Wikipedia:Reference desk/Archives/Science/2007 July 1

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July 1

Why are antistatic bags pink?

Why are antistatic bags pink? Yes there are blue/silver ones too but pink I dont get. Is there a reason or not? Studying Comptia A+ and questions keep coming up like "what colors are antistatic bags" -- why pink? wikipedia link [1]

--88.105.249.208 00:30, 1 July 2007 (UTC)

I honestly don't know the answer - but I would speculate that it's either:

• One is technically supposed to open such bags at a static-protected workstation and assemble the component into whatever it's going into in a static-safe environment. Using a pink bag instead of a clear one is an indicator to the person unpacking it that this procedure is advised. (but rarely taken!)
• It might be to make sure that the people packing the parts in the first place don't grab a non-static-safe bag by mistake.

Hopefully someone will come up with a better answer! SteveBaker 01:24, 1 July 2007 (UTC)

According to this, the pink is just a dye added to distinguish what would otherwise be a transparent bag from all the other transparent and not anti-static plastic bags. By contrast, black and silver colors actually come from the intrinsic colors of the materials used in those cases. Dragons flight 01:54, 1 July 2007 (UTC)

Dragons flight is correct: the pink color is so that you can know, at a glance, that the bag alleges to have some antistatic properties. We do have an article, BTW: Antistatic bag.

Atlant 12:11, 2 July 2007 (UTC)

re:heat and sound

hello friends..

i m currently working on effect of "sound on temperature changes".i m not getting sufficient written matters to complete my project report.kindly prescribe some e-books/wikipedia articles related to this topic.

Sameerdubey.sbp

Could you be more specific on what you are interested in? Do you want to know if sound energy (acoustic vibrations) can make something heat up (or less likely, cool down)? It would be interesting to see someone cook food by yelling at it! Edison 04:48, 1 July 2007 (UTC)

One classic gedankenexperiment is to calculate the speed of sound in a material from fundamental principles and its Young's modulus. I'll see if I can dig up a reference... Nimur 06:36, 1 July 2007 (UTC)

we know that when a sound source is directed in a tube(means it is kept at one end)we get compressions and rarefractions.The longitudinal wave(sound) results from successive compressions (state of maximum density and pressure) and rarefactions (state of minimum density and pressure) of the medium.change in air density changes temperature of that part of air.my project is dealing with this fact .i want to alter the frequency of the incident sound wave and control the temperature.my project aims to assist machines which involve heat transfer by gases.

kindly help now in this regard. Sameerdubey.sbp 5:18 1st july india

It's still not overly clear, but to me it sounds like you are looking at effects of "temperature changes on sound" rather than effects of "sound on temperature changes". See Speed of sound, in particular the section on speed in ideal gases and in air for starters. --jjron 12:10, 1 July 2007 (UTC)

They really aren't. They are asking about the effects of sound on temperature changes, as described in their summary above. They are looking at changing the frequency to get different temperatures. Skittle 20:04, 1 July 2007 (UTC)

Didn't you ask this last week? I pointed out High intensity focused ultrasound and second sound in superfluids. The latest comment sounds more like acoustic refrigeration, though. — Omegatron 12:49, 1 July 2007 (UTC)

thankyou very much ...i hope i could get something very nice out of it. Sameerdubey.sbp 8 :06 1july india

Wireless Energy

I was reading the articles Tesla Coil and Wireless Transmission of energy and I started to contimplate how feasible these devices really are. If I where to build a tesla coil could I power my house wirelessly?68.190.214.230 03:41, 1 July 2007 (UTC)

Yes, in principle you could. In fact, there is a bunch of very active practical research at MIT and elsewhere into finding ways to recharge small portable electronic devices such as cellphones and MP3 players wirelessly - I vaguely recall hearing that practical devices are only a short way from being practical devices that may ship with cellphones in the next year or two. See Wireless energy transfer for example. Furthermore, those RFID tags that you find in things like the Speedpass are powered (briefly) in exactly this manner. SteveBaker 04:26, 1 July 2007 (UTC)

