bluuebunny/crossref_metadata_2025 huggingface dataset:
DISCRIMINATIVE LEARNING OF VISUAL DATA FOR AUDIOVISUAL SPEECH RECOGNITION
Authors: ROGOZAN ALEXANDRINA
Published: April 2003

In recent years a number of techniques have been proposed to improve the accuracy and the robustness of automatic speech recognition in noisy environments. Among these, suplementing the acoustic information with visual data, mostly extracted from speaker's lip shapes, has been proved to be successful. We have already demonstrated the effectiveness of integrating visual data at two different levels during speech decoding according to both direct and separate identification strategies (DI+SI). This paper outlines methods for reinforcing the visible speech recognition in the framework of separate identification. First, we define visual-specific units using a self-organizing mapping technique. Second, we complete a stochastic learning of these units with a discriminative neural-network-based technique for speech recognition purposes. Finally, we show on a connected-letter speech recognition task that using these methods improves performances of the DI+SI based system under varying noise-level conditions.
ROBUST SPEECH RECOGNITION USING A NOISE REJECTION APPROACH
Authors: KHAN EMDAD , LEVINSON ROBERT
Published: April 2003

In this paper, we explore some new approaches to improve speech recognition accuracy in a noisy environment. The key approaches taken are: (a) use no additional data (i.e. use only speakers data, no data for noise) for training and (b) no adaptation phase for noise. Instead of making adaptation in the recognition, preprocessing or both stages, we make a noise tolerant (rejection) speech recognition system where the system tries to reject noise automatically because of its inherent structure. We call our approach a noise rejection-based approach. Noise rejection is achieved by using multiple views and dynamic features of the input sequences. Multiple views exploit more information from the available data that is used for training multiple HMMs (Hidden Markov Models). This makes the training process simpler, faster and avoids the need to use a noise database, which is often difficult to obtain. The dynamic features (added to the HMM using vector emission probabilities) add more information about the input speech during training. Since the values of dynamic features of noise are usually much smaller than that of the speech signal, it helps reject the noise during recognition. Multiple views (we also call these scrambles) can be used at different stages in the recognition processes. This paper explore these possibilities. Also, multiple views of the input sequence are applied to multiple HMMs during recognition and the outcome of the multiple HMMs are combined using maximum evidence criterion. The accuracy of the noise rejection-based approach is further improved by using Higher Level Decision Making (HLD) - our method for data fusion. HLD improves accuracy by efficiently resolving conflicts. The key approaches taken for HLD are: meta reasoning, single cycle training (SCT), confidence factors and view minimization. Our tests show very encouraging results.
RECOGNITION OF ARABIC PHONETIC FEATURES USING NEURAL NETWORKS AND KNOWLEDGE-BASED SYSTEM: A COMPARATIVE STUDY
Authors: SELOUANI S. A. , CAELEN J.
Published: April 2003

In this paper, we are concerned with the automatic recognition of Arabic phonetic macro-classes and complex phonemes by multi-layer sub-neural-networks (SNN) and knowledge-based system (SARPH). Our interest goes to the particularities of the Arabic language such as geminate and emphatic consonants and the vowel duration. These particularities are unanimously considered as the main root of failure of Automatic Speech Recognition (ASR) systems dedicated to standard Arabic. The purely automatic method constituted by the SNNs is confronted to an approach based on the user phonetic knowledge expressed by SARPH rules. For the acoustical analysis of speech as well as for the segmentation task, auditory models have been used. The ability of systems has been tested in experiments using stimuli uttered by 6 native Algerian speakers. The results show that SNNs achieved well in pure identification while in the case of semantically relevant duration the knowledge-based system performs better.
NEURO-FUZZY BASED SEARCH ROBOT FOR SOFTWARE COMPONENTS
Authors: KUO YAU-HWANG , HSU JANG-PONG , HORNG MONG-FONG
Published: April 2003

A personalized search robot is developed as one major mechanism of a personalized software component retrieval system. This search robot automatically finds out the Web servers providing reusable software components, extracts needed software components from servers, classifies the extracted components, and finally establishes their indexing information for local component retrieval in the future. For adaptively tuning the performance of software component extraction and classification, an adaptive thesaurus and an adaptive classifier, realized by neuro-fuzzy models, are embedded in this search robot, and their learning algorithms are also developed. A prototype of the personalized software component retrieval system including the search robot has been implemented to confirm its validity and evaluate the performance. Furthermore, the framework of proposed personalized search robot could be extended to the search and classification of other kinds of Internet documents.
WEBYACHT: A CONCEPT-BASED SEARCH TOOL FOR WWW
Authors: HSU CHING-CHI , CHANG CHIA-HUI
Published: April 2003

This paper describes a Web information search tool called WebYacht. The goal of WebYacht is to solve the problem of imprecise search results in current Web search engines. Due to incomplete information given by users and the diversified information published on the Web, conventional document ranking based on an automatic assessment of document relevance to the query may not be the best approach when little information is given as in most cases. In order to clarify the ambiguity of the short queries given by users, WebYacht adopts cluster-based browsing model as well as relevance feedback to facilitate Web information search. The idea is to have users give two to three times more feedback in the same amount of time that would be required to give feedback for conventional feedback mechanisms. With the assistance of cluster-based representation provided by WebYacht, a lot of browsing labor can be reduced. In this paper, we explain the techniques used in the design of WebYacht and compare the performances of feedback interface designs and to conventional similarity ranking search results.
A TWO-LEVELED CLASSIFICATION AND RETRIEVAL TECHNIQUE FOR PROCESS PROGRAM REUSE
Authors: Chen Jen-Yon Jason , Chou Shih-Chien
Published: April 2003

