bluuebunny/crossref_metadata_2025 huggingface dataset:
Anisotropic pinning enhancement in Nb films with arrays of submicrometric Ni lines
Authors: Jaque D. , González E. M. , Martin J. I. , Anguita J. V. , Vicent J. L.
Published: October 2002

Arrays of submicrometric Ni lines have been fabricated in superconducting Nb films by electron beam lithography. In the mixed state, these arrays induce strong anisotropy in the dissipation behavior. The dissipation is reduced several orders of magnitude, in the whole applied magnetic field range, when the vortex motion is perpendicular to the Ni lines (applied current parallel to them) in comparison with dissipation of vortices moving parallel to the lines. In addition, for the samples studied in this work, a change in the slope of the ρ(B) curves is observed when the vortices move perpendicular to the lines and the vortex lattice parameter matches the width of the Ni lines.
Local electronic structures of GaMnAs observed by cross-sectional scanning tunneling microscopy
Authors: Tsuruoka T. , Tachikawa N. , Ushioda S. , Matsukura F. , Takamura K. , Ohno H.
Published: October 2002

Using cross-sectional scanning tunneling microscopy (STM), we have investigated the local electronic properties of molecular-beam epitaxy grown GaMnAs layers on a p-GaAs substrate. The STM image shows light and dark areas with the average size on the order of nm. From conductance spectra measured with the STM, the bandgap of the GaMnAs is estimated to be 1.23±0.05 eV. An apparent conductance within the bandgap indicates the presence of hole states in the valence band, which are induced by Mn acceptors. A conductance peak at 0.7 eV above the valence band edge can be identified with electron tunneling into the ionization levels of As antisites.
Self-assembly of three-dimensional photonic crystals on structured silicon wafers
Authors: Ferrand P. , Egen M. , Griesebock B. , Ahopelto J. , Müller M. , Zentel R. , Romanov S. G. , Sotomayor Torres C. M.
Published: October 2002

The growth of an opal-like polymer photonic crystal (PhC) on deeply etched silicon wafers is reported. It is shown that 10 μm deep trenches, as narrow as 10 μm can be uniformly filled by self-assembly of microspheres, in a close-packed face-centered-cubic lattice. These observations are confirmed by optical reflectance measurements in the visible range, in agreement with theoretical calculations of the photonic band gap. A slight fluctuation of the lattice parameter is noticed in the case of the narrowest channels. The possibility to detach the PhC from the substrate is also demonstrated. The potential of this approach for building complex PhC-based complex architectures is discussed.
Fabrication of single-hole transistors on hydrogenated diamond surface using atomic force microscope
Authors: Tachiki Minoru , Seo Hokuto , Banno Tokishige , Sumikawa Yu , Umezawa Hitoshi , Kawarada Hiroshi
Published: October 2002

Nanofabrication of electron devices based on the stability of hydrogen- and oxygen-terminated diamond surfaces is performed using an atomic force microscope modification technology. A nanotechnology involving the separation of C–H and C–O bonded surfaces has been applied to realize the single-hole transistors. The single-hole transistors operate at liquid-nitrogen temperature (77 K), where the Coulomb oscillation characteristics are clearly observed.
Does Spatial Assimilation Work for Black Immigrants in the US?
Authors: Freeman Lance
Published: October 2002

This paper uses the following theoretical perspectives to explain the segregation patterns of foreign Blacks in the US: the spatial assimilation model, which posits that immigrants will achieve greater residential proximity to native Whites as they acculturate and become upwardly mobile; the primacy of race model that sees race as trumping all other characteristics in determining spatial relations with Whites and Blacks; and, the ethnic identity model that suggests foreign Blacks' image as a 'model minority' will allow them to differentiate themselves from native Blacks and achieve a relative degree of integration with Whites. The results of this study are most consistent with the primacy of race model. Regardless of their degree of acculturation, Black immigrants were highly segregated from Whites but only modestly so from native Blacks.
Indigenising the Colonial City: Late 19th-century Colombo and its Landscape
Authors: Perera Nihal
Published: October 2002

This paper is concerned with the indigenisation of Colombo and the transformation of the city from an exclusive domain of colonial power to a milieu which supported Ceylonese social and cultural practices. It investigates the shifting indigenous response to the colonisation of Colombo, from challenging to indigenising the city between the 1860s and the 1880s. The paper approaches indigenisation from a 'reverse-Orientalist' perspective that focuses on the landscape produced by the emergence of national elite, the revival of Buddhism and processes of naturalisation and migration. It demonstrates that indigenisation was integral to colonialism, which simultaneously instigated the Westernisation of subjects and the indigenisation of social and spatial structures. The resulting multilayered landscape, negotiated between imposing colonial structures and Ceylonese cultural practices, was characterised by irony, mimicry, ambivalence, liminality and hybridity.
Developmental Toxicity Study of Orally Administered Resorcinol Bis-Diphenylphosphate (RDP) in Rabbits
Authors: Ryan B. M. , Henrich R. , Freudenthal R. I.
Published: October 2002

