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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

Teeth and Other Tales

Handwerger, Alexandra M 06 March 2012 (has links)
TEETH AND OTHER TALES is a novella and a collection of short stories that explore the blurry lines between illusion and reality. Teeth, the novella, is narrated backward in time, chronicling the life of Lucy from the age of sixty-five back to seventeen. After years of surviving an oppressive marriage, Lucy escapes her husband, but in doing so abandons her three children. In order to rationalize her decisions, Lucy uses selective memory to create her own reality to the extent that she comes to believe her own delusions. The four short stories in the collection feature protagonists who create their own personal myths and struggle to protect their distorted truths, with mixed results. These struggles between the “real,” as conventionally defined, and personal fictions are complicated by elements of magical realism and surrealism. The stories were influenced by the short fiction of Nikolai Gogol, Franz Kafka and Haruki Murakami.
2

A mixed methods study of adherence to prophylactic treatment among young people with haemophilia

Van Os, Sandra Barbara January 2016 (has links)
Introduction: Haemophilia is an inherited bleeding disorder caused by a deficiency in one of the coagulation or blood clotting factors in the blood. When injured someone with haemophilia does not bleed more intensely than a person without haemophilia, but they tend to bleed for a much longer time. For people affected by severe haemophilia, the deficiency in coagulation factor can cause spontaneous internal bleeding in joints and muscles, as well as intracranial bleeding, and bleeding in soft tissues (e.g. nosebleeds or bleeding gums). The most common form is Haemophilia A which is caused by a deficiency in factor VIII. Haemophilia B is caused by a deficiency of factor IX and tends to be less severe than haemophilia A. Haemophilia is treated by replacing the deficient coagulation factor in the blood through intravenous injections of factor concentrate. Treatment can be on-demand, where medication is used to treat a bleeding episode; or preventative, where factor replacement treatment is used to increase the concentration of coagulation factor in the blood to prevent bleeding. Most young people with severe haemophilia in the UK follow a preventative treatment regimen (prophylactic treatment or prophylaxis). Patients with severe haemophilia A usually take 3 or 4 injections per week on alternate days, whereas patients with severe haemophilia B usually take 2 or 3 injections per week. There is good evidence that prophylaxis reduces bleeds and joint damage, whilst also improving quality of life. Therefore it is imperative for future health and functioning that young people with haemophilia (YPH) follow the prophylactic regimen they agreed with their haemophilia team. However, reported adherence levels among YPH vary widely (17 - 93%). Additionally, drivers of (non)adherence among YPH specifically have not been evidenced. Aims: The overall aim of the research described in this thesis was to gain a better understanding of the extent to which YPH adhere to their prophylactic treatment, and better understand what drives their (non-)adherence. The aims of the quantitative questionnaire study were to measure levels of adherence among YPH, and to assess whether psychosocial factors that have been shown to be associated with adherence among young people with other chronic illnesses, such as self-efficacy and social support, are also associated with adherence among YPH. Based on previous research on adherence and social cognitive models of illness, it was hypothesised that: - there would be differences between adolescents and young adults in relation to psychosocial correlates of adherence. - higher perceptions of pain and impact of pain would be associated with better adherence (De Moerloose, Urbancik, Van Den Berg, & Richards, 2008; Treil, Rice, & Leissinger, 2007). - higher perceptions of chronicity, consequences and treatment control would be predictive of higher adherence (Chilcot et al., 2010; Horne & Weinman, 2002). - greater perception of necessity of prophylaxis would be predictive of higher adherence whereas concerns about prophylaxis would not be predictive (de Thurah, Nørgaard, Harder, & Stengaard-Pedersen, 2010; Horne et al., 2013; Horne & Weinman, 1999; Llewellyn, Miners, Lee, Harrington, & Weinman, 2003; Wileman et al., 2014). - greater negative mood would be associated with lower adherence scores (Cox & Hunt, 2015; Helgeson, Siminerio, Escobar, & Becker, 2009; Snell, Fernandes, Bujoreanu, & Garcia, 2014). In addition, based on evidence that lower adherence results in worse disease outcomes (Berntorp, 2009; M. J. Manco-Johnson et al., 2007), it was anticipated that non-adherence to prophylaxis would be associated with higher numbers of bleeds and hospital visits. The aims of the qualitative interview studies with YPH, parents of YPH, and haemophilia healthcare professionals were to examine perceptions and experiences in relation to prophylaxis and how they make sense of these experiences. It was anticipated that this would provide evidence to gain a better understanding of the complexities surrounding prophylaxis and of the barriers and facilitators to adherence among YPH.
3

