the "discrepancies" turned out to be errors in the measurements. Of course I can't say there isn't something so dark and far away that it hasn't been discovered, but there is no longer a problem that "requires" another massive body in the solar system
we also know it's density, due to the orbital period of it and it's "moon". Based on its density (and it's lack of a significant atmosphere) there can't be much rock.
I know I was taught Europe was it's ownn continent. And that some people wanted India to be it's own continent.
But why is Europe considered a continent? India is at least on a different techtonic plate than asia. I don't beleive that's the case with Europe and Asia.
Dare I speculate that the reason Europe is considered it's own continent is due to the history of our planet's continents? Please, someone tell me there's a better reason.
Both Geoff Marcy and Paul Butler (I've never met Vogt) are smart guys and are the leaders in the field of radial velocity planet detection. However, I think Geoff went a little far with his remarks (as many slashdotters have already pointed out). I wonder if he made the over the edge remarks about frightening and knowing it all just to be exciting for the press, not that that would excuse it. Pay attention to their first class observations, but don't take their theoretical comments as the final word.
Presently, there's no good reason to beleive that the two criteria for distinguishing between planets and brown dwarfs (mass and how they formed) are consistant. It could be that objects with larger masses form one way. Objects with smaller masses form another. However, it's also possible (and IMHO more likely) that the two formation mechanisms can both produce objects with the same masses somewhere near the transition point or maybe there's a mass range that neither mechanism can produce. Finding a 17 M_J object around a star with another planet shouldn't be that suprising. We've already found planets around stars that have 1 M_sol binary companions (although farther away). Since it's lower mass, it can be closer in.
What's this previous research that 17 M_J planets didn't exist? Marcy and Butler looked at hundreds of stars and didn't find any, but the Geneva group which looked at many more stars (but with larger noise) did. So we already knew they were out there. It's still nice to get a better handle on their frequency, but I certainly wouldn't say previous reserach disproved their existance.
About the other system... Finding two planets in resonant orbits, should not be considered very suprising either. In fact the first extrasolar planets discovered were in resonant orbits (three around PSR 1527 (I think I got the ID right)). Maybe it was suprising then, but a plethora of papers have been published on the system, so that should have been expected to show up eventually. True some formation mechanisms require a stage with large tidal effects (red giant for the PSR system), but those theorists can use the PMS stage for this system, although that may put some interesting requirements on the time to form the planets.
Oh yeah, analyzing resonant orbits from radial velocity data can be especially complicated. So I wouldn't be too suprised if one of them turned out to be a mistake. On the other hand, the complications can provide very strong and dramatic confirmation of resonant orbits (via the objects mutual pertubations), if the data is good enough and the time scales are short compared to the observations. They may already have that (in which case they were very cautous) or they maybe announcing it hoping this critiism will help them justify making more observations. I haven't seen the data yet, so I just don't know...
Anyway, nice work, guys. Please keep the observations coming.
I was one of those physics majors in the math classes. And I was always one of the math savvy among the physics crowd. But I only really worked at "applied" math classes. I only sat in the first few weeks of classes like analysis, algebra, topology, lie groups, number theory,.... They seemed like a lot of hard work for silly little things that weren't that useful. Now that I'm trying to take classes in quantum field theory, I'm getting smacked around big time. Now I almost wish I had spent the time to learn that stuff for real. As it is, I will likely never really understand as much physics as I'd like to, just because I wasn't willing to hack the math. And while I'm not anything special, I did take more math classes than most physcists in my class.
There's some truth to it. Although, I like to think of it more along the lines of people who chose not to hack it, rather than people who can't.
This is very interesting. Of course the popular article is short on details. Of interest to us astrophysicists is how many, how massive, and how large z, and how large a volume did they survey. We already know of a few clusters nearly 10^5 M_sol at z=0.5-0.8. I'll have to ask for details once they get back from the HEAD meeting...
But, in any case, the claim of hundreds is very exciting. In a universe with a large \Omega (both matter and dark matter, but not lambda or quintesence), massive clusters become extremely rare at large redshifts. That's why the person claims this will help measure omega very accurately. Unfortunately, there is a degeneracey (I believe the primary degeneracey is how much the luminous matter distribution is representative of the dark matter distributions, but I'd have to check to be sure.) and this observation alone can not determine Omega. However, when combined with other observations (such as supernovae and CMB), Omega can indeed be tightly constrained. We're closing in...
