bluuebunny/crossref_metadata_2025 huggingface dataset:
GERM CELL DEVELOPMENT IN DROSOPHILA
Authors: Williamson Anne , Lehmann Ruth
Published: July 2002

▪ Abstract  More than 100 years have passed since Weismann first recognized the role of germ cells in the continuity of a species. Today, it remains unclear how a germ cell is initially set aside from somatic cells and how it chooses its unique developmental path. In this review, we address various aspects of germ cell development in Drosophila, such as germ cell determination, germ cell migration, gonad formation, sex determination, and gametogenesis. Many aspects of germ cell development, including the morphology of germ cells, their migratory behavior, as well as the processes of gonad formation and gametogenesis, show striking similarities among organisms. Considering the conservation of factors that regulate somatic development, it is likely that some aspects of germ cell development are shared not only on a morphological but also on the molecular level between Drosophila and other organisms.
ADIPOCYTE DIFFERENTIATION AND LEPTIN EXPRESSION
Authors: Hwang Cheng-Shine , Loftus Thomas M. , Mandrup Susanne , Lane M. Daniel
Published: July 2002

▪ Abstract  Adipose tissue has long been known to house the largest energy reserves in the animal body. Recent research indicates that in addition to this role, the adipocyte functions as a global regulator of energy metabolism. Adipose tissue is exquisitely sensitive to a variety of endocrine and paracrine signals, e.g. insulin, glucagon, glucocorticoids, and tumor necrosis factor (TNF), that combine to control both the secretion of other regulatory factors and the recruitment and differentiation of new adipocytes. The process of adipocyte differentiation is controlled by a cascade of transcription factors, most notably those of the C/EBP and PPAR families, which combine to regulate each other and to control the expression of adipocyte-specific genes. One such gene, i.e. the obese gene, was recently identified and found to encode a hormone, referred to as leptin, that plays a major role in the regulation of energy intake and expenditure. The hormonal and transcriptional control of adipocyte differentiation is discussed, as is the role of leptin and other factors secreted by the adipocyte that participate in the regulation of adipose homeostasis.
Actin-Related Proteins
Authors: Schafer D. A. , Schroer T. A.
Published: July 2002

▪ Abstract  Actin-related proteins (Arps) participate in a diverse array of cellular processes. They modulate assembly of conventional actin, contribute to microtubule-based motility catalyzed by dynein, and serve as integral components of large protein complexes required for gene expression. We highlight here recent work aimed at understanding the roles played by Arps in each of these processes.
Mechanisms of Viral Interference with MHC Class I Antigen Processing and Presentation
Authors: Yewdell Jonathan W. , Bennink Jack R.
Published: July 2002

▪ Abstract  Viruses are ubiquitous and dangerous obligate intracellular parasites. To facilitate recognition of virus-infected cells by the immune system, vertebrates evolved a system that displays oligopeptides derived from viral proteins on the surface of cells in association with class I molecules of the major histocompatibility complex. Here we review the mechanisms counter-evolved by viruses to interfere with the generation of viral peptides, their intracellular trafficking, or the cell surface expression of class I molecules bearing viral peptides. This topic is important in its own right because the viruses that encode these proteins represent medically important pathogens, are potential vectors for vaccines or gene therapy, and provide strategies and tools for blocking immune recognition in transplantation, autoimmunity, and gene therapy. In addition, studies on viral interference provide unique insights into unfettered antigen processing and normal cellular functions that are exploited and exaggerated by viruses.
THE ART OF ENERGY EFFICIENCY: Protecting the Environment with Better Technology
Authors: Rosenfeld Arthur H.
Published: July 2002

▪ Abstract  After a first career as Professor of Physics, University of California at Berkeley, working in experimental particle physics at Lawrence Berkeley National Laboratory (LBNL), I was prompted by the 1973 Organization of Petroleum Exporting Countries (OPEC) oil embargo to switch to improving energy end-use efficiency, particularly in buildings. I cofounded and directed the Energy Efficient Buildings program at LBNL, which later became the Center for Building Science. At the Center we developed high-frequency solid-state ballasts for fluorescent lamps, low-emissivity and selective windows, and the DOE-2 computer program for the energy analysis and design of buildings. The ballasts in turn stimulated Philips lighting to produce compact fluorescent lamps. When they achieve their expected market share, energy savings from products started or developed at the Center for Building Sciences are projected to save American consumers $30 billion/year, net of the cost of the better buildings and products. In terms of pollution control, this is equivalent to displacing approximately 100 million cars. We did the analysis on which the California and later the U.S. appliance standards are based, and we also worked on indoor air quality and discovered how radon is sucked into homes. We worked closely with the California utilities to develop programs in “Demand Side Management” and “Integrated Utility Planning.” I also worked in California and New England on utility “collaboratives” under which we changed their profit rules to favor investment in customer energy efficiency (and sharing the savings with the customer) over selling raw electricity. I cofounded a successful nonprofit, the American Council for an Energy-Efficient Economy, and a University of California research unit, the California Institute for Energy Efficiency, and I served on the steering Committee of Pacific Gas and Electric's ACT2 project, in which we cost-effectively cut the energy use of six sites by one half. Starting in l994, my third career has been as Senior Advisor to the U.S. Department of Energy Assistant Secretary for Energy Efficiency and Renewable Energy.
INSECTS AS TEACHING TOOLS IN PRIMARY AND SECONDARY EDUCATION
Authors: Matthews Robert W. , Flage, and Lynda R. , Matthews Janice R.
Published: July 2002

