bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calculated Optical Properties of the Anisotropic Transition Metals
Authors: KRASOVSKII E.E. , ANTONOV V.N. 
Published: November 2004

The optical properties of Sc, Ti, Y, Zr, Tc and Ru are studied theoretically. The dielectric functions of metals are calculated ab initio in the framework of self-consistent one-electron theory. The Schrödinger equation for the Bloch functions is solved numerically using the linear augmented plane wave (LAPW) method. The momentum matrix elements are computed directly from the LAPW wave functions. On the basis of the calculated energy band structure the optical constants (dielectric functions, optical conductivity, reflectivity, energy loss function) were determined. The theoretically obtained spectra are compared with experimental data. The calculated curves have been found to describe all the main features of the anisotropy of optical spectra. The origin of all the structures is elucidated. The reason for the significant anisotropy of the infra-red reflectivity is discussed.
Q2R+Q2R AS A UNIVERSAL BILLIARD
Authors: CORDERO PATRICIO , GOLES ERIC , HERNANDEZ GONZALO 
Published: November 2004

In this work we study the computing capabilities as well as some dynamical properties of an automaton called M4R. This automaton corresponds to the mixing of the energy profiles of two independent copies of the Q2R automaton with frustrations. We associate to each copy of a Q2R an equivalent automaton M2R, which, with the Margoluos neighborhood, exhibits the local changes of the Q2R energy.1 By doing so we generalize the dynamics by upgrading M2R according to four partitions of the lattice. This new dynamics — called M4R — is based on a local rule which corresponds to the local energy change of two independent copies of Q2R. The M4R model is reversible and conservative (magnetization is constant in time) and it has properties of a discrete billiard (as some of the hydrodynamics discrete versions of Navier-Stokes models). Moreover, this automaton has powerful computing capabilities. In fact, by using some special configurations of M4R, we exhibit universal gates and register that allow us to code any algorithm.
FEIGENBAUM’S CONSTANT FOR MEROMORPHIC FUNCTIONS
Authors: GALLAS JASON A.C. 
Published: November 2004

We calculate Feigenbaum’s constant for a double-periodic meromorphic function: the Jacobian elliptic function sn[2K (m)x, m]. For m=0 this function reduces to sin(πx), with real period, while for m=1 it reduces to a hyperbolic tangent, having a pure imaginary period. For intermediary m values it is unimodal but with a non-quadratic m-dependent maximum. The bifurcation tree for sn[2K(m)x, m], although very much compressed in [0, 1], presents δ=4.699… for all values of m.
MONTE CARLO METHODS FOR FIRST ORDER PHASE TRANSITIONS: SOME RECENT PROGRESS
Authors: BINDER KURT , VOLLMAYR KATHARINA , DEUTSCH HANS-PETER , REGER JOSEPH D. , SCHEUCHER MANFRED , LANDAU DAVID P. 
Published: November 2004

This brief review discusses methods to locate and characterize first order phase transitions, paying particular attention to finite size effects. In the first part, the order parameter probability distribution and its fourth-order cumulant is discussed for thermally driven first-order transitions (the 3-state Potts model in d=3 dimensions is treated as an example). First-order transitions are characterized by a minimum of the cumulant, which gets very deep for large enough systems. In the second part, we discuss how to locate first order phase boundaries ending in a critical point in a large parameter space. As an example, the study of the unmixing transition of asymmetric polymer mixtures by a combination of histogram techniques and finite size scaling is described. As a final problem, we discuss the shift of the gas-liquid condensation in thin-film geometry confined between two parallel plates due to boundary fields (“capillary condensation”). Being interested in temperatures far below bulk criticality (e. g. near the wetting transition), special thermodynamic integration techniques are the method of choice, rather than the use of finite sizes scaling to map out the (asymmetric) phase diagram.
SEMI-FREE FIELD REPRESENTATION AND STRING FIELD THEORY IN 2D GRAVITY
Authors: AREF’EVA I. YA. , ZUBAREV A.P. 
Published: November 2004

