Ferromagnetic relaxation by magnon-induced currents

A theory for calculating spin wave relaxation times based on the magnon-electron interaction is developed. The theory incorporates a thin film geometry and is valid for a large range of magnon frequencies and wave vectors. For high conductivity metals such as permalloy, the wave vector dependent damping constant approaches values as high as 0.2, showing the large magnitude of the effect, and can dominate experimentally observed relaxation.Comment: 5 pages, 4 figure

Think coalitions in contemplrary Argentine

Este artículo analiza el fracaso de los procesos de conversión de las coaliciones electorales en coaliciones de gobierno, y la difícil institucionalización de las coaliciones en Argentina, desde una perspectiva de estudio interesada en destacar la articulación entre factores históricos de larga duración y transformaciones políticas recientes. Desde este ángulo de preocupaciones, se sostiene que las coaliciones fueron más un instrumento de construcción de hegemonía en clave de gobierno de “unidad nacional” que un sistema de pactos inspirado en el principio del poder compartido.This article analyzes the failure of the processes of conversion of the electoral coalitions in coalitions of government, and the difficult institutionalization of the coalitions in Argentina, from a perspective of study interested in emphasizing the joint between historical factors of long duration and political recent transformations. From this angle of worries, is held that the coalitions were more an instrument of construction of hegemony in key of government of “national unit” that a system of agreements inspired by the beginning of the shared power.Fil: Tcach, Cesar Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones y Estudios Sobre Cultura y Sociedad. Universidad Nacional de Córdoba. Centro de Investigaciones y Estudios Sobre Cultura y Sociedad; Argentin

Data Resource Profile: Countdown to 2015: Maternal, Newborn and Child Survival

The Countdown to 2015 country profiles present, in one place, comprehensive evidence to enable an assessment of a country's progress in improving reproductive, maternal, newborn and child health. Profiles are available for each of the 75 countries that together account for more than 95% of all maternal and child deaths. The two-page profiles are updated approximately every 2 years with new data and analyses. Profile data include demographics, mortality, nutritional status, coverage of evidence-based interventions, within-countries inequalities in coverage, measures of health system functionality, supportive policies and financing indicators. The main sources of data for the coverage, nutritional status and equity indicators are the US Agency for Internal Development (USAID)-supported demographic and health surveys and the United Nations Children's Fund (UNICEF)-supported multiple indicator cluster surveys. Data on coverage are first summarized and checked for quality by UNICEF, and data on equity in intervention coverage are summarized and checked by the Federal University of Pelotas. The mortality estimates are developed by the Inter-agency Group for Child Mortality Estimation and the Maternal Mortality Estimation Inter-Agency Group. The financing data are abstracted from datasets maintained by the Organization for Economic Co-operation and Development Assistance Committee, and the policies and health systems data are derived from a special compilation prepared by the World Health Organization. Associated country profiles include equity-specific profiles and one-page profiles prepared annually that report on the 11 indicators selected by the Commission on Information and Accountability for Women's and Children's Healt

The transcription factor Foxo1 controls germinal center B cell proliferation in response to T cell help

Germinal center (GC) B cells cycle between two states, the light zone (LZ) and the dark zone (DZ), and in the latter they proliferate and hypermutate their immunoglobulin genes. How this functional transition takes place is still controversial. In this study, we demonstrate that ablation of Foxo1 after GC development led to the loss of the DZ GC B cells and disruption of the GC architecture, which is consistent with recent studies. Mechanistically, even upon provision of adequate T cell help, Foxo1-deficient GC B cells showed less proliferative expansion than controls. Moreover, we found that the transcription factor BATF was transiently induced in LZ GC B cells in a Foxo1-dependent manner and that deletion of BATF similarly led to GC disruption. Thus, our results are consistent with a model where the switch from the LZ to the DZ is triggered after receipt of T cell help, and suggest that Foxo1-mediated BATF up-regulation is at least partly involved in this switch

Testing the limits of human vision with quantum states of light: past, present, and future experiments

The human eye contains millions of rod photoreceptor cells, and each one is a single-photon detector. Whether people can actually see a single photon, which requires the rod signal to propagate through the rest of the noisy visual system and be perceived in the brain, has been the subject of research for nearly 100 years. Early experiments hinted that people could see just a few photons, but classical light sources are poor tools for answering these questions. Single-photon sources have opened up a new area of vision research, providing the best evidence yet that humans can indeed see single photons, and could even be used to test quantum effects through the visual system. We discuss our program to study the lower limits of human vision with a heralded single-photon source based on spontaneous parametric downconversion, and present two proposed experiments to explore quantum effects through the visual system: testing the perception of superposition states, and using a human observer as a detector in a Bell test.Comment: 7 pages, 6 figure

Using genotype abundance to improve phylogenetic inference

Modern biological techniques enable very dense genetic sampling of unfolding evolutionary histories, and thus frequently sample some genotypes multiple times. This motivates strategies to incorporate genotype abundance information in phylogenetic inference. In this paper, we synthesize a stochastic process model with standard sequence-based phylogenetic optimality, and show that tree estimation is substantially improved by doing so. Our method is validated with extensive simulations and an experimental single-cell lineage tracing study of germinal center B cell receptor affinity maturation

