bluuebunny/crossref_metadata_2025 huggingface dataset:
[Nphe1]nociceptin(113)-NH2 antagonizes nociceptin-induced hypotension, bradycardia, and hindquarters vasodilation in the anesthetized rat
Authors: Chen Y , Chang M , Wang Z Z , Chen L X , Yang Q , Qi Y M , Wang R
Published: July 2002

The purpose of this study was to investigate the effects of [Nphe1]nociceptin(113)-NH2 on nociceptin-induced decreases in mean arterial pressure (MAP), heart rate (HR), and hindquarters vascular bed resistance (HVBR) of the anesthetized rat. The results showed that i.c.v. or i.v. [Nphe1]nociceptin(113)-NH2 (1.512 nmol/kg and 5-120 nmol/kg, respectively) could antagonize the depressor effects of i.c.v. or i.v. nociceptin (3 and 30 nmol/kg, respectively) on MAP and HR. Furthermore, [Nphe1]nociceptin(113)-NH2 (5120 nmol/kg) could reverse nociceptin (30 nmol/kg)-induced decrease of HVBR. However, [Nphe1]nociceptin(113)-NH2 had no significant effects on similar effects induced by morphine. Our results suggest that [Nphe1]nociceptin(113)-NH2 acts as a selective antagonist of the nociceptin receptor in the cardiovascular system of the rat.Key words: nociceptin, [Nphe1]nociceptin(113)-NH2, morphine, mean arterial pressure, heart rate, hindquarters vascular bed resistance.
USING STOCHASTIC INFORMATION TO PREDICT APPLICATION BEHAVIOR ON CONTENDED RESOURCES
Authors: SCHOPF JENNIFER M. , BERMAN FRANCINE
Published: July 2002

Prediction is a critical component in the achievement of application execution performance. The development of adequate and accurate prediction models is especially difficult in local-area clustered environments where resources are distributed and performance varies due to the presence of other users in the system. This paper discusses the use of stochastic values to parameterize cluster application performance models. Stochastic values represent a range of likely behavior and can be used effectively as model parameters. We describe two representations for stochastic model parameters and demonstrate their effectiveness in predicting the behavior of several applications under different workloads on a contended network of workstations.
LINDSTEDT SERIES FOR PERTURBATIONS OF ISOCHRONOUS SYSTEMS: A REVIEW OF THE GENERAL THEORY
Authors: BARTUCCELLI MICHELE , GENTILE GUIDO
Published: July 2002

We give a proof of the persistence of invariant tori for analytic perturbations of isochronous systems by using the Lindstedt series expansion for the solutions of the equations of motion. With respect to the case of anisochronous systems, there is the additional problem of finding the set of allowed rotation vectors, because they cannot be given a priori simply by looking at the unperturbed system. By considering the involved parameters (size of the perturbation, rotation vector and average action of a persisting invariant torus) as independent parameters we can introduce a function which is analytic in such parameters and only when the latter satisfy some constraint it becomes a solution: this can be regarded as a sort of singular implicit function problem. Therefore, although the dependence of the parameters, hence of the solution, upon the size of the perturbation is not smooth, in this way we construct explicitly the solution by using an absolutely convergent power series.
RAPIDLY DECREASING SOLUTIONS AND NONRELATIVISTIC LIMIT OF SEMILINEAR DIRAC EQUATIONS
Authors: MATSUYAMA TOKIO
Published: July 2002

In this paper we study the existence of the solutions for the nonlinear Dirac equations in the weighted Sobolev spaces and the Schwartz space. It is also shown that these solutions converge to the solutions for the nonlinear Schrödinger type equations if the speed of light is regarded as infinity.
Generalised Deformations, Koszul Resolutions, Moyal Products
Authors: Nadaud François
Published: July 2002

We generalise Gerstenhaber's theory of deformations, by dropping the assumption that the deformation parameter should commute with the elements of the original algebra. We give the associated cohomology and construct a Koszul resolution for the polynomial algebra [Formula: see text] in the "homogeneous" case. We then develop examples in the case of [Formula: see text] and find some Moyal-like products of a new type. Finally, we show that, for any field K, matrix algebras with coefficients in K and finite degree extensions of K are rigid, as in the commutative case.
Symmetries of the Quantum State Space and Group Representations
Authors: Cassinelli Gianni , de Vito Ernesto , Lahti Pekka , Levrero Alberto
Published: July 2002

The homomorphisms of a connected Lie group G into the symmetry group of a quantum system are classified in terms of unitary representations of a simply connected Lie group associated with G. Moreover, an explicit description of the T-multipliers of G is obtained in terms of the ℝ-multipliers of the universal covering G* of G and the characters of G*. As an application, the Poincaré group and the Galilei group, both in 3+1 and 2+1 dimensions, are considered.
GENERAL FORMULATION OF QUANTUM ANALYSIS
Authors: SUZUKI MASUO
Published: July 2002

A general formulation of noncommutative or quantum derivatives for operators in a Banach space is given on the basis of the Leibniz rule, irrespective of their explicit representations such as the Gâteaux derivative or commutators. This yields a unified formulation of quantum analysis, namely the invariance of quantum derivatives, which are expressed by multiple integrals of ordinary higher derivatives with hyperoperator variables. Multivariate quantum analysis is also formulated in the present unified scheme by introducing a partial inner derivation and a rearrangement formula. Operator Taylor expansion formulas are also given by introducing the two hyperoperators [Formula: see text] and [Formula: see text] with the inner derivation δA:Q↦[A,Q]≡AQ-QA. Physically the present noncommutative derivatives express quantum fluctuations and responses.
LOG SMOOTH DEFORMATION AND MODULI OF LOG SMOOTH CURVES
Authors: KATO FUMIHARU
Published: July 2002

