If I were an employer, I'd be suspicious of hiring any computer professional (and maybe you are not one, I don't know) who was using antiquated hardware and saw no reason to upgrade. I'd be looking at that and asking myself "if this guy has so little interest in computers that he's running an ancient POS like that, how much enthusiasm can I expect from him in a technical position?"
I do run "POS"s like that. I am very interested in computers. Furtunately, I am not a computer professional. I bailed out of my CS course in third year, in favour of a more challenging physics degree. The shits that were around the CS department where amazing! They knew nothing. Sure they all had the latest fastest computer, but didn't know how to use it. Indeed, they didn't know how to interpret the performance of computers, beyond the marketing hype. A 5% increase on the last computer you bought? Why?! In the average 3 hour exam, I would end up leaving after 45 minutes, along with the rest of my friends, and we find out we are in the top 10% of the class all get greater than 90 percent on the exam, and the others with their fast laptops score below 10%. There truly was a gap in the exam marks between 10 and 90%, but I digress!
No, but I need a lot more than I could get from an AMD K6-3 running at 392mhz! I've got an Athlon XP1700+ and I'm getting ready to upgrade. I can't imagine how glacial a K6-3 would be for video encoding (e.g., Divx), MP3 encoding, hi-res Photoshop work, or running modern first-person shooters like Unreal Tournament 2003.
Personally, I don't waste my time or money on games, so my requirements are obviously differnt to yours. But the desktop sitting in front of me is a "POS" 500MHz Tru64 machine, running a "POS" OSF/1 v5.1. The only time I complain about it, is that every 2 months or so, I have to reboot, because the X server starts leaking memory, stealing the 196MB RAM I have available. Then, and only then, do things start to crawl. I wouldn't even reboot (just restart the X server), except that I like to clean things up occasionally, in case I have any stray processes doing stupid things, and I don't have root access.
With this 500MHz and 196 MB available to me, I run mozilla (a memory hog on the OSF/1 arhcitecture), xemacs, several GV sessions with big.ps files behind them, and about 15 or so xterm sessions, and occasionally the GIMP (oh, and a lightweight window manager - FVWM). Recently, I had a need to generate a 800MB data file, and get a program to generate a ~100,000 by ~1,000 pixel.ps file from it, and open it up using the GIMP - I admit that I had to go to one of our cluster machines with 3Gigs of memory to do this, but other than that......
fyi, gentoo packages are actually source based and are compilied automatically when installed to avoid rpm hell. Hmm lets upgrade to gcc31?.. this took litterally 2 days on my pIII.
Crickeys! You sure you are not running out of memory? I have a 500MHz AMD, (but with 384 megs RAM) and have never complained (I did when I only had 128 megs)! Of course, I used debian, and so don't have to compile from source often, but still, 2 days? Mozilla only took me a couple of hours, last time I tried it.
Hell, I would get sick of things after a day and kill the compilation -- the kernel didn't even take a day to compile on my 486 with 8 megs RAM.
I'm sure most peoples speed problems would be neutralised by them installing a decent window manager instead of the KDE or GNOME crap. I don't beleieve it takes ~30 seconds to start KDE on a top of the line workstation these days. FVWM took about 3 seconds on my 486 (and is there instantly on my ~500MHz laptop and desktop)!
Re:Sigh... I want a *cooler* processor...
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Pentium 4 2.8GHz
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· Score: 2
.4GHz+ certified fan, was still running after it died, fan still in place, no airflow blockage, but 30C outside, 40C in my room, then some in the case and running at 100% load. Sigh... back to Duron 700:(
Wow! 10 degrees extra in your room from your computer.
I am perfectly happy with my 650 MHz laptop (I expolicity bought the slowest one I could find at the time - 1.x years ago), and occasionally investigate getting it go slower (by either cpufreq or APM or ACPI. I also used to use a key combination on the dell inspiron laptops which took the speed down to 200MHz or so on the fly, but I have forgotten it now:( ). My desktop is 500MHz, and also is perfectly fine for everything I do. It's processor is room temp to touch! The fan failed once, and it stopped working, but it didn't kill the CPU, despite being and AMD K2 chip.
If I want speed (for my research), I will come into work, and use our cluster, but for a home computer, my two are perfectly happy.
I still don't understand people's facination with speed (especially the 5% or so we see in these benchmarks reported in the article), outside of the researching domain.
Games shmames.
Of course, our cluster is now (as of about 1 week ago) composed mostly of rack mounted dual p4's - 60 of those, and you can hear the whine from the fans outside the bloody server room and up the escalators! I haven't been inside yet - but I am told it was real bad before our sysadmin installed the bios update that had the fan speed control stuff in it!
