"the damn americans are over sexed over paid and over here!"
To which the appropriate reply was, "The English are undersexed, underpaid, and under Eisenhower!"
Re:Whoa, two mea culpas here
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Nuke-Lobbing
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Better go ahead and toss on another mea culpa for me. I of course meant the Messerschmitt Me-163 Komet , the rocket-powered single-seat interceptor with absolutely unheard-of speed and climb rate, but with about a ten-minute max flight time, and an unusually strong correlation with horrific pilot death. I couldn't remember what the designation of the thing was, and when I typed "Me-162" into Google, I received a number of positive results pertaining to the rocket plane, so I wrote it into my post. I wasn't terribly concerned with this minor issue, as it was only tangential to the subject of the post, and it was also very, very late at night. Later, when I checked back to note the moderation/reply status of my post, I came upon this short thread and was initially confused, because I most definitely did not mean the Me-262, the twin-engine jet fighter/bomber, as that was indeed an engineering marvel and every subsequent jet aircraft owes much to its design. Then I saw the above post, and I found that I was terribly mistaken. A short analysis of the Google results I had earlier suggested that all of the hits I got were from sites that had made the same error. Thus, an unnecessary, though informative and entertaining, thread of discussion was started merely through reverseengineer's boundless stupidity. Guess I had better dust off my copy of "Secret Weapons of the Luftwaffe," which, by the way, lets you fly the Me-163 Komet. Gah.
Oh, and there was a He-162 Volksjager jet fighter, actually, which I learned about in the course of measuring my ignorance (which turned out to be a set with an infinite number of elements). It was a single-engine fighter of unusual design- the single turbojet sat directly aft of the cockpit, making it strongly resemble a piloted V-1 buzz-bomb (although the similarities were purely cosmetic). Incredibly, it went from blueprint to production in a matter of months (during which time, it suffered a number of horrific accidents, mostly the result of substandard glue keeping the plane together), but only a few saw combat before the war ended.
Re:Other Smart Ideas...
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· Score: 4, Informative
I'd like to point out that the Davy Crockett (Best. Weapon. Ever.) which is referenced in my slightly later post (you beat me by 6 minutes) does not fire a 40 kiloton nuclear warhead, it fires a roughly 40 ton nuclear warhead, a difference of three orders of magnitude. The Hiroshima device is estimated at about 15 kilotons; these are about 0.04 kilotons. These are the smallest nuclear warheads ever created, with an explosive power between 2-4 times that of the ANFO bomb that was used to destroy the Murrah Federal Building in Oklahoma City. The equivalent of 40 tons of TNT is still enough to cause a gigantic explosion, of course, and gives you some sort of idea of the incredible devastation caused by a strategic thermonuclear warhead in the megaton range.
Those Wacky 50s
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· Score: 4, Informative
Yeah, this is from a very interesting time in the history of military strategy- that period from 1949 to the invention of the ICBM in the late 1950s. In 1949, the Soviets demonstrated that they had entered the Nuclear Age (with a little help from spies), thus ending America's window to conduct "atomic bomb diplomacy"- if you have a weapon that can destroy an entire city, and no one else has one, or any sort of effective countermeasure, you can get pretty far with extortion.
When the Soviets got the Bomb, of course, the Cold War started in earnest, and so plans had to be drawn up to fight the most colossal and devastating war in human history (hot on the heels of that previous most colossal and devastating war in human history where the Soviet happened to be our allies). It was of course feared that in this upcoming war, the Soviets would have a tremendous advantage in conventional forces, and waves of Soviet tanks would roll across Europe. Thus, our rapidly growing stockpile of atomic bombs would become an important asset. The major question was how these weapons would be delivered. The Air Force of course responded by building a fleet of long range strategic bombers, and the Navy a fleet of submarines that could launch nuclear missiles; these measures, however, took years to set up, leading to a variety of interesting stopgap measures. This includes the lovely "idiot loop" maneuver explained here of course, as well as the Army's approaches, which included a 280mm cannon that fired atomic artillery shells, and what is perhaps the most unbelievable weapon in military history (and that includes the insane ideas the Nazis had at the end of WWII like the Me-162), the
Davy Crockett. Why yes, that is a nuclear warhead being fired out of a recoilless rifle barrel.
Like I said, these were stopgap measures, born out of desperation. Of course, this period pretty much entered its twilight with the development of the thermonuclear "Super" device, and was utterly swept away with the advent of the ICBM and SLBM to carry it. It became clear that there was no longer any place for tactics on a nuclear battlefield- with thousands of ballistic missiles on each side, most of civilization would be vapor before conventional troops got loaded into the transport plane. Also, the long term effects of radiation were becoming known- how does the traditional idea of territorial control work if in order to gain territory, you have to nuke it? Anyway, some of the ideas that came up in this short period were pretty crazy, but they're pretty much par for the course in military history- whenever a new technology hits the battlefield, strategists go nuts trying to either combat against it, or work it into their plans- compare this period in history, where a weapon of incredible power threatened to make conventional forces obsolete, to a period like the introduction of firearms to the medieval battlefield, or the introduction of the ironclad in naval battles- the old weapons and strategies quickly beome obsolete, and military planners become willing to try absolutely anything to gain the upper hand.
Yeah, the best parts of this article for me were definitely when the crew cut 3 tenths of a second off the quarter-mile time by simply swapping 15-inch wheels for those 19-inch penis magnifiers the owner had on, and when they removed those ridiculous spoilers/air dams/etc. You might have to worry about aerodynamic drag and downforce at Indy or an NHRA dragster event, but street racing in a sport compact? As these guys demonstrate (by taking it to its absurd limit), in that situation, you'll want the lightest car with the most powerful engine.
The next time I see some idiot motoring down the street in a riced out 4-cyl. with a giant aluminum rear spoiler, glasspack muffler, "blackout" or clear polycarbonate head/tailights, 3cm of ground clearance, tires that belong at Indy, and decals for products the owner is not paid to endorse (and are probably not present in the car), I will remember this article. And then I will laugh.
Nope, it's named for
Brian Josephson , who as the link mentions won a share of the 1973 Nobel for it. I've read, however, that his more recent research interests have strayed well outside the scientific mainstream- parapsychology, ESP, cold fusion, homeopathy, etc...
Superconductors have a number of important uses in analytical instruments, too. A superconducting magnet sits at the heart of most nuclear magnetic resonance machines, as such magnets are capable of carrying enormous currents with almost no resistance, enabling them to produce magnetic fields of over 20T (400,000 times the strength of the magnetic field of the earth). Most of these magnets are made from alloys of niobium, with critical temperatures (the temp below which superconductivity occurs) around 23 Kelvin, meaning they need liquid helium to cool them. I happen to have a student job dispensing cryogens for research groups on campus- we charge about 4 bucks a liter for liquid helium, and some groups will go through a full 65L dewar in a couple days. Efforts have been made to move to the Type II (cuprate ceramic) superconductors discovered in the late 1980s, but as others have mentioned, ceramic can't be extruded into wire the way most metals can. Still, there is significant financial incentive to use Type II materials- liquid nitrogen, which boils at 77K, only costs about 20 cents per liter. Of course, with a room-temperature superconductor, there would be no cooling expenses, and there would also be no need for bulky cryostats surrounding equipment- it's likely we could see mobile MRI and NMR machines.
