bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phonon Focusing in LiNbO3 Crystals in an Electric Field
Authors: Zubritskii V. V. 
Published: July 2007

AbstractFor the first time in the 0 to 107 V/cm range of electric field (E), taking into account the nonlinear piezoeffect in trigonal lithium niobate, the directions and coefficients of concentration of longitudinal, fast and slow transverse acoustic phonons are calculated and compared with the orientation of the incomplete electric breakdown channels in accordance with the model of incomplete breakdown of crystals along the phonon fluxes. The possibility of controlling focused phonon fluxes by a strong electric field is predicted. The maximum deviations of individual focusing directions of slow transverse phonons in the field E = 107 V/cm can reach 41°. The effects of suppression of some phonon focusing paths and of generation of new ones by the field are revealed. It is shown that from the 24 directions of concentration corresponding to the infinite phonon fluxes, it is possible to find those coinciding with two of the three breakdown channels at E = 0 to 106 and 107 V/cm, respectively. The account of 15 additional local directions of “weak” phonon focusing paths, also sensitive to crystal data, not required by the breakdown model, provides coincidence of all the three discharge channels with individual directions of concentration in the range E = 0 to 106 V/cm.
The Conductivity of a δ‐Doped Parabolic Quantum Well in a Cross Electric Field
Authors: Safronov E. Yu. , Sinyavskii E. P. 
Published: July 2007

AbstractThe conductivity of a δ‐doped parabolic quantum well in cross electric field at low temperatures is studied. An alteration of the cross electric field causes an alteration of the magnitude of the electron–impurity interaction. It allows to alter the mobility of such a system by a cross electric field, which may be used for the creation of new electronic devices. The possibility of the appearance of a direct current in an alternating electric field forming a small angle with the direction of quantization is discussed.
On Antiferromagnetism, Charge Density Wave, and Superconductivity in the Extended Hubbard Model Studied by Means of the Slave‐Boson Method
Authors: Bulka B. R. 
Published: July 2007

AbstractThe ground state of the extended Hubbard model is studied. The stability conditions for the antiferromagnetic, the charge density wave, and the superconducting state are analyzed in the same slave‐boson representation, which is spin‐ and charge‐rotationally invariant. It is found that at the concentration of electrons no = 1 the stable solutions are similar in form.
The Diagram Technique for Calculation of Transport Constants of Random Inhomogeneous Materials. II. Low‐Field Hall Effect
Authors: German A. I. , Chaikovskii I. A. 
Published: July 2007

AbstractDiagram methods are applied for evaluating the off‐diagonal (Hall) components of the ac effective magnetoconductivity tensor σ(ω) in an inhomogeneous material for the case of low magnetic field. Closed expressions for σ(ω) are obtained in two approximations, namely in the self‐consistent cumulant approximation and in the effective‐medium approximation (EMA). Our expression for σ(ω) in the EMA coincides with the one obtained earlier by Fishchuk. The obtained results are applied to the model of a random binary mixture consisting of two conducting materials 1 and 2 with conductivity tensors σ and σ and volume fractions x and 1 − x, respectively. In the special case of σ = 0 and ω = 0 the (dc) Hall conductivity σ in both above‐mentioned approximations has a percolation threshold at some critical value Xc. In each approximation the value of xc coincides with the one for the dc diagonal (ohmic) conductivity σ* taken in the same approximation: the self‐consistent cumulant approximation gives xc = 1 – exp (−1/3), while in the EMA xc is equal to 1/3.
Periodic Solutions in Bubble Mode Resonance
Authors: Sigal M. A. 
Published: July 2007

AbstractA theory of periodic solutions for magnetostatic modes in a hexagonal bubble lattice based upon the application of the quasiperiodic Weierstrass ζ‐function and its even derivatives as matrix potential in common with new boundary conditions on the elementary cell is introduced. Periodic solutions for magnetostatic fields described by doubly periodic elliptic functions P(z) are obtained. The magnetic field structure for all four branches is investigated and is constructed for the low‐frequency branch ω = ω1.
A Mössbauer Effect Investigation of Fe Hyperfine Fields and Solubility Limit of Cr in Fe3−x CrxSi Alloys
Authors: Babu T. V. S. M. Mohan , Bansal C. 
Published: July 2007