Angular momentum creates a barrier in terms of the effective potential. Basically, unless the material can find a way to dissipate angular momentum, it can't fall to the center of the cluster.
A little while back I knew someone who sniffed the local network and looked at where attacks were directed. Linux boxes were targeted more than anything else. We speculated that they're common enough that lots of script kiddies can get their hands on one for learning, easy enough for someone clue-limited to use, and powerful enough to be worth hacking. Getting in a linux box is much more useful than a windows machine. Besides, if they're looking at what OS I'm running, then they might tailor attacks based on that. Of course, if you really wanted to find out what I'm running, it wouldn't be that hard. (One of these days I'm going to recompile my kernel to use non-standard TCP headers.)
How do you know? Sometimes I set my proxy server to fake being an Windows/IE combo. I figure it's good for security when visiting sites of dubious integrity...
> Not to turn this
> into a religious argument, but how many Christians (to pick one group in particular) would be Christians if they, at age
> 18, having never heard of any religion, were given a Bible?
I certainly understand your point. I think many would not, but I also think many would. IMHO, I think there may be a correlation between how committed a person is and whether their faith is based mostly on their upbringing or mostly on their personal quest for spirituality. And by committed I don't mean how often they wake up early on a Sunday morning, but rather something more like how much of their life they live differently because they are Christian.
> What's the saying about the only difference between a
> religion and a cult is that the religion has been around longer?
I've wondered this myself. I've been given an "official" definitions or algorithms that I couldn't immediately poke a whole in, but I forget what is was.
astro --- Proud to be a radially conservative Christian (Don't worry, that does not imply several of the negative things typically associated with other large conservative Christian groups.)
I've been using NetBank and UsaBancShares for about a year now and both seem to work find under linux. For a while, you had to use a different link to the login page for NetBank, but that was fixed (after I complained). I'm not sure whether NetBank did something or if a new version of Netscape fixed it. I did have a general problem logging into UsaBancShares for a couple of days at some point. But that was both windows and linux, if it makes you feel any better
> After all, it seems to me that color blindness can't help anyone, but remains so common simply because it doesn't hurt your chances of productive success very much to have the trait.
One problem is that well meaning people will say, I don't see how this could possibly be a valuable trait. However, unless we completely understand all about DNA and humans (unlikely to ever happen), we just won't know. We could very easily attempt to do good, for example by eliminating color blindness. If it turns out (I'm not saying it's true or is likely. It's just an example...) that color blindness is linked to resistance to some disease or ability of the eye to withstand larger UV fluxes, then in some unknown time in the future, then that decision to eliminate color blindness could come back to haunt us. Instead of having some people who are resistant to the disease or increased UV radiation, nobody would be. In the language of population dynamics, reducing genetic diversity will likely lead to bigger booms, but also bigger busts. Is reducing color blindness worth the risk? I don't think so. Obviously for more serious problems (e.g. diabetes) it becomes a tougher call.
>"The fundamental problem is that people are causing changes much faster than processes like geology and evolution can react."
> Just to clarify (I think we agree here), life will continue to evolve, but it appears that this stage of evolution entails a mass extinction. Perhaps even our own.
Yes, what I said was technically incorrect, but you figured out what I meant.
> This last bit of your post made me wonder: Assuming we survive our follies, how will life evolve 'around us' afterwards? In other words, what traits might our behaviours be encouraging from the species that surround us?
> By changing the environment so dramatically, might we be encouraging the ability to adapt quickly?
I beleive there's already examples of this. I'm terrible about remembering details, but I seem to remember some body of water had been polluted with chemicals, then legislation was passed to prevent such gross pollution. In reality it was then polluted by some thing else that was introduced intending to help clean up the pollution. Then they figured out to stop trying to fix it themselves and just let the lake (or river or whatever it was) clean itself up. Evidently, someone did a study and found that the species of something (probably very simple like bacteria, algae, etc.) that were left could evolve more quickly than similar somethings taken from anotehr water source that hadn't gone through such truama.
Anyone know what I'm thinking of? A reference would be great. Or is this something that has been done in multiple locations and is commonly known by biologists?
A friend asked me about this article and in particular if we could reverse the green house effect. Here's my explanation. Please correct me if any of this is wrong.