▪ Abstract  Insects offer a vast array of teaching opportunities for precollege students. Here we address the basics teachers need in order to use insects successfully in their curricula. We identify exemplary resources in the printed North American literature and point out potentially productive places for teachers and students to search for ideas and materials. We review the roles of entomology in the educational framework, highlight favorite classroom arthropods and less well-known examples, and guide readers to entomological resources. Tips to help teachers identify, rear, and maintain classroom insects and find equipment and supplies are included. The review concludes with a plea for greater classroom and curricular involvement by those in the entomological profession.
How to be a Fig Wasp
Authors: Weiblen George D.
Published: July 2002

▪ Abstract  In the two decades since Janzen described how to be a fig, more than 200 papers have appeared on fig wasps (Agaonidae) and their host plants (Ficus spp., Moraceae). Fig pollination is now widely regarded as a model system for the study of coevolved mutualism, and earlier reviews have focused on the evolution of resource conflicts between pollinating fig wasps, their hosts, and their parasites. Fig wasps have also been a focus of research on sex ratio evolution, the evolution of virulence, coevolution, population genetics, host-parasitoid interactions, community ecology, historical biogeography, and conservation biology. This new synthesis of fig wasp research attempts to integrate recent contributions with the older literature and to promote research on diverse topics ranging from behavioral ecology to molecular evolution.
PRIONS AND RNA VIRUSES OF SACCHAROMYCES CEREVISIAE
Authors: Wickner Reed B.
Published: July 2002

▪ Abstract  Saccharomyces cerevisiae is host to the dsRNA viruses L-A (including its killer toxin-encoding satellite, M) and L-BC, the 20S and 23S ssRNA replicons, and the putative prions, [URE3] and [PSI]. review the genetic and biochemical evidence indicating that [URE3] and [PSI] are prion forms of Ure2p and Sup35p, respectively. Each has an N-terminal domain involved in propagation or generation of the prion state and a C-terminal domain responsible for the protein's normal function, nitrogen regulation, or translation termination, respectively. The L-A dsRNA virus expression, replication, and RNA packaging are reviewed. L-A uses a–1 ribosomal frameshift to produce a Gag-Pol fusion protein. The host SKI2, SKI3, and SKI8 proteins block translation of nonpoly(A) mRNAs (such as viral mRNA). Mutants deficient in 60S ribosomal subunits replicate L-A poorly, but not if cells are also ski−. Interaction of 60S subunits with the 3′ polyA is suggested. SKI1/XRN1 is a 5′ → 3′ exoribonuclease that degrades uncapped mRNAs. The viral Gag protein decapitates cellular mRNAs apparently to decoy this enzyme from working on viral mRNA.
NONSEGMENTED NEGATIVE-STRAND RNA VIRUSES: Genetics and Manipulation of Viral Genomes
Authors: Conzelmann Karl-Klaus
Published: July 2002

▪ Abstract  Protocols to recover negative-strand RNA viruses entirely from cDNA have been established in recent years, opening up this virus group to the detailed analysis of molecular genetics and virus biology. The unique gene-expression strategy of nonsegmented negative-strand RNA viruses, which involves replication of ribonucleoprotein complexes and sequential synthesis of free mRNAs, has also allowed the use of these viruses to express heterologous sequences. There are advantages in terms of easy manipulation of constructs, high capacity for foreign sequences, genetically stable expression, and the possibility of adjusting expression levels. Fascinating prospects for biomedical applications and transient gene therapy are offered by chimeric virus vectors carrying novel envelope protein genes and targeted to defined host cells.
ANTIGEN PROCESSING AND PRESENTATION BY THE CLASS I MAJOR HISTOCOMPATIBILITY COMPLEX
Authors: York Ian A. , Rock Kenneth L.
Published: July 2002

▪ Abstract  Major histocompatibility complex (MHC) class I molecules bind peptides derived from cellular proteins and display them for surveillance by the immune system. These peptide-binding molecules are composed of a heavy chain, containing an antigen-binding groove, which is tightly associated with a light chain (β2-microglobulin). The majority of presented peptides are generated by degradation of proteins in the cytoplasm, in many cases by a large multicatalytic proteolytic particle, the proteasome. Two β-subunits of the proteasome, LMP2 and LMP7, are inducible by interferon-γ and alter the catalytic activities of this particle, enhancing the presentation of at least some antigens. After production of the peptide in the cytosol, it is transported across the endoplasmic reticulum (ER) membrane in an ATP-dependent manner by TAP (transporter associated with antigen presentation), a member of the ATP-binding cassette family of transport proteins. There are minor pathways for generating presented peptides directly in the ER, and some evidence suggests that peptides may be further trimmed in this location. The class I heavy chain and β2-microglobulin are cotranslationally translocated into the endoplasmic reticulum where their assembly may be facilitated by the sequential association of the heavy chain with chaperone proteins BiP and calnexin. The class I molecule then associates with the lumenal face of TAP where it is retained, presumably awaiting a peptide. After the class I molecule binds a peptide, it is released for exocytosis to the cell surface where cytotoxic T lymphocytes examine it for peptides derived from foreign proteins.
Regulation of the Natural Killer Cell Receptor Repertoire
Authors: Raulet David H. , Vance Russell E. , McMahon Christopher W.
Published: July 2002