AbstractDetailed Mössbauer effect studies on Fe3−xCrxSi alloys show a solubility of Cr up to a composition of x = 0.5 and a precipitation of Cr3Si phase beyond this composition. The effect of Cr on the hyperfine fields at the inequivalent (AC) and (B) sites is understood in terms of a local environment model with Cr substituting at the B site with a very small moment. Presence of B32 order besides the DO3 order is also indicated.
Plasma Waves in a Finite Superlattice
Authors: Kuchma A. E. , Sverdlov V. A. , Ermolin A. V. 
Published: July 2007

AbstractDispersion equations for plasma waves in a superlattice with a finite number of conducting layers are obtained. It is shown that the existence of surface‐like plasma waves in a finite superlattice is possible under definite conditions which represent the generalization of the well‐known restrictions for the surface waves in semiinfinite superlattices. Results are demonstrated for the case of a superlattice containing N = 3 layers.
Dynamical Transport Theories versus Semi‐Classical Solutions of the Boltzmann Kinetic Equation
Authors: Farvacque J.‐L. 
Published: July 2007

AbstractIn 1989, a dynamical transport theory was proposed. This theory is based on the use of the dielectric properties of materials. However, mistakes are made in the derivation, making this method far from being able to include as a coherent limit the classical solution of the relaxation time approximation of the Boltzmann kinetic equation. A corrected version of this theory is presented. Potentialities of this theory versus the classical relaxation time approach are pointed out (screening effects, local field effects, carrier‐carrier scattering, galvanomagnetic effects of second order, etc.). Finally, the coherence between our method and the relaxation time solution is shown as soon as classical approximations are used.
Valence Band Crystal Field Splitting of Hexagonal Diluted Magnetic Semiconductors
Authors: Twardowski A. , Chern‐Yu K. , Chen F. R. , Kuo S. S. , Ro C. S. , Chiu K. C. , Chou W. C. , Yang S. L. , Chuu D. S. , Chen Y. F. 
Published: July 2007

AbstractThe valence band crystal field and spin‐orbit splitting in hexagonal diluted magnetic semiconductors based on CdSe and CdS is studied. It is found that the crystal field splitting is practically magnetic ion independent for CdSe based crystals, whereas in the case of CdS based samples a strong influence of magnetic ion substitution on crystal field splitting is observed.
Effect of Crystal Anisotropy on Infrared Hole Transitions in Uniaxially Stressed Semiconductors
Authors: Bakhanova E. V. , Vasko F. T. 
Published: July 2007

AbstractPeculiarities of permittivity are studied for semiconductors with degenerate band structure modified by the uniaxial compression which induces valence band splitting. For [001] and [111] stress orientations cubic crystals become uniaxial, whereas for the [110] stress orientation they become biaxial. The contribution of intersubband hole transitions to the permittivity and the absorption coefficient is found to be significantly anisotropic in the frequency range corresponding to the subband splitting energy. Therefore, studying birefringence for different stress orientations may allow deformation potentials and stiffness constants to be determined.
Wave Reflection Analysis of a Quasibound State Using a Global Transfer Matrix
Authors: Redhammer R. , Urban F. 
Published: July 2007

AbstractAn illustrative analysis of the quasibound state using a complex reflection coefficient is presented. The global transfer matrix technique is formulated and used to evaluate the reflection coefficient. The quasibound state interacting with a half‐space continuum is the well‐known problem of a quantum well in an electric field and here it is called a quantum well mirror. The dependences of rectangular quantum well mirror and double barrier reflection coefficient on energy are compared. The wave functions are shown as well. A new way of finding the quasibound state energy and determining the quasibound state thickness based on the global transfer matrix behaviour is proposed.
Amplification of a Space‐Charge Wave in a Two‐Dimensional Electron Gas in a Strong Electric Field
Authors: Tralle I. E. , Filonov A. B. 
Published: July 2007

