Application d’un modèle conceptuel et d’un modèle de réseaux de neurones artificiels à la simulation des débits annuels dans le bassin versant du N’zi-Bandama (Côte d’Ivoire)

Cette étude présente la comparaison de deux approches de modélisation de la transformation pluie-débit à l'échelle annuelle : un modèle conceptuel et un réseau de neurones artificiels (RNA). Les deux modèles sont appliqués sur trois sous-bassins du fleuve N’zi-Bandama en Côte d'Ivoire. L’analyse comparative est basée sur les performances de simulation en termes de critère de Nash-Sutcliffe. Les modèles ont été testés sur deux périodes, l’une sèche (1973-1997) et l’autre humide (1961-1972). Les données d’entrée des deux modèles sont la pluie et l’évapotranspiration potentielle au pas de temps annuel. Les principaux résultats de ce travail montrent que les performances des deux modèles (conceptuel et neuronal) restent en général satisfaisantes avec des critères de Nash-Sutcliffe supérieurs à 60%. Ces modèles se sont révélés aussi robustes et adaptés pour la simulation des débits annuels des rivières. La comparaison des deux modèles a montré que le réseau de neurones a obtenu des résultats significativement meilleurs que le modèleconceptuel.Mots-clés : modélisation pluie-débit, modèle conceptuel, réseaux de neurones artificiels, N’zi-Bandama, Côte d’Ivoir.Application of a conceptual model and a model of artificial neural networks for the simulation of annual flows in the N'Zi-Bandama watershed (Ivory Coast).This study presents the comparison of two approaches of modelisation of the rainfall-runoff transformation on an annual scale: a conceptual model and an artificial neural network. The two models are applied to three watersheds of the N’zi-Bandama river in Ivory Coast. The comparative analysis is based on the performances of simulation in terms of criterion of Nash-Sutcliffe. The models were tested over two periods, one dries (1973-1997) and the other wet one (1961-1972). The data input of the two models are the rain and the potential evapotranspiration with the step of annual time. The principal results of this work show that the performances of the two models (conceptual and neuronal) remain satisfactory in general with criteria of Nash-Sutcliffe higher than 60%. These models appeared also robust and adapted for the simulation of the annual flow of the rivers. The comparison of the two models showed that the network of neurons had results significantly better than the conceptual model.Keywords : rainfall-runoff modelling, conceptual model, artificial neural network, N’zi-Bandama, Ivory Coast

Evaluation des propriétés hydrauliques des aquifères fracturés des formations cristalline et métamorphique dans la région des Lacs (centre de la Côte d’Ivoire)

Groundwater is the main source of water supply for rural populations in the Region des Lacs area in central Côte d’Ivoire (West Africa). The area is underlain by the metamorphic and crystalline fractured hard rock aquifers. This paper focuses on the assessment of their hydraulic properties. To this end, a data base comprising pumping tests data and the technical reports were gathered. 105 values of transmissivity (T ) and specific capacity (Q/s) have been deduced after pumping tests interpretation by the Jacob recovery method. Statistical analyses of all these data have been done. Depth of wells range from 49.50 to 99 m with an average of 69 m. The thickness of the weathered zone has averaged 16.52 m and lies between 1.90 and 63.10 m. Wells average rate is 2.32 m3/s. The depths of open fractures are significantly in the first 60 meters of hard rock drilling and averaged 42.94 m. The transmissivity and specific capacity of each aquifer span over several orders of magnitude revealing the strong heterogeneity of the aquifer. Both variables are lognormal variables A significant empirical relationship between T and Q/s was found T = 0,937(Q/s)^1.118 with a coefficient of determination (R^2 = 0.82). This relationship enabled the transmissivity data to be supplemented with the 95% prediction interval in order to assess the uncertainty associated with the estimates of transmissivity in the area of the study. These results are significant and can be used as an input in forthcoming modeling these aquifers and facilitate groundwater management policy.[fr] Dans la région des Lacs, centre de la Côte d’Ivoire (Afrique de l’Ouest), l’alimentation en eau potable des populations rurales est assurée en majorité par les eaux souterraines contenues dans les aquifères discontinus cristallin et cristallophyllien. L’objet de cet article est d’évaluer les propriétés hydrauliques de ces aquifères afin d’entreprendre des études pour la gestion optimale de cette ressource. Pour ce faire, une compilation de données regroupant les fiches techniques de forage de même que les essais de pompage disponibles dans la région a été faite. L’interprétation des essais de pompage par la méthode de remontée de Jacob a permis de déterminer 105 valeurs de transmissivité (T ) et de débit spécifique (Q/s). Une analyse statistique des paramètres de forages et des paramètres hydrauliques déterminés a été réalisée. Les forages ont une profondeur totale qui varie de 49,50 à 99 m avec une moyenne de 69 m. L’épaisseur des altérites est comprise entre 1,90 et 63,10 m pour une moyenne de 16,52 m. Les forages ont un débit moyen de 2,32 m3/s. Les profondeurs de venues d’eau sont en moyenne de 42,94 m dans la roche non altérée. Les transmissivités et les débits spécifiques s’échelonnent sur trois ordres de grandeur avec des coefficients de variation supérieurs à 100% traduisant ainsi l’hétérogénéité structurale du milieu aquifère. Ces deux paramètres sont également distribués selon la loi log-normale au seuil de 10%. Une relation empirique significative entre la transmissivité et le débit spécifique a été établie. Elle permet d’estimer la transmissivité par l’expressionT = 0,937(Q/s)^1,118 avec R^2 = 0,82 dans un intervalle de confiance de 95% pour les aquifères de la zone d’étude. Ces résultats sont importants car, ils seront utiles dans les études de modélisation de ces aquifères et faciliteront la politique de gestion des eaux souterraines

