Well, presumably, all that would be used for nanomachinery is the "motor" of the sperm, just the flagellum and the glycolytic machinery to power it. Those pieces are nearly pure protein, and should be fairly hardy in a biological environment, and could perhaps be engineered to be more so.
The reason sperm die so quickly is simply that they've been pared down to the essentials of independent survival, and are so tailored to their mission that additional survival measures would probably make them less fit at their task. A sperm is just a biological torpedo, with a warhead of tightly packed DNA up front and a powerful propeller in back. Survival of the genes of a given sperm means winning the race to the egg, and it appears that slow and steady does not really stand a chance in this race.
In terms of evolutionary success, the advantage of making hardy sperm cells that could live for weeks in the Fallopian tubes, waiting patiently for an egg to arrive, is just overwhelmed by the strategy of rushing 200 million fragile little zerglings up the pipe. And with such fragility, it's actually preferable that older sperm die, since the odds are that those sperm would incur considerable DNA damage during their extended stay.
If you want "pictures" of atoms, images from scanning tunneling microscopes should suffice. IBM's Almaden Research Center has a nice gallery of micrographs- this one is probably my favorite.
Experts suggest security-conscious consumers consider the Western Electric 500 for their next smartphone. Lacking Java, JavaScript, ActiveX, and any other type of software, its spartan phone interface makes it virtually immune to any security vulnerabilities, and its innovative "rotary dial" system circumvents attacks possible on touch-tone phones. The casing is constructed of nearly indestructible Bakelite plastic, making it far more durable than the average smartphone. It does however require a service agreement with AT&T.
I think the congressman was trying to make analogy to a quote by Gen. Omar Bradley, "Ours is a world of nuclear giants and ethical infants." Really, the metaphor actually works better with Lantos's formulation, but Bradley's formulation wisely recognizes that using one of the terms which describes a short stature adult would place that term, and thus the group associated with it, in a pejorative light.
Yeah, the essay tries way too hard to shoehorn Gordon Freeman into the notion of the "rough beast" of "The Second Coming." Now, one nice thing about a silent protagonist in a video game is that all manner of feelings and motivation can be projected onto Freeman by the player. Perhaps Freeman is a bit bemused and cynical about the adoration heaped on him by the human resistance, knowing himself to be the puppet of larger forces. Comparing Freeman to the sphinx-like juggernaut of "The Second Coming" is stretching it a bit though.
If anything, the point of this essay would have been made far more effectively by comparing Freeman to a more traditional heroic/messianic figure. The apocalyse Yeats describes is not about the final triumph of good over evil, but the end and beginning of historical eras, punctuated by a moment of destruction and revelation. The "rough beast" isn't interested in saving anyone, as evidenced by its "gaze blank and pitiless as the sun." It is a god of destruction, one that could be described as great and terrible, but not evil as Yeats saw it, since the annihiliation would precipitate rebirth. If there is a character in the Half-Life series that resembles this, it might be the G-Man, who is clearly willing to spread chaos and destruction to achieve his (or his employers') mysterious goals.
Gordon Freeman, on the other hand, hews more closely to the epic hero type in literature- a comparison to Beowulf, whose story is more about saving innocent people from monsters, would have been fitting. YIt unfortunately seems though that the author of this essay got fixated somehow on comparing Half-Life 2 to this Yeats poem, and instead of abandoning the notion, decided to keep trying to make it work.
The cash grant amounts associated with the Nobel Prizes have an interesting history- the foundation wasn't granted tax-exempt status until 1946, so for some of its early years, the tax assessment on the fund exceeded the total worth of that year's prizes. That, combined with orginally very conservative investment rules, caused the nominal value of the cash grants to stagnate, and the real value against inflation to plummet.
After getting tax-exempt status and easing their investment rules, the fund began to grow exponentially, and in both nominal and real terms, the current monetary award is larger than it's ever been. Here is a listing and chart of how that amount has changed over time.
