bluuebunny/crossref_metadata_2025 huggingface dataset:
KdV ADIABATIC INDEX SOLITONS IN BAROTROPIC OPEN FRW COSMOLOGIES
Authors: ROSU HARET C.
Published: July 2002

Applying standard mathematical methods, it is explicitly shown how the Riccati equation for the Hubble parameter H (η) of barotropic open FRW cosmologies is connected with a Korteweg-de Vries equation for adiabatic index solitons. It is also shown how one can embed a discrete sequence of adiabatic indices of the type [Formula: see text], (γ ≠ 2/3), in the sech FRW adiabatic index soliton.
AN EXACT RG FORMULATION OF QUANTUM GAUGE THEORY
Authors: MORRIS T. R.
Published: July 2002

A gauge invariant Wilsonian effective action is constructed for pure SU(N) Yang-Mills theory by formulating the corresponding flow equation. Manifestly gauge invariant calculations can be performed i.e. without gauge fixing or ghosts. Regularisation is implemented in a novel way which realises a spontaneously broken SU(N|N) supergauge theory. As an example we sketch the computation of the one-loop β function, performed for the first time without any gauge fixing.
HIGGS MASSES AND COUPLING WITHIN AN EXTENSION OF THE MSSM WITH HIGGS TRIPLETS
Authors: FÉLIX-BELTRÁN OLGA
Published: July 2002

We study the properties of the Higgs sector in an extended SUSY model that includes a complex (Y=0) Higgs triplet. In particular, we evaluate the Higgs masses and their couplings to gauge bosons, including the leading radiative corrections using the one-loop effective potential. The mass difference between the CP-even and CP-odd neutral scalars, which can mimic a CP-violating Higgs signature of the MSSM, is also studied. Then, we study the range of parameters that are bounded from the LEP2 search for neutral Higgs bosons, as well as the corresponding region where at least one of the neutral CP-even Higgs boson can be detected at a future e+e- collider with a c.m. energy of 500 GeV.
HEAT KERNEL COEFFICIENTS AND DIVERGENCIES OF THE CASIMIR ENERGY FOR THE DISPERSIVE SPHERE
Authors: BORDAG M. , KIRSTEN K.
Published: July 2002

The first heat kernel coefficients are calculated for a dispersive ball whose permittivity at high frequency differs from unity by inverse powers of the frequency. The corresponding divergent part of the vacuum energy of the electromagnetic field is given and ultraviolet divergencies are seen to be present. Also in a model where the number of atoms is fixed the pressure exhibits infinities. As a consequence, the ground-state energy for a dispersive dielectric ball cannot be interpreted easily.
RADIATION FROM PERFECT MIRRORS FOLLOWING PRESCRIBED RELATIVISTIC TRAJECTORIES
Authors: CALOGERACOS A.
Published: July 2002

The question is examined of a mirror which starts from rest and either (i) accelerates for some time and eventually reverts to motion at constant velocity, (ii) continues accelerating forever. A sharp distinction in made between cases (i) and (ii) concerning the spectrum of the emitted radiation, and the qualitative difference between the two cases is pointed out. The Bogolubov coefficients are calculated for a trajectory of type (i). A type (ii) trajectory is entirely unphysical as far as any realistic mirror is concerned, however it is of interest in that it has been used as a simple analog of black hole collapse. The spectrum emitted for the type (ii) trajectory z = - ln ( cosh t) is examined and it is shown that it is indeed that of a black body. Inconsistencies in previous derivations of the above result are pointed out.
QUANTUM RADIATIVE PROPERTIES OF THE CRYSTAL-LIKE GAS
Authors: LO C. F. , YUNG L. H.
Published: July 2002

In this paper we have examined the quantum properties of the radiance of the crystal-like gas (CLG) in both the Schrödinger picture and Heisenberg picture. We have found that the previous claim of L. M. Duan and G. C. Guo [Quantum Semiclass. Opt.9, 45 (1997)] that the CLG can radiate light with the intensity increasing with time exponentially is in fact erroneous.
THE BENDING INSTABILITY IN THE VORTICITY TRANSPORT THROUGH A TURBULENT FLOW: FEEDBACK CHAOS CONTROLLING AND DYNAMICAL SYMMETRY BREAKING
Authors: VOLCHENKOV D.
Published: July 2002

The model of a large-scale injection into a turbulent flow of immiscible fluid is considered. The long-time, large-scale asymptotic behavior of the energy dissipation rate ∊ is analyzed in the framework of renormalization group approach. It is shown that if the ordinary Kolmogorov dissipation regime (∊= const , in the inertial range) becomes unstable, the alternative asymptotic behavior would come true. In contrast to the standard Navier–Stokes turbulence, the alternative dissipation spectrum ∊(k) has a minimum, which means that an optimal eddy size ℓ exists in the model. This phenomenon provokes the flow into turbulence damping (the "bending effect" in combustion) or stimulates the magnetohydrodynamic system to a generation of a large-scale mean magnetic field ("turbulent dynamo" effect).
ORBITAL EFFECTS IN MANGANITES
Authors: KHOMSKII D. I.
Published: July 2002