Sulfuric acid comes back down relatively quickly, so people will notice the water is becoming acidic as more sulfer is released into the atmosphere. If they were to stop releasing sulfer into the atmosphere then the rain will basically stay at whatever level of acidity it was before people cared enough to stop. Sure it's getting worse and people should do something about it, but I doubt humans will become extinct because of the sulfer build-up (unless there's some long term health
effect of sulfer that people don't realize until it's too late). While it's almost impossible to significantly reduce the levels of sulfer in the atmosphere, it's simple (in theory) to stop increasing it.
The greenhouse effect is another story. The build up of individual chemicals like sulfer and carbon dioxide in principle could be stopped
right away, if people were smart enough to do it. But he build up of heat doesn't stop once you park the cars and shut down the factories. It's a near certainty that average temperatures will continue to increase steadily for at least the next few decades, even if people park all the cars, shut down all the factories, and stop burning all the rain forests. At this point there's nothing we can do to prevent that.
How long the increase will last, assuming people did everything possible to stop it immediately, is not known. Good data to use as inputs to climate models is only avaliable for about 50 years. So scientists can use 25 years for input and 25 years for testing their model. On the basis it works for the most recent 25, they say it's reasonable to apply them to the next 25. Temperatures will probably keep increasing after then, but models become significantly more uncertain. They point out that it seems silly to try to model that far in the future when the biggest uncertainty in their models is what people will do. They often
run three or four scenarios roughly approximating people not changing a thing, people continuing to increase pollution at the current rates, people immediately stopping everything, and some approximation of whatever politicians are currently talking about.
Anyway, the most talked about consequences are things like increased seasonal variability making the same location go from dessert to flooded
every year, melting of polar ice caps, flooding of coastal towns, etc.. Some of these are bad, but it'll be gradual, so people can just evacuate the coastal cities that tend to be old anyway. The real concern is that there will be some run-away effect that will cause the severity to increase and other problems. Things like ice cover matter a lot, because they reflect a lot of sun light. If temperatures increase, you melt ice, the earth reflects less light, it gets hotter, you melt more ice, and the effect continues getting bigger until something else more significant take over. Since we don't know how bad it will get before something else takes over or what that other effect will be, it's a big concern.
I suspect the worst consequences will be unexpected. Predicting heat transport is relatively easy when compared to predicting biology. Increased temperatures cause insects and bacteria to reproduce faster. Maybe the real concern should be insects taking over and spreading lots of weird diseases to people, animals, and crops. (Especially, if farmers
take to the idea of using genetically engineered crops, then it would be much easier for entire crops to be wiped out by one crop disease.)
The recent cool down (~few years) has been due to increased volcanic activity. Maybe we'll be "saved" from the Greenhouse effect by increased
temperatures somehow increasing volcanic activity, only wiping out a few cities in unfortunate locations. The bottom line is that we can reasonablely predict some bad things that will almost certainly happen in the next few decades. We can identify some very bad things that may happen over a slightly longer time scale, but we can't have much confidence in our models, since there's essentially no avaliable data to test such predictions. And the biggest concern is that there's something very big that will happen
if we cross over some boundary, but we don't know that that will be or where the line is.
I don't think anybody's come up with any "reasonable" idea for how humans can reverse the Greenhouse effect. Obviously, eliminating atmospheric pollution will "help", but the effect will continue to get stronger over the next few decades regardless. So in the next thiry years we don't konw any way we can slow it down, let alone reverse it. It will only help on a much
longer timescale, possibly as short as 50 years, but more likely on the order of hundreds of years. Obviously, continuing to pump stuff into the
atmosphere only digs us into a deeper hole. What we can do is decrease the rate at which the greenhouse effect accelerates and postpone the impending problems. That may buy people some more time to come up with a good idea. (I'm tempted
to say that such an idea seems almost impossible given the severity and massive size of the problem, but I guess that's what people always say before a break through.) On 1000 year and longer timescales there are geological processes
that may help. The fundamental problem is that people are causing changes much faster than processes like geology and evolution can react.
You can annotate latex documents. Just put a comment in the source code, using % . That works for me when I'm writing a paper with others. I just insert something like
% JOE: Fill in the above numbers once you rerun the simulation.
It's easily identifiable, can be searched for, and directed to who I want. What more could you want?
Some people I know also use footnotes for this purpose.
Just give guidelines. If your class focuses on data structures require an array, hash table, linked list, stack, queue, red-black tree, etc. If your class is on discrete algorithms quick sort, radix sort, random number generator, etc. If your class is on numerical techniques Romberg integration, Runge-Kutta integration, Monte Carlo integration, or whatever.
