228 research outputs found

    Impact of asymmetries on fuel performance in inertial confinement fusion

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    Low-mode asymmetries prevent effective compression, confinement, and heating of the fuel in inertial confinement fusion (ICF) implosions, and their control is essential to achieving ignition. Ion temperatures (Tion) in ICF experiments are inferred from the broadening of primary neutron spectra. Directional motion (flow) of the fuel at burn also impacts broadening and will lead to artificially inflated "Tion" values. Flow due to low-mode asymmetries is expected to give rise to line-of-sight variations in measured Tion. We report on intentionally asymmetrically driven experiments at the OMEGA laser facility designed to test the ability to accurately predict and measure line-of-sight differences in apparent Tion due to low-mode asymmetry-seeded flows. Contrasted to chimera and xrage simulations, the measurements demonstrate how all asymmetry seeds have to be considered to fully capture the flow field in an implosion. In particular, flow induced by the stalk that holds the target is found to interfere with the seeded asymmetry. A substantial stalk-seeded asymmetry in the areal density of the implosion is also observed

    Overweight and obesity in urban Africa: A problem of the rich or the poor?

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    BACKGROUND: Obesity is a well recognized risk factor for various chronic diseases such as cardiovascular diseases, hypertension, and type 2 diabetes mellitus. The aim of this study was to shed light on the patterns of overweight and obesity in sub-Saharan Africa, with special interest in differences between the urban poor and the urban non-poor. The specific goals were to describe trends in overweight and obesity among urban women; and examine how these trends vary by education and household wealth. METHODS: The paper used Demographic and Health Surveys data from seven African countries where two surveys had been carried out with an interval of at least 10 years between them. Among the countries studied, the earliest survey took place in 1992 and the latest in 2005. The dependent variable was body mass index coded as: Not overweight/obese; Overweight; Obese. The key covariates were time lapse between the two surveys; woman's education; and household wealth. Control variables included working status, age, marital status, parity, and country. Multivariate ordered logistic regression in the context of the partial proportional odds model was used. RESULTS: Descriptive results showed that the prevalence of urban overweight/obesity increased by nearly 35% during the period covered. The increase was higher among the poorest (+50%) than among the richest (+7%). Importantly, there was an increase of 45-50% among the non-educated and primary-educated women, compared to a drop of 10% among women with secondary education or higher. In the multivariate analysis, the odds ratio of the variable time lapse was 1.05 (p < 0.01), indicating that the prevalence of overweight/obesity increased by about 5% per year on average in the countries in the study. While the rate of change in urban overweight/obesity did not significantly differ between the poor and the rich, it was substantially higher among the non-educated women than among their educated counterparts. CONCLUSION: Overweight and obesity are on the rise in Africa and might take epidemic proportions in the near future. Like several other public health challenges, overweight and obesity should be tackled and prevented early as envisioned in the WHO Global strategy on diet, physical activity and health

    Atomic Force Microscopy Study of the Kinetic Roughening in Nanostructured Gold Films on SiO2

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    Dynamic scaling behavior has been observed during the room-temperature growth of sputtered Au films on SiO2using the atomic force microscopy technique. By the analyses of the dependence of the roughness, σ, of the surface roughness power,P(f), and of the correlation length,ξ, on the film thickness,h, the roughness exponent,α = 0.9 ± 0.1, the growth exponent,β = 0.3 ± 0.1, and the dynamic scaling exponent,z = 3.0 ± 0.1 were independently obtained. These values suggest that the sputtering deposition of Au on SiO2at room temperature belongs to a conservative growth process in which the Au grain boundary diffusion plays a dominant role

    Early identification of young children at risk for poor academic achievement: preliminary development of a parent-report prediction tool

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    <p>Abstract</p> <p>Background</p> <p>Early school success is clearly related to later health. A prediction index that uses parent report to assess children's risk for poor academic achievement could potentially direct targeted service delivery to improve child outcomes.</p> <p>Methods</p> <p>We obtained risk factors through literature review and used the National Longitudinal Survey of Youth 1979 Child Files to examine the predictive associations of these factors with academic achievement scores.</p> <p>Results</p> <p>Twenty predictors were identified including four strong predictors (maternal education, child gender, family income, and low birth weight). Significantly, 12 predictors explained 17-24% of score variance.</p> <p>Conclusions</p> <p>Parent-reported factors provide predictive accuracy for academic achievement.</p

    Stakeholder analysis for a maternal and newborn health project in Eastern Uganda

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    Background Based on the realization that Uganda is not on track to achieving Millennium Development Goals 4 and 5, Makerere University School of Public Health in collaboration with other partners proposed to conduct two community based maternal/newborn care interventions aimed at increasing access to health facility care through transport vouchers and use of community health workers to promote ideal family care practices. Prior to the implementation, a stakeholder analysis was undertaken to assess and map stakeholders’ interests, influence/power and position in relation to the interventions; their views regarding the success and sustainability; and how this research can influence policy formulation in the country. Methods A stakeholder analysis was carried out in March 2011 at national level and in four districts of Eastern Uganda where the proposed interventions would be conducted. At the national level, four key informant interviews were conducted with the ministry of health representative, Member of Parliament, and development partners. District health team members were interviewed and also engaged in a workshop; and at community level, twelve focus group discussions were conducted among women, men and motorcycle transporters. Results This analysis revealed that district and community level stakeholders were high level supporters of the proposed interventions but not drivers. At community level the mothers, their spouses and transporters were of low influence due to the limited funds they possessed. National level and district stakeholders believed that the intervention is costly and cannot be affordably scaled up. They advised the study team to mobilize and sensitize the communities to contribute financially from the start in order to enhance sustainability beyond the study period. Stakeholders believed that the proposed interventions will influence policy through modeling on how to improve the quality of maternal/newborn health services, male involvement, and improved accessibility of services. Conclusion Most of the stakeholders interviewed were supporters of the proposed maternal and newborn care intervention because of the positive benefits of the intervention. The analysis highlighted stakeholder concerns that will be included in the final project design and that could also be useful in countries of similar setting that are planning to set up programmes geared at increasing access to maternal and new born interventions. Key among these concerns was the need to use both human and financial resources that are locally available in the community, to address supply side barriers that influence access to maternal and child healthcare. Research to policy translation, therefore, will require mutual trust, continued dialogue and engagement of the researchers, implementers and policy makers to enable scale up.UKai

