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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.
21

Etablierung genetischer Methoden für Clavibacter michiganensis subsp. michiganensis und Charakterisierung von Mutanten mit veränderter Morphologie, Physiologie und Virulenz

Kirchner, Oliver. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2003--Bielefeld.
22

iSAT: The Integrated Satellite and Acoustic Telemetry system for tracking marine megafauna

De La Torre, Pedro R. 05 1900 (has links)
In this dissertation an innovative technology to study whale sharks, Rhincodon typus is presented. The Integrated Satellite and Acoustic Telemetry project (iSAT) combines underwater acoustic telemetry, autonomous navigation and radio frequency communications into a standalone system. The whale shark, a resident of the Saudi Arabian Red Sea, is the target of the study. The technology presented is designed to help close current gaps in the knowledge of whale shark biology; these are gaps that prohibit the design of optimal conservation strategies. Unfortunately, the various existing tracking technologies each have limitations and are unable to solve all the unanswered questions. Whale shark populations are increasingly threatened by anthropogenic activities such as targeted and indirect fishing pressure, creating an urgent need for better management practices. This dissertation addresses the current state-of-the-art of relevant technologies, including autonomous surface vehicles (ASVs), sensors for research in the ocean and remote monitoring of wild fauna (biotelemetry). iSAT contains components of all of these technologies, but the primary achievement of this dissertation is the development of iSAT’s Acoustic Tracking System (ATS). Underwater, the most efficient way of transmitting energy through long distances is sound. An electronic tag is attached to an animal and works as its acoustic identifier. iSAT’s hydrophone array detects the presence and direction of the acoustic signal generated by the tag. The expected performance, range, and capacity to tell the direction to the tag are explained and compared to the actual measured values. The first operational iSAT ATS is demonstrated. This work represents significant advancement towards a fully autonomous iSAT system. Developments on the power electronics, navigation, renewable energy harvesting, and other modules are included in this research. With the recent integration of digital acquisition systems, iSAT’s capabilities were increased to minimize its size and allow it to communicate with other acoustic systems. Future engineering works are still necessary to achieve a fully automated system, but the current developments with the ATS have immediate applications.
23

Distribution Patterns of Migratory Striped Bass in Plum Island Estuary, Massachusetts

Pautzke, Sarah M 01 January 2008 (has links) (PDF)
This is the first study to assess how the coastal migratory stock of striped bass (Morone saxatilis) uses non-natal New England estuaries during their foraging migration. Using hydroacoustic telemetry from June through October in Plum Island Estuary, Massachusetts, I examined how long coastal migratory striped bass stayed throughout the seasons, if they were equally distributed, if individual striped bass were distributed differently, and if distribution changed with season, tide, or light. Striped bass, ages 2-5 (300-480 mm), were tagged with VEMCO transmitters in the spring and summer of 2005 (N=14) and 2006 (N=46). They stayed for an average of 66 days in 2005 (SE=7.6) and 72 days in 2006 (SE=6.2). Of the fish tagged in 2005 and 2006, 60% remained for longer than 30 days. This might reflect two striped bass migration strategies: 1) transient migration, in which striped bass visit many estuaries, and 2) estuary-specific, in which they reside in a single location for the summer. The amount of time the striped bass spent in six reaches delineated within the estuary was quantified. Striped bass were not evenly distributed across these reaches. Instead, they spent the most time in the mid Plum Island Sound and lower Rowley River reaches in both years. Three different uses of PIE were observed. Some striped bass stayed briefly (5-20 d; N=24), some stayed primarily in the Rowley River (N=14), and others stayed primarily in Plum Island Sound (N=22). Striped bass use of the mid Plum Island Sound and lower Rowley River reaches remained consistently high in spring and summer, but decreased in fall, while use of the lower Plum Island Sound did not vary much. Use of other reaches varied seasonally. Tide and light were less associated with distribution, but in the summer the Rowley River use-group increased utilization of tidal creeks during the day, though not at high tide. These three use-groups identified in Plum Island Estuary may be foraging contingents that may learn how to forage in specific parts of the estuary demonstrated by over half the striped bass remaining for much of the summer and congregating in distinct areas.
24

