bluuebunny/crossref_metadata_2025 huggingface dataset:
USING COMPUTER SIMULATIONS FOR EVALUATING THE EFFICACY OF BREAST CANCER CHEMOTHERAPY PROTOCOLS
Authors: SHOCHAT ELIEZER , HART DVORA , AGUR ZVIA
Published: July 2002

The fundamental strategy of chemotherapy is to maximize tumor eradication within the limits of tolerable toxicity to the organism. To demonstrate the use of mathematical models in designing treatment protocols, we modeled the effect of chemotherapy on tumor mass and simulated the outcome of several neoadjuvant protocols for breast cancer disease. The model assumes unperturbed tumor growth, superimposed by periods of tumor regression during treatment applications. It takes into account both cell cycle specific (CCS) and cell-cycle non specific drugs (CCNS). Three possible modes of growth (exponential, Gompertz and power laws) were simulated in the study. The model parameters (such as cytotoxic activity of a given protocol) were estimated by best fit procedure from the clinical data of tumor regression following neoadjuvant treatments. The estimated parameters were then used to simulate various regimens that are employed today in the treatment of adjuvant and metastatic breast cancer. Our results suggest that although high dose chemotherapy (HDT) cannot eradicate overt metastatic disease, it may lead to cure if applied early in the natural history of breast cancer. Moreover, the simulations predict a better response for a rather toxic dose dense regimen, as compared to a more conventional protocol. However, our simulations suggest that a well tolerable continuous protocol is no less efficient. The results of the study provide insights into the effectivity of chemotherapy and may assist in designing better protocols.
P-ADIC DYNAMICAL SYSTEMS AND NEURAL NETWORKS
Authors: ALBEVERIO SERGIO , KHRENNIKOV ANDREI , TIROZZI BRUNELLO
Published: July 2002

A p-adic model which describes a large class of neural networks is presented. In this model the states of neurons are described by digits in the canonical expansion of a p-adic number. Thus each p-adic number represents a configuration of firing and non firing neurons. The process of recognition of patterns is investigated in the P-adic framework. We study heteroassociative and autoassociative nets. P-adic dynamical systems are used to describe a feedback process for autoassociative nets.
A MULTI-AGENT SYSTEM ARCHITECTURE FOR DISTRIBUTED COMPUTER VISION
Authors: GRAF THORSTEN , KNOLL ALOIS
Published: July 2002

We present a multi-agent system architecture dedicated to model computer vision systems, which provides the vision system with a great degree of flexibility. The basic idea of this architecture is to model a vision system as a society of autonomous agents, where each agent is responsible for specific vision tasks, the control strategy of a vision system is decentralized, and agents communicate using a flexible but easy understandable communication language. This directly leads to self-organizing vision systems, which accomplish vision tasks by goal-driven communication processes. We describe in detail the basic concepts of the proposed multi-agent system approach including the agent architectures, the communication language and network, as well as the interaction strategies. As a testbed for the proposed architecture we have modeled an object recognition system as an assembly of agents which organize themselves according to a given recognition task by employing communication.
IMPROVING PERFORMANCE OF INDUCTIVE MODELS THROUGH AN ALGORITHM AND SAMPLE COMBINATION STRATEGY
Authors: VAFAIE HALEH , ABBOTT DEAN , HUTCHINS MARK , MATKOVSKY I. PHILIP
Published: July 2002

Multiple approaches have been developed for improving predictive performance of a system by creating and combining various learned models. There are two main approaches to creating model ensembles. This first is to create a set of learned models by applying an algorithm repeatedly to different training sample data, the second applies various learning algorithms to the same sample data. The predictions of the models are then combined accordings to a voting scheme. This paper presents a method for combining models that were developed using numerous samples, modeling algorithms, and modelers and compares it with the alternate approaches. The presented results are based on findings from an ongoing operational data mining initiative with respect to selecting a model set that is best able to meet defined goals from among trained models. The operational goals to be attained in this initiative are to deploy data mining model(s) that maximizes specificity with minimal negative impact to sensitivity. The results of the model combination methods are evaluated with respect to sensitivity and false alarm rates and are then compared against other approaches.
KNOTS WITH GIVEN FINITE TYPE INVARIANTS AND Ck-DISTANCES
Authors: NAKANISHI YASUTAKA , OHYAMA YOSHIYUKI
Published: July 2002

We show that for any given pair of a natural number n and a knot K, there are infinitely many knots Jm (m=1,2,…) such that their Vassiliev invariants of order less than or equal to n coincide with those of K and that each Jm has Ck-distance 1 (k≠q 2, k=1, …, n) and C2-distance 2 from the knot K. The Ck-distance means the minimum number of Ck-moves which transform one knot into the other.
PRIMORDIAL SPACETIME FOAM AS AN ORIGIN OF COSMOLOGICAL MATTER–ANTIMATTER ASYMMETRY
Authors: AHLUWALIA D. V. , KIRCHBACH M.
Published: July 2002

