bluuebunny/crossref_metadata_2025 huggingface dataset:
TRANSITION FROM QUASIPERIODICITY TO CHAOS AND DEVIL'S STAIRCASE STRUCTURES OF THE DRIVEN CHUA'S CIRCUIT
Authors: MURALI K. , LAKSHMANAN M.
Published: November 2004

In this paper, we report on the influence of an external periodic signal on the familiar double-scroll chaotic attractor of Chua's autonomous circuit. As the external forcing parameters are varied, quasiperiodicity, devil's staircase structures, re-emerging double-scroll and double-hook type attractors have been observed. In addition, period-adding and crisis phenomena have also been observed for this circuit.
ON SPECIFICATION OF REUSABLE SOFTWARE COMPONENTS
Authors: SITARAMAN MURALI , WELCH LONNIE R. , HARMS DOUGLAS E.
Published: November 2004

For widespread reuse in a component-based software industry, a component must be designed and developed to be reused. Benefits of reuse are maximized when a component is reused “as is” (possibly with provisions for expected customization, such as through parameters), based only on its specification. The expression of the specification of a component is crucial in this setting. The specification must be formal, yet understandable, as well as abstract and implementation-independent. The specification also must make it possible to demonstrate correctness of an implementation of the specification and permit formal reasoning about its behavior in a client program. This paper explains how it is possible to write specifications with these properties in RESOLVE, a conceptual framework that we have developed for constructing reusable software components.
THE FRAME PROBLEM FROM AN ENGINEERING PERSPECTIVE
Authors: LENTING JACQUES H.J. , BRASPENNING PETER J.
Published: November 2004

Since its introduction in 1969, the phrase “frame problem” has been attributed various interpretations. Most researchers in the field of Artificial Intelligence define the frame problem as the problem of finding an effective representation for reasoning about change. Logicians use the phrase to refer to a much less general technical problem within logic whereas philosophers tend to interpret the phrase as the more general problem of determining (ir)relevance. All in all, this discrepancy has led to considerable confusion about the meaning of the phrase. We contend that most of this confusion can be avoided, if the original (robotics) context of the frame problem is adhered to. We present an engineering view on the frame problem that allows us to strip the frame problem from associated problem notions like qualification and ramification. The problem that remains is intimately related to the knowledge acquisition bottleneck in knowledge engineering.
AN ABSTRACT, SHARED AND PERSISTENT DATA STRUCTURE FOR SUPPORTING DATABASE MANAGEMENT AND MULTILINGUAL NATURAL LANGUAGE PROCESSING
Authors: ZHANG CUI , WALTERS RICHARD F.
Published: November 2004

Neither today’s general purpose programming environment nor high-level programming languages, including those designed for AI purposes, provide adequate support for database systems. Furthermore, non-English language databases are difficult to treat either in existing database systems or with current high-level languages, because they require culture-sensitive operations on multiple foreign character sets. In this paper, we present an abstract, shared and persistent data structure, called HL+, capable of supporting database management applications. We also describe the means for coping with the aforementioned problems by accessing HL+ features of database management from high-level programming languages with an extensible programmable high-level language interface. Extensions to the data structure to accommodate processing of multiple foreign character strings are also described, and examples of multilingual applications are given.
OPTIMUM GUARD COVERS AND m-WATCHMEN ROUTES FOR RESTRICTED POLYGONS
Authors: CARLSSON SVANTE , NILSSON BENGT J. , NTAFOS SIMEON
Published: November 2004

A watchman, in the terminology of art galleries, is a mobile guard. We consider several watchman and guard problems for different classes of polygons. We introduce the notion of vision spans along a path or route which provide a natural connection between the art gallery problem, the m-watchmen routes problem and the watchman route problem.

We prove that finding the minimum number of vision points, i.e., static guards, along a shortest watchman route is NP-hard. We provide a linear time algorithm to compute the best set of static guards in a histogram polygon. The m-watchmen routes problem, minimize total length of routes for m watchmen, is NP-hard for simple polygons. We give a Θ(n3+n2m2)-time algorithm to compute the best set of m watchmen in a histogram.
Computational Geometry Column 19
Authors: O’ROURKE JOSEPH
Published: November 2004

The computational geometry community bibliography is described.
REGULAR ENUMERATION OF GRID POINTS IN A CONVEX POLYGON
Authors: LEE HSUAN-SHIH , CHANG RUEI CHUAN
Published: November 2004

In this paper we present an efficient algorithm for enumerating all the grid points in a convex polygon, where the enumeration is done by scanning the grid points with a set of parallel grid lines. Given a convex n-gon, enumeration can be done in [Formula: see text] time, where K is the number of the grid points reported, l is the diameter of the polygon and w is the length of the shorter sides of the rectangle enclosing the polygon with longer sides parallel to the line segment connecting the diametral pair of the polygon. We also show that the ratio of the number of the scanned grid lines to the minimal is less than some constant.
INFERENCE OF REVERSIBLE LANGUAGES
Authors: BONOPERA ALAIN , GAUJAL BRUNO
Published: November 2004

