bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bias reduction for risk ratio and vaccine effect estimators
Authors: Chick Stephen E. , Barth‐Jones Daniel C. , Koopman James S. 
Published: August 2002

AbstractWe examine the structural bias for established estimators of vaccine effects on susceptibility and for newer estimates of vaccine effects on infectiousness. We then propose and analyse new bias corrections for vaccine effect estimators of both susceptibility and infectiousness, as well as their combined effect on infection transmission. Each estimator is evaluated empirically with computer simulations. Of the estimators examined in this paper, those with the least bias and root mean squared error are computed by adding one to the positive count in the placebo population. We also identify a source of bias for a standard Bayesian estimator of risk ratios. Copyright © 2001 John Wiley & Sons, Ltd.
Asset divestiture following horizontal acquisitions: a dynamic view
Authors: Capron Laurence , Mitchell Will , Swaminathan Anand 
Published: August 2002

AbstractBusiness acquisition, resource redeployment, and asset divestiture are elements of a dynamic process in which firms change their businesses by recombining internal and external resources. Analyzing 253 horizontal acquisitions, we show that post‐acquisition resource redeployment leads to asset divestiture from the business that receives the redeployed resources, but not from the business that contributes the new resources. Consistent with scale economies rationales, we find that strategic similarity also leads to greater asset divestiture from the target firms. Many theoretical perspectives are skeptical about the positive rationale for acquisitions and many of these believe that asset divestiture is evidence of acquisition failure. Our arguments and analysis help refine the accepted wisdom. In particular, the pattern of resource redeployment and asset divestiture in our analysis suggests that acquisitions provide a means of reconfiguring the structure of resources within firms and that asset divestiture is a logical consequence of this reconfiguration process. Copyright © 2001 John Wiley & Sons, Ltd.
An operationalization of Stevenson's conceptualization of entrepreneurship as opportunity‐based firm behavior
Authors: Brown Terrence E , Davidsson Per , Wiklund Johan 
Published: August 2002

AbstractStevenson (1983) holds that entrepreneurial management, defined as a set of opportunity‐based management practices, can help firms remain vital and contribute to firm and societal level value creation. While his conceptualization has received much attention, little progress has been made because of a lack of empirical tools to examine his propositions. This article seeks to resolve this by describing a new instrument that was developed specifically for operationalizing Stevenson's conceptualization. After two pre‐tests, the instrument was tested full scale on a very large (1200+ cases) stratified random sample of firms with different size, governance structure, and industry affiliation. The results show that both in the full sample and in various sub‐samples it was possible to identify six sub‐dimensions with high discriminant validity and moderate to high reliability, which represent dimensions of Stevenson's theoretical reasoning. We label these Strategic Orientation, Resource Orientation, Management Structure, Reward Philosophy, Growth Orientation and Entrepreneurial Culture. We were further able to show that these dimensions only partly overlap with ‘Entrepreneurial Orientation’, the hitherto best established empirical instrument for assessing a firm's degree of entrepreneurship. Our instrument should open up opportunities for researchers to further evaluate entrepreneurship in existing firms. Copyright © 2001 John Wiley & Sons, Ltd.
When do firms learn from their acquisition experience? Evidence from 1990 to 1995
Authors: Hayward Mathew L. A. 
Published: August 2002

AbstractI use an organizational learning perspective to examine how the nature, performance and timing of a firm's acquisition experience helps it to learn how to select the right acquisition. I predict the performance of 214 acquisitions made by 120 firms in 6 industries between 1990 and 1995. Results show that a firm's focal acquisition performance positively relates to prior acquisitions that are a) not highly similar or dissimilar to the focal acquisition, b) associated with small losses and c) not too temporally close to or distant from the focal acquisition. Taken together, these results identify the broad conditions in which firms generate adaptive and timely inferences from acquisition experience. Copyright © 2002 John Wiley & Sons, Ltd.
Kainate‐induced currents in rat cortical neurons in culture are modulated by riluzole
Authors: Zona Cristina , Cavalcanti Silvio , De Sarro Giovanbattista , Siniscalchi Antonio , Marchetti Caterina , Gaetti Chiara , Costa Nicola , Mercuri Nicola , Bernardi Giorgio 
Published: August 2002

