Study of the physicochemical quality of water in the Sebi-Ponty basin at Diamniadio (Senegal)

The Sebi-Ponty dam has a basin that is widely used by the population for agro-pastoral activities (animal watering, agriculture, etc.). This basin covers an average area of 106,000 m2 and an average depth of 7 m or about a volume of 435,000 m3. The origin of the water is rainfall (runoff and direct descent). The availability of water is estimated to eight months taking into account the water being drawn, infiltration and evaporation. A qualitative knowledge of the contents of this pool will be a great benefit to those activities of the population. Itrsquos in this context that this study was carried out by this group of researchers, following physic-chemical compositions were targeted: turbidity, color, temperature, conductivity, pH, hardness alkalinity, nitrite, iron, phosphate, boron, and chlorine concentrations. The physico-chemical results obtained on samples taken in the basin between October and December showed that the concentrations of boron, iron and nitrite exceeded the levels recommended by the standard for agro pastoral needs. While turbidity, color, temperature, conductivity, pH, hardness, alkalinity, phosphate and chlorine are at acceptable levels

Second harmonic light scattering induced by defects in the twist-bend nematic phase of liquid crystal dimers

The nematic twist-bend (NTB) phase, exhibited by certain thermotropic liquid crystalline (LC) dimers, represents a new orientationally ordered mesophase -- the first distinct nematic variant discovered in many years. The NTB phase is distinguished by a heliconical winding of the average molecular long axis (director) with a remarkably short (nanoscale) pitch and, in systems of achiral dimers, with an equal probability to form right- and left-handed domains. The NTB structure thus provides another fascinating example of spontaneous chiral symmetry breaking in nature. The order parameter driving the formation of the heliconical state has been theoretically conjectured to be a polarization field, deriving from the bent conformation of the dimers, that rotates helically with the same nanoscale pitch as the director field. It therefore presents a significant challenge for experimental detection. Here we report a second harmonic light scattering (SHLS) study on two achiral, NTB-forming LCs, which is sensitive to the polarization field due to micron-scale distortion of the helical structure associated with naturally-occurring textural defects. These defects are parabolic focal conics of smectic-like ``pseudo-layers", defined by planes of equivalent phase in a coarse-grained description of the NTB state. Our SHLS data are explained by a coarse-grained free energy density that combines a Landau-deGennes expansion of the polarization field, the elastic energy of a nematic, and a linear coupling between the two

Cost-eff ectiveness of community-based screening and treatment for chronic hepatitis B in The Gambia: an economic modelling analysis

Background Despite the high burden of hepatitis B virus (HBV) infection in sub-Saharan Africa, absence of widespread screening and poor access to treatment leads to most people remaining undiagnosed until later stages of disease when prognosis is poor and treatment options are limited. We examined the cost-eff ectiveness of community-based screening and early treatment with antiviral therapy for HBV in The Gambia. Methods In this economic evaluation, we combined a decision tree with a Markov state transition model to compare a screen and treat intervention consisting of adult community-based screening using a hepatitis B surface antigen (HBsAg) rapid test and subsequent HBV antiviral therapy versus current practice, in which there is an absence of publicly provided screening or treatment for HBV. We used data from the PROLIFICA study to parameterise epidemiological, primary screening, and cost information, and other model parameter inputs were obtained from a literature search. Outcome measures were cost per disability-adjusted life-year (DALY) averted; cost per life-year saved; and cost per quality-adjusted life-year (QALY) gained. We calculated the incremental cost-eff ectiveness ratios (ICERs) between current practice and the screen and treat intervention. Costs were assessed from a health provider perspective. Costs (expressed in 2013 US$) and health outcomes were discounted at 3 Findings In The Gambia, where the prevalence of HBsAg is 8·8 treatment for HBV has an incremental cost-eff ectiveness ratio (ICER) of$540 per DALY averted, $645 per life-year saved, and$511 per QALY gained, compared with current practice. These ICERs are in line with willingness-to-pay levels of one times the country’s gross domestic product per capita ($487) per DALY averted, and remain robust over a wide range of epidemiological and cost parameter inputs. Interpretation Adult community-based screening and treatment for HBV in The Gambia is likely to be a cost-eff ective intervention. Higher cost-eff ectiveness might be achievable with targeted facility-based screening, price reductions of drugs and diagnostics, and integration of HBV screening with other public health interventions

Development of a Usutu virus specific real-time reverse transcription PCR assay based on sequenced strains from Africa and Europe

