bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of human trophoblast migration and invasiveness
Authors: Chakraborty Chandan , Gleeson Louise M , McKinnon Timothy , Lala Peeyush K
Published: July 2002

The human placenta is an invasive structure in which highly proliferative, migratory, and invasive extravillous trophoblast (EVT) cells migrate and invade the uterus and its vasculature. Using in vitro propagated normal first-trimester EVT cells and immortalized EVT cells, which share all of the phenotypic and functional characteristics of the normal EVT cells, it has been shown that migration/invasion of human EVT cells is stringently regulated by many growth factors, their binding proteins, extracellular matrix (ECM) components, and some adhesion molecules in an autocrine/paracrine manner at the fetalmaternal interface in human pregnancy. Transforming growth factor β (TGF-β), decorin (a proteoglycan in the ECM), and melanoma cell adhesion molecule (Mel-CAM) inhibit, and insulin-like growth factor II (IGF-II), IGF-binding protein 1 (IGFBP-1), and endothelin 1 (ET-1) stimulate EVT cell migration/invasion. Inhibition of EVT cell migration by TGF-β has been suggested to be due to upregulation of integrins, which make the cells more adhesive to the ECM. Its antiinvasive action is due to an upregulation of tissue inhibitor of matrix metalloprotease 1 (TIMP-1) and plasminogen activator inhibitor (PAI-1) and a downregulation of urokinase-type plasminogen activator (uPA). Molecular mechanisms of inhibition of migration/invasion of EVT cells by decorin and Mel-CAM remain to be identified. IGF-II action has been shown to be mediated by IGF type I receptors (IGF-RII) independently of IGF type I receptors (IGF-RI) and IGFBPs. This action of IGF-II appears to involve inhibitory G proteins and phosphorylation of mitogen-activated protein kinase (MAPK) (extracellular signal-regulated protein kinases 1 and 2 (ERK-1 and ERK-2)). IGFBP-1 stimulation of EVT cell migration appears to occur by binding its Arg-Gly-Asp (RGD) domain to α5β1integrin, leading to phosphorylation of focal adhesion kinase (FAK) and MAPK (ERK-1 and ERK-2). These studies may improve our understanding of diseases related to abnormal placentation, viz. hypoinvasiveness in preeclampsia and hyperinvasiveness in trophoblastic neoplasms.Key words: trophoblast, migration, integrin, IGF-RII, IGFBP-1.
Sleep deprivation reduces total plasma homocysteine levels in rats
Authors: de Oliveira A C , D'Almeida V , Hipólide D C , Nobrega J N , Tufik S
Published: July 2002

Hyperhomocysteinemia has been associated with pathological and stressful conditions and is a risk factor for cardiovascular disease. Since sleep deprivation is a stressful condition that is associated with disruption of various physiological processes, we investigated whether it would also be associated with increases in plasma homocysteine levels. Further, since hyperhomocysteinemia may promote oxidative stress, and we had previously found evidence of oxidative stress in brain following sleep deprivation, we also searched for evidence of systemic oxidative stress by measuring glutathione and thiobarbituric acid reactive substance levels. Rats were sleep deprived for 96 h using the platform technique. A group was killed after sleep deprivation and another two groups were allowed to undergo sleep recovery for 24 or 48 h. Contrary to expectation, plasma homocysteine was reduced in sleep-deprived rats as compared with the control group and did not revert to normal levels after 24 or 48 h of sleep recovery. A trend was observed towards decreased glutathione and increased thiobarbituric acid reactive substance levels in sleep-deprived rats. It is possible that the observed decreases in homocysteine levels may represent a self-correcting response to depleted glutathione in sleep-deprived animals, which would contribute to the attenuation of the deleterious effects of sleep deprivation.Key words: sleep deprivation, homocysteine, oxidative stress, glutathione, rats.
Enhanced protection by melatonin and meloxicam combination in a middle cerebral artery occlusion model of acute ischemic stroke in rat
Authors: Gupta Y K , Chaudhary Geeta , Sinha Kusum
Published: July 2002

Mixed efficacy of neuroprotective drugs in clinical trials has led to the emergence of the approach of combination therapy in stroke. The present study was carried out to investigate the effect of the combination of melatonin (potent antioxidant) and meloxicam (preferential inhibitor of cyclooxygenase-2 enzyme) against a middle cerebral artery occlusion model of stroke in rats. Male Wistar rats in the weight range of 250300 g were used. Rats were anesthetized using chloral hydrate (400 mg/kg i.p) and subjected to 2 h of transient middle cerebral artery occlusion. Melatonin was administered at a dose of 20 mg/kg i.p. four times: at the time of middle cerebral artery occlusion, 1.5 h after middle cerebral artery occlusion, at the time of reperfusion, and 1 h after reperfusion. Meloxicam (2.5 mg/kg) was administered 4 h after middle cerebral artery occlusion. Motor performance tests (grip test, foot fault test, rotarod performance test, spontaneous locomotor activity), markers of oxidative stress, and triphenyltetrazolium chloride staining were carried out 24 h after middle cerebral artery occlusion. A vehicle-treated group was run in parallel. It was observed that melatonin treatment improved the motor performance and significantly attenuated the levels of malondialdehyde (MDA) as compared with the middle cerebral artery occluded group. Meloxicam treatment at the dose used neither showed significant improvement on the motor performance nor decreased the levels of MDA significantly as compared with the middle cerebral artery occluded group. However, when the combination of the two drugs was used, better protection was observed as was evident by the significant decrease in the percent foot fault errors, the increase in the time spent on the rotarod, and the increase in the six-point neurological score and grip test score. There was also a significant decrease in the levels of MDA in the combination group. The results of the present study demonstrate that enhanced protection is observed with the use of a combination of melatonin plus meloxicam in the middle cerebral artery occlusion model of acute ischemic stroke in rats.Key words: melatonin, antioxidant, meloxicam, focal ischemia.
COREPRESENTATION THEORY OF MULTIPLIER HOPF ALGEBRAS II
Authors: KUROSE HIDEKI , VAN DAELE ALFONS , ZHANG YINHUO
Published: July 2002

