1,801 research outputs found
Africa's Wealthy Give Back: A Perspective on Philanthropic Giving by Wealthy Africans in sub-Saharan Africa, with a focus on Kenya, Nigeria, and South Africa
Over the last few years we have begun to see the emergence of more strategic philanthropy, the growth of formal vehicles for its practice, and the rise of new platforms that reflect African voices. There is also a growing interest to better understand African philanthropy and learn from the experience of African philanthropists so as to achieve greater impact. This research forms part of that effort by providing a pan-African view of a specific group of philanthropists from Africa. It focuses on Kenya, Nigeria, and South Africa, countries that are in the spotlight due to their respective positions within their regions, their economic status and their levels of giving by the wealthy. However, individuals from countries such as Uganda, Ghana and the Democratic Republic of the Congo as well as from the African Diaspora also participated in the stud
Immigration and low birthweight in the US: The role of time and timing
The literature exploring the health consequences of immigration is largely dominated by efforts to replicate, across outcomes and populations, and explain two widely observed findings: that foreign nativity is protective (yielding the “healthy migrant effect” or “immigrant paradox”) and that the health advantage of immigrants diminishes over time in the host country. In this study, we focus on the second of these patterns and provide evidence that a lifecourse perspective can help to explain the apparent deterioration in health by incorporating attention to immigrants’ timing of arrival. We examine the role of immigrants’ exposure to the US, in terms of both age at immigration and length of residence, in shaping birthweight, a well measured and consequential marker of health, and maternal smoking, an important risk factor for low birthweight.
Africas Wealthy Give Back
Philanthropy is an integral part of the African identity. Philanthropy, or giving, has long been practiced by Africans at individual and community levels, both formally and informally, and at multiple levels of scale
How fluid infiltrates dry crustal rocks during progressive eclogitization and shear zone formation: insights from H2O contents in nominally anhydrous minerals
Granulites from Holsnøy (Bergen Arcs, Norway) maintained a metastable state until fluid infiltration triggered the kinetically delayed eclogitization. Interconnected hydrous eclogite-facies shear zones are surrounded by unreacted granulites. Macroscopically, the granulite–eclogite interface is sharp and there are no significant compositional changes in the bulk chemistry, indicating the fluid composition was quickly rock buffered. To better understand the link between deformation, fluid influx, and fluid–rock interaction one cm-wide shear zone at incipient eclogitization is studied here. Granulite and eclogite consist of garnet, pyroxene, and plagioclase. These nominally anhydrous minerals (NAMs) can incorporate H2O in the form of OH groups. H2O contents increase from granulite to eclogite, as documented in garnet from ~ 10 to ~ 50 µg/g H2O, pyroxene from ~ 50 to ~ 310 µg/g H2O, and granulitic plagioclase from ~ 10 to ~ 140 µg/g H2O. Bowl-shape profiles are characteristic for garnet and pyroxene with lower H2O contents in grain cores and higher at the rims, which suggest a prograde water influx into the NAMs. Omphacite displays a H2O content range from ~ 150 to 425 µg/g depending on the amount of hydrous phases surrounding the grain. The granulitic plagioclase first separates into a hydrous, more albite-rich plagioclase and isolated clinozoisite before being replaced by new fine-grained phases like clinozoisite, kyanite and quartz during ongoing fluid infiltration. Results indicate a twofold fluid influx with different mechanisms to act simultaneously at different scales and rates. Fast and more pervasive proton diffusion is recorded by NAMs that retain the major element composition of the granulite-facies equilibration where hydrogen decorates pre-existing defects in the crystal lattice and leads to OH increase. Contemporaneously, slower grain boundary-assisted aqueous fluid influx enables element transfer and results in progressive formation of new minerals, e.g., hydrous phases. Both mechanisms lead to bulk H2O increase from ~ 450 to ~ 2500 µg/g H2O towards the shear zone and convert the system from rigid to weak. The incorporation of OH groups reduces the activation energy for creep, promotes formation of smaller grain sizes (phase separation of plagioclase), and synkinematic metamorphic mineral reactions. These processes are part of the transient weakening, which enhance the sensitivity of the rock to deform
Developing an Easy Read version of the Adult Social Care Outcomes Toolkit (ASCOT)
Background: This paper reports the experiences of developing and pre-testing an Easy Read version of the Adult Social Care Outcomes Toolkit (ASCOT) for self-report by people with intellectual disabilities. Method: The study has combined survey development and pre-testing methods with approaches to create accessible information for people with intellectual disabilities. A working group assisted researchers in identifying appropriate question formats, pictures and wording. Focus groups and cognitive interviews were conducted to test various iterations of the instrument. Results: Substantial changes were made to the questionnaire, which included changes to illustrations, the wording of question stems and response options. Conclusions: The process demonstrated the benefits of involving people with intellectual disabilities in the design and testing of data collection instruments. Adequately adapted questionnaires can be useful tools to collect information from people with intellectual disabilities in survey research; however its limitations must be recognised
Life and Death of Selfish Genes: Comparative Genomics Reveals the Dynamic Evolution of Cytoplasmic Incompatibility.
