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

Growth Rate in the Dynamical Dark Energy Models

Dark Energy models with slowly-rolling cosmological scalar field provide a popular alternative to the standard, time-independent cosmological constant model. We study simultaneous evolution of background expansion and growth in the scalar field model with the Ratra-Peebles self-interaction potential. We use recent measurements of the linear growth rate and the baryon acoustic oscillation peak positions to constrain the model parameter $\alpha$ that describes the steepness of the scalar field potential.Comment: 7 pages, 6 figures, discussions and references added; conclusions unchange

Current status of cosmological MDM model

An analysis of cosmological models in spatially flat Friedmann Universe with cosmic gravitational wave background and zero $\Lambda$-term is presented. The number of free parameters is equal to 5, they are $\sigma_8$, $n$, $\Omega_\nu$, $\Omega_b$, and $h$. The normalization of the spectrum of density perturbations on galaxy cluster abundance ($\sigma_8 = 0.52\pm 0.04$) has been used to calculate numerically the value of the large scale CMB anisotropy ($\ell\simeq 10$) and the relative contribution of cosmological gravitational waves T/S. Increasing $\Omega_\nu$ weaken the requirements to the value of T/S, however even for $\Omega_\nu\le 0.4$ the models with $h+n\ge 1.5$ suggest considerable abundance of gravitational waves: T/S${}^>_\sim 0.3$. In models with $\Omega_\nu\le 0.4$ and scale-invariant spectrum of density perturbations ($n=1$): T/S${}^>_\sim 10(h-0.47)$. Minimization of the value T/S is possible only in the range of the red spectra ($n<1$) and small $h$ ($<0.6$). It is shown that the models with T/S$\in [0, 3]$ admit both moderate red and blue spectra of density perturbations, $n\in[0.9,1.2]$, with rather high abundance hot dark matter, $\Omega_\nu\in [0.2,0.4]$. Any condition, $n<0.9$ or $\Omega_\nu<0.2$, decreases the relative amplitude of the first acoustic peak for more than 30% in comparison with its hight in the standard CDM normalized by COBE data.Comment: 4 pages, 2 figures included; contribution to the Proceedings of Moriond 2000 "Energy Densities in the Universe", Les Arcs, France, January 22-29 200

The level of unemployment in Ukraine

Contents: Available Nitrogen. Relationship between available soil nitrogen and plant growth - 80GH5. The value of organic matter (\u3e2m) to available soil nitrogen - 67C13 & 67N4. The effect of cropping systems on organic matter - 67C13. The effect of organic matter on plant growth. Incorporating wheat and clover (tops/roots/ burrs) at different rates - 80GH2. Seeding of clover at different rates - 80GH6. Incubation of organic matter - 80GH4. Germination problems after organic matter - 80GH8. Pre-Seeding Application of Nitrogen on cereals - 80A2. Lupin/oat mixture trials - 79MT30, 79BA31, . Mount Barker. Badgingarra. The effect of clover seeding rates on dry matter production - 80MT3, 80WH5

A priori estimates for quasilinear parabolic systems with quadratic nonlinearities in the gradient

summary:We derive local a priori estimates of the Hölder norm of solutions to quasilinear elliptic systems with quadratic nonlinearities in the gradient. We assume higher integrability of solutions and smallness of its BMO norm but the Hölder norm is estimated in terms of BMO norm of the solution under consideration, only