I am not an engineer, but as I understand it one of the more difficult engineering challenges of designing an implosion type device is getting the arrangement of the explosive lenses just right to compress the plutonium pit into a critical mass symmetrically. Just wrapping the pit in a plain sphere of explosives won't do the job - there will be parts of the explosive that will fire later than others and the compression will be non-symmetric.
If the implosion is non-symmetric, the fission primary will fling itself apart before substantial energy from the chain reaction can be generated.
Another design challenge is the electronics needed to fire all the explosive lenses with timing tolerances of less than a few millionths of a second, and switching devices that can switch hundreds of amps of current at those speeds. Needless to say, manufacturers do their best to control who gets their hands on them, though they are "dual use" and probably could be sourced indirectly.
Of course a gun type weapon would be substantially easier to get to work with wider tolerances than an implosion type, but they are so inefficient that they require a relatively huge amount of fissile material to make; perhaps an impractically large amount for a terrorist group to get their hands on without being easily noticed.
One of the principles of the social contract that one becomes a part of in a theoretically democratic society is that one concedes the monopoly on force to the government. The principle advantage of this in a properly functioning democratic society is that while the government has the sole right to use violence (both against its own citizens who do not obey the rule of law and against external threats), its citizens also have the power to exercise their will as to exactly how that power is used.
Your argument cuts both ways, one could as easily say that one who advocates less government are risking the overwhelming violence of the Hobbesian "war of all against all"; in other words the overwhelming violence of anarchy and mob rule where the strong dominate the weak 100% of the time. It's a delicate balancing act - I don't believe putting one's foot down and saying "More government, good!" or "More government, bad!" accurately reflects the complexities of maintaining a stable society.
The carpet in my apartment hasn't been replaced since 1977, I'm hoping that eventually fashion will come out the other side like Asteroids and worn down shag will again be all the rage.
For most of the older games it would be fine, but MAME has no support for hardware graphics acceleration. I use MAME on an Athlon X2 4800+, and it still chugs a bit on some "newer" games such as Mortal Kombat 3.
RS-232 is still a popular communications protocol in industrial/control applications, along with test equipment (i.e. data acquisition as stated in the summary). You can still buy exorbitantly priced RS-232 PCI expansion boards for these applications. The manufacturers of this board are probably looking to get some of that market, hence its inclusion.
I think it's unlikely that the price of scans will come down anytime soon, given that for many hospitals MRIs are a major cash cow. A modern scanner costs the hospital around $4 million, plus around a million a year for related salaries and maintenance. If they're doing an average of 15 scans per day (any major hospital with a scanner hits that number easily) and billing insurers an average of $2000 per scan (which from my experience is on the low end, my last MRI cost my insurance company $2900), they're pulling in near $11 million a year in gross profit. Plus the fact that the initial cost of the scanner is amortized over several years.
The US is screwed in that respect -- a pathetic rail system and approximately none of it electrified. I'm not sure where people get the idea that the US has a pathetic railroad system - there's over 140,000 miles of track currently in freight operation. Rail accounts for 40% of all freight-ton miles, more than any other mode of freight transport. The tonnage hauled per year has been increasing steadily over the past 15 years. Personally, I'd call the US rail system our hidden jewel.
MIDI DIN connectors are by no means dead. The fact that even the most modern sound modules and keyboards have midi/in out connectors 25 years after the creation of the standard should be proof enough of this. Musicians love vintage gear, and the ability to connect my 1986 Roland synth to a 2006 Yamaha synth and have them both understand each other is pretty amazing.
RS232 is still quite popular in industrial and control applications (I'd guess mainly because of technological inertia and the amount of old equipment that still does its job fine) - to the point that many electronics suppliers sell hundred dollar PCI to RS-232 cards to connect new machines to old gear.
It seems difficult to imagine that someone couldn't recognize the Macbook Air, considering at least where I live I'm subjected to that 15 second commercial spot at least 3 times an hour. Perhaps if the laptop played that little piece of doggerel every time someone whipped the computer out it would jog their memory.
After developing an unknown and so far incurable neurological disease a few years back, I started playing video games again at the age of 30 as I didn't have much to do after my family and friends moved on with their lives and were not a part of mine anymore. I don't feel I'm trying to recapture my youth exactly - but games have been a blessing in their ability to distract me from suffering and help regain some of the cognitive function I've lost.
