Lifetime of nonequilibrium charge carriers in the base of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">n</Emphasis>-junction semiconductor diode at arbitrary injection levels

In the approximation of exponential distribution of nonequilibrium charge carriers in the base of semiconductor p-n-junction diode a formula is obtained for lifetime calculation, which is valid at arbitrary injection levels. The lifetime is determined via measurements of only stationary characteristics of diodes (dc-CVC and low-frequency differential resistance). These characteristics, as well as the dependence of the barrier capacity on the reverse voltage, for determination of equilibrium concentration of carriers in the diode base, have been measured for D226B alloy diodes. The dependence of the lifetime of nonequilibrium carriers on the injection level, calculated from experimental data, agrees with the Shockley-Read theory of recombination; this agreement may be considered as a justification of assumptions made for lifetime calculation.     

Temperature dependence of dark current-voltage characteristics of <Emphasis Type="Italic">n</Emphasis>InSb-<Emphasis Type="Italic">n</Emphasis>PbTe-<Emphasis Type="Italic">n</Emphasis>CdTe isotype structure

The temperature dependence of dark current-voltage characteristics of an nInSb-nPbTe-nCdTe structure is investigated. It is shown that in the temperature range from 115 K to 125 K an energy barrier exists for charge carriers through the InSb layer, which is strictly connected with different temperature dependences of electron concentrations in nInSb and nPbTe.     

Laser-beam-induced current in two-dimensional <Emphasis Type="Italic">n-p-n</Emphasis>-structures

Appearance of a transverse photocurrent at local excitation, by an optical beam, of the surface of n-p-n-structure realized on the basis of a two-dimensional electron gas is studied theoretically. It is shown that the magnitude and sign of the photocurrent depend on the coordinate of the center of light spot. Conditions of linearity of this dependence are found demonstrating the suitability of two-dimensional bipolar structures for use in position-sensitive detectors with high spatial resolution.     

Theoretical concepts of operation of a semiconductor detector based on a <Emphasis Type="Italic">p-n</Emphasis> junction

Collected charge originating in a semiconductor detector of the p⁺-n-n⁺ type as a result of interaction with a monoenergetic electron beam with energies in the range from 7 to 25 keV is calculated. Generation of electron-hole pairs (EHPs) is calculated using the Monte Carlo method. In the context of the diffusion-drift model, an analytic expression for the contribution of generated EHPs to the detected signal is derived. It is shown that the losses of charge to recombination in the course of transport significantly affect the shape of detected signal. The comparison of simulated energy spectra with experimentally measured spectra shows good agreement between theory and experiment. Thus, the basics of a theoretical approach that makes it possible to calculate the operational characteristics of semiconductor detectors are developed; as a result, the parameters of these detectors can be optimized in designing the practically important semiconductor proportional detectors to be used in analytical methods.     

Recent high-<Emphasis Type="Italic">p</Emphasis><Subscript><Emphasis Type="Italic">T</Emphasis></Subscript> results from STAR

We present selected recent results of multi-hadron correlation measurements in azimuth and pseudorapidity at intermediate and high p _T in Au+Au collisions at , from the STAR experiment at RHIC. At intermediate p _T , measurements are presented that attempt to determine the origin of the associated near-side (small Δφ) yield at large pseudo-rapidity difference Δη that is found to be present in heavy ion collisions. In addition, results are reported on new multi-hadron correlation measures at high-p _T that use di-hadron triggers and multi-hadron cluster triggers with the goal to constrain the underlying jet kinematics better than in the existing measurements of inclusive spectra and di-hadron correlations.     

Study of quark distribution amplitudes of 1<Emphasis Type="Italic">S</Emphasis> and 2<Emphasis Type="Italic">S</Emphasis> heavy quarkonium states

In this paper, the quark distribution amplitudes of 1S and 2S heavy quarkonium states are studied in terms of Gaussian-type wave functions. The transverse momenta p _⊥ integrals of the formulae for the decay constant are performed analytically. Then the quark distribution amplitudes are obtained. In addition, the ξ-moments are also calculated. After fixing the relevant parameters appearing in the quark distribution amplitude, the curves of the quark distribution amplitude for 1S and 2S heavy quarkonium states are plotted. Finally, the numerical results of this approach are compared with the other theoretical predictions.     

