bluuebunny/crossref_metadata_2025 huggingface dataset:
Infectious Hepatitis C Virus Pseudo-particles Containing Functional E1–E2 Envelope Protein Complexes
Authors: Bartosch Birke , Dubuisson Jean , Cosset François-Loïc
Published: March 2003

The study of hepatitis C virus (HCV), a major cause of chronic liver disease, has been hampered by the lack of a cell culture system supporting its replication. Here, we have successfully generated infectious pseudo-particles that were assembled by displaying unmodified and functional HCV glycoproteins onto retroviral and lentiviral core particles. The presence of a green fluorescent protein marker gene packaged within these HCV pseudo-particles allowed reliable and fast determination of infectivity mediated by the HCV glycoproteins. Primary hepatocytes as well as hepato-carcinoma cells were found to be the major targets of infection in vitro. High infectivity of the pseudo-particles required both E1 and E2 HCV glycoproteins, and was neutralized by sera from HCV-infected patients and by some anti-E2 monoclonal antibodies. In addition, these pseudo-particles allowed investigation of the role of putative HCV receptors. Although our results tend to confirm their involvement, they provide evidence that neither LDLr nor CD81 is sufficient to mediate HCV cell entry. Altogether, these studies indicate that these pseudo-particles may mimic the early infection steps of parental HCV and will be suitable for the development of much needed new antiviral therapies.
Components of the Ligand for a Ni++ Reactive Human T Cell Clone
Authors: Lu Linh , Vollmer Jörg , Moulon Corinne , Weltzien Hans Ulrich , Marrack Philippa , Kappler John
Published: March 2003

The major histocompatibility complex (MHC) restriction element for a human Ni2+ reactive T cell, ANi-2.3, was identified as DR52c. A series of experiments established that the functional ligand for this T cell was a preformed complex of Ni2+ bound to the combination of DR52c and a specific peptide that was generated in human and mouse B cells, but not in fibroblasts nor other antigen processing–deficient cells. In addition, ANi-2.3 recognition of this complex was dependent on His81 of the MHC β chain, suggesting a role for this amino acid in Ni2+ binding to MHC. We propose a general model for Ni2+ recognition in which βHis81 and two amino acids from the NH2-terminal part of the MHC bound peptide coordinate Ni2+ which then interacts with some portion of the Vα CDR1 or CDR2 region.
Increased Susceptibility to LPS-induced Endotoxin Shock in Secretory Leukoprotease Inhibitor (SLPI)-deficient Mice
Authors: Nakamura Akira , Mori Yuriko , Hagiwara Koichi , Suzuki Takuji , Sakakibara Tomohiro , Kikuchi Toshiaki , Igarashi Takayuki , Ebina Masahito , Abe Tatsuya , Miyazaki Junichi , Takai Toshiyuki , Nukiwa Toshihiro
Published: March 2003

Secretory leukoprotease inhibitor (SLPI) protects tissue against the destructive action of neutrophil elastase at the site of inflammation. Recent studies on new functions of SLPI have demonstrated that SLPI may play a larger role in innate immunity than merely as a protease inhibitor. To clarify the functions of SLPI in bacterial infections, we generated SLPI-deficient mice (SLPI−/− mice) and analyzed their response to experimental endotoxin shock induced by lipopolysaccharide (LPS). SLPI−/− mice showed a higher mortality from endotoxin shock than did wild type mice. This may be explained in part by our observation that SLPI−/− macro-phages show higher interleukin 6 and high-mobility group (HMG)-1 production and nuclear factor κB activities after LPS treatment than do SLPI+/+ macrophages. SLPI also affects B cell function. SLPI−/− B cells show more proliferation and IgM production after LPS treatment than SLPI+/+ B cells. Our results suggest that SLPI attenuates excessive inflammatory responses and thus assures balanced functioning of innate immunity.
Compartmentalized Production of CCL17 In Vivo
Authors: Alferink Judith , Lieberam Ivo , Reindl Wolfgang , Behrens Andrea , Weiß Susanne , Hüser Norbert , Gerauer Klaus , Ross Ralf , Reske-Kunz Angelika B. , Ahmad-Nejad Parviz , Wagner Hermann , Förster Irmgard
Published: March 2003

Dendritic cells (DCs)**Abbreviations used in this paper: BM, bone marrow; CHS, contact hypersensitivity; cLN, cutaneous lymph node; CRP, C-reactive protein; DC, dendritic cell; DNFB, dinitrofluorobenzene; EGFP, enhanced green fluorescent protein; LC, Langerhans cell; LP, lamina propria; MACS, magnetic-activated cell sorting; mLN, mesenteric lymph node; ODN, oligodeoxynucleotide; PFA, paraformaldehyde; PP, Peyer's patch; TLR, Toll-like receptor; TRITC, tetramethylrhodamine-5-(and-6-)-isothiocyanate. fulfill an important regulatory function at the interface of the innate and adaptive immune system. The thymus and activation-regulated chemokine (TARC/CCL17) is produced by DCs and facilitates the attraction of activated T cells. Using a fluorescence-based in vivo reporter system, we show that CCL17 expression in mice is found in activated Langerhans cells and mature DCs located in various lymphoid and nonlymphoid organs, and is up-regulated after stimulation with Toll-like receptor ligands. DCs expressing CCL17 belong to the CD11b+CD8−Dec205+ DC subset, including the myeloid-related DCs located in the subepithelial dome of Peyer's patches. CCL17-deficient mice mount diminished T cell–dependent contact hypersensitivity responses and display a deficiency in rejection of allogeneic organ transplants. In contrast to lymphoid organs located at external barriers of the skin and mucosa, CCL17 is not expressed in the spleen, even after systemic microbial challenge or after in vitro stimulation. These findings indicate that CCL17 production is a hallmark of local DC stimulation in peripheral organs but is absent from the spleen as a filter of blood-borne antigens.
The Apoptosome Pathway to Caspase Activation in Primary Human Neutrophils Exhibits Dramatically Reduced Requirements for Cytochrome c
Authors: Murphy Brona M. , O'Neill Amanda J. , Adrain Colin , Watson R. William G. , Martin Seamus J.
Published: March 2003