This paper proposes a classification and retrieval technique for process program reuse, which is composed of a syntax and a semantic level processing. The syntax level uses the process features of: phase, paradigm, technique, standard, and application domain. The facet approach is applied here, in which each feature corresponds to a facet. Since no complicated computations are involved, this level is expected to be efficient. Regarding the semantic level, it uses the process program contents of: product, product component, exception, work assignment, tool, and role. They are organized into a semantic network for classification and retrieval. Since process program contents are used, this level is expected to be precise. It, however, may be inefficient, because complicated computations are involved. The proposed classification and retrieval technique uses the syntax level processing before the semantic level. Since most unreusable process programs are filtered out in the syntax level, the semantic level operates on relatively few process programs. Therefore, this technique is expected to be both efficient and precise.
A PETRI-NETS-BASED APPROACH FOR WORKFLOW AND PROCESS AUTOMATION
Authors: YANG STEPHEN J. H. , CHEN CHYUN-CHYI
Published: April 2003

Based on the workflow management coalition (WFMC) standard and component software technologies, this paper addresses our Petri-nets-based approach for workflow and process automation. Petri nets provide graphical and mathematical formalisms for work-flow process definition and analysis. In this paper, we will present how to use Petri nets and a toolkit NCUPN (National Central University Petri Nets toolkit) for process definition and analysis. NCUPN is a Petri nets modeling and analysis toolkit developed to help software engineers in drawing and doing analysis. Once a workflow process is drawn using NCUPN, analysis can be done automatically. In this paper, we will demonstrate how to use NCUPN to analyze behavioral properties of workflow process, such as deadlock, liveness, safety, and starvation.
MANAGING ACTIVITY DYNAMICS OF WEB BASED COLLABORATIVE APPLICATIONS
Authors: LIU CHEN-CHUNG , CHEN GWO-DONG , OU KUO-LIANG , LIU BAW-JHIUNE , HORNG JORNG-TZONG
Published: April 2003

The World Wide Web has been widely accepted as a viable communication infrastructure to support collaborative activities on computer networks. While cooperating objects of different roles can easily and freely communicate knowledge on the web, the web site managers/developers must write programs to manage the communication behavior in collaborative activities. However, the current hypertext model for the web concentrates on the static structure of hypertext. Few conceptual specifications are capable of effectively integrating the hypertext model with activity dynamics to clarify the dynamic interaction and constraints of desired collaborative activities on the web. Furthermore, decision-makers must observe communication behavior on the web to adapt collaborative activities. Although web servers register each web access in a web log, up to now, only a few query or report mechanisms have been available to obtain required information from the web log. This study presents a specification to capture the static and dynamic structure of intended collaborative activities, and a query mechanism to obtain required information from the web log. The specification and query mechanism make it possible to construct a web site that will provide group activity space and flexibly interpret roles, encourage individuals to commit to responsibilities, and enable activities to be observed.
A FUZZY ROUTE GUIDANCE MODEL FOR INTELLIGENT IN-VEHICLE NAVIGATION SYSTEMS
Authors: CHIANG JUNG-HSIEN
Published: April 2003

This paper presents an adaptive fuzzy clustering model that can be used to identify nature subgroups of links as well as priority memberships in a route guidance system. The fuzzy route guidance model, inspired by the fuzzy clustering technique, provides an adaptive and efficient alternative to traditional fixed costs route guidance methods. Three specific objectives underlie the presentation of the fuzzy route guidance model in this paper. The first is to describe a general overview of the in-vehicle navigation system, and the second is to introduce the fuzzy route guidance model based on adaptive fuzzy clustering and least cost problem. The third part is to demonstrate that the proposed model is able to perform route guidance in road test.
A KNOWLEDGE-BASED METHOD FOR DERIVING CLASSES AND OBJECTS
Authors: LIU ALAN , SHR ARTHUR M. D.
Published: April 2003

Identifying classes and objects in an object-oriented (OO) software development method requires a great amount of domain-specific knowledge and OO developing experiences to achieve the work. Experienced developers always have heuristic solutions to different problems. However, novice developers have difficulties developing their desired OO software systems.

We propose a method that uses a knowledge-based system with the identification knowledge to support developers to obtain classes and objects that are suitable for one special domain problem. With the help of the identification knowledge, the developers can model the system easily and complete the rest of development work quickly.
ROBUST NEURAL APPROACH FOR THE ESTIMATION OF THE ESSENTIAL PARAMETERS IN COMPUTER VISION
Authors: CIRRINCIONE GIANSALVO , CIRRINCIONE MAURIZIO
Published: April 2003

The essential parameters approach is a well-known technique in computer vision for recovering the motion and scene parameters from a sequence of images. This approach has long been considered as suboptimal because of the underestimation of the effect of noise and outliers. This paper re-evaluates this method because it is correctly classified as a structured Total Least Squares problem and proposes very robust linear neurons for its solution. Then, a novel neural network, CASEDEL EXIN, which exploits these neurons together with the case deletion diagnostics, is introduced. It is not only very robust (outlier rejection), but is also able to identify the outliers. This fact can be exploited, for example, to refine the image segmentation.
INFORMATION BLENDING IN VIRTUAL ASSOCIATIVE NETWORKS: A NEW PARADIGM FOR SENSOR INTEGRATION
Authors: YUFIK YAN M. , MALHOTRA RAJ P.
Published: April 2003