Fyrolflex resorcinolbis-diphenylphosphate (RDP) is a nonhalogenphosphate ester product that is widely used as a flame retardant for petrochemicalplastics and high-temperature lubricant additive applications. The potential developmental toxicity of RDP was evaluated in rabbits. Groups of 27 sperm-positive New Zealand white rabbits (Hazelton Research Products Inc., Denver, PA) were administered graded concentrations of 50, 200, or 1000 mg/kg/day of RDP in corn oil. A vehicle control group of equal size was administered corn oil alone. Rabbits were dosed daily (1.5 ml/kg) on gestationdays 6 to 28 and sacrificed on gestationday 29. The fetuses were removed by cesarean section and examined for gross external, visceral, cephalic, and skeletal anomalies. No treatment-related clinical signs of toxicity were observed. No treatment-related effects in maternal food consumption, body weight, body weight gain, or on uterus, liver, kidney, and spleen weights were detected. Fetal viability and body weight, as well as developmental end points were also unaffected by treatment. Accordingly, exposure of pregnant rabbits to doses ranging from 50 to 1000 mg/kg/day of RDP during the periods of major organogenesis and histogenesis did not result in any biologically significant toxic or teratogenic/developmental effect in the dams or fetuses.
Safety Assessment of Panax Ginseng
Authors: Carabin Ioana G. , Burdock George A. , Chatzidakis Chris
Published: October 2002

Since the 1994 Dietary Supplement Health and Education Act, the consumption of botanical supplements has increased to the point where ginseng is the third best selling herbal supplement in the United States and it is now also being used as a flavoring agent in foods. The predominant pharmacologically active constituents of Panax are ginsenosides, at least 25 of which have been identified and are present in variable amounts and ratios to one another, depending on the particular species, variety, and conditions of growth. The toxicological profile of ginseng indicates it to be of rather low acute oral toxicity (LD50 > 5000 mg/kg for rats and mice, approximating 200 mg ginsenoside/kg.) No toxicological effects were identified in mini pigs at a dose of 2000 mg/kg (80 mg ginsenoside/kg). As concluded from a 90-day dog study and in reproduction studies in rats and mice, 15 mg/kg (∼ 0.6 mg ginsenoside/kg) was without effect. No effect was seen in rats administered 4000 mg/kg (160 mg ginsenoside/kg) for 20 days. There was no mutagenic activity observed in Salmonella typhimurium TM677 system with the use of ginseng in the presence or absence of metabolic activation. The no-observed-adverse-effectlevel (NOAEL) in rodents is likely within the range of 50 to 100 mg ginsenoside/kg. There are no confirmed reports of adverse reactions in humans attributed to ginseng alone. Importantly, no consistent symptomology or findings have been attributed to, or identified as being associated with, ginseng consumption. Ginseng extracts standardized at a concentration of 4 mg ginsenosides/100 mg capsule and given at a dose of up to 114 θ g ginsenoside/kg have not resulted in untoward effects when administered to humans for periods of up to 12 weeks.
Inferring Domain–Domain Interactions From Protein–Protein Interactions
Authors: Deng Minghua , Mehta Shipra , Sun Fengzhu , Chen Ting
Published: October 2002

The interaction between proteins is one of the most important features of protein functions. Behind protein–protein interactions there are protein domains interacting physically with one another to perform the necessary functions. Therefore, understanding protein interactions at the domain level gives a global view of the protein interaction network, and possibly of protein functions. Two research groups used yeast two-hybrid assays to generate 5719 interactions between proteins of the yeastSaccharomyces cerevisiae. This allows us to study the large-scale conserved patterns of interactions between protein domains. Using evolutionarily conserved domains defined in a protein–domain database called PFAM (http://PFAM.wustl.edu), we apply a Maximum Likelihood Estimation method to infer interacting domains that are consistent with the observed protein–protein interactions. We estimate the probabilities of interactions between every pair of domains and measure the accuracies of our predictions at the protein level. Using the inferred domain–domain interactions, we predict interactions between proteins. Our predicted protein–protein interactions have a significant overlap with the protein–protein interactions (MIPS:http://mips.gfs.de) obtained by methods other than the two-hybrid assays. The mean correlation coefficient of the gene expression profiles for our predicted interaction pairs is significantly higher than that for random pairs. Our method has shown robustness in analyzing incomplete data sets and dealing with various experimental errors. We found several novel protein–protein interactions such as RPS0A interacting with APG17 and TAF40 interacting with SPT3, which are consistent with the functions of the proteins.

