bluuebunny/crossref_metadata_2025 huggingface dataset:
CLUSTER PERIODIC SOLUTIONS IN GLOBALLY COUPLED MAPS
Authors: AFRAIMOVICH V. S. , GELOVER-SANTIAGO A. L. , LIMA R.
Published: July 2002

Globally coupled maps have been extensively studied in the last years. In a previous paper, we analyzed the phenomenon of synchronization for a family of globally coupled maps. In this paper we will study periodic cluster solutions. We rigorously prove the existence of period-two 2-cluster solutions in some regions of parameters and analytically and numerically describe their stability.
THE STATIC BIFURCATION DIAGRAM FOR THE GRAY–SCOTT MODEL
Authors: CURTU RODICA
Published: July 2002

The singularity theorem is used to derive the deformations of the static bifurcation diagram of the Gray–Scott model.
SIGNAL DROPOUT RECONSTRUCTION IN COMMUNICATING WITH CHAOS
Authors: VALLADARES D. L. , BOCCALETTI S. , MANCINI H. , GREBOGI C.
Published: July 2002

A chaotic system can be guided by tiny perturbations to follow a previously chosen path in phase space carrying a desired sequence of binary symbols. We discuss how to exploit redundancy and flexibility of the chaotic carriers to reconstruct possible signal dropouts incurred in the communication channel, even in the case in which the receiver has no information about the chaotic system on which the message is coded. A crucial issue is whether the natural evolution of the selected chaotic system displays prohibited sequences. We show how to optimize the message recovering process, and how this last one is strictly related to the natural properties of the chaotic sources.
RECONSTRUCTION OF INFORMATION-BEARING CHAOTIC SIGNALS IN ADDITIVE WHITE GAUSSIAN NOISE: PERFORMANCE ANALYSIS AND EVALUATION
Authors: MARIÑO INÉS P. , GREBOGI CELSO , ROSA EPAMINONDAS
Published: July 2002

Chaotic signals can be used as carriers of information in communication systems since they own some redundancy that can be exploited to reconstruct missing or distorted parts of a waveform that has been transmitted through a communication channel. In this paper, we extend our previous results for the ideal noise free channel [Mariño et al., 1999] to a more general situation where additive white Gaussian noise corrupts the information-bearing chaotic signal.
EMBEDDING THEOREMS FOR GROUPS PRESENTED VIA PARTIAL AUTOMORPHISMS: A GENERALIZATION OF SEMIDIRECT PRODUCTS AND HNN EXTENSIONS
Authors: YAMAMURA AKIHIRO
Published: July 2002

We examine a certain embedding problem for groups that have a presentation described by partial automorphisms. Semidirect products and HNN extensions have such a presentation. The embedding problem is closely related to systems of partial automorphisms, which are formalized by the concept of inverse semigroups. A necessary and sufficient condition for a group to be embedded in a certain sense is obtained by geometric methods using van Kampen diagrams.
THE WHITEHEAD ASPHERICITY CONJECTURE AND PERIODIC GROUPS
Authors: IVANOV S. V.
Published: July 2002

The Whitehead asphericity conjecture claims that if [Formula: see text] is an aspherical group presentation, then for every [Formula: see text] the subpresentation [Formula: see text] is also aspherical. This conjecture is generalized for presentations of groups with periodic elements by introducing almost aspherical presentations (for example, every one-relator group is almost aspherical). It is proven that the generalized Whitehead asphericity conjecture (which claims that every subpresentation of an almost aspherical presentation is also almost aspherical) is equivalent to the original Whitehead conjecture. It is also proven that the generalized Whitehead asphericity conjecture holds for Ol'shanskii's presentations of free Burnside groups of large odd exponent, presentations of Tarski monsters and others.
Extremal Values of the Basic Invariants of Plane Curves
Authors: Yu Jianming , Zhou Jianyi , Pan Jianzhong
Published: July 2002

In [A2] V.I. Arnold introduced three basic invariants St, J+ and J- of plane curves and proposed some interesting conjectures concerning the extremal value of these invariants on a given set of curves. Partial answers have been obtained by O. Viro and A. N. Shumakovich. We give explicit formulas for these extremal values of sets of plane curves with fixed number of double points and of Whitney index and we determine on which curves these extremal values are attained (Theorems 3-6). Our arguments are based on understanding of the fine structures of generic curves and some surgery operations on curves.
GENERALIZED CONWAY POLYNOMIALS
Authors: HSIEH CHUN-CHUNG
Published: July 2002

We derive a generalization of the Conway polynomial in knot theory. It turns out that the "classic" Conway polynomial is the zero-th member of our "generalized" Conway polynomials.
ROTATING GROSS–PERRY–SORKIN DILATONS FROM FIVE-DIMENSIONAL KALUZA–KLEIN THEORY
Authors: BECERRIL RICARDO , RIOS MARIBEL , MATOS TONATIUII
Published: July 2002