What's the difference between what is referred to as the baseline in a VLBA, and what we're talking about here? If you increase the baseline, you increase the "aperture", right? But that doesn't increase the sensitivty, right? Is the real advantage of a huge array of dishes designed and operated as one telescope (as opposed to an ad hoc assembly) the things that are involved in this story -- i.e., data communication bandwidth and control?
Interferometers are very differnt beasts to normal radio telescopes. Single dish scopes look at a single area of the sky, and their sensetivity is proportional to the collecting area (square of diameter). Their angular resolution is proportional to the diamater. When I say the are pointing at a single area of sky, the telescope is actually looking at one point the size of the angular resolution - you may choose to look for a long time, gathering a spectrum (or looking at a pulsar) of that single point, or you may scan the telscope back and forth slowly to generate an image (with resolution equal to the angular resolition of the telescope).
With interferometers, you have a bunch of telescopes. The fundamental unit is no longer a single dish - it is now every combination of 2 dishes. At ATNF narrabri, there are 6 dishes, so there are 15 combinations (5 + 4 + 3 + 2 + 1) (I remember once having to step through each baseline individully, for each frequency for each observation we made, for each.... something else, to mitigate some interference manually, to get the best possible image I could generate for some nifty work I was asked to do) of pairs. The resolution is now a function of the distances between all the pairs.
You generate an image immediately, by getting the fourrier transform of the signals from the pairs, as the earth rotates. To generate the optimal image, with an East West synthesis telescope (such as Narrabri) where the X -resolution is (almost) the same as Y-resolution, you have to let the earth rotate a half turn, ie you sit there imaging for 12 hours. I have gotten away with observing for 4 before, but that was a very specific project. Other telescopes can sometimes do a "snapshot" mode, where you observe for a few minutes or hours, without too much loss of information. But basically, you don't have to scan the telscopes anymore, the centre of the image is where you point the telescopes, and the size of the image can be as big as the resolution would have been if you were using just one telescope.
The resolution you get is effectively from the farthest separated dishes, and the biggest structure you can see is from the resolution of the closest dishes (this all comes from the fact that you have to perform an inverse fourrier transform of the data coming from the pairs, and there are bits missing from the fourrier plane, where there aren't telescope pairs). With a single dish, you can see structures of any size bigger than the resolution. But an interferometer is missing all these bits where telscopes aren't situated, and in particular, has effectibely a hole in the middle of the "telescope" the size of the distance between the closest dishes. So there is an upper limit on the size of structures you can see (as well as a lower limit).
So occasionally, there have been tricks where you combine the high resolution data from interfereters with the low resolution data from a single dish, and you generate a very accurate and imformative image. This was done for generating a map of the Large Magellanic Cloud (no URL handy). But this needs a lot of work and telescope time, both hard to come by.
The sensetivety goes only as the size of the physical collecting area. So 1 square kilometer indeed is much better than the previous 1/30 or so sqaure kilometers we have had in a single setup. Note that, if the telscope is set up in Western Australia, (where I certainly hope it will:), then the resolution will be dictated by how big Australia is. About 1 milliarcsecond, or about 1000 times better than the average pre-interferometer resolutions you could get with optical telescopes on the ground, and 100 times better than hubble, keeping in mind that a radio telescope of the same size as an optical telescope will always have a resolution many thousands of times less (the ratio of the wavelength of optical light to radio light).
I apoligise in advance for confusing you all, but it is kindof a complex topic, and no doubt my head will explode now as well!
You wouldn't believe how increasingly difficult it is to do decent Radio Astronomy these days. Heck, the processor in your laptop or desktop is likely radiating right in "L" band (about 1.4 GHz). We thought big hulking monitors were bad until we measured the E/M interference from flat panel displays (it's bad). We're struggling to deal with the onslaught of laptops, 802.11b wireless equipment, PDAs and the like at places like Green Bank. And don't even start to talk about Iridium...
We got an email on the ATNF system about a month ago from a friend of mine (Daniel Mitchell - no doubt his web page ought to have a bit of info) who researches interference mitigation. He said the people who had been operating at 1.4GHz (or was it 2.8?) had finally turned off their bloody transmitter. Much elation! I've had to work around that bloody frequency before.
With current interferometers (ATNF narrabri is one) you get rid of some of the interference by default, because hopefully, the signals go to the 2 antennae in the single baseline at the same time, cancelling each other out (I believe this is a gross simplification, I can't remember the full details). Daniel is working on a small peice of equipment at Narrabri for his thesis, where he will be able to get rid of the interference from several land and satellite transmitters completely, by mixing it back with the signals to each of the telescopes. He is researching, along with many others, how best to do this with SKA. One way it to grab a whole bunch of nulls (destructive interference between all the telescopes) and chuck them in the direction of the offending transmitters. Again, I know no details!