AbstractThe action of the neuroprotective and anticonvulsant agent riluzole on kainate‐induced currents was studied in rat cortical neurons in primary culture by using the whole‐cell configuration of the patch‐clamp technique. Kainate elicited macroscopic, 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX)‐sensitive inward currents in all the patched cells and the amplitude of the current was concentration‐dependent (EC50= 106 μM). Riluzole decreased the inward currents induced by 100 μM kainate at all holding potentials and the reduction was dose‐dependent (IC50= 101 μM). The maximal response to kainate decreased in the presence of 50 μM riluzole, without changing its EC50, indicating a noncompetitive mechanism of inhibition. The amplitude of the responses induced by kainate under control conditions and during riluzole was a linear function of the membrane potential and the reversal potential of the currents was not significantly different in the two experimental conditions. Instead, the total conductance of the cell membrane for the currents induced by 100 μM kainate was significantly reduced in the presence of 50 μM riluzole (P < 0.05). The analysis of the kainate membrane current noise performed under control conditions and during perfusion of 100 μM riluzole revealed that riluzole reduced the probability of kainate‐activated ionic channels to be in the open state. Conversely, the unitary conductance of channels, as well as their characteristic time constant, seemed to be unchanged. These results reveal an additional mechanism by which riluzole can interact with glutamatergic neurotransmission and provides further support for the idea that riluzole may prove beneficial in the treatment of central nervous system injuries involving the excitotoxic actions of glutamate. Synapse 43:244–251, 2002. © 2002 Wiley‐Liss, Inc.
Acute and chronic caffeine administration differentially alters striatal gene expression in wild‐type and adenosine A2A receptor‐deficient mice
Authors: Dassesse Donald , Ledent Catherine , Parmentier Marc , Schiffmann Serge N. 
Published: August 2002

AbstractIn order to assess for the respective involvement of adenosine A1 and A2A receptors (A2A‐R) in the consequences of short‐ and long‐term caffeine exposure on gene expression, the effects of acute caffeine administration on striatal, cortical, and hippocampal expression of immediate early genes (IEG), zif‐268 and arc, and the effects of long‐term caffeine or 1,3‐dipropyl‐8‐cyclopentylxanthine (DPCPX) exposure (once daily for 15 days) on striatal gene expression of substance P, enkephalin, and glutamic acid decarboxylase isoforms, GAD65 and GAD67, were evaluated in wild‐type and A2A‐R‐deficient (A2A‐R−/−) mice. In situ hybridization histochemistry was performed using oligonucleotides followed by quantitative image analysis. Our results demonstrated that a biphasic response of IEG expression to acute caffeine observed in the wild‐type striatum was resumed in a monophasic response in the mutant striatum. In the cerebral cortex and hippocampus, the effect of caffeine was weak in wild‐type, whereas in mutant mice it induced a 2–3‐fold increase in the IEG expression to restore a level similar to the wild‐type basal expression. Chronic caffeine and DPCPX‐mediated regulation in neuropeptide and GADs striatal gene expression typically showed the mimicking of alterations resulting from the A2A‐R genetic deficiency in 25 mg/kg caffeine‐treated wild‐type mice as well as the dose‐dependent normalization of substance P and enkephalin expression in A2A‐R−/− mice. These results indicate that, depending on the dose, the blockade of A2A‐R or A1 receptors by caffeine is preferentially revealed leading to highly differential alterations in striatal gene expression and they also suggested the central role of these two receptors on the control of dopaminergic functions. Synapse 42:63–76, 2001. © 2001 Wiley‐Liss, Inc.
Expression of serotonin 5‐HT2A receptors in the human cerebellum and alterations in schizophrenia
Authors: Eastwood Sharon L. , Burnet Philip W.J. , Gittins Rebecca , Baker Kate , Harrison Paul J. 
Published: August 2002

