1,722,229 research outputs found
Transient rhythmic network activity in the somatosensory cortex evoked by distributed input in vitro
No full textThe initiation and maintenance of physiological and pathophysiological oscillatory activity depends on the synaptic interactions within neuronal networks. We studied the mechanisms underlying evoked transient network oscillation in acute slices of the adolescent rat somatosensory cortex and modeled its underpinning mechanisms. Oscillations were evoked by brief spatially distributed noisy extracellular stimulation, delivered via bipolar electrodes. Evoked transient network oscillation was detected with multi-neuron patch-clamp recordings under different pharmacological conditions. The observed oscillations are in the frequency range of 2-5 Hz and consist of 4-12 mV large, 40-150 ms wide compound synaptic events with rare overlying action potentials. This evoked transient network oscillation is only weakly expressed in the somatosensory cortex and requires increased [K+]o of 6.25 mM and decreased [Ca2+]o of 1.5 mM and [Mg2+]o of 0.5 mM. A peak in the cross-correlation among membrane potential in layers II/III, IV and V neurons reflects the underlying network-driven basis of the evoked transient network oscillation. The initiation of the evoked transient network oscillation is accompanied by an increased [K+]o and can be prevented by the K+ channel blocker quinidine. In addition, a shift of the chloride reversal potential takes place during stimulation, resulting in a depolarizing type A GABA (GABAA) receptor response. Blockade of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-proprionate (AMPA), N-methyl-D-aspartate (NMDA), or GABA(A) receptors as well as gap junctions prevents evoked transient network oscillation while a reduction of AMPA or GABA(A) receptor desensitization increases its duration and amplitude. The apparent reversal potential of -27 mV of the evoked transient network oscillation, its pharmacological profile, as well as the modeling results suggest a mixed contribution of glutamatergic, excitatory GABAergic, and gap junctional conductances in initiation and maintenance of this oscillatory activity. With these properties, evoked transient network oscillation resembles epileptic afterdischarges more than any other form of physiological or pathophysiological neocortical oscillatory activity
Juvenile boars and testicular micro RNA
No full textData represent micro RNA concentrations in testicular tissue at pivotal points in Sertoli cell proliferation. Three in vivo pig models that stimulate Sertoli cell proliferation in vivo were evaluated. These three models were hemicastration on day 8, daily treatment with the androgen receptor blocker, flutamide, and weekly treatment with the aromatase inhibitor, letrozole. Time points were chosen to provide data on levels near the beginning of a demonstrable treatment effect Treatments Sertoli cell response and tissue and circulating hormone levels are described more completely in:
Berger, T., Conley, A., 2014. Reduced endogenous estrogen and hemicastration interact synergistically to increase porcine Sertoli cell proliferation. Biol Reprod 90, 114;
Berger, T., Sidhu, P., Tang, S., Kucera, H., 2019. Are testicular cortisol and WISP2 involved in estrogen-regulated Sertoli cell proliferation? Anim Reprod Sci 207, 44-51; and
Legacki, E., Conley, A.J., Nitta-Oda, B.J., Berger, T., 2015. Porcine Sertoli cell proliferation after androgen receptor inactivation. Biol Reprod 92, 93.
In each model, one littermate was treated and the remaining littermate served as the control. Testicular tissue was flash-frozen on dry ice. The miRNA was analyzed using miRCURY assay kits from Qiagen (Germantown, MD,USA) after isolation of mRNA using Qiazol cDNA synthesis as described in the kits.
The micro RNA data are expressed as the delta Ct for the specific micro RNA relative to the reference micro RNA, miR-103 for each littermate. Samples within the four different data sets were potentially analyzed on different days with different lots of primer, which limits the value of comparisons between datasets
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
Juvenile boars and testicular micro RNA
No full textData represent micro RNA concentrations in testicular tissue at pivotal points in Sertoli cell proliferation. Three in vivo pig models that stimulate Sertoli cell proliferation in vivo were evaluated. These three models were hemicastration on day 8, daily treatment with the androgen receptor blocker, flutamide, and weekly treatment with the aromatase inhibitor, letrozole. Time points were chosen to provide data on levels near the beginning of a demonstrable treatment effect Treatments Sertoli cell response and tissue and circulating hormone levels are described more completely in:
Berger, T., Conley, A., 2014. Reduced endogenous estrogen and hemicastration interact synergistically to increase porcine Sertoli cell proliferation. Biol Reprod 90, 114;
Berger, T., Sidhu, P., Tang, S., Kucera, H., 2019. Are testicular cortisol and WISP2 involved in estrogen-regulated Sertoli cell proliferation? Anim Reprod Sci 207, 44-51; and
Legacki, E., Conley, A.J., Nitta-Oda, B.J., Berger, T., 2015. Porcine Sertoli cell proliferation after androgen receptor inactivation. Biol Reprod 92, 93.
In each model, one littermate was treated and the remaining littermate served as the control. Testicular tissue was flash-frozen on dry ice. The miRNA was analyzed using miRCURY assay kits from Qiagen (Germantown, MD,USA) after isolation of mRNA using Qiazol cDNA synthesis as described in the kits.
The micro RNA data are expressed as the delta Ct for the specific micro RNA relative to the reference micro RNA, miR-103 for each littermate. Samples within the four different data sets were potentially analyzed on different days with different lots of primer, which limits the value of comparisons between datasets
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
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