Exchange coupled perpendicular media

The potential of exchange spring bilayers and graded media is reviewed. An analytical model for the optimization of graded media gives an optimal value of the magnetic polarization of Js = 0.8 T. The optimum design allows for thermally stable grains with grain diameters in the order of 3.3 nm, which supports ultra high density up to 5 to 10 Tbit per inch2. The switching field distribution is significantly reduced in bilayer media and graded media compared to single phase media. For the graded media the switching field distribution is reduced by about a factor of two. For bilayer media the minimum switching field distribution is obtained for soft layer anisotropies about one fifth of the hard layer anisotropy. The influence of precessional switching on the reversal time and the reversal field is investigated in detail for magnetic bilayers. Exchange spring bilayers can be reversed with field pulses of 20 ps.Comment: submitted to JMMM, 'Current Perspectives; Perpendicular recording

Optimizing community case management strategies to achieve equitable reduction of childhood pneumonia mortality:An application of Equitable Impact Sensitive Tool (EQUIST) in five low- and middle-income countries

BACKGROUND: The aim of this study was to populate the Equitable Impact Sensitive Tool (EQUIST) framework with all necessary data and conduct the first implementation of EQUIST in studying cost–effectiveness of community case management of childhood pneumonia in 5 low– and middle–income countries with relation to equity impact. METHODS: Wealth quintile–specific data were gathered or modelled for all contributory determinants of the EQUIST framework, namely: under–five mortality rate, cost of intervention, intervention effectiveness, current coverage of intervention and relative disease distribution. These were then combined statistically to calculate the final outcome of the EQUIST model for community case management of childhood pneumonia: US$ per life saved, in several different approaches to scaling–up. RESULTS: The current ‘mainstream’ approach to scaling–up of interventions is never the most cost–effective. Community–case management appears to strongly support an ‘equity–promoting’ approach to scaling–up, displaying the highest levels of cost–effectiveness in interventions targeted at the poorest quintile of each study country, although absolute cost differences vary by context. CONCLUSIONS: The relationship between cost–effectiveness and equity impact is complex, with many determinants to consider. One important way to increase intervention cost–effectiveness in poorer quintiles is to improve the efficiency and quality of delivery. More data are needed in all areas to increase the accuracy of EQUIST–based estimates

First-Borns Carry a Higher Metabolic Risk in Early Adulthood: Evidence from a Prospective Cohort Study

Background: Birth order has been associated with early growth variability and subsequent increased adiposity, but the consequent effects of increased fat mass on metabolic risk during adulthood have not been assessed. We aimed to quantify the metabolic risk in young adulthood of being first-born relative to those born second or subsequently.Methodology and Principal Findings: Body composition and metabolic risk were assessed in 2,249 men, aged 17-19 years, from a birth cohort in southern Brazil. Metabolic risk was assessed using a composite z-score integrating standardized measurements of blood pressure, total cholesterol, high density lipoprotein, triglycerides and fat mass. First-borns had lower birth weight z-score (Delta = -0.25, 95%CI -0.35, -0.15, p<0.001) but showed greater weight gain during infancy (change in weight z-score from birth to 20 months: Delta = 0.39, 95%CI 0.28-0.50, P<0.0001) and had greater mean height (Delta = 1.2 cm, 95%CI: 0.7-1.6, p<0.0001) and weight (Delta = 0.34 kg, 95%CI: 0.13-0.55, p<0.002) at 43 months. This greater weight and height tracked into early adulthood, with first-borns being significantly taller, heavier and with significantly higher fat mass than later-borns. The metabolic risk z-score was significantly higher in first-borns.Conclusions/Significance: First-born status is associated with significantly elevated adiposity and metabolic risk in young adult men in Brazil. Our results, linking cardiovascular risk with life history variables, suggest that metabolic risk may be associated with the worldwide trend to smaller family size and it may interact with changes in behavioural or environmental risk factors

Class-switched anti-insulin antibodies originate from unconventional antigen presentation in multiple lymphoid sites

Autoantibodies to insulin are a harbinger of autoimmunity in type 1 diabetes in humans and in non-obese diabetic mice. To understand the genesis of these autoantibodies, we investigated the interactions of insulin-specific T and B lymphocytes using T cell and B cell receptor transgenic mice. We found spontaneous anti-insulin germinal center (GC) formation throughout lymphoid tissues with GC B cells binding insulin. Moreover, because of the nature of the insulin epitope recognized by the T cells, it was evident that GC B cells presented a broader repertoire of insulin epitopes. Such broader recognition was reproduced by activating naive B cells ex vivo with a combination of CD40 ligand and interleukin 4. Thus, insulin immunoreactivity extends beyond the pancreatic lymph node–islets of Langerhans axis and indicates that circulating insulin, despite its very low levels, can have an influence on diabetogenesis