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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Devil Facial Tumour Disease : The cancer that's raising hell in Tasmania

Denbaum, P January 2014 (has links)
Since 1996 a mysterious epidemic has been sweeping across the island of Tasmania, threatening the Tasmanian devil (Sarcophilus harrisii) with extinction. The species is endemic to the island which is part of Australia and lies south of Melbourne. Being endemic to the island the devils are of particular risk of extinction. Not only has the risk of losing the world’s largest extant carnivorous marsupial aroused great interest, but also the disease itself, has received much attention from the world of oncology due to its unusual trait of being a contagious cancer.
2

The Pathology of Devil Facial Tumour Disease in Tasmanian Devils (Sarcophilus Harrisii)

thefishvet@gmail.com, Richmond Loh January 2006 (has links)
The pathology of a disfiguring and debilitating fatal disease affecting a high proportion of the wild population of Tasmanian Devils (Sarcophilus harrisii) that was discovered is described. The disease, named devil facial tumour disease (DFTD), has been identified in devils found across 60% of the Tasmanian landscape. The prevalence of this disease was extremely variable, possibly reflecting seasonal trapping success. Between 2001 and 2004, 91 DFTD cases were obtained for pathological description. Grossly, the tumours presented as large, solid, soft tissue masses usually with flattened, centrally ulcerated and exudative surfaces. They were typically multi-centric, appearing first in the oral, face or neck regions. Histologically, the tumours were composed of circumscribed to infiltrative nodular aggregates of round to spindle-shaped cells often within a pseudocapsule and divided into lobules by delicate fibrous septae. They were locally aggressive and metastasised in 65% of cases. There was minimal cytological differentiation amongst the tumour cell population under light and electron microscopy. The diagnostic values of a number of immunohistochemical stains were employed to further characterise up to 50 representative cases. They were negative for cytokeratin, epithelial membrane antigen, von Willebrand factor, desmin, glial fibrillary acid protein, CD16, CD57, CD3 and LSP1. DFTD cells were positive for vimentin, S-100, melan A, neuron specific enolase, chromogranin A and synaptophysin. In conclusion, the morphological and immunohistochemical characteristics together with the primary distribution of the neoplasms indicate that DFTD is an undifferentiated neoplasm of neuroendocrine histogenesis.
3

Telemetering Method Using Delayed Frame Time Diversity (DFTD) and Reed-Solomon Code

Koh, Kwang-Ryul, Lee, Sang-Bum, Kim, Whan-Woo 10 1900 (has links)
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / This paper proposes a telemetering method consisting of delayed frame time diversity (DFTD) as the inner code and Reed-Solomon (RS) code as the outer code. DFTD is used to transmit a real-time frame together with a time-delayed frame which was saved in the memory during a defined period. The RS code is serially concatenated with DFTD. This method was applied to the design of telemetry units that have been used for over ten flight tests. The data results of the flight test for four cases with no applied code, with DFTD only, with the RS code only, and with both DFTD and the RS code are used to compare the number of error frames. The results also show that the proposed method is very useful and applicable to telemetry applications in a communication environment with a deep fade.
4

Génomique des populations appliquée : détection de signatures de sélection au sein de populations expérimentales / Applied population genomics : detection of signatures of selection in experimental populations

Hubert, Jean-Noël 21 June 2018 (has links)
La génomique des populations rend possible la mise en évidence de traces de sélection dans le génome. Les travaux effectués considèrent en général une échelle de temps longue (~ 10³ générations). En comparaison, peu d’intérêt a été porté aux études expérimentales de court terme (~ 10 générations). De telles expériences sont pourtant susceptibles de nous renseigner sur la base génétique de caractères complexes. Nous proposons une méthode de vraisemblance basée sur un modèle de Wright-Fisher pour détecter la sélection à partir d’échantillons génétiques temporels acquis sur une période de dix générations. Nous montrons par simulation que notre méthode permet de différencier les signaux dus à la combinaison de la sélection et de la dérive génétique de ceux dus à la dérive seule. Nous montrons également par simulation qu’il est possible d’estimer le coefficient de sélection appliqué à un locus testé. De plus, nous illustrons l’intérêt de notre méthode pour la détection de marqueurs candidats à la sélection au travers de deux études génomiques sur données réelles, chez le diable de Tasmanie (Sarcophilus harrisii) et chez la truite arc-en-ciel (Oncorhynchus mykiss). Ces applications mettent en évidence des régions génomiques candidates pour des phénotypes complexes dans des contextes différents. Dans l’ensemble, nos résultats montrent qu’il est possible de détecter des gènes sujets à une sélection directionnelle intense à partir d’échantillons génétiques temporels, même si la sélection est de courte durée et si les populations examinées ont un faible effectif. / Population genomics makes it possible to detect traces of selection in the genome. Studies in this field have mainly focused on long time scale (~ 10³ generations). In comparison, short-term experimental studies (~ 10 generations) have attracted much less interest. Such experiments are, however, likely to inform us about the genetic basis of complex characters. We propose a likelihood method based on a Wright-Fisher model to detect selection from genetic temporal samples collected over ten generations. We show through simulation that our method can disentangle signals due to the combination of genetic drift and selection to those due to drift alone. We also show through simulation that it is possible to estimate the selection coefficient applied to a tested locus. In addition, we illustrate the interest of our method for the detection of candidate markers for selection through two genome scans performed on real data, in the Tasmanian devil (Sarcophilus harrisii) and in the rainbow trout (Oncorhynchus mykiss). These practical applications highlight candidate genomic regions for complex phenotypes in different contexts. Collectively, our results show the possibility of detecting genes submitted to strong directional selection from genetic time-series, even if selection is applied on a short time period and if the examined populations are small.

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