bluuebunny/crossref_metadata_2025 huggingface dataset:
Article
Authors: Wang J X , Ho Y K , Scheid W , Hora H
Published: April 2011

By calculation of the classical Newton-Lorentzequation and neglecting the radiation reaction, we find that when anelectron is scattered by an intense continuous monochromatic laser beam (Q equiv eE/(mcwc) > 0.1 in the interaction region), there can benot only momentum transfer but also noticeable energy transfer between thefree electrons and the laser beam. This kind of inelastic effect comes fromnonlinear Compton scattering.PACS Nos.: 42.50Vk and 42.50 Hz
Tutorial/Artical didactique: A high-accuracy mathematical and numerical method for Fourier transform, integral, derivatives, and polynomial splines of any order
Authors: Beaudoin N
Published: April 2011

From few simple and relatively well-known mathematical tools, an easily understandable, though powerful, method has been devised that gives many useful results about numerical functions. With mere Taylor expansions, Dirac delta functions and Fourier transform with its discrete counterpart, the DFT, we can obtain, from a digitized function, its integral between any limits, its Fourier transform without band limitations and its derivatives of any order. The same method intrinsically produces polynomial splines of any order and automatically generates the best possible end conditions. For a given digitized function, procedures to determine the optimum parameters of the method are presented. The way the method is structured makes it easy to estimate fairly accurately the error for any result obtained. Tests conducted on nontrivial numerical functions show that relative as well as absolute errors can be much smaller than 10-100, and there is no indication that even better results could not be obtained. The method works with real or complex functions as well; hence, it can be used for inverse Fourier transforms too. Implementing the method is an easy task, particularly if one uses symbolic mathematical software to establish the formulas. Once formulas are worked out, they can be efficiently implemented in a fast compiled program. The method is relatively fast; comparisons between computation time for fast Fourier transform and Fourier transform computed at different orders are presented. Accuracy increases exponentially while computation time increases quadratically with the order. So, as long as one can afford it, the trade-off is beneficial. As an example, for the fifth order, computation time is only ten times greater than that of the FFT while accuracy is 108 times better. Comparisons with other methods are presented.PACS Nos.: 02.00 and 02.60
Article
Authors: Musso M , Fuso F , Filippo G De , Allegrini M , Gruber D , Windholz L
Published: April 2011

Transfer of excitation from cadmium to sodium atoms was investigated in anheat pipe oven illuminated by a pulsed laser tuned on the intercombinationtransition of cadmium. A rich emission spectrum with cadmium as well assodium lines was observed. Intramultiplet mixing distributes the initialexcited level population 5p3P1 to the nearby fine structurelevels 5p3P0,2 of the same multiplet. We have experimentalevidence that the energy transfer pathway is from Cd (5p3PJ) to Na(4p2PJ) which is collisionally rapidly converted toNa(3d2DJ), from which the strongest emission was observed.PACS No.: 34.90+q
Self-consistent field theory of compressible phospholipid membranes at finite pressure
Authors: Whitmore M D , Whitehead J P
Published: April 2011

In this paper, we use the self-consistent field theory developed in thepreceding paper to study the effects of hydrostatic pressure on theliquid crystal phase of fully hydrated phospholipid membranes, and thecompeting effects of temperature and pressure. In agreement withexperiment, the theory predicts that, at constant temperature, thebilayer thickness and average orientational order parameter both increase withincreasing pressure. When both temperature and pressure are increasedsimultaneously so as to follow the liquid crystal/gel phase coexistencecurve, the thickness and average order parameter decrease, a resultwhich is also in agreement with experiment. We also examine anapproximate relationship between the thickness of the hydrophobicregion and the average orientational order parameter which has beenused to estimate layer thicknesses from NMR data. \\\\ PACS Nos.: 87.22.Bt, 87.10.+e, 64.60.Cn
Article
Authors: Attia H A
Published: April 2011

The unsteady flow and heat transfer of an electrically conducting, viscous, incompressible fluid bounded by two parallel nonconducting porous plates are studied taking the Hall effect into consideration. An external uniform magnetic field is applied normal to the plates, and the fluid motion is subjected to a constant pressure gradient and a uniform suction and injection. An analytical solution for the governing equations of motion is obtained and a numerical solution for the energy equation including the Joule and the viscous dissipation terms is developed. The effect of the Hall term on both the velocity and temperature distributions is examined.PACS No.: 47.70
Article
Authors: Gorgui M A , Faltas M S , Ahmed A Z
Published: April 2011

The wave motion generated in the presence of a porous cylindrical wall isinvestigated taking surface tension into consideration. The boundary value problems forthe velocity potentials are solved using Taylor's porosity assumption on the wall and acontact-line condition that accounts for the dynamic variation of the angle of contact andthe vorticity there. The radiated waves are obtained both when the wall surface executesradial and vertical harmonic oscillations and the re ection coefficient is calculated when aharmonic wave is incident normally on the wall surface. In all cases, the effect of surfacetension is discussed analytically and graphically.PACS No: 04.30
Article
Authors: Singh N L , Shah D J , Patel H B
Published: April 2011

