In today's race to find ways to produce cheap and green hydrogen, the natural hydrogen wells in Bourakebougou offer a promising solution and are a good example of how H
can be produced in the natural ...environment. Not only has one well been successfully exploited to generate electricity for the local village, but twenty-four other exploratory boreholes have also demonstrated the presence of natural H
in the surrounding area. The Bourakebougou H
field offers a unique opportunity for geoscientists to determine the key characteristics of natural hydrogen reservoirs. This paper presents the coring, logging, and geochemistry studies that were performed to better characterize the nature of the Bourakebougou H
-bearing reservoirs. The shallowest main reservoir, in which there is the highest content of H
, is made of dolomitic carbonate (Neoproterozoic cap carbonate). These carbonates are largely karstified and show a high degree of heterogeneity in porosity (0.21-14.32%). Based on the analysis of the drilling imagery of the carbonated reservoirs, the accumulation of hydrogen occurs in the karst (void) representing a secondary porosity in the rock matrix. Other reservoirs, especially the deepest ones, are porous sandstone rocks with much more homogeneous porosities (4.52-6.37%) compared to the massive carbonates. For the wells analysed, the neutron tool reacted in a specific way when there is the presence of hydrogen. Hence, it stands out as being the primary tool to detect the presence of natural hydrogen beyond simple gas logging. When comparing a H
reservoir system to classical oil and gas reservoir systems, the results show that the hydrogen reservoir is a dynamic system that is progressively recharged in H
-rich gas at the production timescale.
In this communication, we present a novel compact dual-band antenna-system for LTE multi-input and multi-output (MIMO) mobile handsets. The radiators consist of 3D Inverted-F- Antennas (IFAs) folded ...on the non-metalized part of the Printed Circuit Board (PCB) and operating in the LTE 700 MHz band. A parasitic radiating element is also attached to the IFAs to operate in the LTE 2.5-2.7 GHz band. Two antennas are placed on a realistic PCB (100 × 40 mm 2 ) for MIMO operation. Various antenna configurations are tested when moving their position on the PCB. Based on the highest port-to-port isolation criterion, two configurations are adopted and their performances are compared. Both simulated and measured results are shown to illustrate the MIMO capabilities of the proposed structures.
Environmental surveillance for poliovirus is increasingly used in poliovirus eradication efforts as a supplement to acute flaccid paralysis (AFP) surveillance. Environmental surveillance was ...officially established in 2017 in Senegal, where no poliovirus had been detected since 2010. We tested sewage samples from 2 sites in Dakar monthly for polioviruses. We identified a vaccine-derived poliovirus serotype 2 on January 19, 2021, from a sample collected on December 24, 2020; by December 31, 2021, we had detected 70 vaccine-derived poliovirus serotype 2 isolates circulating in 7 of 14 regions in Senegal. Sources included 18 AFP cases, 20 direct contacts, 17 contacts in the community, and 15 sewage samples. Phylogenetic analysis revealed the circulation of 2 clusters and provided evidence on the virus introduction from Guinea. Because novel oral polio vaccine serotype 2 was used for response activities throughout Senegal, we recommend expanding environmental surveillance into other regions.
Major investments have been made since 2001, with intensification of malaria control interventions after 2006. Interventions included free distribution of insecticide-treated nets (ITN) to pregnant ...women and children under 5 years old, the introduction of artemisinin combination therapy (ACT) for malaria treatment, and indoor residual spraying of insecticides. Funders include the Government of Mali, the Global Fund to Fight AIDS, Tuberculosis and Malaria, and the US President's Malaria Initiative.
Data from nationally representative household surveys conducted from 2000 to 2015 was used to performed the trend analysis for malaria intervention coverage, prevalence of morbidities among children under 5 years old parasitemia and severe anaemia (< 8 g/dl), and all-cause mortality of children under 5 (ACCM). Prevalence of contextual factors likely to contribute to ACCM were also assessed. The impact of these interventions was assessed on malaria morbidity and mortality using a plausibility argument. With the assumption that malaria contributes significantly to under-five mortality in settings with high malaria transmission, associations between malaria control interventions and all-cause under-five mortality (ACCM) were assessed taking into account other contextual factors related to child survival.