An interesting fact I learned listening to some of the MIT lectures available online about the history and development of the Shuttle: One of the military requirements of the Shuttle was that it had at least 1400 miles crossrange. This was so for example, in a time of crisis (the shuttle was designed during the Cold War after all), the Shuttle could be launched from Vandenberg AFB into a polar orbit, immediately drop a spy satellite into orbit on the first go around (to prevent an enemy from learning the projected orbital path of the spy satellite by tracking the shuttle through multiple orbits), and then come right back to land on the west coast. Of course the earth would have rotated eastwards during that 90 minute orbit, so the shuttle needed the crossrange to be able to also glide eastwards and make a landing. Some original designs showed the shuttle having straight wings; apparently one of the major reasons NASA went with a delta-wing configuration was to meet the crossrange requirement.
You should really read physicist Richard Feynman's report on the Challenger disaster for an honest analysis of what lead to that orbiter's destruction. There's also a good list of myths about the disaster that's worth reading - for example the belief that Reagan's state of the union had anything to do with the disaster.
Launch officials clearly felt pressure to get the mission off after repeated delays, and they were embarrassed by repeated mockery on the television news of previous scrubs, but the driving factor in their minds seems to have been two shuttle-launched planetary probes. The first ever probes of this kind, they had an unmovable launch window just four months in the future. The persistent rumor that the White House had ordered the flight to proceed in order to spice up President Reagan's scheduled State of the Union address seems based on political motivations, not any direct testimony or other first-hand evidence. Feynman personally checked out the rumor and never found any substantiation. If Challenger's flight had gone according to plan, the crew would have been asleep at the time of Reagan's speech, and no communications links had been set up.
Missiles don't automatically cause a plane to instantly self-destruct, ya know. A missile strike could easily be followed by at least the first two of the three scenarios you present. In fact, given the large size of a passenger aircraft compared to a fighter aircraft, the chances that you'd survive the initial attack but the plane would be mortally crippled would be pretty high.
Richard Fenyman's report on the Challenger disaster stated that shuttle engineers on average believed that a catastrophic vehicle loss would occur once for every 100 flights - as they're on STS 127 now the Space Shuttle program is doing approximately par for the course. Space flight is orders of magnitude more risky than air transport, and while both disasters were caused by engineering flaws in the end it seems unfair to make such an apples to oranges comparison and say that NASA knows nothing about safety. Perhaps their management knows little about safety (they wildly overestimated the shuttle's reliability to the media, after all), but given the complexities involved it seems a miracle of engineering safety and otherwise that anyone comes back alive at all.
Unless the spin of the constitute particles of the atom is an integer, where at very low temperatures they should collapse into a Bose-Einstein condensate.
I think the problem of the massive infrastructure needed to create weapons grade fissionables and the use of supercomputers to model weapon designs goes hand-in-hand. If a nation has limited fissionable material available, they're going to want to build the most efficient design possible. Though most current US weapons were designed before the era of modern computing, the US had the luxury of data gathered from hundreds of atmospheric and underground tests to apply to those designs; a luxury which states like Iran obviously don't have. Sure, Iran doesn't need a bomb that can fit in a suitcase, but if they were pursuing nuclear weapons, they would want a weapon that doesn't waste a huge amount of fissile material and had some chance of fitting in a realistic delivery system, and a Fat Man copy isn't it.
Is it possible to build an efficient, relatively compact (i.e. deliverable by cruise or ballistic missile or by fighter aircraft) weapon with no access to live test data and only modern consumer-grade computing power? Probably, but a supercomputer would make things quite a bit easier.
I read the sequel. Perhaps this was just my impression, but as time went on in the novels the main characters and their genetically enhanced kids just became more unlikeable - like the part where Kaye ponders (and accepts) that she'd shoot some unsuspecting vet if she wouldn't provide the antivirals for her kids. Maybe it's just my geek sympathy, but I liked the poor CDC researcher guy (the name of the character escapes me, it's been a few years since I read the novels) who was interested in her and gets snubbed, and then gets near killed in a terrorist bombing. I hoped something interesting would happen with him in Darwin's Children, but nah. It's just about Kaye and Her Man and her Awesome Mutant Kids.
Oh, and Greg Bear uses the phrase "Mons Pubis" in a sex scene. Good grief.
Mod parent up. Evidence suggests that HIV crossed over to humans sometime in the early 20th century - there are records of deaths due to opportunistic infections that should not have affected the healthy patients they did as far back as the 1930s. It's similar to Lyme disease, which is the modern term for a disease that has probably been afflicting people for far longer - though the disease was "discovered" in 1976 clinical cases of debilitating neurological and musculoskeletal symptoms associated with unusual rashes have been recorded in medical records for over 100 years.
