High energy processes in clusters of galaxies and the origin of cosmic rays

We test the hypothesis of a universal cosmic ray intensity by calculating the secondary electron or positron production in the hadronic interactions of cosmic ray nuclei with intergalactic gas within clusters of galaxies. We find that the spectral characteristics of the radio synchrotron emission by these secondary electrons is not consistent with observations of the Coma cluster. Thus the hypothesis can be ruled out on cluster scales.published_or_final_versio

Pulsar Wind Origin of Cosmic Ray Positrons

We show that the electron-positron pairs produced in the magnetosphere of a pulsar can be accelerated monoenergetically to relativistic energies in the wind driven by low-frequency electromagnetic waves. The final achievable energy, depending on the surface magnetic field and rotation period of the individual pulsar, is mostly in the range 10-2--102 GeV. Based on the pair production rate of the individual pulsars and the Galactic pulsar population, the electron-positron flux from the Galactic pulsars is estimated from a statistical analysis of the observed pulsar data. We find that the flux is enough to account for the measured positron fraction and that its energy spectrum well matches the measured one. Our model predicts that the positron fraction will rise with increasing energy until its peak value at 30 GeV and then drop off.published_or_final_versio

Biophysical interactions in tropical agroforestry systems

sequential systems, simultaneous systems Abstract. The rate and extent to which biophysical resources are captured and utilized by the components of an agroforestry system are determined by the nature and intensity of interac-tions between the components. The net effect of these interactions is often determined by the influence of the tree component on the other component(s) and/or on the overall system, and is expressed in terms of such quantifiable responses as soil fertility changes, microclimate modification, resource (water, nutrients, and light) availability and utilization, pest and disease incidence, and allelopathy. The paper reviews such manifestations of biophysical interactions in major simultaneous (e.g., hedgerow intercropping and trees on croplands) and sequential (e.g., planted tree fallows) agroforestry systems. In hedgerow intercropping (HI), the hedge/crop interactions are dominated by soil fertility improvement and competition for growth resources. Higher crop yields in HI than in sole cropping are noted mostly in inherently fertile soils in humid and subhumid tropics, and are caused by large fertility improvement relative to the effects of competition. But, yield increases are rare in semiarid tropics and infertile acid soils because fertility improvement does not offse

Familial and cultural perceptions and beliefs of oral hygiene and dietary practices among ethnically and socio-economically diverse groups

Objective: The aim of this international study was to develop a valid and reliable psychometric measure to examine the extent to which parents' attitudes about engaging in twice-daily tooth brushing and controlling sugar snacking predict these respective behaviours in their children. A supplementary objective was to assess whether ethnic group, culture, level of deprivation or children's caries experience impact upon the relationships between oral health related behaviours, attitudes to these respective behaviours and to dental caries. Clinical setting: nurseries, health centres and dental clinics in 17 countries. Participants: 2822 children aged 3 to 4 years and their parents. Main outcome measures: Dental examination of children and questionnaire to parents. Results: factor analysis identified 8 coherent attitudes towards toothbrushing, sugar snacking and childhood caries. Attitudes were significantly different in families from deprived and non-deprived backgrounds and in families of children with and without caries. Parents' perception of their ability to control their children's toothbrushing and sugar snacking habits were the most significant predictors of whether or not favourable habits were reported. Some differences were found by site and ethnic group. Conclusions: this study supports the hypothesis that parental attitudes significantly impact on the establishment of habits favourable to oral health. An appreciation of the impact of cultural and ethnic diversity is important in understanding how parental attitudes to oral health vary. Further research should examine in a prospective intervention whether enhancing parenting skills is an effective route to preventing childhood caries.link_to_subscribed_fulltex

Adherence and side effects of three ferrous sulfate treatment regimens on anemic pregnant women in clinical trials Adesão e efeitos colaterais em ensaio clínico comparando três esquemas de tratamento com sulfato ferroso em gestantes anêmicas

The objective of this study was to analyze adherence and side effects of three iron supplement regimens (ferrous sulfate) on anemic pregnant women. The clinical trial involved 150 women between the 16th and 20th gestational weeks, at low obstetric risk and with hemoglobin concentration of between 8.0 and 11.0g/dL. Treatment was provided by ferrous sulfate with 60mg of elemental iron during 16 (± 1) weeks, in three regimens: single tablet a week (n = 48); single tablet twice a week (n = 53) or single tablet a day (n = 49). The outcomes were adherence, assessed through interviews and by counting tablets, and side effects, according to patient information. The adherence showed a declining trend (92%, 83% and 71%; p = 0.010) and the side effects revealed a growing trend (40%, 45% and 71%; p = 0.002) as the dosage increased. Diarrhea and epigastric pain were significantly associated with the dose administered (p = 0.002). These results suggest that in anemic pregnant women, complaints are directly proportional and the compliance is inversely proportional to the amount of medicinal iron.<br>O objetivo deste estudo foi analisar a adesão e os efeitos colaterais de três esquemas de suplementação com sulfato ferroso em gestantes anêmicas. O ensaio clínico incluiu 150 mulheres entre a 16ª e 20ª semanas de gestação, de baixo risco obstétrico e com concentração de hemoglobina entre 8,0 e 11,0g/dL. A intervenção foi realizada com 60mg de ferro elementar, durante 16 (±1) semanas, em três esquemas: uma drágea semanal (n = 48); uma drágea duas vezes por semana (n = 53) ou uma drágea diariamente (n = 49). Os desfechos foram adesão, verificada por entrevista e contagem das drágeas, e efeitos colaterais auto-relatados pelas pacientes. A adesão apresentou tendência declinante (92%, 83% e 71%; p = 0,010) e os efeitos colaterais, ascendente (40%, 45% e 71%; p = 0,002) com o aumento da dose prescrita. Diarréia e dor epigástrica estiveram significativamente associadas à dose administrada (p = 0,002). Os resultados sugerem que em gestantes anêmicas as queixas e a adesão ao tratamento com sulfato ferroso são, respectivamente, direta e inversamente proporcionais à quantidade do ferro medicamentoso