Intervention coverage improved significantly from 2006 to 2012. Household ownership of ITN increased from 49% in 2006 to 84% in 2012. ITN use also increased over the same period, from 26% in 2006 to 69% in 2012 among children under 5 and from 28% in 2006 to 73% in 2012 among pregnant women. The coverage of intermittent preventive treatment in pregnancy (IPTp) using two or more doses of SP increased from 10% in 2006 to 29% in 2012. In 2010, 23% of febrile children under 5 received ACT, as opposed to 19% in 2012. The prevalence of Plasmodium falciparum infection increased from 2010 (38.6%) to 2012 (51.6%), followed by a decrease in 2015 (35.8%). The prevalence of severe anaemia decreased from 2010 (26.3%) to 2012 (20.6%) and continued to decline in 2015 (19.9%). An impressive decline in ACCM was observed, from 225 in 1997-2001 to 192 in 2002-2006 and 95 in 2008-2012. Changes in contextual factors such as climate, socio-economic, nutrition, and coverage of maternal and child health interventions over the evaluation period did not favour reductions in ACCM, and are therefore unlikely to explain the observed results.
Taken as a whole, the evidence supports the conclusion that malaria control interventions substantially contributed to the observed decline in ACCM in Mali from 2000 to 2012, even in the context of continued high prevalence of parasitaemia explained by contextual factors such as climate change and political instability.
Due to the increased demand for indoor air conditioning, the residential sector in tropical regions is becoming more and more energy intensive. In this study, several passive cooling strategies in ...the building sector in Guinea, such as natural ventilation, thermal insulation, and cool coating roof, as well as the coupling between these different solutions, have been evaluated. Therefore, the thermal behaviour of a residential building in two climatic zones of Guinea is evaluated. The building thermal discomfort is assessed by the adaptive and conventional approaches, as well as the Wet Bulb Globe Temperature (WBGT) thermal stress indicators and the PMV-PPD indices. The results show that high levels of discomfort and thermal stress are present in the reference building. The use of the combination of passive cooling strategies allowed a reduction of the thermal discomfort evaluated by an adaptive approach of 74% in Conakry and 65% in Kankan. The WBGT index was improved by 42% in Conakry and 45% in Kankan. The operative temperature also decreased to 4.4°C for Conakry and 3.61°C for Kankan.
In this paper, a two efficient Planar Inverted-F Antenna (PIFA) system for dual-band functionality on fourth-generation (4G) band (2.5-2.7 GHz) and future fifth-generation (5G) band (3.4-3.8 GHz) is ...presented. During the optimization process, in order to obtain an efficient system, particular attention has been paid to the antenna system efficiency as well as the isolation between the antennas. Thus, the influence of the antenna slot design used to achieve a dual-band behavior on the antenna efficiency has been particularly studied. Moreover, the antenna positions on the Printed Circuit Board (PCB) have been chosen thanks to the use of characteristic mode analysis to obtain high isolation levels in both bands. The final system is optimized for Multiple Input Multiple Output Half Duplex (MIMO HD) 4G communications and Tx/Rx Full-Duplex (FD) 5G communications. A prototype with 140 mm × 70 mm ground plane was simulated, fabricated and measured. A high isolation level between the two ports of the PIFA elements, better than 35 dB in 5G band and 20 dB in 4G band in simulation and measurement that were done in free space, is obtained. Additionally, the most important diversity metrics are computed to evaluate the potential of this two-antenna system for diversity applications.
Having a geolocated list of all facilities in a country - a "master facility list" (MFL) - can provide critical inputs for health program planning and implementation. To the best of our knowledge, ...Senegal has never had a centralized MFL, though many data sources currently exist within the broader Senegalese data landscape that could be leveraged and consolidated into a single database - a critical first step toward building a full MFL. We collated 12,965 facility observations from 16 separate datasets and lists in Senegal, and applied matching algorithms, manual checking and revisions as needed, and verification processes to identify unique facilities and triangulate corresponding GPS coordinates. Our resulting consolidated facility list has a total of 4,685 facilities, with 2,423 having at least one set of GPS coordinates. Developing approaches to leverage existing data toward future MFL establishment can help bridge data demands and inform more targeted approaches for completing a full facility census based on areas and facility types with the lowest coverage. Going forward, it is crucial to ensure routine updates of current facility lists, and to strengthen government-led mechanisms around such data collection demands and the need for timely data for health decision-making.
