bluuebunny/crossref_metadata_2025_split huggingface dataset:
Approximation schemes for covering and packing problems in image processing and VLSI
Authors: Hochbaum Dorit S. , Maass Wolfgang 
Published: July 2002

A unified and powerful approach is presented for devising polynomial approximation schemes for many strongly NP-complete problems. Such schemes consist of families of approximation algorithms for each desired performance bound on the relative error ε > Ο, with running time that is polynomial when ε is fixed. Though the polynomiality of these algorithms depends on the degree of approximation ε being fixed, they cannot be improved, owing to a negative result stating that there are no fully polynomial approximation schemes for strongly NP-complete problems unless NP = P.
The unified technique that is introduced here, referred to as the shifting strategy, is applicable to numerous geometric covering and packing problems. The method of using the technique and how it varies with problem parameters are illustrated. A similar technique, independently devised by B. S. Baker, was shown to be applicable for covering and packing problems on planar graphs.
A programmable interface language for heterogeneous distributed systems
Authors: Falcone Joseph R. 
Published: July 2002

The 1980s have witnessed the emergence of a new architecture for computing based on networks of personal computer workstations. The performance requirements of such systems of workstations places a strain on traditional approaches to network architecture. The integration of diverse systems into this environment introduces functional compatibility issues that are not present in homogeneous networks. Effective prescriptions for functional compatibility, therefore, must go beyond the communication paradigms used in present distributed systems, such as remote procedure calls.
This paper proposes a distributed system architecture in which communication follows a programming paradigm. In this architecture a programming language provides remote service interfaces for the heterogeneous distributed system environment. This language is a flexible and efficient medium for implementing service function protocols. In essence, clients and servers communicate by programming one another.
Morphology of ``Information Flow''
Authors: Fairthorne Robert A. 
Published: July 2002

Such phrases as “information flow” may be purely metaphorical, or may refer to porterage and storage of physical documents, transmission of signals, power required for signaling, Shannon's Selective Information, changes in the state of one's personal knowledge, propagation of announcements concerning messages, social increase of awareness, propagation of or reaction to imperatives, and so on. These matters are distinct and must be distinguished. Then conditions must be stated under which one can validly speak of and measure the appropriate flow. In this paper it is shown that within the field of Notification (mention and delivery of recorded messages to users) there are twenty basic activities formed by choosing triads from the six variables, Message, Code, Channel, Source, Destination, and Designation.
“Flow” has meaning only when two such triads have two variables in common, forming a tetrad. Then flow or correspondence between any pair of variables is inextricable from a conjugate flow or correspondence between the other pair. Between any pair of endpoints there are six possible distinct types of flow, according to which two of the remaining four variables are directly used to achieve the flow.
A software engineering perspective on algorithmics
Authors: Weihe Karsten 
Published: July 2002

Analgorithm componentis an implementation of an algorithm which is not intended to be a stand-alone module, but to perform a specific task within a large software package or even within several distinct software packages. Therefore, the design of algorithm components must also incorporate software-engineering aspects. A key design goal is adaptability. This goal is important for maintenance throughout a project, prototypical development, and reuse in new, unforseen contexts. From a theoretical viewpoint most algorithms apply to a range of possible use scenarios. Ideally, each algorithm is implemented by one algorithm component, which is easily, safely, and efficiently adaptable to all of these contexts.Various techniques have been developed for the design and implementation of algorithm components. However, a common basis for systematic, detailed evaluations and comparisons in view of therealpractical needs is still missing. Basically, this means a set of concrete criteria, which specify what sort of adaptability isreallyrequired in practice, and which are well-justified by convincing, representative use scenarios.This paper is intended to be a first “milestone” on the way towards such a system of criteria. We will present a set of concrete goals, which are general and problem-independent and might appear ubiquitously in the algorithmic realm. These goals are illustrated, motivated, and justified by an extensive requirements analysis for a particular algorithm from a particular algorithmic domain: Dijkstra's algorithm for shortest paths in networks.Clearly, the field of algorithmics might be too versatile to allow a comprehensive, yet concise set of precise, justified criteria. Even a domain as restricted as graph and network algorithms includes aspects that are not fully understood. The analysis will include a discussion of the limits of the case study and the scope of the goals. The case study was chosen because it seems to be close to the “boderline” between the aspects that are well understood and the aspects that are not. Hence, this example may well serve as an“acid test” for programming techniques in view of the state of the art.
Experiments in SR with different upcall program structures
Authors: Atkins M. Stella 
Published: July 2002