Incidentally, somewhere, I have a photo from inside the observing room at Narrabri, which is surrounding by a Faraday cage (along with the friggin big correlator computers downstairs), where you can see at the controlling desk 4 or those little LCD beasties. Nice:)
In Australia (and I gather everywhere else where mobiles are popular except the US) SMS is regarded as an essential feature by just about anyone under 30.
I'm and Australian under 30. In fact, I'm 21. I loath mobile bloody phones. I really don't understand the conecpt that someone would want to take several minutes to type 160 characters into a tiny keyboard, costing them 20 cents, when they couyld pick up the nearest land-phone and talk for unlimited time (at your talking speed instead of typing speed) for 20 cents (given that most SMS's are sent between people in the same city). Hell, I do don't even pay for most of my local phone calls - I make them from work (my home bill is always the 15 dollars mininum that Telstra charge just for the privelege of having a phone)!
Pity Telstra are kinda neglecting the public phones on the street now, because only people like me use them. Note that before the mobile phone era, the were everywhere, and also happened to cost 40 cents to make a call for as long as you would typically talk on a mobile phone. Indeed, I remember the time when you only had to pay 30 cents!
hmmm you'd think after so many people on slashdot complaining to slashdot editors to check links before they post articles... they would!!... then again... these are slashdot editors...
It was there when I read it. Of course, I read it before there were any posts on the board.
You have to remember, ABC is our government funded free to air TV and news channel. They are running on a rather tight budget....
They wouldn't be able to take much of a Slashdotting.
>> Remember that old story about how you can stand at the bottom of a well and see the stars during the day because the light from the sun is blocked out?
> The sun is still shining, and the athmosphere is still spreading the light from the sun. Standing in a well wont change that...
Well, actually, you can see some stars (such as Sirius) in the day, as long as you know exactly where to look. I have successfully tracked Venus and Jupiter too, after watching them with a telescope through the morning, but as soon as I moved the telescope off the field of view, I could no longer find them!
"No, I don't know that atheists should be considered as citizens, nor should they be considered as patriots. This is one nation under God." -George H. W. Bush, 41st President
I am just wondering the cultural obsession that the Japanese have with rail systms, if any one has an answer.
Perhaps your question should be "What is the reason for the lack of a good rail system in the USA?" Lots of places in the world have good rail transport, not just Japan, virtually all of Europe too.
Actually, I prefer it when you ask the question "I am just wondering the cultural obsession that the Americans have with cars, if any one has an answer."
In Melbourne (my breif experience with America tells me you guys are worse), the average car trip length is 5km. I live 12 km from work/uni, and I ride the distance twice daily, and am much happier for it!
Anyway, it turns out that it's not too difficult or expensive to jury rig your own UPS with extended run times. Pick up some 12AWG power cable, a couple of marine/RV deep-cycle batteries (don't waste your money on sealed or gell cell). Then take apart the UPS, and wire two of the 14V batteries in series with the internal 28V supply. Oh, and use a fuse.:)
For about $500 in all, I was able to build a UPS like this that could power six servers for over 24 hours.
I tried doing that, by plugging in two rather large 12 V batteries in series, but blew the UPS while testing, because it just wasn't expecting to be up for more than 15 minutes, so the transformer was seriously underrated and got very hot very quickly, before developing an open circuit. Because I couldn't be bothered re-winding the transformer, I just grabbed my 350VA inverter, whipped together a circuit that flipped a relay within 4 milliseconds of the mains failing (2 cycles @ 50Hz Australian), and using the 12V batteries in parallel. I haven't tested uptime from fully charged to empty yet, because I only just finished the charger circuit, but it seems to last for 5 hours of more. Oh, of course, because my stereo is "mission critical", I have it plugged in too:)
I think it would be really cool if when they take all this data they are collecting, they produced a 3-d image of the COSMOS and a 3-d image of the cosmos with every star's location shifted to show its theoretical place today... or in the case of billion light year stars.... nothing if they are burned out by now.... that woould truly be an intersting map to look at:)
Except that galaxy evolution (I have just started a PhD on the topic) relies on all sorts of complicated things that this survey wouldn't give us. Star formation and supernova feedback, stellar evolution in general, gas, the cosmological paramaters that we haven't got a physical handle on yet, galaxy mergers - and most importantly - dark matter haloes. The whole evolution of galaxies is dictated by the rather invisible mass surrounding them, that we are only starting to be able to model.
