1,720,986 research outputs found
Voltage-Clamp Analysis and Computer Simulation of a Novel Cesium-Resistant A-Current in Guinea Pig Laterodorsal Tegmental Neurons
No full text Sanchez, Russell M., Alisa Surkis, and Christopher S. Leonard. Voltage-clamp analysis and computer simulation of a novel cesium-resistant A-current in guinea pig laterodorsal tegmental neurons. J. Neurophysiol. 79: 3111–3126, 1998. Increased firing of cholinergic neurons of the laterodorsal tegmental nucleus (LDT) plays a critical role in generating the behavioral states of arousal and rapid eye movement sleep. The majority of these neurons exhibit a prominent transient potassium current ( I A) that shapes firing but the properties of which have not been examined in detail. Although I A has been reported to be blocked by intracellular cesium, the I A in LDT neurons appeared resistant to intracellular cesium. The present study compared the properties of this cesium-resistant current to those typically ascribed to I A. Whole cell recordings were obtained from LDT neurons ( n = 67) in brain slices with potassium- or cesium-containing pipette solutions. A transient current was observed in cells dialyzed with each solution (KGluc-85%; CsGluc-79%). However, in cesium-dialyzed neurons, the transient current was inward at test potentials negative to about −35 mV. Extracellular 4-aminopyridine (4-AP; 2–5 mM) blocked both inward and outward current, suggesting the inward current was reversed I A rather than an unmasked transient calcium current as previously suggested. This conclusion was supported by increasing [K]o from 5 to 15 mM, which shifted the reversal potential positively for both inward and outward current (+17.89 ± 0.41 mV; mean ± SE). Moreover, recovery from inactivation was rapid (τ = 15.5 ± 4 ms; n = 4), as reported for I A, and both inward and outward transient current persisted in calcium-free solution [0 calcium/4 mM ethylene glycol-bis(β-aminoethyl ether)- N,N,N′,N′-tetraacetic acid; n = 4] and during cadmium-blockade of calcium currents ( n = 3). Finally, the transient current was blocked by intracellular 4-AP indicating that adequate dialysis occurred during the recordings. Thus the Cs-resistant current is a subthreshold I A. We also estimated the voltage-dependence of activation ( V 1/2 = −45.8 ± 2 mV, k = 5.21 ± 0.62 mV, n = 6) and inactivation ( V 1/2 = −59.0 ± 2.38 mV, k = −5.4 ± 0.49 mV, n = 3) of this current. Computer simulations using a morphologically accurate model cell indicated that except for the extreme case of only distal A-channels and a high intracellular resistivity, our parameter estimates were good approximations. In conclusion, guinea pig LDT neurons express subthreshold A-channels that are resistant to intracellular cesium ions. This suggests that these channels differ fundamentally in their ion permeation mechanism from those previously studied. It remains to be determined if Cs+ resistance is common among brain A-channels or if this property is conferred by known A-channel subunits. </jats:p
Data Sharing and Management Snafu in 3 Short Acts Video
No full textNYU Health Sciences Library Video Shared during the hackathon : A data management horror story by Karen Hanson, Alisa Surkis and Karen Yacobucci. This is what shouldn't happen when a researcher makes a data sharing request! Topics include storage, documentation, and file formats. Note: this was previously 3 separate videos. The original videos are still available, but for this one we made some edits and compiled to one video
Data Sharing and Management Snafu in 3 Short Acts Video
No full textNYU Health Sciences Library Video Shared during the hackathon : A data management horror story by Karen Hanson, Alisa Surkis and Karen Yacobucci. This is what shouldn't happen when a researcher makes a data sharing request! Topics include storage, documentation, and file formats. Note: this was previously 3 separate videos. The original videos are still available, but for this one we made some edits and compiled to one video
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
The relative citation ratio: what is it and why should medical librarians care?
Full text linkBibliometrics is becoming increasingly prominent in the world of medical libraries. The number of presentations related to research impact at the Medical Library Association (MLA) annual meeting has been increasing in past years. Medical centers have been using institutional dashboards to track clinical performance for over a decade, and more recently, these institutional dashboards have included measures of academic performance. This commentary reviews current practices and considers the role for a newer metric, the relative citation ratio
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