A Trial of Early Antiretrovirals and Isoniazid Preventive Therapy in Africa

BACKGROUND: In sub-Saharan Africa, the burden of human immunodeficiency virus (HIV)-associated tuberculosis is high. We conducted a trial with a 2-by-2 factorial design to assess the benefits of early antiretroviral therapy (ART), 6-month isoniazid preventive therapy (IPT), or both among HIV-infected adults with high CD4+ cell counts in Ivory Coast. METHODS: We included participants who had HIV type 1 infection and a CD4+ count of less than 800 cells per cubic millimeter and who met no criteria for starting ART according to World Health Organization (WHO) guidelines. Participants were randomly assigned to one of four treatment groups: deferred ART (ART initiation according to WHO criteria), deferred ART plus IPT, early ART (immediate ART initiation), or early ART plus IPT. The primary end point was a composite of diseases included in the case definition of the acquired immunodeficiency syndrome (AIDS), non-AIDS-defining cancer, non-AIDS-defining invasive bacterial disease, or death from any cause at 30 months. We used Cox proportional models to compare outcomes between the deferred-ART and early-ART strategies and between the IPT and no-IPT strategies. RESULTS: A total of 2056 patients (41% with a baseline CD4+ count of ≥500 cells per cubic millimeter) were followed for 4757 patient-years. A total of 204 primary end-point events were observed (3.8 events per 100 person-years; 95% confidence interval [CI], 3.3 to 4.4), including 68 in patients with a baseline CD4+ count of at least 500 cells per cubic millimeter (3.2 events per 100 person-years; 95% CI, 2.4 to 4.0). Tuberculosis and invasive bacterial diseases accounted for 42% and 27% of primary end-point events, respectively. The risk of death or severe HIV-related illness was lower with early ART than with deferred ART (adjusted hazard ratio, 0.56; 95% CI, 0.41 to 0.76; adjusted hazard ratio among patients with a baseline CD4+ count of ≥500 cells per cubic millimeter, 0.56; 95% CI, 0.33 to 0.94) and lower with IPT than with no IPT (adjusted hazard ratio, 0.65; 95% CI, 0.48 to 0.88; adjusted hazard ratio among patients with a baseline CD4+ count of ≥500 cells per cubic millimeter, 0.61; 95% CI, 0.36 to 1.01). The 30-month probability of grade 3 or 4 adverse events did not differ significantly among the strategies. CONCLUSIONS: In this African country, immediate ART and 6 months of IPT independently led to lower rates of severe illness than did deferred ART and no IPT, both overall and among patients with CD4+ counts of at least 500 cells per cubic millimeter. (Funded by the French National Agency for Research on AIDS and Viral Hepatitis; TEMPRANO ANRS 12136 ClinicalTrials.gov number, NCT00495651.)

