1,720,968 research outputs found
The Ribbon Synapse Between Type I Spiral Ganglion Neurons and Inner Hair Cells
No full textThis chapter provides an overview of the first auditory synapses, in the cochlea where sound is encoded. We review insights into the development, structure, and function of the excitatory ribbon-type synapses between presynaptic inner hair cells and postsynaps on the type I spiral ganglion neurons. They convey all information about sound timing and intensity to the brain, via action potentials in the auditory nerve. Recordings from individual type I spiral ganglion neurons in vivo demonstrate remarkable diversity between neurons in their sound-response properties. Although much has been learned about the representation of acoustic information in the auditory nerve, relatively little is known about the synaptic mechanisms underlying diversity of encoding. The response properties of SGN determined by properties of SGN may be largely determined by the details of the 1:1 connection between each inner hair cell presynaptic active zone and its postsynaptic type I spiral ganglion neuron. This chapter covers (1) synaptogenesis as inner hair cells mature from pattern generators to sound receivers, (2) presynaptic mechanisms governing exocytosis, (3) synaptic transmission to the type 1 spiral ganglion neuron and subsequent action potential generation, and (4) how pre- and postsynaptic heterogeneities may contribute to the diversity of spiral ganglion neuron response properties that enable hearing over a broad range of sound pressure levels. Presynaptic stimulus-secretion coupling appears to operate in a nanodomain regime and the postsynaptic action potential generator is tightly coupled to synaptic input. Thus, opening of a single presynaptic Ca2+ channel may be sufficient to trigger a postsynaptic action potential
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
Non-invasive Delivery to the Inner Ear: Investigating Blood-labyrinth Barrier Opening using MRI-guided Focused Ultrasound Combined with Microbubbles
No full textNon-invasive therapeutic delivery to the inner ear remains challenging due to the anatomical complexity,its location within the dense temporal bone, and the presence of the blood-labyrinth barrier (BLB). Here,
I investigated the safety and feasibility of using magnetic resonance imaging-guided focused ultrasound
(MRIgFUS) combined with intravenously administered microbubbles to enhance the BLB permeability and
to deliver an adeno-associated virus serotype 9 (AAV9) expressing the green fluorescent protein (GFP) to
the inner ear. AAV9-GFP, microbubbles, and MRI contrast agents were delivered intravenously in rats with
simultaneous FUS exposure, and hearing function was assessed using auditory brainstem response
measurements. My data shows increased BLB permeability post-FUS+MB exposure, as indicated by
gadolinium contrast enhancement and AAV9 transduction in treated inner ears relative to controls with
no effects on auditory function. Taken together, my data supports the feasibility of MRIgFUS towards
clinical development for non-invasive delivery of various therapeutics to treat inner ear disorders.M.Sc.2023-06-29 00:00:0
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
Modulation of Wnt and Notch Signalling Pathways for Sensory Hair Cell Regeneration in the Mammalian Auditory Organ
No full textI investigated the temporal pattern and underlying mechanisms of the transient regenerative response to canonical Wnt activation in the neonatal mouse cochlea. Ectopic Wnt activation in vitro in typically quiescent embryonic day (E) 13.5 and postnatal day (P) 0 cochleae promoted prosensory and supporting cell proliferation, respectively; however, this effect was no longer observed at P5. This age-dependent decline in proliferative capacity occurred despite similar levels of β-catenin accumulation in cochleae following transient exposure to the Wnt activator at all three developmental stages, suggesting that barriers to Wnt-mediated regeneration lie downstream of β-catenin stabilization and might be related to a lack of key transcription factors or limited access to downstream target genes. Furthermore, maintaining Wnt activation in early neonatal stages promoted changes in the expression of specific Wnt and Notch pathway genes and extended the window for hair cell induction in response to Notch signalling inhibition.M.Sc.2020-11-15 00:00:0
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