When astronauts travel in space, their primary health hazards are high-energy cosmic radiations from galactic cosmic rays (GCR). Most galactic cosmic rays have energies between 100 MeV and 10 GeV. For occupants inside of a space shuttle, the structural material is efficient to absorb most of the cosmic-ray energy and reduce the interior dose rate to below 1.2 mGy per day. However, the biological effects of prolonged exposure to low-dose radiation are not well understood. The purpose of this research was to examine the feasibility of constructing a low-dose irradiation facility to simulate the uniform radiation field that exists in space. In this research, we used a pre-manufactured incubator, specifically the Thermo Scientific Forma Series II Water Jacketed CO2 Incubator, to act as shielding and simulate the exterior of the space shuttle. To achieve the desired dose rate (< 1 mGy/h) inside the incubator volume, the computer code MCNPX was used to determine required source activity and distance between the shielding and source. Once the activity and distance were calculated, an experiment was carried out to confirm the simulation results. The confirmation used survey meters and thermoluminescence dosimeters (TLDs) to map the radiation field within the incubator.

Severe influenza virus infection, including human infection with highly pathogenic H5N1 viruses is characterised by massive pulmonary inflammation, immunopathology and excessive cytokine production, a process in which macrophages may play a vital role. The aim of this project was to investigate the hypothesis that inhibition of inflammatory responses from infected macrophages, using either alternatively activated bone marrow derived macrophages (BMDMf), or IFNg receptor deficient (IFNgR-/-) mice may ameliorate the devastating immunopathology and inflammation routinely observed in highly pathogenic influenza virus infections. Infection of alternatively activated BMDMf resulted in enhanced positivity for viral proteins, compared with classically activated, inflammatory BMDMf. However, neither subset propagated the infection indicating that while infection is abortive in both classical and alternatively activated BMDMf, the latter may prove more efficient at removing infectious virus from the site of infection due to enhanced infectivity. However, influenza virus was capable of driving expression of proinflammatory mediators such as iNOS and TNFa from classical and alternatively activated BMDMf even in the absence of IFNg signalling. IFNgR-/- BMDMf demonstrated a reduced inflammatory response to infection compared to Sv129 counterparts, suggesting a potentially impaired inflammatory response in vivo. This was investigated by infection of IFNgR-/- mice, which resulted in ameliorated disease, lower viral titres and mild immunopathology, demonstrating that inhibition of IFNg signalling limits the severity of disease. Additionally, mRNA expression for key inflammatory mediators was reduced, demonstrating that inhibition of the overwhelming inflammatory response to influenza virus infection is beneficial to the host, resulting in protection from immunopathology and improved prognosis, without impairing viral clearance.

This thesis is concerned with very high energy γ-ray observations of blazars observable from the southern hemisphere. The data presented were obtained using the recently deployed University of Durham Mark 6 high sensitivity Čerenkov telescope. Chapters 1 and 2 are introductory; the subjects of γ-ray astronomy, extensive air showers, Čerenkov light production, the development of the atmospheric Čerenkov technique and the current status of TeV astronomy are discussed. Chapter 3 introduces the telescopes operated by the University of Durham. The Mark 6 telescope, designed to have a low threshold energy and a high resolution imaging system, is discussed in detail. Chapter 4 presents the calibration and analysis techniques routinely applied to data obtained with the Mark 6 telescope. The chapter concludes with a set of moment parameter selections designed to reject a significant fraction of the cosmic ray cascades, while retaining the majority of γ-rays cascades. These selections have resulted in a 5σ detection of PSR 1706-44. Chapter 5 discusses active galactic nuclei and in particular blazars. Topics included are recent high energy observations; the differences between the radio/X-ray selected BL Lacs and flat spectrum radio quasars; the infrared background; high energy flux variability and γ-ray production mechanisms within these objects. The chapter concludes with a list of possible very high energy γ-ray emitting blazars observable with the Mark 6 Čerenkov telescope. Chapter 6 presents the results from four of these very high-energy γ-ray blazar candidates; PKS 0548-322, PKS 1514-24, PKS 2005-489 and PKS 2155-304. There is no evidence for γ-ray emission from these sources, either in the form of a steady flux or variable activity. Three sigma integral flux upper limits above 300 GeV are produced for these objects and the implications of these observations are discussed. The conclusions are presented in Chapter 7 as well as ideas for future work.

Previous studies of gamma ray spectra for different elements have been made by others using NaI(T1) (thallium activated, sodium iodide) detectors. This study has been done using a Ge(Li) (lithium drifted germanium) detector. Ge(Li) detectors feature much better energy resolution than do NaI(Tl) detectors. Using a Ge(Li) detector enables one to detect gamma rays closely spaced in energy that ordinarily would be unidentifiable due to the much poorer energy resolution of the NaI(Tl) detectors.Gamma ray spectra from 31 elements irradiated with 14-MeV neutrons have been examined, analyzed, and catalogued. These spectra can be used in the future as an aid in identifying elements using neutron activation analysis.

