Local energy transfer and dissipation in incompressible Hall magnetohydrodynamic turbulence: The coarse-graining approach.

We derive the coarse-graining (CG) equations of incompressible Hall magnetohydrodynamic (HMHD) turbulence to investigate the local (in space) energy transfer rate as a function of the filtering scale ℓ. First, the CG equations are space averaged to obtain the analytical expression of the mean cascade rate. Its application to three-dimensional simulations of (weakly compressible) HMHD shows a cascade rate consistent with the value of the mean dissipation rate in the simulations and with the classical estimates based on the "third-order" law. Furthermore, we developed an anisotropic version of CG that allows us to study the magnitude of the cascade rate along different directions with respect to the mean magnetic field. Its implementation on the numerical data with moderate background magnetic field shows a weaker cascade along the magnetic field than in the perpendicular plane, while an isotropic cascade is recovered in the absence of a background field. The strength of the CG approach is further revealed when considering the local-in-space energy transfer, which is shown theoretically and numerically to match at a given position x, when locally averaged over a neighboring region, the (quasi-)local dissipation. Prospects of exploiting this model to investigate local dissipation in spacecraft data are discussed.

Process evaluation of an intervention to improve HIV treatment outcomes among children and adolescents.

SETTING: Children and adolescents with HIV encounter challenges in initiation and adherence to antiretroviral therapy (ART). A community-based support intervention of structured home visits, aimed at improving initiation, adherence and treatment, was delivered by community health workers (CHWs) to children and adolescents newly diagnosed with HIV. OBJECTIVES: To 1) describe intervention delivery, 2) explore CHW, caregiver and adolescents' perceptions of the intervention, 3) identify barriers and facilitators to implementation, and 4) ascertain treatment outcomes at 12 months' post-HIV diagnosis. DESIGN: We drew upon: 1) semi-structured interviews (n = 22) with 5 adolescents, 11 caregivers and 6 CHWs, 2) 28 CHW field manuals, and 3) quantitative data for study participants (demographic information and HIV clinical outcomes). RESULTS: Forty-one children received at least a part of the intervention. Of those whose viral load was tested, 26 (n = 32, 81.3%) were virally suppressed. Interviewees felt that the intervention supported ART adherence and strengthened mental health. Facilitators to intervention delivery were convenience and rapport between CHWs and families. Stigma, challenges in locating participants and inadequate resources for CHWs were barriers. CONCLUSION: This intervention was helpful in supporting HIV treatment adherence among adolescents and children. Facilitators and barriers may be useful in developing future interventions.

CONTEXTE: Les enfants et les adolescents séropositifs rencontrent des difficultés dans l'initiation et l'adhésion à la thérapie antirétrovirale (TAR). Des agents de santé communautaires (CHW) ont mis en place une intervention de soutien communautaire sous forme de visites structurées à domicile visant à améliorer l'initiation, l'adhésion et le traitement, auprès d'enfants et d'adolescents nouvellement diagnostiqués séropositifs. OBJECTIFS: 1) Décrire la mise en œuvre de l'intervention, 2) explorer les perceptions de l'intervention par les CHW, les soignants et les adolescents, 3) identifier les obstacles et les facilitateurs de la mise en œuvre, et 4) vérifier les résultats du traitement 12 mois après le diagnostic du VIH. METHODES: Nous nous sommes appuyés sur 1) des entretiens semi-structurés (n = 22) avec 5 adolescents, 11 soignants et 6 CHW, 2) 28 manuels de terrain des CHW, et 3) des données quantitatives sur les participants à l'étude (informations démographiques et résultats cliniques du VIH). RÉSULTATS: Quarante et un enfants ont reçu au moins une partie de l'intervention. Parmi ceux dont la charge virale a été testée, 26 (n = 32 ; 81,3%) étaient sous suppression virale. Les personnes interrogées ont estimé que l'intervention soutenait l'adhésion au TAR et renforçait la santé mentale. Les facilitateurs de la mise en œuvre de l'intervention étaient la commodité et les rapports entre les CHW et les familles. La stigmatisation, les difficultés à trouver des participants et les ressources inadéquates pour les CHW étaient des obstacles. CONCLUSION: Cette intervention a été utile pour soutenir l'adhésion au traitement du VIH chez les adolescents et les enfants. Les facilitateurs et les obstacles peuvent être utiles pour développer de futures interventions.

