bluuebunny/crossref_metadata_2025 huggingface dataset:
SYNTHESIS AND CHARACTERIZATION OF Cd1-xZnxS:Cu CRYSTALS BY CO-PRECIPITATION METHOD
Authors: NAYEEM ABDUL , YADAIAH K. , VAJRALINGAM G. , MAHESH P. , NAGABHOOSHANAM M.
Published: July 2002

Copper doped Cd 1-x Zn x S compounds were prepared by controlled precipitation method with 0≤x≤1. The samples were characterized by X-ray, chemical analysis, optical absorption, and SEM studies. The X-ray studies have indicated that the compounds have polycrystalline nature with mixed Hexagonal and Cubic structure of CdS with x=0–0.6, the structure changed to a prominent cubic structure of ZnS with x>0.6. Optical studies have shown that the grain size increased with x varying from 0–0.2 and then it decreased. It was also observed that the optical energy gap decreased with x till x ⋍ 0.2, attained a minimum with x=0.2 and then it increased gradually. The values of E g obtained for CdS and ZnS were 2.21 eV and 2.53 eV. The chemical homogeneity of the samples was also observed from the EDAX and noted that the sulfur and copper contents remained almost the same, and the decrease in Cd and increase in Zn atoms occurred systematically. The results were explained on the basis of different phases formed and the role of copper impurity.
EFFECT OF ELECTRON CORRELATION ON THE TWO-PARTICLE DYNAMICS OF A HELIUM ATOM IN A STRONG LASER PULSE
Authors: DAHLEN NILS ERIK
Published: July 2002

This review discusses the complicated two-electron dynamics of a helium atom in an intense, short laser pulse. A helium gas in femtosecond laser pulses at long wave lengths (λ~700 nm) and high intensities (I~1015 W /cm2) produces surprisingly high numbers of He2+ ions. These laser fields cause large and fast electron oscillations, which makes a solution of the time-dependent Schrödinger equation numerically demanding. The system can be studied using a one-dimensional model atom, which has many of the same properties as the He atom. Using the one-dimensional model, the importance of including electron correlation in a simplified description of the two-electron dynamics is demonstrated. It is shown that electron correlation becomes much less important if the laser field has a short wave length, in which case the electron oscillations are smaller and slower. The problem of including electron correlation in the calculations is discussed in terms of approaches such as time-dependent Hartree–Fock, time-dependent density functional theory and time-dependent extended Hartree–Fock. Some of the commonly used semi-classical models for describing the double-ionization process are presented.
EXPERIMENTAL DEMONSTRATION OF FRACTAL SHAPE TRANSITION AND FRACTAL SIZE IN Ge CLUSTERS FORMATION
Authors: CHEN ZHIWEN , TAN SHUN , ZHANG SHUYUAN , HOU JIANGUO
Published: July 2002

The nucleation and growth of Ge fractal clusters in Au/Ge bilayer films have been investigated by transmission electron microscope (TEM). It is found that the fractal crystallization, the fractal shape transition, and the fractal size strongly depend on the annealing time and the films thickness ratio. The fractal formation can be explained by a random successive nucleation and growth (RSNG) model. The fractal shape transition and fractal size may be determined by the relative ration between the propagation rate of RSN process and the grain growth rate.
OPTICAL ABSORPTION IN QUANTUM DOTS
Authors: KRISHNA PHANI MURALI , MUKHOPADHYAY SOMA , CHATTERJEE ASHOK
Published: July 2002

The optical absorption behaviour of polar semiconductor quantum dots has been investigated in the strong confinement regime using the adiabatic approximation of Landau and Pekar. It has been shown that optical absorption coefficient becomes strongly size dependent below a certain value of the confinement length and also exhibits interesting crossing behaviour when studied as a function of the electron–phonon coupling constant for different values of the confinement length. It has furthermore been shown that the ratio of the one-phonon part of the oscillator strength to the zero-phonon contribution can be significantly large in a small quantum dot and can also exhibit an interesting minimum structure at certain value of the confinement length for intermediate electron–phonon coupling.
CHARGE ORDER TRANSITION IN LiMn2O4
Authors: PAOLONE A. , CANTELLI R. , ROUSSE G. , MASQUELIER C. , FERRETTI M.
Published: July 2002

Stoichiometric LiMn2O4 undergoes a structural phase transition around room temperature from cubic to orthorhombic, induced by a partial charge ordering on the manganese sites, similar to the Verwey transition occurring in Fe3O4 . We studied the charge ordering transition of LiMn2O4 by means of anelastic spectroscopy, measuring the Young's modulus, E, and the elastic energy loss function, Q-1. Our measurements confirm the occurrence of a phase transition at 292 K on cooling, showing a large hysteresis on heating. The anelastic spectroscopy results also indicate that the transformation is characterised by the coexistence of two phases. In addition, the Young's modulus reveals presence of an additional anomaly, on cooling, around the onset of the phase transformation.
Sub-Micron Normal-Insulator-Superconductor Tunnel Junctions for Sensitive Thermometry and Micro-Refrigerators
Authors: Arena G. , Castellano M. G. , Leoni R. , Torrioli G. , Carelli P.
Published: July 2002