String field theory for 2D gravity coupled to a c=1 matter field is described. We use the free field representation and take into account the semi-bounded of the Liouville mode in the last step of calculations. We call such representation semi-free field representation. It is shown that the Witten string field theory gives a tachyon action which up to some, factor in the interaction term coincides with the Das-Jevicki-Polchinski action. Starting from string field theory with semi-free field representation we calculate string amplitudes. These amplitudes instead of energy conservation δ-functions contain energy denominators which residues coincide with the Veneziano (Shapiro-Virasoro) amplitudes for open (closed) string and exhibit very interesting property: the s, t and u poles become the poles in respect to individual external momentum. These poles are related with higher levels excitations living only with fixed momentum.
GENERALIZATION OF MANTON’S CONSTRUCTION OF THE WEINBERG-SALAM MODEL WITH A GAUSS-BONNET TERM
Authors: BERTRAND CHRISTINE , KERNER RICHARD , MIGNEMI SALVATORE 
Published: November 2004

In a paper1 published in 1979 Manton has derived the bosonic sector of the Weinberg-Salam electroweak model by considering the Yang-Mills Lagrangian on a six-dimensional space M4×S2. The model turned out to be very rigid and identified the Weinberg angle with the angle between two neighbor roots in the Cartan diagram of the gauge group. leading to θW=60° for SU(3), θW=45° for O(5) and θW=30° for G2 and to the equality of the masses of the Z particle and of the Higgs boson. We generalize this model by identifying the Yang-Mills Lagrangian with a part of the Einstein-Hilbert Lagrangian on the fibre bundle P(M4×S2), and by adding to it a Gauss-Bonnet invariant. which produces new terms, quartic and cubic in Fμν. This in turn modifies the definition of the Weinberg angle and the Higgs mass. The new free parameter is the dimensional factor in front of the Gauss-Bonnet term. We discuss the values of MW, MZ and MH in function of this parameter and the radii of the internal space S2 of the gauge group G. Realistic values can be obtained if the Gauss-Bonnet term contributes to the Lagrangian with a negative sign.
He DIFFRACTION FROM Ag(110) SURFACE
Authors: ARTUNÇ M. , CEYLAN M. , KOLSUZ N. 
Published: November 2004

Using the exact close-coupling method we have investigated the diffraction intensities of He atoms from a Ag(110) surface. He-Ag(110) interaction is represented by a corrugated Mie potential. In our calculations we have used three different well depths D. Diffraction intensities were calculated for x = <001> direction. The softness parameter β is optimized for a given incident energy Ei and incident angle θi so as to reproduce the experimental results. Using well depth D and van der Waals constant C3 for six He-metal (Al, Ni, Cu, Ag, Pt, Au) systems we have obtained a relation, D = 0.070C3 − 9.006, between parameters D and C3. Our results are in good agreement with experimental observations.
SINGLE PARTICLE AND OPTICAL GAPS IN CHARGE-TRANSFER INSULATORS
Authors: Bang Y. , Castellani C. , Grilli M. , Kotliar G. , Raimondi R. , Wang Z. 
Published: November 2004

We analyze the collective excitations near a Mott-Hubbard and a metal charge transfer insulator transition, using the slave boson technique. We show that the Mott transition can be viewed as an excitonic softening, which takes place when the bound state between the lower and upper Hubbard bands reaches zero energy. The exciton energy is related to the jump of the chemical potential at zero doping. In a charge transfer insulator this mode describes a p-d charge fluctuation, i.e. it is a charge transfer exciton. In the single band Hubbard model the excitonic resonance describes virtual transitions between the lower and the upper Hubbard band. Finally we contrast the behaviour of the collective modes near the Mott transition with and near the Charge Transfer Instability. In the former the exciton energy and the charge compressibility go to zero. In the latter the exciton energy remains finite and the charge susceptibility diverges, causing phase separation.
A THEORY OF FERROMAGNETISM IN THE HUBBARD MODEL WITH INFINITE COULOMB INTERACTION
Authors: IZYUMOV YU. A. , LETFULOV B.M. , SHIPITSYN E.V. , CHAO K.A. 
Published: November 2004

