Have you ever traveled the northeast corridor between New York and Washington? I don't know about other people's sense of aesthetics, but I think a 250 mile long slab of elevated concrete could only improve things.
The Acela runs on the same tracks that have been in existence in the Northeast Corridor for decades - the entire right-of-way from Boston to Washington wasn't relaid solely to accommodate the new trainset, so I'm not sure what you mean by "the tracks were placed several inches too close to each other" as they're essentially the same as they always were - which is a lot better than most parts of the country but nowhere near as arrow-straight as say, the TGV has. The only major modifications made was the electrification of the system from New Haven to Boston done in the late 1990s, and the widening of some bridges. The speed of the Acela is limited because the curves and track spacing are what they are, and also because the train's speed is limited in areas where there are grade crossings, which unfortunately includes pretty much all of Rhode Island and Connecticut.
Living in Massachusetts and being familiar with the "Cape Wind" controversy, I completely agree with you on the NIMBY attitude. It is believed to have the backing of 4/5ths of the state's population according to surveys, however influential left-leaning politicians whom you'd think would be all for renewable energy have done their best to stymie the project, mainly because they or their cronies own prime beach real estate whose lovely views would be ruined.
In the case of nuclear, however, I don't believe that it is only the fault of NIMBYs that has sunk efforts to revive its popularity in the U.S. In the U.S. the construction of a new power plant of any type, including nuclear, requires massive private investment - by investors who are expecting a return on their investment. Even though the risks of the accident at Three Mile Island were exaggerated, the expensive of the cleanup and investigation showed the private investors involved with that plant that a $2 billion asset could be turned into a $1 billion liability in less than 60 minutes. With that in mind, and also the fact that building a new coal or natural gas fired plant costs a fraction of a nuclear plant with a near guarantee of ROI makes the decision for investors rather easy. France and Japan have probably had more luck building a large nuclear infrastructure as their power generation industry is essentially nationalized, and were less reliant on private funding.
The reason some of the technologies you mention are not being used extensively is not only a question of cost, it's also a question of running up against technological difficulties and the laws of physics. Solar panel efficiency is still stuck at around 15% on average. Hydrogen is not an energy source, it is an energy carrier - one needs to use some other energy source to produce it. Battery technology restricts the use of electric powered vehicles. Even if all of the U.S. corn crop were converted to ethanol, it could only power 20% of vehicles on the road, and thats assuming farms still use the hundreds of thousands of tons of petroleum based fertilizers currently applied to make crop yields what they are. Crunching the numbers on all these things is difficult, but from the research I have seen it is easily apparent that even if we used all available alternative energy sources that we know of to maximum efficiency using current technology, the world would still fall short of fulfilling its CURRENT energy demands by a wide margin.
Perhaps there will be continued innovation in more efficient alternative energy technologies; perhaps others will be discovered. It's also possible that neither will happen, or neither is possible. By believing that the free market will automatically rectify the inevitable decline in world oil production with alternative fuels one is essentially betting that both possibilities will come about in time to avert an energy crisis, while the status quo is maintained for the foreseeable future. This seems to me like a dangerous gamble.
Hey, that's actually a great price on the 872, a tube which I wasn't familiar with. I've tried to win some mercury rectifiers on ebay like the 816, 866, and type 83, but since they seem to be popular tubes for antique ham transmitters and tube testers they always go for high prices. 1250 ma output current! I think I'll use two of these in full wave when (if) I get around to building my stereo 150 watt RMS per channel tube power amp project.
I think the most beautiful piece of old AC to DC conversion technology was the mercury arc rectifier...apparently these devices were still used on some branches of the NYC subway until late in the 20th century. A video of one in operation can be seen at http://www.youtube.com/watch?v=Rt-a8fxgtno
A center-tapped transformer was connected to two anodes to form a full-wave rectifier(some had more anodes and were used for 3 phase power), and a pool of liquid mercury was used as the cathode material which would form an arc only if the anode was positive. A keep-alive electrode kept the interior full of vaporized mercury to facilitate the discharge. I'd sure like to have my own. Unfortunately an average sized mercury arc rectifier contains around 2 pounds of liquid mercury, so if it ever broke, my neighborhood would have to be decontaminated, my home razed to the ground, and the rubble buried in a concrete encasement.