At the same time people worry a lot about the dangers of electromagnetic fields EMF causing cancer. How hard is it to plug a cell phone or a laptop power supply/wall wart into an outlet rather than plugging the "wireless transmitter" into the same outlet and beaming the power through the air (and sometimes through the kids) to the gadget you need to power? By all indications if you move too far away or out of the beam the gadget quits working, and under the best circumstances there would be a low efficiency compared to a direct connection. I see some promise in Micropower. Edison 04:43, 1 July 2007 (UTC)

The forementioned MIT guys have 40% efficiency at 7 feet. I must admit there is appeal to having a universal wireless charging tech so I could just put my cell phone, camera, laptop, iPod, whatever on a special shelf and have it be fully charged when I come back. Dragons flight 05:27, 1 July 2007 (UTC)

WiTricity, Evanescent wave coupling — Omegatron 12:46, 1 July 2007 (UTC)

In a way, you already power your house wirelessly. There are transformers between the power plants and your house that step down the voltage. These transformer have no wire connections, only Electromagnetic connections. This is the most common form of wireless power transfer. There are many other forms of wireless power transmission, some with high theoretical efficiencies such as Microwave power transmission. --Duk 05:14, 1 July 2007 (UTC)

Also, the Carrier wave used by FM and AM transmissions are sort of like wireless power, enough to power a simple radio. -- JSBillings 13:16, 1 July 2007 (UTC)

I have vague recollections of a court case involving some enterprising chap who lived very close to some large, powerful radio transmitters who was able to capture enough energy to power his home (I have no clue to what degree) - thereby causing a radio black-spot downstream from his house. I don't recall enough detail to provide a reference sadly. SteveBaker 16:23, 1 July 2007 (UTC)

I heard a similar story about a farmer who laid some coils of wire in his field, beneath the high-tension transmission lines that crossed it, and was successful enough at extracting energy that the electric company's normal monitoring noticed. The farmer argued in court that he was simply picking up "waste" energy, but the electric company brought in an expert witness who showed, convincingly, that due to inductive coupling those coils in the field weren't passive, but were actively sucking -- stealing -- energy from the power company's lines. —Steve Summit (talk) 17:20, 1 July 2007 (UTC)

if I lived next to a transmission line or substation I would probably check into free lighting. Edison 23:12, 1 July 2007 (UTC)

Nice thank you for all the responces.67.121.105.126 00:48, 2 July 2007 (UTC)

Re Steve, Steve and Edison. Mythbusters investigated this in an apparently not very widely released episode and essentially busted it - see here (scroll down to the first entry in the table). --jjron 09:38, 2 July 2007 (UTC)

Incidentally, the evidence for EM fields of the wavelengths suggested for wireless electricity causing cancer is non-existent. Batmanand | Talk 11:36, 2 July 2007 (UTC)

The best evidence (and it is still weak, inconsistent and unconvincing) for there being any link between cancer and powerline EMF comes from the analysis of the experiences of thousands of people who lived near power lines, or thousands of utility worker who spent a career near lines. Obviously any new application with a different frequency will not have had thousands of people working or living for tens of years next to it, so your statement is technically correct but not informative. In the 1890's they could have said "the evidence for X rays causing cancer is nonexistent." They were in fact pretty sure it was harmless. 5 years later there were people such as Clarence Madison Dally dying of cancer after amputation of cancerous limbs. There is no handy database showing a chart of the cancer-causing or other harmful potential and safe intensity of each possible electromagnetic wavelength, from ELF to gamma rays. As an example, a friend who worked on hawk missile battery radar during the Vietnam War noted years later how many of the 40-something year old vets of the unit had developed cataracts, such that a proper statistical study (the government wasn't interested in doing one) would probably fond a link between the microwave exposure and the eye trouble a few years later. Today I see people with celphones clamped to their ears for several hours a month, and am concerned about the possible consequences. To power a device with transmission from several feet away would require a very high field intensity, in what is effectively an air core transformer. Only selected frequencies have been studied for their harmful potential so far, because either natural observation or a lab study of a large number of rats is extremely expensive and time consuming. As for the power near a transmission line only being able to produce negligible amounts of current or voltage, Mythbusters is not always a credible source. I enjoy the show but sometimes groan at their mistakes. They and their tech people do not always approach a question in a way which would show the claimed effect. That said, people should stay away from powerlines and not attempt any such experiment. A conductor parallel to an energized conductor can have very high voltages induced in it, and the ground near a power system ground where imbalance current from a three-phase system goes through a ground rod can have a measurable and significant ground potential. Edison 15:46, 2 July 2007 (UTC)

