Wikipedia:Reference desk/Science

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

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

Want a faster answer?

Main page: Help searching Wikipedia

   

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.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia: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.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

February 1

Unregistered SIM cards

Which countries still don't require people to register their prepaid SIM cards? --49.145.78.106 (talk) 04:46, 1 February 2014 (UTC)

Which countries do? HiLo48 (talk) 07:29, 1 February 2014 (UTC)

Certainly not in the UK. We bought a 'disposable' SIM card (with cash) to use while we were on vacation there back in December - it cost 50 UK pounds and had 50 pounds worth of pre-paid minutes & texts on it - and the whole process was completely anonymous. SteveBaker (talk) 14:19, 1 February 2014 (UTC)

@HiLo48: Which countries? Examples: Kenya, Malawi, Zambia, Uganda --49.147.165.12 (talk) 02:31, 3 February 2014 (UTC)

South Africa https://www.mtn.co.za/support/Pages/Rica.aspx 196.214.78.114 (talk) 10:18, 3 February 2014 (UTC)

I wonder whether these cards in the UK, Kenya, Malawi and so on are truly anonymous, or whether they require some form of activation like calling the number to be activated from a landline, which would leave a track to follow in case you decide to use the SIM for harassment, prank calls, drug dealing, or other criminal activity. Indeed, although they might be quite convenient for tourists, checking the ID of someone would just require 1 minute, and can avoid problems down the line. OsmanRF34 (talk) 13:00, 3 February 2014 (UTC)

It is rather unlikely that there is any such requirement for activation with anonymous prepaid systems: you arrive at an airport, and expect immediate activation of your newly purchased card. Even a landline is of little use, because it could be from the lobby of a hotel. And assuming that the telephone infrastructure leaves the sort of trace, and that it is readily accessible, is assuming NSA-like capabilities of third-world countries. It is also a misconception that registering numbers is a direct countermeasure to crime; it is not difficult to get a card that is registered in way way that does not connect it to the user. It seems more likely that the registration process is a way of simplifying traffic analysis where full traffic analysis is still beyond the capability of the authorities. I suspect that in countries with the capability of recording and analysing telephone traffic on an ongoing basis such as the UK and USA, individuals can be tracked far more reliably through analysis of the frequency of specific numbers called, even when they are not from the same phone. —Quondum 16:05, 3 February 2014 (UTC)

The SIM card I bought at a phone store at London Gatwick airport may well have needed some kind of registration - but that was all done by the guy behind the counter at the store - who didn't ask our names or require any sort of ID. Since we paid with cash - any kind of registration process could only have identified the store and/or it's owner. Of course, the airport is stuffed full of security camera - I'm quite sure that if someone in authority wanted to figure it out, they could have timed when the card was sold to the pictures of my wife and I standing at the store counter - then compared those images to people going through passport control and thereby figured out *exactly* who bought the phone card with that phone number associated with it. The incredible power of this kind of security surveillance is not in one single source of information - but in combining multiple sources - each of which is relatively innocuous.

Note also, that every phone has a unique number built into it - aside from the number on the SIM card and the actual phone number. That number can also be read from the cell tower - so just buying a 'disposable' SIM card isn't enough to ensure that you can't be tied to phone calls. You'd really need to buy a 'disposable' phone too. SteveBaker (talk) 19:23, 3 February 2014 (UTC)

store meat in vacuum?

A couple of sections up, I was reminded of a novel set in a city on the Moon. Expecting a large influx of refugees, the city slaughters most of its meat animals, to reduce competition for air and water. They can't eat all the meat right away, and haven't enough freezer space for all of it; but, I thought, what if the carcasses are stored outside? Obviously they'll dry out in a hurry (enough of a hurry to kill all bacteria?), but does that make the protein useless? Could it be used later for soup stock, say? —Tamfang (talk) 07:10, 1 February 2014 (UTC)

Lots of dried meat is eaten around the world see: Dried meat. It's just a case of preparing it properly - usually using salt to kill the bacteria. Richerman (talk) 08:34, 1 February 2014 (UTC)

The freezing would prevent bacterial problems - so you don't need the salt. Wrapping the meat tightly in plastic would certainly help to delay the onset of freezer burn in much the way that vacuum packing does. But in any case, freezer burn mostly only affects the surface of the meat - so entire cow carcasses would probably be unaffected - especially if the hide is left on it. SteveBaker (talk) 14:15, 1 February 2014 (UTC)

Note that anything outdoors on the moon will fluctuate between extremely cold and extremely hot, with a "day" lasting a month. The hot phase will do bad things to meat. Looie496 (talk) 16:31, 1 February 2014 (UTC)

Although some of the craters are in permanent shadow and extremely cold at the bottom [1] Richerman (talk) 17:18, 1 February 2014 (UTC)

Is sea star wasting syndrome the same thing as starfish wasting disease?

I've created an article for sea star wasting syndrome, which is currently in the news. Some searching revealed an already existing article starfish wasting disease. It looks like these might be about the same thing, but I don't know enough about marine biology to make the call. Are these the same? -- The Anome (talk) 11:19, 1 February 2014 (UTC)

They're the same thing. I saw a report on this problem on TV a few weeks ago. The terms "sea star" and "starfish" are synonyms. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:53, 1 February 2014 (UTC)

Thanks. I've added mergefrom/mergeto tags to the articles. -- The Anome (talk) 14:19, 1 February 2014 (UTC)

Dieting too quickly.

When dieting, it's frequently said that if you eat too little, your body will go into "starvation mode" in which your metabolism becomes more efficient - and it'll actually be harder to lose weight.

My question is for how long do you have to eat too little to produce this effect - and how long does the body take to go back to a normal metabolic rate when you resume eating more?

Some diets claim that skipping even a single meal is too much - where others suggest that you need to take a break from dieting every four to six months in order to avoid this effect!

Is there some scientific evidence for the onset, duration and magnitude of this effect? Is it even true?

SteveBaker (talk) 14:40, 1 February 2014 (UTC)

This study shows that fasting for 24 hours actually increases metabolic rate. Also check out this blog post which - using thyroid surrogate markers - suggests that going under 25kcal/kg lean BW/day (in combination with an exercise-induced 1300kcal/day deficit!) could decrease metabolic rate. Markr4 (talk) 17:33, 1 February 2014 (UTC)

Firstly, dieting really means: Latin diaeta, way of living, not food reduction. Simply reducing food intake can also reduce muscle mass as well as fat. The latter is not good. The body is sacrificing itself to make up for the shortfall of real nutrition (starvation mode). Dieting should really be about eating balanced diet where the body feels sated and not hungering for more, with all it needs have been satisfied. The high sugar and fat rich foods (like ice cream) that we like today, were unknown to out ancient ancestors. Modern prepossessed foods are very short on those other stuffs, that stops our bodies hungering for more. The packaging may have little bit printed on the back stating the fibre content etc as the amount recommend as a daily intake but add up the days consumption of all those printed bits and there is a lot missing. So the body is hungering in the hope of some real food to make up for that short full. The Paleolithic diet is odd to try at first, but it doesn't necessitate eating too little. Alas, it is also not a commercially viable wait-loss-plan that can be owned by any company, so it receives no commercial promotion.--Aspro (talk) 18:50, 1 February 2014 (UTC)

Well, to be fair, a real Paleolithic diet probably involved a lot of fasting, need it or not. :0 Wnt (talk) 03:53, 3 February 2014 (UTC)

