Wikipedia:Reference desk/Archives/Science/2011 October 13

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October 13

Why are multiple personalities a disorder?

Why is displaying multiple personalities considered a mental illness and called dissociative identity disorder? Couldn't it sometimes be advantageous not to always suffer the weaknesses of one's normal personality? (Just think how many more scientists, engineers etc. would be getting laid, if they had a second more extroverted personality.) NeonMerlin 03:37, 13 October 2011 (UTC)

That's not really the way it works, look at the signs and symptoms section. Someone who displayed two perfectly functioning personalities (if that's even possible) would not be diagnosed with a this disorder. Vespine (talk) 03:57, 13 October 2011 (UTC)

If it's not a "disorder", this implies that they have perfect control over them. If so, they are seperate "roles", which healthy people manage to call upon when needed. To use your example, this keeps the scientist from humping his lab assistant mid-experiment or pulling out some test tubes to do research mid-date. StuRat (talk) 14:24, 13 October 2011 (UTC)

See alter ego. Dualus (talk) 18:38, 13 October 2011 (UTC)

Also see this article from the Guardian. ~AH1 ^(discuss!) 23:05, 14 October 2011 (UTC)

Different roles aren't the same as different personalities. Chances are that if I have a strength or weakness in one role, I'll have the same strength or weakness in any other, and that if my job doesn't excite me when I'm in one role, it won't excite me no matter what role I'm in. NeonMerlin 01:02, 17 October 2011 (UTC)

Microwave oven safety

I just got a new microwave oven. In a fairly prominent place among the ten pages of warnings was "Install the microwave oven at least 36 inches above the floor". If, instead, I install it on a thirty-inch-high counter, what's going to happen? --Carnildo (talk) 04:01, 13 October 2011 (UTC)

You could test it and see what happens. It's doubtful anything bad will happen. Of course I could be wrong. However, I am fairly certain that my dorm room's microwave is either that high or lower and nothing bad has happened... yet. :p Anyone know differently? Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 04:17, 13 October 2011 (UTC)

Maybe [1] or [2]? PrimeHunter (talk) 04:29, 13 October 2011 (UTC)

And what child that could reach that far up could actually fit into the microwave? (I've seen some big microwaves, but none that big) Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 04:32, 13 October 2011 (UTC)

I googled [microwave safety 3 feet], and this US government site appeared:[3] They don't explicitly discuss the 3 foot height, but they do mention a 3-foot "kid-free zone" around grills, and they also talk about various microwave issues. This site,[4] which is generally skeptical about microwave ovens, mentions 3 feet as a reasonably safe distance to keep from the oven. As I skim the various items that google displays, there seems to be something "magical" about 3 feet. Maybe there's a risk of fire if it's too close to the floor? Anecdotally, my oven has sat about 2 1/2 feet of the floor for years, with no apparent issues. Further research may be needed. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:28, 13 October 2011 (UTC)

Could be an old wive's tale from early in the microwave oven's history. It could be similar to the whole idea of cell phones blowing up gas stations where someone makes up some idea, it becomes a rumor and then an accepted idea. Any Mythbusters episode to disprove whatever idea there is on this one though? :p Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 05:35, 13 October 2011 (UTC)

Googling the more general [microwave safety minimum height] also yields a number of ideas, including this,[5] which suggests that the 3 foot rule is really more for adults. Also, there's a recurrent theme that the oven should not only not be too low, but also not too high, simply for optimal safety when cooking and when taking stuff out of it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:03, 13 October 2011 (UTC)

The door latch switch can fail or be damaged which risks kids getting nuked if the unit is installed too low ("nuke" is slang for cooking with the microwaves lest anyone new here needs to know that,;-)). I would know this unfortunate failure from personal experience too, because a few years ago my microwave oven was still running after I opened the door and was reaching in for my food! Thus I inadvertently cooked my arm briefly. I had to unplug the unit to get it to stop and my arm was sore for several days. I reported the failure to the safety regulators, who should know more about this issue. --Modocc (talk) 07:49, 13 October 2011 (UTC)

I think that it is very unusual for that to happen really. Sore? That is because the water molecules in your arm were vibrating faster. If you had left it there, your arm's muscle probably would have literally exploded off (not sure what would happen to the bone.). Then you would have had only one arm left to attempt to clean up before you bled to death. On the bright side though, Darwin Award. ;) Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 16:41, 13 October 2011 (UTC)

That's one safety device I feel no need to disable. (One which I do disable is the washing machine not running with the door open. I'm perfectly capable of tossing socks into a running top-loader without tearing my arm off, thank you very much.) StuRat (talk) 14:19, 13 October 2011 (UTC)

I always figured that washing machine feature was more to prevent water from spraying everywhere if you opened it at the wrong time more then worrying about the device mutilating me. Googlemeister (talk) 15:17, 13 October 2011 (UTC)

Not in my machine, at least. The lip on the top of the drum prevents water from spraying out of the top during a spin, since from there it would drip down through the housing onto the floor, in any case. StuRat (talk) 17:35, 13 October 2011 (UTC)