AbstractThe occurrence of human cerebellar serotonin 5‐HT2A receptors (5‐HT2AR) is equivocal and their status in schizophrenia unknown. Using a range of techniques, we investigated cerebellar 5‐HT2AR expression in 16 healthy subjects and 16 subjects with schizophrenia. Immunocytochemistry with a monoclonal antibody showed labelling of Purkinje cell bodies and dendrites, as well as putative astrocytes. Western blots showed a major band at ∼45 kDa. Receptor autoradiography and homogenate binding with [3H]ketanserin revealed cerebellar 5‐HT2AR binding sites present at levels approximately a third of that in prefrontal cortex. 5‐HT2AR mRNA was detected by reverse transcriptase‐polymerase chain reaction, with higher relative levels in men than women. Several aspects of 5‐HT2AR expression were altered in schizophrenia. 5‐HT2AR immunoreactivity in Purkinje cells was partially redistributed from soma to dendrites and was increased in white matter. 5‐HT2AR mRNA was decreased in the male patients. 5‐HT2AR measured by dot blots and [3H]ketanserin binding (Bmax and Kd) were not significantly altered in schizophrenia. These data show that 5‐HT2AR gene products (mRNA, protein, binding sites) are expressed in the human cerebellum at nonnegligible levels; this bears upon 5‐HT2AR imaging studies which use the cerebellum as a reference region. 5‐HT2AR expression is altered in schizophrenia; the shift of 5‐HT2AR from soma to dendrites is noteworthy since atypical antipsychotics have the opposite effect. Finally, the results emphasise that expression of a receptor gene is a mutifaceted process. Measurement of multiple parameters is necessary to give a clear picture of the normal situation and to show the profile of alterations in a disease. Synapse 42:104–114, 2001. © 2001 Wiley‐Liss, Inc.
Effects of griseofulvin in medium‐term liver carcinogenesis assay and peripheral blood micronucleus test in rat
Authors: Labay Karine , Ould‐Elhkim Mostafa , Klés Virginie , Guffroy Magali , Poul Jean‐Michel , Sanders Pascal 
Published: August 2002

AbstractPublished data have suggested a possible link between the tumor promoting activity and the aneugenic properties of griseofulvin. The present study was conducted to explore this relationship. Griseofulvin was evaluated both for its potential promoting activity in liver carcinogenesis in partially hepatectomized F344 male rats initiated by diethylnitrosamine and for its genotoxic potential in the peripheral blood micronucleus assay. Rats were treated daily with 2,000 mg/kg body weight by oral gavage for 12 weeks in the medium‐term carcinogenesis bioassay. GST‐P‐positive foci (mean number and surface area) and altered cell foci were compared in the liver of rats treated with griseofulvin alone, diethylnitrosamine alone ,and griseofulvin in addition to diethylnitrosamine by using immunohistochemical and histopathological evaluation, respectively. This evaluation allowed the conclusion that griseofulvin did not initiate the carcinogenic process but rather had a potential in the liver for tumor promoting activity. Griseofulvin was found to be negative in the rat peripheral blood micronucleus test when given at a daily oral dose of 2,000 mg/kg body weight for at least 3 weeks. Teratogenesis Carcinog. Mutagen. 21:441–451, 2001. © 2001 Wiley‐Liss, Inc.
The chemistry and biological function of natural marine toxins
Authors: Yasumoto Takeshi 
Published: August 2002

AbstractStudies on ciguatera fish poisoning led to clarification of the absolute stereochemistry of ciguatoxin, gambierol, gambieric acids, and maitotoxin. Anisotropic NMR reagents and fluorometric chiral HPLC reagents were effectively used together with synthesis of partial structures. Structures of 16 ciguatoxin congeners were successfully elucidated by FAB/MS/MS using samples of 5 μg or less. Stereochemical assignments were also achieved on dinophysistoxin‐1, pectenotoxins, yessotoxins, polycavernoside‐A, azaspiracid, and prymnesins. The toxins possessed poly‐cyclic‐ether structures and originated from unicellular algae. Biological functions are briefly described. © 2000 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:228–242, 2001
The development of lithium ion secondary batteries
Authors: Nishi Yoshio 
Published: August 2002