True. In palaeolithic times and up to quite recently (on the evolution time scale) there were seasonal times of want. The homo-sapient has a metabolism to go into a acute starvation mode but that is different from a 'chronic' starvation mode as in modern dieting protocols . For instance, we can store up several months worth of ascorbic acid to see us over the winter. Swedish mothers used to encourage their children to run around naked in the spring sunshine (even though they did not have a notion about vitamin D) but cultural wisdom that got passed down from mother to daughter was proved right. A true palaeolithic diet in this sense, would harken back to the old wisdom of my grandmother's time, which was only eat foods that are in season. Now that one can buy Californian grown lettuces way up in Alaska in January, makes this true natural diet difficult, for as I admit, do like a good salad at any time of the year. So one has to aim for the median. If one is living up in (say) Caribou, Maine, then eating high fat foods (energy rich) during the winter keeps you warm. Yet for a Hispanic living down in the warm south and consuming high fat/sugar takeaways.... this is a recipe for diabetes, obesity and an early death.--Aspro (talk) 22:04, 3 February 2014 (UTC)

Aspro's claims about "nutrient deficiency" increasing appetite are common, but there isn't actually any evidence for it. It's more likely that foods like ice cream promote overindulgence because they taste nice. Markr4 (talk) 12:20, 3 February 2014 (UTC)

Yeah! Heroin an Smack make you feel nice to. What is your point? Micronutrient-rich diet's? I say you are allowing yourself to baffled by 'his' science. A good diet contains more. An mixture of protein, carbohydrates, fatty acids etc., as well as micronutiants and vitamins. Also, talk to a cattle farmer. He may mention Mineral lick. The cattle partake in them instinctively (cattle can't read health advice articles). If you have ever looked after livestock – you will see they go for what they need first. Cumulatively, that blows your sided Stephan Guyenet argument out of the water. --Aspro (talk) 21:59, 3 February 2014 (UTC)

What exactly is your claim? My understanding from your original reply was that: modern diets promote obesity via excessive caloric intake, this excessive intake occurs because the body is still hungry for the nutrients that are missing in junk food (e.g. fibre, protein, omega 3, ...). My dispute with this claim is that modern diets aren't actually lacking in any nutrient. You can still become obese eating a nutrient-rich diet if you just add in the junk food on top, but presumably you're claiming that if one eats a nutrient rich diet, one will not have an appetite for junk food such as ice cream? Please clarify. Markr4 (talk) 12:29, 4 February 2014 (UTC)

Yes, if one eats a nutrient rich diet, one will not have an appetite for junk food such as ice cream – it has no appeal. To try and eat junk food on top of a nutritious diet and it feels like force feeding and unappetizing. The important word here is Nutrient. Your quote:modern diets aren't actually lacking in any nutrient. Ah, but do they contain enough? E.g., Your automatic transmission may have a little fluid in it but if there is not enough your car what be going anywhere. The noise it makes means it hungers for more transmission fluid, adding more engine oil to the engine does not help this. Breeding the Nutrition Out of Our Food, The American Society for Clinical Nutrition: Origins and evolution of the Western diet: health implications for the 21st century. Nutritional Science seems to be on my side rather than uneducated opinion. Is that sufficient clarification? If not, please post as a separate question as it is getting off topic to the OP's question.--Aspro (talk) 19:52, 4 February 2014 (UTC)

Macrophages (and glucose, or glycation products)

I'm reading a textbook of mine and came across a claim during a discussion of how the body prevents glycation and cross-linking of proteins, that macrophages "seek out glucose molecules, engulf them, destroy them, and send them to the kidneys for elimination". I have never heard of this function of macrophages and questioned whether it was true, but cannot find any sources supporting this claim. Does anyone know if this actually happens? Brambleclawx 15:47, 1 February 2014 (UTC)

It's true in a sense but weirdly worded. Glucose is the fuel that macrophages primarily burn, so they do "engulf and destroy" them, but the more commonly used terms would be "uptake" and "metabolize". The products of glucose metabolism are CO2 and water -- the water is indeed sent to the kidneys for elimination, but this is again a weird way of putting it. Looie496 (talk) 16:27, 1 February 2014 (UTC)

Yeah, I was wondering if that was what they meant, but in that case, all cells that metabolize should have been mentioned. Brambleclawx 17:26, 1 February 2014 (UTC)

It seems they must have wanted to say "seeks out glycated molecules", otherwise they went to a lot of bother to say macrophages absorb sugar from blood plasma, and there'd be no point of saying anything was sent to the kidneys, unless they meant water. μηδείς (talk) 23:06, 1 February 2014 (UTC)

Yeah, I think they're looking for advanced glycation end-products with both hands and a flashlight. Wnt (talk) 01:54, 3 February 2014 (UTC)

Stiffest Material

Wich materiasl has the highest Bending stiffness? I want to ask cause it is realy interresting which material has the most highest stiffness or bending stiffness. cause you can make great things out of it and you have little weight but you dont have to make complaints out of it.Saludacymbals (talk) 17:49, 1 February 2014 (UTC)

You might want to read articles such as Young's modulus, Stiffness, Graphene and Carbon nanotube. You might not be looking to maximize some specific property, or you might find that many materials exist that surpass your expectations, and that other criteria (other properties and cost) might be significant. —Quondum 19:15, 1 February 2014 (UTC)

From the basic theory of bending, there are 2 important equations relating materials properties, loading, and geometry. The first important property is the Young's modulus. However, the yield strength is also important as the theory is only valid as long as the stress at all points remains below the yield stress. Which one is more important would depend on the geometry of your beam because, as they depend on factors like the second moment of area and how the load is distributed.

It's also only valid for pure bending (there are more complicated theories that can take more complicated loading into account). The geometry can also affect whether it will buckle before it will fail in bending.

And if you're making an actual object out of something, you also have to take brittleness into account. Many stiff materials are also brittle, which means if you do exceed the maximum load, it will shatter rather than bend in plastic deformation.

Many materials also exhibit anisotropic properties (properties that differ depending on direction). Rope is fairly stiff when pulled in tension but has virtually no bending stiffness because it's made up of fibers all oriented in one direction. So how you turn your raw material into a bar will also affect its bending strength.

The highest Young's modulus known is linear acetylenic carbon. However, all the calculations are theoretical based on quantum mechanics no one has actually been able to make more than a few molecules of it and it's not known how, or even if, it could be made into a bulk material.

Diamond is a distant second and could be used to make really small objects.

If you wanted to make something relatively big, the best choice is probably tungsten carbide. It's usually formed as a powder mixed with a softer metal like cobalt. But its melting point is "only" 2870 C, so casting it into a solid piece is difficult, but possible. Osmium has similar properties but at around US$100/gram (where 1 g is a 3.5 mm cube) it probably isn't very practical. Mr.Z-man 21:12, 1 February 2014 (UTC)

Yes. The stiffest materials such as diamond carbon nanotube are too exotic for commonly manufactured things and you may be more interested in materials with high strength-to-weight ratio. Consider the usefulness of balsa wood which weighs little but is used to construct a warplane, wind turbine blades or a sea-going raft because its Specific strength (see article) exceeds metals such as aluminium and brass. You may also be interested in Steel which inexpensive, recyclable and is not one but a wide range of different alloys 1 2 3 that can be selected not only for stiffness but also for their strength, hardness, toughness, wear resistance, corrosion resistance, Weldability, Ductility and hardenability. I don't understand what the OP means about complaints but suspect that Cymbal making may be another article of interest. 84.209.89.214 (talk) 21:18, 1 February 2014 (UTC)thanks for your kind information! but i only thought of the bending stiffness from a material in this case.Saludacymbals (talk) 21:43, 2 February 2014 (UTC)

February 2

Large body flying through the solar system.