Chemical formulae: technical term for subscripted numerals

For quite some time, I have been trying to learn the technical term for such subscripted numerals as the "2" in "H₂O". Would love to know! I'm expecting something like "atomic ratio subscripts", but somebody in chemical tipesetting must know. It's beginning to appear that they have never been given names. (I'm upset by the recent tendency to type them in-line (non-subscripted), now that it's so easy to subscript, but, that's another matter.) Many thanks for considering this! Nikevich (talk) 07:37, 13 October 2011 (UTC)

For seven years I've been using them now, even so I don't remember ever being taught that it had a name. Plasmic Physics (talk) 12:15, 13 October 2011 (UTC)

Chemical symbol refers to them as "right subscripts" to distinguish them from the atomic number rarely included as a left subscript. Thincat (talk) 18:50, 13 October 2011 (UTC)

That's not a technical term for it though. Plasmic Physics (talk) 23:01, 13 October 2011 (UTC)

Collapsible earth embankment

A car hits a 2 m tall, 2 m wide grass-covered earth embankment head-on at motorway speed. Will all the passengers be killed? If the embankment is filled with collapsible plastic "basketballs", with holes for the air to squeeze out of on impact, how will the impact be different? What if the air is replaced with water? How much pressure would it take to crush such a ball? — Preceding unsigned comment added by 140.203.240.23 (talk) 07:59, 13 October 2011 (UTC)

And, 20 million years from now, when the meerkat people of the future dig the earth of the northern hemisphere, their archaeologists will comment, "No wonder the hairless chimps died out, spending all their time in a bizarre religious ceremony turning the landscape into a nest of sterile plastic eggs." μηδείς (talk) 11:49, 13 October 2011 (UTC)

...but why are the eggs only around Galway? they'll ask. Seriously, there are way too many variables to make a reasonable answer. What thickness of soil on the embankment? how big are the balls? is the soil wet or dry? what is the angle of slope on the embankment? how do you keep water in a ball with holes in it? Richard Avery (talk) 13:22, 13 October 2011 (UTC)

I believe water is usually the best choice, as it has the density required to decelerate the car, but is able to flow out of the way (although you may need to add anti-freeze so it doesn't become ice in winter). This is often used in construction zones, etc. :[6]. Note that no holes are neeeded, as the impact will rupture the container. An alternative, used in runaway truck ramps, is a pile of sand. This, however, requires much more room. StuRat (talk) 14:35, 13 October 2011 (UTC)

Did anyone else think the question read like a homework question? O.R.: I saw the aftermath three cars (at different times) hitting an earthen embankment near my home. No one was killed (at least none were dead at the site) but there were serious injuries (broken limbs, faces cut up). I did not have a radar gun on them so cannot be sure how close to "highway speed" they were going at the time of impact. The basketballs squirting out air would be best, if the depth of them is sufficient to arrest the car. How much pressure? Depends on the ball. Edison (talk) 23:52, 13 October 2011 (UTC)

Is it true that a normally healthy person can get cancer from the normal background radiation on this planet?

Topic says it all. ScienceApe (talk) 13:13, 13 October 2011 (UTC)

See background radiation. It specifically discusses cancer caused by naturally occurring radon. -- kainaw™ 13:18, 13 October 2011 (UTC)

One can, yes. But that's not a very good way to think about cancer. A better approach is to think about risk factors. Getting cancer is probabilistic: it isn't an issue of, "if you smoke, you'll get cancer" or "if you're exposed to radon, you'll get cancer." It's more like, "if a given population of people smoke, X% of them will get lung cancer, as compared to people who don't smoke." Same with radon. The percentages change a lot, and can be compounding (your chance of getting cancer is a LOT higher if you both smoke AND are exposed to high amounts of radon — in that case, they are synergistic, because the smoking helps deposit the radon into the lungs, or something like that). So, long story short, yes, background radiation factors into your total cancer risk profile. This is useful to know for some types of comparisons, but is less useful for others. It's useful when considering the hazards brought about by living near nuclear plants, for example: in general, these are a lot less than the hazards presented by background radiation. It's less useful when thinking about, say, cigarettes or toxic chemicals, which are not only very different types of exposure paths, but are way above the background level of radiation. One of the tricky things about cancer is that you generally cannot say, "this cancer was for sure caused by this exposure." It's probabilistic, again: something tipped off the cell and made it start going haywire. You can say, "these kinds of cancers are highly correlated with these kinds of exposures," but that's as close as it gets. (That's close enough for the courts in most cases.) So when a "normally healthy person" does get cancer, it isn't necessarily the case that background radiation is at fault; it's not necessarily clear what exposure (if any!) is at fault. --Mr.98 (talk) 14:59, 13 October 2011 (UTC)

Something else to keep in mind is that everyone has cancerous cells all the time. Normally our immune systems destroy the cancer cells before they spread, and that's the end of it. The real question, then, is if background radiation can impair the body's normal immune response, and thus cause what we call "cancer". In this context, background radiation seems like less of a risk than, say, a poor diet. StuRat (talk) 17:28, 13 October 2011 (UTC)

for StuRat's claim that everyone has cancerous cells all the time, and that our immune systems normally destroy the cancer cells before they spread. --NorwegianBlue ^talk 21:09, 13 October 2011 (UTC)

It's pretty a pretty well understood aspect of cellular biology, so any immunology textbook would do. Nevertheless, here links to abstracts for four review articles on the subject: [7] [8] [9] [10] – – ClockworkSoul 21:44, 13 October 2011 (UTC)

