1,720,960 research outputs found
The membrane based mechanism of cell motility in cochlear outer hair cells
Full text linkThe sensitivity of the mammalian inner ear is extraordinary. At the threshold of hearing, the incoming sound produces vibrations inside the organ of Corti that are of the same order of magnitude or less than the thermal noise motion (Hudspeth, 1989, 1997; Dallos, 1996). Such sensitivity is achieved through an energy-dependent process commonly referred to as “cochlear amplifier,” i.e., the cycle-by-cycle amplification of the intracochlear vibrations that neutralizes viscous losses by positive mechanical feedback (Patuzzi and Robertson, 1988;Ashmore and Kolston, 1994; Kolston, 1995). The mechanical feedback force that makes the amplification possible is thought to be provided by cochlear outer hair cells (OHCs), a class of specialized sensorimotor cells hosted within the organ of Corti (Lim and Kalinec, 1998; Nobili et al., 1998). Direct support to the feedback hypothesis comes from the fact that OHCs posses a unique ability to change significantly their shape in response to electrical stimulation (Brownell et al., 1985; Kachar et al., 1986), a phenomenon called electromotility
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
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
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
Apoptosis in the OC-k3 immortalized cell line treated with different agents.
No full textThe aim of this study is to outline the mechanisms leading cochlear cells to die. We utilized an immortalized cell line (OC-k3 cells) derived from the organ of Corti of transgenic mice in order to perform in-depth biochemical studies with no limitations on sample size and number. We probed these cells with cisplatin and gentamicin, two drugs which display in vivo undesired ototoxic side-effects. We investigated cell viability, reactive oxygen species (ROS) production and glutathione (GSH) levels and tested the effects of different concentrations of cisplatin and gentamicin from 0 to 48 h. Results show that cells undergo a dose- and treatment-time-dependent apoptosis characterized by nuclear fragmentation, integrity of the cell membrane and mitochondria, and absence of DNA endonuclease activity. During the early part of treatment, ROS production increases and intracellular GSH decreases, probably due to the activation of protein kinase C alpha. Use of antioxidants such as N-acetylcysteine, GSH and vitamin C rescues cells from apoptosis almost completely. Overall, these data indicate that ROS generation might play a central role in inducing inner ear cell apoptosis and may have an additive role in the ageing process
Apoptosis in the OC-k3 immortalized cell line treated with different agents
No full textThe aim of this study is to outline the mechanisms leading cochlear cells to die. We utilized an immortalized cell line (OC-k3 cells) derived from the organ of Corti of transgenic mice in order to perform in-depth biochemical studies with no limitations on sample size and number. We probed these cells with cisplatin and gentamicin, two drugs which display in vivo undesired ototoxic side-effects. We investigated cell viability, reactive oxygen species (ROS) production and glutathione (GSH) levels and tested the effects of different concentrations of cisplatin and gentamicin from 0 to 48 h. Results show that cells undergo a dose-and treatment-time-dependent apoptosis characterized by nuclear fragmentation, integrity of the cell membrane and mitochondria, and absence of DNA endonuclease activity. During the early part of treatment, ROS production increases and intracellular GSH decreases, probably due to the activation of protein kinase Ca. Use of antioxidants such as acetylcysteine, GSH and vitamin C rescues cells from apoptosis almost completely. Overall, these data indicate that ROS generation might play a central role in inducing inner ear cell apoptosis and may have an additive role in the ageing process. © 2001, Informa UK Ltd All rights reserved: reproduction in whole or part not permitted
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