Hydrodynamic simulations of AGN jets:The impact of Riemann solvers and spatial reconstruction schemes on jet evolution

Numerical simulations play an essential role in helping us to understand the physical processes behind relativistic jets in active galactic nuclei. The large number of hydrodynamic codes available today enables a variety of different numerical algorithms to be utilized when conducting the simulations. Since many of the simulations presented in the literature use different combinations of algorithms it is important to quantify the differences in jet evolution that can arise due to the precise numerical schemes used. We conduct a series of simulations using the FLASH (magneto-)hydrodynamics code in which we vary the Riemann solver and spatial reconstruction schemes to determine their impact on the evolution and dynamics of the jets. For highly refined grids the variation in the simulation results introduced by the different combinations of spatial reconstruction scheme and Riemann solver is typically small. A high level of convergence is found for simulations using third-order spatial reconstruction with the Harten–Lax–Van-Leer with contact and Hybrid Riemann solvers

Numerical simulations of colliding jets in an external wind:application to 3C 75

The radio galaxy 3C 75 is remarkable because it contains a pair of radio-loud active galaxies, each of which produces a two-sided jet, with the jet beams appearing to collide and merge to the west of the galaxies. Motivated by 3C 75, we have conducted three-dimensional hydrodynamic simulations of jet collisions. We have extended previous studies by modelling the physical properties of the cluster atmosphere, including an external wind, and using realistic jet powers obtained from observational data. We are able to produce a morphology similar to that of 3C 75. The simulations imply that direct contact between the bulk jet flows on the west of the source is required to produce a morphology consistent with 3C 75. We quantify how the merging jets decelerate, how the wind deflects the jets and cocoons, the entrainment of intra-cluster material into the cocoons, the cocoon energetics, and how the jet interactions generate enstrophy. By comparing simulations of pairs of two-sided jets with those of single two-sided sources, we determine how the interaction between two bipolar jets changes their evolution. The unprecedented sensitivity and angular resolution of upcoming observatories will lead to the detection of many more complex sources at high redshift, where interacting jets are expected to be more numerous. The morphology of these complex sources can provide significant insight into the conditions in their environments

Reducing child undernutrition through dietary diversification, reduced aflatoxin exposure, and improved hygiene practices: the immediate impacts in central Tanzania

Open Access Article; Published online: 28 Nov 2019The study aimed to quantify the immediate effects of dietary diversification, food safety, and hygiene interventions on child undernutrition in four rural villages in Kongwa district of central Tanzania. One hundred mothers with their children of less than 24 months old were recruited for this study. The difference-in-difference (DID) method was used to assess the effects of intensive intervention through a learning-by-doing process on the topic of aflatoxin free diversified food utilization and improved hygiene practices. Periodic anthropometric measurements were conducted on the 0th, 7th, 14th, and 21st days, and DID estimator showed the significant and positive average marginal effects of the intervention on Z-Scores being 0.459, 0.252, and 0.493 for wasting, stunting, and underweight, respectively. Notably, at the end of the study, the mean aflatoxin M1 level in urine samples decreased by 64% in the intervention group, while it decreased by 11% in the control group. The study provides quantitative evidence on intensive 21-day training for mothers incorporating integrated technologies yielded positive impacts on their children’s nutritional outcomes

Hydrodynamical simulations of colliding jets:modeling 3C 75

Radio observations suggest that 3C 75, located in the dumbbell shaped galaxy NGC 1128 at the center of Abell 400, hosts two colliding jets. Motivated by this source, we perform three-dimensional hydrodynamical simulations using a modified version of the GPU-accelerated Adaptive-MEsh-Refinement hydrodynamical parallel code ($\mathit{GAMER}$) to study colliding extragalactic jets. We find that colliding jets can be cast into two categories: 1) bouncing jets, in which case the jets bounce off each other keeping their identities, and 2) merging jets, when only one jet emerges from the collision. Under some conditions the interaction causes the jets to break up into oscillating filaments of opposite helicity, with consequences for their downstream stability. When one jet is significantly faster than the other and the impact parameter is small, the jets merge; the faster jet takes over the slower one. In the case of merging jets, the oscillations of the filaments, in projection, may show a feature which resembles a double helix, similar to the radio image of 3C 75. Thus we interpret the morphology of 3C 75 as a consequence of the collision of two jets with distinctly different speeds at a small impact parameter, with the faster jet breaking up into two oscillating filaments.Comment: 13 pages, 9 figures, accepted for publication in Ap