I checked out your links. All of them support the notion that immune surveilance of cancer for many years has been a hot topic, that attracts a lot of funding, and that has a lot of potential if and when it could be exploited therapeutically. They do not, however, give any hard data to support StuRat's claim that "everyone has cancerous cells all the time, and that our immune systems normally destroy the cancer cells before they spread". I state this as a person who for several years (a while back) has been the recipient of such funding. --NorwegianBlue ^talk 20:40, 14 October 2011 (UTC)

Let me clarify: it's a little imprecise to say that "that everyone has cancerous cells all the time", but cells are mutated all the time. Usually this: A) kills the cell or B) causes the cell to kill itself, but neither of these occur and the cell starts showing signs of not doing what it's supposed to (be it growing unusually or simply expressing some novel protein), the immune system usually intervenes (see cell-mediated immunity and antibody-dependent cell-mediated cytotoxicity). In order for a cell to become fully cancerous, it has to first figure out how to avoid these mechanisms. – – ClockworkSoul 22:01, 13 October 2011 (UTC)

Also remember that according to California Proposition 65, pretty much anything and everything can give you cancer. Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 17:56, 13 October 2011 (UTC)

StuRat, that's really not an accurate description. Most people don't have cancer cells, and our immune system isn't the primary thing preventing cancer. A cancer cell is one that has been damaged in such a way that it has lost the internal controls that limit uncontrolled growth. The most important such controls are a series of mechanisms that detect cellular DNA damage and trigger apoptosis (i.e. cell suicide) to prevent the cell from accumulating enough damage to actually become cancerous. A cell wouldn't be classed as cancerous until all the internal constrains on cell proliferation have been lost which requires multiple unfortunate mutations to have occurred in the same cell line. The immune system can play a role in controlling the growth and spread of cancer, but it usually doesn't get involved until uncontrolled growth has already started (if ever), and when it does get involved it can sometimes do nearly as much harm as good by taking out both healthy and cancerous cells due to the difficulty in distinguishing the two (e.g. paraneoplastic syndrome). Dragons flight (talk) 18:30, 13 October 2011 (UTC)

I disagree. Take the case of the bubble boy, David Vetter. He had no sign of cancer, and either did his sister. He got a bone marrow transplant from her, and, due to his lack of immune system, he quickly developed hundreds of cancerous tumors from the dormant Epstein Barr virus she carried, and died. She likely had many cancerous cells herself, due to the virus, but they were wiped out by her immune system before they were noticed. I supposed you can define cancer as "tumors large enough that we notice them", but this seems rather silly. If such a tumor developed from a single mutant cell, which is genetically identical to the cells in the later tumor, on what basis is that cell called non-cancerous while they are called cancerous ? If one of the tumor's cells breaks off and floats away, is it then no longer considered cancerous until it reproduces enough to form a noticeable tumor again ?

For another example, AIDS often results in types of cancer which are normally rare. Is HIV causing those cancers directly ? Doubtful. More likely they are there all the time, but aren't a threat until the immune system is compromised. StuRat (talk) 18:47, 13 October 2011 (UTC)

You are misunderstanding cause and effect. Some viruses, such as Epstein-Barr and HPV (associated with cervical cancer), transform the cell lines they infect rather than simply proliferating and killing off the cell host. For rare diseases the transformed cell is itself cancerous, but in most cases the cell is merely damaged in a way that compromises some of its natural functions but is not itself cancerous. Those compromised cells are more prone to becoming cancerous because many cellular mechanisms for preventing cancer have already been knocked out in order to aid the virus. In immunocompromised people the scale of the transformative viral infection can be much greater, infecting far larger numbers of cells and greatly increasing the odds that cancer will occur. Look at it this way. Suppose there are 8 improbable events that must occur for a cell to turn cancerous, each having a 1% probability. Then, left alone a cell will become cancerous 1 out of 10 quadrillion times. However, if a virus comes along and disables 5 of those 8 things in order to help itself, then the odds sky rocket to 1 in a million. With 10 trillion cells in a human, a one in a million event will end up happening many, many times. For the most part the immune system isn't killing off cancerous cells per se, rather it is controlling infection(s) that can greatly impact the odds that infected cells will ultimately become cancerous. Dragons flight (talk) 19:28, 13 October 2011 (UTC)

Presumably this is so. But the experiment has never been done! So far as I know no one has made so much as a fruit fly or a bacterium that is free of background radiation, much less a person - and without doing the study, you never really know what will happen in biology. There are various models for the effect of low-intensity radiation - some showing it having a linear, proportional effect, some as having more than a proportional effect, some even claiming hormesis. We don't really understand the effect of high radiation over a lifetime (that Ramsar, Mazandaran link keeps popping up in my mind). I wouldn't be surprised (but don't know) if low level radiation causes some risk of cancer, but also keeps the repair mechanisms primed, so that it would have a variable effect depending on whether there was a risk of meeting up with higher levels unexpectedly or not - both a hazard and protective, like the mild sunburn that leads to a tan. Wnt (talk) 01:59, 15 October 2011 (UTC)

Species Identifcation

unidentified species

To aid a rename request what is this? Location of up loader would seem to suggest this is from somewhere in California. Sfan00 IMG (talk) 13:54, 13 October 2011 (UTC)

