186,480 research outputs found
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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
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
Dr. Edward P. Wimberly, ITC, July 2011
No full textThis video is a conversation with Dr. Edward P. Wimberly. Dr. Wimberly talks about his book, "No Shame in Wesley's Gospel: A Twenty-First Century Pastoral Gospel". Brad Ost, AUC Woodruff Library, is the interviewer
Author Rights and Scholarly Publishing
No full textOriginally posted at
http://blog.library.gsu.edu/2014/10/24/author-rights-and-scholarly-publishing/</p
Acute effects of 6-hydroxydopamine on dopaminergic neurons of the rat substantia nigra pars compacta in vitro
No full text6-Hydroxydopamine (6-OHDA) is a neurotoxin which has been implicated in the degeneration of dopaminergic neurons of the substantia nigra pars compacta (SNc) in Parkinson's disease (PD), and is frequently used to produce animal models of the disease. The aim of our study, conducted on midbrain slices obtained from young Wistar rats, was to determine the little known acute effects of this toxin (0.2-2.0 mM; 10-20 min exposure; 34 degrees C) on electrophysiological properties, intracellular Ca2+ levels and dendritic morphology of SNc neurons. Four experimental approaches were used: extracellular recording of firing frequency, whole-cell patch-clamping, ratiometric fura-2 imaging, and cell labeling with lucifer yellow (LY) or dextran-rhodamine. Extracellular recording revealed a concentration-dependent decrease in the tonic, pacemaker-like firing. In whole-cell recordings in voltage-clamp (V(hold) -60 mV), smaller doses (0.2-0.5 mM) induced an outward current (or cell membrane hyperpolarization in current-clamp), which could in some cells be reversed with tolbutamide (blocker of ATP-dependent K+ channels). A higher dose (1.0-2.0 mM) caused rapid reductions of cell membrane capacitance and membrane resistance. Toxin exposure gradually increased the intracellular Ca2+ level, which did not subsequently return to control. The increase in Ca2+ signal was not prevented by depletion of intracellular Ca2+ stores with thapsigargin (10 microM) or cyclopiazonic acid (30 microM), nor by removing extracellular Ca2+. Cell membrane current and Ca2+ responses were not prevented by blocking dopamine transporter (DAT). Cells loaded with LY or dextran-rhodamine showed signs of damage (cell membrane blebbing) in dendrites following toxin exposure (1 mM; 10-20 min). These results demonstrate that the oxidative and metabolic stress induced in SNc neurons by 6-OHDA results in rapid dose-dependent changes of cell membrane properties with morphological evidence of dendritic damage, as well as in disturbance of intracellular Ca2+ homeostasis
Acute action of rotenone on nigral dopaminergic neurons--involvement of reactive oxygen species and disruption of Ca2+ homeostasis
No full textAbstract
Rotenone is a toxin used to generate animal models of Parkinson’s disease; however, the mechanisms of toxicity in substantia nigra pars compacta (SNc) neurons have not been well characterized. We have investigated rotenone (0.05–1 lm) effects on SNc neurons in acute rat midbrain slices, using whole-cell patch-clamp recording combined with microfluorometry. Rotenone evoked a tolbutamide-sensitive outward current (94 ± 15 pA) associated with increases in intracellular [Ca2+] ([Ca2+]i) (73.8 ± 7.7 nm) and intracellular [Na+] (3.1 ± 0.6 mm) (all with 1 lm). The outward current was not affected by a high ATP level (10 mm) in the patch pipette but was decreased by Trolox. The [Ca2+]i rise was abolished by removing extracellular Ca2+, and attenuated by Trolox and a transient receptor potential M2 (TRPM2) channel blocker, N-(p-amylcinnamoyl) anthranilic acid. Other effects included mitochondrial
depolarization (rhodamine-123) and increased mitochondrial reactive oxygen species (ROS) production (MitoSox), which was also abolished by Trolox. A low concentration of rotenone (5 nm) that, by itself, did not evoke a [Ca2+]i rise resulted in a large (46.6 ± 25.3 nm) Ca2+ response when baseline [Ca2+]i was increased by a ‘priming’ protocol that activated voltage-gated Ca2+ channels. There was also a positive correlation between ‘naturally’ occurring variations in baseline [Ca2+]i and the rotenone-induced [Ca2+]i rise. This correlation was not seen in non-dopaminergic neurons of the substantia nigra pars reticulata (SNr). Our results show that mitochondrial ROS production is a key element in the effect of rotenone on ATP-gated K+ channels and TRPM2-like channels in SNc neurons, and demonstrate, in these neurons (but not in the SNr), a large potentiation of rotenone-induced [Ca2+]i rise by a small
increase in baseline [Ca2+]i
Mapping the Discipline of the Olympic Games An Author-Cocitation Analysis
No full textThe authors conducted an author cocitation analysis on prominent authors writing about the Olympics during the 1990s. Author cocitation is an established bibliometric technique that can be used to measure the relative similarities of topics written about by the cited authors. This enables a visual representation of the “intellectual space” of the discipline, in this case the Olympics, to be created for the period under review. So core and peripheral research areas are identified, along with their major contributors. The representation appears as a two-dimensional cluster-enhanced map. Subject expertise was then applied to the results to place labels on the generated clusters of authors and their topics
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