In this paper I give a short review of some properties of the colossal magnetoresistance manganites, connected with the orbital degrees of freedom. Ions Mn 3+, present in most of these compounds, have double orbital degeneracy and are strong Jahn–Teller ions, causing structural distortions and orbital ordering. Mechanisms leading to such ordering are shortly discussed, and the role of orbital degrees of freedom in different parts of the phase diagram of manganites is described. Special attention is paid to the properties of low-doped systems (doping 0.1≤x≤0.25), to overdoped systems (x>0.5), and to the possibility of a novel type of orbital ordering in optimally doped ferromagnetic metallic manganites.
LOCAL MOMENT ORDERING IN PERIODIC ANDERSON MODEL
Authors: RAMAKANTH A. , NOLTING W. , REDDY G. G. , MEYER D. , SCHWIEGER S.
Published: July 2002

Strongly correlated electron systems are studied with the help of periodic Anderson model (PAM). The PAM in which highly correlated nondegenerate localized states form a subsystem is considered and the focus of study is on magnetic ordering of electrons in these localized states. In order to study the PAM, which is not amenable to exact solution, two approximate schemes are proposed. The first one is called the spectral density approximation (SDA). Guided by the atomic limit, a two-pole ansatz is made for the localized electron spectral density. The spectral weights and the quasiparticle energies are determined by a moment method. From the spectral density, the spin and energy dependent self-energy is evaluated. A principal limitation of this method is that per ansatz, the quasiparticles are of infinite lifetime. To introduce a finite lifetime, a second approximation scheme is proposed where coherent potential approximation (CPA) is applied to PAM. In order to do CPA, an alloy analogy (AA) is required. In the conventional AA, the concentrations α and the atomic levels E of the fictitious alloy are taken from the atomic limit. Since the interest is in the magnetic properties, this AA is not appropriate. Therefore, a modified AA (MAA) is proposed. In MAA, α and E are obtained using the high energy expansion of the Green's function and the self-energy. In both the approximations, the density of states and the magnetization are selfconsistently evaluated and a phase diagram is obtained. Comparison of the results of the two schemes brings out the effect of quasiparticle damping on the magnetic properties.
EVOLUTION OF FOCK STATES IN THREE MIXED HARMONIC OSCILLATORS: QUANTUM STATISTICS
Authors: EL-ORANY FAISAL A. A. , PEŘINA J. , ABDALLA M. SEBAWE
Published: July 2002

In this communication we investigate the quantum statistics of three harmonic oscillators mutually interacting with each other considering the modes are initially in Fock states. After solving the equations of motion, the squeezing phenomenon, sub-Poissonian statistics and quasiprobability functions are discussed. We demonstrate that the interaction is able to produce squeezing of different types. We show also that certain types of Fock states can evolve in this interaction into thermal state and squeezed thermal state governed by the interaction parameters.
Quasi-Degenerate Self-Trapping and its Application to Anthracene-PMDA: Phenomenon, Optical Absorption and Luminescence Time-Resolved Spectroscopy
Authors: Mishchenko A. S. , Nagaosa N.
Published: July 2002

The self-trapping by the nondiagonal particle-phonon interaction between two quasi-degenerate energy levels of exitonic subsystem, is studied. We propose this is realized in charge transfer exciton, where the directions of the poralization give the quasi-degeneracy, as in quasi-one-dimensional compound A-PMDA. We present a quantitative theory for the optical properties (light absorption and time-resolved luminescence) of the resonating states, which gives a consistent resolution for the long-standing puzzles in A-PMDA.
SPATIAL FLUCTUATIONS OF THE ORDER PARAMETER IN A DISORDERED SUPERCONDUCTOR WITH p-WAVE PAIRING
Authors: LITAK GRZEGORZ
Published: July 2002

The effect of nonmagnetic disorder on the pairing amplitude is studied by means of a perturbation method. Using an extended one band Hubbard model with an intersite attraction we analyze various solutions of p-wave pairing symmetry and discuss their instability calculating fluctuations of order parameter. The model is applied to describe the effect of disorder in Sr2RuO4. The results shows that the real solution with line nodes can be favoured by disorder.
WETTABILITY AND MICROSTRUCTURES OFNi-Al/TiCxSYSTEM
Authors: SHEN DIAN HONG , LU HUA , WU XINGFANG , FROUMIN NATALIA , POLAK MICHA
Published: July 2002

Wettability and microstructures of Ni-Al/TiCxcomposites have been studied by measuring the wettability contact angle using the "sessile drop" method, and by observation using a scanning electron microscope (SEM) and an analytical transmission electron microscope (ATEM), together with an energy dispersive X-ray spectrometer (EDS). The equilibrium contact angle of Ni-Al alloys on TiCx(X = 0.7-1) vs. Ni content showed that the wetting angle depends on the concentration of C in TiCx. The results agreed with the observation of morphology at the interfaces between the hard phase skeleton of TiCx(x = 0.7, 0.9) and metallic phases. The concentration distance plot for Ti , and Ni across the interface of Ni3Al/TiC0.7showed that an extensive area of intermetallic compounds can be observed at the Ni3Al/TiC0.7interface. The microstructure analysis suggested that Ti in TiC0.7is easier to dissolve into the molten alloy than that in TiC0.9. Some periodic zigzag fringes were also observed in the interface between metallic phase and carbides in the sample of Ni3Al/TiC0.7. The formation of this periodic zigzag fringe, which may be a growth zone of a new Ti-Ni-Al phase, would occur during the initial stage of solidification in the samples obtained by infiltration. This behavior in the interface of Ni-Al/TiCxcomposite would affect their strength, creep resistance at elevated temperatures and low-temperature toughness.
MICROSTRUCTURAL CHARACTERIZATIONS OF PLASMA-SPRAYEDZrO2/Al2O3THERMAL BARRIER COATINGS AS RELATED TO OXIDATION BEHAVIOR
Authors: LIMARGA A. M. , WIDJAJA S. , YIP T. H. , TEH L. K.
Published: July 2002