We consider inductive inference of certain classes of languages, namely the k-reversible languages for some fixed k≥0, from positive, possibly infinite samples. More precisely, given any rational language S, the sample, we prove that there exists a smallest, with respect to inclusion, k-reversible language containing it, which is then also rational. After an algebraic proof, we describe a polynomial algorithm performing the inference.
QUASI-ISOMETRIES AND BICOMBINGS
Authors: HUYNH H.-L. , POON W.Y.
Published: November 2004

It is not known if bicombability of a group is invariant under quasi-isometry, although Hamish Short has shown that combability is. We give an alternative definition of a bicombable group (equivalent to Short’s), and show that bicombability is invariant under a certain kind of quasi-isometry. We apply our result to answer questions about certain extensions of bicombable groups.
ON E-UNITARY COVERS OF ORTHODOX SEMIGROUPS
Authors: SZENDREI MÁRIA B.
Published: November 2004

In this paper we prove that each orthodox semigroup S has an E-unitary cover embeddable into a semidirect product of a band B by a group where B belongs to the band variety generated by the band of idempotents in S. This result is related to an embeddability question on E-unitary regular semigroups raised previously.
AN ORDER-THEORETIC PROPERTY OF THE COMMUTATOR
Authors: KEARNES KEITH A.
Published: November 2004

We describe a new order-theoretic property of the commutator for finite algebras. As a corollary we show that any right nilpotent congruence on a finite algebra is left nilpotent. The result is false for infinite algebras and the converse is false even for finite algebras. We show further that any solvable E-minimal algebra is left nilpotent, any finite algebra whose congruence lattice contains a 0, 1-sublattice isomorphic to M3 is left nilpotent and any homomorphic image of a finite abelian algebra is left and right nilpotent.
DEGENERATE AND RESONANT FOUR-WAVE MIXING IN PLASMAS
Authors: JOSHI C. , KITAGAWA Y. , LAL A.
Published: November 2004

The status of degenerate and resonant four-wave mixing in plasmas is reviewed. For the degenerate case in a collisional plasma, the theory predicts and experiments demonstrate that the thermal-force contribution to the signal reflectivity dominates over the ponderomotive-force contribution. In the resonant case, the reflectivity can be enhanced over the degenerate level. Experiments show that collisions can lead to a narrow spectral width of the ion-acoustic resonance, but the effects of convection and laser heating can limit the enhancement of the reflectivity below the expected value.
IMPROVED THEORY OF NONLINEAR DIRECTIONAL COUPLER
Authors: DECK R.T. , MAPALAGAMA C.
Published: November 2004

We present an improved coupled mode theory of the nonlinear directional coupler based on the supermodes of the coupler and show that the predicted value of the switching intensity agrees well with recent experimental data. The theory relates to couplers constructed from semi-conductor materials and makes use of the plasma theory to express the dependence of the dielectric function on the field intensity. The analysis accounts for both the time dependence of the incident laser pulse and the spacial variation of the laser field in the direction transverse to the propagation direction.
THERMAL RELAXATION TIMES OF BISTABLE THIN FILM ELEMENTS
Authors: GLAW V. , JANIAK K. , KUMMROW A. , PENSCHKE V. , EICHLER H.J.
Published: November 2004

The heat flow in evaporated thin film interference filters with CdS spacer and an optional CdSe absorption layer is investigated, analyzing the dynamics of optical bistability. The influence of the spot radius r of the exciting laser beam on the switching parameters is studied experimentally and theoretically. The response to pulsed excitation of the bistable devices can be described with a relaxation time τ~r and an effective nonlinearity χ~r−2 which is inversely proportional to the heat capacity of the bistable element.
HIGH-ORDER DIFFRACTION IN PHOTOREFRACTIVE SBN:Ce DUE TO NON-SINUSOIDAL GRATINGS FORMED BY BEAMS OF COMPARABLE INTENSITY
Authors: ZHANG HONG-JUN , TANG ZE-SUN , MOORE THOMAS R. , BOYD ROBERT W.
Published: November 2004

We have observed multiple-order diffraction from photorefractive gratings formed by two input beams of comparable intensity that interfere in a single crystal of SBN:Ce. High-order diffraction occurs both in the direction of two-beam coupling gain and in the opposite direction. These results are in good agreement with the predictions of a theoretical model that interprets high-order diffraction as a form of Raman-Nath scattering from a highly anharmonic diffraction grating that is formed by a light intensity distribution having a large depth of modulation.
TRENDS IN OPTICAL SWITCHES, LIMITERS AND DISCRIMINATORS
Authors: HERMANN J.A. , STAROMLYNSKA J.
Published: November 2004

We review many of the optical devices exploiting nonlinear optical and electro-optic effects which fall within the general categories of switches, limiters and discriminators.
OPTICAL LIMITING IN InSb AT ROOM TEMPERATURE, FOR THE PULSED CO2 LASER
Authors: SMITH A.E. , MCDUFF R.G. , HECKENBERG N.R.
Published: November 2004

The potential of InSb as a material for limiters for CO 2 laser pulses is explored. A model of the nonlinearity is presented and material parameters estimated from Z-Scans and ring-scans. This is then used to model the performance of a basic thin-sample defocussing limiter and find optimum conditions. A simple practical device for removing the gain switched peak from a TEA laser pulse is also described.
ISOTROPIC LIQUID CRYSTALLINE FILM AND FIBER STRUCTURES FOR OPTICAL LIMITING APPLICATION
Authors: KHOO I.C. , LEE S. , LOPRESTI P. , LINDQUIST R.G. , LI H.
Published: November 2004

