bluuebunny/crossref_metadata_2025 huggingface dataset:
MAGNETOHYDRODYNAMIC MELTING FLOW FROM A HORIZONTAL ROTATING DISK
Authors: ANDERSSON H.I. , HOLMEDAL B. , DANDAPAT B.S. , GUPTA A.S.
Published: November 2004

Melting from a horizontal solid surface in the shape of a disk rotating about a vertical axis in the presence of a uniform transverse magnetic field is analyzed. The flow is governed by a dimensionless magnetic parameter M and another dimensionless parameter α representing the relative importance of melt rate and rotation times the viscosity. Similarity solutions of the nonlinear MHD equations are obtained by perturbations for small α and numerical integration for arbitrary α. A novel result of the analysis is that for M=1, two different solutions exist in a small α-range (0.170≤α<0.174) for the same value of α. One solution is the ‘thin-film’ solution similar to the non-magnetic case (M=0) while the ‘thick-film’ solution represents a situation with a stagnant fluid layer on top of a flowing fluid adjacent to the rotating disk. No solution exists when the melt rate a exceeds the critical value αs=0.174 and this αs decreases with the increase in M. Further the melt rate for which steady state solution exists decreases with increasing M. However, the magnetic field seems to effectively control the total film thickness. Torque required for the rotation as well as heat transfer rates at the boundaries are found for variations in α, M and the Prandtl number Pr.
CHARACTERIZATION OF THE MEMBRANE THEORY OF A CLAMPED SHELL: THE PARABOLIC CASE
Authors: PIILA JYRKI , PITKÄRANTA JUHANI
Published: November 2004

We study the membrane-dominated deformation state of a cylindrical or conical shell, the lateral shape of which is that of a curved polygon. The shell is assumed to be loaded by a smoothly varying surface traction distribution and rigidly supported (clamped) on its whole boundary. Under these assumptions, a precise mathematical formulation is given for the asymptotic membrane theory corresponding to the limit where the shell becomes infinitely thin. The asymptotic solution is constructed explicitly, and a convergence result relating the actual deformation field to the asymptotic field is proven. The analysis is based on the classical shell model of Koiter-Sanders-Novozhilov.
THE BOLTZMANN EQUATION AND THE GROUP TRANSFORMATIONS
Authors: BOBYLEV A.V.
Published: November 2004

This paper is devoted to the investigation of group properties of the nonlinear Boltzmann equation. The complete Lie group of invariant transformations for the spatially inhomogeneous Boltzmann equation is constructed. The generalization to the Lie-Backlund groups is given for the spatially homogeneous case. It is shown that there are only two non-trivial group transformations for the Boltzmann equation in the wide class of Lie and Lie-Backlund transformations. Some consequences of these symmetry properties are discussed. The special role of Galileo group and the analogy between the spatially homogeneous Boltzmann equation and the full equation are also investigated.
CONTINUOUS DEPENDENCE ON A PARAMETER OF THE SOLUTIONS OF IMPULSIVE DIFFERENTIAL EQUATIONS IN A BANACH SPACE
Authors: BAINOV D.D. , KOSTADINOV S.I. , MINH NGUYEN VAN , ZABREIKO P.P.
Published: November 2004

Continuous dependence of the solutions of an impulsive differential equation on a small parameter is proved under the assumption that the right-hand side of the equation and the impulse operators satisfy conditions of Lipschitz type.
ON THE MATHEMATICAL MODELLING OF CRYSTAL GROWTH IN A BINARY NONREACTING MIXTURE
Authors: IANNECE D. , ROMANO A.
Published: November 2004

A model for the growth of a crystal in a classical mixture is proposed on the basis of the nonlocal thermomechanics of continua with an interface and of a new physical interpretation of localization residuals.
GLOBAL SOLUTION TO A MODEL FOR CELL MORPHOGENESIS BY CALCIUM-REGULATED STRAIN FIELDS
Authors: COLLI PIERLUIGI
Published: November 2004

In this paper we prove an existence and uniqueness result for a time-dependent problem related to a mechanochemical model of cellular morphogenesis, based on calcium ion regulation of the viscoelastic properties of the cellular cortex. Calcium input and output processes, as well as diffusive effects, are accounted in the description of the cell dynamics. The resulting system of nonlinear partial differential equations consists of the balance laws for the concentrations of free calcium and bound (to specific macro-molecules) calcium, coupled with the equilibrium equations for the displacements. It is shown that the initial-boundary value problem has only one solution which satisfies suitable boundedness estimates regarding calcium concentrations.
TWO METHODS FOR ASSESSING THE SIZE OF EXTERNAL PERTURBATIONS IN CHAOTIC PROCESSES
Authors: MOUS SIPKO L.J. , GRASMAN JOHAN
Published: November 2004

This paper deals with the assessment of an external perturbation in nonlinear chaotic dynamical processes using either a modified sentinel function or an extended Kalman filter treatment. We consider processes that can be modeled by a system of nonlinear ordinary differential equations. The sentinel function is used to detect an external perturbation, that is not included in the model of the process. In cases where the time dependency of the external perturbation is known but the size of the perturbation is unknown, the sentinel function is also used to estimate the size of this perturbation. We have compared this approach to estimate the size of a perturbation with an extended Kalman filter treatment and as an example to illustrate these two approaches we have analyzed a lower order spectral model of the atmospheric circulation with a perturbed equator-pole temperature gradient.
AN INTEGRO-DIFFERENTIAL EQUATION ARISING IN RADIONUCLIDE TRANSPORT THROUGH FRACTURED ROCK
Authors: CASSELL J.S. , WILLIAMS M.M.R.
Published: November 2004

