solubilities are well know and tested for all common elements
Indeed ! Some tests are done more often then others.
Solubility of sodium chloride (or calcium chloride) in water is commonly used to prevent it from freezing (application - cleaning sidewalks).
The mixture of salt and water freezes at -21 Celsius = 272K or sooner, depending on purity. When salt water freezes it separates the salt which is why Antartic ice is not salty.
From Wikipedia, the surface temperature of Enceladus is at most 145K, so it is likely that surface ice is pure and it is possible that the liquid water is kept liquid by tidal forces (water in motion freezes at lower temperature). One can even imagine how period crystallization and melting of water by tidal forces has separated out salt somehow.
That said, sodium is extremely easy to ionize. To see that put a few salt crystals into gas or alcohol flame - it will turn yellow from the small quantity of sodium atoms that evaporated from the crystals. Thus, if liquid water was in direct contact with rock it would contain trace amounts of sodium which, when launched into space with the jet, will provide pronounced yellow line.
What is possibly happening is that two ice sheets (pure H20) collide, melt ice with the pressure and spray the resulting water into space. TFA mentions two more possibilities - as well as a speculation that Sodium atoms could be frozen inside water crystals.
My physics TA (a doctoral student) used to say that this "dark matter" talk reminded him a lot of how we posited an extra planet between Mercury and the Sun because that was the only way to account for Mercury's orbit. It turned out that there was no planet, Newtonian mechanics were just too imprecise to predict the orbit of Mercury. Likewise, his bet was that the effects attributed to "dark matter" would be accounted for once we developed more precise physical laws.
There is that.
On the other hand some of the new (and not so new) physics theories (like supersymmetry) actually produce weakly interacting particles. We already know about neutrinos, so it would not be surprising if there were other types.
I use fish:// for file access over SSH instead of SFTP.
I used fish myself a lot - it is great if one only has SSH shell. However, in some places (like University of Michigan), there is too much information in the welcome message which confuses it. I also believe that sftp is somewhat faster - when both source and target are on 100 Mbit or faster network.
So now I try sftp first and then type fish if that does not work.
I still wonder who or what that mythical power-user is, because I don't think I ever met one in person. The skript kiddie that spends 6 hours per day hunting themes and posting screen shots to forums? Some of the most knowledgeable and experienced developers I know barely change anything in their computer's configuration, even keeping the default OS X desktop image.
In between these two extremes there are people who actually use their computer.
You don't have to change everything to make yourself more comfortable.
Here are a few things that I tweak/use regularly:
Window manager: sloppy focus for the mouse, no autoraising or anything. If I want to raise a window I'll click on it, thank you very much.
Decoration: I drag close icon to the left, with the right being sticky/minimize/maximize.
Desktop: new desktops come with big widescreen monitors. I usually remove taskbar, put the panel in bottom left corner and put KasBar in the top right.
this way the space on the left is completely free - and is the size of the regular 4:5 monitors. Great for VNC, reading papers or having a big terminal.
On my notebook I changed desktop background to be a slideshow that changes every 20 minutes. When you concentrate on something you will perceive these to go by much faster - after 10 or 20 it is likely time for another meal.
Konqueror !! The first thing I chased down on Kubuntu Gutsy is how to switch away from Dolphin. Doplhin is fine manager if you don't have many files. Konqueror is the best thing after the shell tools - with the order being reversed when you have images. Right now I have a window open, with several tabs open in different simulation runs, some showing particular documents and this all mixing transparently the documents on my local systems with those on remote systems (using sftp://). And if you are writing a webpage you can have local source in one table, destination public_html in another and a test display in yet another. Just drag files from local to remote when you are done editing and click refresh to display the results !
Konsole - the first thing I do is kill the menubar and everything else that uses up space, though I now keep the tabs. There is much misunderstanding about terminals. What they are is the perfect (and only) way to display a matrix of symbols with perfect control of individual elements. If you make an image you can squeeze more info into it, but you cannot tell which exact pixel is that dot unless you use a magnifier and kruler. And, of course, you can dump output from find/grep and see it align visually.
Sessions in Kate are wonderful if lists of files you are editing extend way past screen.