[Supplementary material is available online athttp://www.genome.organdhttp://www-hto.usc.edu/∼msms/ProteinInteraction.]
Genetic Algorithm–Neural Network Estimation of Cobb Angle from Torso Asymmetry in Scoliosis
Authors: Jaremko Jacob L. , Poncet Philippe , Ronsky Janet , Harder James , Dansereau Jean , Labelle Hubert , Zernicke Ronald F.
Published: October 2002

Scoliosis severity, measured by the Cobb angle, was estimated by artificial neural network from indices of torso surface asymmetry using a genetic algorithm to select the optimal set of input torso indices. Estimates of the Cobb angle were accurate within 5° in two-thirds, and within 10° in six-sevenths, of a test set of 115 scans of 48 scoliosis patients, showing promise for future longitudinal studies to detect scoliosis progression without use of X-rays.
Analysis of Crack Growth in a 3D Voronoi Structure: A Model for Fatigue in Low Density Trabecular Bone
Authors: Makiyama A. M. , Vajjhala S. , Gibson L. J.
Published: October 2002

Both creep and crack growth contribute to the reduction in modulus associated with fatigue loading in bone. Here we simulate crack growth and subsequent strut failure in fatigue in an open-cell, three-dimensional Voronoi structure which is similar to that of low density, osteoporotic bone. The model indicates that sequential failure of struts leads to a precipitous drop in modulus: the failure of 1% of the struts leads to about a 10% decrease in modulus. A parametric study is performed to assess the influence of normalized stress range, relative density, initial crack size, crack shape and cell geometry on the fatigue life. The fatigue life is most sensitive to the relative density and the initial crack length. The results lead to a quantitative expression for the fatigue life associated with crack growth. Data for the fatigue life of trabecular bone are compared with the crack growth model described in this paper, as well as with a previous model for creep of a three-dimensional Voronoi structure. In our models, creep dominates the fatigue behavior in low cycle fatigue while crack growth dominates in high cycle fatigue, consistent with previous observations on cortical bone. The large scatter in the trabecular bone fatigue data make it impossible to identify a transition between creep dominated fatigue and crack growth dominated fatigue. The parametric study of the crack growth model indicates that variations in relative density among specimens, initial crack size within trabeculae and crack shape could easily produce such variability in the test results.
An Automated Approach for Direct Measurement of Two-Dimensional Strain Distributions Within Articular Cartilage Under Unconfined Compression
Authors: Wang Christopher C-B. , Deng Jian-Ming , Ateshian Gerard A. , Hung Clark T.
Published: October 2002

An automated approach for measuring in situ two-dimensional strain fields was developed and validated for its application to cartilage mechanics. This approach combines video microscopy, optimized digital image correlation (DIC), thin-plate spline smoothing (TPSS) and generalized cross-validation (GCV) techniques to achieve the desired efficiency and accuracy. Results demonstrate that sub-pixel accuracies can be achieved for measuring tissue displacements with this methodology with a measurement uncertainty ranging from 0.25 to 0.30 pixels. The deformational gradients (from which the strains are determined) can be evaluated directly using the optimized DIC, with a measurement uncertainty of 0.017∼0.032. In actual measurements of strain in cartilage, TPSS and differentiation can be used to achieve a more accurate measurement of the gradients from the displacement data. Using this automated approach, the two-dimensional strain fields inside immature bovine carpometacarpal joint cartilage specimens under unconfined compression were characterized n=21. The depth-dependent apparent elastic modulus and Poisson’s ratio were also determined and found to be smallest at the articular surface and increasing with depth. The apparent Poisson’s ratio is found to decrease with increasing compressive strain, with values as low as 0.01 observed near the articular surface at 25% compression. The variation of the apparent Poisson’s ratio with depth is found to be consistent with a theoretical model of cartilage which accounts for the disparity in its tensile and compressive moduli.
Fuzzy models for accumulation of reported community noise annoyance from combined sources
Authors: Botteldooren Dick , Verkeyn Andy
Published: October 2002

Many scientists have investigated noise annoyance caused by combined sources. However, general annoyance reported in a social survey still has many unknown features. In this work the cognitive process involved in coming to a general noise rating based on a known, in context, rating of annoyance by particular sources is studied. A comparison of classical and fuzzy models is used for this. The new fuzzy linguistic models give a meaning to the successful strongest component or dominant source model that was used in previous work. They also explain to some extent particular features not included in that previous model. The variance not predicted by the fuzzy linguistic model is contrasted with personal data of the test subjects (age, gender, and education level) and the context of the question in the questionnaire. Only age seems to play a significant role.
INC
Authors: Yellin Daniel M. , Strom Robert E.
Published: October 2002

An incremental computation is one that is performed repeatedly on nearly identical inputs. Incremental computations occur naturally in many environments, such as compilers, language-based editors, spreadsheets, and formatters. This article describes a proposed tool for making it easy to write incremental programs. The tool consists of a programming language, INC, and a set of compile-time transformations for the primitive elements of INC. A programmer defines an algorithm in INC without regard to efficient incremental execution. The transformations automatically convert this algorithm into an efficient incremental algorithm. INC is a functional language. The implementation of an INC program is a network of processes. Each INC function is transformed into a process that receives and transmits messages describing changes to its inputs and outputs. We give an overview to the language and illustrate the incremental techniques employed by INC. We present the static and incremental complexity bounds for the primitive INC functions. We also present some example programs illustrating INC's flexibility.
The Euclidean definition of the functions div and mod
Authors: Boute Raymond T.
Published: October 2002

