Wikipedia:Reference desk/Archives/Science/2014 May 19

= May 19 =

Games that computers can't play
I thought that since this isn't a troubleshooting question, this was a more appropriate forum than the Computing desk.

My question, basically, is are there any games that computers simply cannot play, for whatever reason? Given the right programming, computers can easily play (and win) a game with high complexity, multiple game pieces of varying function, and fine strategy such as chess, and a mathematical puzzle-game like sudoku would probably be orders of magnitude easier for a computer to complete in a fraction of the time. A computer could probably solve a crossword puzzle, given access to information of the sort Watson had when he took down those Jeopardy! champions, though there's obviously very little entertainment value in watching a computer solve a crossword, at least more than once or twice.

What I'm wondering, though, is if there are any games that are simply too complex for a computer to understand and/or put into practice. To come up with a workable definition of "game," I guess it helps to narrow things down. There are certain intellectual pursuits that computers are obviously not capable of (yet?); a computer couldn't compose an essay on Shakespeare, for instance (or at least not one that contains any original ideas), but we wouldn't term that a game. On the other hand, a computer is absolutely capable of analyzing data sets and finding statistical patterns, instances of correlation between different sets, etc. That isn't a game, either, but it is more pertinent to how some board games work. Literary criticism, though, is just a tad more complex, and a bit too abstract.

So I guess we'll impose the requirement of some level of strategy being involved, and a multi-player format, as in chess, checkers, or most card games. Charades has a physical component that makes it hard for a computer to put into practice&mdash;though I suppose a particularly language-savvy computer with a large library of pre-recorded gestures might be able to keep up. Drinking games and paintball are similarly outside the reach of computers for physical reasons, but are there games that are beyond computers' capacity for (for lack of a better term) intellectual reasons? Evan (talk&#124;contribs) 04:25, 19 May 2014 (UTC)


 * Game complexity may be relevant. Among widely played "chess-like" games, Go has been famously difficult—see Computer Go. -- BenRG (talk) 04:38, 19 May 2014 (UTC)
 * Despite the plethora of soccer robots, true bipedal soccer robots are still no match for a human. Bipedal robot control usually depends on inverse kinematics, and state-of-the-art algorithms suffer from instability, slow speed (i.e. solutions cannot be computed fast enough), and poor error recovery.  These are mathematical problems that present-day computer software can not easily solve, even though there has been a lot of research in this exact topic.  To be clear: this isn't a mechanical problem - it's a software problem.  The actual moving parts in a bipedal robot are perhaps expensive but they are not very complicated.  It is the control algorithms that suffer from numerical instability and computational complexity.  A robot with two legs has, in addition to the usual multidimensional kinematics matrix, a branched kinematic chain topology.  That means, for example, that the robot doesn't know which foot is on the ground, and which one is in the air.  As easy this identification-task is for a human brain, it is a difficult challenge even for a supercomputer.  If you can write a software program to answer that question, you've got yourself a solid career as a robotics programmer!  Nimur (talk) 05:11, 19 May 2014 (UTC)


 * There are games that are based on creativity and storytelling, such as role-playing games and perhaps the ultimate, Calvinball. 88.112.50.121 (talk) 10:34, 19 May 2014 (UTC)


 * Computer game designer Chris Crawford (game designer) distinguished between a competition where a player can only outperform the opponent, but not attack them to interfere with their performance, and a game where attacks are allowed. By this logic a computer can't play a game with you unless it can attack you. 84.209.89.214 (talk) 15:02, 19 May 2014 (UTC)


 * Let's be clear that when you ask whether computers could play a certain game, what you are really asking is whether programmers would be able to figure out how to write a computer program that could play the game successfully. There are certain things that people find easy but are very difficult to write programs for.  For example the game Who Is This?, in which you show the contestant pictures of famous people doing various things and ask for identification, would be extremely difficult to program on a computer.  Another game that would be very difficult to program is Twenty Questions. Looie496 (talk) 15:20, 19 May 2014 (UTC)
 * This online version of Twenty Questions is actually pretty good with common objects. I got it to "hairdryer" in twenty-two questions. Evan (talk&#124;contribs) 16:22, 19 May 2014 (UTC)


 * In Pictionary, I would expect a computer to be very good at drawing pics, as long as it had a pic in memory for the word in question, but very bad at recognizing pics drawn by people. More generally, any game that requires the computer to do visual processing of an image to determine what it's seeing will be problematic.  Even Watson didn't do character recognition, but rather they fed it the questions as ASCII code.  (I don't imagine it would have been a problem to recognize the consistent, printed text used on Jeopardy, but reading cursive handwriting, etc., would have been more of a challenge.)  StuRat (talk) 15:27, 19 May 2014 (UTC)


