Semiconductor cooling by thin-film thermocouples

Thin-film, metal alloy thermocouple junctions do not rectify, change circuit impedance only slightly, and require very little increase in space. Although they are less efficient cooling devices than semiconductor junctions, they may be applied to assist conventional cooling techniques for electronic devices

Memory performance of and-parallel prolog on shared-memory architectures

The goal of the RAP-WAM AND-parallel Prolog abstract architecture is to provide inference speeds significantly beyond those of sequential systems, while supporting Prolog semantics and preserving sequential performance and storage efficiency. This paper presents simulation results supporting these claims with special emphasis on memory performance on a two-level sharedmemory multiprocessor organization. Several solutions to the cache coherency problem are analyzed. It is shown that RAP-WAM offers good locality and storage efficiency and that it can effectively take advantage of broadcast caches. It is argued that speeds in excess of 2 ML IPS on real applications exhibiting medium parallelism can be attained with current technology

The StarLink Case: Issues for the Future

The disclosure in September 2000 that StarLink corn had been found in the human food supply putfood biotechnology in the public spotlight and caused concern among consumers and food systemstakeholders alike that a product approved only for animal use could find its way to grocery shelves. TheStarLink experience raises a number of issues that deserve study concerning the current regulatory systemand public policies affecting genetically modified foods. The issues include how to manage allergenicityissues posed by biotech foods at the approval stage. Most of the issues, however, involve post-approvalcontrol of staple food crops that have been genetically modified. It may be increasingly important in thefuture to maintain the identity of genetically modified crops and segregate them from conventional ones,yet neither the grain trading system nor the government regulatory system were designed to ensure this.This paper is the first step in a case study that Resources for the Future is conducting for the PewInitiative on Food and Biotechnology to identify and analyze the regulatory and public policy issuesraised by the StarLink episode. In this paper, we pose questions concerning the adequacy of curent legalauthority, regulatory procedures, and institutional arrangements for post-approval control of biotech foodsthat we intend to analyze in depth during the balance of the study based on interviews and other research.We welcome comment on this paper and the planned study.agricultural biotechnology, food allergens, food regulation, food safety, genetically modified food, grain trading system, StarLinkTM corn

Technological Change and Gender Wage Differentials

This paper investigates the impact of non-neutral technological change on the recent narrowing of the gender wage differentials. The relation between technological change and relative wages of female and male workers is modeled through a constant elasticity of substitution production function that incorporates male and female labor inputs by occupation in each industry, a non-labor input and a productivity parameter function that captures non-neutral technological change. Data from 1979 to 2001 on employment and wages by industry and occupation come from the Current Population Survey. Using non-linear two stage least squares with cross-equation restrictions, the estimated results provide evidence that non-neutral technological change partially explains the documented narrowing of the gender wage gap during the 1980s and 1990s, even after controlling for unexplained differences in gender relative wages. Specifically, changes in non-neutral technological change explain between 5 % and 9 % of the overall increase of women’s wages relative to men’s in the sample. The strongest effect is found for the highest pay occupation level, while the smallest effect is found for the lower pay occupations. Finally, this paper brings evidence that ignoring the unexplained component of the gender wage differentials could result in a biased estimation of the effect on non-neutral technological change on the gender wage gap.

Bayesian approach to image reconstruction in photoacoustic tomography

Photoacoustic tomography is a hybrid imaging method that has a variety of biomedical applications. In photoacoustic tomography, the image reconstruction problem (inverse problem) is to resolve the initial pressure distribution from detected ultrasound waves generated within an object due to an illumination of a short light pulse. In this work, this problem is approached in Bayesian framework. Image reconstruction is investigated with numerical simulations in different detector geometries, including limited view setup, and utilizing different prior information. Furthermore, assessing the reliability of the estimates is investigated. The simulations show that the Bayesian approach can produce accurate estimates of the initial pressure distribution and uncertainty information even in a limited view setup if proper prior information is utilized

Three dimensional photograph of single electron tracks through a scintillator

The reconstruction of particle trajectories makes it possible to distinguish between different types of charged particles. In high-energy physics, where trajectories are rather long, large size trackers must be used to achieve sufficient position resolution. However, in low-background experiments tracks are rather short and three dimensional trajectories could only be resolved in time-projection chambers so far. For detectors of large volume and therefore large drift distances, which are inevitable for low-background experiments, this technique is limited by diffusion of charge carriers. In this work we present a "proof-of-principle" experiment for a new method for the three dimensional tracking of charged particles by scintillation light: We used a setup consisting of a scintillator, mirrors, lenses and a novel imaging device (the hybrid photo detector) in order to image two projections of electron tracks through the scintillator. We took data at the T-24 beam-line at DESY with relativistic electrons with a kinetic energy of 5 GeV and from this data successfully reconstructed their three dimensional propagetion path in the scintillator. With our setup we achieved a position resolution of about 28 mum in the best case.Comment: 9 pages, 13 figures, 1 tabl

Identifying the Most Significant Microbiological Foodborne Hazards to Public Health: A New Risk Ranking Model

In order to help facilitate a risk-based food safety system, we developed the Foodborne Illness Risk Ranking Model (FIRRM), a decisionmaking tool that quantifies and compares the relative burden to society of 28 foodborne pathogens. FIRRM estimates the annual number of cases, hospitalizations, and fatalities caused by each foodborne pathogen, subsequently estimates the economic costs and QALY losses of these illnesses, and, lastly, attributes these pathogen-specific illnesses and costs to categories of food vehicles, based on outbreak data and expert judgment. The model ranks pathogen-food combinations according to five measures of societal burden. FIRRM incorporates probabilistic uncertainty within a Monte Carlo simulation framework and produces confidence intervals and statistics for all outputs. Gaps in data, most importantly in regards to food attribution and the statistical uncertainty of incidence estimates, currently limit the utility of the model. Once we address these and other problems, however, FIRRM will be a robust and useful decisionmaking tool.foodborne illness, risk ranking, pathogens, health valuation, QALYs, cost of illness, uncertainty, modeling, Monte Carlo

Questionnaire design and data analysis: An alternative approach in student evaluation of teaching (SET)

Student evaluation of teaching (SET) has been widely used in institutions of learning to assess teaching effectiveness. However, most of the SET questionnaires are designed by “experts” without taking students’ view into consideration. Besides that, the traditional approach in SET analysis is to obtain a global rating as a measurement of teaching effectiveness based on the average or mean scores of the items of SET. This paper identifies the weaknesses of the traditional approach in SET questionnaire development and data analysis. It then describes an alternative approach to SET items development which involved students- collaboration. The paper also describes the establishment of various scoring matrices for the measurement of overall teaching effectiveness as well as teaching effectiveness from three different domains, namely: knowledge, pedagogical skills and attitud

Detection of non-classical space-time correlations with a novel type of single-photon camera

During the last decades, multi-pixel detectors have been developed capable of registering single photons. The newly developed Hybrid Photon Detector camera has a remarkable property that it has not only spatial but also temporal resolution. In this work, we use this device for the detection of non-classical light from spontaneous parametric down-conversion and use two-photon correlations for the absolute calibration of its quantum efficiency