bluuebunny/crossref_metadata_2025 huggingface dataset:
PROBING CKM PARAMETERS THROUGH UNITARITY, εK AND ΔMBd,s
Authors: RANDHAWA MONIKA , GUPTA MANMOHAN
Published: July 2002

A recently carried out unitarity based analysis1,2 involving the evaluation of Jarlskog's rephasing invariant parameter J as well as the evaluation of the angles α, β and γ of the unitarity triangle is extended to include the effects of [Formula: see text] as well as [Formula: see text] mixings. The present analysis attempts to evaluate CP violating phase δ, |Vtd| and the angles α, β and γ by invoking the constraints imposed by unitarity, [Formula: see text] and [Formula: see text] mixings independently as well as collectively. By invoking the "full scanning" of input parameters, as used by Buras et al., our analysis yields the following results respectively for δ and |Vtd|, unitarity: 50°±20° (in I quadrant), 130°±20° (in II quadrant) and 5.1 × 10-3 ≤ |Vtd| ≤ 13.8 × 10-3, unitarity and εk: 33° ≤ δ ≤ 70° (in I quadrant), 110° ≤ δ ≤ 150° (in II quadrant), 5.8 × 10-3 ≤ |Vtd| ≤ 13.6 × 10-3, unitarity and Δmd: 30° ≤ δ ≤ 70°, 6.4 × 10-3 ≤ |Vtd| ≤ 8.9 × 10-3. Incorporating all the constraints together, we get 37° ≤ δ ≤ 70°, 6.5 × 10-3 ≤ |Vtd| ≤ 8.9 × 10-3, the corresponding ranges for α, β and γ are, 80° ≤ α ≤ 124°, 15.1° ≤ β ≤ 31° and 37° ≤ γ ≤ 70°, again in agreement with the recent analysis of Buras et al. as well as with other recent analyses. Our analysis yields 0.50 ≤ sin 2β ≤ 0.88, in agreement with the the recently updated BABAR results. This range of sin 2β is in agreement with the earlier result of BELLE, which however has a marginal overlap only with the lower limit of recent BELLE results. Interestingly, our results indicate that the lower limit of δ is mostly determined by unitarity, while the upper limit is governed by constraints from Δmd.
SELF-ENERGY IN THE GOTT-HISCOCK SPACE-TIME
Authors: KHUSNUTDINOV NAIL R. , BEZERRA VALDIR B.
Published: July 2002

We calculate the self-energy for an electrically charged particle at rest in the background of Gott-Hiscock cosmic string space-time. The self-energy continuously falls down out-ward from string's with maximum at the origin of the string. The plots of the numerical of the self-energy and the height of barrier are shown.
CASIMIR ENERGY AND VACUA FOR SUPERCONDUCTING BALL IN SUPERGRAVITY
Authors: BURINSKII ALEXANDER
Published: July 2002

Casimir energy for solid conducting ball is considered on the base of some finite models. One model is physical and built of a battery of parallel metallic plates. Two finite models are based on the Higgs model of superconductivity. One of them is supersymmetric and based on the Witten field model for superconducting strings. Treatment shows that contribution of Casimir energy can be very essential for superdence state in the neutron stars and nuclear matter.
VACUUM POLARIZATION IN QED WITH WORLD-LINE METHODS
Authors: SHAISULTANOV R.
Published: July 2002

The application of world-line techniques to calculation of the vacuum polarization and effective action in scalar and spinor QED with external arbitrary constant electromagnetic field configuration is presented.
PHONON INDUCED SUPPRESSION OF THE ZEEMAN SPLITTING IN POLAR SEMICONDUCTOR QUANTUM DOTS: A QUANTUM SIZE EFFECT
Authors: MUKHOPADHYAY SOMA , CHATTERJEE ASHOK
Published: July 2002

The effect of the electron–phonon interaction on the Zeeman splitting of the first excited level of a two-dimensional parabolic quantum dot is studied using the nondiagonal Hartree–Fock variational approximation within the framework of Green's function formalism for the entire range of the electron–phonon interaction strength and arbitrary confinement length. The results are applied to GaAs and CdS quantum dots and it is shown that polaronic interaction can cause a strong size-dependent suppression of the Zeeman splitting in these dots if their sizes are made sufficiently small.
STRUCTURE OF THE Cu-NQR SPECTRUM IN Hg-1223 BETWEEN 4.2 K AND 145 K
Authors: BREITZKE H. , LÜDERS K. , GIPPIUS A. A. , ANTIPOV E. V.
Published: July 2002

An extremely low noise RF preamplifier cooled with liquid helium has been developed and is used to perform Cu-NQR measurements for Hg-1223 (T c =134 K ) at temperatures from 4.2 K to 145 K. At temperatures from 4.2 K to 20 K the spectra are centered at 15 MHz with a spectral width of approximately 2 MHz, similar to the Cu-NQR spectra of the other members of the HgBa 2 Ca n -1 Cu n O 2 n +2+δ series. The Cu-NQR spectra in this temperature range exhibit some features indicating an unresolved splitting but they can still be fitted quite well by a set of two pairs of 63/65 Cu lines, as expected for the 1223 structure. The spectra at 40 K and above clearly show a structure that can not be fitted suitable by a set of two pairs of 63/65 Cu lines. However, a fit with a set of four pairs of 63/65 Cu lines is in good agreement with the experimental results. Furthermore, the spectra at 80 K, 85 K and 90 K show a strong variation with respect to each other which might indicate a structural change like the formation of a superstructure, as discussed for other high-T c compounds, instead of a simple disorder in the crystal lattice.
ANOMALOUS MAGNETORESISTANCE OF BOROCARBIDE SUPERCONDUCTOR YNi2B2C
Authors: CHU RAMBIS K. , ZHANG Z. H. , CHU W. K. , MILLER J. H.
Published: July 2002