The aim of this paper is to define a reasonable moduli theory of log smooth curves which recovers the classical Deligne–Knudsen–Mumford moduli of pointed stable curves.
BOCHNER–WEITZENBÖCK FORMULAS ASSOCIATED WITH THE RARITA–SCHWINGER OPERATOR
Authors: BRANSON THOMAS , HIJAZI OUSSAMA
Published: July 2002

We compute several identities relating curvature actions to second-order differential operators on twistors and sections of related bundles. Based on these formulas, we establish various estimates and vanishing theorems.
KÄHLER GEOMETRY OF TORIC VARIETIES AND EXTREMAL METRICS
Authors: ABREU MIGUEL
Published: July 2002

A (symplectic) toric variety X, of real dimension 2n, is completely determined by its moment polytope Δ ⊂ ℝn. Recently Guillemin gave an explicit combinatorial way of constructing "toric" Kähler metrics on X, using only data on Δ. In this paper, differential geometric properties of these metrics are investigated using Guillemin's construction. In particular, a nice combinatorial formula for the scalar curvature R is given, and the Euler–Lagrange condition for such "toric" metrics being extremal (in the sense of Calabi) is proven to be R being an affine function on Δ ⊂ ℝn. A construction, due to Calabi, of a 1-parameter family of extremal Kähler metrics of non-constant scalar curvature on [Formula: see text] is recast very simply and explicitly using Guillemin's approach. Finally, we present a curious combinatorial identity for convex polytopes Δ ⊂ ℝn that follows from the well-known relation between the total integral of the scalar curvature of a Kähler metric and the wedge product of the first Chern class of the underlying complex manifold with a suitable power of the Kähler class.
AMENABILITY AND STRONG AMENABILITY FOR FUSION ALGEBRAS WITH APPLICATIONS TO SUBFACTOR THEORY
Authors: HIAI FUMIO , IZUMI MASAKI
Published: July 2002

The relationship between index theory and random walks on fusion algebras is discussed. Popa's notion of amenability is reformulated as a property of fusion algebras, and several equivalent conditions of amenability are obtained. A ratio limit theorem is proved as a characterization of amenability. A number of conditions, all equivalent to Popa's notion of strong amenability in the case of subfactors, of a pair of a fusion algebra and a probability measure are proposed, and their relationship is studied from the viewpoint of random walks and entropic densities. Fusion algebra homomorphisms and free products of fusion algebras are also discussed.
THE SZNAJD MODEL OF CONSENSUS BUILDING WITH LIMITED PERSUASION
Authors: STAUFFER DIETRICH
Published: July 2002

The Sznajd model, where two people having the same opinion can convince their neighbors on the square lattice, is modified in the sense of Deffuant et al. and Hegselmann, that only neighbors of similar opinions can be convinced. Then consensus is easy for the competition of up to three opinions but difficult for four and more opinions.
RADIATIVE CORRECTIONS TO NEUTRINO ENERGY LOSS RATE IN STELLAR INTERIORS
Authors: ESPOSITO S. , MANGANO G. , MIELE G. , PICARDI I. , PISANTI O.
Published: July 2002

We consider radiative electromagnetic corrections, at order α, to the process [Formula: see text] at finite density and temperature. This process represents one of the main contributions to the cooling of stellar environments in the late stages of star evolution. We find that these corrections affect the energy loss rate by a factor (-4-1)% with respect to the tree level estimate, in the temperature and density ranges where the neutrino pair production via e+e- annihilation is the most efficient cooling mechanism.
ON DIRECT AND CROSSED CHANNEL ASYMPTOTICS OF FOUR-POINT FUNCTIONS IN AdS/CFT CORRESPONDENCE
Authors: SANJAY
Published: July 2002

We analyse the leading logarithmic singularities in direct and crossed channel limit of the four-point functions in dilaton–axion sector of type IIB supergravity on AdS5 in AdS/CFT correspondence. Logarithms do not cancel in the full correlator in both channels.
QUANTUM AND CLASSICAL GAUGE SYMMETRIES IN A MODIFIED QUANTIZATION SCHEME
Authors: FUJIKAWA KAZUO , TERASHIMA HIROAKI
Published: July 2002

The use of the mass term as a gauge fixing term has been studied by Zwanziger, Parrinello and Jona-Lasinio, which is related to the nonlinear gauge [Formula: see text] of Dirac and Nambu in the large mass limit. We have recently shown that this modified quantization scheme is in fact identical to the conventional local Faddeev–Popov formula without taking the large mass limit, if one takes into account the variation of the gauge field along the entire gauge orbit and if the Gribov complications can be ignored. This suggests that the classical massive vector theory, for example, is interpreted in a more flexible manner either as a gauge invariant theory with a gauge fixing term added, or as a conventional massive nongauge theory. As for massive gauge particles, the Higgs mechanics, where the mass term is gauge-invariant, has a more intrinsic meaning. It is suggested that we extend the notion of quantum gauge symmetry (BRST symmetry) not only to classical gauge theory but also to a wider class of theories whose gauge symmetry is broken by some extra terms in the classical action. We comment on the implications of this extended notion of quantum gauge symmetry.
SEMILEPTONIC B DECAYS INTO EXCITED CHARMED MESONS $(D_1,D^*_2)$ IN HQEFT
Authors: WANG W. Y. , WU Y. L.
Published: July 2002

Exclusive semileptonic B decays into excited charmed mesons [Formula: see text] are studied up to the order of 1/mQin the framework of the heavy quark effective field theory (HQEFT), which contains the contributions of both particles and antiparticles. Two wave functions [Formula: see text] and [Formula: see text], which characterize the contributions from the kinematic operator at the order of 1/mQ, are calculated by using QCD sum rule approach in HQEFT. Zero recoil values of other two wave functions [Formula: see text] and [Formula: see text] are extracted from the excited charmed-meson masses. Possible effects from the transition wave functions arising from the chromomagnetic operators at the order of 1/mQare analyzed. It is shown that the experimental measurements for the branching ratios of B→D1lν and [Formula: see text] can be understood in the framework of HQEFT.
CAN THERE BE PHYSICS WITHOUT EXPERIMENTS? CHALLENGES AND PITFALLS
Authors: 'T HOOFT GERARD
Published: July 2002

