Development of a petawatt class Ti:Sapphire laser for the excitation of extreme radiation sources

2020 Spring.Includes bibliographical references.This dissertation describes the design, construction and characterization of a high peak power, high repetition rate, Titanium-Sapphire laser system. This chirped-pulse amplification (CPA) laser delivers femtosecond pulses of up to 0.85 PW peak power. By utilizing pump laser amplifiers with a slab configuration high repetition rate are achieved, 3.3Hz, the highest at which Petawatt-class lasers have been operated to date. This 800nm laser also has a high power, ultra-high contrast 400 nm beamline. By frequency doubling the 800 nm with a KDP crystal at ≥ 40% conversion we are able to achieve a contrast of > 1 × 10-12. The ability to focus this second harmonic beam to ~1.2 μm Full Width at Half Maximum (FWHM) spot size made it possible to achieve intensities up to ~ 6.5 ×1021 W/cm2. With these high intensities and high contrast this laser is a powerful tool in many applications especially in the study of laser/matter interactions at relativistic plasmas. This Ti:Sapphire laser was used for the excitation of plasma based soft x-ray (SXR) lasers. prior to this work compact, repetitively fired, gain-saturated x-ray lasers had been limited to wavelengths above λ = 8.85 nm. We were able to demonstrate SXR lasers operating in the gain-saturated regime down to wavelengths as low as λ = 6.85 nm in Ni-like Gd. Gain was also observed at λ = 6.4 nm, and λ = 5.8 nm in Ni-like Dy. As an application of plasma-based SXR lasers, single shot Fourier holograms covering a large area of view were demonstrated using an 18.9nm laser with high spatial coherence based on dual plasma amplifier. Compact SXR lasers have made possible applications in nano-scale imaging, dense plasma diagnostics and a variety of new studies of materials and surfaces. Other applications that were enabled by this Petwatt-class laser discussed elsewhere include the study of the interaction of relativistic laser pulses with aligned nanostructures, producing record conversion efficiency of optical laser light into picosecond x-ray pulses with photons of > 1 KeV energy and flashes of deuterium-deuterium fusion neutrons

The Effects of Geometry and Architecture of Polymer Matrix Composites on Acoustic Emissions

The purpose of this project is to study how the variance of the geometry and architecture of polymer matrix composites (PMCs) affect the acoustic emissions measured whilst said structures are subjected to tensile stress. In these tests, a method called Modal AE will be utilized. In Modal AE, some relationships between sources and waves in various materials and geometries are presented in other papers/research. This study will focus on how different thickness and different makeup/ply patterns affect the acoustic emission tests. Some research has been completed and shown how energy attenuation affects the frequency content on PMCs similar to the ones chosen for this project. Using a similar test setup and analysis the goal of this project is to see if the thickness/geometry of these samples will affect energy attenuation and therefore affect frequency content. The reason frequency content is so important in AE is that it is a method of exploring the different damage modes PMCs experience during stress tests. From this data more information can be obtained about frequency content and the effects that energy attenuation/architecture/geometry can have on PMCs. These AE events can also be used to identify the location of a break and to see how internal breaks have propagated through the structure. Polymer matrix composites (PMCs) are widely used in the aerospace industry, particularly in structures securing thrust generating systems to the primary structure. Each test subjects a polymer matrix composite (PMC) of a specific thickness and weave design to determine the damage modes for each sample. The peak frequency of the propagated acoustic emissions with respect to the time domain will also be measured

Using Thermocouple, Thermistor, and Digital Sensors to Characterize the Thermal Wake Below Ascending Weather Balloons

In this paper we present additional results from our on-going research effort to characterize the thermal wake that trails below ascending latex weather balloons on flights into the stratosphere; a wake which interferes with the ability of temperature sensors in payload boxes hanging from the balloon (and hence enveloped by the wake) to correctly measure the ambient temperature of the atmosphere through which the balloon is ascending. A “wake boom” is used to measure temperature variations up to 1.5 m horizontally from varying distances directly below the neck of the balloon. Results to date agree with the literature that especially above the tropopause the thermal wake is warmer than the ambient air during daytime ascents, due to solar radiation warming the balloon skin, but colder than ambient air during night-time ascents, due to adiabatic cooling of the gas inside the balloon (which also occurs in the daytime, but is smaller than the daytime warming effect). In particular we report on thermal wake characterization using (Neulog) thermocouple sensors, as compared to (HOBO) thermistors and (Arduino-logged) DS18B20 digital temperature sensors. We also present additional results from X-shaped 2-dimensional wake booms or “X-Booms” which allow us to compare wake temperatures on the sun side versus the shade side of the balloon, looking for asymmetries in the horizontal temperature profile

Crummer/Suntrust Portfolio: Analysis and Recommendations [2008]

Unfavorable economic conditions have prompted the investment team to meet a short-term goal: preserve the value of the portfolio by reducing overall risk. A top down analysis of the current portfolio resulted in recommendations to change the portfolio by eliminating funds, investing in long term government bonds, TIPS and large cap value type securities. Allocations of securities was performed by either overweighting or underweighting a particular sector, depending on its historical and expected return during a recession. Individual securities were analyzed by our sector analystsand recommendations of hold, buy or sell were made. The outcome.... a robust portfolio, that will preserve its value during the recession by reducing its overall risk by 25%