Except that the frequencies being proposed are already well-studied. BBC News says the proposal is for 6.4MHz frequency EM waves to be used. They are currently used frequently - by ham radio operators! They are as safe any portion of the spectrum. Batmanand | Talk 16:14, 2 July 2007 (UTC)

Is it safe at the power levels involved? IIRC, ham radios don't usually involve power levels of more than tens of watts. --Carnildo 21:52, 2 July 2007 (UTC)

What is the field intensity that human beings near the transmitter for the wireless power would be subject to, and where is a citation showing that it's biological effects have been studied. So far I just see proof by assertion and hand waving. Edison 22:04, 2 July 2007 (UTC)

Doing a quick google search, it seems that laptop power supplies work at about 90W or so, in other words within the same order of magnitude as ham radios. So there is no danger. Batmanand | Talk 00:10, 3 July 2007 (UTC)

Above mentioned MIT guys accomplished only 40% efficiency. That means wireless power source would have to emit at 225W. This number might be bigger/smaller because of other considerations, but just because wired power supply works at 90W that does not mean that wireless power supply will work at 90W. — Shinhan < talk > 13:56, 10 July 2007 (UTC)

Nicotinate concentration in the blood or blood plasma

Can anyone enlighten us as to what the figure is? Thank you so much in advance, anon.

I found this: about 80 ng/ml (= 0.66 nmol/ml). Icek 21:54, 1 July 2007 (UTC)

What is a 'stable ectotherm'?

Hi all. I know that an ectotherm is a cold-blooded animal, ie a snake or fish. Your article doesn't express what a "stable" one is, however, and I was wondering what it meant. Much help appreciated ! Xhin Give Back Our Membership! 04:52, 1 July 2007 (UTC)

I think we need some context. Where have you come across this expression? Our ectotherm article doesn't mention their stability, and "stable ectotherm" returns zero Google hits. "Stable" simply means non-changing.--Shantavira|^{feed me} 07:51, 1 July 2007 (UTC)

Agreed, we need some context. At a guess, it sounds to me you'd be talking about an ectotherm whose body temperature nonetheless remained at a stable temperature. This could refer to creatures that I have heard of previously termed mass (or bulk) endotherms, and which Wikipedia redirects to gigantothermy. In short the idea is that the animal can essentially maintain a constant high body temperature simply by virtue of being so big that it takes a long time to lose heat from normal body processes such as digestion, rather than by actually controlling body temperature in the manner of endotherms. I first heard this discussed in arguments over whether dinosaurs were cold or warm blooded, in particular in reference to the real giants like the brontosaurus and brachiosaurus. --jjron 11:55, 1 July 2007 (UTC)

If a Tree Falls in the Forest MARK II

Perhaps this is a naive question, but ... how has science resolved the dilemma presented in "If a tree falls in the forest, and no one is there to hear it, does it make a sound?" ...? Thanks. (JosephASpadaro 04:33, 30 June 2007 (UTC))

Your question was answered at inordinate length yesterday. Please see above.--Shantavira|^{feed me} 11:26, 1 July 2007 (UTC)

Never mind that!

