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This work presents results on the study of the scintillation of high-pressure Xenon gas irradiated by various sources. Noble gases such as Xenon give off characteristic scintillation light when irradiated. The goal of the study was to develop a characteristic based on the scintillation time response of Xenon gas that would reliably discriminate between events from different types of primary radiation (neutron or gamma). A reliable discrimination characteristic would enable the development of room temperature, gas phase detectors for use in the search for Galactic Dark Matter. The surprising result of the present work was that a reliable discrimination characteristic existed for distinguishing x-ray, gamma ray, and alpha particle events. Results for neutrons were negative. This was due to several factors: Ionization tracks in xenon generally form two roughly cylindrical regions. A region near the center of the track, called the core, has very dense ionization. An outer region, called the penumbra, has sparse ionization. In Xenon, recombination of ions and the subsequent scintillation from the penumbra region happens slowly and can be easily distinguished from scintillation that happens in the core region. Nuclear recoils resulting from neutron collisions that give recoil energies in the same range as that predicted for WIMP-nuclear collisions are of such low energy that they do not produce a significant penumbra region in Xenon gas. As such, the scintillation time response for these events is similar to that of high-energy gamma rays. Other results of the present work include: The amount of energy deposited in the gas needed to produce a scintillation photon was measured for gamma rays and was found to be in agreement with results from other experiments. Low-energy gamma rays appeared to produce more scintillation photons for an equal amount of energy deposited than high-energy gamma rays. The decay of the singlet and triplet molecular states of xenon was observed and the lifetimes of these states were measured. The singlet state lifetime was found to be independent of pressure while the triplet state lifetime was dependent on pressure. The lifetimes were measured and compared to previous results. A better understanding of the ionization, recombination, and scintillation processes of gaseous Xenon was achieved. Argon gas has been proposed as an alternative to Xenon gas for use in a high-pressure gas scintillation detector due to its lower mass and its property of forming a core ionization region that is much less dense than the core region of xenon. This substitution may allow for a reliable discrimination characteristic to be developed. / Physics

It is psychologists, psychiatrists, neuroscientists, and philosophers who most often attempt the formal study of consciousness: it is writers who observe the impossibility of any such study. In the spirit of Joseph O'Neill, Muriel Spark, and J.K. Rowling, with reference to cross-disciplinary thinkers like Donella Meadows, Douglas Hofstadter, and Rudy Rucker, Tree of Knowledge concerns itself with the mystery of mystery and the knowledge of knowledge. This collection of short stories bespeaks the human observer's paradoxical situation in all its the diverse implications, including moral confusion, tragedy, and violence, but also comedy, beauty, and the possibility of transcendence.

Dark Patterns are a variety of different software designs that are used to manipulate and mislead the users of an application or service. These patterns range from making it harder to end a subscription service, adding additional charges to a purchase, or having the user give out data or personal information. With how widespread and varied dark patterns are, it led to us creating a way to detect and warn users of different dark patterns. In this study, we created Dark Pattern Detector, a Chrome extension that would help users detect and understand three different dark patterns: Hidden Costs, Disguised Ads, and Sneak into Basket. This extension was made to detect each of these patterns on any web page while not requiring any information from the user or their data. Study participants installed the extension and completed a series of tasks given to them that would occur on different websites containing the previous dark patterns. After completing the tasks, the users were surveyed to give feedback on what they thought of the extension and what suggestions for change they had. In the study, we had 40 participants and we found that 50% of the users were completely unfamiliar with dark patterns and that 77.5% have used extensions before. For the five tasks, each one had a majority of the participants successfully complete them. Finally, when asked about what they thought, the majority of the participants gave positive feedback claiming that they found the extension useful, interesting, and a good idea. Many participants also gave useful feedback about what changes or additions they would like to see. With our results, we can help users have a better understanding of dark patterns and have created a baseline for any future research done on dark pattern knowledge and detection. / Master of Science / Dark patterns are designs on the internet that websites use to trick its users. They may be used to hide advertisements, make the user spend more time or money on their website or more. Our goal was to create a way to help protect anyone on the internet and their information. For this study, we created a program called Dark Pattern Detector that would help the users see different dark patterns that appeared on websites. A study was conducted that had the participants use our program and give us feedback on what they thought of it as well as data on how well it worked. Out of the 40 participants, we found that half the users were unfamiliar with what dark patterns were. Once they completed the study, we saw that the majority of users were able to complete tasks while using our program and gave positive feedback. Seeing the positive feedback and results from our study, we believe that we can help users not get tricked by these patterns and help forward future research on Dark Patterns.