AbstractThe possibility of charge‐wave amplification in the two‐dimensional electron gas of the GaAs‐(AlGa)As heterostructure is considered. The amplification is the consequence of a beam instability in the 2D electron plasma which, in turn, is the consequence of the inversion of the electron distribution function of GaAs in a strong electric field.
Beam Instability and Space‐Charge Wave Amplification in a Semiconductor Plasma
Authors: Tralle I. E. , Sizjuk V. A. 
Published: July 2007

AbstractThe amplification of a space‐charge wave in a semiconductor induced by the beam instability is considered. The electron beam is regarded as being injected out of the quantum well by means of resonant tunneling. The plasma‐beam interaction is treated in terms of the hydrodynamic equations of a two‐component liquid and the Poisson equation. The increment of SCW is calculated and the dependence of the increment on the different parameters such as temperature, carrier concentration, spacing of grating, and so on is also considered.
Photoemission and Mössbauer Effect Studies of Sputter‐Deposited Fe‐Pd Alloys
Authors: Zhang S. L. , Zhang J. R. 
Published: July 2007

AbstractXPS core level and Mössbauer spectra of sputter‐deposited Fe‐Pd alloy films are studied. These films are composed of nonequilibrium b.c.c. and f.c.c. phases depending on the alloy composition. The core level spectra of Fe 2p and Pd 3d states reveal that the binding energy shift has a strong concentration dependence and the charge transfer between the constituent elements is appreciable. Mössbauer spectra at 290 K show that with increasing Pd concentration the average magnetic hyperfine field slightly increases in the b.c.c. alloys, whereas it decreases rapidly in the f.c.c. alloys.
Size and temperature dependence of electrical transport properties of vacuum evaporated Bi2Se3 films
Authors: Fouad S. S. , Morsy A. Y. , Talaat H. M. , El‐Tawab M. E. 
Published: July 2007

AbstractThe Bi2Se3 films of thicknesses in the range 50 to 546 nm are vacuum deposited on glass substrates at room temperature. After annealing for 1 h at 423 K, the electrical resistivity, Hall coefficient, and the thermoelectric power are measured. It is observed that the resistivity is strongly affected by both the film thickness and temperature, and the activation energy (ΔE) is found to vary from 0.116 to 0.279 eV with the decrease in film thickness. The Hall coefficient (RH) as well as the mobility increase with increasing film thickness. Also, the thermoelectric power varies in a similar manner. It is found that the deposits were all of n‐type and the carrier concentrations (n) measured by different methods have the order of 1020 cm−3. The analysis combining the data from thermoelectric power and electrical conductivity measurements, by using the effective mean free path theory of size effect in thin films developed by Pichard et al. leads to the determination of mean free path, carrier concentration, Fermi energy, and the parameter Ug = (d ln 1g/d ln E), where Ug is a parameter determining the energy dependence of the mean free path of carriers in infinitely thick films.
Modification of the absorption edge due to grain boundaries and mechanical stresses in polycrystalline semiconductor films
Authors: Maity A. B. , Chaudhuri S. , Pal A. K. 
Published: July 2007

AbstractExplicit expressions for the absorption coefficient beyond the absorption edge are obtained by considering the Franz‐Keldysh effect and mechanical stress to be operative simultaneously in the grain boundary regions of polycrystalline semiconductor films. The expressions are successfully utilized to explain the tail end of the absorption spectrum of ZnTe films.
Influence of uniaxial anisotropic edge‐film surfaces upon the properties of a vortex lattice
Authors: Saif A. G. 
Published: July 2007

AbstractThe influence of edge‐film surfaces upon the properties of a vortex lattice is studied. The film is considered to be a uniaxial anisotropic high‐temperaure superconductor of arbitrary thickness. Exact integral expressions are investigated for the distributions of the fields inside and outside the sample. Moreover, an analytical form of the total current density is calculated. Using these solutions, the forces on the vortex segments are completely determined. A simple form of the Gibbs free energy of the system is investigated. Agreement with previous results is achieved for some limiting cases of film thickness as well as for the isotropic case.
Emission‐limited currents in low‐mobility solids
Authors: Godlewski J. , Kalinowski J. , Mancini G. , Stizza S. 
Published: July 2007

