/watch?v=jGD4i1oNoyo at 00:30

How did she rotate the Voyager spacecraft?

It's very unlikely that she ignites the spacecraft's rocket engine which has very limited supply of propellents.

Did they use the spaceprobe's gyroscopes to control its rotation? -- Toytoy (talk) 16:10, 4 April 2015 (UTC)

Both Voyagers have hydrazine thrusters. They didn't have gyro orientation. The Jet Propulsion Laboratory use this fuel very sparingly. Which is why it has lasted so long. Brilliant work for a probe that was originally just going to Jupiter. --Aspro (talk) 17:21, 4 April 2015 (UTC)

An article from a couple of years back says one such maneuver uses 100 grams of hydrazine, with around 250 maneuvers left until the spacecraft runs out, minus whatever is needed for routine attitude control operations. The two Voyagers should run out of electrical power before they run out of hydrazine. 88.112.50.121 (talk) 18:40, 4 April 2015 (UTC)

Thank you guys. I knew that Voyagers have hydrazine thrusters. I just could not believe that they only use the thrusters to rotate the probes. I thought they probably have a gyro hidden inside so the parts don't show on the illustrations. Do they use compressed gas to propel the hydrazine in the zero-g tank?

This is guess: helium is probably used as top pressure for the fuel tank (too cold out there for nitrogen). A stirrer in the tank is also probably need to ensure liquid hydrazine only is sent to the thrusters in zero-g. Although it was designed in the 1970's they were the bees knees in current technology and is a very complex probe so it would have do doubt need these, in order to function in deep space. The thrusters primary use were for navigation not orientation. Having gyros would have added another layer of complexity and it only needs to re-orientate now and then (unlike say the Hubble). Since its launch, its software has been update too. Value for money wise, I think the two Voyagers have turned out to be one of the most successful probes, considering all the science data that they have sent back – far, far beyond all expectations. Yet their cameras only had a 80 by 80 pixel view ( OK 'pels' for the pedantic) and what do our cheap cameras in 2015 have now – yet these two probes keep sending back really useful data.--Aspro (talk) 20:33, 6 April 2015 (UTC)

I still don't understand why they did not use a gyroscope or just a motor and a spinning weight to rotate the Voyager. They have a nuclear power generater. An electrical rotating system may save them much fuel. -- Toytoy (talk) 15:22, 5 April 2015 (UTC)

What you describe is a reaction wheel. Some reasons Voyager's engineering team may have elected not to use them include:

• they didn't want to incur the mass cost of three of these systems
• they needed faster pointing (on close approach events) than reaction wheels could do
• they were worried the reaction wheels would fail, given the very long timeframe and very cold environment
• note the article says "over time, reaction wheels may build up stored momentum that needs to be cancelled" (by some other attitude control system)

146.200.157.224 (talk) 21:41, 5 April 2015 (UTC)

The difference between mutation of gene and genome

April 5

What kind of psychometric test is this?

I’ve taken this exam as a requirement for a job. Unfortunately, I forgot what the exam was called. All I can remember is that the exam has 100 items grouped into five or four. Each group of five or four questions contains numerical, logical, and vocabulary questions. The questions look something like this:

Something that you use when raining --- U, S, G, C, M (Umbrella)

A small explosive thrown by hand --- G, C, W, J, Z (Grenade)

An apple costs $2.50. If you have $10, how many can you buy? --- 4, 5, 6, 4.5, 5.5

Complete the series: 1, 2, 4, 7, 11, 16, ? --- 22, 21, 20, 23, 24

What kind of psychometric test is this?49.144.142.130 (talk) 02:18, 5 April 2015 (UTC)

It reminds me of the IPATO, which was a special proprietary example of an aptitude test (more specifically - an intelligence quotient test), although the IPATO typically presented its answers in two-dimensional format just to slow certain thought-processes (and to favor people who were really good at linear algebra). Were these questions timed?

Proper administration of an intelligence test (like a Wechsler Adult Intelligence Scale test) typically costs a few hundred dollars. Fees cover the cost of the psychologists and professionals who design the test, as well as the intellectual property licenses for the questions and the scoring matrix - not to mention overhead costs to ensure sterile testing conditions. Many similar IQ tests like the Scholastic Aptitude Test and the Graduate Record Examination are administered by private-sector companies and also generally cost over a few hundred dollars. There are hundreds of alternative psychometric tests of similar caliber, vetted by individual contract companies or even built up by specialized in-house HR departments at large companies, that can be administered at much lower total cost. Perhaps your test was one such proprietary company test. Generally, such tests are not called "IQ" tests, for reasons of political correctness and avoiding liability, avoiding licensing, and avoiding strong emotional responses. Without exception, such tests are named "Incoming Applicant Aptitude Scoring System" or some similarly verbose description; this serves to obfuscate intent, but only for the subliterate.

Nimur (talk) 03:36, 5 April 2015 (UTC)

For that first question, shelter, coat, gaiters, and a mackintosh are also valid answers MChesterMC (talk) — Preceding undated comment added 08:44, 7 April 2015 (UTC)

Air Pollution Maps

Are there any other detailed air pollution level maps like http://aqicn.org? I don't need real-time information like aqicn.org (though it would be nice), but I'm looking for one with the most data points. Aqicn.org only has a few per city unfortunately. WinterWall (talk) 09:18, 5 April 2015 (UTC)

No, there is no denser resource. There is satellite data but most of that is lower resolution and limited to long-term averages (plus it has large calibration issues). There is also model data, but again lower resolution. That said, why do you want more data points? Most particulate pollution (the primary health concern) has a atmospheric lifetime of days and quickly becomes mixed on a regional scale (50-100 km). Local effects, such as being next to a factory or highway tend to provide only moderate perturbations. And, of course, some of the apparent detail is related to noisy or poorly calibrated instruments. More important than where you live in the city, is where the air you were breathing came from over the last several days. Air that is imported from industrial areas will usually be dirtier than that which can from agricultural or natural areas. And that depends strongly on day-to-day (and even hour-to-hour) wind patterns. Dragons flight (talk) 20:34, 5 April 2015 (UTC)

trees

Do trees grow as far down as they grow up? if you turned it upside down would it look the same? — Preceding unsigned comment added by Kelticone (talk • contribs) 11:53, 5 April 2015 (UTC)

It depends on the species of the tree, the distribution of water and minerals in soils (roots will grown towards them), and the wind load (wind encourages deeper roots). It is said of oak trees that the roots are about the same shape as the crown, but this http://gardening.stackexchange.com/questions/1555/how-far-on-average-do-tree-roots-extend-out-from-the-base-of-the-tree indicates otherwise. LongHairedFop (talk) 12:51, 5 April 2015 (UTC)

Oaks appear to oscillate. Roots gow, then stop, leaves and so on grow, then stop and go on with roots again. --Hans Haase (有问题吗) 15:58, 5 April 2015 (UTC)

Most tree roots do not grow anywhere near as far down as the branches twigs and leaves grow up. The roots tend to spread out, often surprisingly shallowly in the case of conifers. There are a few exceptions in species that are adapted to seeking deep water tables, but generally, for most species and most soils, the root pattern is wide but not very deep. A Google search gives some patterns for different species. Dbfirs 16:23, 5 April 2015 (UTC)

Yes, if you've ever seen a toppled tree, the roots tend to cover a circular area perhaps as wide as the crown, but nowhere near as deep. μηδείς (talk) 20:54, 5 April 2015 (UTC)