Research reported in this article is motivated, in part, by current U.S. military programs aimed at the development of efficient data integration and sensor management methods capable of handling large sensor suites and achieving robust target recognition performance in real time scenarios. Modern sensor systems have shown good recognition abilities against a few isolated targets. However, these capabilities decline steeply when multiple sensors are acting against large target groups under realistic conditions requiring dynamic allocation of the sensor resources and efficient on-line integration and disambiguation of multiple sensor outputs. Neural networks and other sensor integration technologies have been inspired by cognitive models attributing human perceptual integration to parallel processing and convergence of simultaneous data streams. This article explores a different model emphasizing serial processing and association of consecutive memory traces in the Long Term Memory (LTM) into a globally connected memory structure called a Virtual Associative Network (VAN). Information integration in VAN is called blending. Target representation is constructed dynamically from the segments of virtual net matched serially against the input segments in the Short Term Memory (STM). This article will elaborate the concept of blending, reference its biological foundations, explain the difference between information blending and conventional sensor fusion techniques, and demonstrate blending applications in a large scale sensor management task.
ON THE EMERGENCE OF INTELLIGENT GLOBAL BEHAVIORS FROM SIMPLE LOCAL ACTIONS
Authors: BENJAMIN D. PAUL
Published: April 2003

Artificial Intelligence focuses on the question of how to design system to exhibit intelligent behaviour in complex environments. Complex global behaviours can emerge from simple systems acting in a complex environment; however, this emergence requires that the systems' internal structure reflect essential structures in the environment. This paper examines the algebraic structure of a system's actions. We find that these actions often possess a self-similar local neighborhood structure that permits analysis and synthesis to be performed locally yet produce global, intelligent behaviours. A procedure for finding this local structure is presented, and illustrated with examples.
AN INTRODUCTION TO AN EGOCENTRIC CONCEPT OF MACHINE INTELLIGENCE
Authors: PIENNAR RUDOLPH , KRUGER JOHAN J.
Published: April 2003

Intimate to the functioning and behavior of intelligent systems is the manner in which information is represented internally. The conventional approach to intelligent system design assumes a particular bias in the manner by which this information is represented. Typically, this is characterized by an "abstract" or "objective" design methodology which holds that intelligence is not a function of the physical nature of the system. Such an approach suffers from several shortcomings, most notably problems relating to scaling and complexity. Recent physiological research, however, has demonstrated that physical bodily form is a fundamental building block in the organization of mammalian cortical structures. Consequently, this article explores such a biologically motivated "subjective" or "egocentric" approach to system design, and demonstrates its utility in a simple robot arm control problem.
CLASSIFICATION AND FEATURE EXTRACTION OF PROTEIN STRUCTURES BASED ON STRUCTURE TRANSFORMATION
Authors: OHKAWA TAKENAO , NAMIHIRA DAISUKE , MAEDA TAKUJI , KOMODA NORIHISA , KIDERA AKINORI , NAKAMURA HARUKI
Published: April 2003

This paper presents a new method of comparison of protein structures from the viewpoint of the secondary structural elements. The structural similarity can be evaluated through the structure transformation from one protein to the other, which is composed of a set of predefined primitive operations that are applied to each of the secondary structural elements. The cost that is required for each of the primitive operations is defined in advance, and the similarity between the proteins is calculated as the total cost of transformation that is the sum of costs for applied primitive operations. In addition, a feature extraction method that is also based on the structural transformation is presented. In this method, the feature to be extracted is defined as a pair including a representative structure and a cluster region. The representative structure is generated by estimating the center of structural balance among proteins in one cluster using the transformation costs. The cluster region shows how far the cluster has spread. The effectiveness of these methods are empirically demonstrated through the experiments using the data in the Brookhaven Protein Data Bank.
GENE FAMILY IDENTIFICATION NETWORK DESIGN FOR PROTEIN SEQUENCE ANALYSIS
Authors: WU CATHY H. , HUANG HONGZHAN , MCLARTY JERRY
Published: April 2003

With the exponential accumulation of sequence data, continued progress in the Human Genome Project will depend increasingly on advanced computational tools to manage and analyze the data. Utilizing information embedded within families of homologous sequences, a gene family identification approach may facilitate the understanding of gene functions. We have developed a GeneFIND (Gene Family Identification Network Design) system for database searching against gene families. It provides rapid and accurate protein family identification by combining global and motif sequence similarities and incorporating ProClass family information. Multi-level filters are used, starting with the MOTIFIND neural networks and BLAST search, followed by SSEARCH alignment, motif pattern match, hidden Markov modeling of motifs and ClustalW motif alignment. GeneFIND has been implemented as a full-scale system for the classification of more than 1200 ProSite and 6000 PIR families. It has been used to identify thousands of new family members and is well suited for genomic sequence analysis. The system is available for on-line family identification from our WWW server ().
BIOLOGICAL DATA MINING USING BAYESIAN NEURAL NETWORKS: A CASE STUDY
Authors: MA QICHENG , WANG JASON T. L.
Published: April 2003

