The main reason to use xenon is that you can ionize more of it due its larger size (ionization cross section), most the gas in these trusters is not ionized and is wasted. The ionization energy is insignifcant (tens of volts) compared to the expulsion voltage (tens of kilovolts).
Always remember after shutdown a nuclear plant will put out about 10% of the heat it was producing at shutdown due to the decay of short lived isotopes. So you need a safe way to remove this heat for about 24 hours or the whole thing overheats and destroys itself. Still we need nuclear power. Compared to the long term damage of coal burning, it is a lot better to use nuclear. Three mile island was only an economic loss, not a significant health hazard.
Finally starvation is beginning due to hydrocarbon based food production getting more expensive. We are on the Titanic and have already hit the iceberg. There are not enough lifeboats. Just check the CIA web site for birth rates and average age. So enjoy the music and your late night dinner cause the ship is going down.
Ion paths in an electric field were determined by streching a rubber sheet between walls whose edge heights were proportional the electric voltage on those edges. The rubber sheet would obey Laplace's eqn just like electric fields do. If you roll balls down the rubber sheet they will follow the similar paths to ions in the electric field. Conducting solutions can also be used to for a similar purpose for systems that only vary in two dimentions, like a cylindrical lens. Here a small electric probe can be set up to a servo mechanism to follow the field gradient. The probe is slaved to a pen the draws a parallel path of the probe.
Monte Hall Problem
You pick a door, now given a choice of keeping what is behind that door or switching to get the better of the two prizes that are behind the other two doors, would you switch -- of course. That is what you are doing when you switch.
Many years ago interstate exit signs were switched to white on dark green after a lot of testing. This improved readability. Never seen this on a monitor.
How did life start is the key question, not where. The earth is an ideal place, lots of water and a long-lived sun. Why left-handed, maybe the just one first "living thing", molecule, whatever started it all. In a similar vein, why matter not anti-matter universe I believe is still up in the air.
This points out why it is a good thing we are near the edge of our galaxy. One factor I don't recall seeing in estimates of the odds of other planets in the universe sustaining life is fraction of the stars near the edge of the galaxy. Lots of bad things can happen if you are too close to other stars or worse black holes.
What can you learn from a 125 miles above that you can't from ground based technology? This is awfully expensive technology and great for watching armies, military bases, etc. I can see using something like a UAV to watch a bad guy's house or car. Using a satelite for this is so much overkill.
Due to movement of fluids in your body at zero-g, or perhaps some other cause you lose your sense of smell in space. Food tastes crappy so you put lots of hot sauce on it. An astronaut told me her biggest concern was a drop of hot sauce floating around and getting in her eye. So if you smell something in space it's got to be a strong smell.
I remember reading that Kerry Mullis said that the idea of PCR (method to amplify DNA) came to him while he was driving on a mountain road. He pulled over to reflect on it because he was afraid he would be too distracted to drive safely. He won the Nobel prize and the rights were eventually sold for a billion dollars.
As difficult as making fusion a viable energy source at least there is tremendous potential payoff. As to manned exploration of space it is only for the adventure. Robots can do so much better for so much less $$.
As I understand it most musicians make money at concerts so recorded music's main purpose for muscians is to get folks to come to concerts. So music always will get recorded and be offered to us in some manner. Getting rid of the unnecessary plastic is a good idea as there is so much waste in unbought CDs etc. Therefore we always should have music available to us. In particular I like the idea of being able to buy individual songs so you are not stuck with a bunch of stuff on a CD that you never listen to.
It is my belief that the government phone data mining program only logged phone numbers and not calls. If they could associate a phone number with a terrorist then they could look at the network of calls to and from that number and try to construct webs of calling. The phone company already keeps this information for billing purposes and probably the gov't asked them to hang on to it for longer periods so that they could retrospectively mine this data for linkages between numbers. Trying to keep conversations for everyone would just be too overwhelming not to mention the time required to try to interpret what was was being said.