A neutron multiplicity detector system has been developed to study weak pure neutron evaporation channels from heavy-ion reactions. Such a system allows us to study nuclei far away from the line of β-stability - in particular, self-conjugate nuclei where the shell-effects for protons and neutrons are in phase and their combined effects may drive the nucleus towards superdeformation. The system consists of a neutron wall - 4 large volume Ge(Li) γ-ray detectors positioned as close as possible to the target. Neutron-gamma coincidences were recorded and neutron multiplicity events could be extracted from the data. Rejection of gamma-ray events in the neutron detectors was achieved by time-of-flight and pulse shape discrimination methods. A surface barrier detector at 0⁰ allowed a further rejection of charged particle events - especially events which feature neutrons as well.

High spin states in ⁸⁰Sr have been studied using the techniques of in-beam γ-ray spectroscopy. The reaction used was ⁵⁴Fe(²⁹Si, 2pn)⁸⁰Sr at beam energies between 85 and 110 MeV. γ-γ coincidence measurements were performed with a thin target to investigate the level structure. Both neutron gated and singles angular distribution measurements were carried out to aid in the assignment of level spins. The directional correlation ratios extracted from the γ-γ coincidence data provided a consistency check for the spin assignments. Level lifetimes were measured by the Doppler shift attenuation method in a thick target γ-γ coincidence measurement. The ground state band has been identified up to (26⁺) and three previously unobserved sidebands have been discovered. The deduced level scheme is compared with cranking model calculations; the predicted transformation to mostly non-collective excitations of an oblate shape is not observed experimentally. The behaviour of the J⁽¹⁾ and J⁽²⁾ moments of inertia is discussed and presented as evidence for either static or dynamic γ-deformation in the light Sr isotopes. In addition, the level structure is compared with IBM-2 calculations. These calculations indicate the importance of proton excitations across the Z=40 subshell gap, into the g_9/2 orbital, and suggest that the lowest lying ⁸⁰Sr sideband can be identified with the collective IBM-2 quasi-γ band. NUCLEAR REACTIONS ⁵⁴Fe(²⁹Si, 2pn), ,em>E = 85 - 110 MeV; measured Eγ, Iγ(θ), γ-γ, n-γ coincidences, DCO ratios, Doppler shifted γ-ray lineshapes. ⁸⁰Sr deduced levels, J, π, τ. Enriched target, Ge(Li), Ge, NE213 detectors.

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No description available.

全球金融風暴近年來發生頻率愈來愈快，主要的原因就是許多企業不管是在發行或投資衍生性金融商品的比重都大幅地增加，卻沒有規避它們潛在的市場風險。因此，避險策略的好壞是風險管理上很重要的一個議題。本研究的目的主要是希望在一個Delta Neutral的投資組合下，加入Delta-Gamma Neutral策略能夠使間斷調整避險的效果變得比較好。故本研究透過加入相同標的物和到期日，但不同履約價的選擇權作為避險部位，使用蒙地卡羅模擬法，模擬投資組合在持有一段時間後，未來價值可能的情境，計算風險值來衡量其避險效果。實證結果發現，當原始投資組合部位為價平選擇權所組成，避險部位若能使用相同標的物，到期日也相同，但履約價不同的價平選擇權，不論在到期日長短，皆有很好的避險效果。 / The global financial storm has happened more rapidly. The most important reason is that many enterprises published or invested in the derivatives ratio which has greatly increased without evading the potential market risk. Therefore, the advantages and the disadvantages of hedging strategy is a crucial issue in risk management. This research’s primary goal is to consider Delta-Gamma Neutral strategy in the invested combination of Delta Neutral that render the effect of discretely rebalance hedge became much better. The research entered the same underlying and expiration date, and let the different strike price’s option as hedging position. Using Monte Carol Simulation to obtain the condition of the portfolio’s value after holding a period of time, and compute the value-at-risk to measure hedging effect. The outcome showed that the hedging effect will be nice no matter the date of expiration by using at-the-money options with the same underlying and expiration date but different strike price when the original portfolio was composed of at-the-money options.