We continue our development of the corepresentation theory of multiplier Hopf algebras. In this paper, we consider the corepresentations of a multiplier Hopf algebra A in a nondegenerate algebra B rather than on a vector space (cf. [25]). We concentrate ourself on those corepresentations of A in B which are invertible elements of the multiplier algebra M(B⊗A). They are called the unitary corepresentations of A. In particular, the generalized R-matrices or quasi-triangular structures of a regular multiplier Hopf algebra are unitary (bi)corepresentations. As an application the quantum double of an algebraic quantum group can be constructed by means of the universal unitary corepresentation. Moreover, a unitary corepresentation of A in B can implement an inner coaction of A on B which allows us to study the covariant theory and crossed products.
LINE BUNDLES OF TYPE (1,…,1,2,…,2,4,…,4) ON ABELIAN VARIETIES
Authors: IYER JAYA N.
Published: July 2002

We show birationality of the morphism associated to line bundles L of type (1,…,1,2,…,2,4,…,4) on a generic g-dimensional abelian variety into its complete linear system such that h0(L) = 2g. When g = 3, we describe the image of the abelian threefold and from the geometry of the moduli space SUC(2) in the linear system |2θC|, we obtain analogous results in ℙH0(L).
HARTOGS-TYPE EXTENSION THEOREM AND SINGULAR SETS OF SEPARATELY HOLOMORPHIC MAPPINGS ON COMPACT SETS WITH VALUES IN A WEAKLY BRODY HYPERBOLIC COMPLEX SPACE
Authors: THAI DO DUC , MAI NGUYEN THI TUYET
Published: July 2002

We give a Hartogs-type extension theorem for separately holomorphic mappings on compact sets into a weakly Brody hyperbolic complex space. Moreover, a generalization of Saint Raymond–Siciak theorem of the singular sets of separately holomorphic mappings with values in a weakly Brody hyperbolic complex space is given.
DYNAMICS OF A SIMPLE EVOLUTIONARY PROCESS
Authors: STAUFFER DIETRICH , NEWMAN M. E. J.
Published: July 2002

We study the simple evolutionary process in which we repeatedly find the least fit agent in a population of agents and give it a new fitness, which is chosen independently at random from a specified distribution. We show that many of the average properties of this process can be calculated exactly using analytic methods. In particular, we find the distribution of fitnesses at arbitrary time, and the distribution of the lengths of runs of hits on the same agent, the latter being found to follow a power law with exponent -1, similar to the distribution of times between evolutionary events in the Bak–Sneppen model and models based on the so-called record dynamics. We confirm our analytic results with extensive numerical simulations.
ON THE EXTENSION OF SCALAR GRAVITY TO (2 + 1) DIMENSIONS
Authors: BEZERRA V. B. , SPINELLY J. , ROMERO C.
Published: July 2002

We consider the scalar gravity theory in (2 + 1) dimensions and find a black hole solution. We show that this approach does not lead to a Newtonian limit except for special metric configurations.
DECAY CONSTANTS OF HEAVY–LIGHT MESONS IN THE RELATIVISTIC QUARK MODEL
Authors: EBERT D. , FAUSTOV R. N. , GALKIN V. O.
Published: July 2002

The decay constants of pseudoscalar and vector heavy–light mesons are calculated in the framework of the relativistic quark model with the completely relativistic treatment of the light quark. It is argued that relativistic effects play a significant role. Good agreement of the model predictions with recent lattice and QCD sum rule calculations as well as available experimental data are found.
QUANTUM MECHANICS FROM A FLUCTUATION IN THE COSMOS
Authors: INABA MAKOTO
Published: July 2002

There is an indeterminable part from only the mass distribution in the general relativity. The part is regarded as a fluctuation from the Robertson–Walker geometry. An ensemble is given by a coarse graining of the fluctuation. The averaged least-action principle with respect to the ensemble yields a random motion of a particle in the universe. The random motion is equivalent to the traditional quantum mechanics. There is an additional potential proportional to scalar curvature in the present theory. The potential may be a representation of Mach's principle.
IMPLICATION OF sin 2β FROM GLOBAL FIT AND B→J/ψKS
Authors: WU YUE-LIANG , ZHOU YU-FENG
Published: July 2002

The measurement of sin 2β is discussed within and beyond the standard model. In the presence of new physics, the angle β extracted from the global fit (denoted by [Formula: see text]) and the one extracted from B→J/ψKS(denoted by βJ/ψ) are in general all different from the "true" angle β which is the weak phase of CKM matrix element [Formula: see text]. Possible new physics effects on the ratio [Formula: see text] is studied and parametrized in a most general form. It is shown that the ratio Rβmay provide a useful tool in probing new physics. The experimental value of Rβis obtained through an update of the global fit of the unitarity triangle with the latest data and found to be less than unity at 1σ level. The new physics effects on Rβfrom the models with minimum flavor violation (MFV) and the standard model with two-Higgs-doublet (S2HDM) are studied in detail. It is found that the MFV models seem to give a relative large value Rβ≥1. With the current data, this may indicate that this kind of new physics may be disfavored and alternative new physics with additional phases appears more relevant. As an illustration for models with additional phase beyond CKM phase, the S2HDM effects on Rβare studied and found to be easily coincide with the data due to the flavor changing neutral Higgs interaction.
GEOMETRICAL APPROACH TO LIGHT IN INHOMOGENEOUS MEDIA
Authors: PIWNICKI P.
Published: July 2002