In addition to their uses as magnetic coils, superconductors can be used to exploit something nifty called the Josephson effect: if you separate two superconductors by a tiny insulating gap, a supercurrent of Cooper pairs can quantum tunnel across the gap. This effect can be used in a device known as a SQUID (Superconducting QUantum Interference Device), which is essentially a fantastically sensitive magnetometer- some SQUIDs can detect fields of less than a picotesla. This has already had important applications in materials science- there are scanning-SQUID microscopes, and is finding a number of uses in medicine- specifically measuring the magnetic activity of the brain and heart. Also, SQUIDs will probably have a future in computers, as hyperfast switches, sensitive hard disk heads, or as sensors used in quantum computers, detecting the state of a qubit. IBM tried to make a computer using Josephson junctions as switches back in the late 1970s- there were a number of hurdles that prevented this device from becoming a reality, mostly the incredible rate at which "conventional" silicon chip ICs were improved, and the fact that this conventional technology does not require you to immerse your computer in liquid helium.
And yeah, there could finally be maglev trains- those operate off of the Meissner effect, discovered in the 1930s- superconductors are perfectly diamagnetic- they will expel any external magnetic field, causing the magnet (or superconductor) to be levitated. This is the effect that the scientist who observed the possible diamond RTS admits he has not done experiments to check, and it's the effect I'd really need evidence of in order to believe his findings.
Just adding to that excellent explanation, the arcane code HD 141569A merely gives the star's listing in the Henry Draper Catalogue, a gigantic star catalogue (over 250,000 entries) first compiled about a century ago. The spectral class A does denote that HD 141569A is a young, fairly massive, and hot star- its surface temperature should be between 7,500 - 10,000K, and it should be white to blue-white in color. Another example of an A type star would be Sirius.
I also wanted to point out that the story submitter gets it a bit wrong- which is more the fault of the story, which fails to make this clear- HD 141569A is not in a binary system with a single companion star, it is in a three star system with two other stars. These other two stars, HD 141569B and HD 141569C, are in a binary relationship with each other, and together perturb the disk around HD 141569A, which is over 100 billion miles from the pair. This paper (.pdf file) from 1999 on the Arxiv
gives more details on the star system and protoplanetary disk.
This family of viruses (paramyxoviruses) are very closely related to influenza viruses- in fact, influenzas belong to the family orthomyxoviridae. Myxo, by the way, comes from the Greek for "mucus"- appropriate given their tendency to cause respiratory tract infections.
Both families are single-stranded "antisense" RNA viruses- the RNA strand is complementary to a coding, or "sense" strand of mRNA that it acts as a template for. It should be noted that while these are RNA viruses, they are not retroviruses, as some other posters have suggested- no reverse transcriptase, no DNA stage- instead of hijacking the cell's transcription machinery like HIV, myxoviruses are slightly more considerate guests- they come packing their own RNA polymerase proteins. The RNA polymerase makes a gigantic number of of sense mRNA from the antisense strand. Once these get made, the virus stops being a considerate guest in the cell- the mRNAs head over to the ribosomes in the cell and get translated into proteins just as if the cell's genome had produced them. These are of course viral proteins however- new capsids (protein envelopes), new polymerases, new glycoproteins. This is the part where it really starts to suck for the cell- the original viral antisense mRNA gets replicated many times, and then gets packed into the newly made viral particles. The viruses then lyse (kill) their host cell and then spread out an move on to a new cell. This takes about 20-30 minutes from fusion with the cell to lysis usually.
Both ortho- and para- myxovirus families respond to a characteristic test called hemagglutination, which is pretty much what it sounds like- a glycoprotein on the surface of the virus causes red blood cells to clump together. The major difference between the orthomyxoviridae and paramyxoviridae families is simply a matter of genome arrangement- ortho viruses like the influenzas have their genomes cut into several different smaller segments inside the virus, while the para viruses like measles, rinderpest, and our mystery illness have a single segment.
It should be stressed that genome comparisons are of limited help at the level of families- all the single-stranded antisense RNA viruses have pretty much the same structure, but they code for quite different glycoproteins (these are sugar-protein hybrid molecules on the surface of the virus). Glycoproteins are both the source of host recognition- they bind to specific receptors on a cell (these receptors are often, but not always, unique to the cells of a species)- and the agent that kills the cell. In the paramyxoviruses, remarkably these two functions (fusion and lysis) are carried out by two linked subunits on the same glycoprotein.
The variety of glycoproteins these RNA viruses have produced have made them incredibly diverse- they infect plants, animals, humans, they cause all manner of symptoms. The paramyxoviruses, for example, have members which result in mumps and measles, and then others that cause pneumonia. A closely related family (also ss antisense RNA) are the rhabdoviruses, some of which infect plants, and one of which causes rabies. Another antisense ssRNA family are the filoviruses, which tend to have rather toxic glycoproteins- members include Marburg and Ebola.
While it is a relief that the virus causing this deadly outbreak of pneumonia has been isolated, and catalogued in relation to other viruses, it should be noted that finding this relation may be of little use, given the nearly infinite variety displayed by even its closest relatives.
I totally agree. I was lucky enough to have science teachers in junior high and high school who emphasized hands-on learning. Textbooks can be a valuable resource, but they can't be used as a crutch. In most of my classes, textbooks were used to assign homework and practice problems, but the teaching was done by the teacher.
Of course, I think my teachers' decisions to not make much use of textbooks stemmed in part from the texts sucking pretty hard. Given their current state as a mishmash of facts written by committee, I'd say teaching science from only a middle-school science text would be like teaching English using only a dictionary. The facts are all present and accounted for, but the presentation is a bit dry. Personally, I think Joy Hakim's overhaul sounds like an excellent idea- there are some fascinating stories in science, and I think that they could greatly enrich the material.
A careful balance has to be struck, however, between these "stories" and academic rigor. On the one hand, I would argue that learning about how learning how Newton and Leibniz hated each other, for example, is not as important as learning about their independent discovery of the calculus. Any changes made to middle school science must keep in mind that some of the students passing through middle school will become our nation's next generation of scientists. I don't want to see kids get three years of touchy-feely science "stories" with no real science and then go on to get overrun in high school and college when they take hardcore "real" science courses. On the other hand, I had the honor of meeting distinguished physicist and Nobel laureate Leon Lederman acoupke weeks ago- he gave a talk about his efforts to reform science education at the high school level, actually- and he said something that made a lot of sense. He pointed out that the scientific way of thinking would certainly be a good thing for all citizens to have- it promotes a very healthy sense of skepticism. Thus, any attempt to modify science education must walk a fine line, catering to both future scientists and every other student. While I am a proponent of rigor in science education, I think it would be a damn shame to turn off otherwise bright, eager students from the joys of science on account of a boring textbook. We have to encourage the few, but in a modern world surrounded by science, we can't afford to alienate the many.