On the basis of a regular perturbation theory in the form of diagrammatic technique with X-operators, a ferromagnetic state in the Hubbard model with infinite on-site Coulomb interaction U is studied for a wide range of electron concentration n. Treating the kinetic energy of electrons as perturbation, we get the exact graphic representations for three Green’s functions [Formula: see text] and [Formula: see text] for electrons with spin ↑ and ↓ (spontaneous magnetic moment is in ↑ direction) and [Formula: see text] for spin waves. All of them are expressed through the unique system of four-point and three-point vertex parts for effective electron-magnon and electron-electron interactions. These vertex parts are calculated in two approximations: a low-density approximation for n≪1 or nh=1–n≫1, and the generalized random-phase approximation (GRPA), which was suggested earlier by us for the description of paramagnetic phase in this model. An important result in both cases is the understanding of essential difference of electron states with spin ↑ and ↓. The state for ↑ has coherent character in all region of electron concentration (n>nc) where a ferromagnetic state exists, while the state for spin ↓ has mixed characters including both coherent and incoherent contribution. For the saturated ferromagnetism (n>ns) when nh≪1, [Formula: see text] is an entirely incoherent (nonquasiparticle) state. Appearance of incoherent state is probably a general property of strongly correlated systems distinguishing its behavior from the Fermi liquid. We show also that the Hubbard-I approximation has no region of applicability for the electron with spin ↓ in a ferromagnet and we found a new factor describing the correlation-narrowing of ↓ spin electron band. Green’s function [Formula: see text] calculated in two different limits n≪1 and nh≪1, are jointed together to allow us to calculate ns which lies in the intermediate concentration regime. For simple cubic lattice we found ns=0.87. In the limit nh≪1 our results reduce to the earlier known ones, including Nagaoka’s result for the spin wave energy. We point out the way to construct a rigorous theory for ferromagnetic state in the intermediate range of electron concentration. In the conclusion several important problems are discussed in connection to the continuation of the present work.
A HARMONIC BALANCE APPROACH FOR CHAOS PREDICTION: CHUA’S CIRCUIT
Authors: GENESIO R. , TESI A. 
Published: November 2004

The paper proposes a practical engineering approach for predicting chaotic dynamics in an important class of nonlinear systems. The aim of this approach is to provide a heuristic method of analysis which can give reasonably accurate answers but is far simpler to apply than other more rigorous methods based on nonlinear dynamics. Our approach is founded on the harmonic balance principle and uses standard describing function techniques well known to design engineers. Our method consists of a synergism of two independent techniques, each one constituting a possible mechanism for chaos. These two techniques are combined into a single algorithm which is highly efficient computationally, taking only a fraction of the time normally required by other more exact procedures. In order to present and illustrate our algorithm clearly, and in order to compare its predictions with readily available results obtained by rigorous methods, we have chosen Chua’s circuit as a vehicle to demonstrate the effectiveness of this approach. Chua’s circuit was chosen not only for the huge amount of results already published concerning the dynamics of this system, but also because it represents a real physical system easily built in the laboratory, and whose simple mathematical model has proven to be realistic and mathematically tractable. Although our algorithm does not guarantee its prediction is fully reliable, any more than the widely used describing function method does, its significance is based entirely on the empirical evidence that it yields qualitatively correct, though not exact, results for all of the chaotic phenomena that we have investigated in Chua’s circuit, as well as in many other chaotic systems. We hope therefore that our chaos prediction algorithm will find practical uses among engineers and scientists not familiar with more specialized mathematical approaches, in search of a simple and practical, although not rigorous, tool for analyzing systems with complex dynamics.
STABILITY OF EQUILIBRIUM STATES OF NONLINEAR STRUCTURES AND CHAOS PHENOMENON.
Authors: SHILKRUT D. 
Published: November 2004

