bluuebunny/crossref_metadata_2025 huggingface dataset:
BRANE COSMOLOGY WITH A BULK SCALAR FIELD
Authors: RODRÍGUEZ-MARTÍNEZ M.
Published: October 2002

In the last few years, brane cosmological models with extra dimensions have been actively studied. In these scenarios, ordinary matter is confined in a (3+1)-dimensional surface (the world-sheet of a 3-brane) while gravity lives in the bulk space-time2,3. In this regard, it has been shown that the cosmology of such models is characterized by a non standard Friedmann equation4,5. Some analytic solutions have been found when the scalar field couples to the brane6, but they correspond to static solutions where the cosmological evolution is due to the motion of the brane into the bulk. In this talk I have presented two kinds of exact solutions obtained by solving Einstein's equations in the light-cone coordinate system and making two different assumptions : a. proportionality between the scalar field and the logarithm of the bulk scale factor7 and b. separable solutions. It has been shown that the first kind of solutions correspond to moving branes into static backgrounds : somehow the hypothesis of proportionality froze the evolution of the metric. On the contrary, in the second kind of solution the bulk is really dynamic. The induced cosmology in the brane has been explored for both types of solutions, confirming, in particular, the non standard cosmological evolution of the scale factor.
CAUSAL TENSORS AND RAINICH'S CONDITIONS
Authors: SENOVILLA J. M. M.
Published: October 2002

The mathematical properties of causal tensors,1 which are the tensors satisfying the dominant property (generalization of the dominant energy condition), were presented. The whole class of the so-called superenergy tensors2, including in particular the Bel-Robinson tensor, are causal tensors. Conversely, the superenergy tensors are the basic building blocks of all causal tensors1. Actually, the superenergy tensors of simple forms are intimately related to conformally Lorentz transformations as they leave the null cone invariant.1 This provides, in particular, a wide generalization of the algebraic Rainich conditions1 in arbitrary dimension and for many different fields. See 1,2 and references therein for details.
GENERALISED PSEUDO-RIEMANNIAN GEOMETRY FOR GENERAL RELATIVITY
Authors: STEINBAUER R. , KUNZINGER M.
Published: October 2002

The study of singular spacetimes by distributional methods faces the fundamental obstacle of the inherent nonlinearity of the field equations. Staying strictly within the distributional (in particular: linear) regime, as determined by Geroch and Traschen2 excludes a number of physically interesting examples (e.g., cosmic strings). In recent years, several authors have therefore employed nonlinear theories of generalized functions (Colombeau algebras, in particular) to tackle general relativistic problems1,5,8.

Under the influence of these applications in general relativity the nonlinear theory of generalized functions itself has undergone a rapid development lately, resulting in a diffeomorphism invariant global theory of nonlinear generalized functions on manifolds3,4,6. In particular, a generalized pseudo-Riemannian geometry allowing for a rigorous treatment of generalized (distributional) spacetime metrics has been developed7. It is the purpose of this talk to present these new mathematical methods themselves as well as a number of applications in mathematical relativity.
NUMERICAL TIME EVOLUTION OF INERTIAL MODES IN SLOWLY ROTATING NEUTRON STARS
Authors: VILLAIN L. , BONAZZOLA S.
Published: October 2002

A numerical and linear study of modes driven toward instability by PN radiation-reaction force (current quadrupole) in slowly rotating neutron stars was presented. It consists in a time evolution using spectral methods in spherical coordinates for spatial operators. Whatever the noisy initial data, there exists a hydrodynamic instability. Yet, depending on the background, the symmetric properties of the mode may change. Thus, in a rigid rotating Newtonian star, the expected and purely axial r-mode1 is growing. But, when the Newtonian background is assumed to be differentially rotating or when the evolution is done in the framework of general relativity with Cowling approximation (frozen spacetime), a coupling between axial and polar modes appears. Then, the mode driven to instability no longer belongs to one of these subclasses. Preliminary results were presented, showing the common features and main differences between Newtonian and relativistic cases2.
Charmonium Production in π- Be Collisions at 515 GeV/c
Authors: Jesik Rick
Published: October 2002

We have studied the production of the charmonium states J/ψ, ψ(2S), χc1, and χc2 in 515 GeV/c π- Be collisions in the Feynman-x range 0.1 < xF < 0.8. The χc states are observed through their radiative decays into J/ψ mesons. The resulting photons are reconstructed either as showers in the electromagnetic calorimeter or as e+e- pairs after conversion in the target and subsequent detection in the tracking system. The fraction of inclusive J/ψ production due to χc1 and χc2 decays is 0.443 ± 0.041 ± 0.035. The ratio of the χc1 to χc2 cross section is 0.57 ± 0.18 ± 0.06. Our results indicate that 0.454 ± 0.044 ± 0.042 of the inclusive J/ψ's are produced directly.
Charmonium Production in 800 GeV/c p-Si Interactions
Authors: Hagan Karla
Published: October 2002

Charmonium results are presented from Fermilab Experiment 771, proton-silicon interactions at [Formula: see text] with a fixed target spectrometer and dimuon trigger. Total and differential cross sections for J/ψ and ψ(2S) will be discussed, as well as a preliminary result on χ production.
Hadro-Production of Quarkonia in Fixed Target Experiments
Authors: Rothstein Ira Z.
Published: October 2002

In this talk I review the recent progress made in the calculations of quarkonia production in fixed target experiments. NRQCD organizes the calculations in a systematic expansion in αs and v, the relative velocity between the heavy quarks. Within this formalism there are octet contributions which are not included in the color singlet model. These contributions depend upon unknown matrix elements of local operators which are fit to the data. Using these fits, there are several predictions which do indeed improve agreement with the data. However, the prediction for the polarization of the produced states as well as the ratio of the χ1 to χ2 cross sections differ substantially from the data for the case of pion beams. Possible large corrections from higher twist effects are discussed as is the issue of the the proper choice of masses.
Quarkonium Production at DØ
Authors: Murphy C. R.
Published: October 2002