The definitions of the functions div and mod in the computer science literature and in programming languages are either similar to the Algol of Pascal definition (which is shown to be an unfortunate choice) or based on division by truncation (T-definition) or division by flooring as defined by Knuth (F-definition). The differences between various definitions that are in common usage are discussed, and an additional one is proposed, which is based on Euclid's theorem and therefore is called the
Euclidean
definition (E-definition). Its distinguishing feature is that 0 ≤
D
mod
d < | d |
irrespective of the signs of
D
and
d
. It is argued that the E- and F-definitions are superior to all other ones in regularity and useful mathematical properties and hence deserve serious consideration as the standard convention at the applications and language level. It is also shown that these definitions are the most suitable ones for describing number representation systems and the realization of arithmetic operations at the architecture and hardware level.
The temporal logic of actions
Authors: Lamport Leslie
Published: October 2002

The temporal logic of actions (TLA) is a logic for specifying and reasoning about concurrent systems. Systems and their properties are represented in the same logic, so the assertion that a system meets its specification and the assertion that one system implements another are both expressed by logical implication. TLA is very simple; its syntax and complete formal semantics are summarized in about a page. Yet, TLA is not just a logician's toy; it is extremely powerful, both in principle and in practice. This report introduces TLA and describes how it is used to specify and verify concurrent algorithms. The use of TLA to specify and reason about open systems will be described elsewhere.
The undecidability of aliasing
Authors: Ramalingam G.
Published: October 2002

Alias analysis is a prerequisite for performing most of the common program analyses such as reaching-definitions analysis or live-variables analysis. Landi [1992] recently established that it is impossible to compute statically precise alias information—either may-alias or must-alias—in languages with if statements, loops, dynamic storage, and recursive data structures: more precisely, he showed that the may-alias relation is not recursive, while the must-alias relation is not even recursively enumerable. This article presents simpler proofs of the same results.
Global analysis of constraint logic programs
Authors: de la Banda M. Garcia , Hermenegildo M. , Bruynooghe M. , Dumortier V. , Janssens G. , Simoens W.
Published: October 2002

This article presents and illustrates a practical approach to the dataflow analysis of constraint logic programming languages using abstract interpretation. It is first argued that, from the framework point of view, it suffices to propose relatively simple extensions of traditional analysis methods which have already been proved useful and practical and for which efficient fixpoint algorithms exist. This is shown by proposing a simple extension of Bruynooghe's traditional framework which allows it to analyze constraint logic programs. Then, and using this generalized framework, two abstract domains and their required abstract functions are presented: the first abstract domain approximates definiteness information and the second one freeness. Finally, an approach for combining those domains is proposed. The two domains and their combination have been implemented and used in the analysis of CLP(
R
) and Prolog-III applications. Results form this implementation showing its performance and accuracy are also presented.
Slicing real-time programs for enhanced schedulability
Authors: Gerber Richard , Hong Seongsoo
Published: October 2002

In this article we present a compiler-based technique to help develop correct real-time systems. The domain we consider is that of multiprogrammed real-time applications, in which periodic tasks control physical systems via interacting with external sensors and actuators. While a system is up and running, these operations must be performed as specified—otherwise the system may fail. Correctness depends not only on each program individually, but also on the time-multiplexed behavior of all of the programs running together. Errors due to overloaded resources are exposed very late in a development process, and often at runtime. They are usually remedied by human-intensive activities such as instrumentation, measurement, code tuning and redesign. We describe a static alternative to this process, which relies on well-accepted technologies from optimizing compilers and fixed-priority scheduling. Specifically, when a set of tasks are found to be overloaded, a scheduling analyzer determines candidate tasks to be transformed via program slicing. The slicing engine decomposes each of the selected tasks into two fragments: one that is “time critical” and the other “unobservable.” The unobservable part is then spliced to the end of the time-critical code, with the external semantics being maintained. The benefit is that the scheduler may postpone the unobservable code beyond its original deadline, which can enhance overall schedulability. While the optimization is completely local, the improvement is realized globally, for the entire task set.
Making graphs reducible with controlled node splitting
Authors: Janssen Johan , Corporaal Henk
Published: October 2002

Several compiler optimizations, such as data flow analysis, the exploitation of instruction-level parallelism (ILP), loop transformations, and memory disambiguation, require programs with reducible control flow graphs. However, not all programs satisfy this property. A new method for transforming irreducible control flow graphs to reducible control flow graphs, called Controlled Node Splitting (CNS), is presented. CNS duplicates nodes of the control flow graph to obtain reducible control flow graphs. CNS results in a minimum number of splits and a minimum number of duplicates. Since the computation time to find the optimal split sequence is large, a heuristic has been developed. The results of this heuristic are close to the optimum. Straightforward application of node splitting resulted in an average code size increase of 235% per procedure of our benchmark programs. CNS with the heuristic limits this increase to only 3%. The impact on the total code size of the complete programs is 13.6% for a straightforward application of node splitting. However, when CNS is used, with the heuristic the average growth in code size of a complete program dramatically reduces to 0.2%
A region inference algorithm
Authors: Tofte Mads , Birkedal Lars
Published: October 2002