But having said that, there was a paper on astro-ph the other day claiming that one very high resolution simulation that focussed on one particular galaxy seems to show the thing changing between all the differnt kinds of galaxies - including a spiral growing a bar! Now, there needs to be all sorts of other work to see if this is feasable - such as whether the chemical signatures make any sense, but it would still make one hell of a movie seeing that thing evolve!
Although you are probably looking for a digital solution, don't overlook the solutions that already exist. Security camera VCR's (available at RadioShack et al.) can put 24 hours (or more) of video on a single VHS tape. Get a few VCR's (at $200 each), and a pallet of VHS tapes at Sam's club, and you could record all the video you want!
Geez, I wish I could recall the rate that the Very Long Baseline Interferometry (radio astronomy) people record at. At the Australia Telescope, they have a bank of 8 or 10 modified VCR's that are controlled automatically from the upstairs computers, and write the stream of raw data at something like 10GB/s (can't quite remember, dagnamit) and take the tapes back to HQ in Sydney (never underestimate the bandwidth of a stationwagon full of tapes - must be thousands of times faster than their pipe to Sydney) and correlate all the telescopes' signals there.
Tapes are changed manually, but that is all. The rest is automatic. Reliability is good, but doesn't need to be perfect (corrupted byte? Well, just discard the 10 second interval around it), but more than a few bytes every now and then will lose you a lot of data (hmmm discard this 10 seconds - then then 10 seconds after that, and 10 more....)
Careful -- "best" doesn't suggest what it is best AT. You're right, that all superconductors present zero resistence, but a superconductor that does this trick at room temperature would be "better" than one that required exotically cold temperatures. And one that tasted like chocolate would be better than either of them.
In fact, it might very well be "best in show."
You see? You can't just say "best" -- you have to say what dimension you're measuring.;)
Particularly when high magnetic fields (and hence high currents through the wire!) will collapse the infinite conductivity instantaneously. In *all* superconductors! This means, you pass a lot of current (I think it may be as low as 10 amps) down your continent wide power line, and it instantly castrastropically fails. You would be realeasing megajoules of energy within milliseconds if you blew a high powered line!
Wouldn't want to be near it when the nitrogen supply ran out.
Turned out the ACL was intact, but there was meniscus damage and "a lot of junk and blood in there" that needed to be cleaned up, said the surgeon. I was on crutches for about a week.
Why would blood ever get in your access control lists?
I agree with you, they should be able to have _some_ redress for this. But legally, I don't think they can...that little "AS IS" clause in shrinkwrap licenses and all. Bah. We'll see.
Except that I have never agreed to a MS license, and my connections were hurt. I'm guessing Cisco router operators that were affected never agreed to the license in question, either.
TimC.
Re:Take a look at the startup scripts
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Mandrake 8.1 Released
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· Score: 2, Informative
They're usually in/etc/rc.d and most distros start things that aren't needed. Also, if you have a hackish bent, go to the source directory and "make xconfig" to see how the kernel was built. Are there drivers compiled in that aren't needed? Bloat can be fought!
Startup scripts that aren't used get swapped out and dont slow the system down because they stay swapped out.
The kernel should be less than 4 Megs in total, IIRC. Probably much less, even with a default kernel, especiialy if you are using modules.
But looking at swap going up - is the distribution presumably using the 2.4.x series kernel? It is 'orribly proken as far as the virtual memory subsystem is going. They are working very hard on fixing it (I subscribe to the kernel mailing list, and a good 10% or so of all mails are on the topic of WTF can we do?).
I was running a prerelease version of 2.4.10-pre12 which behaved beautifully for the 4 days I had it going before I installed the proper 2.4.10 version, which seems a bit more broken again.
So what I am saying, is hang in there - the kernel is getting better - but it may be a while. It is amazing how an identical kernel on an identical setup makes one person really happy, and is as slow as heck for another person.
But as soon as I finish my thesis, I am moving to FreeBSD, just to check it out. I suspect its VM is a lot less b0rked.
Slashdot Mirror
If I were an employer, I'd be suspicious of hiring any computer professional (and maybe you are not one, I don't know) who was using antiquated hardware and saw no reason to upgrade. I'd be looking at that and asking myself "if this guy has so little interest in computers that he's running an ancient POS like that, how much enthusiasm can I expect from him in a technical position?"
I do run "POS"s like that. I am very interested in computers. Furtunately, I am not a computer professional. I bailed out of my CS course in third year, in favour of a more challenging physics degree. The shits that were around the CS department where amazing! They knew nothing. Sure they all had the latest fastest computer, but didn't know how to use it. Indeed, they didn't know how to interpret the performance of computers, beyond the marketing hype. A 5% increase on the last computer you bought? Why?! In the average 3 hour exam, I would end up leaving after 45 minutes, along with the rest of my friends, and we find out we are in the top 10% of the class all get greater than 90 percent on the exam, and the others with their fast laptops score below 10%. There truly was a gap in the exam marks between 10 and 90%, but I digress!