The stacked-foil activation technique and HPGe gamma-ray spectroscopy were used for the investigation of alpha-particle-induced reactions on natural iron up to 50 MeV. Excitation functions for the production of reaction residues 57Ni, 56Ni, 58Co, 57Co, and 56Co from alpha-particle-induced reactions on 56Fe were measured with a view to improve the quality of earlier measurements. The experimental results were compared with calculations considering equilibrium as well as preequilibrium reactions according to hybrid model of Blann (ALICE/90). It was found that the initial exciton configuration n0= 4(2p + 2n + 0h ) i.e., pure particle state appears to give a good fit to the experimental data.PACS No.: 25.60
Article
Authors: Ma Y , Robinson A M , Lawson RPW , Allegretto W , Zhou T
Published: April 2011

In this paper we compare the performance of several magneticallyactuated CMOS-micromachined cantilever-in-cantilever structures. Wealso investigate the importance of thermal effects to the actuationand determine that these are significant only for static deflectionoperations; resonant frequencies show very little thermaldependence at the currents we employed, since largedeflections were observed. Qualitative analysis of device behaviouris given using simplified formulae, and a more precise simulation isobtained using a finite element software package (ANSYS). Theseresults are compared with experimental data.PACS No.: 75.80
Article
Authors: McKeon D.G.C.
Published: April 2011

Vortex solutions to the classical field equations in a massive,renormalizable U(1) gauge modelare considered in (2+1) dimensions. A vector field whose kineticterm consists of aChern-Simons term plus a Stuekelberg mass termis coupled to a scalar field. If the classical scalarfield is set equal to zero, then there are classical configurationsof the vector field in which themagnetic flux is nonvanishing and finite. In contrast to theNielsen-Olesen vortex, the magneticfield vanishes exponentially at large distances and divergeslogarithmically at short distances. Thisdivergence, although not so severe as to cause the flux to diverge,results in theHamiltonianbecoming infinite. If the classical scalar field is no longer equalto zero, then the magnetic fluxis not only finite, but quantized and the asymptotic behaviour of thefield is altered so that theHamiltonian no longer suffers from a divergence due to the fieldconfiguration at the origin.Furthermore, the asymptotic behaviour at infinity is dependent on themagnitude of theStuekelberg mass term.PACS No.: 11.15 Kc
Article
Authors: Singh W S , Singh S D , Bhattacharya M , Mazumdar P S
Published: April 2011

In the present paper a method is developed for the determination of the orders of kinetics and activation energies of thermoluminescence (TL) glow curves recorded in a hyperbolic heating scheme. The suitability of the present method is tested by applying it both to numerically computed and experimental TL peaks. PACS No.: 78.60kn
Article
Authors: Chen J , Chen Z , Shuai J , Lu Y , Guo D
Published: April 2011

A coupled chaotic lattice, based on a new chaotic unit, is analyzed numerically in this paper. A circuit of high-dimensional lattice can easily be designed because the structure of every dimension is the same. It can also be easily integrated without involving capacity and induction. The state parameters in the lattice occupy a wide dynamic range with values within reasonable power supply limits. Its circuit of chaotic unit is also discussed in detail. With the span of the parameters (variable resistors in the circuit), typical dynamic phenomena such as the stable point, period states, and the chaotic state are found on the oscilloscope. We also show a scheme of the lattice circuit.The lattice together with its circuit, which can show abundant chaotic and hyperchaotic behaviors, may have important application in communications. PACS Nos.: 05.45+b, 05.50+q, and 07.50Ek
What do we actually know about the proton radius?
Authors: Karshenboim S G
Published: April 2011

This paper considers the different determinations of the proton charge radius. It demonstrates that the results from the elastic electron-proton scattering have to be assigned a higher uncertainty. A review of the hydrogen Lamb-shift measurements and the radius determination from them is also presented.PACS No.: 27.10 and 35.10B
Transition probability between the hyperfine structure components of hydrogenlike ions and bound-electron g-factor
Authors: Shabaev V M
Published: April 2011

The transition probability between the hyperfine splittingcomponents of a hydrogenlike ion is expressed in terms of thebound-electron g-factor. It allows a simple calculationof the QED (quantum electrodynamic) and nuclear-size corrections to the transition probability by using thecorresponding corrections to the bound-electron g-factor.In experimentally interesting cases of Ho, Re, Pb, and Bithe QED corrections increase the transition probability by about 0.3%.Using a recent experimental value for the transition probabilitybetween the hyperfine structure components in 207Pb81+it is foundthat the bound-electron g-factor in lead amounts to 1.78(12).The corresponding theoretical value is 1.7383.\\\\PACS Nos.:12.20Ds, 31.30Gs, and 31.30Jv
Article
Authors: Grigorescu M
Published: April 2011

The quantum dynamics of a Xe atom placed on the STM surfaceis studied considering two important types of nonstationary externalforces. These are the driving forces appearing during the application of avoltage pulse, and the fluctuating forces determined by the coupling to anOhmic environment. The localization probability on the tipduring voltage pulses of 20 and 7 ns with symmetric triangular andtrapezoidal shapes is calculated neglecting the environmental interactions.The results indicate that the atom dynamics in this case is reversible, andafter the pulse the transfer probability is small.The effects of the fluctuating forces produced by the coupling to thesurrounding electrons and surface phonons are studied in a static potential.It is shown that the thermal fluctuations at the environmental temperaturecan lead to irreversible atom tunneling through the potential barrier,described by an exponential decay law.PACS Nos.: 61.16.Di, 73.40.Gk, 05.40.+j
Joule-heating effects on unsteady natural convection from a heatedvertical plate in a micropolar fluid
Authors: Mansour M A , Gorla RSR
Published: April 2011