Physicists investigating space, time and matter at the Planck scale will probably have to work with much less guidance from experimental input than has ever happened before in the history of physics. This may imply that we should insist on much higher demands of logical and mathematical rigor than before. Working with long chains of arguments linking theories to experiment, we must be able to rely on logical precision when and where experimental checks cannot be provided.
CONNECTING GREEN FUNCTIONS IN AN ARBITRARY PAIR OF GAUGES AND AN APPLICATION TO PLANAR GAUGES
Authors: JOGLEKAR SATISH D.
Published: July 2002

We establish a finite field-dependent BRS transformation that connects the Yang–Mills path integrals with the Faddeev–Popov effective actions for an arbitrary pair of gauges F and F'. We establish a result that relates an arbitrary Green function (either a primary one or that of an operator) in an arbitrary gauge F' to those in gauge F that are compatible to the ones in gauge Fby its construction. This is because the construction preserves expectation values of gauge-invariant observables. We establish parallel results also for the planar gauge-Lorentz gauge connection.
THE CDF LAYER 00 DETECTOR
Authors: NELSON TIMOTHY K.
Published: July 2002

The CDF Layer 00 detector consists of single-sided silicon sensors assembled on the beampipe, forming the innermost of eight silicon layers in the CDF detector for Run II of the Fermilab Tevatron. Radiation tolerant p-in-n silicon with 25(50) μm implant(readout) pitch are mounted on a lightweight, cooled support structure and connect to electronics outside the tracking volume via long, fine-pitch cables. Layer 00 will significantly improve the impact parameter resolution and enhance the longevity of the silicon system, benefitting a large portion of the physics program for Run II.
FIBRE BUNDLE FORMULATION OF NONRELATIVISTIC QUANTUM MECHANICS V: INTERPRETATION, SUMMARY AND DISCUSSION
Authors: ILIEV BOZHIDAR Z.
Published: July 2002

We propose a new systematic fibre bundle formulation of nonrelativistic quantum mechanics. The new form of the theory is equivalent to the usual one and is in harmony with the modern trends in theoretical physics and potentially admits new generalizations in different directions. In it the Hilbert space of a quantum system (from conventional quantum mechanics) is replaced with an appropriate Hilbert bundle of states and a pure state of the system is described by a lifting of paths or section along paths in this bundle. The evolution of a pure state is determined through the bundle (analog of the) Schrödinger equation. Now the dynamical variables and density operator are described via liftings of paths or morphisms along paths in suitable bundles. The mentioned quantities are connected by a number of relations derived in this work.

This is the fifth, closing, part of our investigation. We briefly discuss the observer's role in the theory and different realizations of the space–time model used as a base space in the bundle approach to quantum mechanics. The exact conditions for the equivalence of Hilbert bundle and Hilbert space formulations of the theory are pointed out. A table of comparison between both descriptions of nonrelativistic quantum mechanics is presented. We discuss some principal moments of the Hilbert bundle description and show that as a scheme it is more general than the Hilbert space one. Different directions for further research are pointed out.
THEORETICAL ASPECTS OF STANDARD-MODEL HIGGS–BOSON PHYSICS AT A FUTURE e+e-LINEAR COLLIDER
Authors: KNIEHL BERND A.
Published: July 2002

The Higgs boson is the missing link of the Standard Model of elementary particle physics. We review its decay properties and production mechanisms at a future e+e-linear collider and its e-e-, e±γ, and γγ modes, with special emphasis on the influence of quantum corrections. We also discuss how its quantum numbers and couplings can be extracted from the study of appropriate final states.
EXACT SOLUTIONS FOR COSMOLOGICAL MODELS WITH A SCALAR FIELD
Authors: MOTAVALI H. , GOLSHANI M.
Published: July 2002

We consider the existence of a Noether symmetry in the scalar–tensor theory of gravity in flat Friedman–Robertson–Walker (FRW) cosmology. The forms of coupling function ω(ϕ) and generic potential V(ϕ) are obtained by requiring the existence of a Noether symmetry for such theory. We derive exact cosmological solutions of the field equations from a point-like Lagrangian.
HIGH PRESSURE BEHAVIOR OF MANGANITES BY INFRARED AND RAMAN SPECTROSCOPY
Authors: CONGEDUTI A. , POSTORINO P. , DORE P. , LUPI S. , MERCONE S. , NUCARA A. , NARDONE M.
Published: July 2002

The effect of hydrostatic pressure on the properties of the La 0.75 Ca 0.25 MnO 3 manganite have been studied by means of spectroscopic techniques. Raman and infrared (IR) spectra of this pseudocubic manganese perovskite have been collected for the first time over a wide pressure range (0–14 GPa) using a diamond anvil cell. Preliminary results have been obtained also in the case of the Sr 1.5 La 0.5 MnO 4 layered perovskite. The Raman measurements allow us to follow the pressure evolution of the phonon spectrum of the MnO 6 octahedron vibrational modes. Through the IR measurements we study the pressure dependence of the high-frequency octahedron stretching mode and of the broad background associated to polaronic absorption. Raman results show an abrupt discontinuity at P *~7.5 GPa in both frequency and width of some of the observed phonons. The infrared absorption measurements shows a remarkable increase of the polaronic absorption which do not completely screen the phonon peak even at the maximum pressure. Our results, which are in agreement with recent high pressure diffraction data, do not support the possibility of obtaining a metallization transition in the La 0.75 Ca 0.25 MnO 3 manganite at high pressure.
DIRECTED PERCOLATION AND OTHER SYSTEMS WITH ABSORBING STATES: IMPACT OF BOUNDARIES
Authors: FRÖJDH PER , HOWARD MARTIN , LAURITSEN KENT BÆKGAARD
Published: July 2002