From the known Gross–Perry–Sorkin solitonic monopole solution, its corresponding rotating solution is constructed. We discuss some its properties. We also present a rotating magnetic dipole which has an electric dipole induced by rotation.
RELATIVISTIC ELECTRONS ON A ROTATING SPHERICAL MAGNETIC DIPOLE: SURFACE ORBITALS
Authors: GELB JAMES M. , GOPINATH KAUNDINYA S. , KENNEDY DALLAS C.
Published: July 2002

The semiclassical orbitals of a relativistic electron on a rotating sphere threaded by an intense magnetic dipole field are examined. Several physically distinct regimes emerge, depending on the relative sizes of the mass, total energy, canonical azimuthal angular momentum, and magnetic field strength. Magnetic flux enclosed by orbits is quantized very close to the poles, suggesting a quantum Hall-like state. Application of this system to neutron star surfaces is outlined.
ON THE ADIABATICITY OF ACOUSTIC PROPAGATION THROUGH NONGRADUAL OCEAN STRUCTURES
Authors: SHANG E. C. , WANG Y. Y. , GAO T. F.
Published: July 2002

To assess the adiabaticity of sound propagation in the ocean is very important for acoustic field calculating (forward problem) and tomographic retrieving(inverse problem). Most of the criterion in the literature is too restrictive, specially for the nongradual ocean structures. A new criterion of adiabaticity is suggested in this paper. It works for nongradual ocean structures such as front and internal solitary waves in shallow-water.
PHASE DIAGRAM OF ADSORBATE-INDUCED ROW-TYPE ALIGNMENTS
Authors: KANG M. , YASUTANI K. , KABURAGI M.
Published: July 2002

The phase diagram of adsorbate-induced row-type alignments, such as missing-row reconstructions induced by adsorbate atoms on the FCC(110) surface, is calculated by the Blume–Emmery–Griffiths (BEG) model. In the model, we introduce adatom–adatom and dipole–dipole interactions between nearest-neighbor (NN) and next-nearest-neighbor (NNN) rows. The calculation of the temperature versus adatom chemical potential phase diagram is performed using mean-field approximation. It is indicated that when NN and NNN interactions are competitive, there appear either dipole or coverage modulated (incommensurate) phases at high temperatures for a wide regime of the interactions.
(2×1) OXYGEN SUPERSTRUCTURE ON Cu(210) SURFACE STUDIED BY QUANTITATIVE LEED ANALYSIS AND STM
Authors: TAN K. C. , GUO Y. P. , WEE A. T. S. , HUAN C. H. A.
Published: July 2002

Adsorption of oxygen at elevated temperatures on Cu(210) surface leads to the formation of a (2×1) superstructure similar to that found on Cu(110). Previous STM work done on this system showed diperiodic Cu–O rows running along the [001] direction. In this work, low energy electron diffraction (LEED) experiments were done on the Cu(210)-(2×1)O surface structure. Ten diffracted beams at normal incidence were used for multiple scattering calculations using the Barberi/Van Hove symmetrized tensor LEED code. Four models were optimized for the calculations and the best fit to experiment is found to be the model with alternate missing –Cu–0– rows and oxygen atom occupying the long bridge site. Oxygen to first and second Cu nearest neighbors are optimized to 1.81 and 1.92 Å respectively and the position of the oxygen atom above the (110) plane have been optimized to about 0.12 Å.
THE DISTRIBUTION OF RETURNS OF STOCK PRICES
Authors: AMARAL LUÍS A. N. , PLEROU VASILIKI , GOPIKRISHNAN PARAMESWARAN , MEYER MARTIN , STANLEY H. EUGENE
Published: July 2002

We perform a phenomenological study of stock price fluctuations of individual companies. We systematically analyze two different databases covering securities from the three major US stock markets. We consider (i) the trades and quotes (TAQ) database, for which we analyze 40 million records for 1000 US companies for the 2-year period 1994–95, and (ii) the Center for Research and Security Prices (CRSP) database, for which we analyze 35 million daily records for approximately 16,000 companies in the 35-year period 1962–96. We study the probability distribution of returns over varying time scales — from 5 min up to 4 years. For time scales from 5 min up to approximately 16 days, we find that the tails of the distributions can be well described by a power-law decay, characterized by an exponent α ≈ 3 — well outside the stable Lévy regime 0 < α < 2. For time scales greater than 16 days, we observe results consistent with a slow convergence to Gaussian behavior.
THE RIESZ REPRESENTATION THEOREM ON INFINITE DIMENSIONAL SPACES AND ITS APPLICATIONS
Authors: LEE YUH-JIA , SHIH CHEN-YUH
Published: July 2002

Let H be a real separable Hilbert space and let E⊂H be a nuclear space with the chain {Em: m=1,2,…} of Hilbert spaces such that E = ∩m∈ℕEm. Let E* and E-m denote the dual spaces of E and Em, respectively. For γ > 0, let [Formula: see text] be the collection of complex-valued continuous functions f defined on E* such that [Formula: see text] is finite for every m. Then [Formula: see text] is a complete countably normed space equipping with the family {‖·‖m,γ : m = 1,2,…} of norms. Using a probabilistic approach, it is shown that every continuous linear functional T on [Formula: see text] can be represented uniquely by a complex Borel measure νT satisfying certain exponential integrability condition. The results generalize an infinite dimensional Riesz representation theorem given previously by the first author for the case γ = 2. As applications, we establish a Weierstrass approximation theorem on E* for γ≥1 and show that the space [Formula: see text] spanned by the class { exp [i(x,ξ)] : ξ ∈ E} is dense in [Formula: see text] for γ>0. In the course of the proof we give sufficient conditions for a function space on which every positive functional can be represented by a Borel measure on E*.
ON MULTI-COLOR PARTITIONS AND THE GENERALIZED ROGERS–RAMANUJAN IDENTITIES
Authors: JING NAIHUAN , MISRA KAILASH C. , SAVAGE CARLA D.
Published: July 2002

