The effects of ionizing radiation on the breakdown-voltage degradation of power-MOSFET termination structures were examined through two-dimensional simulation. A wide variety of sensitivity to surface-charge density was found for various devices employing floating field rings and/or equipotential field plates. Termination structures that were both insensitive to surface charge and possessed a high breakdown voltage were identified. The results were compared with measurements made on selected structures. The principal ionizing radiation damaging mechanisms in MOS devices are discussed. Modifications made to an existing simulation program in order to simulate these complex field ring and field plate structures are described. Background information into how these termination structures improve the breakdown voltage and their sensitivities to positive interface charge buildup is investigated.

In this dissertation, we have examined mineral assemblages and geomorphologic features in the Sisyphi Planum region of Mars, as well as examined the mineral assemblage of palagonite in Iceland. Chapter 2 is focused on the mineral assemblages detected on possible glaciovolcanic edifices in the Sisyphi Planum region of Mars. Minerals were identified utilizing visible/near-infrared orbital spectra from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Analysis of eleven CRISM images located on the volcanic edifices revealed three distinct spectral classes in the region which are interpreted to be: gypsum-dominated, smectite-zeolite- iron oxide-dominated (possibly palagonite), and polyhydrated sulfate-dominated material. The possible palagonite detections on the volcanic edifices, the geomorphology of the region, and the analogous terrestrial mineralogy of subglacial eruptions strongly suggests the formation of these minerals during subglacial eruptions or associated hydrothermal systems. This implies that thick water ice sheets were present in this region in the late Noachian or early Hesperian, and that the subglacial hydrothermal systems could have supported habitable environments with excellent biosignature preservation potential. Chapter 3 is focused on evaluating the variability of the composition and crystallinity of palagonite on Earth in order to inform efforts to identify it on Mars. We hypothesized that variability in palagonite composition and crystallinity could occur due to differences in environmental conditions during formation. Palagonite samples were collected in Iceland at subglacial volcanic sites around Reykjavík in the Western Volcanic Zone, on the southern coast in the Eastern Volcanic Zone, and from the Herðubreið tuya and Askja volcano in the Northern Volcanic Zone. Visible/near-infrared reflectance spectroscopy, thermal-infrared emission spectroscopy, and quantitative XRD were used to assess the bulk mineralogy, crystallinity, and clay composition of all samples. Results show the sampled palagonites contain partially devitrified glass, unaltered glass, and secondary minerals including clay minerals, poorly crystalline ferric oxides, and zeolites. However, one sample (SCoast01) shows a vastly different mineral assemblage in all sample techniques, including well-crystalline Fe/Mg-clays as opposed to the poorly-crystalline Al-clays observed in our other samples. Based on previous studies of subaqueous palagonites and the location this sample was collected from, we hypothesize that the SCoast01 sample was formed in a submarine environment rather than subglacial. This suggests that it may be possible to differentiate submarine vs. subglacial palagonite on Earth based on composition and from remote sensing observations on Mars. Chapter 4 is a geomorphologic study of the Sisyphi Planum region of Mars where we identified and classified the tops of the Sisyphi Montes as well as geomorphologically mapped the Sisyphi Planum region. Here, we address an overarching question: What is the relationship between the Sisyphi Montes and the ice in this region? To do this, we identified 106 edifices in the region and classified them into five categories: 1) flat topped, 2) rounded tops, 3) sharp peaks, 4) cratered peaks, and 5) height less than 300 meters – a “catch-all” category for all features below the specified height, which exhibit less distinctive morphologies in MOLA topography. While many of the edifices could be sub-glacial in origin, we find that the only morphologic class that exhibits uniquely subglacial morphologies are the flat-topped edifices. These edifices are similar to terrestrial tuyas, which form when a subglacial volcano breaches an ice sheet and erupts a plateau of sub-aerial lavas. Based on the geomorphologic map and topographic data, we have shown that flat-topped edifices are all located outside of regions that we map as the Mantled Unit, which we infer to be related to the Dorsa Argentina Formation. The combination of the flat topped edifices and their location outside of the mapped ice-related regions strongly suggests that the ice in the region was once more extensive than what is currently observed. While this has been proposed in the past, it has not been documented how far the ice sheet could have extended. Here we show that the ice must have extended to at least as far as the flat topped edifices in the region. The combination of these chapters using both mineralogy and morphology suggest that the Sisyphi Planum region of Mars was subglacial in origin. <br><br>

Space exploration continues to expand humanity’s understanding of the universe. And, while Americans have widely favorable attitudes towards efforts to explore outer space, certain religious beliefs appear to be associated with more negative attitudes towards space exploration and the search for extraterrestrial life. The current study explored the role of religion and creationism on attitudes towards space exploration and the search for extraterrestrial life. Priming techniques were used to test whether increasing the accessibility of religious and creationist concepts led to more negative attitudes towards space exploration and beliefs about extraterrestrial life. Participants (N = 230) encountered an explicit prime of religion, creationism, or a control prior to completing a word fragment task and measures of attitudes towards space exploration and beliefs about extraterrestrial life. The results of Bayesian estimation and hypothesis testing did not support the prediction. However, exploratory analyses indicated very strong evidence of atheists having more positive attitudes towards space exploration and beliefs about extraterrestrial life than theists. These findings suggest that while priming religion and creationism did not appear to influence reported attitudes, attitudes towards space exploration and the search for extraterrestrial life may differ based on belief in god.

