Spectroscopic analysis of atoms and molecules

151 p.En esta tesis he estudiado varios aspectos de la respuesta espectroscópica de varios átomos y moléculas a una fuente electromagnética externa. Entender dicha respuesta cuántica tanto nuclear como electrónica es muy complicado, excepto si se usan sistemas simples. Para simplificar este problema he usado la Aproximación de Born Oppenheimer (BOA) para la parte nuclear y la Teoría del Funcional de la Densidad Dependiente del Tiempo (TDDFT) para la parte electrónica debido a su simplicidad y precisión.En dicha tesis he trabajado en tres proyectos. En primer lugar, he estudiado el espectro de excitación lineal para moléculas simples donde se puede resolver el problema cuántico electrónico y nuclear. Así he podido determinar la precisión de la BOA par estudiar dicho espectro. En segundo lugar, he estudiado la ionización de átomos de Argón y Neón compuestos de varios electrones a un campo externo fuerte. He comparado la ionización total e individual de dichos electrones usando TDDFT con otro método teórico para analizar la precisión de TDDFT. En tercer lugar, he estudiado la evolución de los orbitales moleculares de una molécula de etileno expuesta a un sistema bomba-sonda para ionizarla. He observado como los cambios nucleares pueden afectar la evolución de los orbitales mediante un análisis del espectro de fotoemisión (PES) y de la distribución fotoangular (PAD)

Modelling the effect of nuclear motion on the attosecond time-resolved photoelectron spectra of ethylene

Using time dependent density functional theory (TDDFT) we examine the energy, angular and time-resolved photoelectron spectra (TRPES) of ethylene in a pump-probe setup. To simulate TRPES we expose ethylene to an ultraviolet (UV) femtosecond pump pulse, followed by a time delayed extreme ultraviolet (XUV) probe pulse. Studying the photoemission spectra as a function of this delay provides us direct access to the dynamic evolution of the molecule's electronic levels. Further, by including the nuclei's motion, we provide direct chemical insight into the chemical reactivity of ethylene. These results show how angular and energy resolved TRPES could be used to directly probe electron and nucleus dynamics in molecules.Comment: 9 pages, 6 figure

Transitions to tertiary education: Measuring and minimising inequality between private and public school students in a university outreach program

Much of the literature concerned with evaluating public and private schooling focuses upon year 12 examination results. Investigating the transition to university, some studies have compared these results with first-year university marks. Very few researchers, however, have looked beyond students’ marks. This paper examines how “school type” affects student performance, participation, and experience in a university outreach program – SmARTS. SmARTS is run through The University of Western Australia’s (UWA) Faculty of Arts, Humanities, and Social Sciences (FAHSS). It engages year 11 students in a six-month research project, facilitated by the use of both e-learning and more traditional face-to-face methods. This paper is based on research that evaluated the 2009, 2010, and 2011 programs. The methods employed include analyses of student completion rates and results, as well as 198 student surveys, ten school coordinator surveys, and three group interviews with tutors. Based on schools’ socio-economic backgrounds, fees, and examination results, we have divided schools into four types: top-tier private, second-tier private, top-tier public, and second-tier public. Our findings suggest that top-tier private and top-tier public school students have the highest levels of participation, the lowest drop-out rates, and gain the highest results in SmARTS, while the opposite is evident for second-tier public school students. We also found, however, that second-tier public school students reported to have gained more generic skills from the program than did other groups. Our findings suggest that analysing examination results provides only a limited picture of how students experience the transition to university. We argue that through research and practice such as ours, inequalities can be more accurately measured, and thus minimised, before students enter university

Does the presence of a trained support person during labor decrease C-section rates?