Basil Gordon, in the sixties, and George Andrews, in the seventies, generalized the Rogers–Ramanujan identities to higher moduli. These identities arise in many areas of mathematics and mathematical physics. One of these areas is representation theory of infinite dimensional Lie algebras, where various known interpretations of these identities have led to interesting applications. Motivated by their connections with Lie algebra representation theory, we give a new interpretation of a sum related to generalized Rogers–Ramanujan identities in terms of multi-color partitions.
CRITICAL LOADS OF SQUARE PLATES UNDER DIFFERENT INPLANE LOAD CONFIGURATIONS ON OPPOSITE EDGES
Authors: LEE S. G. , KIM S. C. , SONG J. G.
Published: July 2002

The elastic critical load coefficients of square plates, under different inplane load configurations on opposite plate edges, are determined and the results compared. The stability analysis was performed by a finite element method that was developed by the authors. The parameters considered in the analysis are the Kinney's fixity factor, and the width factor of the patch load. It was found that the coefficients of the critical loads increase with increasing values of fixity and width factors. The opposite tendency is that a plate under a patch loaded towards the two corners of an edge is more stable than a plate loaded concentrically at the center of the edge.
NUMERICAL ANALYSIS OF THE NON-LINEAR DYNAMIC BEHAVIOUR OF SUSPENDED CABLES UNDER TURBULENT WIND EXCITATION
Authors: MARTINELLI L. , PEROTTI F.
Published: July 2002

In this paper, a numerical procedure is presented for the dynamic analysis of elastic cables subjected to turbulent wind excitation in quasi-steady conditions. The proposed methodology, which takes geometrical and aerodynamic non-linearities into account, is based on artificial simulation of turbulence, on finite-element modeling of the cables and on a step-by-step implicit procedure for the integration of the dynamic equilibrium equations. As a first application, the dynamic behaviour of a cable in 1 : 2 internal resonance conditions is studied, focusing on some aspects of the influence of wind turbulence on galloping oscillations.
LARGE-SCALE MINING, DISCOVERY AND VISUALIZATION OF WWW USER CLICKPATHS
Authors: KITTS BRENDAN , HETHERINGTON-YOUNG KEVIN , VRIEZE MARTIN
Published: July 2002

Analysis of user clickstreams on the World Wide Web is made challenging by the volume of data and the difficulty of visualizing millions of different navigation paths. We present a method for identifying user clickpaths which scales well on large amounts of data, and provides an intuitive and insightful visual representation of user activity. Our technique borrows from the data mining literature on association rules and the computer graphics literature on graph layout optimization. The method is demonstrated with data from two commercial sources and paints a fascinating picture of web activity.
THE BIOMECHANICS OF INTRAMEDULLARY NAILING: A PROTOCOL FOR LABORATORY TESTING
Authors: COLOMBO MAURIZIO , RAIMONDI MANUELA T. , VILLA TOMASO , QUAGLINI VIRGINIO , PIETRABISSA RICCARDO
Published: July 2002

In this work, a testing protocol has been set up, in order to quantify the load-sharing imposed near the fracture site by an interlocking-type intramedullary nail. A simulated single-leg stance has been applied to a composite fiberglass femur in three different configurations simulating: an intact femur, a fractured nailed femur and a fully healed nailed femur. The repeatability of the measurements and the influence of ilio-tibial band muscle force have been investigated. The tested nail proved to share with the femoral shaft an amount of the total applied load ranging from 50% immediately after the nailing to 80% at full healing.
FORTRAN subroutines for general Toeplitz systems
Authors: Hansen Per Christian , Chan Tony F.
Published: July 2002

This paper presents FORTRAN 77 implementations of the lookahead Levinson algorithm of Chan and Hansen [7, 8] for solving symmetric indefinite and general Toeplitz systems. The algorithms are numerically stable for all Toeplitz matrices that do not have manyconsecutiveill-conditioned leading principal submatrices, and also produce estimates of the algorithm and matrix condition numbers. In contrast, the classical Levinson algorithm is only guaranteed to be numerically stable for symmetric positive definite Toeplitz matrices, and no condition estimate is produced.
A general framework for bidirectional translation between abstract and pictorial data
Authors: Matsuoka Satoshi , Takahashi Shin , Kamada Tomihisa , Yonezawa Akinori
Published: July 2002