 * Of possible interest: mathematical game, solved game. Up until ~2006, no computer was very good at playing angels and devils. But now that some people have done some very difficult math, computers can win easily. So in the field of complex games, it is usually operator/programmer knowledge that limits the computer, not the computer itself. (Sometimes the solution to a game is provably NP-hard, and in a sense, you could say that the restriction is more due to the computer than the operator, insofar as P_versus_NP_problem does not result in P=NP ). SemanticMantis (talk) 15:44, 19 May 2014 (UTC)

Mornington Crescent (game) would make a very good test for a computer - I'd imagine it's the game-playing equivalent of the Turing test. It'd be hard for a computer to join in convincingly, in a way that fulfilled the game's real intent, which is to entertain. --Dweller (talk) 15:50, 19 May 2014 (UTC)
 * I don't know how I'd judge that a computer had successfully been entertained by playing Mornington Crescent. But I rather think I could write a program to play the game. I think Inform 7 might be well-suited to it - create a map representing the network, so that convincing-sounding justifications and objections can be written on the fly. The new adaptive-text feature could make it refer back to earlier rounds fluidly, too. Allowing it to play with multiple human opponents would be a little more challenging, but not impossible. AlexTiefling (talk) 15:58, 19 May 2014 (UTC)
 * Sorry, I wasn't clear. The purpose isn't to entertain the computer (let's not go there) but the audience. While the computer could for sure spout random station names, I find it difficult to imagine any kind of programme that would capture the humour behind its pronouncements, including providing new and sufficiently wacky variants of rules, except by means of mixing up a database of old ones, which would fall flat in much the same way (or worse) than an unfunny fan of the game thrown into the programme would do. In short, a computer would be able to play the game alright, but very badly, because, to coin User:Dweller/Dweller's first law of computers: Computers aren't funny. Much. --Dweller (talk) 16:53, 19 May 2014 (UTC)


 * You may be interested in Arimaa. A game specifically designed to be similar to chess for a human player, but nearly unplayable to computers. 74.113.53.42 (talk) 22:03, 22 May 2014 (UTC)

How German homes are built
I am building a new house and I want it to be made of cinder block, but well insulated. No builders in my area do ICF. I read somewhere that in Germany they make houses out of cinder block, then add Styrofoam insulation to the outside, then cover it with stucco. I would like specific information on how this is done and any problems with it. I am concerned about bugs and ants eating the Styrofoam and also about water or moisture getting behind the Styrofoam and caused mold. ( I am allergic to mold) Is this a problem? Also how is it done, do they put tyvek or a waterproof membrane between the Styrofoam and the cinder block? and how do they attach it to the cinder block? If they have to drill holes does that cause problems with air sealing it? And what thickness Styrofoam do they use?--Interestingusername123 (talk) 05:50, 19 May 2014 (UTC)


 * I don't know but bear in mind your house will have to be built according to your local building code, which might not have provision for that type of construction.--Shantavira|feed me 07:40, 19 May 2014 (UTC)


 * Leca Isoblokk is a ready-made sandwich of cinder block and Styrofoam, shown in this video. I found nothing about it in English but you can try asking at your nearest Weber Saint-Gobain plant, found here. 84.209.89.214 (talk) 14:40, 19 May 2014 (UTC)


 * Note that Styrofoam is both flammable and gives off toxic fumes when it burns, so putting that much of it in a house may make it into a deathtrap. However, given the choice, it might be best on the outside of the cinder blocks, in the hopes that most of the toxic fumes would be released outside the house.  A secondary concern is outgassing of toxic fumes as it sits.  Since most of this happens when it's new, just letting it sit for a few months before using it in the house should help here.  StuRat (talk) 16:32, 19 May 2014 (UTC)


 * I'd be surprised if German building code didn't ban toxic, highly flammable foam like ordinary styrofoam. After all, we're talking about Germany. ¡Aua! (Rammstein \ Kraftwerk) 07:14, 20 May 2014 (UTC)


 * I had a house built down here in Texas using ICF (we used "Greenblock") - it comes as a bunch of foam blocks - like lego bricks. Each one has two sheets of foam - held together with two or three pieces of carbon-fibre.  They pour a conventional concrete slab, then build the house up out of these bricks - threading rebar down between them.  Then they pour concrete down into the gaps between the foam.  So the resulting wall is about 1" of foam, 3" concrete and another 1" of foam.  Then you put brick or stucco on the outside and sheet-rock and plaster on the inside.   It worked amazingly well - the house is incredibly well insulated.   If I ever get the chance to have another house built, that's exactly how I'd do it again.