Biological data mining is the activity of finding significant information in biomolecular data. The significant information may refer to motifs, clusters, genes, and protein signatures. This paper presents an example of biological data mining: the recognition of promoters in DNA. We propose a two-level ensemble of classifiers to recognize E. Coli promoter sequences. The first-level classifiers include three Bayesian neural networks that learn from three different feature sets. The outputs of the first-level classifiers are combined in the second-level to give the final result. Empirical study shows that a precision rate of 92.2% is achieved, indicating an excellent performance of the proposed approach.
Homology of manifolds obtained by Dehn surgery on knots in lens spaces
Authors: Christensen Antje
Published: April 2003

The question whether or not a Dehn surgery on a knot in a lens space yields a lens space of the same order is investigated with homological techniques. Determining the first homology group of the lens space after surgery and of its covering yields some necessary conditions on the knot and the surgery curve. Application of these results along with a calculation of Seifert invariants answers the question completely for surgery on torus knots along nullhomological curves.
FROM FRAMED LINKS TO CRYSTALLIZATIONS OF BOUNDED 4-MANIFOLDS
Authors: CASALI MARIA RITA
Published: April 2003

It is well-known that every 3-manifold M3 may be represented by a framed link (L,c), which indicates the Dehn-surgery from [Formula: see text] to M3 = M3(L,c); moreover, M3 is the boundary of a PL 4-manifold M4 = M4(L, c), which is obtained from [Formula: see text] by adding 2-handles along the framed link (L, c).

In this paper we study the relationships between the above representations and the representation theory of general PL-manifolds by edge-coloured graphs: in particular, we describe how to construct a 5-coloured graph representing M4=M4(L,c), directly from a planar diagram of (L,c). As a consequence, relations between the combinatorial properties of the link L and both the Heegaard genus of M3=M3(L,c) and the regular genus of M4=M4(L,c) are obtained.
The Casson–Walker–Lescop Invariant as a Quantum 3-manifold Invariant
Authors: HABEGGER NATHAN , BELIAKOVA ANNA
Published: April 2003

Let Z(M) be the 3-manifold invariant of Le, Murakami and Ohtsuki. We give a direct computational proof that the degree 1 part of Z(M) satisfies [Formula: see text], where b1(M) denotes the first Betti number of M and where λM denotes the Lescop generalization of the Casson-Walker invariant of M. Moreover, if b1(M)=2, we show that Z(M) is determined by λM.
PERSISTENT INVARIANTS OF TANGLES
Authors: KREBES DAVID A. , SILVER DANIEL S. , WILLIAMS SUSAN G.
Published: April 2003

Invariants of virtual 2n-tangles t are defined using an analog of the Temperley-Lieb algebra. The invariants yield information about the bracket polynomial of any link in which t embeds.
The Generalized Smith Conjecture of Codimension Greater Than Two
Authors: Lü Zhi
Published: April 2003

In this paper we consider the generalized Smith conjecture of codimension greater than two, which says that no periodic tranformation of Sl can have the tame knotted Sh as fixed point set if l-h>2 and h>3. Using the Brieskorn spheres, this paper gives the explicit counterexamples to show that the conjecture is false in the DIFF category for the following cases: (i) l-h is even more than 2 and l is odd; (ii) 2l≤3(h+1) and h+1≡0 (mod 4).
THE SELF-LINKING NUMBER OF A CLOSED CURVE IN ℝn
Authors: AMILIBIA A. MONTESINOS , BALLESTEROS J. J. NUÑO
Published: April 2003

We introduce the self-linking number of a smooth closed curve α:S1→ℝn with respect to a 3-dimensional vector bundle over the curve, provided that some regularity conditions are satisfied. When n=3, this construction gives the classical self-linking number of a closed embedded curve with non-vanishing curvature [5]. We also look at some interesting particular cases, which correspond to the osculating or the orthogonal vector bundle of the curve.
UNCOUNTABLY MANY ARCS IN S3WHOSE COMPLEMENTS HAVE NON-ISOMORPHIC, INDECOMPOSABLE FUNDAMENTAL GROUPS
Authors: MYERS ROBERT
Published: April 2003

An uncountable collection of arcs in S3is constructed, each member of which is wild precisely at its endpoints, such that the fundamental groups of their complements are non-trivial, pairwise non-isomorphic, and indecomposable with respect to free products. The fundamental group of the complement of a certain Fox-Artin arc is also shown to be indecomposable.
EMBEDDING TANGLES IN LINKS
Authors: RUBERMAN DANIEL
Published: April 2003

Extending and reproving a recent result of D. Krebes, we give obstructions to the embedding of a tangle in a link.
VIRTUAL KNOT PRESENTATION OF RIBBON TORUS-KNOTS
Authors: SATOH SHIN
Published: April 2003

Any ribbon torus-knot in 4-space is naturally associated with a virtual knot. We investigate a relationship between ribbon torus-knots and virtual knots from this viewpoint. We also give a new example of a non-classical virtual knots which can not be detected by the group and the Z-polynomial.
WRITHING AND LINKING DENSITIES FOR CLOSED, CIRCULAR DNA
Authors: BENHAM CRAIG , MILLER DAVID
Published: April 2003

We develop formulae for local measures of writhing and linking density for closed, circular DNA.
POLYNOMIALS FOR A FAMILY OF BRUNNIAN LINKS
Authors: CHAN TAT-HUNG
Published: April 2003

We apply skein relations to derive recurrence relations for the HOMFLY polynomials of a family of Brunnian links. Solution of the recurrence relations yields closed-form formulas for the HOMFLY and hence the Jones polynomials.
ON WHITE'S FORMULA
Authors: EGGAR M. H.
Published: April 2003