<Emphasis Type="Italic">f</Emphasis>(<Emphasis Type="Italic">R</Emphasis>) Cosmology from <Emphasis Type="Italic">q</Emphasis>-theory

From a macroscopic theory of the quantum vacuum in terms of conserved relativistic charges (generically denoted by q ^(a) with label a), we have obtained, in the low-energy limit, a particular type of f(R) model relevant to cosmology. The macroscopic quantum-vacuum theory allows us to distinguish between different phenomenological f(R) models on physical grounds. The text was submitted by the authors in English.     

Bianchi Type <Emphasis Type="Italic">VI</Emphasis><Subscript>0</Subscript> Magnetized Barotropic Bulk Viscous Fluid Massive String Universe in General Relativity

A model of a cloud formed by massive strings is studied in the context of the usual general relativity. This model is used as a source of Bianchi type VI ₀ massive with magnetic field and bulk viscosity. To get a determinate model, we assume that the expansion (θ) in the model is proportional to the shear (σ) and also the fluid obeys the barotropic equation of state. The behaviour of the models from physical and geometrical aspects in presence and absence of magnetic field and bulk viscosity is discussed.     

Femtosecond laser ablation of neurons in <Emphasis Type="Italic">C</Emphasis>. <Emphasis Type="Italic">elegans</Emphasis> for behavioral studies

In this paper, the interaction between the inhomogeneous and anisotropic cloak covered infinitely long PEC circular cylinder and the parallel electric-line-source is investigated in detail. First, the permittivity and permeability tensors of the cloak are defined according to Pendry’s model, then the wave equation in the metamaterial cloak is derived; second, the far/near properties of the model are investigated, and using the boundary conditions the electromagnetic fields of the whole region are calculated analytically; finally, based on the analytical expressions, the electric fields of the whole region are demonstrated through numerical results which show the effects of invisibility. Finally, the effects of loss on the performance of the invisible cloak are investigated.     

Local Resolvent Estimates for <Emphasis Type="Italic">N</Emphasis>-body Stark Hamiltonians

For an N-body Stark Hamiltonian , the resolvent estimate holds uniformly in with Re and Im , where , and is a compact interval. This estimate is well known as the limiting absorption principle. In this paper, we report that by introducing the localization in the configuration space, a refined resolvent estimate holds uniformly in with Re and Im . Dedicated to Professor Hideo Tamura on the occasion of his 60th birthday     

Energy distribution in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>) gravity

The well-known energy problem is discussed in f (R) theory of gravity. We use the generalized Landau–Lifshitz energy–momentum complex in the framework of metric f (R) gravity to evaluate the energy density of plane symmetric solutions for some general f (R) models. In particular, this quantity is found for some popular choices of f (R) models. The constant scalar curvature condition and the stability condition for these models are also discussed. Further, we investigate the energy distribution of cosmic string spacetime.     

Non-vacuum Bianchi types <Emphasis Type="Italic">I</Emphasis> and <Emphasis Type="Italic">V</Emphasis> in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>) gravity

In a recent paper (Sharif and Shamir in Class. Quantum Grav. 26:235020, 2009), we have studied the vacuum solutions of Bianchi types I and V spacetimes in the framework of metric f (R) gravity. Here we extend this work to perfect fluid solutions. For this purpose, we take stiff matter to find energy density and pressure of the universe. In particular, we find two exact solutions in each case which correspond to two models of the universe. The first solution gives a singular model while the second solution provides a non-singular model. The physical behavior of these models has been discussed using some physical quantities. Also, the function of the Ricci scalar is evaluated.     

<Emphasis Type="Italic">SL(2; R)</Emphasis> Duality of the Noncommutative DBI Lagrangian

We study the action of the SL(2; R) group on the noncommutative DBI Lagrangian. The symmetry conditions of this theory under the above group will be obtained. These conditions determine the extra U(1) gauge field. By introducing some consistent relations we observe that the noncommutative (or ordinary) DBI Lagrangian and its SL(2; R) dual theory are dual of each other. Therefore, we find some SL(2; R) invariant equations. In this case the noncommutativity parameter, its T -dual and its SL(2; R) dual versions are expressed in terms of each other. Furthermore, we show that on the effective variables, T -duality and SL(2; R) duality do not commute. We also study the effects of the SL(2; R) group on the noncommutative Chern–Simons action.     