AbstractLithium ion secondary batteries (LIBs) were successfully developed as battery systems with high volumetric and gravimetric energy densities, which were inherited from lithium secondary batteries (LSBs) with metallic lithium anodes. LSBs have several drawbacks, however, including poor cyclability and quick‐charge rejection. The cell reaction in LIB is merely a topochemical one, namely the migration of lithium ions between positive and negative electroces. No chemical changes were observed in the two electrodes or in the electrolytes. This results in little chemical transformation of the active electrode materials and electrolytes, and thus, LIBs can overcome the weaknesses of LSBs; for example, LIBs show excellent cyclability and quick‐charge acceptance. Many difficulties, however, were encountered during the course of development, including capacity fade during cycling and safety issues. This article is the story of the development of LIBs and it describes how the difficulties were surmounted. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:406–413, 2001
Emergent learning opportunities in an inner‐city youth gardening program
Authors: Rahm Jrene 
Published: August 2002

AbstractAn emphasis on doing science calls for rich descriptions of the kind of science that gets done in such informal educational contexts as science museums and science‐focused after‐school and summer programs. Described in this article is a study of an inner‐city youth gardening program and of the kinds of learning opportunities that it supported and that emerged from youth‐initiated actions and talk. In particular, there is an examination of the ways in which the garden environment and the experiential nature of the program gave support to the emergence of learning opportunities, while also making connections possible among science, community, and work. The description emphasizes the value of a science that emerges from participants' engagement in activities they deem valuable, meaningful, and authentic. In essence, the results of the study show that informal educational programs that do not have science as their primary goal may provide important insights into the development of learning communities in the classroom. The study highlights the educational value of a school science practice that is driven by its consumers, rather than being imposed on them, and that provides opportunities for the integration of science, work, and community. © 2002 John Wiley & Sons, Inc. J Res Sci Teach 39: 164‐184, 2002
Development and application of a two‐tier multiple choice diagnostic instrument to assess high school students' understanding of inorganic chemistry qualitative analysis*
Authors: Tan Kim Chwee Daniel , Goh Ngoh Khang , Chia Lian Sai , Treagust David F. 
Published: August 2002

AbstractThis article describes the development and application of a two‐tier multiple choice diagnostic instrument to assess high school students' understanding of inorganic chemistry qualitative analysis. The development of the diagnostic instrument was guided by the framework outlined by Treagust. The instrument was administered to 915 Grade 10 students (15 to 17 years old) from 11 schools after they had learned the theory involved in qualitative analysis and after a series of qualitative analysis practical sessions. The Cronbach alpha reliability of the instrument was .68, the facility indices ranged from .17 to .48, and the discrimination indices ranged from .20 to .53. The study showed that the Grade 10 students had difficulty understanding the reactions involved in the identification of cations and anions, for example, double decomposition reactions, the formation and reaction of complex salts, and thermal decomposition. The findings of the study and literature on practical work were used to develop a qualitative analysis teaching package. © 2002 Wiley Periodicals Inc. J Res Sci Teach 39: 283–301, 2002
Modeling science teaching on science practice? Painting a more accurate picture through an ethnographic lab study
Authors: Buxton Cory A. 
Published: August 2002

AbstractThis article reports an ethnographic study of a molecular biology research laboratory, “Sally's Lab.” By studying the daily practices of the lab members, and interpreting these observations through an anthropological lens grounded in practice theory, I portray the social and cultural construction of a scientific community. Findings include an examination of how good science practice was operationalized, status in the lab was constructed, members gained or lost interest in continuing on in careers in research science, and individual members conformed to and resisted localized norms of scientific practice. These issues have direct relevance to our work as science educators, in terms of how we present science practice to our students. For example, when K–16 science students engage in activities based on authentic science practice, upon whose experiences are these simulations based? The current study shows that there is not just one acceptable way to do science, nor one set of experiences that pertain to all members within a given community of science practice. Likewise, there should not be just one way that science is presented in school, nor one set of experiences we expect all our students to take from our classes. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 387–407, 2001
Depletion of Mab21l1 and Mab21l2 messages in mouse embryo arrests axial turning, and impairs notochord and neural tube differentiation
Authors: Wong Rebecca Lee Yean , Chow King Lau 
Published: August 2002