If your class is less focused, you could say they must use everything on a list, or you could let them choose one thing from each of several lists.
Also specify what they're allowed to use. For example, if they use STL, implementing a stack doesn't require understanding it. If they use a linear algebra package, finding eigenvalues of a triangular matrix is trivial. However, if they code these things themselves, it will require they understand how the algorithms work, but also require much more of their time. I guess whether you allow things like qsort is a matter of what the point of the class is and your (and their) taste(s).
Everyone in my department uses LaTeX. If you have lots of equations, it's really a great thing. And besides, many of the journals accept electronic submissions in LaTeX, but nothing else. Once you get used to it, it's no big deal. Kind of like ls, rm, cd, mkdir, etc..
srm is a "secure" rm it overwrites the data on the HD in addition to unlinking the inode. However, I beleive if one were extremely dedicated, it would sometimes be possible to recover such data.
When I'm doing product/service comparisons I normally throw out any options that make it hard for me to get a price. I figure they're likely to be too expensive, and definitely an obnoxious company.
So far Rambus's agreements only give them ~0.5-3% royalties, depending on what type of memory and which manufactuer. So even if the royalties were charged off the retail price (I don't htink this is the case.), and they got 3% royalties on everything (this is an approximate upper bound), then the increase in memory costs due to Rambus enforcing it's patents would only be ~0.03$/MB.
Presently, both RDRAM and DDRRAM are very expensive. This isn't because of rambus taking lots of royalties. It's because the products are still new, people who buy early are willing to pay extra, they haven't become comodities yet, memory manufactuers still haven't matured their manufacturing and testing to the same extend they have for SDRAM, etc..
So I'm not worried about memory prices soaring due to Rambus. I'm confident that with time prices on RDRAM and DDRRAM will come down.
Slashdot Mirror
the "discrepancies" turned out to be errors in the measurements. Of course I can't say there isn't something so dark and far away that it hasn't been discovered, but there is no longer a problem that "requires" another massive body in the solar system
we also know it's density, due to the orbital period of it and it's "moon". Based on its density (and it's lack of a significant atmosphere) there can't be much rock.
I know I was taught Europe was it's ownn continent. And that some people wanted India to be it's own continent.
But why is Europe considered a continent? India is at least on a different techtonic plate than asia. I don't beleive that's the case with Europe and Asia.
Dare I speculate that the reason Europe is considered it's own continent is due to the history of our planet's continents? Please, someone tell me there's a better reason.
the center of mass is actually outside of pluto
Both Geoff Marcy and Paul Butler (I've never met Vogt) are smart guys and are the leaders in the field of radial velocity planet detection. However, I think Geoff went a little far with his remarks (as many slashdotters have already pointed out). I wonder if he made the over the edge remarks about frightening and knowing it all just to be exciting for the press, not that that would excuse it. Pay attention to their first class observations, but don't take their theoretical comments as the final word.
Presently, there's no good reason to beleive that the two criteria for distinguishing between planets and brown dwarfs (mass and how they formed) are consistant. It could be that objects with larger masses form one way. Objects with smaller masses form another. However, it's also possible (and IMHO more likely) that the two formation mechanisms can both produce objects with the same masses somewhere near the transition point or maybe there's a mass range that neither mechanism can produce. Finding a 17 M_J object around a star with another planet shouldn't be that suprising. We've already found planets around stars that have 1 M_sol binary companions (although farther away). Since it's lower mass, it can be closer in.
What's this previous research that 17 M_J planets didn't exist? Marcy and Butler looked at hundreds of stars and didn't find any, but the Geneva group which looked at many more stars (but with larger noise) did. So we already knew they were out there. It's still nice to get a better handle on their frequency, but I certainly wouldn't say previous reserach disproved their existance.
About the other system... Finding two planets in resonant orbits, should not be considered very suprising either. In fact the first extrasolar planets discovered were in resonant orbits (three around PSR 1527 (I think I got the ID right)). Maybe it was suprising then, but a plethora of papers have been published on the system, so that should have been expected to show up eventually. True some formation mechanisms require a stage with large tidal effects (red giant for the PSR system), but those theorists can use the PMS stage for this system, although that may put some interesting requirements on the time to form the planets.