We have carried out the measurements of the magnetoresistance (MR) of YNi 2 B 2 C single crystals (T c =15.3 K and H c 2(5.5 K)~4.7 T ) in a wide range of temperature and magnetic field, T c +1<T<T c +145 K and 0<H<8 T . In the normal state, the in-plane MR, Δρ(H, T)=ρ(H, T)-ρ(0, T), changes from negative to positive as the temperature decreases. A pronounced sign-reversal is observed at T=80 K with H=4 T . A negative MR supports the presence of magnetically-related scattering and could signify considerable suppression of the spin fluctuations most likely associated with nearly magnetic metals in the presence of an external field. Such novel behavior reveals the possibility of pseudo-gap formation, which plays the role of unconventional superconducting mechanism, as indicated by the recent 11 B and 13 C NMR studies [1]. Our results are also in quantitative agreement with the short-range magnetic moment dependence upon temperature and applied field.
PHOTOINDUCED IR ABSORPTION IN AMnO3 AS A FUNCTION OF THE A SITE IONIC SPECIES
Authors: MERTELJ T. , HROVAT M. , KUSCER D. , MIHAILOVIC D.
Published: July 2002

A comparison of photoinduced absorption spectra in AMnO 3 with A = La 3+, Nd 3+, Ca 2+ is presented. The spectra are analyzed in the framework of photon assisted polaron hopping. In contrast to LaMnO 3 and NdMnO 3 the photoinduced absorption spectrum of CaMnO 3 shows distinct contributions from photoexcited holes and electrons. Both contributions are identified, and our results imply that magnitude of electron-phonon coupling constant for electrons in Mn eg orbitals in CaMnO 3 is significantly smaller than in LaMnO 3.
ULTRAFAST DYNAMICS OF THERMAL AND NONTHERMAL STRUCTURAL CHANGES IN METALS
Authors: GUO CHUNLEI , TAYLOR ANTOINETTE J.
Published: July 2002

Although structural phase changes in metals are a vital problem due to its fundamental importance as well as wide applicability in materials processing and manufacturing, the underlying physics of this process is still not fully understood and remains only at a phenomenological level. The study of the dynamics associated with structural changes only becomes possible recently with advances of femtosecond laser techniques. In this paper, we discuss our experimental results in the ultrafast dynamics of structural changes in metals induced by both thermal and nonthermal processes by monitoring materials states through their transient dielectric constants. These results lead to a more complete understanding of the physical mechanism of structural phase changes in metals.
FLUCTUATIONS AND CORRELATIONS IN POPULATION MODELS WITH AGE STRUCTURE
Authors: HOWARD MARTIN , ZIA R. K. P.
Published: July 2002

We study the fluctuations and correlations in a stochastic age-structured population model. Our model, which is closely related to certain "bit-string" models of evolution, incorporates survival probabilities that are density dependent, and also allows for varying reproductive probabilities as a function of age. We first solve for the simple steady-state of the deterministic version of our model, where all fluctuations and correlations are neglected. We then develop analytic techniques to calculate stochastic Gaussian corrections around this deterministic solution. This allows for a systematic, perturbative calculation of the population fluctuations and correlations. Away from the bifurcation point of the deterministic model we find good agreement with Monte–Carlo simulations.
ITINERANT AND LOCALIZED STATES IN STRONGLY CORRELATED SYSTEMS BY A MODIFIED MEAN-FIELD SLAVE-BOSON APPROACH
Authors: CAPPELLUTI EMMANUELE
Published: July 2002

The standard mean field slave-boson solution for the infinite-U Hubbard model is revised. A slightly modified version is proposed which includes properly the incoherent contribution of the localized states. In contrast to the standard mean field result, this new proposed solution defines a unique spectral function to be used in the calculation of local and not local quantities, and satisfies the correct thermodynamic relations. The same approach is applied also to the mean field approximation in terms of Hubbard operators. As a byproduct of this analysis, Luttinger's theorem is shown to be fulfilled in a natural way.
SIMULATION OF THE RESPONSE OF AMORPHOUS SELENIUM TO LIGHT
Authors: Zhang Xiaodong , Drabold D. A.
Published: July 2002

We investigated the physical mechanism of dynamical bond formation, light-created defect centers and light induced electron spin resonance for Se chains and a realistic model of amorphous selenium by ab-inito molecular dynamic simulation. It is found that the Coloumb interaction between light-created charge centers plays the key role in the bond breaking, switching and reconstruction in Se chain and a-Se under the light irradiation.
4π CONFOCAL MICROSCOPE FOR MUTLIPHOTON OPTICAL SECTIONING OF GaN FILM LUMINESCENCE
Authors: UCER K. B. , LIANG DIFEI , WILLIAMS R. T. , MORKOC H.
Published: July 2002

In the 4π confocal microscope developed by S. W. Hell et al, laser light coherently illuminates both sides of a thin sample through a pair of high-NA objectives, effectively producing a single standing-wave fringe of 2-photon fluorescence excitation with weak side lobes. Developed initially for biological applications, the 4π microscope of Hell et al demonstrated 75 nm axial resolution with 810 nm light. We have constructed a 4π confocal multiphoton microscope for 3d analysis of band-edge/excitonic photoluminescence in thin films. Excitation is with 130 fs pulses from a Ti:sapphire laser. Instrumental features and preliminary tests with rhodamine and GaN and InN films are reported.
ELECTRO-ABSORPTION SPECTROSCOPY AND SEMI-EMPIRICAL MOLECULAR ORBITAL CALCULATIONS OF POLAR RETINOID ANALOGUES
Authors: HASHIMOTO HIDEKI , HATTORI KINGO , YAMADA TAKASHI , KOBAYASHI TAKAYOSHI
Published: July 2002