This paper explores program designs for layered systems such as communication protocols and server/client systems that do not exhibit a strict hierarchy in their control flow. Clark has proposed structuring such systems, where both upward and downward control flow are required, to use efficient synchronous procedure calls between the layers whenever possible. The termupcallis used by Clark to describe this synchronous upward communication from server to client.Several techniques are possible for structuring such programs using upcalls. Comparisons are made by implementing a communication protocol described by Clark in three different ways. The first method implements all the protocol routines in a single large module. The second method structures the routines into modules occupying vertical slices of the protocol layers, and the third method structures the routines into modules corresponding to the protocol layers.Comparisons are made on two fronts: Preservation of modularity, in order to determine which method shows fault-tolerance and ease of programming, and program performance, which is a key motivation for the upcalls programming style. We conclude that the vertically layered protocol design is to be preferred unless there are many shared variables between the send-side and receive-side, as it is very efficient and provides the best protection of clients from each other. The horizontally layered design is the least efficient, but it is the easiest to program.
A framework for choosing a database query language
Authors: Jarke Matthias , Vassiliou Yannis 
Published: July 2002

This paper presents a systematic approach to matching categories of query language interfaces with the requirements of certain user types. The method is based on a trend model of query language development on the dimensions of functional capabilities and usability. From the trend model the following are derived: a classification scheme for query languages, a criterion hierarchy for query language evaluation, a comprehensive classification scheme of query language users and their requirements, and preliminary recommendations for allocating language classes to user types.
The method integrates the results of existing human factors studies and provides a structured framework for future research in this area. Current and expected developments are exemplified by the description of "new generation" database query languages. In a practical query language selection problem, the results of this paper can be used for preselecting suitable query language types; the final selection decision will also depend on organization-specific factors, such as the available database management system, hardware and software strategies, and financial system costs.
Security-control methods for statistical databases: a comparative study
Authors: Adam Nabil R. , Worthmann John C. 
Published: July 2002

This paper considers the problem of providing security to statistical databases against disclosure of confidential information. Security-control methods suggested in the literature are classified into four general approaches: conceptual, query restriction, data perturbation, and output perturbation.
Criteria for evaluating the performance of the various security-control methods are identified. Security-control methods that are based on each of the four approaches are discussed, together with their performance with respect to the identified evaluation criteria. A detailed comparative analysis of the most promising methods for protecting dynamic-online statistical databases is also presented.
To date no single security-control method prevents both exact and partial disclosures. There are, however, a few perturbation-based methods that prevent exact disclosure and enable the database administrator to exercise "statistical disclosure control." Some of these methods, however introduce bias into query responses or suffer from the 0/1 query-set-size problem (i.e., partial disclosure is possible in case of null query set or a query set of size 1).
We recommend directing future research efforts toward developing new methods that prevent exact disclosure and provide statistical-disclosure control, while at the same time do not suffer from the bias problem and the 0/1 query-set-size problem. Furthermore, efforts directed toward developing a bias-correction mechanism and solving the general problem of small query-set-size would help salvage a few of the current perturbation-based methods.
The RGYB color geometry
Authors: Ware Colin , Cowan William 
Published: July 2002

Background:
The gamut of a color CRT is defined by its three primary colors, each produced by a phosphor/electron gun combination. Light from the primaries combines additively, so the color gamut is a subset of a three dimensional vector space [1]. With the primaries as basis vectors normalized to 1.0, the color gamut is a unit cube, known as the RGB color geometry, since the three primaries are usually red, green, and blue. User interaction via RGB is generally thought to be counterintuitive, and transformations of RGB, such as Smith's HSV geometry [10] which is derived from centuries old artists' models [2], are more popular. More recent color theories, based on psychophysical and physiological models of early visual processing, suggest that more intuitive geometries may be possible.
The RGYB geometry is based on two recent discoveries about the human visual system. First, the three color signals from the cone receptors are organized into three opponent channels [1, 7]. A single achromatic channel indicates lightness or brightness. Two chromatic channels, red/green and yellow/blue, signal the chromatic quantities. Second, signals on the achromatic channel are easily distinguishable from signals on the chromatic ones [6]. Consequently, it is usual to represent colors as a set of surfaces of colors that vary in chromaticity, each at a different level of brightness. Examples are as diverse as CIE chromaticity coordinates, the CIELUV uniform color space, the Munsell color system, and computer graphics color spaces such as HSV and HLS [10, 12].
Surveying current research in object-oriented design
Authors: Wirfs-Brock Rebecca J. , Johnson Ralph E. 
Published: July 2002