Most vacuum tubes have filaments that need to be hot to cause thermionic emission, but that doesn't mean one can keep the entire tube and its environment at 450 degrees C. The problem is made worse because the tube plates can only cool themselves by radiating heat through the vacuum to the glass or metal envelope or conducting down the leads, unlike semiconductors which can be heat-sunk. If the ambient temperature is too high the plate won't be able to dissipate heat, and out gassing from the overheated metal will ruin the tube.
I was reading about the Apollo Guidance Computer on Wikipedia a while back and this part stood out:
"The Apollo flight computer was the first to use integrated circuits (ICs). The Block I version used 4,100 ICs, each containing a single 3-input NOR logic gate. The later Block II version used dual 3-input NOR gates in a flat-pack, approximately 5,600 gates in all. The gates were made by Fairchild Semiconductor using resistor-transistor logic (RTL). They were interconnected by a technique called wire wrap, in which the circuits are pushed into sockets, the sockets have square posts, and wire is wrapped around the posts. The edges of the posts bite the wire with tons of pressure per square inch, causing gas-tight connections that are more reliable than soldered PC boards. The wiring was then embedded in cast epoxy plastic."
No reference for that section, unfortunately. Dunking the whole thing in epoxy sounds like it might have had more of an effect on the reliability, though.
I bet you'd also tell the team who built a replica Wright flyer a few years back that they were wasting their time, and would be better off building a Zodiac sport plane kit.
Researchers have constructed the equivalent of the old vacuum tube triode using carbon nanotubes. I haven't read the entire paper on the nanotube radio so I don't know if this is how they went about it, but a simple nanotube diode could detect and demodulate a radio signal but not amplify. Using a single nanotube triode one might be able to construct a nanoscale version of a regenerative reciever.
You're correct - it's assumed by many that the destructive power of a thermonuclear air blast scales linearly with the energy released, i.e. a 1 megaton weapon is 10 times as powerful as a 100 kiloton weapon. In fact it's more of a logarithmic relationship. Using ten 100 kiloton devices in a carefully arranged pattern over a "soft target" such as a city or military base would create much more damage than a single device detonated at the center, because it would increase the total area of maximum overpressure. Multiple warheads also have the advantage of redundancy; if some missiles fail on launch or during re-entry you still have that target covered to some degree.
Lower yield, high accuracy warheads also make sense when used for surface attack on hardened targets such as missile silos. Reinforced silos can withstand huge overpressures and wouldn't be harmed by anything less than a direct hit, so surface blasts are needed, but surface explosions eject millions of tons of pulverized soil into the air which could cause "fratricide" to other incoming warheads. The problem can be mitigated somewhat by using smaller, more accurate warheads, and "walking them in" on a precise schedule across a missile field in a direction opposite the prevailing winds to avoid blast and debris damage.
Getting slightly off topic - It was of course in the defender's interest to maximize the chance of a missile failing before it reached it's target, and defending missile fields was of paramount importance. ABM systems were one way, but were costly, controversial, and of limited proven effectiveness. There were several bizzare sounding methods of "passive missile defense" for silos floated in the 1970s and 80s, one of them involved driving thousands of steel rods several meters high into the ground for miles north of a missile field. To achieve high accuracy, Russian warheads had to come in at extremely shallow angles - it was believed that for the last few miles of a high accuracy Russian warhead's trajectory it would be only a few meters off the ground. It was hoped that the warhead would be ripped to shreds by the metal rods before it had a chance to detonate. A similar idea involved placing pits filled with explosives and covered with ball bearings north of a missile field that would be triggered by radar and achieve the same effect.