Caspase activation is a central event in numerous forms of apoptosis and results in the proteolytic degradation of multiple substrate proteins that contribute to the apoptotic phenotype. An important route to caspase activation proceeds via assembly of the “apoptosome” as a result of the cell stress–associated release of mitochondrial cytochrome c. Previous studies have shown that primary neutrophils are largely incapable of mitochondrial respiration, suggesting that these cells either lack functional mitochondria or possess a defective respiratory chain. This prompted us to examine whether neutrophils retain an intact cytochrome c/apoptotic protease-activating factor 1 (Apaf-1) pathway to caspase activation and apoptosis. We show that primary human neutrophils contain barely detectable levels of cytochrome c as well as other mitochondrial proteins. Surprisingly, neutrophil cell–free extracts readily supported Apaf-1–dependent caspase activation, suggesting that these cells may assemble cytochrome c–independent apoptosomes. However, further analysis revealed that the trace amount of cytochrome c present in neutrophils is both necessary and sufficient for Apaf-1–dependent caspase activation in these cells. Thus, neutrophils have a lowered threshold requirement for cytochrome c in the Apaf-1–dependent cell death pathway. These observations suggest that neutrophils retain cytochrome c for the purpose of assembling functional apoptosomes rather than for oxidative phosphorylation.
Defective DNA Repair and Increased Genomic Instability in Artemis-deficient Murine Cells
Authors: Rooney Sean , Alt Frederick W. , Lombard David , Whitlow Scott , Eckersdorff Mark , Fleming James , Fugmann Sebastian , Ferguson David O. , Schatz David G. , Sekiguchi JoAnn
Published: March 2003

In developing lymphocytes, the recombination activating gene endonuclease cleaves DNA between V, D, or J coding and recombination signal (RS) sequences to form hairpin coding and blunt RS ends, which are fused to form coding and RS joins. Nonhomologous end joining (NHEJ) factors repair DNA double strand breaks including those induced during VDJ recombination. Human radiosensitive severe combined immunodeficiency results from lack of Artemis function, an NHEJ factor with in vitro endonuclease/exonuclease activities. We inactivated Artemis in murine embryonic stem (ES) cells by targeted mutation. Artemis deficiency results in impaired VDJ coding, but not RS, end joining. In addition, Artemis-deficient ES cells are sensitive to a radiomimetic drug, but less sensitive to ionizing radiation. VDJ coding joins from Artemis-deficient ES cells, which surprisingly are distinct from the highly deleted joins consistently obtained from DNA-dependent protein kinase catalytic subunit–deficient ES cells, frequently lack deletions and often display large junctional palindromes, consistent with a hairpin coding end opening defect. Strikingly, Artemis-deficient ES cells have increased chromosomal instability including telomeric fusions. Thus, Artemis appears to be required for a subset of NHEJ reactions that require end processing. Moreover, Artemis functions as a genomic caretaker, most notably in prevention of translocations and telomeric fusions. As Artemis deficiency is compatible with human life, Artemis may also suppress genomic instability in humans.
Flt3 Ligand–treated Neonatal Mice Have Increased Innate Immunity Against Intracellular Pathogens and Efficiently Control Virus Infections
Authors: Vollstedt Sabine , Franchini Marco , Hefti Hans P. , Odermatt Bernhard , O'Keeffe Meredith , Alber Gottfried , Glanzmann Bettina , Riesen Matthias , Ackermann Mathias , Suter Mark
Published: March 2003

Flt-3 ligand (FL), a hematopoetic growth factor, increases the number of dendritic cells (DCs), B cells, and natural killer cells in adult mice but the effect in neonates was unknown. We show that FL treatment of newborn mice induced a >100-fold increase in the innate resistance against infection with herpes simplex virus type 1 and Listeria monocytogenes. This resistance required interferon (IFN)-α/β for viral and interleukin (IL)-12 for bacterial infections. Long-term survival after viral but not bacterial infection was increased ∼100-fold by FL treatment. After treatment, CD11c+/major histocompatibility complex type II+ and CD11c+/B220+ DC lineage cells were the only cell populations increased in the spleen, liver, peritoneum, and skin. DC induction was independent of IFNs, IL-2, -4, -7, -9, -15, and mature T and B cells. The data suggest that FL increases the number of DCs in neonates and possibly in other immune-compromised individuals, which in turn improves IFN-α/β– and IL-12–associated immune responses.
T Cell Receptor Gene Rearrangement Lineage Analysis Reveals Clues for the Origin of Highly Restricted Antigen-specific Repertoires
Authors: Hamrouni Abdelbasset , Aublin Anne , Guillaume Philippe , Maryanski Janet L.
Published: March 2003