I wonder why the oldest history book we have says that the Egyptians Imprisoned the Jews for work; slavery.
I suppose none of the labor on the Pyramids was slave labor?
You suppose correctly, actually- the pyramids predate Israelite captivity by centuries- the pyramids at Giza were built 400-500 years before Abraham, actually. The Israelites built a number of storage cities for the pharaohs, but no major pyramids.
Also, I'm assuming that when you write "the oldest history book we have" you mean the Bible, which is incorrect- there are extensive Sumerian, Babylonian, Egyptian, and Chinese historical records that all predate the writings of the Pentateuch.
The suitcase that serves as Reason's power supply and ammo dump is open on the deck next to him, its color monitor screen reading: Sorry, a fatal system error occured. Please reboot and try again.
Well, they're footprints of a recent precursor to modern humans, Homo heidelbergensis, which is believed to be the forerunner of both H. neanderthalensis and H. sapiens There are some paleoanthropologists, however, who think that H. heidelbergensis (I just love that name) might only be the direct ancestor of Neanderthals and that the break between H. neanderthalensis and H. sapiens occurred earlier.
It is also interesting to note that these footprints indicate that they were made by beings which were approximately 4.5ft (1.5m) tall, though H. heidelbergensis remains suggest that adults of the species may have been as tall as 6 feet (1.9m). Thus, as the article suggests, these footprints may have been made by children- or they made be from a completely different hominid species.
In fact, the only thing I think they could use their tenuous logic to justify would be a hard drive. In that case, what if I build a computer with two drives?
Two hard drives? Of course you should get taxed twice- the only possible reason you'd need that much storage is to steal twice as much music!
1. You seem to think that this kid will have only one purpose in life, but in fact, he/she will have two: to save a sibling's life AND to live. If anything, this child has more purpose going for it than the thousands of children born every day because approximately nine months earlier their parents decided to chance it and not use contraception. This child cannot be a failure; even if its cord blood does not cure its sibling, it will still be a human child.
2. This is wildly unrealistic- that the parents would possess alleles for two different genetic ailments that can only be cured by sibling cord blood is extremely improbable. Yet, if it were to occur, and embryos could then be selected that possessed neither ailment (if any existed), and the funds for another round of IVF were available, then I see no reason to deny them the chance. If the couple is really that desperate, and you deny them IVF, it's likely that they might attempt to conceive a child "the old-fashioned way," taking the risk it would bear one or both disorders.
3. Looking at it in pragmatic (and harsh)terms first of all, why would you abort a fetus that cost so much money to conceive? Really, if you wanted to do this, you would not implant the embryo at all- you would simply convert it into a line of stem cells.
4. Huh? First off, the second kid does not even need to be alive to save its sibling's life- you said so yourself in #3. Second, how is the first kid "already dead?" If that were the case, everyone dying of a terminal illness would be legally dead.
5. Look, these parents aren't creating the ubermensch, or an Alpha. To call this a "designer baby" is inaccurate- this child would not be genetically modified in any way- all of its genes will come from its parents, who received them from their parents. A chance exists that the parents could "naturally" produce a child without this genetic defect- but not a very good one. Chance favors the prepared mind, and also the parents who were able to select an embryo with IVF.
6. Why must we kowtow to evolution? Rejecting the idea that producing children that will slowly and agonizingly die from an inherited disease is heaven working in mysterious ways and replacing it with the idea that we must let natural selection discard harmful alleles from the gene pool is merely replacing one tyranny with another. Fsck, at least God has a grand plan, or so I'm told. The examples you give of diseases that tie into our species' supposed genetic fitness decline are rather interesting- I'd say increases in the first four are much more the result of lifestyle choices than genetics (well, not if you mean Type I diabetes, I suppose) As far as asthma, I'd say that has to do more with pollution than genes. Allergies are rather interesting though- I'd suspect that in addition to environmental factors (including the pollution again), at least a small portion of that might be due to the spreading and interbreeding of long isolated groups of humans- thus spreading around genes for hypersensitivities. Anyway, the couple with a child with sickle-cell anemia raises an interesting point- this is the textbook case of a genetic disease that evolution built. Sickle-cell anemia has been known for thousands of years, and until recent advances (such as this cord blood therapy, for instance) was generally lethal at a relatively young age. However, it's stayed around mostly because it is a recessive disorder, and more importantly, the heterozygote (one copy of the normal "wild type" dominant gene and one defective sickle-cell recessive copy) has a resistance to infection by malaria. If this child survives, and then lives to procreate, it is likely that this heterozygote advantage will be conferred on them- that doesn't sound like enfeebling the human race to me.
7. Making this one shorter, I'm sure that's already been tried- many hospitals have set up cord blood donation programs- but a blood relation- particularly a sibling- stands an excellent chance of being a precise match.
8. Now, suppose this child were old enough to understand the present situation- what do you think the child would want? If the parents are willing to do all of this to save their child's life, it would seem that they hold that child to be rather precious. You can be cynical and claim that if the older child dies, he is merely being "replaced," but then the same is true for every other couple who wishes to conceive again after the death of a child. Surely they aren't being selfish?
Phantom Energy and Wormholes
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Man, 22 billion years? I was hoping I could hold out until my protons decay (10^33 years, according to some supersymmetry models). On the other hand, the article does point out that the presence of dark energy makes stable, long-lived wormholes possible, thus enabling us to perhaps see more of the universe before its sudden and catastrophic end. Unfortunately, I suppose it may then be possible to lay waste to the universe manually by setting up bizarre time-traveling paradoxes that create loops in cause and effect. Dammned if you do...
Yeah, I don't know just how practical this setup would actually be out in the real world as far as biosensing. It's probably more suited to the next generation of laboratory gene chips, as you say. The Nature Materials paper of course says nothing about combating bioterror (it does mention the possible use of this technique in improved biosensors), so I think your "P.T. Barnum" comment may be right on target as far as the buzzword-laden but noninformative press release goes. Can't really blame the university from a public relations standpoint, as "Scientists create prototype for next-gen gene array" just doesn't have the same punch as "SCIENCE FIGHTS TERROR!" grandstanding.
The conclusions in this article make a lot of sense actually- the conditions in the solar system are in many ways similar to a chemical vapor deposition setup- very low pressure, almost no oxygen, and yet still plenty of material to use as both a vapor (carbon) and substrate (asteroids, comets, dust motes, etc.). I'd expect that these nanodiamonds are simply the result of carbon atoms coming together and clustering on a surface, with the carbon of course in conditions suitable for diamond formation. I would expect that nanoscale clusters of the other carbon allotropes, graphite and fullerenes, should be found in abundance in the asteroid belt as well.
