Assessing the impact of the introduction of the World Health Organization growth standards and weight-for-height z-score criterion on the response to treatment of severe acute malnutrition in children: Secondary data analysis

OBJECTIVE: The objective of our study was to assess the impact of adopting the World Health Organization growth standards and weight-for-height z-score criterion on the response to treatment of severe acute malnutrition in children compared with the use of the National Center for Health Statistics growth reference. METHODS: We used data from children aged 6 to 59 months with acute malnutrition who were admitted to the Médecins sans Frontières nutrition program in Maradi, Niger, during 2006 (N = 56214). Differences in weight gain, duration of treatment, recovery from malnutrition, mortality, loss to follow-up, and need for inpatient care were compared for severely malnourished children identified according to the National Center for Health Statistics reference and weight-for-height <70% of the median criterion versus the World Health Organization standards and the weight-for-height less than -3 z-score criterion. RESULTS: A total of 8 times more children (n = 25754) were classified as severely malnourished according to the World Health Organization standards compared with the National Center for Health Statistics reference (n = 2989). Children included according to the World Health Organization standards had shorter durations of treatment, greater rates of recovery, fewer deaths, and less loss to follow-up or need for inpatient care. CONCLUSIONS: The introduction of the World Health Organization standards with the z-score criterion to identify children for admission into severe acute malnutrition treatment programs would imply the inclusion of children who are younger but have relatively higher weight for height on admission compared with the National Center for Health Statistics reference. These children have fewer medical complications requiring inpatient care and are more likely to experience shorter durations of treatment and lower mortality rates. The World Health Organization standards with the z-score criterion might become a useful tool for the early detection of acute malnutrition in children, although additional research on the resource implications of this transition is required

Contribution of defects to the spin relaxation in copper nanowires

The contributions to the spin relaxation in copper (Cu) nanowires are quantified by carefully analyzing measurements of both charge and spin transport in lateral spin valves as a function of temperature and thickness. The temperature dependence of the spin-flip scattering solely arises from the scattering with phonons, as in bulk Cu, whereas we identify grain boundaries as the main temperature-independent contribution of the defects in the nanowires. A puzzling maximum in the spin diffusion length of Cu at low temperatures is found, which can be explained by the presence of magnetic impurities. The results presented here suggest routes for improving spin transport in metallic nanostructures, otherwise limited by confinement effects.Comment: 10 pages, 4 figures, 1 tabl

La vigencia del pensamiento científico de Santiago Ramón y Cajal

Discurso de Ingreso como Académico Numerari

Vitamin A Supplementation and Other Predictors of Anemia Among Children from Dar Es Salaam, Tanzania.

The associations of hemoglobin, hematocrit, and packed cell volume with socioeconomic factors, malaria, human immunodeficiency virus (HIV) infection, and nutritional status were examined among 687 children admitted to hospital with pneumonia participating in a double blind, placebo-controlled trial of vitamin A supplementation. Children were randomized to receive 2 doses of vitamin A (200,000 IU) or placebo at baseline, and additional doses at 4 and 8 months after discharge from hospital. Hemoglobin levels were measured at enrollment and, on a subset of 161 children, during follow-up. At baseline, hemoglobin concentration was positively associated with the number of possessions in the household, maternal level of education and quality of water supply, and inversely related to malaria infection after controlling for potential confounding variables. Children infected with HIV experienced a significant fall in mean hemoglobin levels over time. The risk of developing severe anemia (< 7 g/dL) during follow-up was lower for children who were breastfed for longer than 18 months as compared to those with less than 6 months of breastfeeding (adjusted prevalence ratio = 0.14, 95% confidence interval [CI] = 0.02, 0.93; P = 0.04), and higher for children over two years of age as compared to 6 to 11 months-old infants (adjusted prevalence ratio = 8.11, 95% CI = 1.2, 55.8; P = 0.03). Children with repeated diagnoses of malaria had 4.1 times the risk of developing severe anemia than did children without the diagnosis (95% CI = 1.3, 13.5; P = 0.02). Vitamin A supplements were associated with an overall nonsignificant reduction of 14% in the risk of developing severe anemia (adjusted prevalence ratio = 0.86, 95% CI = 0.37, 1.99; P = 0.73). We conclude that malaria, HIV infection, low socioeconomic status, and short duration of breastfeeding are strong and independent determinants of adverse hematologic profiles in this population

Temperature dependence of spin diffusion length and spin Hall angle in Au and Pt

We have studied the spin transport and the spin Hall effect as a function of temperature for platinum (Pt) and gold (Au) in lateral spin valve structures. First, by using the spin absorption technique, we extract the spin diffusion length of Pt and Au. Secondly, using the same devices, we have measured the spin Hall conductivity and analyzed its evolution with temperature to identify the dominant scattering mechanisms behind the spin Hall effect. This analysis confirms that the intrinsic mechanism dominates in Pt whereas extrinsic effects are more relevant in Au. Moreover, we identify and quantify the phonon-induced skew scattering. We show that this contribution to skew scattering becomes relevant in metals such as Au, with a low residual resistivity.Comment: 13 pages, 5 figure

Temperature dependence of spin polarization in ferromagnetic metals using lateral spin valves

A high reproducibility in the performance of cobalt/copper and permalloy/copper lateral spin valves with transparent contacts is obtained by optimizing the interface quality and the purity of copper. This allows us to study comprehensively the spin injection properties of both ferromagnetic materials, as well as the spin transport properties of copper, which are not affected by the used ferromagnetic material, leading to long spin diffusion lengths. Spin polarizations of permalloy and cobalt are obtained as a function of temperature. Analysis of the temperature dependence of both the spin polarization and conductivity of permalloy using the standard two-channel model for ferromagnetic metals suggests that a correction factor of ~2 is needed for the spin polarization values obtained by lateral spin valve experiments.Comment: 16 pages, 5 figures, 1 tabl

Pattern and Predictors of Weight Gain During Pregnancy Among HIV-1-Infected Women from Tanzania

Progression of HIV disease is often accompanied by weight loss and wasting. Gestational weight gain is a strong determinant of maternal and neonatal outcomes; however, the pattern and predictors of weight gain during pregnancy among HIV-positive women are unknown. We obtained monthly anthropometric measurements in a cohort of 957 pregnant women from Tanzania who were HIV infected. We estimated the weekly rate of weight gain at various points during the second and third trimesters of pregnancy and computed rate differences between levels of sociodemographic, nutritional, immunologic, and parasitic variables at the first prenatal visit. The change in mid-upper arm circumference (MUAC) from baseline to delivery was also examined. The rate of weight gain decreased progressively during pregnancy. There was an average decline of 1 cm in MUAC between weeks 12 and 38. Lower level of education and helminthic infections at first visit were associated with decreased adjusted rates of weight gain during the third trimester. High baseline MUAC, not contributing to household income, lower serum retinol and selenium concentrations, advanced clinical stage of HIV disease, and malaria infection were related to decreased rates of weight gain during the second trimester. Low baseline CD4 T-cell counts were related to a poorer pattern of weight gain throughout pregnancy. Prevention and treatment of parasitic infections and improvement of nutritional status are likely to enhance the pattern of gestational weight gain among HIV-infected women