Natural killer cells express inhibitory receptors specific for MHC class I proteins and stimulatory receptors with diverse specificities. The MHC-specific receptors discriminate among different MHC class I alleles and are expressed in a variegated, overlapping fashion, such that each NK cell expresses several inhibitory and stimulatory receptors. Evidence suggests that individual developing NK cells initiate expression of inhibitory receptor genes in a sequential, cumulative, and stochastic fashion. Superimposed on the receptor acquisition process are multiple education mechanisms, which act to coordinate the stimulatory and inhibitory specificities of developing NK cells. One process influences the complement of receptors expressed by individual NK cells. Other mechanisms may prevent NK cell autoaggression even when the developing NK cell fails to express self-MHC-specific inhibitory receptors. Together, these mechanisms ensure a self-tolerant and maximally discriminating NK cell population. Like NK cells, a fraction of memory phenotype CD8+T cells, as well as other T cell subsets, express inhibitory class I–specific receptors in a variegated, overlapping fashion. The characteristics of these cells suggest that inhibitory receptor expression may be a response to prior antigenic stimulation as well as to poorly defined additional signals. A unifying hypothesis is that both NK cells and certain T cell subsets initiate expression of inhibitory receptors in response to stimulation.
ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN THE CLASSIFICATION OF VASCULITIS
Authors: Niles, M.D John L.
Published: July 2002

▪ Abstract  Two important types of antineutrophil cytoplasmic antibodies (ANCA) have been identified: anti-proteinase 3 and anti-myeloperoxidase antibodies. In the appropriate clinical setting, the presence of either is virtually diagnostic of the subset of vasculitis that includes Wegener's granulomatosis, microscopic polyangiitis (microscopic polyarteritis), the Churg-Strauss syndrome, idiopathic pauci-immune necrotizing and crescentic glomerulonephritis, and related and overlapping forms of these vasculitidies. The finding of ANCA throughout this group identifies these syndromes as belonging to a single category or spectrum of disease.
ENDOTHELIAL-DEPENDENT MECHANISMS IN CHRONIC INFLAMMATORY LEUKOCYTE RECRUITMENT
Authors: Luscinskas, Ph.D Francis W. , Gimbrone Michael A.
Published: July 2002

▪ Abstract  Peripheral blood leukocytes interact with the vascular endothelium in a wide range of physiologic and pathophysiologic situations. A current working concept is that activation of vascular endothelium is an important event during the inflammatory response, conferring spatial and temporal localization and leukocyte-type selectivity to the recruitment process. This chapter highlights recent advances in our understanding of the endothelial-dependent molecular mechanisms that mediate recruitment of mononuclear leukocytes (lymphocytes and monocytes) and discusses these advances in the context of chronic inflammatory diseases and their potential therapeutic interventions.
THE ROLE OF LIPOPROTEIN(a) IN ATHEROGENESIS AND THROMBOSIS
Authors: Hajjar, M.D Katherine A. , Nachman, M.D Ralph L.
Published: July 2002

▪ Abstract  Lipoprotein(a) [Lp(a)] represents an important independent risk factor for atherosclerotic cardiovascular disease. Lp(a) constitutes a class of low-density lipoprotein-like particles that are structurally heterogenous due to variability within the distinguishing apoprotein, apolipoprotein(a) [Apo(a)]. Apo(a) bears a high degree of homology to the fibrinolytic zymogen, plasminogen, the parent molecule of the serine protease plasmin. Apo(a) contains a variable number of tandemly repeated triple-loop units called kringles, which appear to mediate Lp(a)'s interactions with fibrin and cell surface receptors. Although the mechanism of its atherogenicity is unknown, Lp(a) has been implicated in the delivery of cholesterol to the injured blood vessel, in blockade of plasmin generation on fibrin and cell surfaces, and as a stimulus for smooth muscle cell proliferation. In addition, new members of the plasminogen/Apo(a) gene family have been defined, creating a potential link between Lp(a) and the control of angiogenesis in both health and disease. Pharmacologic therapy of elevated Lp(a) levels has been only modestly successful; apheresis remains the most effective therapeutic modality.
Adoptive Immunotherapy Following Allogeneic Bone Marrow Transplantation
Authors: Dazzi Francesco , Goldman John M.
Published: July 2002