We review the critical behavior of nonequilibrium systems, such as directed percolation (DP) and branching-annihilating random walks (BARW), which possess phase transitions into absorbing states. After reviewing the bulk scaling behavior of these models, we devote the main part of this review to analyzing the impact of walls on their critical behavior. We discuss the possible boundary universality classes for the DP and BARW models, which can be described by a general scaling theory which allows for two independent surface exponents in addition to the bulk critical exponents. Above the upper critical dimension d c , we review the use of mean field theories, whereas in the regime d<d c , where fluctuations are important, we examine the application of field theoretic methods. Of particular interest is the situation in d=1, which has been extensively investigated using numerical simulations and series expansions. Although DP and BARW fit into the same scaling theory, they can still show very different surface behavior: for DP some exponents are degenerate, a property not shared with the BARW model. Moreover, a "hidden" duality symmetry of BARW in d=1 is broken by the boundary and this relates exponents and boundary conditions in an intricate way.
A NOTE ON THE TIME EVOLUTION OF GENERALIZED COHERENT STATES
Authors: STONE MICHAEL
Published: July 2002

I consider the time evolution of generalized coherent states based on non-standard fiducial vectors, and show that only for a restricted class of such vectors does the associated classical motion determine the quantum evolution of the states. I discuss some consequences of this for path integral representations.
A VARIED FORM OF THE NAGEL–SCHRECKENBERG MODEL
Authors: CHEN HUNG-JUNG
Published: July 2002

By making slight changes of the Nagel–Schreckenberg model, we propose a varied model for a realistic description of the traffic flow on single-lane highways. While the NaSch model fails to cover the "takeover", this realistic situation gets a good description in our model. Moreover, from the fundamental diagrams achieved in our model, we can divide the forms of traffic flow into five different modes, which are obviously observed in their corresponding time-space diagrams. We also make a comparison of the results of a simple kind of mean-field approximation and the cellular automaton approach.
TRANSPORT STUDIES ON NANOMETER THICK YBa2Cu3O7-δ MULTILAYERS USING Y0.4Pr0.6Cu3O7 AND PrBa2(Cu0.8Ga0.2)3O7 AS BUFFER LAYERS
Authors: Wu Ke , Tipparach Udom. , Chen Tar-Pin , Li Qi , Zeng X. H. , Wert E. , Wagner John. L. , Chen Quark Y. , Wang J. T. , Yang Hong-Chang , Horng Herng-Er
Published: July 2002

We have fabricated PrBa2[Cu1-xGax]3O7 (PBGCO) ceramic samples for x = 0.05, 0.10, 0.15 and 0.20. The electrical resistivities of these samples are many orders of magnitude higher than that of PrBa2Cu3O7 (Pr123) while the other physical properties remain much the same. PBGCO therefore may be a possible buffer layer for YBa2Cu3O7-δ (Y123) superlattices/multilayers. For this reason YBa2Cu3O7-δ/PrBa2(Cu0.8Ga0.2)3O7 (Y123/PBCGO) and YBa2Cu3O7-δ/Y0.4Pr0.6Ba2Cu3O7 (Y123/YPBCO) superlattices were fabricated and their transport properties were studied. It is found that although PBGCO is better for insulating Y123 films in trilayers, inter-Y123 layer coupling exists between separated Y123 layer.
RADIATIVE EFFICIENCY OF LOCALIZED EXCITONS IN ZnCdS TERNARY ALLOYS
Authors: KUMANO HIDEKAZU , MURASAWA SATOSHI , AVRAMESCU ADRIAN , UETA AKIO , SUEMUNE IKUO
Published: July 2002

The effect of exciton localization is investigated in ZnCdS ternary alloys. Zn 1-x Cd x S films with Cd composition x(x=0.21-0.79) were prepared and transient optical properties of photoexcited excitons during the energy relaxation as well as steady-state photoluminescence (PL) properties are examined as a function of crystalline quality of the grown films. The sample with x=0.56 that is closely lattice matched to the GaAs substrate was found to show the maximum integrated band-edge PL (BEPL) intensity. The samples with larger lattice mismatch showed stronger quenching of the BEPL intensity, which is well correlated to the crystalline quality evaluated by X-ray rocking curve measurement. In order to study the contribution of exciton localization, time-resolved PL measurements were carried out. It is clearly revealed that the excitons fully relaxed to the localized states exhibit high luminescence efficiency, while the relaxation process of excitons toward the localization states is shown to be influenced by the crystalline quality of the films.
EPITAXIAL GROWTH OF TRANSPARENT CONDUCTIVE OXIDES
Authors: OHTA HIROMICHI , ORITA MASAHIRO , HIRANO MASAHIRO , UEDA KAZUSHIGE , HOSONO HIDEO
Published: July 2002

Transparent conductive oxides of ITO , ZnO , β- Ga 2 O 3, and CuGaO 2 and SrCu 2 O 2 were grown on single crystal substrates of α- Al 2 O 3 and YSZ by pulsed-laser deposition, and their crystallinity was evaluated by using high-resolution X-ray diffraction and electron microscope. Heteroepitaxial growth was observed in spite of relatively large lattice mismatches between film and substrate. A few disordered layers were generated automatically at film/substrate boundary, played buffer layer to suppress propagation of edge dislocations.
THE ADJOINT PROBLEM IN THE PRESENCE OF A DEFORMED SURFACE: THE EXAMPLE OF THE ROSENSWEIG INSTABILITY ON MAGNETIC FLUIDS
Authors: LANGE ADRIAN
Published: July 2002