The state of object-oriented is evolving rapidly. This survey describes what are currently thought to be the key ideas. Although it is necessarily incomplete, it contains both academic and industrial efforts and describes work in both the United States and Europe. It ignores well-known ideas, like that of Coad and Meyer [34], in favor of less widely known projects.
Research in object-oriented design can be divided many ways. Some research is focused on describing a design process. Some is focused on finding rules for good designs. A third approach is to build tools to support design. Most of the research described in this article does all three.
We first present work from Alan Snyder at Hewlett-Packard on developing a common framework for object-oriented terminology. The goal of this effort is to develop and communicate a corporate-wide common language for specifying and communicating about objects.
We next look into the research activity at Hewlett-Packard, led by Dennis de Champeaux. De Champeaux is developing a model for object-based analysis. His current research focuses on the use of a trigger-based model for inter-object communications and development of a top-down approach to analysis using ensembles.
We then survey two research activities that prescribe the design process. Rebecca Wirfs-Brock from Tektronix has been developing an object-oriented design method that focuses on object responsibilities and collaborations. The method includes graphical tools for improving encapsulation and understanding patterns of object communication. Trygve Reenskaug at the Center for Industriforskning in Oslo, Norway has been developing an object-oriented design method that focuses on roles, synthesis, and structuring. The method, called Object-Oriented Role Analysis, Syntheses and Structuring, is based on first modeling small sub-problems, and then combining small models into larger ones in a controlled manner using both inheritance (synthesis) and run-time binding (structuring).
We then present investigations by Ralph Johnson at the University of Illinois at Urbana-Champaign into object-oriented frameworks and the reuse of large-scale designs. A framework is a high-level design or application architecture and consists of a suite of classes that are specifically designed to be refined and used as a group. Past work has focused on describing frameworks and how they are developed. Current work includes the design of tools to make it easier to design frameworks.
Finally, we present some results from the research group in object-oriented software engineering at Northeastern University, led by Karl Lieberherr. They have been working on object-oriented Computer Assisted Software Engineering (CASE) technology, called the Demeterm system, which generates language-specific class definitions from language-independent class dictionaries. The Demeter system include tools for checking design rules and for implementing a design.
HERPES SIMPLEX VIRUS DNA REPLICATION
Authors: Boehmer Paul E. , Lehman I. R. 
Published: July 2002

The Herpesviridae comprise a large class of animal viruses of considerable public health importance. Of the Herpesviridae, replication of herpes simplex virus type-1 (HSV-1) has been the most extensively studied. The linear 152-kbp HSV-1 genome contains three origins of DNA replication and approximately 75 open-reading frames. Of these frames, seven encode proteins that are required for origin-specific DNA replication. These proteins include a processive heterodimeric DNA polymerase, a single-strand DNA-binding protein, a heterotrimeric primosome with 5′-3′ DNA helicase and primase activities, and an origin-binding protein with 3′-5′ DNA helicase activity. HSV-1 also encodes a set of enzymes involved in nucleotide metabolism that are not required for viral replication in cultured cells. These enzymes include a deoxyuridine triphosphatase, a ribonucleotide reductase, a thymidine kinase, an alkaline endo-exonuclease, and a uracil-DNA glycosylase. Host enzymes, notably DNA polymerase α-primase, DNA ligase I, and topoisomerase II, are probably also required.Following circularization of the linear viral genome, DNA replication very likely proceeds in two phases: an initial phase of theta replication, initiated at one or more of the origins, followed by a rolling-circle mode of replication. The latter generates concatemers that are cleaved and packaged into infectious viral particles. The rolling-circle phase of HSV-1 DNA replication has been reconstituted in vitro by a complex containing several of the HSV-1 encoded DNA replication enzymes. Reconstitution of the theta phase has thus far eluded workers in the field and remains a challenge for the future.
A QUEST FOR ERYTHROPOIETIN OVER NINE DECADES
Authors: Fisher James W. 
Published: July 2002

[Figure: see text] ▪ Abstract  The major research accomplishments of the author are described from the time of his PhD thesis work on the mechanism of cobalt polycythemia to the present day. His early work on the quest for the cell that produces erythropoietin (Epo) to his current work on oxygen sensing and signal transduction pathways involved in erythropoietin gene expression are reported. He describes his main research interest in the mechanism of cobalt polycythemia between 1954 and 1962 and his research on how hormones such as the glucocorticoids function in the regulation of erythropoiesis (1956–1962). His major findings during this period were the discovery that hydrocortisone and corticosterone stimulated erythropoiesis (1958) and that cobalt increased erythropoietin production in the isolated perfused dog kidney (1961). He describes how he was led astray in some of his early studies on the cells in the kidney that produce erythropoietin, because of the less-developed technology available to him at that time; and how in situ hybridization and other molecular biology techniques enabled him to confirm some of the earlier work in mice by other investigators that interstitial cells in the kidney were the site of production of erythropoietin in the primate. His work in the controversial area of the mechanism of the anemia of end-stage renal disease is described in detail, as it pertains to Epo deficiency and suppressed erythroid progenitor cell response to Epo. He also discusses his recent work on signal transduction pathways (hypoxia, nitric oxide, adenosine, and C kinase) in oxygen sensing and Epo gene expression.
Meeting Report: Transcranial Magnetic Stimulation and Studies of Human Cognition
Authors: Fitzpatrick Susan M. , Rothman Douglas L. 
Published: July 2002