Are you sure you watched the same movie? As I recall, there are newscasts during the film that report that the Russians have crossed into the Fulda gap in West Germany and have used tactical nuclear weapons against West German targets. As far as the actual full scale ICBM exchange that takes place during the second half of the film goes it's pretty much seen only from the perspective of people living around Lawrence Kansas and Kansas City, and there's really no indication of who fired what first.
IANAMP (I am not a medical professional), but as you are you might know an answer to this - from my limited understanding it seems that the problem of antibiotic resistance is directly related to the replication time of a bacteria, that is the faster a bacteria replicates the more opportunities it has to develop a mutation that makes it resistant to a drug. I'm pretty sure this is one of those "if it were possible it would have been done already" things, but is there any way for some kind of treatment to slow down the replication time of a bacteria (maybe through denying a certain nutrient or something) so that antibiotics could clear the infection before the bacteria could go through enough replications to develop a drug-defeating mutation?
Lyme disease is an illness that is surrounded by controversy regarding whether people who have continuing symptoms after treatment with antibiotics have persistent infection, or some kind of "molecular mimicry" autoimmune dysfunction caused by exposure to the B. burgdorferi spirochete. There was a study done recently where improvement in symptoms was reported in patients treated with hydroxychloroquine and clarithromyicn, a macrolide antibiotic. The theory is that the hydroxychloroquine raises the pH of the intracellular medium of tissues where the spirochete likes to hide out, allowing the macrolide antibiotic to be more effective. Also, because hydroxychloroquine is a anti-rhemuatoid agent as well, it can help address the chronic inflammation that Lyme patients suffer from while potentiating the antibiotic.
Text books in the Third World are expensive They're pretty expensive here in the first world, as well.
With a net connection an e-book on a laptop these can easily, quickly, and cheaply.
I've seen very few textbooks released in e-book format; most of the ones I have seen were in very specialized subjects and released under the GNU FDL. I doubt that textbook publishing companies will jump at the chance to release e-book versions of up-to-date, popular textbooks, undercut their own profits, and put themselves in the same position as the RIAA with regards to piracy, regardless of how much it benefits impoverished children. Even pharmaceutical companies jealously guard their IP when it comes to having low-cost generics manufactured overseas, and in that case there are lives at stake.
On the other hand, publishers might release e-book versions of textbooks a generation or two old at a low price - that could help deal with the problem of piracy by consumers in the first world (since many courses, particularly in college, require the latest edition), and selling some e-books at a reduced price would be better than selling nothing at a high price for both parties involved.
The research presented in this article reminds me of a an abstract I read a while back about a team who developed an on chip vacuum tube micro-triode which used carbon nanotubes as field emitters. It might not be possible to build a computer out of them, but logic built from them would have some of the same advantages mentioned in TFA (high immunity to electromagnetic radiation, etc.)
Link (warning PDF) http://ieeexplore.ieee.org/Xplore/login.jsp?url=/i el5/16/21940/01019936.pdf
>Are American schools really as bad as they are made out in movies?
It often depends on who you are, where you are, and how powerful/wealthy your parents are. Many inner city public schools are exactly the hells on earth that are depicted in movies, and using the term "bullying" to describe the literal crimes against humanity that occur in them would be ridiculous. Suburban public schools are usually somewhat better, but having attended what was considered one of the "best" public high schools in the state of Massachusetts, I can attest that over the four years I was in attendance that in addition to the usual teasing and harassment there were quite a number of incidents of serious violence. The idea of a "mutually agreed fight" is something I have never heard of at least in my educational experience - nearly all of the incidents of physical violence I witnessed or heard about were 20 on 1 assaults that often left the victim needing reconstructive surgery.
Anyone with any money puts their kid into a private school, where they certainly can't be assured that their child won't be the victim of merciless teasing, but at least private schools to some degree have more safeguards to prevent physical harm and have more stringent codes of conduct vis a vis expulsion, etc.
