Conductivity measurements in silicic acid gels during setting

During the course of extensive investigations of the properties and behavior of silicic acid gels, the study of the conductivity of these substances was begun in the hope that data could be assembled to throw some light on the mechanism of gelation. The experiments to be described are a continuation of the work on conductivity carried out at Union College under the direction of Dr. C. B. Hurd. H. Swanker (1), in 1932, making use of a Wheatstone bridge at 1000 cycles, failed to find any change in conductivity, but R. W. Gurry (2), using refined methods, was able to detect small changes as the gels set. Subsequently the technique of measurement was further improved by R. Slobod (3) in 1935, and R. E. Russel (4) in 1936. Slobod\u27s curves showed a definite increase in conductivity, but his own experiments and those of Russell made those results appear doubtful. Russell, continuing the work of Slobod on the equilibrium phenomena arising, studied the treatment of the electrodes

Energiekonzept fuer den Wetteraukreis

SIGLEAvailable from Cooperative Architekten und Ingenieure, Darmstadt (DE) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Sustainable HIV treatment in Africa through viral-load-informed differentiated care

There are inefficiencies in current approaches to monitoring patients on antiretroviral therapy in sub-Saharan Africa. Patients typically attend clinics every 1 to 3 months for clinical assessment. The clinic costs are comparable with the costs of the drugs themselves and CD4 counts are measured every 6 months, but patients are rarely switched to second-line therapies. To ensure sustainability of treatment programmes, a transition to more cost-effective delivery of antiretroviral therapy is needed. In contrast to the CD4 count, measurement of the level of HIV RNA in plasma (the viral load) provides a direct measure of the current treatment effect. Viral-load-informed differentiated care is a means of tailoring care so that those with suppressed viral load visit the clinic less frequently and attention is focussed on those with unsuppressed viral load to promote adherence and timely switching to a second-line regimen. The most feasible approach to measuring viral load in many countries is to collect dried blood spot samples for testing in regional laboratories; however, there have been concerns over the sensitivity and specificity of this approach to define treatment failure and the delay in returning results to the clinic. We use modelling to synthesize evidence and evaluate the cost-effectiveness of viral-load-informed differentiated care, accounting for limitations of dried blood sample testing. We find that viral-load-informed differentiated care using dried blood sample testing is cost-effective and is a recommended strategy for patient monitoring, although further empirical evidence as the approach is rolled out would be of value. We also explore the potential benefits of point-of-care viral load tests that may become available in the future.This article has not been written or reviewed by Nature editors. Nature accepts no responsibility for the accuracy of the information provided