1,720,956 research outputs found
Genetic diversity of Egyptian populations of the African Common Toad (Sclerophrys regularis, Reuss 1833)
No full textVolume: 13Start Page: 104End Page: 11
Nucleotide sequences of mitochondrial cytochrome b gene for phylogeny of some species of Rodentia
Full text linkOrder Rodentia contains approximately half of all living mammalian species. Most of the living species diversity within rodents is within five monophyletic radiations: Hystricognathi, Sciuridae, Geomyoidea, Dipodidae, and Muroidea. The samples collected across different areas of Egypt were analyzed by means of mitochondrial cytochrome b gene sequence analysis to ascertain the true taxonomic status between the studied species. For phylogenetic analysis, the cytochrome b sequences from this study were combined with previously published data. This study reveals that all species were divided into two main clades, the first for the Gerbillinae taxon and the second for the other studied genera in the molecular phylogenetic trees and demonstrates that Gerbillus species form a sister group with Dipodillus species. The phylogenetic relationships specified for the murine genera. Clustering was obtained between Mus and Rattus as well as in all Gerbillinae species. This study provides the first insight into the genetic diversity of some rodents in Egypt.
A New Species of Mullet Chelon caeruleum (Family: Mugilidae) with Description of its Genetic Relationship to Some Mugilids
Full text linkChelon caeruleum sp. nov. is described as a new species of Chelon encountered in the Rashid coastal region of the Mediterranean Sea, Egypt. With this finding, the new species is the sixth member of the genus Chelon. Chelon caeruleum sp. nov. is distinguished from its congeners by the following characters: colouration of body is dark bluish grey dorsally and the sides are blue; head length 20.5 to 21.6% SL; head width 13 to 13.5% SL; pre-first dorsal fin length 50% SL; eye diameter 4.6 to 5.2% SL; postorbital length 10.7 to 11.1% SL; unbranched pyloric caeca are 2 short and 4 long; a pair of long (one longer than the other), spine-like neural postzygapophyse on the second vertebra. DNA of Chelon caeruleum sp. nov. and five mullet species (Mugil cephalus, Liza carinata, Liza ramada, Liza aurata, and Chelon labrosus) was extracted then amplified using polymerase chain reaction (PCR) and sequenced. The mtDNA cytochrome oxidase subunit I sequence analysis confirmed that Chelon caeruleum sp. nov. is distinct from other congeners of Chelon and it is a different species of Chelon which is new to science
Detection of Genetic Relationship in the Tree of Life of Some Quail Through Molecular Markers Analyses
No full textABSTRACT Quail is an important and interesting group of galliform birds. The Common quail (Coturnix coturnix); the Japanese quail (Coturnix japonica); the Panda quail (Coturnix japonica); the Dotted white quail (Coturnix japonica) and the Bobwhite quail (Colinus virginianus) were used in this study. PCR-RFLP and SDS-proteins were performed to reveal the genetic characterization and genetic relationship of the studied quails. Analysis of fragments generated by digestion of PCR product with restriction enzyme NlaIII recorded highly polymorphic restriction profiles. There is a wide intraspecific COI, SEMA3E and TLX genes variability among the studied quails. Protein bands varied from10 to 18 between quails with minimum number of bands were in the Dotted white quail (10 bands) and the maximum were in the Japanese quail (18 bands) as measured by SDS-polyacrylamide gel electrophoresis. The Dotted white quail revealed the lowest similarity to the Bobwhite with a coefficient of 0.18 while The similarity coefficients between the Common quail and each one of the other quails were 0.67, 0.62, 0.45 and 0.42 for the Japanese, Panda, Dotted white and the Bobwhite quails, respectively. The results indicate that, PCR-RFLP and protein analyses are good techniques to evaluate genetic characterization and genetic relationship of these quails
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
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