The possibility is raised that the observed cosmological matter–antimatter asymmetry may reside in asymmetric spacetime fluctuations and their interplay with the Stückelberg–Feynman interpretation of antimatter. The presented thesis also suggests that the effect of spacetime fluctuations is to diminish the fine structure constant in the past. Recent studies of the QSO absorption lines provide a 4.1 standard deviation support for this prediction. Our considerations suggest that in the presence of spacetime fluctuations, the principle of local gauge invariance, and the related notion of parallel transport, must undergo fundamental changes.
ON THE CONTRIBUTION OF DENSITY PERTURBATIONS AND GRAVITATIONAL WAVES TO THE LOWER ORDER MULTIPOLES OF THE COSMIC MICROWAVE BACKGROUND RADIATION
Authors: DIMITROPOULOS A. , GRISHCHUK L. P.
Published: July 2002

The important studies of Peebles, and Bond and Efstathiou have led to the formula Cℓ= const. /[ℓ(ℓ+1)] aimed at describing the lower order multipoles of the CMBR temperature variations caused by density perturbations with the flat spectrum. Clearly, this formula requires amendments, as it predicts an infinitely large monopole C0, and a dipole moment C1 only 6/2 times larger than the quadrupole C2, both predictions in conflict with observations. We restore the terms omitted in the course of the derivation of this formula, and arrive at a new expression. According to the corrected formula, the monopole moment is finite and small, while the dipole moment is sensitive to short-wavelength perturbations, and numerically much larger than the quadrupole, as one would expect on physical grounds. At the same time, the function ℓ(ℓ+1)Cℓ deviates from a horizontal line and grows with ℓ, for ℓ≥2. We show that the inclusion of the modulating (transfer) function terminates the growth and forms the first peak, recently observed. We fit the theoretical curves to the position and height of the first peak, as well as to the observed dipole, varying three parameters: red-shift at decoupling, red-shift at matter-radiation equality, and slope of the primordial spectrum. It appears that there is always a deficit, as compared with the COBE observations, at small multipoles, ℓ~10. We demonstrate that a reasonable and theoretically expected amount of gravitational waves bridges this gap at small multipoles, leaving the other fits as good as before. We show that the observationally acceptable models permit somewhat "blue" primordial spectra. This allows one to avoid the infrared divergence of cosmological perturbations, which is otherwise present.
SYMMETRIES OF THE DUAL METRICS
Authors: BALEANU DUMITRU
Published: July 2002

In this paper the symmetries of the dual manifold are investigated. We found the conditions when the manifold and its dual admit the same Killing vectors and Killing–Yano tensors. The dual conformal Killing vectors and dual conformal Killing–Yano tensors were investigated. In the case of an Einstein's metric gμν the corresponding equations for its dual were found. The examples of Kerr–Newman geometry and the separable coordinates in 1+1 dimensions are analyzed in details.
EXTENDED PARTICLE MODELS BASED ON HOLLOW SINGULAR HYPERSURFACES IN GENERAL RELATIVITY: CLASSICAL AND QUANTUM ASPECTS OF CHARGED TEXTURES
Authors: ZLOSHCHASTIEV KONSTANTIN G.
Published: July 2002

In the present paper we construct classical and quantum models of an extended charged particle. One shows that consecutive modelling can be based on the hollow thin-wall charged texture which acquires gravitational mass due to Einstein–Maxwell interaction. We demonstrate that such a model has equilibrium states at the radius equal to the established classical radius of a charged particle. Also we consider quantum aspects of the theory and obtain the Dirac sea conception in a natural way. Besides, the phenomenological unification on the mass level of the two families of elementary particles, charged pions and electrons and positrons, evidently arises as the effect induced by classical and quantum gravity prior to Standard Model.
ALGEBRAIC APPROACH TO THE PSEUDOHARMONIC OSCILLATOR IN 2D
Authors: DONG SHI-HAI , MA ZHONG-QI
Published: July 2002

A realization of the ladder operators for the solutions to the Schrödinger equation with a pseudoharmonic oscillator in 2D is presented. It is shown that those operators satisfy the commutation relations of an SU(1, 1) algebra. Closed analytical expressions are evaluated for the matrix elements of some operators r2 and r∂/∂ r
INFORMATION FUNCTIONAL MECHANISM OF CYCLIC FUNCTIONING
Authors: LERNER VLADIMIR S.
Published: July 2002

On the basis of a conceptual analysis of the Informational Macrodynamics' equations, this paper introduces a unified information systemic model of evolution including the information functional mechanisms of self-organization, mutation, adaptation, control, the double spiral's genetics with coding language, the system's generation, decaying, and heredity, considered as the information regularities of developing macrosystems.
A RESOURCE DEPENDENT FISHERY MODEL WITH OPTIMAL HARVESTING POLICY
Authors: DUBEY BALRAM , CHANDRA PEEYUSH , SINHA PRAWAL
Published: July 2002

A dynamic model for a single-species fishery, which depends partially on a logistically growing resource with functional response, is proposed using taxation as control instrument to protect fish population from overexploitation. The analysis of the model shows that both the equilibrium density of fish population as well as the maximum sustainable yield increase as resource biomass density increases. The optimal harvesting policy is also discussed with the help of Pontryagin's Maximum Principle. It is found that for the optimum equilibrium value of resource biomass density, the total user's cost of harvest per unit effort must be equal to the discounted value of future price at the steady state.
OPTIMAL ALLOCATION OF MULTISTATE ELEMENTS IN LINEAR CONSECUTIVELY-CONNECTED SYSTEMS WITH DELAYS
Authors: LEVITIN GREGORY
Published: July 2002