Menstrual health and school absenteeism among adolescent girls in Uganda (MENISCUS): a feasibility study.

BACKGROUND: Management of menstruation can present substantial challenges to girls in low-income settings. In preparation for a menstrual hygiene intervention to reduce school absenteeism in Uganda, this study aimed to investigate menstruation management practices, barriers and facilitators, and the influence of menstruation on school absenteeism among secondary school students in a peri-urban district of Uganda. METHODS: Qualitative and quantitative studies were conducted among consenting girls and boys aged 14-17 years in four secondary schools in Entebbe sub-District, Uganda. Methods included group and in-depth interviews with students, a quantitative cross-sectional questionnaire, a prospectively self-completed menstrual diary, key informant interviews with policy makers, and observations of school water, sanitation and hygiene facilities. Multiple logistic regression was used to assess factors associated with school absenteeism during the most recent menstrual period. RESULTS: Girls reported substantial embarrassment and fear of teasing related to menstruation in the qualitative interviews, and said that this, together with menstrual pain and lack of effective materials for menstrual hygiene management, led to school absenteeism. All policy makers interviewed reported poverty and menstruation as the key factors associated with school attendance. The 352 girls with questionnaire data had a median age of 16 (inter-quartile range (IQR) = 15,16) years, with median age at menarche of 13 (IQR = 13,14) years. Of these, 64 girls (18.7%) reported having stained their clothes and 69 (19.7%) reported missing at least 1 day of school, during their most recent period. Missing school during the most recent period was associated with physical symptoms (headache (odds ratio (OR) = 2.15, 95%CI:1.20, 3.86), stomach pain (OR = 1.89, 95%CI:0.89, 4.04), back pain (OR = 1.75, 95%CI:0.97, 3.14), and with changing protection 4 or more times per 24 h period (OR = 2.08, 95%CI:1.06, 4.10). In the diary sub-study among 40 girls, school absence was reported on 28% of period-days, compared with 7% of non-period days (adjusted odds ratio = 5.99, 95%CI:4.4, 8.2; p < 0.001). CONCLUSION: In this peri-urban Ugandan population, menstruation was strongly associated with school attendance. Evaluation of a menstrual management intervention that address both psychosocial (e.g. self-confidence, attitudes) and physical (e.g. management of pain, use of adequate menstrual hygiene materials, improved water and sanitation facilities) aspects of menstruation are needed

Strengthening the community health worker programme for health improvement through enhancing training, supervision and motivation in Wakiso district, Uganda

Objective: The objective of the project was to strengthen the community health worker (CHW) programme in Ssisa sub-county, Wakiso district, Uganda by providing a coherent, structured and standardized training, supervision and motivation package so as to enhance their performance. Results: The project trained all 301 CHWs who received non-financial incentives of t-shirts, gumboots and umbrellas, and 75 of them received solar equipment to support lighting their houses and charging phones. Twenty-four of the CHWs who had coordination roles received additional training. Three motorcycles were also provided to enhance transportation of CHW coordinators during their work including supervision. By end of the project, the CHWs had conducted 40,213 household visits, carried out health education sessions with 127,011 community members, and treated 19,387 children under 5 years of age. From the project evaluation, which used both quantitative and qualitative methods, 98% of the CHWs reported having improved competence in performance of their roles. In addition, the CHWs were highly motivated to do their work. The motorcycles were instrumental in supporting the work of CHW coordinators including monthly collection of reports and distribution of medicines. The project demonstrated that by improving training, supervision and motivation, performance of CHW programmes can be enhanced