I set my default viewer to gwenview - so I can change files by using a scrollwheel. If you have many similar files rotating the wheel makes an animation (I could just make a real animation - but why bother typing)
I think this is about it - does anyone else has tricks to share ?
Nobel prize winner Steve Weinberg says in the article that it will be the only good science done on the ISS if it goes up!!!
And with a very good reason. AMS (the device) is meant to observe extremely high energy cosmic rays - energies magnitudes higher than we can currently achieve in big (or small) colliders.
These rays cannot be observed with ground instruments as once they enter Earth atmosphere they immediately react to produce showers of lighter particles - this is how we know they exist in the first place.
One can hope to observe creation of antimatter, dark matter or tiny black holes - or who knows what else that has been happening in the upper atmosphere of Earth for ages but we did not have instruments to look.
Contrast this with an exciting discovery of more virulent salmonella - a very important hazard to be avoided while you are eating chickens on the way to Mars - but I doubt it will make anyone run naked in the streets as, say, discovery of a reaction that makes dark matter could (it is the 30% of the universe after all !)
Besides the speculation, will we even know when the boundary is crossed? Do they expect data to indicate a transition, or do we even know if the instruments can detect such a thing?
Yes. They are still receiving telemetry from both spacecraft (Voyagers I and II) indicating plasma density, strength of magnetic fields and some other data that I forget.
Why does the picture which most prominently displays Earth show the American continents, instead of Europe or Asia?
Because it is the other side of the Earth ?
More seriously, the most likely cause is that Eurasia is just a big blob of landmass, not much variety. The two Americas do look much better - and make it obvious it is a planet.
How the fuck are they using multi-frequency modulation techniques on light rays (fibre) ?
The frequency of light is of the order of 100000 THz. So the frequencies they are interested in are much smaller and usually limited by dimensions of modulating devices and limits of electronics they use.
A simple setup could be this: a frequency stabilized laser serving as local oscillator followed by two electro-optic crystals offset by a distance that corresponds to needed phase delay. If your electronics and crystals can do 2 GHz modulation this setup would allow to achive 4 GHz with 3.75cm offset between crystals - provided the clock that feeds the electronics is stable enough.
The state of the art in optics is pretty much what electronics used to be in the first part of 20th century - bulky discrete components mounted on large "breadboard" tables. 1 Terahertz corresponds to 0.3mm wavelength, and 10 Thz is 30um - so the researchers had to overcome some significant engineering difficulties.
We will finally know.....when Duke Nukem Forever will be released.
Remember the proof that one cannot decide in advance whether a given algorithm will finish in finite time ? There was a reason they put "Forever" in the title..
Like everyone's been saying, our solution to these problems of dependence on the middle east & emissions is going to be a host of different solutions specific to different areas. I fear that the funding and attention will go into this and we'll have all our eggs in one basket... a basket owned by and controlled by the DoD.
The problem with other solutions is the need to be commercially feasible first (i.e. close to inexpensive) before people put money into it.
The advantages of space based platform is that we get subsidies to develop launch technology, subsidies to solar cell manufacturers, a reason to have a station far enough in space and, perhaps, someone will figure out how to use beamed power to reduce launch costs. Even a 10% increase in thrust of the engines would have a big effect on the launch economy.
I have my doubts as well. There is a picture there of Dr.Bae standing next to an experimental setup which consists of precision scales, a mirror sitting on these scales, another mirror above it and some sort of laser medium in between.
From this I figure that his thruster uses Fabry-Perot cavity to amplify amount of light circulating between mirrors - not exactly a new trick. However the press release says something about importance of putting laser medium inside the cavity so, hopefully, he is doing something more involved (though not described).
Also, this thrust could only be used to push two mirrors apart - so it is hard to see how one can use this for docking - but undocking would work fine..
I just want to highlight a couple of points about released docs.
In the past the hardware did not change much between releases (which is why one can have unified drivers). In particular, having documentation for one card goes a very long way to figuring out how to use a similar, slightly modified card. What happened after R300 is that ATI ripped out their 2d engine which made it impossible to figure out how to set modes on the new cards. Thus, we did not even have a 2d X-server, let alone 3d. With this documentation one can have a driver that allows distributions to boot directly to the largest supported mode - and then download binary driver if they feel like it.
