Wikipedia:Reference desk/Archives/Science/2006 June 27

Human fear/revulsion/hatred towards 'minibeasts'?
Why is it that whenever I see a 'creepy crawly' in close proximity to myself (or even a detailed picture on the web that I wasn't expecting), I immediately experience an adrenaline surge and the 'fight or flight' response? It only seems to happen with the really 'alien' looking creatures and those outside of my experience. For example, flies, ants and beetles don't bother me at all - but the further they are from the 'four limbs and a recognizable face' archetype, the more they unsettle me. I don't like big or fast-moving spiders and if I see a centipede or a millipede, I get the urge to either run or kill (I think it's the number of legs that scare me). That 'black and white spiky thing' posted further up was another example - I have no idea what it is but I don't like it and I don't want it in my world. The terror I experience feels like it's something hardwired and deep-rooted that I have no control over. Any ideas guys? I'm pretty sure that I'm not the only person here who suffers from this. --Kurt Shaped Box 00:56, 27 June 2006 (UTC)
 * I was considering that earlier as I searched page after page of caterpillar pictures. On the one hand, I'm intrigued by the tiny world depicted in the photo above. On the other hand, I'm repulsed by the creepers and crawlers that may very well be a few feet away from me even as I type. The two obvious possibilities are a genetic predisposition to dislike them or a dislike based on experience, especially during childhood (nature v. nurture). As in all nat. v. nurt. arguments, it is likely aspects of both, but I expect it is primarily nurture. The tiny 6- and 8-legged creatures (not to mention those with many more!) that rule our world through their grand numerosity are frequently used in movies and popular culture in general as scary/evil/gross stimuli. When Frodo et al. were hiding beneath a tree root from a Nazgul in LOTR: Fellowship of the Ring, it wasn't ponies that came prancing out, but rather millipedes and spiders. I can't say for sure where the symbolism originally came from, but I imagine it is in part because these creatures are what you see when you're in the dark out in nature and you light a fire/torch/etc. It is common to be afraid of the dark and of whatever invisibly slides or marches through it, perhaps ever nearer to your person. That's my best guess... 65.96.221.107 01:12, 27 June 2006 (UTC)
 * I find it intriguing that the instinctive phobia against spiders, for those who have it, is so precise, in the sense that objectively a spider and an insect should be hard to tell apart, but often a person will fear spiders and not insects, probably because spiders are possibly poisonous, and insects are possibly nutritious. Also, millipedes (or something else) may indicate decaying matter or some similar health risk, so their presence would be a bad sign. Peter Grey 04:18, 27 June 2006 (UTC)


 * The most visible distinction between insects and spiders is that the latter have 2 more legs and if the hardwired fear of spiders is based on that, then millipedes should scare the shit out of you because they're even more 'spidery' than the spiders themselves. :)
 * There's another nurture-possibility, namely not 'having seen it before' but 'not having seen it before'. If you don't know what it is, you don't know how dangerous it might be, so it's best to play it safe. In Borneo I once grabbed a branch and got a spiky and colourful insect stuck on my finger. I asked my guides about it with a bit of a frightened look on my face and they laughed at me. Of course that wasn't dangerous. Yeah, they knew, but whenever I see a spiky multi-coloured animal I get very suspicious.
 * That's another one - not just extremities (legs or spikes) but also colour. Some (combinations of) colours seem to be a nature-wide danger sign because poisonous animals have them. Which, of course, is a reason for other animals to also use those colours, so after a bit more evolution that sign will be worthless, I suppose. DirkvdM 10:33, 27 June 2006 (UTC)
 * ...if the hardwired fear of spiders is based on... and it's clearly a much more sophisticated instinct. Peter Grey 04:42, 28 June 2006 (UTC)
 * It's not instinctive; plenty of people don't have the phobia. I'm perfectly fine with insects, as long as they don't bite or sting; I'll rescue (non-venomous) spiders from bathtubs by letting them crawl up my arm. It would make sense, though, that the phobia is easily acquired; if you pick it up from your parents in childhood it would feel deep-seated. EdC 22:24, 28 June 2006 (UTC)

Light, tough metal alloys... Which is best?
Just a thought, but what would be some of the lightest, yet strongest alloys. I heard Duralumin was light and tough, but what I am looking for is a sharp edge that can be swung against something such wood, perhaps even steel. I realize that it all depends on what aspect of the material is more desired: weight vs. strength, but where can I happen to find a list of alloys and their ability to physical pressure and corresponding densities. I wish to find something cheap and able to be alloyed and crafted with home materials, but not necessarily... material properties are of high priority.
 * From what I've seen carbide steel is the best cutting edge you can get. Just for kicks:
 * Carbide steel is very wear resistant material developed at University of Lund, Division of Production and Materials Engineering. Carbides are extremely hard constituents whether they are of pure cementite or contain alloying material. In thin plates - as in pearlite - cementite can be machined, but larger particles which separate the constituents they drastically reduce machinability. This is the case with carbide steel which contains large carbides up to size of 30 mm and hardness of 840-1400 HV. Such hard conditions of machining demand exclusive tools like ceramics or cubic bore nitride (CBN). This type of tool are manufactured only for tuning and therefore all the tests were carried out on turning operation. --mboverload @  01:37, 27 June 2006 (UTC)


 * Carbides are unlikely to be useful in your application as their ability to hold an edge also results in them being very brittle. Striking, as you describe, is likely to crack or chip a carbide tool. &mdash;Bradley 16:41, 27 June 2006 (UTC)


 * If you want a cutting tool then weight is actually an advantage because it has more momentum when it hits. So what do you want to use it for? DirkvdM 10:36, 27 June 2006 (UTC)


 * Stone tools never lost their performances. They were there before iron and are still in use in cutlery. --DLL 18:44, 27 June 2006 (UTC)


 * Yep, a flake of flint is razor-sharp. But the edge is not very durable, I believe. DirkvdM 06:31, 28 June 2006 (UTC)

Perhaps I should have specified, this is going to be formed into a blade. And yes, momentum is excellent for an edged cutting tool, but... I can swing with the same momentum a very haevy object at a low speed as a light object at a high speed, I am looking for something very light that can be swung fast in a sideways motion. A sledgehammer or an adze gets its momentum from the help of gravity and centripital acceleration. I want something easily held in two hands that can withstand impact after impact against a very hard material and will not crack, shatter, or deform.