An integro-differential equation arising in the transport of radionuclides through fractured rock has been studied. Using a special form for the velocity redistribution function at fracture intersections, it has been possible to obtain an analytical solution. Numerical results are given to illustrate the theory and its physical interpretation.
EXACT SOLUTIONS FOR KINETIC EQUATIONS OF DISCRETE AND SEMI-DISCRETE MODELS
Authors: TIEM DANG HONG
Published: November 2004

New methods are proposed to construct exact solutions for kinetic equations of discrete and semi-discrete models. They are applied to some particular models. The solutions so obtained are used to study the flows of the gas between two parallel planes and the plane shock wave structures.
STEADY FLOWS OF VISCOUS COMPRESSIBLE FLUIDS IN EXTERIOR DOMAINS UNDER SMALL PERTURBATIONS OF GREAT POTENTIAL FORCES
Authors: NOVOTNÝ ANTONÍN
Published: November 2004

We investigate the steady compressible flows in three-dimensional exterior domains, in R3 and [Formula: see text], under the action of small perturbations of large potential forces and zero velocity at infinity. We prove existence and uniqueness of solutions in L2-spaces, and study their regularity as well as the decay at infinity.
A NONLINEAR MATHEMATICAL MODEL OF PRESSURE PRESET VENTILATION: DESCRIPTION AND LIMITING VALUES FOR KEY OUTCOME VARIABLES
Authors: CROOKE, III PHILIP S. , MARINI JOHN J.
Published: November 2004

In recent years, several new forms of pressure preset mechanical ventilation (PPV) have been introduced to clinical practice. Although these modes are widely employed in patient care, clinical decision making remains a largely empirical “trial and error” process. Existing predictive equations for ventilation are questionably accurate, in part because most attempts to model ventilation have assumed constant values for inspiratory and expiratory resistance, even though the pressure-flow relationship is clearly nonlinear in biological systems. In this paper, we present and analyze a nonlinear mathematical model of PPV which accounts for the interactive behavior of inspiratory and expiratory half cycles. It comprises a set of nonlinear differential equations which incorporate a variably nonlinear relationship between the resistive component of the applied pressure and flow rate. This model is compared to our previously described biphasic (linear) exponential model of PPV (J. Appl. Physiol.67 (1989) 1081–0192) which serves to link the clinical “input” variables of pressure level, frequency, inspiratory time fraction, and impedance with the key “outcome” variables of clinical interest: tidal volume, minute ventilation, power, airway pressure, mean alveolar pressure, and expiratory alveolar pressure. Predictive differences arise between linear and nonlinear formulations. Although general closed-form solutions for several of the outcome variables could not be obtained, implicit expressions are derived. Explicit derivations are also presented for selected flow exponents of interest. Furthermore, we found that the limiting values for each outcome variable as a function of cycling frequency could be derived explicitly, once the exponent for flow is uniquely specified.
EVALUATION OF TASK ALLOCATION IN MESH-BASED MULTICOMPUTERS USING GENETIC, NEURAL, AND TRADITIONAL ALGORITHMS
Authors: McCONNELL R.A. , MENEZES B.L.
Published: November 2004

This article compares three techniques for allocating tasks in a mesh-based multi-computer. Tasks are expressed as rectangles of a certain width and height corresponding to the topology of processors desired. The task allocation problem, is thus a variant of the bin-packing problem, with one major difference: in the bin-packing problem one seeks to minimize the height of the bin, while here we seek to maximize the utilization of processors in a multicomputer. The three techniques compared are a classical level-by-level algorithm, a connectionist simulated annealing variant of the Hopfield network, and a genetic algorithm. An extension to the dynamic processor allocation problem is modeled by fixing some rectangles in place and packing the request rectangles in the residual space on the mesh; this corresponds to a pre-existing condition, i.e., some tasks have already been allocated to the Processor Mesh. Implementation and experimental results are presented.
AN ASSOCIATIVE DATA PARALLEL COMPILATION MODEL FOR TIGHT INTEGRATION OF HIGH PERFORMANCE KNOWLEDGE RETRIEVAL AND COMPUTING
Authors: BANSAL ARVIND K.
Published: November 2004

Associative Computation is characterized by intertwining of search by content and data parallel computation. An algebra for associative computation is described. A compilation based model and a novel abstract machine for associative logic programming are presented. The model uses loose coupling of left hand side of the program, treated as data, and right hand side of the program, treated as low level code. This representation achieves efficiency by associative computation and data alignment during goal reduction and during execution of low level abstract instructions. Data alignment reduces the overhead of data movement. Novel schemes for associative manipulation of aliased uninstantiated variables, data parallel goal reduction in the presence multiple occurrences of the same variables in a goal. The architecture, behavior, and performance evaluation of the model are presented.
LOGIC PROGRAMMING AND DEFAULT LOGIC
Authors: ANTONIOU GRIGORIS
Published: November 2004

We present several ideas of increasing complexity how to translate default theories to normal logic programs that make direct use of the deductive capacity of logic programming. We show the limitations of simple, ad hoc approaches, and arrive at a more general construction; its main property is that the answer substitutions computed by the logic program via its standard operational semantics correspond exactly to the extensions of the default theory.
A SPELLING CORRECTION SYSTEM FOR MODERN GREEK
Authors: VAGELATOS A. , TRIANTOPOULOU T. , TSALIDIS C. , CHRISTODOULAKIS D.
Published: November 2004

