Isolated output for class-D dc amplifiers

Transformer-coupled output stage is used with pulse-width modulated class-D dc amplifiers. Circuit is comprised of two channels corresponding to negative and positive input signals. Amplitude of secondary-current triangular pulse is function of duration of driving pulse. Therefore, circuit converts pulse-width modulated driving signal to pulse-amplitude modulated signal

Alterations in immunoglobulin levels in uninfected children born to HIV infected women

Background Immunoglobulin levels are known to be elevated in HIV infected children. However, little is known about the effect of maternal HIV infection and the maternal altered immune system on immunoglobulin levels in uninfected children. As few data are available on immunoglobulins from young healthy children, we used data from uninfected children born to hepatitis C virus (HCV) infected women as a comparison. Methods Prospective data on immunoglobulin levels were available from birth to 5 years for children enrolled in the European Collaborative Study (ECS) of children born to HIV-1 infected women and from birth to 24 months for children enrolled in the European Paediatric HCV Network (EPHN). Children born to HIV/HCV co-infected women were excluded. Smoothers (running means) illustrated patterns of immunoglobulins over age by infection status. Associations between infant and maternal factors and child log10 total IgG, IgM and IgA levels were quantified in linear regression analyses allowing for repeated measures within child. Further analyses were performed using only data of HIV exposed uninfected children to investigate associations between child immunoglobulins and maternal immunological and virological factors and anti-retroviral therapy exposure. Results 1751 HIV uninfected, 190 HIV infected children (ECS), 173 HCV uninfected and 30 HCV infected children (EPHN) were included. HIV infected children had higher levels of all immunoglobulins compared to uninfected children over all ages. HIV uninfected children had significantly higher IgG, IgM and IgA levels than HCV uninfected children upto at least 24 months, adjusting for gender, prematurity and race. Prematurity was associated with significantly lower levels of immunoglobulins upto 24 months. Children born to African women had higher IgG and IgA levels upto 24 months than those born to white women but lower IgM in the first 6 months. Among HIV uninfected children higher IgG levels were associated with elevated maternal IgG levels, as well for measurements from 18 months to 5 years of age. No significant effect of maternal CD4 count was observed. ART exposure was associated with significantly lower IgG levels at 6-24 months. Race was not associated with immunoglobulin levels in multivariable analyses in this sub-group. Conclusions These findings indicate significant alterations in immunoglobulin levels in uninfected children born to HIV infected women. This suggests that exposure to an activated maternal immune system is associated with an altered humoral response in children without antigen stimulation, and warrants further research

The Sure Start Mellow Valley area Through the lens of a camera

This report gives an account of a participatory evaluation conducted using photography within the Sure Start Mellow Valley area. Information about the current status of the Sure Start programme and the plans for the future are first provided. The report then describes the research that was undertaken and presents and discusses the findings

Evaluating three frameworks for the value of information: adaptation to task characteristics and probabilistic structure

We identify, and provide an integration of, three frameworks for measuring the informativeness of cues in a multiple-cue judgment task. Cues can be ranked by information value according to expected information gain (Bayesian framework), cue-outcome correlation (Correlational framework), or ecological validity (Ecological framework). In three experiments, all frameworks significantly predicted information acquisition, with the Correlational (then the Bayesian) framework being most successful. Additionally, participants adapted successfully to task characteristics (cue cost, time pressure, and information limitations) – altering the gross amount of information acquired, but not responding to more subtle features of the cues’ information value that would have been beneficial. Rational analyses of our task environments indicate that participants' behavior can be considered successful from a boundedly rational standpoint

The role of impulse parameters in force variability

One of the principle limitations of the human motor system is the ability to produce consistent motor responses. When asked to repeatedly make the same movement, performance outcomes are characterized by a considerable amount of variability. This occurs whether variability is expressed in terms of kinetics or kinematics. Variability in performance is of considerable importance because for tasks requiring accuracy it is a critical variable in determining the skill of the performer. What has long been sought is a description of the parameter or parameters that determine the degree of variability. Two general experimental protocals were used. One protocal is to use dynamic actions and record variability in kinematic parameters such as spatial or temporal error. A second strategy was to use isometric actions and record kinetic variables such as peak force produced. What might be the important force related factors affecting variability is examined and an experimental approach to examine the influence of each of these variables is provided