 * The key here is that there is foam both outside AND inside the concrete. I don't know whether using hollow cinderblock for the core is good or bad.  The walls are certainly going to be a lot less physically massive - so their thermal properties will be very different.  My house stayed more or less the same temperature through day and night because of the thermal inertia of all of that concrete - plus the two layers of insulation.


 * Personally, in your situation, I'd use cinderblock - but have them insulate both the inside AND outside of the blocks with an inch or so of fire-resistant foam. (It's not really "stryrofoam" it's denser and not only does it not burn easily, if it does start to melt, it actively suppresses the fire somehow.  It's been 15 hears now, so I forget the details.


 * The tricky part about using two layers of foam is having some way to tie the brickwork (or stucco or whatever) to the inner core - and the Greenblock system solves that with those carbon-fibre pieces that are embedded in the foam. They have tabs inside the foam that you can screw into - which is how the sheet-rock is held up, and how you can hang siding on the outside.  There were special metal straps that they used to tie the brickwork to it...I forget how those work.   There was also a way to apply stucco to it - but we didn't do that, so again, I don't know.


 * Definitely a great way to build a house though. It added about 5% to the cost of building it - and our heating/AC bills were about half that of our neighbors with similar sized houses.  I calculate that the extra cost paid for itself in 5 years - but bear in mind that Texas summers are ferocious and they high cost of airconditioning is what kept the payback time that short.   The CO2 benefits are harder to calculate because concrete manufacture is incredibly bad for generating CO2, I never did figure out what the "payback time" was in terms of carbon footprint - but since the concrete structure should still be viable in 50 to 100 years - I'm pretty sure it's a net win.


 * I also liked that the house was so quiet - and because the walls and slab formed a continuous piece of concrete, there were very few insects getting into the house.
 * SteveBaker (talk) 16:59, 19 May 2014 (UTC)


 * "15 hears" ? That's definitely hearsay then. :-)  I'm curious if the outgassing was a problem.  Did the house smell like plastic for the first year ?  Also, putting holes through the wall for cable TV, etc., can be a bit more work with concrete walls.  And if less air naturally flows through the walls, then you might need active ventilation with a fan running all day, and that cuts into your energy savings. StuRat (talk) 17:06, 19 May 2014 (UTC)


 * No, I didn't have a problem with outgassing...you can see details of their materials as . Making holes in the steel-reinforced concrete walls was indeed a major problem.  Our builder mistakenly put the cooker vent three feet away from where the cooker hood was, and he had to get some very exotic drilling equipment to make the new hole.  When the house was built, he had a large hole in the bottom corner of the garage (made by putting a length of 4" plastic pipe into the wall before the concrete was poured) - phone and TV lines came in through there as well as power cables, A/C drain hoses, etc.  The reduction in air flow was something we were very concerned with, so we had a couple of large fans built into the upstairs ceilings that would pull air out of the house and dump it into the attic.  There was enough gaps around door and window frames to let air in whlie it was running.   However, since (here in Texas) there is only about a week between needing to heat the house and needing to cool it(!), the airflow through the heating/cooling system was plenty to keep the air inside fresh.  On those few days when we didn't need either A/C or heat, we'd have the windows open anyway - so I don't think we needed the vent fans for more than a few days each year.  We had heat-pumps for the household heating - things would probably been different if we'd had a different heat source.  SteveBaker (talk) 20:20, 19 May 2014 (UTC)


 * Haven't done this for a while, but in the UK existing brick houses have been insulated on the outside using either flame-retardant insulating foam slabs or rockwool/glass fibre insulating slabs, with fixings going through the insulation into the outer skin of brickwork. The slabs were then covered with glass fibre reinforced stucco (or rendering in UK terms) which provided a waterproof outer layer. Having the insulation on the outside meant the brick structure would warm, giving a lot of thermal inertia, and the dewpoint for condensation would be outside the brick structure. If the building was to be quickly heated intermittently you could perhaps add an internal layer of insulation, but care would be needed to include a vapour barrier and calculate that the dewpoint was somewhere that condensation wouldn't occur or matter. This is to cope with a challenging climate, very variable with a lot of condensation problems in cold weather. Other countries differ. . . dave souza, talk 17:13, 19 May 2014 (UTC)

I was always told not to insulate the inside of a cinder block building, only the outside, becasue the cinder block acts as thermal mass and will hold the heat or cooling that you are putting into the house (basically acting as insulation itself). I'm not sure why you say I should put Styrofoam on the outside and the inside.--Interestingusername123 (talk) 03:45, 20 May 2014 (UTC)


