207 research outputs found
Aménagements hydro-agricoles et santé (vallée du fleuve Sénégal)
PrÚs de 1 500 personnes résidant dans les villages rattachés au périmÚtre irrigué MO 6bis (périmÚtre de Diomandou, département de Podor) ont fait l'objet de prélÚvements d'urine et/ou de selle afin de déterminer la prévalence de la bilharziose urinaire, de la bilharziose intestinale ainsi que des autres parasitoses entériques. Chez les riverains du périmÚtre, 1 295 urines ont été examinées, parmi lesquelles sept contenaient des oeufs viables de #Schistosoma haematobium, ce qui correspond à un indice d'infestation de 0,1%. Il s'agissait là aussi d'un individu dont la contamination avait eu lieu en dehors de la zone d'étude. #Eschirichia coli, #Strongyloïdes stercoralis, #Ascaris lumbricoïdes et #Trichiuris trichiura$ sont rares et ne concernent qu'un peu moins de 2% des sujets examinés. Ces résultats démontrent l'absence, pour l'instant tout au moins, de foyers de transmission des bilharzioses dans les villages du périmÚtre de Diomandou. Le risque d'apparition de ces maladies est cependant important et dépend à la fois de l'évolution des infrastructures et de l'éventuelle apparition d'hÎtes intermédiaires encore absent du réseau hydrographique de ce périmÚtre mis en place récemment. (Résumé d'auteur
Les fourmis (Hymenoptera, Formicidae) de lâenclos dâacclimatation de KatanĂ© de la rĂ©serve de faune du Ferlo nord (SĂ©nĂ©gal)
Les fourmis (Hymenoptera, Formicidae), de par leur biomasse, et leur diversitĂ© spĂ©cifique, jouent un rĂŽle fondamental dans les Ă©cosystĂšmes terrestres tropicaux. NĂ©anmoins, elles sont trĂšs peu Ă©tudiĂ©es et mal connues au SĂ©nĂ©gal. Pour contribuer Ă combler cette lacune nous avons Ă©tudiĂ© le peuplement des fourmis de lâenclos dâacclimatation de KatanĂ©, un site se trouvant dans la RĂ©serve de Faune du Ferlo Nord en zone de savane sahĂ©lienne (rĂ©gion de Matam, SĂ©nĂ©gal). Les fourmis ont Ă©tĂ© Ă©chantillonnĂ©es Ă lâaide de piĂšges Ă fosse et par la chasse Ă vue. La richesse spĂ©cifique (S) est de 21 espĂšces. Les espĂšces les plus remarquables par leur abondance et leur distribution sont Crematogaster senegalensis, Monomorium areniphilum, Trichomyrmex abyssinicus, Monomorium bicolor, Pheidole andrieui, Brachyponera sennaarensis, Tetramorium angulinode papyri et Tetramorium sericeiventre. Elles appartiennent toutes Ă la sous-famille des Myrmicinae sauf B. sennaarensis qui est de la sous-famille des Ponerinae. Lâindice de fourragement (9,79), lâindice de Shannon (0,95), lâindice dâĂ©quitabilitĂ© de PiĂ©lou (0,77), lâindice de Simpson (0,14) et lâindice de diversitĂ© de Simpson (0,86) peuvent ĂȘtre utilisĂ©s comme rĂ©fĂ©rentiels pour le suivi de lâĂ©volution des habitats de lâenclos et pour les Ă©tudes de lâĂ©tat de dĂ©gradation des habitats dans le Ferlo en gĂ©nĂ©ral.© 2016 International Formulae Group. All rights reserved.Mots clĂ©s: Fourmis, Ă©cosystĂšmes, diversitĂ©, abondance, Ferlo nord, SĂ©nĂ©galEnglish Title: Ants (Hymenoptera, Formicidae) of the acclimatization enclosure of Katane in the north Ferlo wildlife reserve (Senegal)English AbstractAnts (Hymenoptera, Formicidae), by their biomass and species diversity, play a fundamental role in the terrestrial ecosystems of the tropical area. Nevertheless, they are very little studied and poorly known in Senegal. To fill this gap we have chosen to study them in the acclimatization enclosure of Katane in the north Ferlo Reserve Wildlife situated in the Sahel savanna in Matam region (Senegal). They were sampled using pitfall traps and hand collecting. Species richness (S) is 21 species. The most remarkable for their abundances and distributions are Crematogaster senegalensis, Monomorium areniphilum, Trichomyrmex abyssinicus, Monomorium bicolor, Pheidole andrieui, Brachyponera sennaarensis, Tetramorium angulinode papyri and Tetramorium sericeiventre. They all belong to the subfamily Myrmicinae except B. sennaarensis which belongs to the subfamily Ponerinae. The foraging index (9.79), the Shannon index (0.95), the index of Pielou equitability (0.77), the Simpson index (0.14) and the Simpson's index diversity (0.86) can be used as reference for monitoring the biotopes evolution in the enclosure of KatanĂ© and for the studies of land degradation in the Ferlo in general.© 2016 International Formulae Group. All rights reserved.Keywords: Ants, ecosystems, diversity, abundance, northern Ferlo, Senega