We present results on inclusive J/ψ production in the central and forward regions and ϒ production in the central region using dimuon data collected with the DØ detector during the 1992-1995 Tevatron collider run. Using muon impact parameters we have estimated the fraction of J/ψ mesons coming from B meson decays and inferred the inclusive b production cross section. We have also obtained the fraction of J/ψ events resulting from radiative decays of χc states. We discuss the implications of our measurements for quarkonium production processes.
Uses and Abuses of Quarkonium Theory
Authors: Cho Peter
Published: October 2002

We survey a few applications of recent theoretical ideas to problems in heavy quarkonium physics. We discuss the utility and limitations of fragmentation approximations for studying Psi and Upsilon production at several collider facilities. We also review the circumstances under which color-octet contributions to quarkonium cross sections are important. We emphasize that results obtained from methods stretched beyond their domains of validity should be regarded with caution.
Determining Color-Octet ψ-Production Matrix Elements from γp and ep Processes
Authors: Fleming Sean
Published: October 2002

We calculate, within the NRQCD factorization formalism, the leading color-octet contributions to ψ production in photon-nucleon and electron-nucleon collisions. The expressions we obtaine depend on the NRQCD matrix elements [Formula: see text] and [Formula: see text]. These matrix elements can be determined by fitting to experimental data. The color-octet contribution to ψ photoproduction is in the forward region of phase space, where there may be large corrections to the NRQCD result from higher twist terms. As to ψ leptoproduction we point out that the theoretical uncertainties plaguing the photoproduction calculation vanish in the large momentum transfer limit. In this region of phase space the NRQCD formalism should be valid, making ψ leptoproduction an ideal laboratory for testing the theory.
Heavy Quark Physics from Lattice NRQCD
Authors: Sloan John
Published: October 2002

I discuss recent lattice calculations of the spectroscopy of mesons containing only b and c quarks using the Non-Relativistic QCD (NRQCD) action for heavy quarks. I discuss the benefits of using a non-relativistic effective action in heavy quark calculations and the manner in which heavy quark systems are insensitive to the systematic errors common in lattice calculations. I discuss how these calculations can be used to determine the standard model parameters αs and mb by requiring that the calculated spectrum agree with experiment, and present our current estimates of these quantities.
Standard Model Physics from Quarkonia and Lattice QCD
Authors: Simone James N.
Published: October 2002

Quarkonia is studied in lattice QCD using Wilson heavy quarks improved to O(a) in the lattice spacing a. The quarkonia spectrum is compared to experiment and provides a check on lattice spacing errors. Careful attention to systematic errors in quarkonia permits determinations of the QCD coupling αs and the heavy quark masses.
Charmonium Spectroscopy in $\bar{p}p$ Annihilations
Authors: Zioulas George
Published: October 2002

We present a review of results from E760, a resonant charmonium formation experiment in the Fermilab Antiproton Accumulator. Experiment E835, a continuation of E760, and its physics goals are also presented.
Resonance Formation in Two-Photon Collisions in L3 at LEP
Authors: Van Rhee T.
Published: October 2002

The formation of quarkonium resonances in γγ collisions has been studied with the L3 detector at LEP, using data taken from 1991 to 1995. The η′ is observed in the channel π+ π-γ, and its two-photon width is measured. The Q2-dependence of the η′ formation cross section has been studied in the interval 0.015< Q2 <10.0 GeV2, and the form factor has been obtained. The charmonium state χc2 is identified through its decay to γJ/ψ, J/ψ→ e+e- or μ+μ-, and a preliminary value for the χc2 two-photon width is given.
EPR STUDY OF DEOXYGENATED Y1-xPrxBa2Cu3O7 (x = 0.0, 0.08, 0.20, 0.50, 1.00)
Authors: IKRAM M. , SINGH R. J.
Published: October 2002

EPR spectra of five compounds of Y 1-x Pr x Ba 2 Cu 3 O 7 with x = 0.0, 0.08, 0.20, 0.50, 1.00 are reported. Different types of spectra are observed after deoxygenation. The most important feature is the occurrence of the 4-line spectra (to which we assigned an electronic spin S = 2) obtained through superexchange among the four Cu 2+ ions (effected through the intervening oxygen ions in the clusters of (CuO) 4). This may be interpreted as the presence of Pr helps in breaking bonds and killing the superconductivity.
THE LOCAL STRUCTURE OF BISMUTH-BORATES CHARACTERIZED BY 11B MAS NMR
Authors: VASILESCU M. , SIMON S.
Published: October 2002

Bismuth-borate glasses and vitroceramics belonging to x Bi 2 O 3 · (100 - x) B 2 O 3 system, 0 ≤ x ≤ 93, doped with 0.5 mol% MnO are investigated by 11 B Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR). The 11 B MAS NMR results indicate the presence of three- and tetra-coordinated boron in all investigated bismuth borates. While the fraction of the tetra-coordinated boron present a large maximum in the range 20 ≤ x ≤ 60 in the bismuth-borate glasses, this maximum is reduced to the range 20 ≤ x ≤ 37.5 in the samples obtained after heat treatment. Crystalline phases are developed in the samples with high bismuth content, x ≥ 60, by heat treatment at 550°C, in which two types of three-coordinated boron are identified. The mean values of the NMR parameters like chemical shift, asymmetry parameter and quadrupolar coupling constant are less influenced by the bismuth/boron ratio, showing that boron structural units are relatively stable on the entire investigated composition range.
SELF-DUALITY IN MAXWELL–CHERN–SIMONS TYPE EFFECTIVE THEORIES
Authors: CHANDELIER FRÉDÉRIC , GEORGELIN YVON , MASSON THIERRY , WALLET JEAN-CHRISTOPHE
Published: October 2002

