1,722,226 research outputs found
Regulation of Endogenous Excitatory Neurotransmitters by Isoprostanes
No full textWe have evidence that isoprostanes (IsoPs) regulate exogenously applied excitatory amino acid neurotransmitter glutamate in bovine retina, in vitro. However, the regulation of retinal endogenous glutamateby IsoPs is unknown. The objective of the present study was to investigate the effect of 8-isoprostaglandin E2 (8-isoPGE2) on endogenous levels of glutamate and its metabolite, glutamine in bovine retina, ex vivo. Freshly isolated bovine eyeballs were injected intravitreally with 8-isoPGE2 and retina and vitreous humor were isolated for measurement of amino acids using high pressure liquid chromatography. 8-isoPGE2 caused a concentration-dependent attenuation of retinal glutamate and glutamine levels. For instance, 8-isoPGE2 (1 μM and 100 μM) significantly (p0.05) on the inhibitory effects of 8-isoPGE2 (1μM-100μM) on retinal glutamate and glutamine concentrations. To determine the role of prostanoid receptors in the effects of 8-isoPGE2, eyeballs were pretreated with the prostanoid receptor antagonists SC-19220 (EP1), AH-6809 (EP2/3), AH-23848 (EP4) or SQ-29548 (TP). SC-19220 (3 μM-30 μM), AH-6809 (3 μM-30 μM) and AH-23848 (3 μM-30 μM) reversed the inhibitory effects of 8-isoPGE2 on glutamate and glutamine levels in a concentration- dependent manner. As a positive control, the EP receptor agonist, PGE2 (10 μM) inhibited glutamate and glutamine levels by 48.4% (p0.05) effects on 8-isoPGE2-induced inhibition of glutamate and glutamine levels in bovine retina. |In conclusion, 8-isoPGE2 can decrease the levels of endogenous excitatory neurotransmitter, glutamate and its metabolite glutamine in bovine retina, ex vivo by EP-receptor-dependent but not prostanoid synthesis-dependent mechanisms.xx, 178 page
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
Attention during pauses between successive saccades: task interference vs. modulation of contrast-gain
No full textPerceptual performance is better at the target of a saccade than other locations (e.g. Gersch et al., 2009). To better understand pre-saccadic attention shifts, four experiments were carried out that measured perceptual discrimination and detection across different stimulus contrasts during pauses between successive saccades. In Experiment 1, displays contained 4 outline squares (1.4° on a side) located at the corners of an imaginary square (3.4° eccentricity from the screen center). Sequences of saccades were made in a V-shaped path from one corner to another. Perceptual targets (oriented letter T’s) appeared inside each eccentric square when the eye reached the center. The orientation of a randomly-selected T was reported after scanning was completed. Orientation discrimination was poor (< 75% correct) at all test locations other than the saccadic goal, even at the highest contrast. These performance losses could be due to selective decay of visual memory (Gersch et. al., 2008). Experiment 2 used a single visual target in order to decrease the memory load. The displays contained 13 outlined squares (1.23° on a side, one in the center, 4 at the inner corners and the 8 in the outer loop), which allowed subjects to make a longer sequence of saccades. The eccentricity from the inner corners to the center was 2.5°. In each trial, an oriented Gabor appeared randomly in either the saccadic goal location or the opposite location in the inner group of squares. Perceptual reports were required either frequently (80% of trials) or infrequently (20% of trials). Although the perceptual performances was good at both locations, a small perceptual enhancement at the saccadic goal location was observed regardless whether there was external noise or how frequently a report was required. Durations of pauses between saccades were prolonged when the Gabor was detected at a location other than the saccadic goal, reflecting an attempt to improve perceptual discrimination by delaying the saccade. Experiment 3 presented two Gabors in each trial, one at the saccadic goal location and one at the opposite location, which prevented subjects from knowing the report location as soon as they detected the Gabor and adjusting their strategy in the trial. Pause durations between saccades were prolonged when a report was required frequently, showing that emphasizing a perceptual task could affect saccadic performance even when there was no location cue. Perceptual enhancement at the saccadic goal location was observed again, and this enhancement was larger when a perceptual report was required infrequently. The perceptual enhancement at the saccadic goal location still existed with a detection task, which reduced the memory load, in Experiment 4, which tried to find out whether the location difference without external noise condition is due to the attention shift or memory load. These results show that fixation pause durations were increased by attention to a non-saccadic-goal location, and that perceptual performance was better at the saccadic goal location than at non-goal location, supporting the conclusion that perception and saccades use a common attentional filter. In contrast to attention shifts controlled by cues during maintained fixation, the pre-saccadic attention shifts were found both with and without the external noise, across the whole range of the stimuli contrasts, and regardless of memory load. This shows that multiple mechanisms of visual attention must be involved in pre-saccadic attention shifts.M.S.Includes bibliographical referencesby Min Zha
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
An integrative description of Pilatobius nuominensis sp. nov. (Tardigrada: Hypsibiidae) from China
No full textSun, Xue-Ling, Zhang, Jing-Yu, Wang, Ning, Zhao, Min, Luo, Xue-Gang (2021): An integrative description of Pilatobius nuominensis sp. nov. (Tardigrada: Hypsibiidae) from China. Zootaxa 5026 (1): 59-70, DOI: https://doi.org/10.11646/zootaxa.5026.1.
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