Q: Does the presence of a trained support person during labor decrease C-section rates? Evidence-based answer: sometimes. The continuous presence of a support person during labor slightly decreases (by about 2%) the likelihood of a cesarean section (C-section) but only when companions can't be present and epidurals aren't routine (strength of recommendation [SOR]: A, a well-done systematic review of randomized controlled trials [RCTs]). When the support person was neither hospital staff nor a member of the woman's social network, C-section was significantly less likely (SOR A, a well-done systematic review of RCTs)

Repression of CIITA by the Epstein-Barr virus transcription factor Zta is independent of its dimerization and DNA binding

Repression of the cellular CIITA gene is part of the immune evasion strategy of the γherpes virus Epstein-Barr virus (EBV) during its lytic replication cycle in B-cells. In part this is mediated through down regulation of MHC class II gene expression via the targeted repression of CIITA, the cellular master regulator of MHC class II gene expression. The repression is achieved through a reduction in CIITA promoter activity initiated by the EBV transcription and replication factor Zta (BZLF1, EB1, ZEBRA). Zta is the earliest gene expressed during the lytic replication cycle. Zta interacts with sequence specific elements in promoters, enhancers and the replication origin (ZREs) and also modulates gene expression through interaction with cellular transcription factors and co-activators. Here we explore the requirements for Zta-mediated repression of the CIITA promoter. We find that repression by Zta is specific for the CIITA promoter and can be achieved in the absence of other EBV genes. Surprisingly, we find that the dimerization region of Zta is not required to mediate repression. This contrasts with an obligate requirement of this region to correctly orientate the DNA contact regions of Zta to mediate activation of gene expression through ZREs. Additional support for the model that Zta represses the CIITA promoter without direct DNA binding comes from promoter mapping that shows that repression does not require the presence of a ZRE in the CIITA promoter

Plain Tobacco Packaging: A Systematic Review

(From the Executive Summary): This systematic review outlines findings from 37 studies that provide evidence of the impacts of plain tobacco packaging. The review was conducted following the publication of the March 2011 White Paper Healthy Lives: Healthy People which set out a renewed Tobacco Control Plan for England. One of the key actions identified in the plan was to consult on possible options to reduce the promotional impact of tobacco packaging, including plain packaging. This systematic review was commissioned to provide a comprehensive overview of evidence on the impact of plain packaging in order to inform a public consultation on the issue

How does perceived risk mediate associations between perceived safety and parental restriction of adolescents\u27 physical activity in their neighborhood?

BackgroundThere is evidence that adolescence is a critical period of decline in physical activity. However, adolescents may have limited opportunities to be physically active outdoors if their parents are concerned about neighborhood safety and restrict their adolescent&rsquo;s physical activity within their neighborhood. Pathways that lead to parental restriction of adolescents&rsquo; physical activity (constrained behavior) are under-researched. This study aimed to examine perceived risk as a potential mediator of associations between perceived safety/victimization and constrained behavior.MethodsCross-sectional study of adolescents (43% boys) aged 15&ndash;17&thinsp;years (n&thinsp;=&thinsp;270) in Melbourne, Australia. Parents reported perceived safety (road safety, incivilities and personal safety) and prior victimization in their neighborhood, perceived risk of their children being harmed and whether they constrained their adolescent&rsquo;s physical activity. Constrained behavior was categorized as &lsquo;avoidance&rsquo; or &lsquo;defensive&rsquo; behavior depending on a whether physical activity was avoided or modified, respectively, due to perceived risk. MacKinnon&rsquo;s product-of-coefficients test of mediation was used to assess potential mediating pathways between perceived safety/victimization and constrained behavior.ResultsFor girls only, perceived risk was a significant mediator of associations between perceived road safety and avoidance/defensive behavior, and between perceived incivilities, perceived personal safety, victimization and defensive behavior.ConclusionsAssociations between perceived safety/victimization and constrained behavior are complex. Findings may guide the design of interventions that aim to improve actual and perceived levels of safety and reduce perceptions of risk. This is of particular importance for adolescent girls among whom low and declining levels of physical activity have been observed worldwide.<br /