I was in complete agreement with the parent on the subject of the processing time- I figured 25 minutes could only possibly be the figure if PCR were unnecessary, as I considered 25 minutes to be quite impressive for just running the gel and the STR analysis. Then I looked at the Pink Tentacle post that the "article" blog post cites (the original NEC press release
is in Japanese). According to Pink Tentacle's summary, PCR is part of the process, and from start to finish is under 25 minutes.
Now, I've been away from molecular bio for a few years, so I was curious to know if this sort of speed was even remotely possible. I mean, I remember this whole process requiring a pretty solid afternoon's worth of work at minimum- and depending on the circumstances, often involved setting stuff up to run overnight. Having Googled "fastest PCR" and having found this paper, I have to admit NEC might not be full of crap about this.
Basically, they find workarounds for all the time-intensive steps in the analysis. DNA extraction? They add proteinase K and guanidine to whole blood, then put it through a solid-phase extraction that they say takes only 6 minutes.
For PCR, there's really only so far you can go to speed things up due to limits imposed by reaction kinetics, but the tiny sample size allows them to run through each temperature station in a couple seconds (it should be noted that the fragments they're replicating are only about 200 base pairs).
The separation by electrophoresis is where the magic really happens. See, the parent and I were thinking about how this is usually done, by moving a band of DNA across a slab of polyacrylamide or agarose gel. The setup is labor-intensive, and as the parent notes, it does take awhile for the gel to run to completion They instead do high voltage capillary electrophoresis- and their capillaries are channels etched into a glass chip. Fluorescent intercalating dye was present in the sieving matrix, and detection was done with laser-induced fluorescence- no Southern blot. Everything runs on a single chip, and in 25 minutes goes from bodily fluids to genetic fingerprinting.
I know there's been a lot of hype about "lab-on-a-chip" systems and what the future holds. What's mentioned in this Dec. 2006 paper is of course a research proof-of-concept system- if you look at their PCR setup, their "thermal control system" is a heat lamp and cooling fan controlled by a laptop. A year later, is NEC about to debut a 25 minute DNA lab-on-a-chip as a commercial product? I don't know, but I no longer think the idea is as crazy as it sounds.
Well, according this earlier abstract by the same group (the paper from two years ago where they originally propose the dye- the paper linked to the article is really just about using X-ray crystallography to study the structure of the dye/urea nitrate complex):
Urea itself, which is the starting material for urea nitrate, does not react with p-DMAC under the same conditions. Other potential sources of false positive response e.g., common fertilizers, medications containing the urea moiety and various amines, do not produce the red pigment with p-DMAC. Exhibits collected from 10 terrorist cases have been tested with p-DMAC. The results were in full agreement with those obtained by instrumental techniques including GC/MS, XRD and IR.
From what I know of the chemistry of aldehydes (there's a great icebreaker at parties...), this dye should react with any primary or secondary amine- like regular old urea, ammonia, amino acids, etc. What this group claims, however, is that there is a particular color change reaction for this dye which occurs for urea nitrate which does not occur for other amines.
I think what the article's confusing picture of the dye and urea nitrate interacting is suggesting is that the hydrogen bonds between the nitrate and urea moieties remain intact even after the urea has bonded to the dye, so the nitrate moiety affects the dye complex and the color it appears. I'd still be concerned about false positives, personally, particularly from different amine salts. The color produced might be uniquely identifiable to a spectrophotometer, but for a visual test I'd be worried about anything that turns "reddish" enough to produce a false positive.
I'd hope no one thinks about massively aerosolizing this stuff (like spraying it throughout an airport to find terror suspects). From this Material Safety Data Sheet for para-dimethylaminocinnamaldehyde, the dye in question: Potential Acute Health Effects: Hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation. That's why what's suggested in the article is to sample a suspect through swabbing, then testing the swab- not spraying directly on people.
