Wikipedia:Reference desk/Archives/Science/2012 April 23

= April 23 =

Chemistry/Amylose and amylopectin Determination.
How can i determined amylose and amlopectine in starch sample. — Preceding unsigned comment added by 78.138.24.1 (talk) 10:19, 23 April 2012 (UTC)
 * Do your own homework. Whoop whoop pull up Bitching Betty 10:23, 23 April 2012 (UTC)
 * The basic schoolchild test for amylose starch is given in the Wikipedia article. A test specific to amylopectin is trickier, and I haven't studied Chemistry for more years than I care to remember, so I'll leave it for someone else to comment of the appropriateness of formamide.  Are you wanting to determine the relative proportions of the starches?    D b f i r s   07:16, 24 April 2012 (UTC)

Kills 99 per cent of germs...
That's the claim of household bleaches and surface cleansers etc - but are they doing the same thing that antibiotics are doing? What of the one per cent of germs that survive? Are we breeding supergerms? Bleach-resistant e-coli? Chlorine-tolerant salmonella bacteria?

Ta

Adambrowne666 (talk) 11:34, 23 April 2012 (UTC) There is a major difference between antibiotics and bleach: the 1st is a bacteria-only poison, working by a very specific damage it deals to the bacteria protein making process. Without protein making on the run no living cell can, well, stay a living cell. It dies and eventually decompose or is eaten by a still-living cells. Bleach is a different thing altogether: it is a highly reactive compound. It reacts with the cell membrane, dissolving it. It reacts with many, many molecules inside the shattered cell, destroying anything and everything. It consumes the cell and it contents. From this it is clear that, unlike antibiotics, bleach is poison for every living cell, not just bacteria. Since bacteria does not live in a protective layer of dead skin as we do, contact with fairly low concentrations of bleach for several dozen minutes kills it. 109.65.9.22 (talk) 13:10, 23 April 2012 (UTC)


 * Bleach works in part by a specific mechanism, which is opposed by Hsp33 and EF-Tu.   Now it's loss of Hsp33 that makes a strain of cholera bacteria extra sensitive to bleach.  I have not seen anything in NCBI about evolution of more bleach resistant bacteria, and it is possible that this is much harder because toxicity affects many different things, all of which would have to simultaneously evolve to overcome the problem.  Nonetheless, until proven otherwise, my guess is that such bacteria can, will, and probably have evolved to develop greater bleach resistance, and that this adversely affects people when their own cells' attacks with oxidizing agents are better rebuffed. Wnt (talk) 13:59, 23 April 2012 (UTC)


 * I suspect the 99% business is a truth-in-advertising CYA to avoid charges of unreasonable claims, but bleach kills pretty much 100% of germs unless they're somehow shielded from contact with the bleach. Scratches in a surface, for instance, coverage by some other substance - grease, for instance, etc. would be a shield - and which could be seen to negate a 100% claim. The building contaminated by Reston virus was decontaminated (initially, anyway) by bleach heated in electric skillets.  Acroterion   (talk)   20:29, 23 April 2012 (UTC)

Quantum entanglement and kinetic energy
Let's say you have two particles that are entangled. If you impart kinetic energy to one particle, will kinetic energy be imparted to the other particle? ScienceApe (talk) 16:55, 23 April 2012 (UTC)
 * No. When you change the particle by adding energy (using some unspecified mechanism), its quantum mechanical energy state is no longer identical to its previous state, and therefore no longer identical to its pair partner.  Rather, its state is "not necessarily identical," because even if you specify how you modify the energy, we don't know what you did to the quantum mechanical energy state until you measure it again, ad infinitum.  Quantum mechanical entanglement sure becomes a lot less interesting, (insofar as it has no useful practical consequences), when it is treated correctly!  Nimur (talk) 17:44, 23 April 2012 (UTC)

Female scientist question
Looking for the name of a Female scientist, who was a pioneer nd gave and lost life to science. She was homeless in early childhood. She grew up in a European city.

I thought Marie curie but looks like some other fits the description. Any help will be appreciated. I searched google/wikipedia with no luck. — Preceding unsigned comment added by 183.83.244.183 (talk) 17:08, 23 April 2012 (UTC)


 * I doubt that you meant Hypatia but I will mention her because she deserves more publicity. What field was this scientist a pioneer in?  Spinning  Spark  19:25, 23 April 2012 (UTC)


 * You might have fun with List of female scientists before the 21st century. {The poster formerly known as 87.81.230.195} 90.197.66.239 (talk) 00:07, 24 April 2012 (UTC)

Population growth vs accelerating returns in technology
From Accelerating change:


 * For example, it can be claimed that inventions are generally created by a fixed population of human inventors at a constant rate, regardless of their current technological prowess, and therefore technological "progress" is actually a function of population growth, not past inventions.

Have any studies attempted to assess the accuracy of this claim, i.e. to determine whether historical statistics still support the Law of Accelerating Returns once adjusted for the (possibly superlinear, and possibly time-lagged) effect of an increased population? Neon Merlin  17:21, 23 April 2012 (UTC)


 * My reading of the article is that that is not a claim, but a dialectical argument against accelerating change. Personally, I very much doubt that there is evidence to back it.  It just does not stack up when comparing, say, the Golden Age of Greece against the stagnation of medieval Europe.  Population size will clearly come into this equation, but equally, if not more, important are good communications, a social system allowing freedom to express ideas, and a society wealthy enough to allow individuals to pursue those ideas.  Spinning  Spark  19:16, 23 April 2012 (UTC)


 * The problem with anything like this is deciding on a metric to measure the rate of invention with. I'm sure you could find plausible metrics to both prove and disprove that claim. --Tango (talk) 21:54, 23 April 2012 (UTC)


 * That is exactly the point being made in the quotation taken from the article. It is not a claim in itself.   Spinning  Spark  23:27, 23 April 2012 (UTC)

Carmine microbial production
"The carminic acid used to produce the pigment can also be extracted from various microbes engineered for the purpose." This is unreferenced- can I get some further information on microbial production of this compound? 71.223.9.1 (talk) 18:46, 23 April 2012 (UTC)

Some Biology questions
1)Till what age an average human gets taller?I mean, after what age the human height generally stops to increase?