When looking at the Virginia department of Forestry you see that trees roots grow to the length the widest branch tips. From this we can see that the trees roots do not grow nearly the same length as the actual tree. You also see in they looked at the depth of roots for several different types of trees. By doing this they compared several different research papers to debunk a common myth about tree roots. They found that the deeper the roots the more drought resistant a tree is. And they only grow the length of the branch tips as well. For a final source I found that Jim Urban, FASLA, a noted tree and soil expert. He found that. “Roots require three things: water, oxygen, and soil compaction levels low enough (or with void spaces sufficiently large enough) to allow root penetration. If all these conditions are met, roots can grow to great depths. Under ideal soil and moisture conditions, roots have been observed to grow to more than 20 feet (6 meters) deep. From this we see that they have to have these for the tree to grow.” (Urban) Lami229 (talk) 21:40, 5 April 2015 (UTC)LaurenAlexis

References

2. Deeproot Urban Landscape

Female sexuality

Are lesbian women more or less likely, statistically speaking, to be virgins after the age of 30 than their straight counterparts? Please provide citations to back up your data

Eyebubummerglue (talk) 18:05, 5 April 2015 (UTC)

Not an answer to the question, but as noted at virginity, not everyone used the same definition. Many heterosexual couples consider the loss of virginity to only occur when a penis penetrates a vagina, while homosexual couples often include oral sex, mutual masturbation, and other acts as a loss of virginity. If one uses a definition that is tied to heterosexual acts, then it seems almost certain that many people who identify as homosexual are technically "virgins". On the other hand, if you include a variety of other sex acts, then many people who have been "saving themselves" and self-identify as "virgins" would probably lose that status under an expanded definition. Without a precise definition of which sex acts you mean, I doubt one could even begin to meaningfully answer the question. Dragons flight (talk) 19:37, 5 April 2015 (UTC)

These two journal articles discuss the subjective nature of "virginity", and discuss some data that includes lesbian participants . SemanticMantis (talk) 19:31, 6 April 2015 (UTC)

Jet aerodynamics of sound

Jet aerodynamics of sound is it been save on the speed of light?--83.237.214.60 (talk) 20:26, 5 April 2015 (UTC)

I'm sorry, but this question is not understandable. Some of us can read languages other than English. Therefore you may get a more useful response if you post your question in your native language. Short Brigade Harvester Boris (talk) 20:29, 5 April 2015 (UTC)

kettles in the bath

How many 1.5L kettles of boiling water would be needed to make a 80L bath of cold water the right temperature for bathing? — Preceding unsigned comment added by 108.192.136.193 (talk) 23:28, 5 April 2015 (UTC)

Anywhere from zero to many, depending on the temperature of the "cold" water and one's personal preference as to the right temperature for bathing. Short Brigade Harvester Boris (talk) 23:47, 5 April 2015 (UTC)

Many people use a bathing temperature of roughly 40 °C, so going with that if the cold water is 20 °C, the cold and boiling water should approximately be mixed in a 3:1 ratio. For a 80 liter bath this means 60 l of cold water with 20 l of boiling water (i.e. 13.33 kettles). Of course this is just an example of a typical situation; like the comment above points out, the answer can be quite different depending on the situation. - Lindert (talk) 00:09, 6 April 2015 (UTC)

(OR Alert) Having actually performed this experiment multiple times (after my gas-fired hot water system broke down), I can advise that in practice it takes rather more boiled kettles than the theoretical calculations indicate.

The problems are that (a) one has to boil the n kettles sequentially, not all at once, and (b) it takes several minutes for each kettle to boil, and all this time the hot water already added to the bath is cooling down. I started with a quantity of cold water already in the bath (to minimise the differential heat loss effect) and boiled two kettles in relay, switching on the next filled one before even pouring the previous one into the bath. To achieve a minimally useful depth of acceptably warm bath water took 30-40 minutes of this quite physically energetic process (depending on ambient temperature – it was winter). It also proved very expensive in terms of electricity bills – I ran up a deficit of several hundred pounds (sterling) which took me over a year to pay off.

If the OP is in a similar actual situation, I can advise a much easier and cheaper method which occurred to me eventually (being a dumb First-Worlder ). Boil one kettle of water and pour half of it into a basin by the bath (my handbasin actually overhangs my bath, which is ideal). Diluted with cold water to a comfortable temperature, this is ample to wet oneself down with a flannel while standing in the bath, soap and scrub, and perform one rinse. The second half, similarly cooled, then suffices for a second and definitive rinse.

One kettle's worth also proves ample for hair washing and rinsing with the aid of a pan while bent over the bath. I actually find this preferable to and more thorough than just lying in a bathful of water, though I admit the latter also has its attractions. It also steams up the bathroom much less, reducing any problems arising from condensation, like mould

In case anyone wants to raise the point: yes, installing a shower is in my long term plans. {The poster formerly known as 87.81.230.195) 2.218.13.204 (talk) 15:57, 6 April 2015 (UTC)

• In the big drought of 1976 we where advised to "Save Water, Bath With A Friend" If your friend don't like cold water and has a job – problem solved. You might even get a free back scrub. --Aspro (talk) 21:30, 6 April 2015 (UTC)

• The answer is that you need 80L of boiling water, then you let it cool to the temperature you like. I believe Lindert's equation might be wrong; I think you have to convert to Kelvin first. μηδείς (talk) 02:07, 7 April 2015 (UTC)

• No, it's the temperature differences that matter, not the absolute temperatures, so any units can be used, as long as they are used consistently. StuRat (talk) 02:25, 7 April 2015 (UTC)

Some points:

1) If you have a helper, they can add kettles of hot water while you bathe. You can start bathing with a small amount of water, and continue bathing as that water cools and more hot water is added. Of course, the helper has to be careful to add the water on the far end of the tub so as not to burn you.

2) Bubble bath seems to help to keep the water warm, by providing an insulating blanket of foam.

3) The room temperature also matters, both because the bathwater will cool faster in a cold room, and because it will feel colder, even the water is the same temperature. StuRat (talk) 02:30, 7 April 2015 (UTC)

April 6

Electric bath warmer

Would warming a bath with this product actually work and would it be safe? How long might it take to warm an 80L bath to 40c? 108.192.136.193 (talk) 00:34, 6 April 2015 (UTC)

Note: The image linked shows an immersion heater. -- ToE 09:32, 6 April 2015 (UTC)

We are in no position to answer questions regarding electrical safety based on nothing but a photograph - though I very much doubt that such a device would be compatible with electrical safety regulations in most countries if used in such manner. Even ignoring the obvious risks of electrocution, anything that small capable of heating a bath full of water is going to present a significant risk of burns. In short, we can't answer your question, and even if we could, the only answer we could legitimately give is "don't even think about trying it". AndyTheGrump (talk) 03:41, 6 April 2015 (UTC)

With the caveats mentioned by AndyTheGrump above, my guess would be that, in a cold room, the bath of water would lose heat faster than that device could add it, so it would never reach 40C. In the distant past, I have heated a bath with a higher power immersion heater, and it worked, but it was a very dangerous thing to do and I now have more sense (I think). Dbfirs 07:20, 6 April 2015 (UTC)

Those are designed for heating a cup of cold water to about 80-90°C (175-195°F) for coffee/tea etc. Assuming no losses for all these calculations, we get: To heat 300 millilitres (10 US fl oz) from 10°C to 90°C requires about 100kJ of energy, to do so in 1 minute requires 1.7kW of power. To heat 50litres (about half a bathfull, before you get in( of water by 30°C (from 10°C to 40°C) requires 6,300kJ. At 1.7kW, that's just over 1 hour, so even without any losses to the air, it's impracticable. LongHairedFop (talk) 08:32, 6 April 2015 (UTC)

I doubt it's actually as high as 1.7kW. This one, for example, is just 300W.--Phil Holmes (talk) 12:06, 6 April 2015 (UTC)