We consider a class of (2+1)-dimensional nonlocal effective models with a Maxwell–Chern–Simons part for which the Maxwell term involves a suitable nonlocality that permits one to take into account some (3+1)-dimensional features of "real" planar systems. We show that this class of models exhibits a hidden duality symmetry stemming from the Maxwell–Chern–Simons part of the action. We discuss and illustrate this result in the framework of a (2+1)-dimensional effective model describing (massive) vortices and charges with realistic interactions.
IMPEDANCE SPECTROSCOPY (IS), XRD AND SEM OF OXIDE-ADDED Si3N4
Authors: SIDDIQI SAADAT. A. , KHAN NASIR A. , ANWAR M. SABIEH
Published: October 2002

Impedance spectroscopy (IS) is a non-destructive technique used for obtaining valuable information about bulk conductivities, dielectric constants, phase composition and grain boundaries of important ceramic materials, amongst many others. We obtained Nyquist plots for four different hot-pressed Si 3 N 4 samples in two different frequency regimes: 1 Hz to 30 MHz and 1 kHz to 100 kHz. The information obtained was compared against results from scanning electron microscopy (SEM) and X-ray diffraction (XRD). The limitations of the frequency response techniques are also discussed.
INTERFERENCE EFFECT OF THREE BOSE–EINSTEIN CONDENSATES
Authors: ZHANG SUN , WANG FAN
Published: October 2002

The macroscopic interference of three Bose–Einstein condensates (BEC) is studied in this paper. The interference pattern between three condensates is given as a further demonstration of the existence of the global phase and the braking of U(1) gauge symmetry. Moreover, the difference between two and three condensates is also pointed out for further experiments.
A DISCRETE FULLY RECURRENT NETWORK OF SIGMOID UNITS FOR ASSOCIATIVE MEMORY AND PATTERN CLASSIFICATION
Authors: BROUWER ROELOF K.
Published: October 2002

Fully recurrent networks have proven themselves to be very useful as associative memories and as classifiers. However, they are generally based on units that have binary states. The effect of this is that data to be processed consisting of vectors in [Formula: see text] have to be converted to vectors in {0, 1}mwith m much larger than n since binary encoding based on positional notation is not feasible. This implies a large increase in number of components. This effect can be lessened by allowing more states for each unit in our network.

This paper describes two effective learning algorithms for a network whose units take the dot product of the input with a weight vector, followed by a tanh transformation and a discretization transformation in the form of rounding or truncation. The units have states that are in {0, 0.1, 0.2, …, 0.9, 1} rather than in {0, 1} or {-1, 1}. The result is a much larger state space given a particular number of units and size of connection matrix. Two convergent learning algorithms for training such a network to store fixed points or attractors are proposed. The network exhibits those properties that are desirable in an associative memory such as limit cycles of 1, attraction to the closest attractor and few transitions required to reach attractors. Since memories that are stored can be used to represent prototypes of patterns the network is useful for pattern classification. A pattern to be classified would be entered and its class would be the same as the class of the prototype to which it is attracted to which it is.
COMBINED CLASSIFICATION OF MULTIPLE VIEWS USING FACIAL CORNERS
Authors: GAO YONGSHENG , LEUNG MAYLOR K. H.
Published: October 2002

The profile view of a face provides a complementary structure that is not seen in the frontal view. The classification system combining both frontal and profile views of faces can improve the classification accuracy. And it would be more foolproof because it is difficult to fool the profile face identification by a mask. This paper proposes a new face recognition approach, which can be applied on both frontal and profile faces, to build a robust combined multiple view face identification system. The recognition employs a novel facial corner coding and matching method, and integrates the outline and interior facial parts in the profile matching. The proposed multiview modified Hausdorff distance fuses multiple views of faces to achieve an improved system performance.
A NEW EDGE PRESERVING BINARY IMAGES RESIZING TECHNIQUE
Authors: ZAHIR SAIF , WARD RABAB
Published: October 2002

Efficient methods for resizing two-dimensional binary signals are increasingly on demand for a variety of applications such as computer graphics, computer cartography, and machine generated text.2,4,6Recently, algorithms have been proposed such as those based on interpolation methods including nearest neighbor, linear, and Butterworth. Other methods such as splines,5wavelets, and DCT-based algorithms11,12are also presented. All these methods generate distortion and noticeable degradation in the quality of the signals (e.g., binary images) especially at and around edges. In this paper, we present a new near optimal edge preserving binary image resizing scheme that produces perceptually perfect edges. This scheme is based on edge detection, edge chain coding, edge code representation, and the uses of predetermined resizing patterns. The results obtained by this method show that the resized images are aesthetically and objectively much better than the results of other published methods.
A NEW FOUR-CC-BASED CONFIGURATION FOR REALIZING A VOLTAGE-MODE BIQUAD FILTER
Authors: SINGH ABDHESH K. , SENANI RAJ
Published: October 2002

A new voltage-mode (VM) biquad filter is presented, which employs four Current Conveyors (CC) along with five resistors and only two grounded capacitors, facilitates electronic control of filter parameters through grounded resistors (realizable by FETs/MOSFETs) and is suitable for IC implementation in bipolar or CMOS technology. The circuit offers several advantages over the four-CC-based VM biquads published earlier. The workability of the new circuit has been confirmed by PSPICE simulations.
GREEDY ALGORITHMS FOR THE TEST SELECTION PROBLEM IN PROTOCOL CONFORMANCE TESTING
Authors: CSÖNDES TIBOR , KOTNYEK BALÁZS
Published: October 2002

This paper presents a mathematical model for the test selection problem in protocol conformance testing, the goal of which is to select a suitable test set from a given test suite. The problem is described together with its mathematical formulation including two optimization problems and four different models for the coverage. The test selection problem is shown to be NP-hard. The Integer Programming transformation of the problems is also discussed. We propose greedy algorithms for the selection, which perform much better than the existing methods and can provide very good solutions as experimental results show.
ON THE MENDÈS FRANCE FRACTAL DIMENSION OF STRANGE ATTRACTORS: THE HÉNON CASE
Authors: PIACQUADIO M. , HANSEN R. , PONTA F.
Published: October 2002