    Modifier Effects between Regulatory and Protein-Coding Variation

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    Genome-wide associations have shown a lot of promise in dissecting the genetics of complex traits in humans with single variants, yet a large fraction of the genetic effects is still unaccounted for. Analyzing genetic interactions between variants (epistasis) is one of the potential ways forward. We investigated the abundance and functional impact of a specific type of epistasis, namely the interaction between regulatory and protein-coding variants. Using genotype and gene expression data from the 210 unrelated individuals of the original four HapMap populations, we have explored the combined effects of regulatory and protein-coding single nucleotide polymorphisms (SNPs). We predict that about 18% (1,502 out of 8,233 nsSNPs) of protein-coding variants are differentially expressed among individuals and demonstrate that regulatory variants can modify the functional effect of a coding variant in cis. Furthermore, we show that such interactions in cis can affect the expression of downstream targets of the gene containing the protein-coding SNP. In this way, a cis interaction between regulatory and protein-coding variants has a trans impact on gene expression. Given the abundance of both types of variants in human populations, we propose that joint consideration of regulatory and protein-coding variants may reveal additional genetic effects underlying complex traits and disease and may shed light on causes of differential penetrance of known disease variants

    Image perception and interpretation of abnormalities; can we believe our eyes? Can we do something about it?

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    The radiologist’s visual impression of images is transmitted, via non-visual means (the report), to the clinician. There are several complex steps from the perception of the images by the radiologist to the understanding of the impression by the clinician. With a process as complex as this, it is no wonder that errors in perception, cognition, interpretation, transmission and understanding are very common. This paper reviews the processes of perception and error generation and possible strategies for minimising them

    An In Vitro System for Studying Murid Herpesvirus-4 Latency and Reactivation

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    The narrow species tropisms of Epstein-Barr Virus (EBV) and the Kaposi's Sarcoma -associated Herpesvirus (KSHV) have made Murid Herpesvirus-4 (MuHV-4) an important tool for understanding how gammaherpesviruses colonize their hosts. However, while MuHV-4 pathogenesis studies can assign a quantitative importance to individual genes, the complexity of in vivo infection can make the underlying mechanisms hard to discern. Furthermore, the lack of good in vitro MuHV-4 latency/reactivation systems with which to dissect mechanisms at the cellular level has made some parallels with EBV and KSHV hard to draw. Here we achieved control of the MuHV-4 lytic/latent switch in vitro by modifying the 5′ untranslated region of its major lytic transactivator gene, ORF50. We terminated normal ORF50 transcripts by inserting a polyadenylation signal and transcribed ORF50 instead from a down-stream, doxycycline-inducible promoter. In this way we could establish fibroblast clones that maintained latent MuHV-4 episomes without detectable lytic replication. Productive virus reactivation was then induced with doxycycline. We used this system to show that the MuHV-4 K3 gene plays a significant role in protecting reactivating cells against CD8+ T cell recognition

    Early Infant Morbidity in the City of São Paulo, Brazil

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    BACKGROUND: Early infant morbidities may produce adverse outcomes in subsequent life. A low Apgar score is a convenient measure of early infant morbidity. We study determinants of early infant morbidity (sex, plurality, mode of delivery, prior losses, gestational age, prenatal care and birth weight, parity and maternal age, race, maternal education and community development) for the 1998-birth cohort, City of São Paulo, Brazil. METHODS: This study identified all deliveries that took place in the City of São Paulo during 1998. Information was extracted from 209,628 birth records. We used multivariate logistic regression to assess the effect of each independent variable on Apgar score less than seven at one minute and Apgar score less than seven at five minutes. RESULTS: Low birth weight, prematurity and community development were found to be strong predictors of morbidity. Maternal education showed strong negative correlation with both Apgar scores. The negative correlations between maternal schooling and Apgar scores were observed after prenatal care, parity and maternal age were included in the model. Unmeasured proximate factors may thus be the true source of disparity between educational groups. Children of very young adolescent mothers had lower Apgar scores at one minute (but not at five minutes) than those born to mothers 15 to 19. Parity one or higher was associated with decreased odds of low Apgar scores. Cesarean section and operative delivery were associated with higher odds of early infant morbidity. CONCLUSION: Education may allow mothers to have better care in the peripartum period. More educated mothers may be more likely to recognize certain morbidities through the pregnancy period and the monitoring of such morbidities yields better infant outcomes. Also, having less than seven prenatal care visits was found to predict early infant morbidity and one way to increase the use of such services is to focus on aspects of care that may lead to easier accessibility and continuity of prenatal care. Physicians should inform mothers about the risks associated with high number of children for a next infant and also about the risks for the infant associated with unnecessary cesarean sections. Special attention should be paid to adolescent mothers, since much of their increased risk is likely to be minimized by counseling
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