A boundary-layer solution is presented to study the effects of viscous and Joule heating on unsteady natural convection flow in a micropolar fluid. Viscous dissipation has been retained as a first-order term. Numerical results for the unsteady boundary-layer equations have been obtained at any point along the vertical plate using the finite-difference method. Details of the velocity, microrotation, and temperature fields are presented for various material parameters.PACS Nos.: 44.25+F, 47.27-i, and 47.27Te
Precision measurement of parity nonconservation in cesium
Authors: Wood C S , Bennett S C , Roberts J L , Cho D , Wieman C E
Published: April 2011

The measurement of parity nonconservation (PNC) in atomic cesium is discussed in detail. With a spin-polarized atomic beam, this experiment achieves a fractional uncertainty of 0.35% in the measurement of the PNC amplitude for the transition between the 6S and 7S states of cesium, the lowest uncertainty of atomic PNC to date. By comparing the PNC amplitude on two hyperfine transitions, we measure for the first time the nuclear-spin-dependent contribution that arises from the nuclear anapole moment. A major portion of this paper describes the characterization and elimination of systematic errors.PACS Nos.: 32.80.Ys, 11.30.Er, 12.15.Ji, 32.10.Dk
Numerical simulation of the excitation and evolution of coherent vortices in hollow magnetized electron columns
Authors: Shoucri M , Marchand R
Published: April 2011

We apply a finite-element code to study the excitation and nonlinear evolution of two-dimensional (2D) vortices in a hollow electron column using 2D guiding center equations. The perturbation (with m = 2) of the hollow column results in an instability (diocotron or Kelvin-Helmholtz instability) that evolves towards the formation of vortices (two vortices for the m = 2 perturbation). The subsequent evolution shows the nonlinear evolution of two vortices interacting to coalesce (cascading to lower azimuthal mode number), with a simultaneous radial transport toward the center of the column. PACS Nos.: 52.25.Wz, 52.65.Kj, 47.32.-y, 02.70.Dh
Surface light-induced drift due to anisotropic gas-surface scattering in models with and without boundary conditions
Authors: Vaksman M A , Dahl J L
Published: April 2011

Surface light-induced drift (SLID), which occurs under velocity-selective excitation due to the state-dependence of the probability of trapping or chemisorption, has demonstrated its extreme sensitivity in studying the state-specificity of gas-surface interactions. Contrary to an intuitive perception, SLID can be also used to obtain the information on the angular dependence of the gas-surface scattering. In this paper we describe this effect qualitatively and then analyze it in two different models, with and without boundary conditions. We also discuss the implications of the results for studying the scaling laws of the angular dependence of surface scattering by the SLID technique. PACS No. 34.50.Rk
The effect of carrier capture and escape on the optical gain of quantum-well semiconductor lasers
Authors: Wartak M S , Kucharczyk M , Makino T
Published: April 2011

Effects of the carrier capture and escape on the optical gain of a quantum-well system are introduced and analyzed. The analysis is based on the density matrix time evolution equation solved in the linear approximation. It has been found that the capture and escape effects modify the broadening function and, as a consequence, reduce the optical and differential gain. The temperature dependence of the gain peak resulting from the inclusion of carrier capture/escape processes has been found.PACS Nos.: 42.55.P, 78.66
Fractal analysis methods to characterize porous solids using nitrogen adsorption data
Authors: Sahouli B , Blacher S , Brouers F , Chahed L
Published: April 2011

The use of the fractal concept to characterize the morphological nature of complex materials, such as porous solids, is considered. The most popular approaches, which are based on analysis of the shape of the adsorption isotherms of a substance vapor (in this case nitrogen at 77 K), are outlined and applied to characterizing a series of commercial carbon blacks. The most recent developments in this domain are given. The results obtained show that some methods, although derived using different arguments, are equivalent in some conditions, and the concept of a standard isotherm can be used in the fractal approach PACS Nos.: 61.43 H Fractals -68.45 -v
Whole-atom differential incoherent-scattering cross sections at 279.2 keV
Authors: Janardhan S , Ravinder S , Murthy Ch. Radhakrishna , Rao G Krishna , Rao AS Nageswara
Published: April 2011

The incoherent-scattering cross sections are determined at 279.2 keV γ-ray energy in the angular range 30° - 105° in Ni, Zn, Ag, Cd, In, Sn, and Pb. The measurements were carried out using an NaI (Tl) detector coupled to a single channel analyser. The scattering functions so determined experimentally have been compared with values evaluated on the basis of non relativistic SCF Hartree-Fock wave function. A reasonable agreement is observed between the theory and experiment within the limit of experimental errors. PACS Nos.: 52.25Nr and 32.80-t
Transition energies and transition rates for the 2p4(3P)3p - 2p4(3P)3d transitions in Ne II
Authors: Fischer C Froese , He Xinghong
Published: April 2011