Oh yeah, analyzing resonant orbits from radial velocity data can be especially complicated. So I wouldn't be too suprised if one of them turned out to be a mistake. On the other hand, the complications can provide very strong and dramatic confirmation of resonant orbits (via the objects mutual pertubations), if the data is good enough and the time scales are short compared to the observations. They may already have that (in which case they were very cautous) or they maybe announcing it hoping this critiism will help them justify making more observations. I haven't seen the data yet, so I just don't know...
Anyway, nice work, guys. Please keep the observations coming.
Whoops, wrong paper. Sorry. Well, here are just the radial velocity curves.
Here's a link to the scientific paper
Anyone else notice that it looks like more the "more evolved" specicies have less base pairs?
Is this just the result of my pre-Coperican biases? Or some observational bias that they wouldn't have printed numbers for small spieces?
Does anyone know if this pattern I've inferred holds true with a larger database of species?
I was one of those physics majors in the math classes. And I was always one of the math savvy among the physics crowd. But I only really worked at "applied" math classes. I only sat in the first few weeks of classes like analysis, algebra, topology, lie groups, number theory,.... They seemed like a lot of hard work for silly little things that weren't that useful. Now that I'm trying to take classes in quantum field theory, I'm getting smacked around big time. Now I almost wish I had spent the time to learn that stuff for real. As it is, I will likely never really understand as much physics as I'd like to, just because I wasn't willing to hack the math. And while I'm not anything special, I did take more math classes than most physcists in my class.
There's some truth to it. Although, I like to think of it more along the lines of people who chose not to hack it, rather than people who can't.
sorry, I meant nearly 10^15 M_sol, not 10^5 M_sol. Technically, it's 10^15 M_sol h^-1, where h = H_o/(100 km/s/Mpc).
This is very interesting. Of course the popular article is short on details. Of interest to us astrophysicists is how many, how massive, and how large z, and how large a volume did they survey. We already know of a few clusters nearly 10^5 M_sol at z=0.5-0.8. I'll have to ask for details once they get back from the HEAD meeting...
But, in any case, the claim of hundreds is very exciting. In a universe with a large \Omega (both matter and dark matter, but not lambda or quintesence), massive clusters become extremely rare at large redshifts. That's why the person claims this will help measure omega very accurately. Unfortunately, there is a degeneracey (I believe the primary degeneracey is how much the luminous matter distribution is representative of the dark matter distributions, but I'd have to check to be sure.) and this observation alone can not determine Omega. However, when combined with other observations (such as supernovae and CMB), Omega can indeed be tightly constrained. We're closing in...
Angular momentum creates a barrier in terms of the effective potential. Basically, unless the material can find a way to dissipate angular momentum, it can't fall to the center of the cluster.
A little while back I knew someone who sniffed the local network and looked at where attacks were directed. Linux boxes were targeted more than anything else. We speculated that they're common enough that lots of script kiddies can get their hands on one for learning, easy enough for someone clue-limited to use, and powerful enough to be worth hacking. Getting in a linux box is much more useful than a windows machine. Besides, if they're looking at what OS I'm running, then they might tailor attacks based on that. Of course, if you really wanted to find out what I'm running, it wouldn't be that hard. (One of these days I'm going to recompile my kernel to use non-standard TCP headers.)
How do you know? Sometimes I set my proxy server to fake being an Windows/IE combo. I figure it's good for security when visiting sites of dubious integrity...
> Not to turn this
> into a religious argument, but how many Christians (to pick one group in particular) would be Christians if they, at age
> 18, having never heard of any religion, were given a Bible?
I certainly understand your point. I think many would not, but I also think many would. IMHO, I think there may be a correlation between how committed a person is and whether their faith is based mostly on their upbringing or mostly on their personal quest for spirituality. And by committed I don't mean how often they wake up early on a Sunday morning, but rather something more like how much of their life they live differently because they are Christian.
> What's the saying about the only difference between a
> religion and a cult is that the religion has been around longer?
I've wondered this myself. I've been given an "official" definitions or algorithms that I couldn't immediately poke a whole in, but I forget what is was.
astro --- Proud to be a radially conservative Christian (Don't worry, that does not imply several of the negative things typically associated with other large conservative Christian groups.)
I've been using NetBank and UsaBancShares for about a year now and both seem to work find under linux. For a while, you had to use a different link to the login page for NetBank, but that was fixed (after I complained). I'm not sure whether NetBank did something or if a new version of Netscape fixed it. I did have a general problem logging into UsaBancShares for a couple of days at some point. But that was both windows and linux, if it makes you feel any better
> After all, it seems to me that color blindness can't help anyone, but remains so common simply because it doesn't hurt your chances of productive success very much to have the trait.