Nonlinear polarizabilities of a series of polar retinoid analogues were determined experimentally by means of electro-absorption (Stark) spectroscopy. The dependence of the magnitude of nonlinear polarizabilities on polyene chain-lengths as well as on the strength of electron-accepting groups was systematically compared. Semi-empirical molecular orbital calculations using AM1 Hamiltonian (MNDO-AM1 method) could quantitatively predict the second (β) and the third (γ) order nonlinear polarizabilities of the present set of molecules except for the γ value of C20BDCInd. The real and imaginary parts of χ(3)(-ω;0,0,ω) spectra were calculated in order to account the figure of merit of the third-order nonlinear optical material.
TIME-RESOLVED PHOTOLUMINESCENCE OF EXCITONS IN HgI2
Authors: OHNO N. , WEN X. M.
Published: July 2002

The time-resolved photoluminescence (TRPL) of red HgI 2 single crystal has been measured to determine the carrier lifetimes and to reveal the energy relaxation of excitons. Sharp near-bandgap luminescence lines due to free and bound excitons are observed at 530 nm, and a broad luminescence band appears at 630 nm at low temperatures. TRPL experiments of the near-bandgap luminescence have revealed that the luminescence comprise fast (30 to 200 ps) and slow (100 to 400 ps) decay components, showing several relaxation processes in free and bound exciton annihilation. TRPL of the broad band at 630 nm has shown that the luminescence is ascribed to the radiative recombination of donor-acceptor (DA) pairs.
GENERALIZED GINSPARG–WILSON ALGEBRA AND INDEX THEOREM ON THE LATTICE
Authors: FUJIKAWA KAZUO
Published: July 2002

Recent studies of the topological properties of a general class of lattice Dirac operators are reported. This is based on a specific algebraic realization of the Ginsparg-Wilson relation in the form γ5 (γ5D) + (γ5D)γ5 = 2a2k+1(γ5D)2k+2 where k stands for a non-negative integer. The choice k = 0 corresponds to the commonly discussed Ginsparg-Wilson relation and thus to the overlap operator. It is shown that local chiral anomaly and the instanton-related index of all these operators are identical. The locality of all these Dirac operators for vanishing gauge fields is proved on the basis of explicit construction, but the locality with dynamical gauge fields has not been fully established yet.
TURBULENT COLD PLASMA: AN EXACTLY PATH INTEGRAL SOLUTION IN A ZERO DIMENSIONAL MODEL AND ITS GENERALIZATIONS TO THE THREE-DIMENSIONAL-CASE
Authors: BOTELHO LUIZ C. L.
Published: July 2002

We write path integrals exact solutions for a 0-dimensional noise (turbulent) force equation for an electronic plasma. We obtain that the equilibrium limit of the plasma tensor magneto conductivity coincides with the classical non-turbulent result in our 0-dimensional proposed model.

Additionally, we show the usefulness of our reduced model by writing exact path integrals solutions for the probabilistic turbulent plasma occupation times. Finally, we point out three-dimensional generalizations of our path integral studies in two appendix.
Stochastic Aspects of Bridging Bonds of Induced Structure of Electro-Rheological Fluids in Shear Flow
Authors: Riha P. , Kimura H. , Takimoto J. , Koyama K.
Published: July 2002

The bridging of electrodes by clusters of polarizable elements occurs to be a dominant feature of the response of certain electrorheological fluid suspensions and liquid polymeric blends to the imposed electric field. The evolution of the bridging structure in deformation and flow is described as a stochastic process and identified with the macroscopic flow behavior. The effect of structure is introduced into the rheological equation providing its non-linear modification. The comparisons are presented showing how the proposed rheological equation describes rheological characteristics measured at steady shearing flow and start-up shearing flow.
Pressure Response of ER Fluids between Two Parallel-Plate Electrodes
Authors: Tsukiji Tetsuhiro , Hori Ken-Ichi
Published: July 2002

The frequency response of the pressure drop of the ER fluids between two parallel-plate electrodes to sine-wave changes in the applied electric field is investigated for constant flow rates. The electrodes gap is set at 2mm. The ER fluids used in the present study consist of cellulose suspended in silicone oil. Unipolar and bipolar sinusoidal electric fields, and constant ones are used. The frequency of the electric fields is changed from 0.1 to 1000Hz. The averages and the amplitudes of the pressure drop are measured. Dependence of the pressure drop on electrical excitation frequency is investigated. Furthermore the microscopic behavior of ER suspension structure between two fixed electrodes is visualized for the flowing ER fluids with high speed video camera under application of the electric fields. The effect of electrical change on the pressure drop is discussed from the results of the flow visualization.
COMPUTER SIMULATION STUDY OF A NEMATOGENIC LATTICE MODEL BASED ON THE NEHRING–SAUPE INTERACTION POTENTIAL
Authors: HASHIM R. , ROMANO S.
Published: July 2002

By now, nematogenic lattice models have been extensively studied in the literature; they usually involve cylindrically symmetric (uniaxial) particles and isotropic interaction potentials defined by even functions of the scalar products between unit vectors defining their orientations; anisotropic interaction potentials involving other scalar invariants, i.e. also depending on the orientations of the two particles with respect to the intermolecular vector, have been considered far less often. A model of the latter kind was proposed by Nehring and Saupe over 25 years ago; we have considered here its restriction to nearest neighbours, having the form [Formula: see text] Here the three-component vectors xj∈ Z3define centre-of-mass coordinates of the particles, and ukare three-component unit vectors defining their orientations; ∊ is a positive quantity setting energy and temperature scales (i.e. T*=kBT/∊); this model is seen to be the anisotropic counterpart to the generic Lebwohl–Lasher lattice model.