No description available.

Source: Dissertation Abstracts International, Volume: 57-08, Section: B, page: 5173. Advisor: Lawrence W. Whitehead. Includes bibliographical references.

This study focuses on the discourse that orders and creates a logic of the extraterrestrial during postmodernity, what I term "Fringe." Using Foucault's notion of discourse, I define and theorize Fringe and its formation during postmodernity, looking at the particular features of the historical moment post-1960 that contributed to the creation and regulation of a particular extraterrestrial. I then investigate historical conceptions of the extraterrestrial from Aquinas to Kant. This genealogy of the extraterrestrial reveals a rich history of the extraterrestrial and compares this history with Fringe. After this I discuss two precursors of Fringe discourse: the Society for Psychical Research and the writings of anomalous researcher Charles Fort. This investigation of pre-Fringe notions of the psychical in discourse shows how the SPR and Fort's work both created new ways of looking at and speaking about phenomena falling outside the purview of "normal science" and contributed to the formation of Fringe while also being distinguishable from it. Finally, I analyze two popular iterations of Fringe discourse—the ancient aliens hypothesis and the abduction narrative—as popularized in the works of Erich von Däniken and Whitley Strieber.

<p> Wet chemical neutron activation analysis procedures for Au., Pd and Ir together with a non-destructive gamma-counting procedure for Mn are described and applied to the determination of these metals in three Antarctic (E21 -17, E13-3 and E 17-10) and one Caribbean (P63 04-9) deep-sea cores. A total of 49 samples were analyzed. The average values of Au, Pd, Ir in ppb and Mn in Wt.% (together with standard deviations of the mean are: (see table in theses) No large differences exist between Au, Pd and Ir concentrations in different types of deep-sea sediments nor in cores from different areas and their values are within the general concentration range found in most crustal rocks. A general discussion of the sources of precious metals in deep-sea sediments is given. The most important precious metal source in the cores studied in this work is detrital material from land. The contribution of extraterrestrial material to the Au and Pd content of deep-sea sediments is not important but in cores with depositional rates as low as a few tenths of a mm per thousand years, extraterrestrial material may account for more than half of the total Ir content. From the non-detrital Ir content of deep-sea manganese nodules the accretion rate of extraterrestrial material over the. entire surface of the earth is calculated to be about 200 tons per day with an upper limit of 310 tons per day. The constancy of Ir content in deep-sea cores as a function of depth suggests that the influx of extraterrestrial material during the past 3 to 4 million years was probably fairly constant. </p> / Thesis / Master of Science (MSc)

No description available.

The objective of this study was to characterize the effects of the space environment on the engineering properties and chemistry of a chemically modified T300/934 graphite-epoxy composite system. The material was subjected to 1.0 x 10¹⁰ rads of 1.0 MeV electron irradiation under vacuum to simulate 30 years in geosynchronous earth orbit. Monotonic tension tests were performed at room temperature (75° F /24° C) and elevated temperature (250° F/121° C) on 4-ply unidirectional laminates. From these tests, in-plane engineering and strength properties (E₁, E₂, ν₁₂, G₁₂, X_T, Y_T) were determined. Cyclic tests were also performed to characterize energy dissipation changes due to irradiation and elevated temperature. Large diameter graphite fibers were tested to determine the effects of radiation on the stiffness and strength of graphite fibers. No significant changes were observed. Dynamic-mechanical analysis demonstrated that the glass transition temperature was lowered by 50° F (28° C) after irradiation. Thermomechanical analysis showed the occurrence of volatile products generated upon heating of the irradiated material. The chemical modification of the epoxy did not aid in producing a material which was more “radiation resistant" than the standard T300/934 graphite-epoxy system. Irradiation was found to cause crosslinking and chain scission in the polymer. The latter produced low molecular weight products which plasticize the material at elevated temperatures and cause apparent material stiffening at low stresses at room temperature. / M.S.

In this essay, I examine the ways in which new myths were made of Barack Obama in the months leading up to, and immediately following, the 2008 U.S. Presidential Election at three sites of cultural production: a UFO-based religious movement historically grounded in the black Israelite religious tradition, TIME magazine’s 2008 “Person of the Year” edition, and Sean Hannity’s “The Real Barack Obama” airing on the FOX News network. I argue that, while the content of these three Obama-myths varies considerable, the ways in which these myths are constructed, and function, are in fact rather similar.