One also has to realize that in the US, high school violence is intrinsically linked with issues of drug use and race. High schools in America's large population centers contain diverse ethnic groups, and contrary to the 'melting-pot' utopia that everyone would like to believe, many of the teenage members of said ethnic groups really don't like each other very much. Add to that the enormous profits made on the drug trade inside US schools and the activities that go along with it and I'm surprised that many schools are as good as they are.
I wonder what would have happened 15 years ago if a production designer had been told "It'll be too expensive to make a set for this scene, we'll just CG it." But I think you're probably right, it most likely is cheaper to create a set in CG than actually hire someone to design the real thing and build it on a lot - particularly for sci-fi movies.
If a director for a project like "Sky Captian and the World of Tomorrow" (which has a lot of cityscape scenes reminiscent of the Blade Runner panoramas) wanted to do that film with models, sets, and in-camera F/X he'd be laughed at.
So it was done with CG, and predictably that movie looked like crap, as I feel the "uncanny valley" effect that applies to CG humans can also apply to inanimate objects. But it got done and it made some money, which is pretty much what has always mattered.
There was a PBS documentary on the other day (the name of which unfortunately escapes me) about the production design of various classic films. Apparently one of the reasons the street scenes in Blade Runner were so incredibly detailed is that during the early stages of filming, the screen actors guild in L.A. went on strike for 8 weeks or so. The only folks still able to come into work and that had anything to do with no actors around were the set-building crew and production designers, and left to their own devices they went nuts. Apparently "Ridleyville" (as the main street set was jokingly referred to) ended up one of the most intricately detailed in movie history by the time the actors came back to restart shooting.
Slashdot Mirror
Have you ever traveled the northeast corridor between New York and Washington? I don't know about other people's sense of aesthetics, but I think a 250 mile long slab of elevated concrete could only improve things.
The Acela runs on the same tracks that have been in existence in the Northeast Corridor for decades - the entire right-of-way from Boston to Washington wasn't relaid solely to accommodate the new trainset, so I'm not sure what you mean by "the tracks were placed several inches too close to each other" as they're essentially the same as they always were - which is a lot better than most parts of the country but nowhere near as arrow-straight as say, the TGV has. The only major modifications made was the electrification of the system from New Haven to Boston done in the late 1990s, and the widening of some bridges. The speed of the Acela is limited because the curves and track spacing are what they are, and also because the train's speed is limited in areas where there are grade crossings, which unfortunately includes pretty much all of Rhode Island and Connecticut.
I'm surprised that there are that many CS majors at Harvard given the 800 pound gorilla down the street at Kendall Square..
Venus's internal dynamo was intentionally stopped by the superconducting electromagnets that encircle the planet.
Living in Massachusetts and being familiar with the "Cape Wind" controversy, I completely agree with you on the NIMBY attitude. It is believed to have the backing of 4/5ths of the state's population according to surveys, however influential left-leaning politicians whom you'd think would be all for renewable energy have done their best to stymie the project, mainly because they or their cronies own prime beach real estate whose lovely views would be ruined.