We consider the Hénon attractor ℋ as a curve limit of continuous planar curves H(n), as n → ∞. We describe a set of tools for studying the Hausdorff dimension dim H of a certain family of such curves, and we adapt these tools to the particular case of the Hénon attractor, estimating its Hausdorff dimension dim H (ℋ) to be about 1.258, a number smaller than the usual estimates for the box-counting dimension of the attractor. We interpret this discrepancy.
STABILITY OF OBSERVER-BASED CHAOTIC COMMUNICATIONS FOR A CLASS OF LUR'E SYSTEMS
Authors: ALVAREZ-RAMIREZ JOSE , PUEBLA HECTOR , CERVANTES ILSE
Published: October 2002

In this paper, the stability of observer-based chaotic communications using Lur'e systems is presented. In this approach, the transmitter contains a chaotic oscillator with an input that is modulate by the information signal. The receiver is composed by a copy of the transmitter driven by a synchronization signal. Some effects of transmission noise on the demodulation procedure are discussed. Numerical simulations on Chua's circuit are provided to illustrate our findings.
CHUA'S PERIODIC TABLE
Authors: TONELLI R. , MELONI F.
Published: October 2002

An interdisciplinary analysis is presented in this paper on the relationship between the bifurcation behavior of chaotic systems, specifically Chua's circuit, and the quantized energy level of atoms. We show that it is possible to associate special capacitance values in Chua's circuits with the electronic energy levels Enof atoms calculated from Bohr's Law. In particular, these particular capacitance values correspond to the bifurcation points αnof Chua's circuits. We found a functional relation associating a specific Chua's circuit to the Hydrogen atom and obtained a map of "Atom" to " Chua's Circuit". This map can be extended to other elements in the Periodic Table, thereby demonstrating an almost universal relation between the two different physical systems. With this map we can calculate the energy levels of different atoms from bifurcation diagrams (or vice-versa) and express the analytical relations in terms of the two variables αnand En.
TEST AGENT SYSTEM
Authors: CHOI JEONGEUN , CHOI BYOUNGJU
Published: October 2002

In this paper, we propose a Test Agent System (TAS) that employs intelligent agent characteristics of autonomy, social ability, and intelligence to provide active assistance to the tester. It consists of the 'User Interface Agent', the 'Test Case Selection & Testing Agent', and the 'Regression Test Agent'. These agents carry out the tests autonomously by employing their intelligent rules in the object-oriented test processes. This system has 2 advantages. Firstly, since the tests are carried out autonomously, it minimizes tester interference and secondly, since redundant-free and consistent effective test cases are intellectually selected, the testing time is reduced while the fault detection effectiveness improves. In this paper, we show the cut-down rate on the testing time and improvement in the fault detection effectiveness through experiments.
A FORMAL FRAMEWORK TO SUPPORT WORKFLOW ADAPTATION
Authors: SHUZHOU LIU , SOONG ANGELA GOH ECK
Published: October 2002

A workflow system automates a business process, enabling documents, information and tasks to be passed among participants following a set of defined rules. The system needs to address changes that are frequently encountered in a complex heterogeneous environment. In such scenarios, a formal description of an adaptive workflow system will lead to greater reliability and clearer understanding of the entire system. Previous studies on workflow formalization have focused on specific perspectives, for example, deadlock and reachability in a workflow process. However, there is a close relationship between workflow components. Therefore a unifying description is an aid to understanding workflow behaviour. In this paper, the main workflow components are described in a unifying framework WfSL (Workflow Specification Language) through a combination of process algebra and Z specification. The former is used to describe workflow processes and the latter to specify the workflow information model and workflow organization model. An integration semantics is presented for data state transition and process state transition. The framework can be used for verifying workflow correctness when changes are made to the workflow.
POLYHEDRA WITH UNGUARDED INTERIORS
Authors: BINGER DAVID
Published: October 2002

A polyhedron may contain points not visible from any vertex. This paper shows that a polyhedron with this property may have as few as 16 vertices.
ON THE TIME BOUND FOR CONVEX DECOMPOSITION OF SIMPLE POLYGONS
Authors: KEIL MARK , SNOEYINK JACK
Published: October 2002

We show that a decomposition of a simple polygon having n vertices, r of which are reflex, into a minimum number of convex regions without the addition of Steiner vertices can be computed in O(n + r2 min {r2, n}) time and space. A Java demo is available at .
FINDING AN OPTIMAL BRIDGE BETWEEN TWO POLYGONS
Authors: TAN XUEHOU
Published: October 2002

Let π(a,b) denote the shortest path between two points a, b inside a simple polygon P, which totally lies in P. The geodesic distance between a and b in P is defined as the length of π(a,b), denoted by gd(a,b), in contrast with the Euclidean distance between a and b in the plane, denoted by d(a,b). Given two disjoint polygons P and Q in the plane, the bridge problem asks for a line segment (optimal bridge) that connects a point p on the boundary of P and a point q on the boundary of Q such that the sum of three distances gd(p′,p), d(p,q) and gd(q,q′), with any p′ ∈ P and any q′ ∈ Q, is minimized. We present an O(n log 3 n) time algorithm for finding an optimal bridge between two simple polygons. This significantly improves upon the previous O(n2) time bound. Our result is obtained by making substantial use of a hierarchical structure that consists of segment trees, range trees and persistent search trees, and a structure that supports dynamic ray shooting and shortest path queries as well.
TEST ELEMENTS IN FINITELY GENERATED ABELIAN GROUPS
Authors: ROCCA CHARLES F. , TURNER EDWARD C.
Published: October 2002