Skipping over the why of the big bang, at one point the universe was nothing but very hot hydrogen. Somehow from this we evolved. Yet we did. The one lost chapter in this story how did the first DNA come into existence? Truly one of the great mysteries of science. Still we have come a long way from one hundred years ago when we speculated on where does the sun's energy come from?
Much better idea is to include info about internet predators, etc. in sex ed class. If done right would do much more to prevent problems than trying to tie My Space to email accounts which many respondents have pointed out is so easy to bypass. Forbiding kids from doing something just makes it more enticing. Realistically explaining the dangers of things is more effective than prohibition.
Over Xmas, I would hear people in electronics stores using the term Blu-ray. I think it is a name with a better cachet to it and believe this has had some effect on its success. The buying public often will pay more for a "better" name so they can say "I have a Blu-ray player." Sometimes the technology or other features will take second place to the name. Remember most of the folks buying these things are not literate/. readers.
Most live performances I've been to recently crank the sound up way too much. At these levels your ears just don't work as well. Proof: put your hands over your ears to reduce the sound volume. Suddenly the music and singer's words are clearer and better sounding. I don't know if the folks running the mixer have damaged hearing or what. I hesitate to think what it must sound like to the folks seating near the speakers. Once and awhile you go to a small club where the sound is done right and realize it doesn't have to be this way. This summer went to a Dave Matthews's concert at the Columbia River Gorge. A wonderful outdoor venue. Even a long way from the stage it sounded better with my hands gentlely placed over my ears.
Picture a simple set up. TV and VCR. Now picture the mess when you add two converter boxes (so you can watch one channel and record another). This assumes converter boxes can be set to output on two different channels. Combine output of both boxes using a splitter (in reverse), feed this to the VCR which then feeds the TV. Minimum you need 3 remotes. This assumes converter boxes won't both be controlled by one remote. Ugly. Bottom line a lot of working analog TVs and VCRs are going into the trash.
Take thermodynamics, we experience that two objects in contact come to the same temperature. Einstein felt thermodyamics was on the most secure foundation. On the other hand quantum mechanics is a mathematical construct to explain the behaviour of things on an atomic scale. We believe it because it works so well even though it is not intuitive at all. For example the double slit experiment which has been performed with molecules (C60) is certainly not intuitive. The absolute speed of light is another example that comes to mind.
It is still amazing to me the leaps that the great scientists made in the early 20th century beyond experience to explain the world we exist in. Planck, Einstein, Schroedinger, Heisenberg, Dirac, and many others made these leaps. It must have been so astounding to have been a scientist then and see this unfold.
Converting digital to analog regardless of recorded format will introduce noise unless you have a really good DAC carefully shielded from electrically noisy power supplies etc in your PC. Sure the DACs can be linear, have low distortion, but they better be in well shielded environment to gain any advantage over a 128 kbps mp3 file quality.
My current laptop with XP and Office is using about 13Gb of disk. No movie files, etc. So this could be my C: drive right now and I could use regular flash for data storage. Add a more efficient display (LED lit or eventually organic polymer) and new generation of efficient processor and you have a great portable system that would serve the needs of most folks.
Ever heard of continental drift? Real concern about global warming is potential for positive feedback. Less snow cover means more heat absorbed means less snow cover. Of course in 50 or so years the cause of global warming will be fixed because most of the fossil fuel will have been burned. Mother nature has her way of taking care of species that overpopulate their environment. No birth control means death control big time.
In the year of Woodstock, 1969, memory for a PDP-8 was about $5000 for 4096 12-bit words of memory. In todays $ that would be a $3 a byte. This was magnetic core memory so you could power off and not have to reload. What's memory now -- less than $1 for 10 Mbytes. Ah those were the days.
Slashdot Mirror
The main reason to use xenon is that you can ionize more of it due its larger size (ionization cross section), most the gas in these trusters is not ionized and is wasted. The ionization energy is insignifcant (tens of volts) compared to the expulsion voltage (tens of kilovolts).