One problem is that well meaning people will say, I don't see how this could possibly be a valuable trait. However, unless we completely understand all about DNA and humans (unlikely to ever happen), we just won't know. We could very easily attempt to do good, for example by eliminating color blindness. If it turns out (I'm not saying it's true or is likely. It's just an example...) that color blindness is linked to resistance to some disease or ability of the eye to withstand larger UV fluxes, then in some unknown time in the future, then that decision to eliminate color blindness could come back to haunt us. Instead of having some people who are resistant to the disease or increased UV radiation, nobody would be. In the language of population dynamics, reducing genetic diversity will likely lead to bigger booms, but also bigger busts. Is reducing color blindness worth the risk? I don't think so. Obviously for more serious problems (e.g. diabetes) it becomes a tougher call.
>"The fundamental problem is that people are causing changes much faster than processes like geology and evolution can react."
> Just to clarify (I think we agree here), life will continue to evolve, but it appears that this stage of evolution entails a mass extinction. Perhaps even our own.
Yes, what I said was technically incorrect, but you figured out what I meant.
> This last bit of your post made me wonder: Assuming we survive our follies, how will life evolve 'around us' afterwards? In other words, what traits might our behaviours be encouraging from the species that surround us?
> By changing the environment so dramatically, might we be encouraging the ability to adapt quickly?
I beleive there's already examples of this. I'm terrible about remembering details, but I seem to remember some body of water had been polluted with chemicals, then legislation was passed to prevent such gross pollution. In reality it was then polluted by some thing else that was introduced intending to help clean up the pollution. Then they figured out to stop trying to fix it themselves and just let the lake (or river or whatever it was) clean itself up. Evidently, someone did a study and found that the species of something (probably very simple like bacteria, algae, etc.) that were left could evolve more quickly than similar somethings taken from anotehr water source that hadn't gone through such truama.
Anyone know what I'm thinking of? A reference would be great. Or is this something that has been done in multiple locations and is commonly known by biologists?
A friend asked me about this article and in particular if we could reverse the green house effect. Here's my explanation. Please correct me if any of this is wrong.
Sulfuric acid comes back down relatively quickly, so people will notice the water is becoming acidic as more sulfer is released into the atmosphere. If they were to stop releasing sulfer into the atmosphere then the rain will basically stay at whatever level of acidity it was before people cared enough to stop. Sure it's getting worse and people should do something about it, but I doubt humans will become extinct because of the sulfer build-up (unless there's some long term health
effect of sulfer that people don't realize until it's too late). While it's almost impossible to significantly reduce the levels of sulfer in the atmosphere, it's simple (in theory) to stop increasing it.
The greenhouse effect is another story. The build up of individual chemicals like sulfer and carbon dioxide in principle could be stopped
right away, if people were smart enough to do it. But he build up of heat doesn't stop once you park the cars and shut down the factories. It's a near certainty that average temperatures will continue to increase steadily for at least the next few decades, even if people park all the cars, shut down all the factories, and stop burning all the rain forests. At this point there's nothing we can do to prevent that.
How long the increase will last, assuming people did everything possible to stop it immediately, is not known. Good data to use as inputs to climate models is only avaliable for about 50 years. So scientists can use 25 years for input and 25 years for testing their model. On the basis it works for the most recent 25, they say it's reasonable to apply them to the next 25. Temperatures will probably keep increasing after then, but models become significantly more uncertain. They point out that it seems silly to try to model that far in the future when the biggest uncertainty in their models is what people will do. They often
run three or four scenarios roughly approximating people not changing a thing, people continuing to increase pollution at the current rates, people immediately stopping everything, and some approximation of whatever politicians are currently talking about.
Anyway, the most talked about consequences are things like increased seasonal variability making the same location go from dessert to flooded
every year, melting of polar ice caps, flooding of coastal towns, etc.. Some of these are bad, but it'll be gradual, so people can just evacuate the coastal cities that tend to be old anyway. The real concern is that there will be some run-away effect that will cause the severity to increase and other problems. Things like ice cover matter a lot, because they reflect a lot of sun light. If temperatures increase, you melt ice, the earth reflects less light, it gets hotter, you melt more ice, and the effect continues getting bigger until something else more significant take over. Since we don't know how bad it will get before something else takes over or what that other effect will be, it's a big concern.