In the case of nuclear, however, I don't believe that it is only the fault of NIMBYs that has sunk efforts to revive its popularity in the U.S. In the U.S. the construction of a new power plant of any type, including nuclear, requires massive private investment - by investors who are expecting a return on their investment. Even though the risks of the accident at Three Mile Island were exaggerated, the expensive of the cleanup and investigation showed the private investors involved with that plant that a $2 billion asset could be turned into a $1 billion liability in less than 60 minutes. With that in mind, and also the fact that building a new coal or natural gas fired plant costs a fraction of a nuclear plant with a near guarantee of ROI makes the decision for investors rather easy. France and Japan have probably had more luck building a large nuclear infrastructure as their power generation industry is essentially nationalized, and were less reliant on private funding.The reason some of the technologies you mention are not being used extensively is not only a question of cost, it's also a question of running up against technological difficulties and the laws of physics. Solar panel efficiency is still stuck at around 15% on average. Hydrogen is not an energy source, it is an energy carrier - one needs to use some other energy source to produce it. Battery technology restricts the use of electric powered vehicles. Even if all of the U.S. corn crop were converted to ethanol, it could only power 20% of vehicles on the road, and thats assuming farms still use the hundreds of thousands of tons of petroleum based fertilizers currently applied to make crop yields what they are. Crunching the numbers on all these things is difficult, but from the research I have seen it is easily apparent that even if we used all available alternative energy sources that we know of to maximum efficiency using current technology, the world would still fall short of fulfilling its CURRENT energy demands by a wide margin.
Perhaps there will be continued innovation in more efficient alternative energy technologies; perhaps others will be discovered. It's also possible that neither will happen, or neither is possible. By believing that the free market will automatically rectify the inevitable decline in world oil production with alternative fuels one is essentially betting that both possibilities will come about in time to avert an energy crisis, while the status quo is maintained for the foreseeable future. This seems to me like a dangerous gamble.Hey, that's actually a great price on the 872, a tube which I wasn't familiar with. I've tried to win some mercury rectifiers on ebay like the 816, 866, and type 83, but since they seem to be popular tubes for antique ham transmitters and tube testers they always go for high prices. 1250 ma output current! I think I'll use two of these in full wave when (if) I get around to building my stereo 150 watt RMS per channel tube power amp project.
I think the most beautiful piece of old AC to DC conversion technology was the mercury arc rectifier...apparently these devices were still used on some branches of the NYC subway until late in the 20th century. A video of one in operation can be seen at http://www.youtube.com/watch?v=Rt-a8fxgtno
A center-tapped transformer was connected to two anodes to form a full-wave rectifier(some had more anodes and were used for 3 phase power), and a pool of liquid mercury was used as the cathode material which would form an arc only if the anode was positive. A keep-alive electrode kept the interior full of vaporized mercury to facilitate the discharge. I'd sure like to have my own. Unfortunately an average sized mercury arc rectifier contains around 2 pounds of liquid mercury, so if it ever broke, my neighborhood would have to be decontaminated, my home razed to the ground, and the rubble buried in a concrete encasement.
Most vacuum tubes have filaments that need to be hot to cause thermionic emission, but that doesn't mean one can keep the entire tube and its environment at 450 degrees C. The problem is made worse because the tube plates can only cool themselves by radiating heat through the vacuum to the glass or metal envelope or conducting down the leads, unlike semiconductors which can be heat-sunk. If the ambient temperature is too high the plate won't be able to dissipate heat, and out gassing from the overheated metal will ruin the tube.
This was a big improvement over the Radio Shack kits that used springs and jumper wires.
I was reading about the Apollo Guidance Computer on Wikipedia a while back and this part stood out:
"The Apollo flight computer was the first to use integrated circuits (ICs). The Block I version used 4,100 ICs, each containing a single 3-input NOR logic gate. The later Block II version used dual 3-input NOR gates in a flat-pack, approximately 5,600 gates in all. The gates were made by Fairchild Semiconductor using resistor-transistor logic (RTL). They were interconnected by a technique called wire wrap, in which the circuits are pushed into sockets, the sockets have square posts, and wire is wrapped around the posts. The edges of the posts bite the wire with tons of pressure per square inch, causing gas-tight connections that are more reliable than soldered PC boards. The wiring was then embedded in cast epoxy plastic."
No reference for that section, unfortunately. Dunking the whole thing in epoxy sounds like it might have had more of an effect on the reliability, though.
I bet you'd also tell the team who built a replica Wright flyer a few years back that they were wasting their time, and would be better off building a Zodiac sport plane kit.
