Chaotic motion in pp-wave spacetimes

We investigate geodesics in non-homogeneous vacuum pp-wave solutions and demonstrate their chaotic behavior by rigorous analytic and numerical methods. For the particular class of solutions considered, distinct "outcomes" (channels to infinity) are identified, and it is shown that the boundary between different outcomes has a fractal structure. This seems to be the first example of chaos in exact radiative spacetimes.Comment: 15 pages (latex),12 figures (gif), to appear in Class. Quantum Gra

Striving for Teaching Success: Enhancing Emotional Intelligence in Pre-Service Teachers

Research has confirmed job dissatisfaction, and high levels of occupational stress and burnout resulting from the emotional demands of teaching. This dissertation focuses on a potential solution to support teachers’ psychological wellbeing in their paramount role to society: training in emotional intelligence. Recent research has demonstrated not only the positive role of emotional intelligence (EI) in enhancing stress management, coping skills, psychological wellbeing, and resilience, but that EI can be developed through EI training. Empirical evidence has recently shown support for EI training specifically within the teaching population. However, there remains a dearth of applicable empirically-based training programs aimed at effectively helping to manage teacher stress in the classroom. Building upon the success that EI training programs have had in a range of populations, the present research focused not only on the evaluation of one specific program, but also sought further understanding regarding the mechanisms through which EI influences positive outcomes. The current work follows the administration of three rounds of one such program, Managing Occupational Stress Through the Development of Emotional Intelligence (Gardner, Stough, & Hansen, 2008) to a group of pre-service teachers. These studies provide a comprehensive, theory-driven evaluation of: 1) the short-term and intermediate outcomes and 2) the implementation and processes with slight modifications of this program between training sessions. The nature of the mixed-method evaluation design involved both quantitative and qualitative analyses of each training component to examine the assumptions underlying service delivery and processes. It also allowed for a more direct exploration of causal effects. Results indicated not only that EI improves compared to controls post-program and at follow-up (1- and 6-month), but also that stress indicators decrease coincidental with an increase in adaptive coping and teacher efficacy. Finally, the assessment of participant responses, comprehension, skills application, and feedback offers a critical understanding regarding how EI impacts outcomes along with insight regarding the agents of change that may drive learning and application processes

Child Care and Development Fund: A Policy Analysis

Legislated as part of welfare reform, the Child Care and Development Fund (CCDF) is the main source of child care government funding earmarked for low-income families. As a block grant, with broad federal guidelines, states have significant freedom in implementing this legislation to meet the needs of their citizens. This diverse implementation has challenged legislators and scholars trying to assess the success of CCDF across the United States. In considering the evaluation research of CCDF, as well as the original goals of this legislation, several major themes related to the diverse state implementation emerged, including access, equity, and stability. This paper provides an overview of CCDF, explains these themes, and uses the 2002 third wave of National Survey of American Families (NSAF) data to demonstrate how policy analysts and researchers might use these themes to structure comprehensive evaluations of CCDF at both state and federal levels

Disparity in outcomes of melanoma adjuvant immunotherapy by demographic profile

Background: Randomized comparisons have demonstrated survival benefit of adjuvant immunotherapy in node-positivemelanoma patients but have limited power to determine if this benefit persists across various demographic factors. Materials & methods: We assessed the impact of demographic factors on the survival benefit of adjuvant immunotherapy in a database of 38,189 node-positive melanoma patients using the Kaplan–Meier method and Cox proportional hazards models. Results: All assessed demographic factors other than race significantly impacted survival of node-positive melanoma patients in univariate analysis. In multivariable analysis, only the age group interacted with immunotherapy. Conclusion: Analysis of this large database of unselected node-positive melanoma patients demonstrated a positive survival benefit of immunotherapy across all demographic factors assessed and the impact was greater for patients 65 years of age and older

Proton fraction in the inner neutron-star crust

Monte Carlo simulations of neutron-rich matter of relevance to the inner neutron-star crust are performed for a system of A=5,000 nucleons. To determine the proton fraction in the inner crust, numerical simulations are carried out for a variety of densities and proton fractions. We conclude---as others have before us using different techniques---that the proton fraction in the inner stellar crust is very small. Given that the purported "nuclear pasta" phase in stellar crusts develops as a consequence of the long-range Coulomb interaction among protons, we question whether pasta formation is possible in such proton-poor environments. To answer this question, we search for physical observables sensitive to the transition between spherical nuclei and exotic pasta structures. Of particular relevance is the static structure factor S(k)---an observable sensitive to density fluctuations. However, no dramatic behavior was observed in S(k). We regard the identification of physical observables sensitive to the existence---or lack-thereof---of a pasta phase in proton-poor environments as an open problem of critical importance.Comment: 24 pages and 7 figure

Virtues and Flaws of the Pauli Potential

Quantum simulations of complex fermionic systems suffer from a variety of challenging problems. In an effort to circumvent these challenges, simpler ``semi-classical'' approaches have been used to mimic fermionic correlations through a fictitious ``Pauli potential''. In this contribution we examine two issues. First, we address some of the inherent difficulties in a widely used version of the Pauli potential. Second, we refine such a potential in a manner consistent with the most basic properties of a cold Fermi gas, such as its momentum distribution and its two-body correlation function.Comment: 16 pages, 6 figure