The model has been addressed by simulation; comparisons are reported with other anisotropic lattice models recently studied in the literature.
45° REFLECTOMETRY OF SEMICONDUCTOR QUANTUM WELLS
Authors: SILVA-CASTILLO A. , PEREZ-RODRIGUEZ F.
Published: July 2002

We have applied the 45° reflectometry for the first time to study exciton-polaritons in quantum wells. The 45° reflectometry is a new polarization-modulation technique, which is based on the measurement of the difference [Formula: see text] between the p-polarization reflectivity (Rp) and the squared s-polarization reflectivity [Formula: see text] at an angle of incidence of 45°. We show that [Formula: see text] spectra may provide qualitatively new information on the exciton-polariton modes in a quantum well. These optical spectra turn out to be very sensitive to the zeros of the dielectric function along the quantum-well growth direction and, therefore, allow to identify the resonances associated with the Z exciton-polariton mode. We demonstrate that 45° reflectometry could be a powerful tool for studying Z exciton-polariton modes in near-surface quantum wells, which are difficult to observe in simple spectra of reflectivity Rp
ABOUT KINKS IN AlGaAs LASERS LIGHT-CURRENT CHARACTERISTIC
Authors: SÁNCHEZ M. , GONZÁLEZ J. C. , DÍAZ P. , PEÑA-SIERRA R. , ESCOBOSA A.
Published: July 2002

The origin of the kinks in semiconductor lasers light-current characteristic (L(l)) is theoretically alld experimentally analyzed. The devices are straight separate confinement heterostructure lasers. We have developed a model to calculate L(l) which considers two thermal loss mechanisms: the leakage current and Auger recombination. It is shown that the kinks in the light-current characteristic appear at temperatures at which the considered mechanisms crossover.
Effects of Tin Addition to the Tl-Based 1223 Superconducting System
Authors: Wang Y. T. , Hermann A. M.
Published: July 2002

Polycrystalline samples of Tl-based-1223 superconducting system were prepared with tin-addition to form ( Tl 0.5 Pb 0.5) Sn x Sr 1.6 Ca 2.4 Cu 3 O y, for x=0–0.3. X-ray diffraction data showed the presence of a minor 1212 phase and impurities which increased with increasing x while the samples without addition of tin, x=0, were nearly single phase of Tl,Pb-1223. The effects of tin addition to Tl,Pb-1223 on the magnetic properties were studied by dc susceptibility and hysteresis magnetization measurements. The magnetic results revealed a significant enlargement of hysteresis magnetization in tin-added samples with an onset transition temperature drop of only 1–4 K. According to recent measurements, the intragrain Jc reflects the transport critical current density in high field region. The critical current density in Tl,Pb-1223 was enhanced by as much as ten-times by tin-addition. An electron micro-probe technique was employed to locate the added tin in the samples, but Sn incorporated into the superconducting phase was below detectability. The variation in Tc with Sn addition and a reduction in pinning strength at Sn concentration above x=0.05 show that the enhanced pinning is due to introduction of pinning centers into the superconducting phase even though micro-probe analysis indicates that most of the Sn is present in a nonsuperconducting phase. The field dependence and time dependence of the magnetization data showed an increased concentration of pinning centers without a change in pinning energy.
EFFECTS OF Y AND RARE EARTH IONS SUBSTITUTION for Ca in (Bi,Pb):2223 SUPERCONDUCTOR
Authors: POP A. V. , ILONCA GH. , BORODI G. , DEAC I. G. , GERU I. I. , KONOPKO L. A. , GERU V. I.
Published: July 2002

The effects of partial substitution of Ca by R = Y 3+, Eu 3+ and Er 3+ on the structural and electrical properties in the ceramic superconductor ( Bi 1.6 Pb 0.4) ( Sr 1.8- Ba 0.2) ( Ca 1-x R x)2, Cu 3 O y(x = 0, 0.02) has been investigated. Substitutions by Y, Lu and Er in Ca site induced the decrease of volume fraction for the "2223" phase and the increase of "2212" and "2201" volume phases fractions. Above the excess conductivity region, all samples are characterized by a linear temperature dependence of electrical resistivity. The rate of depression for critical transition temperature in x = 0.02 samples is found to be almost the same for all substituents. The nature of T c suppresion may be attributed to the increase of oxygen content in Bi 2 O 2 double layers with increasing Y and rare earth concentration.
GENERATING ISOTROPIC DISCRETE WAVES ON CELLULAR AUTOMATA
Authors: FESCHET FABIEN , TOUGNE LAURE
Published: July 2002

Cellular automata are a massively parallel computation model with discrete time and local rules. They are well adapted to biological or physical simulations. However, they are intrinsically anisotropic. The possibility of computing isotropic figures on cellular automata such as circles has already been proved.4 Moreover, the previous construction enables to compute all the major discretizations known in the literature. We present in this article an extension of this work to the construction of spheres in three dimensions. A local characterization of a sphere is presented based upon the relationship between spheres and circles. This leads to the possibility of constructing a family of concentric discrete spheres in real time. Moreover, the approach can use many discretization schemes leading to the construction of various discrete spheres as done for circles.
CONTENT-BASED INDEXING OF VOLUMETRIC IMAGES USING PRINCIPAL COMPONENT ANALYSIS
Authors: HUO CHONGYAN , BHATTACHARYA PRABIR
Published: July 2002

