Influence of Photoexcitation Depth on Luminescence Spectra of Bulk GaAs Single Crystals and Defect Structure Characterization

The results of investigation of bulk GaAs photoluminescence are presented taken from near-surface layers of different thicknesses using for excitation the light with the wavelengths which are close but some greater than the excitonic absorption resonances (so-called bulk photoexcitation). Only the excitonic and band-edge luminescence is seen under the interband excitation, while under the bulk excitation, the spectra are much more informative. The interband excited spectra of all the samples investigated in the present work are practically identical, whereas the bulk excited PL spectra are different for different samples and excitation depths and provide the information on the deep-level point defect composition of the bulk materials.Comment: Aalborg Summer School on Nonlinear Optics, Aalborg, Denmark, 7-12 August 199

Polarization-dependent transformation of a paraxial beam upon reflection and refraction: a real-space approach

We analyze the paraxial beam transformation upon reflection and refraction at a plane boundary. In contrast to the usual approach dealing with the beam angular spectrum, we apply the continuity conditions to explicit spatial representations of the electric and magnetic fields on both sides of the boundary. It is shown that the polarization-dependent distortions of the beam trajectory (in particular, the "longitudinal" Goos-H\"anchen shift and the "lateral" Imbert-Fedorov shift of the beam center of gravity) are directly connected to the incident beam longitudinal component and appear due to its transformation at the boundary.Comment: 10 pages, 1 figure. Formulae (32), (33), footnote 2 and Ref. 27 are added, some sentences are correcte

PROSPECTIVE GROWTH STIMULATORS OF BACTERIAL MASS OF STAPHYLOCOCCUS AUREUS (TO PRODUCE PROTEIN А)

The influence of 2-hydroxyethylammonium salts of biologically active arylsulfanylacetic acids on the yield of bacterial mass of Staphylococcus aureus (strain 209), biomass of Merezhkovsky's bacteria (Salmonella typhi spermophilorum.) and E. coli (E. coli М-17) has bee studied for the first time. The introduction of growth stimulators (in concentration of 10-3-10-8 wt. %) into nutrient medium increases the yield of microorganisms bacterial mass: Staphilococcus aureus by 32-40 %, Merezhkovsky's bacteria Salmonella typhi spermophilorum. by 47,5-140,4 %, E. coli by 11,4-59,4 %. The increase of yield of the microorganisms biomass reached by application of the growth stimulators opens the route to their utilization in large-scale processes of Staphilococcus aureus cultivation for the production of valuable protein А, biopreparations, diagnostic agents, serum, vaccines, probiotic drugs as well as for the struggle with rodents (plaque carriers, pests)

A New Precision Measurement of the 7Be(p,gamma)8B Cross section with an Implanted 7Be Target

The 7Be(p,gamma)8B reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted 7Be target, a raster scanned beam and the elimination of the backscattering loss. The new measurement incorporates a more abundant 7Be target and a number of improvements in design and procedure. The point at Elab=991 keV was measured several times under varying conditions, yielding a value of S17(Ec.m. =850 keV) = 24.0(5) eV b. Measurements were carried out at lower energies as well. Due to the precise knowledge of the implanted 7Be density profile it was possible to reconstitute both the off- and on resonance parts of the cross section and to obtain from the entire set of measurements an extrapolated value of S17(0)=21.2(7) eV b.Comment: 4 Pages, 3 Figure

β\beta - decay of the MT_{T}=-1 nucleus 58^{58}Zn studied by selective laser ionization

$\beta$ - decay of $^{58}$Zn has been studied for the first time. A new laser ion-source concept has been used to produce mass-separated sources for $\beta$ and $\gamma$ - spectroscopy. The half-life of $^{58}$Zn was determined to be 86(18) ms. Comparisons are made with previous data from charge-exchange reactions. Our Gamow-Teller strength to the 1$^{+}$ state at 1051 keV excitation in $^{58}$Cu agrees well with the value extracted from a recent ($^{3}$He, t) study. Extensive shell-model calculations are presented

Диагностика лекарственной непереносимости на эритроцитарной модели

This study intended to elaborate an erythrocytic model approach to diagnosis of drug sensibilisation through an evaluation of lipid peroxidation and the electrophoretic mobility of erythrocytes.The contact of erythrocytes with causal drugs resulted in a major increase of dien conjugate levels and an increased percentage of erythrocytes with a high electrophoretic mobility.The erythrocytic model revealed effects of the causal drug even in patients taking glucocorticoids.Целью исследования явилась разработка подхода к диагностике лекарственной непереносимости с помощью эритроцитарной модели на основе оценки перекисного окисления липидов и электрофоретической подвижности эритроцитов.Было показано, что контакт с причинно-значимым лекарственным агентом приводил в эритроцитах к существенному нарастанию уровня диеновых конъюгатов, а также к нарастанию процента содержания эритроцитов с большой электрофоретической подвижностью.Эффект влияния причинно-значимого лекарственного агента выявлен с помощью эритроцитарной модели даже у больных, получающих глюкокортикоидные препараты

Internal flows and energy circulation in light beams

We review optical phenomena associated with the internal energy redistribution which accompany propagation and transformations of monochromatic light fields in homogeneous media. The total energy flow (linear-momentum density, Poynting vector) can be divided into spin part associated with the polarization and orbital part associated with the spatial inhomogeneity. We give general description of the internal flows in the coordinate and momentum (angular spectrum) representations for both nonparaxial and paraxial fields. This enables one to determine local densities and integral values of the spin and orbital angular momenta of the field. We analyse patterns of the internal flows in standard beam models (Gaussian, Laguerre-Gaussian, flat-top beam, etc.), which provide an insightful picture of the energy transport. The emphasize is made to the singular points of the flow fields. We describe the spin-orbit and orbit-orbit interactions in the processes of beam focusing and symmetry breakdown. Finally, we consider how the energy flows manifest themselves in the mechanical action on probing particles and in the transformations of a propagating beam subjected to a transverse perturbation.Comment: 50 pages, 21 figures, 173 references. This is the final version of the manuscript (v1) modified in accord to the referee's remarks and with allowance for the recent development. The main changes are: additional discussion of the energy flows in Bessel beams (section 4.1), a lot of new references are added and the Conclusion is shortened and made more accurat