Yes, 1 minute sounds very fast to boil a cup of water, I believe a powerful microwave can do it in about a minute, but I wouldn't be surprised if one of those old immersion heaters took 3 or 4 miunutes to boil a cup.Vespine (talk) 00:19, 7 April 2015 (UTC)

I've never used one, so the time of 1 minute was picked at semi-random. The one in Electric_heating#Immersion_heater is indicated at 500W. Anyway, a 300W unit will take about 3hrs to heat a bath, assuming no losses. — Preceding unsigned comment added by 62.56.48.4 (talk) 09:31, 7 April 2015 (UTC)

regrowing fingers

How come my skin regrows when it gets cut and my bones regrow when they break, but my chopped off finger won't grow back? — Preceding unsigned comment added by 219.137.229.2 (talk) 00:56, 6 April 2015 (UTC)

Misplaced Pages has an article titled Regeneration in humans. I suggest you read that article, and then read any bluelinks from that article, to see where it takes you in your research. --Jayron32 01:00, 6 April 2015 (UTC)

That's a bit beyond my mental abilities. Can you just tell me? Thanks! — Preceding unsigned comment added by 219.137.229.2 (talk) 01:06, 6 April 2015 (UTC)

Healing vs. regeneration. Different processes. ←Baseball Bugs carrots→ 02:46, 6 April 2015 (UTC)

From what I found it appears that there really is not an answer to this question as of yet. There have actually been documented cases in an article from nature.com it is documented that some children have been known to regrow fingertips and some adults have even grown back parts of their liver. We have the ability when we are in the womb, humans are built piece by piece simply because we have stem cells by the time we are born our cells turn into adult somatic cells. Other animals still have stem cells even in adulthood . According to NUI-Galway’s Frank's research there may be two main reasons of human's lack of regenerative abilities. First if an amphibian loses a limb it can hide and regenerate without the need for food, this is simply not an option for a mammal with a fast metabolism that must eat, thus a mammal must regenerate "quick, and dirtily" . Professor Galway states “Because these (embryonic-like stem) cells are so versatile, it is difficult to keep them under control,” Frank explains. “They are more likely to ‘misbehave' or form tumors than differentiated cells. We hypothesize that only animals that have very simple body plans, like Hydractinia, can manage this problem because they have less complex organs and 'misbehaving' cells are less of a problem. But complex animals, like humans, need better control of their cells to maintain their highly complex organs. They have to get rid of them during early development before they become too complex.”) Lriverauk22 (talk) 03:40, 6 April 2015 (UTC)

References

1. (http://www.nature.com/nature/journal/v499/n7457/full/nature12214.html)
2. (http://news.discovery.com/human/evolution/why-cant-humans-regenerate-body-parts-130823.htm)
3. (http://www.remedi.ie/research/stem-cell-biology)
4. (http://news.discovery.com/human/evolution/why-cant-humans-regenerate-body-parts-1308231.htm

Note that an injury can be completely healed if the wound is small. That is, new skin or bone can be grown. However, if the injury is larger, then you get scar tissue instead, which isn't as good (less flexible, for one thing), but seems to be necessary to plug the wound quickly, to avoid infection in the case of skin, or allow the use of the leg in the case of a broken femur, etc. In the womb there's little risk of infection and the bones don't need to be used, so there's plenty of time to grow new body parts. Not so on the outside. (The obvious solution would be to use scar tissue to quickly plug the wound, then slowly replace the scar tissue with new skin, bone, etc., but evolution doesn't seem to have figured out how to do that yet.) StuRat (talk) 06:19, 6 April 2015 (UTC)

That sort of language is very misleading - evolution doesn't "figure anything out". It is a simple process of selection where random changes that confer an advantage for survival are passed on and those that don't confer an advantage tend to die out. Richerman (talk) 09:47, 6 April 2015 (UTC)

Yes, I was obviously anthropomorphising it, for comic effect. StuRat (talk) 20:50, 6 April 2015 (UTC)

Evolution does "figure things out" in a way. It's just that it's via non-conscious trial and error. Or as the saying goes, "Nature finds a way." ←Baseball Bugs carrots→ 22:09, 6 April 2015 (UTC)

Turning into a skeleton

After a person is buried in a coffin how long does it take for them to turn into a skeleton? 212.47.240.157 (talk) 03:18, 6 April 2015 (UTC)

After being buried 6 feet underground it takes about 10-15 years according to two of three sources I found with one source saying it could take up to 50 years but that is an extreme outlier and it highly depends on what the coffin is made out of. The 50 year process is common in those that are made out of solid oak.

Here are links to sourcing for this answer. http://www.enkicharity.com/how-long-does-it-take-for-a-body-to-decompose.html http://www.theguardian.com/lifeandstyle/2008/feb/16/healthandwellbeing.weekend2 http://www.memorialpages.co.uk/articles/decomposition.php — Preceding unsigned comment added by Trivle (talk • contribs) 03:47, 6 April 2015 (UTC) Trivle (talk) 03:53, 6 April 2015 (UTC)

Depends on the pH of the soil that the coffin is buried in. Sarcophagus means "flesh-eating"'. Being alkali, the flesh decomposes very quickly. In acid conditions (such as Bog Bodies) the flesh can last millennia. My mother-in-law has pickled herself in gin and tonic and martinis so still looks 21 (cough, cough)--Aspro (talk) 21:48, 6 April 2015 (UTC)

I wish I could tell you how old that joke is. :) Now, these questions are about below-ground burials. Wouldn't the concrete vault stave off that process? Also, wouldn't an above-ground crypt also stave off that process? I recall they disinterred Zach Taylor's body a few years back, and even after 100 years they were able to do something resembling an autopsy. ←Baseball Bugs carrots→ 22:07, 6 April 2015 (UTC)

• You need to ask that as a separate question. I.e., other forms of interment as opposed to ground burials as the OP asks about. --Aspro (talk) 22:39, 6 April 2015 (UTC)

• Does the OP's question include underground burial vaults, which are standard in the US? ←Baseball Bugs carrots→ 23:42, 6 April 2015 (UTC)

Only the OP knows this but I take his question as to being buried in soil rather than being interned in a crypt or catacomb etc., were other conditions can exist, such as humidity/temperature and lead-lined/butyl rubber lined/wooden/stone/steel, etc., coffins maybe used. --Aspro (talk) 14:26, 7 April 2015 (UTC)

Our article about Incorruptibility may be of interest. Richerman (talk) 23:57, 6 April 2015 (UTC)

"Physicist's guide to life" book?

I'm trying to recall a very good book I read a few years ago by a physicist who seemed to have a very good head on his or her shoulders and a great sense of humour. There were chapters on different themes; I think one might have been about nuclear power and another was definitely about nutrition. Some advice I remember in the nutrition chapter was something like "the best physical exercise for losing weight is pushing food away from yourself at the table". Please, what was this book? I hope somebody recognizes it. Hayttom 04:26, 6 April 2015 (UTC) — Preceding unsigned comment added by Hayttom (talk • contribs)

Did I do something wrong? My question seems to have landed in the middle of the previous answer. Hayttom 04:30, 6 April 2015 (UTC) — Preceding unsigned comment added by Hayttom (talk • contribs)

• The error wasn't yours, it was Lriverauk22's when responding to the #regrowing fingers question. Auk added a number of references using <ref> tags, the same way they might do in an article. But by itself this would produce reference footnotes at the bottom of the whole page (I believe the RD pages are set up to do that; otherwise the footnotes might go nowhere). So each time a new question section was added (including yours), the references got separated farther and farther from the section they belonged to. On the RD and similar talk pages, if you use <ref>, you also need to add {{reflist-talk}} (or {{reflist}}, for a different format) below your contribution, so the reference footnotes stay inside the section. See Template:reflist-talk. It was Dismas who saw what had happened and added the missing template, moving the footnotes up where they belong. Thanks, Dismas. --65.95.176.148 (talk) 18:19, 6 April 2015 (UTC)

