bluuebunny/crossref_metadata_2025 huggingface dataset:
Group communication specifications
Authors: Chockler Gregory V. , Keidar Idit , Vitenberg Roman
Published: July 2002

View-oriented group communication is an important and widely used
building block for many distributed applications. Much current
research has been dedicated to specifying the semantics and
services of view-oriented group communication systems (GCSs).
However, the guarantees of different GCSs are formulated using
varying terminologies and modeling techniques, and the
specifications vary in their rigor. This makes it difficult to
analyze and compare the different systems. This survey provides a
comprehensive set of clear and rigorous specifications, which may
be combined to represent the guarantees of most existing GCSs. In
the light of these specifications, over 30 published GCS
specifications are surveyed. Thus, the specifications serve as a
unifying framework for the classification, analysis, and comparison
of group communication systems. The survey also discusses over a
dozen different applications of group communication systems,
shedding light on the usefulness of the presented specifications.
This survey is aimed at both system builders and theoretical
researchers. The specification framework presented in this article
will help builders of group communication systems understand and
specify their service semantics; the extensive survey will allow
them to compare their service to others. Application builders will
find a guide here to the services provided by a large variety of
GCSs, which could help them choose the GCS appropriate for their
needs. The formal framework may provide a basis for interesting
theoretical work, for example, analyzing relative strengths of
different properties and the costs of implementing them.
A computer science perspective of bridge design
Authors: Spector Alfred , Gifford David
Published: July 2002

What kinds of lessons does a classical engineering discipline like bridge design have for an emerging engineering discipline like computer systems design? Case-study editors Alfred Spector and David Gifford consider the insight and experience of bridge designer Gerard Fox to find out how strong the parallels are.
Object lens: a “spreadsheet” for cooperative work
Authors: Lai Kum-Yew , Malone Thomas W. , Yu Keh-Chiang
Published: July 2002

Object Lens allows unsophisticated computer users to create their own cooperative work applications using a set of simple, but powerful, building blocks. By defining and modifying templates for various semistructured objects, users can represent information about people, tasks, products, messages, and many other kinds of information in a form that can be processed intelligently by both people and their computers. By collecting these objects in customizable folders, users can create their own displays which summarize selected information from the objects in table or tree formats. Finally, by creating semiautonomous agents, users can specify rules for automatically processing this information in different ways at different times.

The combination of these primitives provides a single consistent interface that integrates facilities for object-oriented databases, hypertext, electronic messaging, and rule-based intelligent agents. To illustrate the power of this combined approach, we describe several simple examples of applications (such as task tracking, intelligent message routing, and database retrieval) that we have developed in this framework.
A unified approach to approximation algorithms for bottleneck problems
Authors: Hochbaum Dorit S. , Shmoys David B.
Published: July 2002

In this paper a powerful, and yet simple, technique for devising approximation algorithms for a wide variety of NP-complete problems in routing, location, and communication network design is investigated. Each of the algorithms presented here delivers an approximate solution guaranteed to be within a constant factor of the optimal solution. In addition, for several of these problems we can show that unless P = NP, there does not exist a polynomial-time algorithm that has a better performance guarantee.
Module algebra
Authors: Bergstra J. A. , Heering J. , Klint P.
Published: July 2002

An axiomatic algebraic calculus of modules is given that is based on the operators
combination/union, export, renaming,
and
taking the visible signature
. Four different models of module algebra are discussed and compared.
The Languages of New Guinea
Authors: Foley William A.
Published: July 2002

▪ Abstract  The New Guinea region is the most linguistically diverse region in the world, with some 1000 languages in an area smaller than 900,000 km2. There are about three dozen language families and close to the same number of language isolates, although two very different language families, each with about 300 languages, dominate: the coastal Austronesian languages, and the montane Trans New Guinea family. The other, smaller families are largely restricted to the northern lowlands. Typologically, the languages exhibit enormous variation and many unusual properties. Vowel systems in which central vowels predominate and consonantal systems lacking fricatives and, rarer still, nasals are attested. Morphological types range from isolating to polysynthetic, and most languages are head marking. Verbs normally carry more complex inflection than do nouns. Of nominal categories, gender is often exuberantly elaborated, but surprisingly case is not, the weak development being an areal feature, in contrast to Australian languages on the one hand and those of Eurasia on the other. Syntactically, languages fall into left-headed and right-headed types, represented by Austronesian and Trans New Guinea, respectively. Clause chaining and associated morphological structures such as switch reference are a salient feature of right-headed and particularly Trans New Guinea languages. Discourse structures are often highly elliptical, with the verbal morphology providing signals for the recovery of elided information and the cohesion of the text. Highly ritualized texts, such as songs, are characterized by strict formal rules of parallelism and trope usage. Other than Austronesian, no language family has congeners outside the region, and within it, large-scale processes of convergence have shaped languages over many millennia, giving rise to areal traits.
Bioarchaeology of the African Diaspora in the Americas: Its Origins and Scope
Authors: Blakey Michael L.
Published: July 2002