Theoretical transition rates for 2p4(3P)3p - 2p4(3P)3d transitions in Ne II are reported from multiconfiguration Hartree-Fock calculations with Breit-Pauli corrections and multiconfiguration Dirac-Fock calculations with Breit corrections. Because the even parity states have many close-lying energy levels, interaction between terms is strong in some cases. An analysis of the data is presented.PACS Nos.: 31.25Jf, 32.30Jc, 32.70Cs
Exchange of nonclassical properties between two interacting modes of light and mutual conversion of the Fock and coherent states
Authors: Fu J , Gao X -C , Xu J -B , Zou X -B
Published: April 2011

The invariant-related unitary transformation method is used to study the exchange of nonclassical properties between two interacting modes of light. With the aid of numerical computation, it is of interest to find that the mutual conversion of the Fock state and the coherent state is attained when the interaction is chosen appropriately.PACS Nos.: 03.65.Ge, 42.50.Ar
A many-body projection approach to quantum-limit magneto-optical transition of two-dimensional electrons confined in a parabolic well
Authors: Kang N L , Ryu J Y , Choi S D
Published: April 2011

We apply the theory of magneto-optical transitions, introduced earlier by utilizing a many-body projection technique, on a system of electrons scattered by piezoelectric phonons in GaAs; the temperature dependence of the cyclotron resonance linewidth is investigated. It is shown that the width in the quantum limit increases with the temperature.PACS Nos.: 70.00--79.90
On the solution of general thermo-magnetohydrodynamic elasticoviscous flow
Authors: Helmy K A
Published: April 2011

Exact solutions of an oscillatory flow of an incompressible elasticoviscous conducting fluid with variable suction, in the presence of a constant magnetic field, applied perpendicular to the moving porous plate has been obtained. For small values of the elastic parameter k, the approximate solution of the problem has also been obtained.The temperature distribution is evaluated by solving the energy equation, taking into account the effect of the relaxation time. The effects of different physical parameters such as elastic parameter k, Prandtl number Pr, suction parameterA, magnetic parameter M, and the relaxation time τ on the velocity and temperature are discussed. Different values of physical parameters are tabulated and discussed numerically and graphically. PACS Nos.: 47.50, 47.65, 68.10.E
A photon number density operator in the covariant formulation of quantum electrodynamics
Authors: Melde T
Published: April 2011

We introduce a new photon number density operator in the Gupta-Bleuler quantized photon field and show that the corresponding total number operator counts transverse photons in the new model. It is also shown that the suggested operator interpreted in the usual Hilbert space counts, in addition, a number of gauge photons for the free field. In the case of two fixed charges it also counts an extra number of scalar photons due the charges.PACS Nos.: 12.20.-m, 14.70.Pw, 42.50.Ar
Synthesis and spectroscopic studies of Tm3+-doped KY3F10 single crystals
Authors: Diaf M , Braud A , Labbé C , Doualan J L , Girard S , Margerie J , Moncorgé R , Thuau M
Published: April 2011

We examine the laser possibilities offered by Tm3+-doped KY3F10. After crystal growth and X-ray diffraction analysis, the optical properties of thulium ions in KY3F10 are determined for the first time. Absorption and emission spectra recorded at low temperatures are used to obtain a set of Stark sublevels, whereas the room-temperature absorption spectra have been allowed to fit the three phenomenological Judd-Ofelt (JO) parameters. The emission line strengths, branching ratios, and radiative lifetimes of levels from 3F4 up to 1D2 are then deduced. A comparison between the calculated lifetimes and the measured luminescence decay curves permits us to check the reliability of the JO analysis for this system. The potential of Tm:KY3F10 for laser emission from 3H4 or 3F4 emitting levels is briefly examined.PACS Nos.: 42.55.Rz, 78.50.Ec, 78.47.+p, 81.10.Fq.
Study of the elastic properties of sprayed SnO2 and SnS2 layers
Authors: Mnari M , Cros B , Amlouk M , Belgacem S , Barjon D
Published: April 2011

SnO2 and SnS2 thin films have been prepared by the spray pyrolysis technique for photovoltaic application purposes and characterized by high-frequency acoustic microscopy (570 MHz).The surface acoustic images reveal contrasts explained by differences in topography according to atomic force microscopy studies. The acoustic signature V(z) of the systemslayer/substrate were modelled and refined to fit with the experimental V(z). The acoustic parameters of the layers were calculated using the results of the final simulation. The values of Young's modulus deduced from the acoustic parameters, 401 and 56 GPa for SnO2 and SnS2, respectively, are discussed in relation with the chemical structure and bonding involved. PACS Nos.: 43.35Ns and 62.65
Effects of the Shafranov shift on the ballooning mode in negative shear
Authors: Elia M , Hirose A
Published: April 2011

In negative shear tokamak discharges, an excessively large Shafranov shift (Δ') destabilizes the magnetohydrodynamic ballooning mode. A kinetic model, local to a flux surface and which employs the ballooning-mode representation of the gyrokinetic equations, also predicts the existence of the instability as does two-fluid theory.PACS Nos.: 52.35.Fp, 52.35.Kt, 52.55.Fa
Interférométrie et réflectométrie haute résolution en lumière incohérente : modélisation d'interférogrammes
Authors: Lupi C , Tanguy E , Boisrobert C , Fornel F de
Published: April 2011