The Rosensweig instability is the phenomenon that above a certain threshold of a vertical magnetic field peaks appear on the free surface of a horizontal layer of magnetic fluid. In contrast to almost all classical hydrodynamical systems, the nonlinearities of the Rosensweig instability are entirely triggered by the properties of a deformed and a priori unknown surface. The resulting problems in defining an adjoint operator for such nonlinearities are illustrated. The implications concerning amplitude equations for pattern forming systems with a deformed surface are discussed.
DECAGONAL QUASICRYSTAL PATTERNS WITH EIGHT PROTOTILES
Authors: ESCUDERO JUAN GARCÍA , GARCÍA JAVIER GARCÍA
Published: July 2002

Substitutional decagonal patterns with the golden number squared as inflation factor are studied. Two types of patterns are derived starting from the basic geometric construction. The inflation rules can be composed in an arbitrary order giving new types of patterns. A high number of vertex configurations appear in the structures. The patterns can also be obtained by superposition of two subpatterns.
LOW HYDROGEN CONTENT HYDROGENATED AMORPHOUS CARBON FILMS USING DIRECT CURRENT GLOW DISCHARGE PLASMA CVD
Authors: MALHOTRA MANJU , KUMAR SATYENDRA
Published: July 2002

We report on the growth of hydrogenated amorphous carbon (a-C:H) films, using a simple dc glow discharge plasma chemical vapor deposition method. A variety of complementary techniques were employed to analyze the properties of these films. a-C:H films having high fraction of tetrahedrally ( sp 3) bonded carbon atoms (~ 70%) and low hydrogen content (< 5at.%) were obtained. These films were characterized by a high optical bandgap ~ 2.7 eV, and refractive index (at 600nm) ~ 2.2. Growth of metastable diamond structure in a-C:H is attributed to energetic condensation of carbon containing ions in ( sp 3) configuration.
DIAMOND GROWN ON STEEL VIA IN-SITU FORMED INTERLAYERS
Authors: SHANG N. G. , MENG F. Y. , CHAN C. Y. , LI Q. , LEE C. S. , LEE S. T. , BELLO I.
Published: July 2002

Diamond films were grown on steel substrates by a hot filament chemical vapor deposition method without any special substrate pretreatment. When the deposition time was extended from 15 to 83 hrs and above, non-graphitic interfacial layers were formed below diamond films. The interfacial layers were solid and mediated good adherence of diamond films on steel substrates. The interfacial layers were found to be iron and chromium carbides with traces of oxygen as determined by chemical analysis using a scanning Auger microscopy (SAM). The carbide interfacial layers probably resulted from graphitic conversion processes. It is assumed that the graphitic conversion was established on chemical reaction pathways driven by thermal diffusion processes between the earlier formed graphitic layers and atomic constituents of the steel substrates.
Growth and Characterization of C-Axis Oriented YBa2Cu3O7-x/PrBa2Cu3O7-x Bilayers
Authors: Beneduce C. , Bobba F. , Boffa M. , Cucolo M. C. , Cucolo A. M. , Evers W.
Published: July 2002

We report on the preparation and characterization of YBa 2 Cu 3 O 7-x/ PrBa 2 Cu 3 O 7-x bilayers onto (100) SrTiO 3 substrates. The samples have been prepared by sequential dc sputtering processes in high oxygen pressure from stoichiometric targets. The structural characterization of the YBa 2 Cu 3 O 7-x and PrBa 2 Cu 3 O 7-x films and of the bilayers has been performed by means of X-ray diffraction. The Scanning Electron Microscopy analysis has showed that the film surfaces are flat and free of precipitates. A detailed study of the interfaces has been performed by Transmission Electron Microscopy analysis. The electrical resistivity measurements showed for the YBa 2 Cu 3 O 7-x films sharp superconducting transitions at 91.5 K and critical current density of about 106 A/cm 2 at 77 K, while for the PrBa 2 Cu 3 O 7-x films a semiconductor-like behavior has been observed.
AN ANALYTICAL APPROACH TO THE FREDRICKSON–ANDERSEN MODEL WITH VACANCIES
Authors: PIGORSCH C. , SCHULZ M. , TRIMPER S.
Published: July 2002

The dynamics of the n-spin facilitated kinetic Ising model (Fredrickson–Andersen model) with mobile vacancies as a model for the glassy materials are studied analytically by means of the Fock-space representation of the master equation. The system is mapped onto a three state model characterizing mobile, immobile and vacant cells. The characteristic cooperativity for glass forming systems are introduced by restrictions influencing the local dynamics and subsequently the local mobility of different lattice cells. In a moderate temperature regime the relaxation time versus the inverse temperature T-1 reveals two processes. Whereas the slow process can be identified with the conventional α-process of the supercooled liquid, the fast one originated by the additional empty sites is suggested to be the β JG -process due to Johari–Goldstein. The results are accordant with numerical simulations and suggest that the modified n-spin facilitated kinetic Ising model is able to describe qualitatively the behaviour of a supercooled liquid near the glass transition temperature T g .
Apply the Electrorheological Effect to Produce Three-Dimensional Photonic Crystals for Laser Applications
Authors: Tao R.
Published: July 2002

We have applied the electrorheological (ER) effect to produce three-dimensional (3-D) photonic crystals for laser applications. When polyester resin is in a strong electric field, bubbles are generated as a result of a chemical reaction. Because the resin has much high dielectric constant and conductivity than that of the bubbles, the bubbles are negatively polarized. Strong dipolar interactions force the bubbles align in the field direction to form chains and aggregate into a body-centered tetragonal lattice. This crystallization process can be controlled by varying the electric field strength, temperature, and amount of hardener. The final product, a 3-D photonic crystal, has good optical properties for laser applications.
TUNNELING EFFECTS EMERGING FROM MULTI-ELECTRON SYSTEMS IN SPATIALLY MODULATED NANOSTRUCTURES
Authors: UGAJIN RYUICHI
Published: July 2002