Do any of these ring a bell ? I believe Physics for Future Presidents includes both nuclear power and dieting, though I don't know if it matches your themes exactly. Dragons flight (talk) 05:58, 6 April 2015 (UTC)

That was quick ... yes, thanks, it was "Physics for Future Presidents: The Science Behind the Headlines". Hayttom 11:30, 6 April 2015 (UTC)

Our links: Physics for Future Presidents by Richard A. Muller -- ToE 18:40, 6 April 2015 (UTC)

Maybe something by Richard Feynman. Richard Avery (talk) 07:07, 6 April 2015 (UTC)

sleep deprivation

It is stated that sleep deprivation leads to madness and eventually death. However coma patients survive sometimes years in the coma but not sleeping. Can you explain? — Preceding unsigned comment added by KrikvsPicard1969 (talk • contribs) 11:34, 6 April 2015 (UTC)

Have you read Coma? ←Baseball Bugs carrots→ 11:59, 6 April 2015 (UTC)

Are you saying that sleeping and comas are basically the same thing except that coma patients don't wake up in the morning? KrikvsPicard1969 (talk) 12:03, 6 April 2015 (UTC)

It's a different type of sleep, as noted in the article. What you're thinking about is being forced to stay awake, as a form of torture; or in the extreme case, the inability to fall asleep at all, which is called familial fatal insomnia. ←Baseball Bugs carrots→ 12:19, 6 April 2015 (UTC)

• Let me summarize -- the following information is in the coma article but might be hard to extract. The word "coma" is widely misused in the popular literature to encompass two distinct states, which doctors call (1) true coma, and (2) persistent vegetative states. Patients never survive for years in a state of true coma -- rarely longer than a few weeks, after which the patient either deteriorates or else progresses to a vegetative state. A patient in a vegetative state can survive for years. In true coma there is no genuine sleep, but in a vegetative state sleep-wake cycles are usually present. Bottom line: those patients who survive for years are not in a coma, they are in a vegetative state, and they do generally have sleep cycles. Looie496 (talk) 18:04, 6 April 2015 (UTC)

• It's worth noting that insomnia does not, in itself, usually result in death, outside of a handful of isolated and poorly-understood cases concerning the condition which bugs linked to. That's not to say that persistent insomnia is in any way pleasant; after even a single day without sleep, cognitive function takes a dive and after a few days you're looking at serious neurological impairment affecting everything from hormone balance to social capability. Before a week, the physical and cognitive state is not far removed from catatonia. But even at its worst, insomnia is unlikely to result in death, unless it compounds upon another issue (say hypertension or heart disease). Those who are said (in the relevant scientific literature) to have died from insomnia belong to just a handful of families who have been afflicted with the (and the wording is ironic but appropriate) nightmarish genetic condition FFI, and have had little or no sleep for years on end before their bodies finally collapse under the strain. This documentary may be of interest to you. Snow 23:41, 6 April 2015 (UTC)

Losing weight

If a person eats less and then feels hungry, is that the optimum time to begin exercise as the body is forced to draw upon fat stores rather than food in the belly? — Preceding unsigned comment added by 212.231.208.217 (talk) 17:01, 6 April 2015 (UTC)

Not necessarily. The truth is, you're likely to get a huge variety of answers to this inquiry, as this has long been an area of some controversy in the areas of nutrition and exercise physiology, with perspectives all over the place. While it's true that the exerciser's body will need to secure that energy from somewhere in its metabolic stores, it will not necessarily tap adipose tissue in order to do so, so the net effect upon both overall weight and the maintenance of muscle tissue (which might otherwise itself help keep down weight) could be poor. Again, advice is all over the place on this issue, but the most common perspective is to eat a typical meal about an hour before exercise and then a light snack shortly after; if one is looking to maintain their current weight the amount eaten should be roughly equivalent to that burned; if weight loss is the goal, slightly less should be eaten, but one should typically not go hungry into an intensive workout routine. Needless to say, if you personally are considering a new nutritional/exercise regimen, a consult with a physician is invaluable and (if you're inclined) they can always direct you towards a dietician or other nutritional expert. (, , , , , ) Snow 00:04, 7 April 2015 (UTC)

Weight = energy in vs energy out, it's actually not much more complex than that, despite the million self help and diet books that will try to convince you otherwise. The food in your stomach didn't magically 'disappear' becuase you didn't burn it up with exercise at the time. Put another way, if you exercise with food in your stomach, you won't be using up some portion of energy that you would otherwise 'poo' out or something if you didn't "use" it. The enegy from the food you ate will get used, whether you exercise or not, if you exercise you might burn more of it up, if you don't you'll store it, then you'll burn it later. Having said that, I do believe the general recommendation is to eat after exercise not before, but that's as much a practical consideration: exercising on a full stomach is not so comfortable and exercising does make you hungry so it makes sense to eat afterwards. Vespine (talk) 00:13, 7 April 2015 (UTC)

Of course, all of this is relative to general context. Obviously performance athletes and their support teams approach bio-energetics in a much more structured fashion, timing for exact amounts of macronutrients for very specific times, relative to exercise (and correspondingly, exercise timed relative to the metabolic cycle). Snow 02:26, 7 April 2015 (UTC)

The "energy in minus energy out = weight gain" is only going to be useful when you are way too heavy, say you weigh 110 kg while you should weight 75 kg. In that case, you should practice calorie restriction. Some exercise is then also recommended, but if you are that obese you are not physically fit enough to do strenous exercise. Exercise when you are not physically fit isn't going to burn a lot of calories, but being active like walking around will contribute quite a lot as you can keep that up for many hours. Simply walking around will burn 60 Kcal per hour more compared to sitting. So, if you do that for ten hours per day (take a standing desk instead of a normal one) you'll burn 600 Kcal more which is quite significant.

It's a totally different story if you your problem is that you weigh, say 82 kg while you want to weigh 75 kg and you notice that you do lose weight when you diet but when you are at your desired weight you tend to gain weight. In that case, the emphasis should not be on the diet but on physical fitness. You should gradually increase the exercise intensity, duration and frequency which will have the effect of increasing your basal metabolic rate. And this means that you should actually increase your calorie intake as you become fitter and are exercising harder. You must then make sure that your diet only contains healthy foods. If you were to diet and restrict calories then that would make it more difficult for your muscles to grow larger. The goal now is to have a steady state situation where you burn more calories at the same weight, which means that you must also eat more calories. You should do a combination of cardio and strength training, you could follow a program like this one. Count Iblis (talk) 05:29, 7 April 2015 (UTC)

The "energy in minus energy out = weight gain" is only going to be useful when you are way too heavy. I disagree, I don't see any reason why that would be the case. It's simply conservation of mass. One thing many people find surprising is that when you "lose weight" you aren't "converting fat into enerty", or digesting it and pooping it out, you are actually EXHALING it. The majority of weight is lost out of your front hole via carbon dioxide, not your back hole :). When you eat, energy goes in, when you exercise energy comes out: if more energy goes in you will gain weight, if more energy comes out you will lose weight, if they are roughly equal you will stay the same weight. It's really NOT much more complicated than that. Vespine (talk) 23:56, 7 April 2015 (UTC)

Agreed. Conservation of mass / energy is basically the only factor ultimately affecting weight. However, it isn't the only factor affecting overall health. Compared to a sedentary lifestyle, regular exercise will generally improve fitness and overall health regardless of weight. That's one reason to prefer a combination of diet and exercise in most recommendations for improving overall health. Dragons flight (talk) 00:29, 8 April 2015 (UTC)

Thing is that the basal metabolic rate is regulated by hormones. The precise mechanisms are not fully understood, but what should be clear is that evolution over hundreds of millions of years is unlikely to have led to a system with obvious flaws. Suppose an animal would need to expend a bit more energy to get to its food source and that food source would yield just a little less energy. If that negative energy balance, however small, would not be neutralized, that animal would eventually starve to death. E.g. if you eat one dry sandwich of, say, 80 Kcal less per day, and your body would not compensate for that, then this would become a deficit of 8000 Kcal in 100 days which would yield 1 kg weight loss. This means that you would lose 100 kg of weight in 27 years time. Obviously the metabolic rate will simply be adjusted to prevent this from happening. But this then also means that you shouldn't gain weight if you eat a bit more.