I added a CLEAR tag to prevent pic from running into next Q. StuRat (talk) 14:11, 13 October 2011 (UTC)

I think this is probably hopeless. That looks more than anything like a hugely magnified picture of hairs on an insect's abdomen, but it could be spines on a plant or seed -- who knows? By the way, I hope you are not going to be bringing these sorts of random identification questions here very often. If there is reason to think that a picture has some value, that's fine, but mere renaming of random blurry pictures is not a useful way for us to spend our time. Looie496 (talk) 15:49, 13 October 2011 (UTC)

The original uploader seems to be a troll. The picture and his userpage (and blanking a copyright warning) are his only edits-- Obsidi♠n Soul 15:57, 13 October 2011 (UTC)

How about, Wikipedia is not your image host? In general, such images should be recommended for for speedy deletion. They have no encyclopedic merit; Wikipedia doesn't need them. Nimur (talk) 17:22, 13 October 2011 (UTC)

Bucket brigade efficiency ?

I've often wondered if this technique is better than each person just carrying the item in question from the source to the destination directly. Here are some advantages and disadvantages I see to the bucket brigade:

ADVANTAGES

A1) Less mass is moved, since the people themselves don't need to move. This might be particularly important over hilly terrain.

A2) Might work better where insufficent room exists for two columns of people to pass each other, like in a mine.

DISADVANTAGES

D1) Dropping the items seems more likely, especially if the people are far enough apart that they need to toss the objects.

D2) Injury seems more likely, especially if the people are far enough apart that they need to toss the objects. Paula Deen having been smashed in the face with a ham is a prime example: [11].

D3) Would seem to suffer from the "weakest link" problem. For example, if it's necessary to include children to make the human chain reach the target, then the chain can't handle any object heavier than the weakest child can lift.

So, with all this in mind, has anyone proven that a bucket brigade is able to move more items in the same amount of time, or is it just done to foster a spirit of teamwork ? StuRat (talk) 14:09, 13 October 2011 (UTC)

Realistically, I doubt two columns of people can pass each other in the doorway leading to a house fire or a collapsed warehouse, either. I think that the tendency to form a bucket brigade at such obstacles is almost instinctive - when you're holding a full bucket, and you can't go forward around the next person, what do you do? Wnt (talk) 17:15, 13 October 2011 (UTC)

There's also the advantage that a single person may not be able to carry the weight the full distance but can move the weight from one side of their body to the other. Dismas|^(talk) 18:53, 13 October 2011 (UTC)

We discussed this a few years ago on the Ref Desk, and I seem to recall some references from books about bucket brigade functioning. Some towns would have bucket brigade practice periodically, so they could get up to speed quickly. Some towns would have firefighting cisterns holding a thousand gallons throughout the city, with a hundred buckets stored by each. Other towns would rely on each citizen to bring a bucket. Home or business owners were likely to have a ladder permanently against the wall to reach the upper story and roof. The point was to get the fire put out and save the affected, or the neighboring, structures, more than to "foster a spirit of teamwork." "Bucket brigade to flying squadron: fire fighting past and present" (where "the present is 1909" describes the bucket brigade on page 5. The brigade could be set up so that the stronger men passed the full buckets, and used their upper-body strength to throw the water at the fire, while women returned the empty buckets to be refilled. Hand-pumped hose engines were favored for cities with densely packed tall buildings starting around 1800, and steam pumpers came along a few years later. Some towns still relied on only the bucket brigade as late as 1875: [12]. Even with pumpers, a bucket brigade was sometimes used to keep the pumper tank filled, rather than relying on suction hose. Edison (talk) 19:28, 13 October 2011 (UTC)

See The Secret of Santa Vittoria. μηδείς (talk) 17:33, 14 October 2011 (UTC)

Individually, each person would have to go back and forth. ~AH1 ^(discuss!) 22:57, 14 October 2011 (UTC)

Online obituary

How can I see The Times online obituary Geoff Handbury or Helen Handbury? I am keen to know the names of each of their 14 grand children. Kittybrewster ☎ 15:16, 13 October 2011 (UTC)

It's behind a paywall, isn't it? Whereabouts are you? You may be able to see it free at a library. --TammyMoet (talk) 15:20, 13 October 2011 (UTC)

Don't assume a newspaper paywall is impassable. A local paper near me sends non-subscribers away with a message that doesn't work if you are running NoScript. The New York Times will tell you an article is subscriber only, but in the past I've taken the same URL, copied it into Google, clicked on the top hit, presto! I'm in. They like Google searchers for some reason. Deleting cookies may get around access limits (plus allow you to vote many times in computer polls - I remember one time the local paper ran a question about whether computerized voting could be hacked. I say they asked for it... ;) Wnt (talk) 17:11, 13 October 2011 (UTC)

I tried with BeTheBot in both google and yahoo mode. No luck. --NorwegianBlue ^talk 19:47, 13 October 2011 (UTC)

It would be quite unusual for an obit to list that many grandkids by name. --Sean 19:05, 13 October 2011 (UTC)

Obits don't usually list grandchildren. You want a genealogy, like this. -- kainaw™ 19:52, 13 October 2011 (UTC)

I want one better than that! Kittybrewster ☎ 15:01, 14 October 2011 (UTC)