Drop forged heat-tempered-edge chrome-vanadium is probably the toughest and least shatterable, but it's quite dense. Otherwise Titanium-Aluminium alloy is light and strong, and if you can, you can build in a Tungsten Carbide edge. --Eh-Steve 23:09, 28 June 2006 (UTC)

Long term costs of wind farms
I need to find some information to help me estimate the long terms costs of a wind farm. Mabye something like a price breakup of an actual wind farm. Information like replacement blades, repairs, general upkeep etc is not really readily available and im wondering if any of you can help me out?

One thing im looking to find the cost of is one Enercon E-33 and another site with 3 Fuhrlander FL-100's.

Thanks Wayne
 * Googling it has some great sites. I was thinking about putting up a wind farm at one point. --mboverload @  07:41, 27 June 2006 (UTC)


 * Don't forget the ecological cost of windfarms &mdash; BBC News has this article about how wind generators are destroying our eagle habitats! Nimur 13:39, 27 June 2006 (UTC)
 * Natural selection: Get rid of birds who are stupid enough to fly into something with a rotational velocity of 100 miles per hour. --mboverload @  22:31, 2 July 2006 (UTC)

Global warming - solution?
Part of the global warming problem is that when ice melts, it reveals the darker surface beneath it, so more heat from the Sun is absorbed, aggravating the problem (the opposite can also happen, leading to a snowball Earth). So why don't we cover large parts of the Earth's surface with some reflective material, so more Sunlight gets reflected back into space? This can be done relatively cheaply - just cover the Sahara and other deserts (lots of Sun there) with white paper. DirkvdM 08:34, 27 June 2006 (UTC)
 * Paper degrades, the surface area you are talking about is HUGE. I mean, you can't imagine how huge.  Huge huge huge. --mboverload @  08:57, 27 June 2006 (UTC)


 * Yes, I can imagine. Hell, I can even quantify it. Let's take the Sahara and cover 1 million km² (of course we don't want to cover any residential areas, nor upset the Tuareg and it's a nice round figure). Take paper that's 1 mm thick (that's pretty thick, but we want it to be durable and it's also a nice round figure). That would then be 1 km³ of paper. How may trees is that? Average tree in a production forest say 20 m high, with a 20 cm wide stem is about 0,6 m³. Add the branches and you get about 1 m³. So it would take a billion trees (10^9). Oops, that's indeed quite a lot. Still, one would have to weigh that against the effect, and that I find a bit harder to calculate. And maybe there are better materials for this. Of course solar panels would be ideal if the generated energy could replace the burning of fossil fuels. DirkvdM 11:06, 27 June 2006 (UTC)
 * And remember that most of the global warming is due to gasses trapping the heat in the atmosphere, rather than the earth's surface taking it up the first time the heat comes bouncing in. - Mgm|(talk) 11:18, 27 June 2006 (UTC)
 * Why don't try to kill two birds with one stone: cover large areas with solar captors. Let's make electricity out of solar energy instead of sending it back into space.--72.60.51.181 11:07, 27 June 2006 (UTC)


 * Or into the atmoshpere, as Mgm pointed out. That was indeed my last suggestion. You could also look at this the other way around. Solar panels have the added advantage of slowing down global warming and should therefore be subsidised for that effect. The only question is how to quantify the effect. What costs does global warming entail? Given the massive starvation caused by failed harvest I'd say they're huge. But then you'd have put a price tag on a human life. DirkvdM 11:45, 27 June 2006 (UTC)


 * Solar panels would make global warming worse. Solar arrays work by converting the energy from the sun into electrical energy.  This electrical energy would just be expended and turned back into heat elsewhere&mdash;there would be zero net difference in the amount of energy in the world, but only a difference of where the energy was located.  There would be a difference in the amount of a energy reflected back into space&mdash;more energy would stay on the planet as the solar panels would presumably be better absorbers of energy than the sand they are shading. &mdash;Bradley 15:35, 27 June 2006 (UTC)


 * This solution, in a word, is preposterous. First of all, reflecting light with white paper would only do exactly that - reflect light.  A large portion of solar radiation is not even in the visible spectrum, so white paper would do little to stop this phenomenon.  Suppose a hypothetical perfect reflector did exist - and we could coat large sections of earth with it.  Reflection would bounce radiation up, but not off the planet &mdash consider the actions of Urban Heat Magnets where large chunks of concrete actually cause more heat.  Finally, I don't believe the Sahara Desert is the cause of global warming - at best, desertification is a symptom.  The assumption that we could halt global climate change by reflecting heat from Earth's lithopause is fundamentally flawed.  It might  make for some fun science fiction, though. Nimur 13:47, 27 June 2006 (UTC)


 * Slightly randomly, I can remember reading somewhere that painting the rooves of every building in the world white would reflect enough sunlight to lower global temperatures by 1 degree C and effectively reverse all climate change so far. Or something like that.--Saxsux 18:45, 27 June 2006 (UTC)

Hold on, my bad physics alarm is going off. People are misstating the greenhouse effect left and right. The greenhouse effect is not that visible light can get down through the atmosphere but not up, that doesn't make any sense. The greenhouse effect is that the visible light coming from the sun gets through the atmosphere, but the far infrared thermal radiation produced by the Earth can't get out again. If the visible light were reflected with white paper, it would remain visible light, and get out just as easily as it got in.

Also, someone implied that because white paper reflects visible light, it doesn't reflect other wavelengths like infrared and ultraviolet. This is not necessarily so. In fact I think white paper is a pretty good reflector of both infrared and ultraviolet.