Suppose a rogue planet with mass like that of Jupiter went thru the inner solar system at high enough speed to keep going and exit the solar system. Would it be true to say that, the higher the rogue planet's speed, the less disruption to orbits of planets like earth, mars and venus would be caused? Regardless, would orbits be severely deranged? thanks.76.218.104.210 (talk) 05:58, 2 February 2014 (UTC)

If it went perpendicular to the ecliptic and all the planets happened to be on the other side of the Sun, I suspect all it might do would be to permanently disrupt Earth's climate by altering its orbit, and cause mass extinctions by disrupting the asteroid belt, but s.o. would have to do the calculations. — kwami (talk) 06:57, 2 February 2014 (UTC)

Yes, in general, higher speed should mean less disruption. (Providing it doesn't actually hit anything that is!) Gravity is the only significant effect it would have. Gravity imparts an acceleration onto nearby object for as long as it's present - and the longer that acceleration goes on, the more velocities throughout the system are changed - and hence the more kinetic energy is transferred between the various bodies involved. So as a general observation, the amount of energy that it would "rearrange" throughout the system would be in proportion to the amount of time that it was nearby - so the higher the speed, the less time it's transferring energy and the less "disruption" there is. Of course a heck of a lot depends on when, where and in what direction this body was moving...and "disruption" is something of a fuzzy term...if all it did was drastically move the orbits of a few comets - then maybe we'd say that was considerably less "disruption" than (say) an 0.01% change in the Earth's orbital velocity - even if the energies involved were higher for the comets. SteveBaker (talk) 15:53, 2 February 2014 (UTC)

If you are really interested in stuff like this, you can try a gravity simulator like this one and see for yourself what happens. Not sure how easy it would be to set up a scenario like the one you describe, I personally haven’t played with one but I’ve heard it talked about in the context of a game I’ve started playing and it sounds like it should be possible. If not with the software I’ve linked, then with something similar. Vespine (talk) 02:50, 3 February 2014 (UTC)

The orbits may be temporarily disturbed, as the mass of the rogue planet nears the ecliptic (we'll assume the planet passes very close to the sun for simplification) the planets will "feel" more gravity and their orbits briefly contract, ever so slightly, but once the planet is far off, the planets would resume "feeling" the same gravitational force as before and settle back into their original orbits. I imagine the greatest effect would be to change the ellipticity of the planets' orbits.  — TimL • talk 09:10, 3 February 2014 (UTC)

No, that's off, TimL. The perturbed orbits would be under the influence of the original planets as well all the time, the effects of the acceleration they underwent due to the intruder would not simply disappear. There wouldn't be any further disruption by the intruder once it passed, but there are no preferred orbits to snap back to, and once in motion stays in motion. μηδείς (talk) 19:24, 3 February 2014 (UTC)

most ancient arrow poison

Hi,

I am trying to find reliable information on the most ancient arrow poison ever used (maybe from chemical analasys of ancient arrows found?). The article chemical warfare mentiones use of arrow poison by the San people 10000 years ago, but with no reference. I would appreciate any information. Thanks! 2.55.131.28 (talk) 07:15, 2 February 2014 (UTC)

The article on the San people mentions Diamphotoxin as the poison used. --Cookatoo.ergo.ZooM (talk) 10:13, 2 February 2014 (UTC)

yes, but since when? 2.55.127.242 (talk) 12:39, 2 February 2014 (UTC)

If you include biological warfare, dipping arrows in feces might go back much further. The people doing so wouldn't have needed to know about bacteria, or even that it would tend to cause the enemy to become infected. They might have done so just as a way to humiliate the enemy. StuRat (talk) 18:36, 2 February 2014 (UTC)

• I am curious whether there might be a telltale sign on arrowheads like grooving that indicates they've been modified for poison. μηδείς (talk) 20:48, 3 February 2014 (UTC)

• Unfortunately, grooves can also be there to help attach the arrowhead to the arrow. StuRat (talk) 23:25, 3 February 2014 (UTC)

Yes, but attachment grooves have only one location and orientation. Additional grooves would be suspect. μηδείς (talk) 17:41, 4 February 2014 (UTC)

How did Newton derived his law of gravitation?

How did Newton derived his law of gravitation? 182.66.52.106 (talk) 14:02, 2 February 2014 (UTC)

The history of how Newton's law of gravitation came to be is somewhat under dispute. See Newton's law of universal gravitation#History. Red Act (talk) 14:29, 2 February 2014 (UTC)

Newton wrote down exactly how he derived it! It's called Philosophiae Naturalis Principia Mathematica, and it is one of the most important physics books ever written. Fringe historiographers can debate all they like about attribution, or discuss prior work that influenced Newton, but there is no reason to doubt that Newton wrote this book; so to answer the question "how did Newton derive his law of gravitation," there is no better source than Principia.

If you choose to read the Principia (for example, in English translation), you can see exactly how Isaac Newton presents the derivation of universal gravitation. He begins with philosophical assertions. I paraphrase them thusly: natural laws ought to be consistent throughout the universe, and natural law directly corresponds to observable phenomena, and there are no hidden variables (Newton calls these "intensions"). Next, Isaac Newton presents a data table of observations concerning the Galilean moons - the four largest moons of Jupiter that are easily visible from Earth - even using 16th-century optics. Newton writes some mathematics to show that the conclusions of Keplerian motion are consistent with those observations. Finally, Newton writes a mathematical expression that relates the Keplerian motion to a central force law of second order - which he already explored mathematically in Book 1. Over the next few hundred pages, he explores these consequences in greater depth. As Isaac Newton writes in his introduction to Book 3 of the Principia, a commonly-educated man might not have time to read and study all of Principia - there are so many propositions - but anyone sufficiently familiar with the most important principles and definitions - what we today call Newton's laws of motion - can skip directly to Book 3 and study his derivation of the mechanics of gravity. Nimur (talk) 17:11, 2 February 2014 (UTC)

My understanding is that the history is a little more complicated than that. As I understand it, Newton invented calculus and used it to work out the law of gravity and its consequences. But when he wanted to publish it, he felt that people wouldn't believe results obtained using such a newfangled method, so for the book he worked out proofs for everything using classical geometry, and completely avoided any mention of calculus. The result is that the book is much more complicated than it really needs to be. Looie496 (talk) 17:32, 3 February 2014 (UTC)

February 3

How far below the horizon could I see the sun from mount everest?

I've heard the trick of being able to see the sun set twice if you lay down and watch the sun set and then quickly stand up. I also know that due to the earth's refraction we can still see the sun when it is about 1º below the horizon. Now I might be able to figure this out for myself by watching for when the sun's light no longer lights up the tallest of the thunderheads and then looking a smartphone app that shows the current sun elevation, but it's winter here in Florida so no thunderheads to help me out. I looked at the article at horizon but couldn't really wrap my head around which equation would help me out.I think it is basic trigonometry, but my brain is a bit rusty. (the motivation for this question stemmed from wondering about the visibility of partial eclipses at sunrise/sunset when the maximum eclipse is well below the horizon at sea level)  — TimL • talk 08:59, 3 February 2014 (UTC)

You could use an online calculator for calculating the distance to the horizon: [[2]]. I don't believe you need trigonometry for that, the Pythagora's theorem should be enough. OsmanRF34 (talk) 13:34, 3 February 2014 (UTC)

Although the curved hypotenuse (ie, the curvature of the earth) makes it a bit tricky. These calculations were important for battleships in the pre-radar era, as knowing how far away an enemy ship on the horizon was, gave you a clue as to how to aim your guns. Alansplodge (talk) 14:04, 3 February 2014 (UTC)

No, it's not tricky. The hypotenuse is not on the curve. Indeed, there is no curve here. There is a right angle where your view 'touches' the Earth. And you know two sides of these triangle. One of them is the radius of the Earth (one leg of the triangle). The other (the hypotenuse) is the radius of the Earth added to the height your eyes are over the Earth surface. Your are trying to discover the other leg of the triangle. OsmanRF34 (talk) 14:11, 3 February 2014 (UTC)

Quite right. I should know better by now. Alansplodge (talk) 16:11, 4 February 2014 (UTC)