A comparison of HIV outpatient care in primary and secondary healthcare-level settings in Zimbabwe.

SETTING: Decentralisation of HIV care to nurse-led primary care services is being implemented across low- and middle-income countries in sub-Saharan Africa. OBJECTIVE: To compare services offered to clients attending for HIV care at a physician-led and a nurse-led service in Harare, Zimbabwe. DESIGN: A cross-sectional study was performed at Harare Central Hospital (HCH) and Budiriro Primary Care Clinic (PCC) from June to August 2018. An interviewer-administered questionnaire was used to collect sociodemographics, HIV treatment and clinical history from clients attending for routine HIV care. The Mann-Whitney U-test was used to evaluate for differences between groups for continuous variables. For categorical variables, the χ2 test was used. RESULTS: The median age of the 404 participants recruited was 38 years (IQR 28-47); 69% were female. Viral suppression was comparable between sites (HCH, 70% vs. PCC, 80%; P = 0.07); however, screening for comorbidities such as cervical cancer screening (HCH, 61% vs. PCC, 41%; P = 0.001) and provision of referral services (HCH, 23% vs. PCC, 13%; P = 0.01) differed between sites. CONCLUSION: Efforts to improve service provision in primary care settings are needed to ensure equity for users of health services.

Auditing use of antibiotics in Zimbabwean neonates.

BACKGROUND: Neonatal sepsis is a major cause of morbidity and mortality in low-income settings. As signs of sepsis are non-specific and deterioration precipitous, antibiotics are often used profusely in these settings where diagnostics may not be readily available. Harare Central Hospital, Zimbabwe, delivers 12000 babies per annum admitting ∼4800 to the neonatal unit. Overcrowding, understaffing and rapid staff turnover are consistent problems. Suspected sepsis is highly prevalent, and antibiotics widely used. We audited the impact of training and benchmarking intervention on rationalizing antibiotic prescription using local, World Health Organization-derived, guidelines as the standard. METHODS: An initial audit of admission diagnosis and antibiotic use was performed between 8th May - 6th June 2018 as per the audit cycle. An intern training programme, focusing on antimicrobial stewardship and differentiating between babies 'at risk of' versus 'with' clinically-suspected sepsis was instituted post-primary audit. Re-audit was conducted after 5 months. RESULTS: Sepsis was the most common admitting diagnosis by interns at both time points but reduced at repeat audit (81% versus 59%, P<0.0001). Re-audit after 5 months demonstrated a decrease in antibiotic prescribing at admission and discharge. Babies prescribed antibiotics at admission decreased from 449 (98%) to 96 (51%), P<0.0001. Inpatient days of therapy (DOT) reduced from 1243 to 1110/1000 patient-days. Oral amoxicillin prescription at discharge reduced from 349/354 (99%) to 1% 1/161 (P<0.0001). CONCLUSION: A substantial decrease in antibiotic use was achieved by performance feedback, training and leadership, although ongoing performance review will be key to ensuring safety and sustainability.

Evaluation of weight-based prescription of antiretroviral therapy in children.

OBJECTIVES: The aim of the study was to investigate the extent of and factors associated with incorrect dosing of antiretroviral therapy (ART) in HIV-infected children in Harare, Zimbabwe. METHODS: All children aged 0-10 years and children aged 11-17 years who weighed < 35 kg and taking ART were recruited from the paediatric HIV clinic at Harare Hospital. Their current doses of ART drugs were compared against doses recommended by the national guidelines. RESULTS: Among 309 children recruited [55% male; median age 7 years (interquartile range (IQR) 5-10 years)], the median CD4 count was 899 cells/µL and the median duration of their current ART regimen was 11.2 months (IQR 4.9-17.1 months). Overall, 110 (35.6%) children were prescribed incorrect doses of at least one drug component within their ART regimen; 64 (20.7%) under-dosed and 49 (15.9%) over-dosed on at least one drug. Children receiving a higher than recommended dose of at least one drug were younger compared with correctly dosed children (median 6 versus 7 years, respectively; P = 0.001), had been on their current ART regimen for a shorter time (median 7.2 versus 13 months, respectively; P = 0.003) and were less likely to be receiving a three-drug fixed-dose combination (FDC; 42.9 versus 63.3%, respectively; P = 0.009). Those who were under-dosed were also less likely to be on a three-drug FDC (25 versus 63.3%, respectively; P < 0.001). CONCLUSIONS: Over a third of children were prescribed incorrect doses of ART. Children taking triple-drug FDCs were likely to be correctly dosed. Our study highlights the importance of weight monitoring at each clinical contact, training of health care providers on paediatric drug dosing and the need for wider availability of FDCs for children.