Thermally grown oxide scales can provide high-temperature oxidation protection if they are slow growing, sound and adherent to the substrate. In thermal barrier coatings (TBCs), failure occurs near or at the interface between the metallic bond coat and its thermally grown alumina layer. Oxide scales consisting mainly of alumina were grown on duplex ( ZrO2/bondcoat) and functionally-graded ( ZrO2/ Al2O3/bondcoat) systems through static heat treatment at 1050°C. Electron microscopy was used to analyze the microstructures of oxide layers grown on various TBC systems. Different thickness of grown oxide scales resulting in the systems will be discussed in the light of the effectiveness of alumina interlayer acting as an additional oxidation barrier. Spallation observed at higher temperature for functionally-graded (FG) system is believed to be due to phase transformation of γ-alumina to α-alumina, and hence inducing additional residual stress causing a premature failure. The effect of incorporating alumina in the FG system, in terms of minimizing the thermal residual stress at the interfaces, was evaluated from the standpoint of Finite Element Modeling.
STATISTICAL MECHANICAL FOUNDATION FOR THE TWO-STATE TRANSITION IN PROTEIN FOLDING OF SMALL GLOBULAR PROTEINS
Authors: IGUCHI KAZUMOTO
Published: July 2002

We discuss the statistical mechanical foundation for the two-state transition in the protein folding of small globular proteins. In the standard arguments of protein folding, the statistical search for the ground state is carried out from astronomically many conformations in the configuration space. This leads us to the famous Levinthal's paradox. To resolve the paradox, Gō first postulated that the two-state transition — all-or-none type transition — is very crucial for the protein folding of small globular proteins and used the Gō's lattice model to show the two-state transition nature. Recently, there have been accumulated many experimental results that support the two-state transition for small globular proteins. Stimulated by such recent experiments, Zwanzig has introduced a minimal statistical mechanical model that exhibits the two-state transition. Also, Finkelstein and coworkers have discussed the solution of the paradox by considering the sequential folding of a small globular protein. On the other hand, recently Iguchi have introduced a toy model of protein folding using the Rubik's magic snake model, in which all folded structures are exactly known and mathematically represented in terms of the four types of conformations: cis-, trans-, left and right gauche-configurations between the unit polyhedrons. In this paper, we study the relationship between the Gō's two-state transition, the Zwanzig's statistical mechanics model and the Finkelsteinapos;s sequential folding model by applying them to the Rubik's magic snake models. We show that the foundation of the Gō's two-state transition model relies on the search within the equienergy surface that is labeled by the contact order of the hydrophobic condensation. This idea reproduces the Zwanzig's statistical model as a special case, realizes the Finkelstein's sequential folding model and fits together to understand the nature of the two-state transition of a small globular protein by calculating the physical quantities such as the free energy, the contact order and the specific heat. We point out the similarity between the liquid-gas transition in statistical mechanics and the two-state transition of protein folding. We also study morphology of the Rubik's magic snake models to give a prototype model for understanding the differences between α-helices proteins and β-sheets proteins.
Effects of Quasiparticle Diffusion in Nb-Based Superconducting Tunnel Junctions Under X-Rays Irradiation
Authors: Esposito Emanuela , Frunzio Luigi , Parlato Loredana , Cristiano Roberto , Lisitskii Mikhall , Nappi Ciro , Pagano Sergio , Barone Antonio , Peluso Giuseppe , Pepe Giovanni Piero
Published: July 2002

A novel class of sensors is constituted by radiation detectors based on superconducting tunnel junctions, which could lead in the next future to an advanced instrumentation with an interesting fall out for applications. So far, this area is restricted to LTc superconductors. Among them, niobium has the highest critical temperature and is therefore less demanding in terms of operational temperature. The best performances achieved so far in pure Nb-based junction are far away from the expected theoretical limit. The reason of this discrepancy could be attributed to various problems. Quasiparticle diffusion and edge losses seem to be responsible for the broadening of the signal amplitude spectra so often observed and reported in literature. In this paper we report on efforts to investigate the response to X-Ray of Nb-based superconducting tunnel junctions in terms of a model which includes the quasiparticle diffusion and the edge losses. Our model takes into account the contribution from both the electrodes of the junction and well reproduces the experimental data.
New Barriers for Fast-Switching SNS Josephson Junctions
Authors: Lacquaniti V. , Gonzini S. , Maggi S. , Monticone E. , Steni R. , Andreone D.
Published: July 2002

We report recent results on the development of two different kinds of SNS Josephson junctions which can be used as quantum D/A converters. We have fabricated these devices using as a barrier either a thick 50-100 aluminum layer or a not-stabilized tantalum oxide layer. For both technologies we have determined the dependence of the main electrical properties of the junctions on the fabrication process. Measurements of the rf properties for the Nb/Al/Nb junctions and of the magnetical properties for the Nb/TaO x/ Nb junctions are also reported.
Vibration Suppression by Controlling an MR Damper
Authors: Jeon Doyoung , Park Chanho , Park Kiyang
Published: July 2002

For the semiactive vibration control, a variable damper and proper control systems are essential. In this research a controllable damper was designed using the MR fluids and its mechanical properties such as damping constant and response time were measured.