If a single photon passed through a double slit experiment but no one or no detector has observed it, is it behaving like a wave or a particle? 211.28.121.217 11:20, 1 July 2007 (UTC)

Re first question, as Shantavira says, please do not repost the same question when you have received an extensive reply. Re second question, even if you are trying to be silly, the answer is that it behaves as both - see Wave–particle duality. And in case you're wondering, strange as it may sound, even single photons display the properties of this duality. --jjron 11:59, 1 July 2007 (UTC)

Scientists make precise definitions and stick to them. It saves a lot of hassle. The rest of the world could learn this habit, it would make their unscientific pursuits much more efficient. Nimur 17:18, 1 July 2007 (UTC)

Re - first question. I never re-posted it. Some one else, for whatever reason, probably cut-and-pasted it and re-posted it. I do not have the time, energy, inclination, or interest to review the history logs and see who that "some one" might be. You are welcome to do so. In any event, please research facts before making accusations. Thanks. (JosephASpadaro 00:10, 2 July 2007 (UTC))

It was 211.28.121.217! Nimur 00:32, 2 July 2007 (UTC)

Yes, upon reflection, it seems that User 211.28 was merely using my question as a preface to introduce his/her "single photon" question. His photon question took the same syntax as my tree/forest question. What 211.28 was essentially saying is, "Who cares about the tree falling in the woods question, I have a single photon question to ask that seems much more interesting!" (JosephASpadaro 00:39, 2 July 2007 (UTC))

"I do not have the time, energy, inclination, or interest to review the history logs...please research facts before making accusations". And we do have the time, etc, to do this? What, we should research the history of all posters and how the question was created before answering their question? You must be joking! --jjron 02:38, 2 July 2007 (UTC)

Look, it was very, very rude of 211.28.121.217 to repost JosephASpadaro's text, including his signature. If I were Joseph, I'd be annoyed, too, especially after getting scolded for a repost which wasn't mine. If Joseph's reaction wasn't just what you would have liked, let's let it ride, okay? We shouldn't let 211.28.121.217's rudeness set the rest of us against each other. —Steve Summit (talk) 03:13, 2 July 2007 (UTC)

I agree with Steve Summit (at least, your 2nd, 3rd, and 4th sentences). As far as User 211.28, I assume good faith on his part; he was probably cutting-and-pasting simply to show the parallel between his question and mine. He was basically saying, "never mind that question posed above by JosephASpadaro ... let's take a look at my question! If you think the tree question was interesting, how about this question about photons?" I don't think he meant any harm. As far as Jjron, the answer to your question ("And we do have the time, etc, to do this?") is that the proof is in the pudding. Yes, apparently, Nimur did indeed have the time, etc, to do this. Furthermore, no, I am not asking you to research the history of all posters, etc. But, clearly, you did enough "research" to see that my original question was posted a day or so prior with extensive response. Not to mention, discussion and engagement and participation on my part in the thread. It would seem unlikely (at best) that I would engage in the extensive conversation posted a day or so earlier, only to repost the very same question the following day. Given the unlikelihood of that scenario, I would have assumed good faith. And the time that I spent researching the original post could just have easily been spent on researching who, in fact, submitted the re-post. So, yes, I will stick with my statement, which is: before you scold someone, make sure that the scolding is proper and appropriate. (Or, as I worded it, research facts before making accusations.) Bottom line: this is not a big deal, we all have bigger fish to fry, we can all move on. No harm, no foul. Thanks. (JosephASpadaro 04:01, 2 July 2007 (UTC))

Re Steve - agree with the gist of your comment. Three people had posted replies to this requestion, two had politely asked users not to repost the same question. However, a simple 'it wasn't me' was all that required from Joseph, instead he follows that up with a rude 'do some research you jerks' comment. That is what requires a response.

