Distribution of ions around a charged sphere

Using a new method of calculating the effects of excluded volume, the authors evaluate the distribution of counterions around a charged sphere in thermal equilibrium. In regions of high concentration a saturation of the ion density is found, which is absent in the more conventional Gouy-Chapman model. At the same time the saturation effect of the potential (a property of the Gouy-Chapman model) is removed, giving significant corrections to the values of the potential and concentration at the surface of the sphere

Transport coefficients for rigid spherically symmetric polymers or aggregates

In this paper we investigate the transport properties for rigid spherically symmetric macromolecules, having a segment density distribution falling off as r- lambda . We calculate the rotational and translational diffusion coefficient for a spherically symmetric polymer and the shear viscosity for a dilute suspension of these molecules, starting from a continuum description based on the Debye-Brinkman equation. Instead of numerical methods for solving equations we use perturbative methods, especially methods from boundary-layer analysis. The calculations provide simple analytical formulae for the shear viscosity eta , and the translational and rotational diffusion coefficients DT and DR. The results can also be applied to suspensions of other porous objects, such as aggregates of colloidal particles in which D=3- lambda is called the fractal dimension of the aggregate

Effects of excluded volume on the electrolyte distribution around a charged sphere

A recently developed method is used to calculate the main effects of excluded volume on the distribution of ions around a charged central sphere in thermal equilibrium. The authors find significant corrections to the results of the conventional Gouy-Chapman theory when the electrostatic energy due to the charge of the sphere is large compared with the thermal energy. The concentration shows a distinct saturation effect, while at the surface of the sphere the known saturation of the potential is lifted. Furthermore, the effect of excluded volume is found to be strongly dominated by the excluded volume of ions with a charge opposite to the charge of the sphere

Parallel efficiency of a boundary integral equation method for nonlinear water waves

We describe the application of domain decomposition on a boundary integral method for the study of nonlinear surface waves on water in a test case for which the domain decomposition approach is an important tool to reduce the computational effort. An important aspect is the determination of the optimum number of domains for a given parallel architecture. Previous work on hetero- geneous clusters of workstations is extended to (dedicated) parallel platforms. For these systems a better indication of the parallel performance of the domain decomposition method is obtained because of the absence of varying speed of the processing elements

Norms for creativity and implementation in healthcare teams: testing the group innovation inventory

Abstract OBJECTIVE: To test to what extent the four-factor structure of the group innovation inventory (GII) is confirmed for improvement teams participating in a quality improvement collaborative. DESIGN: Quasi-experimental design with baseline and end-measurement after intervention. SETTING: This study included quality improvement teams participating in the Care for Better improvement programme for home care, care for the handicapped and the elderly in the Netherlands between 2006 and 2008. PARTICIPANTS: As part of a larger evaluation study, 261 written questionnaires from team members were collected at baseline (pre-project sample) and 129 questionnaires at end-measurement (post-project sample). MAIN OUTCOME MEASURE: Group innovation inventory. RESULTS: Confirmatory factor analyses revealed the expected four-factor structure and good fit indices. The subscales 'group functioning' and 'speed of action' showed acceptable Cronbach's alphas and high inter-item correlations. The subscales 'support for risk taking' and 'tolerance of mistakes' showed insufficient reliability and validity. CONCLUSIONS: The group functioning and speed of action subscales of the GII showed acceptable psychometric properties and are applicable to quality improvement teams in health care. In order to understand how social expectations within teams working in health care organizations exert influence over attitudes and behaviours thought to stimulate creativity, further conceptualization of the norms for enhancing creativity within health care is needed

Validation of the Caregivers’ Satisfaction with Stroke Care Questionnaire: C-SASC hospital scale

To date, researchers have lacked a validated instrument to measure stroke caregivers’ satisfaction with hospital care. We adjusted a validated patient version of satisfaction with hospital care for stroke caregivers and tested the 11-item caregivers’ satisfaction with hospital care (C-SASC hospital scale) on caregivers of stroke patients admitted to nine stroke service facilities in the Netherlands. Stroke patients were identified through the stroke service facilities; caregivers were identified through the patients. We collected admission demographic data from the caregivers and gave them the C-SASC hospital scale. We tested the instrument by means of structural equation modeling and examined its validity and reliability. After the elimination of three items, the confirmatory factor analyses revealed good indices of fit with the resulting eight-item C-SASC hospital scale. Cronbach’s α was high (0.85) and correlations with general satisfaction items with hospital care ranged from 0.594 to 0.594 (convergent validity). No significant relations were found with health and quality of life (divergent validity). Such results indicate strong construct validity. We conclude that the C-SASC hospital scale is a promising instrument for measuring stroke caregivers’ satisfaction with hospital stroke care

A large-scale longitudinal study indicating the importance of perceived effectiveness, organizational and management support for innovative culture

AbstractTeams participating in QI collaboratives reportedly enhance innovative culture in long-term care, but we currently lack empirical evidence of the ability of such teams to enhance (determinants of) innovative culture over time. The objectives of our study are therefore to explore innovative cultures in QI teams over time and identify its determinants. The study included QI teams participating between 2006 and 2011 in a national Dutch quality program (Care for Better), using an adapted version of the Breakthrough Method. Each QI team member received a questionnaire by mail within one week after the second (2–3 months post-implementation of the collaborative = T0) and final conference (12 months post-implementation = T1). A total of 859 (out of 1161) respondents filled in the questionnaire at T0 and 541 at T1 (47% response). A total of 307 team members filled in the questionnaire at both T0 and T1. We measured innovative culture, respondent characteristics (age, gender, education), perceived team effectiveness, organizational support, and management support. Two-tailed paired t-tests showed that innovative culture was slightly but significantly lower at T1 compared to T0 (12 months and 2–3 months after the start of the collaborative, respectively). Univariate analyses revealed that perceived effectiveness, organizational and management support were significantly related to innovative culture at T1 (all at p ≤ 0.001). Multilevel analyses showed that perceived effectiveness, organizational support, and management support predicted innovative culture. Our QI teams were not able to improve innovative culture over time, but their innovative culture scores were higher than non-participant professionals. QI interventions require organizational and management support to enhance innovative culture in long-term care settings

Creating effective quality-improvement collaboratives: a multiple case study

Objective: To explore whether differences between collaboratives with respect to type of topic, type of targets, measures (systems) are also reflected in the degree of effectiveness. Study setting: 182 teams from long-term healthcare organisation developed improvement initiatives in seven quality-improvement collaboratives (QICs) focusing on patient safety and autonomy. Study design: Multiple case before-after study. Data collection: 75 team leaders completed a written questionnaire at the end of each QIC on achievability and degree of challenge of targets and measurability of progress. Main outcome indicators were collaborative-specific measures (such as prevalence of pressure ulcers). Principal findings: The degree of effectiveness and percentage of teams realising targets varied between collaboratives. Collaboratives also varied widely in perceived measurability (F=6.798 and p=0.000) and with respect to formulating achievable targets (F=6.566 and p=0.000). The Problem Behaviour collaborative scored significantly lower than all other collaboratives on both dimensions. The collaborative on Autonomy and control scored significantly lower on measurability than the other collaboratives. Topics for which there are best practices and evidence of effective interventions do not necessarily score higher on effectiveness, measurability, achievable and challenging targets. Conclusions: The effectiveness of a QIC is associated with the efforts of programme managers to create conditions that provide insight into which changes in processes of care and in client outcomes have been made. Measurability is not an inherent property of the improvement topic. Rather, creating measurability and formulating challenging and achievable targets is one of the crucial tasks for programme managers of QICs