A smooth knot is non-trivial precisely if it cannot be unlinked from every small deformation of itself. White's formula expresses the linking number of a representative of a knot and a deformation of it as a sum of two, not necessarily integral, terms — a writhe and a twist. An elementary proof is given of this formula. A byproduct of the proof is an easy derivation of the expression for the writhe of the knot in terms of standard invariants of the curve and the writhe of the knot diagram obtained by projection onto a plane.
ON DOUBLE-TORUS KNOTS (II)
Authors: HILL PETER , MURASUGI KUNIO
Published: April 2003

A double-torus knot is a knot embedded in a genus two Heegaard surface [Formula: see text] in S3. We consider double-torus knots L such that [Formula: see text] is connected, and consider fibred knots in various classes.
SUPERBRIDGE INDEX OF COMPOSITE KNOTS
Authors: JIN GYO TAEK
Published: April 2003

An upper bound of the superbridge index of the connected sum of two knots is given in terms of the braid index of the summands. Using this upper bound and minimal polygonal presentations, we give an upper bound in terms of the superbridge index and the bridge index of the summands when they are torus knots. In contrast to the fact that the difference between the sum of bridge indices of two knots and the bridge index of their connected sum is always one, the corresponding difference for the superbridge index can be arbitrarily large.
LINK HOMOTOPY AND QUASI SELF DELTA-EQUIVALENCE FOR LINKS
Authors: NAKANISHI YASUTAKA , SHIBUYA TETSUO
Published: April 2003

In this note, we will study on equivalence relations for links and we will give a necessary condition for equivalence in terms of the Alexander polynomial and show their differences.
WEB DIAGRAMS AND REALIZATION OF VASSILIEV INVARIANTS BY KNOTS
Authors: OHYAMA YOSHIYUKI
Published: April 2003

Recently it has been proved by K. Taniyama, S. Yamada and the author that for any natural number n and any knot K, there are infinitely many unknotting number one knots, all of whose Vassiliev invariants of order less than or equal to n coincide with those of K. In this paper we give another proof of this result by using web diagrams.
A COMBINATORIAL APPROACH TO LINKING NUMBERS IN RATIONAL HOMOLOGY SPHERES
Authors: STITZ CARL J.
Published: April 2003

In this paper we find a method to compute the classical Seifert-Threlfall linking number for rational homology spheres without using 2-chains bounded by the curves in question. By using a Heegaard diagram for the manifold, we describe link isotopy combinatorially using the three traditional Reidemeister moves along with a fourth move which is essentially a Kirby move along the characteristic curves. This result is mathematical folklore which we set in print. We then use this combinatorial description of link isotopy to develop and prove the invariance of linking numbers. Once the linking numbers are in place, matrix invariants such as the Alexander polynomial can be computed.
COMBINATORICS AND FOUR BRIDGED KNOTS
Authors: MATIGNON DANIEL
Published: April 2003

The ℝ P 3-Conjecture states a non-trivial knot in S 3 cannot yield ℝ P 3 by a Dehn surgery.

Generically, in the knot-space S3-N(K), the intersection of a projective plane ℝP2 in ℝ P 3, and any 2-sphere S2 in S3 pierced by K, is a 1-complex which can be viewed as a graph in either the projective plane or the 2-sphere. Gordon and Luecke have used similar graphs arising as the intersection of two 2-spheres, to prove that a knot in S3 is determined by its complement.

A part of this paper concerns some new combinatorial results on these graphs. They are considered as an unavoidable step towards showing that the ℝ P 3-Conjecture is true.

Moreover, we use these results to prove that any non-trivial knot that could yield ℝ P 3 has at least five bridges.
LARGE CHARACTERISTIC SUBGROUPS OF SURFACE GROUPS NOT CONTAINING ANY SIMPLE LOOPS
Authors: PIKAART M.
Published: April 2003

We determine the largest (i.e. smallest index) characteristic subgroup of surface groups not containing any simple loops.
ON THE NULLIFICATION WRITHE, THE SIGNATURE AND THE CHIRALITY OF ALTERNATING LINKS
Authors: HONGLER CAM VAN QUACH
Published: April 2003

In this paper, we relate the nullification writhe and the remaining writhe defined by C. Cerf to other link invariants. We prove that the nullification writhe of an oriented reduced alternating link diagram is equal, up to sign, to the signature of the link. Moreover, we relate the difference between the nullication writhe and the remaining writhe to invariants obtained from chessboard-coloured link diagrams such as their numbers of shaded and unshaded regions.
SEXTICS WITH SINGULAR POINTS IN SPECIAL POSITION
Authors: ARTAL E. , CARMONA J. , COGOLLUDO J.I. , TOKUNAGA HIRO-O
Published: April 2003

In this paper we show a Zariski pair of sextics which is not a degeneration of the original example given by Zariski. This is the first example of this kind known. The two curves of the pair have a trivial Alexander polynomial. The difference in the topology of their complements can only be detected via finer invariants or techniques. In our case the generic braid monodromies, the fundamental groups, the characteristic varieties and the existence of dihedral coverings of ℙ2 ramified along them can be used to distinguish the two sextics. Our intention is not only to use different methods and give a general description of them but also to bring together different perspectives of the same problem.
SHIFTING HOMOMORPHISMS IN QUANDLE COHOMOLOGY AND SKEINS OF COCYCLE KNOT INVARIANTS
Authors: CARTER J. SCOTT , JELSOVSKY DANIEL , KAMADA SEIICHI , SAITO MASAHICO
Published: April 2003