Unfolding Humanity: Cross-Disciplinary Sculpture Design

Unfolding Humanity is a 12 foot tall, 30 foot wide, 2 ton interactive metal sculpture that calls attention to the tension between technology and humanity. This sculpture was conceived, designed, and built by a large group (80+) of faculty, students, and community volunteers at the University of San Diego (USD). The piece is a dodecahedron whose pentagonal walls unfold under human power, an engineered design that alludes to Albrecht Dürer\u27s 500-year-old unsolved math problem on unfolding polyhedra. When closed, the mirrored interior of the sculpture makes visitors feel as though they are at the center of the universe. The idea for the sculpture began with two USD mathematics professors, they recount their journey elsewhere (Devadoss & Hoffoss, 2019). This narrative focuses on the story of bringing their vision to a reality

Mainstreaming domestic and gender-based violence into sociology and the criminology of violence

Sociological and criminological views of domestic and gender-based violencegenerally either dismiss it as not worthy of consideration, or focus on specificgroups of offenders and victims (male youth gangs, partner violence victims). Inthis paper, we take a holistic approach to violence, extending the definition fromthat commonly in use to encompass domestic violence and sexual violence. Weoperationalize that definition by using data from the latest sweep of the CrimeSurvey for England and Wales. By so doing, we identify that violence is currentlyunder-measured and ubiquitous; that it is gendered, and that other forms of violence (family violence, acquaintance violence against women) are equally ofconcern. We argue that violence studies are an important form of activity forsociologists

Características de programas de atividade física na atenção básica de saúde do Brasil

The aim of this study was to describe the characteristics of programs that promote physical activity in the public primary care system by region of Brazil, subject to the presence or absence of multidisciplinary primary care teams (NASF). We conducted a cross sectional and population-based telephone survey of the health unit coordinators from 1,251 health care units. Coordinators were asked about the presence and characteristics of physical activity programs. Four out of ten health units reported having a physical activity intervention program, the most common involving walking groups. Most of the activities were performed in the morning, once or twice a week, and in sessions of 30 minutes or more. Physical education professionals were primarily responsible for directing the activities. Interventions occurred in the health unit itself or in adjacent community spaces. In general, these characteristics were similar between units with or without NASF, but varied substantially across regions. These findings will guide future physical activity policies and programs within primary care in Brazil.El objetivo fue describir las características de los programas de actividad física en atención primaria, de acuerdo con el Centro de Apoyo a la Salud de la Familia (NASF) y las regiones de Brasil. Se realizó una encuesta transversal telefónica con 1.251 coordinadores de las unidades de salud. Se preguntó a los coordinadores acerca de la presencia y características de intervenciones de actividad física en funcionamiento. Cuatro de cada diez centros de salud reportaron tener una intervención de actividad física, especialmente, grupos de paseo. La mayor parte de las actividades se llevan a cabo por la mañana una vez o dos veces por semana con sesiones de 30 minutos o más. Los profesores de educación física son los principales responsables de la supervisión de las actividades. Los programas se llevan a cabo en la clínica o en otros espacios públicos. Estas características fueron similares en unidades con o sin NASF y mostraron una variación regional en su prevalencia. Estas características permitirán enfocar próximas acciones para promover la actividad física dentro de la atención primaria de salud.O objetivo foi descrever as características dos programas de atividade física na atenção básica de saúde de acordo com a presença de Núcleo de Apoio à Saúde da Família (NASF) no município e por regiões do Brasil. Foi realizado um estudo transversal por inquérito telefônico com 1.251 coordenadores de unidades de saúde. Foi aplicado um questionário sobre presença de intervenções com atividade física e suas características de funcionamento. Quatro em cada dez unidades de saúde relataram ter uma intervenção com atividade física, especialmente grupos de caminhada. A maior parte da atividade é realizada na manhã uma vez ou duas vezes por semana, com sessões de 30 minutos ou mais. Profissionais de educação física são os principais responsáveis por supervisionar as atividades. Os programas ocorrem na unidade de saúde ou outros espaços comunitários. Estas características, de modo geral, foram semelhantes entre unidades com ou sem NASF no município e apresentaram variação entre as regiões. Os resultados desse estudo irão permitir melhor direcionamento das próximas ações de promoção de atividade física na atenção básica de saúde.Universidade Federal de São Carlos Departamento de GerontologiaUniversidade Estadual Paulista Núcleo de Atividade Física, Esporte e SaúdeUniversidade Federal de Pelotas Grupo de Estudos em Epidemiologia da Atividade FísicaUniversidade Federal de São Paulo (UNIFESP)Centers for Disease Control and Prevention National Center for Chronic Disease Prevention and Health PromotionWashington University in St. Louis George Warren Brown School of Social WorkUniversidade de São Paulo Escola de Artes, Ciências e HumanidadesHospital Israelita Albert EinsteinMinistério da SaúdeEmory University Rollins School of Public HealthUNIFESPSciEL