Electromagnetism in an inhomogeneous dielectric medium at rest is described using the methods of differential geometry. In contrast to a general relativistic approach the electromagnetic fields are discussed in three-dimensional space only. The introduction of an appropriately chosen three-dimensional metric leads to a significant simplification of the description of light propagation in an inhomogeneous medium: light rays become geodesics of the metric and the field vectors are parallel transported along the rays. The new metric is connected to the usual flat space metric diag[1,1,1] via a conformal transformation leading to new, effective values of the medium parameters [Formula: see text] and [Formula: see text] with [Formula: see text]. The corresponding index of refraction is thus constant and so is the effective velocity of light. Space becomes effectively empty but curved. All deviations from straight-line propagation are now due to curvature. The approach is finally used for a discussion of the Riemann–Silberstein vector, an alternative, complex formulation of the electromagnetic fields.
MONTE CARLO SHELL MODEL CALCULATIONS FOR ATOMIC NUCLEI
Authors: OTSUKA T. , MIZUSAKI T. , UTSUNO Y. , SHIMIZU N. , HONMA M.
Published: July 2002

The formulation and recent applications of the Quantum Monte Carlo diagonalization (QMCD) method are reported. The QMCD has been proposed for solving the quantum many-body inteacting systems, providing us with energy eigenvalues, transition matrix elements and wave functions. Its application to the nuclear shell model is referred to as the Monte Carlo Shell Model. By the Monte Carlo Shell Model calculations, the level structure of low-lying states can be studied with realistic interactions, providing a useful tool for nuclear spectroscopy. The Monte Carlo Shell Model has been applied to the study of a variety of nuclei, and can be characterized as the importance truncation scheme to the full diagonalization which is infeasible in many cases due to extremely large dimensions.
TWO-DIMENSIONAL ELECTRON SYSTEM IN ELECTROMAGNETIC RADIATION FIELD
Authors: LUNGU RADU PAUL , MANOLESCU ANDREI
Published: July 2002

We consider a two-dimensional electron gas in the presence of a monochromatic linear polarized electromagnetic field, within the Floquet formalism. The Floquet states have a simple relation with the energy eigenstates in the absence of the field. Therefore the single-particle and the two-particle Green functions of the many-body system with Coulomb interactions, in the radiation field, can be formally calculated by the standard diagrammatic techniques, as for the conservative system. We derive the elementary excitations of quasi-particle type, the plasma dispersion relation, and the ground state quasi-energy, and we relate them to the corresponding results for the conservative system.
SELF-TRAPPED EXCITONS IN ORTHORHOMBIC SnBr2
Authors: YAMASAKI Y. , OHNO N.
Published: July 2002

Luminescence properties of SnBr 2 have been studied to reveal the photo-excited exciton relaxation process. Two types of luminescence with large Stokes shifts are found at low temperatures; the 2.2-eV luminescence band produced under the photo-excitation in the first exciton region, and the 2.5-eV luminescence band stimulated by photons with energies above the bandgap. The time-resolved photoluminescence measurements have revealed that the 2.2-eV luminescence comprises fast (1.2 μs) and slow (6.4 μs) exponential decay components, whereas the 2.5-eV luminescence shows the time dependence of I(t)∞ t-0.9. These results suggest that the former band is attributed to the radiative decay of self-trapped excitons, and the latter band would originate from tunneling recombination of holes with the STEL as in the case of lead halides.
The Collective Excitations in High-Tc Superconductors
Authors: Kanazawa I.
Published: July 2002

It is proposed that the collective modes around the hole for k~(π,0) in underdoped cuprates might correspond to massive gauge fields [Formula: see text], which are introduced by the gauge-invariant carrieron (GIC) model.
NON-LINEAR EFFECTS OF Ti EMISSION ON TIN FILM DEPOSITION
Authors: CHAN MARVIN , XU S. , JIANG N. , LONG J. , DIONG C. H.
Published: July 2002

Non-linear effects on Ti emission during TiN synthesis in an inductively coupled plasma assisted DC magnetron sputtering system have been investigated. TiN films are deposited on stainless steel 304 substrates, using N 2 + Ar mixture in the absence and presence of RF current variation. In-situ measurements of the optical emission collected during the deposition processes indicate differences in the intensities of the Ti species involved. Film characterizations indicate that such plasma non-linearity plays a pivotal role in the eventual film properties. Highly orientated (111) TiN films deposited under the same RF power were found to correspond to two different hardness values, one being 2240Hv and is 40% harder than the other.
FLUX DEPENDENCE OF PERSISTENT CURRENT IN A MESOSCOPIC DISORDERED TIGHT BINDING RING
Authors: HEINRICHS J.
Published: July 2002

We reconsider the study of persistent currents in a disordered one-dimensional ring threaded by a magnetic flux ϕ, using he one-band tight-binding model for a ring of N-sites with random site energies. The secular equation for the eigenenergies expressed in terms of transfer matrices in the site representation is solved exactly to second order in a perturbation theory for weak disorder and fluxes differing from half-integer multiples of the flux quantum ϕ0=hc/e. From the equilibrium currents associated with the one-electron eigenstates we derive closed analytic expressions for the disorder averaged persistent current for even and odd numbers, Ne, of electrons in the ground state. Explicit discussion for the half-filled band case confirms that the persistent current is periodic with a period ϕ0, as in the absence of disorder, and that its amplitude is generally suppressed by the effect of the disorder. In comparison to previous results, based on an approximate analysis of the secular equation, the current suppression by disorder is strongly enhanced by a new periodic factor proportional to 1/ sin 2(2πϕ/ϕ0), for ϕ≠( integer )ϕ0/2.
INVESTIGATION OF THE FERROMAGNETIC PHASE OF WIGNER ELECTRON CRYSTAL
Authors: RAJESWARA PALANICHAMY R. , IYAKUTTI K.
Published: July 2002