No, but I need a lot more than I could get from an AMD K6-3 running at 392mhz! I've got an Athlon XP1700+ and I'm getting ready to upgrade. I can't imagine how glacial a K6-3 would be for video encoding (e.g., Divx), MP3 encoding, hi-res Photoshop work, or running modern first-person shooters like Unreal Tournament 2003.
Personally, I don't waste my time or money on games, so my requirements are obviously differnt to yours. But the desktop sitting in front of me is a "POS" 500MHz Tru64 machine, running a "POS" OSF/1 v5.1. The only time I complain about it, is that every 2 months or so, I have to reboot, because the X server starts leaking memory, stealing the 196MB RAM I have available. Then, and only then, do things start to crawl. I wouldn't even reboot (just restart the X server), except that I like to clean things up occasionally, in case I have any stray processes doing stupid things, and I don't have root access.
With this 500MHz and 196 MB available to me, I run mozilla (a memory hog on the OSF/1 arhcitecture), xemacs, several GV sessions with big
Recently, I had a need to generate a 800MB data file, and get a program to generate a ~100,000 by ~1,000 pixel
fyi, gentoo packages are actually source based and are compilied automatically when installed to avoid rpm hell. Hmm lets upgrade to gcc31?.. this took litterally 2 days on my pIII.
Crickeys! You sure you are not running out of memory? I have a 500MHz AMD, (but with 384 megs RAM) and have never complained (I did when I only had 128 megs)! Of course, I used debian, and so don't have to compile from source often, but still, 2 days? Mozilla only took me a couple of hours, last time I tried it.
Hell, I would get sick of things after a day and kill the compilation -- the kernel didn't even take a day to compile on my 486 with 8 megs RAM.
I'm sure most peoples speed problems would be neutralised by them installing a decent window manager instead of the KDE or GNOME crap. I don't beleieve it takes ~30 seconds to start KDE on a top of the line workstation these days. FVWM took about 3 seconds on my 486 (and is there instantly on my ~500MHz laptop and desktop)!
.4GHz+ certified fan, was still running after it died, fan still in place, no airflow blockage, but 30C outside, 40C in my room, then some in the case and running at 100% load. Sigh... back to Duron 700 :(
:( ). My desktop is 500MHz, and also is perfectly fine for everything I do. It's processor is room temp to touch! The fan failed once, and it stopped working, but it didn't kill the CPU, despite being and AMD K2 chip.
Wow! 10 degrees extra in your room from your computer.
I am perfectly happy with my 650 MHz laptop (I expolicity bought the slowest one I could find at the time - 1.x years ago), and occasionally investigate getting it go slower (by either cpufreq or APM or ACPI. I also used to use a key combination on the dell inspiron laptops which took the speed down to 200MHz or so on the fly, but I have forgotten it now
If I want speed (for my research), I will come into work, and use our cluster, but for a home computer, my two are perfectly happy.
I still don't understand people's facination with speed (especially the 5% or so we see in these benchmarks reported in the article), outside of the researching domain.
Games shmames.
Of course, our cluster is now (as of about 1 week ago) composed mostly of rack mounted dual p4's - 60 of those, and you can hear the whine from the fans outside the bloody server room and up the escalators! I haven't been inside yet - but I am told it was real bad before our sysadmin installed the bios update that had the fan speed control stuff in it!
What's the difference between what is referred to as the baseline in a VLBA, and what we're talking about here? If you increase the baseline, you increase the "aperture", right? But that doesn't increase the sensitivty, right? Is the real advantage of a huge array of dishes designed and operated as one telescope (as opposed to an ad hoc assembly) the things that are involved in this story -- i.e., data communication bandwidth and control?
:), then the resolution will be dictated by how big Australia is. About 1 milliarcsecond, or about 1000 times better than the average pre-interferometer resolutions you could get with optical telescopes on the ground, and 100 times better than hubble, keeping in mind that a radio telescope of the same size as an optical telescope will always have a resolution many thousands of times less (the ratio of the wavelength of optical light to radio light).
Interferometers are very differnt beasts to normal radio telescopes. Single dish scopes look at a single area of the sky, and their sensetivity is proportional to the collecting area (square of diameter). Their angular resolution is proportional to the diamater. When I say the are pointing at a single area of sky, the telescope is actually looking at one point the size of the angular resolution - you may choose to look for a long time, gathering a spectrum (or looking at a pulsar) of that single point, or you may scan the telscope back and forth slowly to generate an image (with resolution equal to the angular resolition of the telescope).