Design, implementation and first results of the Neutrino Triggered Target of Opportunity Program with the IceCube neutrino telescope

Franke, Robert 08 June 2015 (has links)
Die Kerne aktiver Galaxien (AGNs) und einige galaktische Objekte wie z.B. Supernovaüberreste gelten als vielversprechende Kandidaten für die Quellen der hochenergetischen kosmischen Strahlung. Der Nachweis der Emission von hochenergetischen Neutrinos von diesen Objekten wäre ein starker Hinweis für die Beschleunigung von Protonen oder schwereren Kernen. Bisher wurde jedoch keine Punktquelle hochenergetischer Neutrinos identifiziert. Durch die Beobachtung aktiver galaktischer Kerne mit gamma-Strahlung im TeV-Bereich ist bekannt, dass die Emission von AGNs zeitlich extrem variabel ist. Modelle sagen vorher, dass auch die Neutrinoemission diese Variabilität aufweist. Um im Falle der Detektion zeitabhängiger Neutrinoemission von AGNs möglichst viel über den Emissionsmechanismus zu lernen, ist es entscheidend, Daten verschiedener Energiebereiche und Botenteilchen (Neutrinos und Photonen) zur Verfügung zu haben. Durch das beschränkte Gesichtsfeld und den geringen Duty-Cycle der TeV-gamma Instrumente, können diese jedoch nicht alle potentiell interessanten Quellen lückenlos überwachen. Diese Arbeit beschreibt die Entwicklung und die ersten Resultate eines Systems, dass Daten des Neutrinoteleskops IceCube direkt am Südpol analysiert, um Alarme an die TeV-Teleskope MAGIC und VERITAS zu senden, falls eine erhöhte Neutrinoemission eines überwachten Objekts detektiert wird. Der Katalog überwachter Objekte, der im ersten Jahr dieses Programms aktiv war, umfasste 109 Objekte in der nördlichen Himmelshemisphäre (delta>0). Das System befindet sich seit März 2012 kontinuierlich Betrieb und hat von Mai 2012 bis Mai 2013 fünf Alarme generiert. Ein Alarm am 9.November 2012 resultierte in einer Folgebeobachtung durch die VERITAS-Teleskope. Es wurde kein signifikanter gamma-Fluss im TeV-Bereich detektiert. Weiterhin werden Verbesserungen der IceCube Online-Analysemethode beschrieben, die die Sensitivität des vorgestellten Programms in naher Zukunft weiter verbessern werden. / Active Galactiv Nuclei (AGN) and galactic objects like e.g. supernova remnants are promising candidates for the sources of the high-energy cosmic rays. The detection of high-energy neutrinos from these objects would be a strong hint for the acceleration of protons or heavier nuclei. No source of high-energy astrophysical neutrinos has been identified up to now. From the observation of AGN with TeV gamma-rays it is known that their emission is highly variable. Models predict that also the neutrino emission should show that variability. If time-dependent neutrino emission would be detected it would be desirable to have simultaneous data for different messengers (neutrinos and photons) and energy ranges, to learn as much as possible about the emission mechanism. However, due to the small field of view and the low duty cycle of the TeV gamma instruments, not all interesting sources can be continuously monitored. This work describes the development and the first results of a system, that analyses data of the IceCube neutrino telescope online at the South Pole, in order to send alerts to the TeV telescopes MAGIC and VERITAS in case a statistically interesting cluster of neutrinos is detected from an monitored source. This program is termed the Neutrino Triggered Target of Opportunity program (NToO). The catalog of sources monitored during the first year of operation contained 109 objects in the northern sky (delta>0). The system has been continuously operated since March 2012 and has sent five alerts between May 2012 and May 2013. One alarm issued on 9 November 2012 resulted in a follow-up observation by the VERITAS telescopes. No significant TeV-gamma flux has been detected. Improvements to the IceCube online analysis are described that will further improve the sensitivity of the NToO in the near future.
4