Secondly, these documents are now public as opposed to limited to ATI-approved select developers. This makes a huge difference as more people would be able to contribute. Before, with experimental drivers, the outside developers could only provide feedback and getting them approved was not a speedy process. With docs available, not only the driver quality will go up but also one can hope for new and creative use of the chips. I really can't stress enough importance of having public documentation.
- Eagerly waiting for the 3d part - which is also needed for old-fashioned 2d graphics..
I wish people would do cost/benefit analyses on this latter point. After all, everyone knows Unix is cheaper. But is it cheaper than replacing your Win32 GUI point-n-click admins with their Unix replacements? I honestly have no clue... and I suspect it really depends upon the company, the culture, the size, the market, etc.
Problem is "point and click" admins are usually completely incapable to troubleshoot anything. Do you want them to keep reinstalling drivers when the problem is flaky ethernet cable ?
You need at least one competent, find-the-cause-and-solve-it person, preferably two - for redundancy. And once that person is there a conversion to Linux can begin a server or two at a time. Properly setup Linux systems need little maintenance and are very flexible. And they do not put legal barriers to getting the job done.
A major reason why everything just works on Mac OS is because they only have a limited subset of hardware to support.
My reasons for using a Mac are simple, I don't have to set it up, my hardware just works, it has MS Office for work as well as being a unix platform for running my code in the right environment. Also the GUI works well, simple things like expose and spotlight are really useful day to day.
Which is all fine and dandy, until you want to do something that has not been done before - at least not by 99% of users. For example, suppose your application requires more than 8 cores or more than 64GB of RAM. Or both.
With Linux you just buy a bigger box from IBM or Sun and off you go tuning your application to actually use more hardware.
With Mac OS, you also buy a bigger box from IBM or Sun and port your app to Linux first..
MOSIX and OpenMOSIX are separate projects. OpenMOSIX was started because MOSIX is so closed. Try to find an easy download link for MOSIX, go ahead. I'll wait...
Ahh, this clears it up - thank you ! (and sorry to the OpenMosix folks).
From a user standpoint, openMosix is the mainstay of the Open Source clustering world...
Sorry, but I have never worked on an openMosix cluster, but did use several condor-based ones. Also, the NSF-backed grid project is targeted at large and relatively slow networks of computers rather than an emulation of a NUMA-like architecture.
So, while Mosix ideas are certainly cool, etc, it is not a mainstay of anything.
Also, what is it with "MOSIX is very hard to obtain unless you're a student" - is this the same kind of "open" as in OpenXML ?
The first code I see has a goto in it. I always thought goto was considered harmful?
In a nutshell, yes. But there is an important exception - goto's are ok when you jump down in the code (similar to a break in the loop), usually to a piece that frees allocated storage and exits function. In the code you cite, dput_and_out commits information and exits the function. In a way it is kinda a replacement for try {} catch {}, but with multiple try {} clauses.
But this doesn't consider the total price of a computer which would help mid priced chips. A $113 CPU is 54% more expensive than a $73 one, so it would have to perform 54% better. But when you throw them into identical $200 systems (case, hard drive, fan, power supply, memory, etc), the $113 CPU (with a total system cost of $313) is only 14% more expensive than the $73 CPU (with a total system cost of $273).
I want to second that - I am always astounded at how closely the price increments of the cpu's match the cost of a well-configured system. You start configuring a workstation or a server and lo and behold upping the clock rate by 10% costs almost exactly (or slightly below) 10% of the total system price.
The only case when lower priced processors matter is when configuring for capability rather than raw performance. I.e. larger cache, 64bit vs 32bit, thermal power dissipation, etc.
Typically grading the test is just the matter of summing up right answers (perhaps with partial credit) and then chopping the distribution into three parts As, Bs and Cs.
Is this an example of the places too sissy to hand out a failing grade for crap?
It is common in the US universities, I never heard of anyone using a substantially different scheme. You can still get an F if, for example, you register for the class, miss all the exams and ignore e-mail from the professor.
It is not so much the inflation of grades at low end that is the problem (I think, by now, most people equate C with an F), but rather that having an A does not imply you have understood the material.
I have not heard about Rasch model, thank you for the explanation.