The ground state energies of the ferromagnetically ordered electron crystals corresponding to sc, bcc, fcc, diamond and perovskite structures are computed. The stability of these structures is analyzed. In each case, the possibility of the Wigner electrons having cubic or spherical constant energy surface (the region of integration in momentum space) is considered for the range of r s values corresponding to low densities. The role of correlation energy is suitably taken into account. The range of low density region favourable for Wigner crystallization is found to be above r s = 30. It is found that, the ferromagnetically ordered electrons crystallize into fcc lattice in the low density limit. The structure dependent Wannier functions, which give proper localized representation for the Wigner electrons in the crystal, are employed in the calculation.
CHARACTERISTICS OF CVD DIAMOND FILMS IN DETECTING UV, X-RAY AND ALPHA PARTICLE
Authors: AHN J. , GAN B. , ZHANG Q. , YOON S. F. , LIGATCHEV V. , WANG S.-G. , HUANG Q.-F. , CHEW K. , PATRAN A.-C. , SERBAN A. , LIU M.-H. , LEE S. , BETTIOL A. A. , OSIPOWICZ T. , WATT F.
Published: July 2002

The CVD diamond UV photodetector shows more than four orders of photoresponsivity discrimination between UV and visible light. Post-treatment on as-fabricated photodetector is essential for a good response to UV light and blindness to visible light. The CVD diamond X-ray detector shows linear dependence of photocurrent on X-ray intensity and high response speed. The mapping of charge collection efficiency on the whole sensing area of a CVD diamond alpha particle detector has been obtained using ion-beam-induced charge microscopy technique. Three peaks have been observed in the charge collection spectrum.
TWO GAP SIGNATURE IN MAGNESIUM DIBORIDE
Authors: GIUBILEO F. , RODITCHEV D. , SACKS W. , LAMY R. , KLEIN J.
Published: July 2002

Scanning Tunneling Spectroscopy is used at low temperature in an extensive study of the recently discovered superconducting compound MgB2 . Both powder- and crystal-based samples show a very unusual double-gap structure in the tunneling conductance spectra. The spectral weights of the gaps may vary from one junction to another but their energy positions remain constant. Both gaps vanish at the critical temperature of the bulk material. These findings confirm the existence of two-gap superconductivity in MgB2 , which opens a new class of multiple-gap superconductors.
SHORT-TIME BEHAVIORS OF LONG-RANGED INTERACTIONS
Authors: FANG H. , HE C. S. , LI Z. B. , SETO S. P. , CHEN Y. , WU M. Y.
Published: July 2002

Recent results on the short-time behaviors of a few models possessing a common feature of long-ranged interaction will be summarized. For the disorder initial state, the initial order increase is observed for each model in a heat-bath at the critical temperature. The dynamic exponents are calculated. For arbitrary initial order and environment temperature, universal characteristic functions are introduced in order to generalize the scaling relations. Remarkable consistence between the theoretic renormalization group results and the simulations are found in the long-range regime.
Structure Evolution of Electrorheological Fluids under Flow Conditions
Authors: Tang X. , Li W. H. , Wang X. J. , Zhang P. Q.
Published: July 2002

Transparent electrode with a conducting film on a glass surface provides us a useful tool to observe the fired-induced structure formation in ER fluids directly under both quiescent and dynamic conditions. In this paper the flow and field-induced structure evolution in ER fluids will be studied in three flow conditions, i.e., (a) ER fluids flowing through a slit channel between two fixed parallel transparent electrodes, which construct a model ER valve, (b) ER fluids being sheared between two concentric transparent electrode tubes, which correspond to a conventional rotary rheometer and (c) ER fluids being sheared between two parallel plate disks, which correspond to an ER clutch. Shear-induced layer structure was observed even when the shear rate reaches 600 s -1. A tentative phase transition diagram between the layer structure and the homogeneous flow state will be given.
Electrically Induced Phase Inversion in Polyurethane/Dimethylsiloxane Blend
Authors: Kimura Hiroshi , Aikawa Koichiro , Masubuchi Yuichi , Takimoto Jun-Ichi , Koyama Kiyohito , Uemura Takashi
Published: July 2002

Recently, we have reported on an electrically induced "phase inversion" phenomenon which was discovered in a urethane-modified polypropylene glycol (UPPG)/dimethylsiloxane (DMS) blend. The phenomenon occurs when the fraction of UPPG is high but UPPG forms droplets dispersed in DMS matrix. When the electric field is applied, UPPG becomes the continuous matrix and DMS breaks into droplets. The domain morphology does not return to the original structure (DMS = matrix, UPPG = droplets) even after turning off the field. To clarify the relation between the phase inversion and the resulting ER effect, we observed the domain structure in UPPG/DMS blends under both the electric and shear fields.
Indirect Measurements of Microstructure Development in Magnetorheological Fluids
Authors: Jolly M. R. , Bender J. W. , Mathers R. T.
Published: July 2002