What goes wrong in people who need to diet to keep their weight from increasing is that they operate their bodies so far out of its design parameters that the feedback mechanisms that would normally keep the weight constant don't work well enough. If you exercise hard enough then the body will take care of its own weight. Count Iblis (talk) 03:06, 8 April 2015 (UTC)

Addiction

How do people get addicted to non-addictive things like gardening, knuckle cracking, or watching porn? Obviously I understand how people get addicted to marijuana and other substances because it is a drug. — Preceding unsigned comment added by Arduino12345 (talk • contribs) 19:53, 6 April 2015 (UTC)

"The term addiction is also sometimes applied to compulsions that are not substance-related," - Addiction#Behavioral_addiction, we have articles on Behavioral_addiction and Addictive_behavior. The term "addiction" is also often used sloppily, see e.g. Addictive_behavior#Compulsion_vs_addiction and compulsion for some related things. SemanticMantis (talk) 20:18, 6 April 2015 (UTC)

With things like gardening, knuckle cracking, or watching porn, people grow a need to do these things because it provides them some sort of pleasure. This is because when one uses drugs or do activities they enjoy, it elevates the levels of dopamine in the brain increasing the level of pleasure you receive from the action. This even happens when you get good grades, so because those activities you mentioned would bring pleasure to the people doing them they are more likely to continue doing those activities because it provides a euphoric feeling to them.

Here are some sources with information on this topic: http://content.time.com/time/magazine/article/0,9171,986282,00.html http://www.helpguide.org/harvard/how-addiction-hijacks-the-brain.htm http://www.peele.net/lib/diseasing6.html BHope95 (talk) 20:39, 6 April 2015 (UTC)

I suffer from Trichotillomania and can tell you there is no "pleasure" involved, it's very annoying.. Vespine (talk) 00:04, 7 April 2015 (UTC)

Have you tried shaving your head? ←Baseball Bugs carrots→ 02:03, 7 April 2015 (UTC)

Come on, Bugs, seriously, what's the point of this? Vespine presumably shared their condition in order to illustrate an important distinction between different types of compulsion, not to invite obvious lifestyle suggestions made as if they were a complete simpleton. Seriously, what kind of response were you expecting here? "Shay-veeng? What is this Shay-veeng you speak of"? I'm half surprised you didn't wikilink shaving. Snow 04:24, 7 April 2015 (UTC)

Very prescient of you Snow. For the record, 1) It's not on my head, it's actually my beard and 2) shaving does not help; You can't shave off every single ingrown, stubble, bump, pimple and even if you could by the afternoon there would be more than anough to continue. There's never a shortage of something on my face or neck to inadvertently pick at. It started about 8 years ago when I quit smoking, and now I'm pushing 40, so I do not fit the typical trich profile. It's not quite so bad that I need medication for it, but I have seen a few doctors who have suggested a few things that have so far not worked. I have not yet tried hypno or "proper" behavioral therapy. I did not intend to hijack this thread, I'm thinking that maybe admitting and "confessing" my problem might help with my continuing struggle to stop doing it, I suspect at least it won't hurt.. :) Vespine (talk) 04:58, 7 April 2015 (UTC)

My question was sincere, and I see from what you're saying that someone with that compulsion will find a way. It's often said that when you stop one addiction you substitute another. ←Baseball Bugs carrots→ 05:46, 7 April 2015 (UTC)

Not to put too fine a point on it, but not all habits are addictions. I have a habit of drumming my fingers (and, over the course of a lifetime, I've become quite adept at producing very complex and rapid rhythms using only the five fingers of one hand). It's a nervous habit which would be very difficult to stop, but I don't think any professional would call it an addiction. I think the same applies to knuckle-cracking. ―Mandruss ☎ 05:59, 7 April 2015 (UTC)

Well, except that there is some (disputed) evidence that popping of the joints can cause long-term degradation of musculo-skeletal strength. And as the distinction that you seem to be making is based on genuine harm done, that is minimally relevant. Snow 06:09, 7 April 2015 (UTC)

Yes, my lay person test for addiction (and one that at least approximates that used by a large number of professionals) goes as follows. Is it causing significant harm to your life or the lives of others? Is it impossible to stop without being forced to, despite knowing that? If both are yes, it's an addiction. ―Mandruss ☎ 06:16, 7 April 2015 (UTC)

Can an animal genetically engineer itself?

I've been reading about some of the techniques used in genetic engineering, such as Electroporation, Sonoporation, and Vector (molecular biology); and I was wondering whether it would be possible for an animal to use any or these or other methods to introduce it's own DNA into foreign cells that are within it's body. The article for electroporation says hundreds of volts are normally used to introduce new DNA into cells a few millimeters away; however electric eels produce 600 volts of electricity . The Emerald sea slug has genes from an algae that it passes on to it's descendants . Bullets and Bracelets (talk) 21:35, 6 April 2015 (UTC)

Yes, in fact it happens all the time, it's called Horizontal gene transfer. Vespine (talk) 23:01, 6 April 2015 (UTC)

Remember, eels aren't designed to shock themselves, especially internally. They're relatively shock resistant, ensuring electricity will take the easiest path, so even if they wanted to electroporate, I don't think they could. A lot goes into the process beside voltage. I doubt an eel has the brainpower to even begin wanting to actively try.

If the right lightning bolt hit the right river at the right time, maybe something would accidentally fuse, but I'm no expert. InedibleHulk (talk) 23:54, April 6, 2015 (UTC)

Tardigrades are supposed to be pretty good at repairing genetic damage to themselves, if that counts. ←Baseball Bugs carrots→ 18:25, 7 April 2015 (UTC)

Part moss, part piglet. Not bad! InedibleHulk (talk) 18:33, April 7, 2015 (UTC)

April 7

microwave

If you push your face against the door of a microwave to watch the food going around inside, how much dose of radiation do you get? — Preceding unsigned comment added by Coosquirt3 (talk • contribs) 00:53, 7 April 2015 (UTC)

Literally nothing, if you mean ionizing radiation, which is the stuff that causes real issues. Microwave ovens do not produce ionizing radiation, which is what causes cancer and radiation sickness and stuff like that. Microwaves emit a high-energy form of radio waves, not much different from the signal that is picked up by your TV set if you receive an over-the-air broadcast. According to this, the average microwave oven "leaks" about 2 milliwatts per square centimeter at a distance of 2 inches from the glass over the whole lifetime of the microwave total. Assuming a microwave lasts ten years, 2 milliwatts per square centimeter per decade is basically next to nothing. --Jayron32 01:09, 7 April 2015 (UTC)

Your response is susceptible to a misunderstanding. Milliwatts are units of energy flux, not total energy. The meaning of the FDA standard is that the flux (i.e., rate of energy leakage) can't increase beyond a certain limit (5 mW /cm2) as the oven gets older. This is not necessarily related to the accumulated flux over time, which would be measured in joules per unit area. Short Brigade Harvester Boris (talk) 01:31, 7 April 2015 (UTC)