Since the response time of the MR damper was much longer than nominal MR fluid response time, the time delay of the damper should be considered in the design of controllers. It is shown that the advanced on/off vibration control which includes the damper time delay performs more effectively than the conventional one.
SOME SCALING BEHAVIORS IN A CIRCLE MAP WITH TWO INFLECTION POINTS
Authors: TSENG HSEN-CHE , TAI MON-FU , CHEN HUNG-JUNG , LI PING-CHENG , CHOU CHIEN-HO , HU CHIN-KUN
Published: July 2002

By investigating numerically a circle map with two cubic inflection points, we find that the fractal dimension D of the set of quasiperiodic windings at the onset of chaos has a variety of values, instead of a unique value like 0.87. This fact strongly suggests that a family of universality classes of D appears as the map has two various inflection points. On the other hand, at the quasiperiodic transition with the golden mean winding number, the ratios δn of the width of the mode lockings when going from one Fibonacci level to the next do not converge to a fixed value or a limit cycle in most cases. In this sense, local scaling is broken due to the interaction of the two inflection points of the map. Based on the above observations, it seems that the global scaling is more robust than the local one, at least for the maps we considered.
Superconducting gap in tunneling spectra and pseudogap behavior on high-Tc cuprates
Authors: Oda M. , Dipasupil R. M. , Momono N. , Saigo S. , Nakano T. , Ido M.
Published: July 2002

Superconducting gap magnitude 2Δo is re-examined by STM/STS at T≪Tc is Bi2212. It is confirmed that 2Δo increases monotonically with lowering the doping level p and almost scales with pseudogap temperature T* over the entire p range examined; 2Δo(p)~4.3kBT*(p). Furthermore, it is shown that Tc is almost given by renormalizing 2Δo or T* with p; kBTc(p)∝ pΔo(p) or Tc(p)∝pT*(p).
COLLECTIVE MOTION AND MASS EFFECT IN A SUPERCOOLED LIQUID
Authors: LIU HAO-YANG , ZHANG WEN-BING , ZOU XIAN-WU , JIN ZHUN-ZHI
Published: July 2002

Collective motion and mass effect of atomic diffusion have been studied by molecular dynamics simulation on a ternary system. Small mass effect has been found, which shows about ten particles take part in the collective diffusion in the supercooled liquid.
POOLE-FRENKEL ELECTRICAL CONDUCTION IN SILICON OXYNITRIDE DEPOSITED BY LOW PRESSURE CHEMICAL VAPOUR DEPOSITION
Authors: PONCE-PEDRAZA A. , CARRILLO-LOPEZ J. , MORALES-ACEVEDO A.
Published: July 2002

In this work LPCVD silicon oxynitride films of various compositions between SiO 2 and Si 3 N 4 were deposited by changing the relative ratio (Ro) of nitrous oxide to silane pressures, and the ratio (Rl) of silone to ammonia pressures, while keeping constant the silane pressure. The silicon oxynitride films were deposited at 700°C on p-type silicon substrates (with a carrier concentration of 1015 cm-3), varyng Ro from 0.5 to 2 and Rl from 2.5 to 10. The conduction characteristics of the silicon oxynitride films were studied by using current-voltage and capacitance-voltage measurements of MIS capacitors. Poole-Frenkel thermal emission is shown to be the dominant conduction mechanism in the films. In addition, it is shown that when the nitrous oxide to ammonia ratio increases from 1.25 to 20, i.e., as the oxygen concentration increases in the silicon oxynitride films, there seems to be an increase of charge compensation of the donors in the films.
CdSe CHARACTERIZATION BY ENERGY DISPERSIVE SPECTROSCOPY AND THE PHOTOCONDUCTIVITY TECHNIQUE
Authors: AMADOR-GRAJEDA S. , GOMEZ E. , HERNANDEZ-TORRES M. E. , GRACIA-JIMENEZ J. M. , SILVA-GONZALEZ R.
Published: July 2002

In this work we report results of the characterization of morphology, elemental composition and photoconductivity of an available set of CdSe thin films grown on glass substrates by the chemical bath deposition method.
EPR AND MAGNETIC SUSCEPTIBILITY STUDIES OF CALCIUM-BORATE OXIDE GLASSES CONTAINING IRON IONS
Authors: ARDELEAN I. , PASCUTA P. , PETEANU M.
Published: July 2002

EPR and magnetic susceptibility measurements have been performed on x Fe 2 O 3·(100-x) [3B2O3·CaO] glasses with 0<x≤40 mol%.

The Fe 3+ ions in sites of distorted octahedral symmetry and clustered formations containing both Fe 3+ and Fe 2+ ionic species were found. Dipolar and magnetic super-exchange interactions involving iron ions were revealed to depend on the iron content of the sample.
INFLUENCE OF PRESSURE ON SMECTIC A-NEMATIC PHASE TRANSITION
Authors: MUKHOPADHYAY KISOR , MUKHERJEE PRABIR K.
Published: July 2002

We propose a Landau-de Gennes phenomenological model to describe the pressure induced smectic A-nematic phase transition. The influence of pressure on smectic A-nematic phase transitions are discussed for varying coupling between orientational and translational order parameter with pressure. Increasing the pressure, the first order nematic-smectic A transition becomes second order at a tricritical point which agrees fairly well with available experimental results.
A METHOD FOR INCREASING PRECISION AND RELIABILITY OF ELASTICITY ANALYSIS IN COMPLICATED BURN SCAR CASES
Authors: TSAP LEONID V. , GOLDGOF DMITRY B. , SARKAR SUDEEP , POWERS PAULINE S.
Published: July 2002