This press release is rather short on information (read: no information), but the Nature Materials article itself is a bit more helpful. Now, my university is shelling out a bunch of cash for a site license, and I'm sure neither they nor Nature would like me to post that article here, so I will not do that. The abstract is free though:
Diamond, because of its electrical and chemical properties, may be a suitable material for integrated sensing and signal processing. But methods to control chemical or biological modifications on diamond surfaces have not been established. Here, we show that nanocrystalline diamond thin-films covalently modified with DNA oligonucleotides provide an extremely stable, highly selective platform in subsequent surface hybridization processes. We used a photochemical modification scheme to chemically modify clean, H-terminated nanocrystalline diamond surfaces grown on silicon substrates, producing a homogeneous layer of amine groups that serve as sites for DNA attachment. After linking DNA to the amine groups, hybridization reactions with fluorescently tagged complementary and non-complementary oligonucleotides showed no detectable non-specific adsorption, with extremely good selectivity between matched and mismatched sequences. Comparison of DNA-modified ultra-nanocrystalline diamond films with other commonly used surfaces for biological modification, such as gold, silicon, glass and glassy carbon, showed that diamond is unique in its ability to achieve very high stability and sensitivity while also being compatible with microelectronics processing technologies. These results suggest that diamond thin-films may be a nearly ideal substrate for integration of microelectronics with biological modification and sensing.
The method of attachment of DNA to a diamond surface is particularly clever: they use photochemistry to attach a long chain primary amine to the surface of the diamond, and then use a rather curious and complicated sulfur-containing organic molecule called SSMCC to act as a bridge between the diamond/amine and the strand of DNA. Essentially, you get these strands of DNA that point out into the environment like sticky threads. The sensing aspect, presumably (they don't go too much into it in the article - as the press release notes, they plan on discussing that in a meeting of the ACS) takes place as foreign DNAs contact the sensor. As the abstract tells us, the specificity of the attached DNA strands is not compromised by the diamond bonding technique, so the DNA strands can identify a certain complementary DNA sequence present in the enviroment, say, from Bacillus anthracis. Presumably the change induced in the diamond-bonded DNA that occurs when the complement hydrogen bonds with it will then trigger some sort of physically detectable action- you could tag the DNA with a fluorescent dye, for example, and measure how the fluorescence levels change between bonded and unbounded forms. This sort of information can then be translated into an electronic signal. This has a long ways to go before being a practical outside-the-lab type of device, but the results are still pretty exciting.
The problem with nuclear fusion is that it has been the classic example of a tech that's 50 years away- and it's been that way for the last 50 years. It's turned out to be a much more thorny problem than people anticipated- uncontrolled fusion reactions are fairly easy to produce after all- just direct the energy from a fission primary at an appropriate quantity of tritium. Unfortunately, this is a hydrogen bomb, and makes for a rather inefficient power source.
However, controlled confinement of plasma has proven to be much harder. ITER will use the most popular confinement method, a tokamak, which is a design devised by the Soviets (Tamm and Sakharov) back in the 1960s. So essentially, the basic plan is 40 years old, but there have been a number of obstacles- political and economic as well as technical to making this work. It will be interesting to see if their tokamak avoids the key problem of the design; in a tokamak, the plasma itself has an internal current running through it (as opposed to other designs like stellarators) and has proved rather deifficult to contain in the torus. I believe the Joint European Torus has had several "disruptions" of this sort that have lifted the several hundred ton vessel off its bolts. The good news, of course, is that such events (which are rare, and should be much more rare in a non-experimental reactor) are really the worst things that can happen to a fusion reactor. Although the plasma is extremely hot, it is not very dense at all (obtaining a critical density is really the greatest challenge) and thus there exists no possibility of 300 million Kelvin plasma vaporizing the container walls in some sort of runaway accident. Also, while they are not completely clean (no power generation method is) the radioactivity produced is low level, especially in comparision with fission reactor spent fuel rods.
First of all, there is little to no genetic basis for race- it's been pointed out that more genetic variation exists among the tribes of apes living in one river valley in Congo than exists among every human being on this planet. At some point in the history of our species, there was a bottleneck or founder effect, and nearly every homo sapiens is thus very nearly genetically identical.
There is, however, an epidemiological basis for classifying humans into genetic groups that correspond to race- as chance would have it, groups of humans became isolated as they spread across the planet, creating founder effects that eventually led to distinct physical appearance. There are also distinct invisible genetic differences among races, and it would be foolish to ignore these in the name of political correctness- the higher incidence of Caucasians having cystic fibrosis genes, or Africans having sickle-cell or Ashkenazaic Jews having Tay-Sachs genes. Can these genetic traits extend into personality? Perhaps they can. However, while they get compared to blueprints, genes are really more like algorithms- iterative processes dependent on inputs, which can sometimes be completely random, or at least effectively so. Look at the case of cc, that cat clone- looks very little like the animal she was cloned from. Physical appearance is extremely complicated, with multiple genes acting in concert and in opposition with each other. Nurture of course also plays a role as well. Isn't it logical to assume that personality traits in humans will be at least as complicated? What genes do is chemistry, and can influence behavior and personality only in the sorts of ways that chemicals can. Look at the present psychopharmacopeia: antidepressants, tranquilizers, stimultants- but none of these change who you are.
However, referencing yout comment about being able to escape one's culture, I cannot wait until some team of researchers finds "the gene" that determines whether you are going to be more or less likely to try to rebel from your culture.;)
Nope, you meant moieties of the peptides, at least if you were indeed talking about protein folding. No problem though- it's evident what you're saying, and I wouldn't have even noticed until you pointed it out.
Come on! We are the ones who should be embracing this! Who's gonna convince Kamen to invent the Segway you really want? You know, the chariot version, that gets 5x the distance, and is 1/5 the price? It cannot get here by itself.
Now, I understand the "early-adopter" model of sales and everything,and that's fine. That tends to work because early adopters still end up with a product they want, and were willing to pay a premium for the utility and the cache of being first. However, you seem to be suggesting that we should support a product that we don't want so that a company can develop a product that we do want. If I'm going to be Dean Kamen's venture capitalist, I'd like to get more for my money than an 40 kg plastic scooter.
No, while the first organophosphate nerve agents were developed by the Germans in the years prior to WWII, including tabun, soman, and sarin, the most deadly (lowest LD50) nerve agent known, VX (o-ethyl methyl phosphonothiolate), was discovered by British scientists in the 1950s. The story I have heard is that the British then traded the process of VX synthesis to the Americans- for the details of building thermonuclear weapons.
All the nerve agents in this general class are rather nasty- tabun and soman were used by Iraq in their 1980-88 war against Iran, which the US cast a blind eye to (at the very least), and then they used them to kill Kurd and Shiite dissidents in Iraq itself afterward. Then in the mid-90s, the Japanese doomsday cult Aum Shinrikyo released sarin in several attacks, including in the Tokyo subway system in 1995, killing 12 and injuring 5000. If they had used a more sophisticated delivery system (they used sharpened umbrella tips to puncture bags of liquid sarin), it is likely the death toll would have been far larger.