Effect of isoniazid preventive therapy on risk of death in west African, HIV-infected adults with high CD4 cell counts: long-term follow-up of the Temprano ANRS 12136 trial.

BACKGROUND: Temprano ANRS 12136 was a factorial 2 × 2 trial that assessed the benefits of early antiretroviral therapy (ART; ie, in patients who had not reached the CD4 cell count threshold used to recommend starting ART, as per the WHO guidelines that were the standard during the study period) and 6-month isoniazid preventive therapy (IPT) in HIV-infected adults in Côte d'Ivoire. Early ART and IPT were shown to independently reduce the risk of severe morbidity at 30 months. Here, we present the efficacy of IPT in reducing mortality from the long-term follow-up of Temprano. METHODS: For Temprano, participants were randomly assigned to four groups (deferred ART, deferred ART plus IPT, early ART, or early ART plus IPT). Participants who completed the trial follow-up were invited to participate in a post-trial phase. The primary post-trial phase endpoint was death, as analysed by the intention-to-treat principle. We used Cox proportional models to compare all-cause mortality between the IPT and no IPT strategies from inclusion in Temprano to the end of the follow-up period. FINDINGS: Between March 18, 2008, and Jan 5, 2015, 2056 patients (mean baseline CD4 count 477 cells per μL) were followed up for 9404 patient-years (Temprano 4757; post-trial phase 4647). The median follow-up time was 4·9 years (IQR 3·3-5·8). 86 deaths were recorded (Temprano 47 deaths; post-trial phase 39 deaths), of which 34 were in patients randomly assigned IPT (6-year probability 4·1%, 95% CI 2·9-5·7) and 52 were in those randomly assigned no IPT (6·9%, 5·1-9·2). The hazard ratio of death in patients who had IPT compared with those who did not have IPT was 0·63 (95% CI, 0·41 to 0·97) after adjusting for the ART strategy (early vs deferred), and 0·61 (0·39-0·94) after adjustment for the ART strategy, baseline CD4 cell count, and other key characteristics. There was no evidence for statistical interaction between IPT and ART (pinteraction=0·77) or between IPT and time (pinteraction=0·94) on mortality. INTERPRETATION: In Côte d'Ivoire, where the incidence of tuberculosis was last reported as 159 per 100 000 people, 6 months of IPT has a durable protective effect in reducing mortality in HIV-infected people, even in people with high CD4 cell counts and who have started ART. FUNDING: National Research Agency on AIDS and Viral Hepatitis (ANRS)

Drivers of diversification and pluriactivity among smallholder farmers—evidence from Nigeria

Diversification and pluriactivity have become a norm among farm business owners (FBOs) due to persistent low farm income. This study applies the resource-based theory to examine drivers of diversification and livelihood income-oriented towards a sustainable livelihood. Our framework develops hypotheses about the impact of internal and external resources on livelihood choices at the household level. We use a survey of 480 rural Nigerian farmers (agripreneurs), applying a Multivariate Tobit to test our framework. We find that education plays the most significant role in all types of employment options. The more FBOs are educated, the more the likelihood that they will choose non-farm or wage employment. This study revealed that while the agriculture sector’s share of rural employment is declining, non-farm is on the increase. More so, there is a decline in farming among the young generation, marital status bias and gender influence in resource allocation. The socioeconomic (income and food security) and socio-cultural (employment and rural-urban migration) implications of rural sustainability linked to UN Development Goals have been highlighted and analysed in this article

The bii4africa dataset of faunal and floral population intactness estimates across Africa’s major land uses

Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species’ population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate ‘intactness scores’: the remaining proportion of an ‘intact’ reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region’s major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/ taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems

Socializing One Health: an innovative strategy to investigate social and behavioral risks of emerging viral threats