Some of the recent advances in our knowledge of immune recognition have provided new tools to circumvent or reverse some of the major disadvantages of allogeneic bone marrow transplantation (BMT). The pretransplant conditioning regimen produces a major defect in the immune system that greatly favors the occurrence of life-threatening infections, caused particularly by Epstein-Barr virus and cytomegalovirus. However, adoptive transfer of virus-specific cytotoxic T lymphocytes can reconstitute specific immunity and/or cure viral disease in immunocompromised post-BMT patients. The other major drawback of allogeneic BMT is graft-versus-host disease (GVHD). Although potentially detrimental, it is closely associated with an antileukemia reaction (graft-versus- leukemia, GVL). The most direct evidence of the GVL effect has been provided by the efficacy of donor leukocyte infusions (DLI). DLI can induce long-lasting remissions, especially in patients with chronic myeloid leukemia who relapse post-BMT. Although allogeneic cell therapy should still be considered a “naive” form of immunotherapy, work in progress on the identification of leukemia-specific antigens will improve the outcome and enlarge its applications.
Nonreplicating Persistence ofMycobacteriumTuberculosis
Authors: Wayne Lawrence G. , Sohaskey Charles D.
Published: July 2002

▪ Abstract  There is ample clinical evidence, as well as evidence from animal experiments, that Mycobacterium tuberculosis can persist in tissues for months to decades without replicating, yet with the ability to resume growth and activate disease. Our knowledge of both macrophage physiology and the nature of tuberculous lesions in man and animals suggests that hypoxia is a major factor in inducing nonreplicating persistence (NRP) of tubercle bacilli. In vitro models reinforce this conclusion and provide insights into mechanisms that make NRP possible. There is evidence from in vitro models that the strategies employed by the bacilli to permit hypoxic NRP include restriction of biosynthetic activity to conserve energy, induction of alternative energy pathways, and stabilization of essential cell components to lessen the need for repair or replacement.
Biological Weapons—a Primer for Microbiologists
Authors: Hawley Robert J. , Eitzen Jr Edward M.
Published: July 2002

▪ Abstract  Biological weapons are not new. Biological agents have been used as instruments of warfare and terror for thousands of years to produce fear and harm in humans, animals, and plants. Because they are invisible, silent, odorless, and tasteless, biological agents may be used as an ultimate weapon—easy to disperse and inexpensive to produce. Individuals in a laboratory or research environment can be protected against potentially hazardous biological agents by using engineering controls, good laboratory and microbiological techniques, personal protective equipment, decontamination procedures, and common sense. In the field or during a response to an incident, only personal protective measures, equipment, and decontamination procedures may be available. In either scenario, an immediate evaluation of the situation is foremost, applying risk management procedures to control the risks affecting health, safety, and the environment. The microbiologist and biological safety professional can provide a practical assessment of the biological weapons incident to responsible officials in order to help address microbiological and safety issues, minimize fear and concerns of those responding to the incident, and help manage individuals potentially exposed to a threat agent.
Influence of Dendritic Conductances on the Input-Output Properties of Neurons
Authors: Reyes Alex
Published: July 2002

▪ Abstract  A fundamental problem in neuroscience is understanding how a neuron transduces synaptic input into action potentials. The dendrites form the substrate for consolidating thousands of synaptic inputs and are the first stage for signal processing in the neuron. Traditionally, dendrites are viewed as passive structures whose main function is to funnel synaptic input into the soma. However, dendrites contain a wide variety of voltage- and time-dependent ion channels. When activated, the currents through these channels can alter the amplitude and time course of the synaptic input and under certain conditions even evoke all-or-none regenerative potentials. The synaptic input that ultimately reaches the soma is likely to be a highly transformed version of the original signal. Thus, a key step in understanding the relationship between synaptic input and neuronal firing is to elucidate the signal processing that occurs in the dendrites.
REGULATION OF GENE EXPRESSION BY DIETARY FAT
Authors: Jump Donald B. , Clarke Steven D.
Published: July 2002

▪ Abstract  Dietary fat is an important macronutrient for the growth and development of all organisms. In addition to its role as an energy source and its effects on membrane lipid composition, dietary fat has profound effects on gene expression, leading to changes in metabolism, growth, and cell differentiation. The effects of dietary fat on gene expression reflect an adaptive response to changes in the quantity and type of fat ingested. Specific fatty acid–regulated transcription factors have been identified in bacteria, amphibians, and mammals. In mammals, these factors include peroxisome proliferator–activated receptors (PPARα, -β, and -γ), HNF4α, NFκB, and SREBP1c. These factors are regulated by (a) direct binding of fatty acids, fatty acyl–coenzyme A, or oxidized fatty acids; (b) oxidized fatty acid (eicosanoid) regulation of G-protein–linked cell surface receptors and activation of signaling cascades targeting the nucleus; or (c) oxidized fatty acid regulation of intracellular calcium levels, which affect cell signaling cascades targeting the nucleus. At the cellular level, the physiological response to fatty acids will depend on (a) the quantity, chemistry, and duration of the fat ingested; (b) cell-specific fatty acid metabolism (oxidative pathways, kinetics, and competing reactions); (c) cellular abundance of specific nuclear and membrane receptors; and (d) involvement of specific transcription factors in gene expression. These mechanisms are involved in the control of carbohydrate and lipid metabolism, cell differentiation and growth, and cytokine, adhesion molecule, and eicosanoid production. The effects of fatty acids on the genome provide new insight into how dietary fat might play a role in health and disease.
FROM GABAA RECEPTOR DIVERSITY EMERGES A UNIFIED VISION OF GABAergic INHIBITION
Authors: Costa E.
Published: July 2002