We report on measurements of normal-insulator-superconductor tunnel junctions at temperatures below 1K. The junctions have been fabricated by shadow mask technique and e-beam lithography and have submicron dimensions. The measurements on our junctions show that their characteristics are very sensitive to temperature changes making them suitable to be used as a sensitive secondary thermometer. To demonstrate this we use this tunnel structure for sensing the electron temperature drop in a copper strip of an electronic micro-refrigerator, that was made by arrays of tunnel junctions, as well.
Structural Applied Field-Induced Metastability of the Compositions Based on Polyvinyl Alcohol, Orthophosphoric Acid, and Variable-Valence Metals
Authors: Lazareva T. G. , Yakovleva O. V. , Prodan S. A. , Il'Yushenko I. A. , Gayduk J. S.
Published: July 2002

The conditions of formation of the hybrid-organic complexes based on polyvinyl alcohol, variable-valence metals, and orthophosphoric acid (PVA - H 3 PO 4, PVA - Cu 2+, PVA - Co 2+, PVA - Cu 2+ - H 3 PO 4, PVA - Co 2+ - H 3 PO 4) sensitive to electric and magnetic fields are determined by the rheological method with regard for electrophysical properties. Evaluation is made of an influence of the type and concentration of the used components on the properties and structure of the complexes. An influence of a magnetic field on rheological properties of the compositions is determined, the flow curves, concentration and temperature dependences of viscosity are obtained. Some structural features of the PVA - Cu 2+ - H 3 PO 4 films are specified by the dielectric relaxation method and a change in electric, sorption properties in the presence of a d.c. electric field is determined. The optimal fluid and film compositions sensitive to external factors are found. An assumption is made that the metastability induced by the applied field is associated with the formation of a liquid-crystalline phase.
DIFFERENT FACETS OF CHAOS IN QUANTUM MECHANICS
Authors: MANFREDI V. R. , SALASNICH L.
Published: July 2002

Nowadays there is no universally accepted definition of quantum chaos. In this paper we review and critically discuss different approaches to the subject, such as Quantum Chaology and the Random Matrix Theory. Then we analyze the problem of dynamical chaos and the time scales associated with chaos suppression in quantum mechanics.
QUANTUM-WELL EXCITONIC EFFECTS IN FABRY-PEROT FILMS AND MICROCAVITIES: RESONANT ELASTIC SCATTERING OF LIGHT DUE TO INTERFACE ROUGHNESS
Authors: KOSOBUKIN V. A. , SEL'KIN A. V.
Published: July 2002

Within a proposed model of quasi-two-dimensional excitons in a quantunl well (QW) a correlation theory has been developed for resonant elastic scattering of light from excitonic polarization fluctuations induced by randomly rough interfaces. For a single QW placed in a Fabry-Perot many-layer dielectric environment, intensity of the exciton-mediated elastic scattering of light is shown to be two orders of magnitude larger than that of the nonresonant scattering. The resonant excitonic contribution is concluded to be measurable even for a single QW whose interface r.m.s. roughness height is comparable to atomic monolayer thickness.
CRITICAL BEHAVIOR OF A TWO-DIMENSIONAL DILUTE BOSE GAS
Authors: CRISAN M. , TIFREA I. , BODEA D. , GROSU I.
Published: July 2002

We applied the Renormalization Group method at finite temperature to reconsider the two-dimensional dilute Bose gas. The general flow equations are obtained for the case of arbitrary dimensions, and by considering the two-dimensional limit, we estimate the value of the critical temperature, coherence length and specific heat. The value of the critical temperature is in agreement with previous calculations performed using the t-matrix method. The coherence length and the specific heat present a non-universal behavior, a logarithmic temperature dependence in the critical region being identified.
FABRICATION AND CHARACTERISTICS OF ALN NANOWIRES
Authors: CHEN H. , LU X. K. , ZHOU S. Q. , HAO X. H. , WANG Z. X.
Published: July 2002

Single phase AlN nanowires are fabricated by a sublimation method. They were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), typical selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The SEM and TEM images show that most of the nanowires have diameters of about 10–60 nm. The crystal structure of AlN nanowires revealed by XRD, SAED and HRTEM shows the AlN nanowires have a wurtzite structure.
LANDAU-DE GENNES THEORY OF ELECTRONIC LIQUID-CRYSTAL PHASES IN CUPRATES
Authors: CHEN ZENG-BING
Published: July 2002

Based on the Landau theory of striped phases in cuprates proposed recently, we present the Landau-de Gennes theory of coupled charge-density-wave and spin-density-wave order parameters in the presence of the electronic liquid-crystal orders in cuprates. Various electronic liquid-crystal orders of striped cuprates are considered by using the Toner–Nelson formulation for two-dimensional classical liquid-crystal orders. Some related issues are briefly discussed.
Topological Aspects of Quasiparticles in Solid
Authors: Goswami Gautam
Published: July 2002

Particle-quasiparticle analogy is studied here from a geometrical formulation. Since a crystal can, in general be considered to correspond to an anisotropic feature of space-time in vacuum, the quasiparticle in solid can be treated as particles in an anisotropic space. It is pointed out that the low energy excitation can be visualized through the change in chirality of fermions in such a space. The topological aspects are studied through a gauge theoretical formulation of lattice fermions. It is also argued that the mass generation of quasiparticles has topological origin.
Impedance Analysis of Layer Structured NBT–CBT Mixed Ceramics
Authors: Sastry P. S. Rama , Bhimasankaram T. , Kumar G. S. , Prasad G.
Published: July 2002