 * A thermal mass isn't quite the same as insulation. A large thermal mass will tend to delay when the outside temperature makes it to the inside, not stop it.  In the case of most masonry, it seems to delay it about an hour per inch of thickness.  So, 12 inches of masonry would delay the heat of the day from hitting the interior until about 12 hours later, so the middle of the night, when the extra heat might actually be appreciated.  Unfortunately, most homes have maybe half that thickness, so it gets hottest inside some 6 hours after the hottest part of the day, putting it somewhere around 9 PM, when opening the windows to cool the house down might not work yet, since it's still warm out.


 * I'm also not sure why putting insulation on the outside and inside of the cinder blocks is better than putting a double thickness on the outside. Perhaps each creates a vapor barrier, and that prevents moisture from getting into the cinder blocks from the inside, condensing on the cinder blocks when they are cooler than the air in the morning, and causing mold to grow.  I'd expect this to be a potential problem by the bathrooms, if you take showers or baths in the morning, or by the kitchen, if you boil food in the morning.  You can create a vapor barrier without foam, however.  StuRat (talk) 13:36, 20 May 2014 (UTC)


 * I disagree about how thermal mass works. If you take a brick, pile ice-cubes around one side of it for a few hours until it's at 0 degC, then quickly remove the ice and apply a blowtorch to the outside for 30 seconds before putting all of the ice back, it is not the case that an hour or two later, the inside of the brick suddenly gets too hot to touch for about 30 seconds and then cools off again!  So your "delay" theory is busted.


 * What the thermal mass does is to slow down the rate of change of temperature. So as the temperature outside slowly warms up towards noon, the masonry slowly warms up too - but with a considerable delay.  When the hottest part of the day passes, the masonry still won't have reached that maximum temperature - but as soon as the outside temperature starts to fall, the rate at which the masonry is getting hotter gradually decreases.  As soon as the outside temperature falls below that of the masonry, it'll start to slowly cool off.   This doesn't so much delay the outside temperature change (although it does do that) as smooth off the peaks and troughs.   That's what you really want - a "moving average" of day and night temperatures.   Removing the highest peaks and lowest troughs tends to reduce heating and cooling bills - and keeps the house more comfortable.  It also allows the A/C and/or heating unit to operate with fewer on/off  cycles.  If the temperature isn't ideal, then the unit kicks in until the house (with all of that thermal mass) gets to the temperature you want it to be - when it turns off, that large thermal mass continues to maintain that temperature for a long time.  This allows you to narrow the band of acceptable temperatures.   If you had a regular thermostat with a 5 degree "hysteresis" band (so the A/C turns on at 75 degF and turns off again at 70F then it turns on and off more frequently than one with limits at 80 and 65 degrees...but it keeps the house closer to the ideal temperature.  Having all that thermal mass allows you to set tighter limits on the thermostat without it turning on and off too frequently...so the house is more comfortable as a result.


 * Insulation is a bit different, it allows you to have a larger temperature difference between inside and outside without having to use a lot of energy to maintain it. I suppose that slowing the rate at which energy enters and leaves the thermal mass will also increase the 'averaging' effect.


 * Having insulation on both the inside and outside definitely complicates the description of what's going on...but having more insulation is better than less. If you're going to have 2" of insulation (which is what I had), then having half of it inside the wall and half outside is perhaps just convenient from a construction point of view (remember, the foam acts as a "form" for the concrete during construction - holding the concrete in place until it hardens).


 * SteveBaker (talk) 17:44, 20 May 2014 (UTC)


 * Certainly there is some mixture of a narrow heat band with the surrounding temperatures in the masonry, just as a 100 MPH wind gust on an otherwise still day would blend in with the surrounding still air and you'd get a longer and less strong wind gust as it moved along. This doesn't "bust" the underlying effect.  I live in a brick house, and the thermal load from the bricks does indeed hit after sunset, around 9-10 PM, and temperatures inside soar.  When it's hottest outside, around 3 PM, it's not bad inside.  If you live in a brick house, try leaving the A/C off one day, and windows shut, and measure the inside temps, to see if you don't notice the same effect.  Choose an unshaded west-facing room for the measurements, so it will have received afternoon sun.


 * Now, if the masonry was thick enough, you would eventually get an averaging of the daily temps, as you say, and if far thicker still, even an averaging of the yearly temps. However, both of these would require far thicker walls than are the norm. StuRat (talk) 14:04, 21 May 2014 (UTC)


 * ICF houses frequently have foot-thick walls. Mine was over 10 inches thick...4" brick, 1" foam, 4" concrete, 1" foam and a half inch of sheet-rock.  (I was mistaken earlier when I said the concrete was 3" thick - I just checked on http://greenblock.com).