In addition, as both an amine and an aldehyde, I'm willing to bet this stuff has a very strong odor.
On the subject of Wikipedia, the authors of this paper actually use Wikipedia on page 9 of their paper to provide a definition of a quantum computer. (They don't bother with a full citation like they use for their other sources though.)
While this is just a thought experiment, I think their use of interferometry to solve problems is pretty interesting, since it really is in some respects quantum computing. While, as they note, it isn't a quantum computer in the usual sense with entanglement and qubits, their method does, after all, depend on light following Fermat's Principle of Least
Time, which in turn can be considered a consequence of quantum electrodynamics. It makes me wonder what other sorts of computational problems can be solved using invariant properties of the physical world.
Wrong movie. They're building one of the supercomputers in Urbana, Illinois, which means that the HAL Plant must finally be operational, just a few years behind schedule.
Gibson and his predictions fare a lot better in the more recent Pattern Recognition. (I personally think his writing style has actually improved over time as well). There's a lot he gets right about marketing and media in the near future (which would be around now, I guess), and for a book where the September 11th attacks are critical to the plot, the narrative has held up pretty well, particularly in comparison to the certain Big Important Novels which tried to make them the framing device for this generation's White Noise or The Tin Drum.
Of course, comparing Pattern Recognition to something like Neuromancer is really the key to what Gibson is arguing about science fiction. Being speculative about technology far ahead of the present is naturally a recipe for failure. I didn't start reading books like Neuromancer and Snow Crash until about 2000 or so, and while I enjoyed them immensely, most of their predictions had long since become laughable. The authors of cyberpunk novels in the 1980s and early 1990s correctly sensed that the relationship between humans and computers was on the cusp of major change, but virtually all of them put their money down on sophisticated AIs and immersive virtual realities which haven't come to pass. As Gibson notes in his interview, "If I were a smart 12-year-old picking up Neuromancer for the first time today I'd get about 20 pages in and I'd think 'Ahhaa I've got it - what happened to all the cell phones? This is a high-tech future in which cellular telephony has been banned'."
Now, some of this, I think, just happened to be bad timing- no one writing in 1987 could be expected to accurately forecast 2007. However, rather being outstripped by a vertical asymptote of progess as the technological singularity idea suggests,the collapse of the Soviet bloc and the creation of the Web in particular represent "jump discontinuities" in the timeline. Earlier today, I was reading about Arthur C. Clarke's Space Odyssey series on Wikipedia. The political and technological changes which occurred in between the releases of novels in 1968, 1982, 1987, and 1997 were so great as to cause Clarke to state that each work in the series is on a seperate timeline (2061 still has the USSR around in its title year, while in 3001 it fell back in 1991).
I think that even if we don't have a Singularity, we will still have events of such significance every few years which alter the course of history in ways that will only be obvious in hindsight and which will make speculation further than a couple years ahead very difficult indeed. And I suppose if we truly are on the run up to a Singularity, it won't be too long before predicting further than a couple days into the future becomes a fool's errand So, Mr. Gibson has a point. However, I'd suggest that's just part of the fun of science fiction- books from the 60s suggesting we'd be living in space in the year 2000 but using computers the size of houses, books from the early 1990s about computer hackers of the early 21st century as virtual reality ninjas. In these best examples of these, the story is entertaining enough that it didn't matter that the visions of the future (now the present) didn't pan out.
First off, organic photovoltaics based on polythiophene have been around for a few years now; it's a very promising technology, but for now the energy conversions seen are around 5% at best. That of course may be suitable if these things can be made cheaply enough to be installed everywhere.
This discovery builds on experiments using fullerenes and their derivatives as electron acceptors for organic semiconductors like polythiophene, and the use of a carbon nanotube a a molecular wire to cart away electrons may indeed represent significant improvement over the acceptors currently in use- not likely enough to bring it in range of good silicon photovoltaics, but since I can't read the full text of that article, I can't say for sure. The problem I see with this particular new idea is that in comparison to the organic photovolts out there now, it more than likely would strike a poor balance between increased performance and increased price- high purity single walled nanotubes are still in the hundreds of dollars per gram range, after all.
