Double optic system for ion engine Patent

Accel and focus electrode design for ion engine with improved efficienc

Deterrence from self-protection measures in the ‘market model’ of crime: dynamic panel data estimates from employment in private security occupations

Private individuals and entities invest in a wide variety of market-provisioned self-protection devices or services to mitigate their probability of victimization to crime. However, evaluating the effect of such private security measures remains understudied in the economics of crime literature. Unlike most previous studies, the present analysis considers four separate measures of private security: security guards, detectives and investigators, security system installers, and locksmiths. The effects of laws allowing the concealed carrying of weapons (an unobservable precaution) are also evaluated. Given that Ehrlich’s ‘market model’ suggests private security is endogenous to crime, the analysis relies primarily on dynamic panel data methods to derive consistent parameter estimates of the effect of self-protection measures. The relationship between self-protection and UCR Part II Index offense (arrest) data are also considered in order to provide exploratory evidence on the interaction between publicly and privately provisioned crime deterrence efforts.Crime, Deterrence, Market model, Private Security, Self-protection

On the sustainability of collusion in Bertrand supergames with discrete pricing and nonlinear demand

In traditional industrial organization models of Bertrand supergames, the critical discount factor governing the sustainability of collusion is independent of key demand and supply parameters. Recent research has demonstrated that these counterintuitive results stem from the assumption that firms can change prices in infinitesimally small increments (i.e., continuously). This note considers the effects of demand curvature in the context of a model of collusion where, as in Gallice (2008), Bertrand competitors can deviate only by lowering prices by some small, discrete amount. Two alternative demand specifications that capture the influence of demand curvature are considered. In either case, it is shown that with discrete price changes the critical discount factor is determined by the key demand parameters, including demand curvature. However, the direct effects of increased concavity (or convexity) in market demand on the sustainability of collusion runs in opposite directions across the two models. This discrepancy is shown to arise from the way in which the respective demand curves rotate in response to a change in the demand curvature parameter. The results support the conclusion of earlier research that determining the potential for collusion in homogenous goods industries likely requires careful case-by-case investigation.Bertrand supergames; cartels; collusion sustainability; discrete pricing; nonlinear demand

The competitive impact of hypermarket retailers on gasoline prices

Hypermarkets are large retail suppliers of general merchandise or grocery items that also sell gasoline, often at very low margins. Using panel data for 1998-2002, this paper estimates the impact of hypermarkets on average state-level retail gasoline prices. The empirical results suggest a robust, economically (and statistically) significant effect of increased competition from hypermarkets. Furthermore, the results also suggest that refiners’ lower the delivered wholesale prices charged to their affiliated lessee-dealer and open-dealer stations in response to increased hypermarket competition, which in turn translates to lower retail (street) prices. The presence of a state motor fuel sales-below-cost (SBC) law may lessen the price-reducing effects from hypermarket competition by 40-67 percent while independently imparting no other offsetting price reductions. Finally, using recently published estimates of the short-run own price elasticity of demand for gasoline, consumer welfare is estimated to have increased in the neighborhood of $488 million over the sample period.Dealer tank wagon; Hypermarkets; Motor fuel SBC laws; Petroleum; Vertical integration

State executions, deterrence, and the incidence of murder

This study employs a panel of U.S. state-level data over the years 1978-1997 to estimate the deterrent effect of capital punishment. Particular attention is paid to problems of endogeneity bias arising from the non-random assignment of death penalty laws across states and a simultaneous relationship between murders and the deterrence probabilities. The primary innovation of the analysis lies in the estimation of a simultaneous equations system whose identification is based upon the employment of instrumental variables motivated by the theory of public choice. The estimation results suggest that structural estimates of the deterrent effect of capital punishment are likely to be downward biased due to the influence of simultaneity. Correcting for simultaneity, the estimates imply that a state execution deters approximately fourteen murders per year on average. Finally, the results also suggest that the announcement effect of capital punishment, as opposed to the existence of a death penalty provision, is the mechanism actually driving the deterrent effect associated with state executions.capital punishment, deterrence, executions, murder

Computer program conducts facilities utilization and occupancy survey

Computer program identifies the uses of all facilities and provides information on the net area in each room as well as the number and classification of people occupying them. The system also provides a means to indicate unsatisfactory work areas and may be able to be updated each month

Applications of aerospace technology in the public sector

Current activities of the program to accelerate specific applications of space related technology in major public sector problem areas are summarized for the period 1 June 1971 through 30 November 1971. An overview of NASA technology, technology applications, and supporting activities are presented. Specific technology applications in biomedicine are reported including cancer detection, treatment and research; cardiovascular diseases, diagnosis, and treatment; medical instrumentation; kidney function disorders, treatment, and research; and rehabilitation medicine

Experiences with Problem-Based Learning: Virginia Initiative for Science Teaching and Achievement

The Virginia Initiative for Science Teaching and Achievement (VISTA) provides high-quality professional development for teachers and administrators to enhance the quality of their science instructional programs. One emphasis of this program is helping teachers learn to implement Problem-Based Learning in the elementary science classroom. Problem-Based Learning (PBL) has the potential to produce significant positive outcomes for students, such as increased student engagement, and opportunities for in-depth critical thinking [1]. Teachers find PBL challenging because it does take additional time for planning and material acquisition, but experience has shown that the benefits outweigh these challenges. Setting clear goals, identifying specific learning objectives, and developing big questions that tie these together help increase the success of the unit. Additionally, administrators can help teachers succeed in implementing a Problem-Based Learning unit by understanding the dynamic nature of the PBL environment, providing flexibility with unit pacing, and setting aside time for refining, reflection, and revision of the unit

Thermally operated valve Patent

Gas valve operated by thermally expanding and contracting devic

Critical import supply elasticities and the ‘imports-as-market-discipline’ hypothesis

This paper formally examines the factors underlying how responsive imports must be to domestic prices (the ‘import supply elasticity’) in order to thwart an anticompetitive domestic price increase stemming from a merger––an issue that frequently arises in many antitrust reviews. Domestic firms face a fringe comprised of foreign firms who import their products into the domestic market. In the eyes of domestic consumers, these imports are viewed as imperfect substitutes in demand to the output produced by the domestic firms. The model is solved in terms of the ‘critical’ import supply elasticity that can then be used evaluate the ability of imports to constrain an anticompetitive price increase post-merger. Both general and linear demand specifications are considered. Numerical simulations are conducted to consider the magnitude of perturbations in the model’s exogenous parameters. Potential empirical extensions of the model are also considered.