The principal optical nonlinearities of isotropic liquid crystals are reviewed, and their potentials for all-optical limiting and switching applications are assessed. Our dynamic grating studies of a class of isotropic liquid crystals show that, in the nanosecond and longer time scales, the principal mechanisms for nonlinearities are laser induced ordering (molecular orientations), thermal and density fluctuations. We report optical limiting results obtained with bulk thin film and optical fiber fabricated from these isotropic crystals.
RESOURCE-ORIENTED PARALLEL PLANNING
Authors: LEE SUKHAN , CHUNG KYUSIK
Published: November 2004

This paper presents a new paradigm for constructing a partially ordered plan network, referred to as "resource-oriented parallel planning (RP2)". In resource-oriented parallel planning, goal states are grouped into a collection of goal state subsets, each of which consists of those goal states associated with a particular resource. A subplan is generated for each goal state subset by planning the flow of the corresponding resource, and thus satisfying the constraints specified by each of the goal state subsets. A complete plan is then constructed by synthesizing individual subplans based on the synchronization among subplans.

A distinctive feature of RP2 is that each subplanner generates a conflict-free subplan by controlling the flow of a particular resource while synthesizing a complete plan in cooperation with other subplanners. This can be compared with the conventional state-oriented parallel planning, where each subplanner generates a subplan achieving a goal state while resolving conflicts among subplans in cooperation with other subplanners.

RP2 makes use of resource reasoning in distinguishing important and unimportant resources associated with a goal. This allows each subplanner to hierarchically construct a resource-flow plan and to dynamically coordinate among subplanners in achieving a goal associated with more than one resource.

The proposed scheme not only makes it possible to generate an optimal plan in terms of the maximum parallelism or the minimum depth of a plan network, but also makes it easier to implement the concurrent generation of parallel plans in a parallel and distributed processing environment.
TRANSFORMING RECURSIVE PROCESSES INTO EFFICIENT ALGORITHMS: CALL-GRAPH CACHING FOR ARTIFICIAL INTELLIGENCE
Authors: PERLIN MARK W.
Published: November 2004

There are a large number of highly complex, apparently disparate, Artificial Intelligence (AI) algorithms for planning and learning. These entail the (often tedious) construction of specialized data and control structures. In this article, we present Call-Graph Caching (CGC) as an organizing principle for many of these methods. CGC is the preservation of the trace of a computational process for subsequent reuse; CGC allows the operation of highly efficient, but unintuitive, AI algorithms to be recast as far simpler recursive processes. Thus, we shall describe simple recursive constructions that, together with CGC, provide new motivations and derivations of certain classical AI planning and learning algorithms.
DETERMINATION OF NEURAL NETWORK PARAMETERS BY INFORMATION THEORY
Authors: BRAUSE RÜDIGER W.
Published: November 2004

It is well known that artificial neural nets can be used as approximators of any continous functions to any desired degree and therefore be used e.g. in high-speed, real-time process control. Nevertheless, for a given application and a given network architecture the non-trivial task rests to determine the necessary number of neurons and the necessary accuracy (number of bits) per weight for a satisfactory operation.

In this paper the accuracy of the weights and the number of neurons are seen as general system parameters which determine the maximal output information (i.e. the approximation error) by the absolute amount (network description complexity) and the relative distribution of information contained in the network. A new principle of optimal information distribution is proposed and the conditions for the optimal system parameters are derived.

For two examples, a simple linear approximation of a non-linear, quadratic function and a non-linear approximation of the inverse kinematic transformation used in robot manipulator control, the principle of optimal information distribution gives the the optimal system parameters, i.e. the number of neurons and the different resolutions of the variables.
SPIN: THE SEQUENTIAL PIPELINED NEUROEMULATOR
Authors: VASSILIADIS STAMATIS , PECHANEK GERALD G. , DELGADO-FRIAS JOSÉ G.
Published: November 2004

This paper proposes a novel digital neural network architecture referred to as the Sequential PIpelined Neuroemulator or Neurocomputer (SPIN). The SPIN processor emulates neural networks producing high performance with minimum hardware by sequentially processing each neuron in the modeled completely connected network with a pipelined physical neuron structure. In addition to describing SPIN, performance equations are estimated for the ring systolic, the recurrent systolic array, and the neuromimetic neurocomputer architectures, three previously reported schemes for the emulation of neural networks, and a comparison with the SPIN architecture is reported.
ASSESSMENT OF THE RELIABILITY OF AI PROGRAMS
Authors: BASTANI FAROKH , CHEN ING-RAY
Published: November 2004