Successful paediatric HIV treatment in rural primary care in Africa

<p>Objective: Clinical outcomes of HIV-infected children on antiretroviral treatment (ART) in a decentralised, nurse/counsellor-led programme.</p> <p>Design: Clinical cohort.</p> <p>Setting: KwaZulu-Natal, South Africa.</p> <p>Patients: HIV-infected children aged <= 15 years on ART, June 2004-2008.</p> <p>Main outcome measures: Survival according to baseline characteristics including age, WHO clinical stage, haemoglobin and CD4%, was assessed in Kaplan-Meier analyses. Hazard ratios for mortality were estimated using Cox proportional hazards regression and changes in laboratory parameters and weight-for-age z scores after 6-12 months' treatment were calculated.</p> <p>Results: 477 HIV-infected children began ART at a median age of 74 months (range 4-180), median CD4 count (CD4%) of 433 cells/mm(3) (17%) and median HIV viral load of log 4.2 copies/ml; 105 (22%) were on treatment for tuberculosis and 317 (76.6%) were WHO stage 3/4. There were significant increases after ART initiation in CD4% (17% vs 22%; p<0.001), haemoglobin (9.9 vs 11.7 g/l; p <= 0.001) and albumin (30 vs 36 g/l; p <= 0.001). 32 (6.7%) children died over 732 child-years of follow-up (43.7 deaths/1000 child-years; 95% CI 32.7 to 58.2), 17 (53.1%) within 90 days of treatment initiation; median age of death was 84 (IQR 10-181) months. Children with baseline haemoglobin <= 8 g/l were more likely to die (adjusted HR 4.5; 95% CI 1.6 to 12.3), as were those aged <18 months compared with >60 months (adjusted HR 3.2; 95% CI 1.2 to 9.1).</p> <p>Conclusions Good clinical outcomes in HIV-infected children on ART are possible in a rural, decentralised service. Few young children are on ART, highlighting the urgent need to identify HIV-exposed infants.</p&gt

An Analysis of Kinetic Response Variability

Studies evaluating variability of force as a function of absolute force generated are synthesized. Inconsistencies in reported estimates of this relationship are viewed as a function of experimental constraints imposed. Typically, within-subject force variability increases at a negative accelerating rate with equal increments in force produced. Current pulse-step and impulse variability models are unable to accommodate this description, although the notion of efficiency is suggested as a useful construct to explain the description outlined

Development of a Computationally Efficient Fabric Model for Optimization of Gripper Trajectories in Automated Composite Draping

An automated prepreg fabric draping system is being developed which consists of an array of actuated grippers. It has the ability to pick up a fabric ply and place it onto a double-curved mold surface. A previous research effort based on a nonlinear Finite Element model showed that the movements of the grippers should be chosen carefully to avoid misplacement and induce of wrinkles in the draped configuration. Thus, the present study seeks to develop a computationally efficient model of the mechanical behavior of a fabric based on 2D catenaries which can be used for optimization of the gripper trajectories. The model includes bending stiffness, large deflections, large ply shear and a simple contact formulation. The model is found to be quick to evaluate and gives very reasonable predictions of the displacement field

HIV status, breastfeeding modality at 5 months and postpartum maternal weight changes over 24 months in rural South Africa