In this paper we propose a method for increasing precision and reliability of elasticity analysis in complicated burn scar cases. The need for a technique that would help physicians by objectively assessing elastic properties of scars, motivated our original algorithm. This algorithm successfully employed active contours for tracking and finite element models for strain analysis. However, the previous approach considered only one normal area and one abnormal area within the region of interest, and scar shapes which were somewhat simplified. Most burn scars have rather complicated shapes and may include multiple regions with different elastic properties. Hence, we need a method capable of adequately addressing these characteristics. The new method can split the region into more than two localities with different material properties, select and quantify abnormal areas, and apply different forces if it is necessary for a better shape description of the scar. The method also demonstrates the application of scale and mesh refinement techniques in this important domain. It is accomplished by increasing the number of Finite Element Method (FEM) areas as well as the number of elements within the area.

The method is successfully applied to elastic materials and real burn scar cases. We demonstrate all of the proposed techniques and investigate the behavior of elasticity function in a 3-D space. Recovered properties of elastic materials are compared with those obtained by a conventional mechanics-based approach. Scar ratings achieved with the method are correlated against the judgments of physicians.
TOWARDS UNRESTRICTED LIP READING
Authors: MEIER UWE , STIEFELHAGEN RAINER , YANG JIE , WAIBEL ALEX
Published: July 2002

Lip reading provides useful information in speech perception and language understanding, especially when the auditory speech is degraded. However, many current automatic lip reading systems impose some restrictions on users. In this paper, we present our research efforts in the Interactive System Laboratory, towards unrestricted lip reading. We first introduce a top–down approach to automatically track and extract lip regions. This technique makes it possible to acquire visual information in real-time without limiting the user's freedom of movement. We then discuss normalization algorithms to preprocess images for different lightning conditions (global illumination and side illumination). We also compare different visual preprocessing methods such as raw image, Linear Discriminant Analysis (LDA), and Principle Component Analysis (PCA). We demonstrate the feasibility of the proposed methods by the development of a modular system for flexible human–computer interaction via both visual and acoustic speech. The system is based on an extension of the existing state-of-the-art speech recognition system, a modular Multiple State–Time Delayed Neural Network (MS–TDNN) system. We have developed adaptive combination methods at several different levels of the recognition network. The system can automatically track a speaker and extract his/her lip region in real-time. The system has been evaluated under different noisy conditions such as white noise, music, and mechanical noise. The experimental results indicate that the system can achieve up to 55% error reduction using visual information in addition to the acoustic signal.
BIFURCATION OF EQUILIBRIA IN MICROMACHINED ELASTIC STRUCTURES WITH ELECTROSTATIC ACTUATION
Authors: WANG P. K. C.
Published: July 2002

The determination of critical actuator voltages for the onset of "pull-in" or buckling of micromachined elastic structures or microelectromechanical systems (MEMS) with a finite number of electrostatic actuators is posed as a multiparameter bifurcation problem associated with a nonlinear partial differential equation. By making suitable approximations, the problem is reduced to one involving a multiparameter family of mappings on a bounded subset of a finite-dimensional Euclidean space RP into itself. Then the problem is reposed as one involving the intersection of level sets of certain functions whose levels correspond to the variable parameters (squares of actuator voltages). A sufficient condition for fold bifurcation when the actuator voltages exceed certain critical values is deduced using simple geometric arguments. The paper concludes with a discussion on the bifurcation of equilibrium of such systems for the limiting case where the number of actuators tends to infinity.
ACTIVE–PASSIVE DECOMPOSITION WITH APPLICATION TO ARRAYS OF CHAOTIC SYSTEMS
Authors: VEPA RANJAN
Published: July 2002

In this paper an alternate method of Active–Passive Decomposition of chaotic systems based on the notion of passivity is presented. The concepts of model following in control theory are applied to show how such a decomposition is useful in achieving synchronization. Besides the fact that model following control may be implemented in a whole class of systems, it is also the basis for designing adaptive systems where the convergence of the scheme is often proved by the use of passivity concepts.

The method is shown to be extremely useful in synchronizing passively coupled chaotic systems in general and arrays of coupled but identical controlled chaotic systems in particular.
NOISE-ENHANCED PROPAGATION IN A DISSIPATIVE CHAIN OF TRIGGERS
Authors: MORFU S. , COMTE J. C. , BILBAULT J. M. , MARQUIÉ P.
Published: July 2002

We study the influence of spatiotemporal noise on the propagation of square waves in an electrical dissipative chain of triggers. By numerical simulation, we show that noise plays an active role in improving signal transmission. Using the Signal to Noise Ratio at each cell, we estimate the propagation length. It appears that there is an optimum amount of noise that maximizes this length. This specific case of stochastic resonance shows that noise enhances propagation.
ON HAUSDORFF MEASURES AND SBR MEASURES FOR PARABOLIC RATIONAL MAPS
Authors: DENKER M. , ROHDE S.
Published: July 2002

If J is the Julia set of a parabolic rational map having Hausdorff dimension h<1, we show that Sullivan's h-conformal measure on J is either absolutely continuous or orthogonal with respect to the Hausdorff measures defined by the function [Formula: see text], according to whether τ>τ0 or τ<τ0 for some explicitly computable τ0>0.
NUMERICAL PASSAGE FROM RADIATIVE HEAT TRANSFER TO NONLINEAR DIFFUSION MODELS
Authors: KLAR A. , SCHMEISER C.
Published: July 2002