▪ Abstract  The results of over 70 years of African Diasporic bioarchaeology are discussed and explained as emerging from distinct interests and traditions of African Diasporan studies, sociocultural anthropology, history, physical anthropology, and archaeology, in that chronological order. Physical anthropology is the core discipline of African-American bioarchaeology, yet it has been the least informed by cultural and historical literatures. Forensic approaches to bioarchaeology construct a past that fails to be either cultural or historical, while biocultural approaches are emerging that construct a more human history of African Diasporic communities. The involvement of African Americans, both as clients and as sources of scholarship, has begun to transform bioarchaeology as in the example of the New York African Burial Ground. The social history of the field examined here emphasizes the scholarship of diasporans themselves, and critiques a bioarchaeology that, until recently, has had little relevance to the people whose history bioarchaeologists construct.
THE CHLOROPLAST ATP SYNTHASE: A Rotary Enzyme?
Authors: McCarty R. E. , Evron Y. , Johnson E. A.
Published: July 2002

▪ Abstract  The chloroplast adenosine triphosphate (ATP) synthase is located in the thylakoid membrane and synthesizes ATP from adenosine diphosphate and inorganic phosphate at the expense of the electrochemical proton gradient formed by light-dependent electron flow. The structure, activities, and mechanism of the chloroplast ATP synthase are discussed. Emphasis is given to the inherent structural asymmetry of the ATP synthase and to the implication of this asymmetry to the mechanism of ATP synthesis and hydrolysis. A critical evaluation of the evidence in support of and against the notion that one part of the enzyme rotates with respect to other parts during catalytic turnover is presented. It is concluded that although rotation can occur, whether it is required for activity of the ATP synthase has not been established unequivocally.
THEORY OF ACCRETION DISKS II: Application to Observed Systems
Authors: Lin D.N.C. , Papaloizou J.C.B.
Published: July 2002

▪ Abstract  Accretion disks are important for many astrophysical phenomena, including galactic nuclei, interacting binary stars, and young stellar objects. The central issue in the theory of accretion disks is to identify the dominant mechanisms that regulate angular momentum transfer and mass flow in a variety of contexts. In the first part of this review, we described some recent advances in the study of the physical processes that may be present in accretion disks. Concurrent with these theoretical developments, the arrival of high-resolution astronomical instruments has led to explosive progress on the observational side. In many cases, the study of accretion disks has evolved from their inferred presence based on circumstantial evidence to direct imaging and detailed spectral analyses. Here, we summarize the theoretical interpretation of these data. We review the constraints that may be imposed on the efficiency and nature of angular momentum transfer processes in a variety of astrophysical contexts.
RNP Localization and Transport in Yeast
Authors: Chartrand Pascal , Singer Robert H. , Long Roy M.
Published: July 2002

▪ Abstract  The localization of mRNAs is used by various types of polarized cells to locally translate specific proteins, which restricts their distribution to a particular sub-region of the cytoplasm. This mechanism of protein sorting is involved in major biological processes such as asymmetric cell division, oogenesis, cellular motility, and synapse formation. With the finding of localized mRNAs in the yeast Saccharomyces cerevisiae, it is now possible to benefit from the powerful yeast laboratory tools to explore the molecular basis of RNA localization. Because mRNA transport and localization in yeast share many features with RNA localization in higher eukaryotes, including the formation of a large ribonucleoprotein (RNP) localization complex, the requirement of a polarized cytoskeleton and molecular motors, and the role of nuclear RNA-binding proteins in cytoplasmic localization, the yeast can be used as a paradigm for unraveling the molecular aspects of this process. This review summarizes the current knowledge on RNP transport and localization in yeast.
Climate Reconstruction from Subsurface Temperatures
Authors: Pollack Henry N. , Huang Shaopeng
Published: July 2002

Temperature changes at the Earth’s surface propagate downward into the subsurface and impart a thermal signature to the rocks. This signature can be measured in boreholes and then analyzed to reconstruct the surface temperature history over the past several centuries. The ability to resolve surface temperature history from subsurface temperatures diminishes with time. Microclimatic effects associated with the topography and vegetation patterns at the site of a borehole, along with local anthropogenic perturbations associated with land use change, can obscure the regional climate change signal. Regional and global ensembles of boreholes reveal the broader patterns of temperature changes at the Earth’s surface. The average surface temperature of the continents has increased by about 1.0 K over the past 5 centuries; half of this increase has occurred in the twentieth century alone.
VORTEX-BODY INTERACTIONS
Authors: Rockwell Donald
Published: July 2002

▪ Abstract  Interaction of a vortex, or combinations of them, with a cylinder, blade, or foil may involve both rapid distortion of the incident vorticity field and shedding of vorticity from the surface of the body. This review focuses on the underlying flow physics, with the aim of clarifying the origin of the induced loading. In the case of near or direct encounter of the incident vortex, the relation between three-dimensional features of the flow structure and the local loading poses interesting challenges for further research. With recently developed simulation and laboratory techniques, opportunities now exist to determine the instantaneous quantitative structure of these complex distortions and to interpret them within a theoretical, vorticity-based framework. Effective control of vortex interactions appears to be attainable. It will be necessary, however, to develop creative strategies, distinct from those traditionally employed for control of unstable shear flows.
SPIN-UP OF HOMOGENEOUS AND STRATIFIED FLUIDS
Authors: Duck PW , Foster MR
Published: July 2002