With interferometers, you have a bunch of telescopes. The fundamental unit is no longer a single dish - it is now every combination of 2 dishes. At ATNF narrabri, there are 6 dishes, so there are 15 combinations (5 + 4 + 3 + 2 + 1) (I remember once having to step through each baseline individully, for each frequency for each observation we made, for each.... something else, to mitigate some interference manually, to get the best possible image I could generate for some nifty work I was asked to do) of pairs. The resolution is now a function of the distances between all the pairs.
You generate an image immediately, by getting the fourrier transform of the signals from the pairs, as the earth rotates. To generate the optimal image, with an East West synthesis telescope (such as Narrabri) where the X -resolution is (almost) the same as Y-resolution, you have to let the earth rotate a half turn, ie you sit there imaging for 12 hours. I have gotten away with observing for 4 before, but that was a very specific project. Other telescopes can sometimes do a "snapshot" mode, where you observe for a few minutes or hours, without too much loss of information. But basically, you don't have to scan the telscopes anymore, the centre of the image is where you point the telescopes, and the size of the image can be as big as the resolution would have been if you were using just one telescope.
The resolution you get is effectively from the farthest separated dishes, and the biggest structure you can see is from the resolution of the closest dishes (this all comes from the fact that you have to perform an inverse fourrier transform of the data coming from the pairs, and there are bits missing from the fourrier plane, where there aren't telescope pairs). With a single dish, you can see structures of any size bigger than the resolution. But an interferometer is missing all these bits where telscopes aren't situated, and in particular, has effectibely a hole in the middle of the "telescope" the size of the distance between the closest dishes. So there is an upper limit on the size of structures you can see (as well as a lower limit).
So occasionally, there have been tricks where you combine the high resolution data from interfereters with the low resolution data from a single dish, and you generate a very accurate and imformative image. This was done for generating a map of the Large Magellanic Cloud (no URL handy). But this needs a lot of work and telescope time, both hard to come by.
The sensetivety goes only as the size of the physical collecting area. So 1 square kilometer indeed is much better than the previous 1/30 or so sqaure kilometers we have had in a single setup. Note that, if the telscope is set up in Western Australia, (where I certainly hope it will
I apoligise in advance for confusing you all, but it is kindof a complex topic, and no doubt my head will explode now as well!
You wouldn't believe how increasingly difficult it is to do decent Radio Astronomy these days. Heck, the processor in your laptop or desktop is likely radiating right in "L" band (about 1.4 GHz). We thought big hulking monitors were bad until we measured the E/M interference from flat panel displays (it's bad). We're struggling to deal with the onslaught of laptops, 802.11b wireless equipment, PDAs and the like at places like Green Bank. And don't even start to talk about Iridium...
:)
We got an email on the ATNF system about a month ago from a friend of mine (Daniel Mitchell - no doubt his web page ought to have a bit of info) who researches interference mitigation. He said the people who had been operating at 1.4GHz (or was it 2.8?) had finally turned off their bloody transmitter. Much elation! I've had to work around that bloody frequency before.
With current interferometers (ATNF narrabri is one) you get rid of some of the interference by default, because hopefully, the signals go to the 2 antennae in the single baseline at the same time, cancelling each other out (I believe this is a gross simplification, I can't remember the full details). Daniel is working on a small peice of equipment at Narrabri for his thesis, where he will be able to get rid of the interference from several land and satellite transmitters completely, by mixing it back with the signals to each of the telescopes. He is researching, along with many others, how best to do this with SKA. One way it to grab a whole bunch of nulls (destructive interference between all the telescopes) and chuck them in the direction of the offending transmitters. Again, I know no details!
Incidentally, somewhere, I have a photo from inside the observing room at Narrabri, which is surrounding by a Faraday cage (along with the friggin big correlator computers downstairs), where you can see at the controlling desk 4 or those little LCD beasties. Nice
Imagine you're at the pub (perhaps that pub on Glenferrie Road just up from the Swinburne campus)...
:)
:)
...The jukebox is blaring...
You mean that one I was at about 5 hours ago? Nevermind
Good pub
Blaring good music tonight. For a change.
I dunno about you and your friends, but for my friends it's a major way we make sure we meet up on a Friday night.
Astronomers don't have lives - we go to the pub in our own inbred group. We don't need no steenking outsiders.
BTW, where's the astronomy department?
On top of that ugly building next to the big tall ugly building.
Otherwise known as "corner of Serpells ln and Burwood Rd"
In Australia (and I gather everywhere else where mobiles are popular except the US) SMS is regarded as an essential feature by just about anyone under 30.