Reliability assessments of AI programs must consider not only possible program bugs which. remain in the program due to insufficient testing and debugging, but also faults due to intrinsic characteristics of AI programs that cannot be removed even after the program is fully debugged. This paper develops an analytical tool for assessing the reliability of AI programs. Possible intrinsic faults of AI programs are identified, and modifications to existing software reliability models for conventional programs are suggested. An example illustrating the effect of intrinsic faults of AI heuristics on the program reliability in a real-time situation is given. It is shown that under certain conditions the cost-based A* planning algorithm is less reliable than the node-based A* planning algorithm.
RETRIEVING AND INTEGRATING DATA FROM MULTIPLE INFORMATION SOURCES
Authors: ARENS YIGAL , CHEE CHIN Y. , HSU CHUN-NAN , KNOBLOCK CRAIG A.
Published: November 2004

With the current explosion of data, retrieving and integrating information from various sources is a critical problem. Work in multidatabase systems has begun to address this problem, but it has primarily focused on methods for communicating between databases and requires significant effort for each new database added to the system. This paper describes a more general approach that exploits a semantic model of a problem domain to integrate the information from various information sources. The information sources handled include both databases and knowledge bases, and other information sources (e.g. programs) could potentially be incorporated into the system. This paper describes how both the domain and the information sources are modeled, shows how a query at the domain level is mapped into a set of queries to individual information sources, and presents algorithms for automatically improving the efficiency of queries using knowledge about both the domain and the information sources. This work is implemented in a system called SIMS and has been tested in a transportation planning domain using nine Oracle databases and a Loom knowledge base.
DATABASE SUPPORTED COOPERATIVE PROBLEM SOLVING
Authors: CHAKRAVARTHY SHARMA , KARLAPALEM KAMALAKAR , NAVATHE SHAMKANT B. , TANAKA ASTERIO
Published: November 2004

Cooperative problem solving can be viewed as a complex activity requiring harmonious and dynamic interaction between active agents and passive agents. This problem is currently being addressed by the research community at various levels of abstraction. Broadly, this paper analyzes the problem of cooperative problem solving from a database perspective and argues that recent advances in database technology facilitate development of a viable solution to the above problem. Specifically, in this paper, we first analyze the problem of cooperative problem solving to identify its underlying key characteristics. Based upon our analysis, we partition the problem space into classes along a spectrum and indicate the level of cooperation required. We propose near-term as well as long-term solutions for cooperative problem solving that progressively enhances the functionality of database systems by synthesizing appropriate abstractions and techniques. Furthermore, we identify problems, such as agent capability modeling that require further research to address the most general form of cooperative problem solving.
SPECIFICATION AND IMPLEMENTATION OF A BELIEF-DESIRE-JOINT-INTENTION ARCHITECTURE FOR COLLABORATIVE PROBLEM SOLVING
Authors: JENNINGS NICK R.
Published: November 2004

Systems composed of multiple interacting problem solvers are becoming increasingly pervasive and have been championed in some quarters as the basis of the next generation of intelligent information systems. If this technology is to fulfill its true potential then it is important that the systems which are developed have a sound theoretical grounding. One aspect of this foundation, namely the model of collaborative problem solving, is examined in this paper. A synergistic review of existing models of cooperation is presented, their weaknesses are highlighted and a new model (called joint responsibility) is introduced. Joint responsibility is then used to specify a novel high-level agent architecture for cooperative problem solving in which the mentalistic notions of belief, desire, intention and joint intention play a central role in guiding an individual’s and the group’s problem solving behaviour. An implementation of this high-level architecture is then discussed and its utility is illustrated for the real-world domain of electricity transportation management.
AN EFFICIENT MANAGEMENT OF READ-ONLY DATA IN A DISTRIBUTED INFORMATION SYSTEM
Authors: FLATER DAVID W. , YESHA YELENA
Published: November 2004

When dealing with massive amounts of primarily read-only data, significant improvements can be made over distributed DBMS for making these data available to a large network. This paper outlines some methods for heuristic query routing and cooperative caching which manage read-only replicas of data in a fully distributed manner on a network of arbitrary topology. These methods insure that query throughout increases steadily as nodes are added to the network while maintaining good response time. The resulting system is capable of providing automatic resource discovery and information retrieval over a wide area network without relying on resource directories.
THE TURNED TORUS KNOT IN S4
Authors: BOYLE JEFFREY
Published: November 2004

A spun knotted torus in the 4-sphere is formed by rigidly sweeping a knotted curve along a circle. Alternately, as the knotted curve is swept along the circle we could give it a number of full turns (Dehn twists). We show the resulting knotted torus depends only on the knotted curve and whether the number of turns is even or odd. The even and odd turned spun tori have nondiffeomorphic complements. This is generalized in some cases to include twist spun turned torus knots.
THE PLANARITY PROBLEM FOR SIGNED GAUSS WORDS
Authors: CAIRNS GRANT , ELTON DANIEL M.
Published: November 2004

C.F. Gauss gave a necessary condition for a word to be the intersection word of a closed normal planar curve and he gave an example which showed that his condition was not sufficient. M. Dehn provided a solution to the planarity problem [3] and subsequently, different solutions have been given by a number of authors (see [9]). However, all of these solutions are algorithmic in nature. As B. Grünbaum remarked in [7], “they are of the same aesthetically unpleasing character as MacLane’s [1937] criterion for planarity of graphs. A characterization of Gauss codes in the spirit of the Kuratowski criterion for planarity of graphs is still missing”. In this paper we use the work of J. Scott Carter [2] to give a necessary and sufficient condition for planarity of signed Gauss words which is analogous to Gauss’s original condition.
CONSTRUCTING LINKS BY PLUMBING FLAT ANNULI
Authors: HAYASHI CHUICHIRO , WADA MASAAKI
Published: November 2004

