Strongly anisotropic Dirac quasiparticles in irradiated graphene

We study quasiparticle dynamics in graphene exposed to a linearly-polarized electromagnetic wave of very large intensity. Low-energy transport in such system can be described by an effective time-independent Hamiltonian, characterized by multiple Dirac points in the first Brillouin zone. Around each Dirac point the spectrum is anisotropic: the velocity along the polarization of the radiation significantly exceeds the velocity in the perpendicular direction. Moreover, in some of the points the transverse velocity oscillates as a function of the radiation intensity. We find that the conductance of a graphene p-n junction in the regime of strong irradiation depends on the polarization as $G(\theta)\propto|\sin\theta|^{3/2}$, where $\theta$ is the angle between the polarization and the p-n interface, and oscillates as a function of the radiation intensity.Comment: 5 pages + 2 pages of Supplemental Material, 4 figure

Observation of hard radiations in a laboratory atmospheric high-voltage discharge

The new results concerning neutron emission detection from a laboratory high-voltage discharge in the air are presented. Data were obtained with a combination of plastic scintillation detectors and $^3$He filled counters of thermal neutrons. Strong dependence of the hard x-ray and neutron radiation appearance on the field strength near electrodes, which is determined by their form, was found. We have revealed a more sophisticated temporal structure of the neutron bursts observed during of electric discharge. This may indicate different mechanisms for generating penetrating radiation at the time formation and development of the atmospheric discharge.Comment: 10 pages, 10 figures, 2 table

Automated system for diagnosing craniocerebral injury

A Russian national computing and communication system designed to assist non-specialized physicians in the diagnosis and treatment of craniocerebral injury is described

Multifragmentation and nuclear phase transitions (liquid-fog and liquid-gas)

Thermal multifragmentation of hot nuclei is interpreted as the nuclear liquid-fog phase transition. The charge distributions of the intermediate mass fragments produced in p(3.6 GeV) + Au and p(8.1 GeV) + Au collisions are analyzed within the statistical multifragmentation model with the critical temperature for the nuclear liquid-gas phase transition Tc as a free parameter. The analysis presented here provides strong support for a value of Tc > 15 MeV.Comment: 4 pages, 2 figures, Submittet to Proc. of NN2003 to be published in Nucl. Phys.

Out-of-Equilibrium Admittance of Single Electron Box Under Strong Coulomb Blockade

We study admittance and energy dissipation in an out-of-equlibrium single electron box. The system consists of a small metallic island coupled to a massive reservoir via single tunneling junction. The potential of electrons in the island is controlled by an additional gate electrode. The energy dissipation is caused by an AC gate voltage. The case of a strong Coulomb blockade is considered. We focus on the regime when electron coherence can be neglected but quantum fluctuations of charge are strong due to Coulomb interaction. We obtain the admittance under the specified conditions. It turns out that the energy dissipation rate can be expressed via charge relaxation resistance and renormalized gate capacitance even out of equilibrium. We suggest the admittance as a tool for a measurement of the bosonic distribution corresponding collective excitations in the system

Blue laser cooling transitions in Tm I

We have studied possible candidates for laser cooling transitions in $^{169}$Tm in the spectral region 410 -- 420 nm. By means of saturation absorption spectroscopy we have measured the hyperfine structure and rates of two nearly closed cycling transitions from the ground state $4\textrm{f}^{13}6\textrm{s}^2(^2\textrm{F}_0)(J_g=7/2)$ to upper states $4\textrm{f}^{12}(^3\textrm{H}_5)5\textrm{d}_{3/2}6\textrm{s}^2(J_e=9/2)$ at 410.6 nm and $4\textrm{f}^{12}(^3\textrm{F}_4)5\textrm{d}_{5/2}6\textrm{s}^2(J_e=9/2)$ at 420.4 nm and evaluated the life times of the excited levels as 15.9(8) ns and 48(6) ns respectively. Decay rates from these levels to neighboring opposite-parity levels are evaluated by means of Hartree-Fock calculations. We conclude, that the strong transition at 410.6 nm has an optical leak rate of less then $2\cdot10^{-5}$ and can be used for efficient laser cooling of $^{169}$Tm from a thermal atomic beam. The hyperfine structure of two other even-parity levels which can be excited from the ground state at 409.5 nm and 418.9 nm is also measured by the same technique. In addition we give a calculated value of $7(2)$ s$^{-1}$ for the rate of magnetic-dipole transition at 1.14 $\mu$m between the fine structure levels $(J_g=7/2)\leftrightarrow(J'_g=5/2)$ of the ground state which can be considered as a candidate for applications in atomic clocks.Comment: 8 pages, 5 figure

Prediction of the Caspian Sea level using ECMWF seasonal forecasts and reanalysis

This article is made available through the Brunel Open Access Publishing Fund. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.The hydrological budget of the Caspian Sea (CS) is investigated using the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERAi) and seasonal forecast (FCST) data with the aim of predicting the Caspian Sea Level (CSL) some months ahead. Precipitation and evaporation are used. After precipitation events over the Volga River, the discharge (Volga River discharge (VRD)) follows with delays, which are parameterized. The components of the water budget from ERAi and FCSTs are integrated to obtain time series of the CSL. Observations of the CSL and the VRD are used for comparison and tuning. The quality of ERAi data is sufficiently good to calculate the time variability of the CSL with a satisfactory accuracy. Already the storage of water within the Volga Basin allows forecasts of the CSL a few months ahead, and using the FCSTs of precipitation improves the CSL forecasts. The evaporation in the seasonal forecasts is deficient due to unrealistic sea surface temperatures over the CS. Impacts of different water budget terms on the CSL variability are shown by a variety of validation tools. The importance of precipitation anomalies over the catchment of the Volga River is confirmed, but also impacts from the two southern rivers (Sefidrud and Kura River) and the evaporation over the CS become obvious for some periods. When pushing the FCSTs beyond the limits of the seasonal FCSTs to 1 year, considerable forecast skill can still be found. Validating only FCSTs by the present approach, which show the same trend as one based on a statistical method, significantly enhances the skill scores