Always remember after shutdown a nuclear plant will put out about 10% of the heat it was producing at shutdown due to the decay of short lived isotopes. So you need a safe way to remove this heat for about 24 hours or the whole thing overheats and destroys itself. Still we need nuclear power. Compared to the long term damage of coal burning, it is a lot better to use nuclear. Three mile island was only an economic loss, not a significant health hazard. Finally starvation is beginning due to hydrocarbon based food production getting more expensive. We are on the Titanic and have already hit the iceberg. There are not enough lifeboats. Just check the CIA web site for birth rates and average age. So enjoy the music and your late night dinner cause the ship is going down.
Ion paths in an electric field were determined by streching a rubber sheet between walls whose edge heights were proportional the electric voltage on those edges. The rubber sheet would obey Laplace's eqn just like electric fields do. If you roll balls down the rubber sheet they will follow the similar paths to ions in the electric field. Conducting solutions can also be used to for a similar purpose for systems that only vary in two dimentions, like a cylindrical lens. Here a small electric probe can be set up to a servo mechanism to follow the field gradient. The probe is slaved to a pen the draws a parallel path of the probe.
Monte Hall Problem You pick a door, now given a choice of keeping what is behind that door or switching to get the better of the two prizes that are behind the other two doors, would you switch -- of course. That is what you are doing when you switch.
Many years ago interstate exit signs were switched to white on dark green after a lot of testing. This improved readability. Never seen this on a monitor.
How did life start is the key question, not where. The earth is an ideal place, lots of water and a long-lived sun. Why left-handed, maybe the just one first "living thing", molecule, whatever started it all. In a similar vein, why matter not anti-matter universe I believe is still up in the air.
This points out why it is a good thing we are near the edge of our galaxy. One factor I don't recall seeing in estimates of the odds of other planets in the universe sustaining life is fraction of the stars near the edge of the galaxy. Lots of bad things can happen if you are too close to other stars or worse black holes.
What can you learn from a 125 miles above that you can't from ground based technology? This is awfully expensive technology and great for watching armies, military bases, etc. I can see using something like a UAV to watch a bad guy's house or car. Using a satelite for this is so much overkill.
Due to movement of fluids in your body at zero-g, or perhaps some other cause you lose your sense of smell in space. Food tastes crappy so you put lots of hot sauce on it. An astronaut told me her biggest concern was a drop of hot sauce floating around and getting in her eye. So if you smell something in space it's got to be a strong smell.
I remember reading that Kerry Mullis said that the idea of PCR (method to amplify DNA) came to him while he was driving on a mountain road. He pulled over to reflect on it because he was afraid he would be too distracted to drive safely. He won the Nobel prize and the rights were eventually sold for a billion dollars.
As difficult as making fusion a viable energy source at least there is tremendous potential payoff. As to manned exploration of space it is only for the adventure. Robots can do so much better for so much less $$.
As I understand it most musicians make money at concerts so recorded music's main purpose for muscians is to get folks to come to concerts. So music always will get recorded and be offered to us in some manner. Getting rid of the unnecessary plastic is a good idea as there is so much waste in unbought CDs etc. Therefore we always should have music available to us. In particular I like the idea of being able to buy individual songs so you are not stuck with a bunch of stuff on a CD that you never listen to.
It is my belief that the government phone data mining program only logged phone numbers and not calls. If they could associate a phone number with a terrorist then they could look at the network of calls to and from that number and try to construct webs of calling. The phone company already keeps this information for billing purposes and probably the gov't asked them to hang on to it for longer periods so that they could retrospectively mine this data for linkages between numbers. Trying to keep conversations for everyone would just be too overwhelming not to mention the time required to try to interpret what was was being said.