Slashdot Mirror
I am not an engineer, but as I understand it one of the more difficult engineering challenges of designing an implosion type device is getting the arrangement of the explosive lenses just right to compress the plutonium pit into a critical mass symmetrically. Just wrapping the pit in a plain sphere of explosives won't do the job - there will be parts of the explosive that will fire later than others and the compression will be non-symmetric. If the implosion is non-symmetric, the fission primary will fling itself apart before substantial energy from the chain reaction can be generated.
Another design challenge is the electronics needed to fire all the explosive lenses with timing tolerances of less than a few millionths of a second, and switching devices that can switch hundreds of amps of current at those speeds. Needless to say, manufacturers do their best to control who gets their hands on them, though they are "dual use" and probably could be sourced indirectly.
Of course a gun type weapon would be substantially easier to get to work with wider tolerances than an implosion type, but they are so inefficient that they require a relatively huge amount of fissile material to make; perhaps an impractically large amount for a terrorist group to get their hands on without being easily noticed.
One of the principles of the social contract that one becomes a part of in a theoretically democratic society is that one concedes the monopoly on force to the government. The principle advantage of this in a properly functioning democratic society is that while the government has the sole right to use violence (both against its own citizens who do not obey the rule of law and against external threats), its citizens also have the power to exercise their will as to exactly how that power is used. Your argument cuts both ways, one could as easily say that one who advocates less government are risking the overwhelming violence of the Hobbesian "war of all against all"; in other words the overwhelming violence of anarchy and mob rule where the strong dominate the weak 100% of the time. It's a delicate balancing act - I don't believe putting one's foot down and saying "More government, good!" or "More government, bad!" accurately reflects the complexities of maintaining a stable society.
The carpet in my apartment hasn't been replaced since 1977, I'm hoping that eventually fashion will come out the other side like Asteroids and worn down shag will again be all the rage.
What will I be able use as a bonding topic at my 20th high school reunion?!
For most of the older games it would be fine, but MAME has no support for hardware graphics acceleration. I use MAME on an Athlon X2 4800+, and it still chugs a bit on some "newer" games such as Mortal Kombat 3.
RS-232 is still a popular communications protocol in industrial/control applications, along with test equipment (i.e. data acquisition as stated in the summary). You can still buy exorbitantly priced RS-232 PCI expansion boards for these applications. The manufacturers of this board are probably looking to get some of that market, hence its inclusion.
I think it's unlikely that the price of scans will come down anytime soon, given that for many hospitals MRIs are a major cash cow. A modern scanner costs the hospital around $4 million, plus around a million a year for related salaries and maintenance. If they're doing an average of 15 scans per day (any major hospital with a scanner hits that number easily) and billing insurers an average of $2000 per scan (which from my experience is on the low end, my last MRI cost my insurance company $2900), they're pulling in near $11 million a year in gross profit. Plus the fact that the initial cost of the scanner is amortized over several years.
Something like: "Theoretical physicists turn money into ideas. Engineers turn ideas into money."
Correction - 7:07 UTC, I was looking at the wrong table.
It looks like the largest aftershock so far just hit at 08:54 UTC, a 5.9.
The bash.org quote forgets the part where the company says of the other candidate "but he's soooooo totes hot. And doesn't punch us that often."
MIDI DIN connectors are by no means dead. The fact that even the most modern sound modules and keyboards have midi/in out connectors 25 years after the creation of the standard should be proof enough of this. Musicians love vintage gear, and the ability to connect my 1986 Roland synth to a 2006 Yamaha synth and have them both understand each other is pretty amazing.
RS232 is still quite popular in industrial and control applications (I'd guess mainly because of technological inertia and the amount of old equipment that still does its job fine) - to the point that many electronics suppliers sell hundred dollar PCI to RS-232 cards to connect new machines to old gear.
It seems difficult to imagine that someone couldn't recognize the Macbook Air, considering at least where I live I'm subjected to that 15 second commercial spot at least 3 times an hour. Perhaps if the laptop played that little piece of doggerel every time someone whipped the computer out it would jog their memory.
After developing an unknown and so far incurable neurological disease a few years back, I started playing video games again at the age of 30 as I didn't have much to do after my family and friends moved on with their lives and were not a part of mine anymore. I don't feel I'm trying to recapture my youth exactly - but games have been a blessing in their ability to distract me from suffering and help regain some of the cognitive function I've lost.
