Curved Chaotic Map Time Series Models and Their Stochastic Reversals

This paper considers two types of chaotic map time series models, including the well-known tent, logistic and binary-shift maps as special cases; these are called curved tent and curved binary families. Deterministic behaviour is investigated by invariant distributions, Lyapunov exponents, and by serial dependency. Stochastic time reversal of the families is shown to produce models which have a broader range of stochastic and chaotic properties than their deterministic counterparts. The marginal distributions may have concentrations and restricted supports and are shown to be a non-standard class of invariant distribution. Dependenc y is generally weaker with the reversed stochastic models. The work gives a broad statistical account of deterministic and stochastically reversed map models, such as are emerging in random number generation, communica tion systems and cryptography     

Organizational effectiveness. Primary care and the congruence model

The congruence model is a framework used to analyze organizational strengths and weaknesses and pinpoint specific areas for improving effectiveness. This article provides an overview of organizations as open systems, with examples in the primary care arena. It explains and applies the congruence model in the context of primary care issues and functions, including methods by which the model can be used to diagnose organizational problems and generate solutions. Changes needed in primary care due to the managed care environment, and areas of potential problems and sensitivities requiring organizational changes to meet market and regulatory demands now placed on PCOs are examined.     

The medical practice as business organization

Medical practices historically have not been examined in terms of their organizational structures and of the appropriateness of their structures for survival as business entities. In this paper, we propose a model for the typical medical practice and discuss its fit with current organizational theory. It is apparent that the medical practice organization does not fit with the demands of a rapidly changing and complex environment. To survive and grow, the medical practice organization must align itself with others that have an interest and stake in the health care system, develop teamwork among physicians, bridge the gap between physicians and others in the organization, and recognize that the work done in the organization depends on other components of the organization.     

Suggestions for management training of residents

In addition to having medical expertise, physicians must possess managerial skills to deal with the ever-changing business environment of the practice of medicine. This article addresses the need for management training of physicians and calls for management training during residency and medical school. It also describes one residency program's efforts to provide comprehensive management training to its residents in pathology.     

Physician glut. Physicians--the next victims of "downsizing?"

Should physicians really be polishing up their CVs or preparing to enter another line of work? In a word: No. What a recent survey makes clear is that, while managed care is driving physicians from some markets, jobs are still available in other markets traditionally underserved by physicians. This is not to suggest that the physician employment market has gone unchanged. Many physicians, particularly specialists, have taken income hits, and some specialists truly are in need of work. Primary care physicians, however, have seen their stars rise and are now in a position to work wherever they want. Physicians may no longer be able to practice within 50 miles of where they were raised or where they were trained, as has been their wont. Instead, they will have to do what other professionals have long done--go where job opportunities take them. In short, they will have to add a career strategy to their scientific mindset, and that means an aggressive job search, coupled with a strong consumer orientation.     

Assessing right to die attitudes: a conceptually guided measurement model

This article discusses the current status of research regarding the assessment of attitudes toward euthanasia and other right to die constructs with a focus on conceptual and methodological issues hindering advancement in this area. Two models are presented: a conceptual model for differentiating the various right to die constructs, and a measurement model to guide scale development and refinement. The conceptual model defines the right to die constructs as a function of locus of decision and locus of action. Health status and age are hypothesized as important factors that in some instances are defining attributes in right to die constructs and in other instances are factors influencing people's attitudes toward the right to die. The measurement model considers the importance of construct specificity, individual characteristics, and conviction in the assessment of right to die attributes. An extant euthanasia attitude scale is presented and evaluated in terms of the models to demonstrate how they may be useful for advancing attitude research in this important area.     

Mandatory seat belt laws in the states. A study of fatal and severe occupant injuries

This study examines the impact of mandatory seat belt laws on fatal and incapacitating injury rates in the states. Annual data for all 50 states for the period 1975-1991 are used. Pooled time series analysis is employed. The general conclusion that emerges from this analysis is that seat belt laws significantly impact state fatal injury rates. Primary enforcement and all-seat coverage provisions appear to be particularly effective in reducing fatality rates.