In an effort to strengthen global capacity to prevent, detect, and control infectious diseases in animals and people, the United States Agency for International Development’s (USAID) Emerging Pandemic Threats (EPT) PREDICT project funded development of regional, national, and local One Health capacities for early disease detection, rapid response, disease control, and risk reduction. From the outset, the EPT approach was inclusive of social science research methods designed to understand the contexts and behaviors of communities living and working at human-animal-environment interfaces considered high-risk for virus emergence. Using qualitative and quantitative approaches, PREDICT behavioral research aimed to identify and assess a range of socio-cultural behaviors that could be influential in zoonotic disease emergence, amplification, and transmission. This broad approach to behavioral risk characterization enabled us to identify and characterize human activities that could be linked to the transmission dynamics of new and emerging viruses. This paper provides a discussion of implementation of a social science approach within a zoonotic surveillance framework. We conducted in-depth ethnographic interviews and focus groups to better understand the individual- and community-level knowledge, attitudes, and practices that potentially put participants at risk for zoonotic disease transmission from the animals they live and work with, across 6 interface domains. When we asked highly-exposed individuals (ie. bushmeat hunters, wildlife or guano farmers) about the risk they perceived in their occupational activities, most did not perceive it to be risky, whether because it was normalized by years (or generations) of doing such an activity, or due to lack of information about potential risks. Integrating the social sciences allows investigations of the specific human activities that are hypothesized to drive disease emergence, amplification, and transmission, in order to better substantiate behavioral disease drivers, along with the social dimensions of infection and transmission dynamics. Understanding these dynamics is critical to achieving health security--the protection from threats to health-- which requires investments in both collective and individual health security. Involving behavioral sciences into zoonotic disease surveillance allowed us to push toward fuller community integration and engagement and toward dialogue and implementation of recommendations for disease prevention and improved health security

Avaliação da Qualidade de Vida de Crianças Africanas com Dermatite atópica pela escala CDLQI

Introduction: Atopic dermatitis (AD) is a chronic inflammatory disease that affects both children and adults. The main symptom is pruritus, which has an important impact on quality of life (QoL). The objective of our study was to assess the impact of AD on the quality of life of children through the CDLQI score. Population and Methods: We performed a cross-sectional survey, with descriptive and analytical aims, carried out on the basis of prospective recruitment, carried out over a period of 7 months from December 2017 to June 2018. The study included children (5-16 years) with AD selected during dermatology consultations at the Centre Hospitalier Universitaire of Treichville. Data collected included the socio-demographic characteristics of patients and their AD and the results of a questionnaire on the severity score (SCORAD) and the quality of life index in these children (CDLQI). Results: We included 60 children, mainly within the group from 05 to 09 years (57%). CDLQI average score was 9.9 and mean SCORAD 24. Pruritus, insomnia and sadness had more impact on QoL. We found a strong association between the severity of AD objectified by SCORAD and the CDLQI. Conclusion: The study reveals a high impact of AD on the QoL of children in Abidjan mainly through pruritus, insomnia and sadness. It opens up reflection on the need for education for AD management and the prospect of creating an atopy school in Côte d’Ivoire.Introdução: A dermatite atópica (AD) é uma doença inflamatória crónica que afeta crianças e adultos. O prurido é um dos principais sintomas e o que tem um impacto importante na qualidade de vida. O objetivo do estudo é avaliar o impacto da AD na qualidade de vida da criança pela escala de CDLQI. População e Métodos: Durante um período de 7 meses, entre Dezembro 2017 e Junho de 2018, efectuámos um estudo “cross-sectional” descritivo e analítico com base num recrutamento prospetivo que incluiu crianças (5-16 anos) com AD selecionadas durante a consulta de Dermatologia do Centre Hospitalier Universitaire de Treichville. Os dados recolhidos incluíram características sociodemográficas da população e da AD e os resultados de questionários que avaliam a gravidade da AD (SCORAD) e a qualidade de vida destas crianças (CDLQI). Resultados: Foram incluídas 60 crianças, sobretudo do grupo dos 5 aos 9 anos (57%). Os índices médios das escalas do CDLQI e SCORAD foram 9,9 e 24, respetivamente. O prurido, a insónia e a tristeza causaram o maior impacto na qualidade de vida. Encontrámos uma correlação forte entre a severidade da AD objetivada pelo SCORAD e a escala CDLQI. Conclusão: O estudo revela um elevado impacto da AD na qualidade de vida das crianças em Abidjan, especialmente causado pelo prurido, insónia e tristeza. Estes dados chamam a atenção para a necessidade de uma educação especial para abordagem terapêutica global e para a perspetiva de criar uma escola de atopia na Costa do Marfim