Homomorphisms on quandle cohomology groups that raise the dimensions by one are studied in relation to the cocycle state-sum invariants of knots and knotted surfaces. Skein relations are also studied.
Global Knotting in Equilateral Random Polygons
Authors: Diao Y. , Nardo J. C. , Sun Y.
Published: April 2003

In this paper, we study the knotting probability of equilateral random polygons. It is known that such objects are locally knotted with-probability arbitrarily close to one provided the length is sufficiently large ([4]). For Gaussian random polygons, it has been shown that the probability of global knottedness also tends to one as the length of the polygon tends to infinity [8]. In this paper, we prove that global knotting also occurs in equilateral random polygons with a probability approaching one as the length of the polygons goes to infinity.
Presentation of pure braid groups
Authors: DIGNE F. , GOMI V.
Published: April 2003

In this article we study by combinatorial methods presentations of the pure braid group associated with any Coxeter group. We generalize to all types the decomposition of the pure braid group into successive semi-direct products known in the case of type An.
TRACE FIELDS OF TWIST KNOTS
Authors: HOSTE JIM , SHANAHAN PATRICK D.
Published: April 2003

In this paper we compute the trace field for the family of hyperbolic twist knots. We describe this field as a simple extension ℚ(z0) where z0 is a specified root of a particular irreducible polynemial Φn(z)∈ℤ[z]. As a consequence, we find that the degree of the trace field is precisely two less than the-minimal crossing number of a twist knot.
LINKS WITH TRIVIAL JONES POLYNOMIAL
Authors: THISTLETHWAITE MORWEN
Published: April 2003

Examples of non-trivial 2- and 3-component links are given that cannot be distinguished from the corresponding unlink by means of the Jones polynomial.
THE SATURATED MAGNETIC FIELD OF THE NEUTRON STARS
Authors: ZHANG C. M.
Published: April 2003

Considering the ferromagnetic screening for the decay of the X-ray neutron star magnetic field in the binary accretion phase, the phase transition of ferromagnetic materials in the crust of neutron star induces the ferromagnetic screening saturation of the accreted crust, which results in the minimum surface magnetic field of the accreting neutron star, about 108 G, if the accreted matter has completely replaced the crust mass of the neutron star. The magnetic field evolution versus accreted mass is given as [Formula: see text], and the obtained magnetic field versus spin period relation is consistent with the distribution of the binary X-ray sources and recycled pulsars. The further thermal effect on the magnetic evolution is also studied.
CONSTRUCTING HYPERBOLIC SYSTEMS IN THE ASHTEKAR FORMULATION OF GENERAL RELATIVITY
Authors: YONEDA GEN , SHINKAI HISA-AKI
Published: April 2003

Hyperbolic formulations of the equations of motion are essential technique for proving the well-posedness of the Cauchy problem of a system, and are also helpful for implementing stable long time evolution in numerical applications. We, here, present three kinds of hyperbolic systems in the Ashtekar formulation of general relativity for Lorentzian vacuum spacetime. We exhibit several (I) weakly hyperbolic, (II) diagonalizable hyperbolic, and (III) symmetric hyperbolic systems, with each their eigenvalues. We demonstrate that Ashtekar's original equations form a weakly hyperbolic system. We discuss how gauge conditions and reality conditions are constrained during each step toward constructing a symmetric hyperbolic system.
GRAVITATIONAL COLLAPSE OF NEWTONIAN STARS
Authors: JUN JUNG-HWAN , HO YOUNG KWAK
Published: April 2003

We investigate spherically symmetric solutions for nonrelativistic cosmological fluid equations and thermodynamic equation of state for Newtonian stars of ideal gas. Using simple ansätze it is shown that the assumption of a polytrope, [Formula: see text], at the center of the star only suffices to obtain analytic solutions. We find collapse behavior for γ≤4/3 and oscillatory behavior for γ>4/3 along with the discussion on their mechanisms. For the oscillatory behavior we obtained the frequency of small oscillation ω which is [Formula: see text] times that obtained by Zel'dovich and Novikov.
STABLE INFLATIONARY DISSIPATIVE COSMOLOGIES
Authors: CHIMENTO LUIS P. , JAKUBI ALEJANDRO S. , PAVON DIEGO
Published: April 2003

The stability of the de Sitter era of cosmic expansion in spatially curved homogeneous isotropic universes is studied. The source of the gravitational field is an imperfect fluid such that the parameters that characterize it may change with time. In this way we extend our previous analysis for spatially-flat spaces as well as the work of Barrow.
INVESTIGATION OF RADIATIVE OUTFLOWS AROUND COMPACT OBJECTS
Authors: CHATTOPADHYAY INDRANIL , CHAKRABARTI SANDIP K.
Published: April 2003

