bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical Evaluation of the Dynamic Properties of Amorphous Selenium
Authors: Rao R. V. Gopala , Venkatesh R. 
Published: July 2007

AbstractThe phonon frequencies of amorphous Se are calculated according to Bhatia‐Singh's method assuming the electronic contribution to the bulk modulus is zero. These longitudinal phonon frequencies are used to evaluate the dynamic structure factor in the viscoelastic approximation. It is found that the dynamic structure factor of Se exhibits characteristics similar to that of Al and Rb. The current correlation function JL(k, ω) and S(k, ω) are calculated for six typical momentum vectors. ωmax values are obtained from the computed JL(k, ω) correlation functions. The ωmax(k) versus k plots give a maximum midway between zero and the second peak position of S(k). S(k, ω) versus ω at fixed values of k follows the predictions made by Egelstaff. At large k, the S(k, ω) gives a Lorentzian single‐peaked curve resembling that of a perfect gas. It is found that the dynamic structure factor of amorphous Se resembles that of liquid metals like Al and Rb.
The Effect of Anharmonicities on the Absorption Spectrum of a Diatomic Linear Chain within a Central Force Model
Authors: Held Th. , Pfeiffer I. 
Published: July 2007

AbstractClosed‐form expressions for the Fourier‐transformed anharmonic force constants of a diatomic linear chain within a central force model are obtained. Some differences compared to those expressions obtained by some other authors, especially in Peierls' approximation, are discussed and illustrated by numerical calculations of the linewidth and frequency shift of the “reststrahlen” peak of a KCl crystal up to second order of the perturbation theory.
Composite Anderson‐Newns Model and Density of States Due to Chemisorption
Authors: Guleria R. , Ahluwalia P. K. , Sharma K. C. 
Published: July 2007

AbstractA systematic variation in the density of states (DOS) of a substrate with respect to the chemisorption of hydrogen on transition metals using the composite Anderson‐Newns model is investigated for different coverages. The substrate is a one‐dimensional periodically arranged chain of atoms. A comparison between the change in DOS using semi‐elliptical weighted DOS and triangular weighted DOS is also made for non‐magnetic and magnetic cases. The coverage dependence shows a discerning behaviour on the formation of bonding and antibonding peaks. As the coverage increases, the bonding and antibonding peaks are found to shift towards higher energies and at the same time the relative height of the peaks increases, that clearly shows, at which coverage more chemisorption is likely to take place.
Power Losses of a High‐Temperature Superconducting Semi‐Infinite Space
Authors: Saif A. G. 
Published: July 2007

AbstractAn exact solution of the anisotropic London equation is obtained for the system of a vibrating wire carrying dc current (a non‐vibrating wire carrying ac current) parallel to a high‐temperature superconducting planar surface. Also, the distribution of the external magnetic field outside the superconductor is exactly determined. The power losses and the reactive power losses on the surface of the sample are completely determined. It is found that these losses along the versor of the anisotropy axis are increased as λ increases, moreover, they are greater than the power losses along the crystal symmetry direction a. In the isotropic case a satisfactory agreement with previous results is achieved.
Pairing in a Two‐Dimensional Two‐Band Very Anisotropic Model in the Mean Field Approximation
Authors: Fazakas A. B. , Pitis R. 
Published: July 2007

AbstractA two‐dimensional model is proposed: there are two kinds of sites, with one electronic state per site; tunneling takes place only in one direction. The interaction involves only electrons on different sites. The existence of a phase transition involving interband pairing of electrons is discussed in the mean‐field approximation.
Spectral Studies of Isostructural Organic Metals (BEDT‐TTF)3(HSO4)2 and [Ni(dddt)2]3(HSO4)2
Authors: Świetlik R. , Kushch N. D. , Kushch L. A. , Yagubskii E. B. 
Published: July 2007

AbstractThe polarized reflectance spectra of (BEDT‐TTF)3(HSO4)2 and [Ni(dddt)2]3(HSO4)2 crystals are measured in the IR region (660 to 5200 cm−1) at room temperature. Moreover, the powder absorption spectra in the frequency range 400 to 40000 cm−1 are reported. Differences between charge transfer bands of both compounds are found. In [Ni(dddt)2]3(HSO4)2 the strong coupling of electrons with vibrations of C = C ring bonds is observed. The phase transition in (BEDT‐TTF)3(HSO4)2 at the temperature T = 130 K influences the IR powder absorption spectra, especially within the range of C = C vibrations.
Small‐Angle Scattering by Spherical Inhomogeneities of Different Radii and Refractive Indexes
Authors: Pomortsev R. V. , Skryabin Yu. N. 
Published: July 2007