Due to ordered, stage-specific T cell receptor (TCR)-β and -α locus gene rearrangements and cell division during T cell development, a given, ancestral TCR-β locus VDJ rearrangement might be selected into the mature T cell repertoire as a small cohort of “half-sibling” progeny expressing identical TCR-β chains paired with different TCR-α chains. The low frequency of such a cohort relative to the total αβ TCR repertoire precludes their direct identification and characterization in normal mice. We considered it possible that positive selection constraints might limit the diversity of TCR-α chains selected to pair with β chains encoded by an ancestral VDJ-β rearrangement. If so, half-sibling T cells expressing structurally similar, but different TCR-α chains might recognize the same foreign antigen. By single cell polymerase chain reaction analysis of antigen-specific TCRs selected during a model anti-tumor response, we were able to identify clusters of T cells sharing identical VDJ-β rearrangements but expressing different TCR-α chains. The amplification of residual DJ-β rearrangements as clonal markers allowed us to track T cells expressing different TCR-α chains back to a common ancestral VDJ-β rearrangement. Thus, the diversity of TCR-α's selected as partners for a given VDJ-β rearrangement into the mature TCR repertoire may indeed be very limited.
Importin-α Mediates the Regulated Nuclear Targeting of Serum- and Glucocorticoid-inducible Protein Kinase (Sgk) by Recognition of a Nuclear Localization Signal in the Kinase Central Domain
Authors: Maiyar Anita C. , Leong Meredith L.L. , Firestone Gary L.
Published: March 2003

The transcriptionally regulated serum and glucocorticoid inducible protein kinase (Sgk) is localized to the nucleus in a serum-dependent manner, and a yeast two-hybrid genetic screen uncovered a specific interaction between Sgk and the importin-α nuclear import receptor. In vitro GST pull down assays demonstrated a strong and direct association of importin-α with endogenous Sgk and exogenously expressed HA-tagged Sgk, whereas both components coimmunoprecipitate and colocalize to the nucleus after serum stimulation. Consistent with an active mechanism of nuclear localization, the nuclear import of HA-Sgk in permeabilized cells required ATP, cytoplasm, and a functional nuclear pore complex. Ectopic addition of a 107 amino acid carboxy-terminal fragment of importin-α, which contains the Sgk binding region, competitively inhibited the ability of endogenous importin-α to import Sgk into nuclei in vitro. Mutagenesis of lysines by alanine substitution defined a KKAILKKKEEK sequence within the central domain of Sgk between amino acids 131–141 that functions as a nuclear localization signal (NLS) required for the in vitro interaction with importin-α and for nuclear import of full-length Sgk in cultured cells. The serum-induced nuclear import of Sgk requires the NLS-dependent recognition of Sgk by importin-α as well as the PI3-kinase–dependent phosphorylation of Sgk. Our results define a new role importin-α in the stimulus-dependent control of signal transduction by nuclear localized protein kinases.
Obscurin Is a Ligand for Small Ankyrin 1 in Skeletal Muscle
Authors: Kontrogianni-Konstantopoulos Aikaterini , Jones Ellene M. , van Rossum Damian B. , Bloch Robert J.
Published: March 2003

The factors that organize the internal membranes of cells are still poorly understood. We have been addressing this question using striated muscle cells, which have regular arrays of membranes that associate with the contractile apparatus in stereotypic patterns. Here we examine links between contractile structures and the sarcoplasmic reticulum (SR) established by small ankyrin 1 (sAnk1), a ∼17.5-kDa integral protein of network SR. We used yeast two-hybrid to identify obscurin, a giant Rho-GEF protein, as the major cytoplasmic ligand for sAnk1. The binding of obscurin to the cytoplasmic sequence of sAnk1 is mediated by a sequence of obscurin that is C-terminal to its last Ig-like domain. Binding was confirmed in two in vitro assays. In one, GST-obscurin, bound to glutathione-matrix, specifically adsorbed native sAnk1 from muscle homogenates. In the second, MBP-obscurin bound recombinant GST-sAnk1 in nitrocellulose blots. Kinetic studies using surface plasmon resonance yielded a KD= 130 nM. On subcellular fractionation, obscurin was concentrated in the myofibrillar fraction, consistent with its identification as sarcomeric protein. Nevertheless, obscurin, like sAnk1, concentrated around Z-disks and M-lines of striated muscle. Our findings suggest that obscurin binds sAnk1, and are the first to document a specific and direct interaction between proteins of the sarcomere and the SR.
Golgi Localization of Syne-1
Authors: Gough Lisa Lucio , Fan Jun , Chu Stephen , Winnick Shawn , Beck Kenneth A.
Published: March 2003