We show that every oriented link is the boundary of a surface obtained from an embedded disk by plumbing a flat annulus a finite number of times.
SOLAR NEUTRINOS
Authors: BETHE H.A.
Published: November 2004

Solar neutrinos have been measured by a radioactive scheme involving 37 Cl , and by electron collisions at Kamiokande II. The former experiment gave 1/4, the latter 1/2 of the intensity expected from the standard solar model. Kamiokande showed that the central temperature from the standard model is at least approximately correct. Both experiments can be explained by the Mikheyev-Smirnov-Wolfenstein (MSW) theory, and they show the mass of the μ neutrino to be of order 10−3 eV . Preliminary results from an experiment using 71 Ga confirm the conclusions.
NEUTRINO OSCILLATIONS IN AN EXPANDING UNIVERSE
Authors: D’OLIVO JUAN CARLOS , NÚÑEZ DARÍO , TORRES MANUEL
Published: November 2004

The properties of neutrino oscillations in an expanding Universe are considered. The results are derived using the adiabatic solutions of the covariant Dirac equation for the expansion laws corresponding to the radiation and to the matter dominated Universe. The exact expression for the oscillation period is obtained and possible implications on nucleosynthesis are discussed. The relations between the leptonic charges arising from neutrino oscillations are presented.
GEOMETRIZED INSTANTONS AND THE CREATION OF THE UNIVERSE
Authors: NOVELLO M. , OLIVEIRA L.A.R. , SALIM J.M. , ELBAZ E.
Published: November 2004

A nonsingular cosmological scenario is presented in which the currently observed Riemannian configuration of spacetime originates from a primordial Weylian “stiff matter” phase driven by a geometrized inflaton-like field. In the particular case of a Friedman-Robertson-Walker line element, it is shown that an unstable original Minkowski vacuum starts to collapse adiabatically at a remote past and bounces when a minimum radius is attained. Throughout the collapsing stage, this matter-free Universe is accelerated (or “inflationary”). As in models of spontaneous quantum creation, the bouncing phase can be shown to correspond to the propagation of a Weyl instanton in an Euclideanized, classically forbidden region. In the course of the bouncing period, concurrent to the maximal deviation of the Riemannian configuration, a geometry-driven amplification mechanism operates causing the exponential increase of entropy and matter fluctuations. Once the environment temperature is always bounded, this nonadiabatical process stands for a “ Big — but finite — Bang” creation event, followed by a standard radiation-dominated era. The model describes an eternal, Friedman-like open Universe, free of many problems that hinder standard cosmology; the observed existence of a baryon excess also fits naturally within the proposed scheme.
DARK MATTER WITH VARIABLE MASSES
Authors: GARCÍA-BELLIDO JUAN
Published: November 2004

String effective theories contain a dilaton scalar field which couples to gravity, matter and radiation. In general, particle masses will have different dilaton couplings. We can always choose a conformal frame in which baryons have constant masses while (nonbaryonic) dark matter have variable masses, in the context of a scalar-tensor gravity theory. We are interested in the phenomenology of this scenario. Dark matter with variable masses could have a measurable effect on the dynamical motion of the halo of spiral galaxies, which may affect cold dark matter models of galaxy formation. As a consequence of variable masses, the energy-momentum tensor is not conserved; there is a dissipative effect, due to the dilaton coupling, associated with a “dark entropy” production. In particular, if axions had variable masses they could be diluted away, thus opening the “axion window.” Assuming that dark matter with variable masses dominates the cosmological evolution during the matter era, it will affect the primordial nucleosynthesis predictions on the abundances of light elements. Furthermore, the dilaton also couples to radiation in the form of a variable gauge coupling. Experimental bounds will constrain the parameters of this model.
MINISUPERSPACE AND WHEELER-DEWITT EQUATION FOR STRING DILATON COSMOLOGY
Authors: CAPOZZIELLO SALVATORE , RITIS RUGGIBRO DE
Published: November 2004

In connection with the string-dilaton cosmology, we construct a bidimensional mini-superspace model in which we write down and integrate the Wheeler-DeWitt equation. The solution and its probabilistic interpretation contains the feature of the scale factor duality.
HIGH ENERGY RADIATION FROM GEMINGA (1E0630+178)
Authors: KWOK PING-WAI
Published: November 2004

Geminga is one of the brightest gamma-ray sources in the sky but its nature was a mystery for almost two decades. In this article we review the discovery of Geminga and the attempts to identify its nature as a radio-quiet pulsar. We will discuss some of the interpretations and implications.
CHIRAL SYMMETRY BREAKING IN A PHENOMENOLOGICAL DESCRIPTION OF THE QCD VACUUM
Authors: SCHRAMM S. , GREINER W.
Published: November 2004