Magneto-induction experiments have been devised to measure the microstructure response of quiescent magnetorheological (MR) fluids to an applied magnetic field. Unlike many previous techniques this measurement technique is well suited for MR fluids of high iron loading. Two distinct time scales of microstructure formation have been observed within the range of 10-3 to 10-1 seconds. These two time constants are thought to be associated with floc or chain formation and chain growth and migration. The dependency of the time response upon volume fraction, carrier viscosity and applied field is in partial agreement with contemporary theories and models of particle aggregation.
STATES WITH HOLES IN FOCK SPACE IN A MESOSCOPIC JOSEPHSON JUNCTION
Authors: ZOU JIAN , SHAO BIN , XING XIU-SAN
Published: July 2002

Recently a state with holes in Fock space corresponding to a nonclassical state has been studied. In this paper we study the interaction between a mesoscopic Josephson junction and nonclassical microwave, treating both quantum mechanically. We introduce the creation and the annihilation operators for the junction. Within the external field approximation, we show that the state of the junction can evolve into a superposition of two coherent states, which can become a state with holes in Fock space for some specific parameters.
EFFECT OF Ni SUBSTITUTION FOR Cu IN THE VORTEX STATE OF (Bi,Pb):2223 SUPERCONDUCTOR
Authors: POP A. V.
Published: July 2002

The influence of the partial substitution of x=0.02 Ni for Cu on the magnetoresistivity in the (Bi,Pb):2223 superconductor has been investigated. The resistive transitions were studied under magnetic fields up to 0.7 Tesla by using the dρ/dT versus T curves. The Arrhenius plots shows that the dissipation processes are induced by two distinct regimes. In the high temperature regime the activation energy is proportional to ln B and to B-1 in low temperature regime. The main dissipation processes in these regimes are discussed.
THE DIFFUSION OF THE VORTICES IN HIGH Tc THIN FILM MICROBRIDGES: MODEL AND RESULTS
Authors: BERNSTEIN P. , PANNETIER M. , LECOEUR Ph. , DOAN T. D. , HAMET J. F.
Published: July 2002

We have previously proposed a model for the flux creep regime of the vortices in superconducting thin film microbridges in which a bias current flows. In the first part of the paper this model is summarized and we show how physical quantities which are relevant to estimate the importance of vortex pinning in the samples can be determined. Then, the effect of a low applied magnetic field on the modulation of the critical current of the microbridges is discussed and we show how this type of measurements can give additionnal information on the vortex motion in the samples and allows to determine their superconducting thickness and penetration depth as a function of temperature.
Commensurate Inhibition of Vortex Lattice Melting and Enhancement of Critical Current by Periodic Columnar Pins
Authors: Ma Yong-li , XianXi Dai
Published: July 2002

The stiffness of the vortex lattice and the size of thermally induced fluctuations in the presence of a periodic array of columnar pins are calculated. The commensurability effect on the melting line Tm and critical current density Jc is considered. The results show that the melting line is pushed to higher temperatures, the strongly pinned vortex lattice carries the greatly enhanced Jc and a series of lobes occur in Tm(H) and Jc(H) when field closes to a commensurability condition. Jc(T)~(1-T/Tc)3/2 both with and without columnar defects. They agree well with experiments.
TWO UNUSUAL DETERMINATIONS OF ELECTRONIC AND LATTICE THERMAL PARAMETERS IN YBa2Cu3O7 Films
Authors: Maneval J-P.
Published: July 2002

This paper deals with the nanosecond transient electrical resistance following either an optical pulse or the sudden application of a critical current in YBCO films. The observed bi-exponential decay of the photoresistance yields both the electron-phonon relaxation time τep and the phonon escape time τγ to the substrate. A novel treatment of these data allows to derive the low-temperature electron specific heat and the electron-phonon coupling constant lambda in the acoustic regime. Secondly, the nucleation time of phase-slip centers in narrow bridges is analyzed to provide τγ. Finally, the accurate knowledge of τγ is used to determine the temperature inside a dissipation center.
NEW AND OLD SYMMETRIES OF INTEGRABLE SPIN CHAINS
Authors: NEPOMECHIE RAFAEL I
Published: July 2002

This article summarizes the results of two recent investigations with A. Doikou on symmetries of integrable quantum spin chains which have been motivated in part by the computation of exact boundary and bulk scattering matrices.
ENTANGLEMENT OF AMPLITUDE AND OPTICAL PHASE INVOLVED IN THE EPR EIGENSTATE
Authors: FAN HONGYI , FAN YUE
Published: July 2002

By noticing that although single-mode Susskind–Glogower phase operator does not commute with photon number operator, two-mode nonlinear phase operator commutes with number-difference operator. We reveal that the common eigenstate <η| of two-particles' relative coordinate and total momentum involves the entanglement between phase and amplitude. We also reveal entanglement between number difference and amplitude inherent in the state |D,|η|>, where [Formula: see text] is a deductive state of |η>.
EFFECT OF TEMPERATURE ON INTRINSIC LOCALIZED MODES IN ANHARMONIC LATTICES
Authors: TEIXEIRA RABELO J. N. , CARDOSO E. S. , ZUBOV V. I.
Published: July 2002

We study the effect of temperature on Intrinsic Localized Modes (ILM) in anharmonic lattices. An approach is proposed based on the Method of the Unsymmetrized Self-Consistent Field (USF). The special case of an odd-parity mode in an anharmonic linear chain with Mie–Lennard–Jones potential is investigated in more detail. We find that in the weak anharmonic approximation, an increasing of temperature does not change the pattern of the mode, leading to a very small decreasing of the displacement amplitudes and a decreasing of the mode frequency. The frequency of the mode increases with increasing of both the repulsion and attraction indexes. This effect is more sensitive to the repulsion index.
APPLICATION OF III-V MATERIALS IN SPACE SOLAR CELL ENGINEERING
Authors: TORCHYNSKA T. , POLUPAN G. , ZELOCUATECATL F. CONDE , SCHERBINA E.
Published: July 2002