Radiative heat transfer equations including heat conduction are considered in the small mean free path limit. Rigorous results on the asymptotic procedure leading to the equilibrium diffusion equation for the temperature are given. Moreover, the nonlinear Milne problem describing the boundary layer is investigated and an existence result is proven. An asymptotic preserving scheme for the radiative transfer equations with the diffusion scaling is developed. The scheme is based on the asymptotic analysis. It works uniformly for all ranges of mean free paths. Numerical results for different physical situations are presented.
THIN LAYERS IN MICROMAGNETISM
Authors: CARBOU G.
Published: July 2002

In this paper we study the solutions of micromagnetism equation in thin domain both in the stationary and in the time-dependent case. We prove that the magnetic field induced by the magnetisation behaves like the projection of the magnetic moment on the normal to the domain, both for a flat and a non-flat domain.
THE STATE OF THE ART IN ADAPTIVE INFORMATION AGENTS
Authors: LAU RAYMOND Y. K.
Published: July 2002

With the exponential growth of the Internet, information seekers are faced with the so-called problem of information overload. Adaptive Information Agents have been developed to alleviate this problem. The Main issues in the development of these agents are document representation, learning, and classification. Various paradigms have been explored for the development of adaptive information agents, and the performance of these agents differs in terms of computational efficiency, classification effectiveness, learning autonomy, exploration capability, and explanatory power. To develop a basic under-standing of the pros and cons of these paradigms, some representative information agents are examined. Such a review also serves to identify a general for the development of the next generation adaptive information agents.
EFFECT OF MAGNETIC FIELD ON THE PHASE TRANSITION FROM NUCLEAR MATTER TO QUARK MATTER DURING PROTO-NEUTRON STAR EVOLUTION
Authors: GUPTA V. K. , GUPTA ASHA , SINGH S. , ANAND J. D.
Published: July 2002

We have studied phase transition from hadron matter to quark matter in the presence of high magnetic fields incorporating the trapped electron neutrinos at finite temperatures. We have used the density dependent quark mass (DDQM) model for the quark phase while the hadron phase is treated in the frame-work of relativistic mean field theory. It is seen that the energy density in the hadron phase at phase transition decreases with both magnetic field and temperature.
SAMPLE INCOMPLETENESS IN THE STUDY OF THE QUASAR-GALAXY ASSOCIATIONS AS A RESULT OF GRAVITATIONAL LENSING
Authors: ZHU ZONG-HONG , WU XIANG-PING
Published: July 2002

For decades, the angular associations between faint galaxies and high redshift quasars have remained to be a well-known puzzle, which is often cited as an evidence for the noncosmological origin of quasar redshifts. This happens because the attempt at interpreting the phenomenon as being due to gravitational lensing fails in producing the reported high amplitude of the quasar-galaxy associations unless some unconventional hypotheses are made such as an extremely large velocity dispersion for galaxies, a serious contamination of the overall quasar number counts or a strong matter clustering on galaxy scale. While there are good reasons to believe that the magnification bias should be a natural cause for the quasar-galaxy associations, we re-address the question by taking into account an important factor that has been overlooked in previous studies: The expected amplitude of the association in the framework of gravitational lensing depends sensitively on the quasar limiting magnitude, whereas none of the quasar samples in the measurements is actually complete. Taking this correction into account our predictions of the galaxy enhancement factors based on a simple lensing model are essentially consistent with observations, thus providing a helpful clue to eventually resolving the longstanding puzzle in astrophysics.
APPLICATIONS OF THE MODAL SUMMATION TECHNIQUE TO THE THEORETICAL SITE RESPONSE ESTIMATION
Authors: ROMANELLI F. , VACCARI F. , PANZA G. F.
Published: July 2002

A practical definition of site effect, that accounts for both the seismological and engineering point of view, is the one given by Field7: "the unique behavior of a site, relative to other sites, that persists given all (or most) of the potential sources of earthquake ground motion in the region". This definition implicitly indicates the difficulties connected with a correct estimate (or prediction) of the site effect. We estimate theoretical site responses adopting several techniques and using different seismic motion types. Our results confirm that the identification of the site behavior with a set of resonance frequencies can be a very difficult task, especially when the amplification levels seem to be "azimuthally" dependent. We show that the adoption of simplified models can lead to misleading conclusions concerning the seismic response of sedimentary basins. The results suggest that, in order to perform an accurate estimate of the site effects in complicated geometries, it is necessary to make a parametric study that takes into account the complex combination of the source and propagation factors.
ANGULAR RESOLVED X-RAY ABSORPTION NEAR EDGE STRUCTURE INVESTIGATION OF ADSORBED ALKANETHIOL MONOLAYERS ON III–V(110) SURFACES
Authors: CHASSÉ T. , ZERULLA D. , HALLMEIER K. H.
Published: July 2002

The structure of alkanethiol monolayers on III-V(110) surfaces was studied by analyzing the X-ray absorption near edge structure (XANES) of the carbon K edge. Pronounced absorption maxima were observed for special orientations of the polarization vector of the radiation as revealed from angular-dependent measurements, suggesting a rather well-defined molecular axis of the alkyl chains. From quantitative evaluations of these angular dependences the chains were found to be tilted from the normal towards the [001] direction of the (110) surfaces by 34° and 15° in the case of hexadecanethiol (HDT) adsorption on InP and GaP, respectively. The similarities as well as the differences in tilt angles between the substrates are dicussed in terms of constraints imposed by the surface structure and lattice constants as well as the space requirements of the van der Waals spheres of the adsorbed thiols. A unique feature observed on these monolayers is the nearly complete alignment of the alkyl chains with respect to the azimuthal orientation. We suggest that this adsorbate system represents the case of a single domain orientation within the organic monolayer.
PREVENTION OF THE PARROT BEAK DEFORMITY IN FINGERTIP INJURIES
Authors: Pandya Ankur N. , Giele Henk Peter
Published: July 2002