We present an indexing method for volumetric images using the Principal Component Analysis. The scatter plot of the first two components is used to develop a signature of the image set. Using this signature we can compare and recognize various images effectively. We have implemented the proposed method on a number of biomedical images.
RESONANCE-LIKE PHENOMENA IN ARRAYS OF RÖSSLER OSCILLATORS UNDER CORRELATED PARAMETRIC FLUCTUATIONS
Authors: LORENZO M. N. , PÉREZ-MUÑUZURI V. , DEZA R. , CABRERA J. L.
Published: July 2002

The behavior of diffusively coupled Rössler oscillators parametrically perturbed with an Ornstein–Uhlenbeck noise is analyzed in terms of the degree of synchronization between the cells. A resonance-like behavior is found as a function of the noise correlation time, instead of the noise intensity as it occurs in the typical stochastic resonance. A power law scaling between the "optimum" correlation time with regard to synchronization and the deterministic time scale of the oscillators has been obtained, with an exponent that depends on the coupling strength.
CELLULAR NEURAL NETWORKS CAN MIMIC SMALL-WORLD NETWORKS
Authors: YANG TAO , CHUA LEON O.
Published: July 2002

Small-world phenomenon can occur in coupled dynamical systems which are highly clustered at a local level and yet strongly coupled at the global level. We show that cellular neural networks (CNN's) can exhibit "small-world phenomenon". We generalize the "characteristic path length" from previous works on "small-world phenomenon" into a "characteristic coupling strength" for measuring the average coupling strength of the outputs of CNN's. We also provide a simplified algorithm for calculating the "characteristic coupling strength" with a reasonable amount of computing time. We define a "clustering coefficient" and show how it can be calculated by a horizontal "hole detection" CNN, followed by a vertical "hole detection" CNN. Evolutions of the game-of-life CNN with different initial conditions are used to illustrate the emergence of a "small-world phenomenon". Our results show that the well-known game-of-life CNN is not a small-world network. However, generalized CNN life games whose individuals have strong mobility and high survival rate can exhibit small-world phenomenon in a robust way. Our simulations confirm the conjecture that a population with a strong mobility is more likely to qualify as a small world. CNN games whose individuals have weak mobility can also exhibit a small-world phenomenon under a proper choice of initial conditions. However, the resulting small worlds depend strongly on the initial conditions, and are therefore not robust.
CAUCHY PROBLEM FOR A MODEL SYSTEM OF THE RADIATING GAS: WEAK SOLUTIONS WITH A JUMP AND CLASSICAL SOLUTIONS
Authors: KAWASHIMA SHUICHI , NISHIBATA SHINYA
Published: July 2002

This paper deals with the global existence and the time asymptotic state of solutions to the initial value problems for the system derived from approximating a one-dimensional model of a radiating gas. When the spatial derivative of the initial data is larger than a certain negative critical value, a unique solution exists globally in time. But if it is smaller than another negative critical value, the spatial derivative of the corresponding solution blows up in a finite time. Thus it is natural to think about weak solutions in a suitable sense. As a prototype of weak solutions, we consider the Cauchy problem with the Riemann initial data of which the left state is larger than the right state. This condition ensures the existence of the corresponding traveling wave, connecting the left state and the right state asymptotically. This Riemann problem admits a global weak solution, provided that the magnitude of the initial discontinuity is smaller than 1/2. Although the solution has a discontinuity, we have the uniqueness of a solution in weak sense by imposing the entropy condition. Furthermore, the magnitude of the discontinuity contained in the solution decays to zero with an exponential rate as the time t goes to infinity. Also, the solution approaches the corresponding traveling wave with the rate t-1/4 uniformly. The first result is obtained by the maximal principles. To show the second result, we have used an energy method with some estimates, which are also obtained through maximal principles.
ON THE REGULARITY OF THREE-DIMENSIONAL ROTATING EULER–BOUSSINESQ EQUATIONS
Authors: BABIN A. , MAHALOV A. , NICOLAENKO B.
Published: July 2002

The 3-D rotating Boussinesq equations (the "primitive" equations of geophysical fluid flows) are analyzed in the asymptotic limit of strong stable stratification. The resolution of resonances and a nonstandard small divisor problem are the basis for error estimates for such fast singular oscillating limits. Existence on infinite time intervals of regular solutions to the viscous 3-D "primitive" equations is proven for initial data in Hα, α≥ 3/4. Existence on a long-time interval T* of regular solutions to the 3-D inviscid equations is proven for initial data in Hα, α > 5/2 (T*→∞ as the frequency of gravity waves →∞).
GEOMETRIC INTERPRETATIONS OF QUANDLE HOMOLOGY
Authors: CARTER J. SCOTT , KAMADA SEIICHI , SAITO MASAHICO
Published: July 2002

Geometric representations of cycles in quandle homology theory are given in terms of colored knot diagrams. Abstract knot diagrams are generalized to diagrams with exceptional points which, when colored, correspond to degenerate cycles. Bounding chains are realized, and used to obtain equivalence moves for homologous cycles. The methods are applied to prove that boundary homomorphisms in a homology exact sequence vanish.
BAROTROPIC THIN SHELLS WITH LINEAR EOS AS MODELS OF STARS AND CIRCUMSTELLAR SHELLS IN GENERAL RELATIVITY
Authors: ZLOSHCHASTIEV KONSTANTIN G.
Published: July 2002

The spherically symmetric thin shells of the barotropic fluids with the linear equation of state are considered within the frameworks of general relativity. We study several aspects of the shells as completely relativistic models of stars, first of all the neutron stars and white dwarfs, and circumstellar shells. The exact equations of motion of the shells are obtained. Also we calculate the parameters of the equilibrium configurations, including the radii of static shells. Finally, we study the stability of the equilibrium shells against radial perturbations.
NUCLEON-NUCLEON AND HYPERON-NUCLEON INTERACTIONS
Authors: SATO S. , UEDA T.
Published: July 2002