We report on low-coherence, near-infrared reflectometry applied to optical fibres, waveguides, and coupling devices to detect the echoes due to reflective propagation defects and measure their optical properties  losses or attenuation, dispersion. This technique, based on interferometry, leads to the highest spatial resolution and the lowest detectable reflected optical power. We scan the reference arm of our Michelson interferometer around the ``white light fringe'' position and obtain interferograms whose envelopes and fringes contain information on the light source spectrum and the reflectivity of the test arm. Theoretical and experimental results are compared. Examples are given and show that numerical simulations are needed to understand the signatures of the reflectors and get to their physical structures.
Chemical bath process for highly efficient Cd-free chalcopyrite thin-film-based solar cells
Authors: Ennaoui A
Published: April 2011

The highest efficiency for Cu(Ga,In)Se2 (CIGS) thin-film-based solar cells has been achieved with CdS buffer layers prepared by a solution growth method known as the chemical bath deposition (CBD). With the aim of developing Cd-free chalcopyrite-based thin-film solar cells, we describe the basic concepts involved in the CBD technique. The recipes developed in our laboratory for the heterogeneous deposition of good-quality thin films of ZnO, ZnSe, and MnS are presented. In view of device optimization, the initial formation of chemical-bath-deposited ZnSe thin films on Cu(Ga,In)(S,Se)2 (CIGSS) and the subsequent development of the ZnSe/CIGSS heterojunctions were investigated by X-ray photoelectron spectroscopy (XPS). The good surface coverage was controlled by measuring changes in the valence-band electronic structure as well as changes in the In4d, Zn3d core lines. From these measurements, the growth rate was found to be around 3.6 nm/min. The valence band and the conduction band-offsets ΔEV and ΔEC between the layers were determined to be 0.60 and 1.27 eV, respectively for the CIGSS/ZnSe interface. The energy-band diagram is discussed in connection with the band-offsets detemined from XPS data. A ZnSe thickness below 10 nm has been found to be optimum for achieving a homogeneous and compact buffer layer on CIGSS with a total area efficiency of 13.7%.PACS No.: 42.70
Interface tissus vivants-matériaux inertes
Authors: Karray F , Fakhfakh Z , Kallel A , Turki R
Published: April 2011

Stainless steels have numerous applications in many domains. More specifically, they are one of the main materials used in orthopedic surgery. Because they are implanted in the human body, they must be nontoxic, reliable, as safe as possible, and perform well. Under certain circonstances, they loose some of their mechanical properties. This may translate into sudden breaks, possibly with important medical complications. The present work studies how the living organism affects the implant: static constraints, wear and tear, and corrosion. We use scanning electronic microscopy with an X probe. Our purpose is to determine the criteria of durability and to explain how a weakness develops after implantation. An external morphologic examination helps determine the area selected for the study. We are specially interested in the state of the surface of the material and, generally, by the angular points and the regions with curvature variations where strains tend to concentrate.[Journal translation]
Helicon waves in a cylindrical plasma
Authors: Shoucri M
Published: April 2011

The dispersion relation for helicon waves in a uniform bounded plasma is derived by including the finite electron mass. The eigenmodes are identified and the coupling mechanism between the Ez and Bz modes is discussed. This is important since an essential part of the physics associated with the application of helicon waves for the generation and heating of plasmas consists in coupling the whistler branch with the Ez mode, which can interact directly with the electrons.PACS No.: 52.35-g
Diffusion du carbone lors de la décomposition de l'austénite en ferrite et en graphite dans une fonte à graphite sphéroïdal
Authors: Hellal F , Lacaze J , Hazotte A
Published: April 2011

The isothermal decomposition of austenite to ferrite and graphite in a spheroidal graphite cast iron was investigated by dilatometry, metallography and image analysis. The results gave quantitative, although indirect, information on the kinetics of carbon transfer from austenite to graphite, as well as on the kinetics of the austenite to ferrite and graphite transformation. The relations between these kinetics and the graphite nodule count was highlighted. The incubation period before ferrite growth was found to be associated with a global contraction of the material, in spite of the related increase of the graphite volume fraction. Calculations showed good agreement with experimental results, except for the rate of carbon transfer, which was found to be much slower experimentally than predicted by calculations based on the volume diffusion of carbon. Possible reasons for this discrepancy are discussed.
Some remarks on time, uncertainty, and spin
Authors: Carroll R
Published: April 2011

Some observations are made about energy-time, uncertainty, and spin in the context of trajectories as in Faraggi-Matone or Floyd. PACS Nos. 03.65Bz and 04.20Fg
Lattice parameters and optical absorption of CuIn1-xGaxSe2 thin films
Authors: Al-Bassam AAI
Published: April 2011

Thin film polycrystalline solar cells based on CuIn1xGaxSe2 have been fabricated and studied with x values from 0 to 1.0. The lattice parameters, grain size, and band gap were measured. Crystal structure and X-ray data of CuIn1xGaxSe2 were determined using X-ray diffractometry. These materials had a cubic structure with x ≥ 0.5 and a tetragonal structure with x ≤ 0.5. The lattice constants vary linearly with composition. Grain size was measured using X-ray diffraction where the grain size increased linearly with Ga content. A grain size of 1.83-3.52 μm was observed with x ≤ 0.5, while it increased to 4.53 μm for x = 0.58.PACS No.: 70.73
Density-density correlations in a Luttinger liquid: Lattice approximation in the Calogero-Sutherland model
Authors: Sen D , Bhaduri R K
Published: April 2011

