Fission-induced plasmas

The possibility of creating a plasma from fission fragments, and to utilize the energy of the particles to create population inversion that would lead to laser action is investigated. An investigation was made of various laser materials which could be used for nuclear-pumped lasing. The most likely candidate for a fissioning material in the gaseous form is uranium hexafluoride - UF6, and experiments were performed to investigate materials that would be compatible with it. One of the central problems in understanding a fission-induced plasma is to obtain a model of the electron behavior, and some preliminary calculations are presented. In particular, the rates of various processes are discussed. A simple intuitive model of the electron energy distribution function is also shown. The results were useful for considering a mathematical model of a nuclear-pumped laser. Next a theoretical model of a (3)He-Ar nuclear-pumped laser is presented. The theory showed good qualitative agreement with the experimental results

Impurity-induced frustration in correlated oxides

Using the example of Zn-doped La2CuO4, we demonstrate that a spinless impurity doped into a non-frustrated antiferromagnet can induce substantial frustrating interactions among the spins surrounding it. This counterintuitive result is the key to resolving discrepancies between experimental data and earlier theories. Analytic and quantum Monte Carlo studies of the impurity-induced frustration are in a close accord with each other and experiments. The mechanism proposed here should be common to other correlated oxides as well.Comment: 4 pages, updated figures, accepted versio

Risk Theory with the Gamma Process

The aggregate claims process is modelled by a process with independent, stationary and nonnegative increments. Such a process is either compound Poisson or else a process with an infinite number of claims in each time interval, for example a gamma process. It is shown how classical risk theory, and in particular ruin theory, can be adapted to this model. A detailed analysis is given for the gamma process, for which tabulated values of the probability of ruin are provide

In-Flight Flow Visualization Using Infrared Thermography

The feasibility of remote infrared thermography of aircraft surfaces during flight to visualize the extent of laminar flow on a target aircraft has been examined. In general, it was determined that such thermograms can be taken successfully using an existing airplane/thermography system (NASA Dryden's F-18 with infrared imaging pod) and that the transition pattern and, thus, the extent of laminar flow can be extracted from these thermograms. Depending on the in-flight distance between the F-18 and the target aircraft, the thermograms can have a spatial resolution of as little as 0.1 inches. The field of view provided by the present remote system is superior to that of prior stationary infrared thermography systems mounted in the fuselage or vertical tail of a subject aircraft. An additional advantage of the present experimental technique is that the target aircraft requires no or minimal modifications. An image processing procedure was developed which improves the signal-to-noise ratio of the thermograms. Problems encountered during the analog recording of the thermograms (banding of video images) made it impossible to evaluate the adequacy of the present imaging system and image processing procedure to detect transition on untreated metal surfaces. The high reflectance, high thermal difussivity, and low emittance of metal surfaces tend to degrade the images to an extent that it is very difficult to extract transition information from them. The application of a thin (0.005 inches) self-adhesive insulating film to the surface is shown to solve this problem satisfactorily. In addition to the problem of infrared based transition detection on untreated metal surfaces, future flight tests will also concentrate on the visualization of other flow phenomena such as flow separation and reattachment

An exploration of the pedagogies employed to integrate knowledge in work-integrated learning

This article describes a three‐sector, national research project that investigated the integration aspect of work‐integrated learning (WIL). The context for this study is three sectors of New Zealand higher education: business and management, sport, and science and engineering, and a cohort of higher educational institutions that offer WIL/cooperative education in variety of ways. The aims of this study were to investigate the pedagogical approaches in WIL programs that are currently used by WIL practitioners in terms of learning, and the integration of academic‐workplace learning. The research constituted a series of collective case studies, and there were two main data sources — interviews with three stakeholder groups (namely employers, students, and co‐op practitioners), and analyses of relevant documentation (e.g., course/paper outlines, assignments on reflective practice, portfolio of learning, etc.). The research findings suggest that there is no consistent mechanism by which placement coordinators, off‐campus supervisors, or mentors seek to employ or develop pedagogies to foster learning and the integration of knowledge. Learning, it seems, occurs by means of legitimate peripheral participation with off‐campus learning occurring as a result of students working alongside professionals in their area via an apprenticeship model of learning. There is no evidence of explicit attempts to integrate on‐ and off‐campus learning, although all parties felt this would and should occur. However, integration is implicitly or indirectly fostered by a variety of means such as the use of reflective journals

What Evangelical Pastors Want to Know about Psychology

Increasing attention has been given to psychologist-clergy collaboration in mainstream psychology journals, yet much remains to be considered regarding how these collaborative relationships will benefit the work of pastors and Christian congregations. The purpose of this research was to evaluate clergy perspectives regarding what psychologists can offer to facilitate the ministry of the church. Various methods of assessment were used, including a survey of evangelical pastors, responses to an open-ended question via electronic mail and in person, and a focus group of Christian mental health practitioners. Respondents indicated an interest in the relationship of sin and psychological disorder, interventions particularly related to marriage and family counseling, understanding of diverse personalities in dealing with church conflict, understanding of psychological disorders, and methods of caring for their personal needs as pastors. Recommendations are offered for those interested in collaborating with clergy

Finite Element Modeling of Binary Acoustic Fresnel Lenses

Binary acoustic Fresnel lenses (BAFLs) have recently emerged as possible replacements for spherical lenses for applications in acoustic microscopy. BAFLs are surface relief structures that are relatively easy to manufacture compared to conventional spherical lenses. While the latter requires careful grinding and polishing, the former can be easily fabricated to sub-micron dimension accuracy using existing VLSI etching technology. The term binary arises from the fact that each masking step during the lens production creates two phase levels. Therefore, a total of 2 n phase levels are created in n masking etching steps. A special case is when n = 1 (2 phase levels), which corresponds to the conventional Fresnel lens (zone plate)

Soft case-based reasoning

Author name used in this publication: Simon ShiuVersion of RecordPublishe