I just want to point out that I never saw anyone use it (or anything else similarly complex) in universities, even on math departments. Typically grading the test is just the matter of summing up right answers (perhaps with partial credit) and then chopping the distribution into three parts As, Bs and Cs. A good reason for that is people perceive the grading being fair when they can predict how much answering a particular question will benefit them.
Reliability: if your solution costs $3K instead of $47K, just buy 2 or three. Nothing beats system redundancy, provided the components are decent.
Saving money - in 3 years just buy a new system. You will need more storage anyway.
SAS versus SATA: the only company that I know of that makes 300G 15K rpm drives is Seagate. They cost $1000 a piece. Compare to $129-$169 per Western Digital 400G enterprise drives. For multi-terabyte arrays it makes a lot of sense to get SATA disks and put the money into RAM. Lots of RAM - like 32GB or 64GB.
The big advantage of a Linux system (or BSD if you know it better) is flexibility. Configure SAMBA they way you like, mount shares from other machines the way you like. Use chattr, setfacl, or whatever else. Run database on the same machine the RAID controller is on. Use multiple ethernet adaptors.
To people above - if bandwidth is a problem, 10Gb adapter now costs $1000. Though I doubt your RAID controller can saturate even one gigabit line under moderate seek load.
If it's so "basic" to the brain then why is it the exception in human society and not the rule?
It is not an exception, you just need to see it. Ever observed someone doing things against reason, but because it is "the right thing to do" ? This is a form of altruism. People hesitate, have doubts, but then go with popular opinion. The key here is perceived benefit of others. Just as with other feelings what we perceive does not have to be what actually happens, one needs to apply reason for that.
Examples: smoking or drinking with the company, jumping into untested water because everyone is doing it, so on.
From the evolution point of view it is a good thing since it is better that all the herd practice jumps into the river and 1% perish, rather than have those 1% contaminate the genpool.
Slashdot Mirror
Here are the plans from the 60's. Enjoy !
Indeed ! Some tests are done more often then others.
Solubility of sodium chloride (or calcium chloride) in water is commonly used to prevent it from freezing (application - cleaning sidewalks).
The mixture of salt and water freezes at -21 Celsius = 272K or sooner, depending on purity. When salt water freezes it separates the salt which is why Antartic ice is not salty.
From Wikipedia, the surface temperature of Enceladus is at most 145K, so it is likely that surface ice is pure and it is possible that the liquid water is kept liquid by tidal forces (water in motion freezes at lower temperature). One can even imagine how period crystallization and melting of water by tidal forces has separated out salt somehow.
That said, sodium is extremely easy to ionize. To see that put a few salt crystals into gas or alcohol flame - it will turn yellow from the small quantity of sodium atoms that evaporated from the crystals. Thus, if liquid water was in direct contact with rock it would contain trace amounts of sodium which, when launched into space with the jet, will provide pronounced yellow line.
What is possibly happening is that two ice sheets (pure H20) collide, melt ice with the pressure and spray the resulting water into space. TFA mentions two more possibilities - as well as a speculation that Sodium atoms could be frozen inside water crystals.
There is that.
On the other hand some of the new (and not so new) physics theories (like supersymmetry) actually produce weakly interacting particles. We already know about neutrinos, so it would not be surprising if there were other types.
I used fish myself a lot - it is great if one only has SSH shell. However, in some places (like University of Michigan), there is too much information in the welcome message which confuses it. I also believe that sftp is somewhat faster - when both source and target are on 100 Mbit or faster network.
So now I try sftp first and then type fish if that does not work.
In between these two extremes there are people who actually use their computer. You don't have to change everything to make yourself more comfortable.
Here are a few things that I tweak/use regularly:
- Window manager: sloppy focus for the mouse, no autoraising or anything. If I want to raise a window I'll click on it, thank you very much.
- Decoration: I drag close icon to the left, with the right being sticky/minimize/maximize.
- Desktop: new desktops come with big widescreen monitors. I usually remove taskbar, put the panel in bottom left corner and put KasBar in the top right.
this way the space on the left is completely free - and is the size of the regular 4:5 monitors. Great for VNC, reading papers or having a big terminal.