Abstract
A James S. McDonnell Foundation workshop1 examined the role of TMS in studies of human cognition. A summary of the workshop presentations, discussion, and the recommendations appear below.2 A selected reference list is provided at the end of the summary.
Brain Activation During Mental Transformation of Size
Authors: Larsen Axel , Bundesen Claus , Kyllingsbæk Søren , Paulson Olaf B. , Law Ian 
Published: July 2002

Abstract
Visual comparison between different-sized objects with respect to shape can be done by encoding one of the objects as a mental image, transforming the image to the size format of the other object, and then testing for a match (Bundesen, C., & Larsen, A. [1975]. Visual transformation of size. Journal of Experimental Psychology: Human Perception and Performance, 1, 214-220). To identify the brain structures implicated in mental transformation of size, we measured the distribution of regional cerebral blood flow (rCBF) by positron emission tomography (PET) in 12 normal subjects who compared random stimulus patterns with respect to shape regardless of variations in size in a one-back match-to-sample paradigm. Each subject was PET-scanned 12 times during repetitive injections of H2 15O. In one condition (three scans), all stimulus patterns were small. In a second condition (three scans), all stimuli were large. In the third condition (six scans), the stimuli alternated between small and large. Mental transformation of size should occur in the alternating-size condition but not in the fixed-size conditions. As expected, behavioral measures (reaction time [RT], d', β) were nearly the same for the two fixed-size conditions but mean RT was longer and d' smaller in the alternating-size condition. Changes in rCBF specific to mental transformation of size were estimated by contrasting the alternating-size with the fixed-size conditions by use of statistical parametric mapping (SPM96) at a threshold of p &lt; .05 corrected for multiple comparisons. The detected brain structures implicated in mental transformation of size were primarily located in the dorsal pathways, comprising structures in the occipital, parietal, and temporal transition zone (predominantly in the left hemisphere), posterior parietal cortex (bilaterally), area MT/V5 (left), and vermis (bilaterally). Contrasts between the two fixed-size conditions showed significant effects in only the occipital cortex.
Asymmetry of Neuronal Activity During Extracellular Microelectrode Recording from Left and Right Human Temporal Lobe Neocortex During Rhyming and Line-Matching
Authors: Schwartz Theodore H. , Haglund Michael M. , Lettich Ettore , Ojemann George A. 
Published: July 2002

Abstract
Recordings of neuronal activity in humans have identified few correlates of the known hemispheric asymmetries of functional lateralization. Here, we examine single-unit activity recorded from both hemispheres during two delayed match-to-sample tasks that show strong hemispheric lateralization based on lesion effects; a line-matching (LM) task related to the right hemisphere, and a rhyming (RHY) task related to the left. Nineteen neuronal populations were recorded with extracellular microelectrodes from the left temporal neocortex of 11 awake patients, and 18 from the right in 9 patients during anterior temporal lobectomy for complex partial seizures under local anesthesia. All subjects were left hemisphere dominant for language. Twelve (32%) populations exhibited statistically significant changes in activity at p &lt; .05. Although changes in firing frequency were recorded from both hemispheres during both tasks, the RHY task elicited changes in activity several hundred milliseconds earlier on the left side than on the right. The LM task, on the other hand, induced changes earlier on the right side than on the left. Both hemispheres contained units active during verbal responses regardless of which behavior elicited the response. Our results indicate that cerebral dominance is reflected in earlier neuronal activity in the anterior temporal lobe during tasks lateralized to that hemisphere.
Efficient Learning in Boltzmann Machines Using Linear Response Theory
Authors: Kappen H. J. , Rodríguez F. B. 
Published: July 2002

The learning process in Boltzmann machines is computationally very expensive. The computational complexity of the exact algorithm is exponential in the number of neurons. We present a new approximate learning algorithm for Boltzmann machines, based on mean-field theory and the linear response theorem. The computational complexity of the algorithm is cubic in the number of neurons.In the absence of hidden units, we show how the weights can be directly computed from the fixed-point equation of the learning rules. Thus, in this case we do not need to use a gradient descent procedure for the learning process. We show that the solutions of this method are close to the optimal solutions and give a significant improvement when correlations play a significant role. Finally, we apply the method to a pattern completion task and show good performance for networks up to 100 neurons.