Turning back to the original question, I don't have a good idea how feasible such a scheme would be, but let me direct everyone to the article on albedo, which is what we would be trying to change by covering the Earth with white paper. —Keenan Pepper 01:50, 28 June 2006 (UTC)


 * Exactly, and the disappearing of the polar icecaps is lowering the albedo. The article actually mentions snow as having a very high albedo and sea (below it at the North Pole) as having a low one. Through this melting process, global warming amplifies itself. The causes of global warming may be difficult to stop (or so we think - but that's a different issue), but fighting this amplification is relatively much simpler (technically, it's a no-brainer). Just add more 'white'. I used paper as an example and maybe took it a bit too far (although that did illustrate the size of the job, a problem that would be the same with painting rooftops white).
 * But I made a much bigger mistake. I picked a desert because that's where you can reflect most radiation. But that would subsitute one problem with another. It would throw the climate off-balance because the sunlight would get reflected from an essentially different spot and we probably can't predict what effects that would have. Total temperature might drop, but that's not the major problem (a common misconception). It's the predictability of the weather (ie the climate) that's at risk. If we don't know what weather we're going to get we don't know what crops to grow and we'll get mass starvation. So we need to put the reflection back where it disappeared, at the poles. Maybe not the best place to reflect (because there's less to reflect) but then we should have thought of all that before (and 'we' did, but no-one bothered to listen). DirkvdM 05:33, 28 June 2006 (UTC)


 * Geoengineering is fun. My favoured solution is to create a parasol in at the L3 Lagrange point, between Earth and the Sun. All you'd need to do is send up a rocket filled with aluminium dust, and blow it up when it gets there. The dust cloud should prevent a few fractions of a percent of the Sun's rays from ever reaching Earth. EdC 01:45, 29 June 2006 (UTC)


 * Nice idea. At first I wondered why a cloud, but it would have to be a cheap solution because of the area that needs to be covered (something like the diameter of the Earth). But wouldn't that get in the way of SOHO and such? These satellites are also essential to prevent us from disaster, albeit technological, because they give us insight into solar flares that endanger satellites that we depend on and even electricity suplies here on Earth. Also, since it needs to be as big as any such solution here on Earth, why put it in a more expensive spot? DirkvdM 07:13, 29 June 2006 (UTC)
 * Ah, the geoengineering article also mentions my proposal of putting up reflecting surfaces. I suppose that's why you put it there. :) DirkvdM 07:18, 29 June 2006 (UTC)
 * You put it in the Lagrange point because it will stay there, if you blow up a container full of dust in orbit it will just disperse and you'll have simply added to the cumulative volume of space junk floating around the planet, in the Lagrange point it'll just kind of condense--71.247.107.238 15:51, 30 June 2006 (UTC)
 * No it wouldn't. L3 is unstable. You'd need to send up another rocket every few months. -- SamSim 14:49, 3 July 2006 (UTC)

What Is the Absolute Temperature... in Heat?
As zero degree Kelvin is the absolute 'cold' temperature, is there an absolute 'hot' temperature?--JLdesAlpins 11:04, 27 June 2006 (UTC)


 * Since heat is the movement of atoms/molecules, one limit to temperature would be the speed of those particles or whatever they break down to at such high temperatures, which can't exceed the speed of light. I don't know what temperature that would correspond to, though. Good question, by the way. DirkvdM 11:11, 27 June 2006 (UTC)
 * The temperature is related more directly to the average kinetic energy of the particles. Although particle velocities can't exceed the speed of light, the energy (and hence the temperature) can become arbitrarily large.  Thus there is no absolute hot temperature. -- SCZenz 11:17, 27 June 2006 (UTC)


 * Scientifically speaking heat and temperature are two different things. - Mgm|(talk) 11:15, 27 June 2006 (UTC)
 * Yep, but he's talking about temperature. -- SCZenz 11:17, 27 June 2006 (UTC)
 * I'm just glad that we cleared up the fact that there's indeed some sort of difference between kelvin and kelvin.Loomis 12:05, 27 June 2006 (UTC)


 * Aren't there just six degrees of Kelvin?--Shantavira 13:05, 27 June 2006 (UTC)
 * Since temperature is the average kinetic energy of a substance, a gas (or plasma or something) in the limit of its particles moving at the speed of light would have an infinite amount of kinetic energy (according to special relativity), which would be an infinite temperature. So, no, I would say there is no top temperature value.  Of course no one really knows what happens at arbitrarily high energies; that's why we build particle accelerators, so the concept of temperature probably becomes a little silly at some point.  --Bmk 13:20, 27 June 2006 (UTC)
 * In fact, particle accelerators and other scientific experiments or theories that deal with the realms of very very hot objects rarely speak in terms of temperature - instead, energy is the defining parameter. Temperature is a sort of approximation of energy content that loses meaning outside of normal circumstances.  It may even be inappropriate to discuss temperatures in very low-energy physics (the realm of absolute zero.  Nimur 16:17, 27 June 2006 (UTC)


 * Absolute zero temperature is when all the particles in a system exist in the Ground state. As the temperature increases, more particles will be in excited states.  Under normal circumstances, any particle is more likely to be in a lower-energy state a than higher-energy one, and the ratio between these probabilities is a function of temperature, known as the Boltzmann factor.  According to this definition, temperature can increase without limit; the higher it becomes, the closer the states become to having equal probability.  So the answer to your question is no, there is no "absolute hot" temperature.  (As an aside, in certain circumstances, you can have more particles in a given excited state than the ground state, for example in a laser. In this situation, the expression for the Boltzmann factor fits mathematically with a negative temperature, but this doesn't really count because the system isn't in thermal equilibrium.)  Arbitrary username 16:37, 27 June 2006 (UTC)


 * Yes, there is; it's called &minus;0 K. See Negative temperature and −0 (number). Melchoir 18:07, 27 June 2006 (UTC)
 * Neat article! One learns something new every day. Thanks Melchoir.--JLdesAlpins 17:21, 28 June 2006 (UTC)

Homework help needed, thanks
I am due to hand in some material in a few days, so help with the following questions would be appreciated. Thanks!


 * The semiconductor germanium has a bandgap of 0.67eV and effective masses of me* = 0.550me and mh* = 0.37me where me is the electron mass.

i) calculate the Fermi energy of Ge at 300 K in eV. ii) calculate the electron concentration in the conduction band for Ge at 300 K.
 * Lol, I've just finished a course in solid state physics. I can't answer this instantly, and have no time now. But it'll be curious to try to solve this say tomorrow. ellol 18:41, 27 June 2006 (UTC)


 * To what extent is the interpretation and analysis of SAR imagery different from that of multispectral optical imagery?


 * The accessible potential range for a Hg electrode in 0.1 M HNO3 is approximately 0.5 to -1.5 V vs SCE. Explain the term "accessible potential range". Describe the processes that determine the accessible potential range of a Hg electrode.


 * Discuss the production of biomass by filamentous fungi.

