A hierarchy of probabilistic system types

We arrange various types of probabilistic transition systems studied in the literature in an expressiveness hierarchy. The expressiveness criterion is the existence of an embedding of systems of the one class into those of the other. An embedding here is a system transformation which preserves and reflects bisimilarity. To facilitate the task, we define the classes of systems and the corresponding notion of bisimilarity coalgebraically and use the new technical result that an embedding arises from a natural transformation with injective components between the two coalgebra functors under consideration. Moreover, we argue that coalgebraic bisimilarity, on which we base our results, coincides with the concrete notions proposed in the literature for the different system classes, exemplified by a detailed proof for the case of general Segala-type systems.     

Progress and needs in the experimental analysis of drug and alcohol dependence.

Examines the literature on drug dependence from a behavioral viewpoint. Dependence on drugs and alcohol results from an interaction between the individual and the substance within precipitating environmental conditions. Animals and humans self-administer the same drugs, suggesting the biological normality of chemical dependency and the value of laboratory research on the generation and alleviation of such dependencies. Functional or behavioral toxicity can be a serious social problem, and research is needed on why many individuals do not become addicted to drugs and alcohol to which they are exposed, and how social processes can be used to increase an individual's resistance to substance abuse. The cost effectiveness of drug research and treatment is also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An explicit solution to the multi-level programming problem

The multi-level programming problem is defined as an n-person nonzero-sum game with perfect information in which the players move sequentially. The bi-level linear case is addressed in detail. Solutions are obtained by recasting this problem as a standard mathematical probram and appealing to its implicitly separable structure. The reformulated optimization problem is linear save for a complementarity constraint of the form 〈u, g〉 = 0. This constraint is decomposed in a manner that permits us to achieve separability with very little cost in dimensionality. A general branch and bound algorithm is then applied to obtain solutions. Unlike the conventional mathematical program though, the multi-level program may fail to have a solution even when the decision variables are defined over a compact set. An auxiliary optimization problem is employed to detect such failure. Finally, the general max-min problem is discussed within the bi-level programming framework. Examples are given for a variety of related problems.     

Electro-optic imaging of internal fields in (111) GaAsphotoconductors

The nonuniform electric field in a surface (111) GaAs photoconductor was imaged for the first time using the electro-optic effect of the device itself. The technique used a mode-locked 1.06 μm laser with 150 ps pulses to transiently probe the electric field profile at various times following application of a synchronized pulsed voltage bias     

Eosinophilia-myalgia syndrome: mortality data from the US national surveillance system

OBJECTIVE: To describe some of the most severe features of eosinophilia-myalgia syndrome (EMS) and identify potential prognostic indicators. METHODS: Systematic review of data from initial case reports and from followup supplemental death report forms forwarded to the national surveillance system administered by the US Centers for Disease Control (CDC). RESULTS: As of August 10, 1991 36 deaths related to EMS had been reported to CDC. Among all patients fitting the surveillance case definition for EMS, we found that patients who died were older, had higher absolute leukocyte and eosinophil counts, and reported a greater frequency of cough or dyspnea, neuropathy, hepatomegaly, leukocytosis, and elevated erythrocyte sedimentation rate. All patients who died had illnesses affecting multiple organ systems. Of the 36 patients who died, 33 (92%) had neuromuscular sequelae, 29 (81%) had pulmonary complications, and 23 (64%) had cardiac manifestations. The most commonly observed disease process leading to death was progressive polyneuropathy and myopathy (24 of the 36 reported deaths) which produced complications of pneumonia and sepsis or respiratory failure due to weakness; cardiomyopathy was the underlying cause of death for 4 patients, primary pulmonary disease for 3, sudden death attributed to arrhythmia for 2, stroke for 2, and septic complications of therapy for one. CONCLUSION: Although neuromuscular complications were the most prominent sequelae among patients reported to have died, this is clearly a multisystemic disease. Older age and involvement of more than one organ system suggest a particularly poor prognosis, and the neuromuscular, pulmonary and cardiovascular sequelae appear to be the most worrisome.