Oscillating shells: A model for a variable cosmic object

A model for a possible variable cosmic object is presented. The model consists of a massive shell surrounding a compact object. The gravitational and self-gravitational forces tend to collapse the shell, but the internal tangential stresses oppose the collapse. The combined action of the two types of forces is studied and several cases are presented. In particular, we investigate the spherically symmetric case in which the shell oscillates radially around a central compact object

The Blurred Line Between Racism and Innocent Depictions: An Analysis of "Tacos and Tequila"

My research explores the question ???When does something stop being funny and start being racist???? by looking specifically at the ???Tacos and Tequila??? incident. ???Tacos and Tequila??? was a controversial social exchange that occurred in the Fall of 2006 between a fraternity in the Inter Fraternity Council, Zeta Beta Tau, and a sorority in the Panhellenic Council, Delta Delta Delta. The controversy arose from the way these primarily Caucasian organizations depicted Mexican/Mexican American Culture. These portrayals are viewed as malicious racism by one side and as innocent depictions by the other side; I hope to explore why the two sides disagree on when ???the line is crossed??? and make recommendations on how to educate both sides and construct a clearer picture of what is racist. Although a consensus is unlikely, at the very least steps can be taken toward reaching a more understanding and tolerant campus environment.unpublishe

Towards optical intensity interferometry for high angular resolution stellar astrophysics

Most neighboring stars are still detected as point sources and are beyond the angular resolution reach of current observatories. Methods to improve our understanding of stars at high angular resolution are investigated. Air Cherenkov telescopes (ACTs), primarily used for Gamma-ray astronomy, enable us to increase our understanding of the circumstellar environment of a particular system. When used as optical intensity interferometers, future ACT arrays will allow us to detect stars as extended objects and image their surfaces at high angular resolution. Optical stellar intensity interferometry (SII) with ACT arrays, composed of nearly 100 telescopes, will provide means to measure fundamental stellar parameters and also open the possibility of model-independent imaging. A data analysis algorithm is developed and permits the reconstruction of high angular resolution images from simulated SII data. The capabilities and limitations of future ACT arrays used for high angular resolution imaging are investigated via Monte-Carlo simulations. Simple stellar objects as well as stellar surfaces with localized hot or cool regions can be accurately imaged. Finally, experimental efforts to measure intensity correlations are expounded. The functionality of analog and digital correlators is demonstrated. Intensity correlations have been measured for a simulated star emitting pseudo-thermal light, resulting in angular diameter measurements. The StarBase observatory, consisting of a pair of 3 m telescopes separated by 23 m, is described.Comment: PhD dissertatio

HIV-1 Protease Inhibitors From Marine Brown Alga: A Literature Review

The human immunodeficiency virus type 1 (HIV-1) causes an infectious disease that if left untreated can progress to acquired immunodeficiency syndrome (AIDS) and be fatal. Finding a cure and more treatments for HIV has become a top priority in medical research, and due to the cost of synthetic HIV medication, finding a low-cost alternative is essential. Marine pharmacology has provided a possible solution to costly HIV medication through compounds derived from marine brown algae that inhibit the HIV-1 protease (PR). The objective of this study is to emphasize the necessity for further research in HIV-1 protease inhibition using marine wildlife-derived compounds. In order to better understand the process of protease inhibitors, I will investigate the process of producing and purifying HIV-1 PR, extracting and isolating brown algal compounds, and the assays used to test the inhibition effects of the brown alga compounds. This study demonstrates the potential of marine pharmacology as an inexpensive alternative to synthetic pharmaceuticals for HIV-1 PR inhibition

Local cohomology properties of direct summands

In this article, we prove that if $R\to S$ is a homomorphism of Noetherian rings that splits, then for every $i\geq 0$ and ideal $I\subset R$, \Ass_R H^i_I(R) is finite when \Ass_S H^i_{IS}(S) is finite. In addition, if $S$ is a Cohen-Macaulay ring that is finitely generated as an $R$-module, such that all the Bass numbers of $H^i_{IS}(S)$, as an $S$-module, are finite, then all the Bass numbers of $H^i_{I}(R)$, as an $R$-module, are finite. Moreover, we show these results for a larger class a functors introduced by Lyubeznik. As a consequence, we exhibit a Gorenstein $F$-regular UFD of positive characteristic that is not a direct summand, not even a pure subring, of any regular ring.Comment: 8 pages. References updated. Minor change

Tax avoidance and the political appeal of progressivity

Empiriquement, on observe que la majorité des Etats a fait le choix d'un système d'imposition progressif. Pourtant, le fondement théorique de ce choix n'est pas évident. Si l'on interprète le système d'imposition appliquée comme le résultat d'un jeu entre deux partis politiques Downsiens, le fait que la majorité de la population soit relativement pauvre permet de conforter l'observation empirique. Cependant, des résultats théoriques récents montrent que, à l'équilibre, des électeurs purement égoïstes ne font pas toujours ce choix-là. Cet article tente de raffiner ces derniers modèles théoriques pour proposer une autre explication au choix d'un système progressif. Notre thèse est la suivante : la présence d'évasion fiscale – caractéristique importante des systèmes d'imposition sur le revenu – a des effets sur l'équilibre du jeu politique en modifiant les préférences des individus les plus riches de la société. Dans un premier temps, l'ensemble des équilibres en stratégies mixtes du jeu est caractérisé (pour des systèmes d'imposition de type quadratique), et on montre alors que l'évasion fiscale renforce l'élection de systèmes progressifs d'imposition. Dans un deuxième temps, on analyse un cas de système d'imposition de type “wiggling" en montrant que l'évasion fiscale mène, quand elle est suffisamment importante, à l'élection de systèmes progressifs d'imposition avec certitude.Compétition électorale;Taxtation du revenu progressive;Evasion fiscale;Equilibre en stratégies mixtes

Our Vulnerable Teenagers: Their Victimization, Its Consequences, and Directions for Prevention and Intervention

Teenagers are twice as likely as any other age group to be victims of violent crime, and one in five teenagers report being the victim of a violent crime, according to a new report. The single greatest factor in predicting criminal behavior on the part of teenagers, the report also found, was not teenage pregnancy, drug use, or truancy, but whether they had been a victim of crime. This publication provides a new and comprehensive analysis of existing -- but largely unnoticed -- research and data on the crime experiences of American teenagers ages 12-19, who make up about 14 percent of the general population, but represent 25 percent of victims of violent crime