202.36.179.65 11:34, 27 June 2006 (UTC)


 * As it says at the top, we're not here to do your homework for you - please do it yourself. If you have a problem with a specific point, we can help you to understand the concepts you're having trouble with, but we won't just answer the questions you were set for you. &mdash; QuantumEleven 11:42, 27 June 2006 (UTC)

Cheat/trainer programs
How do they do it? Where can I learn how to make those cheats for games? Thanks.


 * Almost all of the cheats are programmed by the developers of the game themselves and are released to the press sometime after the game is released. Although you can cheat in a game by changing some of the files or by using a hex editor(?), the only way you can make cheats for the game is by incorporating them into the program code of the game. Jayant, 17 Years, India  • contribs 12:38, 27 June 2006 (UTC)


 * Trainer programs, unlike cheats, alter your save file for a game. For example, you may be playing a game that requires money to buy cool weapons and armor.  So, you run a trainer on your save file that gives you tons of money.  Then, you start the game, reload your file, and you have a lot of money.  Trainers are developed in two ways.  The most effective is to save a game, change one thing, and save it again.  Then, look at the save files to see what changed.  From that, you can make guesses at what needs to be changed to make other things happen.  The bad way to make a trainer is to randomly change the save file and see if anything good happens. --Kainaw (talk) 13:48, 27 June 2006 (UTC)

Basically it involves reverse code engineering the save file.VdSV9• ♫ 14:16, 27 June 2006 (UTC)


 * In some cases trainers alter the memory of your computer on-the-fly, instead of altering your saved games. --Kjoonlee 16:38, 27 June 2006 (UTC)
 * Yeah, I thought most worked by accessing the game's memory mid-game and changing hex values and such to give you extra health and such. Ones that edit your save game exist as well. Recently I used a hex editor to edit my Fallout saved game to "teleport" around the map, which was interesting. See Trainer (games). Sum0 20:56, 27 June 2006 (UTC)


 * Also, in many cases, "cheats" were originally coded by the developers to speed up play-testing. For instance, a level skip cheat that allows you to pick a level would also be handy for a developer who had found a bug in level 8, tried to fix it and now wants to test it out. --ByeByeBaby 14:00, 28 June 2006 (UTC)


 * MegaGames is one of the best "underground" gaming websites. They provide gaming news, software reviews, trainers, game patches, and such. Nothing illegal though, so it's all safe. You can also try out their forums if you want your question answered in more detail. The answers above do cover all aspects though. Cheats are built into the game by developers, and trainers edit hex values either in your computer's memory on-the-fly, or in a saved file (saved-game editor). --Russoc4 17:50, 28 June 2006 (UTC)

Vegetation vs Urbanisation
Hi! Neverseen urbanisation throughout the globe urged me to ask the wiki users, the following questions : #1. Are there any national/international laws pertaining the FOREST COVER of a country/ the world as a whole ? #2. If yes, how flexible are they ? #3. Don't you think it's high time, that something like "ONE PERSON-ONE HOUSE" policy be implemented ? Thanking you, Pupunwiki 12:10, 27 June 2006 (UTC)

In the US, there are no nationwide forest cover laws (that i've heard of). There are individual protections for specific forests, such as those designated as national parks or wildlife reserves, but many of those can be tossed out by a convenient executive order. I'm sure there are people who can write in more detail about this. And about the "one person one house" idea, I think it would be nice, but I don't really think it's that much of a problem; the number of rich people with multiple houses can't be that huge, right? I feel like there are many more pressing problems, like, "two people, one car", or "two people, no car and instead a bike or a good public light-rail system". Please explain if you disagree - i'd like to hear :)

On the other hand, if we could find a way to eventually stop all new housing construction and build "up" and "down" (as in in towers or underground), now that would be valuable. The increasing suburban sprawl around the country is an excellent problem to solve. Also, could you explain the first part of your question? ("Neverseen urbanisation throughout the globe") Is that some kind of organization? Thanks --Bmk 13:29, 27 June 2006 (UTC)

Remember that vertical mass housing has been proposed and built repeatedly since the first half of the 20th century. In nearly all cases (examples of exceptions welcome), in cities or apart, vertical high-density housing of poor people has resulted in dangerous and unhealthy squalor condemned by everyone even when the buildings initially provided a higher level of housing than most of them lived in before. Given a choice, people build out rather than up. alteripse 15:53, 27 June 2006 (UTC)


 * First, the US President can't just destroy a National Forest with an executive order. Perhaps limited logging could be performed, especially to remove undergrowth which leads to forest fires, but that's not the same as destroying the forest.  Secondly, housing takes up only a small portion of land area.  Food production, on the other hand, takes up huge swathes of land, and is quite harmful to the environment, especially when the "slash and burn" method is used to clear land.  Limiting population and moving to vegetarianism have potential to limit food demand.  Unfortunately, the increasing affluence in China is leading them to eat more food and a higher proportion of meat, which requires significantly more land per calorie to produce than other foods.  This has led to deforestation in countries which supply China with food, such as some in South America. StuRat 16:05, 27 June 2006 (UTC)


 * One man one house? We'd either have to build very high or occupy way too much land. A rough guess is that the average population of a house is about 5 people (1 billion houses in the world?). In the Netherlands there are 7 million houses for 16 million people. In most parts of the world, though, you'll find much more people in one house. Such as around the Mediterranean, but in third world countries it'll be even more.
 * I suppose you meant one house per family. But how do you make such a rule? Who determines what a family is? Or a house, for that matter. DirkvdM 06:48, 28 June 2006 (UTC)

To Bmk : First of all,thanks for understanding 'One man One house' policy rightly(it really becomes ridiculous if seen from different angle... as pointed out by DirkvdM ). And that's certainly not any kind of organisation.I think my poor vocabulary has led to the confusion. Probably, a comma between urbanisation & throughout, and another between globe & urged, may help you to understand me better. Lastly, can you be more precise, in what ways exactly, the said problems are pressing ?

To alteripse : You do have a substantial point, but, think of the situation 100-200 years hence ...

To StuRat : Housing may occupy a negligible portion of land, but remember, once a house is made, it permanently blocks the land for any kind of vegetation... I mean to say, in few cases, after the owner shifts, it is left like that(to be haunted !?!?). And if a bulldozer follows, you may be well assured that,a new construction is in the making. Rarely(rarely to the power of infinity), would you find a bulldozer paving the way for 'green canopies of the future'. Now think of the no.of such cases in your locality, then estimate what figure you would get from the whole world. That's why I think a man should have only one house to his name.Keeping the rate of deforestation in mind,it may play an important role in future. Your information on China is interesting. Thanks.