Quark–antiquark condensation in the QCD groundstate is discussed in the framework of BCS theory. Adopting a phenomenological interaction between the quarks, the vacuum wavefunction is determined variationally. Taking these results, the properties of the vacuum and its excitations are determined. In addition the effect of instanton-type induced quark interactions is discussed.
THE PLASMA ANVIL IN INERTIAL CONFINEMENT FUSION
Authors: FECHNER WALTER , MORLEY P. D.
Published: November 2004

We examine theoretically an inertial confinement fusion (ICF) target consisting of a spherical wedge embedded in a relatively nondeformable "anvil". Questions such as heat loss to the anvil, optimum wedge angle, liner and anvil materials, anvil deformations and deleterious 2-D shock effects on D-T burn and compression symmetry are discussed.
COMMENTS ON PHOTONUCLEAR REACTIONS AT INTERMEDIATE ENERGIES
Authors: MENEZES D. P. , DE TOLEDO PIZA A. F. R.
Published: November 2004

Most of the recently published papers on photonuclear reactions at intermediate energies1 either adopt or criticize the theoretical description by Hebach et al.2 We implement here a simple and realistic calculation for the shell model knock-out contribution which considers a Woods-Saxon potential for the bound state and a shallower optical potential for the outgoing nucleon. Final states are explicitly orthogonalized to the initial state and the effects of the orthogonalization requirement are discussed.
SPIN STRUCTURE FUNCTIONS OF THE NUCLEON
Authors: CARLITZ ROBERT D.
Published: November 2004

These lectures discuss the substructure of the nucleon, first on the scale of 1 fermi and then at much shorter distances. We review relevant features of the quark model and introduce Quantum Chromodynamics and the idea of a running coupling. Recent data involving polarized protons is discussed in this framework, and an outlook is presented for future experiments relating to the spin substructure of the nucleon.
CHIRAL PERTURBATION THEORY WITH NUCLEONS
Authors: Meißner Ulf-G.
Published: November 2004

I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external momenta and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward–identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the method. Some processes which are discussed are threshold photopion production, low-energy Compton scattering off nucleons, πN scattering and the σ–term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon.
PREDICTION POWER OF MATHEMATICAL MODELS FOR TUMOR GROWTH
Authors: MARUŠIĆ M. , VUK-PAVLOVIĆ S.
Published: November 2004

We compared the Gompertz model, the generalized Gompertz model, the Piantadosi model, the autostimulation model and the polynomials for the power to predict growth of multicellular tumor spheroids as paradigms of the prevascular phase of tumor growth. For the comparison of models we developed a criterion that established the Gompertz model as the model with the best prediction power. The prediction power of the remaining models was ranked in declining order: the generalized Gompertz model; the mutually indistinguishable Piantadosi model and the autostimulation model; and the polynomials. The ranking of models was not affected by the applied minimization criteria of weighted least squares, unweighted least squares and fitting to logarithmically transformed data, but the prediction power was affected by these criteria. The best predictions were obtained by weighted least squares, closely followed by fitting to logarithmically transformed data. The unweighted least-squares minimization was much less applicable for prediction (and description) of growth.
CONTRIBUTION OF MATHEMATICAL MODELLING TO ELUCIDATION OF AIDS PATHOGENESIS
Authors: HRABA TOMÁŠ , DOLEŽAL JAROSLAV
Published: November 2004

Although HIV is cytopathogenic for CD4+ lymphocytes in vitro, the depletion of these cells in HIV-infected individuals seems to be caused by some other mechanism. It is probably a direct destructive or inhibitory effect of the viral products or an (auto)immune reaction elicited by them, eventually directed at them. Mathematical model of immunological tolerance was used for simulation of CD4+ lymphocyte depletion dynamics in HIV infection under the assumption that it is caused by HIV products. This model was not able to simulate the observed three-stage dynamics of CD4+ cell counts, i.e., drop of these counts around seroconversion, followed by a slow decrease over a prolonged period and an accelerated decrease before the development of AIDS. When an immune reaction limiting HIV reproduction was included in the model, all these three phases of CD4+ lymphocyte depletion could be simulated. In the paper, different modifications and extensions of the model are reviewed, compared with available clinical data, and their relevance for HIV research is discussed.
AN INTRODUCTION TO MODELS OF SUBDIVIDED POPULATIONS
Authors: LEBRETON J.-D. , GONZALEZ-DAVILA G.
Published: November 2004

Models concerning populations living in fragmented habitats are of increasing biological interest. As a consequence, there is a growing interest in metapopulation models and source-sink models. In this paper we introduce elementary discrete-time matrix models for subdivided populations. We discuss the stabilizing role played by migration, in particular in the presence of strong rates of increase and of population structures (e.g., age). Although the emphasis is on demography, we expect applications in evolutionary biology. Another hope is to provide basis to graduate students, with emphasis on the philosophy of model building and use rather than on mathematical difficulties.
FATAL SEXUALLY TRANSMITTED DISEASES (FSTDs), SUCH AS AIDS, SELECT FOR THE EVOLUTION OF MONOGAMY AND PROVIDE A MODEL FOR BACKGROUND EXTINCTION
Authors: GORDON RICHARD , TYSON JOHN E.
Published: November 2004

