1,720,976 research outputs found
In Brown Norway rats, MPP+ is accumulated in the nigrostriatal dopaminergic terminals but it is not neurotoxic: a model of natural resistance to MPTP toxicity
No full textThe muscarinic agonist, bethanechol, enhances GABA-induced inhibition of Purkinje cells in the cerebellar cortex.
No full textAbstract
An important function of cholinergic projections to the cerebellar cortex may be to modulate the effects of classical afferent inputs to the cerebellar cortex. This hypothesis is supported by the recent observation that cholinergic agonists act at muscarinic receptors in the cerebellar cortex to facilitate Purkinje cell responses to glutamate, the excitatory neurotransmitter of parallel fibers [Brain Res., 617 (1993) 28-36]. Since Purkinje cell excitability is influenced by inhibitory input from basket and stellate cells as well as by excitatory input from granule cells and climbing fibers, the present study investigated whether muscarinic agonists could also modify the Purkinje cell responses to GABA, the putative inhibitory transmitter of basket and stellate neurons. In anesthetized ratrs, microiontophoretic application of bethanechol produced a long-lasting enhancement of GABA-evoked inhibition of firing of Purkinje cells in the cerebellar vermis (22/25 cells) regardless of whether bethanechol increased, decreased or failed to alter the basal firing rate of the cell. The muscarinic antagonist scopolamine prevented the bethanechol-induced increase in the GABA response. It appears, therefore, that cholinergic activation of muscarinic receptors enhances not only the excitatory but also the inhibitory component of cerebellar cortex circuitry. Further experiments are required to investigate whether this combination of effects may potentiate the signal processing capabilities of the cerebellar cortex
IN BROWN-NORWAY RATS, MPP(+) IS ACCUMULATED IN THE NIGROSTRIATAL DOPAMINERGIC TERMINALS BUT IT IS NOT NEUROTOXIC - A MODEL OF NATURAL-RESISTANCE TO MPTP TOXICITY
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Retrieval of biogeophysical parameters from bistatic observations of land at L-band: a theoretical study
No full textVariations on the Author
Full text link“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
Full text linkWe 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
Modelling L band backscattering of wheat in Argentinean Pampas and its application to soil moisture retrieval
No full textIn this paper a data base of L band backscattering simulations, based on the application of a discrete scattering model and detailed ground truth collected over Argentinean wheat fields, is tested. The simulations are directly compared against backscattering measurements collected over single fields. Then the scattering model is used to tune a semi empirical and manageable model function. Finally this function, jointly with a multi-temporal algorithm, is used for soil moisture retrieval and results are tested against an independent set of measurements. The site used for training and validation is located in the Pampas region, which will be continuously monitored in the framework of the SAOCOM (SAtélite Argentino de Observación COn Microondas) programme. In general, both the direct model and the retrieval algorithm produce consistent results. However, variation in the azimuth angle of observation produces appreciable effects, and some discrepancies are observed for radar observations collected just after a rainfall. These issues deserve further investigation with a larger amount of experimental data
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