AbstractThe cross‐section σ of small‐angle scattering of neutrons by inhomogeneities of a wide variety of sizes Rmin < R < Rmax is considered when the scattering crossover from diffraction R < Rc to refraction R > Rc takes place within the available range of size distribution. When qRc ≫ 1 the cross‐section averaged by the distribution function P(R) ∝︁ R−3−Δ(0 < Δ < 1) results in the dependence σ(q) ∝︁ q−4 + 4 in the Born approximation, where q is the transfer momentum, and in case qRc ≪ 1 the averaging leads to the dependence σ(q) ∝︁ q−2+Δ. In the case of scattering in condensed matter containing large scale and loose pores, to which a distribution of the scattering potential can be attributed, the averaging in refractive index fluctuations is carried out. The result of such an averaging is demonstrated by means of a homogeneous distribution.
An Identical Quasicrystal‐Structure Model for T2‐ (AI6CuLi3) from Two Different Six‐Dimensional Crystals
Authors: Pan G. Z. , Li F. H. 
Published: July 2007

AbstractThe restriction for obtaining an identical quasicrystal by using the projection method from different high‐dimensional crystals is discussed. Two kinds of six‐dimensional crystal‐structure models, (Al, Cu)7Li and (Al, Cu)7Li20, are used to obtain the icosahedral quasicrystalline phase T2‐ (Al6CuLi3). It is demonstrated that an identical idealized icosahedral phase T2‐A16CuLi3 with the same chemical composition, mass density, and atomic arrangement can be obtained by projecting anyone of two 6D crystals onto the physical space. Idealized projection windows are determined on the basis of the rhombic tiling of body‐centered cubic crystals and similarities between the local atomic arrangement of the icosahedral phase T2‐A16CuLi3 and that of its crystalline approximant R‐Al5CuLi3. The chemical formula and the mass density of the idealized T2 phase is given.
Spectrum of an Electron Localized by Electrostatic Image Forces in Thin Semiconductor Layers
Authors: Tkach M. , Holovatsky V. , Voitsekhivska O. 
Published: July 2007

AbstractThe spectrum of an electron confined in a layer with the dielectric constant ϵ, embedded between two media with larger (ϵ> > ϵ) and smaller (ϵ< < ϵ) values of the dielectric constant is calculated. The dependence of the spectrum on the layer thickness and on the ratio between the dielectric constants of the layer and the media is calculated. It is shown that if the crystal thickness increases, the whole spectrum of electrons shifts into the region of negative energies and becomes quasi‐hydrogenic there.
Bound State of Electrons in a One‐Dimensional Chain
Authors: Brizhik L. S. , Eremko A. A. 
Published: July 2007

AbstractThe problem of dynamical interaction of two electrons interacting with acoustic phonons in a one‐dimensional chain is investigated using the variational method in nonadiabatic approximation. It is shown that under certain conditions electrons form a bound delocalized singlet spin state. The energy of this state and the binding energy are calculated.
Thermal Strain Effects in YBa2Cu3O6+δ Superconductors
Authors: Nechiporenko I. N. , Popov V. P. , Sirenko V. A. 
Published: July 2007

AbstractResults of the dilatometric study of superconductors with different contents of oxygen and normal phase are presented. They suggest a significant influence of the competition between strain and composition effects upon the superconducting order parameter formation and crystallographic ordering, which is revealed in anomalies on the measured temperature depcndencies of thermal strains.
Tricritical Behaviour in a Simple Model of an Itinerant Antiferromagnet
Authors: Chamati H. 
Published: July 2007

AbstractThe thermodynamics of a simple electron—spin system describing a paramagnetic—antiferromagnetic phase transition is considered for an arbitrary value of the coupling constant in the presence of doping controlled by the chemical potential μ. The ground state is studied exactly, and a second‐order phase transition with respect to μ is found. The case of nonzero temperature is examined numerically. The Landau expansion depending on two parameters is analyzed near the critical line and in the vicinity of the tricritical point (μ*, T*) in the (μ, T)‐plane. The phase diagram in the (n, T)‐plane (n is the electron concentration) shows a coexistence phase for 0 < T ≦ T* and the existence of an isolated point at T = 0.
Phase Diagrams of the Dilute Ashkin‐Teller Model
Authors: Benyoussef A. , Loulidi M. 
Published: July 2007