Let's ignore refraction and assume a spherical Earth with radius R. If you are a height h above sea level then the line of sight to the horizon will be at an angle θ below the horizontal where θ is given by:

$\theta =\cos ^{-1}\left({\frac {R}{R+h}}\right)$

If we take R to be 6371 km and h to be 8.8. km (the approximate height of Mount Everest) then θ is about 3 degrees. The sun takes about 12 minutes to traverse an angle of 3 degrees. Of course, if you are really on Mount Everest your local horizon will be domonated by other nearby mountains, so your effective line of sight to the local horizon will probably be rather less than 3 degrees below the horizontal. Gandalf61 (talk) 14:48, 3 February 2014 (UTC)

Yes, the terrain to the east and west of Mount Everest is very high, and you can't even come close to seeing the sea-level horizon in those directions. There are other places where you'd be able to see a lot farther, even if the peaks are not as high. Looie496 (talk) 17:24, 3 February 2014 (UTC)

That raises an interesting question which the OP's question leads to: What is the highest mountain from which an ocean is visible? ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:32, 3 February 2014 (UTC)

Mauna Kea comes to mind. From the top, at an altitude of about 14,000 feet, you can see ocean in all directions - provided the day is clear. Nimur (talk) 21:11, 3 February 2014 (UTC)

That's about half the height of Everest and the other tallest Himalayan peaks, so it would be a good one to test with. First compute what the answer "should be", and test it by one of you going to the mountaintop and one of you going to the shore, and compare notes via cellphone. As an added bonus to that experiment, you're in Hawaii, which is generally a better climate than the Himalaya range. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:16, 3 February 2014 (UTC)

As I recall, you can see the ocean but not the shore, because the south-eastern coast is obscured by Mauna Loa. Nimur (talk) 23:40, 3 February 2014 (UTC)

The question would be whether the team member who's on top of the mountain can see the ocean's horizon. That assumes the team member near the shore also has a clear view of the ocean's horizon. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:10, 4 February 2014 (UTC)

Is every death by drugs a overdose?

Couldn't it just be some sort of bad reaction, which could happen with any amount of the same drug? Without any trace of a given drug a person wouldn't die of it, so in this sense it's clear that any death by drugs is an overdose. But overdose seems to imply that the quantity was too much, not that an interaction happened. OsmanRF34 (talk) 12:33, 3 February 2014 (UTC)

I'm no expert, but I imagine that you could also be poisoned by something else being mixed in with the drug that you didn't know about, or you could do something fatally dangerous while "under the influence", neither of which could be described as "an overdose". Alansplodge (talk) 14:10, 3 February 2014 (UTC)

Paraquat was one such toxic contaminant, in marijuana. Drug dealers cutting drugs with whatever nasty chemical is at hand is also a problem. During Prohibition in the US, toxic wood alcohol was also a common contaminant in grain alcohol. StuRat (talk) 15:41, 3 February 2014 (UTC)

News reports say they're going to get going on Hoffman's autopsy pronto. That should tell us what specifically killed him. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:32, 3 February 2014 (UTC)

You can get an embolism if you mix air with your heroin. Technically not the drug, but close enough. No idea how common it is, but pretty sure the actual heroin kills more. InedibleHulk (talk) 16:14, February 3, 2014 (UTC)

• NO, people have allergic reactions to certain drugs which are otherwise taken at a small, therapeutic dose. Surely you've heard commercials warn, "If you develop a sudden rash, notice swelling of the tongue, and have trouble breathing, stop taking fratastatin immediately, and make an appointment with your coroner," μηδείς (talk) 16:23, 3 February 2014 (UTC)

I'm trying to figure out what would be the proper dose of heroin. Although it might be that, by definition, an overdose of anything is "just enough to kill you." Like if you're highly allergic to peanuts, maybe you could survive eating a few - but if you ingest an entire container, you might be in major trouble. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:29, 3 February 2014 (UTC)

If you are highly allergic to peanuts you are at risk of anaphylaxis from exposure to trace amounts. Sufferers given oral peanut therapy can only tolerate five peanuts a day after six months increasing exposure. Richerman (talk) 22:52, 3 February 2014 (UTC)

For recreational use, the 'proper' dose is presumably the minimum dose which produces the desired physiological and psychological effects.

Heroin is prescribed to addicts in some countries (generally under fairly restrictive, controlled, specific conditions) as part of a harm reduction strategy and/or to ease withdrawl symptoms.

Heroin is used clinically as a potent analgesic. Taken orally, it is deacetylated and enters the system as morphine. As an injectable, in the UK it is used more often than morphine for treatment of acute pain (in clinical use, the choice between heroin and morphine is down to a combination of history, training, government regulations, and differences in pharmacokinetics and bioavailability in certain circumstances). So yes, there are clearly defined 'proper' doses of heroin for a wide variety of situations. TenOfAllTrades(talk) 16:50, 3 February 2014 (UTC)

The articles on drug overdose and adverse drug reaction suggest that indeed bad things other than overdose can occur. "The term 'overdose' is often misused as a descriptor for adverse drug reactions or negative drug interactions due to mixing multiple drugs simultaneously." More links to related subjects in those articles. 88.112.50.121 (talk) 18:47, 3 February 2014 (UTC)

With some drugs, other substances can dangerously amplify their effects. The most commonly cited example of this is that eating grapefruit will increase the body's sensitivity to a wide range of drugs - resulting in the symptoms of an overdose, even for people taking the correct amounts. SteveBaker (talk) 19:13, 3 February 2014 (UTC)

Pre echo removal

How can I remove pre echo from my audio recordings using a sound editing package?--86.184.57.126 (talk) 16:06, 3 February 2014 (UTC)

I don't know of a tool that does it directly.

The most obvious suggestion is to:

1. Look carefully at the audio wave-form that precedes the start of the recording and try to estimate the delay and the relative amplitude of the pre-echo compared to the true sound.
2. Duplicate the track, shift it in time and reduce it in amplitude to match the delay on the echo. The time shift will need to be very accurate to do this well.
3. Subtract the shifted, quieter version of the track from the original.
4. Play with the delay and the amplitude reduction until you're happy with the results.

I think you can do all of those steps in (for example) Audacity - which is a free/OpenSourced program...but I've never tried it.

The likely problem is that some of the mechanisms that cause pre-echo (such as audio tape print-through and groove distortion in vinyl records) may produce somewhat varying delay and amplitude throughout the recording. That might mean that you can correct this problem for short recordings - but not for long ones.

One problem with this is that if there is noise in the recording that happened AFTER the print-through happened, then you'll be adding pre-echoed noise into the recording by doing it.

Another problem with vinyl record pre-echo on stereo recordings is that the echo will not always be on both sides of the stereo image identically - and one side of the original may have echoed more strongly into the other. So cross-talk maybe a major issue here.

SteveBaker (talk) 19:03, 3 February 2014 (UTC)

What about Spectral subtraction ? Would that work?--86.182.50.230 (talk) 16:43, 4 February 2014 (UTC)

How long would it take for a cylinder of ice 2850m high and 2850m in diameter to melt?

First an explanation: This is not a homework assignment! I'm a linguistics major who graduated a long time ago :) I want this question answered for a personal creative writing project. I have attempted to solve this problem on my own but I've reached a brick wall where my knowledge and ability is totally insufficient, and would really appreciate someone who actually knows this stuff to help me out.

The problem is as follows:

The cylinder of ice is 2850m in length and 2850m in diameter. One of its flat surfaces is on rock and it is surrounded by air on all other sides. The ice starts at -45C and the surrounding air temperature is 5C. How long would it take to completely melt?