Monogamous behavior may have a genetic component, in which case it can be subject to natural selection. The mechanism of selection may be the reduced fertility that correlates with STDs. AIDS is a fatal STD (FSTD) capable (without intervention) of severely reducing the human population. We show how, for any mating species, multiple FSTDs (statistical “runs”) occurring within the characteristic time for population recovery, drive that species exponentially towards extinction. Runs of FSTDs occur on geological time scales, providing a general, quantitative model for background extinction rates, and a simpler alternative to the Red Queen hypothesis. It has been difficult to get people to change their risk behavior even when they have full knowledge of how HIV is spread. If we come to understand monogamy (and perhaps polygamy) as heritable traits, then new approaches for slowing the HIV epidemic become apparent.
HELPING BUSINESSES IMPROVE IN PLANNING AND PERFORMANCE THROUGH INTERFIRM COMPARISON— THE EXPERIENCE OF THE SINGAPORE GARMENT INDUSTRY
Authors: Poh Koon Helen Tan , Lee Meng-Hye
Published: November 2004

It is recognised that the overall success of a business depends very much on the quality of management planning, and management needs relevant information in order to plan effectively. However, most management information systems are centered on information obtained in-house. Very little emphasis is placed on external information, except some very general information published by Government bodies. If it is possible to incorporate information from other similar firms into the analysis, a firm will be able to plan and therefore compete more efficiently and improve its overall performance. The application of interfirm comparison studies as an analytical tool to aid management in planning and performance improvement has been well developed and widely accepted in many developed countries. This paper explains the first application of interfirm comparison studies on a wide and comprehensive scale in Singapore, with particular reference to the garment industry business.
THE ENTREPRENEURIAL GRID: SMALL FIRMS, NEW FIRMS & PUBLIC POLICY
Authors: ANG SOON , CARDOZO RICHARD N.
Published: November 2004

Much popular and scholarly work on entrepreneurship does not distinguish clearly small businesses from new businesses. Size and age represent independent dimensions on which a population of businesses may be described. These two dimensions may be used together to form an Entrepreneurial Grid which describes a population of businesses. The combination of age and size into the Grid facilitates analysis of the structure and dynamics of a population of businesses, and of public policies relating to small and new businesses. The Grid constitutes a framework that should prove useful as a guide to research into populations of businesses, to increase understanding of those populations and to improve our ability to formulate appropriate public policies.
DYNAMISM OF SMALL CHINESE BUSINESS ENTERPRISES IN MALAYSIA AND SINGAPORE
Authors: NG BEOY-KUI , NG ENG-JUAN
Published: November 2004

Numerous studies have been done and various explanations have been advanced in the literature on overseas Chinese business success and entrepreneurial capabilities. However, most of the studies are broad-based and focused on the macro-level; there is relatively little account in the literature on the more down-to-earth, micro-level entrepreneurial characteristics and management styles of the small Chinese firms that have contributed to their success.

The purpose of this paper is to record our observations of the more down-to-earth aspects of the entrepreneurial characteristics and management styles of small Chinese businesses in Malaysia and Singapore that have contributed to their success. We also attempt to relate these peculiar characteristics and styles to Sun Zi’s in “Art of War”.
MARKETING EFFECTIVENESS - DOES IT DIFFER BY SIZE AND TYPE OF COMPANIES
Authors: SCHOCH H. P. , GHOSH B. C.
Published: November 2004

Prior studies distinguished marketing effectiveness only by performance of companies. In this study the focus was on size and type of company. The sample comprised Singapore companies consisting of: Small and Medium Sized Enterprises (SMEs), Large Local Companies (LLCs), and Multi-national companies (MNCs). The objective of the study was to ascertain the marketing effectiveness of two groupings of companies, namely:

(1) SMEs and LLCs as the local group of companies, for comparison with MNCs, and (2) SMEs compared to LLCs. It was generally hypothesised that MNCs are more marketing effective than the local group, and that there is no difference in marketing effectiveness between the local groups of companies.

Analysis of the responses suggests that there is no clear cut evidence that MNCs are more marketing effective than the smaller local companies. There are, however a number of marketing areas where MNCs appear to be more effective. As for the local companies, apart from some difference in focus, which are not necessarily indicative of better or worse marketing effectiveness, there appear to be no significant differences in marketing effectiveness between them.

The implication of these findings probably is that size and type of company have no major overall bearing on marketing effectiveness. Perhaps all organisations concur with the view that "the market genesis of every business has become gospel" (Hanan, 1993).
ENTREPRENEURIAL LEARNING: A CONCEPTUAL FRAMEWORK
Authors: YOUNG JOHN E. , SEXTON DONALD L.
Published: November 2004

This paper investigates and offers tentative explanations of the processes which enable practicing entrepreneurs to learn, as they manage their growing businesses. Specifically, it provides a conceptual framework for acquiring an understanding of the learning processes which entrepreneurs use to grow their businesses. The research suggests that entrepreneurs learn processively, and it also identifies their motives for learning. This paper focuses on the learning activities entrepreneurs choose and the cognitive processes which characterize the acquisition, retention, and use of entrepreneurial knowledge. Principles from several studies within the disciplines of the cognitive sciences are used to help explain entrepreneurial learning processes. Problem-solving categories for learning are delineated; effective entrepreneurial learning is defined; and, ways for facilitating the entrepreneur's learning processes are suggested.
THE ENTREPRENEURIAL PERSONALITY OF SMALL BUSINESS OWNER-MANAGERS IN HONG KONG: A CRITICAL INCIDENT ANALYSIS
Authors: CHAN K. F. , LAU THERESA , MAN THOMAS W. Y.
Published: November 2004