We can see tunneling effects in high-dimensional space through multi-particle states. This is because multi-particle states of quanta are defined in the configuration space with (DN)-dimensions, where N is the number of particles and D is the number of dimensions of our space, though we know the statistics of quanta affect the structure of quantum states. Two examples are reviewed: one is quasi-resonance due to electron–electron interaction in a pair of coupled quantum dots under an external electric field and the other is Hubbard-gap tunneling in which an electron tunnels through Mott insulating electrons in a quantum-dot chain under an overall confining potential.
CONDUCTIVE COPPER SULFIDE THIN FILMS ON POLYIMIDE FOILS FOR OPTICAL AND OPTOELECTRONIC APPLICATIONS
Authors: CARDOSO J. , GOMEZ-DAZA O. , IXTLILCO L. , NAIR M. T. S. , NAIR P. K.
Published: July 2002

Copper sulfide thin films of 75 nm and 100 nm thickness were coated on Kapton foils (PI) of 25 nm thickness by floating them on a chemical bath. The foils were annealed at 150°C-400°C in N 2 converting the coating from CuS to Cu 1.8 S . The sheet resistance of the annealed coatings (100 nm) is 10-50 ohms/square which is almost unaltered after immersion in dilute HCl for 30-120 min. The infrared reflectance predicted for the coatings is 67%-77% at a wavelength 2.5 μm, which is nearly what is experimentally observed. The coated PI has a transmittance (25-35%) peak located around 550-600 nm. These thermally stable conductive coatings on PI foils might be used as conductive substrates for optoelectronic device structures.
RBS ANALYSIS OF MBE GROWN SiGe/(001)Si HETEROSTRUCTURES WITH THIN HIGH Ge CONTENT SiGe CHANNELS FOR HMOS TRANSISTORS
Authors: BARRADAS N. P. , SEQUEIRA A. D. , FRANCO N. , MYRONOV M. , MIRONOV O. A. , PHILLIPS P. J. , PARKER E. H. C.
Published: July 2002

The growth of Si1-xGex quantum wells with high Ge composition (x>0.5) on Si(001) substrates by MBE is of great interest both for HMOS device applications and fundamental research. One of the possibilities to obtain a high Ge content Si1-xGex channel for mobile carriers, while retaining its strain, is to grow a relaxed Si1-yGey buffer layer on an underlying Si substrate. Such a buffer is termed a virtual substrate (VS), which is a constituent of SiGe metamorphic heterostructures. The effect of annealing on the structure of the Si(001)/VS/Si 0.7 Ge 0.3/ Si 0.2 Ge 0.8/ Si 0.7 Ge 0.3 heterostructures was studied by grazing angle of incidence RBS. The thickness of the Si 0.2 Ge 0.8 channel is inhomogeneous, which makes the analysis of the data by traditional means very hard. We have developed a model whereby the influence of the thickness inhomogeneity of each layer in the apparent energy resolution as a function of depth can be calculated. Automatic fits to the data were performed, and the roughness parameters, that is, the standard deviation of the thickness inhomogeneity of the relevant layers, were obtained, together with the thickness and stoichiometry of each layer. The results are compared with TEM and high resolution XRD experiments.
ION-BEAM CONTROL OF THIN-FILM MICROSTRUCTURAL COLUMNAR ANGLE
Authors: HODGKINSON IAN , WU QI HONG
Published: July 2002

The microstructural columnar angle of titanium oxide is shown to be rotated towards the vapor direction during oblique, ion-assisted deposition. The effect was found to increase with increasing ion energy, but experiments with the ion beam directed along and perpendicular to the tangent rule direction did not reveal dependence on the angle of incidence of the ions. The technique may allow access to deposition of biaxial materials in a regime where the columns run nearly parallel to the substrate.
CALCULATION OF SURFACE AREAS FOR POROUS SILICON
Authors: HOU Q. R. , CHI N.
Published: July 2002

Based on atomic force microscopy (AFM) images of porous silicon, a simple model has been proposed to calculate the surface areas of porous silicon. In this model, the porous silicon layer is assumed to be made of numerous identical cones with radius r and height h. The surface area changes due to the formation of porous silicon are found to be dependent on (h/r)2 and correlate with the growth of photoluminescence (PL) intensities. The rise and fall in photoluminescence intensity coincide with those of surface area changes qualitatively. This coincidence supports the hypothesis that the luminescence results from the presence of surface-localized or confined molecular emitters.
STABLE OSCILLATIONS AND DEVIL'S STAIRCASE IN THE VAN DER POL OSCILLATOR
Authors: GILBERT T. , GAMMON R. W.
Published: July 2002

A forced van der Pol relaxation oscillator is studied experimentally in the regime of stable oscillations. The variable parameter is chosen to be the driving frequency. For a range of parameter values, we show that the rotation number varies continuously from 0 to 1. This work provides experimental evidence that period-adding bifurcations to chaos previously reported by Kennedy and Chua are intimately connected to the existence of a regime of stable oscillations where the rotation number shows a Devil's-staircase structure.
NONLINEAR DISCRETE-TIME SYNCHRONIZATION VIA EXTENDED OBSERVERS
Authors: HUIJBERTS H. J. C. , LILGE T. , NIJMEIJER H.
Published: July 2002