A back of the envelope calculation is all I really need, just so I can get an idea if it's going to be more in the order of years or centuries. Thanks very much to anyone who can help me with this. --87.82.207.195 (talk) 20:17, 3 February 2014 (UTC)

Whether there's any wind or sunlight on it would make a huge difference, but I think centuries is more what we're talking about. Also notice that even small impurities will tend to concentrate on the outside, after some ice melts, adding a layer of insulation that won't melt away.

The ground temperature under the ice would also play a roll. Of course, unless it had a major source of heat like volcansm or an underground stream, the ground would soon cool down to match the ice's temperature. Also, if the humidity is low, you could get significant sublimation of the ice directly to the air, without melting first.

Something else to consider is that that much ice, over years, will behave more like gelatin than a solid. That is, it will flatten out and flow downhill, just as glaciers do. The flattening out will increase the surface area and thus the melt rate, as will the inevitable fissures which form, and gullies from meltwater. So, if you hope to keep a cylinder of ice that shape for years, it would need to be in space, away from gravity (although it might even deform a bit under it's own gravity).StuRat (talk) 23:11, 3 February 2014 (UTC)

[dumb error fixed: see below] Hmmm, wind speed and rainfall would also play a major role. Anyway, the heat of fusion of water is 79.8 cal/g, the density of ice is something like 0.92 g/cc, and the volume of this thing is 2850 * (2850/2)^2 * pi = 1.82 x 10¹⁰ m^3 = 1.67 x 10¹⁶ g = 1.33 x 10¹⁸ cal = 5.58 x 10¹⁸ J. Now the entire surface of the cylinder is 2850 * (2850 * pi) + (2850/2)^2 * pi * 2 = 3.8 x 10⁷ m^2. So the time x the amount of watts per square meter absorbed has to be equal to the 5.6 exajoules (Yeah, I also looked that one up, but just to check...), i.e. 5.6 E+18 / 3.8 E+7 = 1.46 E+11. Now sunlight is defined as 120 watts/meter or more for a sunshine duration of perhaps 1200-1600 hours per year (3 to 4 hours a day) in some 5 C-ish climates on the map of Europe shown in that article. Though it is sometimes much brighter I've used this as an ad hoc average, but that's still E+9 seconds. (3.16 E+7 is a year). I'm not sure how to qualify the wind and rain heating though, which I'd expect to be more substantial. (The close observer will note that this relation doesn't hold as the cylinder gets smaller; it will go from the present volume per surface to zero. Whether that integrates to a net 1/2 or something else, I haven't tried to figure out. Also note a net 1/2 in the other direction since sunlight won't hit any more than half of it.) This still doesn't bring me to a bottom line on account of the weather variables. Hmmm, wait... suppose the area gets 20 inches of rainfall a year. It comes down at 5 C. It takes 80 C worth of energy to melt ice, so the rainfall would melt 20 * 5/80 = 1.2 inches (5 cm) of ice a year (supposing from the top down) and take, oh, 20* 2850 years to get to the bottom. The wind, well... Wnt (talk) 23:43, 3 February 2014 (UTC)

For the record, sunlight goes up to about 1000 W/m^2, though after accounting for time of day and angle of incidence, having an average flux of 100 to 200 W/m^2 isn't unreasonable. Dragons flight (talk) 06:23, 4 February 2014 (UTC)

@Wnt: I believe you miscalculated by a factor 10³, as the density of ice is about 0.92 x 10⁶ g/m³, while you seem to have used 0.92 x 10⁹ g/m³. Easy mistake to make obviously, but still, it does make a difference. - Lindert (talk) 15:26, 4 February 2014 (UTC)

Crap! I keep rushing back and forth from Wikipedia recently -- too many hasty errors lately. Thanks! Wnt (talk) 16:28, 4 February 2014 (UTC)

It's really hard to say because something that big would have a fairly drastic effect on local weather patterns - and at close to 3km tall - the top of it would be above 'the snow line' - so it wouldn't be melting at all. But there are other more complex effects going on here - the weight of the ice pushing down on the base would increase the pressure tremendously - and that changes the melting point (see Pressure melting point)...The melting point decreases with pressure until it reaches some very high pressure. Then it increases dramatically. I'm not sure if the ice would reach that higher point - but all of this would have a large effect on the melt time. Another point is that the structural stability of the material wouldn't allow it to remain as a cylinder - it would immediately collapse under it's own weight into more of a conical pile - and then flow and spread out like glaciers.

We know that icebergs that are tens of miles across take years to melt - but those have very cold water beneath them and the action of waves tends to break chunks off of them. In 1946, a 140 square mile iceberg was tracked for 17 years...but it would only have been a hundred feet thick or so - a 3km cylinder would be much harder to melt.

My gut feel is that we're talking centuries rather than decades - but certainly many decades. I agree with StuRat that this thing would rapidly turn into a bunch of glaciers flowing away from the original object - but the lifespan of those glaciers depends dramatically on where in the world they are.

From the point of view of writing fiction, I doubt any scientist would argue with you if you said it would take anywhere between 200 and 1000 years...but if you're looking for any kind of realism then forget the idea that it's a cylinder - think "ice-mountain with glaciers".

SteveBaker (talk) 14:23, 4 February 2014 (UTC)

Well, if the Gods who arranged this PR stunt had resort to a perfect thermal conductor (is such a thing possible?) they could have wrapped it every few feet while they were laying it down with cylindrical shells of the stuff, so that over the years its broad sides would display immense messages of deep spiritual significance for the priests among their descendents to spend their lives pondering. ("Buy Moka-Cola") Wnt (talk) 16:34, 4 February 2014 (UTC)

As a minor nitpick but which is also part of an important point, note that it's not totally clear to me top of the ice cylinder will be above the snow line. As our article atests and I guess SB knows, for many places it's well below the snow line. I myself climbed one Mount Kinabalu that's 4km, where frost and ice is not that uncommon but snow very rare [3] (and no I didn't see any snow), at least in modern times. In fact in some such places even frost at 3 km may be comparatively rare [4].

The key point here is the original statement said the surrounding air temperature was 5 degrees C. Where relevant, some of the above answers appear to have assumed that this referred to the average air temperature at or around sea level. If that's the case, then I would guess it's almost definite that 3km would be well above the snow line (which I think is what SB is getting). Even if it's the average air temperature at the median point or alternatively the average average air temperature I would guess 3km would also be above the snow line. On the other hand, if it was 5 degrees C average air temperatures at the top of the cylinder, it seems unlikely the top would be above the snow line, at least initially.

Of course, and the more important point here, I'm presuming as I think did others that 5 degrees C means the average air temperature at whatever point before the cylinder appeared (or assuming the cylinder wasn't there). As SB has said, the appearance of this cylinder will drasticly affect local weather patterns, not said but I guess implied by his and other answers, it's also going to affect local climate. I'm guessing the average air temperatures will be a lower even 10 km away with the appearance of this ice cylinder. So talking about the air temperature after the appearance of the cylinder is fairly confusing.

Nil Einne (talk) 21:49, 4 February 2014 (UTC)

Wow, thanks for all the replies! I hadn't considered a lot of these other issues. Given me a lot to consider. --87.82.207.195 (talk) 18:01, 4 February 2014 (UTC)

If it's for the sake of fiction - could this be a cone rather than a cylinder? A cone with the correct Angle of repose would be relatively stable - and the resulting glaciers would take a while (years, maybe) to form and expand out. A perfectly formed glassy-smooth cone would still be an impressive thing for the aliens/god/bad-guys-from-the-future/mad-scientist to have left behind - and it would remain looking pretty much exactly like that for a very long time. Sadly, I don't know what the right angle of repose would be for solid ice. We know that for snow, it's 38 degrees - but I'd expect it to be much steeper for solid ice. SteveBaker (talk) 14:57, 5 February 2014 (UTC)

How dangerous is Everclear?