For a one-dimensional model in which the two-body interactions are long-range and strong, the system almost crystallizes. The harmonic modes of such a lattice were used by Krivnov and Ovchinnikov to compute the ground-state wave function and the dynamical density-density correlations. We review this method, and apply it to the Calogero-Sutherland model, whose density-density correlation functions are exactly known for certain values of the coupling constant. We show numerically that the correlations obtained are quite accurate even if the coupling is not very large. Such comparisons have been made earlier by Forrester. The lattice method is considerably simpler than the ones used to derive the exact results, and yields expressions for the correlations- which are easily plotted. The equal-time correlations can be expanded in inverse powers of coupling; we show that the two leading order terms agree with the exact results which are known for integer values of the coupling. The strength-dependent power law fall-off is typical of a Luttinger liquid.In a general one-dimensional model where the two-body interaction decreases as a power of the relative distance, we argue, following Schulz, that at zero temperature the system behaves as a Luttinger liquid if the power exceeds 1, and as a Wigner crystal if it is less than 1.PACS Nos.: 63.20-e, 71.10Pm
Soliton transmission under pulse position modulation in optical fibres
Authors: da Silva J I , Holz R , Sombra ASB
Published: April 2011

A new optical pulse train configuration that may propagate with high stability, in normal and anomalous dispersion regimes,in optical fibres is proposed and simulated using pulse position modulation (PPM) coding. The high stability is achieved by simultaneous propagation of two infinite and periodic trains of bright pulses in normal and anomalous dispersion regimes (solitons) in a single-mode optical fibre. This configuration could lead to transmission velocities around 300 Gb/s with good stability under PPM coding. PACS No.: 78.00
Spinning strings of the Neveu-Schwarz-Ramond type in 3, 4, 6, and 10 space-time dimensions
Authors: Phillips S B
Published: April 2011

A model of a spinning string with an internal coordinate index is proposed and studied. When the action for this model is taken to be diagonal in this internal coordinate space and quantized in the light-cone gauge it is found to be Lorentz covariant in four-dimensional space-time provided that the internal coordinate space is four dimensional.This combination of space-time dimension, D, and internal coordinate space dimension, N, is just one of four possible sets, the other three corresponding to D = 3, 6, and 10, precisely the same values for which it is possible to formulate Yang-Mills theories with simple supersymmetry. By comparing the number of propagating degrees of freedom at the zero-mass level in the open string bosonic and fermionic sectors it is found that a supersymmetric interpretation of this model is possible provided that all physical states in the bosonic sector have even G-parity and the ground-state spin or in the fermionic sector have positive chirality. A possible interpretation of the connection betweenthe N components of each of the D space-time coordinates is presentedon the basis that the space-time coordinates are scalars in the internal coordinate space. This interpretation would appear to be reasonable given the fact that the field variables in the Lagrangian density do not necessarily have to represent physically measurable quantities but can, instead, only represent physically measurable quantities when combined in some manner, the simplest of which being a linear combination. The Lagrangian density simply produces the equations of motion and the constraint equations for the independent variables, only linear combinations of which represent the four dimensions of physical space-time.PACS Nos.: 11.17.+y, 11.10.Qr, 1.30.Cp, 11.30.Pb
Profile of a rotating string
Authors: Mohazzabi P , Schmidt J R
Published: April 2011

The problem of a uniform flexible chain or string rotating about an axis with fixed ends is addressed in the context of both Newtonian mechanics and the variational principle. It is shown that, in the absence of gravity, the equations describing the profile of the string as well as the constraints of the system are all expressible in terms of Legendre's elliptic integrals of various kinds. The effectof gravity is discussed qualitatively, and it is shown that for high enough angularvelocities its effect is negligible. The profile of a rotating chain is obtained using stroboscopic photography and compared with the theoretical results. PACS No.: 46.00
A thermodynamic lattice gas model of Poiseuille flow
Authors: Yang D , Udey N , Spanos TJT
Published: April 2011

Plane Poiseuille flow is simulated using a thermodynamic automaton model. This well-understood problem is used to demonstrate theconsistency of the physical predictions obtained from this new lattice gas model with established physical theory. The model presented is a nonrelativistic version of a model constructed by other researchers in which the collision and propagation rules could be used to derive the relativistic Boltzmann equation. The present model has great potential for describing hydrodynamic processes since it does not suffer from many of the limitations of models that rely on differential equations. For example, it can be used to model highly nonlinear processes or flow past complicated boundaries as easily as it can be used for the Poiseuille flow problems presented here. In the present paper, the physical foundations for using this model to study hydrodynamic processes are demonstratedby showing the Boltzmann nature of the gas, the construction of thermodynamic boundary conditions and consistency with physical theory when the temperature dependence of viscosity is modeled. The principal objective of this paper is to establish the physical validity of this model by comparison with well-established theoretical results from equilibrium thermodynamics. PACS No.: 05.10
Canonical transformations and the Hamilton-Jacobi theory in quantum mechanics
Authors: Kim J -H , Lee H -W
Published: April 2011