Re Joseph - I think you need to learn some real manners. Remember that the people posting answers here are unpaid volunteers giving freely of their own expertise to help out people like you. My guess is that Nimur has better things to do than research edit histories (I know I do), the fact that he did so as another favour to you should be appreciated, not met with a 'nah-nah he's got heaps of time to waste' comment. And if you cared to do your own "research", or rather just read the replies to your own questions properly, you would have seen that I posted the second response to your original question. This is where the extended discussion started - so of course I knew about the original question, I didn't have to research it. Oh, and as for doing some research, in fact I did do some research before posting my initial comment in this section and saw that you had had some run-ins before with other users on questionable use of Wikipedia, including, but not restricted to this, so in fact was suspicious that this could have been trolling on your part. Now, is that scolding "proper and appropriate" - yes, I think it is. --jjron 09:23, 2 July 2007 (UTC)

FWIW, while Joseph's words may have been curt, they certainly didn't strike me as rude. In particular, there was no implication of "you jerks" in there, for me. —Steve Summit (talk) 11:39, 2 July 2007 (UTC)

Steve Summit - thank you. Jjron - please re-read my original post in this thread. It says, quote, " ... please research facts before making accusations." You, completely of your own doing, interpreted those black-and-white words as, quote, "do some research you jerks." Clearly, you have interjected the negative tone and rudeness into the comment, fully of your own doing. And that is your issue, not mine. In other words, despite hard evidence, you are seeing only what you want to see. A second example of the same phenomenon: My statement, exactly, was (quote) "Yes, apparently, Nimur did indeed have the time, etc, to do this." And, completely of your own doing, you interpreted that black-and-white statement as, quote, "nah-nah he's got heaps of time to waste." So, once again, you yourself have interjected the negative tone and rudeness into a comment that, on its face, is 100% neutral and 100% factual. And, once again, that is your issue, not mine. And, once again, despite hard evidence, you are seeing only what you want to see. So, actually, you are making my case for me. Thanks. Let me offer you an example. In your statement to me, you said, quote, "please do not repost the same question when you have received an extensive reply." How would you like it -- and, more importantly -- how fair would it be to you ... if I subsequently asserted (from your direct quote) that in fact you said to me, quote, "hey, you stupid jerk, stop reposting the same damn question over and over" ...? I am quite sure that you would see the point that I am making here. So ... in conclusion, I am done with this thread. If you are the type of person who needs to get the last word in, go ahead. And we can call that the last word. As I said earlier, we all have bigger fish to fry than to belabor some semantic misinterpretation / misunderstanding. Also, I did notice that you offered some input on the original question (tree falls in the woods). Thanks for that. That question had been in the back of my mind for quite some time, and I found that thread interesting, informative, and enlightening. Thank you. And, to Steve Summit, thank you also. (JosephASpadaro 15:19, 2 July 2007 (UTC))

If nobody demands a document from Dick Cheney's office, is it part of the Executive Branch or the Legislative Branch? Gzuckier 16:09, 2 July 2007 (UTC)

That's hysterical. Next, Cheney will twist and turn words in such a way that he is in the Judicial Branch and, didn't you know, he is in fact the Chief Justice of the Supreme Court. Unreal. (JosephASpadaro 18:37, 2 July 2007 (UTC))

I am the "type of person who needs to get the last word in." I want everybody to know that I use Wikipedia with Popups and that it takes just a few seconds to scan a page history. If you aren't using popups, you should be! Nimur 07:23, 4 July 2007 (UTC)

Fibre glass Polyster Resin

I would like to know how to make fibre glass polyster resin and its chemical ingrediants with chemical ratio.

Sadly, our article on Polyester resin isn't very helpful. There is more information in Polyester. SteveBaker 16:10, 1 July 2007 (UTC)

Ganymede (moon) volcanic?

Hi, is Ganymede volcanic in any way? Io would be the most active volcanically, but I was just wondering. --Kjoonlee 13:03, 1 July 2007 (UTC)

Yes. If you go to this page: [2] and scroll down to "Volcanic Landforms on Icy Satellites" where it says "This mosaic illustrates the great variety of relief-forming volcanic landforms observed on the icy satellites, including Ganymede." - also, a bit further down, it's discussing some craters on Ganymede and says "Also visible is a large, irregular, caldera-like feature that may be volcanic in origin (right of Isis).". Ganymede's surface is certainly tectonically active - there would be earthquakes that would cause cracks to form - through which it's icy mantle would ooze out. Such 'volcanoes' as there might be would be water volcanos - so 'geyser' might be a better term. You should also check out: Schenk P. (1995) Volcanic constructs on Ganymede and Enceladus. Journal of Geophysical Research, 100, 19009-19022. SteveBaker 16:05, 1 July 2007 (UTC)

