CHOOSING ALTERNATIVES TO CONTAMINATED GROUND WATER SUPPLIES: A SEQUENTIAL DECISION FRAMEWORK UNDER UNCERTAINTY

In increasing numbers, communities that rely on groundwater for drinking supplies have discovered contamination from agricultural pesticides and herbicides, road salt, underground fuel storage, and septic systems. A variety of short- and long-run remedies are available with highly uncertain outcomes. An appropriate technique for solving a benefit-cost problem of this type is a sequential decision framework using stochastic dynamic programming procedures for solution. The approach is illustrated here by means of an application to the problem of the recent contamination of the groundwater of Whately, Massachusetts by the agricultural fumigant EDB and the pesticide aldicarb.Environmental Economics and Policy,

Nd:YAG development for spaceborne laser ranging system

The results of the development of a unique modelocked laser device to be utilized in future NASA space-based, ultraprecision laser ranger systems are summarized. The engineering breadboard constructed proved the feasibility of the pump-pulsed, actively modelocked, PTM Q-switched Nd:YAG laser concept for the generation of subnanosecond pulses suitable for ultra-precision ranging. The laser breadboard also included a double-pass Nd:YAG amplifier and provision for a Type II KD*P frequency doubler. The specific technical accomplishment was the generation of single 150 psec, 20-mJ pulses at 10 pps at a wavelength of 1.064 micrometers with 25 dB suppression of pre-and post-pulses

Propagation of the First Flames in Type Ia Supernovae

We consider the competition of the different physical processes that can affect the evolution of a flame bubble in a Type Ia supernovae -- burning, turbulence and buoyancy. Even in the vigorously turbulent conditions of a convecting white dwarf, thermonuclear burning that begins at a point near the center (within 100 km) of the star is dominated by the spherical laminar expansion of the flame, until the burning region reaches kilometers in size. Consequently flames that ignite in the inner ~20 km promptly burn through the center, and flame bubbles anywhere must grow quite large--indeed, resolvable by large-scale simulations of the global system--for significant motion or deformation occur. As a result, any hot-spot that successfully ignites into a flame can burn a significant amount of white dwarf material. This potentially increases the stochastic nature of the explosion compared to a scenario where a simmering progenitor can have small early hot-spots float harmlessly away. Further, the size where the laminar flame speed dominates other relevant velocities sets a characteristic scale for fragmentation of larger flame structures, as nothing--by definition--can easily break the burning region into smaller volumes. This makes possible the development of semi-analytic descriptions of the earliest phase of the propagation of burning in a Type Ia supernovae, which we present here. Our analysis is supported by fully resolved numerical simulations of flame bubbles.Comment: 33 pages, 14 figures, accepted for publication in Ap

ePortfolios: Mediating the minefield of inherent risks and tensions

The ePortfolio Project at the Queensland University of Technology (QUT) exemplifies an innovative and flexible harnessing of current portfolio thinking and design that has achieved substantial buy-in across the institution with over 23000 active portfolios. Robust infrastructure support, curriculum integration and training have facilitated widespread take-up, while QUT’s early adoption of ePortfolio technology has enabled the concomitant development of a strong policy and systems approach to deal explicitly with legal and design responsibilities. In the light of that experience, this paper will highlight the risks and tensions inherent in ePortfolio policy, design and implementation. In many ways, both the strengths and weaknesses of ePortfolios lie in their ability to be accessed by a wider, less secure audience – either internally (e.g. other students and staff) or externally (e.g. potential employees and referees). How do we balance the obvious requirement to safeguard students from the potential for institutionally-facilitated cyber-harm and privacy breaches, with this generation’s instinctive personal and professional desires for reflections, private details, information and intellectual property to be available freely and with minimal restriction? How can we promote collaboration and freeform expression in the blog and wiki world but also manage the institutional risk that unauthorised use of student information and work so palpably carries with it? For ePortfolios to flourish and to develop and for students to remain engaged in current reflective processes, holistic guidelines and sensible boundaries are required to help safeguard personal details and journaling without overly restricting students’ emotional, collaborative and creative engagement with the ePortfolio experience. This paper will discuss such issues and suggest possible ways forward

Efficacy of a Workbook to Promote Forgiveness: A Randomized Controlled Trial with University Students

Objective The present study investigated the efficacy of a 6-hour self-directed workbook adapted from the REACH Forgiveness intervention. Method Undergraduates (N = 41) were randomly assigned to either an immediate treatment or waitlist control condition. Participants were assessed across 3 time periods using a variety of forgiveness outcome measures. Results The 6-hour workbook intervention increased forgiveness, as indicated by positive changes in participants’ forgiveness ratings that differed by condition. In addition, benchmarking analysis showed that the self-directed workbook intervention is at least as efficacious as the delivery of the REACH Forgiveness model via group therapy. Conclusion A self-directed workbook intervention adapted from the REACH Forgiveness intervention provides an adjunct to traditional psychotherapy that could assist the mental health community to manage the burden of unforgiveness among victims of interpersonal harm

Generators of simple Lie algebras in arbitrary characteristics

In this paper we study the minimal number of generators for simple Lie algebras in characteristic 0 or p > 3. We show that any such algebra can be generated by 2 elements. We also examine the 'one and a half generation' property, i.e. when every non-zero element can be completed to a generating pair. We show that classical simple algebras have this property, and that the only simple Cartan type algebras of type W which have this property are the Zassenhaus algebras.Comment: 26 pages, final version, to appear in Math. Z. Main improvements and corrections in Section 4.

Esthetic and Recreational Potential of Small Naturalistic Streams Near Urban Areas

The purpose of this study was to find a way to evaluate the esthetic and recreational potential of small streams and their watersheds. Research was limited to naturalistic streams with drainage areas under 100 square miles and located within 25 miles of a city. A methodology, based on some previous work of the U.S. Soil Conservation Service and the principles or concepts of terrain analysis, land use planning, value Judgment philosophy and the economics of outdoor recreation, was developed and applied in detail to two streams (Boone and Jessamine Creeks) near Lexington, Kentucky. Evaluations were made of the streams\u27 potential for camping (primitive, transient and group), fishing, picnicking, a trail system (hiking, horseback riding, bicycling and auto tour routes), esthetic enjoyment (sightseeing, nature walks and walking for pleasure) and the establishment of natural, scenic and historic areas, Limited applications were also made to two other watersheds and to selected recreation sites on Boone and Jessamine Creeks. Extensions of these case studies resulted in procedures for estimating: visitation to a developed site, future participation demand generated by an urban area and the proportion of that demand that would be satisfied at a specific site, and the economic benefits that would accrue if the sites were developed. Conclusions reached were: (1) Esthetic and recreational values can be identified, inventoried and used to evaluate a watershed\u27s development potential. (2) The methodology yielded fairly accurate evaluations for most of the recreational activities considered. (3) The case studies revealed that many small stream areas possess medium to high potential for camping, fishing, picnicking, trail system development and some forms of esthetic enjoyment. (4) Visitation estimates were judged to be only approximate due to lack of relevant data on similar existing recreation areas. Estimates of participation demand, acreage requirements and annual benefits were somewhat more reliable. Suggestions for further research include: (1) Additional applications of the evaluation methodology to streams in other Kentucky urban areas and in states having climatic, topographic and socio-economic conditions different from Kentucky\u27s and (2) A feasibility study of the use of a psychometrics approach to determine personal preferences about outdoor recreation and the preservation of natural areas