A method is described for the synchronization of nonlinear discrete-time dynamics. The methodology consists of constructing observer–receiver dynamics that exploit at each time instant the drive signal and buffered past values of the drive signal. In this way, the method can be viewed as a dynamic reconstruction mechanism, in contrast to existing static inversion methods from the theory of dynamical systems. The method is illustrated on a few simulation examples consisting of coupled chaotic logistic equations. Also, a discrete-time message reconstruction scheme is simulated using the extended observer mechanism.
IMPLICIT APPROXIMATION OF A STABLE SADDLE MANIFOLD GENERATED BY A TWO-DIMENSIONAL QUADRATIC MAP
Authors: MIRA CHRISTIAN , ABDEL-BASET HEBA , EL-HAMOULY HASSAN
Published: July 2002

Consider the Henon's map Tb: (x→ 1-ax2+y, y→bx), the parameters (a, b) being such that |b|<1, with the existence of an attracting set A. This paper deals with an approximate implicit analytical representation of the stable manifold WS(q1) of the saddle fixed point q1 belonging to the basin boundary of the attracting set A. A method of successive approximations of iterative type is used from the definition of a "generating approximation" g0(x, y)=0 (approximation of order zero). In the case of absence of homoclinic points to q1, a generating approximation is defined from the two parabolas constituting the degenerate stable manifold in the (x, y) plane when b=0. Formally the result is extended when homoclinic points to q1 are created for b=0, i.e. the degenerate stable manifold WS(q1) is made up of infinitely many parabolas.
GLOBAL BASIN STRUCTURE OF ATTRACTION OF TWO DEGREES OF FREEDOM SWING EQUATION SYSTEM
Authors: HASEGAWA YOSHITAKA , UEDA YOSHISUKE
Published: July 2002

A model of a simple electric power system consisting of two generators operating onto an infinite bus is studied by numerical simulations. In many practical situations the proper concern of the engineer is the extent of the basin of attraction of the safe operating condition in phase space. However traditional analysis using energy function method can capture only the regions of sufficient conditions, so that geometrical concepts and theories of dynamical systems are recognized to be necessary tools to understand power system stability. In this paper, all equilibrium points and limit cycles are listed, and their locations are investigated with relation to basins. It will be helpful to globally grasp the total structure of the basins of attractions in phase space. Periodic orbits correspond to one or both generators operating in a desynchronized steady state, and if realized, rotors are destroyed. However their basins concern the study of the basin of the stable equilibrium point. Focusing on one of the generators, that is, identifying states of another generator, the basin portrait is similar to that of the single degree of freedom swing equations system. And in this view, basin erosions of synchronized state are understood in connection with an escape phenomena. Global basin structures are studied by taking systematic basin portrait sections. Note that we do not treat situations where inertia ratio between generators is very large as is seen in some reports using Melnikov's method.
APPLICATION OF ORDER PARAMETER EQUATIONS FOR THE ANALYSIS AND THE CONTROL OF NONLINEAR TIME DISCRETE DYNAMICAL SYSTEMS
Authors: LEVI P. , SCHANZ M. , KORNIENKO S. , KORNIENKO O.
Published: July 2002

This work is based on the concept of order parameters of synergetics. The order parameter equations describe the behavior of a system in the vicinity of an instability and are used here not only for the analysis but also for the control of nonlinear time discrete dynamical systems. Usually, the dimensionality of the evolution equations of the order parameters is less than the dimensionality of the original evolution equations. It is, therefore, convenient to introduce control mechanisms, first in the order parameter equations, and then to use the obtained results for the control of the original system. The aim of the control in this case is to avoid chaotic behavior of the system. This is achieved by shifting appropriate bifurcation points of a period-doubling cascade. In this work we concentrate on the shifting of only the first bifurcation point. The used control mechanisms are delayed feedback schemes. As an example the well-known Hénon map is investigated. The order parameter equation is calculated using both the adiabatic elimination procedure and the center manifold theory. Using the order parameter concept two types of control mechanisms are constructed, analyzed and compared.
APPLYING CASE-BASED REASONING TO SUPPORT DYNAMIC FRAMEWORK DOCUMENTATION
Authors: GÓMEZ-ALBARRÁN MERCEDES , GONZÁLEZ-CALERO PEDRO A.
Published: July 2002

From the framework-based application developer point of view, good documentation approaches are those that gather appropriate framework information (usage experiences, descriptive knowledge) and provide efficient mechanisms both for accessing the information represented and discovering new information from the initial one. From the framework developer point of view, documentation approaches involving a low development effort are preferable. This paper presents a Case-Based Reasoning approach for framework documentation whose retrieval and adaptation mechanisms help framework users in the access and discovery processes. The learning mechanism lets the user enrich the initial set of usage experiences, reducing thereby the initial documentation development effort.
LOCAL EXISTENCE OF SOLUTIONS TO THE TRANSIENT QUANTUM HYDRODYNAMIC EQUATIONS
Authors: JÜNGEL ANSGAR , MARIANI MARIA CRISTINA , RIAL DIEGO
Published: July 2002

The existence of weak solutions locally in time to the quantum hydrodynamic equations in bounded domains is shown. These Madelung-type equations consist of the Euler equations, including the quantum Bohm potential term, for the particle density and the particle current density and are coupled to the Poisson equation for the electrostatic potential. This model has been used in the modeling of quantum semiconductors and superfluids. The proof of the existence result is based on a formulation of the problem as a nonlinear Schrödinger–Poisson system and uses semigroup theory and fixed-point techniques.
THE LINEAR BOLTZMANN EQUATION FOR LONG-RANGE FORCES: A DERIVATION FROM PARTICLE SYSTEMS
Authors: DESVILLETTES L. , PULVIRENTI M.
Published: July 2002

In this paper we consider a particle moving in a random distribution of obstacles. Each obstacle generates an inverse power law potential εs/|x|s, where ε is a small parameter and s>2. Such a rescaled potential is truncated at distance εγ-1, where γ∈] 0, 1[ is suitably large. We also assume that the scatterer density is diverging as ε-d+1, where d is the dimension of the physical space.