The present paper is the review of current situation in space solar cell engineering. The comparison of the more popular GaAs, AlGaAs, InGaP and InP solar cell parameters, as well as tlleir variation with temperature rise, radiation treatments and improving design have been represented. The typical working conditions for solar cells on the space orbit and requirements for solar cells are analysed. The modern international space projects, applied new types of III-V material solar cells, have discussed as well.
AC Susceptibilities and Electrical Resistance of (Bi1.6Pb0.4)(Sr1.8Ba0.2)Ca2(Cu1-xZnx)3Oy Superconductor
Authors: Pop A. V. , Ilonca Gh. , Pop V. , Lung C. , Deltour R.
Published: July 2002

Ac susceptibility and electrical resistivity measurements as a function of temperature have been carried out on the samples with x=0.00, 0.02 and 0.05 Zn. The decrease of inter- and intragrain critical temperatures with increasing x is in agreement with the increase of the residual resistivity. The intergrain properties are more influenced than the intragrain ones. The granularity parameters p and ρ ct were evaluated from resistivity data.
PEIERLS PHASE TRANSITION AND NONLINEAR TRANSPORT STUDY OF DOPED BLUE BRONZES K0.3-xNaxMoO3
Authors: WANG DINGLI , XIAO QINGMING , TANG WUFENG , ZHAO TONGYUN , SHI JING , TIAN DECHENG , TIAN MINGLIANG
Published: July 2002

Temperature dependence of Ohmic resistance, and nonlinear current–voltage (I–V) characteristics at 77 K were systematically studied in pure potassium blue bronze K 0.3 MoO 3 and Na-doped alloy bronzes K 0.3-x Na x MoO 3(x = 0.02, 0.05, 0.10). No considerable influence of Na ions doping in K 0.3 MoO 3 was found on the Peierls transition temperature, while obvious enchancement on semiconductor gap and remarkable influence on the first threshold field were observed. We attribute the first phenomenon to two opposite effects of Na ions, and the depinning model is proposed to account for the latter. The analytical form of nonlinear charge-density wave current I CDW in a moderate field range fits the power-law relation, i.e. I CDW ∝ (V/V T -1)α, where the exponent α is about 3/2 and slightly enhanced by Na ions doping.
SCENOGRAM —

S

CENE ANALYSIS USING

C

OMPOSIT

E

N

EURAL

O

SCILLATORY-BASED ELASTIC

GRA

PH

M

ODEL
Authors: LEE RAYMOND S. T. , LIU JAMES N. K.
Published: July 2002

Scene analysis is so far one of the most important topics in machine vision. In this paper, we present an integrated scene analysis model, namely SCENOGRAM (Scene analysis using CompositENeural Oscillatory-based elastic GRAph Model). Basically the proposed scene analyzer is based on the integration of the composite neural oscillatory model with our elastic graph dynamic link model. The system involves: (1) multifrequency bands feature extraction scheme using Gabor filters, (2) automatic figure-ground object segmentation using a composite neural oscillatory model, and (3) object matching using an elastic graph dynamic link model.

From the implementation point of view, we introduce an intelligent agent based scene analysis and object identification solution using the SCENOGRAM technology. From the experimental point of view, a scene gallery of over 6000 color scene images is used for automatic scene segmentation testing and object identification test. An overall correct invariant facial recognition rate of over 87% is attained. It is anticipated that the implementation of the SCENOGRAM can provide an invariant and higher-order intelligent object (pattern) encoding, searching and identification solution for future intelligent e-Business.
THE 1:2 MODE INTERACTION IN RAYLEIGH–BÉNARD CONVECTION WITH WEAKLY BROKEN MIDPLANE SYMMETRY
Authors: MERCADER ISABEL , PRAT JOANA , KNOBLOCH EDGAR
Published: July 2002

The effects of weak breaking of the midplane reflection symmetry on the 1:2 steady state mode interaction in Rayleigh–Bénard convection are discussed in a PDE setting. Effects of this type arise from the inclusion of non-Boussinesq terms or due to small differences in the boundary conditions at the top and bottom of the convecting layer. The latter provides the simplest realization, and captures all qualitative effects of such symmetry breaking. The analysis is performed for two Prandtl numbers, σ=10 and σ=0.1, representing behavior typical of large and low Prandtl numbers, respectively.
FREQUENCY SWITCHED CHUA'S CIRCUIT: EXPERIMENTAL DYNAMICS CHARACTERIZATION
Authors: CANTELLI LUCIANO , FORTUNA LUIGI , FRASCA MATTIA , RIZZO ALESSANDRO
Published: July 2002

In this letter the so-called frequency switched Chua's circuit is presented. Its realization is based on the introduction of a switch device into the Chua's circuit, realized by using three State-Controlled CNN cells. The dynamics of this system has been investigated both numerically and experimentally with respect to the frequency of the switch enabling signal. It exhibits different strange attractors, according to the variation of the frequency of the switching signal. Moreover, very strange frequency hysteresis phenomena demonstrating the peculiarity of the introduced circuit have been revealed.
TRUMPET AND TRUMPET PLAYER: A HIGHLY NONLINEAR INTERACTION STUDIED IN THE FRAMEWORK OF NONLINEAR DYNAMICS
Authors: VERGEZ CHRISTOPHE , RODET XAVIER
Published: July 2002