Perspectives from Nepal, Senegal and Liberia highlight six key components of addressing COVID-19’s effects on RI during the earlier phases of the pandemic: (1) prioritising continued services with ...strengthened infection prevention control; (2) engaging in effective communications and mobilisation activities, especially to offset misinformation about COVID-19 and vaccines; (3) identifying alternative locations and approaches to providing vaccine services (eg, conducting door-to-door vaccination if facility-based services were not possible); (4) instituting infection prevention controls and physical distancing measures (and adapting service provision accordingly); (5) setting up systems and strategies for reaching children who missed doses amid periods of disruption; and (6) conducting catch-up campaigns as soon as SARS-CoV-2 transmission risks can be minimised. In May 2020, an estimated 80 million children were thought to be affected by interrupted vaccination services and campaigns,2 and over 60% of 105 countries reported at least partial RI disruptions to WHO.1 If left unaddressed, these disruptions are poised to halt or even reverse decades of global progress achieved in vaccine delivery and child health.3 4 Yet with great challenges can come great opportunity: knowledge and strategies gained from navigating pandemic’s effects on service delivery could help pave the ways for innovation, adaptions and resilience in the ways that RI programmes are approached more broadly. On their own, each of these disruptions could negatively impact vaccination rates; in combination, they formed substantial obstacles to RI programmes as a whole.Table 1 Summary of main types of pandemic-related disruptions for childhood RI, by vaccination driver, with global examples and reports from Nepal, Senegal and Liberia Vaccination driver Facility readiness Intent to vaccinate Community access Vaccination driver definition Health system supply and capacity, via health facilities, to adequately meet the demand of patients who seek vaccine services Demand for vaccine services by caretakers that, in the absence of all other barriers, would result in children being vaccinated Ability to carry out vaccination via barriers and facilitators between facility readiness and vaccination intent Examples of documented disruptions related to COVID-19 Delayed shipments of vaccine stocks and key supplies due to travel restrictions and reduced flight availability.18 Reduced or halted service availability and/or hours of operation. In late March 2020, for countries with surging infections and without active measles or polio outbreaks, WHO recommendations viewed exposing healthcare workers and community members to the novel coronavirus as greater than temporarily postponing mass campaigns.11 As the world’s understanding of COVID-19 improved and the magnitude of service disruptions began to surface,2 WHO issued follow-up guidance on implementing mass vaccination campaigns12 and principles for maintaining or resuming RI.13 14 How countries have then acted—adapting such guidelines for local needs or developing their own mitigation strategies against COVID-19 disruptions based on prior experience or some combination of each—has become an area of great interest.
The objective of this study was to estimate the retention rate of patients in an ART program and identify the predictors of attrition.
This was a historical cohort study of HIV patients who started ...ART between September 2007 and April 2020, and were followed up on for at least 6 months in nine large-volume sites. Kaplan Meier techniques were used to estimate cumulative retention and attrition probabilities. Cox proportional hazards models were used to identify predictors of attrition.
The cumulative probability of retention at 12 and 24 months was 76.2% and 70.2%, respectively. The attrition rate after a median follow-up time of 3.1 years was 35.2%, or an incidence of 11.4 per 100 person-years. Having initiated ART between 2012 and 2015; unmarried status; having initiated ART with CD4 count <100 cells/μL; and having initiated ART at an advanced clinical stage were factors significantly associated with attrition.
The retention rate in our study is much lower than the proposed national target (90%). Studies to understand the reasons for loss to follow-up are needed.
In Senegal, cervical cancer is the most common cancer among women and the leading cause of morbidity and mortality from all cancers. In 2018, Senegal launched a national human papillomavirus (HPV) ...vaccination program with Gavi, the Vaccine Alliance (Gavi), support. HPV vaccination was incorporated into the national immunization program as a two-dose schedule, with a 6-12-month interval, to nine-year-old girls via routine immunization (RI) services at health facilities, schools and community outreach services throughout the year. During February to March 2020, we conducted interviews to assess the awareness, feasibility, and acceptability of the HPV vaccination program with a cross-sectional convenience sample of healthcare workers (HCWs), school personnel, community healthcare workers (cHCWs), parents, and community leaders from 77 rural and urban health facility catchment areas. Participants were asked questions on HPV vaccine knowledge, delivery, training, and community acceptability of the program. We conducted a descriptive analysis stratified by respondent type. Data were collected from 465 individuals: 77 HCW, 78 school personnel, 78 cHCWs, 152 parents, and community leaders. The majority of HCWs (83.1%) and cHCWs (74.4%) and school personnel (57.7%) attended a training on HPV vaccine before program launch. Of all respondents, most (52.5-87.2%) were able to correctly identify the target population. The majority of respondents (60.2-77.5%) felt that the vaccine was very accepted or accepted in the community. Senegal's HPV vaccine introduction program, among the first national programs in the African region, was accepted by community stakeholders. Training rates were high, and most respondents identified the target population correctly. However, continued technical support is needed for the integration of HPV vaccination as a RI activity for this non-traditional age group. The Senegal experience can be a useful resource for countries planning to introduce the HPV vaccine.
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