That's the first thing that came to my mind when I read the summary. I think the notion is that airbags couldn't be deployed in the same sort of system used for the last few Mars rover projects, with a stately tetrahedron of cushions surrounding the rover package. If you've seen any of the NASA CGI dramatizations of what happens in these rover landings, these packages seem to hit pretty hard, and bounce wildly in all directions and orientations before settling to a stop.
I'm guessing the notion here is that sort of landing would be decidedly unpleasant, and probably dangerous to a human crew. That being said, I don't see why an airbag system couldn''t at least be a component of a manned craft landing system- just provide a margin of impact cushioning, rather than the bouncing and tumbling. It certainly would seem easier to land a craft on a shield of airbags than on thin legs like the moon landers.
That's not necessarily true- there are quite a few ways bacteria have become resistant to drugs- because there are quite a few different drug targets scientists have tried.
Before even penicillin, there were the miraculous sulfa drugs, which block a bacteria's ability to make folic acid: bacteria learned to uptake folate just as we do.
Beta-lactams like penicillin prevent bacteria from making peptidoglycan, the material of their cell walls: bacteria came up with beta-lactamase to break it down.
Better beta-lactams like oxacillin and methicillin were developed to be more effective at killing bacteria before lactamase neutralized them: mutant forms of proteins involved in making peptidoglycan (and were resistant to binding lactam drugs) began to proliferate, and now we of course have Methicillin Resistant Staphylococcus Aureus to deal with. (And studies have shown that MRSA bacteremia is just as deadly as regular SA, even correcting for the fact that MRSA tends to hit hospital patients. The rise in community-associated MRSA suggests it can fend for itself in the wild as well.)
Quinolones attack bacterial topoisomerases, the enzymes they use to wind and unwind DNA: mutant topoisomerases beat these.
Macrolides (most of the -mycin family) and oxazolidones bind to bacterial ribosomes to stop protein translation: modified ribosomal subunits beat these.
Vancomycin prevents peptidoglycan formation in by preventing incorporation of the monomers that make it up: modified monomers, and now we see VRSA.
We keep finding new targets for antibiotics, but as the Red Queen said, "It takes all the running you can do, to keep in the same place."
Actually, it would be unwise to prescribe these drugs recklessly for another reason- the bisphosphonates, the class of compounds which these two drugs belong to, can have a rather serious side effect when taken in high doses for long periods. Bisphosphonates taken in high doses for long periods can cause osteonecrosis of the jaw, though it should be noted that etidronate and clodronate are older drugs with far less potency than newer drugs in the class like alendronate and zoledronic acid.
Superconductors have a critical applied magnetic field associated with them, above which they are no longer superconducting. An external magnetic field stronger than the critical value tears apart Cooper pairs, making them behave as single electrons with their boring old regular current. An advantage to Type II superconductors (like the niobium alloys often used in very high field magnets) is that they generally can withstand higher applied fields than Type I superconductors because they can function in a mixed mode of normal and supercurrent.
Magnetic levitation in superconductors occurs due to the Meissner-Ochsenfeld effect, which is slightly different than what the parent describes. The parent's memory may well not be faulty, however, as the Meissner effect is often erroneously explained in terms of perfect diamagnetism and Faraday's Law of Induction. While it is true that as a perfect conductor, a superconductor is also a perfect diamagnet, and can be expected to generate an opposing electromagnetic field in response to a changing magnetic flux through it, a superconductor also opposes a constant field.
This can be demonstrated by placing a magnet on top of a superconductor above its critical remperature, then cooling the superconductor below the critical temperature. When the superconductor hits the critical temperature, the applied field from the magnet will be expelled out to the London depth (about 50 nanometers in most superconductors), and the magnet will levitate. It's a subtle difference from the perfect diamagnetism explanation, but it was one of the key clues that led to the explanation of superconductivity as a phase transition and as a nonclassical process.
