Not quite: it's more interesting than that. The Nature Biotechnology paper referenced in TFA goes into more detail.
A simple version: the anthrax bacterium makes a particular protein complex - the anthrax toxin - that disrupts cell membranes. This toxin has seven-fold symmetry, meaning that it is made up of seven identical subunits. There are various peptides that bind to each subunit and inhibit the anthrax toxin, thereby protecting cells.
What this group has done is to make liposomes (fat globules, not antibodies) with different concentrations of these peptides on the surface. When the density of inhibitory peptides on the liposomes roughly matches the density of target sites (one on each of the seven subunits) on the anthrax toxin, the inhibition is much more efficient. (This means you need much less of the peptide to protect cells.)
This general idea - of putting lots of inhibitory agents on one particle or compound - has been done before. The big advance here is that this is an easy way control the number & density of the inhibitors. Pretty slick.
That damn sundial taunts me every time I walk past it. I walk past it on my way back from work every day, and on the few days the sun hasn't set, it's invariably overcast. Maybe some day I'll be able to tell the time without having to look at my wristwatch.
<farnsworth>A man can dream, can't he? A man can dream...</farnsworth>
Indian mythology does include a city that was submerged - Dwaraka - but this is completely different from Atlantis because a) it was a coastal city, not an island b) there's a modern city called Dwaraka, more or less where the Mahabharata says Dwaraka is supposed to be c) there are a bunch of submerged ruins near modern Dwaraka* Which leads to the hypothesis that there was once a historical city, which submerged due to rising sea levels/land subsidence/other geological weirdness, whose inhabitants resettled nearby. No resorting to missing continents or racial memory or UFOs.
I'm a TA for a course that meets in Kane Hall this quarter. I can verify that the Kane Hall wireless mike is, in fact, a lapel mike tethered to a transmitter clipped onto your belt.
Very useful for subduing undergrad biochemistry students...
Given that they've just started (in sunny California), my guess is they'll be pumping iron and groping each other. And marrying into the Kennedy family.
...just like electric charge. Microsoft is +10 AlwaysWinning(TM) Evil, while Amazon and Disney are both -5 OppressiveIP Evil. However note that by the Slashdot conventions, Microsoft is always twice as evil as any other company. Thus when Amazon, Disney and MS collaborate, all their evil cancels out and we can root for them.
Note that any branch of the government, the MPAA/RIAA etc. is -20 OppressiveIP Evil, twice as evil as MS, and so we can never root for them.
That's a rather Newtonian viewpoint; it was already 50 years out of date by the time Asimov wrote Foundation.
A quantum-mechanical universe precludes being able to observe or predict the universe in infinite detail. However we can still make useful predictions about the universe (and smaller systems).
We do this by estimating probabilities that a quantum mechanical system will enter one of a number of states, and using a sample size large enough that essentially the most likely outcome always happens.
This hand-waving lets us make rigorous mathematical predictions about substances and objects that can be verified - such as "At 100 Celsius and atmospheric pressure, water will boil." And by George, it works!
Psychohistory was intended to be exactly analogous to thermodynamics. Both sciences study particles whose individual behavior cannot be predicted, and both are inherently based on statistical mechanics.
Now thermodynamics only works because the number of particles in any real-world system is so mindnumbingly large. If we tried to predict the behavior of only (!) a million or a billion particles, you're right, the errors would add up pretty quickly. But by using a sufficiently large sample size, we give the system so many states that deviations from the average become essentially neglible.
When Asimov conceived of psychohistory, one of the most important characteristics of the science was that the sample size needed to be inconceivably large - quadrillions of people spread over half a million worlds. IIRC, this was in fact one of Hari Seldon's first postulates. (The second was that the people in the system could not be allowed to learn that their actions were predictable.)
Also consider that psychohistory was not used primarily to predict the actions of the Foundation: the sample size was too small and the Foundationers knew they were being tampered with. Psychohistory was used instead to analyze the future of the Empire in general and the barbarian kingdoms of the periphery in particular.
As you might have guessed I'm a big fan of the books and all of Asimov's writings. His writing style was not what you would call sublime, but you can't beat his production of great ideas and well-conceived universes.
He talks about the descendants of Algol and Fortran merging, and then has a throwaway line about that never having happened to actual species. I think it's interesting that something like that has probably occurred at least twice in the history of life.
Mitochondria and chloroplasts are two of the most complicated organelles, cellular machinery found in complex organisms. Chloroplasts, found in the cells of higher plants, carry out photosynthesis, converting solar energy to food (glucose). Mitochondria are found in both animals and plants, and use oxygen to extract energy from nutrients. Both have very complicated mechanisms that we haven't completely elucidated yet, and are crucial to the survival of their respective host organisms.
