1,721,040 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
No full textWe 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
Properties of GABAergic inhibition of the medial prefrontal cortex
No full textGamma-aminobutyric acid type A receptors (GABAARs) are the main inhibitory neurotransmitter receptors in the central nervous system. As such, they play a pivotal role in synchronising neuronal network activity in the brain and their dysregulation has been implicated in numerous neuropsychiatric diseases such as depression, anxiety and schizophrenia. GABAARs are ligand-gated heteropentamers and can be modulated either directly or indirectly by a number of therapeutically-relevant compounds, such as the benzodiazepines, or by endogenous neuromodulators, such as the neurotransmitters dopamine and serotonin, and by neurosteroids. While much is known about the function of GABAARs, their modulation and interaction with neuromodulators and other neurotransmitter systems are less well understood. In particular, their role in the prefrontal cortex (PFC), a brain area strongly involved in motivation and planning, which is often negatively affected in neuropsychiatric disease, remains to be elucidated. The aims of this research project were to characterise synaptic and tonic inhibition in the PFC, explore dopaminergic and neurosteroid modulation of GABA inhibition and to examine effects on neuronal excitability. We focused on α2 subunit-containing GABAARs because of their role in anxiety and preferred subcellular localisation at the axon initial segment (AIS), an area that is critical for regulating neuronal spike output. Contrary to previous findings, we could not detect an effect of dopamine D4 receptor activation on GABA inhibition. However, using a mouse model expressing neurosteroid-insensitive GABAAR α2 subunits, we found evidence for a significant differential involvement of this subunit and neurosteroid modulation in GABAergic synaptic inhibition between various layers of the PFC. We discovered that alterations in phasic GABA-mediated inhibition had no significant effects on pyramidal cell excitability, whilst increasing tonic inhibition reduced cell firing. Overall, this study demonstrates that tonic GABA inhibition has a more important role to play in regulating cortical network function than previously thought
Structural and functional studies of a chimeric GABA-A receptor
No full textGABA-A receptors are ligand-gated ion channels principally responsible for inhibitory neurotransmission in the mammalian CNS. GABA binding initiates a series of conformational changes causing the receptor to transition from inactive (shut/closed) to active (open) ion channel states; and during prolonged agonist exposure, to a desensitized (closed) state. Critical to the fine-tuning of inhibitory responses in vivo is the allosteric modulation of GABA-A receptors by an array of compounds, many of which impart their effect through binding within the receptor’s transmembrane domain. Beyond the importance of GABA-mediated inhibition in maintaining nervous system function, GABA-A receptors are established therapeutic targets for psychiatric and neurodevelopmental disorders. Despite this, an understanding of the structure of these receptors at atomic resolution is crucially lacking; particularly with regards to the structural elements underpinning channel gating and allosteric modulation. Therefore, GABA-A receptor ion channels were subjected to atomic-resolution structural analyses using chimeric receptors, in addition to comparative studies with bacterial ion channel homologues. A functional receptor was formed from chimeras between the extracellular domain of the prokaryotic ion channel GLIC and the transmembrane domain of GABA-A receptor α1 subunits. These receptors exhibited GABA-A receptor-like properties with respect to their response to brain neurosteroids. The amenability of this receptor to high-level expression and purification was assessed. The baculovirus-insect cell expression system was identified as an appropriate system for generating receptor of sufficient quantity and purity to generate diffracting protein crystals. Additional studies of GABA-A receptor modulators at the bacterial homologs GLIC and ELIC identified previously unreported effects prompting further structural investigation using X-ray crystallography, cryo-electron microscopy and native mass spectrometry. In conclusion, these studies reveal a new system for atomic structural resolution investigation of GABA-A receptor subunits, likely to be applicable to other receptors. These receptors are potentially powerful tools for understanding the mechanism of GABA-A receptor allosteric modulation
Receptor for activated C kinase-1 facilitates protein kinase C-dependent phosphorylation and functional modulation of GABA(A) receptors with the activation of G-protein-coupled receptors
No full textGABA(A) receptors are the principal sites of fast synaptic inhibition in the brain. These receptors are hetero-pentamers that can be assembled from a number of subunit classes: alpha(1-6), beta(1-3), gamma(1-3), delta(1), epsilon, theta, and pi, but the majority of receptor subtypes is believed, however, to be composed of alpha, beta, and gamma2 subunits. A major mechanism for modulating GABA(A) receptor function occurs via the phosphorylation of residues within the intracellular domains of receptor subunits by a range of serine/ threonine and tyrosine kinases. However, how protein kinases are targeted to these receptors to facilitate functional modulation remains unknown. Here we demonstrate that the receptor for activated C kinase (RACK-1) and protein kinase C (PKC) bind to distinct sites on GABA(A) receptor beta subunits. Although RACK-1 is not essential for PKC binding to GABAA receptor beta subunits, it enhances the phosphorylation of serine 409, a residue critical for the phospho-dependent modulation of GABA(A) receptor function in the beta1 subunit by anchored PKC. Furthermore, RACK-1 also enhances GABA(A) receptor functional modulation in neurons by a PKC-dependent signaling pathway with the activation of muscarinic acetylcholine receptors (mAChRs). This PKC-dependent modulation of neuronal GABAA receptors was mirrored by an increase in the phosphorylation of GABA(A) receptor beta subunits with the activation of mAChRs.Our results suggest a central role for RACK-1 in potentiating PKC-dependent phosphorylation and functional modulation of GABA(A) receptors. Therefore, RACK-1 will enhance functional cross talk between GABA(A) receptors and G-protein-coupled receptors and therefore may have profound effects on neuronal excitability
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