For musical purposes, a real-time physical model of trumpet-like instruments was built. The model exhibits different behaviors which are studied in the framework of nonlinear dynamical systems. Periodic, quasi-periodic, chaotic and intermittency regimes are identified and studied in order to better understand the general behavior of the model, which is essential for musical use.
ON THE SPATIAL ENTROPY AND PATTERNS OF TWO-DIMENSIONAL CELLULAR NEURAL NETWORKS
Authors: LIN SONG-SUN , YANG TZI-SHENG
Published: July 2002

This work investigates binary pattern formations of two-dimensional standard cellular neural networks (CNN) as well as the complexity of the binary patterns. The complexity is measured by the exponential growth rate in which the patterns grow as the size of the lattice increases, i.e. spatial entropy. We propose an algorithm to generate the patterns in the finite lattice for general two-dimensional CNN. For the simplest two-dimensional template, the parameter space is split up into finitely many regions which give rise to different binary patterns. Qualitatively, the global patterns are classified for each region. Quantitatively, the upper bound of the spatial entropy is estimated by computing the number of patterns in the finite lattice, and the lower bound is given by observing a maximal set of patterns of a suitable size which can be adjacent to each other.
STUDY OF SYNCHRONIZED MOTIONS IN A ONE-DIMENSIONAL ARRAY OF COUPLED CHAOTIC CIRCUITS
Authors: GALIAS ZBIGNIEW , OGORZAŁEK MACIEJ J.
Published: July 2002

We investigate the stability of synchronous motion in an array of bidirectionally coupled electronic circuits. We compute Lyapunov exponents of the generic variational equation associated with directions transversal to the synchronization subspace. Using Lyapunov exponents we derive conditions for the coupling strength for which the stable synchronous solution exists. We also find the limit on the size of the network, which can sustain stable synchronous motion. Theoretical results are compared with the results of numerical experiments.
QUANTUM COSMOLOGY IN ANISOTROPIC COSMOLOGICAL MODELS WITH SCALAR–TENSOR THEORIES
Authors: CHAKRABORTY SUBENOY
Published: July 2002

This paper deals with quantum cosmological phenomena in anisotropic cosmological models with nonminimally coupled scalor field. With proper transformation of the field variables, the Wheeler–Dewitt (WD) equation looks simple in form and solutions are obtained using separable form of the wave function. Using part integral formulation, the wave function of the Universe has been evaluated by the method of steepest descent. Finally, the causal interpretation has been done using quantum Bohmian trajectories and also we study the classical limit of some particular solutions of these quantum models.
SPHERICALLY SYMMETRIC SOLUTIONS IN MULTIDIMENSIONAL GRAVITY WITH THE SU(2) GAUGE GROUP AS THE EXTRA DIMENSIONS
Authors: DZHUNUSHALIEV V. , SCHMIDT H.-J. , RURENKO O.
Published: July 2002

The multidimensional gravity on the principal bundle with the SU(2) gauge group is considered. The numerical investigation of the spherically symmetric metrics with the center of symmetry is made. The solution of the gravitational equations depends on the boundary conditions of the "SU(2) gauge potential" (off-diagonal metric components) at the symmetry center and on the type of symmetry (symmetrical or antisymmetrical) of these potentials. In the chosen range of the boundary conditions it is shown that there are two types of solutions: wormhole-like and flux tube. The physical application of such kind of solutions as quantum handles in a spacetime foam is discussed.
DIRAC MONOPOLES ON KERR BLACK HOLES: COMPARING GAUGES
Authors: GONCHAROV YU. P.
Published: July 2002

We update our previous work on the description of twisted configurations for complex massless scalar field on the Kerr black holes as the sections of complex line bundles over the Kerr black hole topology [Formula: see text]. From physical point of view, the appearance of twisted configurations is linked with the natural presence of Dirac monopoles that arise as connections in the above line bundles. We consider their description in the gauge inequivalent to the one studied previously and discuss a row of new features appearing in this gauge.
KINETIC MODELS ON ACETYLCHOLINESTERASE MODULATION BY SELF-SUBSTRATE AND POLYAMINES: ESTIMATION OF INTERACTION PARAMETERS AND RATE CONSTANTS FOR FREE AND ACETYLATED STATES OF THE ENZYME
Authors: VENTURINO ANDRÉS , BERGOC ROSA MARÍA , DE D'ANGELO ANA MARÍA PECHEN , ROSENBAUM ENRIQUE ARTURO
Published: July 2002

Polyamines act as dual modulators on electric eel acetylcholinesterase, modifying both the apparent Km and Ki, depending on substrate levels. A kinetic model was developed to explain the results, based on two-step catalysis, a peripheral site for substrate inhibition apart from the catalytic site, and one binding site for polyamine. This model presented the best fittings to data, when compared with a simpler one considering one catalytic step. A fitting equation built up with sixteen independent parameters let us calculate the kinetic constants. In this way, we were able to solve the parameter identifiability problem arising from model uncertainty when only substrate was used in acetylcholinesterase kinetics. Besides, fitting parameters directly provide information about the binding constants of the different complexes, the modulatory strength of substrate and polyamines, and the effect on the standard activation free energy for acetylcholinesterase.

