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May 4

The Unidentified Crawling Objects

What are they? these pictures are taken in New England. -- Toytoy 01:38, 4 May 2007 (UTC)

Possibly a centipede? Nimur 01:45, 4 May 2007 (UTC)

(ec) They're house centipedes. They are harmless to humans, but not to any roaches, flies, or spiders thinking about moving in with you. --TotoBaggins 01:48, 4 May 2007 (UTC)

Actually, not completely harmless... I got bitten on the foot by one last summer while I was on holiday (in the Dordogne in France) and it hurt a lot more than I was expecting. The next day I was emptying the bin and I got bitten/pinced/whatever by a European mantis. Gah. --YFB ¿ 01:54, 4 May 2007 (UTC)

Their bite is supposedly equivalent to a bee sting, ouch! But they do eat all the other bugs in your house. So if you can avoid them, they are best to leave alone, as they are like brilliant little roach-hotels running around killing other intruders. --Cody.Pope 09:01, 4 May 2007 (UTC)

When they are being attacked, they may shed legs (see the left image). What's wrong with them? -- Toytoy 02:27, 4 May 2007 (UTC)

Complete speculation, but I guess that they will shed a few legs so that a predator will be happy with that small, easy meal rather than the larger meal that is running away. 213.48.15.234 08:05, 4 May 2007 (UTC)

it looks like it has been squashed--Lerdthenerd 09:05, 4 May 2007 (UTC)

No. I didn't do anything other than spray insectide (I know it's not insect). It just breaks apart. -- Toytoy 15:54, 4 May 2007 (UTC)

Length of Legs

In human beings, which leg is usually longer, the upper leg or the lower leg? Does the relative lengths of the legs of human beings depend on gender, race, or age?The Anonymous One 08:59, 4 May 2007 (UTC)

I don't know about you, but I have a left and right leg, both of which are pretty similar in length. 213.48.15.234 09:53, 4 May 2007 (UTC)

Check out tibia, femur, and fibula. The femur, the bone of the "upper leg," is always longer (though I guess you could have a wierd mutation). The fibula (one of the bones of the "lower leg") differs in shape between genders. Also note that "upper leg" is more accurately called the thigh, and the "lower leg" is the leg itself. Someguy1221 10:30, 4 May 2007 (UTC)

The relative lengths depend on whether you go to a chiropractor doing "free" public screenings. Unless you appear unable to afford a series of adjustments, he will demonstrate a discrepancy and offer to fix it.[1][2] alteripse 11:25, 4 May 2007 (UTC)

Well, that is rather biased, and it doesn't seem to address the original question. I went to a Chiropractor for some back problems, and I could afford treatment. He commented that I had a good symmetrical stance, and had an even walking rhythm. He physically examined my back and was able to point to the exact spot (with out me telling) where I was hurting. He adjusted my back, and I think that is was definitely worth it. The ever present low grade pain that I had been living with for over a year was gone. To me this was a much better treatment that the pain killers and muscle relaxants that I had been given when I originally hurt my back. Chiropractic treatment can't cure cancer, but sometimes people do benefit from it. -Czmtzc 12:49, 4 May 2007 (UTC)

Chiropractors can help if you genuinely suffer from a pinched nerve. Unfortunately, the lack of regulation has also led to a world full of chiropractic quacks. StuRat 23:49, 4 May 2007 (UTC)

Maglev Speed

This question was placed in the article JR-Maglev by Chris apodaca . I will tell him/her that I reposted it here.--MrFish^{Go Fish} 11:40, 4 May 2007 (UTC)

Is it true that a maglev train can be powered to the speed of light if it did not have to worry about aerodynamics.

1. With today's understanding of science, Nothing with mass can be accelerated to the speed of light. It's impossible.

2. Even with absolutely no atmosphere to slow the train with viscous drag, there would be friction created by other effects in the magnets (depending on the type of maglev used).

3. How on Earth would you turn a corner going at the speed of light with mass? 213.48.15.234 11:58, 4 May 2007 (UTC)

Doesn't light have mass? How else could it be effected by gravity? Jeffrey.Kleykamp 12:19, 4 May 2007 (UTC)

No, photons have no rest mass. They are affected by gravity anyway, general relativity being like that. Algebraist 12:28, 4 May 2007 (UTC)

Mass bends space. Therefore even massless object curve around massive objects, because the space is curved.Czmtzc 15:46, 4 May 2007 (UTC)

Well, it bends spacetime. Capuchin 21:37, 4 May 2007 (UTC)

An extremely high speed maglev in an evacuated tunnel could benefit from two systems:

1) A straight line could be drilled between each pair of stations. This would mean it would go deep underground in the middle. The pairs of stations would need to be fairly close, or the depth in the center would go down too far, where the temperatures are extremely hot. The advantage of such a system is that no energy would be needed for acceleration and decel (other than to overcome any residual friction), as gravity will slowly accelerate the train at the start and decelerate it at the finish.

2) A train following the curvature of the Earth and going at the proper speed would have a centrifugal force equal to gravity, so wouldn't need any energy to levitate it, as it would essentially be in orbit at ground level. The speed of escape velocity at the Earth's surface is 11.2 kilometers per second (~7 mi/s). This system would only be suitable for very long distances between stations, such as London to Tokyo, and would certainly kill everyone on board in an accident.

Hybrid systems, that go deeper in the middle but still somewhat follow the Earth's contour, or trains that go a substantial fraction of the escape velocity at the surface, could also be used. StuRat 23:35, 4 May 2007 (UTC)

Plant life

I have a Mermaid Vine houseplant that must be sixteen years old.It definitely looks past its prime.Do houseplants have recognised life spans as do,for instance,trees? Where can I find this sort of information? —The preceding unsigned comment was added by 86.13.217.242 (talk) 13:44, 4 May 2007 (UTC).

Yes, an individual Mermaid Vine plant (probably Cissus sp.) has a definite life span. Propagating it by cuttings "resets the clock" for the new plants; but, sadly, not for the parent plant. See Vegetative reproduction. Dr_Dima.

As for the more general question, some plants do have life spans (especially annuals), while others don't, and survive as long as all the proper conditions remain for their survival. StuRat 23:12, 4 May 2007 (UTC)

The knowledge needed to start from scratch

I quite often wonder what would happen if you take a few thousand modern-day people from around the world and make them the only survivors of an apocalypse - and in this hypothetical let's assume all technology was destroyed and all the resources we had were back to their natural forms - the sea, jungle, forest, grassland, etc.
So to clarify there would be no records of information, no manuals, textbooks, nothing - just natural resources - heck maybe the people are even naked to begin with.
All that they have left are memories and the knowledge they had before the apocalypse.

I then wonder how much technical knowledge is needed among people to do these various things:

• Manufacture metal
• Generate electricity
• Build a computer
• Build a labroratory
• Fly a rocket
• Etc

1. How possible is it to do those things from absolute scratch using only natural resources? - in other words in order to harness metals it would be extremely difficult to do without metal tools
2. Similar to the previous question, is it in the power of a single person to posses the knowledge of these things (see list above) - or is it currently highly unlikely that a single person possesses the knowledge to do all these things.
   

Any thoughts or references to these types of questions would be appreciated.
Rfwoolf 14:04, 4 May 2007 (UTC)

Metals don't have to be particularly difficult. Fire, wood, and clay are easy enough to get hold of; from there you get to kilns, pottery, charcoal, and ceramics—all the tools you'll need for very basic metalwork. (A post-apocalyptic world would actually have gobs of refined metals just lying around, but you've stipulated that all of that has been lost.) With very modest tools you start being able to gather coal, which lets you make steel. It's time consuming to scale up these technologies from scratch, but certainly not impossible.

Once you have coal, metal tools, water-powered mills, and the capacity to smelt metals, you're able to start doing things like draw wires and machine metal. That gets you to electricity, if you want it.

Early electronic computers (vacuum tube-based) could have been built using technology available in Thomas Edison's time, though you'd really want electrically-driven mass production equipment. Semiconductors to build transistors are going to cost you another whack of time and effort to get pure silicon or germanium. Really, it's all a bootstrapping issue—since we already know how to do all of the things listed, it's just a matter of building the infrastructure (adequate supplies of fuels, metals, tools, and electricity) to support each task. TenOfAllTrades(talk) 15:07, 4 May 2007 (UTC)

There's also a question of critical mass. At the hypothesized level of "a few thousand", you clearly won't have a biological store of all of the accumulated specialties of knowledge. You'll also be polluted with a great many people who believe they "know" something, but are quite, quite wrong; it wouldn't take many of those folks to undo all the correct knowlegde brought forward. And finally, a few thousands aren't enough to immediately do everything needed to be done to restore technology. Imagine how many people it takes to build a big hydroelectric dam, for instance (especially when you trace back everything that goes into the dam).

Maybe we'd better hope that a good copy of Wikipedia survives and that it wasn't too vandalised when the snapshot was taken?

Atlant 16:02, 4 May 2007 (UTC)

(adding some paragraph breaks per Atlant:)Yes, a copy of Wikipedia or Diderot's encyclopedia or Britannica (even th e 1911 edition) would be pretty useful. If it did not contain detailed plans for every doodad they needed, at least it could steer them toward things that were doable and away from alchemy and efforts to build perpetual motion machines or find the fountain of youth. Prisoners of war in Hanoi pooled their memories to reconstruct Bible passages, fo a coterie of scientists could make some papyrus and write down most of Halliday and Resnick's physics textbook, etc. The premise allows for post-apocalypse people in a non-post-apocalypse world. After any conceivable natural or man-made event such as giant asteroids striking, nuclear war, biological war, or the global triumph of some vicious ignorant tribe of Luddites, there would be a virtually inexhaustable supply of steel, copper, lead, brass, aluminum and every other useful metal. Native Americans quickly adapted from flint arrowheads to ones made form scavenged metal when Europeans moved in. In some developing countries, they can't keep guardrails in place along highways because the steel is such a handy thickness for fabricating tools. The ruins of buildings would furnish vast quantities of rebar, steel columns, steel and copper from pipes, and steel from beams and columns, as is evident if you watch the recycling which goes on when a building is demolished.