Astrologist Claims

Anyone here have an example of an astrologist who claims astrology is science (and claims to be a scientist). Thank you. Wekn reven i susej eht ^{Talk• Follow} 15:37, 13 October 2011 (UTC)

Jaipal Singh Datta apparently does (one of his websites). --Colapeninsula (talk) 16:39, 13 October 2011 (UTC)

In India, astrology is considered a science by some and is even taught at some universities. Unlike in America where astrology is generally what you read in the back of a newspaper, it's taken much more seriously in India. For instance, an astrologer will be consulted when arranging marriages. N^oformation ^Talk 21:17, 13 October 2011 (UTC)

I'm not sure I agree with the above, I think it's far more pervasive then they let on. Even in America the "belief" is wide spread and there are many people who take it seriously enough. I don't dispute that the superstition is greater in India, but there was Joan Quigley, you don't get much more serious then that. Vespine (talk) 23:09, 13 October 2011 (UTC)

Thanks. Wekn reven i susej eht ^{Talk• Follow} 17:09, 14 October 2011 (UTC)

Theodor Landscheidt was another individual who had publications in scientific journals but used some astrological techniques, also claiming that other planets can affect Earth's climate. ~AH1 ^(discuss!) 22:53, 14 October 2011 (UTC)

I'm surprised nobody's mentioned Michel Gauquelin, who amassed a vast amount of statistical data in order to either confirm or disprove astrology as a science, and ended up disproving it overall, but nevertheless made some findings along the way that were quite unexpected and cannot be easily dismissed. -- Jack of Oz ^{[your turn]} 03:26, 15 October 2011 (UTC)

RBC Indices

Hello. Why is the mean corpuscular volume multiplied by a factor of 10 and the mean corpuscular haemoglobin concentration by 100? Thanks in advance. --Mayfare (talk) 16:36, 13 October 2011 (UTC)

Not sure of the context, but it's probably a matter of how the values are traditionally written. I know h(a)emoglobin is typically written in grams per deciliter, so there's an obvious multiple of ten. In practice, most clinical laboratory data is discussed without the units because the users are all familiar with the expected units. If for some odd reason what you're looking at is using nonstandard units you'd have to multiply it to convert it to the "standard" units. SDY (talk) 16:59, 13 October 2011 (UTC)

Basically, concur with SDY. A definite answer would require that you tell us which units are used for haemoglobin, MCV and MCHC in the reports that you receive, and the reference values for each parameter. If you do the calculations taking the units into account, you might be able to answer the question yourself. Otherwise, please supply the necessary information. --NorwegianBlue ^talk 20:17, 13 October 2011 (UTC)

What kind of snake is this? (US Rockies region)

Resolved

See image. Larger than a Garter snake. Chillin' on a trail up in Colorado foothills, just west of Denver. I think it was in digesting mode because the middle of it looked fatter and nothing seemed to bother it. Image link: [13]. Thanks! Theesotericniffler (talk) 17:53, 13 October 2011 (UTC)

Of the striped snakes native to Colorado, this looks to me most like a Western Terrestrial Garter Snake. Deor (talk) 18:20, 13 October 2011 (UTC)

Wow, neat, thank you! Theesotericniffler (talk) 19:01, 13 October 2011 (UTC)

Household Bleach

Hi, I just used around a 50/50 mixture of water and Clorox brand household Bleach to clean my kitchen floor. It worked well, but I didn't go back over it with another round of plain water, instead I just let it dry. The floor looks great, but is slightly sticky to touch. My question is simply if there is any danger of burns to the skin hours from now, if someone walks over the floor with bare feet. Keep in mind, the floor is totally dry now. Also, what if I spill a small amount of water on the floor later today or two days from now, and then come in contact with it. Will it cause any adverse effects, such as bleaching out nearby carpet if it comes in contact, or has the Sodium hypochlorite already broken down at that point? If so, I'll go mop again with water soon. Thanks, 10draftsdeep (talk) 18:43, 13 October 2011 (UTC)

What was your intention with using so much bleach? Just a glug or two (old Scouting term for about a quarter cup, enough for the bottle to go "glug" when pouring) would have sufficed for disinfecting the floor. Dismas|^(talk) 18:49, 13 October 2011 (UTC)

Hi Dismas, I knew I was going heavy on the bleach. My intentions were not so much disinfection but rather making an old worn discolored floor look close to white in color again. Hopefully someone can provide some insight. 10draftsdeep (talk) 18:58, 13 October 2011 (UTC)

I would be inclined to rinse well and keep rinsing until the floor no longer dries tacky. It's possible the tackiness is the bleach dissolving the top surface of the floor covering! --TammyMoet (talk) 19:09, 13 October 2011 (UTC)

You didn't mention what your floor is made of, I think that would probably make a difference.. But really, without trying to be a jerk, this just about falls into the "spirit" of medical advice; Without knowing all the variables and being a bleach expert, you could get some well meaning, but very poor advice. If you are actually concerned about burning your feet or bleaching your carpet, what you SHOULD do is follow the directions on the bottle; if it is not intended to be used as a floor cleaner and does not have instructions for that use, buy something that is intended for that use and follow its instructions. Vespine (talk) 23:00, 13 October 2011 (UTC)