This paper reports on the research being carried out in Hong Kong on the entrepreneurial personality of eighteen small business owner-managers in the following sectors: (1) clothing, (2) food processing, (3) catering. A profile of each of the small business companies was drawn up. In addition, unstructured in-depth interviews were carried out with the business owner-managers who were asked to explain the process of business development through the medium of critical incidents and their ways of handling the situations in the incidents. The transcribed and translated interviews have been content analysed. Behavioural attributes contributing to the entrepreneurial personality are thus identified. Throughout the study, a 'grounded theory' approach has been adopted to explore the behavioural pattern displayed by small business owner-managers in Hong Kong so that no specific prescribed pattern from the West is imposed. The paper concludes therefore with the entrepreneurial personality specifically applicable in the Hong Kong. Hence the conclusions derived are significant in that they are specific to the Hong Kong context.
Assessment of Myocardial Viability by Intracellular
23
Na Magnetic Resonance Imaging
Authors: Jansen Maurits A. , Van Emous Jan G. , Nederhoff Marcel G.J. , Van Echteld Cees J.A.
Published: November 2004

Background—

Because of rapid changes in myocardial intracellular Na
+
(Na
+
i
) during ischemia and reperfusion (R),
23
Na magnetic resonance imaging (MRI) appears to be an ideal diagnostic modality for early detection of myocardial ischemia and viability. So far, cardiac
23
Na MRI data are limited and mostly concerned with imaging of total Na
+
. For proper interpretation, imaging of both Na
+
i
and extracellular Na
+
is essential. In this study, we tested whether Na
+
i
imaging can be used to assess viability after low-flow (LF) ischemia.

Methods and Results—

Isolated rat hearts were subjected to LF (1%, 2%, or 3% of control coronary flow) and R. A shift reagent was used to separate Na
+
i
and extracellular Na
+
resonances. Acquisition-weighted
23
Na chemical shift imaging (CSI) was alternated with
23
Na MR spectroscopy. Already during control perfusion, Na
+
i
could be clearly seen on the images. Na
+
i
image intensity increased with increasing severity of ischemia. During R, Na
+
i
image intensity remained highest in 1% LF hearts. Not only did we find very good correlations between Na
+
i
image intensity at end-R and end-diastolic pressure (
R
=0.85,
P
<0.001) and recovery of the rate-pressure product (
R
=−0.88,
P
<0.001) at end-R, but most interestingly, also Na
+
i
image intensity at end-LF was well correlated with end-diastolic pressure (
R
=0.78,
P
<0.01) and with recovery of the rate-pressure product (
R
=−0.81,
P
<0.01) at end-R. Furthermore, Na
+
i
image intensity at end-LF was well correlated with creatine kinase release during R (
R
=0.79,
P
<0.05) as well as with infarct size (
R
=0.77,
P
<0.05).

Conclusions—

These data indicate that
23
Na CSI is a promising tool for the assessment of myocardial viability.
Short-Term Effects of Right-Left Heart Sequential Cardiac Resynchronization in Patients With Heart Failure, Chronic Atrial Fibrillation, and Atrioventricular Nodal Block
Authors: Hay Ilan , Melenovsky Vojtech , Fetics Barry J. , Judge Daniel P. , Kramer Andrew , Spinelli Julio , Reister Craig , Kass David A. , Berger Ronald D.
Published: November 2004

Background—

Single-site ventricular pacing in patients with heart failure, atrial fibrillation, and severe atrioventricular (AV) nodal block risks the generation of discoordinate contraction. Whether altering the site of stimulation can offset this detrimental effect and what role sequential right ventricular–left ventricular (RV-LV) stimulation might play in such patients remain unknown.

Methods and Results—

Nine subjects with heart failure (ejection fraction, 14% to 30%), atrial fibrillation, and AV block were studied by pressure-volume analysis. Ventricular stimulation was applied to the RV (apex and outflow tract), LV free wall, and biventricular (BiV) at 80 and 120 bpm. BiV improved systolic function more than either site alone (dP/dt
max
, 810±83, 924±98, 983±102 mm Hg/s for RV, LV, BiV, respectively;
P
<0.05), although LV pacing was significantly better than RV pacing. However, only BiV improved diastolic function (isovolumic relaxation) over RV or LV alone. Similar results were obtained for both heart rates. RV pacing site did not alter the BiV effect, and concomitant stimulation of both RV sites did not improve function over each alone. Finally, varying RV-LV delay revealed optimal responses with simultaneous pacing.

Conclusions—

Simultaneous BiV pacing acutely enhances both systolic and diastolic function over single-site RV or LV pacing in congestive heart failure patients with atrial fibrillation and advanced AV block. Sequential RV-LV stimulation offers minimal benefit on average and should perhaps be considered only in targeted subsets such as nonresponding patients.