Within the framework of a project yielding to the development of an interactive spelling checking/correction system for Modern Greek (M.G.) to run on MS-DOS based computers, our team comprised of several computer engineers and linguists, undertook the following preliminary tasks: The examination and evaluation of pertinent existing research/work from both the computer engineering and linguistic fields, and conducted supplementary research deemed necessary for the purposes of the project. The overall objectives focused on the development of a system that would be convenient to run and use. Unlike similar current systems however, emphasis was given to optimal engineering quality and performance and moreover, optimal linguistic performance attained through substantial linguistic expertise backing.
A THEORY REVISION APPROACH FOR CONCEPT LEARNING
Authors: CHEN PO-CHI , YU YONG-NENG , HWANG SHU-YUEN
Published: November 2004

Concept learning from examples in first-order languages has been widely studied recently. Specifically, many systems that integrate inductive learning and explanation-based learning have been proposed. However, concept learning is only a subproblem of the problem of knowledge base (which is referred to as a theory in first-order logic) revision. This is mainly because concept learning methods utilize background knowledge without regard to whether the knowledge is perfect or imperfect, while a knowledge base revision system should revise the knowledge base to be consistent with all environmental changes.

This paper presents a real theory revision method that guarantees the revised theory to be correct on all given examples. As a consequence, the problem of concept learning is also solved through the proposed method.

The proposed method is a two-phase approach. In the first phase, the input theory is generalized to cover all positive examples. Theoretically, this can be done by existing concept learning systems. The second phase then specializes the theory to exclude negative examples. The specialization must not cause excessive exclusion of covered positive examples. The paper focuses on designing such a specialization algorithm. Experimental results show that the proposed algorithm can mitigate the over-specialization problem.
AN ARCHITECTURE FOR DYNAMICALLY INTERACTING AGENTS
Authors: MÜLLER JÖRG P. , PISCHEL MARKUS
Published: November 2004

In this paper, we present the layered agent architecture INTERRAP which has been developed to cope with the basic requirements for Cooperative Intelligent Systems (CIS): agents shall behave in a situated, efficient, and goal-directed manner, and they shall be able to interact (i.e. coordinate and collaborate) with other agents. Over the past few years, agent architectures combining reactive with deliberative facilities have become very trendy in DAI. However, most attempts end up at the local planning layer and fail to take into account important mechanisms for interaction and collaboration among agents. INTERRAP extends previous attempts to build layered architectures by a cooperation component which holds cooperation knowledge as well as a library of joint plant. The modules of the model and the flow of control among them are explained. The model is described and evaluated by the FORKS application, the simulation of an automated loading-dock.
COOPERATIVE MODELING IN APPLIED GEOGRAPHIC RESEARCH
Authors: ALONSO GUSTAVO , ABBADI AMR EL
Published: November 2004

The characteristics of geographic data and the nature of geographic research require the participation of many agents. Data is generated by multiple sources (satellites, ground observation, weather stations, photography, etc.), accessed, processed and transformed by many users and available for use to an even larger population of users. Lack of coordination among all these different agents may render large amounts of work useless. Most existing GIS (Geographic Information Systems) do not provide any support for cooperative work, which adds to the problem. To overcome this serious limitation while still allowing users to take advantage of GIS technology, we propose GOOSE, a system implemented as a top layer for existing GIS. GOOSE provides the tools for constructing large geographic models in a cooperative environment with potentially many users and participants.
SWIFT:

S

YSTEM

W

ORKBENCH FOR

I

NTEGRATING AND

F

ACILITATING

T

EAMS
Authors: LU STEPHEN , SMITH KEN , HERMAN ALLEN , MATTOX DAVE , SILLIMAN MIKE , LUCENTI MARTY , JACOBS JIM , CHAZIN DAVE , LAWLEY MARK , CASE MIKE
Published: November 2004

There have been many R&D efforts in recent years to develop computer environments that directly enhance group problem-solving productivity. An example of such efforts is the computer-based Virtual Teaming Technology (VTT) currently being developed at the Knowledge-based Engineering Systems Research Laboratory (KESRL). The core software environment for KESRL's VTT is called SWIFT (System Workbench for Integrating and Facilitating Teams) and is based on the knowledge processing technology (KPT) previously developed at KESRL to support various engineering design tasks. SWIFT is a flexible environment which enables the rapid development of collaborative applications, linking workers in distributed environments, of many domains. This paper presents the overall system architecture of SWIFT, and introduces the current and future R&D efforts at KESRL in realizing SWIFT for significant industrial applications.
EXTENDING GROUP COMMUNICATION FACILITIES TO SUPPORT COMPLEX DISTRIBUTED OFFICE PROCEDURES
Authors: SCHILL ALEXANDER , GUETTER DIETBERT
Published: November 2004