I'm and Australian under 30. In fact, I'm 21. I loath mobile bloody phones. I really don't understand the conecpt that someone would want to take several minutes to type 160 characters into a tiny keyboard, costing them 20 cents, when they couyld pick up the nearest land-phone and talk for unlimited time (at your talking speed instead of typing speed) for 20 cents (given that most SMS's are sent between people in the same city). Hell, I do don't even pay for most of my local phone calls - I make them from work (my home bill is always the 15 dollars mininum that Telstra charge just for the privelege of having a phone)!
Pity Telstra are kinda neglecting the public phones on the street now, because only people like me use them. Note that before the mobile phone era, the were everywhere, and also happened to cost 40 cents to make a call for as long as you would typically talk on a mobile phone. Indeed, I remember the time when you only had to pay 30 cents!
hmmm you'd think after so many people on slashdot complaining to slashdot editors to check links before they post articles... they would!!... then again... these are slashdot editors...
It was there when I read it. Of course, I read it before there were any posts on the board.
You have to remember, ABC is our government funded free to air TV and news channel. They are running on a rather tight budget....
They wouldn't be able to take much of a Slashdotting.
man apt-cache
/var/cache/apt/archives
cd
apt-cache dotty *
google "i'm feeling lucky" on graphviz, and voila!
I have a feeling someone is working on packaging graphviz, but there was problems with true-type fonts....
>> Remember that old story about how you can stand at the bottom of a well and see the stars during the day because the light from the sun is blocked out?
> The sun is still shining, and the athmosphere is still spreading the light from the sun. Standing in a well wont change that...
Well, actually, you can see some stars (such as Sirius) in the day, as long as you know exactly where to look. I have successfully tracked Venus and Jupiter too, after watching them with a telescope through the morning, but as soon as I moved the telescope off the field of view, I could no longer find them!
- giving your girl/boyfriend a mind-blowing orgasm?
:)
Now, you may say, 'but these things aren't important to me; I don't have time for them.' And then you'll understand why all the 'lusers' don't RTFM.
And it is revealed as to why the entire slashdot crowd are single. *I* know how to give a mind-blowing orgasm
Someone should tell your president.
Good luck getting it through that A-hole!
"No, I don't know that atheists should be considered as citizens, nor should they be considered as patriots. This is one nation under God." -George H. W. Bush, 41st President
>somebody in UK, please write your queen about this.
No, but they may write *to* our Queen.
After all, they speak English.
....as there is the free 2.4 Ghz alternative and both use similar technology and products can easily support both bands?
:(
Oh crap? I didn't realise it was 2.4 GHz. Can someone with knowledge tell me the exact frequency?
I just remember observing at the Australia Telescope last summer at 2496 MHz.
Just another hurdle to overcome, I guess.....
I am just wondering the cultural obsession that the Japanese have with rail systms, if any one has an answer.
Perhaps your question should be "What is the reason for the lack of a good rail system in the USA?" Lots of places in the world have good rail transport, not just Japan, virtually all of Europe too.
Actually, I prefer it when you ask the question "I am just wondering the cultural obsession that the Americans have with cars, if any one has an answer."
In Melbourne (my breif experience with America tells me you guys are worse), the average car trip length is 5km. I live 12 km from work/uni, and I ride the distance twice daily, and am much happier for it!
Anyway, it turns out that it's not too difficult or expensive to jury rig your own UPS with extended run times. Pick up some 12AWG power cable, a couple of marine/RV deep-cycle batteries (don't waste your money on sealed or gell cell). Then take apart the UPS, and wire two of the 14V batteries in series with the internal 28V supply. Oh, and use a fuse.
For about $500 in all, I was able to build a UPS like this that could power six servers for over 24 hours.
I tried doing that, by plugging in two rather large 12 V batteries in series, but blew the UPS while testing, because it just wasn't expecting to be up for more than 15 minutes, so the transformer was seriously underrated and got very hot very quickly, before developing an open circuit. Because I couldn't be bothered re-winding the transformer, I just grabbed my 350VA inverter, whipped together a circuit that flipped a relay within 4 milliseconds of the mains failing (2 cycles @ 50Hz Australian), and using the 12V batteries in parallel. I haven't tested uptime from fully charged to empty yet, because I only just finished the charger circuit, but it seems to last for 5 hours of more. Oh, of course, because my stereo is "mission critical", I have it plugged in too
RTFP:
9
http://xxx.adelaide.edu.au/abs/astro-ph/?020508
What, you trust everything the popular media says? You don't watch to CNN, do you?
Therefore,
99 = 19
80 = 0
Cool... I like these new cubes. Next lesson: Using the circumference of a Pepsi can to disprove the theory of relativity.