Actually, that's the price for a troy ounce, which still holds on as the customary unit for precious metals. There are 12 ounces troy in a troy pound (which is the same pound as in the currency pound sterling- it was originally defined as one troy pound of sterling silver) . For reference, a troy ounce is about 31 grams while an avoirdupois ounce (the 1/16 of a lb. ounce) is about 28 grams.
There is an Ice-IX, but it only exists at a combination of very low temperature (less than 140K) and very high pressure (~300MPa). Raise the temperature, and there will be a conversion to another polymorph of ice (or to liquid water). This site has some good information on the phases of water, especially the ice polymorphs.
True, but many types of microorganisms are hardy enough to withstand the conditions of space-and not just exotic ones, either. Bacterial endospores (like from Clostridium and Bacillus bacteria, for instance) can be exceptionally tough, and they can preserve DNA in a dormant state pretty much indefinitely. And the famous extremophile Deinococcus radiodurans can at least intermittently withstand irradiation at 5000 gray- about a thousand times the dose sufficient to kill a person.
Well, this case is primarily interesting in the sense of "this thing that very rarely happens, it just happened." The main scientific benefit is that further light is shed on the mechanisms of human reproduction. Obviously, the outlines of that process are well-known, but there's still a lot of uncharted territory when it comes to the non-normal functioning on this process. Reproductive biology is an area where animal models (even in other primates) tend to translate rather poorly to human beings, and is of course also an area with ethical limits on human experimentation. Conceivably, learning about cases like this can advance knowledge about things like infertility and birth defects.
There's actually an interesting story, almost the flip side of this rare case in humans, running now in the New York Times about marmosets, in which a form of chimerism is quite widespread:
One of the most surprising results of the study is that over half of male marmosets have chimeric sperm. Dr. Ross and her colleagues discovered cases in which the DNA of male marmosets turned up in babies supposedly fathered by their fraternal twins. In other words, the sperm came from one male, but it had the DNA of the male's brother. A paternity test would show that the baby's genetic father was actually its uncle. The scientists were not able to isolate DNA from marmoset eggs, but they did find that 2 out of 21 marmoset ovaries were chimeric. It's possible that a female marmoset can give birth to nephews and nieces.
Slashdot Mirror
Zed's dead, baby. Zed's dead.
The reason sperm die so quickly is simply that they've been pared down to the essentials of independent survival, and are so tailored to their mission that additional survival measures would probably make them less fit at their task. A sperm is just a biological torpedo, with a warhead of tightly packed DNA up front and a powerful propeller in back. Survival of the genes of a given sperm means winning the race to the egg, and it appears that slow and steady does not really stand a chance in this race.
In terms of evolutionary success, the advantage of making hardy sperm cells that could live for weeks in the Fallopian tubes, waiting patiently for an egg to arrive, is just overwhelmed by the strategy of rushing 200 million fragile little zerglings up the pipe. And with such fragility, it's actually preferable that older sperm die, since the odds are that those sperm would incur considerable DNA damage during their extended stay.
If you want "pictures" of atoms, images from scanning tunneling microscopes should suffice. IBM's Almaden Research Center has a nice gallery of micrographs- this one is probably my favorite.
Experts suggest security-conscious consumers consider the Western Electric 500 for their next smartphone. Lacking Java, JavaScript, ActiveX, and any other type of software, its spartan phone interface makes it virtually immune to any security vulnerabilities, and its innovative "rotary dial" system circumvents attacks possible on touch-tone phones. The casing is constructed of nearly indestructible Bakelite plastic, making it far more durable than the average smartphone. It does however require a service agreement with AT&T.
