Domain: cnrs.fr
Stories and comments across the archive that link to cnrs.fr.
Comments · 19
-
Re:Dark Matter Filaments
On the basis of this equation, the optical energy flow can be deflected by a magnetic field
found here http://lpm2c.grenoble.cnrs.fr/...
Funny, there seems to be something else that can bend light in our universe. -
Re:something new.
I won't assume anything about Italian and Spanish, but would love to hear if it's also a big PITA to write in those languages.
Spanish and Italian suck because of low information density. To many letters/syllables to make your point. http://www.ddl.ish-lyon.cnrs.f... (Table 1 on Page 40).
-
Re:link to 2010 CNRS press release
Looks cool, indeed.
-
Strong Magnets! (but only transient)
I used to work next to the french Laboratoire National des Champs Magnétiques Intenses (Powerful Magnetic Field National Laboratory) and was lucky enough to visit it once during the yearly Science Day (why don't we have this in the US?).
They claimed they had the second most powerful magnets in the world, IIRC behind the Fermilab, at about 32T (again, IIRC). Note that this is a sustained magnetic field, not transient as the OP's record. (still, hitting 100T without destroying the magnet is one hell of a feat! Now if only we could find a source of power to sustain such a field...).
32T is extremely high, more powerful than any natural magnetic field on Earth (according to WP, the Earth's field is about 25uT at the equator to 65uT at the poles). The most powerful permanent magnets (rare-earth) can achieve a little under 1T, and good luck getting that magnet off a piece of steel. 32T is achieved only in a space about the size of 2 coke-cans at the center of a large cylindrical apparatus that is the concentric electromagnets. But even at such a strength, the fields we make are dwarfed by stellar and interstellar magnetic fields, that have been calculated to reach hundreds or thousands of Teslas.
Fun facts: they run the magnets at night, when power is significantly cheaper. They have big banks of capacitors and batteries for spare surge power. The (classical) electromagnets aren't built by spooling wire on a tube, because wire isn't thick enough the sustain the kind of current that goes through. Instead they take a thick copper tube that they slice in a spiral and insert an isolator in the spacing.
Their most powerful magnets were formed of a core superconducting electromagnet surrounded by standard electromagnets. The cost of superconducting materials is what prevent them from making more powerful stuff.
But despite all that, I'm still not sure what kind of experiments require such powerful magnetic fields. Such awesome engineering, so few applications...
-
Re:And conveniently enough
Dude, seriously step back a sec and think about it:
This: http://www.insu.cnrs.fr/co/univers/les-exoplanetes/un-disque-cyan-dans-un-ciel-pourpre-coucher-de-soleil-sur-osiris is the official link
This: http://blogs.discovermagazine.com/badastronomy/2012/01/09/sunset-on-an-alien-world/ is an article targeting laymen. It's from Discover *Magazine*. It's science entertainment, not a peer reviewed journal. The 'planet' your so upset about is an artist paid to slap together something for people to look at the pretty colors. -
frustration...
google: http://www.googleartproject.com/museums/vangogh/the-bedroom iipimage: http://merovingio.c2rmf.cnrs.fr/iipimage/showcase/zoom.php?path=%2Fbaie3%2Fpyr-F5%2FF5702%2FHD3%2FHD3_pyr_000_090.tif The problem is that we don't have their money!
:( -
Re:Some more food for thought...
Heh heh
... god forbid you should give "equal time" to climatologists!
Personally I'm not too fussed whether this is "normal" climate ... in fact I don't see why you are so keen to make the point - who cares?! I just like the fact that, at this temperature, the city where I live is above sea level. Maybe this is "abnormally cold" by long-term standards, but really, so what? Even if global warming were caused almost entirely by increased solar radiation (which it is not) - what does that matter? Do you think that lets us off having to do anything about it?
We are well advised to try to do our best to keep the global climate stable, whether that's (so-called) "normal" or not, and whatever is causing it. Sure we can't turn down the sun when it gets brighter, but we can reduce greenhouse gas emissions to compensate.
BTW, do you honestly doubt that the recently-enhanced CO2-levels in the atmosphere are warming up the Earth's surface? Seriously? I mean ... do you think that paleoclimatologists are trying to hoax us? Didn't you study physics at school? Did you not cover the greenhouse effect? Are you just unaware of fossil evidence linking CO2 and temperatures, going back hundreds of thousands of years? http://www.cnrs.fr/cw/en/pres/compress/mist030699. html
You will always find some mavericks to dispute any science (see the Discover Institute), but you are kidding yourself if you think that climatologists in general are in doubt about it. Pretending that it's still too early to take seriously while there's not 100% consensus just makes you look naive and silly, frankly.