Complex distributed office procedures are based on sequential and parallel execution of basic services offered by a distributed service environment. Office procedure execution can be considered to be a special kind of group communication with groups of collaborating servers. This paper first presents a general group communication abstraction. We then show in detail how the generic approach has been extended and specialized in order to support complex office procedures. The extended solution comprises a graph-based, declarative specification notation for office procedures, and a distributed runtime support environment. This maps office procedure service requests dynamically to actual servers for execution. Moreover, additional management facilities enable external supervision of office procedures. Based on examples, we show how applications can benefit from the abstractions. By discussing their similarities and evolution, we also outline the strong relationship between group communication and office procedures.
AMALGAMATING KNOWLEDGE BASES II: DISTRIBUTED MEDIATORS
Authors: ADALI SIBEL , SUBRAHMANIAN V. S.
Published: November 2004

Integrating knowledge from multiple sources is an important aspect of automated reasoning systems. In [23], we presented a uniform declarative and operational framework, based on annotated logics, for amalgamating multiple knowledge bases and data structures (e.g. relational, object-oriented, spatial, and temporal structures) when these knowledge bases (possibly) contain inconsistencies, uncertainties and non-monotonic modes of negation. We showed that annotated logics may be used, with some modifications, to mediate between different knowledge bases. The multiple knowledge bases are amalgamated by embedding the individual knowledge bases into a lattice. In this paper, we describe how, given a network of sites where the different databases reside, it is possible to define a distributed semantics for amalgamated knowledge bases. More importantly, we study how the mediator may be distributed across multiple sites so that when certain conditions are satisfied, network failures do not affect the end results of queries that a user may pose. We specify different ways of distributing the mediator to protect against different types of network link failures and develop alternative soundness and completeness results.
BUILDING A FEDERATED RELATIONAL DATABASE SYSTEM: AN APPROACH USING A KNOWLEDGE-BASED SYSTEM
Authors: BLANCO JOSÉ MIGUEL , ILLARRAMENDI ARANTZA , GOÑI ALFREDO
Published: November 2004

Due to the emerging interest in integrating different application environments, there have been many recent proposals for federated systems. In this paper, a federated system that permits the integration of heterogeneous relational databases using a terminological knowledge representation system is presented. In particular, two of the system's components: the translator and the integrator are explained in depth. The translator permits one to obtain a terminology from a relational schema, either semiautomatically, by expressing database properties, or manually, by using a set of predefined operations. In turn, the integrator generates a federated terminology by integrating several terminologies using the semantics expressed as correspondences between the data elements of different terminologies. Unlike many other approaches, the use of a terminological system permits us to obtain a semantically richer federated terminology and, at the same time, define a wider and more consistent integration process.
MANY CLASSICAL KNOT INVARIANTS ARE NOT VASSILIEV INVARIANTS
Authors: DEAN JOHN
Published: November 2004

We show that under twisting, a Vassiliev invariant of order n behaves like a polynomial of degree at most n. This greatly restricts the values that a Vassiliev invariant can take, for example, on the (2, m) torus knots. In particular, this implies that many classical numerical knot invariants such as the signature, genus, bridge number, crossing number, and unknotting number are not Vassiliev invariants.
AN UPPER BOUND FOR THE NUMBER OF VASSILIEV KNOT INVARIANTS
Authors: CHMUTOV S. V. , DUZHIN S. V.
Published: November 2004

We prove that the number of independent Vassiliev knot invariants of order n is less than (n − 1)! — thus strengthening the a priori bound (2n − 1)!!
A JONES TYPE INVARIANT OF LINKS IN THE PRODUCT SPACE OF A SURFACE AND THE REAL LINE
Authors: INOUE KAORI , KANETO TAKESHI
Published: November 2004

We define invariants < L)−1 and FL(A) for links L in Σ × R where Σ is a surface by using the idea of Kauffman bracket. We compute < L)−1 in case of Σ = P2, a projective plane. In case of Σ = T2, a torus, we show examples of computations of FL(A) for a certain class of links L in T2 × R related to genus 1 Heegaard diagrams of lens spaces and a relation among them. This relation implies that FL(A) is a topological invariant for lens spaces in a certain sense.
THE FUNCTORIALITY OF VASSILIEV-TYPE INVARIANTS OF LINKS, BRAIDS, AND KNOTTED GRAPHS
Authors: STANFORD TED
Published: November 2004

We define a category to express certain relationships among different kinds of embedding types of graphs in R3, which include links and braids. We define Vassiliev-type invariants in terms of a functor to the category of abelian groups, and we give some applications of this point of view.
DNA KNOT FORMATION IN AQUEOUS SOLUTIONS
Authors: SHAW STANLEY Y. , WANG JAMES C.
Published: November 2004

The knotting probability of a closed chain has been calculated as a function of chain dimensions and solvent properties in a number of studies. We have measured the probability of DNA knot formation upon random cyclization of linear DNA in vitro to provide an experimental test of the various theoretical treatments of the problem; parameters of these models, such as the effective chain diameter of DNA, were calculated in different concentrations of counterions. Our results in the presence of sodium ions agree well with theoretical treatments of DNA as a polyelectrolyte; knotting data in the presence of divalent magnesium ions indicate that moderate concentrations of magnesium ions can induce an attractive potential between DNA segments, resulting in negative values of the calculated effective DNA helix diameter. We discuss structures in which the divalent magnesium counterion facilitates the close apposition of two DNA segments, and review the effect of chemical- and protein-mediated crosslinks between DNA segments on DNA knot formation. Finally, we consider DNA knot formation in vivo.
TABULATING ALTERNATING KNOTS THROUGH 14 CROSSINGS
Authors: ARNOLD BRIAN , AU MICHAEL , CANDY CHRISTOPER , ERDENER KAAN , FAN JAMES , FLYNN RICHARD , MUIR ROBS JOHN , WU DANNY , HOSTE JIM
Published: November 2004