Induction of humoral immune response to multiple recombinant Rhipicephalus appendiculatus antigens and their effect on tick feeding success and pathogen transmission

BACKGROUND: Rhipicephalus appendiculatus is the primary vector of Theileria parva, the etiological agent of East Coast fever (ECF), a devastating disease of cattle in sub-Saharan Africa. We hypothesized that a vaccine targeting tick proteins that are involved in attachment and feeding might affect feeding success and possibly reduce tick-borne transmission of T. parva. Here we report the evaluation of a multivalent vaccine cocktail of tick antigens for their ability to reduce R. appendiculatus feeding success and possibly reduce tick-transmission of T. parva in a natural host-tick-parasite challenge model. METHODS: Cattle were inoculated with a multivalent antigen cocktail containing recombinant tick protective antigen subolesin as well as two additional R. appendiculatus saliva antigens: the cement protein TRP64, and three different histamine binding proteins. The cocktail also contained the T. parva sporozoite antigen p67C. The effect of vaccination on the feeding success of nymphal and adult R. appendiculatus ticks was evaluated together with the effect on transmission of T. parva using a tick challenge model. RESULTS: To our knowledge, this is the first evaluation of the anti-tick effects of these antigens in the natural host-tick-parasite combination. In spite of evidence of strong immune responses to all of the antigens in the cocktail, vaccination with this combination of tick and parasite antigens did not appear to effect tick feeding success or reduce transmission of T. parva. CONCLUSION: The results of this study highlight the importance of early evaluation of anti-tick vaccine candidates in biologically relevant challenge systems using the natural tick-host-parasite combination

Soccer-based promotion of voluntary medical male circumcision: A mixed-methods feasibility study with secondary students in Uganda.

The Ugandan government is committed to scaling-up proven HIV prevention strategies including safe male circumcision, and innovative strategies are needed to increase circumcision uptake. The aim of this study was to assess the acceptability and feasibility of implementing a soccer-based intervention ("Make The Cut") among schoolboys in a peri-urban district of Uganda. The intervention was led by trained, recently circumcised "coaches" who facilitated a 60-minute session delivered in schools, including an interactive penalty shoot-out game using metaphors for HIV prevention, sharing of the coaches' circumcision story, group discussion and ongoing engagement from the coach to facilitate linkage to male circumcision. The study took place in four secondary schools in Entebbe sub-district, Uganda. Acceptability of safe male circumcision was assessed through a cross-sectional quantitative survey. The feasibility of implementing the intervention was assessed by piloting the intervention in one school, modifying it, and implementing the modified version in a second school. Perceptions of the intervention were assessed with in-depth interviews with participants. Of the 210 boys in the cross-sectional survey, 59% reported being circumcised. Findings showed high levels of knowledge and generally favourable perceptions of circumcision. The initial implementation of Make The Cut resulted in 6/58 uncircumcised boys (10.3%) becoming circumcised. Changes made included increasing engagement with parents and improved liaison with schools regarding the timing of the intervention. Following this, uptake improved to 18/69 (26.1%) in the second school. In-depth interviews highlighted the important role of family and peer support and the coach in facilitating the decision to circumcise. This study showed that the modified Make The Cut intervention may be effective to increase uptake of safe male circumcision in this population. However, the intervention is time-intensive, and further work is needed to assess the cost-effectiveness of the intervention conducted at scale

Risk factors of virologic failure and slow response to art among HIV-infected children and adolescents in Nairobi

