A cognitive-behavioral plus exercise intervention for older adults with chronic back pain: race/ethnicity effect?

This pilot study examined the feasibility and potential efficacy of a self-management program for seniors with chronic back pain and assessed for possible race/ethnicity differences in program impact. Sixty-nine seniors (24 African Americans, 25 Hispanics, and 20 non-Hispanic Whites) enrolled in the 8-wk community-based program. Efficacy outcomes included pain-related disability as measured by the Roland Morris Disability Questionnaire (RMDQ), pain intensity, pain self-efficacy, depressive symptoms, social activity, and functional status. Eighty percent of enrollees completed the program. Clinically important decreases in RMDQ scores were found for non-Hispanic White (adjusted change score = -3.53), African American (-3.89), and Hispanic (-8.45) participants. Improvements in all other outcomes were observed, but only for Hispanic participants. Results confirm that implementation of the protocol in urban senior centers is feasible, and the program shows potential efficacy. The race/ethnicity differences observed in the current study merit further investigation.     

An EM type estimation procedure for the destructive exponentially weighted Poisson regression cure model under generalized gamma lifetime

In this paper, we assume the number of competing causes to follow an exponentially weighted Poisson distribution. By assuming the initial number of competing causes can undergo destruction and that the population of interest has a cure fraction, we develop the EM algorithm for the determination of the MLEs of the model parameters of such a general cure model. This model is more flexible than the promotion time cure model and also provides an interesting and realistic interpretation of the biological mechanism of the occurrence of an event of interest. Instead of assuming a particular parametric distribution for the lifetime, we assume the lifetime to belong to the wider class of generalized gamma distribution. This allows us to carry out a model discrimination to select a parsimonious lifetime distribution that provides the best fit to the data. Within the EM framework, a two-way profile likelihood approach is proposed to estimate the shape parameters. An extensive Monte Carlo simulation study is carried out to demonstrate the performance of the proposed estimation method. Model discrimination is carried out by means of the likelihood ratio test and information-based methods. Finally, a data on melanoma is analyzed for illustrative purpose.     

Trace Class Markov Chains for Bayesian Inference with Generalized Double Pareto Shrinkage Priors

Bayesian shrinkage methods have generated a lot of interest in recent years, especially in the context of high‐dimensional linear regression. In recent work, a Bayesian shrinkage approach using generalized double Pareto priors has been proposed. Several useful properties of this approach, including the derivation of a tractable three‐block Gibbs sampler to sample from the resulting posterior density, have been established. We show that the Markov operator corresponding to this three‐block Gibbs sampler is not Hilbert–Schmidt. We propose a simpler two‐block Gibbs sampler and show that the corresponding Markov operator is trace class (and hence Hilbert–Schmidt). Establishing the trace class property for the proposed two‐block Gibbs sampler has several useful consequences. Firstly, it implies that the corresponding Markov chain is geometrically ergodic, thereby implying the existence of a Markov chain central limit theorem, which in turn enables computation of asymptotic standard errors for Markov chain‐based estimates of posterior quantities. Secondly, because the proposed Gibbs sampler uses two blocks, standard recipes in the literature can be used to construct a sandwich Markov chain (by inserting an appropriate extra step) to gain further efficiency and to achieve faster convergence. The trace class property for the two‐block sampler implies that the corresponding sandwich Markov chain is also trace class and thereby geometrically ergodic. Finally, it also guarantees that all eigenvalues of the sandwich chain are dominated by the corresponding eigenvalues of the Gibbs sampling chain (with at least one strict domination). Our results demonstrate that a minor change in the structure of a Markov chain can lead to fundamental changes in its theoretical properties. We illustrate the improvement in efficiency resulting from our proposed Markov chains using simulated and real examples.     

Information Diffusion among Agents: Implications for Humanitarian Operations

The basis for this article is an information‐processing view of the UN's cluster approach. We use agent‐based modeling and simulations to show that clusters, if properly utilized, encourage better information flow and thus facilitate effective response to disasters. The article intends to turn the attention of the humanitarian community to the importance of sharing information and the role of cluster leads in facilitating humanitarian aid. Our results indicate that if cluster leads act as information hubs, information reaches its target faster, enabling a prompt humanitarian response. In addition, we show that information quality is critical for effective resource utilization—if cluster leads filter information, it moves faster. We also found evidence that the willingness to exchange information plays a larger role in transmitting information than that of an information hub, particularly during later stages of response operations.     

Public Relations in a Global Context: The Relevance of Critical Modernism as a Theoretical Lens

This article aims to interrupt the modernist goals of public relations research that predominantly privileges a management discourse. The emergence of the intertwined nature of cultural phenomena in the context of globalization necessitates alternative ways of thinking about public relations. This article explores the possibilities of postmodernism to disrupt the accepted norms of the dominant discourse of public relations. However, given the fragmented nature of the discursive space in postmodernism, this article advances the argument that critical modernism provides a relevant alternative to the modernist paradigm of public relations research by utilizing globalization theories. It suggests a space for articulating the roles of power and structure situated within the constitutive spaces of discourse.