 * The houses don't require bulldozing to have the land returned to nature. The yards can grow trees immediately once abandoned, and the house will collapse and decay in a few decades.  Eventually the original plant life would return and there would be no sign man was ever there. There are many historical settlements which have gone through this entire process. StuRat 02:04, 29 June 2006 (UTC)

To DirkvdM : You misunderstood the policy (it's not your fault!!)...See Bmk's reply,you will understand. And I too agree that it's very difficult to DETERMINE a HOUSE.Perhaps, annual income of an individual may be an yardstick of the standard of the house he/she lives in.

Thanks a lot, Pupunwiki 09:42, 28 June 2006 (UTC)

Pupunwiki, all these spaces at the beginning of lines puts grey boxes around them, which makes your post rather hard to read. DirkvdM 19:12, 28 June 2006 (UTC)


 * I fixed the format problem. StuRat 02:04, 29 June 2006 (UTC)

StuRat, Thanx for your comments, & Thankxx for your formatting. - Pupunwiki 06:08, 29 June 2006 (UTC)


 * Now you try it yourself with your last entry. And the first one, while you're at it. Come on, you can do it! :) DirkvdM 07:21, 29 June 2006 (UTC)

Can you catch AIDS from a tick bite?
If a tick had been feeding on someone with AIDS before it started drinking your blood, would it be possible to get infected? --84.65.204.64 14:01, 27 June 2006 (UTC)


 * Ticks suck blood. They do not open a hole in a blood vein and inject blood into it.  Now, if the tick hit just the right spot and was a very messy eater... --Kainaw (talk) 14:36, 27 June 2006 (UTC)
 * I don't understand your answer. There is no question whether ticks are a major disease vector - you can definitely get diseases from a tick bite, notably Lyme disease - see tick-borne disease.  The real question is, can you particularly catch HIV from a tick bite?  I can't seem to find a good answer.  It isn't on the list of common tick-borne diseases, but that doesn't mean it isn't possible.    --Bmk 14:48, 27 June 2006 (UTC)


 * I believe that I explained exactly why the blood-born virus that causes AIDS is not transmitted by ticks. Of course, there is always room for that one case where a tick transmitted the virus, just as there are extremely rare cases where a fly and a mosquito transmitted Lyme disease.  By the way, Lyme disease is a bacterial infection from the tick.  After a tick burrows for about 12 hours, the bacteria on the tick spread into the host's skin.  Removing the tick doesn't remove the bacteria and Lyme disease starts.  It doesn't have anything to do with mixing up blood between the host and the tick. --Kainaw (talk) 15:02, 27 June 2006 (UTC)
 * Lyme disease is indeed a bacterium, however numerous other diseases known to be transmitted via ticks are viruses like HIV. For instance coltivirus, which causes Colorado tick fever, and types of meningoencephalitis which are caused by a flavivirus.  When ticks bite into the skin, they secrete anticoagulants and immunosuppressants, both of which facilitate the drawing of blood for the tick and incidentally the passage of many different kinds of pathogens into the host.  --Bmk 15:14, 27 June 2006 (UTC)


 * In the case of HIV, no. The enzymes that biting insects use to digest their blood meals are also quite effective at inactivating and digesting HIV.  The human immunodeficiency virus is actually pretty delicate, as viruses go.  It falls apart with very little provocation.
 * I'll note in reply to Kainaw's comments – which are a bit terse – that viruses transmitted by biting insects are (practically) never spread by direct transfer of blood from one host to another on the outside of an insect's proboscis. Rather, the virus must be capable of infecting and reproducing in both human and insect hosts.  An uninfected insect will bite a human (or other) host, and become infected with the virus.  The virus then spreads throughout the insect's body, eventually infecting the salivary glands, and contaminating the insect's saliva with virus...which then can infect new animal hosts when the insect bites.  Unless a virus is adapted to growth in the insect host, the insect can't become infected and 'contagious'. TenOfAllTrades(talk) 15:15, 27 June 2006 (UTC)


 * Interesting... could one of y'all please write a note on Tick-borne disease? It seems relevant to mention diseases known not to be transmitted. Melchoir 18:03, 27 June 2006 (UTC)

the same question on mosquitos was answered (sorry, no source) in addition to the above with the points:
 * HIV is rare in the blood and mosquitos contain only a tiny tiny bit of blood. Very few samples of the virus are in that quantity of blood, further reducing the chance that the even tinier bit that could get re-injected would contain some.
 * HIV sucks at surviving. The virus dies quickly after the tiny blood sample is drawn.

I/O current booster
I would like to sink and source around 100 mA per I/O but most microcontrollers can only sink or source 20 mA per I/O. What type of device can I use to boost the current I can sink or source from an I/O? I've looked at a darlington driver but from my understanding, you can only sink current from such a driver.

The project uses two pin bicolor LEDs, on one pin, there will be a 2.5 V source from 5 V using a voltage divider, then on the other pin a logic output. If the output is LOW, the LEDs will be one color, then if the output is HIGH, the LEDs will be the other color. Since the array of LEDs will draw more than 20 mA, I cannot directly use the I/O. --Jcmaco 15:14, 27 June 2006 (UTC)


 * The most fool-proof method would be to use an op-amp or comparator to drive the LEDs. The less fool-proof method is to use a PNP and NPN transistor, but then you have to worry about dead time (when both transistors are off) when you switch between them or else you'll have shoot-through where the positive end of the supply is directly, albeit briefly, connected to ground&mdash;which is bad.  The transistor design is called a push-pull design.  I would definitely go with the op-amp or comparator design as they are cheap and small. &mdash;Bradley 16:19, 27 June 2006 (UTC)


 * Consider an H-bridge to boost current output. Or, you could use a current divider (two different resistors in parallel, and then connect the lower-current, higher resistor to your IO input)... but why in the world are you trying to sink current into a microcontroller? Perhaps your best solution is an external analog to digital converter? Nimur 16:21, 27 June 2006 (UTC)


 * I use the 74AS1034 for that sort of thing. It has TTL inputs and its outputs can source and sink 48 mA. --Heron 17:46, 27 June 2006 (UTC)

same chance of getting the HIV as dying within the next year
My question: how accurate is my conclusion at the bottom?

I'm not very good at math so this could all be wrong...

