Recent results on GaAs detectors - 137

The present understanding of the charge collection in GaAs detectors with respect to the materials used and its processing are discussed. The radiation induced degradation of the charge collection efficiency and the leakage current of the detectors are summarised. The status of strip and pixel detectors for the ATLAS experiment are reported along with the latest results from GaAs X-ray detectors for non-high energy physics applications.Comment: 7 pages. 4 postscript figures + 1 postscript preprint logo + 1 LaTeX file + 1 style file. Also available at http://ppewww.ph.gla.ac.uk/preprints/97/05

A Note on the International Coffee Agreement

This research note develops a model of the institutional features of the international coffee agreement and analyzes the allocation of export quotas under the terms of the agreement in 1982. It suggests that the agreement can be viewed as a weighted majority voting game. It employs the assumption of rationality to predict how allocations should be made given the rules of the agreement and tests the model by determining whether the allocations which passed (failed) fell within (outside) of the solution of the game

Political Power in the International Coffee Organization: A Research Note

In recent decades, international commodity agreements have been proposed as a way of promoting “development." Behrman, McNicol and others have analyzed them from a purely economic point of view. Fisher, Krasner, and others have adopted a more political perspective. In this article, we seek to advance the political analysis of such agreements. We do so by studying the allocation of export entitlements in the International Coffee Organization (ICO). In the ICO, as in other international organizations, political processes replace markets in the allocation of source resources. In the case of the ICO, allocational decisions are made by majority rule. Given the possibility of strategic behavior in such political environments, game theory should provide a useful set of tools for the analysis of such institutions. A particular interest of this article is the appropriateness of a specific solution concept--the Shapley value--to the analysis of politically contrived allocations under the ICO

Validation of a survey tool for use in cross-cultural studies

There is a need for tools to measure the information patients need in order for healthcare professionals in general, and particularly pharmacists, to communicate effectively and play an active part in the way patients manage their medicines. Previous research has developed and validated constructs to measure patients’ desires for information and their perceptions of how useful their medicines are. It is important to develop these tools for use in different settings and countries so that best practice is shared and is based on the best available evidence. Objectives: this project sought to validate of a survey tool measuring the “Extent of Information Desired” (EID), the “Perceived Utility of Medicines” (PUM), and the “Anxiety about Illness” (AI) that had been previously translated for use with Portuguese patients. Methods: The scales were validated in a patient sample of 596: construct validity was explored in Factor analysis (PCA) and internal consistency analysed using Cronbach’s alpha. Criterion validity was explored correlating scores to the AI scale and patients’ perceived health status. Discriminatory power was assessed using ANOVA. Temporal stability was explored in a sub-sample of patients who responded at two time points, using a T-test to compare their mean scores. Results: Construct validity results indicated the need to remove 1 item from the Perceived Harm of Medicines (PHM) and Perceived Benefit of Medicines (PBM) for use in a Portuguese sample and the abandon of the tolerance scale. The internal consistency was high for the EID, PBM and AI scales (alpha>0.600) and acceptable for the PHM scale (alpha=0.536). All scales, except the EID, were consistent over time (p>0.05; p<0.01). All the scales tested showed good discriminatory power. The comparison of the AI scale with the SF-36 indicated good criterion validity (p<0.05). Conclusion: The translated tool was valid and reliable in Portuguese patients- excluding the Tolerance scale. Some of the scales may benefit from further refinement, such as the PHM subscale

Preliminary Results for LP VPE X-Ray Detectors

Thick epitaxial layers have been grown using Low Pressure Vapour Phase Epitaxy techniques with low free carrier concentrations . This type of material is attractive as a medium for X-ray detection, because of its high conversion efficiency for X-rays in the medically interesting energy range.Comment: 4 pages. PS file only - original in WORD. Also available at http://ppewww.ph.gla.ac.uk/preprints/97/07

Establishing uncertainty ranges of hydrologic indices across climate and physiographic regions of the Congo River Basin

Study region The five drainage systems of the Congo River Basin in central Africa. Study focus This study aims to establish uncertainty ranges of hydrologic indices and to provide a basis for transferring hydrologic indices from gauged to ungauged sub-basins by identifying the most influential climate and physiographic attributes. New insights for this region Only limited information on individual sub-basins natural hydrology exists across the Congo River Basin, limiting the application of commonly used regionalization approaches for prediction in ungauged sub-basins. This study uses predictive equations for the hydrologic indices across all climate and physiographic regions based only on the aridity index. The degree of uncertainty in the derived uncertainty bounds is less than 41% for both Q10/MMQ and Q50/MMQ indices across the basin. A greater degree of uncertainty is associated with the runoff ratio and the Q90/MMQ indices. The uncertainty is assumed to be due to uncertainty in rainfall and evapotranspiration estimates, a lack of spatial representativeness of the available observed streamflow data and other factors (e.g., geology) that might control the hydrologic indices rather than the aridity index alone. The uncertainty ranges provide the first estimates of hydrologic indices that are intended to constrain the outputs from hydrologic models and appropriately quantify prediction uncertainty and risks associated with water resources decision making

Stochastic Cahn-Hilliard equation with singular nonlinearity and reflection

We consider a stochastic partial differential equation with logarithmic (or negative power) nonlinearity, with one reflection at 0 and with a constraint of conservation of the space average. The equation, driven by the derivative in space of a space-time white noise, contains a bi-Laplacian in the drift. The lack of the maximum principle for the bi-Laplacian generates difficulties for the classical penalization method, which uses a crucial monotonicity property. Being inspired by the works of Debussche and Zambotti, we use a method based on infinite dimensional equations, approximation by regular equations and convergence of the approximated semi-group. We obtain existence and uniqueness of solution for nonnegative intial conditions, results on the invariant measures, and on the reflection measures

On the geometric quantization of twisted Poisson manifolds

We study the geometric quantization process for twisted Poisson manifolds. First, we introduce the notion of Lichnerowicz-twisted Poisson cohomology for twisted Poisson manifolds and we use it in order to characterize their prequantization bundles and to establish their prequantization condition. Next, we introduce a polarization and we discuss the quantization problem. In each step, several examples are presented

On the Operations of the International Coffee Agreement

Next to oil, coffee is the most valuable commodity traded in world markets; it is produced in the developing world and consumed within the developed nations. Moreover, the International Coffee Agreement is the major successful international commodity agreement. In this research note we analyze the allocation of quotas to export coffee in 1982 under the terms of the agreement. The way in which entitlements to export are allocated offers insights into significant features of the international political economy.African and African American StudiesGovernmen