1,720,988 research outputs found
Anàlisi bioinformàtica de seqüències reguladores de l'expressió gènica en eucariotes.
Get PDF[cat] El treball realitzat durant el meu doctorat ha estat dirigit a entendre millor l'organització i l'evolució de les regions de DNA que regulen la transcripció. En concret els objectius d'aquesta tesi són: (1) millorar els mètodes in silico de caracterització, representació i predicció de llocs d'unió de factors de transcripció; (2) estudiar les restriccions que actuen sobre la conservació evolutiva de les seqüències reguladores de la transcripció; (3) estudiar l'efecte de la duplicació gènica sobre l'evolució de les seqüències reguladores de la transcripció i sobre l'expressió gènica. El primer capítol, presenta el desenvolupament del programa PROMO, per predir llocs d'unió de factors de transcripció (TFBSs) en una seqüència de DNA o en un conjunt de seqüències. Per una espècie determinada o un determinat nivell taxonòmic, PROMO construeix matrius de pes a partir de seqüències de TFBSs coneguts que són utilitzades per fer la predicció. La predicció simultània sobre múltiples seqüències permet descobrir elements de regulació comuns i es pot aplicar, per exemple, per a comparar regions reguladores de gens ortòlegs o de gens que s'expressen en el mateix teixit. En el segon capítol es presenta l'estudi en que vàrem demostrar la hipòtesi de que el nombre de teixits en que un gen s'expressa està relacionat de manera significativa amb el grau de conservació de la seqüència del promotor. Mostrem que els gens housekeeping de mamífers, els que s'expressen en tots o gairebé tots els teixits, tenen una menor conservació de la seqüència del promotor que els gens que s'expressen en un subconjunt de teixits. El tercer i darrer capítol presenta un estudi sobre l'efecte de la duplicació gènica sobre l'evolució de les seqüències reguladores de la transcripció. S'han fet molts estudis sobre l'efecte de la duplicació gènica sobre la divergència de les seqüències proteiques, però poc es coneix de com aquest procés afecta l'evolució de les seqüències reguladores de l'expressió gènica. En aquest treball hem trobat que el nombre de duplicacions gèniques mostra una relació positiva amb la divergència del promotor, la taxa de substitucions no-sinònimes de la seqüència codificant i la divergència de l'expressió tissular. Per tant, la duplicació gènica no només condueix a un increment de les mutacions aminoacídiques, sinó a una acceleració de la divergència de seqüències involucrades en la regulació de l'expressió gènica.[eng] Goal of this thesis is to better understand the organization and evolution of DNA regions that regulate gene transcription. Particular aims are: (1) to improve in silico methods of characterization, representation and prediction of transcription factor binding sites; (2) to study the constraints that affect the evolutionary conservation of transcription regulatory sequences; (3) to study the effect of gene duplication on the evolution of transcription regulatory sequences and gene expression. The first chapter describes the development of PROMO, a software program to predict transcription factor binding sites (TFBSs) in DNA sequences using species-tailored positional weight matrices. Simultaneous prediction on multiple sequences can be applied to discover common regulatory elements in promoters of orthologous genes or co-expressed genes. In the study presented in the second chapter, the hypothesis that the number of tissues in which a gene is expressed is related in a significant manner to the extent of promoter sequence conservation is tested. It is shown that mammalian housekeeping genes, those expressed in all or nearly all tissues, have lower promoter sequence conservation than genes expressed in a subset of tissues. The third and final chapter presents a study about the effect of gene duplication on the evolution of transcription regulatory sequences. Many studies have been carried out on the effect of gene duplication on protein sequence divergence, but little is known of how this process affects the sequences that regulate gene expression. It is shown here that gene duplication is associated with increased protein sequence divergence, increased promoter sequence divergence, and increased tissue expression divergence. Therefore, gene duplication drives not only an increase in amino-acidic mutations but also an acceleration of divergence of DNA sequences involved in the regulation of gene expression
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
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
Neural networks for process parameter identification and assisted controller tuning for control loops
No full textThe paper introduces a method for identification and assisted controller tuning for industrial process control loops suitable for an 'in-chip' solution. The method is based on utilization of neural network technology. It employs pattern recognition and exploits the nonlinear function approximation feature of neural networks. The method has the advantage of simplicity and sufficient accuracy. It is developed for on-line usage in closed-loop operations
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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