We tabulate all prime alternating knots through fourteen crossings. This provides the first list of 14-crossing prime alternating knots as well as the first confirmation of Thistlethwaite's tabulation of 12- and 13-crossing alternating knots.
ALEXANDER POLYNOMIAL OF A CURVE OF DEGREE SIX
Authors: DEGTYAREV ALEXANDER
Published: November 2004

The complete description of the Alexander polynomial of the complement of an irreducible sextic in [Formula: see text] is given. Some general results about Alexander polynomials of algebraic curves are also obtained.
ON BOTT POLYNOMIALS
Authors: WANG ZHENGHAN
Published: November 2004

R. Bott defined two combinatorial invariants for finite cell complexes in the 1950's [2]. As described in [3], they fit beautifully into a state model framework. Recently, it has been observed that for finite graphs, the coefficients of this polynomial are the same set of invariants as defined by H. Whitney in [5]. In section 1, we define the Bott-Whitney polynomial and prove some of its basic properties. In section 2, we show that for a planar connected graph, the Bott-Whitney polynomial is essentially the chromatic polynomial of its dual graph. In section 3, an interpretation of the coefficients of the Bott-Whitney polynomial is given following Whitney [5]. In section 4, we study more general Bott polynomials.
RESONANCES IN HEAVY-ION REACTIONS: AN OVERVIEW OF CURRENT MODELS
Authors: ABBONDANNO UGO , CINDRO NIKOLA
Published: November 2004

Models of resonances in heavy-ion reactions are reviewed on the basis of recent experimental and theoretical results. Qualitative and quantitative agreement between experimental data and calculated quantities is examined. For nuclear systems where a sufficient quantity of data is available, a unified quasi-molecular description is presented. Future perspectives are discussed.
THE QUARK MODEL, DEUTERON FORM FACTORS AND NUCLEAR MAGNETIC MOMENTS
Authors: FAESSLER AMAND , BUCHMANN A. , YAMAUCHI Y.
Published: November 2004

The study of the deuteron electromagnetic form factors based on the quark cluster model is reviewed. The deuteron wave function is derived from a microscopic quark Hamiltonian with the help of the Resonating Group Method. One-pion and one-gluon exchange potentials are included in addition to a quadratic confinement potential. The photon is coupled directly to the quarks. Aside from the one-body impulse current, pion and gluon exchange currents are included on the quark level. Due to the Pauli principle on the quark level, new electromagnetic currents arise which are not present on the nucleon level. These currents, called quark exchange currents, describe processes in which a photon couples to a quark or a pair of quarks interacting via gluon or pion exchange and which are accompanied by a simultaneous quark interchange between the two threequark clusters (nucleons). They are small for low momentum transfers but appreciably influence the electromagnetic structure of the deuteron beyond a momentum transfer of q=5 fm−1. The discussion is extended to the magnetic moments of 15N, 17O and 39K by introducing the quark exchange currents as effective operators on the nucleon level. The quark exchange currents written in terms of nonlocal and spin-isospin dependent nuclear operators are effective only at short distances. They are evaluated with shell-model (harmonic oscillator) wave functions including the (short-range) Brueckner correlations. The Bethe-Goldstone equation is solved with our effective NN potential, which is derived from a microscopic quark Hamiltonian. The quark exchange currents shift the isovector magnetic moment of 39K by −20% from its Schmidt value.
OCTUPOLE CORRELATIONS IN 152Eu AND 154Eu
Authors: NOSEK D. , SHELINE R.K. , SOOD P.C. , KVASIL J.
Published: November 2004

The structures of the low-lying intrinsic states in 152 Eu and 154 Eu are calculated using a microscopic quasiparticle phonon model similar to that of Soloviev. Experimental data with specific emphasis on stripping and pick-up cross-sections on 153 Eu are in agreement with the calculations. Octupole correlations between these calculated intrinsic states are analyzed. The opposite parities and appropriate octupole correlations of several of the states provide a theoretical basis for the previous interpretation of parity doublets in 152 Eu and 154 Eu . The E1 enhancements of the ΔK=0 transitions in both nuclei are also discussed.
COMPLEXITY OF HADRONIC AMPLITUDES VIA QUARK LOOPS
Authors: MITRA A.N. , SANTHANAM I. , ESSAGHOLIAN A.
Published: November 2004

The structure of hadronic transition amplitudes h→h′+h″ via quark triangle loops is investigated in terms of hadron quark vertex functions [Formula: see text], using for illustration the case of the ρ→ππ transition. A Bethe-Salpeter model based on the Covariant-Instantaneity-Ansatz (CIA) for its kernel which provides an exact interconnection between the 3D and 4D forms the BS wave function, determines the structure [Formula: see text]. The nonlocality feature inherent in the vertex function causes the imaginary part of gρππ calculated from the loop integral to be generally different from its dispersion relation value which would be obtained from analyticity of gρππ in the ρ-mass. Pending a proper understanding of this nonlocality (associated with confining interactions) only the real part of gρππ is found unambiguous while the imaginary part is model-dependent.
REAL SOLUTION OF THE COMPLEX RANDOM PHASE APPROXIMATION EQUATION
Authors: TERUYA N. , KYOTOKU M. , DIAS H.
Published: November 2004

