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Theoretical Mechanism (theoretical + mechanism)
Selected AbstractsBlob Transport in the Tokamak Scrape-off-LayerCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2004D. A. D'Ippolito Abstract Recent experimental evidence suggests the importance of fast radial plasma transport in the scrape-off-layer (SOL) of tokamaks. The outward transport appears to be convective rather than diffusive, extends into the far SOL, and can produce significant recycling from the main-chamber walls, partially bypassing the divertor. A plausible theoretical mechanism to explain this phenomenon is the radial transport of "blobs" of locally dense plasma created by turbulent processes. A related process is the inward transport of "holes" of reduced density plasma, which provides a mechanism for rapid inward transport of impurities. The blob model is also consistent with the spatial and temporal intermittency and the non-Gaussian statistics observed in the SOL plasma. This paper reviews the present status of blob theory, including analytic models and simulations, and discusses the preliminary comparisons of the blob model with experimental data. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Reproductive asynchrony in natural butterfly populations and its consequences for female matelessnessJOURNAL OF ANIMAL ECOLOGY, Issue 4 2008Justin M. Calabrese Summary 1Reproductive asynchrony, where individuals in a population are short-lived relative to the population-level reproductive period, has been identified recently as a theoretical mechanism of the Allee effect that could operate in diverse plant and insect species. The degree to which this effect impinges on the growth potential of natural populations is not yet well understood. 2Building on previous models of reproductive timing, we develop a general framework that allows a detailed, quantitative examination of the reproductive potential lost to asynchrony in small natural populations. 3Our framework includes a range of biologically plausible submodels that allow details of mating biology of different species to be incorporated into the basic reproductive timing model. 4We tailor the parameter estimation methods of the full model (basic model plus mating biology submodels) to take full advantage of data from detailed field studies of two species of Parnassius butterflies whose mating status may be assessed easily in the field. 5We demonstrate that for both species, a substantial portion of the female population (6·5,18·6%) is expected to die unmated. These analyses provide the first direct, quantitative evidence of female reproductive failure due to asynchrony in small natural populations, and suggest that reproductive asynchrony exerts a strong and largely unappreciated influence on the population dynamics of these butterflies and other species with similarly asynchronous reproductive phenology. [source] A Typology of Organizational Membership: Understanding Different Membership Relationships Through the Lens of Social ExchangeMANAGEMENT AND ORGANIZATION REVIEW, Issue 3 2009Christina L. Stamper abstract Using a social exchange perspective and responding to prior calls to separate resources exchanged from the relationship between parties, we develop a relationship typology based on rights and responsibilities arguments. We begin with the idea that various levels and types of rights and responsibilities are the exchange currency utilized by the employer and employee, respectively. Further, the degree to which an organization grants rights to an individual and the degree to which the individual voluntarily accepts responsibilities results in four distinct organizational membership profiles (i.e., peripheral, associate, detached, and full). We believe this membership typology is an important theoretical mechanism that may be used to link the exchange between the employee and employer (as represented by psychological contracts) to psychological attachment (as represented by perceived membership) between these two parties. Specifically, members in each profile will tend to have certain kinds of psychological attachments to the organization, causing them to (i) perceive membership in certain ways and (ii) behave in a manner consistent with that perception. The article concludes by discussing the implications of the propositions for both researchers and practitioners, as well as making suggestions for future research efforts. [source] A review of the theories of corporate social responsibility: Its evolutionary path and the road aheadINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 1 2008Min-Dong Paul Lee This study aims to trace the conceptual evolutionary path of theories on corporate social responsibility (CSR) and to reflect on the implications of the development. The retrospection has revealed that the trend has been a progressive rationalization of the concept with a particular focus on tighter coupling with organizations' financial goals. Rationalization involves two broad shifts in the conceptualization of CSR. First, in terms of the level of analysis, researchers have moved from the discussion of the macro-social effects of CSR to organizational-level analysis of CSR's effect on profit. Next, in terms of theoretical orientation, researchers have moved from explicitly normative and ethics-oriented arguments to implicitly normative and performance-oriented managerial studies. Based on the retrospection, the limitations of the current state of CSR research that places excessive emphasis on the business case for CSR are outlined, and it is suggested that future research needs to refocus on basic research in order to develop conceptual tools and theoretical mechanisms that explain changing organizational behavior from a broader societal perspective. [source] Self-management for men surviving prostate cancer: a review of behavioural and psychosocial interventions to understand what strategies can work, for whom and in what circumstancesPSYCHO-ONCOLOGY, Issue 9 2010Jane Cockle-Hearne Abstract Objective: In the context of increasing prostate cancer survivorship, evidence of unmet supportive care needs and growing economic health-care restraints, this review examined and evaluated best approaches for developing self-management programmes to meet men's survivorship needs. Methods: A search of international literature published in the last 12 years was conducted. Only randomised controlled trials were included in the analysis. Key components of the interventions were evaluated to determine what has been offered, and which elements are most beneficial in improving health outcomes. Methodological issues were also considered. Results: Targeting participant need and promoting motivation to participate and maintain programme adherence were the most important factors to emerge in ensuring positive health outcomes. Both need and motivation are multi-faceted, the components of which are identified and evaluated. Guidance was also identified in relation to delivery design, theoretical mechanisms for change, modes of delivery and facilitator issues. Conclusion: Self-management is a viable and appropriate way of providing health-care solutions to ameliorate men's functional and emotional problems associated with increased prostate cancer survivorship. Integration into clinical practice will require training, resources and commitment and, in addition, economic viability will be difficult to assess since cost comparison with current provision is not straightforward. Nevertheless, from the psychosocial and behavioural studies reviewed there is convincing evidence that can be used to design, implement and evaluate future self-management programmes for men surviving prostate cancer. Copyright © 2010 John Wiley & Sons, Ltd. [source] Models for Bounded Systems with Continuous DynamicsBIOMETRICS, Issue 3 2009Amanda R. Cangelosi Summary Models for natural nonlinear processes, such as population dynamics, have been given much attention in applied mathematics. For example, species competition has been extensively modeled by differential equations. Often, the scientist has preferred to model the underlying dynamical processes (i.e., theoretical mechanisms) in continuous time. It is of both scientific and mathematical interest to implement such models in a statistical framework to quantify uncertainty associated with the models in the presence of observations. That is, given discrete observations arising from the underlying continuous process, the unobserved process can be formally described while accounting for multiple sources of uncertainty (e.g., measurement error, model choice, and inherent stochasticity of process parameters). In addition to continuity, natural processes are often bounded; specifically, they tend to have nonnegative support. Various techniques have been implemented to accommodate nonnegative processes, but such techniques are often limited or overly compromising. This article offers an alternative to common differential modeling practices by using a bias-corrected truncated normal distribution to model the observations and latent process, both having bounded support. Parameters of an underlying continuous process are characterized in a Bayesian hierarchical context, utilizing a fourth-order Runge,Kutta approximation. [source] | ||||||||||