The merits of direct manipulation are now widely recognized. However, direct manipulation interfaces incur high cost in their creation. To cope with this problem, we present a model of bidirectional translation between pictures and abstract application data, and a prototype system, TRIP2, based on this model. Using this model, general mapping from abstract data to pictures and from pictures to abstract data is realized merely by giving declarative mapping rules, allowing fast and easy creation of direct manipulation interfaces. We apply the prototype system to the generation of the interfaces for kinship diagrams, Graph Editors, E-R diagrams, and an Othello game.
Algorithm 723: Fresnel integrals
Authors: van Snyder W.
Published: July 2002

An implementation of approximations for Fresnel integrals and associated functions is described. The approximations were originally developed by W. J. Cody, but a Fortran implementation using them has not previously been published.
The weakest failure detector for solving consensus
Authors: Chandra Tushar Deepak , Hadzilacos Vassos , Toueg Sam
Published: July 2002

We determine what information about failures is necessary and sufficient to solve Consensus in asynchronous distributed systems subject to crash failures. In Chandra and Toueg [1996], it is shown thatW, a failure detector that provides surprisingly little information about which processes have crashed, is sufficient to solve Consensus in asynchronous systems with a majority of correct processes. In this paper, we prove that to solve Consensus, any failure detector has to provide at least as much information as W. Thus, W is indeed the weakest failure detector for solving Consensus in asynchronous systems with a majority of correct processes.
Programming languages for mobile code
Authors: Thorn Tommy
Published: July 2002

Sun's announcement of the programming language Java more that anything popularized the notion of mobile code, that is, programs traveling on a heterogeneous network and automatically executing upon arrival at the destination. We describe several classes of mobile code and extract their common characteristics, where security proves to be one of the major concerns. With these characteristics as reference points, we examine six representative languages proposed for mobile code. The conclusion of this study leads to our recommendations for future work, illustrated by examples of ongoing research.
Code placement techniques for cache miss rate reduction
Authors: Tomiyama Hiroyuki , Yasuura Hiroto
Published: July 2002

In the design of embedded systems with cache memories, it is important to minimize the cache miss rates to reduce power consumption of the systems as well as improve the performance. In this article, we propose two code placement methods ( a simplified method and a refined one) to reduce miss rates of instruction caches. We first define a simplified code placement problem without an attempt to minimize the code size. The problem is formulated as an integer linear programming (ILP) problem, by which an optimal placement can be found. Experimental results show that the simplified method reduces cache misses by an average of 30% (max. 77%). However, the code size obtained by the simplified method tends to be large, which inevitably leads to a larger memory size. In order to overcome this limitation, we further propose a refined code placement method in which the code size provided by the system designers must be satisfied. The effectiveness of the refined method is also demonstrated.
A robust framework for content-based retrieval by spatial similarity in image databases
Authors: El-Kwae Essam A. , Kabuka Mansur R.
Published: July 2002

A framework for retrieving images by spatial similarity (FRISS) in ima ge databases is presented. In this framework, a robust retrieval by spatial similarity (RSS) algorithm is defined as one that incorporates both directional and topological spatial constraints, retrieves similar images, and recognized images even after they undergo translation, scaling, rotation (both perfect and multiple), or any arbitrary combination of transformatioins. The FRISS framework is discussed and used as a base for comparing various existing RSS algorithms. Analysis shows that none of them satisfies all the FRISS specifications. An algorithm,

SIM
dtc

, is then presented.

SIM
dtc

introduces the concept of a
rotation correction angle
(RCA) to align objects in one image spatially closer to matching objects in another image for more accurate similarity assessment. Similarity between two images is a function of the number of common objects between them and the closeness of directional and topological spatial relationships between object pairs in both images. The

SIM
dtc

retrieval is invariant under translation, scaling, and perfect rotation, and the algorithm is able to rank multiple rotation variants. The algorithm was tested using synthetic images and the TESSA image database. Analysis shows the robustness of the

SIM
dtc

algorithm over current algorithms.
Code generation of nested loops for DSP processors with heterogeneous registers and structural pipelining
Authors: Cheng Wei-Kai , Lin Youn-Long
Published: July 2002

We propose a microcode-optimizing method targeting a programmable DSP processor. Efficient generation of microcodes is essential to better utilize the computation power of a DSP processor. Since most state-of-the-art DSP processors feature some sort of irregular architectures and most DSP applications have nested loop constructs, their code generation is a nontrivial task. In this paper, we consider two features frequently found in contemporary DSP processors — structural pipelining and heterogeneous registers. We propose a code generator that performs instruction scheduling and register allocation simultaneously. The proposed approach has been implemented and evaluated using a set of benchmark core algorithms. Simulation of the generated codes targeted towards the TI TMS320C40 DSP processor shows that our system is indeed more effective compared with a commercial optimizing DSP compiler.
The design and implementation of INGRES
Authors: Stonebraker Michael , Held Gerald , Wong Eugene , Kreps Peter
Published: July 2002

The currently operational (March 1976) version of the INGRES database management system is described. This multiuser system gives a relational view of data, supports two high level nonprocedural data sublanguages, and runs as a collection of user processes on top of the UNIX operating system for Digital Equipment Corporation PDP 11/40, 11/45, and 11/70 computers. Emphasis is on the design decisions and tradeoffs related to (1) structuring the system into processes, (2) embedding one command language in a general purpose programming language, (3) the algorithms implemented to process interactions, (4) the access methods implemented, (5) the concurrency and recovery control currently provided, and (6) the data structures used for system catalogs and the role of the database administrator.