I suspect the worst consequences will be unexpected. Predicting heat transport is relatively easy when compared to predicting biology. Increased temperatures cause insects and bacteria to reproduce faster. Maybe the real concern should be insects taking over and spreading lots of weird diseases to people, animals, and crops. (Especially, if farmers
take to the idea of using genetically engineered crops, then it would be much easier for entire crops to be wiped out by one crop disease.)
The recent cool down (~few years) has been due to increased volcanic activity. Maybe we'll be "saved" from the Greenhouse effect by increased
temperatures somehow increasing volcanic activity, only wiping out a few cities in unfortunate locations. The bottom line is that we can reasonablely predict some bad things that will almost certainly happen in the next few decades. We can identify some very bad things that may happen over a slightly longer time scale, but we can't have much confidence in our models, since there's essentially no avaliable data to test such predictions. And the biggest concern is that there's something very big that will happen
if we cross over some boundary, but we don't know that that will be or where the line is.
I don't think anybody's come up with any "reasonable" idea for how humans can reverse the Greenhouse effect. Obviously, eliminating atmospheric pollution will "help", but the effect will continue to get stronger over the next few decades regardless. So in the next thiry years we don't konw any way we can slow it down, let alone reverse it. It will only help on a much
longer timescale, possibly as short as 50 years, but more likely on the order of hundreds of years. Obviously, continuing to pump stuff into the
atmosphere only digs us into a deeper hole. What we can do is decrease the rate at which the greenhouse effect accelerates and postpone the impending problems. That may buy people some more time to come up with a good idea. (I'm tempted
to say that such an idea seems almost impossible given the severity and massive size of the problem, but I guess that's what people always say before a break through.) On 1000 year and longer timescales there are geological processes
that may help. The fundamental problem is that people are causing changes much faster than processes like geology and evolution can react.
People have already pointed you to lyx/klyx.
You can annotate latex documents. Just put a comment in the source code, using % .
That works for me when I'm writing a paper with others. I just insert something like
% JOE: Fill in the above numbers once you rerun the simulation.
It's easily identifiable, can be searched for, and directed to who I want. What more could you want?
Some people I know also use footnotes for this purpose.
Just give guidelines. If your class focuses on data structures require an array, hash table, linked list, stack, queue, red-black tree, etc. If your class is on discrete algorithms quick sort, radix sort, random number generator, etc.
If your class is on numerical techniques Romberg integration, Runge-Kutta integration, Monte Carlo integration, or whatever.
If your class is less focused, you could say they must use everything on a list, or you could let them choose one thing from each of several lists.
Also specify what they're allowed to use. For example, if they use STL, implementing a stack doesn't require understanding it. If they use a linear algebra package, finding eigenvalues of a triangular matrix is trivial. However, if they code these things themselves, it will require they understand how the algorithms work, but also require much more of their time. I guess whether you allow things like qsort is a matter of what the point of the class is and your (and their) taste(s).
Everyone in my department uses LaTeX. If you have lots of equations, it's really a great thing. And besides, many of the journals accept electronic submissions in LaTeX, but nothing else. Once you get used to it, it's no big deal. Kind of like ls, rm, cd, mkdir, etc..
srm is a "secure" rm
it overwrites the data on the HD in addition to unlinking the inode. However, I beleive if one were extremely dedicated, it would sometimes be possible to recover such data.
When I'm doing product/service comparisons I normally throw out any options that make it hard for me to get a price. I figure they're likely to be too expensive, and definitely an obnoxious company.
So far Rambus's agreements only give them ~0.5-3% royalties, depending on what type of memory and which manufactuer. So even if the royalties were charged off the retail price (I don't htink this is the case.), and they got 3% royalties on everything (this is an approximate upper bound), then the increase in memory costs due to Rambus enforcing it's patents would only be ~0.03$/MB.
Presently, both RDRAM and DDRRAM are very expensive. This isn't because of rambus taking lots of royalties. It's because the products are still new, people who buy early are willing to pay extra, they haven't become comodities yet, memory manufactuers still haven't matured their manufacturing and testing to the same extend they have for SDRAM, etc..
So I'm not worried about memory prices soaring due to Rambus. I'm confident that with time prices on RDRAM and DDRRAM will come down.