Links for 2010-05-08

“Liquid Mountaineering is a new sport which is attempting to achieve what man has tried to do for centuries: walk on water. Or to be more precise: running on water. We are developing the sport from scratch. By accident we found out that with the right water repellent equipment you can run across bodies of water, just like a stone skimming the surface.”

“Cooperative scattering of light by an extended object such as an atomic ensemble or a dielectric sphere is fundamentally different from scattering from many pointlike scatterers such as single atoms. Homogeneous distributions tend to scatter cooperatively, whereas fluctuations of the density distribution increase the disorder and suppress cooperativity. In an atomic cloud, the amount of disorder can be tuned via the optical thickness, and its role can be studied via the radiation force exerted by the light on the atomic cloud. Monitoring cold 87Rb atoms released from a magneto-optical trap, we present the first experimental signatures of radiation force reduction due to cooperative scattering. The results are in agreement with an analytical expression interpolating between the disorder and the cooperativity-dominated regimes.”

“Currently, laser cooling schemes are fundamentally based on the weak coupling regime. This requirement sets the trap frequency as an upper bound to the cooling rate. In this work we present a numerical study that shows the feasibility of cooling in the strong-coupling regime which then allows cooling rates that are faster than the trap frequency with experimentally feasible parameters. The scheme presented here can be applied to trapped atoms or ions as well as to mechanical oscillators. It can also cool medium sized ion chains close to the ground state.”

“One of the discussions that happened while I was snowed under with work involved Henry Louis Gates Jr.’s New York Times op-ed about slavery and reparations. Gates argued that because Africans themselves were the principal slavers who fueled the Atlantic slave trade, the question of reparations is a permanently vexed one.

Africanist historians have been round the bend on this conversation before many times, not just about the overall issue of African participation in the slave trade, but specifically about Gates’ interventions into that discussion. After his Wonders of the African World television series, there was a well-attended panel at the African Studies Association meeting that year which pilloried Gates for his many perceived slights to Africa and Africans.[…]

That said, I do have a few things to add to the discussion as it has developed across listservs and blogs. “

“There has been lots of riots and protests from both anarchists and workers in Athens, Greece specially the past few years. One interesting thing is that there is one dog that is spotted at these riots from 2008 till today”