Usutu virus (USUV) has been isolated in several African and European countries mainly from mosquitoes and birds. However, previous benign and two recent severe cases of human infections point out the need of a tool for the identification of USUV in human samples. A published real-time reverse transcription (RT) PCR assay for the detection of USUV in human blood or cerebrospinal fluid does not take into account the genetic variability of USUV in different geographic regions. Therefore, this article presents a quantitative real-time RT-PCR assay based on sequences from Europe and Africa. Primers and probe were designed in conserved regions among USUV strains that differed from closely related flaviviruses. The specificity of the assay was investigated by testing 16 other flaviviruses circulating in Africa. The sensitivity was determined by testing serial dilutions of virus and RNA standard. Intra- and inter-assay coefficients of variation were evaluated by 10 reactions in a same and in different assays, respectively. The assay provides high analytical specificity for USUV and detection limits of 1.2pfu/reaction for virus dilutions in L-15 medium or human serum and 60 copies/reaction for the RNA standard. The assay needs to be evaluated in a clinical context and integrated in standard diagnosis of flaviviral diseases

Interleukin 7 from Maternal Milk Crosses the Intestinal Barrier and Modulates T- Cell Development in Offspring

Background Breastfeeding protects against illnesses and death in hazardous environments, an effect partly mediated by improved immune function. One hypothesis suggests that factors within milk supplement the inadequate immune response of the offspring, but this has not been able to account for a series of observations showing that factors within maternally derived milk may supplement the development of the immune system through a direct effect on the primary lymphoid organs. In a previous human study we reported evidence suggesting a link between IL-7 in breast milk and the thymic output of infants. Here we report evidence in mice of direct action of maternally-derived IL-7 on T cell development in the offspring. Methods and Findings  We have used recombinant IL-7 labelled with a fluorescent dye to trace the movement in live mice of IL-7 from the stomach across the gut and into the lymphoid tissues. To validate the functional ability of maternally derived IL- 7 we cross fostered IL-7 knock-out mice onto normal wild type mothers. Subsets of thymocytes and populations of peripheral T cells were significantly higher than those found in knock-out mice receiving milk from IL-7 knock-out mothers. Conclusions/Significance Our study provides direct evidence that interleukin 7, a factor which is critical in the development of T lymphocytes, when maternally derived can transfer across the intestine of the offspring, increase T cell production in the thymus and support the survival of T cells in the peripheral secondary lymphoid tissue

Carboxymethyl guar gum nanoparticles for drug delivery applications: preparation and preliminary in-vitro investigations

Abstract Carboxymethyl guar gum (CMGG) synthesised from commercially available polysaccharide was formulated into nanoparticles via ionic gelation using trisodium trimetaphosphate (STMP) as cross-linking agent. Characterisation using a range of analytical techniques (FTIR, NMR, GPC, TGA and DLS) confirmed the CMGG structure and revealed the effect of the CMGG and STMP concentration on the main characteristics of the obtained nanoformulations. The average nanoparticle diameter was found to be around 208 nm, as determined by dynamic light scattering (DLS) and confirmed by scanning electron microscopy (SEM) and nanoparticle tracking analysis (NTA). Experiments using simulated gastric and intestinal fluids evidenced significant pH-dependent drug release behaviour of the nanoformulations loaded with Rhodamine B (RhB) as a model drug (loading capacity in excess of 83%), as monitored by UV-Vis. While dose-dependent cytotoxicity was observed, the nanoformulations appeared completely non-toxic at concentrations below 0.3 mg/mL. Results obtained so far suggest that carboxymethylated guar gum nanoparticles formulated with STMP warrant further investigations as polysaccharide based biocompatible drug nanocarriers

A Review of the Participation of Smallholder Farmers in Land-based Carbon Payment Schemes

There is renewed interest in the engagement of smallholder farmers in carbon markets. This follows in the wake of commitments by governments and companies to reduce or avoid the release of greenhouse gases. It is well known that soil can store large amounts of carbon, and soil stewardship offers a means to harness this potential. However, issues around permanence and scaling in smallholder farmer systems must be addressed if progress is to be made in this area. In this review, we examine the engagement of smallholder farmers in carbon sequestration payment schemes that promote sustainable land management (SLM). Drawing on a review of documents from carbon payment projects, interviews with key informants, and scientific literature, we highlight approaches for smallholder engagement along the project cycle, identify key barriers to participation, and outline options to enhance farmers’ agency. In assessing a total of ten projects, we observe considerable variation in participation across the projects. Project design tools classified as co-decision tools were common, with 60 % of projects reporting the use of individualised land management plans, 30 % the use of participatory rural appraisals (PRAs) and 10 % participatory mapping. However, few projects featured detailed frameworks for the incorporation of community feedback. The key informant interviews and literature review revealed that low carbon revenues, insecure land tenure, and high transaction costs are the primary barriers to participation, placing disproportionate pressure on marginalised households. Further, designing and implementing rigorous, participatory, and cost-effective monitoring reporting and verification (MRV) methodologies remains a challenge for many project proponents. We also find that flexible contracts can foster broad participation by including details that are attractive to mallholders such as longer terms, local contract providers and low-cost SLM measures. Projects that strengthen community institutions and social capital can stimulate participation among the marginalised, reduce transaction costs, and promote equity as well as smallholder agency. Engagement with communitybased organisations or other civil society actors can facilitate communication between project proponents and farmers, bolster farmers’ bargaining power, and reduce transaction costs during implementation