1,721,068 research outputs found
Role of spontaneous and sensory orexin network dynamics in rapid locomotion initiation
Full text linkISSN:1873-5118ISSN:0301-0082ISSN:0301-008
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
Orexin/Hypocretin and Organizing Principles for a Diversity of Wake-Promoting Neurons in the Brain.
No full textAn enigmatic feature of behavioural state control is the rich diversity of wake-promoting neural systems. This diversity has been rationalized as 'robustness via redundancy', wherein wakefulness control is not critically dependent on one type of neuron or molecule. Studies of the brain orexin/hypocretin system challenge this view by demonstrating that wakefulness control fails upon loss of this neurotransmitter system. Since orexin neurons signal arousal need, and excite other wake-promoting neurons, their actions illuminate nonredundant principles of arousal control. Here, we suggest such principles by reviewing the orexin system from a collective viewpoint of biology, physics and engineering. Orexin peptides excite other arousal-promoting neurons (noradrenaline, histamine, serotonin, acetylcholine neurons), either by activating mixed-cation conductances or by inhibiting potassium conductances. Ohm's law predicts that these opposite conductance changes will produce opposite effects on sensitivity of neuronal excitability to current inputs, thus enabling orexin to differentially control input-output gain of its target networks. Orexin neurons also produce other transmitters, including glutamate. When orexin cells fire, glutamate-mediated downstream excitation displays temporal decay, but orexin-mediated excitation escalates, as if orexin transmission enabled arousal controllers to compute a time integral of arousal need. Since the anatomical and functional architecture of the orexin system contains negative feedback loops (e.g. orexin ➔ histamine ➔ noradrenaline/serotonin-orexin), such computations may stabilize wakefulness via integral feedback, a basic engineering strategy for set point control in uncertain environments. Such dynamic behavioural control requires several distinct wake-promoting modules, which perform nonredundant transformations of arousal signals and are connected in feedback loops
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
Recommended from our members
Neuronal cicuits and reinforcement mechanisms underlying feeding behaviour
Full text linkAnimal survival depends on the brain’s ability to detect the energetic state of the body and to alter behaviour in order to maintain homeostasis. Current research in the control of food consumption stresses the importance of identifying and establishing the specific roles of homeostatic neurons, which sense the body’s energetic state and elicit complex and flexible food seeking behaviours. Recent developments in optogenetics, molecular genetics, and anatomical techniques have made these investigations possible at the resolution of specific cell types and circuits. These neurons are of particular interest because they serve as key entry points to the identification of downstream circuits and reinforcement mechanisms that control feeding behaviour. This dissertation probes the role of two kinds of homeostatic neurons— agouti-related peptide (AGRP) in the arcuate nucleus (ARC) and leptin receptor (LepRb) neurons in the lateral hypothalamic area (LHA)—in the control of food intake. First, I examined the role of LepRb neurons in the LHA in feeding. Results from electrophysiological studies indicate that these neurons consist of a subpopulation of homeostatic sensing LHA γ-aminobutyric acid (GABA) expressing neurons. In addition to their response to leptin, these neurons are capable of modulating their activity in response to changes in glucose levels, further substantiating their role as homeostatic sensing neurons. Behavioural studies using optogenetic activation of these neurons show that their elevated activity is capable of reducing body weight, although their role in modulating feeding remains unclear. Second, I investigated the reinforcement mechanisms employed by AGRP neurons to elicit voracious food consumption and increased willingness to work for food. Conditioned place avoidance studies under optogenetic activation of AGRP neurons reveal that their increased activity has negative valence and is avoided. In addition, imposition of elevated AGRP neuron activity in an operant task reduced instrumental food seeking with particular sensitivity under high effort requirements. Taken together, these results suggest that AGRP neurons employ a negative reinforcement teaching signal to direct action selection during food seeking and consumption. Third, I systematically analyzed the contribution of specific AGRP neuron projection subpopulations in AGRP neuron mediated evoked-feeding behaviour. Optogenetic activation studies of AGRP neuron axons in downstream projection regions indicate that several, but not all, subpopulations are capable of independently evoke food consumption. This work reveals a parallel and redundant functional circuit organization for AGRP neurons in the control of food intake. Interestingly, all AGRP neuron subpopulations examined displayed similar modulation by states of energy deficit and signals of starvation, despite their apparent divergence in function. As a whole, this dissertation extends our understanding of the role of homeostatic neurons in food consumption and uncovers previously unappreciated functional organization and reinforcement mechanisms employed by neuronal circuits that control feeding behaviour
- …