Region Inference is a program analysis which infers lifetimes of values. It is targeted at a runtime model in which the store consists of a stack of regions and memory management predominantly consists of pushing and popping regions, rather than performing garbage collection. Region Inference has previously been specified by a set of inference rules which formalize when regions may be allocated and deallocated. This article presents an algorithm which implements the specification. We prove that the algorithm is sound with respect to the region inference rules and that it always terminates even though the region inference rules permit polymorphic recursion in regions. The algorithm is the result of several years of experiments with region inference algorithms in the ML Kit, a compiler from Standard ML to assembly language. We report on practical experience with the algorithm and give hints on how to implement it.
Reasoning about Grover's quantum search algorithm using probabilistic
wp
Authors: Butler Michael , Hartel Pieter
Published: October 2002

Grover's search algorithm is designed to be executed on a quantum-mechanical computer. In this article, the probabilistic
wp
-calculus is used to model and reason about Grover's algorithm. It is demonstrated that the calculus provides a rigorous programming notation for modeling this and other quantum algorithms and that it also provides a systematic framework of analyzing such algorithms.
Procedure placement using temporal-ordering information
Authors: Gloy Nikolas , Smith Michael D.
Published: October 2002

Instruction cache performance is important to instruction fetch efficiency and overall processor performance. The layout of an executable has a substantial effect on the cache miss rate and the instruction working set size during execution. This means that the performance of an executable can be improved by applying a code-placement algorithm that minimizes instruction cache conflicts and improves spatial locality. We describe an algorithm for procedure placement, one type of code placement, that signicantly differs from previous approaches in the type of information used to drive the placement algorithm. In particular, we gather temporal-ordering information that summarizes the interleaving of procedures in a program trace. Our algorithm uses this information along with cache configuration and procedure size information to better estimate the conflict cost of a potential procedure ordering. It optimizes the procedure placement for single level and multilevel caches. In addition to reducing instruction cache conflicts, the algorithm simultaneously minimizes the instruction working set size of the program. We compare the performance of our algorithm with a particularly successful procedure-placement algorithm and show noticeable improvements in the instruction cache behavior, while maintaining the same instruction working set size.
Context-sensitive synchronization-sensitive analysis is undecidable
Authors: Ramalingam G.
Published: October 2002

Static program analysis is concerned with the computation of approximations of the runtime behavior of programs. Precise information about a program's runtime behavior is, in general, uncomputable for various different reasons, and each reason may necessitate making certain approximations in the information computed. This article illustrates one source of difficulty in static analysis of concurrent programs. Specifically, the article shows that an analysis that is simultaneously both context-sensitive and synchronization-sensitive (that is, a context-sensitive analysis that precisely takes into account the constraints on execution order imposed by the synchronization statements in the program) is impossible even for the simplest of analysis problems.
Automatic Derivation of Code Generators from Machine Descriptions
Authors: Cattell R. G.
Published: October 2002

Work with compiler compilers has dealt principally with automatic generation of parsers and lexical analyzers. Until recently, little work has been done on formalizing and generating the back end of a compiler, particularly an optimizing compiler. This paper describes formalizations of machines and code generators and describes a scheme for the automatic derivation of code generators from machine descriptions. It was possible to separate all machine dependence from the code generation algorithms for a wide range of typical architectures (IBM-360, PDP-11, PDP-10, Intel 8080) while retaining good code quality. Heuristic search methods from work in artificial intelligence were found to be both fast and general enough for use in generation of code generators with the machine representation proposed. A scheme is proposed to perform as much analysis as possible at code generator generation time, resulting in a fast pattern-matching code generator. The algorithms and representations were implemented to test their practicality in use.
Ultracomputers
Authors: Schwartz Jacob T.
Published: October 2002

A class of parallel processors potentially involving thousands of individual processing elements is described. The architecture is based on the perfect shuffle connection and has two favorable characteristics: (1) Each processor communicates with a fixed number of other processors. (2) Important communication functions can be accomplished in time proportional to the logarithm of the number of processors. A number of basic algorithms for these “ultracomputers” are presented, and physical design considerations are discussed in a preliminary fashion.
Semiring-based constraint logic programming
Authors: Bistarelli Stefano , Montanari Ugo , Rossi Francesca
Published: October 2002

We extend the Constraint Logic Programming (CLP) formalism in order to handle semiring-based constraints. This allows us to perform in the same language both constraint solving and optimization. In fact, constraints based on semirings are able to model both classical constraint solving and more sophisticated features like uncertainty, probability, fuzziness, and optimization. We then provide this class of languages with three equivalent semantics: model-theoretic, fix-point, and proof-theoretic, in the style of classical CLP programs.
Procedures as persistent data objects
Authors: Atkinson Malcolm P. , Morrison Ronald
Published: October 2002