Complex impedance spectra of ferroelectric mixed ceramic system ( Na 0.5 Bi 0.5)1-x Ca x Bi 4 Ti 4 O 15 with x=0, 0.1, 0.3, 0.5, 0.7 and 1 was studied as a function of frequency and temperature in the range 1 KHz to 10 MHz and 30°C to 620°C respectively. Equivalent circuits involving resistive and capacitive elements at different temperatures, activation energies of relaxations and conduction were evaluated using impedance plots. A comparative study of impedance and conductivity facilities an insight in understanding the electrical nature of these electroceramics.
AN ELEMENTARY UNAMBIGUOUS, COMPLETE RENORMALIZATION PROCEDURE IN NONRELATIVISTIC QUANTUM ELECTRODYNAMICS
Authors: SEKE JOSIP
Published: July 2002

A new unambiguous, complete renormalization procedure is presented. Without introducing any energy (or mass) counter terms, by using the elementary time-dependent perturbation theory, it is shown that the renormalization procedure is equivalent to the identification and removement of those terms which stem from the experimentally unobservable free-electron–vacuum-field interaction.
APPLICATION OF ESR TO HIGH-TC SUPERCONDUCTORS AND RELATED MATERIALS V: A NEW METHOD OF MAKING YBa2Cu3Oζ AND ITS SUPERCONDUCTIVE CHARACTERISTICS
Authors: SUGAWARA K. , YAMAMOTO K. , ARAI N. , HOTTA K. , HIROSE H.
Published: July 2002

A new method of making superconductor of YBa 2 Cu 3 O ζ was developed. The fundamental technology of the method is to take advantage of Ba-diffusion into YCu 3 alloy. Two kinds of samples of the YBa 2 Cu 3 O ζ system were prepared, and their superconductivity was confirmed by non-resonant microwave absorption and the Meissner effect. In the first kind, the thin alloy of YCu 3 and BaCO 3 (powder) were pressed into pellet, and sintered in air at 900°C for 24 hours. In the second kind, a rod of YCu 3 alloy was imbedded in a matrix of BaCO 3 powder, and they were calcined at 900°C for 24 hours in air. Both samples were confirmed to be superconductors of about T c ≃90 K.
HYSTERESIS STUDIES IN COUPLED MAP LATTICES
Authors: RAI RENUKA , SINGH HARJINDER
Published: July 2002

We have studied hysteresis phenomenon in spatially extended systems and investigated the effect of additive and parametric noises. We observe that the behavior of hysteresis loop area as a function of coupling strength is different for additive and parametric noises. It is interesting to observe that behavior of hysteresis loop area is analogous to the behavior of the signal-to-noise ratio [Phys. Rev.E56, 2518 (1997)].
A NEW METHOD FOR EXTRACTING PRIMITIVES OF REGULAR TEXTURES BASED ON WAVELET TRANSFORM
Authors: LEE KUEN-LONG , CHEN LING-HWEI
Published: July 2002

In this paper, a new method for extracting primitives of a regular texture via wavelet transform is provided. Each primitive is restricted to be a parallelogram. The main work of the proposed method is to extract the two displacement vectors that form the primitive of a regular texture. A contrast-based criterion is used to select appropriate subimages obtained from wavelet transform for detecting displacement vectors. An edge thresholding method is then performed on the subimages selected to locate edges. Based on these edges, Hough transform is applied to extract the displacement vectors. The proposed method is quite efficient and can get more accurate results for displacement vectors when comparing to traditional co-occurrence matrix based methods. Synthesized textures are provided to show the effectiveness of the proposed method.
CHAOTIC SCATTERING IN A SYSTEM OF THREE INVERSE SQUARE LAW REPULSIVE POTENTIALS
Authors: BLACKBURN JAMES A. , SMITH H. J. T.
Published: July 2002

This report deals with particle trajectories within a system of three potentials that induce inverse square law forces. The "soft" collisions with the scattering centers together with the ensuing chaotic dynamics may be viewed as a generalization of the more familiar chaotic scattering from configurations of hard disks. Two modes are considered: external injection into the scattering system, and internal release within the inter-potential region. In addition to extensive numerical simulations, an experiment is described in which a small permanent magnet is scattered by a system of three fixed magnets. Chaotic regions, marked by anomalously long escape times, are observed for some release coordinates of the moving magnet.
REPLICATION PROPERTIES OF PARITY CELLULAR AUTOMATA
Authors: JULIÁN PEDRO , CHUA LEON O.
Published: July 2002

In this paper we analyze the replication properties of additive or parity Cellular Automata (CA). The objective of the paper is twofold. Firstly, to review and extend the existing results in the cases of one- and two-dimensional CA. Secondly, to report a general result that states the replication properties of an n-dimensional CA, whose evolution law depends on an arbitrarym number of neighbor cells.
DEGENERATE BIFURCATIONS OF RESONANT TORI IN HAMILTONIAN SYSTEMS
Authors: VOYATZIS GEORGE , ICHTIAROGLOU SIMOS
Published: July 2002

The twist condition is a necessary condition in integrable Hamiltonian systems and symplectic maps to obtain Poincaré–Birkhoff bifurcations under small perturbations. When this condition does not hold, topological structures other than Poincaré–Birkhoff chains arise in phase space through bifurcations of isolated periodic orbits and reconnections of asymptotic manifolds. In this paper we construct an integrable model Hamiltonian with degeneracies suitable to observe these phenomena close to nontwist resonant tori. The generation of isochronous chains and the stability of their fixed points is determined analytically and a condition for the reconnection is found. Particular examples are given, illustrating the bifurcation and reconnection scenario for several cases of degeneracy.
SIMULATIONS OF VOCAL FOLDS WITH AN ANALOG CIRCUIT
Authors: REUTER ROBERT , ORGLMEISTER REINHOLD , HERZEL HANSPETER
Published: July 2002