▪ Abstract  We consider the manner in which a container filled with viscous fluid adjusts to changes in its rotation rate. We begin with homogeneous flows involving small departures in rotation rate from an initial state of solid-body rotation in an axisymmetric container. This is followed by a summary of other more recent developments, including weakly and fully nonlinear calculations and comparison with experiment and the question of spin-down. The question of “spin-over” is addressed, followed by a brief synopsis of free-surface effects, and a discussion of nonaxisymmetric spin-up. The second part of the review focuses on the effects of stratification on the spin-up process. Linearized (low Rossby number) spin-up within a cylindrical container is described. Thereafter, both experimental and nonlinear computational results are described and compared. The final section focuses on stratified spin-up and spin-down in conical geometries, and a number of comparisons between theory and experiment are given.
CONSEQUENCES OF CHROMOSOMAL ABNORMALITIES IN TUMOR DEVELOPMENT
Authors: Sánchez-García I.
Published: July 2002

▪ Abstract  This article highlights recent advances in the molecular structure and function of proteins that are activated or created by chromosomal abnormalities and discusses their possible role in tumor development. The molecular characterization of these proteins has revealed that tumor-specific fusion proteins are the consequence of most chromosome translocations associated with leukemias and solid tumors. An emerging common theme is that creation of these proteins disrupts the normal development of tumor-specific target cells by blocking apoptosis. These insights identify these chromosomal translocation-associated genes as potential targets for improved cancer therapies.
THE CRITICAL ROLE OF CHROMOSOME TRANSLOCATIONS IN HUMAN LEUKEMIAS
Authors: Rowley Janet D.
Published: July 2002

▪ Abstract  Many chromosome abnormalities, especially translocations or inversions, are closely associated with a particular morphologic or phenotypic subtype of leukemia, lymphoma, or sarcoma. Cloning the genes at the breakpoints of these rearrangements has had a major impact on our understanding of the molecular biology of cancer. One such gene is MLL (myeloid-lymphoid or mixed lineage leukemia) located at chromosome band 11q23. The target gene(s) of MLL is unknown at present, but because of its homology to the trithorax gene in Drosophila as well as experimental data from mice, it appears to be involved in maintaining the function of some of the homeobox genes. Most genes involved in translocations have homologs in other organisms. Comparison of the functions of these genes in human cells with their function in other systems has enriched our understanding of their role in cell biology.
Producing Nature’s Gene-Chips: The Generation of Peptides for Display by MHC Class I Molecules
Authors: Shastri Nilabh , Schwab Susan , Serwold Thomas
Published: July 2002

Gene-chips contain thousands of nucleotide sequences that allow simultaneous analysis of the complex mixture of RNAs transcribed in cells. Like these gene-chips, major histocompatibility complex (MHC) class I molecules display a large array of peptides on the cell surface for probing by the CD8+T cell repertoire. The peptide mixture represents fragments of most, if not all, intracellular proteins. The antigen processing machinery accomplishes the daunting task of sampling these proteins and cleaving them into the precise set of peptides displayed by MHC I molecules. It has long been believed that antigenic peptides arose as by-products of normal protein turnover. Recent evidence, however, suggests that the primary source of peptides is newly synthesized proteins that arise from conventional as well as cryptic translational reading frames. It is increasingly clear that for many peptides the C-terminus is generated in the cytoplasm, and N-terminal trimming occurs in the endoplasmic reticulum in an MHC I–dependent manner. Nature's gene-chips are thus both parsimonious and elegant.
THE ROLE OF CATHETER-DIRECTED THERAPIES IN THE TREATMENT OF CONGENITAL HEART DISEASE
Authors: Rome, M.D Jonathan J.
Published: July 2002

▪ Abstract  Over the past decade, transcatheter interventions have become increasingly important in the treatment of patients with congenital heart defects. These procedures may be broadly grouped as dilations (valvuloplasty, angioplasty, and endovascular stenting) or as closures (vascular embolizations and device closure of defects). Balloon valvuloplasty has become the treatment of choice for simple valvar pulmonic stenosis in all age groups and, although not curative, appears at least comparable to surgery for noncalcific aortic stenosis in newborns through young adults. Balloon angioplasty is successfully applied to a wide range of aortic, pulmonry artery, and venous stenoses. Catheter-delivered coils are used to embolize a wide range of arterial, venous, and prosthetic vascular connections. Although still investigational, devices have been successfully used for closure of large numbers of atrial and ventricular septal defects.