The description of several physical phenomena may require the solution of a complex eigenvalue problem of a non-Hermitian matrix. This problem may be met in the description of some nuclear and plasmon collective excitations using the linear-response theory. It is shown that there exists a related real matrix which satisfies the usual standard real eigenvalue problem whose solution yields directly the solution of the original problem.
SOME CHARACTERISTICS OF MULTIPLE HELIUM FRAGMENTS PRODUCED IN HEAVY ION COLLISIONS AT DUBNA ENERGY
Authors: EL-NADI M. , SHERIF M.M. , EL-SALAM A. ABD , YASIN M.N. , BAKR A. , EL-NAGDY M.S. , JILANY M.A.
Published: November 2004

Within the experimental errors the interaction mean free paths of He-fragments produced by the collisions of 12 C , 22 Ne and 28 Si nuclei at 4.5 A GeV/c in nuclear emulsion have been found to be independent of the He-multiplicity and the distance from the interaction point. Evidence for the multiplicity scaling of He-fragments is reported. The pseudo-rapidities for the shower particles accompanying the emission of the different multiplicities of the projectile He-fragments are also investigated. Each of these distributions is found to be satisfactorily fitted by a single Gaussian distribution. The temperature of the system emitting the shower particles T is also calculated and found to be independent of both the projectile and the multiplicities of the He-fragment.
LOW-MASS SCALAR MESONS IN NUCLEAR PHYSICS: MULTILOOP EFFECTS IN THE BOSONIZATION OF THE NAMBU-JONA-LASINIO MODEL
Authors: CELENZA L.S. , SHAKIN C.M. , SZWEDA J.
Published: November 2004

We review a momentum-space bosonization of the Nambu-Jona-Lasinio model performed at the one-loop level by Bernard, Osipov and Meissner. At that level of approximation, the theory predicts a low-mass sigma meson where [Formula: see text] with mq being the constituent quark mass. Such a meson is not seen in experiment. We therefore extend the bosonization procedure to include a multiple-loop diagram describ-ing the coupling of the sigma to the two-pion channel. We find that for spacelike values of the momentum p2 (p2 ≤ 0), the sigma propagator behaves as if there were a pole at a small value of the mass, m eff ≃460 MeV. However, we see that the channel coupling is very large for timelikep2. That limits the applicability of a perturbative bosonization scheme in the timelike regime where a theory with explicit multichannel unitarity is to be preferred. We extend our analysis to include unitarity corrections to the self-energy in the isoscalar-scalar channel. Quite satisfactory results are obtained in that case. Again for spacelikep2, the dynamics is governed by a small value of m eff (m eff ≃500 MeV ); however, the theory no longer predicts a physical low-mass a meson. This analysis clarifies the nature of the low-mass sigma meson used in relativistic nuclear physics and in the one-boson exchange model of the nucleon-nucleon force. It is also seen that the low-mass (effective) sigma is predominantly of [Formula: see text] character with some admixture of [Formula: see text] (correlated two-pion components).
STRUCTURE OF LIGHT NUCLEI IN RELATIVISTIC MEAN FIELD THEORY
Authors: PATRA S.K.
Published: November 2004

Bulk properties such as the binding energies and rms radii are calculated for some light (Z=1−8) nuclei using deformed relativistic mean-field model. Severe discrepancy between the calculated and experimental results are pointed out for the very light nuclei. We discuss possible causes of discrepancy for very light nuclei.
MULTIQUARK ENERGIES IN SU(2) LATTICE GAUGE THEORY
Authors: GREEN A.M. , MICHAEL C. , PATON J.E. , SAINIO M.E.
Published: November 2004

Energies of four-quark systems have been extracted in a quenched SU(2) lattice Monte Carlo calculation for two different geometries, rectangular and colinear, with β=2.4 and lattice size 163×32. Also by going to a lattice 243×32 and to β=2.5, the effect of the finite lattice size and scaling are checked. An attempt is made to understand these results in terms of a model based on interquark two-body potentials but modified very significantly by a phenomenological gluon-field overlap factor.
A SYMMETRIZED ANSATZ FOR THE DIBARYON SKYRMION
Authors: LEVY-NATHANSOHN R. , EISENBERG J.M.
Published: November 2004

We investigate a symmetrized ansatz for the dibaryon system in the Skyrme model. The ansatz obeys the same reflection symmetry that is observed in the complete, static numerical solution for the B=2 sector. The baryon-baryon potential between two skyrmions is calculated as a function of the separation distance. As a check on our numerics and on the general validity of the procedure, we verify that the baryon number is equal to two and is independent of the separation distance. This symmetrized ansatz does not yield attraction in the baryon-baryon interaction.
SCALAR-ISOSCALAR CORRELATOR IN A PHENOMENOLOGICAL COUPLED-CHANNEL QUARK MODEL
Authors: CELENZA L.S. , SHAKIN C.M. , SUN WEI-DONG , SZWEDA J. , ZHU XIQUAN
Published: November 2004

