The casimir free energy in high- and low-temperature limits

The problem with the temperature dependence of the Casimir force is investigated. We analyse high-temperature limit analytically making calculations at real frequencies. The purpose is to answer the questionwhy there is no continuous transition between real and ideal metals and why the result\ud does not depend on the relaxation frequency. It is found that the contribution of evanescent s polarized fields is finite even for an infinitely small relaxation frequency (plasma model) and exactly cancels the contribution of propagating fields. For the ideal metal the evanescent fields do not contribute at all. The lowtemperature\ud limit is analysed to establish behaviour of the entropy at T → 0. It is stressed that the nonlocal effects are important in this limit because the mean free path for electrons becomes larger than the field penetration depth.\ud In this limit vF /a plays the role of the relaxation frequency, where vF is the Fermi velocity and a is the distance between plates. It is indicated that the\ud Leontovich approximate impedance cannot be used for calculations because it is good for the description of propagating but not evanescent fields. It is found\ud that due to nonlocality the Casimir entropy approaches zero at T → 0 when s polarization does not contribute to the classical part of the Casimir force

Casimir force calculations near the insulator-conductor transition in gold thin films

We present theoretical calculations of the Casimir force for Au thin films near the insulator-conductor transition that has been observed experimentally. The dielectric function of the Au thin films is described by the Drude-Smith model. The parameters needed to model the dielectric function such as the relaxation time, plasma frequency and the backscattering constant depend on the thickness of the film. The Casimir force decreases as the film thickness decreases until it reaches a minimum after which the force increases again. The minimum of the force coincides with the critical film thickness where a percolation conductor-insulator occurs.Comment: 5 figures, 1 tabl

Pediatric liver transplantation

Liver transplantation, which once was an experimental procedure of no practical interest, has become the preferred treatment for infants and children dying of almost all non-neoplastic end-stage liver diseases. Liver replacement is being provided by many well-trained teams on all of the continents, as is evident from the program today - the first international symposium on pediatric liver transplantation. I have been honored in giving the first paper in the process of introducing the remarkable work of a gifted younger generation of physicians and surgeons