SMF

John. To support your notion that twin studies are poorly controlled you found a good twin study that supports my contention that this research is experimental and not just simple correlation, and now you are disparaging your find. I conclude that you don't understand the research. SM

Lemur. I think that some of the carbon composites used in recent aircraft construction (stealth military and the 777) could be used for cars. The question is whether this method is practical for construction and, especially, for structural repairs often required for cars. SM

Marat:

One is that the immune systems of people in the Third World are weaker, given their frequent exposure to parasites and bacterial infections, so they are less resistant to AIDS.

 

Gay sexual practices which weaken the immune system.

 

Another theory is that parasitic infections common in the Third World create patterns of micro-tunnels throughout the body, thus promoting the spread of the AIDS virus, especially out of the vaginal canal.

Could you please document these three statements. I am not familiar with these concepts and would like to read up on the science. SM

John. You are agreeing with me on everything I have said but claiming I am wrong. The Schizophrenia opinion article you offered was about disease (infection of the mother during pregnancy) and the author admitted that it was only citing correlations, while the intelligence research article was a good twin study of the type that I have been saying is good science. Strange. You don't appear to understand what you are talking about, or how this type of science progresses, so further discussion is not worth pursuing. Perhaps someone else here can clarify for me how the Minnesota and Swedish twin projects are just producing correlational epidemiology, because I think this assertion is obviously incorrect. SM

OK John. The Schizophrenia article suggests that infection of the mother might be responsible for the disease. I asked you to provide evidence of phenotipic variability of normal traits, but you give me disease. In any case, because this article cautions against correlational studies regarding this relationship, saying- "Although epidemiological studies cannot establish causality," -it is basically an example, in your terms, of a bad example.

I just love the the Jacobs et.al. (2001) piece because it is an excellent illustration of what I have been saying. Here is a twin study that is able to identify the contribution of the intrauterine environment component that affects intelligence, relative to the inherited and post uterine environmental component, that can be attributed to monochorionic versus dichorionic environments of monozygotic twins. But if I wished to play your game I could still ask about the effect of the competence of the delivery teams and the disposition of the family dog on the result. Instead, I think I will just accept this study as a good example of scientific investigation about which I have been talking.

Just correlation eh, you make my point. SM

John, you are playing a distracting logical game. I don't believe that there are very many single studies, in any field, that by themselves don't have some uncertainty. This is why there is replication and extension of results by subsequent experimentation. Scientific certainty is never certain, it is always provisional and is accompanied with confidence limits. Further, like most research the twin studies are hypothesis driven and based on previous research. Your invoking of "just correlation" for this kind of research is inappropriate. Save it for the pop culture sassafras roots prevent cancer claims.

If you wish to continue with this silliness, I challenge you to come up with a half dozen differences in normal individuals that can be attributed to normal variations of the placenta. Give me one example. Find me the study that shows the effects of normal placental variation and using your logic I could claim it is just correlation. How about the competence of the delivery teams? How about the disposition of the family dog? This is a game that real scientists do not play; instead criticisms are based on existing facts and contradictory evidence. What is yours for the twin studies? SM

I suggest that you study up on Robert Goddard's work. There are probably some pretty good sources and construction plans for his working rockets. Here is a decent Wikipedia article about him. SM

http://en.wikipedia.org/wiki/Robert_H._Goddard#The_.27Goddard_rocket.27

In addition to what I and others have said above, I have a one word explanation based on the behavior of one of the members of my household just yesterday on the rug. Hairballs! Eat some grass and then yak it up. SM

Gnetic, could you please restate your question. I don't understand what you are asking well enough to comment. SM

So John, are you saying that in a large study which finds that if a trait is present that 100% of identical twins reared together, 100% of identical twins reared apart, 50% of nonidentical twins reared together or apart, but only 4% of adoptees reared together will share it, and 4% is the rate the trait is found in the general population as a whole, that the trait is not conclusively the result of genetic inheritance? This is an example of an extreme data set, but with large numbers of subjects the genetic component of many complex traits have been attributed, with high statistical significance, proportionally to inheritance or environment. This is what was contested in the discussion above. I don't think that anybody is claiming that simple demographic correlations with the frequency of some trait demonstrates causation. SM

Because with current technology there is absolutely no way to verify that dream content represents anything, assertions to the contrary are just unsupported opinion and speculation. SM

JohnG:

I think SamTheSkeptic is right in that using observation exclusively is inadequate to show that a correlation is actually a causation. I think that is the main criticism, hypotheses can't be test in humans because we would have to induce the genetic lesion to see if that results in the predicted change in behaviour. If there were no ethical consideration one could of course just remove a gene for a serotonin and see if that increases the chances of aggression later in life, like it does in mice. Or we could induce the mutations in the monoamine oxidase gene,that have been shown to increase the likelihood of aggression in humans, in a normal individual and see if that leads to the same effect. We can't obviously.

You seem to be confusing simple correlation with the experimental evidence provided by genetic diversity. For some traits the genetic differences (lesions?) are there for scientific observation and the twin studies, for example, are much more than simple correlations. They are natural experiments. SM

DrRocket, Early percussion caps for black powder weapons was fulminate of mercury and was manufactured in the early 1800s. SM

EDIT- a quick search finds http://www.powerlabs.org/chemlabs/fulminate.htm which shows how to make fulminate of mercury. I think that this may be illegal because it is a high explosive, but might be useful information for the OPs novel.

