1,721,383 research outputs found
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
Variations 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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Chronic stress induces activity, synaptic and transcriptional remodeling of the lateral habenula associated with deficits in motivated behaviors
Full text linkChronic stress is a major risk factor for the development of depression. In recent years, the lateral habenula (LHb) has emerged as a potential key structure in depression. LHb is connected with dopaminergic neurons in the ventral tegmental area (VTA) and serotoninergic neurons in the dorsal raphe nucleus (DR), and changes in these monoaminergic systems have been associated with depression-related behaviors. In my dissertation, I demonstrate that chronic stress-induced hyperactivity in LHb neurons projecting to VTA is associated with increased passive coping but not anxiety or anhedonia. Moreover, LHb→VTA neurons in mice with increased passive coping show increased burst and tonic firing as well as synaptic adaptations in excitatory inputs from the entopeduncular nucleus (EP). In vivo manipulations of EP→LHb or LHb→VTA neurons also selectively alter passive coping and effort-related motivation. Conversely, dorsal raphe (DR)-projecting LHb neurons do not show chronic stress-induced hyperactivity and are targeted indirectly by the EP. Using single-cell transcriptomics I reveal a set of genes that can collectively serve as biomarkers to identify mice with increased passive coping phenotype and differentiate LHb→VTA from LHb→DR neurons. Together, I provide a set of biological markers at the level of genes, synapses, cells and circuits that define a distinctive chronic stress-induced behavioral phenotype
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Inputs to midbrain dopamine neurons control nicotine aversion and motivated feeding
No full textThe activity of ventral tegmental area dopamine neurons (VTA DA) in the midbrain is central to the generation of motivated behaviors, such as feeding. Drugs of abuse, such as nicotine, are capable of “hijacking” this system by artificially driving VTA DA activity to promote reinforcement, but high doses of nicotine are aversive. Many brain regions send inputs to the VTA to influence DA activity, including those independently sensitive to food or nicotine consumption, which can strongly modulate behavior. In Chapter 2, I describe how a high dose of nicotine can promote aversive behavior in mice by employing in vivo fiber photometry with nicotine and/or nicotinic acetylcholine receptor (nAChr) blockers, a computational model of nAChr activation and sensitization, and optogenetic behavior experiments. I reveal that a high dose of nicotine inhibits DA release in the canonical reward pathway, from VTA DA neurons that project to the lateral shell of the nucleus accumbens (NAcLat). Using a computational model as a guide, I show that the inhibition of NAcLat dopamine release arises from an alpha7 nAChr sensitive laterodorsal tegmentum (LDT) GABA projection to the VTA, which is activated by aversive nicotine. Finally, by suppressing activity of LDT GABA during delivery of an aversive dose of nicotine, I show diminished inhibition of NAcLat dopamine and that conditioned place aversion is prevented. In Chapter 3, I introduce the role of NAcLat inputs to the VTA which are sensitive to and can impose hedonic feeding behavior. Using in vivo and ex vivo electrophysiology, RNA sequencing, imaging with a novel peptide fluorescent sensor, and optogenetic behavior experiments, I reveal that NAcLat→VTA releases neurotensin and requires neurotensin receptor availability to drive hedonic feeding behavior. I find that in a high fat diet-induced obese mouse model, neurotensin release is diminished, which correlates with reduced hedonic feeding behavior and an inability to increase VTA DA firing and hedonic feeding behavior from optogenetic activation. Finally, by specifically overexpressing neurotensin in the NAcLat→VTA pathway in mice on high-fat diet (HFD), I will show that mice gain less weight and exhibit more locomotion and hedonic feeding behavior compared to control mice on HFD, partially ameliorating the negative impact of the obesogenic food environment. Together, these results highlight the power of inputs to VTA DA neurons to modify responses to nicotine and hedonic feeding, which can translate to targeted therapeutics for nicotine dependence and obesity in the future
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An inhibitory brainstem input to dopamine neurons encodes nicotine aversion
Full text linkDecades of research implicate dopamine neurons as the brain’s center for reward, which drugs of abuse “hijack” to cause addiction. Indeed, nicotine acts on nicotinic acetylcholine receptors on ventral tegmental area dopamine neurons to increase dopamine release and consequently, feelings of reward and pleasure. However, recent research has revealed that a subset of dopamine neurons signal aversion, contrary to the popular belief that dopamine neurons solely mediate reward. At high doses, nicotine is aversive, and understanding how this dose-dependent switch in valence may lead to novel insights for treating nicotine addiction. To dissect the neural circuits that mediate nicotine’s aversive effects, I performed a detailed anatomical, electrophysiological, and behavioral investigation on VTA dopamine neurons, their inputs from the brainstem, and outputs to the nucleus accumbens. With in vivo calcium imaging, I demonstrate that a high dose of nicotine encodes aversion both by suppressing DA release in the canonical reward-signaling lateral mesolimbic pathway and by increasing DA release in the aversion-signaling medial pathway. I introduce an inhibitory input from the brainstem’s laterodorsal tegmentum (LDT) to the VTA that drives aversive behaviors when stimulated and is activated by an aversive dose of nicotine.Importantly, when this LDT GABA population is ablated, I observed blunted DA release patterns in the nucleus accumbens in response to aversive nicotine compared to animals with an intact LDT. Together, this work provides novel insights into the circuit mechanisms of how a high dose of nicotine may induce aversion by both increasing aversion signaling and reducing reward signaling, and that an inhibitory input from the brainstem may be an important modulator of the mesolimbic pathway in the context of nicotine response
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