AbstractBackgroundThe nematode mab‐21 gene specifies sensory ray cell identity and was first isolated because of its mutant sensory ray defects. Vertebrate Mab21 orthologs have since been identified in mammals and amphibians. In this report, we characterized in detail two Mab21 orthologs in mouse, Mab21l1 and Mab21l2.MethodsWe examined the genomic organizations of Mab21 genes and used northern blot and in situ hybridizations to assay their temporal‐spatial expression pattern. Their embryonic functions were revealed by specific attenuation of Mab21 messages with antisense oligos in cultured embryos.ResultsMab21l1 and Mab21l2 have very similar protein make‐up and gene structures. Both genes were expressed in overlapping domains of actively differentiating embryonic tissues. In addition, Mab21l1 had unique expression in the lens vesicles and genital tubercle whereas Mab21l2 was expressed in the retinal epithelium and umbilical cord. Mab21l1 and Mab21l2 depleted embryos had severe defects in notochord, neural tube, organogenesis, vasculogenesis, and axial turning.ConclusionsThe findings demonstrate that both Mab21 genes are required in developing embryos for embryonic turning, formation of the notochord, neural tube, and other organ tissues. Teratology 65:70–77, 2002. © 2002 Wiley‐Liss, Inc.
Toxicity evaluation of metal plating wastewater employing the Microtox® assay: A comparison with cladocerans and fish
Authors: Choi Kyungho , Meier Peter G. 
Published: August 2002

AbstractThe relative sensitivity of the Microtox assay is closely related to the type of toxicant, and hence its utility in biomonitoring effluents is better evaluated on a case‐by‐case basis. The Microtox® assay, employing the marine bacterium Vibrio fischeri, was evaluated for its applicability in monitoring metal plating wastewater for toxicity. The results of the Microtox assay after 5, 15, and 30 min of exposure, were compared with data obtained from conventional whole effluent toxicity testing (WET) methods that employed Daphnia magna, Ceriodaphnia dubia, and the fathead minnow (Pimephales promelas). The Microtox assay produced notably comparable EC50 values to the LC50 values of the acute fathead minnow toxicity test (<0.5 order of difference). The Spearman's rank correlation analyses showed that the bacterial assay, regardless of exposure duration, correlated better with the acute fish than the daphnid results (p<0.05). These observations were consistent to other studies conducted with inorganic contaminants. The relative sensitivity of the 30‐min Microtox assay was within the range of the two frequently used acute daphnid/fish toxicity tests. In conclusion, the Microtox assay correlated well with the acute fathead minnow data and is well suited for toxicity monitoring for these types of industrial wastes. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 136–141, 2001
Saccharomyces cerevisiae cell wall chitin, the Kluyveromyces lactis zymocin receptor
Authors: Jablonowski Daniel , Fichtner Lars , Martin Vera J. , Klassen Roland , Meinhardt Friedhelm , Stark Michael J. R. , Schaffrath Raffael 
Published: August 2002

AbstractThe exozymocin secreted by Kluyveromyces lactis causes sensitive yeast cells, including Saccharomyces cerevisiae, to arrest growth in the G1 phase of the cell cycle. Despite its heterotrimeric (αβγ) structure, intracellular expression of its smallest subunit, the γ‐toxin, is alone responsible for the G1 arrest. The α subunit, however, has a chitinase activity that is essential for holozymocin action from the cell exterior. Here we show that sensitive yeast cells can be rescued from zymocin treatment by exogenously applying crude chitin preparations, supporting the idea that chitin polymers can compete for binding to zymocin with chitin present on the surface of sensitive yeast cells. Consistent with this, holozymocin can be purified by way of affinity chromatography using an immobilized chitin matrix. PCR‐mediated deletions of chitin synthesis (CHS) genes show that most, if not all, genetic scenarios that lead to complete loss (chs3Δ), blocked export (chs7Δ) or reduced activation (chs4Δ), combined with mislocalization (chs4Δchs5Δ; chs4Δchs6Δ; chs4Δchs5Δchs6Δ) of chitin synthase III activity (CSIII), render cells refractory to the inhibitory effects of exozymocin. In contrast, deletions in CHS1 and CHS2, which code for CSI and CSII, respectively, have no effect on zymocin sensitivity. Thus, CSIII‐polymerized chitin, which amounts to almost 90% of the cell's chitin resources, appears to be the carbohydrate receptor required for the initial interaction of zymocin with sensitive cells. Copyright © 2001 John Wiley & Sons, Ltd.