AbstractResults of computer‐calculated solutions of a set of equations describing emission‐limited currents (ELC) in low‐mobility solids are presented. The continuity of current equation with electric field‐dependent mobility is used to calculate the field dependence of ELC under various injection conditions. Its shape and steepness are found to change strongly with decreasing scattering length of injected carriers, approaching the standard description of the one‐dimensional Onsager model with field‐independent mobility. The recombination of the charge carriers at the contact is shown to reduce the current without remarkable change of its functional dependence on practically accessible electric fields.
Entropy and specific heat of the 3D ising model as functions of temperature and microscopic parameters of the system
Authors: Kozlovskii M. P. , Pylyuk I. V. 
Published: July 2007

AbstractExplicit expressions for the critical amplitudes of the specific heat and other thermodynamic functions of the three‐dimensional Ising model with extracted universal part and non‐universal factor are obtained applying the non‐Gaussian measure density of fluctuation distribution for the calculation of the partition function. The curves for thermodynamic characteristics as functions of temperature and microscopic parameters of the Hamiltonian near the phase transition point are presented.
MFRG and DPIR for a S = 3/2 transverse ising model in a random field
Authors: Song W. J. , Yang C. Z. 
Published: July 2007

AbstractA spin‐3/2 transverse Ising model in a random field (RFTIM) is studied within the framework combined by mean‐field renormalization group theory (MFRG) with the discretized pathintegral representation (DPIR). The phase diagrams and the other critical properties are investigated.
Electric field dependent dielectric constants in amorphous semiconductors
Authors: Khan W. I. 
Published: July 2007

AbstractThe electric field dependence of dielectric constants in amorphous semiconductors is obtained theoretically. It can be shown, taking into consideration the lattice thermal energy, that the polarization vector Ps can exist in different orientations included in a cone. When an electric field is applied, the total energy changes and a new equilibrium is reached. This gives a relationship between field and polarization. A first‐order process effect is observed under certain conditions. Some experimental evidence of the field dependence is produced. Finally a method of evaluation of the coefficients involved in the free energy is presented.
The effect of doubled CO2 and model basic state biases on the monsoon‐ENSO system. II: Changing ENSO regimes
Authors: Turner A. G. , Inness P. M. , Slingo J. M. 
Published: July 2007

AbstractIntegrations of a fully‐coupled climate model with and without flux adjustments in the equatorial oceans are performed under 2 × CO2 conditions to explore in more detail the impact of increased greenhouse gas forcing on the monsoon‐ENSO system. When flux adjustments are used to correct some systematic model biases, ENSO behaviour in the modelled future climate features distinct irregular and periodic (biennial) regimes. Comparison with the observed record yields some consistency with ENSO modes primarily based on air‐sea interaction and those dependent on basinwide ocean wave dynamics. Simple theory is also used to draw analogies between the regimes and irregular (stochastically forced) and self‐excited oscillations respectively. Periodic behaviour is also found in the Asian‐Australian monsoon system, part of an overall biennial tendency of the model under these conditions related to strong monsoon forcing and increased coupling between the Indian and Pacific Oceans. The tropospheric biennial oscillation (TBO) thus serves as a useful descriptor for the coupled monsoon‐ENSO system in this case. The presence of obvious regime changes in the monsoon‐ENSO system on interdecadal timescales, when using flux adjustments, suggests there may be greater uncertainty in projections of future climate, although further modelling studies are required to confirm the realism and cause of such changes. Copyright © 2007 Royal Meteorological Society
Leukaemogenic mechanism of human T‐cell leukaemia virus type I
Authors: Yasunaga* Jun‐ichirou , Matsuoka Masao 
Published: July 2007

AbstractAdult T‐cell leukaemia (ATL) is a neoplastic disease derived from CD4+ T‐lymphocytes and etiologically associated with human T‐cell leukaemia virus type I (HTLV‐I). In addition to structural genes, HTLV‐I encodes regulatory and accessory genes in the pX region. Among them, Tax is thought to play a central role in leukaemogenesis through its potent transforming activity. However, since Tax is a major target of the host immune system, its expression is often lost in ATL cells, indicating Tax is dispensable in the last phase of leukaemogenesis. The HTLV‐I bZIP factor (HBZ), encoded on the HTLV‐I minus strand, was recently shown to be expressed in all ATL cells, and to support growth of human T‐cell lines. These findings suggest that HBZ is critical to ATL onset. In addition to viral factors and genetic and epigenetic changes in cellular genes, the host immune status and genetic background also function in leukaemogenesis. Copyright © 2007 John Wiley & Sons, Ltd.
Viability and sustainability of civilizations, corporations, institutions and ecological systems
Authors: Grossmann Wolf Dieter , Watt Kenneth E. F. 
Published: July 2007