We have previously identified a Golgi-localized spectrin isoform by using an antibody to the β-subunit of erythrocyte spectrin. In this study, we show that a screen of a λgt11 expression library resulted in the isolation of an ∼5-kb partial cDNA from a Madin-Darby bovine kidney (MDBK) cell line, which encoded a polypeptide of 1697 amino acids with low, but detectable, sequence homology to spectrin (37%). A blast search revealed that this clone overlaps with the 5′ end of a recently identified spectrin family member Syne-1B/Nesprin-1β, an alternately transcribed gene with muscle-specific forms that bind acetylcholine receptor and associate with the nuclear envelope. By comparing the sequence of the MDBK clone with sequence data from the human genome database, we have determined that this cDNA represents a central portion of a very large gene (∼500 kb), encoding an ∼25-kb transcript that we refer to as Syne-1. Syne-1 encodes a large polypeptide (8406 amino acids) with multiple spectrin repeats and a region at its amino terminus with high homology to the actin binding domains of conventional spectrins. Golgi localization for this spectrin-like protein was demonstrated by expression of epitope-tagged fragments in MDBK and COS cells, identifying two distinct Golgi binding sites, and by immunofluorescence microscopy by using several different antibody preparations. One of the Golgi binding domains on Syne-1 acts as a dominant negative inhibitor that alters the structure of the Golgi complex, which collapses into a condensed structure near the centrosome in transfected epithelial cells. We conclude that the Syne-1 gene is expressed in a variety of forms that are multifunctional and are capable of functioning at both the Golgi and the nuclear envelope, perhaps linking the two organelles during muscle differentiation.
Dissociating the Centrosomal Matrix Protein AKAP450 from Centrioles Impairs Centriole Duplication and Cell Cycle Progression
Authors: Keryer Guy , Witczak Oliwia , Delouvée Annie , Kemmner Wolfram A. , Rouillard Danielle , Taskén Kjetil , Bornens Michel
Published: March 2003

Centrosomes provide docking sites for regulatory molecules involved in the control of the cell division cycle. The centrosomal matrix contains several proteins, which anchor kinases and phosphatases. The large A-Kinase Anchoring Protein AKAP450 is acting as a scaffolding protein for other components of the cell signaling machinery. We selectively perturbed the centrosome by modifying the cellular localization of AKAP450. We report that the expression in HeLa cells of the C terminus of AKAP450, which contains the centrosome-targeting domain of AKAP450 but not its coiled-coil domains or binding sites for signaling molecules, leads to the displacement of the endogenous centrosomal AKAP450 without removing centriolar or pericentrosomal components such as centrin, γ-tubulin, or pericentrin. The centrosomal protein kinase A type II α was delocalized. We further show that this expression impairs cytokinesis and increases ploidy in HeLa cells, whereas it arrests diploid RPE1 fibroblasts in G1, thus further establishing a role of the centrosome in the regulation of the cell division cycle. Moreover, centriole duplication is interrupted. Our data show that the association between centrioles and the centrosomal matrix protein AKAP450 is critical for the integrity of the centrosome and for its reproduction.
Facial expressions, their communicatory functions and neuro–cognitive substrates
Authors: Blair R. J. R.
Published: March 2003

Human emotional expressions serve a crucial communicatory role allowing the rapid transmission of valence information from one individual to another. This paper will review the literature on the neural mechanisms necessary for this communication: both the mechanisms involved in the production of emotional expressions and those involved in the interpretation of the emotional expressions of others. Finally, reference to the neuro–psychiatric disorders of autism, psychopathy and acquired sociopathy will be made. In these conditions, the appropriate processing of emotional expressions is impaired. In autism, it is argued that the basic response to emotional expressions remains intact but that there is impaired ability to represent the referent of the individual displaying the emotion. In psychopathy, the response to fearful and sad expressions is attenuated and this interferes with socialization resulting in an individual who fails to learn to avoid actions that result in harm to others. In acquired sociopathy, the response to angry expressions in particular is attenuated resulting in reduced regulation of social behaviour.
The manifold nature of interpersonal relations: the quest for a common mechanism
Authors: Gallese Vittorio
Published: March 2003

It has been proposed that the capacity to code the ‘like me’ analogy between self and others constitutes a basic prerequisite and a starting point for social cognition. It is by means of this self/other equivalence that meaningful social bonds can be established, that we can recognize others as similar to us, and that imitation can take place.

In this article I discuss recent neurophysiological and brain imaging data on monkeys and humans, showing that the ‘like me’ analogy may rest upon a series of ‘mirror–matching’ mechanisms. A new conceptual tool able to capture the richness of the experiences we share with others is introduced: theshared manifoldof intersubjectivity. I propose that all kinds of interpersonal relations (imitation, empathy and the attribution of intentions) depend, at a basic level, on the constitution of a shared manifold space. This shared space is functionally characterized by automatic, unconscious embodied simulation routines.
Computational approaches to motor learning by imitation
Authors: Schaal Stefan , Ijspeert Auke , Billard Aude
Published: March 2003