Researchers have constructed the equivalent of the old vacuum tube triode using carbon nanotubes. I haven't read the entire paper on the nanotube radio so I don't know if this is how they went about it, but a simple nanotube diode could detect and demodulate a radio signal but not amplify. Using a single nanotube triode one might be able to construct a nanoscale version of a regenerative reciever.
Has Bob made up any degrees lately? Has he successfully completed a replica of the Grey's anti-gravity warp drive?
You're correct - it's assumed by many that the destructive power of a thermonuclear air blast scales linearly with the energy released, i.e. a 1 megaton weapon is 10 times as powerful as a 100 kiloton weapon. In fact it's more of a logarithmic relationship. Using ten 100 kiloton devices in a carefully arranged pattern over a "soft target" such as a city or military base would create much more damage than a single device detonated at the center, because it would increase the total area of maximum overpressure. Multiple warheads also have the advantage of redundancy; if some missiles fail on launch or during re-entry you still have that target covered to some degree.
Lower yield, high accuracy warheads also make sense when used for surface attack on hardened targets such as missile silos. Reinforced silos can withstand huge overpressures and wouldn't be harmed by anything less than a direct hit, so surface blasts are needed, but surface explosions eject millions of tons of pulverized soil into the air which could cause "fratricide" to other incoming warheads. The problem can be mitigated somewhat by using smaller, more accurate warheads, and "walking them in" on a precise schedule across a missile field in a direction opposite the prevailing winds to avoid blast and debris damage.
Getting slightly off topic - It was of course in the defender's interest to maximize the chance of a missile failing before it reached it's target, and defending missile fields was of paramount importance. ABM systems were one way, but were costly, controversial, and of limited proven effectiveness. There were several bizzare sounding methods of "passive missile defense" for silos floated in the 1970s and 80s, one of them involved driving thousands of steel rods several meters high into the ground for miles north of a missile field. To achieve high accuracy, Russian warheads had to come in at extremely shallow angles - it was believed that for the last few miles of a high accuracy Russian warhead's trajectory it would be only a few meters off the ground. It was hoped that the warhead would be ripped to shreds by the metal rods before it had a chance to detonate. A similar idea involved placing pits filled with explosives and covered with ball bearings north of a missile field that would be triggered by radar and achieve the same effect.
Are you sure you watched the same movie? As I recall, there are newscasts during the film that report that the Russians have crossed into the Fulda gap in West Germany and have used tactical nuclear weapons against West German targets. As far as the actual full scale ICBM exchange that takes place during the second half of the film goes it's pretty much seen only from the perspective of people living around Lawrence Kansas and Kansas City, and there's really no indication of who fired what first.
IANAMP (I am not a medical professional), but as you are you might know an answer to this - from my limited understanding it seems that the problem of antibiotic resistance is directly related to the replication time of a bacteria, that is the faster a bacteria replicates the more opportunities it has to develop a mutation that makes it resistant to a drug. I'm pretty sure this is one of those "if it were possible it would have been done already" things, but is there any way for some kind of treatment to slow down the replication time of a bacteria (maybe through denying a certain nutrient or something) so that antibiotics could clear the infection before the bacteria could go through enough replications to develop a drug-defeating mutation?
Lyme disease is an illness that is surrounded by controversy regarding whether people who have continuing symptoms after treatment with antibiotics have persistent infection, or some kind of "molecular mimicry" autoimmune dysfunction caused by exposure to the B. burgdorferi spirochete. There was a study done recently where improvement in symptoms was reported in patients treated with hydroxychloroquine and clarithromyicn, a macrolide antibiotic. The theory is that the hydroxychloroquine raises the pH of the intracellular medium of tissues where the spirochete likes to hide out, allowing the macrolide antibiotic to be more effective. Also, because hydroxychloroquine is a anti-rhemuatoid agent as well, it can help address the chronic inflammation that Lyme patients suffer from while potentiating the antibiotic.