A linear consecutively-connected system consists of N + 2 linear ordered positions. The first position contains a source of a signal and the last one contains a receiver. M statistically independent multistate elements (retransmitters) with different characteristics are to be allocated at the N intermediate positions. The elements provide retransmission of the received signal to the next few positions. Each element can have different states determined by a number of positions that are reached by the signal generated by this element. The probability of each state for any given element depends on the position where it is allocated. The signal retransmission process is associated with delays. The system fails if the signal generated by the source can not reach the receiver within a specified time period.

A problem of finding an allocation of the multistate elements that provides the maximal system reliability is formulated. An algorithm based on the universal generating function method is suggested for the system reliability determination. This algorithm can handle cases where any number of multistate elements are allocated in the same position while some positions remain empty. It is shown that such an uneven allocation can provide greater system reliability than an even one. A genetic algorithm is used as an optimization tool in order to solve the optimal element allocation problem.
SCANNING TUNNELING MICROSCOPY INVESTIGATION OF THE Si(103)- (1 × 1)–In SURFACE
Authors: GAI ZHENG , YANG W. S. , XUE Q.-K. , SAKURAI T. , ZHAO R. G.
Published: July 2002

In view of the special importance of the IV(103)- (1× 1)–III surface structures to the III/IV interfacial systems, in this paper the atomic structure of the Si(103)-(1× 1)–In surface is studied by means of scanning tunneling microscopy. The model that contains an indium and a silicon adatom in a unit cell, which has passed the test of low energy electron diffraction calculations, is confirmed to be correct. The dangling bond of the silicon adatom is found to be essentially empty.
DIFFUSE LEED INTENSITY CALCULATIONS TAKING INTO ACCOUNT THE PAIR CORRELATION EFFECTS IN PARTIALLY ORDERED OVERLAYER
Authors: ZASADA I. , RYCHTELSKA T.
Published: July 2002

The elastic diffuse intensity of electrons scattered by a short-range-ordered adlayer depends on the structure factors and on renormalized t matrices for each kind of occupied bonding sites. In many cases, the computation of these structure factors is a crucial point for the application of the general DLEED theory. Their determination necessitates the knowledge of the site-occupancy pair correlation functions. Up to now two procedures removing pair correlation effects from the data have been used for DLEED intensity calculations. The first procedure, the Y-function method, can be applied only in the particular case where there is one kind of chemisorption site. The second one was proposed recently and is based on the sampling of diffuse LEED intensity distributions by conventional spot intensities. The aim of this paper is to study DLEED intensity distribution coming from the sampling method and from the general treatment of DLEED taking into account the pair correlation effects. We take as an example the Pt(111)/CO system. The site-occupancy pair correlation functions of CO adsorbed on Pt(111) are obtained by a Monte Carlo simulation. DLEED intensities are analyzed using the energy-dependent I–V curves.
SURFACE ROUGHNESS AND RESONANT SCATTERING EFFECTS IN SOFT X-RAY SPECKLE FROM RANDOM SEMICONDUCTOR INTERFACES
Authors: ADAMCYK M. , EISEBITT S. , KARL A. , NICOLL C. , PINNINGTON T. , SCHERER R. , TIEDJE T. , EBERHARDT W.
Published: July 2002

We report the use of coherent soft X-ray scattering, or speckle, to study the morphology of random surfaces on single crystal semiconductor substrates. The experiments were carried out with photon energies in the 266–290 eV range. The effect of the magnitude of the roughness on the scattering was observed by measuring speckle patterns at various angles of incidence from two different surfaces with InP islands in the nanometer size range and in the micron range. The effect of element-specific resonant scattering was explored with a PMMA-coated textured silicon sample by tuning the wavelength to the carbon K-edge. Two dimensional numerical simulations of the coherent scattering have been carried out in the Fraunhofer approximation, using AFM data for the sample surface morphology. Good agreement with the observed speckle patterns was obtained, taking into account the 20 μm lateral coherence length of the source.
A Case of Missed Scaphoid Dislocation in Association with Monteggia Fracture Dislocation and Compartment Syndrome
Authors: Leung Y. F. , Kam W. L. , Ip P. S. , Wai Y. L.
Published: July 2002

A case of volar and ulnar solitary dislocation of the scaphoid of the right hand associated with type 3 Monteggia fracture dislocation (Bado) of the same limb is reported. It was complicated by median nerve palsy which was masked by the compartment syndrome of the forearm. He was treated with open reduction, internal fixation and decompression of the median nerve. The functional result is good.