▪ Abstract  Transmitter receptor diversity often indicates differences in transmitter receptor transduction mechanisms. This is not the case for γ-aminobutyric acid subtype A (GABAA) receptor subtypes despite the presence of 16 genes to encode the 5 families of native GABAA receptor subtypes. Similar considerations apply to GABAC receptors and GABAB receptors. Both GABAA and GABAB receptors cause hyperpolarization of neuronal membranes and inhibition of neuronal excitability, but their mechanisms differ. GABAB receptors involve an efflux of K+ rather than an influx of Cl−, as in the case of GABAA and GABAC receptors. The stimulation of GABAA receptors can sometimes cause depolarization by Cl− efflux; this efflux is not the result of a transduction mechanism modification, but of Cl−-concentration gradient modification. Presumably, GABAA receptor diversity is directly linked to the inhibitory activity of basket cells and other interneuron axons, each innervating several postsynaptic neurons (cortical and hippocampal pyramidal cells for instance). Since the role of this inhibition is to entrain hippocampal and cortical pyramidal neurons into columnary activity, the GABAA receptor diversification may be a mechanism expressed by these postsynaptic neuron populations that uses different GABA potencies to synchronize pyramidal neurons into columnary activity. Thus, GABA potency variability, which emerges from GABAA receptor diversity, plays a unifying role in the intrinsic functional mechanism of laminated structures. GABAA receptor structural differences also play a role in diazepam tolerance, which is a mechanism operative in neuronal circuit adaptation to the extreme amplification of GABA-gated Cl− current intensities. Partial agonists (such as imidazenil), which modestly amplify GABA action at many GABAA receptor subtypes, fail to cause tolerance, dependence, ataxia, or ethanol and barbiturate potentiation. Partial agonists might become a new class of anxiolytic and anticonvulsant drugs that are virtually devoid of the side effects that cause serious concerns in the clinical use of full allosteric positive modulators of GABA action, such as diazepam, alprazolam, triazolam, and others. None of the above can be used as anticonvulsants because of an extremely high tolerance liability.

When there is tolerance to diazepam, signs of sensitization to proconvulsive action are exhibited simultaneously. After tolerance, associated changes in GABAA recepter subtype expression are virtually reversed in 72 h. Also, 96 h after termination of long-term diazepam treatment, rats exhibit anxiety and are more sensitive to kainic acid–elicited convulsions. At the same time, these rats have an increase in brain expression of GLuR1, R2, and R3. It is believed that the supersensitivity to kainic acid, convulsions and anxiety, and the increased expression of GLuR1, R2, and R3 may be parts of the mechanism of diazepam dependence.
BIOLOGICAL ICE NUCLEATION AND ICE DISTRIBUTION IN COLD-HARDY ECTOTHERMIC ANIMALS
Authors: Lee Richard E. , Costanzo Jon P.
Published: July 2002

▪ Abstract  For many ectotherms, overwintering survival depends on the avoidance or regulation of ice nucleation and growth within their body fluids. Freeze avoidance via supercooling plays an important role in the cold hardiness of many small species, particularly terrestrial arthropods, that do not survive the freezing of their body fluids. In contrast, mechanisms that limit supercooling and initiate freezing at relatively high temperatures promote survival of the few invertebrates and vertebrates that tolerate freezing. These mechanisms include inoculative freezing, which results from contact with ice in the environment, and various ice nucleating proteins, microbes, and crystalloid compounds. In freeze-tolerant ectotherms, cold hardiness is influenced by complex, seasonally changing interactions among physiological factors, ice nucleators, and the physical microenvironment. Extraorgan sequestration of ice is a major adaptation of freeze tolerance. For most freeze-tolerant species, ice growth is primarily restricted to extracellular compartments; however, intracellular freezing also occurs in some species.
Ovulation: New Dimensions and New Regulators of the Inflammatory-Like Response
Authors: Richards JoAnne S. , Russell Darryl L. , Ochsner Scott , Espey Lawrence L.
Published: July 2002

▪ Abstract  Ovulation is a complex process that is initiated by the lutenizing hormone surge and is controlled by the temporal and spatial expression of specific genes. This review focuses on recent endocrine, biochemical, and genetic information that has been derived largely from the identification of new genes that are expressed in the ovary, and from knowledge gained by the targeted deletion of genes that appear to impact the ovulation process. Two main areas are described in most detail. First, because mutant mouse models indicate that appropriate formation of the cumulus matrix is essential for successful ovulation, genes expressed in the cumulus cells and those that control cumulus expansion are discussed. Second, because mice null for the progesterone receptor fail to ovulate and are ideal models for dissecting the critical events downstream of progesterone receptor, genes expressed in mural granulosa cells that regulate the expression of novel proteases are described.
DWARF BUNT: Politics, Identification, and Biology
Authors: Mathre D. E.
Published: July 2002