Canonical transformations using the idea of quantum generating functions are applied to construct a quantum Hamilton-Jacobi theory, based on the analogy with the classical case. An operator and a c-number form of the time-dependent quantum Hamilton-Jacobi equation are derived and used to find dynamical solutions of quantum problems. The phase-space picture of quantum mechanics is discussed in connection with the present theory.PACS Nos.: 03.65-w, 03.65Ca, 03.65Ge
Cherenkov-like shock waves associated with surpassing the light velocity barrier
Authors: Afanasiev G N , Kartavenko V G
Published: April 2011

The effects arising from the accelerated and decelerated motion of a point charge inside a medium are studied. The motion is manifestly relativistic and may be produced by a constant uniform electric field. It is shown that in addition to the bremsstrahlung and Cherenkov shockwaves, the electromagnetic shock wave arises when the charged-particle velocity coincides with the light velocity in the medium. For the accelerated motion, this shock wave, forming an indivisible entity with the Cherenkov shock wave, arrives after the arrival of the bremsstrahlung shock wave. For the decelerated motion the above shock wave detaches from the charge at the moment when its velocity coincides with the light velocity in the medium. This wave, existing even aftertermination of the charge motion, propagates with the velocity of light in the medium. It has the same singularity as the Cherenkov shock wave andis more singular than the bremsstrahlung shock wave.The space-time regions, where these shock waves exist, and conditions under which they can be observed are determined.PACS No.: 41.60
On the Cherenkov radiation from extended charge distributions
Authors: Villavicencio M , Jiménez J L , Roa-Neri JAE
Published: April 2011

In this work the Cherenkov effect for extended charge distributions is analyzed using two different methods. In the first method, the Poynting vector is employed to determine the energy radiated, whereas in the second one, we apply the idea of generating time-dependent elemental dipoles, induced by a charge distribution moving with constant velocity, inside a material medium. An explicit expression for the Cherenkov radiation generated by some different kinds of spherically symmetric charge, travelling inside a medium, is obtained.PACS Nos.: 03.50.De, 41.20.Bt, 41.60.-m, 41.60.Bq
On the relationship between anharmonic oscillators and perturbed Coulomb potentials in N dimensions
Authors: Morales D A , Parra-Mejías Z
Published: April 2011

The relation between the perturbed Coulomb problem in N dimensionsand the sextic anharmonic oscillator in N' dimensionsis presented and generalized in this work.We show that by performing a transformation, containing a free parameter, on the equations for the two problems we can relate the two systems in dimensions that have not been previously linked. Exact solutions can be obtained for the N-dimensional systems from knownthree-dimensional solutions of the two problems. Using the known ground-state wave functions for these systems, we construct supersymmetric partner potentials that allow us to apply the supersymmetric large-Nexpansion to obtain accurate approximate energy eigenvalues.PACS Nos.: 03.65.Ge, 03.65.Fd, 11.30.Na
Classical Yang-Mills equations invariant under subgroups of the conformal group without coupling to matter
Authors: Bracken P
Published: April 2011

Classical Yang-Mills field equations on Minkowski space with gaugegroup SU(2) are determined. Solutions invariant up to a gauge transformation under a four-dimensional subgroup of the conformal group are evaluated for the Yang-Mills field in the absence of matter. Some properties of the solutions of the equations such as their asymptotic behaviour are obtained.PACS No.: 03.50-z
Positron impact ionization of krypton and xenon
Authors: Campeanu R I , McEachran R P , Stauffer A D
Published: April 2011

Several distorted-wave models for positron ionization of krypton and xenon are investigated. Our previous CPE (Coulomb plus Plane waves -- full Energy range) model produces reliable cross sections for krypton. For xenon, at high positron energies, the CPE results fall below experiment. We have proposed an alternate model DCPE4 that works well for both krypton and xenon. A common feature of both of these models is that the free electron and positron are treated differently.PACS No.: 34.90.+q
Materials preparation by ball milling
Authors: Dunlap R A , Small D A , MacKay G R , O'Brien J W , Dahn J R , Cheng Z H
Published: April 2011

Ball milling is an important method for the preparation of materials both for the investigation of fundamental physical properties and for a number of possible commercial applications. In the present report, the basic principles of ball milling are discussed. This includes a brief overview of experimental techniques as well as an introduction to modeling methods used to analyze milling processes. This will be followed with a discussion of some of the experiments involving ball milling that are being conducted at Dalhousie University. Specifically, a summary of results on mechanically alloyed Fe-Al and experimental studies of the formation of metal hydrides by ball milling will be presented.PACS No.: 81.20Ev
On plasma diffusion in strong turbulence
Authors: Hirose A , Ishihara O
Published: April 2011

It is shown that the velocity diffusivity of electrons in strong Langmuir turbulence is linearly proportional to the root-mean-square (rms) value of the electric field. The time-dependent diffusivity previously identified is a transient phenomenon. In 2-D spatial diffusion due to ExB velocity turbulence, time-dependent intermediate diffusivity emerges also followed by a well-behaved diffusivity proportional to the rms amplitude of the turbulent field.PACS Nos.: 52.25Fi, 52.35Ra, 52.65Cc
Comment on: Curling rock dynamics - The motion of a curling rock: inertial vs. noninertial reference frames
Authors: Shegelski MRA , Reid M
Published: April 2011