The human voice source generates complex signals including subharmonics and toroidal oscillations. Essential features of voice production are covered by two-mass models where each vocal fold is represented by two oscillators. We present a related analog circuit which allows online analysis of the generated complex signals. Using narrow-band spectrograms various bifurcations due to left–right asymmetry are monitored. Time series, spectra, return maps, and response measurements provide further detailed information about phase-locking and toroidal oscillations. Finally, possible clinical applications are discussed.
TOWARDS A NATURAL INTERNET-BASED COLLABORATIVE ENVIRONMENT WITH SUPPORT OF OBJECT PHYSICAL AND SOCIAL CHARACTERISTICS
Authors: MA JIANHUA , HUANG RUNHE , NAKATANI RYOUHEI
Published: July 2002

Objects in this article refer to sharable applications, such as a whiteboard and a video player, used by multi-users who are in different sites and have computers connected to networks. The objects are important elements in our Internet-based desktop collaborative system, called virtual collaboration room (VCR). We argue that a natural collaborative environment should be developed in a framework of using both a room metaphor and an object metaphor, i.e., emulating the fundamental characteristics of real rooms and real objects, respectively. This article gives the first systematic specifications of object physical and social characteristics, and discusses how to exploit and implement the object characteristics in VCR. A preliminary prototype of platform independent real-time audio/video communications among multiple users is also described. It can be used together with VCR.
INTRINSICALLY n-LINKED GRAPHS
Authors: FLAPAN ERICA , POMMERSHEIM JAMES , FOISY JOEL , NAIMI RAMIN
Published: July 2002

For every natural number n, we exhibit a graph with the property that every embedding of it in ℝ3 contains a non-split n-component link. Furthermore, we prove that our graph is minor minimal in the sense that every minor of it has an embedding in ℝ3 that contains no non-split n-component link.
GRAVITATIONAL COLLAPSE AND FRAGMENTATION OF MOLECULAR CLOUD CORES
Authors: SIGALOTTI LEONARDO DI G. , KLAPP JAIME
Published: July 2002

The detected multiplicity of main-sequence and pre-main-sequence stars along with the emerging evidence for binary and multiple protostars, imply that stars may ultimately form by fragmentation of collapsing molecular cloud cores. These discoveries, coupled with recent observational knowledge of the structure of dense cloud cores and of the properties of young binary stars, provide serious constraints to the theory of star formation. Most theoretical progress in the field of star formation is largely based on numerical calculations of the early collapse and fragmentation of protostellar clouds. Although these models have been quite successful at predicting the formation of binary protostars, a direct comparison between theory and observations has not yet been established. The results of recent observations as well as of early and recent analytic and numerical models, on which the present theory of star formation is based, are reviewed here in a self-consistent manner.
PECULIARITIES OF ANISOTROPY AND POLARIZATION AS AN INDICATOR OF NOISES IN THE CMB MAPS
Authors: KOTOK E. , NOVIKOV I. D. , NASELSKY P. , NOVIKOV D.
Published: July 2002

We discuss some new problems of the modern cosmology which arose after the BOOMERANG and MAXIMA-1 successful missions. Statistics of high peaks of the CMB anisotropy is analyzed and we discuss possible inner structure of such peaks in the observational data of future MAP and PLANCK missions. We have investigated geometrical and statistical properties of the CMB polarization around such high isolated peaks of anisotropy in the presence of a polarized pixel noise and point sources. The structure of polarization fields in the vicinity of singular points with zero polarization is very sensitive to the level of pixel noises and point sources in the CMB maps.
EINSTEIN GRAVITY AS AN EMERGENT PHENOMENON?
Authors: BARCELÓ CARLOS , VISSER MATT , LIBERATI STEFANO
Published: July 2002

In this essay we marshal evidence suggesting that Einstein gravity may be an emergent phenomenon, one that is not "fundamental" but rather is an almost automatic low-energy long-distance consequence of a wide class of theories. Specifically, the emergence of a curved spacetime "effective Lorentzian geometry" is a common generic result of linearizing a classical scalar field theory around some nontrivial background. This explains why so many different "analog models" of general relativity have recently been developed based on condensed matter physics; there is something more fundamental going on. Upon quantizing the linearized fluctuations around this background geometry, the one-loop effective action is guaranteed to contain a term proportional to the Einstein–Hilbert action of general relativity, suggesting that while classical physics is responsible for generating an "effective geometry," quantum physics can be argued to induce an "effective dynamics." This physical picture suggests that Einstein gravity is an emergent low-energy long-distance phenomenon that is insensitive to the details of the high-energy short-distance physics.
EFFECTIVE HADRON MASSES AND COUPLINGS IN NUCLEAR MATTER AND INCOMPRESSIBILITY
Authors: TUCHITANI KUNITO , KOUNO HIROAKI , HASEGAWA AKIRA , NAKANO MASAHIRO
Published: July 2002