The “classical” chaos of deterministic systems is characteristic for the motion of dynamical systems. Recently, some attempts were made to find static analogies of chaos [Thompson & Virgin, 1988; Naschie & Athel, 1989; Naschie, 1989]. However, this was considered for structures in specific artificial conditions (for example, infinitely long bars with sinusoidal geometric imperfections) transferring de facto the boundary value problem (which always describes static deformation of structures) into an initial value problem characteristic for problems of motion. In this article, chaotic (unpredictable) behavior is described for a usual (not special) nonlinear structure in statics, which is governed, naturally, by a boundary value problem in a finite interval of the argument. The behavior of this structure (geometrically nonlinear plate), which is an example of the class of static chaotic structures, is investigated by a new geometrical approach called the “deformation map.” The presented results are one of the first steps in the chapter of chaos in statics, and therefore the link between “classical” and static chaos needs further investigations.
GENERALIZATIONS OF THE CHUA EQUATIONS
Authors: BROWN RAY 
Published: November 2004

In this paper we present two generalizations of the equations governing Chua’s circuit. In order to obtain the first generalization we simplify Chua’s equations by replacing the piecewise-linear term with a signum function. The resulting simplified system produces a double scroll similar to the one observed experimentally in Chua’s circuit. What is significant about this simplified system is that it can be reduced to what we shall call a two-dimensional single scroll, and from the two-dimensional single scroll we are able to derive a one-dimensional map. This entire derivation is carried out analytically, in contrast to the one-dimensional map analysis that has been carried out for the Lorenz equations which is based on axioms. After we have carried out our analysis for this simplified version of Chua’s equations, we use these equations as a guide to the construction of the first generalization to be presented in this paper. We call this a type-I generalization of Chua’s equations. The generalization consists in using a two-dimensional autonomous flow as a component in a three-dimensional autonomous flow in such a way that the resulting equations will have double scroll attractors similar to those observed experimentally in Chua’s circuit. The value of this generalization is that: (1) it provides a building block approach to the construction of chaotic circuits from simpler two-dimensional components which are not chaotic by themselves. In so doing it provides an insight into how chaotic systems can be built up from simple nonchaotic parts; (2) it illustrates a precise relationship between three-dimensional flows and one-dimensional maps. Of particular significance in this regard is a recent paper of Misiurewicz [1993], which analytically connects the two-dimensional single scroll to the class of unimodal maps, thus providing a framework within which a theory linking unimodal maps to three-dimensional flows may be possible. The second generalization is suggested by considering three-dimensional flows whose only nonlinearities are sigmoid, sgn, or piecewise-linear functions. Clearly, such flows are a generalization of the Chua equations. We call these equations type-II generalization Chua equations. The significance of this direction of investigation is that attractors similar to the Lorenz and Rössler attractors can be produced from type-II generalized Chua equations in a building block approach using only piecewise-linear vector fields. As a result we have a method of producing the Lorenz and Rössler dynamics in a circuit without the use of multipliers. This suggests that the type-II generalized Chua equations are in some sense fundamental in that the dynamics of the three most important autonomous three-dimensional differential equations producing chaos are seen as variations of a single class of equations whose nonlinearities are generalizations of the Chua diode.
REFLECTION IN OBJECT-ORIENTED PROGRAMMING
Authors: Ibrahim Mamdouh H. 
Published: November 2004