A persistent programming environment, together with a language that supports first class procedures, may be used to provide the semantic features of other object modeling languages. In particular, the two concepts may be combined to implement abstract data types, modules, separate compilation, views, and data protection. Furthermore, the ideas may be used in system construction and version control, as demonstrated here.
MULTILISP: a language for concurrent symbolic computation
Authors: Halstead Robert H.
Published: October 2002

Multilisp is a version of the Lisp dialect Scheme extended with constructs for parallel execution. Like Scheme, Multilisp is oriented toward symbolic computation. Unlike some parallel programming languages, Multilisp incorporates constructs for causing side effects and for explicitly introducing parallelism. The potential complexity of dealing with side effects in a parallel context is mitigated by the nature of the parallelism constructs and by support for abstract data types: a recommended Multilisp programming style is presented which, if followed, should lead to highly parallel, easily understandable programs.

Multilisp is being implemented on the 32-processor
Concert
multiprocessor; however, it is ultimately intended for use on larger multiprocessors. The current implementation, called
Concert Multilisp
, is complete enough to run the Multilisp compiler itself and has been run on Concert prototypes including up to eight processors. Concert Multilisp uses novel techniques for task scheduling and garbage collection. The task scheduler helps control excessive resource utilization by means of an unfair scheduling policy; the garbage collector uses a multiprocessor algorithm based on the incremental garbage collector of Baker.
Efficient and precise array access analysis
Authors: Paek Yunheung , Hoeflinger Jay , Padua David
Published: October 2002

A number of existing compiler techniques hinge on the analysis of array accesses in a program. The most important task in array access analysis is to collect the information about array accesses of interest and summarize it in some standard form. Traditional forms used in array access analysis are sensitive to the complexity of array subscripts; that is, they are usually quite accurate and efficient for simple array subscripting expressions, but lose accuracy or require potentially expensive algorithms for complex subscripts. Our study has revealed that in many programs, particularly numerical applications, many access patterns are simple in nature even when the subscripting expressions are complex. Based on this analysis, we have developed a new, general array region representational form, called the
linear memory access descriptor
(LMAD). The key idea of the LMAD is to relate all memory accesses to the linear machine memory rather than to the shape of the logical data structures of a programming language. This form helps us expose the simplicity of the actual patterns of array accesses in memory, which may be hidden by complex array subscript expressions. Our recent experimental studies show that our new representation simplifies array access analysis and, thus, enables efficient and accurate compiler analysis.
Explaining cultural differences in decision conferencing
Authors: Quaddus M.A. , Tung Lai Lai
Published: October 2002

A comparison of two cultures---Western and Asian---in the context of group conflict generation and management.
A graph-based formalism for RBAC
Authors: Koch Manuel , Mancini Luigi V. , Parisi-Presicce Francesco
Published: October 2002

Role-Based Access Control (RBAC) is supported directly or in a closely related form, by a number of products. This article presents a formalization of RBAC using graph transformations that is a graphical specification technique based on a generalization of classical string grammars to nonlinear structures. The proposed formalization provides an intuitive description for the manipulation of graph structures as they occur in information systems access control and a precise specification of static and dynamic consistency conditions on graphs and graph transformations. The formalism captures the RBAC models published in the literature, and also allows a uniform treatment of user roles and administrative roles, and a detailed analysis of the decentralization of administrative roles.
Physiological measures of presence in stressful virtual environments
Authors: Meehan Michael , Insko Brent , Whitton Mary , Brooks Frederick P.
Published: October 2002

A common measure of the quality or effectiveness of a virtual environment (VE) is the mount of
presence
it evokes in users. Presence is often defined as the sense of
being there
in a VE. There has been much debate about the best way to measure presence, and presence researchers need, and have sought, a measure that is
reliable, valid, sensitive, and objective.
We hypothesized that to the degree that a VE seems real, it would evoke physiological responses similar to those evoked by the corresponding real environment, and that greater presence would evoke a greater response. To examine this, we conducted three experiments, the results of which support the use of physiological reaction as a reliable, valid, sensitive, and objective presence measure. The experiments compared participants' physiological reactions to a non-threatening virtual room and their reactions to a stressful virtual height situation. We found that change in heart rate satisfied our requirements for a measure of presence, change in skin conductance did to a lesser extent, and that change in skin temperature did not. Moreover, the results showed that inclusion of a passive haptic element in the VE significantly increased presence and that for presence evoked: 30FPS > 20FPS > 15FPS.
A year after 9/11
Authors: Davies Simon
Published: October 2002

The dissention over technology has migrated from the East to the West over the last 12 months.
Mobile instant messaging through Hubbub
Authors: Isaacs Ellen , Walendowski Alan , Ranganathan Dipti
Published: October 2002

Associating online buddies with musical notes, Hubbub lets users (on both PCs and handhelds) interact by way of opportunistic impromptu exchanges, even as they move about.
Engaging students with theory through ACM collegiate programming contest
Authors: Shilov Nikolay V. , Yi Kwangkeun
Published: October 2002