Is there anything specific about Everclear, other than its strength that would make it extremely dangerous to do straight shots, or chug it freely from the bottle? I realize that the strength is more than twice that of a typical vodka, so you're going to get drunk quicker (twice as fast - is it even a linear thing?) - but aside from that, is there anything else that justifies the 'Everclear will kill you' belief that seems to be around.

The purpose of this question is not so that I may plan my own debauched drinking session. I don't think that you can even buy it, or anything comparable in my country (that I've seen). I've seen people talking about it (slightly fearfully) online, and joking about the crazy guys who shoot Everclear, is all. --Kurt Shaped Box (talk) 21:04, 3 February 2014 (UTC)

No. Alcohol is alcohol. The real danger is people not realizing the strength and drinking too much, too fast. Oftentimes people associate everclear with backyard distilling operations, in which case, contaminants like methanol, etc. can find their way into the everclear. But for the legally produced and regulated everclear, there is no danger. Justin15w (talk) 21:10, 3 February 2014 (UTC)

"Alcohol is alcohol" is not quite correct. Everclear is a very strong but consumable form of Ethanol a.k.a. grain alcohol. Wood alcohol, or Methanol, can be deadly. Of course, even consumable alcohol can be poisonous if too much is ingested. Everclear is typical added to something else, to "spike" it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:14, 3 February 2014 (UTC)

It is my understanding, though I don't have a ref, that if you concentrate ethanol to nearly 100% (absolute alcohol), it actually is more dangerous than the same amount of total ethanol consumed as a larger volume of more dilute liquor. The reason is that, at such high concentrations, it sucks water out of your tissues on its way down, which can severely irritate your throat and esophagus. Whether EverClear is that concentrated, I don't really know.

By the way, there is another danger to lab-grade ethanol even if you dilute it, which is that, in order to get ethanol more concentrated than the ethanol–water azeotrope, it is distilled using benzene, which causes cancer. How much benzene is left, or how dangerous that is, again, I don't really know. But just because the bottle has a liquor tax stamp (in the US at least) doesn't necessarily mean it's safe to spike the punch with it. --Trovatore (talk) 21:23, 3 February 2014 (UTC)

In chemistry lessons at school, they always told us not to even think of drinking the lab ethanol - because it would kill you. I was never sure whether they actually meant it, or it was just something that they said to discourage 14 year olds from stealing it and getting drunk. Later on in life I met someone who worked in a lab, who told me that the stuff goes great with orange juice, so I dunno... --Kurt Shaped Box (talk) 21:36, 3 February 2014 (UTC)

Well, they may both have been right. If the issue is cancer, then it very well might kill you, but not so fast as to keep you from coming to the conclusion that it goes great with OJ. --Trovatore (talk) 21:48, 3 February 2014 (UTC)

School Chemistry Lab alcohol will be Denatured alcohol in most cases. APL (talk) 23:05, 3 February 2014 (UTC)

• Everclear is meant for consumption, so you don't need to worry about contaminants. But it is a wicked desiccant, as Trovatore mentions, and can lead to acute and chronic damage, along the path of Christopher Hitchens. If you leave Everclear open to the air it will absorb water until it reaches a certain weaker proof at equilibrium with the ambient humidity. Lab alcohol is often denatured alcohol, meaning it has been adulterated to make it unpalatable, and thus not subject to the steep tariff on drinking alcohol. But not all lab alcohol is adulterated, since some reaction need pure ethanol. Basically, Everclear is a vanity item. μηδείς (talk) 22:05, 3 February 2014 (UTC)

Note that there is another reason why drinking concentrated alcohol is more dangerous than drinking the same quantity of alcohol, mixed with more filler (mainly water). That is because the filler limits your rate of consumption. If it takes a gallon of beer to reach a fatal level of alcohol poisoning, most people will find it difficult to drink a gallon quickly. They might very well be able to drink a gallon of beer over the course of a night, but their body is metabolizing the alcohol during that period, so it never reaches a fatal level. Also, since the alcohol level builds up more slowly, they are likely to pass out or vomit before they reach a fatal blood alcohol level.

Now, with highly concentrated alcohol, provided they can choke it down, it's relatively easy to receive a fatal dosage quickly. StuRat (talk) 23:05, 3 February 2014 (UTC)

What, in ounces, would be a fatal LD50 of Everclear? μηδείς (talk) 01:11, 4 February 2014 (UTC)

It would, of course, be unethical to kill half your human test subjects to determine the LD50. However, the LD50 for rats, fed a 70% ethanol solution orally, is >90 mL/kg of body weight, according to [5]. From there you can convert from metric and adjust for the percentage of ethanol in Everclear (there are apparently 2 concentrations commonly sold). StuRat (talk) 01:27, 4 February 2014 (UTC)

And of course you have to be careful with applying this LD50 to humans, because rats and humans differ, sometimes dramatically, in what is toxic and why (e.g. [[6]]). Another example: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2259215/ Why isn't this wikilink to Median lethal dose showing up correctly? --TheMaster17 (talk) 10:28, 4 February 2014 (UTC)

This might be an urban legend, but I have heard stories of people drinking neat Polish vodka of similar strength, and having no immediate effect, supposedly "because osmosis means that water comes in to your stomach first to dilute it". After 10 to 15 minutes they have suddenly become very drunk and in some tellings fallen unconscious and been rushed to hospital. I have no desire to test this experimentally. -- Q Chris (talk) 11:54, 4 February 2014 (UTC)

Left as an exercise for the reader, of course, is the question of how long it takes for beverage alcohol of any sort, once ingested, to make its way from the gastrointestinal tract into the bloodstream. Most absorption of ethanol happens in the small intestine, though a bit is absorbed through the stomach lining as well. In a fasting state – that is, with an empty stomach – beverage alcohol will pass fairly quickly through the stomach into the small intestine, but even then there is a lag of several minutes between beverage consumption and a significant rise in blood alcohol levels. (You can see some real kinetic data in this study, which also shows that patients who have undergone gastric bypass surgery have a much shorter lag between ingestion and absorption of ethanol.) On a full stomach, the kinetics will be even slower. No need to resort to 'osmosis' for an explanation. TenOfAllTrades(talk) 15:14, 4 February 2014 (UTC)

Is it true that a person can become a stutterer by wilful practice?

Is it true that a person can become a stutterer by wilful practice, or is the speech disorder neurological? (Please note: this question is not to demean stutterers in any way, as I have high respect for these people. I am only asking out of curiosity.) 140.254.227.177 (talk) 21:21, 3 February 2014 (UTC)

Two words: Mel Blanc. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:15, 3 February 2014 (UTC)

Thufferin' thuccotash! Practice can also help fake various mental disorders. InedibleHulk (talk) 11:25, February 4, 2014 (UTC)

On that note, hats off to Clarence Nash for creating one of craziest, unintelligible characters this side of Taz. InedibleHulk (talk) 11:32, February 4, 2014 (UTC)

Yes. Hence the Mad character "Darnold Duck", whose quacking had to be translated. I'm just wondering if the OP meant that someone could literally develop an uncontrollable stutter. The orginal voice of Porky Pig was a guy who was a real-life stutterer but couldn't control it. Blanc's voice for Porky was totally under his control, i.e. he could turn it on and off as needed. Obviously, Colin Firth did a fake stutter very well in The King's Speech. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:52, 4 February 2014 (UTC)

joule heating is rii but also vv/r

so.. why using high voltage to distribute power? thanx --80.182.18.25 (talk) 22:13, 3 February 2014 (UTC)--80.182.18.25 (talk) 22:13, 3 February 2014 (UTC)

In the formulas P = I²R and P = V²/R, the value of R is the total resistance in the circuit, including both the resistance of the wires, and the resistance of the load. When one is only interested in finding the power dissipation in the wires, the formulas do not apply. Jc3s5h (talk) 23:05, 3 February 2014 (UTC)

They do apply if you use the right values, where P is the power lost in transmission, R is the resistance of the transmission line, I is the current, and V is the voltage drop only along the transmission lines, not the total voltage. 80...125 was probably confused by thinking of using the total voltage dropped across both the transmission lines and the load in their calculation for power lost. -- ToE 01:25, 4 February 2014 (UTC)

Indeed it's awkward that P = V²/R implies that the higher is V the higher is P --Ulisse0 (talk) 17:45, 4 February 2014 (UTC)

February 4

Delta Dagger, part 3

Since at least some Delta Daggers that stood alert in the bad old days were armed with the AIM-26 nuclear air-to-air missile, and since that missile was always under the pilot's direct control, this begs the question: What precautions (if any) were in place to prevent an accidental launch? 67.169.83.209 (talk) 03:10, 4 February 2014 (UTC)

Probably none.

