Internal migration and health in South Africa: determinants of healthcare utilisation in a young adult cohort.

Background: In South Africa, human geographic mobility is high as people engage in both permanent and temporary relocation, predominantly from rural to urban areas. Such mobility can compromise healthcare access and utilisation. The objective of this paper is to explore healthcare utilisation and its determinants in a cohort of internal migrants and permanent residents (non-migrants) originating from the Agincourt sub-district in South Africa's rural northeast.

Does It Take a Village? Migration among Rural South African Youth.

In a rural African context, the saying, "it takes a village to raise a child," suggests that community characteristics are substantially important in children's lives as they transition to adulthood. Are these contextual factors also related to youth migration? Demographers are uncertain about how community characteristics improve our understanding of an individual's propensity to migrate, beyond individual and household factors. In many low and middle-income country settings, youth become migrants for the first time in their lives to provide access to resources that their families need.

Holomorphic Hartree-Fock Theory: The Nature of Two-Electron Problems.

We explore the existence and behavior of holomorphic restricted Hartree-Fock (h-RHF) solutions for two-electron problems. Through algebraic geometry, the exact number of solutions with n basis functions is rigorously identified as /(3 - 1), proving that states must exist for all molecular geometries. A detailed study on the h-RHF states of HZ (STO-3G) then demonstrates both the conservation of holomorphic solutions as geometry or atomic charges are varied and the emergence of complex h-RHF solutions at coalescence points.

Moving beyond the household: Innovations in data collection on kinship.

Across settings, it has been shown that the co-residential household is an insufficient measure of family structure and support. However, it continues to be the primary means of population data collection. To address this problem, we developed a new instrument, the Kinship Support Tree (KST), to collect kinship structure and support data on co-residential and non-residential kin and tested it on a sample of 462 single mothers and their children in a slum community in Nairobi, Kenya.

Figuring large optics at the sub-nanometer level: compensation for coating and gravity distortions.

Large, precision optics can now be manufactured with surface figures specified at the sub-nanometer level. However, coatings and gravity deform large optics, and there are limits to what can be corrected by clever compensation. Instead, deformations caused by stress from optical mounts and deposited coatings must be incorporated into the optical design.

Micro-battery development for juvenile salmon acoustic telemetry system applications.

The Endangered Species Act requires actions that improve the passage and survival rates for migrating salmonoids and other fish species that sustain injury and mortality when passing through hydroelectric dams. To develop a low-cost revolutionary acoustic transmitter that may be injected instead of surgically implanted into the fish, one major challenge that needs to be addressed is the micro-battery power source. This work focuses on the design and fabrication of micro-batteries for injectable fish tags.

Ultraviolet laser-induced damage on fused silica substrate and its sol-gel coating.

A comparative study of the laser-induced damage thresholds (LIDTs) of fused silica substrates and their sol-gel silica coatings was carried out with 355 nm laser irradiation. Chemical etching and superpolishing were employed in different ways to improve the substrate. The laser damage tests showed that the coated substrate was no more susceptible to laser damage than the bare substrate, showing that the substrate quality was the dominant factor limiting the LIDT for UV irradiation.

Optimization of coating uniformity in an ion beam sputtering system using a modified planetary rotation method.

A modified planetary rotation system has been developed to obtain high uniformity optical coatings on large substrates in an ion beam sputter coater. The system allows the normally fixed sun gear to rotate, thus allowing an extra degree of freedom and permitting more complex motions to be used. By moving the substrate platen between two fixed positions around the sun axis, averaging of the distributions at these two positions takes place and improved uniformity can be achieved.

A deterministic optical figure correction technique that preserves precision-polished surface quality.

A deterministic surface correction technique has been used to improve the surface figure of two fused silica optical flats over a diameter of 60 mm with no measurable degradation in their surface quality at spatial frequencies of View Article and Find Full Text PDF

Deterministic control of thin film thickness in physical vapor deposition systems using a multi-aperture mask.

A technique for controlling the thickness profile of a thin film in physical vapor deposition systems is reported. The technique uses a novel mask design with apertures of varying dimension to selectively deposit the required film thickness at predetermined locations across the aperture of the substrate. The technique has been used to correct the thickness uniformity of a 55 mm diameter, 280 microm thick, lithium niobate wafer to less than 0.

Mechanical characteristics of optical coatings prepared by various techniques: a comparative study.

Good performance of optical coatings depends on the appropriate combination of optical and mechanical properties. Therefore, successful applications require good understanding of the relationship between optical microstructural and mechanical characteristics and film stability. In addition, there is a lack of standard mechanical tests that allow one to compare film properties measured in different laboratories.