Yes, microwaves are designed to be safe. The glass door has a mesh that prevents leakage of sufficient microwave radiation to cook your eyeballs, but I wouldn't recommend spending many minutes with your eyes pressed against the glass, just in case ... Dbfirs 09:15, 7 April 2015 (UTC)

I suppose that in cases of microwaves all been depended on by ionizer (radiator) of microwaves.--85.141.239.195 (talk) 15:47, 7 April 2015 (UTC)

No. Again, ten times no. Microwaves do not ionize anything. Microwaves are not ionizing radiation. Microwaves do not do to your cells what things like X-rays and gamma rays do. --Jayron32 16:45, 7 April 2015 (UTC)

Thanks. I’m thought, that a configurations of ionizer (radiator) of microwaves are been determine.--83.237.194.163 (talk) 17:39, 7 April 2015 (UTC)

Are not been. But when you press your eyeballs against the glass, you really see light waves that aren't really there. No harm staring at water to see what are been later, but if microwaved first, you be not seen again. Like been atomic and hydrogen bomb, but not really leave shadows that aren't really there. InedibleHulk (talk) 18:21, April 7, 2015 (UTC)

Sitting in front of old TVs can also burn shadows, but only on TV. InedibleHulk (talk) 18:27, April 7, 2015 (UTC)

Did geometry is been determine too?--83.237.197.142 (talk) 18:57, 7 April 2015 (UTC)

Of course. If trajectory is been known, you drop rectangle at bisection point. If rectangle area is been greater than or equal to face and volume is been beating ballistic limit, harm is been undone. If not, face melt. InedibleHulk (talk) 19:26, April 7, 2015 (UTC)

How long do LED, CFL, etc bulbs stay "on"?

LED and CFL bulbs cut on and off 60 times per second right (on US A/C). How long do they stay on in each cycle?

Yesterday I took three photos that included a street lamp. The exposure time was 1/400 second. In two of the photos, the street lamp was very dim but in the third it was brighter than I remember it being.

So how does the light output of modern bulbs vary across one cycle of A/C? Bubba73 03:20, 7 April 2015 (UTC)

I don't know, but I do know that "60 times per second" is wrong unless the light is only on when the AC current is flowing one way and not the other way. Any such flicker should normally be at 120 times per second. --65.95.176.148 (talk) 03:27, 7 April 2015 (UTC)

You are right - if it flickers, it should be 120 times per second (US A/C). Bubba73 03:51, 7 April 2015 (UTC)

An LED may not flicker in both directions. Current tends to only easily flow in one direction through a diode. I'd think that'd keep them at 60 Hz. --OuroborosCobra (talk) 03:57, 7 April 2015 (UTC)

Ah, that D does stand for "diode", doesn't it? Good point. (But see Z-man's response just below.)--65.95.176.148 (talk) 18:27, 7 April 2015 (UTC)

Most modern fluorescent lights use an electronic ballast that changes the frequency to to something on the order of tens of kHz. LED bulbs don't turn off and on at all. They use a rectifier to supply the actual LED with DC. Any flicker is just a result of the driver circuitry not smoothing the output very well. Mr.Z-man 04:07, 7 April 2015 (UTC)

Bet me to it, even cheap LED bulbs will have a rectifier circuit in them, I have actually used them as a cheap source of 12v rectifiers for other projects. Vespine (talk) 04:22, 7 April 2015 (UTC)

I've added cropped versions of three photos that I took the other day within seconds of each other. I didn't notice any change in brightness. They were all taken in aperture priority, ISO 100, f/8. (the first one was at a focal length of 60mm, the next two were at 70mm.) The camera exposed the first and third for 1/320 second and the second one for 1/400 second. Yet, the second one is brighter, even though its exposure was shorter. Why? Bubba73 05:14, 7 April 2015 (UTC)

The lamp in question could very well be flickering, that would explain the different brightness. We're making a lot of assumptions. MY guess is that it isn't an LED lamp, but have no good guess as to what it is. I suppose some sort of fluro makes the most sense. Could you take some more photos, maybe manually set the exposure to 1000th and see what it looks like? also take some photos of OTHER lamps in the area, in case the one you picked just happened to have a faulty driver perhaps flickering because it's "on the way out"? That's probably unlikely, but might be worth eliminating as a factor. Vespine (talk) 06:51, 7 April 2015 (UTC)

Flickering fluorescent lights are a fairly well known problem in photography. See here for example. Modern DSLRs can include anti-flicker circuitry. Check out the review of the Canon 7d Mk II at the same site for a description of it in action.--Phil Holmes (talk) 10:05, 7 April 2015 (UTC)

My camera (Nikon D7100) as the anti-flicker and I have it on. However, the lamp is only a small portion of the entire photograph, so it may not have picked it up. Bubba73 15:24, 7 April 2015 (UTC)

I would like more info on this. The OP asks about LED, CFL, etc. These photos look like one of the 'etc' bulbs. I.e., common incandescent. What color balance did you use (AWB?)(and there are sky clouds clearly visible behind so me thinks AWB) ... its reddish, so not a LED nor fluorescent. Its light flux is just varying 120 times per second. --Aspro (talk) 15:12, 7 April 2015 (UTC)

Yes, I did have auto white balance on, and it was set to normal. Bubba73 15:24, 7 April 2015 (UTC)

In my WP:OR, it is rather hard to get two identical photos, even with a tripod, with a modern digital camera on "auto/normal" modes. The white balance, autofocus, and lots of other factors conspire such that even in controlled situations where you know the subject and light haven't changed, the photos can still look rather different. SemanticMantis (talk) 15:42, 7 April 2015 (UTC)

It wasn't in auto/normal mode. Bubba73 17:55, 7 April 2015 (UTC)

Forgetting the specific terminology of your camera, I just meant this - "Yes, I did have auto white balance on, and it was set to normal" - that means the camera was making at least a few choices on your behalf, that may well change the apparent brightness in the photograph. SemanticMantis (talk) 18:06, 7 April 2015 (UTC)

Yellowish, street light? I would guess sodium-vapor lamp. I think these can flicker with the power cycle, though I'm not entirely sure. Dragons flight (talk) 17:42, 7 April 2015 (UTC)

I think sodium-vapor is most likely. Bubba73 17:58, 7 April 2015 (UTC)

Sodium-vapor lights can flicker: flicker. Bubba73 18:06, 7 April 2015 (UTC)

Modern medicine / human evolution

To what extent does modern medicine undermine natural selection in humans, thereby hindering human evolution? ―Mandruss ☎ 11:48, 7 April 2015 (UTC)

This is a hard question. We can't really do controlled experiments, and there's no generally applicable method of quantifying the "strength" or "speed" of evolution. Here's an article that discusses the problems with studying human evolution, and points to newer methods in genome studies and haplotype structure as a way forward , and here's a more recent article by some of the same authors: . The point is, these are relatively recent papers in Science and Nature, and we are a long way from having robust and widely accepted methods and results. A few things to keep in mind: Selective pressure will usually act the fastest when it acts at a life stage prior to sexual maturity. Now, some medical treatments save children that would have otherwise died without, but many medical treatments are applied to people who have already reproduced, or may never, and these don't have as strong of an effect. Here's an article that briefly mentions human impacts on human evolution, but it's mostly about human impacts on evolution in general . Now, there are some ways that pressures after reproductive age can influence evolution - notably kin selection and group selection. This recent work on orcas points out some similarities with humans - we are some of the few species where females survive and hang around after menopause. Now, humans did that before modern medicine, but it hints at how culture and sociology can influence evolution via mechanisms different from classical Darwinian selection. Finally, this book seems to have some discussion closely related to your question, but I have not read it. So - no real answers here, but lots of refs. SemanticMantis (talk) 15:02, 7 April 2015 (UTC)