We determine which finitely generated abelian groups have test elements and give examples when they exist.
SIMULATION OF SOME QUANTUM MODELS FOR SEMICONDUCTORS
Authors: CAUSSIGNAC PH. , DESCLOUX J. , YAMNAHAKKI A.
Published: October 2002

Three different existing steady-state models with quantum correction for simulating the resonant tunnelling diode are summarized. Numerical methods and a theoretical argument for one of the models are briefly described. Results of simulation are focused on the capability of reproducing the negative differential resistivity.
CLOSURE OF THE SET OF DIFFUSION FUNCTIONALS WITH RESPECT TO THE MOSCO-CONVERGENCE
Authors: CAMAR-EDDINE M. , SEPPECHER P.
Published: October 2002

We characterize the functionals which are Mosco-limits, in the L2(Ω) topology, of some sequence of functionals of the kind [Formula: see text] where Ω is a bounded domain of ℝN (N ≥ 3). It is known that this family of functionals is included in the closed set of Dirichlet forms. Here, we prove that the set of Dirichlet forms is actually the closure of the set of diffusion functionals. A crucial step is the explicit construction of a composite material whose effective energy contains a very simple nonlocal interaction.
THOMAS–FERMI–DIRAC MODEL FOR LOW DENSITY STELLAR MATTER IN THE PRESENCE OF A STRONG QUANTIZING MAGNETIC FIELD
Authors: NAG NANDINI , CHAKRABARTY SOMENATH
Published: October 2002

The effect of strong quantizing magnetic field on low density stellar matter is investigated using Thomas–Fermi–Dirac (TFD) model. The Wigner–Seitz cell structure is assumed for the low density matter. The significant changes in the properties of such low density matter in presence of strong magnetic fields are discussed. It is seen that the decay time scale for magnetic field decreases by at least two orders of magnitude in such a model calculation.
OPTIMUM CONFIGURATION OF DETERMINING THE GRAVITATIONAL CONSTANT G WITH FOUR ATTRACTING MASSES
Authors: HU ZHONG-KUN , LUO JUN , WANG WEN-MIN
Published: October 2002

A configuration with four attracting masses in the determination of Newtonian gravitational constant G by the time-of-swing method is proposed. One couple of attracting masses is put in the outer space of the two attracted masses and another couple one is put in the inner space. Because the signals of the two couples of attracted masses will be superposed while the noises due to the uncertainty of the attracted masses separation will be compensated. There exists an optimum separation between the attracted masses, in which the requirement of measuring this separation can be reduced by a factor of about 400.
SPECTRAL CLASSIFICATION OF ARCHAEAL AND BACTERIAL GENOMES
Authors: NYEO SU-LONG , YANG I-CHING , WU CHI-HAO
Published: October 2002

The power spectra of the nucleotides in the coding and noncoding sequences of the complete genomes of twenty-two archaea and bacteria are obtained. According to the intensities at the periodicity of 3 bp in the spectra, it is observed that the genomic sequences may be classified into three types. Moreover, the spectra generally have a small but broad peak in the 10–11 bp periodicities. For the archaea, the peak is seen to locate preferably at about 10 bp periodicity, while for the bacteria, it tends to locate at about 11 bp. These features suggest that the DNA sequences of archaea generally have a tighter double helical structure than those of bacteria in order to cope with harsh environmental conditions. Besides, among the archaea, A. Pernixi K1 is found to have the largest periodicity of about 11 bp, but has a comparatively high CG content in its genome and hence a high denaturation temperature.
A NOVEL DEFUZZIFYING APPROACH TO CAR EVALUATION AND SELECTION UNDER FUZZY ENVIRONMENT
Authors: CHU TA-CHUNG , TSAO CHUNG-TSEN
Published: October 2002

This paper proposes a new method for ranking fuzzy numbers by difference between relative areas. Comparative examples illustrate the advantage of the proposed method. The ranking method is further applied to help establish a defuzzified multiple level FMADM model, which avoids the complicatied aggregation of fuzzy numbers so that the multiple level FMADM problem can be efficiently solved. A numerical example of car evaluation and selection illustrates the feasibility of the proposed model.
COMPARATIVE VERY-HIGH-RESOLUTION VUV SPECTROSCOPY: LASER SPECTROSCOPY OF O2
Authors: LEWIS B. R. , GIBSON S. T. , BALDWIN K. G. H. , DOOLEY P. M. , WARING K.
Published: October 2002

Despite their importance to the photochemistry of the terrestrial atmosphere, and many experimental studies, previous characterization of the Schumann–Runge (SR) bands of O 2, [Formula: see text] (1750–2050 Å) has been limited by poor experimental resolution. In addition, our understanding of the SR spectrum is incomplete, many rovibrational transitions in the perturbed region of the spectrum [B(v > 15)] remaining unassigned. We review new very-high-resolution measurements of the O 2 photoabsorption cross section in the SR bands. Tunable, narrow-bandwidth background vacuum-ultraviolet (VUV) radiation for the measurements (~ 7 × 105 resolving power) was generated by the two-photon-resonant difference-frequency four-wave mixing in Xe of excimer-pumped dye-laser radiation. With the aid of these cross-section measurements, rovibrational and line-shape analyses have led to new insights into the molecular structure and predissociation dynamics of O 2. The current VUV laser-spectroscopic measurements are shown to compare favourably with results from two other very-high-resolution experimental techniques, namely laser-induced fluorescence spectroscopy and VUV Fourier-transform spectroscopy, the latter performed using a synchrotron source.
VIBRATIONAL EXCITATION OF C 1s-IONIZED ETHANE
Authors: HERGENHAHN U. , KUGELER O. , RENNIE E. E. , RÜDEL A. , MARBURGER S.
Published: October 2002

