Specular nonlinear anisotropic polarization effect along fourfold crystal symmetry axes

We present what is to our knowledge the first experimental observation of the specular nonlinear anisotropic polarization effect of a pump-induced polarization-plane rotation for normal-incidence reflection from the (001) surface of a cubic crystal. In GaAs, azimuth rotation of the order of 9 × 10-6 rad is seen for a pump intensity of 75 MW/cm2 at 750 nm, from which the anisotropic component of the cubic nonlinearity |Re(χxxxx - 2χxxyy - χxyyx)| = 5 × 10-9 esu is found.<br/

Features of cadets’ adaptation universities Ukrainian Interior Ministry to study the art of sambo

Purpose : to study the problem of adaptation of students to the study of throwing techniques Sambo in the educational process of professional orientation. Material : the study involved 53 first-year cadet. Also 8 teachers - experts. Results : the initial study of the features of self-defense techniques without weapons in the universities of the Interior Ministry of Ukraine. The factors that impede the development of technical action: lack of preparedness of students on basic psychophysical parameters, the desire to avoid pain when you fall; big breaks between classes. Developed a set of special exercises aimed at improving the mental and physical qualities of the future police officers. Complex promotes adaptation to the study of self-defense techniques without weapons. An efficiency of specific exercises to improve motor skills formation and neutralization of negative factors. Conclusions : recommend the use in the educational process special physical training specific exercises. Exercises gradually become more complex in structure as close as possible to the difficult coordination in unarmed combat

Controlling Silver Nanoparticle Size and Morphology with Photostimulated Synthesis

Photo-induced synthesis and control over the size and shape of colloidal silver nanoparticles is investigated in contrast to photo-stimulated aggregation of small nanoparticles into large fractal-type structures. The feasibility of light-driven nanoengineering which enables manipulation of the sizes and shapes of the isolated nanoparticles is studied by varying the amount and type of the stabilizing agent and the type of optical irradiation.Comment: 10 pages, 7 figures, 11 image

Two-Dimensional Graphene Superlattice: Energy Spectrum and Current-Voltage Characteristics

The properties of two-dimensional graphene-based superlattice are studied. The creation of a twodimensional periodic potential in the graphene layer is assumed to be alternating in a checkerboard pattern of rectangular areas of the substrate materials. For this system the energy spectrum and an expression for the current in the graphene layer were obtained. The influence of a transverse constant electric field on the current is investigated. It is shown that the presence of the transverse field leads to the appearance of an additional peak in the current-voltage characteristics of the superlattice

Slow deterministic vector rogue waves

For an erbium-doped fiber laser mode-locked by carbon nanotubes, we demonstrate experimentally and theoretically a new type of the vector rogue waves emerging as a result of the chaotic evolution of the trajectories between two orthogonal states of polarization on the Poincare sphere. In terms of fluctuation induced phenomena, by tuning polarization controller for the pump wave and in-cavity polarization controller, we are able to control the Kramers time, i.e. the residence time of the trajectory in vicinity of each orthogonal state of polarization, and so can cause the rare events satisfying rogue wave criteria and having the form of transitions from the state with the long residence time to the state with a short residence time

2W/nm Peak-power All-Fiber Supercontinuum Source and its Application to the Characterization of Periodically Poled Nonlinear Crystals

We demonstrate a uniform high spectral brightness and peak power density all-fiber supercontinuum source. The source consists of a nanosecond Ytterbium fiber laser and an optimal length PCF producing a continuum with a peak power density of 2 W/nm and less than 5 dB of spectral variation between 590 to 1500 nm. The Watt level per nm peak power density enables the use of such sources for the characterization of nonlinear materials. Application of the source is demonstrated with the characterization of several periodically poled crystals.Comment: 8 pages 4 figures v2 includes revisions to the description of the continuum formatio

Analytical approximation of the stress-energy tensor of a quantized scalar field in static spherically symmetric spacetimes

Analytical approximations for ${}$ and ${}$ of a quantized scalar field in static spherically symmetric spacetimes are obtained. The field is assumed to be both massive and massless, with an arbitrary coupling $\xi$ to the scalar curvature, and in a zero temperature vacuum state. The expressions for ${}$ and ${}$ are divided into low- and high-frequency parts. The contributions of the high-frequency modes to these quantities are calculated for an arbitrary quantum state. As an example, the low-frequency contributions to ${}$ and ${}$ are calculated in asymptotically flat spacetimes in a quantum state corresponding to the Minkowski vacuum (Boulware quantum state). The limits of the applicability of these approximations are discussed.Comment: revtex4, 17 pages; v2: three references adde

Vacuum polarization of a scalar field in wormhole spacetimes

An analitical approximation of $$ for a scalar field in a static spherically symmetric wormhole spacetime is obtained. The scalar field is assumed to be both massive and massless, with an arbitrary coupling $\xi$ to the scalar curvature, and in a zero temperature vacuum state.Comment: 10 pages, RevTeX, two eps figure