The role of effective hadron masses and effective couplings in nuclear matter is studied using a generalized effective Lagrangian for σ-ω model. A simple relation among the effective masses, the effective couplings and the incompressibility K is derived. Using the relation, it is found that the effective repulsive and the effective attractive forces almost cancel each other out at the normal density. Inversely, if this cancellation is almost complete, K is 250~350 MeV.
MULTIFRACTAL MEASURES IN FRACTIONAL ITERATIVE MAPS
Authors: KIM KYUNGSIK , KIM G. H. , LEE J. R. , CHOI J. S. , KONG Y. S. , HENRY B. I. , YUM M. K. , ODAGAKI T.
Published: July 2002

We introduce a new fractional iterative map with two control parameters of β and γ in the range of the fractional value between one and two. Particularly, we present basically chaotic properties and multifractals of this map. The fractal dimension obtained from multifractal measures is taken to be near one as γ→4 and η→2 for fixed values of β, while it is expected to take the minimum value of the fractal dimension 0.538 as γ→γ∞ for β=1 and η=1. Our result obtained from multifractal measures are also compared with other well-known results.
POWER-LAW ACCELERATED BIRNBAUM–SAUNDERS LIFE MODELS
Authors: OWEN W. J. , PADGETT W. J.
Published: July 2002

An accelerated life testing procedure can reduce the lifetime of a material by observing the material's behavior under higher levels of stress than what is normally encountered. Useful inference hinges on the selection of an appropriate lifetime distribution and the substitution of an acceleration model for a distribution parameter, such as the mean or scale. The (inverse) power-law model is one such acceleration model that has applications to fatigue studies in metals, where failure tends to be crack-induced. The Birnbaum–Saunders distribution was developed to model fatigue in materials where the failure of a specimen is due to the propagation of a dominant crack. This paper will compare two Birnbaum–Saunders type models from the literature (that have power-law accelerated features) with a new but distinctive model proposed here. The new model is an accelerated life model for a reparameterization of the baseline distribution. Comparison of the three models will be via the aluminum coupon data set from Birnbaum and Saunders5 and issues of accelerated testing will be discussed.
PREDICTING FAULT-PRONE SOFTWARE MODULES IN EMBEDDED SYSTEMS WITH CLASSIFICATION TREES
Authors: KHOSHGOFTAAR TAGHI M. , ALLEN EDWARD B.
Published: July 2002

Embedded-computer systems have become essential to life in modern society. For example, the backbone of society's information infrastructure is telecommunications. Embedded systems must have highly reliable software, so that we avoid the severe consequences of failures, intolerable down-time, and expensive repairs in remote locations. Moreover, today's fast-moving technology marketplace mandates that embedded systems evolve, resulting in multiple software releases embedded in multiple products.

Software quality models can be valuable tools for software engineering of embedded systems, because some software-enhancement techniques are so expensive or time-consuming that it is not practical to apply them to all modules. Targeting such enhancement techniques is an effective way to reduce the likelihood of faults discovered in the field. Research has shown software metrics to be useful predictors of software faults. A software quality model is developed using measurements and fault data from a past release. The calibrated model is then applied to modules currently under development. Such models yield predictions on a module-by-module basis.

This paper examines the Classification And Regression Trees (CART) algorithm for building tree-based models that predict which software modules have high risk of faults to be discovered during operations. CART is attractive because it emphasizes pruning to achieve robust models. This paper presents details on the CART algorithm in the context of software engineering of embedded systems. We illustrate this approach with a case study of four consecutive releases of software embedded in a large telecommunications system. The level of accuracy achieved in the case study would be useful to developers of an embedded system. The case study indicated that this model would continue to be useful over several releases as the system evolves.
LASER-INDUCED PROCESS OF BINARY ALLOYING OF Ge–Se
Authors: BHADRA S. K. , BANDYOPADHYAY T. , MAITI A. K. , GOSWAMI K.
Published: July 2002

Thin films of chalcogenides are synthesized by CW argon ion laser irradiation of separate Ge/Se and Se/Te film sandwiches according to near stoichiometric proportions. The compound formation and crystalline transition of amorphous Se film are characterized by observing photomicrographs and optical absorption spectra. The composite film of bilayer Ge/Se does not form compounds but deposits as separate elements under equivalent laser fluence.
MANY-BODY EFFECTS AND THE METAL–INSULATOR TRANSITION AT SEMICONDUCTOR SURFACES AND INTERFACES
Authors: FLORES FERNANDO , ORTEGA JOSÉ , PÉREZ RUBÉN
Published: July 2002

The aim of this paper is to present a general perspective of the different correlation effects appearing at semiconductor surfaces and interfaces. The unifying theoretical picture is the generalized Hubbard Hamiltonian. In a first step, we show how such Hamiltonians can be analyzed using both a local density approach and many-body techniques. This discussion shows how to determine the different electron–electron interaction parameters appearing in the generalized Hubbard Hamiltonian, from a set of restricted LDA calculations for the full surface. Then, different surfaces and interfaces are analyzed; in particular, we consider the Si(111)-(7 × 7), -(5 × 5) and -(3 × 3) reconstructions as well as the Si-rich SiC(111)-[Formula: see text] and -(3 × 3) surfaces. These Si-rich SiC(111) surfaces are shown to behave like a Mott–Hubbard insulator, while the Si(111) reconstructions are charge transfer systems presenting a variety of different behaviors; thus, the Si(111)-(7 × 7) is metallic, while the -(5 × 5) and the -(3 × 3) are found to be insulating. We have also analyzed the Sn/Ge(111)-(3 × 3) reconstruction, the alkali metal/GaAs(110) junction and the K/Si(111)-[Formula: see text]-B interface. Our discussion shows that the alkali metal/GaAs and K/Si(111) interfaces present also a Mott–Hubbard metal–insulator transition, and that the Sn/Ge(111)-(3 × 3) interface is still metallic in spite of nonnegligible many-body effects appearing in the surface band density of states. We conclude that two-dimensional systems at semiconductor surfaces and interfaces present a rich variety of many-body effects that modify substantially the one-electron picture one gets from LDA calculations.
INTERPRETATION OF REFLECTION HIGH ENERGY ELECTRON DIFFRACTION FROM DISORDERED SURFACES: DYNAMICAL THEORY AND ITS APPLICATION TO THE EXPERIMENT
Authors: KORTE UWE
Published: July 2002