A Search for Extended Gamma-Ray Emission from the Galactic Center with VERITAS

Kelley-Hoskins, Nathan 07 May 2020 (has links)
Dunkle Materie bindet etwa 24 % der gesamten Energie im Universum. Bis heute ist jedoch dessen Ursprung nicht bekannt. Untersuchungen von Galaxien und kosmologischen Messungen deuten auf Dunkle Materie hin. Ein Kandidat für Dunkle Materie ist das sogenannte Weakly Interactive Massive Particle (WIMP), welches nur der Schwerkraft und der schwachen Wechselwirkung unterliegt. Eines dieser supersymmetrischen Teilchen ist das Neutralino. Das Ziel dieser Arbeit ist es, nach Dunkler Materie in dieser Form zu suchen. Aufgrund seiner Nähe sowie der hohen Dichte an Dunkler Materie bietet das Zentrum unserer Galaxie besondere Möglichkeiten zur Suche nach diesen Teilchen. Es wird vermutet, dass Neutralinos miteinander wechselwirken, dabei in Teilchen des Standard Modells zerfallen und so Photonen mit hohen Energien entstehen. Die Suche nach hochenergetischen Gammastrahlen in der Nähe des Galaktischen Zentrums kann folglich das Rätsel der Dunklen Materie lösen. Das Gammastrahlenobservatorium VERITAS hat das Galaktische Zentrum für etwa 108 Stunden beobachtet. Diese Daten wurden mittels einer unbinned Likelihood-Analyse auf die Existenz von Dunkler Materie untersucht. Da VERITAS das Galaktische Zentrum bei geringer Elevation beobachtet, können nur Gammastrahlen in einem Energiebereich zwischen 4 und 70 TeV detektiert werden. Die Analysemethode modelliert sowohl die räumliche Verteilung der Dunklen Materie als auch das Gammastrahlenspektrum. Der Beitrag der Gammastrahlen, welcher nicht von Dunkler Materie erzeugt wird, ist mittels einer punktförmigen Quelle modelliert. Zum Schluss wird der Untergrund mit realen Daten außerhalb des Galaktischen Zentrums abgeschätzt. Im Energiebereich zwischen 4 und 100 TeV wurden keine Signale der Dunklen Materie gefunden. Obere Grenzwerte für den Wechselwirkungsquerschnitt der WIMPs ergeben ⟨σv⟩ < (6.6 − 7.6) × 10−25 cm^3 oberhalb von 70 TeV in einem 95-prozentigen Erwartungsintervall. / Dark matter accounts for 24% of the universe’s energy, but the form in which it is stored is currently unknown. Understanding what form this matter takes is one of the major unsolved mysteries of modern physics. Much evidence exists for dark matter in the measurements of galaxies, dwarf galaxies, galaxy clusters, and cosmological measurements. One theory posits dark matter is a new undiscovered particle that only interacts via gravity and the weak force, called a weakly interacting massive particle (WIMP). One WIMP candidate is a supersymmetric particle called a neutralino. The objective of this thesis is to search for these dark matter particles, and attempt to measure their mass and cross section. Dark matter particles appear to concentrate in most galaxy-scale gravitational wells. One region of space that is both nearby and assumed to have a high density of dark matter is the center of our own galaxy. The neutralino is expected to annihilate into Standard Model particles, which may decay into photons. Therefore, a search for gamma rays near the Galactic Center may uncover the presence of dark matter. 108 hours of VERITAS gamma-ray observations of the Galactic Center are used in an unbinned likelihood analysis to search for dark matter. The Galactic Center’s low elevation results in VERITAS observing gamma rays in the 4–70 TeV energy range. The analysis used in this thesis consists of modeling the halo of dark matter at the Galactic Center, as well as the spectrum of gamma rays produced when two WIMPs annihilate. A point source is added to model the non-dark-matter gamma-ray emission detected from the Galactic Center. Background models are constructed from data of separate off-Galactic-Center observations. No dark matter signal is found in the 4–100 TeV mass range. Upper limits on the WIMP’s velocity-averaged cross section have been calculated, which above 70 TeV result in new limits of ⟨σv⟩ < (6.6 − 7.6) × 10−25 cm3 at the 95% confidence level.
5

Modifying and Measuring the Stiffness of a Regenerative Cardiac Scaffold In Vitro

