1,721,126 research outputs found
The mitochondrial DNA makeup of Romanians: a forensic mtDNA control region database and phylogenetic characterization
No full textResolving the most common mtDNA control region haplotype by massively parallel sequencing: a pilot study in an Italian population sample.
No full textThe high mutation rate of mitochondrial (mt)DNA, its lack of recombination, its high abundance in the cell
and its greater resistance to environmental stress make the analyses of this molecule the most promising
choice in forensic genetics when nuclear markers fail to give reliable results. The control region (CR) shows
the highest variability and is therefore routinely typed in forensic studies. Coding region data are currently
used almost exclusively for a phylogenetic assignment of mtDNA haplotypes and in population genetic
studies. The extended analysis of the mitochondrial genome covering also the coding region is however
also useful in forensic applications, e.g. to further differentiate identical CR haplotypes.
The most frequent western Eurasian mtDNA CR haplotype 16519C-263G-315.1C (with respect to the
rCRS) has been observed in various sub-haplogroups of haplogroup R0 (Brandstätter et al., 2008). In the
current study 29 samples that displayed this haplotype were selected from a larger Italian population study
(Boattini et al., 2013) and sequenced for their coding region by massively parallel sequencing as previously
described (Parson et al., 2013).
The obtained complete mtGenome haplotypes were assigned to their established sub-haplogroups and
interpreted with respect to their phylogenetic and geographic background. This study clearly demonstrates
the benefit of full mtGenomes to increase the resolution of mtDNA sequencing in forensic genetics
Helena, the hidden beauty: Resolving the most common West Eurasian mtDNA control region haplotype by massively parallel sequencing an Italian population sample
Full text linkThe analysis of mitochondrial (mt)DNA is a powerful tool in forensic genetics when nuclear markers fail
to give results or maternal relatedness is investigated. The mtDNA control region (CR) contains highly
condensed variation and is therefore routinely typed. Some samples exhibit an identical haplotype in
this restricted range. Thus, they convey only weak evidence in forensic queries and limited phylogenetic
information. However, a CR match does not imply that also the mtDNA coding regions are identical or
samples belong to the same phylogenetic lineage. This is especially the case for the most frequent West
Eurasian CR haplotype 263G 315.1C 16519C, which is observed in various clades within haplogroup H
and occurs at a frequency of 3–4% in many European populations.
In this study, we investigated the power of massively parallel complete mtGenome sequencing in
29 Italian samples displaying the most common West Eurasian CR haplotype – and found an unexpected
high diversity. Twenty-eight different haplotypes falling into 19 described sub-clades of haplogroup H
were revealed in the samples with identical CR sequences. This study demonstrates the benefit of
complete mtGenome sequencing for forensic applications to enforce maximum discrimination, more
comprehensive heteroplasmy detection, as well as highest phylogenetic resolution
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
Optimizing forensic trace DNA analysis under consideration of mitochondrial DNA and massively parallel sequencing
No full textThe analysis of micro traces is a central topic of forensic casework, presenting an ongoing challenge. Advances in reagents and methodologies have enabled the utilization of even minute amounts of trace material for short tandem repeat (STR) typing. Current research is dedicated to exploring sample collection techniques at various levels and developing customized workflows for improved analysis. This thesis contributed to the optimization of several steps within this process.
The collection of touch DNA from porous material such as fabric usually involves taping with an adhesive foil. In an attempt to avoid mixture generation and masking of minor components in STR typing, labor-intensive single particle collection is often conducted. Staining with trypan blue highly facilitates specimen visibility, thus reducing screening time. As the success rate of single cell analysis remains low, enlargement of the sampling area was investigated. Swabbing 1 x 1 cm compartments of a foil emerged as an effective strategy, collecting all available biological material even from latent DNA-bearing areas. This approach increased DNA quantity and genotyping success while maintaining acceptable limits of mixture creation. Furthermore, direct lysis kits, enriching DNA concentration in small volumes, prevent DNA loss associated with purification steps in commonly employed DNA extraction kits.
In situations where STR typing is deficient, sequencing of the mitochondrial control region serves as an alternative tool. The need for separate quantification of nuclear and mitochondrial DNA (mtDNA) was circumvented by the development of a capillary electrophoresis (CE)-mediated assay that also included markers for assessment of length heteroplasmies (LHPs). Autosomal and Y-chromosomal markers were simultaneously targeted with mtDNA degradation markers and fragments spanning common sections of LHPs. The number of STR alleles indicates successful genotyping with a commercial kit, while the presence or absence of mtDNA markers determines the sequencing approach (maxi, midi, mini, micro) and reveals the dominant LHP variant. This approach reduced consumption of sample extract and minimizes additional sequencing reactions needed to overcome sequence overlay at heterogeneous homopolymeric stretches.
Finally, the potential of massively parallel sequencing for micro trace analysis was explored. Micro traces, often containing degraded DNA, benefit from a larger panel size allowing simultaneous amplification of shorter fragments in a single run as sample extract can be spared. Results from a large set of mock samples exhibited higher concordance to reference genotypes than CE-mediated STR typing, particularly in the amplification of long CE-amplicons. Consequently, a higher number of samples fulfilled requirements for a potential database entry. In addition, the obtained sequence information enhanced the identification of artefacts like stutters, mediated discrimination, and facilitated mixture deconvolution
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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