How formal methods can be presented in a popular---but mathematically sound---manner to undergraduate students of various disciplines.
Design, implementation and testing of extended and mixed precision BLAS
Authors: Li Xiaoye S. , Demmel James W. , Bailey David H. , Henry Greg , Hida Yozo , Iskandar Jimmy , Kahan William , Kang Suh Y. , Kapur Anil , Martin Michael C. , Thompson Brandon J. , Tung Teresa , Yoo Daniel J.
Published: October 2002

This article describes the design rationale, a C implementation, and conformance testing of a subset of the new Standard for the BLAS (Basic Linear Algebra Subroutines): Extended and Mixed Precision BLAS. Permitting higher internal precision and mixed input/output types and precisions allows us to implement some algorithms that are simpler, more accurate, and sometimes faster than possible without these features. The new BLAS are challenging to implement and test because there are many more subroutines than in the existing Standard, and because we must be able to assess whether a higher precision is used for internal computations than is used for either input or output variables. We have therefore developed an automated process of generating and systematically testing these routines. Our methodology is applicable to languages besides C. In particular, our algorithms used in the testing code will be valuable to all other BLAS implementors. Our extra precision routines achieve excellent performance---close to half of the machine peak Megaflop rate even for the Level 2 BLAS, when the data access is stride one.
Top-
k
selection queries over relational databases
Authors: Bruno Nicolas , Chaudhuri Surajit , Gravano Luis
Published: October 2002

In many applications, users specify target values for certain attributes, without requiring exact matches to these values in return. Instead, the result to such queries is typically a rank of the "top
k
" tuples that best match the given attribute values. In this paper, we study the advantages and limitations of processing a top-
k
query by translating it into a single range query that a traditional relational database management system (RDBMS) can process efficiently. In particular, we study how to determine a range query to evaluate a top-
k
query by exploiting the statistics available to an RDBMS, and the impact of the quality of these statistics on the retrieval efficiency of the resulting scheme. We also report the first experimental evaluation of the mapping strategies over a real RDBMS, namely over Microsoft's SQL Server 7.0. The experiments show that our new techniques are robust and significantly more efficient than previously known strategies requiring at least one sequential scan of the data sets.
Scheduling expressions on a pipelined processor with a maximal delay of one cycle
Authors: Bernstein David , Gertner Izidor
Published: October 2002

Consider a pipelined machine that can issue instructions every machine cycle. Sometimes, an instruction that uses the result of the instruction preceding it in a pipe must be delayed to ensure that a program computes a right value. We assume that issuing of such instructions is delayed by at most
one
machine cycle. For such a machine model, given an unbounded number of machine registers and memory locations, an algorithm to find a shortest schedule of the given expression is presented and analyzed. The proposed algorithm is a modification of Coffman-Graham's algorithm [7], which provides an optimal solution to the problem of scheduling tasks on two parallel processors.
Correctness proofs of distributed termination algorithms
Authors: Apt Krzysztof R.
Published: October 2002

The problem of correctness of the solutions to the distributed termination problem of Francez [7] is addressed. Correctness criteria are formalized in the customary framework for program correctness. A very simple proof method is proposed and applied to show correctness of a solution to the problem. It allows us to reason about liveness properties of temporal logic (see, e.g., Manna and Pnueli [12]) using a new notion of
weak total correctness
.
Generating editing environments based on relations and attributes
Authors: Horwitz Susan , Teitelbaum Tim
Published: October 2002

The ability to generate language-based editors depends on the existence of a powerful, language-independent model of editing. A model is proposed in which programs are represented as attributed abstract-syntax trees with an associated relational database. Relations can depend on the state of the attributed tree, and attributes can depend on the values in relations, provided there are no circular dependencies.

The power and the limitations of relational operations are demonstrated with respect to the support of static-semantic checking, anomaly detection, an interrogation facility, and the ability to define alternative program displays. The advantages of the hybrid system over both the purely relational and purely attribute-based systems are presented, and new algorithms are given for query evaluation and incremental view updating motivated by the efficiency requirements of interactive editing under the defined model. A prototype implementation of an editor generator is described, and suggestions for future research are made.
Influence of Leptin on Arterial Distensibility
Authors: Singhal Atul , Farooqi I. Sadaf , Cole Tim J. , O’Rahilly Stephen , Fewtrell Mary , Kattenhorn Mia , Lucas Alan , Deanfield John
Published: October 2002

Background—

The mechanisms by which obesity increases the risk of atherosclerotic cardiovascular disease (CVD) are poorly understood. In experimental models, leptin, a hormone produced by adipose tissue, has been shown adversely to affect vascular health. Therefore, we tested the hypothesis that high leptin concentrations are associated with lower arterial distensibility, an index of circulatory function relevant to the atherosclerotic process.