Background: Antiretroviral therapy (ART) in resource-limited settings is effective when backed up with adequate clinical, immunological, and virologic monitoring. Undetected, virologic failure results in increased HIV-1 drug resistance mutations (DRMs), morbidity and mortality, or the need for costly second-line and third-line ART.Objective: To evaluate the prevalence, patterns, and risk factors of virologic failure and slow response to ART, among children and adolescents in resource-limited settings in Nairobi, Kenya.Design: A Retrospective study.Setting: The 8 Lea Toto Programme (LTP) Clinics in Dagoretti, Dandora, Kangemi, Kariobangi, Kawangware, Kibera, Mukuru, and Zimmerman areas of Nairobi. Subjects: One hundred and forty-six HIV-infected children and adolescents aged 1 month to 19 years of the LTP in Nairobi Kenya. Medical and demographic data including, HIV-1 viral loads, information on adherence to ART, HIV-1 DRMs and other key determinants of virologic failure, collected over a period of 2 years, was used for this study.Results: A threshold of 1,000 HIV RNA copies/ml was used to determine treatment outcome. The virologic failure rates in this cohort were 43.8% after 6 months, 32.2% after 12 months, 28.8% after 18 months, and 24.0% after 24 months of first-line ART. Twelve (8.2%) of 146 children showed a slow response to ART: they initially failed ART at 12 months, but had treatment success after 18 to 24 months. The rates of virologic rebound were 4 (2.7%) after 18 months and 3 (2.1%) after 24 months of ART. Multivariate Cox proportional hazards regression revealed that children with suboptimal adherence to ART were 37 times more likely to experience virologic failure (P = 0.000003).Conclusions: This study showed that ART implementation in resource-limited settings is effective when regular virologic monitoring, adherence counselling, and HIV-DR testing are available. Secondly, adherence to ART is a strong predictor of treatment outcome for children and adolescents in resourcelimited settings. Therefore, methods of optimizing adherence levels should be explored and implemented

Elevated serum IL-10 is associated with severity of neonatal encephalopathy and adverse early childhood outcomes

BACKGROUND: Neonatal encephalopathy (NE) contributes substantially to child mortality and disability globally. We compared cytokine profiles in term Ugandan neonates with and without NE, with and without perinatal infection or inflammation and identified biomarkers predicting neonatal and early childhood outcomes. METHODS: In this exploratory biomarker study, serum IL-1α, IL-6, IL-8, IL-10, TNFα, and VEGF (<12 h) were compared between NE and non-NE infants with and without perinatal infection/inflammation. Neonatal (severity of NE, mortality) and early childhood (death or neurodevelopmental impairment to 2.5 years) outcomes were assessed. Predictors of outcomes were explored with multivariable linear and logistic regression and receiver-operating characteristic analyses. RESULTS: Cytokine assays on 159 NE and 157 non-NE infants were performed; data on early childhood outcomes were available for 150 and 129, respectively. NE infants had higher IL-10 (p < 0.001), higher IL-6 (p < 0.017), and lower VEGF (p < 0.001) levels. Moderate and severe NE was associated with higher IL-10 levels compared to non-NE infants (p < 0.001). Elevated IL-1α was associated with perinatal infection/inflammation (p = 0.013). Among NE infants, IL-10 predicted neonatal mortality (p = 0.01) and adverse early childhood outcome (adjusted OR 2.28, 95% CI 1.35-3.86, p = 0.002). CONCLUSIONS: Our findings support a potential role for IL-10 as a biomarker for adverse outcomes after neonatal encephalopathy. IMPACT: Neonatal encephalopathy is a common cause of child death and disability globally. Inflammatory cytokines are potential biomarkers of encephalopathy severity and outcome. In this Ugandan health facility-based cohort, neonatal encephalopathy was associated with elevated serum IL-10 and IL-6, and reduced VEGF at birth. Elevated serum IL-10 within 12 h after birth predicted severity of neonatal encephalopathy, neonatal mortality, and adverse early childhood developmental outcomes, independent of perinatal infection or inflammation, and provides evidence to the contribution of the inflammatory processes. Our findings support a role for IL-10 as a biomarker for adverse outcomes after neonatal encephalopathy in a sub-Saharan African cohort