A nerve agent attack on any populated area could be extraordinarily deadly, and would certainly carry the additional weight of psychological terror- the fear that the air you breathe is contaminated with an invisible killer. And VX in particular is extremely long-lived in most environments (by design) Contact with residue could lead to injuries and deaths long after the initial attack. However, the syntheses involved in making organophosphate nerve agents are nontrivial. They make relatively unlikely terrorist agents simply because there are so many easier ways to kill and terrorize people- mustard, chlorine, phosgene, as well as biological agents like anthrax, botulin toxin, or a hemorrhagic fever virus. The feds seem so concerned about smallpox, for whatever reason, when the nations that have had Ebola outbreaks (Congo, Cote D'Ivoire, and Sudan) are in so much political chaos that setting up a lab and collecting and amplifying virus appears quite possible (whereas the only known smallpox stocks in the world are being kept in cold storage in Russia and the US).
I don't believe that much of this sort of information should be kept secret. I realize I know quite a bit about bioterror for a private citizen- but I'm not planning on becoming a terrorist- quite the opposite. I didn't obtain any knowledge from breaking into a top secret lab or kidnapping a scientist or cracking into a database anyway. As with many things, knowing how to defeat a threat involves understanding the threat (compare to computer security). Terrorists already know how to kill people- the information published in scientific journals is what's going to stop them. Secret government labs are of course going to be a large part of our nation's defense, as they have been for decades. However, the free exchange of information among labs holds the promise that discoveries could be made much more quickly.
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To which the appropriate reply was, "The English are undersexed, underpaid, and under Eisenhower!"
Oh, and there was a He-162 Volksjager jet fighter, actually, which I learned about in the course of measuring my ignorance (which turned out to be a set with an infinite number of elements). It was a single-engine fighter of unusual design- the single turbojet sat directly aft of the cockpit, making it strongly resemble a piloted V-1 buzz-bomb (although the similarities were purely cosmetic). Incredibly, it went from blueprint to production in a matter of months (during which time, it suffered a number of horrific accidents, mostly the result of substandard glue keeping the plane together), but only a few saw combat before the war ended.
I'd like to point out that the Davy Crockett (Best. Weapon. Ever.) which is referenced in my slightly later post (you beat me by 6 minutes) does not fire a 40 kiloton nuclear warhead, it fires a roughly 40 ton nuclear warhead, a difference of three orders of magnitude. The Hiroshima device is estimated at about 15 kilotons; these are about 0.04 kilotons. These are the smallest nuclear warheads ever created, with an explosive power between 2-4 times that of the ANFO bomb that was used to destroy the Murrah Federal Building in Oklahoma City. The equivalent of 40 tons of TNT is still enough to cause a gigantic explosion, of course, and gives you some sort of idea of the incredible devastation caused by a strategic thermonuclear warhead in the megaton range.
When the Soviets got the Bomb, of course, the Cold War started in earnest, and so plans had to be drawn up to fight the most colossal and devastating war in human history (hot on the heels of that previous most colossal and devastating war in human history where the Soviet happened to be our allies). It was of course feared that in this upcoming war, the Soviets would have a tremendous advantage in conventional forces, and waves of Soviet tanks would roll across Europe. Thus, our rapidly growing stockpile of atomic bombs would become an important asset. The major question was how these weapons would be delivered. The Air Force of course responded by building a fleet of long range strategic bombers, and the Navy a fleet of submarines that could launch nuclear missiles; these measures, however, took years to set up, leading to a variety of interesting stopgap measures. This includes the lovely "idiot loop" maneuver explained here of course, as well as the Army's approaches, which included a 280mm cannon that fired atomic artillery shells, and what is perhaps the most unbelievable weapon in military history (and that includes the insane ideas the Nazis had at the end of WWII like the Me-162), the Davy Crockett. Why yes, that is a nuclear warhead being fired out of a recoilless rifle barrel.
Like I said, these were stopgap measures, born out of desperation. Of course, this period pretty much entered its twilight with the development of the thermonuclear "Super" device, and was utterly swept away with the advent of the ICBM and SLBM to carry it. It became clear that there was no longer any place for tactics on a nuclear battlefield- with thousands of ballistic missiles on each side, most of civilization would be vapor before conventional troops got loaded into the transport plane. Also, the long term effects of radiation were becoming known- how does the traditional idea of territorial control work if in order to gain territory, you have to nuke it? Anyway, some of the ideas that came up in this short period were pretty crazy, but they're pretty much par for the course in military history- whenever a new technology hits the battlefield, strategists go nuts trying to either combat against it, or work it into their plans- compare this period in history, where a weapon of incredible power threatened to make conventional forces obsolete, to a period like the introduction of firearms to the medieval battlefield, or the introduction of the ironclad in naval battles- the old weapons and strategies quickly beome obsolete, and military planners become willing to try absolutely anything to gain the upper hand.
C'mon, you totally forgot chemical engineers: http://www.astroglide.com/
The next time I see some idiot motoring down the street in a riced out 4-cyl. with a giant aluminum rear spoiler, glasspack muffler, "blackout" or clear polycarbonate head/tailights, 3cm of ground clearance, tires that belong at Indy, and decals for products the owner is not paid to endorse (and are probably not present in the car), I will remember this article. And then I will laugh.
Nope, it's named for Brian Josephson , who as the link mentions won a share of the 1973 Nobel for it. I've read, however, that his more recent research interests have strayed well outside the scientific mainstream- parapsychology, ESP, cold fusion, homeopathy, etc...
Superconductors have a number of important uses in analytical instruments, too. A superconducting magnet sits at the heart of most nuclear magnetic resonance machines, as such magnets are capable of carrying enormous currents with almost no resistance, enabling them to produce magnetic fields of over 20T (400,000 times the strength of the magnetic field of the earth). Most of these magnets are made from alloys of niobium, with critical temperatures (the temp below which superconductivity occurs) around 23 Kelvin, meaning they need liquid helium to cool them. I happen to have a student job dispensing cryogens for research groups on campus- we charge about 4 bucks a liter for liquid helium, and some groups will go through a full 65L dewar in a couple days. Efforts have been made to move to the Type II (cuprate ceramic) superconductors discovered in the late 1980s, but as others have mentioned, ceramic can't be extruded into wire the way most metals can. Still, there is significant financial incentive to use Type II materials- liquid nitrogen, which boils at 77K, only costs about 20 cents per liter. Of course, with a room-temperature superconductor, there would be no cooling expenses, and there would also be no need for bulky cryostats surrounding equipment- it's likely we could see mobile MRI and NMR machines.
In addition to their uses as magnetic coils, superconductors can be used to exploit something nifty called the Josephson effect: if you separate two superconductors by a tiny insulating gap, a supercurrent of Cooper pairs can quantum tunnel across the gap. This effect can be used in a device known as a SQUID (Superconducting QUantum Interference Device), which is essentially a fantastically sensitive magnetometer- some SQUIDs can detect fields of less than a picotesla. This has already had important applications in materials science- there are scanning-SQUID microscopes, and is finding a number of uses in medicine- specifically measuring the magnetic activity of the brain and heart. Also, SQUIDs will probably have a future in computers, as hyperfast switches, sensitive hard disk heads, or as sensors used in quantum computers, detecting the state of a qubit. IBM tried to make a computer using Josephson junctions as switches back in the late 1970s- there were a number of hurdles that prevented this device from becoming a reality, mostly the incredible rate at which "conventional" silicon chip ICs were improved, and the fact that this conventional technology does not require you to immerse your computer in liquid helium.