ObjectiveTo determine the effect of infant feeding practices on postpartum weight change among HIV-infected and -uninfected women in South Africa.MethodsIn a non-randomised intervention cohort study of antiretroviral therapy-naïve women in South Africa, infants were classified as exclusive (EBF), mixed (MF) or non-breastfed (NBF) at each visit. We analysed infant feeding cumulatively from birth to 5 months using 24-hour feeding history (collected weekly for each of the preceding 7 days). Using generalised estimating equation mixed models, allowing for repeated measures, we compared postpartum weight change (kg) from the first maternal postpartum weight within the first 6 weeks (baseline weight) to each subsequent visit through 24 months among 2340 HIV-infected and -uninfected women with live births and at least two postpartum weight measurements.ResultsHIV-infected (?0.2 kg CI: ?1.7 to 1.3 kg; P = 0.81) and -uninfected women (?0.5 kg; 95% CI: ?2.1 to 1.2 kg; P = 0.58) had marginal non-significant weight loss from baseline to 24 months postpartum. Adjusting for HIV status, socio-demographic, pregnancy-related and infant factors, 5-month feeding modality was not significantly associated with postpartum weight change: weight change by 24 months postpartum, compared to the change in the reference EBF group, was 0.03 kg in NBF (95% CI: ?2.5 to +2.5 kg; P = 0.90) and 0.1 kg in MF (95% CI: ?3.0 to +3.2 kg; P = 0.78).ConclusionHIV-infected and -uninfected women experienced similar weight loss over 24 months. Weight change postpartum was not associated with 5-month breastfeeding modality among HIV-infected and -uninfected women.ObjectifDéterminer l'effet des pratiques d'alimentation des nourrissons sur la variation du poids postpartum chez les femmes infectées et non infectées par le VIH en Afrique du Sud.MéthodesDans une étude de cohorte d'intervention non randomisée sur la thérapie aux antirétroviraux, les nourrissons de femmes naïves pour le traitement en Afrique du Sud, ont été classés comme allaités exclusivement au sein (EBF), recevant une alimentation mixte (MF) ou non allaités au sein (NBF), à chaque visite. Nous avons analysé l'alimentation du nourrisson cumulativement de la naissance à cinq mois, en utilisant l'historique de l'alimentation sur 24 heures (recueillies hebdomadairement pour chacun des sept jours précédents). En utilisant l’équation d'estimation des modèles mixtes généralisés, permettant des mesures répétées, nous avons comparé les changements de poids (kg) postpartum de la première mesure du poids postpartum de la mère endéans les six premières semaines (poids de base) au poids à chaque visite subséquente durant 24 mois chez 2340 femmes infectées et non infectées par le VIH, ayant eu des naissances vivantes et au moins deux mesures du poids postpartum.RésultatsLa perte de poids des femmes infectées (-0,2 kg; IC: -1,7 à 1,3 kg; P = 0,81) et non infectées (0,5 kg, IC95%: -2,1 à 1,2 kg; P = 0,58) par le VIH était marginalement non significative de la base à 24 mois postpartum. En ajustant pour le statut VIH et sociodémographique, pour les facteurs liés à la grossesse et infantiles, le mode d'alimentation sur cinq mois n’étaient pas significativement associé à la variation du poids postpartum; la variation de poids sur 24 mois postpartum comparée à celle dans le groupe EBF de référence, était de 0,03 kg chez les NBF (IC95%: -2,5 à 2,5 kg; P = 0,90) et 0,1 kg chez les MF (IC95%: -3,0 à 3,2 kg; P = 0,78).ConclusionLes femmes infectées et non infectées par le VIH connaissent une perte de poids similaire sur 24 mois. La variation du poids postpartum n'a pas été associée au mode d'allaitement à cinq mois chez les femmes infectées et non infectées par le VIH.ObjetivoDeterminar el efecto de las prácticas de alimentación de los bebés en la variación del peso materno postparto entre mujeres infectadas y no infectadas con VIH en Sudáfrica.MétodosEn una intervención en Sudáfrica no aleatorizada, dentro de un estudio de cohortes de mujeres que no habían recibido anteriormente terapia antirretroviral (naive) – los bebés de se clasificaron como recibiendo exclusivamente el pecho (EP), alimentación mixta (AM), o que no eran amamantados (NA) en cada visita. Hemos analizado la alimentación acumulativa del bebé, desde el nacimiento hasta los cinco meses de edad, utilizando un historial de alimentación de 24 horas (recogido semanalmente para los 7 días anteriores). Utilizando modelos mixtos de ecuaciones de estimación generalizadas, permitiendo medidas repetidas, hemos comparado el cambio de peso (kg) durante el postparto - desde la primera pesada dentro de las primeras seis semanas postparto (peso inicial) con cada visita subsiguiente, durante los 24 meses posteriores, para 2340 mujeres - infectadas con VIH y sin infectar – que dieron a luz bebés nacidos vivos y que tenían recogidas al menos dos pesadas postparto.ResultadosLas mujeres infectadas con VIH (-0.2 kg IC: -1.7 – 1.3 kg; P = 0.81) y aquellas no infectadas (-0.5kg; 95% IC: -2.1 – 1.2 kg; P =0.58) tenían una pérdida de peso marginal y no significativa entre el comienzo del estudio hasta los 24 meses después del parto. Ajustando para el estatus de VIH, los factores sociodemográficos y relacionados con el embarazo y el bebé, la modalidad de alimentación del bebé durante sus cinco primeros meses no estaba significativamente asociada con el cambio de peso postparto: el cambio de peso 24 meses después del parto, comparada con el cambio en referencia al grupo EP, era de 0.03 kg en NA (IC 95%: -2.5 – +2.5 kg; P = 0.90) y 0.1 kg en AM (IC 95%: -3.0 – +3.2 kg; P = 0.78).ConclusiónLas mujeres infectadas con VIH y aquellas sin infección experimentaron una pérdida de peso similar en los 24 meses postparto. El cambio de peso no estaba asociado con la modalidad de amamantamiento entre las mujeres VIH positivas y VIH negativas