Solitary dislocation of the scaphoid is a very rare carpal bone injury. Isolated case reports were published in the past. However, it was complicated with median nerve palsy and masked by the compartment syndrome of the forearm that had never been described.
LONGITUDINAL MEDIAN NERVE CONDUCTION STUDIES AFTER ENDOSCOPIC CARPAL TUNNEL RELEASE
Authors: Nakamura Yukio , Uchiyama Shigeharu , Toriumi Hiroshi , Nakagawa Hiroyuki , Miyasaka Tada-atsu
Published: July 2002

Forty hands of 36 patients who had undergone endoscopic carpal tunnel release (ECTR), utilising Chow's two-portal technique after being diagnosed with idiopathic carpal tunnel syndrome, were subjected to longitudinal median nerve conduction studies. The distal motor latency (DML) was examined pre-operatively on all the hands, which were re-examined at the post-operative 1st, 3rd, 6th and 12th months. Rapid improvement of DML was observed post-operatively in the first three months. These improvements patterns are not much different from those after open carpal tunnel release (OCTR) reported in the literatures. We consider that the data reported herein can be used as standards of DML course after ECTR.
ARCHITECTURE OF A UNIVERSAL DATABASE: A FRAME MODEL APPROACH
Authors: FONG JOSEPH , HUANG SHI-MING
Published: July 2002

RDB has been dominant in the industry for the last decade. OODB is recongnized as a post-relational technology that can improve productivity, Hierarchical Database and Network Database were popular in the 1970s, and have been developed into legacy database systems. The DBMS of various data models have proliferated into many companies, and become their important assets. There is a need to integrate these database system into a data warehouse in the company. We investigate a solution to the problem by offering an architecture of a universal database for the connectivity of various DBMSs using different data models. A frame model is chosen to represent the conceptual and logical schema of the universal database, which structures an application domain into classes organized via generalization, aggregaton and user-defined relationships, and its data in relational tables. The schemas of the existing database systems are translated into frame model conceptual shcemas which are integrated into a global frame model in a knowledge representation that includes classes for object structure descriptions and constraints for supporting user-defined relationships. The universal database is implemented by a relational DBMS as a kernel. In addition to relational tables, the universal database consists of program area to emulate database navigation in nonrelatoinal DBMS, method classes to implement program calls to emulate methods of OODBMS, and contraint classes to preserve semantic and resolve naming conflicts in schema translation and integration. To ensure each database program access the universal database, a database gateway for each source DBMS is developed to translate their DML into SQL, which is chosen to be its kernel database language, for its user-friendliness, standardization and popularity in the industry.
THE BRITTEN-JONES AND NEUBERGER SMILE-CONSISTENT WITH STOCHASTIC VOLATILITY OPTION PRICING MODEL: A FURTHER ANALYSIS
Authors: ROSSI ALESSANDRO
Published: July 2002

In part of the recent financial literature, exotic option pricing models have been built by establishing a link with European-style options. All these models share the characteristic of being consistent with the observed market smile. They differ respect to the specification of the volatility process. This paper provides a deeper insight into the Britten-Jones and Neuberger (1999) smile-consistent no arbitrage with stochastic volatility option pricing model. Their approach is similar, in spirit, to that one of Derman and Kani (1997), but the implementation is simpler and faster. We explain the main features of the model by performing a set of exercises. In addition we propose some extensions of the model, which make it more flexible.
Internationalization of the Taiwan Financial Industry: Equity Markets, Efficiency and Short-Term Capital Flows
Authors: Scott James H.
Published: July 2002

Strong, developed economies need well-functioning equity markets. Such markets require openness. Open equity markets attract different types of investors, some more useful than others. Just like in the debt market, the equity investors who best serve the social good are those who seek to understand the economic fundamentals underlying corporate profitability. Other, momentum, investors are more like gamblers whose presence is largely unavoidable, and who contribute little to economic efficiency or financial stability. The regulatory challenge is to mitigate the effects of momentum investors without discouraging the fundamental investors.
THE POSITIVE PREKERNEL OF A COOPERATIVE GAME
Authors: SUDHÖLTER PETER , PELEG BEZALEL
Published: July 2002

The positive prekernel, a solution of cooperative transferable utility games, is introduced. We show that this solution inherits many properties of the prekernel and of the core, which are both sub-solutions. It coincides with its individually rational variant, the positive kernel, when applied to any zero-monotonic game. The positive (pre)kernel is a sub-solution of the reactive (pre)bargaining set. We prove that the positive prekernel on the set of games with players belonging to a universe of at least three possible members can be axiomatized by non-emptiness, anonymity, reasonableness, the weak reduced game property, the converse reduced game property, and a weak version of unanimity for two-person games.
A SIMPLE CONSTRUCTION OF GENERALIZED HARMONIC MAPS DISCONTINUOUS EVERYWHERE
Authors: JI MIN
Published: July 2002

This paper constructs an everywhere discontinuous harmonic map from a domain of dimension 2 into S1. Our construction is simpler than that of L. Almeida.
NOWHERE-ZERO HARMONIC SPINORS AND THEIR ASSOCIATED SELF-DUAL 2-FORMS
Authors: SCORPAN ALEXANDRU
Published: July 2002

Let M be a closed oriented 4-manifold, with Riemannian metric g, and a [Formula: see text]-structure induced by an almost-complex structure ω. Each connection A on the determinant line bundle induces a unique connection ∇A, and Dirac operator [Formula: see text] on spinor fields. Let [Formula: see text] be the natural squaring map, taking self-dual spinors to self-dual 2-forms.