Winds and outflows form in active galaxies and in binary systems which are known to harbour compact objects such as black holes. Matter starting subsonically from a disc must be accelerated very close to the black hole in order to reach a velocity comparable to the velocity of light, which is actually observed. In the absence of magnetic fields, winds forming in inner regions of accretion discs could primarily be accelerated by radiations emitted from this region where centrifugal force is important. We study critical point behaviour of outflows in presence of this radiative acceleration. We show that the momentum deposition term changes the character of the solution drastically depending on the magnitude and the location of the deposition. We discuss the implications of these solutions in detail. Particularly important is the fact that matter were found to be pushed to infinity, even when they were originally bound energetically. We perform numerical simulations by smoothed particle hydrodynamics (SPH), and show that these new solutions are stable.
A NEW STATIC SPHERICALLY SYMMETRIC SOLUTION IN SIX-DIMENSIONAL DILATONIC KALUZA–KLEIN THEORY
Authors: BIESIADA M. , MAŃKA R. , SYSKA J.
Published: April 2003

Multidimensional theories still remain attractive from the point of view of better understanding of fundamental interactions. In this paper we present a new static spherically symmetric solution in a six-dimensional Kaluza–Klein theory with a dilaton field. The solution offers a nonperturbative answer to the problem of metric back--reaction due to presence of a dilaton field. The spacetime described in our paper is everywhere regular without event horizon like the Gross–Perry five-dimensional Kaluza–Klein soliton. The presence of massless dilaton field has the same dynamical effect on test particles as the existence of massive matter which opens up the possibility to consider the dilaton field as a candidate for dark matter.
S-MATRICES FOR QUANTUM CHARGED MASSIVE SCALAR PARTICLES ON SCHWARZSCHILD AND REISSNER–NORDSTRÖM BLACK HOLES
Authors: FIRSOVA N. E.
Published: April 2003

We study the scattering problems arising when considering the contribution of the topologically inequivalent configurations (TICs) of the massive complex scalar fields on Schwarzschild and Reissner–Nordström black holes to the Hawking radiation. The corresponding S-matrices are explored and presented in the form convenient to numerical computations.
GRAVITATIONAL THERMODYNAMICS OF SPACETIME FOAM IN ONE-LOOP APPROXIMATION
Authors: LIU LIAO , MA YONGGE
Published: April 2003

We show from one-loop quantum gravity and statistical thermodynamics that the thermodynamics of quantum foam in flat spacetime and Schwarzschild spacetime is exactly the same as that of Hawking–Unruh radiation in thermal equilibrium. This means we show unambiguously that Hawking–Unruh thermal radiation should contain thermal gravitons or the contribution of quantum spacetime foam. As a by-product, we give also the quantum gravity correction in one-loop approximation to the classical black hole thermodynamics.
A HAMILTONIAN TREATMENT OF FIVE-DIMENSIONAL KALUZA–KLEIN GRAVITY
Authors: SAJKO W. N.
Published: April 2003

We give a Hamiltonian treatment of 5D vacuum Kaluza–Klein theory that is unrestricted in the extra coordinate dependence. When the extra coordinate dependence is removed from the 5D metric we recover the Hamiltonian for gravity and electromagetism nonminimally coupled to a scalar field. The energies of 5D uncharged and charged soliton solutions are calculated via the Hamiltonian and are identified with the total mass. The expressions for the total mass are shown to agree with the sum of scalar and gravitational masses calculated from the scalar-tensor induced matter in 4D. A semi-classical derivation of the temperature for the uncharged solitons is calculated and it is shown that the only nontrivial member of the 5D class is the 4D Schwarzschild solution trivially embedded in 5D, and therefore the entropy obeys the one-quarter area law.
MATCHING CHARACTERISTIC CODES: EXPLOITING TWO DIRECTIONS
Authors: LEHNER LUIS
Published: April 2003

Combining incoming and outgoing characteristic formulations can provide numerical relativists with a natural implementation of Einstein's equations that better exploits the causal properties of the spacetime and gives access to both null infinity and the interior region simultaneously (assuming the foliation is free of caustics and crossovers). We discuss how this combination can be performed and illustrate its behavior in the Einstein–Klein–Gordon field in 1D.
CAUSAL BULK VISCOUS COSMOLOGIES IN CONFORMALLY FLAT SPACETIME
Authors: MAK M. K. , HARKO T.
Published: April 2003

The evolution of a causal bulk viscous cosmological fluid filled open conformally flat spacetime is considered. By means of appropriate transformations the equation describing the dynamics and evolution of the very early Universe can be reduced to a first order Abel type differential equation. In the case of a bulk viscosity coefficient proportional to the square root of the density, ξ~ρ1/2, an exact and two particular approximate solutions are obtained. The resulting cosmologies start from a singular state and generally have a noninflationary behavior, the deceleration parameter tending, in the large time limit, to zero. The thermodynamic consistency of the results is also checked.
LRS BIANCHI I COSMOLOGICAL UNIVERSE MODELS WITH VARYING COSMOLOGICAL TERM Λ
Authors: PRADHAN ANIRUDH , KUMAR AMBARISH
Published: April 2003

Einstein's field equations with cosmological term Λ varying with time are considered in the context of general homogeneous, anisotropic universes in a way which conserves the energy–momentum tensor of matter content. It is shown that the field equations are solvable for any arbitrary cosmic scale functions. Some physical and geometrical features of the models are discussed.
GRAVITY ON EXOTIC R4's WITH FEW SYMMETRIES
Authors: SŁADKOWSKI J.
Published: April 2003

We use various results concerning isometry groups of Riemannian and pseudo-Riemannian manifolds to prove that there are exotic R4's which allow the action of only SO(n, 1), SO(n, 2) or finite groups as isometry groups.
COSMIC NO-HAIR CONJECTURE IN EINSTEIN–CARTAN THEORY
Authors: LU H. Q. , HARKO T. , MAK M. K.
Published: April 2003