We prove that, as ε→0 (the Boltzmann–Grad limit), the probability density of a test particle converges to a solution of the linear (uncutoff) Boltzmann equation with the cross-section relative to the potential V(x)=|x|-s.
INVARIANTS OF KNOT DIAGRAMS AND RELATIONS AMONG REIDEMEISTER MOVES
Authors: ÖSTLUND OLOF-PETTER
Published: July 2002

In this paper a classification of Reidemeister moves, which is the most refined, is introduced. In particular, this classification distinguishes some Ω3-moves that only differ in how the three strands that are involved in the move are ordered on the knot.

To transform knot diagrams of isotopic knots into each other one must in general use Ω3-moves of at least two different classes. To show this, knot diagram invariants that jump only under Ω3-moves are introduced.

Knot diagrams of isotopic knots can be connected by a sequence of Reidemeister moves of only six, out of the total of 24, classes. This result can be applied in knot theory to simplify proofs of invariance of diagrammatical knot invariants. In particular, a criterion for a function on Gauss diagrams to define a knot invariant is presented.
MODELLING ACETYLCHOLINESTERASE KINETICS: THE IDENTIFIABILITY PROBLEM IN PARAMETER ESTIMATION
Authors: ROSENBAUM ENRIQUE ARTURO , PECHEN DE D'ANGELO ANA MARÍA , BERGOC ROSA MARÍA , VENTURINO ANDRÉS
Published: July 2002

Acetylcholinesterase (E.C. 3.1.1.7) is a typical hydrolase showing substrate inhibition. Classical works stated a two-step kinetics for the catalytic mechanism. We analyse here a full interacting model for the substrate bound to an inhibitory site different to the catalytic one, in agreement with current tridimensional data. A mixed model derived from equilibrium-steady state analysis fits fairly well to experimental data. We conclude that both catalytic steps are susceptible of partial inhibition, with 15% of remaining activity for substrate saturated enzyme. Indeed, substrate inhibition would be preferentially exerted on one of the catalytic steps, leading to particular cases which fit to data as well. The parametric identity among the mathematical expressions from restricted models disables identifiability of kinetic constants solely by fitting to data. Thus, additional information is required from other experimental approaches. Based on the cited closeness between both rate constants for the substrate acetylthiocholine, dissociation constants at the catalytic and inhibitory sites are estimated in ~ 63 μM and ~ 0.35 mM respectively, while interaction between binding sites might enhance the latter up to 16 mM. We also emphasise the relevance of considering substrate inhibition in kcat extrapolations even at low substrate concentrations. Finally, we are able to predict total acetylated enzyme values in the order of those done from direct experimental measurements.
SCALING LAWS IN A TURBULENT BAROCLINIC INSTABILITY
Authors: SERIO C. , TRAMUTOLI V.
Published: July 2002

This work provides an empirical investigation of scaling laws in a cloud system generated and advected by a strong baroclinic instability. An infrared satellite image with a spatial (horizontal) resolution of about 1 km has been analyzed. The presence of two sizeable and unmistakable scaling regions, one extending from 1 to 15 km and characterized by a power law with an exponent close to 1, the other stretching from 20 km up to 100 km and characterized by a power law with exponent close to 1/3, have been revealed by variogram analysis. These two scaling laws are in agreement with the idea of scale invariance of the turbulent motion and also suggest the presence of a self-similar structure. To explore this possibility, wavelet transform analysis at different spatial scales has been used. Our findings are that self-similarity is present at the smallest scales, but this universal characteristic may be masked by non-universal effects which influence the homogeneity of the underlying turbulent motion. The implications of the two scaling exponents, 1 and 1/3, are also discussed.
PLANNING FOR ACCELERATED LIFE TESTS
Authors: TANG LOON-CHING
Published: July 2002

We present two alternative perspectives to the current way of planning for constant-stress accelerated life tests (CSALTs) and step-stress ALT (SSALT). In 3-stress CSALT, we consider test plans that not only optimize the stress levels but also optimize the sample allocation. The resulting allocations also limit the chances of inconsistency when data are plotted on a probability plot. For SSALT, we consider test plans that not only optimize both stress levels and holding times, but also achieve a target acceleration factor that meets the test time constraint with the desirable fraction of failure. The results for both problems suggest that the statistically optimal way to increase acceleration factor in an ALT is to increase lower stress levels and; in the case of CSALT, to decrease their initial sample allocations; in the case of SSALT, to reduce their initial hold times. Both problems are formulated as constrained nonlinear programs.
ATOMISTIC SIMULATION OF LASER ABLATION OF DIAMOND AND SILICON (111) SURFACE
Authors: WANG C. Z. , HO K. M.
Published: July 2002

Tight-binding molecular dynamics simulations are performed to study femtosecond-laser ablation of diamond and silicon (111) surface. The simulation results show that under intense ultrafast laser ablation the diamond (111) surface graphitizes while the silicon (111) surface melts spontaneously. All structural changes occur within a few hundred femtoseconds, which is much shorter than the typical lattice dynamics time scale, in consistent with experimental observations.
STRUCTURE OF Si(001)-(4×3)-In SURFACE STUDIED BY X-RAY PHOTOELECTRON DIFFRACTION
Authors: SHIMOMURA M. , NAKAMURA T. , KIM K.-S. , ABUKAWA T. , TANI J. , KONO S.
Published: July 2002

X-ray photoelectron diffraction (XPD) patterns of In 3d core levels have been measured for the Si(001)-(4×3)-In surface. An R factor analysis with single-scattering and multiple-scattering simulations of In 3d XPD patterns was performed for three structural models proposed so far. Only the model proposed by surface X-ray diffraction [Appl. Surf. Sci.123/124, 104 (1998)] appeared to give a reasonably small R factor when the geometric parameters were modified from the original ones.