1,721,682 research outputs found
In vivo labelling of the neuronal dopamine uptake complex in the mouse striatum by [3H]GBR 12783
No full textInternational audienceVarious characteristics of the in vivo striatal binding of [3H]GBR 12783 (1-[2-(diphenylmethoxy)-ethyl]-4-(3-phenyl-1[3H]-2-propenyl)pipera zine), a specific ligand of the neuronal dopamine uptake complex, were determined in mice. Increasing doses of the ligand revealed the saturability of the binding at a single site with half-maximal saturation at a dose of approximately 7 mumol/kg and an apparent maximal number of binding sites (Bmax) of 12.8 pmol/mg protein in striatum. Specific binding was prevented by various dopamine uptake blockers, pyrovalerone, GBR 13069, GBR 12783, N-[1-2-benzo(b)thiophenyl)cyclohexyl] piperidine, cocaine, methylphenidate and was inhibited in a stereoselective manner by the enantiomers of nomifensine. Other drugs which are not dopamine uptake blockers either did not modify [3H]GBR 12783 binding (the diphenylbutylpiperazine derivative flupenthixol) or increased it (the diphenylpiperazine derivative flunarizine or the chemically unrelated compounds fenfluramine and SKF 525A). A close correlation was found between occupancy of the striatal [3H]GBR 12783 binding site and the stimulant locomotor effect of the drug. A similar specific striatal binding of [3H]GBR 12783 was evidenced in both NMRI and CD1 strains. It was concluded that [3H]GBR 12783 administered in vivo provides a measure of the density of dopamine uptake sites in mouse striatum
Relationship between the effects of dexamphetamine on locomotion and on striatal [3H]GBR 12783 binding in vivo
No full textInternational audienceIn mice, low doses (1-2-4 mg/kg s.c.) of dexamphetamine stimulated locomotor activity in a dose-dependent manner. Over the same range of doses the drug dose dependently inhibited the in vivo striatal binding of the dopamine uptake inhibitor, [3H]GBR 12783. At 3 mg/kg dexamphetamine, the stimulant effect and the inhibition of the striatal binding of [3H]GBR 12783 displayed a similar time course. Pretreatments that either increased (L-DOPA 200 mg/kg, benserazide 50 mg/kg i.p.) or decreased (reserpine 5 mg/kg s.c., alpha-methyl-p-tyrosine 200 mg/kg) striatal dopamine levels did not modify the inhibition by dexamphetamine of [3H]GBR 12783 binding in vivo. This suggests that the inhibition is due to a direct effect of dexamphetamine, not mediated by endogenous dopamine, and further that a unique site is responsible for the neuronal uptake of dexamphetamine and for the binding of pure dopamine uptake inhibitors
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Ionic requirements for the specific binding of [3H]GBR 12783 to a site associated with the dopamine uptake carrier
No full textInternational audienceAt 0 degrees C, when Na+ was the only cation present in the incubation medium, increasing the Na+ concentration from 3 to 10 mM enhanced the affinity of [3H]1-[2-(++di-phenylmethoxy)ethyl]-4-(3-phenyl-2-propenyl)piperaz ine [( 3H]GBR 12783) for the specific binding site present in rat striatal membranes without affecting the Bmax. For higher Na+ concentrations, specific binding values plateaued and then slightly decreased at 130 mM Na+. In a 10 mM Na+ medium, the KD and the Bmax were, respectively, 0.23 nM and 12.9 pmol/mg of protein. In the presence of 0.4 nM [3H]GBR 12783, the half-maximal specific binding occurred at 5 mM Na+. A similar Na+ dependence was observed at 20 degrees C. Scatchard plots indicated that K+, Ca2+, Mg2+, and Tris+ acted like competitive inhibitors of the specific binding of [3H]GBR 12783. The inhibitory potency of various cations (K+, Ca2+, Mg2+, Tris+, Li+, and choline) was enhanced when the Na+ concentration was decreased from 130 to 10 mM. In a 10 mM Na+ medium, the rank order of inhibitory potency was Ca2+ (0.13 mM) greater than Mg2+ greater than Tris+ greater than K+ (15 mM). The requirement for Na+ was rather specific, because none of the other cations acted as a substitute for Na+. No anionic requirement was found Cl-, Br-, and F- were equipotent. These results suggest that low Na+ concentrations are required for maximal binding; higher Na+ concentrations protect the specific binding site against the inhibitory effect of other cations
Comparative analysis of morphometric traits of farmed sugar kelp and skinny kelp, Saccharina spp., strains from the Northwest Atlantic
Get PDF© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Umanzor, S., Li, Y., Bailey, D., Augyte, S., Huang, M., Marty-Rivera, M., Jannink, J., Yarish, C., & Lindell, S. Comparative analysis of morphometric traits of farmed sugar kelp and skinny kelp, Saccharina spp., strains from the Northwest Atlantic. Journal of the World Aquaculture Society, (2021), https://doi.org/10.1111/jwas.12783.Our team has initiated a selective breeding program for regional strains of sugar kelp, Saccharina latissima, to improve the competitiveness of kelp farming in the United States. Within our breeding program, we also include an endemic putative species, Saccharina angustissima, locally referred to as skinny kelp. We crossed uniclonal gametophyte cultures derived from 37 wild‐collected blades representing five sugar kelp strains and one skinny kelp strain to produce 104 unique crosses. Each cross was outplanted on a near‐shore research farm located in the Gulf of Maine (GOM). After the first farming season, our results indicated that sugar kelp and skinny kelp were interfertile, and produced mature and reproductively viable sporophytes. Morphological traits of individual blades varied depending on the parental contribution (sugar vs. skinny), with significant differences found in progeny blade length, width, thickness, and in stipe length and diameter. Despite these differences, wet weight and blade density per plot showed no statistical differences regardless of the cross. Given their published genetic similarity and their interfertility shown here, S. angustissima and S. latissima may not be different species, and may each contribute genetic diversity to breeding programs aimed at meeting ocean farming and market needs.Funding was provided by the U.S. Department of Energy, ARPAe MARINER project contract number DE‐AR0000915 and DE‐AR0000911, AgCore Technologies of Rhode Island, and the Massachusetts Clean Energy Center, AmplifyMass Program
Chaos-assisted tunneling and 1/ƒ^(α) spectral fluctuations in the order-chaos transition
Get PDF© 2008 The American Physical Society. This work was supported by Grants No. FIS2006-12783-C03-01 from Ministerio de Educación y Ciencia of Spain, and No. CCG07-CSIC/ESP-1962 from Comunidad de Madrid and CSIC. The author is supported by the Spanish program ‘‘Juan de la Cierva’’.It has been shown that the spectral fluctuations of different quantum systems are characterized by 1/ƒ^(α) noise, with 1 </= "alpha" </= 2, in the transition from integrability to chaos. This result is not well understood. We show that chaos-assisted tunneling gives rise to this power-law behavior. We develop a random matrix model for intermediate quantum systems, based on chaos-assisted tunneling, and we discuss under which conditions it displays 1/ƒ^(α) noise in the transition from integrability to chaos. We conclude that the variance of the elements that connect regular with chaotic states must decay with the difference of energy between them. We compare the characteristics of the transition modeled in this way with what is obtained for the Robnik billiard.Ministerio de Educación y Ciencia of SpainComunidad de MadridCSICSpanish program ‘‘Juan de la Cierva’’Depto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUEpu
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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