I think the congressman was trying to make analogy to a quote by Gen. Omar Bradley, "Ours is a world of nuclear giants and ethical infants." Really, the metaphor actually works better with Lantos's formulation, but Bradley's formulation wisely recognizes that using one of the terms which describes a short stature adult would place that term, and thus the group associated with it, in a pejorative light.
If anything, the point of this essay would have been made far more effectively by comparing Freeman to a more traditional heroic/messianic figure. The apocalyse Yeats describes is not about the final triumph of good over evil, but the end and beginning of historical eras, punctuated by a moment of destruction and revelation. The "rough beast" isn't interested in saving anyone, as evidenced by its "gaze blank and pitiless as the sun." It is a god of destruction, one that could be described as great and terrible, but not evil as Yeats saw it, since the annihiliation would precipitate rebirth. If there is a character in the Half-Life series that resembles this, it might be the G-Man, who is clearly willing to spread chaos and destruction to achieve his (or his employers') mysterious goals.
Gordon Freeman, on the other hand, hews more closely to the epic hero type in literature- a comparison to Beowulf, whose story is more about saving innocent people from monsters, would have been fitting. YIt unfortunately seems though that the author of this essay got fixated somehow on comparing Half-Life 2 to this Yeats poem, and instead of abandoning the notion, decided to keep trying to make it work.
Nah, Colossus has his own form of magnetoresistance.
After getting tax-exempt status and easing their investment rules, the fund began to grow exponentially, and in both nominal and real terms, the current monetary award is larger than it's ever been. Here is a listing and chart of how that amount has changed over time.
Now, I've been away from molecular bio for a few years, so I was curious to know if this sort of speed was even remotely possible. I mean, I remember this whole process requiring a pretty solid afternoon's worth of work at minimum- and depending on the circumstances, often involved setting stuff up to run overnight. Having Googled "fastest PCR" and having found this paper, I have to admit NEC might not be full of crap about this.
Basically, they find workarounds for all the time-intensive steps in the analysis. DNA extraction? They add proteinase K and guanidine to whole blood, then put it through a solid-phase extraction that they say takes only 6 minutes.
For PCR, there's really only so far you can go to speed things up due to limits imposed by reaction kinetics, but the tiny sample size allows them to run through each temperature station in a couple seconds (it should be noted that the fragments they're replicating are only about 200 base pairs).
The separation by electrophoresis is where the magic really happens. See, the parent and I were thinking about how this is usually done, by moving a band of DNA across a slab of polyacrylamide or agarose gel. The setup is labor-intensive, and as the parent notes, it does take awhile for the gel to run to completion They instead do high voltage capillary electrophoresis- and their capillaries are channels etched into a glass chip. Fluorescent intercalating dye was present in the sieving matrix, and detection was done with laser-induced fluorescence- no Southern blot. Everything runs on a single chip, and in 25 minutes goes from bodily fluids to genetic fingerprinting.
I know there's been a lot of hype about "lab-on-a-chip" systems and what the future holds. What's mentioned in this Dec. 2006 paper is of course a research proof-of-concept system- if you look at their PCR setup, their "thermal control system" is a heat lamp and cooling fan controlled by a laptop. A year later, is NEC about to debut a 25 minute DNA lab-on-a-chip as a commercial product? I don't know, but I no longer think the idea is as crazy as it sounds.
From what I know of the chemistry of aldehydes (there's a great icebreaker at parties...), this dye should react with any primary or secondary amine- like regular old urea, ammonia, amino acids, etc. What this group claims, however, is that there is a particular color change reaction for this dye which occurs for urea nitrate which does not occur for other amines.
I think what the article's confusing picture of the dye and urea nitrate interacting is suggesting is that the hydrogen bonds between the nitrate and urea moieties remain intact even after the urea has bonded to the dye, so the nitrate moiety affects the dye complex and the color it appears. I'd still be concerned about false positives, personally, particularly from different amine salts. The color produced might be uniquely identifiable to a spectrophotometer, but for a visual test I'd be worried about anything that turns "reddish" enough to produce a false positive.
