Two facts:
1) all superconductors superconduct better at lower temperatures
2) all superconductors superconduct better at lower magnetic fields
Basically, you can think of it as both temperature and magnetic field introducing a kind of disorder (causing Cooper pairs to break up, destroying superconductivity).
Type I superconductors don't allow any magnetic fields, Type II allow up to certain field strengths, depending on the material and also on temperature. (This is a 'competition' between the two important length scales in a superconductor: the coherence length--size of a Cooper pair; and the penetration depth--up to which distance a magnetic field still penetrates into the material).
In fact, the most important drawback of the high-temperature superconductors (up to about 140K), is that at those higher temperatures they don't allow for high magnetic field nor high current. Also, they're hard to produce on a large scale. Still it's commercially viable these days to use superconductors for current transport at liquid nitrogen temperatures.
But almost universally other parents remark on how pleasant and respectful my children are.
Then you're probably doing a good job.
Look, children are supposed to disagree with their parents (and to fight with each other), it's what they do.
Of course I don't know what you mean by don't show me or their mother the level of respect; but I'd be more scared if they were obedient all the time--sounds like mindless conditioning to me.
And this is the first time I've seen an argument disproved in the abstract alone. One wonders why they need the six pages of the article itself, probably arXiv doesn't accept just an abstract:)
A good and appropriate project is the way to go. Then choose which tools are most suited.
Write a rehearsal application, a database for his music collection, program Lego Mindstorms, whatever. A project automatically set both short-term and long-term goals, your kid will inituitively pick up quickly how things work, and it is easier to think about the problem encountered.
You can always go more low-level afterwards, according to the developing interests of your child.
MRIs are usually built with what are called high-Tc superconductors. Here Tc stands for critical temperature, and means the temperature at which it possibly still superconducts.
But another factor needs to be taken into account: high magnetic fields destroy superconductity, just as high temperature does. So there is also a critical magnetic field (called Hc).
The catch is, that the critical magnetic field depends on temperature: the lower the temperature, the higher a magnetic field is allowed. This is of course quite important if you are building large electromagnets, as in MRI-scanners.
The reason high-Tc superconductors are used for MRIs is that their higher critical temperature is related to the high critical field allowed at low temperatures.
Aside: the reason that only now superconductors are getting to be used in power applications, such as the one mentioned in TFA, is that it is still very expensive, and that large scale production of quality superconducting material is still hard (it is very brittle).
I'm just saying that if your in music for the money, then shut up and let your record company make that money for you, because their good at it. If not, then show it to us by sharing your music.
Free music is not crazy, just google "copyleft mp3" or whatever, lots of things to find and hear.
I gave you an example.
I'm not in music but in science, I make enough to eat and drink the occassional beer, and when I have found something interesting, I put it on arXiv, so others can read and use it when they want, thank you very much.
... is when bands, especially those who have made it already and don't need more money (I'm talking to you R.E.M.), just dump their records labels and publish their music freely. They can ask you for a contribution if you like, or for you to come to their shows. Here's an example from the Netherlands, all their music for download as long as you "promise to let all your friends listen to it".
In general, I think if you want to be an artist, then you want to have as many people as possible to have access to your material, and if can also make a buck, it's an extra. Otherwise you're just an "entrepeneur" (I quote Rock the Net) and part of the system that aims only for consumers' money, and you should not complain.
I use Ubuntu Dapper, and it hasn't updated to 2.0 yet, I type this running 1.5.0.9.
I do not really understand the exploit, but it seems quite elaborate. There is no concept of proof that I can test over there, sorry. It doesn't say whether only Windows versions are susceptible either.
I am a theoretical physicist finishing my MSc thesis, and have bought the book (over six months ago). I like it very much, for me it just gives a good, mathematically approached overview of everything I've learned in the past few years.
However, I do not feel that just anybody with an interest in the subject can just pick up the book, read and enjoy. It's not that easy, some deep concepts are introduced in just a few sentences. It helps if you do the excercises, but it's still pretty hard. Fortunately, Penrose continuously references back to the relevant chapters when using some material developed earlier. But, like all mathematics, definitions follow each other very quickly, and by no means is it straightforward to remember and comprehend them.
Summarizing: if you want to know more about real physics this book is for you, but be prepared to spend a lot of time and effort, and regard it as studying, not reading.
But maybe it's like the LOTR movies: if you've read the book, they're going amazingly fast, otherwise they progress tediously slow.
Slashdot Mirror
You're half right.
Two facts:
1) all superconductors superconduct better at lower temperatures
2) all superconductors superconduct better at lower magnetic fields
Basically, you can think of it as both temperature and magnetic field introducing a kind of disorder (causing Cooper pairs to break up, destroying superconductivity).