- On my notebook I changed desktop background to be a slideshow that changes every 20 minutes. When you concentrate on something you will perceive these to go by much faster - after 10 or 20 it is likely time for another meal.
- Konqueror !! The first thing I chased down on Kubuntu Gutsy is how to switch away from Dolphin. Doplhin is fine manager if you don't have many files. Konqueror is the best thing after the shell tools - with the order being reversed when you have images. Right now I have a window open, with several tabs open in different simulation runs, some showing particular documents and this all mixing transparently the documents on my local systems with those on remote systems (using sftp://). And if you are writing a webpage you can have local source in one table, destination public_html in another and a test display in yet another. Just drag files from local to remote when you are done editing and click refresh to display the results !
- Konsole - the first thing I do is kill the menubar and everything else that uses up space, though I now keep the tabs. There is much misunderstanding about terminals. What they are is the perfect (and only) way to display a matrix of symbols with perfect control of individual elements. If you make an image you can squeeze more info into it, but you cannot tell which exact pixel is that dot unless you use a magnifier and kruler. And, of course, you can dump output from find/grep and see it align visually.
- Sessions in Kate are wonderful if lists of files you are editing extend way past screen.
- I set my default viewer to gwenview - so I can change files by using a scrollwheel. If you have many similar files rotating the wheel makes an animation (I could just make a real animation - but why bother typing)
I think this is about it - does anyone else has tricks to share ?And with a very good reason. AMS (the device) is meant to observe extremely high energy cosmic rays - energies magnitudes higher than we can currently achieve in big (or small) colliders.
These rays cannot be observed with ground instruments as once they enter Earth atmosphere they immediately react to produce showers of lighter particles - this is how we know they exist in the first place.
One can hope to observe creation of antimatter, dark matter or tiny black holes - or who knows what else that has been happening in the upper atmosphere of Earth for ages but we did not have instruments to look.
Contrast this with an exciting discovery of more virulent salmonella - a very important hazard to be avoided while you are eating chickens on the way to Mars - but I doubt it will make anyone run naked in the streets as, say, discovery of a reaction that makes dark matter could (it is the 30% of the universe after all !)
Yes. They are still receiving telemetry from both spacecraft (Voyagers I and II) indicating plasma density, strength of magnetic fields and some other data that I forget.
Because it is the other side of the Earth ?
More seriously, the most likely cause is that Eurasia is just a big blob of landmass, not much variety. The two Americas do look much better - and make it obvious it is a planet.
The frequency of light is of the order of 100000 THz. So the frequencies they are interested in are much smaller and usually limited by dimensions of modulating devices and limits of electronics they use.
A simple setup could be this: a frequency stabilized laser serving as local oscillator followed by two electro-optic crystals offset by a distance that corresponds to needed phase delay. If your electronics and crystals can do 2 GHz modulation this setup would allow to achive 4 GHz with 3.75cm offset between crystals - provided the clock that feeds the electronics is stable enough.
The state of the art in optics is pretty much what electronics used to be in the first part of 20th century - bulky discrete components mounted on large "breadboard" tables. 1 Terahertz corresponds to 0.3mm wavelength, and 10 Thz is 30um - so the researchers had to overcome some significant engineering difficulties.
If you are concerned about storage space mysql has 48bit storage type.
Remember the proof that one cannot decide in advance whether a given algorithm will finish in finite time ? There was a reason they put "Forever" in the title..
The problem with other solutions is the need to be commercially feasible first (i.e. close to inexpensive) before people put money into it.
The advantages of space based platform is that we get subsidies to develop launch technology, subsidies to solar cell manufacturers, a reason to have a station far enough in space and, perhaps, someone will figure out how to use beamed power to reduce launch costs. Even a 10% increase in thrust of the engines would have a big effect on the launch economy.
I have my doubts as well. There is a picture there of Dr.Bae standing next to an experimental setup which consists of precision scales, a mirror sitting on these scales, another mirror above it and some sort of laser medium in between.
From this I figure that his thruster uses Fabry-Perot cavity to amplify amount of light circulating between mirrors - not exactly a new trick. However the press release says something about importance of putting laser medium inside the cavity so, hopefully, he is doing something more involved (though not described).