The nucleon-nucleon and hyperon-nucleon interactions are studied by the one-boson-exchange(OBE) potential with the vertex form factor. To make our theory as relativistic as possible, we calculate the OBE-potential in the momentum space and use the Blankenbecler-Sugar equation. We also treat the singularity in the multichannel Blankenbecler-Sugar equation. By these formulations, we analyze the nucleon-nucleon and the hyperon-nucleon scatterings.
APPLICATION OF AN APPROXIMATE INVERSION METHOD TO SHORT-RANGED POTENTIALS
Authors: BÁTHORY B. , JESGARZ S. , SCHEID W. , APAGYI B.
Published: July 2002

The performance of a recent inversion scheme due to Ramm is investigated by applying it to the case of short-ranged potentials relevant in nuclear physics. It is shown that the sphere of validity of the Ramm inversion method is the same as the Born approximation.
DISCOVERY OF LONG-LIVED SHAPE ISOMERIC STATES WHICH DECAY BY STRONGLY RETARDED HIGH-ENERGY PARTICLE RADIOACTIVITY
Authors: MARINOV A. , GELBERG S. , KOLB D.
Published: July 2002

The reaction28Si +181Ta has been studied at ELab=125 and 135 MeV. Coincidences between high energy particles from abnormally long-lived states and various X- and γ-rays were observed, e.g. 7.8–8.6 MeV α-particles with γ-rays of a superdeformed band, 5.1–5.5 MeV α-particles with X- and γ-rays of W, Re and Pt, and 3.88 MeV particles (interpreted as protons) with 185.8 keV γ-rays. The data are interpreted in terms of the production of long-lived (t1/2of several months) high spin isomeric states in the second well of the potential in the parent nuclei, which decay to the normal states in the daughters, and in the third well of the potential, which decay to the second well.
LONG-RANGE CORRELATIONS IN THE PHASE-SHIFTS OF NUMERICAL SIMULATIONS OF BIOCHEMICAL OSCILLATIONS AND IN EXPERIMENTAL CARDIAC RHYTHMS
Authors: DE LA FUENTE I. M. , MARTINEZ L. , AGUIRREGABIRIA J. M. , VEGUILLAS J. , IRIARTE M.
Published: July 2002

In biochemical dynamical systems during each transition between periodical behaviors, all metabolic intermediaries of the system oscillate with the same frequency but with different phase-shifts. We have studied the behavior of phase-shift records obtained from random transitions between periodic solutions of a biochemical dynamical system. The phase-shift data were analyzed by means of Hurst's rescaled range method (introduced by Mandelbrot and Wallis). The results show the existence of persistent behavior: each value of the phase-shift depends not only on the recent transitions, but also on previous ones. In this paper, the different kind of periodic solutions were determined by different small values of the control parameter. It was assessed the significance of this results through extensive Monte Carlo simulations as well as quantifying the long-range correlations. We have also applied this type of analysis on cardiac rhythms, showing a clear persistent behavior. The relationship of the results with the cellular persistence phenomena conditioned by the past, widely evidenced in experimental observations, is discussed.
THE VARIATIONAL INDIRECT BOUNDARY ELEMENT METHOD: A STRATEGY TOWARD THE SOLUTION OF VERY LARGE PROBLEMS OF SITE RESPONSE
Authors: SÁNCHEZ-SESMA FRANCISCO J. , VAI ROSSANA , DRETTA ELINA
Published: July 2002

Boundary integral equation approaches and their discretization into boundary element methods (BEM) have been useful to obtain solutions for numerous problems in dynamic elasticity. Well documented advantages over domain approaches are dimension reduction, relatively easy fulfillment of radiation conditions at infinity, and high accuracy of results. In spite of dimension reduction, the computational cost at high frequencies may easily exceed the capacity of computing facilities. To overcome this problem, Galerkin's ideas may be used. The Indirect Boundary Element Method (IBEM) equations are the starting point of the proposed methodology. The boundary force density is expanded in terms of a complete set of functions. Weighting functions from the same complete set are used to minimize the error of this approximation. Once a significant subset is selected, the size of the resulting linear system is much smaller than that of the IBEM method as currently applied. Moreover, with appropriate trial functions, some matrix operations can be reduced to Fourier transformations.

In what follows, the formulation and some examples for scalar problems are presented. Simple 2-D topographies are studied, but the extension to 3-D realistic configurations may well be treated on the same basis.
SAFETY ASSESSMENT MODEL OF SOFTWARE FOR FAILURE DIAGNOSIS SYSTEMS
Authors: KOHDA TAKEHISA , INOUE KOICHI
Published: July 2002

The software for a failure diagnosis system can be represented in terms of production rules; the condition part represents a system failure condition and the conclusion part corresponds to a cause of the system failure or an appropriate protective action to be taken. This paper proposes a safety assessment model of the software to evaluate its contribution to the risk caused by the entire failure diagnosis system. The proposed risk criterion considers not only the reliability of hardware components of the failure diagnosis system, but also the reliability characteristics of the system to be monitored. Conventional verification and validation methods of rule-based systems assume that the software reliability can be achieved by maintaining the consistent relation between condition parts and conclusion parts. However, the risk criterion derived in this paper shows that the software for a failure diagnosis system cannot be optimized without considering these environmental factors.
SURFACE COSEGREGATION OF CHROMIUM AND SULFUR IN SINGLE CRYSTALLINE AUSTENITICFe–Ni–CrALLOYS
Authors: DZIAKOVA A. , CLAUBERG E. , UEBING C. , JANOVEC J.
Published: July 2002

