41 research outputs found
Investment Climate Reforms and the Development of SMEs: A Comparative Analysis from South Africa, Cameroon and Nigeria
It has been observed in fast growing economies that the private sector plays an important role in the domestic mobilisation of resources useful for developmental purposes.
An investigation of community perceptions of the socioeconomic factors that hinder the empowerment of women in Belhar
Magister Artium - MAThe aim of this study is to examine the community’s perceptions of the factors that hamper the empowerment of women in post apartheid South Africa, particularly, women in Belhar community in the Western Cape. Of special interest is the community’s perception of how different policies in post-apartheid South Africa have impacted on the socio-economic participation/discrimination of women’s fight against disempowerment. It will also provide recommendations on how best community based systems can be structured to improve women empowerment
A Shack-Hartmann sensor for single-shot multi-contrast imaging with hard X-rays
An array of compound refractive X-ray lenses (CRL) with 20x20 lenslets, a
focal distance of 20 cm and a visibility of 0.93 is presented. It can be used
as a Shack-Hartmann sensor for hard X-rays (SHARX) for wavefront sensing and
permits for true single-shot multi-contrast imaging the dynamics of materials
with a spatial resolution in the micrometer range, sensitivity on nanosized
structures and temporal resolution on the microsecond scale. The object's
absorption and its induced wavefront shift can be assessed simultaneously
together with information from diffraction channels. This enables the imaging
of hierarchical materials. In contrast to the established Hartmann sensors the
SHARX has an increased flux efficiency through focusing of the beam rather than
blocking parts of it. We investigated the spatiotemporal behavior of a
cavitation bubble induced by laser pulses. Furthermore, we validated the SHARX
by measuring refraction angles of a single diamond CRL, where we obtained an
angular resolution better than 4 microrad
Bone mineral density and risk of heart failure in older adults: The Cardiovascular Health Study
Background
Despite increasing evidence of a common link between bone and heart health, the relationship between bone mineral density (
BMD
) and heart failure (
HF
) risk remains insufficiently studied.
Methods and Results
We investigated whether
BMD
measured by dual‐energy x‐ray absorptiometry was associated with incident
HF
in an older cohort. Cox models were stratified by sex and interactions of
BMD
with race assessed.
BMD
was examined at the total hip and femoral neck separately, both continuously and by World Health Organization categories. Of 1250 participants, 442 (55% women) developed
HF
during the median follow‐up of 10.5 years. In both black and nonblack women, neither total hip nor femoral neck
BMD
was significantly associated with
HF
; there was no significant interaction by race. In black and nonblack men, total hip, but not femoral neck,
BMD
was significantly associated with
HF
, with evidence of an interaction by race. In nonblack men, lower total hip
BMD
was associated with higher
HF
risk (hazard ratio, 1.13 [95% CI, 1.01–1.26] per 0.1 g/cm
2
decrement), whereas in black men, lower total hip
BMD
was associated with lower
HF
risk (hazard ratio, 0.74 [95% CI, 0.59–0.94]). There were no black men with total hip osteoporosis. Among nonblack men, total hip osteoporosis was associated with higher
HF
risk (hazard ratio, 2.83 [95% CI, 1.39–5.74]) compared with normal
BMD
.
Conclusions
Among older adults, lower total hip
BMD
was associated with higher
HF
risk in nonblack men but lower risk in black men, with no evidence of an association in women. Further research is needed to replicate these findings and to study potential underlying pathways.
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Imaging defects in vanadium(iii) oxide nanocrystals using Bragg coherent diffractive imaging
Defects in strongly correlated materials such as V2O3 play influential roles on their electrical properties. Understanding the defects' structure is of paramount importance. In this project, we investigate defect structures in V2O3 grown via a flux method. We use AFM to see surface features in several large flake-like particles that exhibit characteristics of spiral growth. We also use Bragg coherent diffractive imaging (BCDI) to probe in 3 dimensions a smaller particle without flake-like morphology and note an absence of the pure screw dislocation characteristic of spiral growth. We identified and measured several defects by comparing the observed local displacement of the crystal, measured via BCDI to well-known models of the displacement around defects in the crystal. We identified two Image ID:d1ce00736j-t1.gif partial dislocations in the crystal. We discuss how defects of different types influence the morphology of V2O3 crystals grown via a flux method
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Nanoscale strain mapping in battery nanostructures
Coherent x-ray diffraction imaging is used to map the local three dimensional strain inhomogeneity and electron density distribution of two individual LiNi0.5Mn1.5O4-δ cathode nanoparticles in both ex-situ and in-situ environments. Our reconstructed images revealed a maximum strain of 0.4%. We observed different variations in strain inhomogeneity due to multiple competing effects. The compressive/tensile component of the strain is connected to the local lithium content and, on the surface, interpreted in terms of a local Jahn-Teller distortion of Mn 3+. Finally, the measured strain distributions are discussed in terms of their impact on competing theoretical models of the lithiation process. © 2014 AIP Publishing LLC
A Shack-Hartmann Sensor for Single-Shot Multi-Contrast Imaging with Hard X-rays
An array of compound refractive X-ray lenses (CRL) with 20 x 20 lenslets, a focal distance of 20 cm and a visibility of 0.93 is presented. It can be used as a Shack-Hartmann sensor for hard X-rays (SHARX) for wavefront sensing and permits for true single-shot multi-contrast imaging the dynamics of materials with a spatial resolution in the micrometer range, sensitivity on nanosized structures and temporal resolution on the microsecond scale. The object’s absorption and its induced wavefront shift can be assessed simultaneously together with information from diffraction channels. In contrast to the established Hartmann sensors the SHARX has an increased flux efficiency through focusing of the beam rather than blocking parts of it. We investigated the spatiotemporal behavior of a cavitation bubble induced by laser pulses. Furthermore, we validated the SHARX by measuring refraction angles of a single diamond CRL, where we obtained an angular resolution better than 4 μrad