The effects of interaction between the vibrational and electronic structure, so-called vibronic coupling, are reviewed in the context of core-ionized states. High resolution C 1s spectra of ethane and deuterated ethane are used as an example to compare our reasoning with measurements.
MAGNETIC COUPLING IN THIN LAYERS AND SUPERLATTICES INVESTIGATED BY RESONANT SCATTERING OF POLARIZED SOFT X-RAYS
Authors: SACCHI MAURIZIO , HAGUE CORYN F.
Published: October 2002

A short overview is given of recent developments in the use of resonant scattering of polarized soft X-rays to investigate magnetic materials. A few studies are chosen to exemplify possible applications in the field of thin films and ordered multilayer structures.
DIRECTIONAL TRANSPORT OF K ON CATALYTIC METAL SURFACES
Authors: GÜNTHER S. , MARBACH H. , LÜRSSEN B. , IMBIHL R. , GREGORATTI L. , BARINOV A. , KISKINOVA M.
Published: October 2002

Photoelectron emission and scanning photoelectron microscopies have been used to study the mass transport of potassium on the surface of a Rh(110) catalyst with Pt microstructures, induced by propagating chemical waves during the H 2 + O 2 reaction or by coadsorption of NO. Imaging the dynamic changes in the adsorbed layer, an energetically driven redistribution of K and formation of condensed coadsorbed patterns on the Rh(110) surface has been evidenced. The local composition of the different patterns on this spatially heterogeneous interface has been determined by microspot photoelectron spectroscopy, and the mechanism of the observed self-organization processes has been verified.
PROGRESS OF HIGH-RESOLUTION PHOTOEMISSION SPECTROSCOPY IN STRONGLY CORRELATED ELECTRON SYSTEMS
Authors: TAKAHASHI TAKASHI
Published: October 2002

Recent progress in the energy and momentum resolutions in photoemission spectroscopy (PES) is remarkable, enabling a new challenge to long-standing and/or current fundamental problems in the strongly correlated electron systems. We review the history, current status, and future of high-resolution PES by showing representative experimental results on high-temperature superconductors, low-dimensional materials and heavy fermion f electron compounds.
FINE-STRUCTURE SELECTIVE PREDISSOCIATION OF O2
Authors: LIEBEL H. , MÜLLER-ALBRECHT R. , LAUER S. , VOLLWEILER F. , EHRESMANN A. , SCHMORANZER H.
Published: October 2002

The OI [Formula: see text] emission cross section and the absorption cross section of O2 were investigated near the threshold for neutral dissociation into the OI [Formula: see text] state with a very narrow bandwidth (0.9 meV) of the exciting radiation. The fine-structure components of vibrational levels were resolved for the first time in the emission cross section. A certain degree of selectivity in the population of fine-structure components was observed.
STUDIES AND AB INITIO CALCULATIONS ON THE CHARACTERISTICS OF THE C STATE OF SF2
Authors: ZHOU XIAOGUO , YU SHUQIN , SHENG ZHENYU , MA XINGXIAO , LIU YAJUN , HUANG MINGBAO , LI QUANXIN
Published: October 2002

SF 2 radicals were generated by a pulsed dc discharge in a gas beam of SF 2 and Ar. The (2+1) resonance-enhanced multiphoton ionization (REMPI) excitation spectrum of SF 2 radical was obtained between 330 and 365 nm. The SF + cation signals were also observed in the same wavelength range. Ab initio calculations show that the C state is a predissociative state with Rydberg characteristics. The REMPI spectrum is assigned to a two-photon resonant excitation of the SF 2 radical (the B 1 B 1 and C 1 A 1 states). Potential energy curves of excited states of the SF 2 radical obtained by ab initio calculations suggest that SF + cations originate from the ionization of SF fragments yielded from the dissociation of the C state.
SYMMETRY BREAKING OF A SiF4 MOLECULE BY F 1s EXCITATION
Authors: OKADA KAZUMASA , TAMENORI YUSUKE , KOYANO INOSUKE , UEDA KIYOSHI
Published: October 2002

Angle-resolved ion yield spectroscopy revealed that ionic fragmentation of a Td symmetry molecule SiF 4 is anisotropic after F 1s photoexcitation. The anisotropic fragmentation is interpreted as being due to preferential bond rupture at the F 1s core-hole site. The probability of the bond rupture at the core-hole site is three times as large as those at other sites. The origin of the preferential bond rupture is discussed in terms of symmetry breaking due to dynamical core-hole localization.
BEAT STRUCTURE IN THE DOUBLY EXCITED RYDBERG STATES CONVERGING TO THE N = 2 THRESHOLD OF HELIUM
Authors: FOLLATH R. , Reichardt G. , SCHWARZKOPF O. , GUDAT W.
Published: October 2002

The N = 2 double excitation series of helium was examined with the high performance U125 plane grating monochromator at BESSY II set to a resolving power of 90 000. A hitherto unresolved beat structure in the principal series was observed at very high excitation levels. The beat can be explained by the mixing of two series converging to different ionization thresholds and having an energy spacing corresponding to the energy split between the 2p1/2 and the 2p3/2 level of singly ionized helium. This indicates that the electron interaction at high excitation levels must be described within the JK coupling scheme.
ALIGNMENT OF Ar+ IONS PRODUCED AFTER RESONANT AUGER DECAY OF Ar* 2p53d RESONANCES
Authors: MEYER M. , MARQUETTE A. , GRUM-GRZHIMAILO A. , FLESCH R. , RÜHL E.
Published: October 2002