Here's the weird thing, though: all of the chloroplasts and mitochondria seem to have descended from bacteria that that invaded (or were taken in by) ancient cells, back in the days before multicellular life. These organelles have their own rather simple genomes, and reproduce independently in the cells of the "host" organism. What started out as symbiosis on a cellular level has evolved over billions of years until neither the complex eukaryotes nor the simpler organelles can survive without the other.
A little offtopic, I admit, but I couldn't let the opportunity for a lecture pass me by. At least you learned something from slashdot today;)
[sarcasm] Mein Gott! What a truly horrifying and unsettling scenario of the applications of DRM! But let's take it one step further. Let's imagine a system of communication that leaves even fewer traces than your self-deleting emails, say merely a timestamp or even no computerized record at all. Let's call this hypothetical protocol the V3RB4L protocol.
So your boss sends you a v3rb4l message, telling you to do something immoral. Amazingly, these v3rb4l messages leave no trace. Then you have five options, each stomach-turningly shocking:
1. Do what the verbal^H^H^H v3rb4l message says and get caught....
And so on ad nauseam
I can't wait either for your stupidity to be rewarded. [/sarcasm]
No, seriously, mods, what were you thinking? Didn't you even consider that a manager could use the telephone, or even -gasp- talk to this hypothetical conscientious employee? What an insidious troll.
Well in Newton's case, he himself wrote that the idea of gravity was "occasioned by the fall of an apple from a tree", and the sight of the full moon in the sky. He realized (he wrote) that the same force had to govern the moon's rotation (and Kepler's Laws) and the fall of the apple. I think it unlikely that it actually hit him on his head.
I think it unfortunate that Newton is often credited with a discovery instead of an invention. Yes, he discovered gravity, but he invented the Theory of gravity.
Google is a little different. Brin & Page were able to see the possibilities arising from their more-or-less failed experiment to annotate the web. You're right in that they wrote good code, but to do the wrong thing. Their "moment of brilliance" was in seeing that this code could be used for something entirely different than they had intended.
Wow. Good job checking the links and proofreading by everybody involved in posting that article. USA Today really needs to work on branding though. I could have sworn I was reading CNN...
That's an interesting theory you've got going there. Unfortunately, the handedness of DNA does not determine the chirality of amino acids used.
The handedness of DNA is determined by the handedness of the sugar in its "backbone" - that is, B-DNA is right-handed because it contains D-deoxyribose instead of L-deoxyibose. A hypothetical DNA molecule formed using L-deoxyribose would have a left-handed B-DNA helix. (Now remember that the A, B and Z forms of DNA are artifacts of it being a double helix. These are three different stable conformations of a DNA double helix (local minima). Z-DNA is globally unstable, and unusual in nature, because it requires some of the bases in DNA to flip from their usual "anti" conformation relative to deoxyribose to a less stable "syn" conformation.)
There is no reason that an RNA-based "enzyme" (similar to parts of a ribosome) would inherently prefer one isomer of an amino acid over another. It's just that once machinery had evolved to synthesize/utilize one isomer, it becomes very inefficient to use a whole 'nother set of enzymes for the other isomer of the same amino acid (unless you really really need a D-amino acid, as in bacterial cell walls). Dumb chance dictated that L-amino acids were chosen, for the most part, over D-amino acids.
Interestingly, the D/L conventions of sugars and of amino acids both derive from the isomers of glyceraldehyde, the simplest 3-carbon sugar. Whether a compound is D or L is determined by the orientation of the major group on the 2-carbon, when the molecule is drawn in the Fischer projection. The D/L convention is just that, a convention, and does not affect the chemical or optical properties of compounds in any consistent fashion. (That is, D/L names are totally distinct from dextrorotatory/laevorotatory names, which denote optical activity. It sucks, but there it is.) Your parent post is just flat out wrong when it says L-amino acids are energetically more favored than D-amino acids.
Slashdot Mirror
Not quite: it's more interesting than that. The Nature Biotechnology paper referenced in TFA goes into more detail.
A simple version: the anthrax bacterium makes a particular protein complex - the anthrax toxin - that disrupts cell membranes. This toxin has seven-fold symmetry, meaning that it is made up of seven identical subunits. There are various peptides that bind to each subunit and inhibit the anthrax toxin, thereby protecting cells.
What this group has done is to make liposomes (fat globules, not antibodies) with different concentrations of these peptides on the surface. When the density of inhibitory peptides on the liposomes roughly matches the density of target sites (one on each of the seven subunits) on the anthrax toxin, the inhibition is much more efficient. (This means you need much less of the peptide to protect cells.)