Energy Cascade Rate Measured in a Collisionless Space Plasma with MMS Data and Compressible Hall Magnetohydrodynamic Turbulence Theory.

The first complete estimation of the compressible energy cascade rate |ϵ_{C}| at magnetohydrodynamic (MHD) and subion scales is obtained in Earth's magnetosheath using Magnetospheric MultiScale spacecraft data and an exact law derived recently for compressible Hall MHD turbulence. A multispacecraft technique is used to compute the velocity and magnetic gradients, and then all the correlation functions involved in the exact relation. It is shown that when the density fluctuations are relatively small, |ϵ_{C}| identifies well with its incompressible analog |ϵ_{I}| at MHD scales but becomes much larger than |ϵ_{I}| at subion scales. For larger density fluctuations, |ϵ_{C}| is larger than |ϵ_{I}| at every scale with a value significantly higher than for smaller density fluctuations. Our study reveals also that for both small and large density fluctuations, the nonflux terms remain always negligible with respect to the flux terms and that the major contribution to |ϵ_{C}| at subion scales comes from the compressible Hall flux.

Impact of scaling up Xpert® MTB/RIF testing for the detection of rifampicin-resistant TB cases in Karachi, Pakistan.

SETTING: Pakistan ranks fourth among the countries with a high burden of multidrug-resistant tuberculosis (MDR-TB), with only 19.2% of the 15 000 estimated incident cases being notified. Increasing treatment coverage for MDR-TB is a key priority for Pakistan's National Tuberculosis Programme. The World Health Organization recommends the use of the Xpert® MTB/RIF assay as the first-line diagnostic test for individuals with presumed TB. OBJECTIVE: To describe a multifaceted case-finding intervention targeting public and private sector health care facilities that used the Xpert assay as a frontline diagnostic test for individuals with presumptive TB, in Karachi, Pakistan, and its impact on case notifications of MDR-TB. DESIGN: Cross-sectional study. RESULTS: A total of 51 168 individuals were tested using Xpert, of whom respectively 7581 and 1534 people were diagnosed with TB in the public sector (reverse public-private mix) and private sector (social business model) arms; 574 (6.3% of all TB cases) were identified as having rifampicin (RMP) resistance. A total of 517 (90.1%) people with RMP-resistant TB (RR-TB) identified through the project were initiated on second-line treatment. The intervention resulted in 194 additional cases of RR-TB, an increase of 43% over the baseline. CONCLUSION: This project, one of the largest Xpert testing programmes conducted at city level, resulted in significantly increased detection and treatment of MDR-TB.

Extensive cerebrovascular disease and stroke with prolonged prodromal symptoms as first presentation of perinatally-acquired human immunodeficiency virus infection in a young adult.

A 26-year-old black African woman presented with an acute onset of hemiparesis and visual symptoms. This had been preceded several months by symptoms which were apparently psychiatric in nature. She had no apparent risk for cerebrovascular disease. Neurological evaluation revealed a striking burden of cerebrovascular disease for her age, including the rare stroke syndrome of basilar artery occlusion. Human immunodeficiency virus (HIV) infection was identified during clinical assessment. This was judged to be perinatally acquired, as there was no history of sexual debut or blood transfusion; her mother was taking antiretroviral therapy and she had facial planar warts and underlying bronchiectasis. Therefore, it has been concluded that presentation of stroke should prompt HIV testing in young people and perinatally-acquired infection can present in adulthood.

Carriage of extended-spectrum beta-lactamase-producing Enterobacteriaceae in HIV-infected children in Zimbabwe.