In this paper, we characterize the self-dual 2-forms that are images of self-dual spinor fields through σ. They are those α for which (off zeros) c1(α)=c1(ω), where c1(α) is a suitably defined Chern class. We also obtain the formula: [Formula: see text].

Using these, we establish a bijective correspondence between: {Kähler forms α compatible with a metric scalar-multiple of g, and with c1(α)=c1(ω)} and {gauge classes of pairs (φ,A), with ∇Aφ=0}, as well as a bijective correspondence between: {Symplectic forms α compatible with a metric conformal to g, and with c1(α)=c1(ω)} and {gauge classes of pairs (φ,A), with [Formula: see text], and <∇Aφ,iφ>ℝ=0, and φ nowhere-zero}.
AUTOMATIC IDENTIFICATION OF DIATOMS USING VISUAL HUMAN-INTERPRETABLE FEATURES
Authors: FISCHER STEFAN , BUNKE HORST
Published: July 2002

In this paper we present an identification scheme for diatoms using visual human-interpretable features. Diatoms are unicellular algae found in water and other places wherever there is humidity and enough light for photosynthesis. The automatic identification of diatoms has applications in a number of areas, for example, environmental monitoring and climate research. The overall identification is performed by an ensemble of multiple decision trees following the bagging approach. The use of human-interpretable features in contrast to traditional features, such as Fourier descriptors or moment invariants, makes it possible for a human expert to verify the induced decision trees and opens up the possibility of integrating human expert knowledge into automatically derived decision trees.
TRADING BEHAVIOR AND EXCESS VOLATILITY IN TOY MARKETS
Authors: MARSILI MATTEO , CHALLET DAMIEN
Published: July 2002

We study the relation between the trading behavior of agents and volatility in toy markets of adaptive inductively rational agents. We show that excess volatility, in such simplified markets, arises as a consequence of (i) the neglect of market impact implicit in price taking behavior and of (ii) excessive reactivity of agents. These issues are dealt with in detail in the simple case without public information. We also derive, for the general case, the critical learning rate above which trading behavior leads to turbulent dynamics of the market.
DENSE GRANULAR MEDIA AS ATHERMAL GLASSES
Authors: KURCHAN JORGE
Published: July 2002

We briefly describe how mean-field glass models can be extended to the case where the bath and friction are non-thermal. Solving their dynamics, one discovers a temperature with a thermodynamic meaning associated with the slow rearrangements, even though there is no thermodynamic temperature at the level of fast dynamics. This temperature can be shown to match the one defined on the basis of a flat measure over blocked (jammed) configurations. Numerical checks on realistic systems suggest that these features may be valid in general.
Modelling Migration and Economic Agglomeration with Active Brownian Particles
Authors: Schweitzer Frank
Published: July 2002

We propose a stochastic dynamic model of migration and economic aggregation in a system of employed (immobile) and unemployed (mobile) agents which respond to local wage gradients. Dependent on the local economic situation, described by a production function which includes cooperative effects, employed agents can become unemployed and vice versa. The spatio-temporal distribution of employed and unemployed agents is investigated both analytically and by means of stochastic computer simulations. We find the establishment of distinct economic centers out of a random initial distribution. The evolution of these centers occurs in two different stages: (i) small economic centers are formed based on the positive feedback of mutual stimulation/cooperation among the agents, (ii) some of the small centers grow at the expense of others, which finally leads to the concentration of the labor force in different extended economic regions. This crossover to large-scale production is accompanied by an increase in the unemployment rate. We observe a stable coexistence between these regions, although they exist in an internal quasistationary non-equilibrium state and still follow a stochastic eigendynamics.
VLSI cell placement techniques
Authors: Shahookar K. , Mazumder P.
Published: July 2002

VLSI cell placement problem is known to be NP complete. A wide repertoire of heuristic algorithms exists in the literature for efficiently arranging the logic cells on a VLSI chip. The objective of this paper is to present a comprehensive survey of the various cell placement techniques, with emphasis on standard cell and macro placement. Five major algorithms for placement are discussed: simulated annealing, force-directed placement, min-cut placement, placement by numerical optimization, and evolution-based placement. The first two classes of algorithms owe their origin to physical laws, the third and fourth are analytical techniques, and the fifth class of algorithms is derived from biological phenomena. In each category, the basic algorithm is explained with appropriate examples. Also discussed are the different implementations done by researchers.
Implementation and computational results for the hierarchical algorithm for making sparse matrices sparser
Authors: Chang S. Frank , McCormick S. Thomas
Published: July 2002

If A is the (sparse) coefficient matrix of linear-equality constraints, for what nonsingular
T
is A = TA as sparse as possible, and how can it be efficiently computed? An efficient algorithm for this
Sparsity Problem
(SP) would be a valuable preprocessor for linearly constrained optimization problems. In a companion paper we developed a two-pass approach to solve SP called the
Hierarchical Algorithm
. In this paper we report on how we implemented the Hierarchical Algorithm into a code called HASP, and our computational experience in testing HASP on the NETLIB linear-programming problems. We found that HASP substantially outperformed a previous code for SP and that it produced a net savings in optimization time on the NETLIB problems. The results allow us to give guidelines for its use in practice.
Multiresolution stochastic hybrid shape models with fractal priors
Authors: Vemuri B. C. , Radisavljevic A.
Published: July 2002