Movement imitation requires a complex set of mechanisms that map an observed movement of a teacher onto one's own movement apparatus. Relevant problems include movement recognition, pose estimation, pose tracking, body correspondence, coordinate transformation from external to egocentric space, matching of observed against previously learned movement, resolution of redundant degrees–of–freedom that are unconstrained by the observation, suitable movement representations for imitation, modularization of motor control, etc. All of these topics by themselves are active research problems in computational and neurobiological sciences, such that their combination into a complete imitation system remains a daunting undertaking—indeed, one could argue that we need to understand the complete perception–action loop. As a strategy to untangle the complexity of imitation, this paper will examine imitation purely from a computational point of view, i.e. we will review statistical and mathematical approaches that have been suggested for tackling parts of the imitation problem, and discuss their merits, disadvantages and underlying principles. Given the focus on action recognition of other contributions in this special issue, this paper will primarily emphasize the motor side of imitation, assuming that a perceptual system has already identified important features of a demonstrated movement and created their corresponding spatial information. Based on the formalization of motor control in terms of control policies and their associated performance criteria, useful taxonomies of imitation learning can be generated that clarify different approaches and future research directions.
Causal path modeling: what it does and what it does not tell us
Authors: Bozionelos Nikos
Published: March 2003

This paper attempts to demystify the technique of causal path modeling for the non‐specialists by presenting aspects of its value for social science and management research and by illustrating common misunderstandings about its attributes. Special emphasis is placed on the real world validity of causal relationships depicted in causal path models and on the information that the data‐fitting properties of causal path models provide regarding this issue. Causal path models that are based on research in antecedents of career success are used to illustrate the points that are made. It is stressed that the validity of causal relationships depicted in causal path models is subject to exactly the same methodological restrictions as the validity of causality claims that are made without the use of causal path modeling; and that the purpose of using quantitative techniques in causal path modeling is not to improve certainty on causality direction.
Testing the endogenous growth model: public expenditure, taxation, and growth over the long run
Authors: Bleaney Michael , Gemmell Norman , Kneller Richard
Published: March 2003

Endogenous growth models, such as Barro (1990), predict that government expenditure and taxation will have both temporary and permanent effects on growth. We test this prediction using panels of annual and period‐averaged data for OECD countries during 1970–95, isolating long‐run from short‐run fiscal effects. Our results strongly support the endogenous growth model and suggest that long‐run fiscal effects are not fully captured by period averaging and static panel methods. Unlike previous investigations, our estimates are free from biases associated with incomplete specification of the government budget constraint and do not appear to result from endogeneity of fiscal or investment variables. JEL Classification: H30, O40

Validation du modèle de croissance endogène: dépenses publiques, fiscalité et croissance à long terme. Des modèles de croissance endogène comme celui de Barro (1990) prédisent que dépenses gouvernementales et fiscalité vont avoir des effets temporaires et permanents sur la croissance. On met cette prévision au test à l'aide de données annuelles et pour certaines moyennes couvrant des sous‐périodes pour les pays de l'OCDE (1970–95) dans le but de départager les effets à court et à long terme. Les résultats valident fortement le modèle de croissance endogène et suggèrent que les effets fiscaux à long terme ne sont pas pleinement capturés par des méthodes utilisant des moyennes ou des méthodes statiques. Contrairement aux résultats d'enquêtes antérieures, les résultats proposés ne souffrent pas de distorsions attribuables à une spécification incomplète de la contrainte budgétaire du gouvernement, et ne semblent pas être l'effet d'écho de l'endogénéité des variables fiscales et de l'investissement.
Price, scarcity rent, and a modified r per cent rule for non‐renewable resources
Authors: Livernois John , Martin Patrick
Published: March 2003

Since Hotelling's seminal paper on the optimal depletion of exhaustible resources, much has been published; yet confusion remains about whether scarcity rent and price increase or decrease as a resource is depleted when costs tend to rise with depletion. We show that Hotelling's fundamental results of rising scarcity rent and price paths are sustained and that the path of scarcity rent converges on the r per cent rule, provided the objective function is concave. Predictions of non‐monotonic or declining scarcity rent paths are due to implicit assumptions that lead to a non‐concave objective function. We identify the sources of these non‐concavities. JEL Classification: Q30, D90, C60

Prix, rente de rareté et une règle modifiée du r‐pourcent pour les ressources non renouvelables. Malgré la volumineuse littérature spécialisée qui a fleuri depuis qu'Hotelling a écrit son mémoire fondateur sur l'épuisement optimal des ressources renouvelables, une grande confusion règne toujours quand il faut établir si la rente de rareté et le prix augmentent ou chutent à proportion que la ressource s'épuise quand les coûts tendent à croître avec l'épuisement. Ce mémoire montre que les résultats fondamentaux obtenus par Hotelling quant aux sentiers de croissance de la rente de rareté et du prix tiennent toujours, et que le sentier de croissance de la rente de rareté converge vers la règle du r‐pourcent pourvu que la fonction objective soit concave. Les prédictions de sentiers de croissance non monotone ou de déclin de la rente de rareté présentées dans la littérature spécialisée sont attribuables à des postulats implicites qui engendrent une fonction objective non concave. Les auteurs identifient les sources de ces non‐concavités.
Information Linkages in Local Economic Development
Authors: Weiler Stephan , Scorsone Eric , Pullman Madeleine
Published: March 2003

Profitable private investments may be bypassed in struggling regions due precisely to such regions' isolation, leading to a self‐reinforcing cycle of marginalization. In many cases, development in such regions may be most effectively promoted by providing key information to the private and public sectors, thus addressing potentially significant market failures. In the case study project, the calculation of private and social returns have been particularly crucial in sparking both private investor interest and public support of this business venture. The project's example suggests an updated role for universities in the assistance of productive economic development programs.
The Impact of Public School Attributes on Home Sale Prices in California
Authors: Clark David E. , Herrin William E.
Published: March 2003

