1,720,961 research outputs found
Germline Cyst Formation and Development in Zebrafish
Get PDFIn developing pre-natal mice, germline cysts are clusters or packages of cells consisting of individual oocytes. They are formed after the primordial germ cells move to the ovary during embryogenesis. The primordial germ cells divide, but do not completely separate. The cells within the cysts are linked by intercellular bridges, which end up breaking down leading to the formation of primordial follicles. The primordial follicles are oocytes surrounded by somatic cells called granulosa cells. Only one third of the original oocytes survive cyst breakdown and become the eggs that will be used by the mouse for her reproduction. This developmental process is conserved in many organisms including Drosophila and humans. Infertility is a disorder that affects 330 million women in the United States alone. This striking statistic has led to much research on oocyte development. The developmental of cysts and cyst breakdown are vital to reproductive success as infertility arises when this process is hindered. Many factors can inhibit cyst breakdown, such as fetal exposure to estrogenic compounds found in the environment. By studying model organisms we hope to elucidate the mechanisms of cyst formation and regulation and bring this knowledge to the human scale. Cyst formation has already been well studied in fruit flies and in mice. My research will focus on oocyte development specifically cyst formation in zebrafish and how it compares to that of mice and fruit flies. Germline cysts have not been well studied in zebrafish so this research is relatively uncharted territory. To date there is some evidence to suggest the existence of germline cysts in other teleosts (bony fishes) such as the Medaka. By using the knowledge of what is known about cyst formation in Drosophila and mice, as well as literature on oogenesis in a wide range of organisms, I have conducted research to identify germline cysts in zebrafish. Zebrafish were sacrificed at different ages: from two weeks to adult, and their ovaries were stained with oocyte specific antibodies as well as antibodies that have been shown to mark intercellular bridges in Drosophila and mice. The ovary tissues were then imaged using confocal microscopy. My findings show preliminary data that supports the existence of germline cysts in zebrafish
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
Identifying, Characterizing, and Exploring the Profiles of Ribosomal RNA Fragments (rRFs) and Their Implications for Personalized Medicine Contexts
No full textPersonalized medicine is a way to treat and monitor a patient based not only their symptoms but also on the unique factors that contribute to their disease. With the advent of new technologies like Next Generation Sequencing, scientists have explored many of these factors, including noncoding RNAs, a type of genetic material that does not make proteins. Short noncoding RNAs like miRNA, miRNA isoforms, and tRNA-derived fragments are one type of material under active investigation. These RNAs have been shown to be important, playing regulatory roles in diseases and fluctuating based on personal attributes such as population of origin, sex, disease status, etc. Through computational and experimental approaches, this thesis aims to explore a recently-emerged short RNA class called ribosomal RNA fragments (rRFs). To identify and characterize rRFs, we developed a computational analysis pipeline, which for the first time systematically maps, identifies, and characterizes all the rRFs present in a human cell type (Lymphoblastoid Cell Line). We observed both universal and population-specific profiles of rRFs in cells. In an effort to uncover the role that rRFs play in cells, we developed a new method called Fraction-seq. The method separates, sequences, analyzes, models, and validates the short RNA from model cell lines of Triple Negative Breast Cancer (BT-20, MDA-MB-231, and MDA-MB468) into its cell compartments (nucleus, cytoplasm, mitochondria, and mitoplast). We found that rRFs, in addition to isomiRs and tRFs, exhibit dynamic localization profiles that are cell-line-specific. Taken together, this work supports rRFs acting as important players in health and disease contexts, especially when it comes to personalized medicine. The knowledge gained from this study provides a springboard for future work directed at identifying rRF biogenesis and function in the cell. In addition, the context-specific features of rRFs align with those of isomiRs and tRFs and can be used as important biomarkers for disease and potential therapeutics
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
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