Measurements of the dc resistivity of surface-state electrons on liquid helium exposed to microwave radiation are reported. It is shown that the resonant microwave excitation of surface-state electrons is accompanied by a strong increase in their resistivity, which is opposite to the result expected from the previously used two-level model. We show that even a very small fraction of electrons excited to the first excited state and decaying back due to vapor-atom scattering strongly heat the electron system, causing a population of higher subbands. The calculated resistivity change is in good agreement with the observed data.

No abstract

A resonance-induced change in the resistivity of the surface state electrons (SSE) exposed to the microwave (MW) radiation is observed. The MW frequency corresponds to the transition energy between two lowest Rydberg energy levels. All measurements are done with electrons over liquid 3 He in a temperature range 0.45−0.65 K, in which the electron relaxation time and the MW absorption linewidth are determined by collisions with helium vapor atoms. The input MW power is varied by two orders of magnitude, and the resistivity is always found to increase. This effect is attributed to the heating of electrons with the resonance MW radiation. The temperature and the momentum relaxation rate of the hot electrons are calculated as a function of the MW power in the cell, and the Rabi frequency is determined from the comparison of the theoretical result with the experiment. In addition, the broadening of the absorption signal caused by the heating is studied experimentally, and the results are found to be in good agreement with our calculations.

We present a case of a gradually developing ischaemic contracture of the forearm muscles of an infant who developed without any trauma or acute gangrene at birth. Release of the middle and ring finger digitorum profundus muscles and pronator quadratus at 2 years of age corrected the deformity. Histopathology showed no evidence of fibromatosis or any other tumor. Although a dynamic splint was used to maintain the range of motion, the range of the middle finger motion deteriorated gradually 2 years after surgery. Though the pathogenesis of this problem was unclear, we assume that it was caused by fibrosis of muscles as a result of bleeding before or during delivery.

We report on the experimental study of the resonance microwave absorption of surface-state electrons (SSE) on liquid 3He. The absorption is detected as a variation of the microwave power passing through the experimental cell, or as a resonance-induced change in the electron conductivity. In the latter method a decrease of the conductivity is observed, which points out on the possibility of substantial heating of the electrons by the absorbed microwave power. In a vapor-atom scattering regime the temperature dependence of the linewidth agrees well with the theoretical model, and the absolute value of the measured linewidth is about twice larger than the theoretical one. At very high microwave power the side band absorption peaks are observed.

No abstract

No abstract

We present a rare case of a lateral dislocation of the proximal interphalangeal joint that required open reduction. During an operation, we found the collateral ligament and the capsule interposing into the joint space. After reducing the soft tissue and reproducing the collateral ligament with a suture anchor, sufficient joint stability and full range of motion was achieved.