Also, I don't care that animals from millions of years ago wouldn't like today's climate - it doesn't matter now because those animals are extinct. In the long term, if the climate continues to warm, humans and other animals will continue to adapt. Polar bears will die out, but when the Earth cools down again similar animals will evolve to fill the polar niche again. A few tens of thousands of years should be ample. But your long-term sang-froid is not much comfort to people of the next 100 years having to live with the consequences of rapid global warming, though.
You sound very defensive in your eagerness to deflect the "blame" onto something other than humans - are you secretly a guilty SUV-driver or something?
BTW, perhaps we are due for a bit of global cooling ... but remeber that right at the moment we are in fact in a period of rapid warming, correlated strongly with rapid increases in greenhouse-gas concentrations. Let's leave hypothetical problems of the future to the future, shall we, and instead try fixing the actual problem of the present? Because if it turns out that we are up for an ice age we will be fine because we now have an established technique for averting it - burning fossil fuel. You can get your SUV back out of the garage then. -
Re:Mythbusters
I always like those arguments that basically say "THEY could ot have done X because I can't figure out how to do X" The fact that some guy could not figure out how to burn wood with a mirror does not mean that one of the smartest guys in all of history could not have. In later centurys it was common to build solar furnaces Here is a link to the largest modern solor reflector http://www.imp.cnrs.fr/foursol/1000_en.shtml
-
1000 KW "death ray"General technical specifications
The parabolic reflector gaves at the focal point a maximum flux of 1000 W/cm2. The experimentations takes place at the focal zone (18 m in front of the paraboloid. The range of available temperature is from 800 to 2500 C (the maximum reachable temperature is 3800 C) for a maximum thermal power of 1000 kW.
-
a small paper from french CNRS on that subject
http://www.cnrs.fr/Cnrspresse/Archives/n347a2.htm
l
Paper is dated from 1997, so it's not such a news item.
You can also peruse the full pdf (http://www.cnrs.fr/Cnrspresse/n403/pdf/n403rd09.p df) from July 2002 explainig how this research we just learned from came to be......
As far as parasistic behaviour go, I have a peculiar liking for "La petite Douve du Foie" :
Dicrocoelium dendriticum (the lancet liver fluke)
"Dicrocoelium dendriticum is called the lancet liver fluke because of its characteristic shape. Unlike most other digenetic trematodes whose life cycles involve aquatic or marine hosts, the life cycle of this parasite is completely terrestrial involving a terrestrial snail as the first intermediate host and an ant as the second intermediate host. The definitive host, which includes sheep, cattle, goats, pigs, and humans (rarely), is infected when it ingests ants that are infected with metacercariae (view diagram of the life cycle). In the definitive host the parasite migrates into the bile duct and causes pathology similar to that caused by Clonorchis sinensis. This parasite is distributed throughout much of Europe and Asia, and it is also found in parts of North America and Australia."http://www.biosci.ohio-state.edu/~paras ite/dicrocoelium.html
What is most interesting with Dicrocoelium dendriticum is that it hijacks the ant and make it climb on grass during full daylight and hold tight with it's mandible so it has a greatest chance of being eaten by a passing sheep - quite un-ant like..
if the ant is not successfull in its "suicide" it will do the same thing day after day until the larva dies or it is eaten... -
a small paper from french CNRS on that subject
http://www.cnrs.fr/Cnrspresse/Archives/n347a2.htm
l
Paper is dated from 1997, so it's not such a news item.
You can also peruse the full pdf (http://www.cnrs.fr/Cnrspresse/n403/pdf/n403rd09.p df) from July 2002 explainig how this research we just learned from came to be......
As far as parasistic behaviour go, I have a peculiar liking for "La petite Douve du Foie" :
Dicrocoelium dendriticum (the lancet liver fluke)
"Dicrocoelium dendriticum is called the lancet liver fluke because of its characteristic shape. Unlike most other digenetic trematodes whose life cycles involve aquatic or marine hosts, the life cycle of this parasite is completely terrestrial involving a terrestrial snail as the first intermediate host and an ant as the second intermediate host. The definitive host, which includes sheep, cattle, goats, pigs, and humans (rarely), is infected when it ingests ants that are infected with metacercariae (view diagram of the life cycle). In the definitive host the parasite migrates into the bile duct and causes pathology similar to that caused by Clonorchis sinensis. This parasite is distributed throughout much of Europe and Asia, and it is also found in parts of North America and Australia."http://www.biosci.ohio-state.edu/~paras ite/dicrocoelium.html
What is most interesting with Dicrocoelium dendriticum is that it hijacks the ant and make it climb on grass during full daylight and hold tight with it's mandible so it has a greatest chance of being eaten by a passing sheep - quite un-ant like..
if the ant is not successfull in its "suicide" it will do the same thing day after day until the larva dies or it is eaten... -
Re:Ha! You call that a solar death ray?
