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Effect of cumulus cells and β-mercaptoethanol supplement during in vitro maturation on bovine oocyte competency / Nor Azlina Abd. Aziz
Get PDFThe oocyte source of livestock animals in eastern tropical region was relatively scarce and of unknown history, with the low-quality oocytes outnumbered the good quality. Hence, there was a need to develop more objective criteria or indicators for oocyte selection and modification of the microenvironment to improve the outcome of bovine in vitro embryo production. The objective of the study was to investigate the effects of: I) different groups of bovine oocytes according to the compactness of cumulus cells and II) β-mercaptoethanol (BME) supplement (50, 100, 150 and 200 μM) during in vitro maturation (IVM), on a) early apoptosis; b) intracellular GSH contents; c) oocyte maturation rate, and d) cleavage and subsequent embryo development rates after in vitro fertilisation (IVF). Bovine oocytes were retrieved from local slaughterhouses and classified into three groups, namely, Groups A (compact and dense cumulus cells), B (compact but less dense cumulus cells) and C (thin or little remnant of cumulus cells); and subsequently cultured in vitro in CO2 (5%) in air at 38.5ºC in humidified atmosphere. Early apoptosis in oocytes before and after maturation was assessed using Annexin-V staining and GSH contents using GSH assay. Maturation rate, i.e. resumption to metaphase II was evaluated using Giemsa staining. Embryo development was assessed for 9 days after IVF. Analysis of Variance, Duncan’s Multiple Range Tests and Independent T-test were used to analyse the data. The findings of Experiment I: cumulus cells influenced early apoptosis rates and GSH contents before and after in vitro maturation of bovine oocytes. In vitro maturation increased rates of early apoptosis and intracellular GSH was synthesised during maturation only in Group A oocytes. The compactness of cumulus cell layers exerted no effect on the bovine oocyte maturation rate after IVM. Cumulus cells promoted early embryo development up to 16-cell stage. In Experiment II, BME supplement during IVM increased GSH synthesis and early apoptosis in oocytes with less compact cumulus cells (Groups B and C) contradictory to Group A oocytes. In a nutshell, supplementation of BME in IVM medium did not exert any effect on oocyte developmental competency of good quality oocytes, except the addition of 50 μM BME increased maturation rate of Group A oocytes. The supplementation of BME above concentration 100 μM appeared to be detrimental to early embryo development. Group A oocytes, considered as good quality oocytes, with compact and dense cumulus cells, displayed a particular characteristic compared with Groups B and C. β-mercaptoethanol supplement during IVM played a role in promoting some factors in oocytes with less cumulus cells (Groups B and C). It is recommended that a specific in vitro embryo production protocols and procedures be established for the different bovine oocyte groups
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
Faktor yang mempengaruhi pasaran wang di Malaysia serta kesannya ke atas dasar kewangan / Azlina Abd. Aziz.
Get PDFPenulis jemputan: perjalanan PhD saya / Prof. Madya Dr. Nur Azlina Abd Aziz
Get PDFSetiap orang mempunyai alasan yang tersendiri kenapa ingin menyambung pengajian ke peringkat Doktor Falsafah (PhD). Sebahagian orang membuat PhD kerana ingin mendalami ilmu, manakala sebahagian yang lain membuat PhD untuk meningkatkan keupayaan akademik sebagai pensyarah. Saya membuat Phd atas sebab ingin mencabar diri sendiri serta menguji kemampuan saya. Mencari tajuk kajian adalah cabaran pertama bagi saya. Saya telah menghubungi seorang sahabat yang merupakan seorang profesor di salah sebuah universiti tempatan di utara tanahair. Beliau adalah seorang yang aktif membuat penyelidikan. Kami telah berbincang dan beliau telah mencadangkan beberapa tajuk yang sesuai untuk kajian Phd saya. Saya telah membuat penyelidikan dalam tajuk-tajuk yang dicadangkan. Walau apa cara sekalipun kita mendapat tajuk kajian PhD, apa yang paling penting ialah kita mesti mempunyai minat yang mendalam terhadap penyelidikan yang akan kita terokai. Ini untuk memastikan kita mampu bertabah dengan cabaran yang akan dihadapi sepanjang tempoh pengajian. Cabaran utama bermula setelah pembentangan cadangan kajian kepada panel yang dilantik, kerana selepas itu kajian penyelidikan akan bermula. Beberapa cubaan dan dugaan yang perlu dihadapi, satu demi satu
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