Also discussed are (1) support for integrity constraints (which is only partly operational), (2) the not yet supported features concerning views and protection, and (3) future plans concerning the system.
A Modification of Filon's Method of Numerical Integration
Authors: Flinn E. A.
Published: July 2002

Filon's method of numerical integration was developed to deal with integrals of the form
I
= ∫

B

A

ƒ(
x
) cos
px dx
(1)
A Convergent Algorithm for Solving Polynomial Algorithms
Authors: Moore J. B.
Published: July 2002

The method of steepest descent is applied in a convergent procedure to determine the zeros of polynomials having either real or complex coefficients. By expressing the polynomials in terms of the Siljak functions, the methods are readily programmed on a digital computer. The significance of the procedures is that their application is straightforward, and not only is convergence rapid in the region of a zero but convergence is guaranteed independent of the initial values.
Nomadic radio
Authors: Sawhney Nitin , Schmandt Chris
Published: July 2002

Mobile workers need seamless access to communication and information services while on the move. However, current solutions overwhelm users with intrusive interfaces and ambiguous notifications. This article discusses the interaction techniques developed for Nomadic Radio, a wearable computing platform for managing voice and text-based messages in a nomadic environment. Nomadic Radio employs an auditory user interface, which synchronizes speech recognition, speech synthesis, nonspeech audio, and spatial presentation of digital audio, for navigating among messages as well as asynchonous notific ation of nely arrived messages. Emphasis is placed on an auditory modality as Nomadic Radio is designed to be used while performing other tasks in a user's everyday environment; a range of auditory cues provides peripheral awareness of incoming messages. Notification is adaptive and cntext sensitive; messages are presented as more or less obtrsive based on importance inferred from content filtering, whether the user is engaged in conversation and his or her own recent responses to prior messages. Auditory notifications are dynamically scaled from ambient sound through recorded voice cues up to message summaries. Iterative design and a preliminary user evaluation suggest that audio is an appropriate medium for mobile messaging, but that care must be taken to minimally intrude on the wearer's social and physical environment.
A real-time garbage collector based on the lifetimes of objects
Authors: Lieberman Henry , Hewitt Carl
Published: July 2002

In previous heap storage systems, the cost of creating objects and garbage collection is independent of the lifetime of the object. Since objects with short lifetimes account for a large portion of storage use, it is worth optimizing a garbage collector to reclaim storage for these objects more quickly. The garbage collector should spend proportionately less effort reclaiming objects with longer lifetimes. We present a garbage collection algorithm that (1) makes storage for short-lived objects cheaper than storage for long-lived objects, (2) that operates in real time—object creation and access times are bounded, (3) increases locality of reference, for better virtual memory performance, (4) works well with multiple processors and a large address space.
A selective traversal algorithm for binary search trees
Authors: Driscoll James R. , Lien Y. Edmund
Published: July 2002

The problem of selecting data items from a binary search tree according to a list of range conditions is considered. The process of visiting a minimal number of nodes to retrieve data satisfying the range conditions is called selective traversal. Presented in this paper is an algorithm for selective traversal which uses a tag field for each node in the tree. The algorithm is particularly useful and efficient when examination of data is more time consuming than examination of a tag field.
Analyses of deterministic parsing algorithms
Authors: Cohen Jacques , Roth Martin S.
Published: July 2002

This paper describes an approach for determining the minimum, maximum, and average times to parse sentences acceptable by a deterministic parser. These quantities are presented in the form of symbolic formulas, called time-formulas. The variables in these formulas represent not only the length of the input string but also the time to perform elementary operations such as pushing, popping, subscripting, iterating, etc. By binding to the variables actual numerical values corresponding to a given compiler-machine configuration, one can determine the execution time for that configuration. Time-formulas are derived by examining the grammar rules and the program representing the algorithm one wishes to analyze. The approach is described by using a specific grammar that defines simple arithmetic expressions. Two deterministic parsers are analyzed: a top-down recursive descent LL(1) parser, and a bottom-up SLR(1) parser. The paper provides estimates for the relative efficiencies of the two parsers. The estimates applicable to a specific machine, the PDP-10, are presented and substantiated by benchmarks. Finally, the paper illustrates the proposed approach by applying it to the analyses of parsers for a simple programming language.
Specifying queries as relational expressions
Authors: Boyce Raymond F. , Chamberlin Donald D. , King W. Frank , Hammer Michael M.
Published: July 2002

This paper presents a data sublanguage called SQUARE, intended for use in ad hoc, interactive problem solving by non-computer specialists. SQUARE is based on the relational model of data, and is shown to be relationally complete; however, it avoids the quantifiers and bound variables required by languages based on the relational calculus. Facilities for query, insertion, deletion, and update on tabular data bases are described. A syntax is given, and suggestions are made for alternative syntaxes, including a syntax based on English key words for users with limited mathematical background.
Introducing computing to smaller colleges and universities—a progress report
Authors: Parker Louis T. , Gallie Thomas M. , Brooks Frederick P. , Ferrell James K.
Published: July 2002