▪ Abstract  Dwarf bunt is a disease of wheat caused by the smut fungus Tilletia controversa Kuhn. Winter wheat (Triticum aestivum L.) is the primary host of economic significance. Although the total acreage affected by dwarf bunt is small relative to total wheat production worldwide, the disease has assumed attention disproportionate to its economic impact because it has become a matter of contention in world trade in cereals. This review describes the political and economic issues underlying the study and identification of T. controversa.
International Institutions and System Transformation
Authors: Jacobson Harold K.
Published: July 2002

Starting in the 1990s, scholarship has produced interesting, new, nuanced ideas about the potential role of international institutions in transforming the global political system. Political scientists have achieved a new understanding of how the Westphalian system came into being, and this understanding has provided a rudimentary model of the dynamics of system transformation. The new institutionalism has provided insights into the possible role of institutions. Scholars have developed new understandings of secondary consequences of conducting interactions among nation-states through international institutions. The study of a particular institution, the European Union, has been revitalized and important knowledge has emerged about its dynamics and trajectory. Finally, scholars have begun to raise questions about the properties of a non-Westphalian system, especially about how democratic accountability could be established. This chapter examines each of these developments in turn.
Oral Health in the United States: The Post-Fluoride Generation
Authors: Milgrom P. , Reisine S.
Published: July 2002

▪ Abstract  Tremendous strides have been made in reducing the incidence of tooth decay, periodontal diseases, and associated loss of teeth in adults and children since the inception of community water fluoridation programs. Yet the disadvantaged and poor have not fully shared in the benefits. Other challenges to oral health remain. Oral cancer and related smoking and smokeless tobacco use remain major public health problems. Access to preventive and therapeutic dental care is far from universal. Public health programs similar in commitment to the approach of community water fluoridation programs initiated in the 1950s and 1960s are needed to address neglected oral health needs of underserved and high-risk populations in the United States.
An Independent Means: The American Revolution and the Rise of a National Economy
Authors: Chu Jonathan M.
Published: July 2002

Scholars endlessly debate about whether the economy of Britain's North American colonies had become autonomous on the eve of Independence and whether and when it could accurately be termed capitalistic, but they tend to agree that the colonies had their share of acquisitive entrepreneurs who understood the commodity value of money and shaped their behavior accordingly. Although this point of convergence ultimately leaves the issue of American economic independence unresolved, it strongly supports the position that a transition to capitalism preceded the Revolution.
Automatic Text Categorization in Terms of Genre and Author
Authors: Stamatatos Efstathios , Fakotakis Nikos , Kokkinakis George
Published: July 2002

The two main factors that characterize a text are its content and its style, and both can be used as a means of categorization. In this paper we present an approach to text categorization in terms of genre and author for Modern Greek. In contrast to previous stylometric approaches, we attempt to take full advantage of existing natural language processing (NLP) tools. To this end, we propose a set of style markers including analysis-level measures that represent the way in which the input text has been analyzed and capture useful stylistic information without additional cost. We present a set of small-scale but reasonable experiments in text genre detection, author identification, and author verification tasks and show that the proposed method performs better than the most popular distributional lexical measures, i.e., functions of vocabulary richness and frequencies of occurrence of the most frequent words. All the presented experiments are based on unrestricted text downloaded from the World Wide Web without any manual text preprocessing or text sampling. Various performance issues regarding the training set size and the significance of the proposed style markers are discussed. Our system can be used in any application that requires fast and easily adaptable text categorization in terms of stylistically homogeneous categories. Moreover, the procedure of defining analysis-level markers can be followed in order to extract useful stylistic information using existing text processing tools.
Confidence in Recognition Memory for Words: Dissociating Right Prefrontal Roles in Episodic Retrieval
Authors: Henson R. N. A. , Rugg M. D. , Shallice T. , Dolan R. J.
Published: July 2002

We used event-related functional magnetic resonance imaging (efMRI) to investigate brain regions showing differential responses as a function of confidence in an episodic word recognition task. Twelve healthy volunteers indicated whether their old-new judgments were made with high or low confidence. Hemodynamic responses associated with each judgment were modeled with an “early” and a “late” response function. As predicted by the monitoring hypothesis generated from a previous recognition study [Henson, R. N. A., Rugg, M. D., Shallice, T., Josephs, O., & Dolan, R. J. (1999a). Recollection and familiarity in recognition memory: An event-related fMRI study. Journal of Neuroscience, 19, 3962-3972], a right dorsolateral prefrontal region showed a greater response to correct low-versus correct high-confidence judgements. Several regions, including the precuneus, posterior cingulate, and left lateral parietal cortex, showed greater responses to correct old than correct new judgements. The anterior left and right prefrontal regions also showed an old-new difference, but for these regions the difference emerged relatively later in time. These results further support the proposal that different subregions of the prefrontal cortex subserve different functions during episodic retrieval. These functions are discussed in relation to a monitoring process, which operates when familiarity levels are close to response criterion and is associated with nonconfident judgements, and a recollective process, which is associated with the confident recognition of old words.
The Effect of Divided Attention on Encoding and Retrieval in Episodic Memory Revealed by Positron Emission Tomography
Authors: Iidaka Tetsuya , Anderson Nicole D. , Kapur Shitij , Cabez Roberto , Craik Fergus I. M.
Published: July 2002