AbstractAbstract— The viability and sustainability of civilizations, corporations, institutions and ecological life‐support systems (CIES) can now effectively be enhanced with new insights, new methods and new strategies. This is urgently needed because CIES's are increasingly more endangered by new as well as long‐known threats and risks. CIES' have many strengths to deal with these but also many deficiencies or weaknesses. Strengths and deficiencies of systems are relative terms which have to be assessed against potential threats and risks.Important potential threats are analysed and, in particular their combinations into new, more severe threats. Here a viability approach for CIES's is used to analyse their strengths and deficiencies and devise new criteria showing how to make these systems more capable of dealing with threats and more capable of viable evolvement.
Systems modelling of cost and quality: An application of extended physical system theory and simulation
Authors: Sushil  , Pankaj  
Published: July 2007

AbstractThis paper develops an integrated systems approach towards quality and cost in production systems. A spinning unit producing medium count ranges of yarn, has been taken as a case for study. The first part deals with developing a suitable methodology for the purpose by modifying the existing physical system theory modelling framework. The second part deals with the aspect of simulation for studying the impact of various processes and the quality of the output. Finally, the response of cost of output to the quality of output has been studied using the modified cost equation and carrying out the sensitivity analysis.
Systems characteristics in information systems design
Authors: Xu Li D. 
Published: July 2007

AbstractAlthough many information systems (IS) design methods and techniques are available to IS professionals, none of them completely supports the design process. One of the problems is that there is a mismatch between IS design method; and the system to be built. Actually, in designing an IS, the methods or techniques employed should match the types and characteristics of the system to be built. Thus paper will explore the relationship between IS types/characteristics and systems design methods, and provide IS designers with a systems framework to develop methods or techniques that match the types and characteristics of IS.
Life symptoms: The behaviour of open systems with limited energy dissipation capacity and evolution
Authors: Winiwarter Peter , Cempel Czeslaw 
Published: July 2007

AbstractFor income distributions, city‐size distributions and word frequencies we observe skewed or long‐tailed distributions of the PARETO‐ZIPF type. In general ‐for properties of units belonging to the same astrophysical, biological, ecological, urban, social, political, economic or mechanical machinery system ‐ we observe similar regularities referred to as Pareto law, Zipfs law or rank‐size law. We give a short historical overview over the discovery of these empirical regularities. Then we review a variety of theoretical tentatives, none of which can “explain” that similar regularities are observed in such an incredible wide range of scientific research areas.Finally, departing from a very specific model ‐ describing tribo‐vibro‐acoustic processes in machines ‐ we propose a generalized theoretical framework in terms of energy transformation with limited internal energy dissipation capacity, which is applicable to all fields.The proposed model “unifies” a large variety of concepts and applies a coherent terminology to fields, which have at first sight nothing in common. For the observed life symptoms, theoretical predictions can be compared with past and future empirical observations.What is most important is the model's inference power: from the observations of a set of units at a given moment of life‐time (a snapshot of the system), one can predict the average behaviour of a single unit over its entire life‐time.
To evolve an ear. Epistemological implications of gordon pask's electrochemical devices
Authors: Cariani Peter 
Published: July 2007

AbstractAbstract ‐ In the late 1950's Gordon Pask constructed several electrochemical devices having emergent sensory capabilities. These control systems possessed the ability to adaptively construct their own sensors, thereby choosing the relationship between their internal states and the world at large. Devices were built that evolved de novo sensitivity to sound or magnetic fields. Pask's devices have far‐reaching implications for artificial intelligence, self‐constructing devices, theories of observers and epistemically‐autonomous agents, theories of functional emergence, machine creativity, and the limits of contemporary machine learning paradigms.