The nail is supported by the dorsal tuft of the terminal phalanx. Following distal fingertip trauma, varying amounts of nail support may be lost resulting in the nail curving palmarwards. This curvature is dependent upon the degree of bony loss, the amount of remaining nail bed and the degree of scar contracture at the hyponychial-pulp interface. The parrot beak or hooked nail deformity is most commonly caused by tight closure of a fingertip amputation and excessive palmar tension at the hyponychial-pulp suture line. A simple technique using a hypodermic needle, that eliminates tension from the suture line at the fingertip pulp-hyponychial interface and prevents hooked nail deformity is described. This allows healing to take place without any palmarwards pull of the scar and a subsequent parrot beak deformity.
COMMINUTED INTRA-ARTICULAR FRACTURE OF THE DISTAL RADIUS — THE TECHNIQUE OF OPEN REDUCTION AND INTERNAL FIXATION WITH PLATING
Authors: Chow S. P. , Ip W. Y. , Poon T. L.
Published: July 2002

The technical details of open reduction and internal fixation with double plating for a patient with comminuted intra-articular fractures of the distal radius were described. The vital steps included the exposure, initial dorsal reduction, ventral reduction and fixation, checking of reduction, return to dorsal surface with final reduction and X-ray check, and wound closure. Special attention and other technical tips were also highlighted, and hopefully will shorten the learning curve of others who would like to use this rather demanding technique for their patients.
AN EXTENSIBLE BUSINESS COMMUNICATION LANGUAGE
Authors: WEIGAND HANS , HASSELBRING WILHELM
Published: July 2002

A main problem for electronic commerce, particularly for business-to-business applications, lies in the need for the involved information systems to meaningfully exchange information. Domain-specific standards may be used to define the semantics of common terms. However, in practice it is not easy to find those domain-specific standards that are detailed and stable enough to allow for real interoperability. Therefore, we propose an architecture that allows for incremental construction of a shared repository including a multilingual thesaurus, which is used in a business communication language. Communicating information systems then refer to the common thesaurus while exchanging messages. Our emphasis is be on separating semantics (in the thesaurus) and syntax (in XML). Therefore, our extensibility is not only that of XML, but also the extensibility of the semantics that is modeled in the shared repository. The business communication language XLBC is presented and how it can be used in electronic commerce applications. XLBC message patterns and conversation protocols are stored in the shared repository as well.
BREAK-DOWN OF SCALING AND CONVERGENCE TO GAUSSIAN DISTRIBUTION IN STOCK MARKET DATA
Authors: KULLMANN L. , KERTÉSZ J. , TÖYLI J. , KASKI K. , KANTO A.
Published: July 2002

We analyze the Standard and Poor's 500 index data of the New York Stock Exchange for more than 32 years. It was suggested earlier that the high frequency data are well described by a truncated Lévy distribution and scaling with respect to the sampling time differences was found. The truncated character of the distribution implies that scaling must break down and that the distribution ultimately converges to a Gaussian. We show by comparing Lévy and Gaussian fits that the characteristic time of the break-down of scaling is of the order of few days. The analysis of the dependence of the kurtosis on the time differences shows that this is much shorter than the time needed for the convergence to the Gaussian being of the order of months.
TRADER DYNAMICS IN A MODEL MARKET
Authors: JOHNSON NEIL F. , HART MICHAEL , HUI PAK MING , ZHENG DAFANG
Published: July 2002

We explore various extensions of Challet and Zhang's Minority Game in an attempt to gain insight into the dynamics underlying financial markets. First we consider a heterogeneous population where individual traders employ differing "time horizons" when making predictions based on historical data. The resulting average winnings per trader is a highly non-linear function of the population's composition. Second, we introduce a threshold confidence level among traders below which they will not trade. This can give rise to large fluctuations in the "volume" of market participants and the resulting market "price".
RENORMALIZATION OF BLACK-SCHOLES EQUATION FOR STOCHASTICALLY FLUCTUATING INTEREST RATE
Authors: MUSLIMOV ALEXANDER G. , SILANT'EV NIKOLAI A.
Published: July 2002

We investigate the effect of stochastic fluctuations of an interest rate on the value of a derivative. We derive the modified Black-Scholes equation that describes evolution of the value of a derivative averaged over an ensemble of stochastic fluctuations of the rate of interest and depends on the "renormalized" values of volatility and rate of interest. We present the explicit expressions for the renormalized volatility and interest rate that incorporate the corrections owing to the short-term stochastic variations of the interest rate. The stochastic component of the interest rate tends to enhance the effective volatility and reduce the effective interest rate that determine an evolution of the option pricing "smoothed out" over the stochastic variations. The results of numerical solution of the modified Black-Scholes equation with the renormalized coefficients are illustrated for an American put option on non-dividend-paying stock.
DECOMPOSITION OF THE VERTEX OPERATOR ALGEBRA $V_{\sqrt{2}D_l}$
Authors: DONG CHONGYING , LAM CHING HUNG , YAMADA HIROMICHI
Published: July 2002