You have to understand that the W54 warhead was believed to have a yield of only 10 to 20 tons of TNT (although subsequent tests suggest it may have accidentally been much higher). A version of it intended to be fired from a shoulder-mounted infantry weapon was said to be able to destroy buildings within a 2 block radius. That's comparable to a GBU-43 conventional weapon which has a an explosive charge equivalent to 11 tons of TNT. As such, the consequences of an accidental launch were not that much worse than a large conventional weapon. Nowadays, the stigma of accidentally detonating a nuclear weapon would be horrific compared to the same amount of explosive power in a conventional bomb...but back in the cold war, not so much! So the idea of needing a decision to launch at the presidential level of the chain of command simply didn't figure into the thinking of the time.

Remember, "nuclear" has horrible connotations these days - but back then, they were experimenting with nuclear powered airplanes (flying the test model with an unshielded, working nuclear reactor on board over downtown Fort Worth, Texas!) - there was talk of nuclear powered cars! The technology simply didn't have the big scare factor it has now - so a 10 ton-equivalent warhead was no big deal for a pilot to launch on his own decision...at least no more than a pilot would be restricted in dropping a GPU-43.

SteveBaker (talk) 14:57, 4 February 2014 (UTC)

Maverick missile

Was the AGM-65 Maverick developed from the AIM-4 Falcon, or does it just happen to look similar? 67.169.83.209 (talk) 03:14, 4 February 2014 (UTC)

This article says it's "reminiscent" of the Falcon. This one says "The AGM-65's configuration is similar to that of AIM-54 Phoenix and AIM-4 Falcon missiles". I can't find anything that says it actually was developed from the AIM-4, but it would make sense if it was. Alansplodge (talk) 16:30, 4 February 2014 (UTC)

change in top #11 - #100 leading causes of death over the last 73 years

I'd like to know, over time, how the top #11 - #100 leading causes of death worldwide has changed over the last 73 years.

Is there some graph that might show this clearly? 212.96.61.236 (talk) 19:31, 4 February 2014 (UTC)

WHO has a vast database of statistics. It wasn't formed until around the 1940's but it is a good place to start. [7] . They don't tend to have graphs but rather excel spread sheets.--Aspro (talk) 20:12, 4 February 2014 (UTC)

RIGHT, that's what I'd like to know! 212.96.61.236 (talk) 23:00, 4 February 2014 (UTC)

(HAHahaHAHahaHAHahaHAHahaHAHahaHAHaha μηδείς (talk) 04:39, 5 February 2014 (UTC) )

Just to clarify why Medeis is so amused, Aspro meant World Health Organization when he typed "WHO". There is a link in his response to some of the WHO's factsheets. Katie R (talk) 12:53, 5 February 2014 (UTC)

And re-reading, it sounds to me like you were aware and making a deliberate joke and I think I should not post things here before I have my coffee... Katie R (talk) 13:13, 5 February 2014 (UTC)

accelerated regions in dna

are they usually associated to deleterious changes? thank you --95.233.126.241 (talk) 20:43, 4 February 2014 (UTC)

Chap stick and cold sores

I've seen conflicting information online about the use of chap stick during cold sore outbreaks. Can the cold sore virus be transmitted onto the chap stick, and from there back to the person after the outbreak, or to another person? If so, how long can the virus survive on the chap stick? --BDD (talk) 22:05, 4 February 2014 (UTC)

Not a full answer, but a start: this paper [8] titled "Human herpes simplex virus infections: Epidemiology, pathogenesis, symptomatology, diagnosis, and management", says

“ The principal mode of acquisition is through direct exposure of mucous membranes or abraded skin to the lesions or mucosal secretions of an individual with active primary or recurrent infection. Virus can also be transmitted by respiratory droplets or exposure to mucocutaneous secretions of an asymptomatic person shedding the virus in the absence of clinical disease. HSV1 is primarily associated with oral, pharyngeal, facial, ocular, and central nervous system infections and largely transmitted by oral secretions and nongenital contact... HSV1 can remain viable on the skin, clothing, or plastic for brief periods, facilitating transmission through close nonsexual contact, such as kissing on the cheeks or sharing common utensils ”

(wikilink, emphasis and removal of inline references by me) -- the point is, if there were any known, significant risk of transmission via chapstick, I'd suspect this (2007, highly cited) paper would have mentioned it in that section. I don't know how short of time "brief" means to these authors, but I suspect it on an order of hours, not weeks. SemanticMantis (talk) 22:25, 4 February 2014 (UTC)

1) You should never share chap sticks.

2) Medicated chap sticks should kill any virus but refer to point one.

3) Recovery from a cold sore usually means your immune system has kicked in and you wont reinfect yourself.

4) Prolonged use can dry the epidermis of the lips causing cracking. --Aspro (talk) 22:37, 4 February 2014 (UTC)

• Thanks. The paper is very informative, and seems to disprove the apocryphal evidence I found of people re-infecting themselves with old chap stick. Man, if you can't trust Yahoo Answers, who can you trust anymore? --BDD (talk) 23:20, 4 February 2014 (UTC)

Ha! Keep in mind that re-emerging or recurrent infection need not (as far as I know) correspond to new exposure or transmission. It can just lie dormant without producing symptoms, then flare up based on other factors. That is very easy to confuse with "re-infection". SemanticMantis (talk) 00:09, 5 February 2014 (UTC)

It's hard to find someone giving a number, but sharing lip balm is a known cause of meningitis infections. In the absence of specific data about a lip balm and HSV1, I wouldn't want to predict whether there could be a connection or not. The issue may not be literal "infection" with the HSV1, which is already in the cells, but whether some product of HSV1 could linger in the stick that might tell other HSV1 lying dormant in cells that it is time for another attack - perhaps indirectly, i.e., the immune system recognizes fragments of HSV1, steps up enforcement, ends up activating HSV1 in the targeted cells. But it's useless to speculate a mechanism without hard data in hand whether the effect happens at all, which it likely may not, except to illustrate that we can't call things "impossible". P.S. to editorialize a moment (hopefully we shall not call this medical advice as it is a subclinical, i.e. non-medical, condition), I should call attention to Ariboflavinosis, which says that a) riboflavin deficiency is marked by severely dry/cracked lips, and b) nearly 1/10 of Americans have "subclinical" riboflavin deficiency. I've never used lip balm, but in rare instances that I've noticed any roughness I grabbed a multivitamin. Wnt (talk) 00:27, 5 February 2014 (UTC)

I'm guessing you don't live in an area where it is cold, dry and windy for a significant proportion of the year - dry lips for me are exclusively a winter phenomenon, and specifically an outdoors winter phenomenon (if I don't spend a lot of time outdoors my lips don't get cracked). I find lip balm to be essential in such conditions . Equisetum (talk | contributions) 16:40, 5 February 2014 (UTC)

February 5

Heroin

What's the point of cooking heroin in a spoon before injecting it? Is it basically to speed up the dissolving process for quicker injection? Is the reaction more potent when it enters the blood stream if it's warm?