Filipe, Daniel V 01 December 2010 (has links)
"The stiffness of scaffolds used in surgical ventricular restoration may play an important role in the degree to which they facilitate regeneration of functional cardiac tissue. The stiffness of the scaffold influences the phenotype of cells which are present in it as well as their ability to deform the scaffold. The goal of this study was to evaluate in vitro methods to characterize and alter the stiffness of new scaffold materials. Membrane inflation testing, an in vitro mechanical testing method, was evaluated in this study because of its ease of use and the similar mode of loading which it shares with scaffolds implanted in vivo. The structural stiffness of two scaffold materials, urinary bladder matrix and Dacron, were determined in vivo and using membrane inflation testing. Despite higher tensions and lower area stretch ratios for scaffolds tested using membrane testing, similar changes in structural stiffness between the two materials were found for both methods (5.6 ± 3.3 fold in vivo, 5.0 ± 1.0 in vitro). This finding demonstrated that membrane inflation testing is a useful in vitro method for measuring changes in structural stiffness between scaffold materials with a level of sensitivity similar to that which is measured in vivo. Membrane inflation testing was used to assess the effectiveness of altering scaffold stiffness through exposure to various cell culture conditions. Incubation of a biological membrane in cell culture media resulted in a drastic decrease in the elastic modulus from its initial value (3.55 ± 0.52 MPa) after 2 weeks (1.79 ± 0.30 MPa), 4 weeks (1.04 ± 0.09 MPa), and 10 weeks (0.014 ± 0.01 MPa). When fibroblasts were cultured on the scaffolds for 10 weeks an increase in elastic modulus (0.134 ± 0.05 MPa) over scaffolds incubated in culture media for the same amount of time was observed. The increase in elastic modulus due to the presence of fibroblasts was accompanied by an increase in the percentage of collagen in the samples (54.1 ± 5.1 % without fibroblasts, 83.2 ± 5.1 % with fibroblasts). Contrary to expectation, addition of ascorbic acid to the media to increase production of collagen by the fibroblasts resulted in a decrease in elastic modulus (0.030 ± 0.01 MPa) compared to scaffolds cultured with fibroblasts in standard media and a decrease in the amount of enzymatically degraded collagen (40.8 ± 4.7 % without ascorbic acid, 21.1 ± 3.3 % with ascorbic acid). Regeneration of cardiac tissue after a myocardial infarction is a complicated process which is influenced by a myriad of different factors. Future studies investigating the exact role which substrate stiffness has on regeneration will be essential to the development of improved cardiac scaffolds. Characterization of the stiffness of these scaffolds by membrane inflation and manipulation through exposure to cell culture conditions are powerful approaches to facilitate future studies."
6

VERITAS observations of galactic gamma-ray sources

Tsurusaki, Kazuma 01 July 2012 (has links)
The main topic of this thesis is analysis of an unidentified Galactic TeV gamma-ray source, MGRO J1908+06, discovered by Milagro instrument in 2007. We analyzed 54 hours of observational data from the Very Energetic Radiation Imaging Telescope Array System (VERITAS), a ground-based gamma-ray observatory in southern Arizona comprised of an array of four Cherenkov Telescopes that reconstructs the energy and direction of astrophysical gamma-rays by imaging Cherenkov light emitted by energetic particles in air showers produced by the primary gamma-rays. MGRO J1908+06 is located between a supernova remnant SNR G40.5-0.5 and a young, energetic pulsar PSR J1907+0602. We studied the energy dependent morphology of the TeV emission from the source and measured the source extent and spectrum. The source extends well past the boundary of the SNR and is not correlated with strong radio continuum or molecular line emission which likely excludes an origin for the emission as solely due to the SNR. While emission in the 0.5-1.25 TeV band was centered around the pulsar, higher energy emission was observed near the supernova remnant. This morphology is opposite that observed in other pulsar wind nebulae. We proposed two models for the high energy emission located well away from the pulsar but close to the SNR: (1) shock acceleration at the shock front created by an interaction between the pulsar wind and the dense gas at the edge of the SNR or (2) molecular clouds around the SNR provides seed photons with energies higher than those from Cosmic Microwave Backgrounds for inverse Compton scattering. The former model can be tested by looking for molecular emission lines that trace shocks and by measuring the pulsar velocity. In addition, we investigated the gamma-ray emission from the nova explosion of V407 Cygni that occurred in March 2010. The Fermi-LAT observed this event in the energy range of E >100 MeV. The origins of the gamma-ray emission that the Fermi-LAT team proposed are either protons (hadronic model) or electrons (leptonic model), both of which were accelerated at the nova shock via the Fermi acceleration mechanism. We did not consider their leptonic model because no TeV gamma-ray emission is predicted. Their hadronic model can generate TeV gamma-rays with the modeled parameters. We found no evidence for TeV emission. We showed that with the flux upper limit calculated using the VERITAS data imposes constraints on the extension of the proton spectrum at high energies.
7

Modernisering av marint styr- och övervakningsskåp

Oskarsson, Daniel, Henriksson, Jan-Erik January 2003 (has links)
No description available.
8

Modernisering av marint styr- och övervakningsskåp

Oskarsson, Daniel, Henriksson, Jan-Erik January 2003 (has links)
No description available.
9