We determine the decomposition of [Formula: see text] into a sum of irreducible T-modules for general l where Dl is the root lattice of type Dl and T is the tensor product of l+1 Virasoro vertex operator algebras with central charges c1=1/2, c2=7/10, c3=4/5, and ci=1 for 4≤i≤l+1.
POSITIVE SOLUTIONS FOR ELLIPTIC SYSTEMS WITHOUT VARIATIONAL STRUCTURE
Authors: LASSOUED LOTFI
Published: July 2002

This paper is concerned mainly with the existence of bounded solutions for the system [Formula: see text] where Ω is a bounded domain in ℛn. In the case n≥3, assuming each fiis a nonnegative C1function which is nondecreasing in each variable, we prove the existence of a bounded solution for the system under appropriate smallness condition in [Formula: see text] for each Vi. For n=2 two conditions which involve weaker norms, namely the Hardy space norm and the L1-norm, that ensure existence of a bounded solution. In addition, some generalizations for more general elliptic operators are considered and the existence of positive entire solutions is also investigated.
REFLECTION PRINCIPLE AND J-COMPLEX CURVES WITH BOUNDARY ON TOTALLY REAL IMMERSIONS
Authors: IVASHKOVICH S. , SHEVCHISHIN V.
Published: July 2002

We prove a version of the reflection principle for pseudoholomorphic disks with boundary on totally real submanifolds in almost-complex manifolds. Furthermore, we give a proof of the Gromov compactness theorem for pseudoholomorphic curves with boundary on immersed totally real submanifolds. As a corollary we show that a complex disk can be attached to any immersed Lagrangian submanifold with only transversal double points in a complex linear space.
A lower bound for integer greatest common divisor computations
Authors: Mansour Yishay , Schieber Baruch , Tiwari Prasoon
Published: July 2002

It is proved that no finite computation tree with operations { +, -, *, /, mod, < } can decide whether the greatest common divisor (gcd) of
a
and
b
is one, for all pairs of integers
a
and
b
. This settles a problem posed by Gro¨tschel et al. Moreover, if the constants explicitly involved in any operation performed in the tree are restricted to be “0” and “1” (and any other constant must be computed), then we prove an Ω(log log
n
) lower bound on the depth of any computation tree with operations { +, -, *, /, mod, < } that decides whether the gcd of
a
and
b
is one, for all pairs of
n
-bit integers
a
and
b
.

A novel technique for handling the truncation operation is implicit in the proof of this lower bound. In a companion paper, other lower bounds for a large class of problems are proved using a similar technique.
Collaborative efforts
Authors: Neumann Peter G.
Published: July 2002

This issue of
Communications
focuses on social and organizational influences governing collaborative uses of computers and communications. Here we review some of those influences from the perspectives of the risks involved.
Constant-time maintainability
Authors: Wang Ke , Graham Marc H.
Published: July 2002

The
maintenance problem
of a database scheme is the following decision problem: Given a consistent database state ρ and a new tuple
u
over some relation scheme of ρ, is the modified state ρ ∪ {
u
} still consistent? A database scheme is said to be
constant-time-maintainable(ctm)
if there exists an algorithm that solves its maintenance problem by making a fixed number of tuple retrievals. We present a practically useful algorithm, called the
canonical maintenance algorithm
, that solves the maintenance problem of all ctm database schemes within a "not too large" bound. A number of interesting properties are shown for ctm database schemes, among them that non-ctm database schemes are not maintainable in less than a linear time in the state size. A test method is given when only cover embedded functional dependencies (fds) appear. When the given dependencies consist of fds and the join dependency (jd) ⋈
R
of the database scheme, testing whether a database scheme is ctm is reduced to the case of cover embedded fds. When dependency-preserving database schemes with only equality-generating dependencies (egds) are considered, it is shown that every ctm database scheme has a set of dependencies that is equivalent to a set of embedded fds, and thus, our test method for the case of embedded fds can be applied. In particular, this includes the important case of lossless database schemes with only egds.
An evaluation of the Chandy-Misra-Bryant algorithm for digital logic simulation
Authors: Soulé Larry , Gupta Anoop
Published: July 2002

We explore the suitability of the Chandy-Misra-Bryant (CMB) algorithm for the domain of digital logic simulation. Our evaluation is based on results for six realistic benchmark circuits, one of them being the R6000 microprocessor form MIPS. A quantitative evaluation of the concurrency exhibited by the CMB algorithm shows that an average of 42-196 element activations can be evaluated in parallel if arbitrarily many processors are available. One major factor limiting the parallel performance is the large number of deadlocks that occur. We present a classification of the types of deadlocks and describe them in terms of circuit structure. Using domain-specific knowledge, we propose and evaluate several methods for both reducing the number of deadlock occurences and for reducing the time spent on each occurence. Running on a 16-processor Encore Multimax we observe speedups of 6-9. While these self-relative speedups are larger than a parallel version of the traditional centralized-time event-driven algorithm, they come at the price of large overheads: significantly more complex element evaluations, extra element evaluations, and deadlock resolution time. These overheads overwhelm the advantages of using distributed time and consistently make the parallel performance of the CMB algorithm about three times slower than that of the traditional parallel event-driven algorithm. Our experience leads us to conclude that the distributed-time CMB algorithm does not present a viable alternative to the centralized-time event-driven algorithm in the domain of parallel digital logic simulation.