Eelpie. Cells, including neurons, recycle molecular components on some time scale. SM

Nathan. Note that 18^th century would be mostly muzzle loading flint locks. Black powder made it through most of the 19^th century and fowling was much less of a problem with black powder cartridges. It is even less when not using a revolver because the remaining solids don't coat the mechanism and are mostly swept from the barrel with each firing. For example, check out the Gatling gun. It could fire 150 to 200 rounds per minute (up to 600 in the 1864 model) for an hour. The extra barrels were to keep it cool. Black powder cartridges might be a better route for your novel because you don't have to make nitric and sulfuric acid and ether, and have to have oxygen free manufacturing to prevent ignition while washing out the acids (as per the String Junky link). I suggest you talk to some black powder enthusiasts about how to make or modify a modern semiautomatic weapon that could use black powder cartridges. SM

Dekan, this is an interesting question. It also suggests further questions regarding all pain. For example what is the function of cancer pain, or any internal pain from an evolutionary perspective? An external injury, such as a foot or hand, the pain is obviously telling you to leave it alone so it can heal. Disturbing a wound makes infection much more likely, and to make an infection worse. This is also true regarding internal injuries, but why cancer or a tooth ache. Actually, maybe there is a dentist in the house that could tell us if avoiding chewing on a painful tooth makes any difference in the progression of the disease.

For what it is worth, my opinion is that there is no evolutionary significance to pain that you can do nothing about or that is caused by something that will kill you no matter what you do. If some trait or factor doesn't affect the ability to pass on ones genes, there is no selection for or against it. SM

There are some cell types that are completely recycled every few days and others that last a lifetime. Most of the components of our cells are also recycled over some period, but there are some molecules that never are (look up lipofuscin). Any estimate of turnover time would have to consist of a mean and standard deviation in order to get some idea of how this all works, but why would anyone pursue this for the whole body? These sorts of pseudo facts get imbedded in popular culture and this one has achieved the memehood of the downright silly supposed fact that we all only use only 10% of our brains. I think there is wonder enough in the realization that a large though imperfectly measured turnover of our cells and molecules doesn't appear to affect our personhood. SM

Total.noob:

Heat.

SM

Lemur. Could you elaborate on all of the practical concerns regarding current solar technology. When you can buy a set of PV (photovoltaic) panels that pay off their cost, which of course includes the embodied energy, in a few years and then run on the sun for free for a guaranteed 20 years (many of the original panels used by consumers are still running after almost 50 years), where is the downside. SM

JohnG. I read the article and don't think it suggests an epidemic. More likely a few more bovine spongiform encephalopathy (BSE) cases over the years. This is an interesting study and the authors discussed several uncertainties regarding predicting from their data in some detail. A newer study by one of the authors has refined and broadened some of the findings, but conclude-

"Our data lend considerable support to the hypothesis that genetic susceptibility in addition to PRNP codon 129 genotype has contributed significantly to the outbreak of vCJD to date. Whether these effects are on the incubation period rather than susceptibility, such that further waves of BSE-associated prion disease with longer incubation periods might occur in the years ahead and be associated with different genotypes at many risk loci, is unknown."

http://www.ncbi.nlm....les/PMC2643048/

SM

CharonY, my point is that grant reviewers are quite capable of making decisions regarding what is fishing and what is promising exploration.

Regarding your comment about the old thread. It is always amusing to bring this up to tease those of us who begin commenting on an old thread. So, do you think this issue was settled in December '08, and do you think that MatthewF, who apparently was reading in the archives and found something interesting to comment on, was inappropriate in posting? SM

TonyMcC, your diagram has me very confused. It appears that the water tap that was opened was above the water tank and the only pressure on this system was only a few feet of water above the tap. I don’t see how a vacuum could have formed in the tank at all from opening the tap.

John Cuthber, any of us can only comment on what we know about when there is no country or standard specified. I am pretty sure that the depicted system is not common in 95% of the world, and I am very sure that any responsible plumbing contractor in the US would run screaming from this one for good reason.

SM

The problem with motivation is who decides what's cool enough or useful enough? Does it depend on species? How big is the field? The extremes are easy, but what about the middle? Who makes the call? And can you make that call in an objective manner?

Grant review panels at the NSF and NIH, composed of experts in the research area of the grant submissions, don't seem to have any problem making these decisions. If an application that proposes to explore something just to see what is going on looks interesting and has potential to encourage further research, the experts make pretty good decisions.

Along the lines of others above, I am loath to say that Darwin's or Golgi's many years of observation were not science. It seems to me that that careful and objective observations recorded and synthesized into something sensible, and published for others to replicate or build on is science at its best. In my own area, many lines of active research originally started with an "I wonder what is going on here" question, or was an accidental discovery. SM

TonyMcC, although the pressure relief valve on a hot water tank is set at 160psi they are pressure tested to 320 psi. These tanks are made of steel and normally would not collapse from air pressure. Pressure tanks in domestic water systems are subjected to an internal vacuum much more frequently than one might guess, and are designed appropriately. Your collapsed tank could have been seriously damaged by freezing, or it was rusted out. SM

Green Xenon. I know that there are some substances that are hydrophobic but not lipophilic, but I don't think the other way (lipophilic not hydrophobic) and Mississippichem might comment on this. I am pretty sure that completely lipophilic keratins might not assemble into the tough protein fibers required for their function, and intracellularly they might mess up cellular function. Remember, the soft keratins of the stratum corneum and the hard keratins of hair and finger nails are the cytoskeletons of keratinocytes. Keratinocytes make a very elaborate cytoskeletion that is bound together with adjacent cells via cellular junctions to make a very tough epithelial sheet. When the cells die their bound together cytoskeletons remain as the skin surface or make hair and nails.

What you are really asking is a sensory question- What would it feel like? This is an even more difficult question to answer, but I am pretty sure that altering the skin surface might make it very hard to keep clean. SM