A Horseshoe Crab (Limulus polyphemus) Demographic Study

Walls, Elizabeth Ann 19 December 2001 (has links)
We examined various aspects of horseshoe crab populations in conjunction with BioWhittaker, a biomedical company that bleeds horseshoe crabs (Limulus polyphemus) and utilizes their blood for biomedical purposes. We examined mortality rates of bled and unbled crabs by holding crabs in tanks for 2-week periods. We estimate average differential mortality between bled and unbled horseshoe crabs to be 7.5% (95% CI: 0.14% - 38.1%), significant with p<0.001. We examined the range in amounts of blood extracted from 98 male horseshoe crabs. Mean mass of blood extracted was was 78.3 grams (95% CI: 70.5g - 86.0g) and ranged from 8.2g to 212.3g. We compared gender-, size-, and stage-class distributions of crabs caught in trawls by BioWhittaker in Chincoteague, Virginia and Ocean City, Maryland during the years 1999 - 2000. Significant differences in gender distribution (p=0.0062), size distribution (p=0.0002) and stage-class distribution (p<0.001) were seen between locations, with Chincoteague, Virginia's population comprised of smaller and younger crabs, with greater proportions of females as compared with Ocean City, Maryland. Significant differences in overall gender distributions (p=0.0109) were also seen between years 2000 and 2001, with greater proportions of females present in 2000 than in 2001. We tagged 7,500 bled, adult horseshoe crabs to gain information on horseshoe crab population dynamics. From resight reports (N=121), we examined movement patterns and found average distance traveled was 29.8 miles and maximum distance traveled was 195 miles, suggesting mixing along the Atlantic coast. We found a 1.6% recovery rate of tagged crabs and tags found detached from crabs. 11.6% of our resights consisted of tags found detached from crabs. We use information gained in our study to suggest improvements for future tagging efforts that could lead to further knowledge of horseshoe crab population dynamics. / Master of Science
25

Seed germination, kanamycin sulfate selection, and the influence of nitrogen treatments on an insertional mutant population of Fragaria vesca

Lindsay, Robert Clark 18 January 2011 (has links)
With the goal of creating faster and more efficient methods of generating unique Ac/Ds insertional mutants in a population of Fragaria vesca, various methods of seed germination, kanamycin screening, and the effects of varying nitrogen fertilization on diploid strawberry have been examined. Seed germination was improved to 42% in B5 liquid medium compared to _ on MS solid medium. Kanamycin screening during germination was most effective in liquid B5 medium as well. A readily discernable phonotypic difference between sensitive (necrotic radical) and resistant (branched roots) seedlings was observed in the B5 liquid medium and the frequency of escapes was reduced from __ on solid MS to __ in liquid B5. Although there were few phenotypic differences due to nitrogen application over the tested treatments (25-300 ppm) runner initiation was suppressed and chlorophyll was increased in the high (300 ppm) nitrogen treatment. There was limited evidence to suggest an increased rate of transposition in the high (300 ppm nitrogen) treatment level compared to those plants receiving lower levels of nitrogen. The selection efficiency and greater germination of the B5 liquid medium over MS medium would be expected to reduce the cost of screening thousands of seedlings because of the need for fewer disposables and medium transfers during the 5 week germination process. The use of B5 liquid medium, as well as treating plants with high levels of nitrogen (300 ppm), may be facilitate high throughput production of transposon tagged mutants in a population of F. vesca. / Master of Science
26

Recherche de production électrofaible supersymétrique dans des cascades de désintégration contenant un boson de Higgs avec le détecteur ATLAS au LHC / Search for electroweak production of supersymmetry in decay cascades containing a Higgs boson with the ATLAS detector at LHC

Ughetto, Michaël 07 November 2014 (has links)
Depuis le démarrage des collisions proton-proton au LHC en 2009, les expériences ATLAS et CMS ont collecté plus de 25/fb de données. Le boson de Higgs est une prédiction clé du Modèle Standard de la physique des particules et sa découverte en 2012 par les expériences ATLAS et CMS complète le Modèle Standard. Le Modèle Standard, bien qu'en excellent accord avec les observations faites auprès des collisioneurs, ne répond pas à de nombreuses questions~: la nature de la matière noire, de l'énergie noire... De plus, l'instabilité de la masse du Higgs sous l'effet des corrections radiatives semble indiquer la présence d'une nouvelle physique à haute énergie. Parmi les théories au-delà du Modèle Standard, les modèles supersymétriques restent encore aujourd'hui d'excellents candidats pour étendre le Modèle Standard. Durant cette thèse, qui s'est déroulée de 2011 à 2014, j'ai travaillé à la recherche de signaux supersymétriques au sein de l'expérience ATLAS. Tout d'abord au L2C à Montpellier, où nous avons co-développé une nouvelle version de SuSpect, un programme permettant de calculer le spectre de masse du MSSM. Au sein du groupe ATLAS du CPPM à Marseille, j'ai développé pour la collaboration ATLAS des outils d'identification des jets issus de l'hadronisation des quarks b basés sur des réseaux de neurones artificiels et des arbres de décisions. Ces outils ont permis d'améliorer la discrimination des différentes saveurs de jet pour les analyses de données d'ATLAS.J'ai ensuite utilisé les données enregistrées par ATLAS en 2012 pour poser des limites sur la production associée de charginos et neutralinos se désintégrant via un boson de Higgs et un boson W pour donner un lepton chargé, deux jets issus de quarks b et de l'énergie transverse manquante. / Since the start of proton-proton collisions at LHC in 2009, the ATLAS and CMS experiments have recorded more than 25/fb of data each. The Higgs boson is akey prediction of the Standard Model of particle physics and its discovery in 2012 by the ATLAS and CMS experiments complete the Standard Model.The Standard Model, despite its excellent agreement with experiments at colliders, doesn't answer to many questions~: the nature of dark matter, dark energy... Furthermore, the instability of the Higgs mass under the effect of radiative corrections seems to indicate the existence of new physics at high energy.Among the theories beyond the Standard Model, supersymmetric models are excellent candidates to extend the Standard Model. During this thesis, between 2011 and 2014, I worked on the search of supersymmetric signals with the ATLAS experiment.First at L2C in Montpellier, where we have co-develloped a new version of SuSpect, a program designed to compute the MSSM mass spectrum.In the ATLAS groupe at CPPM in Marseille, I developped for the ATLAS collaboration a serie of tools based on artificial neural networks and decision trees to identify jets coming from b-quark hadronization. This tools have improved the discimination between different jets flavors for data analysis in ATLAS.Then, I analyzed the data collected by ATLAS in 2012 to obtain limits on the associated production charginos and neutralinos decaying via a W and a Higgs boson, resulting in a final state containing a charged lepton, two b-jets and missing transverse momentum
27

RELATIVE ENERGY CALIBRATION OF THE TJNAF HALL-B PHOTON TAGGER AND INVESTIGATION OF LIMITATIONS OF THE PHOTON TAGGING TECHNIQUE

Gabrielyan, Marianna 01 January 2006 (has links)
In this work we report on two sets of measurements involving the Hall-B photon tagging system of the Tomas Jefferson National Accelerator Facility. The relative energy calibration of the tagging counters was performed by using the PrimEx pair spectrometer and a series of high position resolution micro-strip detectors. The photon energies were determined by forming coincidence between the tagger and the e+ e- pairs for several values of the pair spectrometer magnetic field between 0.36T to 1.9T (total of 180 fields). The second set of measurements, collected in conjunction with the Fall 2004 PrimEx run, investigated inherent limitations on the photon tagging technique. We report for the first time an experimental signature for these effects.
28

Release-recapture models for migration juvenile and adult salmon in the Columbia and Snake Rivers using PIT tag and radiotelemetry data /

Buchanan, Rebecca A. January 2005 (has links)
Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (p. 310-318).
29

ASSESSMENT OF CIRCUMFERENTIAL MYOCARDIAL FUNCTION USING RADIAL TAGGED MRI

Kim, YuJaung 08 March 2012 (has links)
No description available.
30

Hybrid models for Chinese unknown word resolution

Lu, Xiaofei 12 September 2006 (has links)
No description available.

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