3D shape modeling has received enormous attention in computer graphics and computer vision over the past decade. Several shape modeling techniques have been proposed in literature, some are local (distributed parameter) while others are global (lumped parameter) in terms of the parameters required to describe the shape. Hybrid models that combine both ends of this parameter spectrum have been in vogue only recently. However, they do not allow a smooth transition between the two extremes of this parameter spectrum.

We introduce a
new shape-modeling scheme
that can
transform smoothly from local to global
models or vice versa. The modeling scheme utilizes a hybrid primitive called the deformable superquadric
constructed in an orthonormal wavelet basis
. The multiresolution wavelet basis provides the power to continuously transform from local to global shape deformations and thereby allow for a continuum of shape models—from those with local to those with global shape descriptive power—to be created. The multiresolution wavelet basis allows us to generate fractal surfaces of arbitrary order that can be useful in describing natural detail.

We embed these multiresolution shape models in a probabilistic framework and use them for recovery of anatomical structures in the human brain from MRI data. A salient feature of our modeling scheme is that it can naturally allow for the incorporation of prior statistics of a rich variety of shapes. This stems from the fact that, unlike other modeling schemes, in our modeling, we require relatively few parameters to describe a large class of shapes.
A simple and efficient bus management scheme that supports continuous streams
Authors: Hosseini-Khayat Saied , Bovopoulos Andreas D.
Published: July 2002

An efficient bandwidth management and access arbitration scheme for an I/O bus in a multimedia workstation is presented. It assumes that a multimedia workstation consists of a number of processing modules which are interconnected by a packet bus. The scheme is efficient in the sense that it allows the bus to support both continuous media transfers and regular random transactions in such a way that continuous streams can meet their real-time constraints independently of random traffic, and random traffic is not delayed significantly by continuous traffic except when traffic load is very high. Implementation guidelines are provided to show that the scheme is practical. Finally, the performance of this scheme is compared with alternative solutions through simulation.
Building future medical education environments over ATM networks
Authors: Schnepf James A. , Du David H. C. , Ritenour E. Russell , Fahrmann Aaron J.
Published: July 2002

The educational requirements of our society are changing. It is no longer sufficient to obtain an education at a single point in time and be done; rather, education must be a lifelong process to allow people, particularly those in technical diciplines, to keep up with their constantly changing fields. This is especially true with medical education, as exemplified by the continued training of radiology residents. It has been difficult to provide this training to physicians and other health care practitioners who are spread over a wide geographical area and who cannot travel away from their communities for lenghty training sessions. To meet the needs of this expanding base of students, it is necessary to go beyond the traditional campus setting and bring education to the students.
Efficient checking of temporal integrity constraints using bounded history encoding
Authors: Chomicki Jan
Published: July 2002

We present an efficient implementation method for temporal integrity constraints formulated in Past Temporal Logic. Although the constraints can refer to past states of the database, their checking does not require that the entire database history be stored. Instead, every database state is extended with auxiliary relations that contain the historical information necessary for checking constraints. Auxiliary relations can be implemented as materialized relational views.
Algorithm design
Authors: Tarjan Robert E.
Published: July 2002

The quest for efficiency in computational methods yields not only fast algorithms, but also insights that lead to elegant, simple, and general problem-solving methods.
Structuring Z specifications with views
Authors: Jackson Daniel
Published: July 2002

A view is a partial specification of a program, consisting of a state space and a set of operations. A full specification is obtained by composing several views, linking them through their states (by asserting invariants across views) and through their operations (by defining external operations as combinations of operations from different views). By encouraging multiple representations of the program's state, view structuring lends clarity and terseness to the specification of operations. And by separating different aspects of functionality, it brings modularity at the grossest level of organization, so that specifications can accommodate change more gracefully. View structuring in Z is demonstrated with a few small examples. Both the features of Z that lend themselves to view structuring and those that are a hindrance are discussed.
A style analysis of C programs
Authors: Berry R E. , Meekings B A.E.
Published: July 2002

A large quantity of well-respected software is tested against a series of metrics designed to measure program lucidity, with intriguing results. Although slanted toward software written in the C language, the measures are adaptable for analyzing most high-level languages.
Storing a collection of polygons using quadtrees
Authors: Samet Hanan , Webber Robert E.
Published: July 2002