Decision tables versus classification tables

While both a decision table and a classification table are based upon truth table format it appears that they are different in some respects. For instance, in a classification table there can be only one rule for each dependent variable, that is, each rule is unique per table or context whereas in a decision table there may be more than one dependent variable which has the same rule per table or context. Where can I find a list of any other such differences between decision tables and classification tables? Ugly bag of mostly water 13:14, 1 July 2007 (UTC)

Decision tree, decision table? Nimur 17:25, 1 July 2007 (UTC)

The Decision tree article mentions that "...classification tree (discrete outcome)..." but nother more and does not state the type outcome of a decision tree although the Decision table article may suggest that it is exhaustive for the condition set. There seem to be other differences bewteen a decision table and a classification table, however, which are not expressed in either article or in any article related to either topic which I could find.

I'm not quite sure what your question is, but a decision table, easily visualized as a decision tree, can also be seen as a way to partition a many-dimensional space, where each decision splits the remaining partition in two. For the XOR problem for instance, with 2 parameters you'd first split the space in two, with a rule based on parameter 1 and then use two different rules on parameter 2, on the two parts. Alternatively, the same rule may be used twice, once in each half. So what kind of table can be used depends on how the categories are distributed in the many-dimensional space.

super tall

i'd really love to be super tall well 6ft (no bigger!) im 5ft 9 at the moment (plus im still young 16) but i read about Maria Sharapova's height and all the growth spurts she had plus i've got all the 'growth spurt' symptoms at the moment and i've always been taller than average (for a girl!) since the day i was born,so how can i put my 'growth spurt' to advantage and recieve maximum height?

There is very little you can do to increase growth, but there is some you can do to limit inhibiting growth. Lack of exercise and malnutrition both inhibit growth. So, exercise and eat a healthy balanced diet. Your body will take care of the rest to the best of its ability. However, I should note that I've seen multiple studies that show bone thicker under stress - in other words, the leg bones of a runner are thicker and longer than those of someone who never puts stress on their legs. To my knowledge, this type of observation has never been proven or applied to the body to increase growth. -- Kainaw^(what?) 18:02, 1 July 2007 (UTC)

SWIMING POOL CHEMICALS

I RECENTLY ACCIDENTALLY MIXED THE FOLLOWING TWO CHEMICALS AND THEY EXPLODED. I WOULD LIKE TO KNOW WHAT CHEMICAL EVOLVED FROM THIS MIXING.

CALCIUM HYPOCLORITE was added to ACID TRICLORO-S-TRIAZINETRIONE then water which caused the explosion.

CONTACT EDGAR ALLEN PAUL, AIA (Contact information removed)

Always add acid to water. The fact that you added water to acid is often sufficient to cause explosion. Nimur 20:19, 1 July 2007 (UTC)

Mixing concentrated acid and water generates a lot of heat, often enough to cause localized boiling, which causes a lot of spatter. You'd rather have a bucket of water with a little bit of acid spatter all over you than the other way around, which is why you add the acid to water. Gzuckier 16:13, 2 July 2007 (UTC)

Treadmill Question

When running on a treadmill, there is some internal "calculator" that displays various data: how many miles you've run, the speed at which you are running, the number of calories you have burned, etc. Does anyone know of either a website or a mathematical formula that computes these values? Basically, I would like to calculate the answer to a question such as this (generically stated): If I weigh X pounds, and I want to set the treadmill at X miles per hour, how many minutes of running will be required for me to burn X calories?

Namely, the questions (below), as well as other variants of the same question:

If I weigh 165 pounds, and I want to set the treadmill at 4.5 miles per hour, how many minutes of running will be required for me to burn 1,000 calories?