In this review, the current role of each major catheter intervention is discussed and results are compared with alternative forms of therapy. Catheter-based therapeutics are then placed in context in a discussion of combined catheter-surgical treatment of patients with complex congenital heart defects.
The Extracellular Calcium-Sensing Receptor: Its Role in Health and Disease
Authors: Brown, MD Edward M. , Pollak, MD Martin , Hebert, MD Steven C.
Published: July 2002

The recent cloning of an extracellular calcium (Ca2+o)-sensing receptor (CaR) from parathyroid, kidney and other cell types has clarified the mechanisms through which Ca2+oexerts its direct actions on various cells and tissues. In the parathyroid, the CaR mediates the inhibitory effects of Ca2+oon parathyroid hormone (PTH) secretion and likely on expression of the PTH gene and parathyroid cellular proliferation. In the kidney, the receptor mediates direct inhibition of the reabsorption of divalent cations in the cortical thick ascending limb, and it likely underlies the inhibitory actions of hypercalcemia on the urinary-concentrating mechanism in the medullary thick ascending limb and inner medullary collecting duct. The identification of inherited diseases of Ca2+o-sensing that arise from mutations in the CaR gene has proven, by genetic means, the central role of the CaR in mineral ion homeostasis and the importance of the receptor in regulating the parathyroid and kidney. An allosteric CaR agonist (“calcimimetic”) is currently being tested for the treatment of primary hyperparathyroidism, and CaR-based therapeutics will likely be applicable to other disorders in which CaRs are under- or overactive. Thus the discovery of the CaR and its associated diseases has documented that Ca2+oplays an essential role as an extracellular first messenger, in addition to serving its better recognized role as an intracellular second messenger.
BIOSYNTHESIS OF HALOGENATED METABOLITES BY BACTERIA
Authors: van Pée Karl-Heinz
Published: July 2002

Halogenated metabolites, originally thought to be infrequent in nature, are actually nothing unusual at all, and are produced by many different organisms, including bacteria. Whereas marine bacteria usually produce brominated compounds, terrestrial bacteria preferentially synthesize chlorometabolites, but fluoro- and iodometabolites can also be found. Haloperoxidases, enzymes capable of catalyzing the formation of carbon halogen bonds in the presence of hydrogen peroxide and halide ions (Cl−, Br− and I−) have been isolated and characterized from different bacteria. These enzymes turned out to be very unspecific and are obviously not the type of halogenating enzymes responsible for the formation of halometabolites in bacteria. A yet-unknown type of halogenating enzyme having both substrate and regio-specificity must be involved in the biosynthesis of halogenated compounds.
REGULATION OF ACETATE METABOLISM BY PROTEIN PHOSPHORYLATION IN ENTERIC BACTERIA
Authors: Cozzone Alain J.
Published: July 2002

▪ Abstract  Growth of enteric bacteria on acetate as the sole source of carbon and energy requires operation of a particular anaplerotic pathway known as the glyoxylate bypass. In this pathway, two specific enzymes, isocitrate lyase and malate synthase, are activated to divert isocitrate from the tricarboxylic acid cycle and prevent the quantitative loss of acetate carbons as carbon dioxide. Bacteria are thus supplied with the metabolic intermediates they need for synthesizing their cellular components. The channeling of isocitrate through the glyoxylate bypass is regulated via the phosphorylation/dephosphorylation of isocitrate dehydrogenase, the enzyme of the tricarboxylic acid cycle which competes for a common substrate with isocitrate lyase. When bacteria are grown on acetate, isocitrate dehydrogenase is phosphorylated and, concomitantly, its activity declines drastically. Conversely, when cells are cultured on a preferred carbon source, such as glucose, the enzyme is dephosphorylated and recovers full activity. Such reversible phosphorylation is mediated by an unusual bifunctional enzyme, isocitrate dehydrogenase kinase/phosphatase, which contains both modifying and demodifying activities on the same polypeptide. The genes coding for malate synthase, isocitrate lyase, and isocitrate dehydrogenase kinase/phosphatase are located in the same operon. Their expression is controlled by a complex dual mechanism that involves several transcriptional repressors and activators. Recent developments have brought new insights into the nature and mode of action of these different regulators. Also, significant advances have been made lately in our understanding of the control of enzyme activity by reversible phosphorylation. In general, analyzing the physiological behavior of bacteria on acetate provides a valuable approach for deciphering at the molecular level the mechanisms of cell adaptation to the environment.
PERSPECTIVES ON NUTRITIONAL IRON DEFICIENCY
Authors: Hallberg Leif
Published: July 2002

Nutritional iron deficiency (ID) is caused by an intake of dietary iron insufficient to cover physiological iron requirements. Studies on iron absorption from whole diets have examined relationships between dietary iron bioavailability/absorption, iron losses, and amounts of stored iron. New insights have been obtained into regulation of iron absorption and expected rates of changes of iron stores or hemoglobin iron deficits when bioavailability or iron content of the diet has been modified and when losses of iron occur. Negative effects of ID are probably related to age, up to about 20 years, explaining some of earlier controversies. Difficulties in establishing the prevalence of mild ID are outlined. The degree of underestimation of the prevalence of mild ID when using multiple diagnostic criteria is discussed. It is suggested that current low-energy lifestyles are a common denominator for the current high prevalence not only of ID but also of obesity, diabetes, and osteoporosis.