The effects of divided attention (DA) on episodic memory encoding and retrieval were investigated in 12 normal young subjects by positron emission tomography (PET). Cerebral blood flow was measured while subjects were concurrently performing a memory task (encoding and retrieval of visually presented word pairs) and an auditory tone-discrimination task. The PET data were analyzed using multivariate Partial Least Squares (PLS), and the results revealed three sets of neural correlates related to specific task contrasts. Brain activity, relatively greater under conditions of full attention (FA) than DA, was identified in the occipital-temporal, medial, and ventral-frontal areas, whereas areas showing relatively more activity under DA than FA were found in the cerebellum, temporo-parietal, left anterior-cingulate gyrus, and bilateral dorsolateral-prefrontal areas. Regions more active during encoding than during retrieval were located in the hippocampus, temporal and the prefrontal cortex of the left hemisphere, and regions more active during retrieval than during encoding included areas in the medial and right-prefrontal cortex, basal ganglia, thalamus, and cuneus. DA at encoding was associated with specific decreases in rCBF in the left-prefrontal areas, whereas DA at retrieval was associated with decreased rCBF in a relatively small region in the right-prefrontal cortex. These different patterns of activity are related to the behavioral results, which showed a substantial decrease in memory performance when the DA task was performed at encoding, but no change in memory levels when the DA task was performed at retrieval.
Interactions Between Forms of Memory: When Priming Hinders New Episodic Learning
Authors: Wagner Anthony D. , Maril Anat , Schacter Daniel L.
Published: July 2002

Human memory consists of multiple forms, including priming and explicit memory. Although considerable evidence indicates that priming and explicit memory are functionally and neuroanatomically distinct, little is know about when and how these different forms of memory interact. Here, behavioral and functional magnetic resonance imaging (fMRI) methods were used to examine a novel and counterintuitive hypothesis: Priming during episodic encoding may be negatively associated with subsequent explicit memory. Using an experimental design that exploited known properties of spacing or lag effects, the magnitudes of behavioral and neural priming during a second study episode were varied and the relation between these magnitudes of priming during re-encoding and performance on a subsequent explicit memory test was examined. Results revealed that greater behavioral priming (reduced reaction times) and neural priming (reduced left inferior prefrontal brain activation) during re-encoding were associated with lower levels of subsequent explicit memory. Moreover, those subjects who demonstrated greater behavioral and neural priming effects during re-encoding following a long lag tended to demonstrate the least benefit in subsequent explicit memory due to this second study episode. These findings suggest that priming for past experiences can hinder new episodic encoding.
The Neural Substrate of Orientation Working Memory
Authors: Cornette L. , Dupont P. , Salmon E. , Orban Guy A.
Published: July 2002

We have used positron emission tomography (PET) to identify the neural substrate of two major cognitive components of working memory (WM), maintenance and manipulation of a single elementary visual attribute, i.e., the orientation of a grating presented in central vision. This approach allowed us to equate difficulty across tasks and prevented subjects from using verbal strategies or vestibular cues. Maintenance of orientations involved a distributed fronto-parietal network, that is, left and right lateral superior frontal sulcus (SFSl), bilateral ventrolateral prefrontal cortex (VLPFC), bilateral precuneus, and right superior parietal lobe (SPL). A more medial superior frontal sulcus region (SFSm) was identified as being instrumental in the manipulative operation of updating orientations retained in the WM. Functional connectivity analysis revealed that orientation WM relies on a coordinated interaction between frontal and parietal regions. In general, the current findings confirm the distinction between maintenance and manipulative processes, highlight the functional heterogeneity in the prefrontal cortex (PFC), and suggest a more dynamic view of WM as a process requiring the coordinated interaction of anatomically distinct brain areas.
Brain Areas Specific for Attentional Load in a Motion-Tracking Task
Authors: Jovicich Jorge , Peters Robert J. , Koch Christof , Braun Jochen , Chang Linda , Ernst Thomas
Published: July 2002

Although visual attention is known to modulate brain activity in the posterior parietal, prefrontal, and visual sensory areas, the unique roles of these areas in the control of attentional resources have remained unclear. Here, we report a dissociation in the response profiles of these areas. In a parametric functional magnetic resonance imaging (fMRI) study, subjects performed a covert motion-tracking task, in which we manipulated “attentional load” by varying the number of tracked balls. While strong effects of attention—independent of attentional load—were widespread, robust linear increases of brain activity with number of balls tracked were seen primarily in the posterior parietal areas, including the intraparietal sulcus (IPS) and superior parietal lobule (SPL). Thus, variations in attentional load revealed different response profiles in sensory areas as compared to control areas. Our results suggest a general role for posterior parietal areas in the deployment of visual attentional resources.
Short-and Long-Delay Intracranial ERP Repetition Effects Dissociate Memory Systems in the Human Brain
Authors: Guillem François , Rougier Alain , Claverie Bernard
Published: July 2002

