Stabilization of class-B broad-area lasers emission by external optical injection

We theoretically examine the effect of external optical injection on the spatio-temporal dynamics of class-B broad-area lasers. We demonstrate that optical injection can efficiently stabilize the intrinsic transverse instabilities in such lasers associated with both the boundaries of the pumping area and with the bulk nonlinearities of the active medium. Stabilizing action of optical injection is shown to be closely related to the suppression of inherent relaxation oscillations behavior.Comment: 8 pages, 7 figure

Giant magnetoimpedance in crystalline Mumetal

We studied giant magnetoimpedance (GMI) effect in commercial crystalline Mumetal, with the emphasis to sample thickness dependence and annealing effects. By using appropriate heat treatment one can achieve GMI ratios as high as 310%, and field sensitivity of about 20%/Oe, which is comparable to the best GMI characteristics obtained for amorphous and nanocrystalline soft magnetic materials.Comment: 8 pages, 3 figure

Position-sensitive detector for the 6-meter optical telescope

The Position-Sensitive Detector (PSD) for photometrical and spectral observation on the 6-meter optical telescope of the Special Astrophysical Observatory (Russia) is described. The PSD consists of a position-sensitive tube, amplifiers of output signals, analog-to-digital converters (ADC) and a digital logic plate, which produces a signal for ADC start and an external strob pulse for reading information by registration system. If necessary, the thermoelectric cooler can be used. The position-sensitive tube has the following main elements: a photocathode, electrodes of inverting optics, a block of microchannel plates (MCP) and a position-sensitive collector of quadrant type. The main parameters of the PSD are the diameter of the sensitive surface is 25 mm, the spatial resolution is better than 100 (\mu)m in the centre and a little worse on the periphery; the dead time is near 0.5 (\mu)s; the detection quantum efficiency is defined by the photocathode and it is not less than 0.1, as a rule; dark current is about hundreds of cps, or less, when cooling. PSD spectral sensitivity depends on the type of photocathode and input window material. We use a multialkali photocathode and a fiber or UV-glass, which gives the short- wave cut of 360 nm or 250 nm, respectively.Comment: 4 pages, 7 figures, to be published in Nuclear Instruments & Methods in Physics Researc

Generation of unipolar half-cycle pulse via unusual reflection of a single-cycle pulse from an optically thin metallic or dielectric layer

We present a significantly different reflection process from an optically thin flat metallic or dielectric layer and propose a strikingly simple method to form approximately unipolar half-cycle optical pulses via reflection of a single-cycle optical pulse. Unipolar pulses in reflection arise due to specifics of effectively one-dimensional pulse propagation. Namely, we show that in considered system the field emitted by a flat medium layer is proportional to the velocity of oscillating medium charges instead of their acceleration as it is usually the case. When the single-cycle pulse interacts with linear optical medium, the oscillation velocity of medium charges can be then forced to keep constant sign throughout the pulse duration. Our results essentially differ from the direct mirror reflection and suggest a possibility of unusual transformations of the few-cycle light pulses in linear optical systems

Dielectric responses of the layered cobalt oxysulfide Sr_2Cu_2CoO_2S_2 with CoO_2 square-planes

We have studied the dielectric responses of the layered cobalt oxysulfide Sr$_2$Cu$_2$CoO$_2$S$_2$ with the CoO$_2$ square-planes. With decreasing temperature below the N\'eel temperature, the resistivity increases like a semiconductor, and the thermopower decreases like a metal. The dielectric constant is highly dependent on temperature, and the dielectric relaxation is systematically changed with temperature, which is strongly correlated to the magnetic states. These behaviors suggest that carriers distributed homogeneously in the paramagnetic state at high temperatures are expelled from the antiferromagnetically ordered spin domain below the N\'eel temperature.Comment: 3 pages, 4 eps figures, to be published in J. Appl. Phy

Expression of TLR1-10 and caspase-3 alfa at women with early miscarriages

Toll-like receptors (TLR) are the first signal receptors of innate immunity, recognizing bacteria and viruses and promoting development of inflammation through the activation of proinflammatory cytokines secretion (1). In animal models it was shown, that TLRs play role in pathogenesis of miscarriages (2, 3) and can influence to trophoblast apoptosis. The aim of research was to investigate study specialty of mRNA expression of TLR1-10 and caspase-3a in endometrium at patients with early miscarriagesyesBelgorod State Universit

Quantum Size Effect transition in percolating nanocomposite films

We report on unique electronic properties in Fe-SiO2 nanocomposite thin films in the vicinity of the percolation threshold. The electronic transport is dominated by quantum corrections to the metallic conduction of the Infinite Cluster (IC). At low temperature, mesoscopic effects revealed on the conductivity, Hall effect experiments and low frequency electrical noise (random telegraph noise and 1/f noise) strongly support the existence of a temperature-induced Quantum Size Effect (QSE) transition in the metallic conduction path. Below a critical temperature related to the geometrical constriction sizes of the IC, the electronic conductivity is mainly governed by active tunnel conductance across barriers in the metallic network. The high 1/f noise level and the random telegraph noise are consistently explained by random potential modulation of the barriers transmittance due to local Coulomb charges. Our results provide evidence that a lowering of the temperature is somehow equivalent to a decrease of the metal fraction in the vicinity of the percolation limit.Comment: 21 pages, 8 figure