We examine the approach used and the results presented in a recent publication(Can. J. Phys. 76, 295 (1998))in which (i) a noninertial reference frame is used to examine the motion ofa curling rock, and (ii) the lateral motion of a curling rock isattributed to left-right asymmetry in the force acting on the rock.We point out the important differences between describing the motionin an inertial frame as opposed to a noninertial frame.We show that a force exhibiting left-right asymmetryin an inertial frame cannot explain the lateral motion of a curlingrock. We also examine, as was apparently done in the recent publication,an effective force that has left-right asymmetry in a noninertial, rotating frame. We show that such a force is not left-right asymmetric in an inertial frame, and that anylateral motion of a curling rock attributed to the effective forcein the noninertial frame is actually due to a real force, in aninertial frame, which has a net nonzero component transverse to the velocityof the center of mass. We inquire as to the physical basis for thetransverse component of this real force. We also examine the motion ofa rotating cylinder sliding over a smooth surface for which there isno melting: we show that the motion is easily analyzed in an inertialframe and that there is little to be gained by considering a rotating frame.We relate the results for this simple case to the more involved problemof the motion of a curling rock: we find that the motion of curling rocksis best studied in inertial frames. Perhaps most importantly, we showthat the approach taken and the results presented in the recent publicationlead to predicted motions of curling rocks that are indisagreement with observed motions of real curling rocks.PACS Nos.: 46.00, 01.80+b
Reply to comment on: Curling rock dynamics - The motion of a curling rock: inertial vs. noninertial reference frames
Authors: Denny M
Published: April 2011

In their comment, Shegelski and Reid (SR) question the validity ofthe approach adopted in my paper to calculate the motion ofa curling rock. Predictions of the motion of a curling rockfall into two categories: those that depend upon frictionalasymmetry and those that do not. Predictions in the firstcategory are discussed here and shown to contradict the resultsof SR. Predictions in the second category are shown to be notapplicable to the game of curling.PACS Nos.: 46.00, 01.80+b
Shell-model tests of the bimodal partial state densities in a 2 × 2 partitioned embedded random matrix ensemble
Authors: Kota VKB , Majumdar D , Haq R , Leclair R J
Published: April 2011

The mixing of well-separated subspacesof an interacting many-particle system,such as a nucleus with active nucleons distributed in more than one major shell,can be studied usingpartitioned embedded ensembles of random matrices. The bimodalform of partial state densities (one-point functions) predictedearlier for a 2 × 2 partitioned embedded ensemble, whichmay be regarded as a model for the mixing of two well-separated degeneratesubspaces, is tested using nuclear shell-model calculations in the[(ds)6 ⊕ (ds)4 (f7/2)2]J=0,T=0 space. Thetheoretical forms predicted by the binary correlationapproximation theory are in good agreement with the shell-modelresults. This suggests that with suitable extensions it might be feasibleto use the binary correlation method to deal with severalinteracting subspaces involving multimodal distributions.PACS Nos.: 05.30.-d, 05.45.Mt, 24.60.Lz
Tutorial / Article didactique Derivatives of curvilinear coordinate unit vectors: A concise matrix-vector approach
Authors: Mohazzabi P
Published: April 2011

The time evolution of a curvilinear coordinate system can be identifiedwith an angular velocity matrix or vector, which contains the complete differentiationrule for all unit coordinate vectors of the curvilinear system, providinga concise method for their computations. When generalized the technique provides a powerful tool fordifferentiation, with respect to any parameter, of not only unit coordinate vectors but any vector that remains fixed in a general orthogonal curvilinear coordinate system. Several curvilinear systems, as well as the normal and tangentialcoordinate system are examined.PACS No.: 46.00
Atomic interface structure-property investigations
Authors: Kavanagh K L
Published: April 2011

Our current understanding of the relationship between interfacialstructure and the resulting properties remains very rudimentary.This is a concern for many fields and applications, includingmetal/semiconductor contacts, insulator/semiconductor field effectjunctions, magnetic multilayers, ferroelectric thin films, andsemiconductor heterostructures. The situation is slightly improvedin the case of epitaxial growth where a deposited layer followsthe structure of the underlying substrate. However, even withthese systems the interfacial properties are difficult to predictaccurately, even when impurities and defects can be ignored. Thispaper highlights a number of recent examples of interfacestructure-property investigations that have attempted tounderstand how the interface formation determines the relevantfilm or interface property.

PACS Nos.: 68.55.Jk, 68.55.Ln, 68.65.+g
Inactivation of phytotoxin produced by the rice sheath blight pathogenRhizoctonia solani
Authors: Sriram S , Raguchander T , Babu S , Nandakumar R , Shanmugam V , Vidhyasekaran P , Balasubramanian P , Samiyappan. R
Published: April 2011

The rice sheath blight pathogen, Rhizoctonia solani, produces a toxin designated as RS-toxin, a carbohydrate compound containing mainly alpha-glucose and mannose. Different microflora were tested for RS-toxin inactivation. Isolates of Trichoderma viride inactivated this toxin when it was provided as the sole food source, and these isolates reduced the severity of toxin-induced symptoms and electrolyte leakage from rice cells. The best-performing isolate, TvMNT7, produced two extracellular proteins of 110 and 17 kDa. The high molecular mass protein was shown to have alpha-glucosidase activity. The purified 110 kDa protein was able to reduce RS-toxin activity.Key words: rice sheath blight disease, Rhizoctonia solani, RS-toxin, toxin inactivation, Trichoderma viride.