1,721,204 research outputs found
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
Current Approaches in Spatial Genetics
No full textSpatial and landscape genetics have been recently undergone rapid advancement, although their theoretical development can be dated back to the origin of theoretical population genetics. The extent at which the spatial distribution of a population influences the short- and long-term population dynamics can be investigated by the application of several genetic and statistical approaches. In the present chapter, we offer a perspective on the different aims in spatial and landscape genetic researches and the tools to achieve them, reviewing some of the most important software that have been implemented to date
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
Assessing Evolutionary Potential in Tree Species Through Ecology-Informed Genome Screening
No full text© 2017. Springer International Publishing AG. Gaining insight into the ability of tree populations to evolve pest, disease, and drought resistance is of major importance with regard to the conservation of adaptive tree genetic resource variation under global change. However, the longevity of tree species challenges accurate assessment of additive genetic variation driving trait evolution through common garden experiments and pedigree-informed quantitative genetic analyses. Here, we argue that recent developments in landscape and population genomics pave the way for molecular marker-based analysis of evolutionary potential as a more time and cost-efficient alternative. Focusing on phenotype- or ecology-informed molecular markers increases the per-marker contribution to the genetic variation underpinning phenotypic trait evolution. Considering that most tree species lack a reference genome, landscape genomic analysis of anonymous markers can be used in concert with in situ and ex situ phenotypic monitoring of tree populations to quantify tree adaptive potential. Global forest restoration efforts and strategies to conserve tree genetic resources are likely to benefit considerably from marker-based insights in the spatial distribution of tree adaptive genetic diversity.status: Publishe
Splitting or lumping? A conservation dilemma exemplified by the critically endangered Dama Gazelle (Nanger dama)
No full textManagers of threatened species often face the dilemma of whether to keep populations separate to conserve local adaptations and minimize the risk of outbreeding, or whether to manage populations jointly to reduce loss of genetic diversity and minimise inbreeding. In this study we examine genetic relatedness and diversity in three of the five last remaining wild populations of dama gazelle and a number of captive populations, using mtDNA control region and cytochrome b data. Despite the sampled populations belonging to the three putative subspecies, which are delineated according to phenotypes and geographical location, we find limited evidence for phylogeographical structure within the data and no genetic support for the putative subspecies. In the light of these data we discuss the relevance of inbreeding depression, outbreeding depression, adaptive variation, genetic drift, and phenotypic variation to the conservation of the dama gazelle and make some recommendations for its future conservation management. The genetic data suggest that the best conservation approach is to view the dama gazelle as a single species without subspecific divisions
Land-Bridge Calibration of Molecular Clocks and the Post-Glacial Colonization of Scandinavia by the Eurasian Field Vole Microtus agrestis
Get PDFPhylogeography interprets molecular genetic variation in a spatial and temporal context. Molecular clocks are frequently used to calibrate phylogeographic analyses, however there is mounting evidence that molecular rates decay over the relevant timescales. It is therefore essential that an appropriate rate is determined, consistent with the temporal scale of the specific analysis. This can be achieved by using temporally spaced data such as ancient DNA or by relating the divergence of lineages directly to contemporaneous external events of known time. Here we calibrate a Eurasian field vole ( Microtus agrestis) mitochondrial genealogy from the well-established series of post-glacial geophysical changes that led to the formation of the Baltic Sea and the separation of the Scandinavian peninsula from the central European mainland. The field vole exhibits the common phylogeographic pattern of Scandinavian colonization from both the north and the south, however the southernmost of the two relevant lineages appears to have originated in situ on the Scandinavian peninsula, or possibly in the adjacent island of Zealand, around the close of the Younger Dryas. The mitochondrial substitution rate and the timescale for the genealogy are closely consistent with those obtained with a previous calibration, based on the separation of the British Isles from mainland Europe. However the result here is arguably more certain, given the level of confidence that can be placed in one of the central assumptions of the calibration, that field voles could not survive the last glaciation of the southern part of the Scandinavian peninsula. Furthermore, the similarity between the molecular clock rate estimated here and those obtained by sampling heterochronous (ancient) DNA ( including that of a congeneric species) suggest that there is little disparity between the measured genetic divergence and the population divergence that is implicit in our land-bridge calibration.Funding Agencies|National Science Centre, Poland [N N304 058340]; European Union [245737]</p
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