Thanks, ~PEter

(see table on the right of AIDS for background)

Consider the following:

I am a white male, 31 years old.

127 out of 97,276 of my kind died on our way to become 32 years old.

(from the 2003 life table, table 5)

Now granted, my life is fairly mundane and I'm fairly healthy too unlike a lot of those 127 who died so let's account for accidents first.

30.4% of deaths by those aged 25-34 were by accident. [http:// http://www.cdc.gov/nchs/data/nvsr/nvsr53/nvsr53_17.pdf PDF file on causes of death, go to Table 1]

So that accounts for 0.304*127 = ~38.6 deaths.

Let's say I'm liable for another 10% in all those categories (I mean, the vague, "All other causes" is 20% itself)

0.10*127 = 12.7 deaths

12.7 + 38.6 = 51 deaths out of 97276 guys who are my age and act like me

51/97276 = ~0.052% chance of death for someone like me

Conclusion: A guy like me has the same chance of getting the HIV from having unprotected penile/vaginal sex with a woman (a woman who definitely has the HIV) as a guy like me has of dying before I age another year.


 * Does this mean that people in South Africa are just really unlucky (AIDS)? &mdash;Bradley 15:57, 27 June 2006 (UTC)


 * I dont mean to stomp on any theories, but you might take a look at the diagnostic criteria for AIDS in the African continent. In many places, malaise, diarrhea, and fever are all that is needed for a diagnosis. (Sorry for the lack of citation, I'll post it when I look for it, I don't have time now).Tuckerekcut 16:28, 27 June 2006 (UTC)


 * Hey, I'm only talking about doing it one time, not scores and scores of times like those South Africans. ~Peter


 * Without delving too deeply into your math, I'd agree that the odds of dying from having unprotected vaginal sex once is about the same as the combined risks of everything an average man of your age does in one year (including car crashes, workplace accidents, murders, illnesses, food-poisoning, etc.). That seems like a lot of risk to roll into one day's entertainment.  Since the odds are roughly equal to a whole-year's worth of average risk factors, some people might look at it as (on average) taking a year off your life.  Why would you want to do that? Johntex\talk 19:45, 27 June 2006 (UTC)


 * This is comparing all risks within a year with a specific risk from an activity probably measured in minutes - or am I missing something? Peter Grey 04:46, 28 June 2006 (UTC)
 * No, I don't think you are missing something. it's not that dissimilar to comparing the risks of cancer from radiation in a nuclear accident to your risk of cancer from dental x-rays taken in small doss over your life.  You can always compare the risk of A to the risk of B, regardless of whether A and B take the same amount of time or not.  In this particular case, it would appear that the chances of a 31 year-old white male dying by the time he is 32 are approximately the same odds as getting HIV from one infected sexual encounter (vaginal sex, no condom) with an affected woman. Now of course, the HIV will take longer than 1 year to actually kill you, but it will kill you if you don't die from some other cause first.  Johntex\talk 05:15, 28 June 2006 (UTC)


 * kind of interesting, no? ~Peter

Age progression software
Yeah, software like used for photos of missing children.

One: Is it publicly available?

Two: Can it regress a photo, take someone as an adult and show what they looked like as a kid? --Penta 15:49, 27 June 2006 (UTC)


 * I can't answer those questions, but would like to point out that the software only does an "average" aging process. It can't account for differences due to scars, tattoos, hair style changes, weight changes, etc. StuRat 16:12, 27 June 2006 (UTC)


 * Yes, even the best commercial softwares are best-guess and probably use a lot of manual image tweaking by a skilled operator/graphic artist to perform adjustments and generate an accurate output. Nimur 16:26, 27 June 2006 (UTC)


 * I was looking for this kind of thing a little while ago and found, with help from the Ref Desk, the following sites: www.infoscotland.com/experience and www.perceptionlab.com. If you're looking to make funny pictures of you and your friends then they can do that, including making you younger.  But the results will be at best funny - not for any serious purpose.  But if that's what you're after...  --The Gold Miner 17:11, 27 June 2006 (UTC)

Electro Convulsive Shock Therapy
When/Where was the first ECT treatment done in the late 80's following it being out of practice for a period of time? Vicki


 * It was first used in the 1930s. See Electroconvulsive therapy, also the discussion at Talk:Electroconvulsive_therapy and this site. --Shantavira 17:52, 27 June 2006 (UTC)

AIDS/HIV infection
I posted the question lat month, and two people did within the last two days. Ok, so the man has about a 0.05% chance of becoming infected during vaginal sex (approximately, I don't remember). This seems to be another example of politicized science gone bad. I am fed everyday from public service announcements, and knowledgeable people that if you have sex one time with a girl that has HIV you are going to be infected, and die a slow, horrible death. I was fed the same bullshit about pot two years ago! What the hell is going on, can't we just tell kids the truth, and not have it blown-up past fact into fiction just to scare us out of doing something? —  The   Mac Davis ] ⌇☢ ญƛ. 17:40, 27 June 2006 (UTC)
 * yes, that's exactly it, you've discovered the truth, HIV isn't real at all, in fact it's as fake as global warming, evolution, the moon landing, the actual moon itself (just a big circular bill board suspended in geosynchronous orbit around the Earth at an altitude of 500 ft, which is pretty hard considering that the Earth is not only flat, but rectangular as well), toothpaste, cavaties, cancer, dinasours, and of course quantum mechanics and public education. Virtually all science in the world is actually an elaborate conspiracy to keep upper middle class white people from really small towns from having a good time on weekends!--64.12.116.74 17:55, 27 June 2006 (UTC)


 * Mass Media is aimed at the dumbest majority in the nation - those who cannot understand the concept of blood-to-blood transmission. --Kainaw (talk) 18:06, 27 June 2006 (UTC)


 * Independent chances add themselves. Did you have sex only once in your life ? If you buy a gun, there is less than a scruple of chance that you once kill a man. If millions of guns are sold, there shall be violent deaths and rich lawyers and populated jails. --DLL 18:35, 27 June 2006 (UTC)


 * Many thanks for the multitude of mature adult reponses to Mac's question. Mac, one of the disavantages of having a free expression is some people will not use that freedom responsibly, and use it instead to phony up, inflate or dismiss serious subjects.  Keep that in mind next time you hear something from someone who does not have any obligation to play it straight.


