A Christmas hymn by Martin Luther

From heaven above\u27

Discrete ordinates-Monte Carlo coupling: A comparison of techniques in NERVA radiation analysis

In the radiation analysis of the NERVA nuclear rocket system, two-dimensional discrete ordinates calculations are sufficient to provide detail in the pressure vessel and reactor assembly. Other parts of the system, however, require three-dimensional Monte Carlo analyses. To use these two methods in a single analysis, a means of coupling was developed whereby the results of a discrete ordinates calculation can be used to produce source data for a Monte Carlo calculation. Several techniques for producing source detail were investigated. Results of calculations on the NERVA system are compared and limitations and advantages of the coupling techniques discussed

Getting Potomac Fever: Increasing Civic Engagement Through Experiential Learning Communities

Drawing upon the literature on experiential learning, learning communities, and the scholarship of civic engagement, this paper assesses the outcomes of the Washington D.C. Summer Study Program developed by the College of St Benedict and St. John’s University. We are especially interested in examining the extent to which students who undertake this two month, eight credit internship learning community experience engage with politics and political life. Do students learn more about the US political system, its operation and opportunities? Are they more enthusiastic about public policy and politics? Do they increase their level of trust in government or their feelings of efficacy? In addition to these questions, we examine what the students’ experiences mean for them in terms of the integration of past and future course material, and how students use these experiences to examine their career goals, to develop their own career path, and to learn to live and work independently and responsibly in an urban setting. Data gathered from a survey of the program’s interns is compared with an initial survey of 200 students who have not yet undertaken internships either inside or outside a learning community model, as well as data from interviews with students, site supervisors, and faculty, and student archival data from the three decades old program. The study demonstrates that while there are numerous tradeoffs and costs, internships embedded within a learning community create unique benefits not available to the more isolated individual internship model

Quantization of the First-Order Two-Dimensional Einstein-Hilbert Action

A canonical analysis of the first-order two-dimensional Einstein-Hilbert action has shown it to have no physical degrees of freedom and to possess an unusual gauge symmetry with a symmetric field $\xi_{\mu\nu}$ acting as a gauge function. Some consequences of this symmetry are explored. The action is quantized and it is shown that all loop diagrams beyond one-loop order vanish. Furthermore, explicit calculation of the one-loop two-point function shows that it too vanishes, with the contribution of the ghost loop cancelling that of the ``graviton'' loop

Functional programming and the logical variable

Disponible dans les fichiers attachés à ce documen

Long-term behavior of energetic inner-belt protons

Long term behavior of energetic inner-belt proton

Preventing type 2 diabetes mellitus in Qatar by reducing obesity, smoking, and physical inactivity: mathematical modeling analyses.

BACKGROUND: The aim of this study was to estimate the impact of reducing the prevalence of obesity, smoking, and physical inactivity, and introducing physical activity as an explicit intervention, on the burden of type 2 diabetes mellitus (T2DM), using Qatar as an example. METHODS: A population-level mathematical model was adapted and expanded. The model was stratified by sex, age group, risk factor status, T2DM status, and intervention status, and parameterized by nationally representative data. Modeled interventions were introduced in 2016, reached targeted level by 2031, and then maintained up to 2050. Diverse intervention scenarios were assessed and compared with a counter-factual no intervention baseline scenario. RESULTS: T2DM prevalence increased from 16.7% in 2016 to 24.0% in 2050 in the baseline scenario. By 2050, through halting the rise or reducing obesity prevalence by 10-50%, T2DM prevalence was reduced by 7.8-33.7%, incidence by 8.4-38.9%, and related deaths by 2.1-13.2%. For smoking, through halting the rise or reducing smoking prevalence by 10-50%, T2DM prevalence was reduced by 0.5-2.8%, incidence by 0.5-3.2%, and related deaths by 0.1-0.7%. For physical inactivity, through halting the rise or reducing physical inactivity prevalence by 10-50%, T2DM prevalence was reduced by 0.5-6.9%, incidence by 0.5-7.9%, and related deaths by 0.2-2.8%. Introduction of physical activity with varying intensity at 25% coverage reduced T2DM prevalence by 3.3-9.2%, incidence by 4.2-11.5%, and related deaths by 1.9-5.2%. CONCLUSIONS: Major reductions in T2DM incidence could be accomplished by reducing obesity, while modest reductions could be accomplished by reducing smoking and physical inactivity, or by introducing physical activity as an intervention