The quality of public schools is often cited as an important attribute which distinguishes a community. Indeed, a recent public opinion poll conducted by the California Public Education Partnership indicates that residents rank improvements in public education higher than such high profile issues as environmental quality and crime reduction. In order to explore the role of educational quality in determining residential property values, a hedonic housing price model is used on a large sample of homes which sold within Fresno County in California over the period 1990‐1994. After controlling for a wide range of housing characteristics and neighborhood features, the findings indicate that the school district does significantly influence the real sale price. Then the relative importance of inputs into the production of educational services is investigated as compared to output measures of productivity. These findings suggest that both input and output measures are important. However, elasticity estimates of input measures tend to be higher than those of output measures, with the average class size by far the strongest influence. There is some evidence to suggest that the benefits of additional teachers likely outweigh the costs. Finally, the findings suggest that attributes of schools are more highly valued by local residents than either crime or environmental quality measures within the community.
Regional Variations of Firm Births, Deaths and Growth Patterns in the UK, 1980–1991
Authors: Fotopoulos Georgios , Spence Nigel
Published: March 2003

One of the debates around new firm formation across sub‐national territories focuses on whether regional differences in industrial structure are more important influences than regional differences in individual industry performance. The present research, using Value Added Tax (VAT) registration data, attempts to make a contribution to this debate in the United Kingdom (UK) context using a shift‐share covariance model. Firm de‐registrations and, as a consequence, net changes in firm stocks are also analyzed with similar questions in mind. The findings show that although the effects of industrial mix are significant across most regions, in several key regional contexts the industrial competitive effect dominates. The issue of the role of regional industrial concentration forms a second major theme of this paper. This basically involves a questioning as to whether concentration is a positive or negative force for new firm formation. The results of this research indicate that industrial concentration, measured through localization, is more important for firm deaths than for firm births (although significant for both), but not particularly relevant to the understanding of the net outcome of entry and exit processes. In the UK, regions with higher levels of industry concentration seem to be associated overall with relatively lower levels of both firm births and deaths.
The Impact of Trade Liberalization on Regional Disparities in Mexico
Authors: Sánchez‐Reaza Javier , Rodríguez‐Pose Andrés
Published: March 2003

After a long period of industrialization based on import substitution (ISI), Mexico started to open up its economy by accessing the General Agreement on Tariffs and Trade (GATT) in 1986. The export‐promotion strategy was transformed into one of regional integration with the signing of the North American Free Trade Agreement (NAFTA) in 1994. The paper explores the impact of the opening of the economy on regional disparities in Mexico using σ and β‐convergence analyses. Four different samples have been employed to control for possible data bias linked to the inclusion of oil‐producing and maquiladora‐based states. The results show that whereas the final stages of the ISI period were dominated by convergence trends, trade liberalization (GATT) and economic integration (NAFTA) have led to divergence. In particular, the NAFTA period is related to divergence regardless of the type of analysis chosen and the sample used.
Testing the Random Walk Behavior and Efficiency of the Gulf Stock Markets
Authors: Abraham Abraham , Seyyed Fazal J. , Alsakran Sulaiman A.
Published: March 2003

Inferences drawn from tests of market efficiency are rendered imprecise in the presence of infrequent trading. As the observed index in thinly traded markets may not represent the true underlying index value, there is a systematic bias toward rejecting the efficient market hypothesis. For the three emerging Gulf markets examined in this paper, correction for infrequent trading significantly alters the results of market efficiency and random walk tests. The Beveridge–Nelson (1981) decomposition of index returns is done to estimate the underlying index.
Abstractional Concept Mapping: A Foundational Model for Analogical Reasoning
Authors: Dierbach Charles , Chester Daniel L.
Published: March 2003

We present a mathematical model providing a formal basis for analogical reasoning, referred to as abstractional concept mapping. The approach provides a formal basis for all comparison–based reasoning (e.g., literal similarity, analogy, metaphor, and scientific models) in that given any two descriptions in first–order logic, arbitrary comparisons of similarity are representable as first–order theories (referred to as “comparison theories”), dependent only on the notion of logical truth and not on domain–specific heuristics or particular features of the knowledge representation.
Integrating Case‐Based and Rule‐Based Reasoning to Meet Multiple Design Constraints
Authors: Marling C. R. , Petot G. J. , Sterling L. S.
Published: March 2003

Although case‐based reasoning (CBR) was introduced as an alternative to rule‐based reasoning (RBR), there is a growing interest in integrating it with other reasoning paradigms, including RBR. New hybrid approaches are being piloted to achieve new synergies and improve problem‐solving capabilities. In our approach to integration, CBR is used to satisfy multiple numeric constraints, and RBR allows the performance of “what if” analysis needed for creative design.

The domain of our investigation is nutritional menu planning. The task of designing nutritious, yet appetizing, menus is one at which human experts consistently outperform computer systems. Tailoring a menu to the needs of an individual requires satisfaction of multiple numeric nutrition constraints plus personal preference goals and aesthetic criteria.