Substrate inhibition operates mainly on the first catalytic step with an affinity constant of 5.2 mM-1, which is reduced to one third for the acetylated enzyme. The interaction factor between substrate binding at both sites is about 12. The modulatory strength of polyamines is spermine > spermidine > putrescine. This order is directly related to the number of amino groups in the molecule, and to the calculated free interaction energy. The effect of the number of amino groups on the binding energy is significantly increased in acetylated acetylcholinesterase. It is also inferred that the formation of a quaternary complex enzyme-substrate-substrate-polyamine would not be possible. Some relations between polyamine structure and acetylcholinesterase activity are suggested from estimated constants. Due to the distal amino group distances, it is possible for spermine and spermidine to span along the catalytic gorge of acetylcholinesterase, binding to the catalytic and peripheral sites in a way similar to bisquaternary ammonium inhibitors.
FRACTALITY IN A MACROECONOMIC MODEL: NONLINEAR OSCILLATION AROUND A LONG-TERM EQUILIBRIUM
Authors: RICHARDS GORDON R.
Published: July 2002

Recent studies have established that macroeconomic time series exhibit fractal properties. Empirical tests here demonstrate that interest rates, exchange rates, output and prices all show evidence of a non-integer fractal dimension. Several classes of volatility models widely used in econometrics can give rise to fractality. In the paradigm proposed here, fractality results from multiplicative relationships between residual noise terms in simultaneous equation systems. The emergence of fractality in a large-scale econometric model is analyzed. The model uses well-established structural equations, so that all variables converge toward their equilibrium paths in the long run. The forecasted paths are then embedded in noise, and the model is re-simulated at a higher frequency. The simultaneity of the model equations causes the embedding noise to take on fractal properties. Multi-scaling demonstrates that the model simulations reproduce the fractal properties of the real-world time series reasonably well. Finally, it is possible to forecast at short horizons using an algorithm that exploits two aspects of fractality, scaling symmetries and intermittency. Ratios of rates of change capture proximate symmetries. A logit regression is used to predict the conditional probability of extreme events.
DIRECTING GENETIC ALGORITHMS FOR PROBABILISTIC REASONING THROUGH REINFORCEMENT LEARNING
Authors: ZHONG XIAOMIN , SANTOS EUGENE
Published: July 2002

In this paper, we develop an efficient online approach for belief revision over Bayesian networks by using a reinforcement learning controller to direct a genetic algorithm. The random variables of a Bayesian network can be grouped into several sets reflecting the strong probabilistic correlations between random variables in the group. We build a reinforcement learning controller to identify these groups and recommend the use of "group" mutation and "group" crossover for the genetic algorithm based on these groupings online. The system then evaluates the performance of the genetic algorithm based on these groupings online. The system then evaluates the performance of the genetic algorithm and continues with reinforcement learning to further tune the controller to search for a better grouping.
DISCRETE TESTING RESOURCE ALLOCATION IN MODULE TESTING
Authors: ICHIMORI TETSUO
Published: July 2002

This paper treats an allocation problem of discrete testing resources in module testing where software modules are tested independently. The total amount of discrete testing resources is given beforehand. When an allocation is determined in module testing, each software module defines the share per size. Since discrete resources do not allow each software module to get an equal share per size, there exists a dispersion. The aim of this paper is to find an allocation minimizing the variance of this dispersion.
COLOUR-MATCHING IN HAND AND FINGER PROSTHESES: THE ASIAN PERSPECTIVE
Authors: Leow Eng-Lye , Kour Anam-Kueh , Pereira Barry P. , Pho Robert W.H.
Published: July 2002

The wide range of skin tones in the Asian population presents a challenge when colour-matching hand and finger prostheses. It requires that the prostheses be custom-made to better match the wide variations. We have developed a finger and hand prosthesis using a multi-layered moulding technique incorporating a colour-matching procedure capable of reproducing the colour tones and life-like appearance of the skin. Between 1990–1994, we have fitted these prostheses to a total of 109 patients. In evaluating the colour-match of their prostheses, 84% of the patients fitted with hand prostheses and 78% of those fitted with finger prostheses had a good to excellent match. This paper discusses some of the challenges we face in colour-matching hand and finger prostheses in the Asian population.
NONLINEAR OSCILLATIONS IN BUSINESS CYCLE MODEL WITH TIME LAGS
Authors: KRAWIEC ADAM , SZYDŁOWSKI MAREK , TOBOŁA JANUSZ
Published: July 2002

We analyse the Hopf bifurcations in the Kaldor–Kalecki business cycle model represented by a delay differential equation system.
MARKOV PROCESS IN PATTERN RECOGNITION
Authors: CAI JINHAI , LIU ZHI-QIANG
Published: July 2002

Using the Markov random process, we developed two new approaches to pattern recognition: (1) Hidden Markov model for modeling spectral features for recognizing 2D shapes. This is because Fourier spectra are suitable for describing 2D shapes of simple closed contours and probabilistic models are capable of coping with random variations in object shapes. We will analyze the properties of spectral features derived from contours of 2D shapes and use these features in 2D pattern recognition. (2) Markov random fields for modeling 2D structural and statistical features. We will give a theoretic analysis of this approach, discuss the issues in the design of neighborhood system and cliques for Markov random field models, and analyze the properties of the models.

We have applied the proposed approach to the recognition of unconstrained handwritten numerals and 2D shapes. Our extensive experimental results show that the proposed approach can achieve a higher performance than that reported recently in the literature.
KINETIC THEORY AND HYDRODYNAMICS FOR A LOW DENSITY GRANULAR GAS
Authors: DUFTY JAMES W.
Published: July 2002

Many features of real granular fluids under rapid flow are exhibited as well by a system of smooth hard spheres with inelastic collisions. For such a system, it is tempting to apply standard methods of kinetic theory and hydrodynamics to calculate properties of interest. The domain of validity for such methods is a priori uncertain due to the inelasticity, but recent systematic studies continue to support the utility of kinetic theory and hydrodynamics as both qualitative and quantitative descriptions for many physical states. The basis for kinetic theory and hydrodynamic descriptions is discussed briefly for the special case of a low density gas.