Evaluation of Xanthan Gum in the Preparation of Sustained Release Matrix Tablets

The objective of this study was to evaluate xanthan gum as a matrix former for the preparation of sustained release tablets. Preliminary experiments indicated that a fine particle sue of xanthan gum produced the slowest and most reproducible release profiles. Based on single surface experiments and tablet erosion studies, it was concluded that release of a soluble drug (chlorpheniramine maleate) and an insoluble drug (theophylline) from tablets containing low concentraions of xanthan gum was mainly via diffusion and erosion, respectively. Drug release from tablets containing xanthan gum was slightly faster in acidic media due to more rapid initial surface erosion than at higher pH. After hydration of the gum, drug release was essentially pH-independent. The amount released was directly proportional to the loading dose of drug and inversely proportional to gum concentration in tablets. Release profiles of chlorpheniramine maleate and theophylline remained unchanged after three months storage of the tablets at 40°C/80% RH and 40°C. Model tablets containing 5% xanthan gum exhibited release profiles similar to tablets containing 15% hydroxypropyl methylcellulose.     

Psychometrically matched measures of global cognition, memory, and executive function for assesment of cognitive decline in older persons.

Item response theory methods were used to derive psychometrically sophisticated measures of global cognition, memory, and executive function. Goals were that these measures (a) could be derived from commonly used neuropsychological tests, (b) would have linear measurement properties, and (c) would be psychometrically matched. Scale development was based on a sample of 400 older individuals with cognitive function ranging from normal to demented. Scales were reasonably matched with linear measurement over an ability range relevant to many important clinical applications. Cognitively normal, mild impairment and dementia participant groups differed on baseline measures and rate of decline. Association of measures with quantitative structural magnetic resonance imaging variables followed expected patterns. This approach to scale development may have applications for other neuropsychological assessment problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vicarious dissonance: Attitude change from the inconsistency of others.

Three studies support the vicarious dissonance hypothesis that individuals change their attitudes when witnessing members of important groups engage in inconsistent behavior. Study 1, in which participants observed an actor in an induced-compliance paradigm, documented that students who identified with their college supported an issue more after hearing an ingroup member make a counterattitudinal speech in favor of that issue. In Study 2, vicarious dissonance occurred even when participants did not hear a speech, and attitude change was highest when the speaker was known to disagree with the issue. Study 3 showed that speaker choice and aversive consequences moderated vicarious dissonance, and demonstrated that vicarious discomfort--the discomfort observers imagine feeling if in an actor's place--was attenuated after participants expressed their revised attitudes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Outsourcing in Client/Server Environments

The growing heterogeneity of client/server environments and current state of tool immaturity challenge the skills of IT organizations while increasing management and support costs. Selectively outsourcing nonstrategic client/server tasks that are not performed cost-effectively in-house helps IT managers close the skills gap and improve productivity, reduce costs, and focus on core competencies and initiatives.     

Void formation in OFE copper

This paper reports results from the study of dynamic plastic deformation produced in OFE copper specimens by symmetric rod impact (rod-on-rod) tests. The study was performed by post-test sectioning of the specimens and examination of their microstructure using relatively low magnification optical microscopy. Particular emphasis was placed on porosity as a microstructural feature that relates directly to damage theories of constitutive behavior.     

Cost and performance of CO2 storage in forestry projects

In order to include forestry projects in a possible CO₂ emission reduction regime, and to compare the costs of individual projects or national programs, it is necessary to determine the rate of equivalency between carbon in fossil fuel emissions and carbon stored in different types of forestry projects. This paper presents a comprehensive and consistent methodology to account for the costs and carbon flows of different categories of forestry projects and describes the application of the methodology to a set of projects in Central America. Several estimates have been made to date of the overall potential for carbon storage through global reforestation and the costs of such efforts, based on global macroeconomic estimates and extrapolations from current forest-sector experience. However, there has yet to be a consistent analysis of the magnitude and cost of carbon savings by a “bottom-up” approach to sustainable forestry development

This methodology is applied to a set of projects proposed in Costa Rica and other Central American countries under the Tropical Forest Action Plan, to estimate a sample set of national CO₂ reduction cost curves. The costs of carbon savings in the forestry projects studied in Central America mostly fall between $5 and $13 ton-C¹, depending on the type of project, the climate, and the opportunity cost of land. These projects also promise socio-economic benefits at the local level, provided they are adequately endowed with funding, training and institutional support. The total amount of CO₂ storage potential is significant, about 100 million tons per country, but not enough to suggest that forestry can offset more than a few percent of global CO₂ emissions from fossil fuel use.     

Recall memory, recognition memory, and the eyewitness confidence–accuracy correlation.

Research on the eyewitness confidence-accuracy correlation assesses the degree of insight that eyewitnesses have into the accuracy of their memories. Recently, researchers have begun to consider some of the variables that may facilitate or hinder such insight. In the present study with 205 college undergraduates, a previously unexamined influence on this correlation in the context of memory for details of a simulated crime was investigated. The authors hypothesized and found that recall memory conditions (in which no alternative answers were provided) were characterized by a higher eyewitness confidence–accuracy correlation than recognition memory conditions (in which alternative answers were provided). These findings are explained as a function of the availability of an ease-of-retrieval cue in recall memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An explicit closed-form solution for linear systems subjected to nonstationary random excitation

Explicit, closed-form solutions are presented for the correlation matrix and evolutionary power spectral density matrix of the response of a linear, classically damped MDOF system subjected to a uniformly modulated random process with the gamma envelope function. The effects of the statistical cross-modal correlations on the evolutionary mean square responses are investigated. A simple MDOF system subjected to ground motion is used as an illustrative example. Through this study, additional insight is gained into the nonstationary behavior of linear dynamic systems.     

A controlled, powerful multiple-comparison strategy for several situations.

The multiple-comparison procedure originally proposed by R. A. Fisher (1935) for the 1-way ANOVA context has several desirable properties when K (the number of groups) is equal to 3. In this article, the logic of the procedure is described in conjunction with those properties. A discussion follows of how the Fisher procedure can be similarly applied in a number of other K?=?3 (and, more generally, 2-degree-of-freedom) hypothesis-testing situations. Finally, the Fisher logic is combined with recent sequential applications of the Bonferroni inequality to illustrate the utility and versatility of that combination for the applied researcher. (PsycINFO Database Record (c) 2010 APA, all rights reserved)