Aryl diazonium functionalization of carbon nanohorns

Carbon nanohorns (CNHs) are a relatively new material within the family of elongated carbon nanostructures. A strategy for their solubilization is presented here. Aryl diazonium functionalization of CNHs has been achieved giving rise to soluble materials in common organic solvents as well as water. The modified CNHs have been characterized by complementary spectroscopic and microscopic means as well as thermal gravimetric analysis and dynamic light scattering measurements.     

Healthcare provider cultural competency: Development and initial validation of a patient report measure.

Objective: Health researchers have proposed that provider cultural competency may contribute to health disparities. Yet, this belief continues to lack empirical support, and this is due in part to measurement issues that have plagued the cultural competency construct. In the present research, we report on the development of a theoretically grounded, generally applicable, and patient report measure of provider cultural competency. Design: Samples of predominantly African American patients (N = 310) were recruited from three urban medical clinics to complete a survey about their relationship with their physician. Main Outcome Measures: We examined the factor structure, validity and other psychometric characteristics of a newly proposed patient report measure of provider cultural competency. Results: Psychometric analyses supported a tripartite model of cultural competency that was comprised of patient judgments of their physician's cultural knowledge, awareness, and skill. In addition, this result was replicated across multiple clinical contexts, while also demonstrating convergent and incremental validity when correlated with measures of trust, satisfaction and discrimination. Conclusion: This newly proposed measure addresses prior limitations in cultural competency measurement and may enhance future research by providing a standardized tool for use in multiple clinical and cultural contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Constant Shape Parameter Assumption in Weibull Regression

ABSTRACT

The usual assumption in Weibull regression is that the scale parameter is a function of the predictor variables, and the shape parameter is constant. We consider the problem of estimating parameters in the presence of a nonconstant shape parameter and the effect of assuming a constant shape parameter when it really is not constant. We consider both classical and Bayesian methods of estimation. The misspecification of a constant shape parameter can lead to a loss of power for tests regarding the slope parameters. We find that prediction intervals can be inaccurate when the shape parameter is incorrectly assumed to be constant.