In this work we have studied cosegregation of sulfur and chromium on well-defined austenitic Fe–Cr–Ni alloy surfaces. For this purpose we have investigated (100)-oriented surfaces of Fe–14.8%Cr–17.8%Ni(cS=9 wt-ppm) and Fe–18%Cr–14%Ni (cS=18 wt-ppm) single crystals using Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). Segregation experiments were carried out under UHV conditions at temperatures ranging from 500 to 900°C. Cosegregation of chromium and sulfur is very pronounced on the Fe–14.8%Cr–17.8%Ni(100) alloy surface, while on Fe–18%Cr–14%Ni(100) the surface concentration of cosegregated chromium is rather small. On both surfaces sulfur segregation is characterized by a c(2 × 2) LEED pattern. The results of the present study are compared with a previous study using ferritic Fe–15%Cr–S(100) alloy single crystals.
DIRECT OBSERVATIONS OF THE SURFACE ATOMIC STRUCTURE OF THE Si(111)-(7 × 7) RECONSTRUCTED SURFACE WITH KIKUCHI ELECTRON HOLOGRAPHY
Authors: CHANG C. Y. , SHEN T. S. , CHOU Y. C. , WEI C. M.
Published: July 2002

More than 50 symmetry-inequivalent emitter–scatterer (E–S) pairs were observed for the Si (111)-(7 × 7) surface using Kikchi electron holography (KEH) with various incident/detection configurations. For different configurations, the E–S pairs in the backscattering direction are preferentially enhanced. Thus, one can obtain detailed structural information by changing the incident/detection direction, which will be helpful in sorting out the correct surface structure model.
NORMAL KINEMATICS OF THE INTEROSSEOUS MEMBRANE DURING FOREARM PRONATION-SUPINATION — A THREE-DIMENSIONAL MRI STUDY
Authors: Nakamura Toshiyasu , Yabe Yutaka , Horiuchi Yukio , Seki Tsuneo , Yamazaki Nobutoshi
Published: July 2002

We studied in vivo dynamic shape changes of the interasseous membrane (IOM) during forearm rotation using three-dimensional magnetic resonance imaging (3D-MRI), and simultaneously analysed 3D-motion of the forearm rotation. Wavy deformities were seen in the IOM in the pronated position, and similar small changes were also seen at maximum supination (average 82°) and in the neutral position. These dynamic changes mainly occurred in the membranous part of the IOM, whereas the tendinous part demonstrated minimal dynamic changes during rotation in all subjects. On the dorsal aspect, deformity around the dorsal oblique cord was seen at maximum pronation. From this 3D-MRI observation, the tendinous part is considered to be taut during rotation to provide stability between the radius and ulna, because of its straightness and less dynamic changes. The more deformable membranous part is important to allow for smooth rotation, since it lies at a distance from the rotation axis. Inelasticity developing in the membranous part from trauma may pre-dispose to pronation-supination contracture. The radius rotated around the ulna from maximum supination to 45° pronation. At maximum pronation (average 75°), the radius translated average 1.8 mm palmarly and rotated average 4.0° ulnarward on the ulna. Incongruity of the distal radioulnar joint, contraction of the pronator quadratus and torsion between the radius and ulna at maximum pronation may produce this irregular motion of the radius and cause the dynamic changes of the IOM.
VULNERABILITY OF THE GRADUALLY ELONGATED NERVE TO COMPRESSION INJURY
Authors: Ikeda Kazuo , Yokoyama Mitsuteru , Tomita Katsuro , Tanaka Shigenori
Published: July 2002

The purpose of this study is to clarify the vulnerability of the gradually elongated peripheral nerve. Rabbit's sciatic nerves were gradually elongated to 30 mm at the rate of 2.0 mm/day and 4.0 mm/day. Immediately after elongation, the sciatic nerve was exposed and compressed for 30 minutes at various forces, 15, 30 and 60 g/0.1 cm2. Immediately after elongation and compression, 2, 4 and 8 weeks after compression, each group was electrophysiologically and histologically estimated — 15 g/0.1 cm2 caused no damage to the control group, neurapraxia to the 2.0 mm/day group, and axonotmesis to the 4.0 mm/day group; 30 g/0.1 cm2 caused neurapraxia to the control group and axonotmesis to the 2.0 mm/day group; 60 g/0.1 cm2 caused axonotmesis to the control group and slowly recovered axonotmesis to the 2.0 mm/day group. This study shows that though mild compression, does not cause nerve injury to the intact nerve, it can sometimes cause severe damage to the gradual elongated nerve.
Pawnbroking in Singapore
Authors: Lim Ghee-Soon , Lye Soo-Choon
Published: July 2002

Started in 1875, pawnbroking was a unique small business sector in Singapore. Its core business activity comprised giving out loans to walk-in pawners who presented valuables as collateral (pledges). Pawnbrokers made most of their profits from the interest differentials between the interests charged on the loans and the cost of capital of providing the loans. They were allowed to auction off unredeemed pledges through approved auction houses to recover their losses. Pawnbrokers were also allowed to purchase unredeemed pledges that had been pawned with themselves at the auction. About 90% of the pledges accepted by pawnbrokers thus were gold and jewelry.