Reflection high energy electron diffraction (RHEED) is one of the few surface science techniques that are applied in a fabrication process, namely to monitor the epitaxial growth of ultrathin films and advanced materials. In spite of this technological relevance the multiple scattering nature of the involved scattering processes has hindered the quantitative interpretation of RHEED in the case of real, i.e. imperfect, surfaces for a long time. This article reviews recent progress in the understanding of RHEED from surfaces exhibiting various types of disorder. It concentrates on a multiple scattering formalism — based on perturbation theory with the nonperiodic part of the structure as perturbation — that allows the computation and interpretation of RHEED from real systems. The validity regime of the approach is discussed. We demonstrate the potential of the method by its application to the quantitative interpretation of experimental data. The range of treated problems comprises occupational disorder, intensity oscillations, structure of disordered metal/adsorbate systems, diffuse scattering from adatoms, Kikuchi scattering and phonon scattering.
THEORETICAL ANALYSIS OF ADSORBATE-INDUCED ROW-TYPE ALIGNMENTS ON THE FCC(110) SURFACE
Authors: YASUTANI K. , KABURAGI M. , KANG M.
Published: July 2002

The structures of adsorbate-induced row-type alignments of the FCC(110) surface are analyzed using the two-dimensional Blume–Emmery–Griffiths (BEG) model with the nearest-neighbor (NN) and the next-nearest-neighbor (NNN) interactions. The ground state phase diagram in whole regimes of interactions is determined by the energy comparison method. Comparing the results of ground state analysis with experimentally observed structures of the O/Rh(110) and O/Pd(110), we determine the interaction regimes for these systems. From the thus determined interaction regime, we propose the model structure in the c(2 × 6) phase of the O/Pd(110).
Growth Disturbance of the Paralytic Limb in Newborn Brachial Plexus Palsy
Authors: Hamada Yasuhiko , Kawabata Hidehiko , Yasui Natsuo , Kitano Motohiro , Masatomi Takashi
Published: July 2002

Growth disturbance of the paralytic limb was analyzed in 50 patients with newborn brachial plexus palsy. The ratio of the bone length on the paralyzed side to that on the normal side as depicted on the roentogenogram was calculated at the average age of 7.2 years. While in upper type palsy the ratio was 95% in the humerus, 97% in the radius, and 96% in the ulna, that in total type palsy was 93%, 89%, and 88%, respectively. In mild paralysis, it was 95%, 98%, and 97%, respectively, while in severe paralysis, it was 93%, 88%, and 88%, respectively. In those who underwent neurosurgical reconstruction, it was 94%, 93%, and 92%, respectively, while in those who did not, it was 92%, 84%, and 85%, respectively.

The degree of shortening was well correlated with the extent and severity of paralysis, and early neurosurgical reconstruction was found to reduce it.
Opening Wedge Osteotomy and Bone Grafting for Distal Radius Malunion
Authors: Wada Takuro , Usui Masamichi , Aoki Mitsuhiro , Ishii Seiichi
Published: July 2002

We performed opening wedge osteotomy and bone grafting in conjunction with buttress plate fixation for distal radius malunion of 16 wrists in 15 patients (nine dorsal and seven volar displacements). Surgery was indicated in manually active patients with functional disability in the wrist due to a limited range of motion, weakness in grip, and pain. Surgery was attempted to restore the anatomical configuration of the distal radius: volar tilt, radial inclination, and radial length. The preoperative average volar tilt was -31° for dorsal displaced malunions and 28° for volar displaced malunions. The postoperative volar tilt was restored to 3° for dorsal diplaced malunions and to 10° for volar displaced malunions. Radial shortening was corrected from 6.8 mm to 1.4 mm. The preoperative combined dorsal and volar flexion of all patients improved from an average of 87° to 136°. Combined pronation and supination of the forearm improved from an average of 115° to 159°. Subjective evaluation by Saito's functional score was excellent in nine wrists, good in four, fair in two, and poor in one. The poor and fair results were due to residual deformities in volar tilt and radial length.
INTRODUCTION TO POS: A PROTOCOL OPERATIONAL SEMANTICS
Authors: KONING JEAN-LUC , OUDEYER PIERRE-YVES
Published: July 2002

In this paper, we propose a system for representing interaction protocols called POS which is both Turing complete and determine a complete semantics of protocols. This work is inspired by the Structured Operational Semantics in programming languages. We precisely define POS and illustrate its power on an extended example.
FORMALIZING AND REASONING ABOUT THE REQUIREMENTS SPECIFICATIONS OF WORKFLOW SYSTEMS
Authors: TRAJCEVSKI GOCE , BARAL CHITTA , LOBO JORGE
Published: July 2002