 * However, I'm still strongly skeptical about your "delay" theory. For what you say to be true, heat would have to flow through the material at an incredibly slow speed.  The thermal conductivity simply isn't that low...even in materials like brick and concrete.  The thermal conductivity of brick, cement and concrete are all around 1 W/(m.K) (see http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html).  So a change in external temperature will rapidly propagate through the entire thickness of the material - it can't progress as a slow wave of heat moving through it with cooler material on either side - as you seem to imagine.  So the 'lag' between the hottest outside temps and the hottest inside temps simply can't be measured in hours.  If the outside temps max out at between 3pm and 4:30pm (fairly typical for most places in the world) - then what conceivable mechanism can delay that rise for the 6 or so hours that you claim?!  There is simply no possible way that can be true.  With that kind of thermal conductivity, the temperature throughout the wall will even out within a relatively short period of time.  The 'averaging' effect comes about because the rate of change is so slow - but the moment the temperature outside starts to drop, the walls inside must also start to gradually cool...and the only delay is in the time it takes for heat to be transmitted through the material - but with a conductivity around 1.0, that's only going to be a matter of minutes - not 6 hours.   It's thermal mass, not transport delay that makes this stuff work.


 * Put another way, lean beef has a thermal conductivity that's about half that of brick - heat takes as long to travel through 2" of beef as it does through 4" of brick.  So...how long does it take to roast a 4" thick joint until the middle is cooked?   Do you think that you could turn off the stove once it reached 450 degrees and have the heat continue to penetrate through it until the middle finally got hot enough 6 hours later?   That's precisely what you're suggesting is happening with the bricks.   It's not like a sound wave travelling through some material.


 * So I don't know what you are measuring or how - but there is no physical possibility that it's working as you seem to imagine.
 * SteveBaker (talk) 16:06, 21 May 2014 (UTC)


 * The flaw in your meat example is that the interior is also meat, which has a high thermal capacity, so takes a lot of energy to heat. The interior of a house, on the other hand, is mostly air, with a low thermal capacity, and heating that takes very little thermal energy.  Also, the meat typically starts out as either refrigerated or frozen, while the interior of the house starts out around room temperature.  Finally, assuming no significant bacterial growth or radioactivity, the meat has no internal heat source, while the house has people and pets, cooking, water heaters, lights, and electronics; all creating heat inside.


 * As for thermal conductivity: Perhaps it's not just the masonry then, but also the air gaps, which require radiation to jump from one surface to another.  Also note that "insulating brick" is listed as "0.15", so much slower, and plaster and gypsum board have similarly low values.  All I can tell you is what I've observed.


 * And I'm not quite sure what effect the insulating foam has on the process. I suspect that actually stops the thermal conduction (well, reduces it to a level that's insignificant compared with other sources of heat), as opposed to just slowing it down.  My walls are uninsulated brick.  StuRat (talk) 16:55, 21 May 2014 (UTC)

I live in a colder climate and use gas central heat so is it better to put the insulation on the inside or outside on the cinder block?--Interestingusername123 (talk) 08:41, 21 May 2014 (UTC)


 * I don't think the temp makes a diff on where you should put the foam, just how thick it should be. So, the answer given before, both inside and outside, still applies.  As far as using gas central heat, that would only be an issue if the air ducts are on exterior walls.  If so, you want them inside all the layers of insulation, so there's no insulation between them and the interior.  And be sure you have the full amount of insulation between the air ducts and the exterior, too.  If you need to reduce the thickness of the insulation to make room for the air ducts, then use a more effective (and more expensive) insulation in that area.   StuRat (talk) 20:43, 21 May 2014 (UTC)


 * The material you describe at the top of the page is called exterior insulation finishing system or EIFS. Dryvit and STO are prominent trade names in North America, and are widely used there. A version of the system was used in the southeastern US over wood frame construction, but suffered from moisture penetration issues, resulting in extensive litigation. I'm not aware of problems when used as originally intended, over masonry. All the theorizing above aside, building codes and energy codes encourage the placement of insulation as far out on the building envelope as possible, keeping the greatest possible mass on the inside of the thermal envelope. That way you can use the thermal inertia of the masonry to advantage: having on the outside wastes the mass. However, while the use of concrete block or clay tile is commonplace in Euopean houses, those materials are not widely used above grade in North America and tend to cost more.  Acroterion   (talk)   14:14, 22 May 2014 (UTC)

