Практикум з мовної комунікації (англійська мова)

Навчально-методичний посібник з курсу "Практикум з мовної комунікації (англійська мова)" призначено для формування та удосконалення знань і навичок, необхідних для високого практичного володіння англійською мовою, точного та всебічного розуміння оригінальних англійських текстів, а також подальшого поповнення словникового запасу студентів. У навчально-методичному посібнику наведені вправи з лексики, граматики та говоріння, пропонуються тексти з проходження співбесід та відповідні завдання для розвитку навичок письмового та усного мовлення

Features of resistance of major pathogens of respiratory tract infections in Dnipropetrovsk region.

According to the retrospective analysis of data obtained for the period of the last four years, the resistance level of major infectious agents (Strepto­coccus pneumoniae, Hаemophilus influenzaе)  to the most of commonly used classes of antibacterial agents (β-lactams, macrolides, lincosamides, fluoroquinolones) was rather low, except for the established resistance level of penicillin-resistant Streptococcus pneumoniae (19% of tested strains were resistant to oxacillin). Multiply resistance of Streptococcus pneumoniae strains in Dnipropetrovsk region was 4,3%. Prognosed by world-wide trials growth of bacterial resistance levels requires decrease of the irrational antibiotics using and constant monitoring of resistance in each region and in the country as a whole to preserve the potential of clinical effective antibacterial agents

Multiple Andreev reflections and enhanced shot noise in diffusive SNS junctions

We study the dc conductance and current fluctuations in diffusive voltage biased SNS junctions with a tunnel barrier inside the mesoscopic normal region. We find that at subgap voltages, eV<2Delta/n, the current associated with the chain of n Andreev reflections is mapped onto the quasiparticle flow through a structure of n+1 voltage biased barriers connected by diffusive conductors. As a result, the current-voltage characteristic of a long SNINS structure obeys Ohm's law, in spite of the complex multiparticle transport process. At the same time, nonequilibrium heating of subgap electrons produces giant shot noise with pronounced subharmonic gap structure which corresponds to stepwise growth of the effective transferred charge. At eV\to 0, the shot noise approaches the magnitude of the Johnson-Nyquist noise with the effective temperature T^*=Delta/3, and the effective charge increases as (e/3)(1 + 2Delta/eV), with the universal ``one third suppression'' factor. We analyse the role of inelastic scattering and present a criterion of strong nonequilibrium.Comment: 4 pages, 2 figure

On the theory of Josephson effect in a diffusive tunnel junction

Specific features of the equilibrium current-carrying state of a Josephson tunnel junction between diffusive superconductors are studied theoretically in the 1D geometry. It is found that the Josephson current induces localized states of electron excitations in the vicinity of the tunnel barrier, which are a continuous analog of Andreev levels in a ballistic junction. The depth of the corresponding ``potential well'' is much greater than the separation between an Andreev level and the continuous energy spectrum boundary for the same transmissivity of the barrier. In contrast to a ballistic junction in which the Josephson current is transported completely by localized excitations, the contribution to current in a diffusive junction comes from whole spectral region near the energy gap boundary, where the density of states differs considerably from its unperturbed value. The correction to the Josephson current in the second order of the barrier transmissivity, which contains the second harmonic of the phase jump, is calculated and it is found that the true expansion parameter of the perturbation theory for a diffusive junction is not the tunneling probability $\Gamma$ itself, but a much larger parameter $W = (3\xi_0/4l)\Gamma$.Comment: 8 pages, 5 Postscript figures, submitted to Low Temp. Phy

Subgap current in superconducting tunnel junctions with diffusive electrodes

We calculate the subgap current in planar superconducting tunnel junctions with thin-film diffusive leads. It is found that the subharmonic gap structure of the tunnel current scales with an effective tunneling transparency which may exceed the junction transparency by up to two orders of magnitude depending on the junction geometry and the ratio between the coherence length and the elastic scattering length. These results provide an alternative explanation of anomalously high values of the subgap current in tunnelling experiments often ascribed to imperfection of the insulating layer. We also discuss the effect of finite lifetime of quasiparticles as the possible origin of additional enhancement of multiparticle tunnel currents.Comment: 4 pages, 4 figures, to be published in Phys. Rev.