By technical means that are now routine, computer service for smaller colleges and universities can be provided by remote terminals of a central facility. Access, however, is not enough—effective organizational and educational methodology for introducing computing at such institutions must also be developed. The experience of two years with a statewide network involving 41 institutions is discussed. Lessons include the importance of a separate organization representing the small colleges, the necessity for on-campus training for the institutions, the need for some special programming and documentation to support such users, and the development of curriculum by evolutionary means.
The predictive analyzer and a path elimination technique
Authors: Kuno Susumu
Published: July 2002

Some of the characteristic features of a predictive analyzer, a system of syntactic analysis now operational at Harvard on an IBM 7094, are delineated. The advantages and disadvantages of the system are discussed in comparison to those of an immediate constituent analyzer, developed at the RAND Corporation with Robinson's English grammar. In addition, a new technique is described for repetitive path elimination for a predictive analyzer, which can now claim efficiency both in processing time and core storage requirement.
Finding zeros of a polynomial by the Q-D algorithm
Authors: Henrici P. , Watkins Bruce O.
Published: July 2002

A method which finds simultaneously all the zeros of a polynomial, developed by H. Rutishauser, has been tested on a number of polynomials with real coefficients. This slowly converging method (the Quotient-Difference (Q-D) algorithm) provides starting values for a Newton or a Bairstow algorithm for more rapid convergence.

Necessary and sufficient conditions for the existence of the Q-D scheme are not completely known; however, failure may occur when zeros have equal, or nearly equal magnitudes. Success was achieved, in most of the cases tried, with the failures usually traceable to the equal magnitude difficulty. In some cases, computer roundoff may result in errors which spoil the scheme. Even if the Q-D algorithm does not give all the zeros, it will usually find a majority of them.
Disk cache—miss ratio analysis and design considerations
Authors: Smith Alan J.
Published: July 2002

The current trend of computer system technology is toward CPUs with rapidly increasing processing power and toward disk drives of rapidly increasing density, but with disk performance increasing very slowly if at all. The implication of these trends is that at some point the processing power of computer systems will be limited by the throughput of the input/output (I/O) system.

A solution to this problem, which is described and evaluated in this paper, is
disk cache
. The idea is to buffer recently used portions of the disk address space in electronic storage. Empirically, it is shown that a large (e.g., 80-90 percent) fraction of all I/O requests are captured by a cache of an 8-Mbyte order-of-magnitude size for our workload sample. This paper considers a number of design parameters for such a cache (called cache disk or disk cache), including those that can be examined experimentally (cache location, cache size, migration algorithms, block sizes, etc.) and others (access time, bandwidth, multipathing, technology, consistency, error recovery, etc.) for which we have no relevant data or experiments. Consideration is given to both caches located in the I/O system, as with the storage controller, and those located in the CPU main memory. Experimental results are based on extensive trace-driven simulations using traces taken from three large IBM or IBM-compatible mainframe data processing installations. We find that disk cache is a powerful means of extending the performance limits of high-end computer systems.
A decomposable algorithm for contour surface display generation
Authors: Zyda Michael J.
Published: July 2002

We present a study of a highly decomposable algorithm useful for the parallel generation of a contour surface display. The core component of this algorithm is a two-dimensional contouring algorithm that operates on a single 2 x 2 subgrid of a larger grid. An intuitive procedure for the operations used to generate the contour lines for a subgrid is developed. A data structure, the contouring tree, is introduced as the basis of a new algorithm for generating the contour lines for the subgrid. The construction of the contouring tree is detailed. Space requirements for the contouring tree algorithm are described for particular implementations.
A global optimization algorithm using stochastic differential equations
Authors: Aluffi-Pentini Filippo , Parisi Valerio , Zirilli Francesco
Published: July 2002

SIGMA is a set of FORTRAN subprograms for solving the global optimization problem, which implements a method founded on the numerical solution of a Cauchy problem for a stochastic differential equation inspired by statistical mechanics.

This paper gives a detailed description of the method as implemented in SIGMA and reports the results obtained by SIGMA attacking, on two different computers, a set of 37 test problems which were proposed elsewhere by the present authors to test global optimization software.

The main conclusion is that SIGMA performs very well, solving 35 of the problems, including some very hard ones.