If nasty space aliens somehow used nanomachines to remove all our buildings, roads, sunken ships, buried pipelines, etc, then we would not be back in the world that our primitive ancestors found, because all the easily found petroleum, coal, and ores would be long gone. Your scenario would have to move modern people back through time to the primordial past, or to a different but similar unspoiled planet. In such a world, assuming it was like pre-Columbian America but without the native population, with the mineral exploitation clock reset to zero, on day one some survival specialists who knew how to make stone tools and start a fire without matches would be invaluable, as would be hunters and fishermen, as well as people who are born leaders to keep the people rational in a challenging situation. An historian of science and technology preferable who has worked in industry and with woodshop and metalshop skills, would need a labor force to do the drudge work of cutting and hauling wood and stone, and digging in the ground to extract mineral ores. You use flint to make flint tools, which can make wooden wedges to split trees into planks and to quarry stone. You use fiber to make rope, which combined with strong backs can move large stones and timbers to make structures. Animal hides bones and sinews are very useful in the beginning. A few Boy Scout and Girl Scout vets would be useful, along with military people who have survival training.

In a year or two they should be at the level of the native populations of pre-Columbian America, but likely with a large death toll due to starvation and disease. Agriculturists would be needed to feed those workers, and doctors (hopefully with a knowledge of medicinal plants) to keep the work force healthy. Someone would need to start in selectively improving the native plants and domesticating cattle, sheep, goats, equine species, and dogs, as well as bees and hopefully silkworms. You need hides, wool and and plant fiber for clothes and industrial processes. Domesticate cats and you lose less of your grain crop to rodents. Carpentry and stoneworking skills would be needed to build the first generation of factories (due to the lack of iron and steel). The metallurgist would have lots to plan. Coal, timber and iron ore were readily available in many countries. Tin and copper make brass. Zinc and copper provide batteries. Mercury and glass allow good vacuum pumps. (You did include glassblowers? Shoemakers, seamstresses, brickmakers, boatmakers, and all the trades whose work spawned descendent's names: wainrights, coopers, bakers, brewers, turners, cordwainers, weavers, schneiders, etc?) Chemists would have to start producing basic industrial chemicals such as sulfuric acid and chlorine. Water power and steam engines fueled by coal could be the first generation prime movers to power big factories with overhead shafts driving belt operated tools, the first generation of which could be primarily wood with iron cutting surfaces. There were a few big iron meteorites from which natives obtained iron for tools. Given ore, stone for furnaces, and forests for charcoal, our ancestors made lots of iron with low tech furnaces. Metal allows movable type which allows books to preserve the knowledge in the memories of the first generation. Some engineers and architects and urban planners would be helpful to avoid stupid mistakes in putting up buildings and laying out towns. Chemists hopefully had the periodic table pretty well memorized before they left. Mathematicians should get to work building slide rules and calculating math and trig tables.

The second generation of technology would be able to extract copper and draw wire, and insulate it with cotton or silk. Now you can make dynamos, power lines, transformers, motors, arc lights for public spaces, and electric lights for homes. Light bulb technology allows vacuum tubes and you have radio and computers. Given a hypothetical Eden, there should be an increase of population to furnish the labor and adundant raw materials, such that your "few thousand" well prepared individuals could (optimistically) have early 20th century technology in 30 to 50 years, starting with a "few thousand" well prepared Robinson Crusoes.Look at the Amana Colonies for an example of colonists numbering about 1000 who migrated from Europe to the the east coast of the U.S then to the midwest, who were largely self sufficient, with people of each generation in the late 19th early 20th century assigned to print books, make shoes, build excellent furniture, brew beer, etc.) Edison 16:07, 4 May 2007 (UTC)

Gee, Edison, surely the paragraph break would survive, wouldn't it?

Atlant 16:31, 4 May 2007 (UTC)

First up you'd need a food supply, which means farming knowledge. The industrial revolution was kick-started by the green revolution. But the very basics, like the specifics of crop rotation would need to be known or rediscovered. Once that's in place, we can branch out a bit. Even fairly simple science can be difficult to impliment, as anyone who's watched Rough Science will know. Then it'd be a race against the clock, as you wouldn't have anyone with first hand knowledge in under 100 years, but knowledge can be passed on to the next generation, I guess. --h2g2bob (talk) 16:13, 4 May 2007 (UTC)

Do you mean the British agricultural revolution, h2g2bob? Algebraist 17:34, 4 May 2007 (UTC)

I've thought about this question a lot. My favorite critical technology -- not mentioned so far -- is the lathe. It's essential for forming threaded parts like screws, but it contains as one of its essential components a long lead screw, so there's a nicely-encapsulated bootstrap problem there. —Steve Summit (talk) 15:03, 5 May 2007 (UTC)

Nice to see that other people have similar thoughts. Often if there is nothing else that can be done I wonder how human progress (in a very broad sense) could be improved if we could use a hypothetical time machine to send something back in time. I imagine several levels of possibilities of such time travel. One, to go back in a kind of spacetime ship, carrying usefull things. Two, go back as a spirit only and take over the mind of someone living at that time. Three, be preborne back in time, with old knowlage becoming availabe as you grow up. Four and five, establish two way or one way information transfer to someone living in the past, for example, by apearing in their dreams.

Now that I see I'm not alone I wonder and ask if anyone knows of other people who have these things more elaborated, perhaps written down or in some kind of (please, non too fictional!!?!) discussion forums? 84.160.226.72 20:50, 4 May 2007 (UTC)

I would say we need science to progress slower, so it doesn't outpace social developments, as it has in our world. We now have tribal societies (like Pakistan) in possession of nuclear weapons, not a good combo. StuRat 22:58, 4 May 2007 (UTC)

As I remember the first two nuclear bombs that were actually used for mass destruction didn't come from a tribal society. I hear that the majority of US soldiers in Irak were in pro of torture. Democracy does not make better people, it only provides more efficient means to deal with internal conflicts. 84.160.226.72 08:01, 5 May 2007 (UTC)

You might be interested in the book Earth Abides, by George R. Stewart. While the setup isn't quite the same as yours (technology was preserved, but very few people survived a plague), the direction it takes is quite interesting, dealing with the loss of a "critical mass" of humanity. Ultimately, the remaining people aren't able to maintain the infrastructure and they lose their technology (as when they can't keep a forest fire from destroying the town) and even lose their belief in science, instead resorting to primitive beliefs (somewhat similar to what happens in Lord of the Flies). StuRat 22:51, 4 May 2007 (UTC)

I recommend All_the_Weyrs_of_Pern. You need to read the novel, you won't get enough from the Wikipedia article. DGG 23:01, 4 May 2007 (UTC)

This all is just tip of the iceberg and you have only uncovered the whole genre of Alternate history. One of my favorite book genres :) One of the biggest problems of a society without any books, computers and such would be transfer of education. In first years there would be an imperative on everyone having to help grow enough food and other essential stuff, and it will be become harder and harder to preserver higher-level knowledge. Pern examines that nicely, but even they started with books (that deteriorated after hundreds of years). And who knows what would happen without AIVAS... In 1632 series a whole town is transported back in time to year 1632. But with books, computers and so on. Even so, after 3 years there are many large problems, some of them to do with access to rare ores, producing stainless steel and so on. Baen's Bar has a lot of discusion about this at [3] (registration required). Shinhan 12:40, 5 May 2007 (UTC)

DGG above recommended "All the Weyrs of Pern", but another Anne McCaffrey book probably matches the premise even closer: Freedom's Landing. Not so much post-apocalyptic as "humans abducted by aliens and dropped on an empty planet" (which is not entirely correct but sums up how things look at the start). Confusing Manifestation 23:11, 6 May 2007 (UTC)

The death rate would probably be very high, because with antiseptics (see hygiene hypothesis) modern people have weaker immune systems than pre-civilized people. On the other hand, we understand sanitation better. On yet another hand (??), the majority of North American Native American groups tended to have few sanitation problems due to low populations and mobility, and their life expectancies weren't all that high. 24.167.75.163 02:11, 7 May 2007 (UTC)

Feedback from the asker

Thank you all so very much for your feedback on this, all the answers have been very interesting. I suppose I should have rephrased the question as "What if a few thousand people with the top technological knowledge were all transported back to pre-civilization with only the clothes on their backs and their knowledge, skills, and memories."
One of the questions that wasn't answered however was the one about whether or not there are individual people out there that have the knowledge to recreate a technology from scratch - so even though it may take thousands to build a power plant, maybe there's a guy out there that knows how to build one all by himself in a pre-civilized world. That's what I'm wondering about as well. I will be creating another question to focus on this aspect. Thanks again! Rfwoolf 13:27, 5 May 2007 (UTC)

(NB: This question was asked separately below...see answers there!) SteveBaker 15:54, 5 May 2007 (UTC)

little question

In the event of an adoption of a Non-Nuclear Proliferation Act in all countries north of the equator, would it be possible to lower the mandatory minimum military age from sixteen to six with the provisor that the agricultural marketing board would not be adversely undermined tomorrow or the day after? 138.130.23.133

Huh? I don't really get the question. Most nuclear powers already sign the Nuclear Non-Proliferation Treaty. Nuclear weapons can be fired from the southern hemisphere into the northern hemisphere and vise versa. In any case, I'm sure people will have a lot to say on child soldiers. As for agriculture, that has many international problems already, largely related to the principles of free trade conflicting with the first world's use of subsidies and tariffs related to agricultural produce. If you can clarify what you mean, we can help you better. --h2g2bob (talk) 15:58, 4 May 2007 (UTC)

Electrical conversion

Some BLDC (brushless direct current electric motor) 3 phase motors are variable speed and appear to achieve this using either frequency modulation of constant pulse width (50% duty cycle), constant voltage and constant current or by pulse width modulation at constant frequency, constant voltage and constant current. I do not know which one predominates.

My question is how do you convert volt amps (VA) to watts (W) for such motors?