An adaptation of the quadtree data structure that represents polygonal maps (i.e., collections of polygons, possibly containing holes) is described ina manner that is also useful for the manipulation of arbitrary collections of straight line segments. The gol is to store these maps without the loss of information that results from digitization, and to obtain a worst-case execution time that is not overly sensitive to the positioning of the map. A regular decomposition variant of the region quadtree is used to organize the vertices and edges of the maps. A number of related data organizations are proposed in an iterative manner until a method is obtained that meets the stated goals. The result is termed a PM (polygonal map) quadtree and is based on a regular decomposition point space quadtree (PR quadtree) that stores additional information about the edges at its terminal nodes. Algorithms are given for inserting and deleting line segments from a PM quadtree. Use of the PM quadtree to perform point location, dynamic line insertion, and map overlay is discussed. The PM quadtree is compared conceptually to the K-structure and the layered dag with respect to typical cartographic data. An empirical comparison of the PM quadtree with other quadtree-based representations for polygonal maps is also provided.
Using nonspeech sounds to provide navigation cues
Authors: Brewster Stephen A.
Published: July 2002

This article describes 3 experiments that investigate the possibiity of using structured nonspeech audio messages called
earcons
to provide navigational cues in a menu hierarchy. A hierarchy of 27 nodes and 4 levels was created with an earcon for each node. Rules were defined for the creation of hierarchical earcons at each node. Participants had to identify their location in the hierarchy by listening to an earcon. Results of the first experiment showed that participants could identify their location with 81.5% accuracy, indicating that earcons were a powerful method of communicating hierarchy information. One proposed use for such navigation cues is in telephone-based interfaces (TBIs) where navigation is a problem. The first experiment did not address the particular problems of earcons in TBIs such as “does the lower quality of sound over the telephone lower recall rates,” “can users remember earcons over a period of time.” and “what effect does training type have on recall?” An experiment was conducted and results showed that sound quality did lower the recall of earcons. However; redesign of the earcons overcame this problem with 73% recalled correctly. Participants could still recall earcons at this level after a week had passed. Training type also affected recall. With personal training participants recalled 73% of the earcons, but with purely textual training results were significantly lower. These results show that earcons can provide good navigation cues for TBIs. The final experiment used compound, rather than hierarchical earcons to represent the hierarchy from the first experiment. Results showed that with sounds constructed in this way participants could recall 97% of the earcons. These experiments have developed our general understanding of earcons. A hierarchy three times larger than any previously created was tested, and this was also the first test of the recall of earcons over time.
Recipes for adjoint code construction
Authors: Giering Ralf , Kaminski Thomas
Published: July 2002

Adjoint models are increasingly being developed for use in meteorology and oceanography. Typical applications are data assimilation, model tuning, sensitivity analysis, and determination of singular vectors. The adjoint model computes the gradient of a cost function with respect to control variables. Generation of adjoint code may be seen as the special case of differentiation of algorithms in reverse mode, where the dependent function is a scalar. The described method for adjoint code generation is based on a few basic principles, which permits the establishment of simple construction rules for adjoint statements and complete adjoint subprograms. These rules are presented and illustrated with some examples. Conflicts that occur due to loops and redefinition of variables are also discussed. Direct coding of the adjoint of a more sophisticated model is extremely time consuming and subject to errors. Hence, automatic generation of adjoint code represents a distinct advantage. An implementation of the method, described in this article, is the tangent linear and adjoint model compiler (TAMC).
Design-time simulation of a large-scale, distributed object system
Authors: Frølund Svend , Garg Pankaj
Published: July 2002

We present a case study in using simulation at design time to predict the performance and scalability properties of a large-scale distributed object system. The system, called Consul, is a network management system designing to support hundreds of operators managing millions of network devices. It is essential that a system such as Consul be designed with performance and scalability in mind, but due to Consul's complexity and scale, it is hard to reason about performance and scalability using ad hoc techniques. We built a simulation of Consul's design to guide the design process by enabling performanace and scalability analysis of various design alternatives. A major challenge in doing design-time simulation is that many parameters for the simulation are based on estimates rather than measurements. We developed analysis methods that derive conclusions that are valid in the presence of estimation errors. In this article, we describe our scalability analysis method for design simulations of distributed object systems. The main idea is to use relative and comparative reasoning to analyze design alternatives and compare transaction behaviors. We demonstrate the analysis approach by describing its application to Consul.
Parallel algorithms for the execution of relational database operations
Authors: Bitton Dina , Boral Haran , DeWitt David J. , Wilkinson W. Kevin
Published: July 2002

This paper presents and analyzes algorithms for parallel processing of relational database operations in a general multiprocessor framework. To analyze alternative algorithms, we introduce an analysis methodology which incorporates I/O, CPU, and message costs and which can be adjusted to fit different multiprocessor architectures. Algorithms are presented and analyzed for sorting, projection, and join operations. While some of these algorithms have been presented and analyzed previously, we have generalized each in order to handle the case where the number of pages is significantly larger than the number of processors. In addition, we present and analyze algorithms for the parallel execution of update and aggregate operations.
A foundation of CODD's relational maybe-operations
Authors: Biskup Joachim
Published: July 2002

Database relations which possibly contain maybe-tuples and null values of type “value at present unknown” are studied. Maybe-tuples and null values are formally interpreted by our notion of
representation
, which uses classical notions of predicate logic, elaborates Codd's proposal of maybe-tuples, and adopts Reiter's concept of a closed world. Precise notions of
information content
and
redundancy
, associated with our notion of representation, are investigated.
Extensions of the relational algebra
to relations with maybe-tuples and null values are proposed. Our extensions are essentially Codd's, with some modifications. It is proved that these extensions have natural properties which are formally stated as being
adequate
and
restricted
.