Unfortunately, the limited results available to us at present do not appear sufficient to enable a conclusive comparison with other global optimization methods.
Collaborative Virtual Environments for Analysis and Decision Support
Authors: Maybury Mark
Published: July 2002

Creating a productive collaborative environment requires a delicate balance of technology, knowledge, and trust.
Intelligent agents and financial risk monitoring systems
Authors: Wang Huaiqing , Mylopoulos John , Liao Stephen
Published: July 2002

A society of intelligent agents can work together to monitor financial transactions and yield important information regarding potential financial calamities.
Organizational power and the information services department: a reexamination
Authors: Saunders Carol S. , Scamell Richard W.
Published: July 2002

In a recent application of the theory of strategic contingencies in three large multinational firms, Lucas found that information services departments were perceived by others as having low levels of power and influence and suggested a variety of reasons for the results. This note continues the application of the theory of strategic contingencies to the information services department by describing a study of intraorganizational power that uses basically the same procedures as the Lucas study and obtains similar results. In an effort to stimulate future power-related research in the information systems area, this note concludes by suggesting several reasons, beyond those given by Lucas, for the levels of power attributed to information services departments.
Assessing software maintainability
Authors: Berns Gerald M.
Published: July 2002

How easy is it to maintain a program? To a large extent, that depends on how difficult the program is to understand. A technique to measure program difficulty yields encouraging results.
Designing software for one-dimensional partial differential equations
Authors: Schryer N. L.
Published: July 2002

Users of software for solving partial differential equations are often surprised by its inability to formulate their problems.

Computer scientists speak of partial differential equations (PDEs) as canonical coupled systems, typically in divergence form. Physicists, chemists, and engineers start with the same description, but then add real-world things like “Rankine-Hugoniot” conditions, integro-differential operators, and Eulerian (moving) coordinate systems.

This paper describes a generalization of the classical PDE formulation that allows users to formulate virtually any pde problem. The extended formulation has been used successfully on a wide range of nontrivial problems in the physical sciences that cannot even be written down in the classical form.
Departmentalization in software development and maintenance
Authors: Swanson E. Burton , Beath Cynthia Mathis
Published: July 2002

Exploring the strengths and weaknesses of three alternative bases for systems staff departmentalization suggests the benefits of an organizational form in which maintenance is separate from new system development.
Adventures in Cosmogony
Authors: Cameron A. G. W.
Published: July 2002

▪ Abstract  I was born and educated in Canada, obtaining my PhD in experimental nuclear physics. When I learned that technetium had been found in stellar spectra, I taught myself some astrophysics and began to study stellar nucleosynthesis. This is an account of those studies and of the pathway through much of theoretical astrophysics and planetary physics that was a natural outgrowth of the pursuit of nucleosynthesis problems. I also discuss my experiences in government service and in academia, in organization of conferences, in governmental advising, and in academic administration. In particular, I emphasize the logical connections among the various scientific themes that I have pursued.
ACQUISITION OF IDENTITY IN THE DEVELOPING LEAF
Authors: Sylvester Anne W. , Smith Laurie , Freeling Michael
Published: July 2002

▪ Abstract  Leaves are produced repeatedly from the shoot apical meristem of plants. Molecular and cellular evidence show that identity of the leaf and its parts is acquired progressively and that the underlying process changes as the leaf matures. The relative importance of cell lineage compared with a position-dependent model for specifying cell fates is discussed.
Neural Induction
Authors: Weinstein Daniel C. , Hemmati-Brivanlou Ali
Published: July 2002

▪ Abstract  The formation of the vertebrate nervous system is initiated at gastrula stages of development, when signals from a specialized cluster of cells (the organizer) trigger neural development in the ectoderm. This process, termed neural induction, was first described in 1924 and stemmed from experiments on amphibia ( Spemann & Mangold 1924 ). In recent years, the molecular mechanisms underlying neural induction in the amphibian have been elucidated. Surprisingly, neuralizing agents secreted by the organizer do not act via receptor-mediated signaling events; rather, these factors antagonize local epidermal inducers within the cells of the dorsal ectoderm and function to uncover the latent neural fate of these cells.

Many of the recent advances in our understanding of vertebrate neural induction come from studies on the frog, Xenopus laevis. It is now clear that a blockade of signaling of the bone morphogenetic proteins (BMPs) during gastrula stages is sufficient to initiate neuralization of the ectoderm in this species. Thus this review first details our current understanding of neural induction, using the amphibian as a model. We then use data emerging from other systems to examine the extent to which the Xenopus studies can be applied to other vertebrate species. The initiation of the neurectoderm-specific gene expression program and subsequent steps in patterning and neuronal development are only touched on here. We focus primarily on the initial establishment of the neural fate in the vertebrate gastrula ectoderm.
ECOLOGY AND MANAGEMENT OF HAZELNUT PESTS
Authors: AliNiazee M. T.
Published: July 2002

▪ Abstract  Insect and mite pests cause serious damage to the hazelnut crop worldwide. The control strategies used against these pests include application of insecticides, classical and augmentative biological control, utilization of resistant varieties, and use of Bacillus thuringiensis–based preparations. In the United States, extensive research has been directed toward elucidating ecological interactions among different pests and natural enemies and understanding the role of abiotic factors in pest population dynamics. Differences exist worldwide regarding the understanding of pests and natural enemy biologies and, to a limited extent, control practices. An integrated pest management approach based on utilizing effective sampling and monitoring techniques and a near complete reliance on biological control and “soft” pesticides, including insect growth regulators, is currently under development both in North America and Europe/Turkey. Hazelnuts are on the verge of becoming one of the first crops in the United States that could possibly be produced commercially without the use of any broad-spectrum organic insecticides.
Biology and Ecology of Higher Diptera from Freshwater Wetlands
Authors: Keiper Joe B. , Walton William E. , Foote Benjamin A.
Published: July 2002