Skipping over the why of the big bang, at one point the universe was nothing but very hot hydrogen. Somehow from this we evolved. Yet we did. The one lost chapter in this story how did the first DNA come into existence? Truly one of the great mysteries of science. Still we have come a long way from one hundred years ago when we speculated on where does the sun's energy come from?
Much better idea is to include info about internet predators, etc. in sex ed class. If done right would do much more to prevent problems than trying to tie My Space to email accounts which many respondents have pointed out is so easy to bypass. Forbiding kids from doing something just makes it more enticing. Realistically explaining the dangers of things is more effective than prohibition.
Over Xmas, I would hear people in electronics stores using the term Blu-ray. I think it is a name with a better cachet to it and believe this has had some effect on its success. The buying public often will pay more for a "better" name so they can say "I have a Blu-ray player." Sometimes the technology or other features will take second place to the name. Remember most of the folks buying these things are not literate /. readers.
Most live performances I've been to recently crank the sound up way too much. At these levels your ears just don't work as well. Proof: put your hands over your ears to reduce the sound volume. Suddenly the music and singer's words are clearer and better sounding. I don't know if the folks running the mixer have damaged hearing or what. I hesitate to think what it must sound like to the folks seating near the speakers. Once and awhile you go to a small club where the sound is done right and realize it doesn't have to be this way. This summer went to a Dave Matthews's concert at the Columbia River Gorge. A wonderful outdoor venue. Even a long way from the stage it sounded better with my hands gentlely placed over my ears.
I live 5 min from my video rental store. So unless the cost is a lot less, I doubt I would want to wait the longer time for a download.
Picture a simple set up. TV and VCR. Now picture the mess when you add two converter boxes (so you can watch one channel and record another). This assumes converter boxes can be set to output on two different channels. Combine output of both boxes using a splitter (in reverse), feed this to the VCR which then feeds the TV. Minimum you need 3 remotes. This assumes converter boxes won't both be controlled by one remote. Ugly. Bottom line a lot of working analog TVs and VCRs are going into the trash.
FF 3.0, IE 8.0 and XP SP3 betas all have good reviews, great news for us. Vista sp1 not so much. Anything else to be excited about in the pipeline.
Take thermodynamics, we experience that two objects in contact come to the same temperature. Einstein felt thermodyamics was on the most secure foundation. On the other hand quantum mechanics is a mathematical construct to explain the behaviour of things on an atomic scale. We believe it because it works so well even though it is not intuitive at all. For example the double slit experiment which has been performed with molecules (C60) is certainly not intuitive. The absolute speed of light is another example that comes to mind.
It is still amazing to me the leaps that the great scientists made in the early 20th century beyond experience to explain the world we exist in. Planck, Einstein, Schroedinger, Heisenberg, Dirac, and many others made these leaps. It must have been so astounding to have been a scientist then and see this unfold.
Converting digital to analog regardless of recorded format will introduce noise unless you have a really good DAC carefully shielded from electrically noisy power supplies etc in your PC. Sure the DACs can be linear, have low distortion, but they better be in well shielded environment to gain any advantage over a 128 kbps mp3 file quality.
My current laptop with XP and Office is using about 13Gb of disk. No movie files, etc. So this could be my C: drive right now and I could use regular flash for data storage. Add a more efficient display (LED lit or eventually organic polymer) and new generation of efficient processor and you have a great portable system that would serve the needs of most folks.
Ever heard of continental drift? Real concern about global warming is potential for positive feedback. Less snow cover means more heat absorbed means less snow cover. Of course in 50 or so years the cause of global warming will be fixed because most of the fossil fuel will have been burned. Mother nature has her way of taking care of species that overpopulate their environment. No birth control means death control big time.
In the year of Woodstock, 1969, memory for a PDP-8 was about $5000 for 4096 12-bit words of memory. In todays $ that would be a $3 a byte. This was magnetic core memory so you could power off and not have to reload. What's memory now -- less than $1 for 10 Mbytes. Ah those were the days.