An interesting fact I learned listening to some of the MIT lectures available online about the history and development of the Shuttle: One of the military requirements of the Shuttle was that it had at least 1400 miles crossrange. This was so for example, in a time of crisis (the shuttle was designed during the Cold War after all), the Shuttle could be launched from Vandenberg AFB into a polar orbit, immediately drop a spy satellite into orbit on the first go around (to prevent an enemy from learning the projected orbital path of the spy satellite by tracking the shuttle through multiple orbits), and then come right back to land on the west coast. Of course the earth would have rotated eastwards during that 90 minute orbit, so the shuttle needed the crossrange to be able to also glide eastwards and make a landing. Some original designs showed the shuttle having straight wings; apparently one of the major reasons NASA went with a delta-wing configuration was to meet the crossrange requirement.
You should really read physicist Richard Feynman's report on the Challenger disaster for an honest analysis of what lead to that orbiter's destruction. There's also a good list of myths about the disaster that's worth reading - for example the belief that Reagan's state of the union had anything to do with the disaster.
Launch officials clearly felt pressure to get the mission off after repeated delays, and they were embarrassed by repeated mockery on the television news of previous scrubs, but the driving factor in their minds seems to have been two shuttle-launched planetary probes. The first ever probes of this kind, they had an unmovable launch window just four months in the future. The persistent rumor that the White House had ordered the flight to proceed in order to spice up President Reagan's scheduled State of the Union address seems based on political motivations, not any direct testimony or other first-hand evidence. Feynman personally checked out the rumor and never found any substantiation. If Challenger's flight had gone according to plan, the crew would have been asleep at the time of Reagan's speech, and no communications links had been set up.
Feynman's Appendix to the Rogers Commission Report on the Space Shuttle Challenger Accident
7 myths about the Challenger shuttle disaster
Missiles don't automatically cause a plane to instantly self-destruct, ya know. A missile strike could easily be followed by at least the first two of the three scenarios you present. In fact, given the large size of a passenger aircraft compared to a fighter aircraft, the chances that you'd survive the initial attack but the plane would be mortally crippled would be pretty high.
Smoking on a plane! Man, those were the days. I think nowadays a constantly lit bulb behind the No Smoking sign would work just fine.
Richard Fenyman's report on the Challenger disaster stated that shuttle engineers on average believed that a catastrophic vehicle loss would occur once for every 100 flights - as they're on STS 127 now the Space Shuttle program is doing approximately par for the course. Space flight is orders of magnitude more risky than air transport, and while both disasters were caused by engineering flaws in the end it seems unfair to make such an apples to oranges comparison and say that NASA knows nothing about safety. Perhaps their management knows little about safety (they wildly overestimated the shuttle's reliability to the media, after all), but given the complexities involved it seems a miracle of engineering safety and otherwise that anyone comes back alive at all.
Unless the spin of the constitute particles of the atom is an integer, where at very low temperatures they should collapse into a Bose-Einstein condensate.
I think the problem of the massive infrastructure needed to create weapons grade fissionables and the use of supercomputers to model weapon designs goes hand-in-hand. If a nation has limited fissionable material available, they're going to want to build the most efficient design possible. Though most current US weapons were designed before the era of modern computing, the US had the luxury of data gathered from hundreds of atmospheric and underground tests to apply to those designs; a luxury which states like Iran obviously don't have. Sure, Iran doesn't need a bomb that can fit in a suitcase, but if they were pursuing nuclear weapons, they would want a weapon that doesn't waste a huge amount of fissile material and had some chance of fitting in a realistic delivery system, and a Fat Man copy isn't it.
Is it possible to build an efficient, relatively compact (i.e. deliverable by cruise or ballistic missile or by fighter aircraft) weapon with no access to live test data and only modern consumer-grade computing power? Probably, but a supercomputer would make things quite a bit easier.
I read the sequel. Perhaps this was just my impression, but as time went on in the novels the main characters and their genetically enhanced kids just became more unlikeable - like the part where Kaye ponders (and accepts) that she'd shoot some unsuspecting vet if she wouldn't provide the antivirals for her kids. Maybe it's just my geek sympathy, but I liked the poor CDC researcher guy (the name of the character escapes me, it's been a few years since I read the novels) who was interested in her and gets snubbed, and then gets near killed in a terrorist bombing. I hoped something interesting would happen with him in Darwin's Children, but nah. It's just about Kaye and Her Man and her Awesome Mutant Kids. Oh, and Greg Bear uses the phrase "Mons Pubis" in a sex scene. Good grief.
Mod parent up. Evidence suggests that HIV crossed over to humans sometime in the early 20th century - there are records of deaths due to opportunistic infections that should not have affected the healthy patients they did as far back as the 1930s. It's similar to Lyme disease, which is the modern term for a disease that has probably been afflicting people for far longer - though the disease was "discovered" in 1976 clinical cases of debilitating neurological and musculoskeletal symptoms associated with unusual rashes have been recorded in medical records for over 100 years.