Variant – example: If I weigh 165 pounds and I want to run for 30 minutes and I want to burn 1,000 calories, what speed (miles per hour) should I set the treadmill on?

Variant – example: If I weigh 165 pounds and I set the treadmill for 4.5 miles per hour and I run for 30 minutes, how many calories will I burn?

Etc. Etc. Etc.

Of course, I can do this through trial-and-error on the treadmill. But (a) that would be an inefficient and laborious process; and (b) I don’t have a treadmill at my disposal at home, but only at the gym. I assume that there are websites where I can plug in the numbers and the calculator will compute the answer … or I assume that there is a (relatively simple?) mathematical formula that can do this. In fact, there must (?) be some formula that does this, as that very formula must be what is programmed into the treadmill apparatus. No? Thanks. (JosephASpadaro 18:35, 1 July 2007 (UTC))

Yes, a formula must exist if the treadmill is giving the output, but it's a "rough estimate" at best. I would not put a lot of stock in the numbers it displays for "calories burned." Nimur 20:06, 1 July 2007 (UTC)

I will take a "rough estimate" ... any idea where to find the formula? Thanks. (JosephASpadaro 20:20, 1 July 2007 (UTC))

This and this online calculator both use formulas in which energy burned is proportional to body weight times distance, with a proportionality constant of about 0.9–1 kCal/(kg*km). In your units, that would be (energy burned, in kCal) = (body weight, in lbs)*(speed, in mph)*(time, in minutes)*C, where the constant C is 0.0109 kCal/(lb*mph*min) according to the first site, and 0.0121 kCal/(lb*mph*min) according to the second site. This is of course all but complete BS, since the actual energy use must depend in much more complicated ways on body weight, speed, running skill, height, etc. But your treadmill is probably using a similar formula. --mglg_(talk) 21:04, 1 July 2007 (UTC)

To Nimur and mglg: why do you both put such little stock in these calculations? Isn't simply a non-controversial mathematical formula based on physics, biology, chemistry, kinesiology, whatever field of science? Why the skepticism and cynicim? Why is the formula not reliable? (JosephASpadaro 00:44, 2 July 2007 (UTC))

There are two problems: (1) measuring the mechanical work output of the treadmill user, and (2) figuring out how many of the calories the user is burning are going into that mechanical work.

Theoretically, the treadmill could measure the mechanical work you're putting into it fairly accurately. But I tend to doubt it does this, because it would be harder (for the manufacturer, that is), and given all the other uncertainties, it probably wouldn't be worth it. So my guess is that they make a simple estimate based on your speed.

The big problem is the connection between the calories you burn and the mechanical work you're doing. I'm pretty sure humans (like most animals, and most machines, for that matter) are about 25-30% efficient. That is, for each unit of energy (i.e. food energy) you burn, you can produce 1/4 to 1/3 of a unit of actual, usable mechanical energy. The rest of the energy you're burning is lost as waste heat (again, just as for machines). But the actual efficiency figure will probably vary widely for different people.

Finally, for weight-loss purposes, the amount of calories you "burn" while exercising is most usefully computed as the difference between the calories you're burning while exercising, minus the calories you'd be burning just sitting on a couch watching TV or editing Wikipedia (that is, your basal metabolic rate). But different people's basal metabolic rates vary all over the place.

So it's a hard problem. And, cynically speaking, there's no incentive for the treadmill manufacturers to work very hard at solving it. The people using the machines will certainly want some indication of "how many calories they're burning", but they're in no position to verify the numbers the machine gives them. So as long as the machine displays some vaguely-plausible number, which goes up the faster you run, everybody's happy.