The present study is part of a long time cooperative study of the Education and Home Economics Departments of North Texas State Teachers College begun in 1940. The purpose is to compare the dark adaptations of second and third grade children made in 1940 with those made in 1941, and to determine also the dark adaptation of a group of fifth and sixth grade children receiving vitamin A concentrate.

Because of the paucity of evidence with regard to dark adaptation and the vitamin A status of pre-school children, this study is made. The purpose, therefore, is to add to the available data on this subject through an investigation of the bio-photometer as a means of detecting vitamin A deficiency in pre-school children.

The purpose of the study is to determine the dark adaptation of second grade children in Denton, Texas.

The nature of dark matter and dark energy are currently two of the most important questions in cosmology. In this thesis, we consider studying the dark universe with the redshifts and peculiar velocities of galaxies. In the first half of the thesis, we analyse current peculiar velocity measurements of the bulk flow of our local volume to estimate the underlying dark matter power spectrum. In the second half of the thesis, we consider the prospects for measuring dark matter and dark energy with future galaxy redshift surveys, particularly via redshift space distortions. Fundamentally, bulk flow measurements and redshift space distortions are both sensitive probes of the power spectrum and growth rate of cosmic structure. In the final chapter, we directly compare power spectrum measurements with both methods.

La présente thèse traite des propriétés de la Matière Noire (MN), en particulier dans le contexte du Next-to-Minimal Supersymmetric Standard Model (NMSSM). En premier lieu, est examinée la question de savoir si un neutralino dans le NMSSM pourrait expliquer un excès de photon monochromatique possiblement présent dans les données Fermi-LAT. Il est montré qu’un neutralino, associé à l’anéantissement d’une particule Higgs CP-impair échangée dans le canal s, peut, en principe, donner lieu à une section efficace suffisamment grande. Sont également étudiés les modèles asymétriques de matière noire aux fins d’expliquer la MN actuelle et la densité de baryons. Les limites supérieures de l’auto- anéantissement de la section efficace, qui peuvent potentiellement détruire la MN asymétrique, sont dérivées et appliquées à une variété de modèles. Enfin, est proposé un modèle supersymétrique qui prévoit des sneutrinos en tant que MN asymétrique viable et qui explique les petites valeurs de la masse des neutrinos. Sont ainsi étudiées des limites à ce modèle à partir de la physique des particules, de la cosmologie et des observations de la MN. / This thesis deals with Dark Matter (DM) properties, mainly in the context of the Next-to-Minimal Supersymmetric Standard Model (NMSSM). First, it is examined whether a neutralino in the NMSSM could explain a monochromatic photon excess possibly present in the Fermi-LAT data. It is shown that neutralino pair annihilation with a CP-odd Higgs exchanged in s-channel can, in principle, give rise to a sufficiently large cross section. Asymmetric dark matter models, aiming at the explanation of the coincidence of present-day DM and baryon abundances, are also discussed. Upper bounds on DM self-annihilation cross section, which can potentially destroy the DM asymmetry, are derived and applied to a variety of models. Finally, a supersymmetric model is proposed, providing sneutrinos as viable asymmetric DM and explaining the smallness of neutrino masses. Bounds on this model from particle physics, cosmology and DM searches are studied.

In this work we test a cosmological model with an interaction between dark energy and dark matter, where a tachyon scalar field plays the role of dark energy. With that in mind, we developed a numerical code that solves the background equations and extracts the cosmological parameters and we compared the results of the interacting tachyon model with those of other dark energy candidates. Our results show that the model indeed explains the observational data and has interesting cosmological properties, but might face challenges when compared to other dark energy candidates. / Neste trabalho testamos um modelo cosmológico com uma interação entre energia escura e matéria escura, onde um campo escalar taquiônico desempenha o papel da energia escura. Para isso, desenvolvemos um código computacional que resolve as equações numericamente e vincula os parâmetros cosmológicos e, assim, comparamos os resultados do modelo taquiônico interagente com os de outros candidatos à energia escura. Nossas análises mostram que o modelo, de fato, consegue explicar os dados observacionais, além de possuir propriedades cosmológicas interessantes, mas apresenta dificuldades quando comparado a outros modelos de energia escura.