AbstractThe phase diagram of the dilute Ashkin‐Teller model is investigated within a real‐space renormalization scheme. Using two probability distributions which correspond to the two‐spin coupling, K2, dilution and the four‐spin coupling, K4, dilution, a rich variety of phase diagrams are obtained. The percolation phase diagram is obtained at T = 0. It describes a system of two types of links with different concentrations.
Electron Paramagnetic Resonance of an O, Ion Trapped in KI
Authors: Moens P. , Callens F. , van Doorslaer S. , Maes F. , Matthys P. 
Published: July 2007

AbstractAn ozonide ion is detected in single crystals of KI by means of electron paramagnetic resonance. The new data support the monovacancy model for the location of the O ion in the alkali halides proposed recently. Theoretical calculations using self‐consistent field Hartree‐Fock methods are performed in order to determine the principal g‐tensor values for the O molecular ion. The results are in good agreement with the experimental data.
Implantation Profile and Positronium Fraction for Low‐Energy Positrons
Authors: Shrivastava S. B. , Agrawal Kavita 
Published: July 2007

AbstractThe diffusion equation for positrons is solved subjected to two types of implantation profiles, namely, exponential and derivative of Gaussian type. The positronium fraction obtained using the two profiles has been compared with experimental results. It is found that in general, the use of the derivative of the Gaussian‐type profile gives better results. The maximum yield of the positronium as a function of temperature is predicted corresponding to the different orientations of the aluminum surface.
Influence of Hydrostatic Pressure on the Fermi Surface of Vb Transition Metals
Authors: Solanki A. K. , Ahuja R. , Auluck S. 
Published: July 2007

AbstractAb initio calculations of the effect of hydrostatic pressure on the Fermi surface of transition metals, vanadium (V), niobium (Nb), and tantalum (Ta) using the linear mufin‐tin orbital method in the atomic‐sphere approximation are presented. The self‐consistent calculations are performed with the use of various exchange‐correlation potentials. The results are compared with available experimental data and theoretical Calculations.
Oscillator Strengths of the Intraband Transitions in a Semiconductor Superlattice in an Electric Field
Authors: Tronc P. 
Published: July 2007

AbstractThe oscillator strengths of the intraband optical transitions in a semiconductor superlattice in an electric field parallel to the growth axis is calculated using a perturbation model with Bloch envelope functions. The applied electric field induces strength asymmetry between the oblique +p and — p transitions of the Wannier‐Stark ladder.
Rotational Hysteresis Work and Rotational Hysteresis Integral of Polycrystalline Permanent Magnets
Authors: Elk K. 
Published: July 2007

AbstractThe possible information on the magnetization processes of the grains available from the rotational hysteresis work and the rotational hysteresis integral of polycrystalline samples is investigated. A combined theoretical model for the switching field of the grains is considered, and numerical computations are carried out for different values of the model parameters. Especially, the influence of different orientations of the rotational plane of the applied field is studied.
EPR Identification of the Trigonal Ti‐Sp Pair in GaP
Authors: Kreissl J. , Ulrici W. , Gehlhoff W. 
Published: July 2007

AbstractEPR experiments on titanium‐doped n‐ and p‐type GaP are reported. In n‐type GaP:Ti co‐doped with sulphur additional to the known isolated defects an angular dependent spectrum showing trigonal symmetry can be observed. The analysis suggests that the spectrum is caused by a donor‐acceptor nearest‐neighbour pair defect [Ti
‐Sp]. Theparameters of the spin‐Hamiltonian are determined as follows: S = l, g | = g⟂ = 1.95(1), |D| = 0.0670(5) cm−1. The concentration of thepair defect confirms that Coulomb attraction is responsible for its preferential formation. However, no EPR spectrum of a pair can be proved for p‐type GaP: Ti co‐doped with Zn, although the existence of such a pair is also most probable. The lack of the EPR spectrum could have spectroscopical reasons.
Dispersion in the Linear and Second‐Order Bond Polarizabilities of Alkali Halides
Authors: Kucharczyk W. 
Published: July 2007