Impurity photovoltaic effect in <Emphasis Type="Italic">p-i-n</Emphasis> structures of undoped GaAs

Photo-emf in the range hv = 0.76 ? 1.35 eV was found in p-i-n structures produced from undoped GaAs crystals with known parameters; the current sensitivities in the impurity and intrinsic (hv > 1.35 eV) regions were comparable. It was proven that the impurity photovoltaic effect results from EL2 and EL3 structural defects creating deep donor levels in the forbidden zone. Calculations were performed that justified the possibility of observing this effect on the investigated structures.     

Bacteriochlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> as a sensitizer for photodynamic therapy

A simple scheme of modification of the native pigment bacteriochlorophyll a, extracted from the biomass of phototropic bacteria, for the purpose of obtaining a water-soluble derivative — bacteriochlorin e ₆ — which is similar in molecular structure to the effective sensitizer chlorin e ₆ and, in addition, has an intense longwave absorption band in the near-infrared region of the spectrum where biological tissues weakly absorb light — has been developed. The ease of production of bacteriochlorin e ₆ in combination with its physicochemical and spectral properties allow it to be considered as a promising sensitizer for photodynamic therapy.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 745–748, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Ferromagnetism and ferroelectricity in Eu<Emphasis Type="Italic">X</Emphasis> (<Emphasis Type="Italic">X</Emphasis> = <Emphasis Type="Italic">O</Emphasis>, <Emphasis Type="Italic">S</Emphasis>): pressure effects

Ferromagnetism and ferroelectricity in Eu monochalcogenides have been investigated by ab initio density functional theory in the DFT+U approach. Exchange interaction parameters and Curie temperatures under pressure are studied and discussed using Heisenberg Hamiltonian with first and second-nearest-neighbor interactions. The calculations showed that the hydrostatic pressure perfectly improves the Curie temperature (EuO: T _C = 175 K; EuS: T _C = 33.8 K) and in the other hand it cannot induce the spontaneous polarization (P _s ). The effect of uniaxial and biaxial pressure is also studied. Although the uniaxial strains slightly increases the Curie temperature, it ensures the ferrolectricity in these systems by producing a spontaneous polarization of the order of P _s (EuO) = 57.50 μC/cm² and P _s (EuS) = 42.86 μC/cm² with pressures of 5% and 4%, respectively. The search for new model systems is a necessity to better understand the physics related to multiferroïc materials and to consider possible applications.     

Energy and system dependence of high-<Emphasis Type="Italic">p</Emphasis><Subscript><Emphasis Type="Italic">T</Emphasis></Subscript> triggered two-particle near-side correlations

Previous studies have indicated that the near-side peak of high-p _T triggered correlations can be decomposed into two parts, the Jet and the Ridge. We present data on the yield per trigger of the Jet and the Ridge from d+Au, Cu+Cu and Au+Au collisions at GeV and 200 GeV and compare data on the Jet to PYTHIA 8.1 simulations for p+p. PYTHIA describes the Jet component up to a scaling factor, meaning that PYTHIA can provide a better understanding of the Ridge by giving insight into the effects of the kinematic cuts. We present collision energy and system dependence of the Ridge yield, which should help distinguish models for the production mechanism of the Ridge.     

<Emphasis Type="Italic">q</Emphasis>-Analogue of Modified KP Hierarchy and its Quasi-Classical Limit

A string basis is constructed for each subalgebra of invariants of the function algebra on the quantum special linear group. By analyzing the string basis for a particular subalgebra of invariants, we obtain a “canonical basis” for every finite dimensional irreducible -module. It is also shown that the algebra of functions on any quantum homogeneous space is generated by quantum minors. Supported by the Australian Research Council and Chinese National Natural Science Foundation project number: 10471070