Circuit theory of multiple Andreev reflections in diffusive SNS junctions: the incoherent case

The incoherent regime of Multiple Andreev Reflections (MAR) is studied in long diffusive SNS junctions at applied voltages larger than the Thouless energy. Incoherent MAR is treated as a transport problem in energy space by means of a circuit theory for an equivalent electrical network. The current through NS interfaces is explained in terms of diffusion flows of electrons and holes through tunnel and Andreev resistors. These resistors in diffusive junctions play roles analogous to the normal and Andreev reflection coefficients in OTBK theory for ballistic junctions. The theory is applied to the subharmonic gap structure (SGS); simple analytical results are obtained for the distribution function and current spectral density for the limiting cases of resistive and transparent NS interfaces. In the general case, the exact solution is found in terms of chain-fractions, and the current is calculated numerically. SGS shows qualitatively different behavior for even and odd subharmonic numbers, and the maximum slopes of the differential resistance correspond to the gap subharmonics. The influence of inelastic scattering on the subgap anomalies of the differential resistance is analyzed.Comment: 14 pages, 9 figures, title and text revised, to appear in PR

Current noise in long diffusive SNS junctions in the incoherent MAR regime

Spectral density of current fluctuations at zero frequency is calculated for a long diffusive SNS junction with low-resistive interfaces. At low temperature, T << Delta, the subgap shot noise approaches linear voltage dependence, S=(2/ 3R)(eV + 2Delta), which is the sum of the shot noise of the normal conductor and voltage independent excess noise. This result can also be interpreted as the 1/3-suppressed Poisson noise for the effective charge q = e(1+2Delta/eV) transferred by incoherent multiple Andreev reflections (MAR). At higher temperatures, anomalies of the current noise develop at the gap subharmonics, eV = 2Delta/n. The crossover to the hot electron regime from the MAR regime is analyzed in the limit of small applied voltages.Comment: improved version, to be published in Phys. Rev.

DC current through a superconducting two-barrier system

We analyze the influence of the structure within a SNS junction on the multiple Andreev resonances in the subgap I-V characteristics. Coherent interference processes and incoherent propagation in the normal region are considered. The detailed geometry of the normal region where the voltage drops in superconducting contacts can lead to observable effects in the conductance at low voltages.Comment: 11 pages, including 7 postscript file

Theory of AC Josepson Effect in Superconducting Constrictions

We have developed a microscopic theory of ac Josephson effect in short ballistic superconducting constrictions with arbitrary electron transparency and in constrictions with diffusive electron transport. The theory is valid for arbitrary miscroscopic structure of the superconducting electrodes of the constriction. As applications of the theory we study smearing of the subgap current singularities by pair-breaking effects and also the structure of these singularities in the constrictions between the composite S/N electrodes with the proximity-induced gap in the normal layer.Comment: 11 pages, RevTex, 3 figures available on reques

Results from the Survey of Antibiotic Resistance (SOAR) 2014–16 in Ukraine and the Slovak Republic

S. pneumoniae isolates collected in Ukraine (n"100) showed susceptibility 97% fratesor amoxicillin, amoxicillin/clavulanic acid, penicillin [intravenous (iv) non-meningitis] and fluoroquinolones, between 83% and 86% for oral penicillin, macrolides and cefaclor, and 75% for trimethoprim/sulfamethoxazole. Susceptibility was substantially lower in the Slovak Republic (n"95). All isolates were susceptible to ratesthe fluoroquinolones, but susceptibility to penicillin, amoxicillin, amoxicillin/clavulanic acid, cefuroxime and trimethoprim/sulfamethoxazole varied between 61% and 64%, with only 44% of isolates susceptible to the macrolides. Susceptibility of H. influenzaewasmorehomogeneous,with susceptibilitytoamoxicillin/clavulanic acid,ceftriaxone,cefuroxime, azithromycin and the fluoroquinolones seen in .90% of isolates by CLSI criteria in both countries. Much greater variability was seen across breakpoints, especially for azithromycin, cefaclor and cefuroxime. The b-lactamase rate was 5.1% (5/98) in the Slovak Republic and 7.3% (7/96) in Ukraine, but the Slovak Republic also had a relativelyhighrateofb-lactamase-negative-ampicillin-resistant(BLNAR)isolates(7.1%;7/98)