Mu, uhh, death ray is bigger than your death ray
The parabolic reflector gaves at the focal point a maximum flux of 1000 W/cm2. The experimentations takes place at the focal zone (18 m in front of the paraboloid. The range of available temperature is from 800 to 2500 C (the maximum reachable temperature is 3800 C) for a maximum thermal power of 1000 kW.
Picture of the Odeillo Solar Furnace -
Feh, Kid's stuff
This one is a bit bigger!
The parabolic reflector gaves at the focal point a maximum flux of 1000 W/cm2. The experimentations takes place at the focal zone (18 m in front of the paraboloid. The range of available temperature is from 800 to 2500 C (the maximum reachable temperature is 3800 C) for a maximum thermal power of 1000 kW.
(Did someone just say holy fucking shit?)
Picture of the Odeillo Solar Furnace -
*different* link
There's a (not yet
/.-ed) link: http://hal.ccsd.cnrs.fr/docs/00/00/32/74/PDF/The-r oots-of-any-polynomial-equation.pdf Also I'm afraid that it's been done before http://library.wolfram.com/examples/quintic/main.h tml#diffeq -
Re:Man does the impossible
(Can't read PDF; slashdotted) PDF of the same name here, presume it's the same document.
-
Re:/.ed after 4 comments
-
Re:Non-linear Schrodinger Equation
You're probably looking for the paper titled "Physical Mechanisms of the Rogue Wave Phenomenon"
by Christian Kharif and Efim Pelinovsky. It includes several photographs of rogue waves, and all the derived mathematical equations. -
Solar furnaces
Solar furnaces like this one: http://www.imp.cnrs.fr/foursol/1000_en.shtml look like fun too
:)
The setup can produce 1000kW of heat in a very small area, and temperatures of up to 4000 Celsius. -
Foucault Pendulum + Topology, a point of suspicion
I bet most nonphysics
/. readers will find the original Bogdanov papers quite difficult to read, and perhaps the theses even more so since they are in French. But I can show here some very simple things that will make nonphysics reader very suspicious about the Bogdanov twin's work.As some
/. readers have pointed out already, John Baez, the UCI physics prof, criticizes a very specific passage from one thesis, involving the Foucault pendulum part. You don't have to read everything, just see that Bogdanov mentions the pendulum and topology in one breath! here I quote from Baez's webpage:"It goes on to discuss the supposed connection between N = 2 supergravity, Donaldson theory, KMS states and the Foucault pendulum experiment, which he claims "cannot be explained satisfactorily in either classical or relativistic mechanics". If you know some physics you'll find this statement slightly odd.
After several pages he concludes: We draw from the above that whatever the orientation, the plane of oscillation of Foucault's pendulum is necessarily aligned with the initial singularity marking the origin of physical space S3, that of Euclidean space E4 (described by the family of instantons Ibeta of whatever radius beta), and, finally, that of Lorentzian space-time M4.
Zounds! He took that pendulum and rode it right off into hyperspace..."
And this Foucault pendulum quote you can obtain directly from one Bogdanov thesis.
The Foucault pendulum bit is on page 49/162 of the thesis, in French. It's easy to read and probably will parse in babelfish.
So what's the big hoopla about Foucault's pendulum and the supergravity stuff? Well, Foucault's pendulum, contrary to the Bogdanov thesis that it's not understood in classical mechanics, is really well understood, at least the regular ole' Foucault pendulum. It's basically a free-swinging pendulum, that over time, rotates its plane of swinging because of the Coriolis force. You can check it out in any decent undergrad mechanics text, such as my dusty copy of Marion/Thornton classical dynamics, page 399, where the solution is quietly sitting. Or you can read this little web tidbit.
That a PHD physics candidate would be trying to tell us there is some connection between the very earthly, understood Foucault pendulum, and the big bang (initial singularity) really stretches the imagination! But again, this just makes one suspicious, and doesn't prove anything.