This case provides a detailed description of the pawnbroking industry in Singapore and the operations of pawnbrokers. The case is useful for teaching in areas such as industry analysis, company operation and human resource management.
A NETWORK MODEL FOR FOREIGN EXCHANGE ARBITRAGE, HEDGING AND SPECULATION
Authors: JONES C. KENNETH
Published: July 2002

This paper presents alternative approach to foreign exchange market trading decisions. The model is equally applicable to the arbitrage practices of international banks, to the hedging decisions of multinational corporations, to the investment decisions of currency fund managers and to the uncovered positions of currency speculators. By using a network model to represent these situations complex problems can be modeled and the optimization problem required to maximize profit or eliminate risk can be accurately formulated.
NOISE-INDUCED UNIDIRECTIONAL TRANSPORT
Authors: MILSTEIN G. N. , TRETYAKOV M. V.
Published: July 2002

Constructive conditions for existence of unidirectional transport are given for systems with state-dependent noise and for forced thermal ratchets. Using them, domains of parameters corresponding to unidirectional transport are identified. Some results of numerical experiments are presented.
THE DENSITOMETRIC RESPONSE OF THE HIGH SENSITIVE GAFCHROMIC FILM EXPOSED TO X-RAYS
Authors: ODERO D. O.
Published: July 2002

Tests have been performed on the high sensitive (HS) GAFChromic film to evaluate its densitometric response to external X-rays (photon beam). Several 2 cm by 2 cm pieces of HS and MD-55-2 GAFChromic films were prepared and irradiated for sensitivity comparison, and X-rays energy dependence study. The optical densities of three irradiated pieces of HS film were measured as a function of time to establish the time taken for the optical density to stabilize. The densitometric sensitivity curves comparison showed that the HS film is twice as sensitive as its predecessor, MD-55-2, more spatially uniform and dosimetric measurements can be made with high precision. Its sensitivity is independent of 6 MV and 15 MV X-ray beam energies and its optical density is stable after about 36 hours post-irradiation time.
RANDOM MULTIPLICATIVE RESPONSE FUNCTIONS IN GRANULAR CONTACT NETWORKS
Authors: MOUKARZEL CRISTIAN F.
Published: July 2002

The contact network of a frictionless polydisperse granular packing is isostatic in the limit of low applied pressure. It is argued here that, on disordered isostatic networks, displacement–displacement and stress–stress static Green functions are described by random multiplicative processes and have a truncated power-law distribution, with a cut-off that grows exponentially with distance. If the external pressure is increased sufficiently, excess contacts are created, the packing becomes hyperstatic, and the abovementioned anomalous properties disappear because Green functions now have a bounded distribution. Thus, the low-pressure, isostatic, limit is a critical point.
SUBWAVELENGTH OPTICAL DEVICES FOR NANOMETER SCALE APPLICATIONS
Authors: GIRARD C. , DEREUX A. , QUIDANT R. , DES FRANCS G. COLAS , WEEBER J. C.
Published: July 2002

Recent progress in near-field optics instrumentation led to a new class of subwavelength optical experiments in which it is intended to use either the optical tunnel effect (OTE) or the lower mode based transmission (LMBT) in order to control the optical transfer between several delocalized detection or injection centers. This paper presents a panel of new theoretical and experimental results computed or observed near various dielectric or metallic patterns, linear, curved, or dashed, integrated in coplanar geometry. In particular, we demonstrate, how an efficient control of light evanescent waves can allow structures of subwavelength cross sections to be addressed.
Distributed, object-based programming systems
Authors: Chin Roger S. , Chanson Samuel T.
Published: July 2002

The development of distributed operating systems and object-based programming languages makes possible an environment in which programs consisting of a set of interacting modules, or objects, may execute concurrently on a collection of loosely coupled processors. An object-based programming language encourages a methodology for designing and creating a program as a set of autonomous components, whereas a distributed operating system permits a collection of workstations or personal computers to be treated as a single entity. The amalgamation of these two concepts has resulted in systems that shall be referred to asdistributed,object-based programming systems.

This paper discusses issues in the design and implementation of such systems. Following the presentation of fundamental concepts and various object models, issues in object management, object interaction management, and physical resource management are discussed. Extensive examples are drawn from existing systems.
Numerical comparisons of some explicit Runge-Kutta pairs of orders 4 through 8
Authors: Sharp P. W.
Published: July 2002

We performed numerical testing of six explicit Runge-Kutta pairs ranging in order from a (3,4) pair to a (7,8) pair. All the test problems had smooth solutions and we assumed dense output was not required. The pairs were implemented in a uniform way. In particular, the stepsize selection for all pairs was based on the locally optimal formula. We tested the efficiency of the pairs, to what extent tolerance proportionality held, the accuracy of the local error estimate and stepsize prediction, and the performance on mildly stiff problems. We also showed, for these pairs, how the performance could be altered noticeably by making simple changes to the stepsize selection strategy. As part of the work, we demonstrated new ways of presenting numerical comparisons.
—From the Author's Abstract
Tolerating failures of continuous-valued sensors
Authors: Marzullo Keith
Published: July 2002

One aspect of fault-tolerance in process control programs is the ability to tolerate sensor failure. This paper presents a methodology for transforming a process control program that cannot tolerate sensor failures into one that can. Issues addressed include modifying specifications in order to accommodate uncertainty in sensor values and averaging sensor values in a fault-tolerant manner. In addition, a hierarchy of sensor failure models is identified, and both the attainable accuracy and the run-time complexity of sensor averaging with respect to this hierarchy is discussed.
Self-stabilization
Authors: Schneider Marco
Published: July 2002

In 1973 Dijkstra introduced to computer science the notion of self-stabilization in the context of distributed systems. He defined a system as
self-stabilizing
when “regardless of its initial state, it is guaranteed to arrive at a legitimate state in a finite number of steps.” A system which is not self-stabilizing may stay in an illegitimate state forever. Dijkstra's notion of self-stabilization, which originally had a very narrow scope of application, is proving to encompass a formal and unified approach to fault tolerance under a model of transient failures for distributed systems. In this paper we define self-stabilization, examine its significance in the context of fault tolerance, define the important research themes that have arisen from it, and discuss the relevant results. In addition to the issues arising from Dijkstra's original presentation as well as several related issues, we discuss methodologies for designing self-stabilizing systems, the role of compilers with respect to self-stabilization, and some of the factors that prevent self-stabilization.