1,720,964 research outputs found
Extratympanic hearing in salamanders: A comparative assessment of structural variation and terrestrial function of an atympanic ear
No full textThe auditory system mediates the detection of acoustic cues and enhances survival within complex environments by enabling organisms to construct an auditory scene of their surroundings. The tympanic middle ear evolved multiple times in all terrestrial tetrapod lineages to overcome the impedance mismatch encountered by sound pressure at the air-skin boundary, indicating its significance for aerial hearing; however, fossil evidence demonstrates that the earliest terrestrial tetrapods retained aquatically-adapted ears that were unspecialized for detecting airborne sound. How did these unspecialized ears function on land? Comparative study of extant atympanate vertebrates can provide key insights into the ancestral state and early evolution of the terrestrial tetrapod auditory system following the water-to-land transition. In this dissertation, I use atympanate salamanders as a model to investigate the structural and functional parameters underlying terrestrial hearing with unspecialized ears. In chapter one, I review the biology of the salamander auditory system. In chapter two, I characterized morphological variation of the salamander ear and found evidence for habitat-related specialization, suggesting underlying physiological variation. In chapter three, I measured auditory sensitivity to sound pressure and seismic vibration, and observed variation in sensitivity that corroborates the ecomorphological trends reported in chapter two. I assessed the contributions of hypothesized extratympanic pathways for hearing, including seismic sensitivity, cavity resonance, and bone conduction. I determined that aerial auditory sensitivity is mediated by bone conduction of sound as head vibrations that are detectable to the inner ear. In chapter four, I evaluated the sound localization capabilities of an atympanic ear. I found that bone conduction hearing in salamanders supports a figure-eight pattern of directional sensitivity to airborne sound. I contextualize my findings with other studies of tympanate and atympanate taxa and suggest that bone conduction may represent a general mechanism enabling aerial sound detection and localization in terrestrial species with atympanic ears
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Hearing in plethodontid salamanders: A review
No full textThe ability to detect airborne sound using a pressure-transducing tympanic ear has evolved several times over the course of vertebrate history, suggesting that hearing is an advantageous modality and an informative model for sensory evolution. Amphibian hearing is especially interesting because these animals must negotiate water to land transitions. Salamanders are good animal models for the study of hearing, not only because they have a wide range of ear morphologies, but also because they have evolved extratympanic pathways for sound and vibration transmission. Here we suggest that sufficient extratympanic hearing in salamanders and reduced reliance on vocal communication has relaxed selection on the auditory system and allowed for the structural diversity of the salamander ear. Unique among salamanders is the family Plethodontidae, which is not only the most speciose and ecologically diverse family of salamanders, but also possesses a highly derived ear with great inter-specific variation. In this review, we provide an overview of historical and current research on acoustic behavior, auditory anatomy, evolution, and physiology. We highlight plethodontid salamanders as an informative model for study of extratympanic function and auditory evolution
- …