▪ Abstract  Although studies of freshwater entomofauna frequently do not include the biodiversity and ecological roles of higher Diptera, cyclorraphous flies are often numerous and species rich in wetlands. Seventeen families are commonly found in freshwater wetlands, with Ephydridae, Chloropidae, Sciomyzidae, Sphaeroceridae, and Scathophagidae being among the most important in terms of population size and species richness. Difficulty with sampling cryptic larval habitats and species identification challenges may account for the exclusion of acalyptrate and other dipterans from wetlands ecology studies. Large populations are facilitated by the high productivity of freshwater wetlands and the high intrinsic rate of increase characteristic of many species. Higher dipterans exist in all freshwater wetland types, are microhabitat selective, and play significant roles in food webs. The varied strategies for food acquisition and patterns of spatial and temporal distribution limit ecological overlap among the higher Diptera.
TEMPORAL PATTERN FORMATION BY HETEROCHRONIC GENES
Authors: Slack Frank , Ruvkun Gary
Published: July 2002

▪ Abstract  Heterochrony describes the phylogenetic variation in the relative timing of major developmental events. Such heterochronic variation has been noted across phylogeny, including closely related species, suggesting that particular genetic loci control global aspects of developmental timing, and that variation at those loci may play important roles in evolutionary change. Genetic analyses of heterochronic mutations in the nematode Caenorhabditis elegans reveal that control of temporal patterning is analogous to the dedicated genetic pathways that control the patterning of the spatial axes in Drosophila and other metazoans. These pathways generate graded or binary levels of regulatory factors that pattern particular axes of the developing animal. C. elegans heterochronic genes constitute a regulatory cascade that both generates a temporal decrease in the level of the LIN-14 and LIN-28 proteins and responds to the changes in these gene activities to coordinate the temporal sequence of many cell fates as the animal develops. The temporal regulation of lin-14 and lin-28 gene activities is posttranscriptional and mediated by the antisense RNA product of the lin-4 gene. Hormonal control of developmental timing is a common theme throughout phylogeny. Heterochronic genes that involve hormonal signaling have been identified in vertebrates as well as C. elegans.
CLAYS AND CLAY INTERCALATION COMPOUNDS:Properties and Physical Phenomena
Authors: Solin S. A.
Published: July 2002

▪ Abstract  The materials properties and physical phenomena exhibited by layered silicate clays and clay intercalation compounds, a subgroup of the general class of layered solids, are reviewed. The importance of layer rigidity is emphasized. Clays are compared and contrasted with the more familiar layered solids such as graphite and dichalcogenides. Some of the unusual structural features of clays including interstratification, swelling, and the lack of staging are discussed and explained qualitatively and quantitatively. Novel magnetic phenomena such as that associated with a disordered two-dimensional kagomé antiferromagnet formed in synthetic clays and the effect of co-intercalated water on the crystal field–induced magnetic ordering in natural clays are described and analyzed. The vibrational excitations in clays are addressed in terms of lattice dynamical models for the phonon dispersion curves. The theoretical models are compared with experimental measurements including neutron scattering and Raman spectroscopy.
SPIN-DEPENDENT TRANSPORT AND LOW-FIELD MAGNETORESISTANCE IN DOPED MANGANITES
Authors: Sun J. Z. , Gupta A.
Published: July 2002

▪ Abstract  Doped manganite perovskites exhibit large magnetoresistance, but usually only in high fields (>1 Tesla). Efforts are under way to understand the underlying mechanism and to explore possibilities of achieving large magnetoresistance at low fields, which has led to focused studies of spin-dependent transport across macroscopic interfaces between manganites. We review recent experimental progress in this area.
NONRENAL COMPLICATIONS OF THE NEPHROTIC SYNDROME
Authors: Kaysen George A.
Published: July 2002

▪ Abstract  The nephrotic syndrome is a consequence of urinary loss of intermediate-sized plasma proteins and the resulting homeostatic responses to those losses. Plasma protein composition is changed greatly. Pathphysiologic changes are a consequence of the nature of the proteins lost and of the proteins that are increased in plasma to replace them. Plasma oncotic pressure (π) falls because of the replacement of relatively small plasma proteins by larger ones. Decreased π increases transudation of fluid into the interstitum and favors edema. This is exacerbated by causing renal insensitivity to atrial natriuretic factor (ANF), primary renal sodium retention, and plasma volume expansion. Many proteins lost in the urine, such as erythopoietin and IgG, are not defended by increased synthesis. Their loss may result in reduced immunity, anemia, and endocrinopathies. Albumin synthesis can be increased by dietary protein augmentation; however, urinary protein losses also increase, offsetting any palliative effect of increased albumin synthesis on albumin stores. The synthesis of many other proteins secreted by the liver is also increased, causing an elevation in plasma levels of several large proteins, including lipoproteins and elements of the coagulation cascade. This results in hyperlipidemia and, in conjunction with the urinary loss of smaller proteins that impede coagulation, a hypercoagulable state. Lipoprotein catabolism is also reduced as a consequence of proteinuria contributing to increased lipid levels.