Recently, the notion of having programming languages and computational systems that allow their programs to reason about themselves and reflect on their computations has attracted the attention of many researchers. These systems, called "Reflective Systems", promise many advantages over conventional systems. For example, dynamic program stepping, execution tracing, and code analysis and modification at run time are few of the reflective operations that can be easily implemented in reflective systems. Reflectivity of programming languages allows the language users to extend the language to support other programming paradigms. Reflective systems can also play an important role in programming solutions for non-conventional domains. Artificial intelligence applications, particularly learning systems, benefit from the reflectivity of a programming language. A learning system must be able to modify itself at run time to incorporate its learned behaviors. The goal of this article is to define reflection and its components, introduce the appropriate terminology, and present briefly some reflective applications in object-oriented systems.
INTELLIGENT AND COOPERATIVE INFORMATION SYSTEMS MEET MACHINE LEARNING
Authors: VITTAL JOHN , SILVER BERNARD , FRAWLEY WILLIAM , IBA GLENN , FAWCETT TOM , DUSSEAULT SUSAN , DOLEAC JOHN 
Published: November 2004

Intelligent and Cooperative Information Systems (ICIS) will have large numbers of distributed, heterogeneous agents interacting and cooperating to solve problems regardless of location, original mission, or platform. The agents in an ICIS will adapt to new and possibly surprising situations, preferably without human intervention. These systems will not only control a domain, but also will improve their own performance over time, that is, they will learn. This paper describes five heterogeneous learning agents and how they are integrated into an Integrated Learning System (ILS) where some of the agents cooperate to improve performance. The issues involve coordinating distributed, cooperating, heterogeneous problem-solvers, combining various learning paradigms, and integrating different reasoning techniques. ILS also includes a central controller, called The Learning Coordinator (TLC), that manages the control of flow and communication among the agents, using a high-level communication protocol. In order to demonstrate the generality of the ILS architecture, we implemented an application which, through its own experience, learns how to control the traffic in a telephone network, and show the results for one set of experiments. Options for enhancements of the ILS architecture are also discussed.
Inflecting Gender: Zhan Kai/Siqi Zhai's 'New Novels' and Courtesan Sketches
Authors: Widmer Ellen 
Published: November 2004

AbstractThis essay introduces Zhan Kai/Siqi Zhai, a little known writer of the late Qing. It focuses on his two "new novels" (Zhongguo xin nühao and Nüzi quan, both of 1907) which it presents in the context of his sketches of courtesans, a genre with which he was more at home. The two genres configure gender in different ways. Whether it be the intended reader, central characters, or narrator, the gender composition shifts when Zhan moves to his new style. I hypothesize that these changes stem from his attempts to reach gentlewomen, an audience newly drawn to novels at that time.
Corruption and Integration – Does the Expansion of the European Union Represent a Risk Factor?
Authors: Hetzer Wolfgang 
Published: November 2004

AbstractThe imminent entry of ten countries into the European Union is one of the greatest success stories in the contemporary history of the continent. Following the devastation of the Second World War and the political and economic paralysis during the ‘Cold War’ period the future holds promise of development opportunities of historical significance for twenty-five Member States. It must not be overlooked, however, that, due to the still prevalent differences in living standards, in income ratios and in administrative structures, the process of economic approximation is also not without risks. Among these is the tendency towards corruption. The expansion of the European Union can only succeed economically and politically if the dangers associated with corruption are minimized by far-sighted legislation and consistent implementation measures throughout Europe. This is true not only with respect to the new Member States.
Hostile Enterprise Takeovers: Russia's Economy in 1998–2002
Authors: Volkov Vadim 
Published: November 2004

AbstractThe period following the change of presidency in Russia in 1999–2000 featured multiple corporate confl icts and enterprise takeovers. This resulted in the largest redistribution of major assets of the Russian economy after the 1993–1994 privatization. This redistribution was exercised through extensive use of bankruptcy law enforced by state coercive organizations in the interests of powerful corporate raiders and privileged business groups. This article examines the origins, logic, methods, and outcomes of enterprise takeovers in Putin's Russia. It focuses on the uses of legislation and its selective enforcement by the state, which—to date—remains one of the major complications of the transitional period.