Type I superconductors don't allow any magnetic fields, Type II allow up to certain field strengths, depending on the material and also on temperature. (This is a 'competition' between the two important length scales in a superconductor: the coherence length--size of a Cooper pair; and the penetration depth--up to which distance a magnetic field still penetrates into the material).
In fact, the most important drawback of the high-temperature superconductors (up to about 140K), is that at those higher temperatures they don't allow for high magnetic field nor high current. Also, they're hard to produce on a large scale. Still it's commercially viable these days to use superconductors for current transport at liquid nitrogen temperatures.
A student comes in and asks:
- What's your favourite branch of mathematics?
- Well, knot theory
- Yeah, me neither
But almost universally other parents remark on how pleasant and respectful my children are.
Then you're probably doing a good job.
Look, children are supposed to disagree with their parents (and to fight with each other), it's what they do.
Of course I don't know what you mean by don't show me or their mother the level of respect; but I'd be more scared if they were obedient all the time--sounds like mindless conditioning to me.
Nice explanation.
:)
And this is the first time I've seen an argument disproved in the abstract alone. One wonders why they need the six pages of the article itself, probably arXiv doesn't accept just an abstract
A Jackalope? If thats what it is, well fuck if I know. /ICP
A good and appropriate project is the way to go. Then choose which tools are most suited.
Write a rehearsal application, a database for his music collection, program Lego Mindstorms, whatever. A project automatically set both short-term and long-term goals, your kid will inituitively pick up quickly how things work, and it is easier to think about the problem encountered.
You can always go more low-level afterwards, according to the developing interests of your child.
MRIs are usually built with what are called high-Tc superconductors. Here Tc stands for critical temperature, and means the temperature at which it possibly still superconducts.
But another factor needs to be taken into account: high magnetic fields destroy superconductity, just as high temperature does. So there is also a critical magnetic field (called Hc).
The catch is, that the critical magnetic field depends on temperature: the lower the temperature, the higher a magnetic field is allowed. This is of course quite important if you are building large electromagnets, as in MRI-scanners.
The reason high-Tc superconductors are used for MRIs is that their higher critical temperature is related to the high critical field allowed at low temperatures.
Aside: the reason that only now superconductors are getting to be used in power applications, such as the one mentioned in TFA, is that it is still very expensive, and that large scale production of quality superconducting material is still hard (it is very brittle).
You can at least cite properly:
http://xkcd.com/221/
Especially in a two-party system.
http://theamazingrolo.blogspot.com/2007/03/wii-loo p-machine.html
I guess I'd better not respond, but can't resist.
... is when bands, especially those who have made it already and don't need more money (I'm talking to you R.E.M.), just dump their records labels and publish their music freely. They can ask you for a contribution if you like, or for you to come to their shows. Here's an example from the Netherlands, all their music for download as long as you "promise to let all your friends listen to it".
In general, I think if you want to be an artist, then you want to have as many people as possible to have access to your material, and if can also make a buck, it's an extra. Otherwise you're just an "entrepeneur" (I quote Rock the Net) and part of the system that aims only for consumers' money, and you should not complain.
Indeed. If you want power, just burn the food you eat, that can be done far more efficiently.
And guess what your body produces by generating power from sugar: yes, carbon dioxide. There is no environmental gain here at all.
Actually, it was Nosovelov and Geim's group in Manchester. See e.g. their original article in Science.
How does static electricity get you an AC current?
"proof of concept" that is; I should go to bed
I use Ubuntu Dapper, and it hasn't updated to 2.0 yet, I type this running 1.5.0.9. I do not really understand the exploit, but it seems quite elaborate. There is no concept of proof that I can test over there, sorry. It doesn't say whether only Windows versions are susceptible either.
Full article available on the arXiv since July 2006
it will make one person happy in each city
Perhaps he should consider going down a level
Here or use the Firefox extension.
... this
Someone found out earlier, by a more adventurous method
I am a theoretical physicist finishing my MSc thesis, and have bought the book (over six months ago). I like it very much, for me it just gives a good, mathematically approached overview of everything I've learned in the past few years.
However, I do not feel that just anybody with an interest in the subject can just pick up the book, read and enjoy. It's not that easy, some deep concepts are introduced in just a few sentences. It helps if you do the excercises, but it's still pretty hard. Fortunately, Penrose continuously references back to the relevant chapters when using some material developed earlier. But, like all mathematics, definitions follow each other very quickly, and by no means is it straightforward to remember and comprehend them.
Summarizing: if you want to know more about real physics this book is for you, but be prepared to spend a lot of time and effort, and regard it as studying, not reading.
But maybe it's like the LOTR movies: if you've read the book, they're going amazingly fast, otherwise they progress tediously slow.
I do not seem to recall; what question was that again?