 * Rounding slightly from the figures in our HIV article, you can see that the odds of a man getting HIV from unprotected vaginal intercourse with an infected woman are about 1 in 1,000. Currently, there is no cure for HIV, so if you get it, you will die (unless you die from something else first).  The risk may sound small to you, but before you dismiss it, please consider risks adding up as you have sex more often, or if you consider larger numbers of people having sex.  For example, the Chicagoland area includes 10 million people.  If half of those are men, and half of those men are sexually active, that gives us 2.5 million people.  If they each take this 1 in 1,000 risk just once, then you would expect about 2,500 people to die from this one indiscretion.  Of course, we are talking about the risks for heterosexual men since that is the question you asked, other sexual acts, such as receiving anal intercourse, carry higher risks.  To bring it back to a more personal level for you, let's suppose you meet an HIV infected woman and date her for a year, having sex regularly.  How many times might you have sex in that year? 50 times? 100 times?  Maybe more?  If you have unprotected sex with her 100 times over that year, you now have about a 10% chance of dying from your actions.  Would you board a plane if you knew there was a 10% chance of it blowing up? Johntex\talk 19:30, 27 June 2006 (UTC)
 * Your chicagoland comparison is unrealistic because it assumes every woman (or the one woman servicing all 2.5 million active guys) is infected. I would also suspect that far more than 50% of men fall short of the 'active' category.  As far as planes go, they are by far the safest way to travel (beating cars and all other land-bound methods) and there are still people who insist it's too risky (they drive instead, raising their risk of death significantly).  There are also guys who will have sex with a woman without protection simply because she insists she is on the pill (or conversely, women when men insist they will pull out).  Humans are very bad at assessing risk, especially when 'other motivators' are in play.  Knowing the facts is nice, but to have the perspective to make rational decisions from it?  Keep dreaming!
 * I think you miss the point about the Chicagoland example. I never said it would happen in one day.  I am just making a point about the consequences when many people all decide to engage in an activity that seems to have a small risk.  Those risks add up to a big effect over the whole population.  As to whether 50% of the men are "active" or not, I have only assumed them to each have sex one time, so that is not very active.
 * I don't see how your point about air travel has any relevance. You are confusing what is traditionally true of airlines (the fact that they are safe) with the hypothetical example posed above - which is that a specific plane has a 10% chance of blowing up. If the airplane example confuses you because of your predisposition to think of planes as safe, then use this example instead:  "Would you eat a piece of pie if you knew it had a 10% chance of killing you?"
 * Well, what if the pie was really really really really good, lasted more than a minute, and you had a 0.01% chance of dying in 30 years? —  The   Mac Davis ] ⌇☢ ญƛ. 00:18, 28 June 2006 (UTC)
 * Well, everyone's got to make their own decisions, but I don't know where you came up with the numbers you just cited. Johntex\talk 00:47, 28 June 2006 (UTC)
 * As for you statements about people being bad at assessing risk, I agree with you, but your comment to "Keep dreaming" misses the mark and is insulting. Some people here are asking honest questions and seeking the best answer they can get.  If you don't like the facts, you don't need to read or post here. Johntex\talk 21:38, 27 June 2006 (UTC)
 * My answer to the plane question is no, but maybe if the chance were .1% It is also untrue about there being no cure for HIV.  There are some rather drastic cures, if it is caught soon enough (while the body is still healthy enough to survive the cure).  One of these is thermal therapy, taking advantage of the viruses vulnerability to temperature.  It involves heating a person up to about 120F which is hard on the body, but fatal to the virus.
 * It would be great if you could provide some sources for that informaiton aobut the heat treatment. Our article on HIV does not mention it.  In fact, our article states "HIV infection is a chronic infectious disease that can be treated, but not yet cured."


 * Sorry, I read it in a science magazine years ago and could not quote the issue if my life depended on it. I will see if I can find some reference.
 * Well, I tried and found a reference on the search page which says it was not very effective, but when I tried to find that in the article I could not. I will keep searching but not much hope.


 * Our article does go on to state "Post-exposure prophylaxis (PEP) with a course of antiviral drugs is also thought to reduce the risk of seroconversion after high risk exposure (unprotected anal or vaginal sex) to HIV. To be effective, it must be started as soon as possible after exposure and no later than 72 hours post-exposure. The treatment for HIV lasts four weeks. While there is compelling data to suggest that PEP after HIV exposure is extremely effective, there have been cases where it has failed."  So, our article holds this up as the most effective early onset treatment, and we do not lael it a cure.  Johntex\talk 21:18, 27 June 2006 (UTC)


 * Mac, no matter what the US media is feeding you (btw, there are plenty of other resources for information if you choose to look for them), please realise the risk involved. According to the chances of being in an aircraft accident are 1 in 11 million. These odds have been achieved by making every aspect of flying as safe as possible since in the event of an accident the price is high on the passangers.
 * I encourage you to follow a similar route in your sexual practices and ensure the safety and well-being of you and your bedfellows by taking precautionary steps such as using condoms and engaging in low-risk sexual activity with partners whose sexual history you don't know.
 * Most importantly: DON'T EVER have sex with anyone if you have a suspicion that you might be infected with a sexually transmitted desease! Go get yourself regularly tested. It's often free and always confidential.
 * That said, have fun ;-) --Swift 22:35, 27 June 2006 (UTC)