[Figure: see text]
5-ht6 Receptors as Emerging Targets for Drug Discovery
Authors: Branchek Theresa A. , Blackburn Thomas P.
Published: July 2002

5-ht6 receptors are the latest serotonin receptors to be identified by molecular cloning. Their high affinity for a wide range of drugs used in psychiatry, coupled with their intriguing distribution in the brain, has stimulated significant interest. Antisense oligonucleotides, antipeptide antibodies, selective radioligands, knockout mice, and selective antagonists of the 5-ht6 receptor have recently become available. Surprisingly, 5-ht6 receptors appear to regulate cholinergic neurotransmission in the brain, rather than the expected interaction as modulators of dopaminergic transmission. This interaction predicts a possible role for 5-ht6 receptor antagonists in the treatment of learning and memory disorders. Furthermore, polymorphisms in the sequence of the 5-ht6 receptor gene may provide a genetic tool to further our understanding of the differential responses of patients to antipsychotic medications.
Phenobarbital Response Elements of Cytochrome P450 Genes and Nuclear Receptors
Authors: Sueyoshi T , Negishi M
Published: July 2002

Phenobarbital (PB) response elements are composed of various nuclear receptor (NR)-binding sites. A 51-bp distal element PB-responsive enhancer module (PBREM) conserved in the PB-inducible CYP2B genes contains two NR-binding direct repeat (DR)-4 motifs. Responding to PB exposure in liver, the NR constitutive active receptor (CAR) translocates to the nucleus, forms a dimer with the retinoid X receptor (RXR), and activates PBREM via binding to DR-4 motifs. For CYP3A genes, a common NR site [DR-3 or everted repeat (ER)-6] is present in proximal promoter regions. In addition, the distal element called the xenobiotic responsive module (XREM) is found in human CYP3A4 genes, which contain both DR-3 and ER-6 motifs. Pregnane X receptor (PXR) could bind to all of these sites and, upon PB induction, a PXR:RXR heterodimer could transactivate XREM. These response elements and NRs are functionally versatile, and capable of responding to distinct but overlapping groups of xenochemicals.
Physiological Functions of Cyclic ADP-Ribose and NAADP as Calcium Messengers
Authors: Lee Hon Cheung
Published: July 2002

Cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP) are two Ca2+messengers derived from NAD and NADP, respectively. Although NAADP is a linear molecule, structurally distinct from the cyclic cADPR, it is synthesized by similar enzymes, ADP-ribosyl cyclase and its homolog, CD38. The crystal structure of the cyclase has been solved and its active site identified. These two novel nucleotides have now been shown to be involved in a wide range of cellular functions including: cell cycle regulation in Euglena, a protist; gene expression in plants; and in animal systems, from fertilization to neurotransmitter release and long-term depression in brain. A battery of pharmacological reagents have been developed, providing valuable tools for elucidating the physiological functions of these two novel Ca2+messengers. This article reviews these recent results and explores the implications of the existence of multiple Ca2+messengers and Ca2+stores in cells.
Cellular Mechanisms for the Repression of Apoptosis
Authors: Bortner Carl D. , Cidlowski John A.
Published: July 2002

Apoptosis, also known as programmed cell death, is a ubiquitous mode of cell death known to play an important role during embryogenesis, development, and adult cellular homeostasis. Disruption of this normal physiological cell death process can result in either excessive or insufficient apoptosis, which can lead to various disease states and pathology. Since most cells contain the machinery that brings about apoptosis, it is clear that living cells must contain inherent repressive mechanisms to keep the death process in check. In this review, we examine several modes of repression of apoptosis that exist in cells.
SINGLE-MOLECULE SPECTROSCOPY
Authors: Plakhotnik Taras , Donley Elizabeth A. , Wild Urs P.
Published: July 2002

▪ Abstract  Recent experimental and theoretical studies concerning single-molecule spectroscopy in solids are discussed. Pure quantum effects—such as photon bunching, antibunching, and spectral jumps—and more classical phenomena—such as near-field excitation, saturation, ac/dc Stark shifts, spectral diffusion, two-photon excitation, and customary spectroscopic analysis—are considered. The emphasis of this review is on physical results and their interpretation. This is preceded by a general introduction, where fundamentals of single-molecule spectroscopy are explained.
CHEMICAL REACTION DYNAMICS BEYOND THE BORN-OPPENHEIMER APPROXIMATION
Authors: Butler Laurie J.
Published: July 2002

▪ Abstract  To predict the branching between energetically allowed product channels, chemists often rely on statistical transition state theories or exact quantum scattering calculations on a single adiabatic potential energy surface. The potential energy surface gives the energetic barriers to each chemical reaction and allows prediction of the reaction rates. Yet, chemical reactions evolve on a single potential energy surface only if, in simple terms, the electronic wavefunction can evolve from the reactant electronic configuration to the product electronic configuration on a time scale that is fast compared to the nuclear dynamics through the transition state. The experiments reviewed here investigate how the breakdown of the Born-Oppenheimer approximation at a barrier along an adiabatic reaction coordinate can alter the dynamics of and the expected branching between molecular dissociation pathways. The work reviewed focuses on three questions that have come to the forefront with recent theory and experiments: Which classes of chemical reactions evidence dramatic nonadiabatic behavior that influences the branching between energetically allowed reaction pathways? How do the intramolecular distance and orientation between the electronic orbitals involved influence the nonadiabaticity in the reaction? How can the detailed nuclear dynamics mediate the effective nonadiabatic coupling encountered in a chemical reaction?
Theoretical Studies of Atomic-Scale Processes Relevant to Crystal Growth
Authors: Jónsson Hannes
Published: July 2002