How does knowing the gene for a disease help you treat the disease?
How does knowing the gene for a disease help you treat the disease? 203.45.159.248 (talk) 07:03, 19 May 2014 (UTC)


 * As far as I know, it doesn't. It is not the reason why one would want to know the gene for a disease. Plasmic Physics (talk) 08:42, 19 May 2014 (UTC)


 * It might help if you were developing a drug to target it specifically, or perhaps a corresponding bacteriophage. ←Baseball Bugs What's up, Doc? carrots→ 09:28, 19 May 2014 (UTC)


 * How is that supposed to work? Plasmic Physics (talk) 09:40, 19 May 2014 (UTC)


 * I think there's some ambiguity here between sequencing the genome of a pathogen (say a virus or a bacterium) as assumed by Bugs' reply, and knowing the relationship of individual genes in a larger genome which produces a given genetic disorder in that genome's owner. The latter was my interpretation of the question, and I think yours too, but it's definitely ambiguous. AlexTiefling (talk) 09:43, 19 May 2014 (UTC)


 * Yes, I agree. Although, I wouldn't normally associate a disease with a pathogen. Plasmic Physics (talk) 09:55, 19 May 2014 (UTC)


 * Why not? Our article disease even lists pathogenic diseases first in its typology of disease near the end of the the lead. AlexTiefling (talk) 10:00, 19 May 2014 (UTC)


 * Habit - I'm not saying that it's wrong, it's just not my primary go-to. Plasmic Physics (talk) 10:04, 19 May 2014 (UTC)


 * It can help a great deal indeed. If the exact mechanism of disease development wasn't know before, but becomes more clear after finding the genetic association, you can start far more targeted studies for therapies. Fgf10 (talk) 14:45, 19 May 2014 (UTC)


 * Biologists generally dislike the term "gene for a disease", because it is an easily misunderstood way of saying "gene whose malfunction causes a disease". Knowing that a certain gene malfunctions may be a step toward understanding how to cure a disease. In most cases the result of a gene malfunction is either (a) a certain type of protein is malformed and does not work properly, or (b) a certain type of protein is made in quantities that are either excessive or deficient. For any of those mechanisms, pinning down what happens is a step toward figuring out how to deal with it. Looie496 (talk) 14:48, 19 May 2014 (UTC)


 * "Gene" is commonly used, at least in everyday language, to refer to a specific allele of a gene; for example, one might speak of the "gene for type A blood". Perhaps biologists are careful not to use the word "gene" this way; but saying "the gene for a disease" or "the gene that causes a disease" (as OttawaAC does just below) is just another example of it. --50.100.193.30 (talk) 03:56, 20 May 2014 (UTC)


 * If the gene(s) that cause a disease are identified, that can lead to a test for diagnosing the disease. Not all diseases are easily diagnosed, for example mental illnesses like schizophrenia, bipolar disorder, and so on. They can be tricky to diagnose and sometimes it takes years, simply because there's no way to do a test to find the correct diagnosis. And the more quickly a disease is accurately diagnosed, the more quickly the correct treatment can begin. If the genetic basis of these illnesses was more fully understood, the effects on the brain would be known with more precision, and medications that target brain chemistry more effectively could be developed. Some illnesses are developmental problems, meaning the genes are "programmed" to trigger the problem at a certain point in the patient's development, like autism in toddlers. If the genes triggering those issues were known, then testing and perhaps preventative gene therapy could be introduced. OttawaAC (talk) 15:47, 19 May 2014 (UTC)

It is rare, but knowing the gene that causes a disease absolutely can lead directly to a treatment. Figuring out that chronic myelogenous leukemia is typically caused by a mutation of BCR and ABL1 led to the creation of imatinib. Figuring out that cystic fibrosis is caused by mutations to CTFR led to the creation of ivacaftor.

Those are just examples where treatments were developed that target the gene (or rather, it's protein product) directly. There are countless more examples where knowledge of the genes that cause a disease expanded our knowledge of how disease occurs, and led to treatments in more indirect manners. Someguy1221 (talk) 06:15, 20 May 2014 (UTC)

Is it true that RNA helix viruses mutate faster than DNA helix viruses?
And if so, then why does the MMR vaccine (which treats an RNA helix group of viruses) only require one vaccine while the flu vaccine only works for 1 year and even then sometimes doesn't work. Both being RNA viruses, one would assume they mutate at about the same rate. ScienceApe (talk) 15:00, 19 May 2014 (UTC)