We first constructed and evaluated independent CBR and RBR menu planning systems, then built a hybrid system incorporating the strengths of each system. The hybrid outperforms either single strategy system, designing superior menus, while synergistically providing functionality that neither single strategy system could provide. In this paper, we present our hybrid approach, which has applicability to other design tasks in which both physical constraints and aesthetic criteria must be met.
Maintaining Case‐Based Reasoners: Dimensions and Directions
Authors: Wilson David C. , Leake David B.
Published: March 2003

Experience with the growing number of large‐scale and long‐term case‐based reasoning (CBR) applications has led to increasing recognition of the importance of maintaining existing CBR systems. Recent research has focused on case‐base maintenance (CBM), addressing such issues as maintaining consistency, preserving competence, and controlling case‐base growth. A set of dimensions for case‐base maintenance, proposed by Leake and Wilson, provides a framework for understanding and expanding CBM research. However, it also has been recognized that other knowledge containers can be equally important maintenance targets. Multiple researchers have addressed pieces of this more general maintenance problem, considering such issues as how to refine similarity criteria and adaptation knowledge. As with case‐base maintenance, a framework of dimensions for characterizing more general maintenance activity, within and across knowledge containers, is desirable to unify and understand the state of the art, as well as to suggest new avenues of exploration by identifying points along the dimensions that have not yet been studied. This article presents such a framework by (1) refining and updating the earlier framework of dimensions for case‐base maintenance, (2) applying the refined dimensions to the entire range of knowledge containers, and (3) extending the theory to include coordinated cross‐container maintenance. The result is a framework for understanding the general problem of case‐based reasoner maintenance (CBRM). Taking the new framework as a starting point, the article explores key issues for future CBRM research.
Applications of Rough Genetic Algorithms
Authors: Lingras Pawan , Davies Cedric
Published: March 2003

This paper describes rough genetic algorithms based on the notion of interval values. A gene in a rough genetic algorithm can be represented using an interval. The paper explains how this generalization facilitates development of new genetic operators and evaluation measures. Various operations of rough genetic algorithms are illustrated using a simple document retrieval example. An experiment involving classification of interval‐valued traffic patterns demonstrates the usefulness of rough genetic algorithms for real‐world applications. A discussion on further extensions of rough genetic algorithms to rough sets is also included.
Granular Computing: a Rough Set Approach
Authors: Nguyen Son H. , Skowron Andrzej , Stepaniuk Jarosław
Published: March 2003

We discuss information granule calculi as a basis of granular computing. They are defined by constructs like information granules, basic relations of inclusion and closeness between information granules as well as operations on them. The exact interpretation between granule languages of different information sources (agents) often does not exist. Hence (rough) inclusion and closeness of granules are considered instead of their equality. Examples of all the basic constructs of information granule calculi are presented. The construction of more complex information granules is described by expressions called terms. We discuss the synthesis problem of robust terms, i.e., descriptions of information granules, satisfying a given specification in a satisfactory degree. We also present a method for synthesis of information granules represented by robust terms (approximate schemes of reasoning) by means of decomposition of specifications for such granules. The discussed problems of granular computing are of special importance for many applications, in particular related to spatial reasoning as well as to knowledge discovery and data mining.
The Guardian State: A Comparative Analysis of Interest Group Regulation
Authors: Yishai Yael
Published: March 2003

This article discusses the regulation of interest groups by the state in four democracies: two liberal, namely Australia and Canada, and two nonliberal, namely Israel and Turkey. The analysis centers on five questions: the scope of regulation, its causes, public reaction to regulation, implementation of regulation, and its impact on state and society. The article suggests that the type of regime does make a difference regarding all parameters of regulation. Liberal democracies tend to regulate strategy of interest groups; regulation is caused by fear of undue associational pressure exerted on decision‐makers. The public tends to be hostile to regulation; implementation is strict, but impact on both interest groups and society is modest. Nonliberal democracies tend to regulate interest groups' structure. Regulation is caused by fear of subversion and threats to the state's survival. The public is compliant disregarding regulation. Implementation is lax and impact may be potentially substantial. These hypotheses were largely confirmed in the four cases under consideration.
The Solitary Center: the Core Executive in Central and Eastern Europe
Authors: Goetz Klaus H. , Margetts Helen Z.
Published: March 2003

This article discusses the coordinative capacity of Centers of Government (COGs) in several Central and Eastern Europe countries. In formal terms, COGs are at the heart of the executive process; but their contribution to coherence in executive policymaking has remained limited. This observation applies both to coordination within the executive, and between the executive and other key participants in the political process. In important respects, the “solitary centers” operate in isolation from their political and institutional environment. In part, this weakness of linkage reflects the particular features of the post‐Communist political systems; in part, it can be explained by a lack of nodality, authority and policy expertise at the COG. There are good reasons to assume that, as policy systems mature, problems of linkage will decline in significance. But this outcome cannot be taken for granted. Instead, we might be witnessing the emergence of a “new administrative type” in some Central and Eastern European countries.
Veto Players and Institutional Analysis
Authors: Tsebelis George
Published: March 2003