 * Don't get me wrong guys, I'm not some little kid that got his feelings hurt. Thanks for caring enough to tell me to wear a condom though. Hmm.. that sounded weird. Its not something new to me, or that for the first time I have discovered I've been lied to. Frankly, I would not be exagerrating if I said I didn't take anything anybody said to be true until I checked it out first. At times I just can't believe how little normal people know about things they should know about! I always wondered if there were actually stupid people that needed to know the " does not prevent transfer of sexually transmitted diseases such as HIV." Thanks whoever said that. For instance politics. A lot of people that have an opinion on something don't exactly have a clear idea of what it is that they have an opinion on or both sides of the arguement. The weakly-minded and unpassionate are just sitting ducks waiting to get steamrolled by someone that knows what they are talking about and are passionate about a subject. What he says, they will believe to be true!! Confidence trick! I understand why someone may have good intentions (or just be a helpless disease vector) by blowing-up some threat, like sexually-transmitted diseases, marajuana, and most collective hysterias. But is blatantly lying the way to do it? Relax guys-that-are-worried-about-me-getting-infected, I'm not getting much, besides, I'm only 14. Also, to add, it seems only 0.5%-1% of people have HIV in the United States. —  The   Mac Davis ] ⌇☢ ญƛ. 00:15, 28 June 2006 (UTC)
 * I don't know what your teachers/parents/ministers/whoever told you, but it is quite possible they have not lied to you. They may consider these risks to be quite high in their opinion - especially since it is an avoidable risk.  Not many of us can do without our cars, but we can take steps about our sexual behavior.  Also, there is something called Probabilistic risk assessment, which attempts to take into consideration not only the probability of something happening, but also how bad the consequences are.    Finally, keep in mind that statistics are not the whole story.  It may be that less than 1% of the people in the US have HIV, but those people are likely to be the ones having the most sex.  In other words, on a per-person basis the odds may be less than 1%, but on a per sexual-event basis the odds may be higher than that that your partner is infected because infected people may be engaging in sex more often and therefore are participating in more sexual events. Johntex\talk 00:47, 28 June 2006 (UTC)
 * look all I ever wanted was to have sex one time with a HIV-infected prostitute and live 10-15 years to tell the tale. In my book, that's worth possibly signing one paper in a batch of 999 blank sheets and one post-dated death warrant. ~Peter
 * OK Peter, do what you want. BTW - our figures in the HIV article are for sex without a condom - the condom is 87% effective (sometimes they break or slip off or don't fully cover all of the penis).  So, if you use a condom you can improve your rates a little more. Johntex\talk 04:39, 28 June 2006 (UTC)


 * Might i ask, do you play the lottery? I only ask because there is a much much greater chance of you dying from an HIV related disease after a single sexual act with an infected individual that there is you winning any national lottery in your whole life. It appears illogical to me to consider a 1 in a 1000 risk acceptably small when the payoff is your life. Yet a 1 in several million chance is worth a punt for a financial windfall. That, to butcher Einstein, is relativity for you.  Rockpock e  t  08:17, 28 June 2006 (UTC)
 * No, I don't play the lotery because I know I'll never win--there is no chance. --User:Mac_Davis
 * You can live 10-15 years with HIV these days anyway&mdash;assuming you have heath care. So, I see no problem for you.  Of course, if you are then infected you stand to spread the disease around for the next 10-15 years. &mdash;Bradley 16:12, 28 June 2006 (UTC)


 * Y'all just don't understand my Weltanschauung. Sorry. ~Peter
 * Or maybe you don't understand ours? Besides, you've yet to provide any evidence you've been lied to, or that these numbers are incorrect. Johntex\talk 07:12, 29 June 2006 (UTC)
 * It's a public policy consideration. If 1 in 2000 unprotected sexual contacts passes on HIV, and 1 in 50 people are infected, then assuming USAians have sex once a week, that's 400 new infectees a night. That's a lot, from a public health point of view. Sure, the individual risk is small (you'd need to have over 1000 unprotected sexual contacts for your chances to reach 50-50) but exaggerating the risk does make sense. At the very least, it stops the unlucky ones moaning about why they weren't warned.
 * About your worldview - look, you seem rational if a little naïve. The best way to cope with the stupidity of the masses and the venality of the élite is to cultivate your cynicism: yes, the rulers are lying to the workers, but 'twas ever thus, and it's not as if the plebes would thank you for pulling the oh-so-comfortable wool from their eyes. When you realise you've been lied to, know that it's not you the lie was aimed at. After a while you'll realise that it really doesn't matter. EdC 02:38, 29 June 2006 (UTC)
 * I like this EdC! In some ways he reminds me of Meursault, in others he does not. Thank you for your comment EdC. ~Peter

Chemistry
My summer school teacher was explaining how scientists had found out things about atoms and whats in them, he was also discussing the Periodic Table. When I was looking at the Table a question popped into my head how did the scientists come up with the number of protons in each element? Especially when it took them so long to find out about electrons then neutrons. Thank You in advance.
 * See atomic number and then proton (specifically, the history section). &mdash; Lomn | Talk 20:37, 27 June 2006 (UTC)

What do I have to do to work in Intel/AMD?
As a microprocessor engineer or something related to high-tech design and/or manipulation.


 * Try writing them a letter with your CV attached... EVOCATIVE INTRIGUE   TALKTOME  |  EMAILME  |  IMPROVE  ME  23:06, 27 June 2006 (UTC)


 * But first, if you don't already have the requisite qualifications, you probably need a degree in electronic engineering and probably specialising in computer engineering. --Robert Merkel 02:48, 28 June 2006 (UTC)


 * Any possible connections help. Find anyone you know who works there, ask who their manager is, and shoot them an e-mail of interest.  Odds are they've had a situation like this before and they'll know how to hook you up.  One strong truth though: you're not likely to catch anyone on the phone, email is the best way to contact them. -- BUSY 06:28, 28 June 2006 (UTC)


 * Depending on your age, you may also want to get an internship with them. I don't know how widespread summer internships with technology companies are, but if they exist they can help you gain inside connections (which help in getting a high-demand job).--69.171.123.148 21:01, 2 July 2006 (UTC)

tramadol
how long does tramadol stay in your system?

--68.64.190.240 22:59, 27 June 2006 (UTC)


 * According to Tramadol, nobody is sure:


 * The mechanism of action of tramadol has yet to be fully elucidated, but it is believed to work through modulation of the GABAergic, noradrenergic and serotonergic systems. The contribution of non-opioid activity is demonstrated by the analgesic effects of tramadol not being fully antagonized by the μ-opioid receptor antagonist naloxone.


 * Hope this helps in some way. EVOCATIVE  INTRIGUE   TALKTOME  |  EMAILME  |  IMPROVE  ME  23:01, 27 June 2006 (UTC)

I slipped down a flight of stairs in Costa Rica. their pharmacy gave me tramadol for pain. (thats right, you don't need prescriptions over there for just about nothing). I came back and was drug tested at work 3 days later. i did not have or need a prescription in Costa Rica. now i have trouble on my hands. will this tramadol show up in a drug test 3 days after taken? --68.64.190.240 23:08, 27 June 2006 (UTC)


 * Erowid informs us that Tramadol is not usually tested for in drug tests and has a half life of ~7 hours. "So unless a urine sample is being sent in to a laboratory, it is unlikely that Tramadol will cause any sort of positive test result." 128.197.81.181 23:25, 27 June 2006 (UTC)