Some plastics brake down with strong bleach but I would not think that is the reason for the tackiness. It might simply be that the bleach also contains some surfactants (read the label). As Tammy suggests: rinse well. This should remove the coating of surfactant.--Aspro (talk) 23:26, 13 October 2011 (UTC)

What is tacky? The only description that I have is an adjective describes an object as being of bad taste according to common opinion, like fluffy dice hanging from the rear view mirror. Surely that is not what you mean here? Plasmic Physics (talk) 23:57, 13 October 2011 (UTC)

tacky, first definition. Where Blu-tack gets its name from. Vespine (talk) 04:45, 14 October 2011 (UTC)

Thanks for all the response. The bleach does an amazing job in whitening the old linoleum floor. 10draftsdeep (talk) 19:46, 14 October 2011 (UTC)

Just don't come back crying when your lino floor finally melts into a puddle of goo:) Vespine (talk) 22:31, 16 October 2011 (UTC)

Types of fermentation

Is it true that there are two types of fermentation? One which produces primarily ethanol, while the other produces primarily lactic acid? If so, is silage the result of lactic acid fermentation? ScienceApe (talk) 19:07, 13 October 2011 (UTC)

Yes, there is ethanol fermentation, which is similar to, but distinct from lactic acid fermentation. Silage#Fermentation will explain what's going on there. SemanticMantis (talk) 19:50, 13 October 2011 (UTC)

Your question is not very clear. There are many types of fermentation. In the context of wine-making, there is also malolactic fermentation, which converts malic acid to lactic acid. --NorwegianBlue ^talk 20:26, 13 October 2011 (UTC)

Muon positron annihilation

In muon positron annihilation (or the charge flipped reverse), is the result one neutrino and two photons or two neutrinos and two photons? Hcobb (talk) 19:16, 13 October 2011 (UTC)

Muon and positrons are from different fermion generations, and so their interactions are not generally described as annihilations. The possible outcomes depend on the energy involved, but the easiest case is that they either scatter (without changing form) or they are transmuted into neutrinos (e.g. a muon neutrino and an antielectron neutrino). A variety of other outcomes are of course possible, however I'm not sure why you would expect the ones that you suggested. Dragons flight (talk) 21:09, 13 October 2011 (UTC)

Muon- and e+ could turn into electron and Muon neutrinos plus a pair of photons without violating any of the conservation laws. Hcobb (talk) 22:01, 13 October 2011 (UTC)

Hmmm, it seems to me that the muon positron bound state should be able to oscillate to the antimuon electron bound state, because of the mismatch between neutrino mass and flavor eigenstates responsible for neutrino oscillations:

$\mu ^{-}+e^{+}\rightarrow e^{-}+e^{+}+\nu _{\mu }+{\bar {\nu }}_{e}\rightarrow e^{-}+e^{+}+\nu _{e}+{\bar {\nu }}_{\mu }\rightarrow \mu ^{+}+e^{-}$

Count Iblis (talk) 01:45, 14 October 2011 (UTC)

See muon neutrino. ~AH1 ^(discuss!) 22:48, 14 October 2011 (UTC)

Silicon based life

Lets say, we create more powerful computers and robots. Then they become so intelligent that they are not only self aware, but they are more intelligent than humans. Eventually they kill all humans and learn how to self replicate. Would they be considered silicon based life? ScienceApe (talk) 19:22, 13 October 2011 (UTC)

You are also assuming that they stubbornly decide that silicon is the only semiconductor to use. Why is that? Right on my desk now, I know that I have some germanium and gallium arsenide electronics. -- kainaw™ 19:24, 13 October 2011 (UTC)

Considered by whom? This is a matter of semantics. We have extensive coverage on the definition of life. There is not a great degree of consensus about how to apply the terminology, outside of the well-established "obvious" cases. Nimur (talk) 19:28, 13 October 2011 (UTC)

I'm assuming that the whole "silicon-based life form" trope was kicked out as an idea based on the chemical similarities between Silicon and Carbon, not as a reference to electronics. SDY (talk) 19:37, 13 October 2011 (UTC)

Perhaps, with humans extinct, the silicon-based machines might define themselves as life, and define us as having been "a chemical abberration". StuRat (talk) 21:13, 13 October 2011 (UTC)

This is my understanding as well. Si based life would refer to life that developed by natural means, using silicon as the main bond forming atom rather than carbon. N^oformation ^Talk 21:15, 13 October 2011 (UTC)

You could call them that, why not? But it wouldn't be "silicon-based life form" as we understand the term. That's usually used to describe life that works like ours, but with silicon in place of carbon. 21:14, 13 October 2011 (UTC)

Why silicon though. Provided advanced levels of biotechnology, it would probably be just as likely that we can make 'wetware' in the future - organic computers. It's actually one of the more ubiquitous kinds of technologies in cyberpunk, spanning neural interfaces, disposable communication patches, to artificial 'brains' etc.-- Obsidi♠n Soul 04:17, 14 October 2011 (UTC)

I'm surprised nobody has linked to organosilicon. There are otherwise several possible scenarios involving hyperintelligent robots who eventually outsmart their inefficient human counterparts, but the mass extermination of humans is the most often discussed. ~AH1 ^(discuss!) 22:45, 14 October 2011 (UTC)

Sure, why not? Dualus (talk) 09:45, 15 October 2011 (UTC)

