1,875 research outputs found

    Survey of children accessing HIV services in a high prevalence setting: time for adolescents to count?

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    OBJECTIVE: To establish the proportion of adolescents among children infected with human immunodeficiency virus (HIV) in Zimbabwe who receive HIV care and support, and what clinic staff perceives to be the main problems faced by HIV-infected children and adolescents. METHODS: In July 2008, we sent a questionnaire to all 131 facilities providing HIV care in Zimbabwe. In it we requested an age breakdown of the children (aged 0-19 years) registered for care and asked what were the two major problems faced by younger children (0-5 years) and adolescents (10-19 years). FINDINGS: Nationally, 115 (88%) facilities responded. In 98 (75%) that provided complete data, 196 032 patients were registered and 24 958 (13%) of them were children. Of children under HIV care, 33% were aged 0-4 years; 25%, 5-9 years; 25%, 10-14 years; and 17%, 15-19 years. Staff highlighted differences in the problems most commonly faced by younger children and adolescents. For younger children, such problems were malnutrition and lack of appropriate drugs (cited by 46% and 40% of clinics, respectively); for adolescents they concerned psychosocial issues and poor drug adherence (cited by 56% and 36%, respectively). CONCLUSION: Interventions for the large cohort of adolescents who are receiving HIV care in Zimbabwe need to target the psychosocial concerns and poor drug adherence reported by staff as being the main concerns in this age group

    Geometrical effects on the optical properties of quantum dots doped with a single magnetic atom

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    The emission spectra of individual self-assembled quantum dots containing a single magnetic Mn atom differ strongly from dot to dot. The differences are explained by the influence of the system geometry, specifically the in-plane asymmetry of the quantum dot and the position of the Mn atom. Depending on both these parameters, one has different characteristic emission features which either reveal or hide the spin state of the magnetic atom. The observed behavior in both zero field and under magnetic field can be explained quantitatively by the interplay between the exciton-manganese exchange interaction (dependent on the Mn position) and the anisotropic part of the electron-hole exchange interaction (related to the asymmetry of the quantum dot).Comment: 5 pages, 5 figures, to be published in Phys. Rev. Let

    The social fabric of Jeans': Assessing the social: Coupling social simulation and assessment methods

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    International audienceThe culture and manufacturing of the cotton fabric used to make your Jeans’ may have implied the use of fertilizers or pesticides polluting a water basin, have led to relocating people and even of children labour at different stages of its fabrication. As a consumer you probably didn’t take all these consequences into account (for your sake most of the information is not available, or value-wise you feel unconcerned) and you surely preferred to buy the cheapest one or to follow the fashion trend. Basically, every economic or public activity has repercussions directly, or through a chain of consequences on the environment and the society. In order to try and measure those impacts, or to valuate one choice (Jeans’ L) compared to another (Jeans’ P&J), several assessment methods have been developed and are frequently used. As a self-evident truth, assessment methods are instruments used to evaluate something. These could include measuring a performance on a specific case. In terms of evaluating policies and strategies, their possible outcomes are intended to evaluate their potential impacts. This refers to impact assessment in which past (already implemented actions) or future (ex-ante analysis) performances are studied

    Acquired epidermodysplasia verruciformis due to multiple and unusual HPV infection among vertically-infected, HIV-positive adolescents in Zimbabwe.

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    BACKGROUND: We have previously described the presentation of epidermodysplasia verruciformis (EV)-like eruptions in almost a quarter of hospitalized adolescents with vertically-acquired human immunodeficiency virus (HIV) infection in Harare, Zimbabwe, a region with a high prevalence of HIV infection. METHODS: We performed a clinical case note review and skin biopsy from affected sites in 4 HIV-infected adolescents with EV-like lesions in Harare. Biopsies were processed for histology and for human papillomavirus (HPV) typing. RESULTS: All patients had long-standing skin lesions that pre-dated the diagnosis of HIV by several years. The histology of skin biopsies from all patients was consistent with EV. In each biopsy, EV-associated β-HPV type 5 was identified (additionally, type 19 was found in 1 biopsy). Cutaneous wart-associated HPV types 1 and 2 were detected in all biopsies, together with genital lesion-associated HPV types 6, 16, and 52, (as well as ≥3 other genital lesion-associated HPV types). Despite immune reconstitution with combination antiretroviral therapy (cART), there was no improvement in EV-like lesions in any patient. CONCLUSIONS: EV is a disfiguring and potentially stigmatizing condition among this patient group and is difficult to treat; cART appears to have no impact on the progression of skin disease. Among adolescents with longstanding HIV-induced immunosuppression and with high levels of sun exposure, close dermatological surveillance for potential skin malignancy is required

    Observation of strong-coupling effects in a diluted magnetic semiconductor (Ga,Fe)N

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    A direct observation of the giant Zeeman splitting of the free excitons in (Ga,Fe)N is reported. The magnetooptical and magnetization data imply the ferromagnetic sign and a reduced magnitude of the effective p-d exchange energy governing the interaction between Fe^{3+} ions and holes in GaN, N_0 beta^(app) = +0.5 +/- 0.2 eV. This finding corroborates the recent suggestion that the strong p-d hybridization specific to nitrides and oxides leads to significant renormalization of the valence band exchange splitting.Comment: 4 pages, 2 figure

    Observation of Fragile-to-Strong Dynamic Crossover in Protein Hydration Water

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    At low temperatures proteins exist in a glassy state, a state which has no conformational flexibility and shows no biological functions. In a hydrated protein, at and above 220 K, this flexibility is restored and the protein is able to sample more conformational sub-states, thus becomes biologically functional. This 'dynamical' transition of protein is believed to be triggered by its strong coupling with the hydration water, which also shows a similar dynamic transition. Here we demonstrate experimentally that this sudden switch in dynamic behavior of the hydration water on lysozyme occurs precisely at 220 K and can be described as a Fragile-to-Strong dynamic crossover (FSC). At FSC, the structure of hydration water makes a transition from predominantly high-density (more fluid state) to low-density (less fluid state) forms derived from existence of the second critical point at an elevated pressure.Comment: 6 pages (Latex), 4 figures (Postscript

    Inverse problem and Bertrand's theorem

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    The Bertrand's theorem can be formulated as the solution of an inverse problem for a classical unidimensional motion. We show that the solutions of these problems, if restricted to a given class, can be obtained by solving a numerical equation. This permit a particulary compact and elegant proof of Bertrand's theorem.Comment: 11 pages, 3 figure

    Magneto-optical spectroscopy of (Ga,Mn)N epilayers

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    We report on the magneto-optical spectroscopy and cathodoluminescence of a set of wurtzite (Ga,Mn)N epilayers with a low Mn content, grown by molecular beam epitaxy. The sharpness of the absorption lines associated to the Mn3+^{3+} internal transitions allows a precise study of its Zeeman effect in both Faraday and Voigt configurations. We obtain a good agreement if we assume a dynamical Jahn-Teller effect in the 3d4^{4} configuration of Mn, and we determine the parameters of the effective Hamiltonians describing the 5T_2^{5}T\_{2} and 5E^{5}E levels, and those of the spin Hamiltonian in the ground spin multiplet, from which the magnetization of the isolated ion can be calculated. On layers grown on transparent substrates, transmission close to the band gap, and the associated magnetic circular dichroism, reveal the presence of the giant Zeeman effect resulting from exchange interactions between the Mn3+^{3+} ions and the carriers. The spin-hole interaction is found to be ferromagnetic
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