BACKGROUND: Antimicrobial resistance is an emerging global health issue. Data on the epidemiology of multidrug-resistant organisms are scarce for Africa, especially in HIV-infected individuals who often have frequent contact with healthcare. We investigated the prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) carriage in stool among HIV-infected children attending an HIV outpatient department in Harare, Zimbabwe. METHODS: We recruited children who were stable on antiretroviral therapy (ART) attending a HIV clinic from August 2014 to June 2015. Information was collected on antibiotic use and hospitalization. Stool was tested for ESBL-E through combination disc diffusion. API20E identification and antimicrobial susceptibility was performed on the positive samples followed by whole genome sequencing. RESULTS: Stool was collected from 175/202 (86.6 %) children. Median age was 11 [inter-quartile range (IQR) 9-12] years. Median time on ART was 4.6 years (IQR 2.4-6.4). ESBL-Es were found in 24/175 samples (13.7 %); 50 % of all ESBL-Es were resistant to amoxicillin-clavulanate, 100 % to co-trimoxazole, 45.8 % to chloramphenicol, 91.6 % to ceftriaxone, 20.8 % to gentamicin and 62.5 % to ciprofloxacin. ESBL-Es variously encoded CTX-M, OXA, TEM and SHV enzymes. The odds of ESBL-E carriage were 8.5 times (95 % CI 2.2-32.3) higher in those on ART for less than one year (versus longer) and 8.5 times (95 % CI 1.1-32.3) higher in those recently hospitalized for a chest infection. CONCLUSION: We found a 13.7 % prevalence of ESBL-E carriage in a population where ESBL-E carriage has not been described previously. Antimicrobial resistance (AMR) in Africa merits further study, particularly given the high HIV prevalence and limited diagnostic and therapeutic options available.

Stool Xpert® MTB/RIF test for the diagnosis of childhood pulmonary tuberculosis at primary clinics in Zimbabwe.

OBJECTIVE: To evaluate the diagnostic performance of Xpert® MTB/RIF on stool samples from children with clinical suspicion of pulmonary tuberculosis (PTB) at primary care clinics. DESIGN: A cross-sectional diagnostic evaluation enrolling 5-16 year olds from whom one induced sputum (IS) sample was tested for microbiological TB confirmation. Results of a single stool sample tested using Xpert were compared against microbiologically confirmed TB, defined as a positive result on sputum microscopy and/or culture and/or IS Xpert. RESULTS: Of 222 children enrolled, 218 had complete microbiological results. The median age was 10.6 years (interquartile range 8-13). TB was microbiologically confirmed in 19/218 (8.7%) children. Of these, respectively 5 (26%), 9 (47%) and 15 (79%) were smear-, culture- and IS Xpert-positive. Stool Xpert was positive in 13/19 (68%) microbiologically confirmed cases and 4/199 (2%) microbiologically negative cases. Stool Xpert detected 76.9% (10/13) of human immunodeficiency virus (HIV) infected and 50% (3/6) of non-HIV-infected children with microbiologically confirmed TB (P = 0.241). CONCLUSION: Stool Xpert is a potential alternative screening test for children with suspected TB if sputum is unavailable. Strategies to optimise the diagnostic yield of stool Xpert assay need further study.

[Technical aspects of protontherapy: Setup, equipment and radioprotection]. / Aspects techniques de la protonthérapie : installation, appareils, radioprotection.

The number of protontherapy facilities is still increasing rapidly with more than 30 ongoing projects and close to 60 currently under operation. Although the technology is now validated and robust, a proton facility cannot be considered as a standard radiation therapy equipment: its constraints in terms of building, services, project management are of paramount impact at the level of the hospital. Therefore, a protontherapy project must be carefully considered and prepared, which is mandatory for further fluid and efficient clinical operation.

HLA-C*06:04:02 a novel HLA-C allele isolated from donors of Southern African descent.

HLA-C*06:04:02 allele differs from HLA-C*06:02:01:01 with two nucleotide substitutions in exon 3 and 3' untranslated region (UTR_.

HLA-C*16:01:01:02, a recently isolated HLA class I allele from Southern Africa.

The full-length nucleotide sequence of HLA-C*16:01:01:02 differs from that of HLA-C*16:01:01:01 with a SNP at 2996C>T.