In addition, as both an amine and an aldehyde, I'm willing to bet this stuff has a very strong odor.
While this is just a thought experiment, I think their use of interferometry to solve problems is pretty interesting, since it really is in some respects quantum computing. While, as they note, it isn't a quantum computer in the usual sense with entanglement and qubits, their method does, after all, depend on light following Fermat's Principle of Least Time, which in turn can be considered a consequence of quantum electrodynamics. It makes me wonder what other sorts of computational problems can be solved using invariant properties of the physical world.
Wrong movie. They're building one of the supercomputers in Urbana, Illinois, which means that the HAL Plant must finally be operational, just a few years behind schedule.
...We love no other,
So let our motto be
Victory, Illinois! Varsity!
Of course, comparing Pattern Recognition to something like Neuromancer is really the key to what Gibson is arguing about science fiction. Being speculative about technology far ahead of the present is naturally a recipe for failure. I didn't start reading books like Neuromancer and Snow Crash until about 2000 or so, and while I enjoyed them immensely, most of their predictions had long since become laughable. The authors of cyberpunk novels in the 1980s and early 1990s correctly sensed that the relationship between humans and computers was on the cusp of major change, but virtually all of them put their money down on sophisticated AIs and immersive virtual realities which haven't come to pass. As Gibson notes in his interview, "If I were a smart 12-year-old picking up Neuromancer for the first time today I'd get about 20 pages in and I'd think 'Ahhaa I've got it - what happened to all the cell phones? This is a high-tech future in which cellular telephony has been banned'."
Now, some of this, I think, just happened to be bad timing- no one writing in 1987 could be expected to accurately forecast 2007. However, rather being outstripped by a vertical asymptote of progess as the technological singularity idea suggests,the collapse of the Soviet bloc and the creation of the Web in particular represent "jump discontinuities" in the timeline. Earlier today, I was reading about Arthur C. Clarke's Space Odyssey series on Wikipedia. The political and technological changes which occurred in between the releases of novels in 1968, 1982, 1987, and 1997 were so great as to cause Clarke to state that each work in the series is on a seperate timeline (2061 still has the USSR around in its title year, while in 3001 it fell back in 1991).
I think that even if we don't have a Singularity, we will still have events of such significance every few years which alter the course of history in ways that will only be obvious in hindsight and which will make speculation further than a couple years ahead very difficult indeed. And I suppose if we truly are on the run up to a Singularity, it won't be too long before predicting further than a couple days into the future becomes a fool's errand So, Mr. Gibson has a point. However, I'd suggest that's just part of the fun of science fiction- books from the 60s suggesting we'd be living in space in the year 2000 but using computers the size of houses, books from the early 1990s about computer hackers of the early 21st century as virtual reality ninjas. In these best examples of these, the story is entertaining enough that it didn't matter that the visions of the future (now the present) didn't pan out.
This discovery builds on experiments using fullerenes and their derivatives as electron acceptors for organic semiconductors like polythiophene, and the use of a carbon nanotube a a molecular wire to cart away electrons may indeed represent significant improvement over the acceptors currently in use- not likely enough to bring it in range of good silicon photovoltaics, but since I can't read the full text of that article, I can't say for sure. The problem I see with this particular new idea is that in comparison to the organic photovolts out there now, it more than likely would strike a poor balance between increased performance and increased price- high purity single walled nanotubes are still in the hundreds of dollars per gram range, after all.
I'm guessing the notion here is that sort of landing would be decidedly unpleasant, and probably dangerous to a human crew. That being said, I don't see why an airbag system couldn''t at least be a component of a manned craft landing system- just provide a margin of impact cushioning, rather than the bouncing and tumbling. It certainly would seem easier to land a craft on a shield of airbags than on thin legs like the moon landers.