And yeah, there could finally be maglev trains- those operate off of the Meissner effect, discovered in the 1930s- superconductors are perfectly diamagnetic- they will expel any external magnetic field, causing the magnet (or superconductor) to be levitated. This is the effect that the scientist who observed the possible diamond RTS admits he has not done experiments to check, and it's the effect I'd really need evidence of in order to believe his findings.
Just adding to that excellent explanation, the arcane code HD 141569A merely gives the star's listing in the Henry Draper Catalogue, a gigantic star catalogue (over 250,000 entries) first compiled about a century ago. The spectral class A does denote that HD 141569A is a young, fairly massive, and hot star- its surface temperature should be between 7,500 - 10,000K, and it should be white to blue-white in color. Another example of an A type star would be Sirius.
I also wanted to point out that the story submitter gets it a bit wrong- which is more the fault of the story, which fails to make this clear- HD 141569A is not in a binary system with a single companion star, it is in a three star system with two other stars. These other two stars, HD 141569B and HD 141569C, are in a binary relationship with each other, and together perturb the disk around HD 141569A, which is over 100 billion miles from the pair. This paper (.pdf file) from 1999 on the Arxiv gives more details on the star system and protoplanetary disk.
This family of viruses (paramyxoviruses) are very closely related to influenza viruses- in fact, influenzas belong to the family orthomyxoviridae. Myxo, by the way, comes from the Greek for "mucus"- appropriate given their tendency to cause respiratory tract infections.
Both families are single-stranded "antisense" RNA viruses- the RNA strand is complementary to a coding, or "sense" strand of mRNA that it acts as a template for. It should be noted that while these are RNA viruses, they are not retroviruses, as some other posters have suggested- no reverse transcriptase, no DNA stage- instead of hijacking the cell's transcription machinery like HIV, myxoviruses are slightly more considerate guests- they come packing their own RNA polymerase proteins. The RNA polymerase makes a gigantic number of of sense mRNA from the antisense strand. Once these get made, the virus stops being a considerate guest in the cell- the mRNAs head over to the ribosomes in the cell and get translated into proteins just as if the cell's genome had produced them. These are of course viral proteins however- new capsids (protein envelopes), new polymerases, new glycoproteins. This is the part where it really starts to suck for the cell- the original viral antisense mRNA gets replicated many times, and then gets packed into the newly made viral particles. The viruses then lyse (kill) their host cell and then spread out an move on to a new cell. This takes about 20-30 minutes from fusion with the cell to lysis usually.
Both ortho- and para- myxovirus families respond to a characteristic test called hemagglutination, which is pretty much what it sounds like- a glycoprotein on the surface of the virus causes red blood cells to clump together. The major difference between the orthomyxoviridae and paramyxoviridae families is simply a matter of genome arrangement- ortho viruses like the influenzas have their genomes cut into several different smaller segments inside the virus, while the para viruses like measles, rinderpest, and our mystery illness have a single segment.
It should be stressed that genome comparisons are of limited help at the level of families- all the single-stranded antisense RNA viruses have pretty much the same structure, but they code for quite different glycoproteins (these are sugar-protein hybrid molecules on the surface of the virus). Glycoproteins are both the source of host recognition- they bind to specific receptors on a cell (these receptors are often, but not always, unique to the cells of a species)- and the agent that kills the cell. In the paramyxoviruses, remarkably these two functions (fusion and lysis) are carried out by two linked subunits on the same glycoprotein.
The variety of glycoproteins these RNA viruses have produced have made them incredibly diverse- they infect plants, animals, humans, they cause all manner of symptoms. The paramyxoviruses, for example, have members which result in mumps and measles, and then others that cause pneumonia. A closely related family (also ss antisense RNA) are the rhabdoviruses, some of which infect plants, and one of which causes rabies. Another antisense ssRNA family are the filoviruses, which tend to have rather toxic glycoproteins- members include Marburg and Ebola.
While it is a relief that the virus causing this deadly outbreak of pneumonia has been isolated, and catalogued in relation to other viruses, it should be noted that finding this relation may be of little use, given the nearly infinite variety displayed by even its closest relatives.
I totally agree. I was lucky enough to have science teachers in junior high and high school who emphasized hands-on learning. Textbooks can be a valuable resource, but they can't be used as a crutch. In most of my classes, textbooks were used to assign homework and practice problems, but the teaching was done by the teacher.
Of course, I think my teachers' decisions to not make much use of textbooks stemmed in part from the texts sucking pretty hard. Given their current state as a mishmash of facts written by committee, I'd say teaching science from only a middle-school science text would be like teaching English using only a dictionary. The facts are all present and accounted for, but the presentation is a bit dry. Personally, I think Joy Hakim's overhaul sounds like an excellent idea- there are some fascinating stories in science, and I think that they could greatly enrich the material.
A careful balance has to be struck, however, between these "stories" and academic rigor. On the one hand, I would argue that learning about how learning how Newton and Leibniz hated each other, for example, is not as important as learning about their independent discovery of the calculus. Any changes made to middle school science must keep in mind that some of the students passing through middle school will become our nation's next generation of scientists. I don't want to see kids get three years of touchy-feely science "stories" with no real science and then go on to get overrun in high school and college when they take hardcore "real" science courses. On the other hand, I had the honor of meeting distinguished physicist and Nobel laureate Leon Lederman acoupke weeks ago- he gave a talk about his efforts to reform science education at the high school level, actually- and he said something that made a lot of sense. He pointed out that the scientific way of thinking would certainly be a good thing for all citizens to have- it promotes a very healthy sense of skepticism. Thus, any attempt to modify science education must walk a fine line, catering to both future scientists and every other student. While I am a proponent of rigor in science education, I think it would be a damn shame to turn off otherwise bright, eager students from the joys of science on account of a boring textbook. We have to encourage the few, but in a modern world surrounded by science, we can't afford to alienate the many.
I wonder why the oldest history book we have says that the Egyptians Imprisoned the Jews for work; slavery.
I suppose none of the labor on the Pyramids was slave labor?
You suppose correctly, actually- the pyramids predate Israelite captivity by centuries- the pyramids at Giza were built 400-500 years before Abraham, actually. The Israelites built a number of storage cities for the pharaohs, but no major pyramids. Also, I'm assuming that when you write "the oldest history book we have" you mean the Bible, which is incorrect- there are extensive Sumerian, Babylonian, Egyptian, and Chinese historical records that all predate the writings of the Pentateuch.
The suitcase that serves as Reason's power supply and ammo dump is open on the deck next to him, its color monitor screen reading: Sorry, a fatal system error occured. Please reboot and try again.
-Neal Stephenson, Snow Crash
Well, they're footprints of a recent precursor to modern humans, Homo heidelbergensis, which is believed to be the forerunner of both H. neanderthalensis and H. sapiens There are some paleoanthropologists, however, who think that H. heidelbergensis (I just love that name) might only be the direct ancestor of Neanderthals and that the break between H. neanderthalensis and H. sapiens occurred earlier.