Investigating the Microquasar SS 433 and the PeVatron Candidate MGRO J1908+06 with a Novel Extended Source Analysis Method

Kleiner, Tobias Kai 10 June 2024 (has links)
Die Herkunft galaktischer sehr hochenergetischer und ultrahochenergetischer kosmischer Strahlung bleibt rätselhaft, aber Studien weisen auf zahlreiche galaktische Quellen namens PeVatrons hin, die Teilchen auf Petaelektronenvolt-Energien beschleunigen können, darunter Pulsarwindnebel, Supernovareste und Mikroquasare. Die Untersuchung der Gammastrahlung bei Giga- und Teraelektronenvolt-Energien bietet entscheidende Einblicke in ihre Eigenschaften und erweitert unser Verständnis hochenergetischer astrophysikalischer Phänomene. Diese Arbeit analysiert Daten des VERITAS-Gammastrahlenobservatoriums, bestehend aus vier 12-Meter-Tscherenkow-Teleskopen in Arizona, um ein umfassendes Verständnis von zwei galaktischen Quellen zu liefern: MGRO J1908+06, ein potenzieller PeVatron-Kandidat, und SS 433, ein Mikroquasar. MGRO J1908+06 wurde bereits in verschiedenen Wellenlängen untersucht, wobei mehrere potenzielle Ursprünge der Strahlung identifiziert wurden. Diese Arbeit führt eine umfassende Neuuntersuchung seiner ausgedehnten Gammastrahlenemissionen durch, um präzisere Abschätzungen des Gammastrahlenflusses zu liefern und frühere Ergebnisse zu aktualisieren. Die Untersuchung deutet auf einen möglichen Ursprung der Gammastrahlung sowohl aus einem Relikt eines Pulsar-Windnebels als auch aus einem neuen Pulsar-Windnebel im Feld von MGRO J1908+06 hin. Erstmals wird in den VERITAS-Daten eine signifikante Gammastrahlenemission von SS 433 festgestellt. Es werden die Gammastrahlen der Jets bei größeren Abständen und ihre Morphologie untersucht, und TeV-Spektren werden generiert. Modelle zeigen einen leptonischen Ursprung dieser Emissionen, ohne dass eine signifikante Gammastrahlenemission in der Nähe des Schwarzen Lochs oder Anzeichen für Variabilität beobachtet werden. Ausblickend präsentiert die Arbeit Untersuchungen zur Optimierung der Eigenschaften des Cherenkov-Teleskop-Array Observatoriums, mit Fokus auf die Platzierung von Illuminatoren und Abschattungseffekte zwischen Teleskopen. / The origins of galactic very-high energy and ultra-high energy cosmic rays remain elusive. Recent studies propose the existence of PeVatrons, galactic sources capable of accelerating particles to Petaelectronvolt energies, such as pulsar wind nebulae, supernova remnants, and micro-quasars. Exploring gamma-ray emission at Giga- and Teraelectronvolt energies offers crucial insights into their properties, enriching our understanding of high-energy astrophysical phenomena. This thesis focuses on analysing data from the VERITAS gamma-ray observatory, comprising four 12-meter imaging atmospheric Cherenkov telescopes in Arizona. Employing 3D maximum-likelihood analysis methods, the study aims to provide a comprehensive understanding of two extended galactic sources: MGRO J1908+06, a potential PeVatron candidate, and SS 433, a microquasar. MGRO J1908+06, though unidentified, has been scrutinized across various wavelengths, with several potential counterparts identified previously. This thesis undertakes a re-analysis of its extended gamma-ray emission, leveraging updated analysis methods and recent VERITAS observations. The improved analysis method provides a more accurate estimate of the gamma-ray flux, revising prior VERITAS flux estimates and suggesting a scenario involving both relic and new pulsar wind nebulae. Regarding SS 433, significant gamma-ray emission is detected in VERITAS data for the first time. The morphological properties of the gamma-ray emission regions seen at larger distances along the jets are examined, and their TeV spectra are constructed. Modelling supports a leptonic origin of these emissions, with no significant gamma-ray emission observed near the black hole or any indication of variability. Looking ahead, the thesis presents investigations aimed at optimizing the characteristics of the Cherenkov Telescope Array Observatory, focusing on illuminator placement and mutual shadowing effects to enhance telescope positioning within the array.
10

Management information system for Hong Kong regional office of a ship classification society.

January 1988 (has links)
Leung Tak-fai, Ho Chun-fu. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1988. / Bibliography: leaf 68.

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