Before even penicillin, there were the miraculous sulfa drugs, which block a bacteria's ability to make folic acid: bacteria learned to uptake folate just as we do.
Beta-lactams like penicillin prevent bacteria from making peptidoglycan, the material of their cell walls: bacteria came up with beta-lactamase to break it down.
Better beta-lactams like oxacillin and methicillin were developed to be more effective at killing bacteria before lactamase neutralized them: mutant forms of proteins involved in making peptidoglycan (and were resistant to binding lactam drugs) began to proliferate, and now we of course have Methicillin Resistant Staphylococcus Aureus to deal with. (And studies have shown that MRSA bacteremia is just as deadly as regular SA, even correcting for the fact that MRSA tends to hit hospital patients. The rise in community-associated MRSA suggests it can fend for itself in the wild as well.)
Quinolones attack bacterial topoisomerases, the enzymes they use to wind and unwind DNA: mutant topoisomerases beat these.
Macrolides (most of the -mycin family) and oxazolidones bind to bacterial ribosomes to stop protein translation: modified ribosomal subunits beat these.
Vancomycin prevents peptidoglycan formation in by preventing incorporation of the monomers that make it up: modified monomers, and now we see VRSA.
We keep finding new targets for antibiotics, but as the Red Queen said, "It takes all the running you can do, to keep in the same place."
Actually, it would be unwise to prescribe these drugs recklessly for another reason- the bisphosphonates, the class of compounds which these two drugs belong to, can have a rather serious side effect when taken in high doses for long periods. Bisphosphonates taken in high doses for long periods can cause osteonecrosis of the jaw, though it should be noted that etidronate and clodronate are older drugs with far less potency than newer drugs in the class like alendronate and zoledronic acid.
In honor of Leon Lederman, /. just sent a massive muon neutrino pulse to the Symmetry Magazine servers.
Magnetic levitation in superconductors occurs due to the Meissner-Ochsenfeld effect, which is slightly different than what the parent describes. The parent's memory may well not be faulty, however, as the Meissner effect is often erroneously explained in terms of perfect diamagnetism and Faraday's Law of Induction. While it is true that as a perfect conductor, a superconductor is also a perfect diamagnet, and can be expected to generate an opposing electromagnetic field in response to a changing magnetic flux through it, a superconductor also opposes a constant field.
This can be demonstrated by placing a magnet on top of a superconductor above its critical remperature, then cooling the superconductor below the critical temperature. When the superconductor hits the critical temperature, the applied field from the magnet will be expelled out to the London depth (about 50 nanometers in most superconductors), and the magnet will levitate. It's a subtle difference from the perfect diamagnetism explanation, but it was one of the key clues that led to the explanation of superconductivity as a phase transition and as a nonclassical process.
Actually, that's the price for a troy ounce, which still holds on as the customary unit for precious metals. There are 12 ounces troy in a troy pound (which is the same pound as in the currency pound sterling- it was originally defined as one troy pound of sterling silver) . For reference, a troy ounce is about 31 grams while an avoirdupois ounce (the 1/16 of a lb. ounce) is about 28 grams.
There is an Ice-IX, but it only exists at a combination of very low temperature (less than 140K) and very high pressure (~300MPa). Raise the temperature, and there will be a conversion to another polymorph of ice (or to liquid water). This site has some good information on the phases of water, especially the ice polymorphs.
True, but many types of microorganisms are hardy enough to withstand the conditions of space-and not just exotic ones, either. Bacterial endospores (like from Clostridium and Bacillus bacteria, for instance) can be exceptionally tough, and they can preserve DNA in a dormant state pretty much indefinitely. And the famous extremophile Deinococcus radiodurans can at least intermittently withstand irradiation at 5000 gray- about a thousand times the dose sufficient to kill a person.
There's actually an interesting story, almost the flip side of this rare case in humans, running now in the New York Times about marmosets, in which a form of chimerism is quite widespread: