bluuebunny/crossref_metadata_2025 huggingface dataset:
Flagellum-Mediated Adhesion byBurkholderia pseudomalleiPrecedes Invasion ofAcanthamoeba astronyxis
Authors: Inglis Timothy J. J. , Robertson Terry , Woods Donald E. , Dutton Nichole , Chang Barbara J.
Published: March 2003

In this study we investigated the role of the bacterial flagellum inBurkholderia pseudomalleientry toAcanthamoeba astronyxistrophozoites.B. pseudomalleicells were tethered to the external amoebic surface via their flagella. MM35, the flagellum-lackingfliCknockout derivative ofB. pseudomalleiNCTC 1026b did not demonstrate flagellum-mediated endocytosis in timed coculture, confirming that an intact flagellar apparatus assistsB. pseudomalleientry intoA. astronyxis.
Immunization withPorphyromonas gingivalisCapsular Polysaccharide PreventsP. gingivalis-Elicited Oral Bone Loss in a Murine Model
Authors: Gonzalez Dario , Tzianabos Arthur O. , Genco Caroline A. , Gibson Frank C.
Published: March 2003

The capsular polysaccharide (CPS) of the periodontal pathogenPorphyromonas gingivalisis an important virulence factor for this organism. We purifiedP. gingivalisCPS, immunized mice with this antigen, and assessed the vaccine potential ofP. gingivalisCPS by using the murine oral challenge model. Animals immunized withP. gingivalisCPS developed elevated levels of immunoglobulin M (IgM) and IgG in serum that reacted with wholeP. gingivalisorganisms. The mice immunized withP. gingivalisCPS were protected fromP. gingivalis-elicited oral bone loss. These data demonstrate thatP. gingivalisCPS is a vaccine candidate for prevention ofP. gingivalis-elicited oral bone loss.
Bidirectional Concentration-Dependent Effects of Tumor Necrosis Factor Alpha in
Shigella dysenteriae
-Related Seizures
Authors: Yuhas Yael , Weizman Abraham , Ashkenazi Shai
Published: March 2003

We have previously demonstrated that pretreatment of mice with
Shigella dysenteriae
sonicate enhanced their susceptibility to pentylenetetrazole-induced seizures and that tumor necrosis factor alpha (TNF-α) was proconvulsive in this respect. The present study shows that TNF-α, at high concentrations, may also exert a suppressive effect on
Shigella
-mediated seizures. This implies that high levels of TNF-α may play a protective role in neurologic complications of
S
.
dysenteriae
infection.
The Fibronectin-Binding Proteins of
Staphylococcus aureus
May Promote Mammary Gland Colonization in a Lactating Mouse Model of Mastitis
Authors: Brouillette Eric , Talbot Brian G. , Malouin François
Published: March 2003

The fibronectin-binding proteins (FnBPs) of
Staphylococcus aureus
are believed to be implicated in the pathogen's adherence to and colonization of bovine mammary glands, thus leading to infectious mastitis. In vitro studies have shown that FnBPs help the adhesion of the pathogen to bovine mammary epithelial cells. However, the importance of FnBPs for the infection of mammary glands has never been directly established in vivo. In this study with a mouse model of mastitis, the presence of FnBPs on the surface of
S. aureus
increased the capacity of the bacterium to colonize mammary glands under suckling pressure compared to that of a mutant lacking FnBPs.
COLLECTIVE POTENTIAL FOR LARGE-N HAMILTONIAN MATRIX MODELS AND FREE FISHER INFORMATION
Authors: AGARWAL A. , AKANT L. , KRISHNASWAMI G. S. , RAJEEV S. G.
Published: March 2003

We formulate the planar "large N limit" of matrix models with a continuously infinite number of matrices directly in terms of U(N) invariant variables. Noncommutative probability theory is found to be a good language to describe this formulation. The change of variables from matrix elements to invariants induces an extra term in the Hamiltonian, which is crucial in determining the ground state. We find that this collective potential has a natural meaning in terms of noncommutative probability theory: it is the "free Fisher information" discovered by Voiculescu. This formulation allows us to find a variational principle for the classical theory described by such large N limits. We then use the variational principle to study models more complex than the one describing the quantum mechanics of a single Hermitian matrix (i.e. go beyond the so-called D = 1 barrier). We carry out approximate variational calculations for a few models and find excellent agreement with known results where such comparisons are possible. We also discover a lower bound for the ground state by using the noncommutative analog of the Cramer–Rao inequality.
NONCOMMUTATIVE SUPERSYMMETRY IN TWO DIMENSIONS
Authors: ABBASPUR REZA
Published: March 2003

Based on an argument for the noncommutativity of momenta in noncommutative directions, we arrive at a generalization of the [Formula: see text] super E2 algebra associated to the deformation of translations in a noncommutative Euclidean plane. The algebra is obtained using appropriate representations of its generators on the space of superfields in a D = 2, [Formula: see text] "noncommutative superspace." We find that the (anti)commutators of several (super)translation generators are no longer vanishing, but involve a new set of generators which together with the (super)translation and rotation generators form a consistent closed algebra. We then analyze the spectrum of this algebra in order to obtain its fundamental and adjoint representations.
BOUNDARY ONE-POINT FUNCTIONS, SCATTERING, AND BACKGROUND VACUUM SOLUTIONS IN TODA THEORIES
Authors: FATEEV V. A. , ONOFRI E.
Published: March 2003

The parametric families of integrable boundary affine Toda theories are considered. We calculate boundary one-point functions and propose boundary S-matrices in these theories. We use boundary one-point functions and S-matrix amplitudes to derive boundary ground state energies and exact solutions describing classical vacuum configurations.
EXCHANGE RELATIONS OF LEVEL-TWO VERTEX OPERATORS OF $U_q (\widehat{{\rm sl}_2})$
Authors: YANG WEN-LI
Published: March 2003

We calculate the exchange relations of vertex operators of [Formula: see text] at level-two from their bosonic realization. We also study the corresponding invertibility relation of type I vertex operators.
ON THE GENERALIZED UNITARY PARASUPERSYMMETRY ALGEBRA OF BECKERS–DEBERGH
Authors: CHENAGHLOU A. , FAKHRI H.
Published: March 2003

An appropriate generalization of the unitary parasupersymmetry algebra of Beckers–Debergh to arbitrary order is presented in this paper. A special representation for realizing the even arbitrary order unitary parasupersymmetry algebra of Beckers–Debergh is analyzed by one-dimensional shape invariance solvable models, 2D and 3D quantum solvable models obtained from the shape invariance theory as well. In particular, in the special representation, it is shown that the isospectrum Hamiltonians consist of the two partner Hamiltonians of the shape invariance theory.
APPROXIMATE NEXT-TO-LEADING ORDER AND NEXT-TO-NEXT-TO-LEADING ORDER CORRECTIONS
Authors: CONTOGOURIS A. P. , MEREBASHVILI Z.
Published: March 2003

For processes involving structure functions and/or fragmentation functions, arguments that over a range of a proper kinematic variable, there is a part that dominates the next-to-leading order (NLO) corrections, are briefly reviewed. The arguments are tested against more recent NLO and in particular complete next-to-next-to-leading order (NNLO) calculations. A critical examination of when these arguments may not be useful is also presented.
STABILITY OF THE FUZZY SPHERE SOLUTION FROM MATRIX MODEL
Authors: VALTANCOLI P.
Published: March 2003

We consider a matrix model depending on the parameter λ which permits the fuzzy sphere as a classical background. By expanding the bosonic matrices around this background one recovers a U(1) (U(n)) noncommutative gauge theory on the fuzzy sphere. To check the classical stability of this background, we look for new classical solutions of this model and find them for λ < 1, that make the fuzzy sphere solution unstable for [Formula: see text] and stable otherwise.
EMERGENT RELATIVITY
Authors: LAUGHLIN R. B.
Published: March 2003

A possible resolution of the incompatibility of quantum mechanics and general relativity is that the relativity principle is emergent. I show that the central paradox of black holes also occurs at a liquid-vapor critical surface of a bose condensate but is resolved there by the phenomenon of quantum criticality. I propose that real black holes are actually phase boundaries of the vacuum analogous to this, and that the Einstein field equations simply fail at the event horizon the way quantum hydrodynamics fails at a critical surface. This can occur without violating classical general relativity anywhere experimentally accessible to external observers. Since the low-energy effects that occur at critical points are universal, it is possible to make concrete experimental predictions about such surfaces without knowing much, if anything about the true underlying equations. Many of these predictions are different from accepted views about black holes — in particular the absence of Hawking radiation and the possible transparency of cosmological black hole surfaces.
ROTATIONALLY SINGLE-PARTICLE AND VIBRATIONAL EXCITED STATES OF DEFORMABLE ODD NUCLEI WITH SMALL NONAXIALITY
Authors: SHARIPOV SH. , ERMAMATOV M. J.
Published: March 2003

Rotationally single-particle and vibrational excitations of deformable odd nuclei with small nonaxiality are investigated with allowance for the interaction of collective and single-particle states. The ratios of excitation energies, of reduced probabilities of E2 transitions, and of quadrupole moments for deformable odd nuclei with small nonaxiality are calculated up to high-spin states.
SIGNATURE INVERSION IN ODD-ODD NUCLEI IN THE MASS REGION A 100
Authors: ZHENG RENRONG , ZHU SHUNQUAN , LUO XIANGDONG
Published: March 2003

With the model of a rotor plus two quasi-particles, the signature inversion (SI) in two odd-odd nuclei102Rh and98Rh in the mass region A 100 is studied. The calculation results show that the possible SI mechanism, which has been confirmed by the calculation of odd-odd nuclei in the A 160 and A 80 regions (i.e., the competition between the n–p interaction and the coriolis force in low K space) is also appropriate for odd-odd nuclei in the A 100 region. This seems to indicate that there might be a universal mechanism of SI in odd-odd nuclei for different mass regions.
NUCLEON ELECTROMAGNETIC FORM FACTORS
Authors: GAO HAIYAN
Published: March 2003

Nucleon electromagnetic form factors are fundamental quantities related to the charge and magnetization distributions inside the nucleon. Understanding the nucleon electromagnetic structure in terms of the underlying quark and gluon degrees of freedom of quantum chromodynamics is a challenging and urgent task. The nucleon electromagnetic form factors have been studied in the past extensively in unpolarized electron scattering experiments. With the development in polarized beam, recoil polarimetry, and polarized target technologies, polarization experiments have provided more precise data on these quantities. At the same time, significant theoretical progress in areas ranging from effective field theories to lattice QCD calculations, has been made in describing these data. In this article, we review recent experimental and theoretical progress on this subject. We also provide the future outlook on this topic.
ON THE APPLICABILITY OF THE JELLIUM MODEL TO THE DESCRIPTION OF ALKALI CLUSTERS
Authors: MATVEENTSEV ANTON , LYALIN ANDREY , SOLOV'YOV ILIA A. , SOLOV'YOV ANDREY V. , GREINER WALTER
Published: March 2003

This work is devoted to the elucidation of the applicability of the jellium model to the description of alkali cluster properties. We compare the jellium model results with those derived within ab initio theoretical approaches and with experiments. On the basis of Hartree–Fock and local-density approximations we have calculated the binding energies per atom, ionization potentials, deformation parameters and optimized values of the Wigner–Seitz radii for neutral and singly charged sodium clusters with the number of atoms N ≤ 20. The characteristics calculated within the framework of the deformed jellium model are compared with the results derived from ab initio simulations of cluster electronic and ionic structure based on density functional theory and systematic post Hartree–Fock many-body perturbation theory accounting for all electrons in the system. The comparison performed demonstrates the great role of the cluster shape deformations in the formation cluster properties and quite reasonable level of applicability of the deformed jellium model. This elucidates the similarities of atomic cluster physics with the physics of atomic nuclei.
NUMBER CONSERVING APPROACH IN QUASIPARTICLE REPRESENTATION
Authors: OUDIH M. R. , FELLAH M. , ALLAL N. H.
Published: March 2003

An exact number conserving approach is formulated in the quasiparticle representation to show the effect of the particle-number projection on the ground and the first 0+ excited states. It is applied to the two-level pairing model, which allows an exact solution and a comparison to other approaches. The present method has proved to be an advantageous alternative as compared to the BCS and to the usual methods used to restore the particle number symmetry.
RELATIVISTIC MEAN FIELD CALCULATIONS OF NUCLEAR MATTER INCOMPRESSIBILITY ALONG ISOTHERMAL AND ISENTROPIC PATHS
Authors: HADDAD S.
Published: March 2003

Nuclear matter incompressibility is calculated in the framework of the relativistic mean field theory. Asymmetry reduces the incompressibility. The isothermal incompressibility decreases with increasing temperature, and the isentropic one decreases with increasing entropy. Attention is given to the incompressibility at supernova collapse conditions.
MATRIX ELEMENTS OF A HYPERBOLIC VECTOR OPERATOR UNDER SO(2,1)
Authors: ZETTILI NOUREDINE , BOUKAHIL ABDELKRIM
Published: March 2003

We deal here with the use of Wigner–Eckart type arguments to calculate the matrix elements of a hyperbolic vector operator [Formula: see text] by expressing them in terms of reduced matrix elements. In particular, we focus on calculating the matrix elements of this vector operator within the basis of the hyperbolic angular momentum [Formula: see text] whose components [Formula: see text], [Formula: see text], [Formula: see text] satisfy an SO(2,1) Lie algebra. We show that the commutation rules between the components of [Formula: see text] and [Formula: see text] can be inferred from the algebra of ordinary angular momentum. We then show that, by analogy to the Wigner–Eckart theorem, we can calculate the matrix elements of [Formula: see text] within a representation where [Formula: see text] and [Formula: see text] are jointly diagonal.
FRACTAL DIMENSIONS AND CORRECTIONS TO SCALING FOR CRITICAL POTTS CLUSTERS
Authors: AHARONY AMNON , ASIKAINEN JOONAS
Published: March 2003

Renormalization group and Coulomb gas mappings are used to derive theoretical predictions for the corrections to the exactly known asymptotic fractal masses of the hull, external perimeter, singly connected bonds and total mass of the Fortuin-Kasteleyn clusters for two-dimensional q-state Potts models at criticality. For q = 4 these include exact logarithmic (as well as log-log) corrections.
COMPLEX VISCOELASTIC BEHAVIOUR AT THE SOL-GEL TRANSITION
Authors: DE ARCANGELIS LUCILLA , DEL GADO EMANUELA , CONIGLIO ANTONIO
Published: March 2003

We present a percolation dynamic model for the study of dynamics at the sol-gel transition. Percolation and bond-fluctuation dynamics result to be suited to study the critical behaviour of the viscoelastic properties and show a complex relaxation behaviour. The results obtained via numerical simulation on the cubic lattice are in good agreement with some theoretical predictions and experimental results.
SCALING AND FINITE-SIZE EFFECTS FOR THE CRITICAL BACKBONE
Authors: BARTHELEMY M. , BULDYREV S. V. , HAVLIN S. , STANLEY H. E.
Published: March 2003

In a first part, we study the backbone connecting two given sites of a two-dimensional lattice separated by an arbitrary distance r in a system of size L. We find a scaling form for the average backbone mass and we also propose a scaling form for the probability distribution P(MB) of backbone mass for a given r. For r ≈ L, P(MB) is peaked around LdB, whereas for r ≪ L, P(MB) decreases as a power law, [Formula: see text], with τB ≃ 1.20 ± 0.03. The exponents ψ and τB satisfy the relation ψ = dB(τB - 1), and ψ is the codimension of the backbone, ψ = d - dB. In a second part, we study the multifractal spectrum of the current in the two-dimensional random resistor network at the percolation threshold. Our numerical results suggest that in the infinite system limit, the probability distribution behaves for small i as P(i) ~ 1/i where i is the current. As a consequence, the moments of i of order q ≤ qc = 0 diverge with system size, and all sets of bonds with current values below the most probable one have the fractal dimension of the backbone. Hence we hypothesize that the backbone can be described in terms of only (i) blobs of fractal dimension dB and (ii) high current carrying bonds of fractal dimension going from d red to dB, where d red is the fractal dimension of the red bonds carrying the maximal current.
ROUGHENING TRANSITION IN BRANCHING POLYMERS
Authors: LUCENA LIACIR S. , DA SILVA LUCIANO R. , ROUX STÉPHANE
Published: March 2003

A growth model, introduced to model the development of branched polymers in an heterogeneous environment, gives rise to clusters whose boundary is either faceted or rough. We study the transition between these two morphologies as a function of the parameters of the model, impurity concentration and branching ratio. The phase diagram is first obtained by direct numerical simulations, using an original algorithm, based on a self-regulated search of a critical point. Then an analytic computation of the phase boundary is proposed based on a simple approximation. The obtained phase boundary is in good agreement with the numerical results. The nature of the transition is discussed.
PERCOLATION AND CRITICAL PHENOMENA OF AN ATTRACTIVE MICELLAR SYSTEM
Authors: MALLAMACE F. , CHEN S. H. , GAMBADAURO P. , LOMBARDO D. , FARAONE A. , TARTAGLIA P.
Published: March 2003

In this work we study an attractive micellar system for which the percolation curve terminates near the critical point. We have studied such an intriguing situation by means of scattering (elastic and dynamical) and viscoelasticity experiments. Obtained data are accounted by considering in a proper way the fractal clustering processes typical of percolating systems and the related scaling concepts. We observe that the main role in the system structure and dynamics it is played by the cluster's partial screening of hydrodynamic interaction. This behaves on approaching the percolation threshold dramatic effects on the system rheological properties and on the density decay relaxations. The measured correlation functions assume a stretched exponential form and the system becomes strongly viscoelastic. The overall behavior of the measured dynamical and structural parameters indicates, that in the present micellar system, the clustering process originates dilute, polydisperse and swelling structures. Finally, this originates an interesting situation observed in the present experiment. As it has been previously, proposed by A. Coniglio et al., percolation clusters can be considered to be "Ising clusters" with the same properties as the Fisher's critical droplets. Therefore at the critical point the percolation connectedness length (ξp) can be assumed as the diverging correlation length (ξp ≡ ξ) and the mean cluster size diverges as the susceptibility.
THERMALLY DILUTED ISING SYSTEMS
Authors: MARQUÉS MANUEL I. , GONZALO JULIO A. , ÍÑIGUEZ JORGE
Published: March 2003

In this paper finite size scaling techniques are used to study the universality class of thermally diluted Ising systems, in which the realization of the disposition of magnetic atoms and vacancies is taken from the local distribution of spins in the pure original Ising model at criticality. The critical temperature, the critical exponents and therefore the universality class of these thermally diluted Ising systems depart markedly from the ones of short range correlated disordered systems. This result is in agreement with theoretical predictions previously made by Weinrib and Halperin for systems with long range correlated disorder.
CRITICAL FLUCTUATIONS IN THE BREAKDOWN OF DISORDERED SYSTEMS
Authors: PETRI ALBERTO
Published: March 2003

In this paper some critical aspects of the behaviour of breaking lattices subject to slow driving forces are briefly reviewed. In particular, fluctuations in the response to external solicitations are discussed.
CRITICAL FLUCTUATIONS IN 2D XY MAGNETS
Authors: SELLITTO M. , HOLDSWORTH P. C. W.
Published: March 2003

We give a review of the properties of low-temperature magnetic fluctuations in a finite-size 2D XY system. The behavior of such a simple model closely resembles that of several complex systems, notably the spectrum of power fluctuations in enclosed turbulent flow and interface width in surface growth problems. It suggests moreover new ideas in the study of aging phenomena in disordered systems.
COMPACTION OF GRANULAR MATTER: A SHORT REVIEW, AND THE RANDOM TETRIS MODEL
Authors: BARRAT A. , LORETO V.
Published: March 2003

We present a short review of experimental and theoretical aspects of granular compaction, and we discuss in more details the behaviour of the so-called Random Tetris Model, a model of particles diffusing on a lattice, subject to gravity and geometrical constraints. We show how this model reproduces the experimental phenomenology, e.g. slow relaxation, irreversible/reversible cycles, memory effects. The study of the density profiles allows to interpret these results.
WHY CONDUCTIVITY DECREASES WITH PRESSURE IN ION-DOPED POLYMERS
Authors: BENDLER JOHN T. , FONTANELLA JOHN J. , SHLESINGER MICHAEL F.
Published: March 2003

The relaxation time scale in glassy materials is derived within a model of anomalous defect diffusion. The effect of the defects on ion-doped polymeric glasses is to produce a stretched exponential waiting time distribution for ion jumps. The characteristic time scale for ion jumps is connected to the temperature and pressure dependent concentration of mobile defects. The resultant expression for ionic conductivity is compared with experimental results for the polymer electrolyte poly(propylene glycol) (PPG) containing LiCF 3 SO 3.
DYNAMICAL NON-LINEAR SUSCEPTIBILITY OF THE QUENCHED AND ANNEALED FRUSTRATED LATTICE GAS MODELS
Authors: DE CANDIA ANTONIO , FIERRO ANNALISA , CONIGLIO ANTONIO
Published: March 2003

In this paper we study the 3D frustrated lattice gas model in the quenched and annealed versions. In the first case, the dynamical non-linear susceptibility grows monotonically as a function of time, until reaching a plateau that corresponds to the static value. The static non-linear susceptibility diverges at some density, signaling the presence of a thermodynamical transition. In the annealed version, where the disorder is allowed to evolve in time with a suitable kinetic constraint, the thermodynamics of the model is trivial, and the static non-linear susceptibility does not show any singularity. Nevertheless, the model shows a maximum in the dynamical non-linear susceptibility at a characteristic value of the time. Approaching the density corresponding to the singularity of the quenched model, both the maximum and the characteristic time diverge. We conclude that the critical behavior of the dynamical susceptibility in the annealed model is related to the divergence of the static susceptibility in the quenched case. This suggests a similar mechanism also in supercooled glass-forming liquids, where an analogous behavior in the dynamical non-linear susceptibility is observed.
LACK OF EQUILIBRATION IN A MODEL FOR CONTINUOUSLY SUPERCOOLED LIQUIDS
Authors: CORBERI F. , CONIGLIO A.
Published: March 2003

We consider the dynamics of supercooled fluids subject to a continuous quenching procedure, with cooling rate r = dT(t)/dt. The analysis is carried out analytically in the framework of a mean field schematic model recently introduced.1 We show the existence of a glass temperature Tg(r) below which the system falls out of equilibrium. Tg(r) approaches logarithmically in r the ideal glass temperature T0 = lim r→0Tg(r), where the relaxation time diverges á la Vogel-Fulcher, similarly to some experimental observations. Well above Tg(r) a simple fluid behavior is observed. As Tg is approached from above a characteristic wave vector kd divides an high momenta equilibrated region, where a fluid-like behavior is obeyed, from the non thermalized modes with k < kd, for which time translational invariance lacks. Below Tg the system is found in a globally off-equilibrium glassy state characterized by a logarithmic decay of the density fluctuations and aging. The two time correlator decays as an enhanced power law.
EFFECTS OF AN IMPOSED FLOW ON PHASE-SEPARATING BINARY MIXTURES
Authors: CORBERI F. , GONNELLA G. , LAMURA A.
Published: March 2003

We study the phase separation of a binary mixture in uniform shear flow in the framework of the continuum convection-diffusion equation based on a Ginzburg-Landau free energy. This equation is solved both numerically and in the context of large-N approximation. Our results show the existence of domains with two typical sizes, whose relative abundance changes in time. As a consequence log-time periodic oscillations are observed in the behavior of most thermodynamic observables.
FAST RELAXATION TIME IN A SPIN MODEL WITH GLASSY BEHAVIOR
Authors: FRANZESE GIANCARLO
Published: March 2003

We consider a frustrated spin model with a glassy dynamics characterized by a slow component and a fast component in the relaxation process. The slow process involves variables with critical behavior at finite temperature Tp and has a global character like the (structural) α-relaxation of glasses. The fast process has a more local character and can be associated to the β-relaxation of glasses. At temperature T > Tp the fast relaxation follows the non-Arrhenius behavior of the slow variables. At T ≲ Tp the fast variables have an Arrhenius behavior, resembling the α - β bifurcation of fragile glasses. The model allows us to analyze the relation between the dynamics and the thermodynamics.
MOLECULAR-DYNAMICS STUDIES OF BIATOMIC SUPERCOOLED LIQUIDS: INTERMITTENCY, STICK-SLIP TRANSITION AND THE BREAKDOWN OF THE STOKES-EINSTEIN LAWS
Authors: DE MICHELE CHRISTIANO , LEPORINI DINO
Published: March 2003

The transport and the relaxation properties of a biatomic supercooled liquid are studied by molecular-dynamics methods. Both translational and rotational jumps are evidenced. At lower temperatures their waiting-time distributions decay as a power law at short times. The Stokes-Einstein relation (SE) breaks down at a temperature which is close to the onset of the intermittency. A precursor effect of the SE breakdown is observed as an apparent stick-slip transition. The breakdown of Debye-Stokes-Einstein law for rotational motion is also observed. On cooling, the changes of the rotational correlation time τ1 and the translational diffusion coefficient at low temperatures are fitted by power laws over more than three and four orders of magnitude, respectively. A less impressive agreement is found for τl with l = 2 - 4 and the rotational diffusion coefficient.
VORTEX MATTER OUT OF EQUILIBRIUM
Authors: NICODEMI MARIO
Published: March 2003

The present paper provides a short review of recent progresses in understanding out of equilibrium vortex behaviours in type II superconductors by use of a schematic coarse grained vortex model. In particular, it is possible to depict a unifying scenario for magnetic and transport properties of off-equilibrium vortex matter, ranging from the reentrant phase diagram, to magnetisation loops, "anomalous" 2-nd peak, logarithmic creep, "anomalous" finite creep rate for T → 0, "memory" and "irreversibility" in I-V characteristics, "rejuvenation" and "stiffening" of the system response.
ON THE STATISTICAL PROPERTIES OF THE LARGE TIME ZERO TEMPERATURE DYNAMICS OF THE SK MODEL
Authors: PARISI GIORGIO
Published: March 2003

Here we study the zero temperature dynamics of the Sherrington Kirkpatrick model and we investigate the statistical properties of the configurations that are obtained in the large time limit. We find that the replica symmetry is broken (in a weak sense). We also present some general considerations on the synchronic approach to the off-equilibrium dynamics, that has motivated the present study.
THE RELATIONSHIP BETWEEN THE SCALING PARAMETER AND RELAXATION TIME FOR NON-EXPONENTIAL RELAXATION IN DISORDERED SYSTEMS
Authors: RYABOV YA. E. , FELDMAN YU.
Published: March 2003

A memory function equation and scaling relationships were used for the physical interpretation of the Cole-Cole exponent. The correspondence between the relaxation time, the geometrical properties, the self-diffusion coefficient and the Cole-Cole exponent was established. Using this approach the dielectric relaxation spectra of the polymer-water mixtures and the glass transition process in the nylon 6,6 quenched, crystalline and micro-composite samples were analyzed.
SLOW DYNAMICS, AGING AND HISTORY-DEPENDENT EFFECTS IN THE PARKING-LOT MODEL
Authors: VIOT P. , TALBOT J. , TARJUS G.
Published: March 2003

We review the properties of the Parking Lot Model and their connection with the phenomenology of vibrated granular materials. New simulation results concerning the out-of-equilibrium, aging behavior of the model are presented. We investigate in particular the relation between two-time response and correlation functions and the so-called violation of the fluctuation-dissipation theorem.
STANDARD SCALING AND MULTISCALING IN PHASE ORDERING DYNAMICS
Authors: ZANNETTI MARCO , CASTELLANO CLAUDIO
Published: March 2003

The phase-ordering dynamics with conserved scalar order parameter is studied simulating the Cahn-Hilliard equation and the kinetic Ising model. In both cases a preasymptotic multiscaling regime is found revealing that the late stage of phase-ordering is always approached through a crossover from multiscaling to standard scaling, independently from the nature of the microscopic dynamics.
SCALING IN THE ATMOSPHERE: ON GLOBAL LAWS OF PERSISTENCE AND TESTS OF CLIMATE MODELS
Authors: BUNDE ARMIN , HAVLIN SHLOMO
Published: March 2003

Characterizing the complex atmospheric variability at all pertinent temporal and spatial scales remains one of the most important challenges to scientific research today.1–5 The main issues are to quantify, within reasonably narrow limits, the potential extent of global warming, and to downscale the global results in order to describe and quantify the regional implications of global change.
NONLINEAR RELAXATION IN POPULATION DYNAMICS
Authors: CIRONE MARKUS A. , DE PASQUALE FERDINANDO , SPAGNOLO BERNARDO
Published: March 2003

We analyze the nonlinear relaxation of a complex ecosystem composed of many interacting species. The ecological system is described by generalized Lotka-Volterra equations with a multiplicative noise. The transient dynamics is studied in the framework of the mean field theory and with random interaction between the species. We focus on the statistical properties of the asymptotic behaviour of the time integral of the i th population and on the distribution of the population and of the local field.
SCALING BEHAVIOUR OF A MULTIPLY CONNECTED FLUCTUATING INTERFACE IN TWO DIMENSIONS
Authors: ERZAN AYŞE , KAYA HÜSEY.IN , KABAKÇIOĞLU ALKAN
Published: March 2003

We consider a one-parameter kinetic model for a fluctuating interface which can be thought of as an infinite string decorated with infinitely many closed strings. Numerical simulations show that a number of scaling exponents describing this string system may be related to the Kardar-Parisi-Zhang exponents. However, as the average velocity of the infinite string is taken to zero, and the string system becomes an isotropic fractal set, we also find new exponents which cannot be reduced to previously known ones.
MULTILINEAL RANDOM PATTERNS EVOLVING SUBDIFFUSIVELY IN SQUARE LATTICE
Authors: GADOMSKI ADAM
Published: March 2003

Stochastic multiline evolution in square lattice is studied. It turns out that the emerging patterns evolve subdiffusively, which is characterized by the ¼ exponent. Possible origin of such a slow behavior is discussed, and some elucidation, supporting the small fractional value is given. A notion of (dynamic) phase transition concept may sometimes help in understanding the presented random kinetic behavior.
HOW TO BECOME A DICTATOR: A SIMPLE MODEL FROM PHYSICS
Authors: GALAM SERGE
Published: March 2003

The dynamics of majority rule voting in hierarchical structures is studied using concepts from collective phenomena in physics. In the case of a two-party competition a very simple model to a democratic dictatorship is presented. For each running group, a critical threshold (in the overall support) is found to ensure full and total power at the hierarchy top. However, the respective value of this threshold may vary a lot from one party to the other. It is this difference which creates the dictatorian nature of the democratic voting system. While climbing up the hierarchy, the initial majority-minority ratio can be reversed at the profit of actual running party. Such a reversal is shown to be driven by the natural inertia of being in power. The model could shed light on last century Eastern European Communist collapse.
ON FRACTIONAL RELAXATION
Authors: HILFER R.
Published: March 2003

Generalized fractional relaxation equations based on generalized Riemann-Liouville derivatives are combined with a simple short time regularization and solved exactly. The solution involves generalized Mittag-Leffler functions. The associated frequency dependent susceptibilities are related to symmetrically broadened Cole-Cole susceptibilities occurring as Johari Goldstein β-relaxation in many glass formers. The generalized susceptibilities exhibit a high frequency wing and strong minimum enhancement.
STRIPE PATTERNS IN SELF-STRATIFICATION EXPERIMENTS
Authors: LECOCQ NOÉ , VANDEWALLE NICOLAS
Published: March 2003

We report pattern formation of complex stripes with binary and ternary granular mixtures. Ternary mixtures lead to a particular ordering of the strates which was not accounted for in former explanations. Bouncing grains are found to have an important effect on strate formation. A complementary mechanism for self-stratification of binary and ternary granular mixtures is proposed. This mechanism leads to a simple model. Eventually we report the observation of self-stratification for a binary mixture of grains of the same size but with different shapes.
SCALING IN COSMIC STRUCTURES
Authors: PIETRONERO LUCIANO , BOTTACCIO MAURIZIO , MONTUORI MARCO , LABINI FRANCESCO SYLOS
Published: March 2003

The study of the properties of cosmic structures in the universe is one of the most fascinating subject of the modern cosmology research. Far from being predicted, the large scale structure of the matter distribution is a very recent discovery, which continuosly exhibits new features and issues. We have faced such topic along two directions; from one side we have studied the correlation properties of the cosmic structures, that we have found substantially different from the commonly accepted ones. From the other side, we have studied the statistical properties of the very simplified system, in the attempt to capture the essential ingredients of the formation of the observed strucures.
REVISITING THE DERIVATION OF THE FRACTIONAL DIFFUSION EQUATION
Authors: SCALAS ENRICO , GORENFLO RUDOLF , MAINARDI FRANCESCO , RABERTO MARCO
Published: March 2003

The fractional diffusion equation is derived from the master equation of continuous time random walks (CTRWs) via a straightforward application of the Gnedenko-Kolmogorov limit theorem. The Cauchy problem for the fractional diffusion equation is solved in various important and general cases. The meaning of the proper diffusion limit for CTRWs is discussed.
LEARNING IN AN OSCILLATORY CORTICAL MODEL
Authors: SCARPETTA SILVIA , LI ZHAOPING , HERTZ JOHN
Published: March 2003

We study a model of generalized-Hebbian learning in asymmetric oscillatory neural networks modeling cortical areas such as hippocampus and olfactory cortex. The learning rule is based on the synaptic plasticity observed experimentally, in particular long-term potentiation and long-term depression of the synaptic efficacies depending on the relative timing of the pre- and postsynaptic activities during learning. The learned memory or representational states can be encoded by both the amplitude and the phase patterns of the oscillating neural populations, enabling more efficient and robust information coding than in conventional models of associative memory or input representation. Depending on the class of nonlinearity of the activation function, the model can function as an associative memory for oscillatory patterns (nonlinearity of class II) or can generalize from or interpolate between the learned states, appropriate for the function of input representation (nonlinearity of class I). In the former case, simulations of the model exhibits a first order transition between the "disordered state" and the "ordered" memory state.
FLUID FLOW THROUGH DISORDERED POROUS MEDIA
Authors: STANLEY H. E. , ARAÚJO A. D. , COSTA U. M. S. , ANDRADE J. S.
Published: March 2003

This talk briefly reviews the subject of fluid flow through disordered media. First, we use two-dimensional percolation networks as a simple model for porous media to investigate the dynamics of viscous penetration when the ratio between the viscosities of displaced and injected fluids is very large. The results indicate the possibility that viscous displacement through critical percolation networks constitutes a single universality class, independent of the viscosity ratio. We also focus on the sorts of considerations that may be necessary to move statistical physics from the description of idealized flows in the limit of zero Reynolds number to more realistic flows of real fluids moving at a nonzero velocity, when inertia effects may become relevant. We discuss several intriguing features, such as the surprisingly change in behavior from a "localized" to a "delocalized" flow structure (distribution of flow velocities) that seems to occur at a critical value of Re which is significantly smaller than the critical value of Re where turbulence sets in.
SOCIOPHYSICS — A REVIEW OF RECENT MONTE CARLO SIMULATIONS
Authors: STAUFFER D.
Published: March 2003

Computational models for social phenomena are reviewed: Bonabeau et al. for the formation of social hierarchies, Donangelo and Sneppen for the replacement of barter by money, Solomon and Weisbuch for marketing percolation, and Sznajd for political persuasion. Finally we review how to destroy the internet.
REMARKS ON THE NONUNIVERSALITY OF BOLTZMANN-GIBBS STATISTICAL MECHANICS
Authors: TSALLIS C.
Published: March 2003

How general are Boltzmann-Gibbs statistical mechanics and standard Thermodynamics? What classes of systems have thermostatistical properties, in particular equilibrium properties, that are correctly described by these formalisms? The answer is far from trivial. It is, however, clear today that these relevant and popular formalisms are not universal, this is to say that they have a domain of validity that it would be important to define precisely. A few remarks on these questions are herein presented, in particular in relation to nonextensive statistical mechanics, introduced a decade ago with the aim to cover at least some (but most probably not all) of the natural systems that are out of this domain of validity.
EFFECT OF DAMAGE ON THE ROUGHNESS OF PLANAR CRACKS: THE CASE OF THE RANDOM FUSE MODEL
Authors: ZAPPERI STEFANO , HERRMANN HANS J. , ROUX STÉPHANE
Published: March 2003

We investigate the effect on the roughness of microcrack nucleation ahead of a propagating planar crack and study the structure of the damage zone. To this end we consider a quasi-two dimensional random fuse model, confining the crack between two horizontal plates. The two-dimensional geometry introduces a characteristic length in the problem, limiting the crack roughness. The damage ahead of the crack does not appear to change the scaling properties of the model, which are well described by gradient percolation.
Strategies to Motivate Brokers Adopting On-line Trading in Hong Kong Financial Market
Authors: Lau Adela S. M.
Published: March 2003

This paper aims to study what factors affect the adoption of online trading towards brokers in Hong Kong. By using the adoption model, Decomposed Version Theory of Planned Behavior (DTPB), we identify the factors that affect brokers towards online trading. A hypothesized model has been proposed to design the questionnaire. A statistical analysis has been conducted to investigate whether the attributes, variables, and belief structure of the proposed model correlated with each other or not. After such analysis, the factors that influenced brokers' behavior have been identified as well as the strengths of their relationships. Such results are very helpful to support the planning of related parties in launching Internet trading.
THE TREND TOWARD OUTSOURCING IN NEW PRODUCT DEVELOPMENT: CASE STUDIES IN SIX FIRMS
Authors: ZHAO YUSHAN , CALANTONE ROGER J.
Published: March 2003

In the constant drive for higher quality, lower cost, and faster-to-market products, many firms have begun to learn "how not to make things" — how to give some tasks to other firms who could make more efficiently. Examples from industries highlight the trend. Case studies were conducted in six firms and many insightful comments from prominent managers are incorporated.

The case studies reveal a trend toward outsourcing some tasks in new product development. We use the transaction cost theory and the resource-based theory to explain the trend of outsourcing. This kind of outsourcing allows the firm to focus on core tasks and access resources and capabilities not available or not easily developed internally. NPD program performance can be greatly enhanced, and the R&D department can move away from routine administration toward a more strategic role. Many implications for managers are offered, and theoretical contributions are discussed.
Superparamagnetic Iron Oxide–Based Method for Quantifying Recruitment of Monocytes to Mouse Atherosclerotic Lesions In Vivo
Authors: Litovsky Silvio , Madjid Mohammad , Zarrabi Alireza , Casscells S. Ward , Willerson James T. , Naghavi Morteza
Published: March 2003

Background—

It has been found recently that the MRI contrast agent superparamagnetic iron oxide (SPIO) localizes to aortic atherosclerotic plaques. We therefore asked whether SPIO might be used to monitor monocyte recruitment into aortic atherosclerotic plaques.

Methods and Results—

Eleven female apo E knockout (K/O) mice, each 11 months old, were divided into 2 groups. Six mice received tissue necrosis factor-α (0.2 μg IP once), interleukin-1β (0.2 μg IP once), and interferon-γ (100 U/g per day IP for 5 days); 5 received 0.5 mL saline containing1% BSA and served as sham-treated atherosclerotic controls. Two wild-type C57BL/6 mice served as sham-treated nonatherosclerotic controls. Three hours after initial cytokine or sham treatment, all mice received SPIO by intravenous injection (1 mmol/kg iron). Six days later, all mice were euthanized, the hearts and aortas were perfused under physiological pressure, and the entire aortas were studied histologically. Atherosclerotic plaques in cytokine-treated mice contained more iron-positive macrophages per cross section than did those in sham-treated apo E K/O control mice (42±11.8 versus 11.6±5.9) (
P
<0.0001). Iron-laden macrophages were present either in subendothelial plaque surfaces or in thin layers overlying the internal elastic lamina, often at the edges of atherosclerotic plaques. No iron deposition was seen in aortas of the wild-type nonatherosclerotic control mice. Immunocytochemistry showed mostly macrophages and few T lymphocytes in atherosclerotic plaques of cytokine-treated mice.

Conclusions—

SPIO allows detection of iron-laden macrophages in the aortic subendothelium of apo E–deficient mice under basal conditions and monitoring of monocyte recruitment after cytokine injection.
Small GTP-Binding Protein Rac Is an Essential Mediator of Vascular Endothelial Growth Factor-Induced Endothelial Fenestrations and Vascular Permeability
Authors: Eriksson Anna , Cao Renhai , Roy Joy , Tritsaris Katerina , Wahlestedt Claes , Dissing Steen , Thyberg Johan , Cao Yihai
Published: March 2003

Background—

Vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) induces both angiogenesis and vascular permeability. Although its angiogenic activity has been well characterized, the signaling pathways of VEGF-induced permeability remain poorly understood.

Methods and Results—

Using the mouse corneal micropocket assay, Miles assay, and a combination of cytochemical, electron microscopic, and biochemical assays, we demonstrate that VEGF-induced vascular leakage partly can be separated from its angiogenic activity. VEGF but not FGF-2 induced capillaries with a highly fenestrated endothelium, a feature linked with increased vascular permeability. A cell-permeable Rac antagonist (TAT-RacN17) converted VEGF-induced, leaky vascular plexuses into well-defined vascular networks. In addition, this Rac mutant blocked formation of VEGF-induced endothelial fenestrations and vascular permeability but only partially inhibited angiogenesis. Studies on endothelial cell cultures further revealed that VEGF stimulated phosphorylation of VEGF receptor-2 (VEGFR-2), leading to activation of Rac as well as increased phosphorylation of phospholipase Cγ (PLCγ), protein kinase B (Akt), endothelial nitric oxide synthase (eNOS), and extracellular regulated kinase (Erk1/2). We further found that phosphatidylinositol-3-OH kinase (PI3K) acted upstream of Rac and Akt-eNOS in VEGF/VEGFR-2 signaling.

Conclusions—

Our findings indicate that the small GTP-binding protein Rac is a key component in mediation of VEGF-induced vascular permeability but less so in neovascularization. This may have conceptual implications for applying Rac antagonists in treatment and prevention of VEGF-induced vascular leakage and edema in connection with ischemic disorders.