1,720,958 research outputs found
Bio-inspired crossover and a model of neuronal reprogramming
Get PDFBio-inspired crossover:Natural genomes are affected by various kinds of mutations, manifesting as variations in the genome. This includes modifications to individual base pairs (single nucleotide polymorphism, SNP), but also short insertions and deletions (indels), and variations in the position (translocations) or multiplicity (copy number variations) of genetic sequences. While SNPs are historically the most studied, the other, structural variations are now known to affect a large fraction of the human genome, and can result in clinically relevant expressions in the phenotype. In biology, structural variations are also known to affect evolutionary dynamics of a population. For example, most genes originate through duplication, followed by divergent evolution of the two copies. However, in computer programs simulating evolution, structural variations are rarely included. Their absence makes it difficult to study the evolutionary consequences of translocation and copy number variation in simulated models. Including them may also have positive consequences for bio-inspired computation such as genetic algorithms. In this dissertation, a theoretical framework with algorithmic implementations is presented for sexual reproduction between linear genomes structures with structural variation, including permutations, and DNA-like strings.A model of neuronal reprogramming:In multicellular organisms, cells typically follow a hierarchical progression from embryonal stem cells to increasingly specialised cell types. However, by manipulating the expression of key genes, it is possible to reverse this specialisation, or convert directly between terminal cell types. This technology has been applied to convert human skin cells to neurons, with promising applications in disease modelling and regenerative medicine. Understanding the gene regulation network (GRN) governing this transition is crucial for improving the efficiency of this conversion in the future. In this dissertation, we integrated known interactions described in the literature into a holistic GRN model. We measured the activity of genes that are known to play pivotal roles during a reprogramming process, and compared these data to our modelling system. We found that the reprogramming process could be accurately modelled. The interaction between two genes, PTB and nPTB, played a different role from its usual interpretation in the literature, acting as a negative feedback loop
Bio-inspired crossover and a model of neuronal reprogramming [Elektronisk resurs]
No full textBio-inspired crossover: Natural genomes are affected by various kinds of mutations, manifesting as variations in the genome. This includes modifications to individual base pairs (single nucleotide polymorphism, SNP), but also short insertions and deletions (indels), and variations in the position (translocations) or multiplicity (copy number variations) of genetic sequences. While SNPs are historically the most studied, the other, structural variations are now known to affect a large fraction of the human genome, and can result in clinically relevant expressions in the phenotype. In biology, structural variations are also known to affect evolutionary dynamics of a population. For example, most genes originate through duplication, followed by divergent evolution of the two copies. However, in computer programs simulating evolution, structural variations are rarely included. Their absence makes it difficult to study the evolutionary consequences of translocation and copy number variation in simulated models. Including them may also have positive consequences for bio-inspired computation such as genetic algorithms. In this dissertation, a theoretical framework with algorithmic implementations is presented for sexual reproduction between linear genomes structures with structural variation, including permutations, and DNA-like strings. A model of neuronal reprogramming: In multicellular organisms, cells typically follow a hierarchical progression from embryonal stem cells to increasingly specialised cell types. However, by manipulating the expression of key genes, it is possible to reverse this specialisation, or convert directly between terminal cell types. This technology has been applied to convert human skin cells to neurons, with promising applications in disease modelling and regenerative medicine. Understanding the gene regulation network (GRN) governing this transition is crucial for improving the efficiency of this conversion in the future. In this dissertation, we integrated known interactions describedin the literature into a holistic GRN model. We measured the activity of genes that are known to play pivotal roles during a reprogramming process, and compared these data to our modelling system. We found that the reprogramming process could be accurately modelled. The interaction between two genes, PTB and nPTB, played a different role from its usual interpretation in the literature, acting as a negative feedback loop
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
Perfect edge-transmitting recombination of permutations
No full textCrossover is the process of recombining the genetic features of two parents. For many applications where crossover is applied to permutations, relevant genetic features are pairs of adjacent elements, also called edges in the permutation order. Recombination of edges without errors is thought to be an NP-hard problem, typically approximated by heuristics that either introduce new edges or are only able to produce a small variety of offspring. Here, we derive an algorithm for crossover of permutations that achieves perfect transmission of edges and produces a uniform sampling of all possible offspring, in quadratic average computation time. The algorithm and its derivation reveal a link between cycle crossover (CX) and edge assembly crossover (EAX), offering a new perspective on these well-established algorithms. We also describe a modification of the algorithm that generates the mathematically optimal offspring for the asymmetric travelling salesman problem
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
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