Luttinger liquids with curvature: Density correlations and Coulomb drag effect

We consider the effect of the curvature in fermionic dispersion on the observable properties of Luttinger liquid (LL). We use the bosonization technique where the curvature is irrelevant perturbation, describing the decay of LL bosons (plasmon modes). When possible, we establish the correspondence between the bosonization and the fermionic approach. We analyze modifications in density correlation functions due to curvature at finite temperatures, T. The most important application of our approach is the analysis of the Coulomb drag by small momentum transfer between two LL, which is only possible due to curvature. Analyzing the a.c. transconductivity in the one-dimensional drag setup, we confirm the results by Pustilnik et al. for T-dependence of drag resistivity, R_{12} ~ T^2 at high and R_{12} ~ T^5 at low temperatures. The bosonization allows for treating both intra- and inter-wire electron-electron interactions in all orders, and we calculate exact prefactors in low-T drag regime. The crossover temperature between the two regimes is T_1 ~ E_F \Delta, with \Delta relative difference in plasmon velocities. We show that \Delta \neq 0 even for identical wires, due to lifting of degeneracy by interwire interaction, U_{12}, leading to crossover from R_{12} ~ U_{12}^2 T^2 to R_{12} \~ T^5/U_{12} at T ~ U_{12}.Comment: 16 pages, 10 figures, REVTE

Electronic correlations on a metallic nanosphere

We consider the correlation functions in a gas of electrons moving within a thin layer on the surface of nanosize sphere. A closed form of expressions for the RKKY indirect exchange, superconducting Cooper loop and `density-density' correlation function is obtained. The systematic comparison with planar results is made, the effects of spherical geometry are outlined. The quantum coherence of electrons leads to the enhancement of all correlations for the points--antipodes on the sphere. This effect is lost when the radius of the sphere exceeds the temperature coherence length.Comment: 5 pages, no figures, to appear in PRB (RC

Designing of phantom head used in optical diagnostics of brain injury

This article shows the results of an experimental research on properties of the materials chosen for designing of a phantom head, which is to be used in testing of a brain hematoma diagnostics device. We have conducted a comparative research of the optical properties of model materials and real head tissue

High efficiency and low absorption Fresnel compound zone plates for hard X-ray focusing

Circular and linear zone plates have been fabricated on the surface of silicon crystals for the energy of 8 keV by electron beam lithography and deep ion plasma etching methods. Various variants of compound zone plates with first, second, third diffraction orders have been made. The zone relief height is about 10 mkm, the outermost zone width of the zone plate is 0.4 mkm. The experimental testing of the zone plates has been conducted on SPring-8 and ESRF synchrotron radiation sources. A focused spot size and diffraction efficiency measured by knife-edge scanning are accordingly 0.5 mkm and 39% for the first order circular zone plate.Comment: 5 pages, 7 figure

Reversed Switch-On Dynistor Switches of Gigawatt Power Microsecond Pulses

A high-power (250 kA and 25 kV) compact switch based on an assembly of reversed switch-on dynistors (RSDs) connected in series and a coaxial saturable-core choke, which is necessary for their effective switching, is described. An essential feature of this switch is a drastic reduction of the duration of RSDs control pulse, which allows using minimum dimensions and low inductance saturable core choke and obtain high rise rate (more than 30 kA/µs) of the switched current. The increased RSDs control pulse amplitude and rise rate that are required for RSDs switching on by reduced duration triggering pulse are attained by using a fast switch based on new type semiconductor devices deep-level dynistors (DLDs)

Optical-conductivity sum rule in cuprates and unconventional charge density waves: a short review

We begin with an overview of the experimental results for the temperature and doping dependences of the optical-conductivity spectral weight in cuprate superconductors across the whole phase diagram. Then we discuss recent attempts to explain the observed behavior of the spectral weight using reduced and full models with unconventional $d_{x^2-y^2}$ charge-density waves.Comment: 17 pages, RevTeX4, 4 EPS figures; Invited paper for a special issue of Low Temperature Physics dedicated to the 20th anniversary of HTS

Spin-Peierls instability in a quantum spin chain with Dzyaloshinskii-Moriya interaction

We analysed the ground state energy of some dimerized spin-1/2 transverse XX and Heisenberg chains with Dzyaloshinskii-Moriya (DM) interaction to study the influence of the latter interaction on the spin-Peierls instability. We found that DM interaction may act either in favour of the dimerization or against it. The actual result depends on the dependence of DM interaction on the distortion amplitude in comparison with such dependence for the isotropic exchange interaction.Comment: 12 pages, latex, 3 figure

New classes of exact solutions of three-dimensional Navier-Stokes equations

New classes of exact solutions of the three-dimensional unsteady Navier-Stokes equations containing arbitrary functions and parameters are described. Various periodic and other solutions, which are expressed through elementary functions are obtained. The general physical interpretation and classification of solutions is given.Comment: 11 page