This work addresses the problem of workflow requirements specifications considering the realistic assumptions that, it involves experts from different domains (i.e. representatives of different business policies); not all the possible execution scenarios are known beforehand, during the early stage of specification. In particular, since the main purpose of a workflow is to achieve a certain (bussiness) goal, we propose a formalism which enables the users to specify their requirements (and expectations) and test if the information that they have provided is, in a sense, sufficient for the workflow to behave "as desired", in terms of the goal. Our methodology allows domain experts to express not only their knowledge, but also the "ignorance" (the semantics allows for unknown values to reflect a realistic situation of agents dealing with incomplete information) and the possibility of occurrence of exceptional situations. As a basis for formalizing the process of equirements specifications, we are using the recent results on reasoning about actions. We propose a high level language AW which enables specifying the effects that activites have on the environment and how they should be coordinated. We also describe our prototype tool for process specification. Strictly speaking, in this work we go "one step" before actual analysis and design, and offer a formalism which enables the involved partners to see if the extent to which they have expressed their domain knowledge (which may sometimes be subject to a proprietary restricions) can satisfy the intended needs and behaviour of their product_to_be. We define an entailment relation which enables reasoning about the correctness of the specification, in terms of achieving a desired goal and, also testing about consequences of modifications in the workflow descriptions.
BEIJING JEEP AT A CROSSROADS: FACING THE CHALLENGE OF CHINA'S ENTRY INTO THE WTO
Authors: Young Michael N. , Tan Justin
Published: July 2002

Beijing Jeep Corporation (BJC) was founded in 1984 as one of the first and largest joint venture between an American company (American Motors Corporation) and a Chinese enterprise. Early in its operation, BJC had been given preferential treatment on tariffs and foreign exchange. Since over forty percent of the content of BJC was produced in China, it had operated as a local manufacturer under heavy protection from imports for all of its short life. All this appeared to be on the brink of changing when trade negotiators for the United States and China announced, after thirteen years of on and off negotiations, the agreement on the terms for China's entry into the World Trade Organization. The terms of the agreement called for a steep reduction in tariffs for imported automobiles from nearly one hundred percent to twenty-five percent by 2006. This would have a direct impact on BJC performance. The case focuses on the strategic challenges facing companies in the changing trade and economic environment.
THE MAGNETIC RESONANCE IMAGING OF THE LUMBAR SPINE IN OUT-PATIENTS WITH LOW BACK PAIN
Authors: CHEN BOHUA , LAVENDER STEVE , ANDERSSON GUNNAR B. J.
Published: July 2002

This paper aims to estimate the prevalence rates of MRI change in LBP out-patients and to determine the relationship between abnormalities in an MRI and personal and occupational factors. The MRI records were obtained from 200 out-patients with LBP (114 males and 86 females) who received a diagnostic MRI at St. Luke's Medical Center. The mean and standard deviation of this sample's age were 43.8 years and 14.8 years, respectively. Based on the MRI, each lumbar disc was scored as normal or degenerated. Bulging and herniated were also recorded. Each patient completed a short questionnaire that included the measures of height, weight, age, and present occupation and any history of "heavy manual labor". Occupations were grouped into white collar sedentary, white collar professional, blue collar exposed to prolonged sitting and vibration, blue collar exposed to heavy, unemployed or retired, and homemaker. Chi-square tests were used to determine the statistical significance of these trends. A multiple logistic regression was used to develop a predictive model of spine pathology based on a subject's individual characteristics and occupational classification.

Normal discs were found in 26% of the patients and degenerated discs in 47.5%. There were bulging/herniated disks in 26.5%. In men who were younger than 29 years, 50% had herniated disks, and 50% were normal. Three fourth of the women in the same age group showed normal discs. Forty-three percent of the subjects reported a history of performing heavy labor. Using the logistic regression model there were two variables predictive of observable MRI pathology: age and prior history of heavy labor. The analysis indicated that an older individual who had a history and heavy labor was more likely to show one or more pathological model discs in an MRI scan.
RESULTS ON PASSIVATION OF InP BY PHOTO-CVD SiO2 AND SiNx OBTAINED BY USING THE LOW-FREQUENCY NOISE MEASUREMENT TECHNIQUE
Authors: GOTTWALD P. , KRÄUTLE H. , SZENTPÁLI B. , HARTNAGEL H. L.
Published: July 2002

Photo enhanced chemical vapour deposition (PVD) of SiO 2 and Si 3 N 4 has been applied for surface passivation of specially designed n-type InP planar test resistors prepared by mesa etching on a semiinsulating InP substrate. The deposition temperatures were 150, 200 and 300 °C. The low-frequency noise (LFN) measurement technique was used for the characterisation. It was stated that the commercial PVD technology using Hg sensitization results in a low-damage passivation of InP, if a SiO 2 layer is deposited at a temperature around 300 °C. Low 1/f noise and low generation-recombination noise are generated in the test resistors passivated by this technology, and no surface conduction has been caused on the high-resistivity substrate-material holding the resistor patterns. Otherwise, for the PVD deposited Si 3 N 4 layer a significantly higher noise level has been measured, and surface conduction has also appeared.
RANDOM DYNAMICAL SYSTEMS IN ECONOMICS
Authors: SCHENK-HOPPÉ KLAUS REINER
Published: July 2002

This paper surveys recent advances in the application of random dynamical systems theory in economics. It illustrates the usefulness of this framework for modeling and analysis of economic phenomena with stochastic components, mainly focusing on stochastic dynamic models of economic growth. The paper also highlights some directions for further applications and interdisciplinary research on random dynamical systems.
MediaView
Authors: Phillips Richard L.
Published: July 2002