It is also interesting to note that these footprints indicate that they were made by beings which were approximately 4.5ft (1.5m) tall, though H. heidelbergensis remains suggest that adults of the species may have been as tall as 6 feet (1.9m). Thus, as the article suggests, these footprints may have been made by children- or they made be from a completely different hominid species.
In fact, the only thing I think they could use their tenuous logic to justify would be a hard drive. In that case, what if I build a computer with two drives?
Two hard drives? Of course you should get taxed twice- the only possible reason you'd need that much storage is to steal twice as much music!
1. You seem to think that this kid will have only one purpose in life, but in fact, he/she will have two: to save a sibling's life AND to live. If anything, this child has more purpose going for it than the thousands of children born every day because approximately nine months earlier their parents decided to chance it and not use contraception. This child cannot be a failure; even if its cord blood does not cure its sibling, it will still be a human child.
2. This is wildly unrealistic- that the parents would possess alleles for two different genetic ailments that can only be cured by sibling cord blood is extremely improbable. Yet, if it were to occur, and embryos could then be selected that possessed neither ailment (if any existed), and the funds for another round of IVF were available, then I see no reason to deny them the chance. If the couple is really that desperate, and you deny them IVF, it's likely that they might attempt to conceive a child "the old-fashioned way," taking the risk it would bear one or both disorders.
3. Looking at it in pragmatic (and harsh)terms first of all, why would you abort a fetus that cost so much money to conceive? Really, if you wanted to do this, you would not implant the embryo at all- you would simply convert it into a line of stem cells.
4. Huh? First off, the second kid does not even need to be alive to save its sibling's life- you said so yourself in #3. Second, how is the first kid "already dead?" If that were the case, everyone dying of a terminal illness would be legally dead.
5. Look, these parents aren't creating the ubermensch, or an Alpha. To call this a "designer baby" is inaccurate- this child would not be genetically modified in any way- all of its genes will come from its parents, who received them from their parents. A chance exists that the parents could "naturally" produce a child without this genetic defect- but not a very good one. Chance favors the prepared mind, and also the parents who were able to select an embryo with IVF.
6. Why must we kowtow to evolution? Rejecting the idea that producing children that will slowly and agonizingly die from an inherited disease is heaven working in mysterious ways and replacing it with the idea that we must let natural selection discard harmful alleles from the gene pool is merely replacing one tyranny with another. Fsck, at least God has a grand plan, or so I'm told. The examples you give of diseases that tie into our species' supposed genetic fitness decline are rather interesting- I'd say increases in the first four are much more the result of lifestyle choices than genetics (well, not if you mean Type I diabetes, I suppose) As far as asthma, I'd say that has to do more with pollution than genes. Allergies are rather interesting though- I'd suspect that in addition to environmental factors (including the pollution again), at least a small portion of that might be due to the spreading and interbreeding of long isolated groups of humans- thus spreading around genes for hypersensitivities. Anyway, the couple with a child with sickle-cell anemia raises an interesting point- this is the textbook case of a genetic disease that evolution built. Sickle-cell anemia has been known for thousands of years, and until recent advances (such as this cord blood therapy, for instance) was generally lethal at a relatively young age. However, it's stayed around mostly because it is a recessive disorder, and more importantly, the heterozygote (one copy of the normal "wild type" dominant gene and one defective sickle-cell recessive copy) has a resistance to infection by malaria. If this child survives, and then lives to procreate, it is likely that this heterozygote advantage will be conferred on them- that doesn't sound like enfeebling the human race to me.
7. Making this one shorter, I'm sure that's already been tried- many hospitals have set up cord blood donation programs- but a blood relation- particularly a sibling- stands an excellent chance of being a precise match.
8. Now, suppose this child were old enough to understand the present situation- what do you think the child would want? If the parents are willing to do all of this to save their child's life, it would seem that they hold that child to be rather precious. You can be cynical and claim that if the older child dies, he is merely being "replaced," but then the same is true for every other couple who wishes to conceive again after the death of a child. Surely they aren't being selfish?
Man, 22 billion years? I was hoping I could hold out until my protons decay (10^33 years, according to some supersymmetry models). On the other hand, the article does point out that the presence of dark energy makes stable, long-lived wormholes possible, thus enabling us to perhaps see more of the universe before its sudden and catastrophic end. Unfortunately, I suppose it may then be possible to lay waste to the universe manually by setting up bizarre time-traveling paradoxes that create loops in cause and effect. Dammned if you do...
Yeah, I don't know just how practical this setup would actually be out in the real world as far as biosensing. It's probably more suited to the next generation of laboratory gene chips, as you say. The Nature Materials paper of course says nothing about combating bioterror (it does mention the possible use of this technique in improved biosensors), so I think your "P.T. Barnum" comment may be right on target as far as the buzzword-laden but noninformative press release goes. Can't really blame the university from a public relations standpoint, as "Scientists create prototype for next-gen gene array" just doesn't have the same punch as "SCIENCE FIGHTS TERROR!" grandstanding.
The conclusions in this article make a lot of sense actually- the conditions in the solar system are in many ways similar to a chemical vapor deposition setup- very low pressure, almost no oxygen, and yet still plenty of material to use as both a vapor (carbon) and substrate (asteroids, comets, dust motes, etc.). I'd expect that these nanodiamonds are simply the result of carbon atoms coming together and clustering on a surface, with the carbon of course in conditions suitable for diamond formation. I would expect that nanoscale clusters of the other carbon allotropes, graphite and fullerenes, should be found in abundance in the asteroid belt as well.
This press release is rather short on information (read: no information), but the Nature Materials article itself is a bit more helpful. Now, my university is shelling out a bunch of cash for a site license, and I'm sure neither they nor Nature would like me to post that article here, so I will not do that. The abstract is free though:
Diamond, because of its electrical and chemical properties, may be a suitable material for integrated sensing and signal processing. But methods to control chemical or biological modifications on diamond surfaces have not been established. Here, we show that nanocrystalline diamond thin-films covalently modified with DNA oligonucleotides provide an extremely stable, highly selective platform in subsequent surface hybridization processes. We used a photochemical modification scheme to chemically modify clean, H-terminated nanocrystalline diamond surfaces grown on silicon substrates, producing a homogeneous layer of amine groups that serve as sites for DNA attachment. After linking DNA to the amine groups, hybridization reactions with fluorescently tagged complementary and non-complementary oligonucleotides showed no detectable non-specific adsorption, with extremely good selectivity between matched and mismatched sequences. Comparison of DNA-modified ultra-nanocrystalline diamond films with other commonly used surfaces for biological modification, such as gold, silicon, glass and glassy carbon, showed that diamond is unique in its ability to achieve very high stability and sensitivity while also being compatible with microelectronics processing technologies. These results suggest that diamond thin-films may be a nearly ideal substrate for integration of microelectronics with biological modification and sensing.