Arbitrary digital record of sound

If I want to record digitally some sound, can this record be of any arbitrary length? (even fractions of seconds). Quest09 (talk) 19:48, 13 October 2011 (UTC)

Not quite sure what you're asking. Are you refering to the length of the digital tape or other media ? In that case, the longer the tape, the more detail you will be able to record. StuRat (talk) 20:13, 13 October 2011 (UTC)

I too find your question a bit unclear, but check out our article sampling rate. It is clearly possible to make a digital audio recording with a duration of a fraction of a section. The amount of information you will be able to collect will obviously depend on the sampling rate, and, depending on your reason for collecting the data, its usefulness may be limited by the audible frequency range of human hearing. --NorwegianBlue ^talk 20:46, 13 October 2011 (UTC)

It's not about the details, about a very long tape or a very short tape. I want to know if the hypothetical length is continuous or necessarily discrete (which sounds intuitively right). Quest09 (talk) 22:01, 13 October 2011 (UTC)

I'd say the minimum length is one sample, which would produce a pulse sound. Then the length is as long as the number of bits in your sample. At the minimum, this would be one bit. That's a discrete length.

However, the length of time it takes to play it would be determined by the playback sampling rate. That's a continuous length, determined by the pulse width in the playback device. ~Amatulić (talk) 22:16, 13 October 2011 (UTC)

Also note that some compressed formats operate on blocks rather than individual samples, so your sound may need to be padded to a complete block when you save it (see MP3#Encoding audio, for example). 130.76.64.118 (talk) 22:20, 13 October 2011 (UTC)

The OP was asking hypothetically, in which case fancy compression formats aren't necessary. One could always save it uncompressed. For that matter, if the software to play back already has an expectation of the format, it isn't even necessary to store header data in the file. I have seen sound files and image files that consist of raw data only and nothing else. ~Amatulić (talk) 22:37, 13 October 2011 (UTC)

Perhaps the OP would find our article on Sample rate relevant? Vespine (talk) 22:55, 13 October 2011 (UTC)

It's not clear to me exactly what the OP is asking, so I just thought I'd throw in a different angle. Not disagreeing with any of your points. 130.76.64.121 (talk) 22:57, 13 October 2011 (UTC)

I was asking something completely impractical and hypothetical (don't try to find any use in it, it's useless). I wanted to know how can you tape digitally sound, which is a continuum. Digitally, you always have discrete unit (right?), so you'll always lose something (even if it's not important), right? Quest09 (talk) 00:09, 14 October 2011 (UTC)

Basically, yes. Digits are discrete, so any digital recording is, also. But is sound really a continuum? It is made up of pressure waves which are transmitted through air, which is made up of discrete molecules. In principle, if your digital recording used enough digits, you could count the individual air molecules as they hit the microphone (this might you lead into uncertainty principle problems, though. Short version: there's no such thing as a perfect recording). 130.76.64.121 (talk) 00:58, 14 October 2011 (UTC)

There is a mathematical theorem that states that if you sample at a rate at least twice the highest frequency present in the sound, you get all of the information present in the sound. If you sample at a lower rate, you lose information due to the phenomenon called aliasing. The mathematics behind this is called Fourier theory. Looie496 (talk) 00:58, 14 October 2011 (UTC)

True, but the phrase "highest frequency present in the sound" brings with it certain assumptions about the nature of sound. 130.76.64.121 (talk) 01:06, 14 October 2011 (UTC)

I believe this question stems from a fundamental question about the nature of digital signals. By definition, a digital signal is:

• discrete in amplitude - see quantization or "bit depth," and also
• discrete in time - see sampling rate.

There are other signal types that are continuous in amplitude, but sampled at discrete time points; or are recorded continuously on analog media, but are quantized; or are neither quantized nor sampled. None of these are digital signals in the conventional sense. If you want to work with such signals, you have an analog recording. Analog recordings may still have some fundamental "granularity," in the sense that any physical object is not a perfect mathematical idealization of the continuity abstraction. Digital signals in standard formats using readily available technology will have prescribed sampling rates; modern technology requires both a sampling rate and a "frame" or "window" (hinted at above in discussions about padding for compression algoritms). This usually means, for example, that you must sample at 44.1 kHz, and end your recording after a group of 512 samples - because the equipment you have has such hardware requirements. (Your gear may support other sample-rates and sample buffer-sizes). If you work in a purely software environment, you may be unconstrained by such limitations, and may specify sampling rate freely (and typically, you have no buffering, windowing, or framing requirements at all). Nimur (talk) 01:07, 14 October 2011 (UTC)

Well said. 130.76.64.121 (talk) 01:17, 14 October 2011 (UTC)

The article Nyquist limit may also be of interest to Quest09, the OP. --NorwegianBlue ^talk 20:25, 14 October 2011 (UTC)

Global observation of the Miracle of the Sun

While I believe in the authenticity of the eyewitness' accounts, there is an interesting concern: why the miracle was not observed globally? Are there any reports from other countries from that time? The idea that the sun miraculously behaved like that only locally is horribly crazy.--46.205.9.216 (talk) 20:01, 13 October 2011 (UTC)

Are you asking about the event described in our article Miracle of the Sun? If so, the section Miracle_of_the_Sun#Critical_evaluation_of_the_event at least partially answers your question. --NorwegianBlue ^talk 20:56, 13 October 2011 (UTC)

Agreed, it sounds like some local effect to me, like ball lightning. StuRat (talk) 21:10, 13 October 2011 (UTC)

The only claim that the apparition was witnessed outside of Portugal within the article was that the Pope at the time saw the event in Rome. Other than this, the colours seen around the sun (if in fact it was the Sun) seem to be some form of intense cloud iridescence, irisation, corona or a combination of these and other optical phenomena. Most descriptions of the event do seem to suggest meteorological optics, and the Sun would have been covered in cloud if it were visible without hurting the eyes of onlookers. ~AH1 ^(discuss!) 22:42, 14 October 2011 (UTC)

Is the science in The Subtle Knife correct?