Fluorescence spectra have been recorded in the wavelength region 300 nm ≤ λ(fluo) ≤ 500 nm after resonant 2p → 3d excitation of atomic Ar using monochromatic synchrotron light. The radiative emission is characterized by strong transitions from Ar + 3p 4 (1 S , 1 D , 3 P ) n ℓ ionic states. It is mainly assigned to processes of the type 3p 4 4d → 3p 4 4p and 3p 4 4p → 3p 4 4s . In addition, we have analyzed the degree of polarization of the fluorescence lines and we have determined the alignment of the Ar + ions, which are produced after the resonant Auger decay. In comparison to investigations based on photoelectron spectroscopy, the spectral analysis of the fluorescence provides complementary information about the electronic relaxation during the resonant Auger process and, in particular, it allows one to examine directly the remaining ion.
BEHAVIOR OF LINEWIDTHS IN RESONANT AUGER AND CASCADE AUGER PROCESSES
Authors: HEINÄSMÄKI S. , HUTTULA S.-M. , KUKK E. , AKSELA H.
Published: October 2002

We study the linewidths in cascade Auger spectra in synchrotron radiation experiments and discuss their dependence on the lifetimes of the discrete states and the experimental conditions. In particular we consider the possibility of manipulating the linewidths of the first step decay by tuning the bandwidth of the incoming photons. This may be used as an identification method in cases where the spectra from different decays are energetically overlapping. As an example we take the cascade process in Xe following the 4d5/2 → 6p resonant excitation.
THE EFFECTS OF ANNEALING OF A p-TYPE PHOTOLUMINESCENT POROUS SILICON IN VACUUM
Authors: SHIN H. J. , LEE M. K , HWANG C. C. , KIM K. J. , KANG T.-H. , KIM B. , KIM G. B. , HONG C. K. , LEE K. W. , KIM Y. Y.
Published: October 2002

The changes of the structure and chemical states of photoluminescent p-type porous silicon (PS) caused by annealing in vacuum were investigated with atomic force microscopy and X-ray photoemission spectroscopy. The relative intensities of the silicon dioxide and suboxide peaks increased with the annealing temperature. The average size of the fine crystallites of the as-prepared samples was 5–10 nm and became 50–100 nm after being annealed at 550°C. The cause of photoluminescence quenching upon annealing is discussed.
LUMINESCENCE PROPERTIES OF LiKGdF5 CRYSTALS DOPED WITH Er3+ AND Tm3+ AS PROMISING MATERIALS FOR VUV-EXCITED PHOSPHORS
Authors: MAKHOV V. N. , KHAIDUKOV N. M. , KIRM M. , ZIMMERER G. , LAM S. K. , LO D. , SUETIN N. V.
Published: October 2002

The spectroscopic properties of LiKGdF 5 crystals doped with Er 3+ or Tm 3+ and codoped with Dy 3+, Tb 3+ or Sm 3+, and of LiKYF 5 crystals doped with Er 3+ or Tm 3+ and codoped with Dy 3+ have been studied under excitation by vacuum ultraviolet (VUV) radiation. It has been found that in LiKGdF 5 crystals doped with Er 3+ or Tm 3+ the VUV energy absorbed by 4f–5d transitions in the Er 3+ or the Tm 3+ ion is nearly completely converted into the UV/visible emission. At least in the LiKGdF 5: Er 3+ crystal some part of such a conversion is due to the energy transfer from the 5d state of the Er 3+ ion to the neighboring Gd 3+ ion as a result of cross-relaxation giving rise to the emission of two UV/visible photons instead of one VUV quantum. LiKGdF 5 crystals doped with Er 3+ and codoped with Dy 3+, Tb 3+ or Sm 3+ can be considered as promising materials for phosphors excited by VUV radiation from noble gas discharge.
THE OPTIMAL FORMATION CONDITION OF CHROMIUM OXIDE THIN FILM ON STAINLESS-STEEL SURFACE
Authors: MOON SANGWOON , CHO BOKLAE , CHUNG SUKMIN , PARK CHONGDO , KIM KIJEONG , KANG TAIHEE , KIM BONGSOO
Published: October 2002

We investigated the various oxidation conditions of stainless-steel surface using synchrotron radiation photoemission spectroscopy. Stainless-steel samples are oxidized at 450–550°C in various oxygen partial pressures. Increasing the annealing temperature from 450°C to 550°C, the trivalent chromium concentration in the surface increased and iron oxides decreased. The PES spectra from stainless steels oxidized at 550°C show that there exists the critical oxygen partial pressure, [Formula: see text] Torr. Below this critical pressure, the oxide formed mainly consists of chromium oxide, while the oxide formed mainly consists of iron oxide above the critical pressure. The oxidation behavior is in good agreement with the Ellingham diagram (a free-energy/temperature diagram).
EFFECT OF THE ANNEALING TEMPERATURE ON THE ELECTRONIC AND ATOMIC STRUCTURES OF EXCHANGE-BIASED NiFe–FeMn BILAYERS
Authors: LEE J. M. , JAN J. C. , CHIOU J. W. , PONG W. F. , TSAI M.-H. , CHANG Y. K. , CHEN Y. Y. , WANG C. R. , LEE J. F. , YANG T. , LU Z. , LAI W. Y. , MAI Z. H.
Published: October 2002

In this study we measured the Fe, Mn, and Ni L2,3-edge X-ray absorption near-edge structure (XANES) and K-edge extended X-ray absorption fine structure (EXAFS) of the ferromagnetic (FM) NiFe and antiferromagnetic (AFM) FeMn bilayer films prepared with various annealing temperatures. The branching ratios of the white-line intensities in the Fe, Mn, and Ni L2,3-edges XANES spectra and consequently the magnetic properties of these exchange-biased FM NiFe - AFM FeMn bilayers are found to depend strongly on the annealing temperature. We find that the first peak in the Fe, Mn, and Ni K-edge EXAFS Fourier transform spectra are very similar, which suggests that the nearest-neighbor bond lengths among Fe, Mn, and Ni atoms are essentially the same in the NiFe–FeMn bilayers. However, the peaks at distances greater than ~ 3 Å appear to be sensitive to the annealing temperature especially for the Fe and Mn K-edge spectra, which suggests that annealing alters the atomic structures of the next-nearest-neighbor and more distant shells surrounding the Fe and Mn atoms in the NiFe–FeMn bilayers.
ABLATION OF POLY(METHYL METHACRYLATE) BY A SINGLE PULSE OF SOFT X-RAYS EMITTED FROM Z-PINCH AND LASER-PRODUCED PLASMAS
Authors: JUHA L. , KRÁSA J. , PRÄG A. , CEJNAROVÁ A. , CHVOSTOVÁ D. , ROHLENA K. , JUNGWIRTH K. , KRAVÁRIK J. , KUBEŠ P. , BAKSHAEV Yu. L. , CHERNENKO A. S. , KOROLEV V. D. , TUMANOV V. I. , TUMANOV M. I. , BERNARDINELLO A. , ULLSCHMIED J. , BOODY F. P.
Published: October 2002