The method of attachment of DNA to a diamond surface is particularly clever: they use photochemistry to attach a long chain primary amine to the surface of the diamond, and then use a rather curious and complicated sulfur-containing organic molecule called SSMCC to act as a bridge between the diamond/amine and the strand of DNA. Essentially, you get these strands of DNA that point out into the environment like sticky threads. The sensing aspect, presumably (they don't go too much into it in the article - as the press release notes, they plan on discussing that in a meeting of the ACS) takes place as foreign DNAs contact the sensor. As the abstract tells us, the specificity of the attached DNA strands is not compromised by the diamond bonding technique, so the DNA strands can identify a certain complementary DNA sequence present in the enviroment, say, from Bacillus anthracis. Presumably the change induced in the diamond-bonded DNA that occurs when the complement hydrogen bonds with it will then trigger some sort of physically detectable action- you could tag the DNA with a fluorescent dye, for example, and measure how the fluorescence levels change between bonded and unbounded forms. This sort of information can then be translated into an electronic signal. This has a long ways to go before being a practical outside-the-lab type of device, but the results are still pretty exciting.
The problem with nuclear fusion is that it has been the classic example of a tech that's 50 years away- and it's been that way for the last 50 years. It's turned out to be a much more thorny problem than people anticipated- uncontrolled fusion reactions are fairly easy to produce after all- just direct the energy from a fission primary at an appropriate quantity of tritium. Unfortunately, this is a hydrogen bomb, and makes for a rather inefficient power source.
However, controlled confinement of plasma has proven to be much harder. ITER will use the most popular confinement method, a tokamak, which is a design devised by the Soviets (Tamm and Sakharov) back in the 1960s. So essentially, the basic plan is 40 years old, but there have been a number of obstacles- political and economic as well as technical to making this work. It will be interesting to see if their tokamak avoids the key problem of the design; in a tokamak, the plasma itself has an internal current running through it (as opposed to other designs like stellarators) and has proved rather deifficult to contain in the torus. I believe the Joint European Torus has had several "disruptions" of this sort that have lifted the several hundred ton vessel off its bolts. The good news, of course, is that such events (which are rare, and should be much more rare in a non-experimental reactor) are really the worst things that can happen to a fusion reactor. Although the plasma is extremely hot, it is not very dense at all (obtaining a critical density is really the greatest challenge) and thus there exists no possibility of 300 million Kelvin plasma vaporizing the container walls in some sort of runaway accident. Also, while they are not completely clean (no power generation method is) the radioactivity produced is low level, especially in comparision with fission reactor spent fuel rods.
First of all, there is little to no genetic basis for race- it's been pointed out that more genetic variation exists among the tribes of apes living in one river valley in Congo than exists among every human being on this planet. At some point in the history of our species, there was a bottleneck or founder effect, and nearly every homo sapiens is thus very nearly genetically identical.
;)
There is, however, an epidemiological basis for classifying humans into genetic groups that correspond to race- as chance would have it, groups of humans became isolated as they spread across the planet, creating founder effects that eventually led to distinct physical appearance. There are also distinct invisible genetic differences among races, and it would be foolish to ignore these in the name of political correctness- the higher incidence of Caucasians having cystic fibrosis genes, or Africans having sickle-cell or Ashkenazaic Jews having Tay-Sachs genes. Can these genetic traits extend into personality? Perhaps they can. However, while they get compared to blueprints, genes are really more like algorithms- iterative processes dependent on inputs, which can sometimes be completely random, or at least effectively so. Look at the case of cc, that cat clone- looks very little like the animal she was cloned from. Physical appearance is extremely complicated, with multiple genes acting in concert and in opposition with each other. Nurture of course also plays a role as well. Isn't it logical to assume that personality traits in humans will be at least as complicated? What genes do is chemistry, and can influence behavior and personality only in the sorts of ways that chemicals can. Look at the present psychopharmacopeia: antidepressants, tranquilizers, stimultants- but none of these change who you are.
However, referencing yout comment about being able to escape one's culture, I cannot wait until some team of researchers finds "the gene" that determines whether you are going to be more or less likely to try to rebel from your culture.
Nope, you meant moieties of the peptides, at least if you were indeed talking about protein folding. No problem though- it's evident what you're saying, and I wouldn't have even noticed until you pointed it out.
Come on! We are the ones who should be embracing this! Who's gonna convince Kamen to invent the Segway you really want? You know, the chariot version, that gets 5x the distance, and is 1/5 the price? It cannot get here by itself.
Now, I understand the "early-adopter" model of sales and everything,and that's fine. That tends to work because early adopters still end up with a product they want, and were willing to pay a premium for the utility and the cache of being first. However, you seem to be suggesting that we should support a product that we don't want so that a company can develop a product that we do want. If I'm going to be Dean Kamen's venture capitalist, I'd like to get more for my money than an 40 kg plastic scooter.
No, while the first organophosphate nerve agents were developed by the Germans in the years prior to WWII, including tabun, soman, and sarin, the most deadly (lowest LD50) nerve agent known, VX (o-ethyl methyl phosphonothiolate), was discovered by British scientists in the 1950s. The story I have heard is that the British then traded the process of VX synthesis to the Americans- for the details of building thermonuclear weapons.
All the nerve agents in this general class are rather nasty- tabun and soman were used by Iraq in their 1980-88 war against Iran, which the US cast a blind eye to (at the very least), and then they used them to kill Kurd and Shiite dissidents in Iraq itself afterward. Then in the mid-90s, the Japanese doomsday cult Aum Shinrikyo released sarin in several attacks, including in the Tokyo subway system in 1995, killing 12 and injuring 5000. If they had used a more sophisticated delivery system (they used sharpened umbrella tips to puncture bags of liquid sarin), it is likely the death toll would have been far larger.
A nerve agent attack on any populated area could be extraordinarily deadly, and would certainly carry the additional weight of psychological terror- the fear that the air you breathe is contaminated with an invisible killer. And VX in particular is extremely long-lived in most environments (by design) Contact with residue could lead to injuries and deaths long after the initial attack. However, the syntheses involved in making organophosphate nerve agents are nontrivial. They make relatively unlikely terrorist agents simply because there are so many easier ways to kill and terrorize people- mustard, chlorine, phosgene, as well as biological agents like anthrax, botulin toxin, or a hemorrhagic fever virus. The feds seem so concerned about smallpox, for whatever reason, when the nations that have had Ebola outbreaks (Congo, Cote D'Ivoire, and Sudan) are in so much political chaos that setting up a lab and collecting and amplifying virus appears quite possible (whereas the only known smallpox stocks in the world are being kept in cold storage in Russia and the US).
I don't believe that much of this sort of information should be kept secret. I realize I know quite a bit about bioterror for a private citizen- but I'm not planning on becoming a terrorist- quite the opposite. I didn't obtain any knowledge from breaking into a top secret lab or kidnapping a scientist or cracking into a database anyway. As with many things, knowing how to defeat a threat involves understanding the threat (compare to computer security). Terrorists already know how to kill people- the information published in scientific journals is what's going to stop them. Secret government labs are of course going to be a large part of our nation's defense, as they have been for decades. However, the free exchange of information among labs holds the promise that discoveries could be made much more quickly.