Prior exposure to a stimulus can facilitate the performance to subsequent presentations of that stimulus. ERP studies have shown that this facilitation is associated with the modulation of two components (N400 and P600). Investigation of the time course of both behavioral and ERP repetition effects have led to the assumption that it is subserved by the combination of at least two mechanisms operating at different time-points: a short-delay semantic activation and a long-lasting episodic mechanism. The present experiment recorded intracranial ERPs from various structures during a continuous recognition memory task to investigate the respective contribution of the different brain regions to short-and long-delay ERP repetition effects. The results are in good agreement with both the classical neuropsychological literature and the more recent data obtained with functional imagery techniques. They provide electrophysiological evidence of multiple anatomo-functional memory systems in the human brain: a short-term semantic activation system and a long-term episodic memory system, with interface structures that coordinate the functioning of these two systems.
Bootstrapping Neural Networks
Authors: Franke Jürgen , Neumann Michael H.
Published: July 2002

Knowledge about the distribution of a statistical estimator is important for various purposes, such as the construction of confidence intervals for model parameters or the determination of critical values of tests. A widely used method to estimate this distribution is the so-called bootstrap, which is based on an imitation of the probabilistic structure of the data-generating process on the basis of the information provided by a given set of random observations. In this article we investigate this classical method in the context of artificial neural networks used for estimating a mapping from input to output space. We establish consistency results for bootstrap estimates of the distribution of parameter estimates.
Synchronization in Relaxation Oscillator Networks with Conduction Delays
Authors: Fox Jeffrey J. , Jayaprakash Ciriyam , Wang DeLiang , Campbell Shannon R.
Published: July 2002

We study locally coupled networks of relaxation oscillators with excitatory connections and conduction delays and propose a mechanism for achieving zero phase-lag synchrony. Our mechanism is based on the observation that different rates of motion along different nullclines of the system can lead to synchrony in the presence of conduction delays. We analyze the system of two coupled oscillators and derive phase compression rates. This analysis indicates how to choose nullclines for individual relaxation oscillators in order to induce rapid synchrony. The numerical simulations demonstrate that our analytical results extend to locally coupled networks with conduction delays and that these networks can attain rapid synchrony with appropriately chosen nullclines and initial conditions. The robustness of the proposed mechanism is verified with respect to different nullclines, variations in parameter values, and initial conditions.
Measuring Information Spatial Densities
Authors: Bezzi Michele , Samengo Inés , Leutgeb Stefan , Mizumori Sheri J.
Published: July 2002

A novel definition of the stimulus-specific information is presented, which is particularly useful when the stimuli constitute a continuous and metric set, as, for example, position in space. The approach allows one to build the spatial information distribution of a given neural response. The method is applied to the investigation of putative differences in the coding of position in hippocampus and lateral septum.
Cosine Tuning Minimizes Motor Errors
Authors: Todorov Emanuel
Published: July 2002

Cosine tuning is ubiquitous in the motor system, yet a satisfying explanation of its origin is lacking. Here we argue that cosine tuning minimizes expected errors in force production, which makes it a natural choice for activating muscles and neurons in the final stages of motor processing. Our results are based on the empirically observed scaling of neuromotor noise, whose standard deviation is a linear function of the mean. Such scaling predicts a reduction of net force errors when redundant actuators pull in the same direction. We confirm this prediction by comparing forces produced with one versus two hands and generalize it across directions. Under the resulting neuromotor noise model, we prove that the optimal activation profile is a (possibly truncated) cosine—for arbitrary dimensionality of the workspace, distribution of force directions, correlated or uncorrelated noise, with or without a separate cocontraction command. The model predicts a negative force bias, truncated cosine tuning at low muscle cocontraction levels, and misalignment of preferred directions and lines of action for nonuniform muscle distributions. All predictions are supported by experimental data.
Deformation Theory of Dynamic Link Matching
Authors: Aonishi Toru , Kurata Koji
Published: July 2002

Dynamic link matching is a self-organizing topographic mapping between a template image and a data image. The mapping tends to be continuous, linking two points sharing similar local features, which, as a result, can lead to its deformation to some degree. In analyzing such deformation mathematically, we reduced the model equation to a phase equation, which enabled us to clarify the principles of the deformation process and the relationship between high-dimensional models and low-dimensional ones. We also elucidated the characteristics of the model in the context of the standard regularization theory.
On Decoding the Responses of a Population of Neurons from Short Time Windows
Authors: Panzeri Stefano , Treves Alessandro , Schultz Simon , Rolls Edmund T.
Published: July 2002

The effectiveness of various stimulus identification (decoding) procedures for extracting the information carried by the responses of a population of neurons to a set of repeatedly presented stimuli is studied analytically, in the limit of short time windows. It is shown that in this limit, the entire information content of the responses can sometimes be decoded, and when this is not the case, the lost information is quantified. In particular, the mutual information extracted by taking into account only the most likely stimulus in each trial turns out to be, if not equal, much closer to the true value than that calculated from all the probabilities that each of the possible stimuli in the set was the actual one. The relation between the mutual information extracted by decoding and the percentage of correct stimulus decodings is also derived analytically in the same limit, showing that the metric content index can be estimated reliably from a few cells recorded from brief periods. Computer simulations as well as the activity of real neurons recorded in the primate hippocampus serve to confirm these results and illustrate the utility and limitations of the approach.