We calculate the Fourier transform of the scalar-isoscalar correlator[Formula: see text] making use of a generalized coupled-channel Nambu-Jona-Lasinio (NJL) model. The calculation is based upon the assumption that the correlator may be calculated by inserting two-pion continuum states between the operators [Formula: see text] and [Formula: see text]. We introduce a model for confinement such that the various quark-loop integrals only have cuts due to the physical two-pion continuum thus allowing us to construct dispersion relations for the correlator. It is then shown that for spacelike P2(P2<0) and for small timelike P2, a sigma-dominance model provides an excellent representation of the correlator that was calculated here using a dispersion relation. The parameters of the sigma-dominance model are consistent with those that characterize the low-mass (500–600 MeV) sigma meson that is extensively used in studies of the relativistic nuclear many-body problem. We also contrast the dynamics in the scalar-isoscalar channel with that in the vector-isovector channel where a physical particle (the rho meson) is to be found in the timelike region P2>0.
SEMICLASSICAL DESCRIPTION OF SPIN EXCITATIONS OF THE PARTICLE-CORE INTERACTION SYSTEM
Authors: RADUTA A.A. , SANDULESCU N. , SUHONEN J.
Published: November 2004

A model Hamiltonian describing a nucleon moving in a shifted oscillator well and inter-acting with a harmonic core through a quadrupole-quadrupole term is semiclassically treated. The solutions of the linearised equations of motion are quantised by the Bohr-Sommerfeld procedure. Among the four RPA modes, there is one which corresponds to the harmonic vibration of the spin degree of freedom. This mode is analogous to the spin wave mode describing a system of interacting spins placed in a magnetic field. The state describes a harmonic wobbling motion around a stationary state belonging to the ground rotational band.
FLUID-DYNAMICAL APPROACH TO THE DAMPING OF NUCLEAR TRANSVERSE EXCITATIONS
Authors: BASTRUKOV S.I. , MOLODTSOVA I.V. , SHILOV V.M.
Published: November 2004

Within the dissipative nuclear fluid-dynamics, the predictions are presented for the widths of Mλ, T=0 twist and E1, T=0 torus resonances associated with the longwavelength transverse vibrations of a nucleon flow. The macroscopic damping mechanism is presumed to be originated from the individual nucleon collisions with each other resulting in the shear viscosity. The collisional width of magnetic twist resonance as a function of mass number and multipole degree is found to be γ(Mλ)≈6(2λ+3)(λ−1) A−2/3 MeV. The width of the dipole torus mode is given by Γ tor (E1, T=0)≈130 A −2/3 MeV .
SOME PRELIMINARY RESULTS FROM THE NEW 10.6 GeV/NUCLEON GOLD BEAM AT BROOKHAVEN
Authors: WADDINGTON C. JAKE
Published: November 2004

Preliminary results are described from three separate experiments observing the interactions of gold nuclei accelerated to 10.6 GeV/nucleon at the Brookhaven AGS. Nuclear emulsion results present a global picture of the various interaction modes and reveal the production of mesons, copious multifragmentation and the angular distributions of the emitted particles. Electronic detectors make a more precise measurement of the heavy fragments emitted from interactions in a wide range of well defined targets. Etchable glass detectors provide unique charge resolution of these heavy fragments but give results that are discordant with those from the other detectors. Very significant differences are seen between these interactions and those observed at energies of ≤1.0 GeV/nucleon. Fission appears to be almost entirely suppressed while charge pickup is reduced by a factor of two to three. Total charge changing cross-sections are increased but partial cross sections for small charge changes are reduced. Frequent examples of multifragmentation are observed and central collisions result in copious particle production with total multiplicities as great as 370 singly charged particles being emitted from a single interaction. Other interactions show the emission of as many as 15 alpha particles or 7 heavier fragments. The implications of these results on the problem of the propagation of cosmic ray nuclei through the interstellar medium are considered.
SHELL DEFORMATION AND SPIN EFFECTS IN NUCLEON SEPARATION ENERGIES
Authors: RAJ D. CALEB CHANTHI , RAJASEKARAN M. , PREMANAND R.
Published: November 2004

A new formula to obtain shell correction to separation energy is derived from a Strutinsky type calculation. A systematic analysis of shell and deformation effects on nucleon separation energy is made. Spin induced structural changes are also evident in shape changes along the spin coordinate. Calculations are performed for a wide range of nuclei from Zr to Cm. The results are generally in very good agreement with experimental analysis.
PROBABILITY AND TIME OF PHOTOFISSION IN THE QUASI-DEUTERON ENERGY REGION
Authors: KANIADAKIS G. , LUCIA U. , QUARATI P.
Published: November 2004

Using results of a previous phenomenological and numerical analysis of the photofission of Bi, Th and U in the QD energy region, we study the photofission probability as the solution of a differential equation of Clausius-Clapeyron type and derive an expression for the time of photofission. We argue about some aspects of the photofission dynamics from a thermodynamical point of view and suggest the introduction of some nuclear thermodynamical quantities. The photofission time statistically formulated on the base of the mean free path of the pn pair inside the fissioning nucleus is also examined.
BOSON AND ROTOR EXPANSIONS OF LIE ALGEBRAS IN VECTOR COHERENT STATE THEORY
Authors: ROWE D.J.
Published: November 2004

A brief overview is given of some of the ways VCS theory can be used to generate boson and rotor expansions of Lie groups. It is demonstrated by examples that such representations are a powerful aid in computing the explicit matrices of the irreducible representations needed in the application of Lie groups and Lie algebras in physics. It is shown that VCS theory is a theory of induced representations and that it has some advantages over other inducing constructions. Boson and rotor expansions are applied to the microscopic theory of nuclear rotations and it is shown that, in addition to providing algorithms for the calculation of the representation matrices needed, these expansions also provide new perspectives on the theory which enable it to be extended to include intrinsic nucleon spin degrees of freedom and the adiabatic mixing of representations.
MAXIMAL-DECOUPLING VARIATIONAL PRINCIPLE AND OPTIMAL AUXILIARY HAMILTONIANS FOR NUCLEAR COLLECTIVE MOTIONS
Authors: Li Ching-teh
Published: November 2004