Isolation of full-length HLA-C*18:02 allele in an individual from Sub-Saharan Africa.

The full-length sequence of HLA-C*18:02 differs from that of HLA-C*18:01 by a single nucleotide polymorphism.

An empirical model for calculation of the collimator contamination dose in therapeutic proton beams.

Collimators are used as lateral beam shaping devices in proton therapy with passive scattering beam lines. The dose contamination due to collimator scattering can be as high as 10% of the maximum dose and influences calculation of the output factor or monitor units (MU). To date, commercial treatment planning systems generally use a zero-thickness collimator approximation ignoring edge scattering in the aperture collimator and few analytical models have been proposed to take scattering effects into account, mainly limited to the inner collimator face component. The aim of this study was to characterize and model aperture contamination by means of a fast and accurate analytical model. The entrance face collimator scatter distribution was modeled as a 3D secondary dose source. Predicted dose contaminations were compared to measurements and Monte Carlo simulations. Measurements were performed on two different proton beam lines (a fixed horizontal beam line and a gantry beam line) with divergent apertures and for several field sizes and energies. Discrepancies between analytical algorithm dose prediction and measurements were decreased from 10% to 2% using the proposed model. Gamma-index (2%/1 mm) was respected for more than 90% of pixels. The proposed analytical algorithm increases the accuracy of analytical dose calculations with reasonable computation times.

TestMeEast: a campaign to increase HIV testing in hospitals and to reduce late diagnosis.

Late diagnosis occurs in almost half of those diagnosed in the UK (HIV Prevention England, 2013. Retrieved June 22, 2014, from HIV Prevention England: http://www.hivpreventionengland.org.uk/Campaigns-Current/National-HIV-Testing-Week ). Testing occurs mainly in sexual health and antenatal clinics despite recommendations to test more broadly [Ellis, S., & Curtis, H. (2012). HIV diagnoses and missed opportunities. Results of the British HIV association (BHIVA) National Audit 2010. Clinical Medicine, 12(5), 430-434]. We report the findings of an HIV-testing week campaign to offer testing to those who have blood tests as part of routine care within outpatient clinics and emergency departments of six London hospitals. The campaign target was to test 500 patients a day during the 2013 National HIV Testing Week (NHTW). Clinic staff and medical students were trained to offer routine HIV testing. Linkage to care was arranged for those who tested HIV-positive. During NHTW we tested 2402 of the planned 2500 test target. 2402/4317 (55.6% 95% CI 54.1-57.1%) of those who had routine blood tests were tested for HIV. There were eight HIV-positive tests; three were new diagnoses (all linked to care). The campaign hashtag #TestMeEast achieved a total Twitter "reach" of 238, 860 and the campaign had widespread news coverage. Our campaign showed that staff and students could be trained and mobilised to do thousands of routine HIV tests during a campaign.

[Current use and prospects for hadron therapy in 2015]. / Hadronthérapie : quelle place et quelles perspectives en 2015 ?

Hadron therapy (including protons and ions) is still expanding worldwide, although still limited by the cost and thus the number of available facilities. If the historical indications remain eye melanomas, skull base tumours and paediatric tumours for protontherapy; and salivary glands, paranasal sinus and nasal cavity tumours, and soft tissue sarcomas for carbon ions, no conclusion can be drawn about the role of these modalities for other tumours, such as prostate, lung cancers. Since 2013, more than 100 clinical trials are on-going, including comparisons between advanced photons modalities, protontherapy and carbon ions therapy. An important technological and scientific (physics, radiobiology) effort has been made in parallel in order to reduce the cost of the facilities and to fully take advantages of the beam properties: standardization of beam scanning, image guided treatment, robust and 4D planning. Furthermore, the increasing number of facilities, the development of hypofractionation and the selection of indications will contribute to find the true place of particle therapy, despite the "screening effect" of the cost. The long term effects assessment on large patient cohorts will allow or not to correlate adverse effects and dosimetric data, always evoked.

Application of the Exradin W1 scintillator to determine Ediode 60017 and microDiamond 60019 correction factors for relative dosimetry within small MV and FFF fields.

