Ion adsorption at a metallic electrode: an ab initio based simulation study.

A method for parametrizing, from first principles density functional theory calculations, a model of the interactions between the ions in an ionic liquid and a metallic (electrode) surface is described. The interaction model includes the induction of dipoles on the ions of the liquid by their mutual interaction and the interaction with the electrode surface as well as the polarization of the metal by the ionic charges and dipoles ('image' interactions). The method is used to obtain a suitable interaction model for a system consisting of a LiCl liquid electrolyte and a solid aluminium electrode. The model is then used in simulations of this system for various values of the electrical potential applied to the electrode. The evolution of the liquid structure at the electrochemical interface with applied potential is followed and the capacitance of the electrochemical interface is measured. The electrolyte is found to exhibit a potential-driven phase transition which involves the commensurate ordering of the electrolyte ions with the electrode surface; this leads to a maximum in the differential capacitance as a function of applied potential. Away from the phase transition the capacitance was found to be independent of the applied potential.

Background for the studies on ancillary services and primary care use.

Timely and optimal HIV primary care is a key tenet of the Ryan White CARE Act, a safety net programme for vulnerable and marginalized people living with HIV in the USA. Health services researchers, local providers and policy makers suspect that ancillary services are necessary to improve entry into and retention in HIV primary care for vulnerable populations experiencing barriers to HIV services, including access to antiretroviral therapies. This paper provides background to the eight studies featured in this special supplement to AIDS Care. The eight studies examine retrospectively ancillary (support) services data collected after 1996 in six HIV epicenters (New York and Chicago, plus four sites included in the Client Demonstration project-Los Angeles, San Francisco, Orange County [California] and Washington, DC), three smaller hard-hit cities (Boston, New Orleans and St Louis) and several states (California, plus Michigan and Virginia from the Client Demonstration Projects). These varied delivery settings serve racial and ethnic minority populations, men who have sex with men, injection drug users, women and mothers. The studies use a range of analytic approaches to understand whether receipt of certain enabling services correlated with early entry into and retention in care. Ancillary services (support services such as case management, housing, food, transportation, mental health and substance abuse treatment) are used by local HIV medical and community-based organizations in facilitative strategies directed to populations that have difficulty entering or staying in HIV primary care. Understanding the contribution of ancillary services to timely entry into and consistent use of primary care, including the expanding range of HIV therapeutics, is important to service delivery system planners and resource allocation decision-makers.

The role of ancillary services in client-centred systems of care.

The studies in this issue reflect the operation of the Ryan White CARE Act's holistic model of health and support services for people living with HIV in the USA. Ancillary services available through the CARE Act are responsive to predisposing factors, enabling factors, and system characteristics that pose barriers to clients' receipt of primary medical care. That nearly all of the studies use cross-sectional rather than longitudinal data makes it difficult to draw causal inferences. Taken as a whole, however, the studies suggest that receipt of ancillary services such as case management, mental health and substance abuse treatment, transportation, and housing assistance is associated with primary care entry and retention among CARE Act clients. The studies and the literature out of which they arise suggest that there is a need to refine further our understanding of care systems so that we can refine the care systems themselves. Among the concepts proposed for the study of care systems are comprehensiveness, capacity, coordination, integration, cultural competence, and client-centredness.

Associations between HIV-positive individuals' receipt of ancillary services and medical care receipt and retention.

This study examines associations between HIV-positive individuals' receipt of ancillary services and their receipt of and retention in primary medical care. Ancillary care services examined include case management, mental health and substance abuse treatment/counseling, advocacy, respite and buddy/companion services, as well as food, housing, emergency financial assistance, and transportation. The selection criterion used was the receipt of care from January-June 1997 at selected facilities receiving funding under the Ryan White Comprehensive AIDS Resources Emergency (CARE) Act, a federally funded safety net programme in the USA. The receipt of each ancillary service was associated with the receipt of any primary medical care from a safety net provider. All ancillary services were more strongly associated with primary care receipt than with retention in care or the mean number of primary care visits per year. Mental health and substance abuse treatment/counselling, client advocacy, respite care and buddy/companion services all had significant associations with all primary medical care measures. This is the first time in one study that the primary medical and ancillary services received by all clients at safety net-funded providers from multiple cities and states have been examined. All types of safety net providers, from the largest medical centre to the smallest community-based organization, are represented in this study. The patterns seen here are similar to the findings from the other, geographically more restricted, studies reported on in this volume.

Changing water-use patterns in a water-poor area: lessons for a trachoma intervention project.

An epidemiological survey carried out in the Dodoma region of Tanzania found that high rates of trachoma infection in pre-school children were associated with unwashed faces. Prior to a planned trachoma intervention project, a pilot study was done on household decisions about water use and perceptions about face washing and eye disease. The study found that mothers overestimated the amount of water necessary to wash a child's face. In addition, mothers would not change their water-use priorities without the consent of their husbands and the support of the community. Therefore a health education program was designed to address the perception that face washing required a great deal of water. The program also sought to involve and re-educate the whole community rather than focus only on the mothers who were most likely to wash the children's faces.