I've seen very few textbooks released in e-book format; most of the ones I have seen were in very specialized subjects and released under the GNU FDL. I doubt that textbook publishing companies will jump at the chance to release e-book versions of up-to-date, popular textbooks, undercut their own profits, and put themselves in the same position as the RIAA with regards to piracy, regardless of how much it benefits impoverished children. Even pharmaceutical companies jealously guard their IP when it comes to having low-cost generics manufactured overseas, and in that case there are lives at stake.
On the other hand, publishers might release e-book versions of textbooks a generation or two old at a low price - that could help deal with the problem of piracy by consumers in the first world (since many courses, particularly in college, require the latest edition), and selling some e-books at a reduced price would be better than selling nothing at a high price for both parties involved.
The research presented in this article reminds me of a an abstract I read a while back about a team who developed an on chip vacuum tube micro-triode which used carbon nanotubes as field emitters. It might not be possible to build a computer out of them, but logic built from them would have some of the same advantages mentioned in TFA (high immunity to electromagnetic radiation, etc.)i el5/16/21940/01019936.pdf
Link (warning PDF) http://ieeexplore.ieee.org/Xplore/login.jsp?url=/
>Are American schools really as bad as they are made out in movies?
It often depends on who you are, where you are, and how powerful/wealthy your parents are. Many inner city public schools are exactly the hells on earth that are depicted in movies, and using the term "bullying" to describe the literal crimes against humanity that occur in them would be ridiculous. Suburban public schools are usually somewhat better, but having attended what was considered one of the "best" public high schools in the state of Massachusetts, I can attest that over the four years I was in attendance that in addition to the usual teasing and harassment there were quite a number of incidents of serious violence. The idea of a "mutually agreed fight" is something I have never heard of at least in my educational experience - nearly all of the incidents of physical violence I witnessed or heard about were 20 on 1 assaults that often left the victim needing reconstructive surgery.
Anyone with any money puts their kid into a private school, where they certainly can't be assured that their child won't be the victim of merciless teasing, but at least private schools to some degree have more safeguards to prevent physical harm and have more stringent codes of conduct vis a vis expulsion, etc.
One also has to realize that in the US, high school violence is intrinsically linked with issues of drug use and race. High schools in America's large population centers contain diverse ethnic groups, and contrary to the 'melting-pot' utopia that everyone would like to believe, many of the teenage members of said ethnic groups really don't like each other very much. Add to that the enormous profits made on the drug trade inside US schools and the activities that go along with it and I'm surprised that many schools are as good as they are.
Oh, but Pan Am still exists! http://www.flypanam.com/ The trademark is now owned by Boston-Maine Airways. Maybe by 2017 they'll be big again!
I wonder what would have happened 15 years ago if a production designer had been told "It'll be too expensive to make a set for this scene, we'll just CG it." But I think you're probably right, it most likely is cheaper to create a set in CG than actually hire someone to design the real thing and build it on a lot - particularly for sci-fi movies. If a director for a project like "Sky Captian and the World of Tomorrow" (which has a lot of cityscape scenes reminiscent of the Blade Runner panoramas) wanted to do that film with models, sets, and in-camera F/X he'd be laughed at. So it was done with CG, and predictably that movie looked like crap, as I feel the "uncanny valley" effect that applies to CG humans can also apply to inanimate objects. But it got done and it made some money, which is pretty much what has always mattered.
There was a PBS documentary on the other day (the name of which unfortunately escapes me) about the production design of various classic films. Apparently one of the reasons the street scenes in Blade Runner were so incredibly detailed is that during the early stages of filming, the screen actors guild in L.A. went on strike for 8 weeks or so. The only folks still able to come into work and that had anything to do with no actors around were the set-building crew and production designers, and left to their own devices they went nuts. Apparently "Ridleyville" (as the main street set was jokingly referred to) ended up one of the most intricately detailed in movie history by the time the actors came back to restart shooting.