There's also the false dichotomy between the natural and unnatural. Environmental pressures effects evolution. Period. Modern medicine is an environmental pressure which effects human evolution. Nothing else needs to be understood by introducing spurious ideas like "natural" and "unnatural". The question makes more sense if you merely asked "What sorts of evolutionary pressure is introduced to the human species by modern medicine?" --Jayron32 16:42, 7 April 2015 (UTC)

I agree with Jay. Selection pressures are changing, but they are not going away. So evolution will continue to do its thing. Consider moles - by digging underground they stop being preyed on by birds of prey - that means that that evolutionary pressure is reduced, but others come into play (less vision, better sense of smell, better sensing of vibrations, better burrowing). It's similar with humans - we can now treat some conditions that would previously be deadly, but that does not mean that all people have the same reproductive success. It's hard to tell which features currently are selected for, but that does not mean that none are. Richard Dawkins's The Extended Phenotype has some interesting ideas on the interaction of populations and how they modify and interact with their environment. --Stephan Schulz (talk) 16:54, 7 April 2015 (UTC)

• For a species with generation length as long as humans, selection pressure has to be sustained for thousands of years to have a significant impact. In far less time than that we will be able to engineer the human genome from top to bottom. So it really doesn't matter at all. Looie496 (talk) 17:21, 7 April 2015 (UTC)

I believe a better question would be: Is there any form of selection pressure in humans? Selection pressure would increase the likelihood that one set of humans would produce offspring while reducing the likelihood that another set of humans would produce offspring. Other than young death, I've only seen respectable studies linking lack of education and poverty to an increase in the number of offspring, but not to the likelihood of producing offspring. 209.149.113.89 (talk) 19:04, 7 April 2015 (UTC)

Sexual selection is a mechanism that evolved over hundreds of millions of years to keep evolution from going off the rails when for prolonged periods important selection mechanisms are absent. E.g. if prey animals live for many generations in an area where predators are absent, sexual attraction will still lead the fitter animals to contribute to the gene pool. Count Iblis (talk) 20:04, 7 April 2015 (UTC)

Sexual selection is of course a real thing, but for the rest of your claims, please. SemanticMantis (talk) 20:12, 7 April 2015 (UTC)

Well, it just seems logical to me that sexual attraction will, in general, have evolved to enhance the survival of the next generation. The article on sexual selection is a bit misleading because the evidence for sexual selection is most apparant in the rare cases where sexual preference leads to offspring with features that are of no benefit. This then leads to the evidence that sexual selection is a factor these cases, but of course, this is not how it works in general. Count Iblis (talk) 21:06, 7 April 2015 (UTC)

• Infectious disease is believed to be the greatest evolutionary force in humans, from sickle-cell anemia to smallpox, to cholera causing the evolution of multiple sclerosis. It has also been suggested that shortsightedness among the Chinese is linked to their long history of agriculture (where one need not spot and sneak up on the prey from a distance) and modern medicine has removed much of the burden of things like type-I diabetes and problematic childbirth, which will lead to people who otherwise wouldn't have survived to reproduce passing on problematic genes. μηδείς (talk) 20:21, 7 April 2015 (UTC)

My question was prompted by an earlier thread at WP:RDM, in which the issue of infant cranial size vs birth canal size was mentioned. I don't think there's any disputing that this problem has resulted in the deaths of many mothers (and infant girls), but far fewer after the development of relatively safe C-sections and other things. It seems intuitive that, without the interference of modern medicine, the problem would eventually correct itself. Aside from Looie496's point, which would render this purely academic, is there any validity to this? Is the idea that with modern medicine this should cease to be viewed as a "problem"? ―Mandruss ☎ 02:20, 8 April 2015 (UTC)

Engineering and design - constructional systems of the USSR

Are engineering and design - constructional systems of the USSR, including the civil and military army systems of the USSR being promising advanced (perfected) systems? I saw, many people told that engineering and design - constructional systems of the USSR, including the civil and military army systems of the USSR are not being perfected, because the USSR had not a advanced (perfected) computer.--85.141.239.195 (talk) 15:25, 7 April 2015 (UTC)

Every one of those words is English, and yet I can't understand what you say. Perhaps if you asked the question at the Misplaced Pages of your native language, you could be better understood? Just about every Misplaced Pages of any size has a place like the reference desk. If you tell us your native language, we can direct you better to a place where you can be understood by those trying to help you. --Jayron32 16:39, 7 April 2015 (UTC)

The USSR was losing in the Cold (nuclear) War, because the USSR had not a basis of applied programming. I’m sorry, but I had not got an education in applied programming, what’s why I was asking this question.--83.237.197.142 (talk) 18:19, 7 April 2015 (UTC)

Asking questions at a website where they understand your native language is more likely to get meaningful answers. AndyTheGrump (talk) 18:21, 7 April 2015 (UTC)

Thanks. I suppose that to become a winner in Cold (nuclear) War always must be had scientific skills, but not a finances or political reasons as biography of politics.--83.237.197.142 (talk) 18:53, 7 April 2015 (UTC)

I should edit, that I’m understood that Cold War was win the program linguistics of assembler, but what kind of symbiosis of assembler program linguistics did win, I’m don’t know.--83.237.197.142 (talk) 19:37, 7 April 2015 (UTC)

Is been lost USSR from dangerous ovens Cold (microwave) War? μηδείς (talk) 20:00, 7 April 2015 (UTC)

Nothing is ever perfected, I'd say; there are always compromises – between different requirements, or with the time available for the engineers to complete their task. The USSR had good computers, I believe, but they might not have been available to engineers on low-priority projects. —Tamfang (talk) 22:39, 7 April 2015 (UTC)

Flat loudspeakers

I would like to know something more about a series of big, flat loudspeakers manufactured by Yamaha some twenty years ago. They were blue with a black frame and marketed as "digital" (whatever they mean with that word). Designed mainly for theatres and similar places.--Carnby (talk) 16:58, 7 April 2015 (UTC)

If you would like to know about how these planar speakers work we have two articles: Magnetostatic loudspeaker & Electrostatic loudspeaker.--Aspro (talk) 21:57, 7 April 2015 (UTC)

Squeezing a very round head inside an oval helmet?

Is it safe to squeeze a very round head inside an oval helmet? Given an oval helmet on a very round head, will that protect the round-headed bicyclist from accidents? 140.254.136.149 (talk) 17:19, 7 April 2015 (UTC)

We have a pretty long article on Bicycle_helmets. I'm not sure what you are asking. There are a few different shapes and styles, but many of them are indeed just and oval shell that rides on top of the head. A good fit is important for a helmet to properly protect, see e.g. here . There shouldn't be any squeezing of heads required to wear a helmet. SemanticMantis (talk) 17:59, 7 April 2015 (UTC)

Some cyclists wear skateboard helmets like these , to give better protection to the sides of the head. But they are hotter and heavier, so each rider makes their own choices. Here are a few scientific studies on the effectiveness of using bicycle helmets to prevent injuries in crashes . From the first article " Risk of head injury in helmeted vs unhelmeted cyclists adjusted for age and motor vehicle involvement indicate a protective effect of 69% to 74%" -- short answer: helmets do help protect against head injuries. SemanticMantis (talk) 18:02, 7 April 2015 (UTC)

There was a recent ESPN Outside the Lines about hockey helmets and such. Helmets largely protect against skull fracture. They are much less reliable for protecting against concussions. ←Baseball Bugs carrots→ 18:22, 7 April 2015 (UTC)

Please be aware that for a cyclist that knows what they are doing, and is just commuting and not racing, a helmet is completely unnecessary (cf the Netherlands and Denmark), and will only put people of cycling. 82.21.7.184 (talk) 20:19, 7 April 2015 (UTC)