MediaView is a multimedia digital publication system that was designed to be flexible and free from restrictions. It was also designed to take maximum advantage of the media-rich hardware and software capabilities of the NeXT [5] computer, especially the features of the NeXTdimension [17] subsystem. Rather than emphasize the work that is almost always paired with multimedia,
presentation,
MediaView emphasizes communication. The system does not tacitly impose the “publisher's” agenda on the reader, but structure and sequencing can be overlaid if appropriate. The result is a very general system—free of artificial structure and inconvenient metaphors.
Digital media and the law
Authors: Samuelson Pamela
Published: July 2002

Over the past two years, I have written seven “Legally Speaking” columns and one feature article for
Communications
about legal issues affecting computing professionals. These writings have covered an array of legal topics including: criminal and civil liability for hackers who breach computer security systems; first amendment issues arising in computing or electronic publishing markets; intellectual property issues, such as patent protection for computer program algorithms; copyright protection for look and feel of user interfaces; what the user interface design field thinks about such protection, and various theories by which a firm might claim to own interface specification information for software systems.
On the selection of efficient record segmentations and backup strategies for large shared databases
Authors: March Salvatore T. , Scudder Gary D.
Published: July 2002

In recent years the information processing requirements of business organizations have expanded tremendously. With this expansion, the design of databases to efficiently manage and protect business information has become critical. We analyze the impacts of
record segmentation
(the assignment of data items to segments defining subfiles), an efficiency-oriented design technique, and of
backup and recovery strategies
, a data protection technique, on the overall process of database design. A combined record segmentation/backup and recovery procedure is presented and an application of the procedure is discussed. Results in which problem characteristics are varied along three dimensions: update frequencies, available types of access paths, and the predominant type of data retrieval that must be supported by the database, are presented.
Theorem proving using equational matings and rigid
E
-unification
Authors: Gallier Jean , Narendran Paliath , Raatz Stan , Snyder Wayne
Published: July 2002

In this paper, it is shown that the method of matings due to Andrews and Bibel can be extended to (first-order) languages with equality. A decidable version of
E
-unification called
rigid E-unification
is introduced, and it is shown that the method of equational matings remains complete when used in conjunction with rigid
E
-unification. Checking that a family of mated sets is an equational mating is equivalent to the following restricted kind of
E
-unification.

Problem
Given E
→
={E
i
| 1≤i≤n} a family of
n
finite sets of equations and S={〈u
i
,v
i
〉 |1≤i≤n} a set of
n
pairs of terms, is there a substitution θ such that, treating each set θ(E
i
) as a set of
ground
equations (i.e., holding the variables in θ(E
i
) “rigid”), θ(u
i
), and θ(v
i
) are provably equal from θ(E
i
) for i=1,...,n?

Equivalently, is there a substitution θ such that θ(u
i
) and θ(v
i
) can be shown congruent from θ(E
i
) by the congruence closure method for i=1,...,n?

A substitution θ solving the above problem is called a
rigid
E
→
-unifier of S
, and a pair 〈E
→
,S〉 such that
S
has some rigid E
→
-unifier
is called an
equational premating.
It is shown that deciding whether a pair 〈 E
→
,S〉is an equational premating is an NP-complete problem.
Rule-based optimization and query processing in an extensible geometric database system
Authors: Becker Ludger , Güting Ralf Hartmut
Published: July 2002

Gral is an extensible database system, based on the formal concept of a many-sorted relational algebra. Many-sorted algebra is used to define any application's query language, its query execution language, and its optimiztion rules. In this paper we describe Gral's optimization component. It provides (1) a sophisticated rule language—rules are transformations of abstract algebra expressions, (2) a general optimization framework under which more specific optimization algorithms can be implemented, and (3) several control mechanisms for the application of rules. An optimization algorithm can be specified as a series of steps. Each step is defined by its own collection of rules together with a selected control strategy.

The general facilities are illustrated by the complete design of an example optimizer—in the form of a rule file—for a small nonstandard query language and an associated execution language. The query language includes selection, join, ordering, embedding derived values, aggregate functions, and several geometric operations. The example shows in particular how the special processing techniques of a geometric database systems, such as spatial join methods and geometric index structures, can be integrated into query processing and optimization of a relational database system. A similar, though larger, optimizer is fully functional within the geometric database system implemented as a Gral prototype.
Polymorphic time systems for estimating program complexity
Authors: Dornic Vincent , Jouvelot Pierre , Gifford David K.
Published: July 2002

We present a new approach to static program analysis that permits each expression in a program to be assigned an execution time estimate. Our approach uses a
time system
in conjunction with a conventional type system to compute both the type and the time of an expression. The
time
of an expression is either an integer upper bound on the number of ticks the expression will execute, or the distinguished element long that indicates that the expression contains a loop, and thus may run for an arbitrary length of time. Every function type includes a
latent time
that is used to communicate its expected execution time from the point of its definition to the points of its use. Unlike previous approaches, a time system works in the presence of first-class functions and separate compilation. In addition,
time polymorphism
allows the time of a function to depend on the times of any functions that it takes as arguments. Time estimates are useful when compiling programs for multiprocessors in order to balance the overhead of initiating a concurrent computation against the expected execution time of the computation. The correctness of our time system is proven with respect to a dynamic semantics.