In this work we use EBT3 film measurements at 10 MV to demonstrate the suitability of the Exradin W1 (plastic scintillator) for relative dosimetry within small photon fields. We then use the Exradin W1 to measure the small field correction factors required by two other detectors: the PTW unshielded Ediode 60017 and the PTW microDiamond 60019. We consider on-axis correction-factors for small fields collimated using MLCs for four different TrueBeam energies: 6 FFF, 6 MV, 10 FFF and 10 MV. We also investigate percentage depth dose and lateral profile perturbations. In addition to high-density effects from its silicon sensitive region, the Ediode exhibited a dose-rate dependence and its known over-response to low energy scatter was found to be greater for 6 FFF than 6 MV. For clinical centres without access to a W1 scintillator, we recommend the microDiamond over the Ediode and suggest that 'limits of usability', field sizes below which a detector introduces unacceptable errors, can form a practical alternative to small-field correction factors. For a dosimetric tolerance of 2% on-axis, the microDiamond might be utilised down to 10 mm and 15 mm field sizes for 6 MV and 10 MV, respectively.

Use of gEUD for predicting ear and pituitary gland damage following proton and photon radiation therapy.

OBJECTIVE: To determine the relationship between the dose to the inner ear or pituitary gland and radiation-induced late effects of skull base radiation therapy. METHODS: 140 patients treated between 2000 and 2008 were considered for this study. Hearing loss and endocrine dysfunction were retrospectively reviewed on pre- and post-radiation therapy audiometry or endocrine assessments. Two normal tissue complication probability (NTCP) models were considered (Lyman-Kutcher-Burman and log-logistic) whose parameters were fitted to patient data using receiver operating characteristics and maximum likelihood analysis. The method provided an estimation of the parameters of a generalized equivalent uniform dose (gEUD)-based NTCP after conversion of dose-volume histograms to equivalent doses. RESULTS: All 140 patients had a minimum follow up of 26 months. 26% and 44% of patients experienced mild hearing loss and endocrine dysfunction, respectively. The fitted values for TD50 and γ50 ranged from 53.6 to 60.7 Gy and from 1.9 to 2.9 for the inner ear and were equal to 60.6 Gy and 4.9 for the pituitary gland, respectively. All models were ranked equal according to Akaike's information criterion. CONCLUSION: Mean dose and gEUD may be used as predictive factors for late ear and pituitary gland late complications after skull base proton and photon radiation therapy. ADVANCES IN KNOWLEDGE: In this study, we have reported mean dose effects and dose-response relationship of small organs at risk (partial volumes of the inner ear and pituitary gland), which could be useful to define optimal dose constraints resulting in an improved therapeutic ratio.

Hearing impairment and deafness among HIV infected children and adolescents in Harare, Zimbabwe.

Background: Among HIV-infected children ear infections are recurrent and chronic, which may lead to hearing loss. Objective: To determine the prevalence, cause and severity of hearing impairment among HIV-infected children aged 5-17 years attending for HIV care in Harare. Design and Setting: An analytical cross-sectional survey conducted at Newlands Clinic, an opportunistic infections clinic in Harare. Materials and Methods: Participants underwent a standardised otoscopic examination of the ear and Pure Tone Audiometry (PTA). Factors associated with hearing impairment were investigated using multivariate logistic regression. Results: Three hundred and eighty (380) participants (55% female and mean age 11 years (SD: 3.3 years)) were consecutively recruited. The vast majority of participants (n=338; 89% were taking antiretroviral therapy (ART) for a median of 3 (IQR: 2-5) years at recruitment, and the most recent median CD4 Count (i.e. CD4 count measured within 6 months of the study recruitment) was 725 (IQR: 497-1000) cells/µL, with no difference by ART status. 61% (n= 231) of participants had an abnormal ear examination. Of the 359 participants who underwent audiometry, the prevalence of hearing impairment was 32.3% (95%CI: 27.5%-37.4%) based on a PTA threshold ≥26Db. Hearing impairment was associated with a recent CD4 count <350cell/µL (OR 2.1, P<0.037). Conclusion: There is a high prevalence of hearing impairment among HIV-infected children and adolescents. Low CD4 count remains a risk factor even among those who are on ART. We recommend that HIV infected children and adolescents, particularly those with low CD4 counts, should have routine evaluation of hearing as part of HIV care.