The numbers probably aren't complete BS. But the fact that it's hard to find concise formulas in the open literature is suggestive. I'd guess that the various manufacturers guard their own formulas as trade secrets, and (as is the case for lots of trade secrets) not so you can't snitch them, but just so that you can't see how lousy they are. —Steve Summit (talk) 01:13, 2 July 2007 (UTC)

Treadmill (and those elliptical machines) are actually rather accurate if used properly. The formulas were not just made up. They are based on the "work" (from a physics standpoint) of moving your weight a specific distance. It doesn't matter if you run on your hands or legs - your body is putting the same amount of work into moving your body over a certain distance. In fact, treadmills are more accurate than running because, on a treadmill, you are not working against or with the wind (unless you use your treadmill outdoors - but that is ridiculous. Why would you even suggest taking a treadmill out to the park to run on?) The fault in treadmills is that they are normally NOT used properly. The person doesn't enter their weight properly (yes, the treadmills COULD weigh you when you hopped on). Also, most people hold the rails when they run. If you do this, you are not working to move your weight forward. You are just hopping a little and sort of bouncing in place. -- Kainaw^(what?) 01:25, 2 July 2007 (UTC)

Thanks to all for your input. This thread was certainly enlightening and informative. Kainaw -- are you saying that, when the user holds the rails on the treadmill, that is essentially "cheating" (i.e., lessening the work load)? I have been using them all along, assuming (since the rails are there) that that (hands on rail) was the proper way to use a treadmill. Aaaarrrggghhhhh! So, what's the proper form? Hands swinging by your sides? Thanks. (JosephASpadaro 02:25, 2 July 2007 (UTC))

Correct. According to our physical therapy people, you use the rails to maintain balance when starting and stopping. While exercising, do not hold on to them. As one of the ladies put it, you don't get any effective exercise if you just hold on to the back of a bus and let it drag you ten miles. You have to let go and run it yourself. -- Kainaw^(what?) 12:13, 2 July 2007 (UTC)

Kainaw -- yes, what you said makes perfect sense. Thanks. The bus example is a great parallel. But -- on a bad note -- you are effectively telling me that these past two months of me running/ sweating on a treadmill have all been for naught! Aaaaaarrrrrrrgghhhhhh! (JosephASpadaro 15:29, 2 July 2007 (UTC))

If you've been working up a sweat, then you've been exercising! Holding the rails on a treadmill is not the same as being towed by a bus: you are still working your leg muscles, your arms are taking some of the weight of your upper body, but by no means all. Some people find it hard to balance on a treadmill, so holding on to the rails could be a sensible safety precaution. DuncanHill 15:36, 2 July 2007 (UTC)

Business model

What is the name of the business model Microsoft uses to sell copies of its personal computer operating systems - providing an OS with a specific version number or name who's content is upgraded continuously until the version can no longer be updated to match current technology or is otherwise outdated and support can be justifiably removed following replacement by a new version name or number? What businesses have used or developed this business model prior to Microsoft? Ugly bag of mostly water 19:28, 1 July 2007 (UTC)

This probably does not belong on the science reference desk. Anyway, business plans tend to be proprietary and confidential. Needless to say, any software provider will try to optimize the frequency that it sells new versions, based on how often people will buy it and how rapidly it can be developed. Nimur 20:08, 1 July 2007 (UTC)

Business plan and business model are entirely different. Why do you keep guessing at answers to the questions I've asked? Stop doing it. Ugly bag of mostly water 07:38, 2 July 2007 (UTC)

Vendor lock-in, Tying (commerce)? --antilived^{T | C | G} 09:34, 3 July 2007 (UTC)

The business model you describe sounds like planned obsolescence. The article has some history. --HughCharlesParker (talk - contribs) 14:25, 5 July 2007 (UTC)

What did Surrealists like Andre Breton and others think about Zionism?

As much as I know Andre Breton and his surrealist group in Paris appreciated the foundation of Israel in 1948. But I really wasn´t able to find reliable sources for that. Can anybody help? 77.2.106.24 22:24, 1 July 2007 (UTC)

This belongs at the Humanities desk. Nimur 22:55, 1 July 2007 (UTC)

The link, for those looking for the answer. WP:RD/H#What_did_Surrealists_like_Andre_Breton_and_others_think_about_Zionism.3F Skittle 16:02, 2 July 2007 (UTC)