AbstractAn analysis of dispersion in the linear bond polarizability and in the lattice contribution to the second‐order polarizability of some alkali halides is performed. The linear and nonlinear polarizabilities are evaluated employing the elasto‐optic coefficients p11; p12, and p44. The results obtained show significant wavelength dependence of the linear polarizability and the longitudinal component of the second‐order polarizability. The anisotropy of the bond polarizability is also found to be frequency dependent.
The Contributions of Lattice Anharmonicity to the Zero‐Phonon Linewidth
Authors: Chow H. C. 
Published: July 2007

AbstractThe influence of the host lattice anharmonicity on the optical absorption and emission by an impurity center or a defect in a solid is studied theoretically. Lattice anharmonicity is shown to contribute to the width of the zero‐phonon line via two mechanisms: the finite lifetimes of phonon states and those impurity (defect)‐phonon collisions which are mediated by another phonon.
Dynamical theory of X‐ray diffraction by elastically bent crystals with microdefects. II. Diffraction intensity
Authors: Molodkin V. B. , Olikhovskii S. I. , Kostyuk A. N. 
Published: July 2007

AbstractThe amplitudes of wave fields inside a macroscopically deformed crystal with defects are obtained in the two‐beam approximation. The amplitudes of coherent (strong Bragg and “quasidiffuse”) and diffuse waves emerging from the crystal are determined by taking account of boundary conditions for both Bragg and Laue cases of diffraction. The general expressions for coherent and diffuse components of the differential reflection power of bent crystals with microdefects are obtained.
Hamiltonian dynamics of the landau model of ferroelectric liquid crystals (II)
Authors: Pitanga P. , Filho A. Ribeiro , Mundim K. C. 
Published: July 2007

AbstractFerroelectric liquid crystals are presented as a simple non‐integrable Hamiltonian system. The smectic A‐smectic C* phase transition undergoes a Hopf bifurcation. The Poincaré sections of the solutions in the smectic C* phase shows the existence of spatially chaotic behavior of the molecular structure depending on temperature and external magnetic field. The smectic C‐smectic C* phase transition is also studied as second‐order derivative Hamiltonian theory.
Vacuum ultraviolet optical analysis of spin‐cast chitosan films modified by succinic anhydride and glycidyl phenyl ether
Authors: Nosal W. H. , Thompson D. W. , Tiwald T. E. , Sarkar S. , Subramanian A. , Woollam J. A. 
Published: July 2007

AbstractOptical properties of spin‐cast chitosan films were determined in the vacuum ultraviolet (VUV) through visible regions of the spectrum using spectroscopic ellipsometry. The onset of absorption in the ultraviolet was determined for chitosan films modified with succinic anhydride (SA) and glycidyl phenyl ether (GPE). This absorption was accounted for by including Gaussian and Tauc–Lorentz shaped oscillators in the optical model. VUV through visible optical constants were determined for these modified films, as well as for immunoglobulin G (IgG) attached to GPE‐modified samples. Several resonant oscillator structures exhibit greatly differing oscillator parameters for the as‐deposited, as well as SA‐ and GPE‐modified films. These in‐plane and out‐of‐plane oscillator strengths, energy positions, and broadening were determined and tabulated, and their chemical origins identified. A phenyl resonant π‐bond at approximately 6.3 eV was observed for the GPE‐modified sample. This was not present in the bare chitosan data. GPE contains a phenyl group in the molecule and absorption due to it is clearly identified. Clarity of data after surface chemical modification is due to the high surface sensitivity of VUV ellipsometry. Copyright © 2007 John Wiley & Sons, Ltd.
The general rescue subsystem‐adaptation and structure at sea
Authors: Skyttner Lars 
Published: July 2007

AbstractThe existence of a general rescue subsystem in higher organisms, as part of the GLS theory and the GAS syndrome, is asserted. Working principles for the system and its existence throughout higher system levels are presented. Among important processes demonstrated are the adaptation of the system to special threats at sea and the storage of the system's knowledge and organization in the sea‐safety convention. Recursiveness of the rescue subsystem within all higher system levels was found to be a basic requisite for individual survival, especially at sea. Finally, the most serious threat to lives on board ships at sea, was found to be system morality failures.
A systems‐based conceptual framework for auditing
Authors: Swanson G. A. , Marsh Hugh L. 
Published: July 2007