By the treatment of difference and division, our formal framework can be used even for operations that require “negative information.” Finally, extensions of
update operations
are discussed.
Serial Correlation in the Generation of Pseudo-Random Numbers
Authors: Coveyou R. R.
Published: July 2002

Many practiced and proposed methods for the generation of pseudo-random numbers for use in Monte Carlo calculation can be expressed in the following way: One chooses an integer
P
, the base; an integer λ, the multiplier, prime to
P
; and an integer
μ
, the increment, less than
P
(
μ
is frequently, but not always, zero).
Unrecognizable Sets of Numbers
Authors: Minsky Marvin , Papert Seymour
Published: July 2002

When is a set
A
of positive integers, represented as binary numbers, “regular” in the sense that it is a set of sequences that can be recognized by a finite-state machine? Let π

A

(
n
) be the number of members of
A
less than the integer
n
. It is shown that the asymptotic behavior of π
A
(
n
) is subject to severe restraints if
A
is regular. These constraints are violated by many important natural numerical sets whose distribution functions can be calculated, at least asymptotically. These include the set
P
of prime numbers for which π

P

(
n
) @@@@
n
/log
n
for large
n
, the set of integers
A
(
k
) of the form

n
k

for which π

A
(
k
)

n
) @@@@

n
P/k

, and many others. The technique cannot, however, yield a decision procedure for regularity since for every infinite regular set
A
there is a nonregular set
A′
for which | π

A

(
n
) — π

A′

(
n
) | ≤ 1, so that the asymptotic behaviors of the two distribution functions are essentially identical.
PRIME—toward process-integrated modeling environments
Authors: Pohl Klaus , Weidenhaupt Klaus , Dömges Ralf , Haumer Peter , Jarke Matthias , Klamma Ralf
Published: July 2002

Research in process-centered environments (PCEs) has focused on project management support and has neglected method guidance for the engineers performing the (software) engineering process. It has been dominated by the search for suitable process-modeling languages and enactment mechanisms. The consequences of process orientation on the computer-based engineering environments, i.e., the interactive tools used during process performance, have been studied much less. In this article, we present the PRIME (Process Integrated Modeling Environments) framework which empowers method guidance through process-integrated tools. In contrast to the tools of PCEs, the process-integrated tools of PRIME adjust their behavior according to the current process situation and the method definitions. Process integration of PRIME tools is achieved through (1) the definition of tool models; (2) the integration of the tool models and the method definitions; (3) the interpretation of the integrated environment model by the tools, the process-aware control integration mechanism, and the enactment mechanism; and (4) the synchronization of the tools and the enactment mechanism based on a comprehensive interaction protocol. We sketch the implementation of PRIME as a reusable implementation framework which facilitates the realization of process-integrated tools as well as the process integration of external tools. We define a six-step procedure for building a PRIME-based process-integrated environment (PIE) and illustrate how PRIME facilitates change integration on an easy-to-adapt modeling level.
Xor-trees for efficient anonymous multicast and reception
Authors: Dolev Shlomi , Ostrobsky Rafail
Published: July 2002

We examine the problem of efficient anonymous multicast and reception in general communication networks. We present algorithms that achieve anonymous communication, are protected against traffic analysis, and require
O
(1) amortized communication complexity on each link and low computational comlexity. The algorithms support sender anonymity, receiver(s) anonymity, or sender-receiver anonymity.
Communicating sequential processes
Authors: Hoare C. A. R.
Published: July 2002

This paper suggests that input and output are basic primitives of programming and that parallel composition of communicating sequential processes is a fundamental program structuring method. When combined with a development of Dijkstra's guarded command, these concepts are surprisingly versatile. Their use is illustrated by sample solutions of a variety of familiar programming exercises.
Bresenham's algorithm with Grey scale
Authors: Pitteway M. L. V. , Watkinson D. J.
Published: July 2002

The control parameter in Bresenham's algorithm, when interpreted as a measure of distance from a straight line boundary, gives a weighted average of the intensities on each side of the line. This can be used to produce an aesthetically pleasing visual effect with modern display devices.
Characteristics of application software maintenance
Authors: Lientz B. P. , Swanson E. B. , Tompkins G. E.
Published: July 2002

Maintenance and enhancement of application software consume a major portion of the total life cycle cost of a system. Rough estimates of the total systems and programming resources consumed range as high as 75-80 percent in each category. However, the area has been given little attention in the literature. To analyze the problems in this area a questionnaire was developed and pretested. It was then submitted to 120 organizations. Respondents totaled 69. Responses were analyzed with the SPSS statistical package. The results of the analysis indicate that: (1) maintenance and enhancement do consume much of the total resources of systems and programming groups; (2) maintenance and enhancement tend to be viewed by management as at least somewhat more important than new application software development; (3) in maintenance and enhancement, problems of a management orientation tend to be more significant than those of a technical orientation; and (4) user demands for enhancements and extension constitute the most important management problem area.