This general idea - of putting lots of inhibitory agents on one particle or compound - has been done before. The big advance here is that this is an easy way control the number & density of the inhibitors. Pretty slick.
366 MB?! Do you realize how long it'll take me to download that through someone else's access point?
That damn sundial taunts me every time I walk past it. I walk past it on my way back from work every day, and on the few days the sun hasn't set, it's invariably overcast. Maybe some day I'll be able to tell the time without having to look at my wristwatch.
<farnsworth>A man can dream, can't he? A man can dream...</farnsworth>
Where do the Vedas talk about Atlantis? Nowhere.
Indian mythology does include a city that was submerged - Dwaraka - but this is completely different from Atlantis because
a) it was a coastal city, not an island
b) there's a modern city called Dwaraka, more or less where the Mahabharata says Dwaraka is supposed to be
c) there are a bunch of submerged ruins near modern Dwaraka*
Which leads to the hypothesis that there was once a historical city, which submerged due to rising sea levels/land subsidence/other geological weirdness, whose inhabitants resettled nearby. No resorting to missing continents or racial memory or UFOs.
(cf. Current Science 86(9):1256-60 (10 May 2004))
"If you don't know, don't say."
Wait... have I been trolled? Dammit.
I'm a TA for a course that meets in Kane Hall this quarter. I can verify that the Kane Hall wireless mike is, in fact, a lapel mike tethered to a transmitter clipped onto your belt.
Very useful for subduing undergrad biochemistry students...
"Word to your mother."
Generic hip-hop greeting, I believe it's related to "Word"/"Word up!".
All they need is a face detector!
...crickets chirping...
Given that they've just started (in sunny California), my guess is they'll be pumping iron and groping each other. And marrying into the Kennedy family.
"Linguistic conciseness", not "concision". ;)
Nice try, though
Shame on you. That should be "ta da da... da duh-duh-duh daaah"
Did we just DOS the paper of record?
FYI, Dr. A was credited with coining 3 words: "psychohistory" in Foundation, "robotics" and "positronic" in I, Robot.
...just like electric charge. Microsoft is +10 AlwaysWinning(TM) Evil, while Amazon and Disney are both -5 OppressiveIP Evil. However note that by the Slashdot conventions, Microsoft is always twice as evil as any other company. Thus when Amazon, Disney and MS collaborate, all their evil cancels out and we can root for them.
;-)
Note that any branch of the government, the MPAA/RIAA etc. is -20 OppressiveIP Evil, twice as evil as MS, and so we can never root for them.
Next time RTFM
To the editors: word.
You have successfully posted two stories on two different revolutionary camcorders with no dupes.
Yet.
That's a rather Newtonian viewpoint; it was already 50 years out of date by the time Asimov wrote Foundation.
A quantum-mechanical universe precludes being able to observe or predict the universe in infinite detail. However we can still make useful predictions about the universe (and smaller systems).
We do this by estimating probabilities that a quantum mechanical system will enter one of a number of states, and using a sample size large enough that essentially the most likely outcome always happens.
This hand-waving lets us make rigorous mathematical predictions about substances and objects that can be verified - such as "At 100 Celsius and atmospheric pressure, water will boil." And by George, it works!
Psychohistory was intended to be exactly analogous to thermodynamics. Both sciences study particles whose individual behavior cannot be predicted, and both are inherently based on statistical mechanics.
Now thermodynamics only works because the number of particles in any real-world system is so mindnumbingly large. If we tried to predict the behavior of only (!) a million or a billion particles, you're right, the errors would add up pretty quickly. But by using a sufficiently large sample size, we give the system so many states that deviations from the average become essentially neglible.
When Asimov conceived of psychohistory, one of the most important characteristics of the science was that the sample size needed to be inconceivably large - quadrillions of people spread over half a million worlds. IIRC, this was in fact one of Hari Seldon's first postulates. (The second was that the people in the system could not be allowed to learn that their actions were predictable.)
Also consider that psychohistory was not used primarily to predict the actions of the Foundation: the sample size was too small and the Foundationers knew they were being tampered with. Psychohistory was used instead to analyze the future of the Empire in general and the barbarian kingdoms of the periphery in particular.
As you might have guessed I'm a big fan of the books and all of Asimov's writings. His writing style was not what you would call sublime, but you can't beat his production of great ideas and well-conceived universes.
For that kinda money, I would just but a bunch of nice TV's and scatter them around my living room at random distances.