Methods and Results—

Noninvasive, high-resolution, vascular ultrasound was used to measure brachial artery distensibility in 294 healthy adolescents (aged 13 to 16 years) who had a broad range of body mass indexes. Fat mass was measured by bioelectric impedance analysis; fasting serum leptin concentration by radioimmunoassay; and lipid profile, fasting insulin, glucose, and C-reactive protein concentrations by standard laboratory techniques. Higher leptin concentrations were associated with impaired arterial distensibility (regression coefficient, −1.3% change in arterial distension per 10% increase in leptin; 95% CI, −1.9% to −0.8%;
P
<0.001). This association was independent of fat mass, blood pressure, and C-reactive protein, fasting insulin, or LDL cholesterol concentrations.

Conclusions—

Elevation in leptin was associated with impaired vascular function, independent of the metabolic and inflammatory disturbances associated with obesity. Our observations are consistent with data from experimental models and suggest that high leptin concentration is an important mechanism for the adverse influence of body fatness on CVD.
Anatomic Variability in Coronary Arterial Distribution With Regard to the Arterial Switch Procedure
Authors: Massoudy Parwis , Baltalarli Ahmet , de Leval Marc R. , Cook Andrew , Neudorf Ulrich , Derrick Graham , McCarthy Karen P. , Anderson Robert H.
Published: October 2002

Background—

We investigated the coronary arterial origins and course and the position of the great arteries in hearts with discordant ventriculoarterial connections. At the same time, we sought to evaluate the practicality of alphanumeric classifications in accounting for surgically relevant features of the coronary arteries.

Methods and Results—

We studied 200 postmortem hearts, noting the patterns of coronary arterial branching, the vertical and horizontal location of the arterial orifices within the aortic sinuses, the course of the proximal coronary arteries in relation to the aortic wall, and the relations of the great arteries and their respective commissures. All hearts examined had concordant atrioventricular and discordant ventriculoarterial connections. We found 7 of the 8 predicted patterns for sinusal origin of the 3 major coronary arteries and identified 5 different positions of the arterial trunks relative to each other. A correlation was found between less frequent relationships of the arterial trunks and unusual patterns of coronary arterial branching, as well as with mismatch between the valvar commissures.

Conclusions—

The surgically relevant features of the coronary arteries in hearts with discordant ventriculoarterial connections are best described rather than classified. Correlations exist between certain, less frequent relations of the great arteries and unusual patterns of branching of the coronary arteries. The presence of unusual great arterial positions should alert the surgeon to potentially complicated arrangements of the origin and distribution of the coronary arteries.
KronoScope: The Beginning
Authors: Soulsby Marlene
Published: October 2002

Time bears a unique and direct pertinence to all human concerns. It is a fundamental feature of the physical universe, of the life process, of the functions of the mind, and of collective behavior. In humans, temporal experience is all pervasive, intimate and immediate. Life, death and time combine in a dynamic unity that has been of concern to all great philosophies, religions, and to the arts and the humanities.
A Comparative Study of Copper and Zinc Ion Adsorption on to Activated and Non-activated Date-pits
Authors: Banat Fawzi , Al-Asheh Sameer , Al-Rousan Deaa
Published: October 2002

Date-pits (an agricultural by-product available commercially) were utilized, with and without activation, as an adsorbent for the removal of Zn2+ and Cu2+ ions from aqueous solutions. Activated carbons were prepared from date-pits by carbon dioxide activation at 700°C. The effects of contact time, pH, temperature and the adsorbent concentration on the removal of Zn2+ and Cu2+ ions were studied. The Freundlich isotherm model described the equilibrium adsorption data. Non-activated date-pits exhibited higher Zn2+ and Cu2+ ion uptake than activated date-pits. The uptake of Cu2+ ions by both activated and non-activated date-pits was higher than the uptake of Zn2+ ions. The uptake of both metal ions increased on increasing the pH value of the system from 3.5 to 5.0 as well as on decreasing the temperature from 50°C to 25°C. Adsorption capacities for the non-activated date-pits towards Cu2+ and Zn2+ ions as high as 0.15 mmol/g and 0.09 mmol/g, respectively, were observed. This study demonstrated that date-pits without any physical or chemical pretreatment could be used as an effective adsorbent for the treatment of waters containing heavy metal ions such as Zn2+ and Cu2+.
Multicomponent Adsorption of Butane, NO2 and SO2 on Activated Carbon
Authors: Ahnert Falk , Heschel Wolfgang
Published: October 2002

Dynamic adsorption experiments have been carried out with the help of an FT-IR (Fourier-Transform InfraRed) spectrometer. Fixed bed adsorption breakthrough curves were obtained for n-butane, SO2 and NO2 gases as well as for the reaction products NO, N2O and CO2. The adsorption of SO2 and NO2 on activated carbon was studied both during single- and co-adsorption experiments at 30°C. The activated carbon used exhibited a disadvantage towards NO2 adsorption in that it was partly converted to NO and immediately desorbed as NO. A further reaction to N2O could also be observed. The activated carbon was rapidly altered and lost a notable part of its loading capacity as a result of the presence of water and oxygen. During co-adsorption, SO2 reacted with NO2 (both as adsorbed species) and produced an additional amount of NO. An ash-tree spherical activated carbon with an extended surface area (1000 m2/g) was used in all experiments.