Note: I'm not (I think this is obvious) a heroin addict. I don't plan to be one. I don't plan on using this information for my own use or to inject anyone else. This is not homework. Please don't hat this medeis. Not a junkie, Dismas|^(talk) 01:13, 5 February 2014 (UTC)

It's to get it to go into solution. Bad enough to be injecting it in the first place, last thing you want is particulate matter in the bloodstream. μηδείς (talk) 01:17, 5 February 2014 (UTC)

• This I think is more of a chemistry question. Good quality heroin ( the medical type) is a salt and will dissolve in cold water. Much street heroin is of the smoking type Free base. Hence the the need to add acid and heat. Citric and ascorbic are the most common but hydrochloric will yield diacetylmorphine hydrochloride (have purposely missed out how to obtain the precipitate, so don't try this at home folks). Most 'Nam' vets will tell you this because smoking heroin was all that was on offer over there. --Aspro (talk) 02:17, 5 February 2014 (UTC)

I am not quite sure how saying getting it into solution with a link is not a question of chemistry. In any case, our article doesn't give the solubility of the pure salt, but I'd be very surprised to see someone on a jones using a precious portion of a gram of heroin mixing it in a flask and hoping it all dissolves and he leaves no waste behind rather than assuring he utilises it all and gets almost all of the product by dissolving it in a very small amount of boiling water. μηδείς (talk) 04:36, 5 February 2014 (UTC)

Does the Coanda effect make pyroclastic surges hug the ground?

Since hot air normally would rise, I'd find it natural that the Coanda effect is what confines pyroclastic surges to relatively close to the ground. Is that true?--Jasper Deng (talk) 03:50, 5 February 2014 (UTC)

This source [9] makes clear that a pyroclastic surge is a mixture of hot gas and volcanic particles - the latter will add significantly to the density. AndyTheGrump (talk) 04:03, 5 February 2014 (UTC)

Long term memory

what is the real mechanism of storage of long term memory in human brain?Singh.ssm (talk) 05:23, 5 February 2014 (UTC)

Isn't it connections formed between the brain cells ? StuRat (talk) 06:52, 5 February 2014 (UTC)

Yes. Either new, or more strongly or less strongly potentiated existing synaptic connections. See long term memory. μηδείς (talk)

Spark Generator

I have completed a physics experiment. A cylinder (solid with nearly no air resistance) was dropped from the top of a free fall apparatus. I used a spark generator and a free fall apparatus to create marks on a peice of tape to measure the acceleration of gravity on earth's surface. The tape was marked every 1/60 second. The mark was made at the location of the cylinder during that time. What would be some errors in the experiment caused by the spark generator? For instance, do spark generators fire exactly every 1/60 seconds? — Preceding unsigned comment added by 99.146.126.108 (talk) 06:40, 5 February 2014 (UTC)

If it's using the A/C frequency from the wall outlet, then it should be quite accurate. However, the spark may sometimes deflect more upwards or downwards from the source. I'd expect more error from that. Then there's air resistance to consider, so the actual acceleration is less than g. StuRat (talk) 06:48, 5 February 2014 (UTC)

Also, 'g' varies considerably from place to place - depending on things like the kinds of rocks beneath your feet, your latitude and your elevation above sea level. It's possible that your answer differs from the text-book value for 'g' - yet is still an accurate measurement of your local gravitational acceleration. Gravity_of_Earth#Variation_in_gravity_and_apparent_gravity says that this variation is about 0.7% over the surface of the earth...about 0.5%.

The spark generator itself could possibly add some delay - but you'd expect the delay to be the same each time it 'fires' - so that shouldn't create an error if all you're doing is measuring the distance fallen between two sparks. SteveBaker (talk) 14:47, 5 February 2014 (UTC)

How Exactly Did Gay Males Reproduce Several Centuries Ago and Beyond?

I apologize if this question is perceived as offensive, but I do think that this is a legitimate question to ask here. How exactly did gay (not bisexual) males reproduce back in the old days, centuries before modern technology such as in-vitro fertilization became developed and available? For reference, an example of a gay male who reproduced several hundred years ago was Philippe I, Duke of Orléans, so obviously this event indeed occurred sometimes even several centuries ago and perhaps even earlier than that. Futurist110 (talk) 06:46, 5 February 2014 (UTC)

I think gay men who are incapable of having sex with a woman are relatively rare. In that case, I suppose they could always have somebody else do the deed and they could take the credit. StuRat (talk) 06:51, 5 February 2014 (UTC)

How exactly would they get sufficiently aroused, though? Would they be able to successfully pretend that the woman that they are sleeping with is a man, or what? (For instance, I myself, as someone who is not attracted to males, might find it extremely hard, if not impossible, to successfully ejaculate if I ever actually have intercourse with a male.) Yeah, taking credit for another man's children is certainly possible, though. Futurist110 (talk) 07:06, 5 February 2014 (UTC)

The same way as straight ones, but with fewer tries.

Why exactly with fewer tries? Futurist110 (talk) 07:06, 5 February 2014 (UTC)

Or their sisters did so for them. You might also read kin selection and hybrid vigor assuming you think there's a gene that causes homosexuality. μηδείς (talk) 06:52, 5 February 2014 (UTC)

Thanks for these articles. I will make sure to read them. As for their sisters doing the deed, you mean having their sisters sleep with someone else and then falsely claiming to be these children's actual father, correct? Yeah, this might work, especially if one replaces the word "sisters" with "wives" here, considering that I don't see how a male would be able to marry his sister back then (and since at least some of the children which gay males fathered back then were indeed legitimate, as in being born within a marriage). Futurist110 (talk) 07:06, 5 February 2014 (UTC)

Your question was ambiguous. If you meant produce a live heir on their wives, the answer was with less enthousiasm than straight husbands would, but it only takes one or a few successful attempts. If the question was, how did the gayness gene (assuming you believe in that) get passed on, it would be kin selection--the children of gay aunts and uncles somehow benefitted from some other trait, like higher intelligence or higher fertility or some other reproductively beneficial effect of the gene. I.e., two copies of the gene makes uncle gay, but one copy makes dad smart, or mom fertile, etc., μηδείς (talk) 07:17, 5 February 2014 (UTC)

My dad figured getting married and acting straight would help him "kick the habit". It didn't (for long), but he managed to make me. If there's a hereditary gay gene, it didn't work, either. InedibleHulk (talk) 07:15, February 5, 2014 (UTC)

Britain's sea erosion

Hello sciency people and enthusiastic amateurs.

Loads of news stories in Britain in recent weeks about sea defences being washed away, along with significant sections of cliff, beach etc.

My simplistic understanding is that material destroyed in one place comes ashore elsewhere, so that Britain is neither shrinking nor expanding.

Is that right, or is there a nett gain/loss for the British mainland?

And where are the main areas of deposition and erosion for Britain?

Cheers --86.12.139.50 (talk) 15:33, 5 February 2014 (UTC)

1) The land washed away may be deposited elsewhere, as sand bars, etc. Erosion would be expected to eventually result in the grinding down of all land into the sea. It's only the forces which cause uplift of the land, like collisions of tectonic plates or volcanoes, which fight this tendency. So, if an area ceases to be geologically active, erosion will eventually grind it down into the sea. You can see this process in action in Hawaii, where the smaller Hawaiian islands no longer have active volcanoes, so are being eroded away into the ocean.

2) Sea level rise as a result of global climate change is expected to reduce the land area along the coasts.

3) Silt is deposited at the mouth of rivers, so you could expect land area to grow there, under normal conditions. However, when they dredge the rivers to allow for more ship traffic, this allows the silt to move farther out into the sea before it deposits, replenishing the sea floor instead of extending the land. StuRat (talk) 16:15, 5 February 2014 (UTC)