Also, this thrust could only be used to push two mirrors apart - so it is hard to see how one can use this for docking - but undocking would work fine..
1. Get documentation
2. Have fun
3. Have more fun
4. Have fun and profit !
In the past the hardware did not change much between releases (which is why one can have unified drivers). In particular, having documentation for one card goes a very long way to figuring out how to use a similar, slightly modified card. What happened after R300 is that ATI ripped out their 2d engine which made it impossible to figure out how to set modes on the new cards. Thus, we did not even have a 2d X-server, let alone 3d. With this documentation one can have a driver that allows distributions to boot directly to the largest supported mode - and then download binary driver if they feel like it.
Secondly, these documents are now public as opposed to limited to ATI-approved select developers. This makes a huge difference as more people would be able to contribute. Before, with experimental drivers, the outside developers could only provide feedback and getting them approved was not a speedy process. With docs available, not only the driver quality will go up but also one can hope for new and creative use of the chips. I really can't stress enough importance of having public documentation.
- Eagerly waiting for the 3d part - which is also needed for old-fashioned 2d graphics..
Problem is "point and click" admins are usually completely incapable to troubleshoot anything. Do you want them to keep reinstalling drivers when the problem is flaky ethernet cable ?
You need at least one competent, find-the-cause-and-solve-it person, preferably two - for redundancy. And once that person is there a conversion to Linux can begin a server or two at a time. Properly setup Linux systems need little maintenance and are very flexible. And they do not put legal barriers to getting the job done.
Which is all fine and dandy, until you want to do something that has not been done before - at least not by 99% of users. For example, suppose your application requires more than 8 cores or more than 64GB of RAM. Or both.
With Linux you just buy a bigger box from IBM or Sun and off you go tuning your application to actually use more hardware.
With Mac OS, you also buy a bigger box from IBM or Sun and port your app to Linux first..
Ahh, this clears it up - thank you ! (and sorry to the OpenMosix folks).
Sorry, but I have never worked on an openMosix cluster, but did use several condor-based ones. Also, the NSF-backed grid project is targeted at large and relatively slow networks of computers rather than an emulation of a NUMA-like architecture.
So, while Mosix ideas are certainly cool, etc, it is not a mainstay of anything.
Also, what is it with "MOSIX is very hard to obtain unless you're a student" - is this the same kind of "open" as in OpenXML ?
In a nutshell, yes. But there is an important exception - goto's are ok when you jump down in the code (similar to a break in the loop), usually to a piece that frees allocated storage and exits function. In the code you cite, dput_and_out commits information and exits the function. In a way it is kinda a replacement for try {} catch {}, but with multiple try {} clauses.
I want to second that - I am always astounded at how closely the price increments of the cpu's match the cost of a well-configured system. You start configuring a workstation or a server and lo and behold upping the clock rate by 10% costs almost exactly (or slightly below) 10% of the total system price.
The only case when lower priced processors matter is when configuring for capability rather than raw performance. I.e. larger cache, 64bit vs 32bit, thermal power dissipation, etc.
It is common in the US universities, I never heard of anyone using a substantially different scheme. You can still get an F if, for example, you register for the class, miss all the exams and ignore e-mail from the professor.
It is not so much the inflation of grades at low end that is the problem (I think, by now, most people equate C with an F), but rather that having an A does not imply you have understood the material.
I just want to point out that I never saw anyone use it (or anything else similarly complex) in universities, even on math departments. Typically grading the test is just the matter of summing up right answers (perhaps with partial credit) and then chopping the distribution into three parts As, Bs and Cs. A good reason for that is people perceive the grading being fair when they can predict how much answering a particular question will benefit them.
It is not an exception, you just need to see it. Ever observed someone doing things against reason, but because it is "the right thing to do" ? This is a form of altruism. People hesitate, have doubts, but then go with popular opinion. The key here is perceived benefit of others. Just as with other feelings what we perceive does not have to be what actually happens, one needs to apply reason for that.
Examples: smoking or drinking with the company, jumping into untested water because everyone is doing it, so on.
From the evolution point of view it is a good thing since it is better that all the herd practice jumps into the river and 1% perish, rather than have those 1% contaminate the genpool.
Emotion is a tool. Use wisely.