I have noticed that the "last 24 hour" and "show all users posts" functions often return the following error message:
"You cannot make another search at this time. Please try again in a few minutes.
Please use your back button to return to the previous page."
A Safari/Mac OS X issue?
I have had exactly the same problem ever since the latest (most excellent) upgrade.
I am running Win98 and IE 6.0.2800, so it wouldn't appear to be completely OS/browser specific.
This is the last apparent bug to persist on my configuration, all the others have been resolved at least on my machine.
A thank you to Magister Ventrue for all of his hard work: LttD is the most elegant/supercharged/just plain cool message board system online I know of.
Helium II is a superfluid, a quantum mechanical state of matter with strange properties .
The thermal conductivity of helium II is greater than that of any other known substance, a million times that of helium I and hundred of times that of copper. This is because heat conduction occurs via a quantum mechanism.
Second sound is a quantum mechanical phenomenon in which heat transfer occurs by wave-like motion, rather than by the usual mechanism of diffusion. Heat takes the place of pressure in normal sound waves. This leads to very high thermal conductivity. It's known as "second sound" because the wave motion of heat is similar to the propagation of sound in air.
Sound waves are fluctuations in the density of molecules in a substance; second sound waves are fluctuations in the density of phonons. Second sound can be observed in any system in which most phonon-phonon collisions conserve momentum. This occurs in superfluids and in dielectric crystals when Umklapp scattering is small.