Numerical study of vortex system quantum melting

We report a numerical study of the vortex system in the two dimensional II-type superconductors. We have proposed a phenomenological model that takes into account quantum fluctuations of Abrikosov's vortices. The results of the quantum Monte-Carlo simulations by the SSE algorithm show that the thermal fluctuations are dominated by quantum fluctuations at low temperatures. In particular, we demonstrate the possibility of the quantum melting transition for vortex system in the temperature region where thermal melting transition is improbable

Negative magnetoresistance of heavily doped silicon p-n junction

At the liquid helium temperature and under application of magnetic fields up to 9.4 T, a voltage drop across a silicon diode with metallic conductivity of the emitter and base has been measured under passing a constant forward current through the diode. Observed magnetoresistance of the diode is proved as a whole to be extremely small, negative at low fields and changing its sign when the field increases. In the positive region of the diode magnetoresistance, its field dependence is quadratic at first and then becomes close to the linear one. With increase in the current through the diode, the negative component of the diode magnetoresistance decreases, and the smaller its value, the more extended is the quadratic section and the shorter is the linear one. The results are interpreted as caused by hopping conduction over a system of electron “lakes” in the region of p-n junction

Dendritic flux avalanches in superconducting Nb3Sn films

The penetration of magnetic flux into a thin superconducting film of Nb3Sn with critical temperature 17.8K and critical current density 6MA/cm^2 was visualized using magneto-optical imaging. Below 8 K an avalanche-like flux penetration in form of big and branching dendritic structures was observed in response to increasing perpendicular applied field. When a growing dendritic branch meets a linear defect in the film, several scenarios were observed: the branch can turn and propagate along the defect, continue propagation right through it, or "tunnel" along a flux-filled defect and continue growth from its other end. The avalanches manifest themselves in numerous small and random jumps found in the magnetization curve.Comment: 3 pages, 4 figures, submitted to Cryogenics. Revision: M(H) data adde

Медико-организационные аспекты совершенствования ультразвуковой диагностики

One of the important directions of improving ultrasound diagnostics is to improve the resource support of the service. According to the data obtained, 25.2% of ultrasound diagnosticians rated the existing ultrasound equipment as obsolete. 18.9% of respondents reported a lack of consumables for conducting ultrasound examinations, 13.8% of office equipment (printer, scanner, xerox), 10.1% of computers, 11.9% of internal document management software . The proportion of doctors of ultrasound diagnostics dissatisfied with the premises for the workplace amounted to 14.5%.Одним из важных направлений совершенствования ультразвуковой диагностики является улучшение ресурсного обеспечения службы.Согласно полученным данным, 25,2% врачей ультразвуковой диагностики оценили имеющееся ультразвуковое оборудование как устаревшее. О недостатке расходных материалов для проведения ультразвуковых исследований сообщили 18,9% респондентов, оргтехники (принтер, сканер, ксерокс) - 13,8%, компьютеров - 10,1%, программного обеспечения для внутреннего документооборота - 11,9%. Доля врачей ультразвуковой диагностики недовольных помещением для рабочего места составила 14,5%