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Economic analysis has begun to focus on the implications of transaction costs to trading in capital assets. Specifically, the economics of market making and the price of liquidity has received considerable attention. This paper formulates the market maker's bid-ask price decision as a semi-Markov decision process with the reward being a function of expected return and risk. Risk is intimately related to dealer inventory and hence the solution of the analysis specifies bid-ask price strategies which are inventory dependent. Numerical examples indicate the market maker's optimal bid-ask prices will tilt around the ‘assets’ equilibrium price to control inventory as well as influence expected profit.  相似文献   
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Despite a 50-year interdisciplinary and longitudinal research legacy--showing that nearly 80% of young people considered most "at risk" thrive by midlife-only recently have practitioners/researchers engaged in the explicit, prospective facilitation of "resilience" in educational settings. Here, theory/knowledge distinguishing and extending risk and resilience from its risk-based social history to resilience's normative occurrence leads to the first known international and prospective application of resilience in school-based drug education, Project REBOUND [resilience-bound]. It will be implemented as a controlled pilot study, first in Germany, then expand to the United States, as well as other parts of Europe. With evaluation occurring throughout, the goal is to enhance the quality of drug decisions among young people, as well as support their overall competence-based learning and development throughout school. With limitations and underlying psychological mechanisms discussed, it is concluded Project REBOUND offers promising potential for supporting positive drug decisions as well as youth learning and development.  相似文献   
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In electrical engineering, circuit designs are now often optimized via circuit simulation computer models. Typically, many response variables characterize the circuit's performance. Each response is a function of many input variables, including factors that can be set in the engineering design and noise factors representing manufacturing conditions. We describe a modelling approach which is appropriate for the simulator's deterministic input–output relationships. Non-linearities and interactions are identified without explicit assumptions about the functional form. These models lead to predictors to guide the reduction of the ranges of the designable factors in a sequence of experiments. Ultimately, the predictors are used to optimize the engineering design. We also show how a visualization of the fitted relationships facilitates an understanding of the engineering trade-offs between responses. The example used to demonstrate these methods, the design of a buffer circuit, has multiple targets for the responses, representing different trade-offs between the key performance measures.  相似文献   
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Abstract

Despite the availability of a safe and effective vaccine, rubella continues to occur in the United States. In recent years 70% of all cases have occurred in college aged individuals. Since 1978 the University of Rochester has required all entering students to have either rubella immunization or rubella serology. Compliance with this requirement has been excellent and has resulted in an increase in the rubella immunization rate from 52% to 71 %. Of those obtaining serology, the overall susceptibility rate (HI titer < 1:16) was 18%. Less than half of susceptible women accepted immunization, and few susceptible men sought immunization. College entry is a logical time to define an individual's rubella status.  相似文献   
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