Cytoplasmic incompatibility is a selfish reproductive manipulation induced by the endosymbiont Wolbachia in arthropods. In males Wolbachia modifies sperm, leading to embryonic mortality in crosses with Wolbachia-free females. In females, Wolbachia rescues the cross and allows development to proceed normally. This provides a reproductive advantage to infected females, allowing the maternally transmitted symbiont to spread rapidly through host populations. We identified homologs of the genes underlying this phenotype, cifA and cifB, in 52 of 71 new and published Wolbachia genome sequences. They are strongly associated with cytoplasmic incompatibility. There are up to seven copies of the genes in each genome, and phylogenetic analysis shows that Wolbachia frequently acquires new copies due to pervasive horizontal transfer between strains. In many cases, the genes have subsequently acquired loss-of-function mutations to become pseudogenes. As predicted by theory, this tends to occur first in cifB, whose sole function is to modify sperm, and then in cifA, which is required to rescue the cross in females. Although cif genes recombine, recombination is largely restricted to closely related homologs. This is predicted under a model of coevolution between sperm modification and embryonic rescue, where recombination between distantly related pairs of genes would create a self-incompatible strain. Together, these patterns of gene gain, loss, and recombination support evolutionary models of cytoplasmic incompatibility.Wellcome Trust grant number WT094664MA
- Wellcome Trust grant number WT202888/Z/16/Z
- ERC grant 28166
Idiosyncratic Brain Activation Patterns Are Associated with Poor Social Comprehension in Autism
Autism spectrum disorder (ASD) features profound social deficits but neuroimaging studies have failed to find any consistent neural signature. Here we connect these two facts by showing that idiosyncratic patterns of brain activation are associated with social comprehension deficits. Human participants with ASD (N = 17) and controls (N = 20) freely watched a television situation comedy (sitcom) depicting seminaturalistic social interactions (“The Office”, NBC Universal) in the scanner. Intersubject correlations in the pattern of evoked brain activation were reduced in the ASD group—but this effect was driven entirely by five ASD subjects whose idiosyncratic responses were also internally unreliable. The idiosyncrasy of these five ASD subjects was not explained by detailed neuropsychological profile, eye movements, or data quality; however, they were specifically impaired in understanding the social motivations of characters in the sitcom. Brain activation patterns in the remaining ASD subjects were indistinguishable from those of control subjects using multiple multivariate approaches. Our findings link neurofunctional abnormalities evoked by seminaturalistic stimuli with a specific impairment in social comprehension, and highlight the need to conceive of ASD as a heterogeneous classification
Sol–gel thermal barrier coatings: Optimization of the manufacturing route and durability under cyclic oxidation
A new promising and versatile process based on the sol–gel transformation has been developed to deposit yttria-stabilised thermal barrier coatings. The non-oriented microstructure with randomly structured pore network, resulting from the soft chemical process, is expected to show satisfactory thermo-mechanical behaviour when the TBC is cyclically oxidized. First stage of the research consists of optimizing the processing route to generate homogeneous microstructure and controlled surface roughness. The objective is to reduce, as much as possible, the size and depth of the surface cracks network inherent to the process. Indeed, the durability of the TBC when cyclically oxidized strongly depends on the sharpness of those cracks that concentrate thermo-mechanical stresses and generate detrimental propagation resulting in spallation. Cyclic oxidation tests are performed using a cyclic oxidation rig instrumented with CCD cameras to monitor in a real time basis the mechanism of crack propagation and spallation. The impact of various parameters either directly related to the processing route, e.g. the intimate microstructure of the TBC and the TBC thickness, or to the thermal loading, e.g. the oxidation temperature and the cumulated hot time, on the durability of the TBC is investigate
Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems
Small-angle coronagraphy is technically and scientifically appealing because
it enables the use of smaller telescopes, allows covering wider wavelength
ranges, and potentially increases the yield and completeness of circumstellar
environment - exoplanets and disks - detection and characterization campaigns.
However, opening up this new parameter space is challenging. Here we will
review the four posts of high contrast imaging and their intricate interactions
at very small angles (within the first 4 resolution elements from the star).
The four posts are: choice of coronagraph, optimized wavefront control,
observing strategy, and post-processing methods. After detailing each of the
four foundations, we will present the lessons learned from the 10+ years of
operations of zeroth and first-generation adaptive optics systems. We will then
tentatively show how informative the current integration of second-generation
adaptive optics system is, and which lessons can already be drawn from this
fresh experience. Then, we will review the current state of the art, by
presenting world record contrasts obtained in the framework of technological
demonstrations for space-based exoplanet imaging and characterization mission
concepts. Finally, we will conclude by emphasizing the importance of the
cross-breeding between techniques developed for both ground-based and
space-based projects, which is relevant for future high contrast imaging
instruments and facilities in space or on the ground.Comment: 21 pages, 7 figure
The syncytial Drosophila embryo as a mechanically excitable medium
Mitosis in the early syncytial Drosophila embryo is highly correlated in
space and time, as manifested in mitotic wavefronts that propagate across the
embryo. In this paper we investigate the idea that the embryo can be considered
a mechanically-excitable medium, and that mitotic wavefronts can be understood
as nonlinear wavefronts that propagate through this medium. We study the
wavefronts via both image analysis of confocal microscopy videos and
theoretical models. We find that the mitotic waves travel across the embryo at
a well-defined speed that decreases with replication cycle. We find two markers
of the wavefront in each cycle, corresponding to the onsets of metaphase and
anaphase. Each of these onsets is followed by displacements of the nuclei that
obey the same wavefront pattern. To understand the mitotic wavefronts
theoretically we analyze wavefront propagation in excitable media. We study two
classes of models, one with biochemical signaling and one with mechanical
signaling. We find that the dependence of wavefront speed on cycle number is
most naturally explained by mechanical signaling, and that the entire process
suggests a scenario in which biochemical and mechanical signaling are coupled
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