2)Is the death is certain for every human being?.If it is provided all the necessities and is cured from all diseases then how the death would come? Max Viwe  &#124;  Wanna chat with me?  19:52, 23 April 2012 (UTC)


 * 2) Yes, death is certain. Some reasons:


 * 2a) Parts of our body wear out. Some are never replaced, like nerve cells.


 * 2b) Other parts can be replaced, but our bodies slow down the rate of replacement as we age. This seems to be evolution at work, using mechanisms like telomeres to ensure that we grow old and die, to make room for new individuals with new genes, so the species is better able to adapt to changing conditions.  (Note that there may be a way to fight telomere shortening, as with telomerase reverse transcriptase, but there are probably other mechanisms at work, too.)


 * 2c) We also have an accumulation of damage to our bodies, such as scars and genetic damage to DNA from UV light and other radiation.


 * 2d) If nothing else killed us, we would eventually die in an accident or violence. There are some plants and simpler organisms with no fixed lifespan, and this is what kills them all off, eventually.


 * 2e) As for artificial immortality: One day, if we can duplicate out brain in a computer, we might be able to live forever as a robot. With sufficient backups located far away (Pluto ?), this would make us reasonably safe from accidents, too. StuRat (talk) 20:40, 23 April 2012 (UTC)


 * Human height has a chart (for the US). Looking at it, it appears the average female stops at around 19, the average male at about 20. Taxes are certain; as for death, check out Immortality. Clarityfiend (talk) 21:09, 23 April 2012 (UTC)
 * 2b the main function of telomere shortening IIRC is to prevent rogue cells from becoming cancerous and killing you early in life. Only that fraction of cancer cells that manage to switch on their telomerase genes become really dangerous. That allows you to escape cancer for quite a while at a young age (when it really matters to evolution). The breakdown of the human body is also because of antagonistic pleiotropy - some genes that let you have a good early life at the cost of long term damage. An example is the choice between a strong immune response and the body eventually slipping up and attacking itself (diabetes and arthritis).Staticd (talk) 05:13, 24 April 2012 (UTC)


 * Death is by no means certain - like most biological phenomena, it sort of dissolves when you try to think about it. If the two halves of your brain were split apart from each other, and put into similar heads and sewn together with halves from some other person, would you still be alive?  What if you took half of each those halves and repeated?  And so on, until just one neuron from your brain was in each other head?  Would you be alive then?  Well, what if every neuron you have in your head is more or less identical to one neuron which is in some other person's head, somewhere in the world, right now?  Would you be alive then, in those heads, even if the original head were no more? Wnt (talk) 23:24, 23 April 2012 (UTC)


 * There is a difference between continuum of biology and continuum of self-aware personhood. Cell lines can be made to become immortal. Swapping hemispheres of the brain out would result (if it could be made to work in humans) in a completely new person. From a human perspective it is continuum of personhood that matters in the quest for immortality. Maybe we can achieve for people something similar to these lobsters. Sky Machine   ( ++ ) 23:59, 23 April 2012 (UTC)


 * 1) According to Introduction to Child Development by John Dworetzky, boys reach full height between 18 and 20 years, while girls between the ages of 15 and 17. Source: Roche & Devila 1972. Using the same source, Bodyspace: Anthropometry, Ergonomics, and the Design of Work by Stephen Pheasant gives a median age for reaching adult stature as 21.2 years for boys and 17.3 for girls, although 10% of boys were still growing after 23.5 and 10% of girls after 21.1 years. Alansplodge (talk) 01:00, 24 April 2012 (UTC)


 * For #2: I hope so. I can't take much more than 50-60 years of this shit... -- Jayron  32  04:05, 24 April 2012 (UTC)

what is the year old of the donkey when it begin to bray?
which is year old of the donkey when it start to bray? it's bray from the start when it's born? thank you. 95.35.155.88 (talk) 21:16, 23 April 2012 (UTC)


 * Are you asking about a Chinese zodiac year? There is a year of the horse, but no donkey. If this is not what you are asking about, perhaps you can clarify your question by providing context. -- ToE 03:17, 24 April 2012 (UTC)
 * My guess is that the question is "at what age does a donkey start to bray?". (I don't know the answer.) --Trovatore (talk) 03:18, 24 April 2012 (UTC)
 * Oh, of course! Thanks.  The answer might be found in some YouTube videos of newborn donkeys.  I don't have the bandwidth here to receive video, but I'll check later if I reception improves. -- ToE 03:28, 24 April 2012 (UTC)
 * yea, I meant about the age of donkey start to bray. I have found the answer in You tube. Thank all of you95.35.240.97 (talk) 13:11, 24 April 2012 (UTC)
 * If you found the answer, it is polite to share it even if you were the person who originally asked it. In case someone else comes looking for the same answer. Vespine (talk) 23:21, 25 April 2012 (UTC)
 * Yes. The best I could find were Huey - Braying where a 4 month old donkey's bray is quite recognizable, though high pitched, and Paper Tyger Braying! where a much younger donkey (age not given, but appears to be at most a couple of weeks old) brays at the end of the video, sounding more like a dog's squeeze toy. There are a lot of baby donkey videos out there; I only scratched the surface. -- ToE 11:42, 27 April 2012 (UTC)