We prove the cosmic no-hair conjecture in the Einstein–Cartan theory by taking into account the effects due to the spin of matter. If the ordinary matter forming the cosmological fluid satisfies the dominant and strong energy conditions and the anisotropy energy σ2 is larger than the spin energy S2 (i.e. σ2-S2≥ 0), then all initially expanding Bianchi cosmologies-except type IX- evolve toward the de Sitter spacetime on a Hubble expansion time [Formula: see text]. The behavior of the Bianchi type IX Universe is similar, provided that the cosmological constant is larger than the half of the largest scalar spatial curvature (3)R max .
BULK VISCOUS FRW COSMOLOGY IN LYRA GEOMETRY
Authors: PRADHAN A. , YADAV V. K. , CHAKRABARTY INDRAJIT
Published: April 2003

We have studied an isotropic homogeneous FRW universe in the presence of a bulk viscous fluid within the framework of Lyra's geometry. We have obtained exact solutions of the Sen equations assuming the deceleration parameter to be constant. The coefficient of bulk viscosity has been assumed to be a power function of the mass density. With this assumption, we have considered the behavior of the displacement field and the energy density for both power-law and exponential expansions of the universe. We show that our models are generalised and we obtain the results of previous works by considering k=0 and k=-1.
SYMMETRY WITHOUT SYMMETRY: NUMERICAL SIMULATION OF AXISYMMETRIC SYSTEMS USING CARTESIAN GRIDS
Authors: ALCUBIERRE MIGUEL , BRÜGMANN BERND , HOLZ DANIEL , TAKAHASHI RYOJI , BRANDT STEVEN , SEIDEL EDWARD , THORNBURG JONATHAN
Published: April 2003

We present a new technique for the numerical simulation of axisymmetric systems. This technique avoids the coordinate singularities which often arise when cylindrical or polar-spherical coordinate finite difference grids are used, particularly in simulating tensor partial differential equations like those of 3+1 numerical relativity. For a system axisymmetric about the z axis, the basic idea is to use a three-dimensional Cartesian(x,y,z) coordinate grid which covers (say) the y=0 plane, but is only one finite-difference-molecule–width thick in the y direction. The field variables in the central y=0 grid plane can be updated using normal (x,y,z)-coordinate finite differencing, while those in the y≠ 0 grid planes can be computed from those in the central plane by using the axisymmetry assumption and interpolation. We demonstrate the effectiveness of the approach on a set of fully nonlinear test computations in 3+1 numerical general relativity, involving both black holes and collapsing gravitational waves.
HAMILTONIAN ANALYSIS OF GENERAL RELATIVITY WITH THE IMMIRZI PARAMETER
Authors: SÁ NUNO BARROS E
Published: April 2003

Starting from a Lagrangian we perform the full constraint analysis of the Hamiltonian for General relativity in the tetrad-connection formulation for an arbitrary value of the Immirzi parameter and solve the second class constraints, presenting the theory with a Hamiltonian composed of first class constraints which are the generators of the gauge symmetries of the action. In the time gauge we then recover Barbero's formulation of gravity.
HYPOTHESIS OF PATH INTEGRAL DUALITY: APPLICATIONS TO QED
Authors: SHANKARANARAYANAN S. , PADMANABHAN T.
Published: April 2003

We use the modified propagator for quantum field based on a "principle of path integral duality" proposed earlier in a paper by Padmanabhan to investigate several results in QED. This procedure modifies the Feynman propagator by the introduction of a fundamental length scale. We use this modified propagator for the Dirac particles to evaluate the first order radiative corrections in QED. We find that the extra factor of the modified propagator acts like a regulator at the Planck scales thereby removing the divergences that otherwise appear in the conventional radiative correction calculations of QED. We find that: (i) all the three renormalization factors Z1, Z2, and Z3 pick up finite corrections and (ii) the modified propagator breaks the gauge invariance at a very small level of [Formula: see text]. The implications of this result to generation of the primordial seed magnetic fields are discussed.
A THEORY OF TIME-VARYING CONSTANTS
Authors: BELINCHÓN JOSÉ ANTONIO , ALFONSO-FAUS ANTONIO
Published: April 2003

We present a flat (K=0) cosmological model, described by a perfect fluid with the "constants" G, c and Λ varying with cosmological time t. We introduce Planck's "constant" ℏ in the field equations through the equation of state for the energy density of radiation. We then determine the behaviour of the "constants" by using the zero divergence of the second member of the modified Einstein's field equations i.e. div [Formula: see text], together with the equation of state and the Einstein cosmological equations. Assuming realistic physical and mathematical conditions we obtain a consistent result with ℏ c= constant . In this way we obtain gauge invariance for the Schrödinger equation and the behavior of the remaining "constants."
WEIGHING THE UNIVERSE WITH ACCELERATORS AND DETECTORS
Authors: BRHLIK MICHAL , CHUNG DANIEL J. H. , KANE GORDON L.
Published: April 2003

Suppose the lightest superpartner (LSP) is observed at colliders, and WIMPs are detected in explicit experiments. We point out that one cannot immediately conclude that cold dark matter (CDM) of the universe has been observed, and we determine what measurements are necessary before such a conclusion is meaningful. We discuss the analogous situation for neutrinos and axions; in the axion case we have not found a way to conclude axions are the CDM even if axions are detected.