The study of adsorption, diffusion, island formation, and interlayer transport of atoms on a growing surface has been an active field in the past decade, because of both experimental and theoretical advances. Experiments can give detailed images of patterns formed on growing surfaces. An important challenge to the theoretical studies is the identification of dynamical processes controlling the pattern formation and overall surface morphology. This can be achieved by accurate modeling of the atomic interactions, a thorough search for active atomic-scale processes, and simulation of the growth on the experimental timescale to allow for detailed comparison with the experimental measurements. An overview of some of the theoretical methodology used in these studies and results obtained for one of the most extensively studied systems, Pt(111), is given here. A remarkable richness of phenomena has emerged from these studies, where apparently small effects can shift the balance between competing molecular processes and thereby change the morphology of a growing surface. The article concludes with a discussion of possible future directions in this research area.
Barley Yellow Dwarf Viruses
Authors: Miller and  W. Allen , Rasochová Lada
Published: July 2002

Barley yellow dwarf viruses represent one of the most economically important and ubiquitous groups of plant viruses. This review focuses primarily on four research areas in which progress has been most rapid. These include (a) evidence supporting reclassification of BYDVs into two genera; (b) elucidation of gene function and novel mechanisms controlling gene expression; (c) initial forays into understanding the complex interactions between BYDV virions and their aphid vectors; and (d ) replication of a BYDV satellite RNA. Economic losses, symptomatology, and means of control of BYD are also discussed.
Impact of Different Platelet Glycoprotein IIb/IIIa Receptor Inhibitors Among Diabetic Patients Undergoing Percutaneous Coronary Intervention
Authors: Roffi Marco , Moliterno David J. , Meier Bernhard , Powers Eric R. , Grines Cindy L. , DiBattiste Peter M. , Herrmann Howard C. , Bertrand Michel , Harris Katherine E. , Demopoulos Laura A. , Topol Eric J.
Published: July 2002

Background

—

The platelet glycoprotein IIb/IIIa receptor inhibitor abciximab, a monoclonal antibody, has been shown to improve early and late outcomes among diabetic patients undergoing percutaneous coronary intervention (PCI). It is unknown whether small-molecule agents confer similar benefits.

Methods and Results

—

In 18 countries, 4809 patients undergoing PCI with stent implantation were randomized to tirofiban or abciximab. At the time of enrollment, patients were stratified according to diabetes status. As compared with non-diabetic patients, patients with diabetes (n=1117) showed similar 30-day ischemic outcomes, an increased incidence of any target vessel revascularization (TVR) at 6 months (10.3% versus 7.8%;
P
= 0.008), and a trend toward higher 1-year mortality (2.5% versus 1.6%;
P
=0.056). Among diabetic patients randomized to tirofiban (n=560), the incidence of death, myocardial infarction (MI), or urgent TVR at 30 days was 6.2%, and among those randomized to abciximab (n=557) it was 5.4% (hazard ratio [HR] 1.16;
P
=0.540). At 6 months, the composite of death, MI, or any TVR occurred in 15.7% and in 16.9% of tirofiban and abciximab patients, respectively (HR 0.93;
P
=0.610). Any TVR occurred in 9.5% and 11.1%, respectively (HR 0.84;
P
= 0.366). The 1-year mortality was 2.1% in the tirofiban group and 2.9% in the abciximab group (HR 0.74;
P
= 0.436).

Conclusions

—

Among diabetic patients undergoing PCI, tirofiban and abciximab were associated with comparable event rates, including similar rates of 6-month TVR and 1-year mortality. These findings suggest that the non-glycoprotein IIb/IIIa properties of abciximab do not translate into a discernible long-term clinical benefit among diabetic patients.
Biochemical Basis of Angioedema Associated With Recombinant Tissue Plasminogen Activator Treatment
Authors: Molinaro Giuseppe , Gervais Nicole , Adam Albert
Published: July 2002

Background

—

Angioedema has been reported during recombinant tissue plasminogen activator (rtPA) treatment of acute ischemic stroke, often with concomitant use of angiotensin I–converting enzyme inhibitor treatment. Angioedema has been partly attributed to the nonapeptide bradykinin (BK), although its precise role has been poorly documented until now. The purposes of this report are 2-fold. First, we sought to define and characterize the in vitro kinin-forming capacity of rtPA when incubated with human plasma at a concentration within the therapeutic concentration range of rtPA attained in blood in vivo during fibrinolysis. Second, we sought to define the mechanism by which rtPA liberates BK from purified human single-chain high-molecular-weight kininogen, a key constituent of the contact system of plasma and the precursor of BK.