He talks about the descendants of Algol and Fortran merging, and then has a throwaway line about that never having happened to actual species. I think it's interesting that something like that has probably occurred at least twice in the history of life.
;)
Mitochondria and chloroplasts are two of the most complicated organelles, cellular machinery found in complex organisms. Chloroplasts, found in the cells of higher plants, carry out photosynthesis, converting solar energy to food (glucose). Mitochondria are found in both animals and plants, and use oxygen to extract energy from nutrients. Both have very complicated mechanisms that we haven't completely elucidated yet, and are crucial to the survival of their respective host organisms.
Here's the weird thing, though: all of the chloroplasts and mitochondria seem to have descended from bacteria that that invaded (or were taken in by) ancient cells, back in the days before multicellular life. These organelles have their own rather simple genomes, and reproduce independently in the cells of the "host" organism. What started out as symbiosis on a cellular level has evolved over billions of years until neither the complex eukaryotes nor the simpler organelles can survive without the other.
A little offtopic, I admit, but I couldn't let the opportunity for a lecture pass me by. At least you learned something from slashdot today
So what is it then? 37 (a guess after ~3 sec).
Hold on...
36.56... well whaddya know?
[sarcasm]
Mein Gott! What a truly horrifying and unsettling scenario of the applications of DRM! But let's take it one step further. Let's imagine a system of communication that leaves even fewer traces than your self-deleting emails, say merely a timestamp or even no computerized record at all. Let's call this hypothetical protocol the V3RB4L protocol.
So your boss sends you a v3rb4l message, telling you to do something immoral. Amazingly, these v3rb4l messages leave no trace. Then you have five options, each stomach-turningly shocking:
1. Do what the verbal^H^H^H v3rb4l message says and get caught....
And so on ad nauseam
I can't wait either for your stupidity to be rewarded.
[/sarcasm]
No, seriously, mods, what were you thinking? Didn't you even consider that a manager could use the telephone, or even -gasp- talk to this hypothetical conscientious employee? What an insidious troll.
Fat guy in butterfly suit. Duh!
Although we do appear to have slashdotted the FCC. Good work, men!
Well in Newton's case, he himself wrote that the idea of gravity was "occasioned by the fall of an apple from a tree", and the sight of the full moon in the sky. He realized (he wrote) that the same force had to govern the moon's rotation (and Kepler's Laws) and the fall of the apple. I think it unlikely that it actually hit him on his head.
I think it unfortunate that Newton is often credited with a discovery instead of an invention. Yes, he discovered gravity, but he invented the Theory of gravity.
Google is a little different. Brin & Page were able to see the possibilities arising from their more-or-less failed experiment to annotate the web. You're right in that they wrote good code, but to do the wrong thing. Their "moment of brilliance" was in seeing that this code could be used for something entirely different than they had intended.
Wow. Good job checking the links and proofreading by everybody involved in posting that article. USA Today really needs to work on branding though. I could have sworn I was reading CNN...
That's an interesting theory you've got going there. Unfortunately, the handedness of DNA does not determine the chirality of amino acids used.
The handedness of DNA is determined by the handedness of the sugar in its "backbone" - that is, B-DNA is right-handed because it contains D-deoxyribose instead of L-deoxyibose. A hypothetical DNA molecule formed using L-deoxyribose would have a left-handed B-DNA helix. (Now remember that the A, B and Z forms of DNA are artifacts of it being a double helix. These are three different stable conformations of a DNA double helix (local minima). Z-DNA is globally unstable, and unusual in nature, because it requires some of the bases in DNA to flip from their usual "anti" conformation relative to deoxyribose to a less stable "syn" conformation.)
There is no reason that an RNA-based "enzyme" (similar to parts of a ribosome) would inherently prefer one isomer of an amino acid over another. It's just that once machinery had evolved to synthesize/utilize one isomer, it becomes very inefficient to use a whole 'nother set of enzymes for the other isomer of the same amino acid (unless you really really need a D-amino acid, as in bacterial cell walls). Dumb chance dictated that L-amino acids were chosen, for the most part, over D-amino acids.
Interestingly, the D/L conventions of sugars and of amino acids both derive from the isomers of glyceraldehyde, the simplest 3-carbon sugar. Whether a compound is D or L is determined by the orientation of the major group on the 2-carbon, when the molecule is drawn in the Fischer projection. The D/L convention is just that, a convention, and does not affect the chemical or optical properties of compounds in any consistent fashion. (That is, D/L names are totally distinct from dextrorotatory/laevorotatory names, which denote optical activity. It sucks, but there it is.) Your parent post is just flat out wrong when it says L-amino acids are energetically more favored than D-amino acids.