Would you calculate three-phase conversion as follows:

("POWER FACTOR" means motor efficiency, which best follows the applied power and RPM according to a tilted parabolic curve with a maximum of .80 at 300 RPM)

       WATT (W) = VOLTS x AMPERES x POWER FACTOR x 1.73
                                                                                 
       36x20x1.73 = 1245.6   1245.6 * .80 = 996.48 W

71.100.2.43 14:52, 4 May 2007 (UTC)

Please provide the words behnd abbreviations such as such as BLDC, since they may not be familiar to Ref Desk editors who are otherwise familiar with the topic of the question. Power factor makes sense with sinusoidal current and voltage. When the current and voltage are not even remotely sinusoidal, being pulses of variable duty cycle, it would seem to make more sense to simply integrate the instantaneous product of current times voltage throughout a cycle. This should be a trivial exercise when dealing with theoretical pulses. When measuring field data, recorders such as those by Dranetz and BMI can use calibrated current probes and voltage probes and a sampling process wherein analog to digital convertors sample the parameters at a high enough frequency (1000 Hz?) to capture the harmonics which contain meaningful amounts of power, then numerically integrate. These instruments should be able to print out or provide a digital record of RMS equivalent V, I, and P. "Parabolic motor efficiency" gets zero Google hits. Edison 15:20, 4 May 2007 (UTC)

In the absence of sinisodial variation then would you simply drop 1.73 but retain motor efficiency or the "POWER FACTOR" as listed for applied power and RPM of the motor to obtain the rated power in watts? 71.100.2.43 16:08, 4 May 2007 (UTC)

If you knew the integral of instantaneous volts and amps in each phase, the total is the sum of the three. Edison 16:19, 4 May 2007 (UTC)

BLDCs that are powered from 3-phase mains power almost all include power factor correction circuitry so that they draw roughly sinusoidal, phase-correlated current.

Atlant 16:34, 4 May 2007 (UTC)

Wait – a DC motor powered from 3-phase AC? That must involve circuitry to convert the AC power to (pulsed) DC, and the resulting voltages and currents on the DC side could be very different than on the AC side. Atlant is talking about the current drawn on the 3-phase AC side, but other of the above responses refer to the voltages and currents on the DC side. So to avoid confusion: is your question about the voltages and currents drawn from the line on the AC side, or delivered to the motor on the DC side? --mglg_(talk) 19:10, 4 May 2007 (UTC)

To eliminate any confusion the entire supply is from battery power and the controller does not convert (or invert) this to AC. My uderstanding is that current and voltage remain constrant and the circuit provides variable power by either modulating the width of the phase under constant frequency or by modulating frequency under a constant phase of say a 50% duty cycle or width. "Conversion" here refers entirely to conversion from Volt-Amps to Watts. 71.100.2.43 20:29, 4 May 2007 (UTC)

I see, "3-phase" referred to the construction of the motor, not to any AC power source. Thanks for the clarification. I think your assumption that both current and voltage are constant during each pulse must be invalid. The motor will define some time-varying relationship (a "load condition") between the voltage and current, imposed by the constant resistance and inductance of the motor windings together with the time-varying back-EMF caused by the rotating magnets. The driver will impose a "driving condition" (effectively open-circuit when the pulse is off, and either constant voltage or constant current (or most likely an intermediate case, which can be thought of as constant voltage plus internal resistance) during the pulse, onto the windings. The load condition and the driving condition will together define the voltage and current. Because the resulting voltage and/or current will vary with time, even during each "on" pulse, the best answer I can come up with is Edison's advice to integrate the instantaneous product of current times voltage throughout a cycle. --mglg_(talk) 21:03, 4 May 2007 (UTC)

Thanks for explaining the abbreviation. These motors should have clear advantages over brush type motors in low power, light weight application. Nikola Tesla would have heartily approved. The article says DC controllers feed full positive and negative power to two of the legs at a time. It should be possible to get better efficiency by using sinusoidal currents, which could be approximated from a battery supply through suitable electronics. Variable frequency power supplies are made for motors in the thousands of horsepower, which convert AC to DC and back to variable frequency AC for "soft starts" to eliminate the flicker caused by the starting of huge motors. If it works for kilovolts and kilohorsepower, it shoudl be easily implemented for the power levels you quote. Edison 22:51, 4 May 2007 (UTC)

I understand that it is an option but at significantly greater controller cost (two to three times maybe or more). Some motors I've seen try to deal with the problem of jerky starts by skewing the stator teeth and thereby to keep costs low (but then charge twice as much for this inovation). While Nikola would probably approve electronically produced AC from a DC supply for AC induction as a good thing I'm not so sure about skewed teeth as anything else but slight edge up on the competition. As LED STARS seem to have significantly increasing the efficiency of using current to produce lumens innovations that wpuld do the same for induction would be remarkable. 71.100.2.43 02:30, 5 May 2007 (UTC)

black hole

why there is blackholes ? —The preceding unsigned comment was added by 213.42.21.151 (talk) 16:37, 4 May 2007 (UTC).

See the cunningly named article black hole. Algebraist 17:30, 4 May 2007 (UTC)

If you do not understand the article fully, feel free to come back and ask a (more specific) question. Also, try typing something you want to know about in the search box at the top of this page to the left. [Mac Δαvιs] ❖ 18:41, 4 May 2007 (UTC)

Indicator for presense of Humalog® insulin

What chemical indicator would react by changing color to the presence of Humalog insulin on fabric by a color change, whether the fluid is present in a dried or liquid state? The insulin (which is clear) is described as follows: "Each milliliter of Humalog® insulin contains insulin lispro 100 Units, 16 mg glycerin, 1.88 mg dibasic sodium phosphate, 3.15 mg Metacresol, zinc oxide content adjusted to provide 0.0197 mg zinc ion, trace amounts of phenol, and water for injection." It has a pH of 7.0-7.8. I am looking for an indicator chemical which would react perhaps with the Metacresol or some other component to provide a color change indication, but would not react with water or perspiration. Some other method such as a light source which caused fluorescence in the presence of the product would also be good. The metacresol is apparently a coal-tar derivative, strong smelling, and present as a preservative, and seems like it might be a good possibility to react with an indicator. Edison 17:26, 4 May 2007 (UTC)

Depends on if you want to destroy the fabric or not. A blacklight might work. Many organic compounds, especially aromatics like cresols and phenols, and most likely the insulin, should glow under a blacklight, although there are a lot of substances that will glow (possibly the perspiration). If you have access to a lab, a ferric chloride test might work on the cresols and phenols, but that would require trying to extract the compound from the fibers, etc, and may react with water. --Bennybp 20:32, 4 May 2007 (UTC)

Why would anyone wish to do such a thing? If you want to quantify m-cresol, perhaps you'd get lucky with something like p-dimethylaminobenzaldehyde. One can reasonably assume that it would form a dye, along the theme of Spy dust. Wot, no article on spy dust? 129.170.29.111 21:18, 4 May 2007 (UTC)

I see that an improvement could be made to insulin infusion sets used with insulin pumps. Presently the pumps will give an indication if there is blockage in the catheter, but if the insulin is leaking due to a bad connection at the infusion site, or if due to degradation of the tissues and skin over the several days the preparation is left in place, it is oozing out of the patient's skin, there is presently no way of telling except for the patient's blood sugar reading going dangerously high. An adhesive cloth patch covers the skin at the infusion site. There should generally be none of the medication around the infusion site, so an indicator sensitive to any of the components of the medication would provide a visual indication that the site was leaking, something that the brain of an insulin pump can't detect. Edison 22:11, 4 May 2007 (UTC)

Per [4] p-dimethylaminobenzaldehyde is "slightly hazardous in case of skin contact" and "Repeated exposure to the substance can produce target organ damage" so a possibility but less than ideal. Anything else that would change color in contact with Metacresol? Edison 22:37, 4 May 2007 (UTC)

The only leakage indicator you need is your nose (or someone else's if you are not a contortionist). Cresol and phenol have strong, unmistakeable odors. Sniff near the hub or at the infusion site and you will see what I mean. alteripse 00:23, 5 May 2007 (UTC)

Smell is not VISUAL as requested, and large quantities of te chemical lost would be required to allow an olfactory detection. Looking for something like phenolphtalein (which doesn't work). Edison 06:39, 6 May 2007 (UTC)

Is there a database of chemical indicators where one cold look for something to achieve the stated goal of reacting to a component of the medicine by a color change? Edison 14:17, 7 May 2007 (UTC)

Microwave Ovens

I have recently received an e-mail to the effect that research at John Hopkins reveals that putting plastic containers in a microwave oven releases dioxins which can cause cancer, especially breast cancer. True???68.106.12.232 20:10, 4 May 2007 (UTC)

No. Snopes page debunking this particular email. --LarryMac 20:24, 4 May 2007 (UTC)

THIS urban legends site provides a more comprehensive and referenced answer, and their conclusion isn't as clear-cut as Snopes'. Anchoress 23:56, 4 May 2007 (UTC)

The question specifically referenced dioxin, though. --LarryMac 00:11, 5 May 2007 (UTC)

Yes, I noticed that. Anchoress 00:16, 5 May 2007 (UTC)

However, if you microwave plastics (or foam-type containers) to the point that they melt and mix with the food, then you do, indeed, expose yourself to a variety of toxic chemicals, some of which may be carcinogenic. StuRat 22:26, 4 May 2007 (UTC)

It's generally not recommended to eat plastic, melted or otherwise ;-) Someguy1221 23:14, 4 May 2007 (UTC)

IIRC, Consumer Reports magazine mentioned years ago that there are two different chemicals used to make plastic wrap. One was low-density polyethylene and the other was Polyvinylidene chloride (sold under Dow Chemical Company's trademark of 'Saran Wrap') that used (more?) plasticizers. That second wrap was not recommened for microwave cooking, but I see from our article that Dow switched to LDPE in 2004.

Atlant 23:57, 4 May 2007 (UTC)

In a similar vein, can anyone confirm or deny that microwaving a CD produces Arsenic? --Kiltman67 02:25, 5 May 2007 (UTC)

I think you might consider rewording that question to releases Arsenic since we're talking about an element (although produces Arsenic may be sufficient in some contexts). And obviously it need be a element used in production. Root⁴(one) 03:45, 5 May 2007 (UTC)

It is apparently used "in construction of electrical semiconductors, diodes, and solar batteries" according to Occupational Safety and Health Guideline for Inorganic Arsenic and its Compounds (as As), Potential Human Carcinogen. That article was created a few years before CDs really became popular AFAIK ('88). So you might not want to microwave that solar panel or that hard drive you have lying around ;-) Root⁴(one) 03:59, 5 May 2007 (UTC)

May 5

Interstellar probes end points.

To date, 4 interstellar probes were lunched. What stars will become end points of those probes? And, how long will it take for each probe to get there? TestPilot 01:06, 5 May 2007 (UTC)

When you say End Points are you asking what's their intended destination? Because as far as I know none of them were planned any further then leaving the solar system. --Kiltman67 02:28, 5 May 2007 (UTC)

StuRat asked a related question on April 29. He provided this, which gives some indication which way they were headed and how fast...after "lunch". Clarityfiend 04:46, 5 May 2007 (UTC)

Chemical rockets, like the ones used to launch those probes, are insufficient for interstellar missions. At their current speeds, it would take them thousands of years to reach even the nearest star at about four light years out. You can count on no serious interstellar missions until someone perfects and builds a solar sail, Bussard ramjet, or something along those lines. Maybe even an Orion if you have a pile of nukes handy. Someguy1221 09:41, 5 May 2007 (UTC)

Not necessarily. All that is required is patience. We can launch a vehicle with enough speed to reach solar escape velocity. So if we are patient we already have the technology. The way to get patient is to live much longer. As I have explained before, I believe we'll figure out how to transfer out intellects into computers within 30 to 40 years. At that point, you can lower the clock rate on your CPU and time will seem to simply fly by. Taking a thousand years to travel to the next star wouldn't be so terrible if it only seemed like a week of your life. SteveBaker 20:12, 5 May 2007 (UTC)

One was destroyed in Star Trek, as for the rest, see Olber's paradox

The current probes are moving so slowly they are likely to be collected by future faster craft and placed in museums before they reach any other solar systems. StuRat 08:08, 6 May 2007 (UTC)

Spider identification

hi i need another idetificaion on a spider as there are many here lol. i got more info then the last time i did this so here it goes. This spider has a clear brown body with a clear abdomin. almost see through and is acording to my aunt about 1 inch big. a bit from this spider isnt exactly deadly but instead it desulves your tissue quite quickly *bout a week for a large noticable area* i really want to read about this spider so a link to a article is much appreciated thanks!! User:Maverick423 If It Looks Good Nuke It 03:42, 5 May 2007 (UTC)

It might be a Brown recluse. The spider bite article lists all venomous spiders that bite humans. -Arch dude 11:14, 5 May 2007 (UTC)

The Brown recluse has a very clear fiddle shape on the back, which wasn't in the description. The wound characteristics do sound like the recluse. When it heals, the wound may be a depressed area like a bullet entry wound. Medical care is essential. Edison 15:09, 5 May 2007 (UTC)

Visible Laser Light

When looking perpendicular to/at a beam of green laser light what am I seeing? Just what is the beam? Would I see it as it passes through a vacuum?

12.175.230.38 04:33, 5 May 2007 (UTC)Greg

This has been asked before; you might find it searching the archives. But, as I recall, the consensus was that you would see laser light scattered by dust particles and other gunk in the air. I'm not sure what you mean by your second question; the beam is light, which differs from ordinary light by being all of the same frequency. No vacuum is perfect, so if the beam was intense enough, you might be able to see it. Clarityfiend 04:56, 5 May 2007 (UTC)

You wouldn't be able to see the beam even in a reasonably high vacuum. Scattering off tiny particles (like air molecules) is fairly inperceivable. I've never personally observed any noticible scattering of a visible-wavelength laser beam (several milliwatts) in a clean room environment (that is, an area where there are very few particles larger than a micron in diameter). Also, the photon created by a stimulated emission has identical phase and propagation direction to the (other) photon that resonantly couples with an excited electron of the same frequency and phase to cause the stimulated emission. Contrast with spontaneous emission (which dominates in sub-threshold semiconductor lasers and is the primary process by which LEDs operate), which releases photons of random phase and propagation direction (and less predictable frequency). Basically, the photons created by this optical amplification process are identical, which is what gives the laser its coherence characteristic. (line width broadening mechanisms in lasers are mostly related to variations in carrier population distribution, which in a nutshell changes the probability for stimulated emission at a given energy) -- mattb 05:42, 5 May 2007 (UTC)

I don't think most of that has anything to do with the question. Someguy1221 09:34, 5 May 2007 (UTC)

mattb, among other things, explained why you wouldn't see the beam in vacuum or in any Cleanroom environment. Also, the Physics portion of the Laser article talks about what and why of lasers. Shinhan 12:52, 5 May 2007 (UTC)

Sorry, my explanation did ramble a bit. The point of it was to explain a bit further about the stimulated emission process since the first response didn't make it clear that lasing implies more than simply monochromatic light emission. I don't think many people realize that stimulated emission does actually create identical photons, not just photons of the same energy. This is an important point. -- mattb 12:38, 8 May 2007 (UTC)

This is one of the comments made about movies - that laser beams would not just show themselves as being solid - in real life you would only see the laser as it hits dust particles or solid objects - so it wouldn't be visible in thin air. Also using fancy goggles to see them would not be very effective at all (apparently). Technologically the lasers in movies would also have to have a laser side that emits the laser beem and a receiving side the detects whether the laser is on or off (and when the burglar steps in front of the laser it does not get received by the receiver and a giant cage will then come crashing down killing the burglar) and apparently that type of technology is a) quite expensive, b) very hard to align the laser and the receive perfectly, and c) ineffective (there are motion sensors that could detect the presence of a burglar).

Apparantly the best way to see the lasers would be to spray a dusty/smoky aerosol.

Rfwoolf 13:48, 5 May 2007 (UTC)

And in fact I believe people working with lasers keep a can of aerosol smoke handy for precisely this purpose. —Steve Summit (talk) 15:06, 5 May 2007 (UTC)

Worth noting is that the path of very powerful visible wavelength lasers can be seen, even in clean dry air (see Rayleigh scattering for an explanation of why). Any laser source you're likely to get your hands on as a private individual won't be intense enough to be seen this way, however. TenOfAllTrades(talk) 14:49, 5 May 2007 (UTC)

Once you have powerful lasers, you can detect the beam by many of its "effects on the air" other than just reflection off solid particles. I used to know when I was near the ArF beam by smelling the ozone created due to ionization of O₂ in the air. Not quite the exact positional observation of "seeing" the beam, but still a good warning sign to make sure everyone was wearing UV protection. DMacks 13:44, 7 May 2007 (UTC)

The beam of a relatively low power "laser pointer" of 20 milliwatts is visible in daylight in a relatively clean dry office environment. Rayleigh scattering/filtering is wavelength dependent, and may alter/enhance the perceived "color", but not as I understand it, manifest it.

So, an apparent visible laser beam is the result of geometric reflections from sub-micron dust? 12.175.230.39 16:33, 5 May 2007 (UTC) Greg

Probably much larger than a micron (on the order of tens to hundreds of microns), but yes, dust is a big culprit. -- mattb 20:28, 8 May 2007 (UTC)

Stinging nettle

Is there any plant that displaces the Stinging nettle that I plant amongst them to drive them out? I know they thrive in wet soil (its under my hegde) and aside from cutting them back all the time, drying out the soil (near impossible) or torching them with napalm, driving them out with another kind of plant was the only thing I could think of. Preferably a kind of plant that I would like to have as a replacement! Or if not, any other good methods to torch the annoying things? Thanks SGGH ^speak! 10:44, 5 May 2007 (UTC)

weedkiller? Tomgreeny 14:54, 5 May 2007 (UTC)

I would also employ some serious week killer - but if you prefer something more organic...If you are patient - then pull them up with as much of the root as you can get - turn the soil over with a spade and cover the area with heavy black plastic (several layers of trash bags weighted down with bricks). This cuts off photosynthesis and will kill anything that germinates. Eventually you'll get rid of all of the seed in the soil and you'll be able to replant with something that can out-perform the nettles. Meanwhile - plant some Rumex obtusifolius ("Dock weed") - which is a natural cure for nettle stings. SteveBaker 15:37, 5 May 2007 (UTC)

Will try, thanks. SGGH ^speak! 16:25, 5 May 2007 (UTC)

You could also try dandelions, which poison the soil and stop anything else growing, but really they are worse than nettles. Or there is some japanese plant around that takes over whole areas, killing every other plant around it. If all else fails, very few plants of any sort grow well on concrete.

The nettle has extensive food reserves in its roots. You can get rid of them by cutting them back repeatedly for many years. Estimates vary between cutting them back 3-4 times a year in 2 years, to 3 times a year for 3 years (source: Royal Horticultural Society, via h2g2). --h2g2bob (talk) 20:11, 5 May 2007 (UTC)

That's why I advise pulling them up (with as much of the root intact as possible) - rather than cutting them down (which leaves you with an extremely vigerous root-stock for a tiny new plant to regrow from). Digging the soil afterwards helps because it exposes more of the seeds to the air and to animals to eat and allows the sun to dry out any remaining roots. But a plant can't survive long without photosynthesis - so covering the ground with black plastic for a while will help to prevent anything that does manage to germinate from growing into a vigerous plant. SteveBaker 04:00, 6 May 2007 (UTC)

With Ground-elder growing in my garden, stinging nettle has a hard time. For the few spots where stinging nettle still grows it can easily be cut down. Though ground elder is considered to be a weed, I can't see why. It's edible, it has no thorns and no woody parts that might hurt. If I was a three year old child, a ground-older field (head height for a child) would be paradise. 84.160.229.189 23:14, 5 May 2007 (UTC)

Nettles only grow (or maybe germinate) with relatively high nutrient levels. Maybe grow some greedy "gross feeder" plants like tomatoes etc. Or reduce nutrient levels, tried but failed to re-find article in "new scientist" on using sugar where fertizer has been spilled; microbial activity then supposedly reduces nutrient levels.Polypipe Wrangler 22:18, 7 May 2007 (UTC)

Mid Atlantic Ridge and transatlantic cables

How come all the communications cables laid across the Atlantic don't melt where they go over the mid-Atlantic ridge with all the tectonic/lava-y activity? No, I'm Spartacus 11:51, 5 May 2007 (UTC)

Why would they? Land / ocean surface over mid-Atlantic ridge is not all hot and molten; quite the opposite, vast majority of it is perfectly solid and quite cold. Take a look at Iceland: mid-Atlantic ridge goes right across it, yet Iceland is not split in half by a lava river ;) . Or did you have something else in mind? Dr_Dima

Now, as far as the tectonic activity goes, yes, earthquakes have broken submarine communications cables several times. Also, (somewhat off-topic), sperm whales are known to have tangled themselves in the cables laid on the ocean surface floor, with lamentable consequences for both the whales and the cables involved. Dr_Dima

Undersea earthquakes do break cables. See 2006 Hengchun earthquake, which seriously disrupted the Asian portion of the Internet. I looked at several cable maps at the time: a lot of different cable routes cross that area because it's on the shortest path for quite a few city pairs. That spot is on a subduction zone, not a ridge. -Arch dude 17:01, 6 May 2007 (UTC)

Individual People with full knowledge of a technology and its foundation technologies

I recently asked a similar question and got some very good answers - thank you all so much - and to a large extent I'm very satisfied with the answers I got and the references to look at.
I just have one more sub-question that wasn't answered that I'd like to posit again...

Question:
Are there individuals out there who have the knowledge of how to rebuild a technology from absolute scratch if they were transported with some labourers back to the pre-civilized world. Very much a hypothetical question, but I'm very curious to know if there are people in this world that have the knowledge to, for example, create electricity if they were transported back to say, 9000BC - keeping in mind that at this time there was very little technology in the world altogether - there would be no wire or furnaces or matches or chemicals or nothing. Just bush/jungle/grassland/swamps/oceans/mountains/forests and pre-civilization.
Or, is such knowledge highly unlikely to exist among single individuals?
You could ask the same question about Rocket Science (which comes after electricity I should hope), or nuclear technology, or aviation, etc

Please keep in mind that in this hypothetical question the individual that was transported back in time with his/her labourers would have no manuals or textbooks to rely on, in fact he/she would have absolutely nothing but his knowledge and the clothes on his/her back. Sure, they could invent paper and write the textbooks then if they wanted to, but as a rule to this question these people are expected to already have the knowledge, not just an understanding of textbooks and manuals.
Rfwoolf 13:41, 5 May 2007 (UTC)

I would say, certainly yes. While a written record, and an established technical infrastructure, are both hugely important, they are not absolute essentials: knowledge, once gained, is very difficult to quench. I would guess that a true expert in any field would have enough knowledge to rebuild that field -- if not from scratch, then from lower-level foundations which other experts could be presumed to be able to rebuild. (For example, a semiconductor designer or fabrication expert might not know enough about metallurgy and machining to smelt the iron and fashion the lathe to construct the vacuum pump necessary for semiconductor manufacture, but skilled metallurgists and machinists would.)

See also Renaissance man (a.k.a. Polymath).

It's an interesting question (as speculated earlier by Atlant) what the critical mass might be. The fewer people you have, the odds of having the right set of experts drops to zero. A single hyperpolymath might theoretically have enough smarts to rebuild or reinvent everything, but he wouldn't have enough time after searching for food, and he'd be too likely to be eaten by a bear.

(You set the bar too low, I think, when you ask about merely recreating electricity. That'd be easy; I'm sure I could do it. The only hard part would be finding copper ore and rediscovering how to refine it, because that I don't know off the top of my head.) —Steve Summit (talk) 14:54, 5 May 2007 (UTC)

Just send MacGyver. He could easily reconstruct mining, metallurgy, and electronics to build a powerful laser in a one hour episode, with 17 minutes deducted for commercials. Edison 15:15, 5 May 2007 (UTC)

Yeah - I think it's possible for a reasonably well educated person to 'bootstrap' technology from zero - the problem I think is doing it in one man's lifetime. First basic shelter, then stone knapping to make basic tools, then better shelter, then capture animals, redirect local water sources for irrigation - start up farming, then make charcoal, find clay, then build a really HOT clay furnace with animal-skin bellows to pump air into it - then try smelting various local rocks and see what metals you can make. Then establish standard units of time, mass and length - writing technology (charcoal on animal skins? Maybe start paper manufacturing.) - write down every equation you can remember or derive - start a library. Build up metal smelting, leather production, farming and timber production up to an industrial scale. Start work on tools - edged tools, hammers, adzes and such are no problem. Once you have those, your burgeoning civilisation may need defensive weapons - hopefully not. We need looms, spinning wheels, ploughs, carts and draft animals. Building saws, drills and metalworking tools comes next - a lot would depend on what metal ores you can find locally and smelt. About now you'll want to start a guild system so your population can start to specialise their skills and train youngsters. Pass on skills for sand-mold making and extrusion dies and such so you can fashion more sophisticated shapes from your metals. Now you need some magnets - there are natural rocks ('lodestones') - and you need your people to keep a continual lookout for them by dangling rocks from thin strings and see if they orient themselves north/south. With lodestones, you can magnetise the iron you've smelted - you should have the ability to melt copper into thin bars that you can then draw out into fine wires - from magnets and copper wire, you could make a simple electrical generator - which you could power with a water mill or animal power. Now you have electricity - your generator design will serve as a motor too - so now you have handy portable power - power tools become possible. Battery technology - leyden jars - that's doable too. I think I could manage to achieve all of those steps given a willing and loyal workforce and enough local resources. My chemistry is weak - so batteries and maybe some of the details of the smelting process would require some experimentation - but knowing the underlying principles should make experimentation go fairly quickly. But I think it would simply take too much time to do all of this in one lifetime. SteveBaker 15:26, 5 May 2007 (UTC)

Is it just me, or are some of the points in these answers reminiscent of the Golgafrinchans' attempts to colonise Earth? 80.169.64.22 16:29, 5 May 2007 (UTC)

The real difficulty here, as well as time, is that there are unlikely to be any shortcuts. Almost all modern technology requires most older technology to have been discovered/created first.

I strongly disagree. Do we need astrology in order to get to astronomy? Do we need to work for a while under the assumption (which we'll know to be false) that everything is composed of earth/air/fire and water before we can move on to chemistry? Certainly not. We'll know that bacteria are the cause of disease and to wash our hands often long before we regain the use of antibiotics. In fact, we could probably figure out how to isolate and grow penicillin in a beef broth before we even have farming back up and running! No - we emphatically wouldn't need to repeat the order of events from the past. SteveBaker 20:06, 5 May 2007 (UTC)

I think there are plenty of people that could go back in time and create, to a certain degree, objects of technological value today. I'm sure plenty of us could develop or redevelop techniques based on memory of general ideas, and, we are much more intelligent than they were, even the best of any historical society, I don't think would compare to, for instance some of us at the reference desk who actually have a good enough general knowledge and good enough skills at learning and finding new things (of course in our case, mostly the internet and books are used, but the same still applies I believe), that we would most definitely equal or beat them. A good swiss timekeeper might be stretching it. Two more notes: I asked a question in the past here about the possibility of building a piano from scratch. This morning I thought of how the "good swiss timekeeper" was made when I was watching a tv show about making watches. Evolution. It didn't just appear. One person didn't just invent the watch. It took hundreds of years and very tiny steps to eventually get to the mechanical or digital watch you may be wearing right now. Mechanical timekeepers were most needed as chronographers on ships, I believe. Pendulums don't work so well on the high seas. [Mac Δαvιs] ❖ 23:17, 5 May 2007 (UTC)

We have the Scientific_method. Doesn't that give us a big jump over all scientist/inventors up to the Renaissance. —The preceding unsigned comment was added by 136.224.90.29 (talk) 04:07, 7 May 2007 (UTC).

Regarding technology

Q. Why paper make noise on tearing ? —The preceding unsigned comment was added by 221.135.246.75 (talk) 15:30, 5 May 2007 (UTC).

As each of the microscopic strands of wood pulp breaks, the energy that's released will cause it to vibrate. That vibration disturbs the air nearby and the resulting air vibrations spread outwards like ripples on a pond - those a 'sound waves'. SteveBaker 15:39, 5 May 2007 (UTC)

Ferroxyl indicator

Do we not have an article on ferroxyl indicator? 81.132.215.242 15:37, 5 May 2007 (UTC)

I don't think we do - there is mention of it's ingredients and function here, where it says: Potassium ferricyanide is also one of two compounds present in ferroxyl indicator solution (along with phenolphthalein) which turns blue (Prussian blue) in the presence of Fe³⁺ ions, and which can therefore be used to detect rust. It is possible to calculate the number of moles of Fe³⁺ ions by using a colorimeter, because the very intense color of Prussian blue Fe₄[Fe(CN)₆]₃. SteveBaker 15:47, 5 May 2007 (UTC)

Do you know anything about ferroxyl indicator: why not add a page on it? --h2g2bob (talk) 20:00, 5 May 2007 (UTC)

Matter waves of photons?

I couldn't find it anywhere explicitly, but are the wave equations for light the very same thing as the matter waves (de Broglie waves) for a photon? —The preceding unsigned comment was added by 87.67.1.240 (talk) 16:28, 5 May 2007 (UTC).

Photons are light (light is made of photons). The de Broglie hypothesis still holds for photons. See also wave-particle duality. --h2g2bob (talk) 19:56, 5 May 2007 (UTC)

The how many-eth cousin is a chimpanzee

Chimpanzees are my great-great-great-... ...great-Grandfather's great-... ...great-Grandson so that makes us cousins like first cousin and second cousin, so what number would a chimpanzee be, and while we're at it, how about the number of a lobster and an oak tree. I think chimpanzees split 30 million years ago so it seems to be something along the lines of 1.5 millionth cousin(30 million divided by 20 years) but I'm not sure because I doubt that the average age of having a child over the 30 million years of separation humanity and chimpanzees is really 20 years because a chimpanzee has kids when it's younger, I think at an age of 6 or something, and I don't know about the lobster and oak tree. Thanks, Jeffrey.Kleykamp 18:09, 5 May 2007 (UTC)

You should read Richard Dawkins' book "The Ancestors Tale" - which shows all of the branching points for humanity going back in history - with approximate years (and numbers of generations where that information can be figured out). He says that Neanderthals and modern humans split 500,000 years ago. Chimps and humans split 6 million years ago - and he suggests 250,000 generations. Flipping throught the book at random, I'm seeing Gorillas at 7 million years ago (mya), other monkeys split off arouynf 40 mya, Amphibians 340 mya, FIsh 417 mya, but before that - we don't have any kind of reliable dating - our last common ancestor with the lobster was probably around 600mya - but that's uncertain. We don't know when we split with the oak tree - it's gotta be a billion years. SteveBaker 19:58, 5 May 2007 (UTC)

planning a family reunion? 59.180.41.78 20:19, 5 May 2007 (UTC)

W'all- I'll be a monkey's uncle! Edison 06:30, 6 May 2007 (UTC)

I figured out that we are chimpanzees 333,333th cousin 666,667 times removed, all you do is take the years when we separated (6 million) and divide that by the average years per generation (I picked 18) to get the number for the cousin-ship and then take the the years that we separated and divide that by the average years per generation (I picked 6) and subtract the number for the cousin-ship from it to get the times removed, does that seems correct?

The problem is that the "average years per generation" number is horribly variable - it's increased dramatically during the last 50 years. The article Generation says an average of 22 years is generally accepted. Also, there is no symmetry in the generational span between humans and chimps. Because Common Chimpanzees are sexually mature at age about 8 years - their generational span might average out at half that of humans - we would expect twice as many generations of chimps to have passed than generations of humans since our last common ancestor. But at the point of separation of the two species, our generational spans must have been identical - so the variation in generational spans over time is another big unknown. I don't think we can say how many generations have passed us by in any meaningful manner. SteveBaker 14:51, 6 May 2007 (UTC)

Steve, you abject pessimist, whaddayou mean it "can't be done"? The previous poster not only got a mathematically sound answer, he got it to six significant digits. You can't argue with that kind of math! —Steve Summit (talk) 15:14, 6 May 2007 (UTC)

The anon poster wins the "2007 Archbishop Ussher Award" for creative use of mathematics in the eternal quest for the truth. :) JackofOz 03:00, 7 May 2007 (UTC)

I posted the calculation and I can prove it, see [[5]], so send me my prize! ;P Jeffrey.Kleykamp 10:21, 7 May 2007 (UTC)

For your lifelong services to to the cause of excessive precision - your ceremonial golden decimal-point is on it's way to you! Of course being a mathematics award, it is a mathematical point.  :-) SteveBaker 23:52, 7 May 2007 (UTC)

non mendelian inheritance in arabidopsis thaliana

Hi folks. I was hoping you could help me with a question.

From "arabidopsis thaliana"

"Lolle and Pruitt agree that Peng et al.'s did observe cross-pollination but note that some of their own data, such as double reversions of both mutant genes to the regular form...."

I know what Peng's study said, basically they had bad design or something. I guess my question is what the h bomb is double reversion. —The preceding unsigned comment was added by 139.225.242.164 (talk) 18:34, 5 May 2007 (UTC).

Gene reversions occur when a mutant allele reverts to a wildtype allele. If the reversion occurs in a somatic cell, it will usually result in mosaicism. The mechanisms for reversion are numerous and not always fully understood. Examples involve Retrotransposons or unequal sister chromatid exchange. A double reversion would be when two genes revert to wildtype in the same organism. Rockpocket 20:52, 5 May 2007 (UTC)

I appreciate your time and effort. 139.225.242.164 21:04, 5 May 2007 (UTC) cyanide_sunshine

Skin Infection Rates

Where might I find data regarding skin maceration while wearing an orthopedic cast? RDunagan 19:56, 5 May 2007 (UTC)

Taking of Wallpaper

This is a duplicate question. Please provide answers at the question's first appearance on the Miscellaneous Desk.

I know this isn't really a scientifc question, but since this surely involves chemicals of some kind, does a chemist( or anyone) have any suggestions on how to remove wallpaper? I've heard of products like DIF, and home made mixtures of fabric softener with hot water, but do they work well? If not, what could I use? Thanks! Beeaz193 21:16, 5 May 2007 (UTC)

On HGTV they always use Downy fabric softener on wallpaper. Try checking the website of Sell This House, or a good search and it can tell you what exactly to do. I think they just brush it on and then wait. [Mac Δαvιs] ❖ 23:10, 5 May 2007 (UTC)

Find a local tool rental shop and rent one of those steam-based wallpaper strippers - they work like magic and don't fill your room with nasty chemicals. It's worth the cost just in saved effort. Check out the final section of our Wallpaper article. SteveBaker 01:08, 6 May 2007 (UTC)

Burning Calories

Since a (kilogram) calorie is the energy needed to increase the temperature of 1 kg of water by 1 °C, shouldn't one be able to burn calories simply by immersing themselves in a pool of cool water for an hour or so, and letting body heat warm the water? The Userboxer^Complain/_ubx 21:27, 5 May 2007 (UTC)

Yes, but it wouldn't be very efficient, because most of what heated the water would be the heat we give off as a matter of course. For comparison, one of the reasons why arctic explorers and mountaineers have such high caloric requirements (8000 calories a day IIRC), is to keep warm. Anchoress 21:44, 5 May 2007 (UTC)

Disagree although its going to take much longer than 1 hr. Since the Artic explorers do indeed need at least 8000 cal per day, if follows that if you are not consuming as many calories than it takes to keep you warm, you will lose weight. I believe some of the artic explorers lost about 14 llb per mo even though they were taking 8kcal per day. —The preceding unsigned comment was added by 88.110.17.225 (talk) 22:20, 5 May 2007 (UTC).

Disagree with the part about losing heat anyway. Cold water strips heat away from your body (and thus makes you burn more calories) much faster than cold air. Infact, 30C water (typical indoor swimming pool) feels colder than 22C air (room temperature or the temp of the air in the pool area) because it strips heat away from your body at a higher rate. And by the way, it sounds like you figure it's an "easy" way to lose the calories... but the fact is you will need more than an hour a day to see a difference and it would probably be more agonizing than doing something physical instead. Or maybe you should try a combination of both (ie do aqua aerobics in a colder pool).  Adam2288  T  C  04:04, 7 May 2007 (UTC)

May 6

Uses of propynol

I live on rain water and had a water tampering and found high levels of sulfer and iron and also propynol at 20-30ppm in a 1lt jar, the water was acidic at 4.1. My question is does sulfrik acid contain propynol or what everyday things in our home would contain it? The police are of no use out here in the country and queensland health could only tell me thier findings, I suspect that sulfrik acid or concrett lime was placed inside the tank but I am having trouble finding full list of poisions in the product list. regards Kenpeds 03:41, 6 May 2007 (UTC)

From here;

"Propargyl alcohol has several major use areas. They include: reactant/chemical intermediate; pharmaceutical intermediate; agricultural chemical intermediate; corrosion inhibitor; solvent stabilizer; and polymer modifier (ACGIH, 1992; Kuney, 1994; Lewis, 1993; STN International, 1995b). Some examples of these uses and some specialty or potential new uses are presented in Table 2. In addition to the above uses, ACGIH (1993) and Lewis (1993) list "soil fumigant" as a use for propargyl alcohol. However, further literature and database searching failed to substantiate this use; and, responding to a request for information, Dr. Bill Burnham of EPA's Office of Pesticide Programs (OPP) reported that he was unable to locate any record of this chemical being used as a fumigant (Burnham, 1995)."

Propargyl alcohol is a synonym for propynol. There's a bit of a list of more synonyms here. Aaadddaaammm 04:57, 6 May 2007 (UTC)

This sounds rather serious, like somebody is trying to kill you. I'd set up cameras and motion detector lights to catch anyone who attempts to poison you again. StuRat 07:54, 6 May 2007 (UTC)

If someone is actually trying to kill you, don't play amateur detective. Seek professional assistance; see my comment below. TenOfAllTrades(talk) 18:21, 6 May 2007 (UTC)

I have all the set up camers and lights ect ect now and I know who the person was but proving it is different, I looked up the info you sent but has anyone got the making of what the propynol would have come in? I was thinking sulfurik acid becorse of the smell and fumes being a steem like vaper coming out of the tank. the tank was full 25,000 ltrs which run the whole house and the propynol was 20 to 30 ppm in a 1 ltr sample, so I am trying to work out how much was used and how long was I drinking and washing in it before the chem reaction happend? my 21 month old girl was very sick and my wife who just had surgery was also sick with bleeding internal. I am just concerned for the long time health my little girl. Kenpeds 08:43, 6 May 2007 (UTC)

Is there any possibility this could be acid rain ? That would be the case if you sometimes get rain falling through gases in the air released by industrial areas in major cities. StuRat 17:56, 6 May 2007 (UTC)

No. Acid rain does not contain propynol, and a pH of 4.1 is quite a bit too low for rain in rural Queensland. TenOfAllTrades(talk) 18:21, 6 May 2007 (UTC)

If you believe that you have been poisoned (deliberately or accidentally), your best bet is to see your physician (and your daughter's pediatrician). Be sure to bring a copy of the water testing report and the MSDS: link. Propynol is a common ingredient in corrosion inhibitors; it is widely used in industry. (Is it possible that there was some sort of accidental backflushing of a heating or cooling system liquid loop into your water? Such systems often contain corrosion inhibitors and various other nasty chemicals.)

For your reference, a single bottle containing 500 mL to 750 mL (a pint to a pint and a half) of propynol would be sufficient to produce a concentration of 20 to 30 ppm when uniformly mixed into 25 000 liters of water. It is not going to be an ingredient in sulfuric acid; the two chemicals are incompatible.

If you have reason to suspect that the contamination was deliberate, go to the police. Be prepared with the water testing report, MSDS for propynol, any medical reports on health problems you believe (or your physician believes) are related to possible propynol exposure, and a description of your water system's design. Your physician may also – with your permission – be willing to speak directly to the police. If you feel that the local police are not providing sufficient assistance, the Queensland Police Service website provides contact information for police headquarters as well as instructions for registering complaints.

While the suggestion above to include security lighting is not a bad idea from a general security standpoint, please don't assume that it's your responsibility to play Remington Steele and do all the investigation yourself. Your health is too important to leave to amateur detective work, and I am aghast that someone would suggest you deal with all this on your own. TenOfAllTrades(talk) 18:21, 6 May 2007 (UTC)

But before getting all worked up and starting a legal case, please first consider StuRat's idea about acid rain for one more moment. The few measurements of rain pH in rural tropical Australia have shown an average pH of 4.5, similar to Sydney levels, largely from natural vegetation sources of acidity [6]. A few values as low as 3.5 have been measured. The rain pH is highly seasonally dependent in tropical Australia, with the lowest pH values occurring in November at the beginning of the wet season. Thus a pH of 4.1 isn't extraordinary. Where in Queensland are you located, and when did you collect the water? Are you in the tropical region? Are you near or downwind from any human acidity source, such as the Mt. Isa smelter or some local power plant? As for the Propynol, note its use as a polymer modifier. Do you by any chance use a plastic tank? Or do you pipe the water through plastic tubing? If so, you might consider whether the propynol could have simply leached out of the plastic. Modifiers such as plasticizers are notorious for leaching or outgassing from plastics. The water presumably spends a lot of time sitting around in the tank and tubing. As for health effects of propynol, the US Environmental Protection Agency, based on very limited data, suggests a reference dose (a concentration estimated to yield "negligible" risk of health effects over a lifetime of exposure) of 2 micrograms per kg of body weight. That would correspond to only a few grams daily intake of your tank water. So you may want to fix the problem, if the concentration is reproducible. Before freaking out too much, however, note that the EPA reference value was based on an "uncertainty factor" (a factor they lower the reference value by when they don't have clear toxicity data, in the spirit of "better safe than sorry") of 8000. --mglg_(talk) 19:31, 6 May 2007 (UTC)

Hi all, no the tank is steel and qld health advised me that the leavals they found was to high to be in acid rain, I have found that Hydrochloric acid uses Propynol as a solvent and that might explain my eyes burning and blisters, also the rooten egg smell and viper like a steem coming from the tank??? as far as I can work out we where exposed for probely 3-4 days before I noticed the vipper from the tank. I live outside of Kilcoy 1hr from brisy and no factery or industral sights near us. The water was all 100% rain collected and the tank overfloed the day I found the affects. We are waiting on QLD police complaints to get back to us (public holiday today) as for my lighting and security camers all I can prove with them is what I capture at that time and it might only be simple tresspassing. At less I have gotten more ideas and info in the last 24hrs of this sight then all my questions and surching over the last 6 weeks on others. also everyone in my area are on tank water and no other complints or pollution have been reported. a house 2 doors down had a falling out with this man 3 years ago and the next day he found a white substance in his gutters testing was done on his water and the powder but nill to report as not anougth was found (same police still) and to him it is all just a pain in the ass. again thank you all for your help and ideas and keep them coming as the more info I have the more situations I can discount Kenpeds 21:57, 6 May 2007 (UTC)

Brainstorming specific examples for biology themes

Hi,

I'm trying to create a list of specific examples for the following themes in biology. I've got a couple of examples, it would be great if you could add to the list. Alex Ng 04:28, 6 May 2007 (UTC)

Energy Transfer Concept that energy flows from the sun into plants and into animals that eat them. Could look at energy currency in the cell (ATP)

Continuity and Change/Evolution

Relationship between Structure to Function

(Polymers) Cellulose: Beta-linking of glucose monomers results in firmness in plants

(Different organs/parts of organs and their functions)

Neuron:	Narrow shape (high SA/V ratio allows for quick change in Na/K ion concentration.
Node of Ranvier	increases speed of impulse transmission
Na/K Pump	maintains resting potential/restores resting potential
Villi:
Smaller microvilli	increases surface area for reabsorption
Single cell epithelial	faciliates reabsorption of nutrients
Alveoli	Massive, branching surface area allows for rapid oxygen uptake, carbon dioxide dumping.
Single cell epithelial	faciliates diffusion of oxygen and carbon dioxide
Moist membrane	faciliates diffusion of gases

PROTEINS. The structure of proteins dictates their function. Their 3D (tertiary) structure is dictated by their primary structure (amino acid sequence) which is dictated by the gene.

You could look at gross anatomy stuff, like um... long legs -> running, egg shell shape -> can't break it, gills -> breath underwarter, structure of the skin keeps stuff out (and in!)...

I would actually phrase it - lungs ->breath above water, since, you know, it's newer ;-) I'm not even gonna make a guess on where insect breathing apparatus fits in, though :-/ Someguy1221 05:26, 6 May 2007 (UTC)

Regulation/Homeostasis:

Blood glucose concentration (insulin lowers blood glucose levels by storing glucose as glycogen, glucagon increases blood glucose levels by doing the opposite) Maintaining proton gradient in mitochondria to keep ATPase making ATP. Glutathione reductase keeps glutathione reduced which keeps the right proteins disulfide-linked.

Interdependence in Nature

Examples of Relationships in Nature:

Relationship	Example
Neutralism (no affect on both)	A lizard resting on a tree root, neither ones really gives a damn.
Amensalism (one is negatively affected)	Bread mold Penicillium secrete penicillin that kills bacteria
Commensalism (one is positively affected)	Can't recall the general name, but plants that live on the bark of trees. The former gets a place to live, the latter is unaffected so long as the former isn't eating it.
Synnecrosis (both negatively affected)	One animal eating some other, poisonous animal.
Mutualism (both positively affected)	Cellulose digesting bacteria in cows steal food from the cow but help them digest grass.
Predation/Parasitism (one positive, one negative)	ANY PARASITE, but i like tapeworms

Re: Today's Feature Picture

"evidence of large bodies of liquid methane on Titan"

....according to the images taken by the Cassini orbiter.

My questions are:

1. Has methane been scientifically and absolutely identified?
2. What could be the source of such substance in a place like Titan?
3. Whence the carbon atom in methane????????????????
4. Has wave activity been recorded on the surface of the "75 large bodies of liquid" ??
5. What is NASA's "definitive evidence opf lakes fillled with methane" on Titan??

Thank you,

(email removed to prevent spam)

(Note: Question reformated to be easier to read, but words were not altered in any way by Sifaka ^talk)

3) Carbon is common on small bodies throughout the solar system. It also exists on larger bodies (Jupiter, Saturn, Uranus, Neptune, and the Sun), but is rare compared with the huge volumes of hydrogen and helium such bodies retain due to their higher gravitational attraction. StuRat 07:43, 6 May 2007 (UTC)

Our sub-article: Titan (moon)#Liquids on Titan says scientists have "definitive evidence of lakes filled with methane on Saturn's moon Titan" and provides this source. Rockpocket 07:50, 6 May 2007 (UTC)

As for (1), you can confirm what element something is just by looking at it - see emission spectrum / absorption spectrum. --h2g2bob (talk) 08:37, 6 May 2007 (UTC)

Exactly, there were a number of elements that were discovered this way, such as helium whose emission spectra was first identified in the Sun, hence the name. And if I'm not mistaken, this was prior to its discovery on Earth--VectorPotential^Talk 18:00, 6 May 2007 (UTC)

Watts

Hi, I'm trying to work out how many watts a household device is, but dont have any specialist tools. I baselined the current house load by timing the electricity meter outside, then turned on the device and measured again.

The meter wheel measures in kwh (kilowatt-hour) where 266.6 turns = 1kwh

The initial baseline measurement was 43.3 seconds for a single turn.

After the device was turned on, it changed to 25.97 seconds for a single turn.

I'm figuring I should be able to do some math to figure out the wattage, but dont seem to be able to. Please help. E!

Let's see:

43.3 secs for a turn means 3600/43.3 or 83 turns per hour. That's 83/266.6 or 0.312 kw or 312 watts.

26 secs for a turn means 3600/26 or 138 turns per hour. That's 138/266.6 or 0.520 kw or 520 watts.

So, I get 208 watts. Anyone care to check my math ? StuRat 07:36, 6 May 2007 (UTC)

Much appreciated StuRat, the math looks good. I guess I just realised that a watt-hour and a watt are the same thing!! E!

They're not quite the same thing. If you leave a 100 watt light bulb on for an hour, that is 100 watt hours. If you leave the 100 watt light bulb on for a half hour, that is 50 watt hours. StuRat 08:23, 6 May 2007 (UTC)

1 watt-hour is equivalent to 3,600 joules. This is because 1 Watt is 1 joule per second. It already has time built in. Watt x Time = Energy (joules). So Kwh is just a measure of energy used. So, I dont think the math is right. Let's see if I can figure out what I mean.

43.3 secs for a turn means 3600 secs/43.3 secs per turn = 83 turns per hour. That's 83 turns per hour/266.6 turns per KWH or 0.312 kw-hours per hour. Ah, so the hours cancel and you are left with just kilowatts. So, the above math seems to be right. Mrdeath5493 14:07, 6 May 2007 (UTC)

Just to be thorough, this method of measurement seems very susceptible to error, but it looks to be the best you can do for now. Mrdeath5493 14:12, 6 May 2007 (UTC)

If you are going to do those kinds of tests, I'd make sure to unplug your refrigerator, freezer and turn off any electrical heating or air-conditioner (don't forget water heaters) for the duration of the test. Those things are on thermostats and may turn on and off at random during your experiment. Since they are all high wattage devices, that would drastically mess up your readings. But User:StuRats math seems solid to me. SteveBaker 14:20, 6 May 2007 (UTC)

I got some complexes in dealing with complex ions

Up to 5 minutes ago I used to believe that precipitates where covalent substances and now I discovered that there're neutral complex ions. I wanted to ask you how can you distinguish between neutral complex ions and covalent substances? Also in atmospheric oxidation eg Fe(OH)2 ---> Fe(OH)3 is it right to say that the oxidation was followed by a ligand substitution?

Oh also anybody know why negative mercury complex ions aren't called hydragates?Bastard Soap 15:20, 6 May 2007 (UTC)

Paper hydrolysis??

What happends to the bonds in a piece of paper when it is soaked in water?Bastard Soap 16:13, 6 May 2007 (UTC)

It's the same as the process of dissociation of salts and sugars in water. Water is capable of bonding to the components of the paper, and thus it is no longer so energetically stable for the paper to remain bound to itself. Someguy1221 17:32, 6 May 2007 (UTC)

So it's just partially dissolved? But I would imagine that some water molecules would get in between the structure of the paper as well, correct?Bastard Soap 18:19, 6 May 2007 (UTC)

False color satellite imaging

Why do most if not all photos taken by a satellite or any other unmanned vehicle in space are in false color? Why can't they send a true-color camera to take pictures? Examples being pictures of Mars and such. Never understood that. —The preceding unsigned comment was added by 99.244.236.45 (talk) 16:13, 6 May 2007 (UTC).

Many spacecraft do have "true-color" capability. However, they also captyre wavelengths beyond the spectrum visible to humans in hte near-infrared and ultraviolet wavelengths.To allow humans to guage certain realationships a scientist will map the recorded spectrum onto the visible spectrum.For instance: you cannot see the different temperatures of seawater, but hte infrared camera can detect the difference. We then map hotterto red and cooler to blue to show the differences.

The other reason to map colors is for aesthetics: a great many objects in the solar system are visually very boring, subtle shades of gray (for asteroids and the Moon) or brown (for Mars.) By remapping the colors, we can more easily see the subtle distinctions. -Arch dude 16:34, 6 May 2007 (UTC)

Additionally if you are taking pictures through a heavy atmosphere (i.e. Venus) then visual wavelength isn't useful at all. And there are plenty of true color pictures of Mars as well — Google Image search "mars surface" and you'll see a lot of them. --24.147.86.187 17:01, 6 May 2007 (UTC)

For most purposes, you need multispectral images in order to extract the maximum amount of information from the data. They often take photos at a range of different wavelengths - some visual some not. Most of the time the interesting data is available all across the spectrum - and if you are looking outside of the human visual range then you can pull more information out of the images using false color. But on some missions with a particular scientific goal the additional weight and power requirements for a visual spectrum camera may not be justified. Depends on what you are trying to find. SteveBaker 17:47, 6 May 2007 (UTC)

It would be very weird to *not* use imaging outside the human visual spectrum, since that's a totally arbitrary slice of the EM spectrum that happens to have evolved here on Earth where it's useful due to us being diurnal air-dwellers under a UV-blocking atmosphere. There's nothing special or more "natural" about 400 to 700 nm wavelengths. --TotoBaggins 18:32, 6 May 2007 (UTC)

There actually is. Earth's atmosphere is particuarly transparent in the 400-800 nm range. See Optical window for details. Out in space you are of course not bound by such contraints. Dr Zak 18:37, 6 May 2007 (UTC)

Yes, that's what I meant: we didn't evolve to use UV since it's so well blocked, and we didn't evolve to use infrared because we're diurnal, so it's just an accident of fate that the 400-700 nm range is "natural color" to us. --TotoBaggins 20:13, 6 May 2007 (UTC)

Earth's Spin

The previous question started me thinking. If you theoretically attached a giant rocket booster on the earth's crust to counter rotation (imagine that the booster wouldn't just break away with a piece of crust into space) and you blew up the moon to avoid it's annoying tides, the earth would never star spinning again?Bastard Soap 16:26, 6 May 2007 (UTC)

Well, one assumes that stopping the mantle from rotating wouldn't stop the vast liquid iron core from continuing to rotate. So when you turned off the motors, the friction between core and underside of mantle would gradually bring everything back spinning again. But I guess if you left the motors firing - adjusting the thrust to keep the earth from spinning, you'd eventually stop the core from spinning too. At that point, the earth would not start spinning again. SteveBaker 17:42, 6 May 2007 (UTC)

Being hit by a giant meteor might start the Earth spinning very slowly. StuRat 17:47, 6 May 2007 (UTC)

Many satellites are tidally locked to their gravitational big-neighbor the way the Moon is to the Earth. In the absence of spinning, perhaps the Earth would be lock onto the Sun, which would set it spinning at 1 revolution per year. --TotoBaggins 18:41, 6 May 2007 (UTC)

Also, that's going to take a *lot* of rocket fuel to stop the Earth from spinning. Maybe a mass-driver made with a supergun would be more environmentally sound? --TotoBaggins 18:45, 6 May 2007 (UTC)

A supergun uses fuel to propell a bullet which would impose a reaction of the earth, I'm not sure but I think in using rocket fuel you would have less losses of forcesBastard Soap 20:51, 6 May 2007 (UTC)

ahh heres a quick little experiment you can try for this. grab a regular egg spin it and then place your finger on the middle *gently* to stop the egg. release the egg and it will start spinning slowly again! its pretty awsome try it. User:Maverick423 Im in ur science steeling ur gravity 00:55, 7 May 2007 (UTC)

Apnea

Are there any exercises which are specific to increase lung capacity and general respiratory pigment content in the body?Bastard Soap 16:30, 6 May 2007 (UTC)

Exercising at altitude will result in increased haemoglobin concentration in the blood. See Altitude sickness#Altitude acclimatisation for details of physiological adaptions (healthy and otherwise). David Ruben ^Talk 16:53, 6 May 2007 (UTC)

If a person has sleep apnea and is obese, then any exercise which helps them lose weight is likely to help. StuRat 17:45, 6 May 2007 (UTC)

Thanks but I was interested in particular exercises done at normal altitude which would have a particularly pronounced effect on lung capacity and respiratory pigment. I already knew about altitude aclimitasation and had thought about buying a hypoxic air generator but it's way too costly for a poor assed student such as me'self.Bastard Soap 17:55, 6 May 2007 (UTC)

42.2

I'm sure that the number 42.2 is important in atomic physics somehow, I just can't think where. Can anyone help me out? 128.243.220.42 19:37, 6 May 2007 (UTC) (User:Ollie)

I suspect 42.2 is just a pretentious version of 42, which is the most important number to the life, the universe, and everything. alteripse 19:55, 6 May 2007 (UTC)

Nah, this is proper physics I'm talking about ;) 128.243.220.42 19:57, 6 May 2007 (UTC)

42 (number), and [7] ? -- Consumed Crustacean (talk) 21:30, 6 May 2007 (UTC)

Could be one of the atomic weights of something? --h2g2bob (talk) 22:46, 6 May 2007 (UTC)

No, none of the above. I've now got home and had chance to look through my books and lecture notes, and I think I am making things up. All I can think is that I was getting mixed up with 54.4, the second ionisation energy of helium. Anyhow, many thanks for your suggestions. →Ollie (talk • contribs) 22:54, 6 May 2007 (UTC)

Flower Identification

Can this flower be identified? J Are you green? 20:09, 6 May 2007 (UTC)

It looks like Foxglove.199.126.28.71 22:01, 6 May 2007 (UTC)

Sorry, 199.126, it is not foxglove. --mglg_(talk) 00:43, 7 May 2007 (UTC)

Dimensions

How come objects exist only in the 3rd dimension, and not anything higher? A response on my talk page or to let me know thus would be greatly apprieciated, thank you.199.126.28.71 21:54, 6 May 2007 (UTC)

Well, for a start, they don't, because there are at least four dimensions to space-time (although under general relativity you can't really say that there are three dimensions of space and one of time, although you can usually treat three of them as "spacelike" and one as "timelike"). Secondly, string theory generally suggests that there are at least six more, but they're curled up tightly so we don't notice them. (To visualise this, imagine you lived on a cylinder of infinite height but finite radius, so your world has two dimensions - along the height dimension and around the circumference. Now shrink the radius to something incredibly small, so it seems as though there is only one dimension left, although there may still be enough indirect evidence for you to discover the second dimension.) So it's not that objects only exist in four dimensions, but that we can only perceive four (and our perception of time is quite different to our perception of space). Recommended reading: Flatland: A Romance of Many Dimensions. Confusing Manifestation 22:54, 6 May 2007 (UTC)

(edit conflict)

That is just an observational fact: the world we see appears to have 3 spatial dimensions. There is no (known) fundamental reason for the number 3. In fact, according to some physical theories there are fundamental reasons for the number of spatial dimensions to be much larger, maybe 10 or 11. These theories sweep the extra dimensions under the rug (make them undetectable) through a trick called compactification. --mglg_(talk) 22:58, 6 May 2007 (UTC)

I thank you for trying to explain, but your explaination is confusing.199.126.28.71 23:55, 6 May 2007 (UTC)

We live in a three dimensional paradigm, nothing more. It doesn't make it real or true, it's just the best way we have found to explain it at the moment. Just like when we thought the world was flat, until someone found enough evidence to support a new model and contradict the current one. Fortunately if you see problems with the current three dimensional model at least you can discuss your ideas without the fear of being burned at the stake. Vespine 00:00, 7 May 2007 (UTC)

hudrochloric acid

if hydrochloric acid is added to a ph level of 6.5-7.0 water what would be the outcome?

propynol is used as a solvent for hydrochloric acid and my guess would be that the acid would quickly brack down in water leaving traces of propynol?? would it also rise the iron and sulfer leavels of the water?? regards Kenpeds 22:58, 6 May 2007 (UTC)

Umm .. hydrochloric acid is a solution of hydrogen chloride in water. If you add it to water you get a different concentration of hydrochloric acid. That's all.

You could get propynol if you started out with some. There's nothing about water and HCL which is going to synthesise it. --ColinFine 23:26, 6 May 2007 (UTC)