Summary of Report

—

When incubated with human plasma, in the presence of an angiotensin I–converting enzyme inhibitor, rtPA generates BK, which is further metabolized to des-Arg
9
-BK. The quantity of kinins generated by rtPA is similar to that observed during the activation of the contact system of plasma with a negatively charged surface, suggesting that it is physiologically relevant. The total amount of des-Arg
9
-BK liberated during the incubation period depends on the aminopeptidase P activity, its main degrading peptidase. Additionally, incubations using purified proteins of the fibrinolytic and the contact system pathways show that the rtPA kinin-forming capacity is mediated by plasmin.

Conclusions

—

We conclude that rtPA used in vitro at a therapeutic concentration has the capacity to generate significant quantities of kinins from human plasma. This kinin-forming activity depends on the activation of the fibrinolytic pathway. These data suggest that angioedema associated with rtPA treatment of ischemic stroke results directly from plasmin-mediated release of BK.
On the Cognitive Functioning of Aesthetic Emotions
Authors: Pouivet Roger
Published: July 2002

This article seeks to show that we cannot accept an opposition between aesthetics and logic on the basis of the distinction between aesthetic emotion and cognition. This false distinction is founded on another ill-founded one between private states of mind and public languages. Echoing works by R. de Sousa, we can talk about the rationality of emotions. Following N. Goodman and I. Scheffler, we are conducted to the notion of cognitive emotions. If there are aesthetic emotions, they are likely cognitive. The notion of supervenience seems very adequate to show how aesthetic emotion, even aesthetic pleasure, can be related to cognitive experience.
ArTbitration: Human-Machine Interaction in Artistic Domains
Authors: Moroni Artemis , Zuben Fernando Von , Manzolli Jônatas
Published: July 2002

In this article, the authors analyze the process of humanmachine interaction in the context of artistic domains, as a framework for exploring creativity and producing results that could not be obtained without such interaction. “ArTbitration” denotes a process aimed at improving users' aesthetic judgment involving evolutionary computation and other computational intelligence methodologies. The authors interpret it as an interactive, iterative optimization process. They also suggest ArTbitration as an effective way to produce art through the efficient manipulation of information and the proper use of computational creativity to increase the complexity of the results, without neglecting the aesthetic aspects. The article emphasizes the spoken, visual and musical domains, since these are generally characterized by the lack of a systematic way to determine the quality of the result.
A Reformulation of Rule 2 of Centering Theory
Authors: Kibble Rodger
Published: July 2002

The standard preference ordering on the well-known centering transitions Continue, Retain, Shift is argued to be unmotivated: a partial, context-dependent ordering emerges from the interaction between principles dubbed cohesion (maintaining the same center of attention) and salience (realizing the center of attention as the most prominent NP). A new formulation of Rule 2 of centering theory is proposed that incorporates these principles as well as a streamlined version of Strube and Hahn's (1999) notion of cheapness. It is argued that this formulation provides a natural way to handle “topic switches” that appear to violate the canonical preference ordering.
Reading the Windows to the Soul: Evidence of Domain-Specific Sparing in Williams Syndrome
Authors: Tager-Flusberg Helen , Boshart Jenea , Baron-Cohen Simon
Published: July 2002

This study tested the hypothesis that Williams syndrome, a rare genetic neurodevelopmental disorder with an unusual cognitive phenotype, involves spared abilities in the domain of understanding other minds. A group of retarded adults with Williams syndrome was compared to an age-, IQ-, and language-matched group of adults with Prader-Willi syndrome, another genetic disorder without the cognitive characteristics of Williams syndrome, and a group of age-matched normal adults, on a task that taps mentalizing ability. The task involved selecting the correct labels to match photographs of complex mental state expressions in the eye region of the face. The adults with Williams syndrome performed significantly better than the adults with Prader-Willi on this task, and about half the group performed in the same range as the normal adults. These findings are consistent with anecdotal evidence about Williams syndrome and provide evidence that mentalizing is a distinct cognitive domain. This spared cognitive capacity may be linked to the relative sparing of limbic-cerebellar neural substrate in Williams syndrome, which is also connected to cortico-frontal regions that are known to be involved in understanding complex mental states.
Synthesis of Generalized Algorithms for the Fast Computation of Synaptic Conductances with Markov Kinetic Models in Large Network Simulations
Authors: Giugliano Michele
Published: July 2002

Markov kinetic models constitute a powerful framework to analyze patch-clamp data from single-channel recordings and model the dynamics of ion conductances and synaptic transmission between neurons. In particular, the accurate simulation of a large number of synaptic inputs in wide-scale network models may result in a computationally highly demanding process. We present a generalized consolidating algorithm to simulate efficiently a large number of synaptic inputs of the same kind (excitatory or inhibitory), converging on an isopotential compartment, independently modeling each synaptic current by a generic n-state Markov model characterized by piece-wise constant transition probabilities. We extend our findings to a class of simplified phenomenological descriptions of synaptic transmission that incorporate higher-order dynamics, such as short-term facilitation, depression, and synaptic plasticity.
The Arrival of a New Musical Aesthetic: Extracts from a Half-Buried Diary
Authors: Prévost Eddie
Published: July 2002