A variational principle of maximal decoupling between the collective and noncollective subspaces has recently been proposed to pin down the collective degrees of freedom of the nuclear many-body problem. This maximal-decoupling variational principle is further utilized here to determine in an optimal way the auxiliary Hamiltonians to be used in severely truncated boson-space calculations for nuclear collective motions. In the present method one treats the spurious-state problem in truncated boson-space calculations by using appropriate auxiliary boson Hamiltonians. The viability of the method is demonstrated through its application to a simplified shell model containing only the monopole pairing interactions.
A LOGICAL DESCRIPTION OF THE EVOLUTION OF FEEDBACK LOOP SYSTEMS AND ITS APPLICATION TO RHABDOVIRUS INFECTION
Authors: MARTINET-EDELIST CLAIRE
Published: November 2004

The molecular biology of viruses can be effectively described by kinetic logic, even in its so-called “naïve” version, since feedback loops are implicated in all viral cycles and viral proteins generally display several functions. A general method for the evolution of systems involving feedback loops using this modelling is presented. It can be summarized as follows:

(i) description of the system through boolean equations,

(ii) identification of the steady states (is there a good agreement between the observations and the logical description?),

(iii) experimental determination of several parameters,

(iv) computer simulation of viral cycles,

(v) predictions and their relation to the biological facts.

This survey of oscillation between experimentation and logical description was applied to the study of rhabdovirus cycles and allowed us to describe some aspects of their gene expression.
ON ELEMENTARY FLUX MODES IN BIOCHEMICAL REACTION SYSTEMS AT STEADY STATE
Authors: SCHUSTER STEFAN , HILGETAG CLAUS
Published: November 2004

A mathematical definition of the concept of elementary mode is given so as to apply to biochemical reaction systems subsisting at steady state. This definition relates to existing concepts of null-space vectors and includes a condition of simplicity. It is shown that for systems in which all fluxes have fixed signs, all elementary modes are given by the generating vectors of a convex cone and can, thus, be computed by an existing algorithm. The present analysis allows for the more general case that some reactions can proceed in either direction. Basic ideas on how to compute the complete set of elementary modes in this situation are outlined and verified by way of several examples, with one of them representing glycolysis and gluconeogenesis. These examples show that the elementary modes can be interpreted in terms of the particular biochemical functions of the network. The relationships to (futile) substrate cycles are elucidated.
A NEURO-ETHOLOGICAL APPROACH FOR THE TSP: CHANGING METAPHORS IN CONNECTIONIST MODELS
Authors: MIGLINO O. , MENCZER F. , BOVET P.
Published: November 2004

Biological systems often offer solutions to difficult problems which are not only original but also efficient. Connectionist models have been inspired by neural systems and successfully applied to the formulation of algorithms for solving complex problems such as the travelling salesman problem. In this paper we extend the connectionist metaphor to include an ethological account of how problems similar to the travelling salesman problem are solved by real living systems. A model is presented in which a population of neural networks with simple sensory-motor systems evolve genetically in simulated environments which represent the problem instances to be solved. Preliminary results are discussed, showing how the ethological metaphor allows to overcome some shortcomings of other connectionist models, such as their time and space complexity.
WATER QUALITY MODELLING WITHIN THE RAISON EXPERT SYSTEM
Authors: BOOTY W.G. , WONG I.W.S.
Published: November 2004

The RAISON (Regional Analysis by Intelligent Systems ON a microcomputer) system is a multimedia environmental data analysis tool-kit that contains a fully integrated database management system, spreadsheet, G.I.S., graphics, statistics, modelling and expert system modules as well as a programming language that allows the user to create specialized applications. This paper presents case studies of modelling applications which illustrate the utility of the system in assisting the users of water quality models to make the models more user friendly. This is accomplished through the use of added visualization of inputs and auxiliary information as well as on-line knowledge added. This system also enables the user to represent model results in numerous graphical forms as well as animated results presented on maps. In addition, it has the ability to interface models with expert systems to aid in the selection and use of models and in the interpretation of results.
THE CASE FOR RESEARCH ON THE EFFECTS OF ZEBRA MUSSELS IN LAKE ERIE: VISUALIZATION OF INFORMATION FROM AUGUST AND SEPTEMBER 1993
Authors: CHARLTON MURRAY N.
Published: November 2004

Recent concern about the effects of Zebra mussels has centred on potential loss of fish production and potential loss of fish edibility. The mussels are thought to cause these effects by diversion of energy flow and alteration of contaminant processing. Because management options are limited to controls on nutrients and fish harvest/stocking, it is important to determine the extent and degree of Zebra Mussel effects. Some effects of the mussels are obvious in sheltered shallow areas but the effects on the whole ecosystem are not known.

A series of research surveys done in 1993 is reported in this paper. The effects of the mussels seem to result in a loss of about 25 % of the standing algal biomass in some areas. Although an attempt was made to visit many areas of the lake, more extensive work is needed to find whole ecosystem effects. The difficulty in delineating the effects of the mussels is caused by the coincidental achievement of nutrient loading goals. Because the distribution of zebra mussels is uneven their effects may be found through extensive spatial surveys.