Resolved

In particular, I'm wondering about the passage in the chapter Alamo Gulch. "In a storm, as the air pressure sank," Lee released the ballast per mental calculations. But doesn't the decrease in air pressure call for a heavier load (impossible as it may be in a hot balloon), especially during landing? Wouldn't releasing the ballast and thus making the balloon lighter make it rise, not lower? 65.88.88.70 (talk) 20:47, 13 October 2011 (UTC)

I don't remember the details of this part of the story. In any case, hot air balloons are continually losing buoyancy through cooling. Without a continuous source of heat, the balloon will descend. If one runs out of fuel, one needs to lighten the load to slow down a descent.

Also, if air pressure drops, so will the pressure in the balloon. There may be an increase in buoyancy temporarily if the heat inside is sufficient to contain the air in the bag, causing a temporary expansion. But the balloon is still open at the bottom, so it's likely the pressure won't change relative to the outside, and some hot air will escape. ~Amatulić (talk) 20:57, 13 October 2011 (UTC)

It's a long time since I read it, but isn't it actually a gas balloon, not a hot air balloon? I seem to remember he has to make or capture the gas when he needs to take off again, and vents the gas to sink. Have I misremembered this bit? A gas balloon is certainly limited by low pressure outside, which is why it cannot float all the way to the moon. Low pressure outside would make the difference in density between the gas in the balloon and the gas outside the balloon smaller, and it is this difference which provides buoyancy, simplistically speaking. (I'm actually muddling concepts a bit here, but I assume you don't want the full buoyancy tutorial) With a non-elastic material holding the gas in, the pressure inside the balloon cannot decrease to match the outside, because that would require it to expand. So the balloon will start to drop, possibly at an alarming rate: releasing ballast will correct for this, by making the balloon lighter, so it will drop more slowly or start to rise. 86.163.1.168 (talk) 21:33, 13 October 2011 (UTC)

I think this is the correct answer. The balloon was a gas balloon, not a hot air balloon. APL (talk) 21:52, 13 October 2011 (UTC)

Becoming ambidexter

If a right-handed person tries to learn ambidexterity, would it be harmful to the brain? Is it safe for the right-handed person to pursue left-hand exercises (especially writing) to develop ambidexterity? Thank you.--46.205.9.216 (talk) 21:20, 13 October 2011 (UTC)

I know of nothing that says training yourself to work well with both hands is harmful. In fact I have seen just the opposite.

Anectodal from personal experience: In my last job, we had an ergonomics professional who recommended to us to learn to use the computer mouse with both hands to prevent stress-related injury to one hand. Since I use the computer at home a lot too, I ended up using the mouse left-handed at work, and right-handed at home. After a week or so, it felt perfectly natural in either hand.

Also, sometimes it's forced on you. I had an injury to my left hand that prevents me from fingering the neck of a guitar. So I re-learned to play it left handed (with the right hand on the neck). A guitarist told me that this is actually the best way for a right-handed person to play the guitar; dexterity is more important in the neck-fingering hand than the string-picking hand. So if you're right handed and you play a guitar the "normal" way, you've already trained yourself to be ambidextrous in a fashion, because it's unnatural for your non-dominant hand to do such dexterous work.

Another anecdote: Leonardo da Vinci trained himself to write backwards with his left hand as a means to make his notes illegible to snoopers. You had to view his notes from the back, shining a light on the front side, or view them in a mirror. There's no argument about Leonardo's brilliant brain, either. ~Amatulić (talk) 22:06, 13 October 2011 (UTC)

However, most people today can read backwards text. ~AH1 ^(discuss!) 22:25, 14 October 2011 (UTC)

There is not a lot of good data of the effects on the brain of forced use of the non-preferred hand. Given that forced use of the non-preferred eye is a standard treatment for amblyopia, one would expect it to have some effect, though. Looie496 (talk) 00:46, 14 October 2011 (UTC)

It could be that it has a slight effect on re-shaping the brain functions via neuroplasticity. ~AH1 ^(discuss!) 22:25, 14 October 2011 (UTC)

Shock wave and blast wave

What's the difference between a shock wave and a blast wave? I have read both articles but I still don't understand what's the difference. --Belchman (talk) 21:37, 13 October 2011 (UTC)

A shock wave is the leading component of a blast wave. You can have a shock wave without a blast wave (like the shock wave disturbance emanating from leading edges in supersonic flight), but it seems you can't have a blast wave without a shock wave. ~Amatulić (talk) 22:12, 13 October 2011 (UTC)