Yes, the Danish and the Dutch have it great, with their protected cycle superhighways, , and all sorts of other cycling-friendly infrastructure. In the USA however, cyclists " face a higher risk of crash-related injury and deaths than occupants of motor vehicles do" . WP:OR: Last weekend I saw a car intentionally knock down some cyclists in TX. Even in non-race situations, skilled cyclists can crash and get severely injured. I would probably not wear a helmet if I cycled in the Netherlands :) SemanticMantis (talk) 20:51, 7 April 2015 (UTC)

"Knowing what you're doing" is insufficient. Wearing a helmet is essential. ←Baseball Bugs carrots→ 22:11, 7 April 2015 (UTC)

colleges for message therapy

Is there any colleges have message therapy courses ? — Preceding unsigned comment added by 106.76.24.162 (talk) 17:40, 7 April 2015 (UTC)

I think you mean "massage therapy". There is a type of vocational school called "massage therapy school", where people come out as licensed/certified massage therapists. Legal massage therapists abide by the laws of the jurisdiction, which may or may not charge illegal services like erotic massages and prostitution. You may be interested in seeking a massage therapy school in your district. 140.254.136.149 (talk) 17:48, 7 April 2015 (UTC)

If you actually mean "message therapy", a course in business writing would be a good option. ←Baseball Bugs carrots→ 18:20, 7 April 2015 (UTC)

Discovering an asteroid

A century ago, how was it decided that one had discovered an asteroid? For example, when 284 Amalia was discovered, how did the discoverer know that it wasn't just another asteroid that had already been discovered by someone else? I understand that astronomical tables have been developed for planets and bigger objects, with precise orbits calculated and future locations accurately predicted, but was this routinely done for minor asteroids? Nyttend (talk) 17:59, 7 April 2015 (UTC)

The short answer is that yes they did plot the orbits of all the asteroids. The somewhat longer answer is that sometimes asteroids did get lost and rediscovered later. See: Lost asteroids. In general, if you know the orbit, you can calculate where something would have been in the past and then match early observations with modern ones, so sometimes people do rediscover previously lost asteroids. Dragons flight (talk) 18:08, 7 April 2015 (UTC)

Also, an orbit is characterized by its orbital elements. These are just a set of numbers and are easily compared to confirm that two bodies are in different orbits, provided that there's enough data for the orbital elements to be well established. (Different computations of the orbit for the same body may not produce exactly identical numbers, due to things like perturbations and minor observational errors, but the elements will be close enough to suggest when further investigation is required. That'd be the only case where you'd actually have to compute where the thing was at some particular time.) --65.95.176.148 (talk) 18:38, 7 April 2015 (UTC)

You can probably find the original paper on the topic, this search for Auguste_Charlois between the years of 1888 and 1905 gets plenty of hits. The articles are even freely available. But they do seem to be in French... This address titled "Asteroids past present and future" may also shed some light. SemanticMantis (talk) 18:16, 7 April 2015 (UTC)

Who realised that whales and dolphins are not fish?

See title. It doesn't seem very obvious. --82.45.61.67 (talk) 18:31, 7 April 2015 (UTC)

Aristotle said so in the 4th century BC, according to this book preface (7th page of the PDF). --65.95.176.148 (talk) 18:45, 7 April 2015 (UTC)

It is sort of obvious, when you consider pre-scuba people typically only saw whales coming up for air. Fish don't do that. The first time they killed one and realized it was filled with blubber would've also been a hint. InedibleHulk (talk) 18:49, April 7, 2015 (UTC)

Aristotle had it right, but not necessarily for the right reasons. Moby Dick contains a long passage on the subject, and concludes that dolphins must be fish. Here is what you should read: When Whales Became Mammals: The Scientific Journey of Cetaceans From Fish to Mammals in the History of Science -- it is a nice historical overview of cetacean taxonomy from a historical perspective: it starts with Aristotle, and continues through antiquity, Renaissance, and up to the modern day, detailing each new them in taxonomy and some of the morphological work that supports the claims. SemanticMantis (talk) 20:10, 7 April 2015 (UTC)

Amusingly, Misplaced Pages has an entire article on the cetology of Moby-Dick. Ishmael/Melville wasn't saying anything about cetacean biology when he said they ought to be fish. He was merely complaining about the over-narrow modern definition of "fish". -- BenRG (talk) 23:05, 7 April 2015 (UTC)

Can a human body creates toxins by itself?

Can a human body cell creates toxin by itself, or it must be done by bacteria and other foreign things? by the way, CO2 can be called "toxin"? Thanks. 5.28.178.16 (talk) 18:37, 7 April 2015 (UTC)

The human body produces many toxic waste products through natural metabolic processes. These need to be filtered out by the kidneys and then excreted. When the kidneys are not functioning properly, there can be serious health problems that result. Deli nk (talk) 18:41, 7 April 2015 (UTC)

"Methanol (wood alcohol), for instance, is oxidized to formaldehyde and then to the poisonous formic acid in the liver by alcohol dehydrogenase and formaldehyde dehydrogenase enzymes, respectively; accumulation of formic acid can lead to blindness or death." (See Alcohol#Toxicity). StuRat (talk) 18:57, 7 April 2015 (UTC)

For a simple example, see creatinine. This is produced in muscle cells and has to be excreted from the body. It is a very common toxin to be checked to see if the liver and kidneys are functioning well because the rate of creatinine production is fairly consistent throughout the day. 209.149.113.89 (talk) 18:56, 7 April 2015 (UTC)

Whether CO2 is toxic depends on its concentration. It is present in in small quantities in ordinary air and that doesn't injure anyone. But in high concentrations it is a dangerous toxin (not just an asphyxiant). See this page from the CDC and this PDF appendix from a US BLM document produced under their National Environmental Policy Act. --65.95.176.148 (talk) 18:57, 7 April 2015 (UTC)

• Relevant here is the adage the dose makes the poison. The idea is that almost anything is toxic (and almost anything is safe) depending on the amount present. While not 100% true (there's probably some substances toxic in any measurable amount), as noted with something like CO2, it absolutely depends on the dose. Also relevant is the quote The amount of times someone uses the word "Toxin" is inversely proportional to their actual knowledge of chemistry. The word "toxin" is a marketing term created by charlatans who want to sell you magic crystals and other new-age hokum. It really is a marker of a lack of science knowledge to use the term. --Jayron32 19:29, 7 April 2015 (UTC)

April 8

Material for heaviest bat possible

If I wanted to make the heaviest and most sturdy bat/club possible, what material or element should I use? (Even if it's not easily workable, though hopefully not too radioactive). CesarFelipe (talk) 02:52, 8 April 2015 (UTC)

Short answer, heavy does does not equal sturdy, so you would have to specify which you want. Others will be along with longer answers. ―Mandruss ☎ 03:00, 8 April 2015 (UTC)

Well, by "heaviest" I mean densest, and by "sturdiest" I mean "resistant to damage/breaking, i.e. not brittle". I've looked up a few materials that are very dense yet brittle, so I don't know if they would work for making a functional bat or not. CesarFelipe (talk) 03:07, 8 April 2015 (UTC)

Yeah, dense doesn't equal sturdy, either, so you still need to specify which you want. You can't be both densest and sturdiest in the same material. ―Mandruss ☎ 03:14, 8 April 2015 (UTC)

Anything that's really dense probably wouldn't make a functional bat, because you'd barely be able to lift it. Platinum is pretty dense and not brittle. An MLB-sized bat made out of it would be around 32 kg (and cost over a million dollars). Mr.Z-man 03:40, 8 April 2015 (UTC)

• Pages automatically checked for accidental language links
• Misplaced Pages resources for researchers
• Misplaced Pages help forums
• Misplaced Pages reference desk