 * I'm not expert in viruses, but I assume this is at least partly due to the fact that the flu is not caused by just one, but an entire family of viruses, the orthomyxoviridae, which typically generate new strains not just by mutating but by recombining with one another. Someguy1221 (talk) 06:19, 20 May 2014 (UTC)
 * What's relevant is that DNA helices bind more strongly and repair more deftly that RNA carriers of genetic material. For this reason DNA mutates less readily. μηδείς (talk) 04:00, 21 May 2014 (UTC)


 * DNA polymerase has error checking so DNA viruses are copied more carefully, RNA polymerase doesn't. This doesnt address the issue really though.Polypipe Wrangler (talk) 05:12, 22 May 2014 (UTC)

Inconspicuous transport by sea
I was watching some film and they had to smuggle millions in cash from the US to Switzerland and I wonder couldn't they transfer it via a private boat? What's the problem sending a yacht or something else? Range? Inclement weather? --78.148.110.113 (talk) 15:22, 19 May 2014 (UTC)


 * Perhaps they were worried about being intercepted by the Swiss Navy. Gandalf61 (talk) 15:28, 19 May 2014 (UTC)


 * I should point out that it could be transferred by land after reaching the European continent. 78.148.110.113 (talk) 16:05, 19 May 2014 (UTC)


 * The more times they transfer it and cross borders, the more chances they will be caught, by customs agents, etc. Since cash is fairly compact, a private plane would be the obvious method, needing to pass inspection only once.  And weather is also a concern for a boat trying to cross an ocean, as is the time it takes.  Both work together, in fact, as it takes too long to cross to get an accurate forecast for the entire trip before you leave.  And taking a small boat across an ocean is sufficiently rare that it might garner extra attention, particularly looking for drug smuggling or illegal immigrants.  StuRat (talk) 16:11, 19 May 2014 (UTC)


 * It depends on how much money one is transferring. One million dollars in hundred dollar bills is about the size of a briefcase.  Thus, a hundred million dollars would require 100 briefcases to transport.  This page gives an interesting perspective on the size of large sums of money, from a geometric point of view.  -- Jayron  32  18:19, 19 May 2014 (UTC)


 * Don't use the train 95.112.250.227 (talk) 19:08, 19 May 2014 (UTC)


 * The constraint of using cash per se severely limits the options - I'm very surprised though that we haven't heard a lot about solar powered micro-boats or balloons designed to pop and send a radio location signal when they exit a certain polygonal area. Of course if you didn't have to use cash you could use Bitcoins, traditional IOUs with criminal organizations (what was that, "Premium Rush" I think - ahh, hawala, clearly a system that needs to learn how to do marketing in "news" reports to compete), gray-market art that hasn't been seen since the Holocaust, heavy gold necklaces, etc.  Customs shouldn't have a chance against a good idea with a decent cover story. Wnt (talk) 21:55, 20 May 2014 (UTC)


 * Green Dot Corporation issues untraceable prepaid cards, which are often used by criminals. StuRat (talk) 13:23, 21 May 2014 (UTC)

Is it true that blood glucose can change your eye prescription if you wear glasses?
^Topic ScienceApe (talk) 15:28, 19 May 2014 (UTC)
 * < reference. -- Jayron  32  16:02, 19 May 2014 (UTC)

Creatures with 3 pairs of limbs
There are a lot of mythical creatures that look quite like Tetrapods but with an additional pair of limbs, mostly wings or arms. (Centaurs, angels, pegasus to give just a few examples.

I always wonder how the additional pair of limbs would be attached to the skeleton in a was that is not obviously dis-functional.

So what in real nature comes closest to those creatures, or, to avoid all the answers saying "this is impossible because we have not observed such a thing": if some students would have a joke and fake such a skeleton, working real hard avoiding obvious mistakes, how would that look like?

95.112.250.227 (talk) 18:49, 19 May 2014 (UTC)
 * Perhaps like this Meganeura. And that has an extra pair of legs and an extra pair of wings over and above what you wanted. Dmcq (talk) 19:34, 19 May 2014 (UTC)
 * Also try googling "six legged cow" to get some examples. Dmcq (talk) 19:40, 19 May 2014 (UTC)


 * In vertebrates, limbs come from girdles formed during development. We don't have a page on general girdles, but see pelvic girdle and pectoral girdle. The pectoral girdle developed in bony fish. Here is a paper that specifically discusses evolution of girdles and mechanisms that account for the change in development . In short, a putative six-limbed vertebrate would come from a whole lineage of three-girdled ancestors. This is not a sport that can spontaneously pop up and survive to reproduction, let alone have some advantage among extant tetrapods. In nature, we do have ants with three-limbed workers. They have imaginal discs that allow development of separate limb pairs, but they don't have internal skeletons. Certain Odonata are slightly closer to the pegasus, but they have three pairs of legs and two pairs of wings. I can't think of any animal that has exactly four legs and exactly two wings. SemanticMantis (talk) 19:41, 19 May 2014 (UTC)