The efficiency of ablation induced in poly(methyl methacrylate) (PMMA) by single soft X-ray pulses emitted from Z-pinch and laser-produced plasmas was determined. X-ray ablation of PMMA was found to be less efficient than that of teflon (PTFE). Nonthermal effects of the radiation on the polymer structure play a key role in the mechanisms of the ablation, i.e. the ablation can be explained by the formation of radiation-chemical scissions of the polymer chain followed by blowoff of low-molecular fragment fluid into the vacuum. The most promising application of this phenomenon seems to be micropatterning/micromachining.
PHOTOINDUCED PHASE TRANSITION OF A SPIN-CROSSOVER COMPLEX STUDIED WITH THE COMBINATION OF SR AND LASER
Authors: TAKAHASHI KAZUTOSHI , KAMADA MASAO , DOI YO-ICHIRO , FUKUI KAZUTOSHI , TAYAGAKI TAKESHI , TANAKA KOICHIRO
Published: October 2002

We have performed a photoemission study on an organometal spin-crossover complex, [ Fe(2-pic) 3] Cl 2 EtOH , using the combination of synchrotron radiation and laser. The core-level and valence-band photoemission spectra were measured for high-spin, low-spin, and photoinduced phases. The N 1s and valence-band spectra showed remarkable changes due to the photoinduced phase transition, indicating that the electron charge was transferred from nitrogen to iron at the photoinduced phase transitions. It was also found that the valence-band structure of the photoinduced phase is very different from that of the high-spin phase caused by the thermally induced phase transition.
PHOTOELECTRON-SPECTROSCOPIC STUDY OF CORE-EXCITON DECAY IN AUGER-FREE LUMINESCENCE MATERIAL BaF2
Authors: KAMADA MASAO , ITOH MINORU
Published: October 2002

The nonradiative decay processes of the Ba -5p core exciton in BaF 2 have been investigated by using photoelectron spectroscopy, since the exciton peak is missing in the excitation spectrum of the Auger-free luminescence. The decay probability of the direct recombination process estimated from the constant-initial state spectrum and the absorption coefficient was found to be smaller than unity, indicating the existence of the other decay processes. It is suggested that the Ba -5p core exciton is relaxed by about 0.9 eV.
VUV PHOTOELECTRON DYNAMICS IN PURE CESIUM HALIDE AND IMPURITY (Tl AND Na) DOPED CsI; ABSOLUTE PHOTOEMISSION TOTAL YIELD, AUGER FREE LUMINESCENCE, AND STE LUMINESCENCE
Authors: EJIRI ARISATO , KUBOTA SHINZOU
Published: October 2002

Absolute photoemission total yield (APTY) spectra and VUV-excited luminescence in cesium halides of CsCl, CsBr, and CsI, as well as in Tl-doped and Na-doped cesium iodide, were studied at several temperatures from 400 K to 80 K in the VUV region (5–30 eV). Although it is common that the intensities of APTY exceed unity in the photon energy region exciting Cs + 5p core electron in all of these halides at room temperature, this is most in the cesium iodides and most less in CsCl. These phenomena are explained in terms of Auger enhancement due to the Auger effect associated with the decay process of the Cs + 5p core hole. From the detailed analysis of temperature dependence of APTY and of Auger free luminescence (AFL) in CsCl and CsBr, a strong complementary relation between APTY and AFL was revealed, and the temperature-dependent energy level diagram of CsBr including the valence band and the Cs + 5p core level was proposed. While in these CsI, APTY indicate as large as 1.5 or more at the high temperature and the decrease of APTY for decreasing temperature can be commonly explained in terms of the complementary relation with photoluminescence.
SOFT X-RAY ABSORPTION SPECTRA OF THE LITHIUM PHTHALOCYANINE RADICAL
Authors: OKAJIMA TOSHIHIRO , FUJIMOTO HITOSHI , SUMITOMO MICHINORI , ARAKI TOHRO , ITO EISUKE , ISHII HISAO , OUCHI YUKIO , SEKI KAZUHIKO
Published: October 2002

In near edge X-ray absorption fine structure (NEXAFS) spectra of carbon (C) and nitrogen (N) K-edge regions were measured for the stable radical compound lithium phthalocyanine (LiPc). The observed spectra were compared with those of metal free Pc ( H 2 Pc ), copper Pc (CuPc), and zinc Pc (ZnPc). The spectral features in the C K-edge region of LiPc were different from those of other Pcs in the low photon energy region. An additional peak around 283.5 eV was observed only in the spectrum of LiPc. On the other hand, the spectral features of these MPcs in the N K-edge region were similar and did not show a corresponding extra peak. These results were explained by the patterns of molecular orbitals of these Pcs and the selection rules of X-ray absorption in the localized core-hole picture. The extra peak observed in the C K-edge region is assigned to the excitation from C1s to the highest occupied molecular orbital (HOMO), which is only singly occupied due to the radical nature of the phthalocyanine ring. Group-theoretical consideration indicated that the transition from N1s to the HOMO is not allowed, and this explains the lack of an extra peak at the N K-edge.