The author recounts the origins and growth of London's “newmusic” scene of the late 1960s and early 1970s and some later developments issuing from it. He describes some outstanding ensembles, collaborations and events of the period from his vantage point as a participant in such improvisational ventures as AMM, the Scratch Orchestra and the London Musicians' Cooperative.
Fragments of Glass: A Conversation between Hijikata Tatsumi and Suzuki Tadashi
Authors: Akihiko Senda
Published: July 2002

For the first time in English, we present many of Hijikata's aesthetic and poetic texts. These texts are put into context by Kurihara Nanako's introductory essay. The section includes an interview with Hijikata and a conversation between Hijikata and Japanese experimental theatre innovator Suzuki Tadashi.
Kawamura Takeshi: New Ideas in/for Japanese Theatre
Authors: Martin Carol
Published: July 2002

The founder and director of Daisan Erotica discusses his theatre—its aesthetics, hierarchy, funding, and repertory—with Carol Martin.
Operator Performance in Surgical Telemanipulation
Authors: Kazi Arif
Published: July 2002

The application of telemanipulator systems in minimally invasive surgery (MIS) poses high demands on the quality of force feedback. Forces exerted on the tissue are often small and should be reflected back amplified to the surgeon. The dynamic behavior of a telemanipulator system can be adjusted in three basic ways to guarantee sufficient stability robustness in spite of high force scaling factors: by scaling down the surgeon's input motion, by increasing the compliance at the slave arm, and/or by increasing the motion resistance at the master arm. More “transparent” telemanipulator dynamics can be achieved when the damping provided by the surgeon's hand-arm-system is taken into account (for example, the motion resistance necessary to guarantee stability robustness can be reduced).

This paper investigates the effect of the three basic types of telemanipulator dynamics on operator performance in surgical tasks. The impact of improving transparency by making use of operator damping is also studied. Three experiments imitating elementary surgical procedures were conducted: inserting a catheter tip into a vessel, puncturing a membrane, and detecting differences in tissue hardness through palpation. Subjects exerted significantly higher forces when inserting a catheter without force feedback, which shows the benefit of force feedback in surgical telemanipulation. Performance of the subjects was also greatly influenced by the basic type of telemanipulator dynamics. However, differences in outcome between the experiments indicate that the best basic type will generally depend on the surgical task at hand. Improving the transparency of the telemanipulator system by making use of operator damping did not improve performance of the subjects any further. Thus, it appears that providing the appropriate basic type of telemanipulator dynamics for a given task may be even more critical to the performance of the surgeon than an optimized transparency of the telemanipulator dynamics.
Providing More Interactivity to Virtual Museums: A Proposal for a VR Authoring Tool
Authors: Wazlawick Raul S. , Rosatelli Marta C. , Ramos Edla M. F. , Cybis Walter A. , Storb Bernd H. , Schuhmacher Vera R. N. , Mariani Antonio C. , Kirner Tereza , Kirner Claudio , Fagundes Lea C.
Published: July 2002

This paper describes the museuVirtual project that is developing an authoring tool for the collaborative building of nonimmersive museums in virtual reality. The rationale behind museuVirtual is based on the observation that virtual museums found on the Internet normally have very limited opportunities for user interactivity. We examine different kinds of interactivity and propose an authoring tool that allows a teacher or student to create virtual exhibits in which dynamic interactive objects and chatterbots may be programmed in a relatively easy way. This proposal is strongly based on the concepts of actor-based programming and constructivist theory, which have been applied in the last five years to teach basic programming skills to beginners. The ideas applied with success in many previous experiments using 2-D graphics are now being introduced in an authoring tool that generates VRML/Java code. The museuVirtual project is developing a tool that not only allows the students to be the organizers and curators of their own museums, but also to work collaboratively, by building such museums in a virtual distributed environment.
Multisensor Integrated Prediction for Virtual Reality
Authors: Emura Satoru , Tachi Susumu
Published: July 2002

Unconstrained measurement of human head motion is essential for HMDs (headmounted displays) to be really interactive. Polhemus sensors developed for that purpose have deficiencies of critical latency and low sampling rates. Adding to this, a delay for rendering virtual scenes is inevitable. This paper proposes methods that compensate the latency and raises the effective sampling rate by integrating Polhemus and gyro sensors. The adoption of quaternion representation enables us to avoid singularity and the complicated boundary process of rotational motion. The ability of proposed methods under various rendering delays was evaluated in the respect of RMS error and our new correlational technique, which enables us to check the latency and fidelity of a magnetic tracker, and to assess the environment where the magnetic tracker is used. The real-time implementation of our simpler method on personal computers is also reported in detail.
Evolution of Visual Resolution Constrained by a Trade-off
Authors: Kortmann Rens , Postma Eric , Herik Jaap van den
Published: July 2002

The evolution of visual systems is constrained by a trade-off between spatial and temporal resolution. In this article we aim at identifying the causes of the trade-off at the retinal level in both artificial and natural visual systems. We start by selecting two factors that limit the values of spatial and temporal resolution. Then we show in two experiments on the evolution of an artificial system that the two factors induce trade-off curves connecting the evolved values of spatial and temporal resolution. A comparison of the experimental results with the resolution evolved in natural visual systems leads us to the conclusion that in natural systems the same factors are responsible for the observed trade-off.