 * With respect to Dmcq's cow comment, here's a science article presenting a dissection of a six-legged goat . From what I can tell, it did not have an extra girdle, and the legs would have been totally useless. SemanticMantis (talk) 19:46, 19 May 2014 (UTC)


 * I guess the same applies to other creatures mentioned in our article on polymelia (such as Stumpy)? ---Sluzzelin talk  19:55, 19 May 2014 (UTC)

Thanks for the answers so far. I was really thinking about Tetrapods (to be distinguished from quadrupeds), not about arthropods. So the hint to girdles seems crucial. Those polymelia forms look like they are not even good for an additional Eisbein.

But I know that there are additional vertebral notches occurring in nature, either genetically or somatically. Nature does all kinds of "mistakes", so is there anything known about additional girdles? 95.112.250.227 (talk) 20:25, 19 May 2014 (UTC)


 * The problem with having an extra limb girdle is that it changes the entire vertebrate bauplan. The few genes (HOX being probably the best known) that account for correct rostro-caudal segmentation and development of an animal, in my understanding do not separately encode developmental "commands" like "make an extra pair of lungs" or "make a shoulder girdle here". Rather, by modifying those genes, it is possible to change the developmental "fate" of certain body segments: e. g. have a Drosophila grow legs instead of antennae, or have a duplicate thorax (example here: http://biobabel.wordpress.com/tag/abd-b/). Duplication of a limb girdle in a vertebrate animal would probably result in duplication of some of the internal organs as well. There is no funcdamental reason why this would be impossible, though. In fact, a centaur is supposed to have two hearts, two stomachs, and two pairs of lungs; and a catbus 8 or 10 pairs :) Dr Dima (talk) 21:22, 19 May 2014 (UTC)


 * For centaurs I was always wondering if they had duplicate precious parts. 95.112.250.227 (talk) 21:49, 19 May 2014 (UTC)


 * I can imagine an evolutionary path (if conditions somehow favored it) where a bird develops longer and longer talons, and shorter legs, until the talons essentially are the legs. At that point it might have 6 "legs" and two wings. StuRat (talk) 22:25, 19 May 2014 (UTC)


 * Obviously mythologers were both ignorant of and unconcerned with anatomy. The wings of gryphons are speculated to be the dislocated head shields of fossil ceratopsians  Where are the scapulae and musculature going to go for a harpy?  Not to mention how is it going to carry the extra weight of the arms?  Forelimbs in tetrapods develop cranially in relation to the thorax, hindlimbs develop caudally to the abdomen.  Nothing develops medially to the abdomen and thorax.  The disruption to the abdominal diaphragm alone would be a lethal malformation.  Even how turtles manage to develop their limbs inside their ribcages remains an evolutionary mystery.  And four-legged ruminants inevitable have a doubled set of rear limbs, not three pairs of limbs equally spaced.  Given the presence of two dorsal fins in the ancestors of tetrapods, there doesn't seem to be any a priori reason why we couldn't have a third arm and leg in the middle of the back, but the purpose that might serve excapes me.  I'd actually be surprised if some competent physiognomist hasn't examined the conundrum. Good luck. μηδείς (talk) 02:08, 20 May 2014 (UTC)

Drug tests, "cleansing"
so i have a drug test tomorrow and i bought this strip nc extra strength body cleanser. It contains a 1 fl oz liquid and 4 pills. How long does it last and when should i take it? — Preceding unsigned comment added by 50.185.136.93 (talk) 21:24, 19 May 2014 (UTC)


 * I added a header so your question appears in its own section. Please use the "ask a new question" button at the top in the future. As to your question: we cannot give you medical or legal advice here, and your question could easily be seen as asking for one or both. I can point you to this site, which seems to have some good information about the various sorts of drug tests, how they work, etc. . Good luck, SemanticMantis (talk) 21:37, 19 May 2014 (UTC)
 * If any reference is given here, it should be to the Wikipedia article Drug test rather than to a marihuana promotion site. 84.209.89.214 (talk) 23:29, 19 May 2014 (UTC)
 * I should have looked at our article first. Here is a link from our refs there that might be more reliable than the one I posted before . SemanticMantis (talk) 13:30, 20 May 2014 (UTC)