The veto players theory can be used to analyze all political systems regardless of regime (presidential or parliamentary), party system (one‐, two‐, or multiparty), and type of parliament (unicameral or multicameral). This paper develops the veto players theory to account for a series of important political phenomena: the difference between majoritarian and supermajoritarian institutions; the importance of absenteeism, or of political marginalization; the importance of agenda control and referendums; the reasons for government stability (parliamentary systems) and regime stability (presidential systems); the reasons for independence of bureaucracies, and judicial independence. All these phenomena are analyzed in a coherent way, on the basis of the same framework. Empirical evidence from existing literature corroborating the theory is provided.
Principles for Public Management Practice: From Dichotomies to Interdependence
Authors: Feldman Martha S. , Khademian Anne M.
Published: March 2003

In this essay we explore the relationship between management practices and a basic governance dilemma: how to manage flexibly and accountably. The challenge is both practical and theoretical. Managers must respond flexibly to the changing demands and expectations of the public and the ever‐changing nature of public problems, yet they must do so in a manner that provides accountability to the public and political overseers. A dichotomous approach to the study of leadership as management action and the governance structures within which managers operate has inhibited the search for a public management theory that reconciles the dilemma. Emphasis upon managers as leaders typically focuses on the flexible actions managers might take to overcome structural “barriers,” while emphasis upon governance structures typically focuses on the essential role of structure in ensuring accountability and restraining or motivating particular management efforts. The practicing manager, however, cannot deal with these aspects of the work separately. Managers must attend to demands for both flexible leadership action and structures that promise accountability. Anecdotal evidence provides illustrations of some of the ways that managers can integrate these demands. We suggest that these efforts point to an alternative theoretical framework that understands action and structure as mutually constitutive, creating a dynamic tension in which attention to one requires attention to the other.
Quangos—What's in a Name? Defining Quangos from a Comparative Perspective
Authors: Greve Carsten , Flinders Matthew , Van Thiel Sandra
Published: March 2003

Without definitional clarity the “quango debate” is inherently flawed and meaningful progress undermined. A possible solution to this problem is proposed in this article by way of a subsectional map which aims to clarify the quango topography. This accepts the diversity inherent in the quango debate while allowing for increased clarity and focused research. This, the authors believe, is the only way forward for practitioners, academics and policymakers working within the sphere of quasi‐government. There is a need to address precise forms or subsections of the quango continuum as studies or reforms which focus on one type of quango would not necessarily work if applied to all quangos, or quangos in other countries.
The Bureaucrat Who Fell Under a Bus: Ministerial Responsibility, Executive Agencies and The Derek Lewis Affair in Britain
Authors: Polidano Charles
Published: March 2003

Various concerns have been raised about the practicability of Next Steps and the adequacy of accountability mechanisms in Britain, particularly after the dismissal of Derek Lewis as chief executive of the Prison Service. This article critically reviews these concerns. It argues that the agency model is viable notwithstanding doubts about the practicability of the policy–operations distinction; that Next Steps is not the cause of defective accountability or the scapegoating of bureaucrats by ministers; and that a commonly proposed solution—making agency heads accountable to parliamentary select committees—has fundamental drawbacks of its own. The “conventional wisdom” that Next Steps cannot work ignores important evidence and badly needs reassessment.
A Cultural Perspective on Negotiation: Progress, Pitfalls, and Prospects
Authors: Gelfand Michele , Dyer Naomi
Published: March 2003

Cet article passe en revue les vingt dernie`res anne´es de recherche sur la culture et la ne´gociation et pre´sente les progre`s qui ont e´te´ faits, les pie`ges dont il faut se de´fier et les perspectives pour de futurs travaux. On a remarque´ que beaucoup de recherches avaient tendance a` suivre ces deux mode`les implicites: (1) l’influence de la culture sur les strate´gies et l’aboutissement de la ne´gociation et/ou (2) l’interaction de la culture et d’autres aspects de la situation imme´diate sur les re´sultats de la ne´gociation. Cette recherche a porte´ sur un grand nombre de cultures et a mis en e´vidence plus d’un mode`le inte´ressant. Nous signalons cependant trois pie`ge caracte´ristiques de cette litte´rature, pie`ges qui nous ont handicape´s. Tout d’abord, la plupart des travaux se satisfont de de´nominations ge´ographiques pour de´signer les cultures et il est par suite souvent impossible de de´terminer les dimensions culturelles qui rendent compte des diffe´rences observe´es. Ensuite, beaucoup de recherches ignorent les processus psychologiques (c’est‐a`‐dire les motivations et les cognitions) qui sont en jeu dans les ne´gociations prenant place dans des cultures diffe´rentes si bien que nous apprenons peu de choses a` propos de la psychologie de la ne´gociation dans des contextes culturels diversifie´s. On se heurte ainsi a` une ûboîte noireÃ½ que les travaux sur la culture et la ne´gociation se gardent ge´ne´ralement d’ouvrir. Enfin, notre travail n’a recense´ qu’un nombre restreint de variables situationnelles imme´diates intervenant dans des ne´gociations prenant place dans des cultures diffe´rentes; notre compre´hension des effets mode´rateurs de la culture sur la ne´gociation est donc limite´e. Nous proposons un troisie`me mode`le, plus complet, de la culture et de la ne´gociation, pre´sentons quelques donne´es re´centes en sa faveur et esquissons quelques perspectives pour l’avenir.