Mit vorliegender Arbeit wurde die Aussagekraft der gamma-Glutamyltransferase (GGT) im Serum des Rindes geprüft. Anhand der Krankheitsbilder von 1128 Rinderpatienten der Medizinischen Tierklinik der Veterinärmedizinischen Fakultät der Universität Leipzig der letzten sieben Jahre und eines breiten Untersuchungsspektrums zum Fett- und Leberstoffwechsel, Parametern zur Beurteilung des Nieren- und Muskelstoffwechsels, sowie dem Blutbild, der Blutgasanalyse, den Elektrolyten, Mengen- und Spurenelementen wurde untersucht, welche Parameter Beziehungen zur Aktivitätshöhe der GGT haben. Zusätzlich erfolgten Untersuchungen zum Verlauf der Enzymaktivität, der prognostischen Aussagekraft und anhand einer lebergesunden Population von 1450 Rindern die Einschätzung eines Referenzwertes der GGT. Der in der Humanmedizin nachgewiesene Einfluss, einer Vielzahl von extrahepato-biliären Erkrankungen und Parametern auf die Aktivitätshöhe der GGT, konnte in den Untersuchungen dieser Studie am Rind nicht bestätigt werden. Die GGT korrelierte hoch signifikant (p£ 0,01) mit den untersuchten Leberparametern [Glutamat-dehydrogenase (GLDH), Aspartataminotransferase (AST), Alkalische Phosphatase (AP) und Gesamtbilirubin], der Beurteilung der Gallenblase intra operationem sowie dem cholestaseinduzierenden Krankheitsbild der rechten Labmagenverlagerung (LMV). Nur geringe Bezüge ließen sich zu den anderen Parametern der klinisch-chemischen Serumanalyse, des Blutbildes und der Blutgase sowie Erkrankungen anderer Organsysteme errechnen. Somit kann die Leberspezifität der GGT in der Buiatrik und ihre Funktion als cholestaseanzeigendes Enzym bestätigt werden. Untersuchungen zur Aussage des Enzyms über den Gesamtlipidgehalt der Leber erfolgten anhand der Auswertung von Leberbioptaten, mittels Kupfersulfat-Schwimmtest und durch pathohistologische Untersuchung. Eine Korrelation der gamma-GT mit dem Gesamtlipidgehalt der Leber konnte mit r= 0,45 bzw. r= 0,39 statistisch signifikant (p£ 0,01) nachgewiesen werden. Ein schneller, hochgradiger Anstieg des Enzyms, der nach Therapie auch schnell wieder absank, sprach für Enzyminduktion durch Cholestase, wie sie auch das Krankheitsbild der rechten LMV verursacht. Langsame Anstiege, wie sie in der Literatur beschrieben worden sind, scheinen auf Leberzellschäden unterschiedlicher Genese hinzudeuten. Ein Absinken der Enzymaktivität in den Referenzbereich, erfolgte in solchen Fällen im Median nach fünfeinhalb Wochen. Die durch periphere Insulinresistenz induzierten Hyperglycämien scheinen aufgrund des verzögerten Enzymanstieges nicht mit der Höhe der GGT-Aktivität zu korrelieren. Eine generelle prognostische Aussagekraft konnte der GGT nicht nachgewiesen werden. Die Aktivitäten der Eingangsuntersuchungen von Patienten mit exitus letalis unterschieden sich nicht statistisch signifikant von den Aktivitäten der überlebenden Rinder. Auch aus den Verlaufs- und Enduntersuchungen konnten keine Aussagen quo ad vitam getroffen werden. Patienten, die eine rechte LMV aufwiesen und mit einer hochgradigen Erhöhung der GGT vorgestellt wurden, waren prognostisch schlechter zu bewerten, als Rinder mit dem gleichen Krankheitsbild und einer niedri-geren Enzymaktivität. Bei Patienten mit linker LMV und solchen ohne LMV ergab sich in der Regel, unabhängig vom Ausgang, ein Anstieg der Enzymaktivität im Verlauf des stationären Aufenthaltes. Ein Referenzwert der GGT-Aktivität im Serum des Rindes konnte anhand einer lebergesunden Population bei 30 U/l ermittelt werden. 80 % der Leberbiopsien wiesen eine Leberverfettung auf, davon 50 % eine mittel- oder hochgradige. Eine prognostische Aussagekraft des Grades der Leberverfettung quo ad vitam konnte in dieser Studie nicht bestätigt werden. Die Aussagekraft der untersuchten Leberenzyme zum Verfettungsgrad der Leber waren statistisch hoch signifikant (p£ 0,01) mit Korrelationskoeffizienten der AST mit r= 0,71, der GLDH mit r= 0,59, dem Gesamtbilirubin mit r= 0,43 und der AP mit r= 0,39. Schlussfolgerungen: Die GGT-Aktivität im Serum des Rindes kann (unter Berücksichtigung des herabgesetzten Referenzwertes) aufgrund der nachgewiesenen Spezifität und Sensitivität bei hepatobiliären Erkrankungen, durchaus als eine diagnostische Bereicherung im buiatrischen Lebersuchprogramm angesehen werden. Die Enzymaktivität korrelierte zwar mit dem Grad der intrahepatischen Lipidakkumulation, aufgrund des perakuten bis akuten Geschehens bei Kühen, konnten im Gegensatz zur Humanmedizin, latente Leberveränderungen nicht sicher diagnostiziert werden. Für die Therapie und Prognose wird sich (außer bei der rechten LMV) kaum ein Nutzen aus der Bestimmung der GGT-Aktivität im Serum des Rindes ziehen lassen.