Which one?
--
TimC
The path to enlightenment_0.16.5-6 is through apt-get
I think it would be really cool if when they take all this data they are collecting, they produced a 3-d image of the COSMOS and a 3-d image of the cosmos with every star's location shifted to show its theoretical place today... or in the case of billion light year stars.... nothing if they are burned out by now.... that woould truly be an intersting map to look at :)
Except that galaxy evolution (I have just started a PhD on the topic) relies on all sorts of complicated things that this survey wouldn't give us. Star formation and supernova feedback, stellar evolution in general, gas, the cosmological paramaters that we haven't got a physical handle on yet, galaxy mergers - and most importantly - dark matter haloes. The whole evolution of galaxies is dictated by the rather invisible mass surrounding them, that we are only starting to be able to model.
But having said that, there was a paper on astro-ph the other day claiming that one very high resolution simulation that focussed on one particular galaxy seems to show the thing changing between all the differnt kinds of galaxies - including a spiral growing a bar! Now, there needs to be all sorts of other work to see if this is feasable - such as whether the chemical signatures make any sense, but it would still make one hell of a movie seeing that thing evolve!
Although you are probably looking for a digital solution, don't overlook the solutions that already exist. Security camera VCR's (available at RadioShack et al.) can put 24 hours (or more) of video on a single VHS tape. Get a few VCR's (at $200 each), and a pallet of VHS tapes at Sam's club, and you could record all the video you want!
Geez, I wish I could recall the rate that the Very Long Baseline Interferometry (radio astronomy) people record at. At the Australia Telescope, they have a bank of 8 or 10 modified VCR's that are controlled automatically from the upstairs computers, and write the stream of raw data at something like 10GB/s (can't quite remember, dagnamit) and take the tapes back to HQ in Sydney (never underestimate the bandwidth of a stationwagon full of tapes - must be thousands of times faster than their pipe to Sydney) and correlate all the telescopes' signals there.
Tapes are changed manually, but that is all. The rest is automatic. Reliability is good, but doesn't need to be perfect (corrupted byte? Well, just discard the 10 second interval around it), but more than a few bytes every now and then will lose you a lot of data (hmmm discard this 10 seconds - then then 10 seconds after that, and 10 more....)
TimC.
Careful -- "best" doesn't suggest what it is best AT. You're right, that all superconductors present zero resistence, but a superconductor that does this trick at room temperature would be "better" than one that required exotically cold temperatures. And one that tasted like chocolate would be better than either of them.
;)
In fact, it might very well be "best in show."
You see? You can't just say "best" -- you have to say what dimension you're measuring.
Particularly when high magnetic fields (and hence high currents through the wire!) will collapse the infinite conductivity instantaneously. In *all* superconductors! This means, you pass a lot of current (I think it may be as low as 10 amps) down your continent wide power line, and it instantly castrastropically fails. You would be realeasing megajoules of energy within milliseconds if you blew a high powered line!
Wouldn't want to be near it when the nitrogen supply ran out.
TimC.
Why would blood ever get in your access control lists?
TimC.
I agree with you, they should be able to have _some_ redress for this. But legally, I don't think they can...that little "AS IS" clause in shrinkwrap licenses and all. Bah. We'll see.
Except that I have never agreed to a MS license, and my connections were hurt. I'm guessing Cisco router operators that were affected never agreed to the license in question, either.
TimC.
They're usually in /etc/rc.d and most distros start things that aren't needed. Also, if you have a hackish bent, go to the source directory and "make xconfig" to see how the kernel was built. Are there drivers compiled in that aren't needed? Bloat can be fought!
Startup scripts that aren't used get swapped out and dont slow the system down because they stay swapped out.
The kernel should be less than 4 Megs in total, IIRC. Probably much less, even with a default kernel, especiialy if you are using modules.
But looking at swap going up - is the distribution presumably using the 2.4.x series kernel? It is 'orribly proken as far as the virtual memory subsystem is going. They are working very hard on fixing it (I subscribe to the kernel mailing list, and a good 10% or so of all mails are on the topic of WTF can we do?).
I was running a prerelease version of 2.4.10-pre12 which behaved beautifully for the 4 days I had it going before I installed the proper 2.4.10 version, which seems a bit more broken again.
So what I am saying, is hang in there - the kernel is getting better - but it may be a while. It is amazing how an identical kernel on an identical setup makes one person really happy, and is as slow as heck for another person.
But as soon as I finish my thesis, I am moving to FreeBSD, just to check it out. I suspect its VM is a lot less b0rked.
TimC.
In the last 10 years, we've deployed troops to help Muslims in Kuwait
That and to help secure cheap oil supplies for the US.
TimC.