AbstractSince the stock market crash of 1929, the auditing profession has rapidly emerged in advanced economies. The procedures of the profession have generally evolved out of political processes without the systematic guidance of a cohesive conceptual framework. That eclectic approach has produced generally accepted accounting principles that encourage publication of global organizational performance assessments such as net income that have little obvious connection to the concrete processes they purport to describe. The approach, furthermore, allows fragmented and disconnected auditing procedures. This paper presents an interpretive and analytical study of auditing in organizations and societies. A systematic conceptual framework of auditing based on observable, measurable entities is developed through living systems theory. This approach provides a means of applying to auditing the well developed investigation methods and procedures of the sciences.
System life cycle ‐ system life: The model ‐ based technical diagnostics ‐ A view on holistic modelling
Authors: Cempel C. , Natke H. G. 
Published: July 2007

AbstractMan‐made systems are becoming more and more complex, so there is a necessity to analyse and simulate their dynamic behaviour over their whole life. To deal with these problems we require a holistic model of the operating system which includes the concept of life. This is defined on the basis of energy internally dissipated in the system, when it is treated as open and energy‐transforming. The holistic model of a system can be very useful for the space‐time‐life simulation of its condition at the design stage and for a model‐based diagnosis at the life stage. This procedure will substantially increase the reliability of operating systems and reduce the total life cycle costs.
Methodology for Design of Mis Architecture (INFLOS)
Authors: Gupta M. P. , Sushil  
Published: July 2007

AbstractAbstract Management Information System (MIS) architecture reveals the nexus of information‐decision elements and has been described as an important planning tool of MIS development. In this paper, it is considered as a key design issue and a methodology (INFLOS) is presented for the same. Salient features of INFLOS have been discussed. The methodology proceeds in two phases. This paper is restricted to discuss only the first phase.
Visionary Systems Thinking (VST) as a Support to Creativity in the Quality Management (TQM) Process
Authors: Filion Louis Jacques 
Published: July 2007

AbstractAbstract ‐ Innovation, the introduction of new products/services and new ways of doing is one of the dimensions of quality. It is achieved by the integration of creativity. Visionary Systems Thinking (VST) based on Soft Systems Methodology (SSM) ‐ is identified as one of the concepts for supporting creativity in the quality management (TQM) process. This paper presents VST and proposes a model for effective integration of quality management within the managerial process. Learning, unlearning and anticipatory learning become basic means for making this possible.
Symbolic and subsymbolic models, and their use in systems research
Authors: Pessa Eliano 
Published: July 2007

AbstractThis paper contains a sketch of a generalized systems theory in order to deal with the so‐called “subsymbolic” models, whose implicit informational content cannot be made entirely explicit in a reasonable amount of time. To deal with such a situation, a new “genetic” approach has been proposed, in which the researcher manages a “population” of models, instead of a single one. The systemic modeling activity thus become equivalent to an evolutionary dynamics of this population, driven by suitable “genetic” rules and satisfying some fitness criteria. Some concrete examples are presented to this regard, so that a rigorous formalization of this new type of systems theory becomes possible, opening the way for a semi‐automatized application to the modeling of economic, social, and psychological systems, where we deal with organized complexity.
Discontinuous change in multilevel hierarchical systems
Authors: Rosser J. Barkley , Folke Carl , Günther Folke , Isomaki Heikki , Perrings Charles , Puu Tönu 
Published: July 2007

AbstractWe examine sources and dynamics of discontinuous changes in discrete multi‐level hierarchical ecological‐economic systems. We hypothesize the anagenetic moment, the creation of a new level of hierarchy, as arising from variable entrainment at some level. Bottom‐up as well as top‐down dynamics are studied and competing theories of the sources of such discontinuities are reviewed. Implications for the analysis of complex ecological‐economic systems are considered depending on whether they are characterized by single hierarchy, bi‐hierarchy, or matrix hierarchy relationships.
Gdss does not guarantee equal participation
Authors: Maris Jo‐Mae 
Published: July 2007

AbstractGroup decision support systems (GDSS) provide forums capable of reducing group process loss and of allowing equal participation. The design of GDSS provides conditions necessary to produce equal participation, but a forum does not ensure equal participation. Reducing group process loss increases the number of comments produced by groups using GDSS. Participants producing more comments did not lead to a uniform distribution of the number of comments. Our study, also, investigated quantity of comments produced by participants with some self‐reported measures of participation. We found participation was associated with “talkativeness”.