Avantages des biodigesteurs sur le bois de chauffe dans les élevages laitiers à Kaolack (Sénégal)
Le dĂ©ficit Ă©nergĂ©tique constitue une contrainte Ă lâĂ©panouissement des mĂ©nages ruraux notamment, au niveau de lâĂ©nergie de cuisson. Les femmes utilisent le bois de chauffe pour les besoins Ă©nergĂ©tiques de la cuisson mais aussi, pour la pasteurisation du lait. Cette Ă©tude met en Ă©vidence les avantages de lâutilisation des biodigesteurs sur le bois de chauffe dans les Ă©levages laitiers Ă Kaolack (SĂ©nĂ©gal). Cent seize mĂ©nages ont Ă©tĂ© enquĂȘtĂ©s dont 58 dĂ©tenteurs de biodigesteurs. Les rĂ©sultats montrent que les mĂ©nages possĂ©dant un biodigesteur avaient plus de temps pour se consacrer Ă des activitĂ©s rĂ©munĂ©ratrices ou pour le bien ĂȘtre de la famille avec un tiers (32,75 %) qui mettent moins de 2 h par jour pour la recherche du bois et 2 h pour la cuisson dâun repas contre (67,25 %) de mĂ©nages sans biodigesteurs qui y consacraient 2 Ă 6 h par jour et plus de 3 h pour la cuisson dâun repas. Plus du quart (25,86 %) des mĂ©nages avec biodigesteurs utilisaient le biogaz comme source dâĂ©clairage. De mĂȘme, 36,20 % prĂ©parent les repas et pasteurisent le lait avec le biogaz. Il est Ă©galement constatĂ© une rĂ©duction de la frĂ©quence des pathologies respiratoires et oculaires mais aussi des dĂ©penses pour lâachat de combustible et de compost.Mots clĂ©s: Biogaz ; bois ; Ă©levages laitiers ; Ă©conomie des mĂ©nages ; Kaolack ; SĂ©nĂ©gal Biodigester benefits on wood heating in dairy farming of Kaolack (Senegal)The energy deficit is a major constraint to the development of rural house holds including at cooking energy. Women use firewood for cooking energy needs but also for the pasteurization of milk. This study highlights the benefits of using biogas digesters on firewood in dairy farms in Kaolack (Senegal). One Hundred sixteen households were surveyed of which 58 possessed biodigester.The results show that households with a biodigester had much more time devoted to income-generating activities or for the welfare of the family. One third (32.75 %) of biodigester owners take less than 2 hours per day for wood search and 2 hours for cooking a meal against (67.25 %) of house holds without biodigester who spent 2 to 6 hours per day and put more than 3 hours to cook meal. More than a quarter (25.86 %) of households with biodigester used biogas as a lighting. Similarly, 36.20 % Cook food and pasteurize milk with biogas.The used of biogas expenses for the purchase of fuel as well as the compost for filed fertilization. It seem that biogas utilization reduce the incidence of respiratory and eye diseases.Keywords: Biogas ; wood ; dairy farms ; household economy ; Kaolack ; Senegal
A High-Resolution Regional Climate Model Physics Ensemble for Northern Sub-Saharan Africa
While climate information from General Circulation Models (GCMs) are usually too coarse for climate impact modelers or decision makers from various disciplines (e.g., hydrology, agriculture), Regional Climate Models (RCMs) provide feasible solutions for downscaling GCM output to finer spatiotemporal scales. However, it is well known that the model performance depends largely on the choice of the physical parameterization schemes, but optimal configurations may vary e.g., from region to region. Besides land-surface processes, the most crucial processes to be parameterized in RCMs include radiation (RA), cumulus convection (CU), cloud microphysics (MP), and planetary boundary layer (PBL), partly with complex interactions. Before conducting long-term climate simulations, it is therefore indispensable to identify a suitable combination of physics parameterization schemes for these processes. Using the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis product ERA-Interim as lateral boundary conditions, we derived an ensemble of 16 physics parameterization runs for a larger domain in Northern sub-Saharan Africa (NSSA), northwards of the equator, using two different CU-, MP-, PBL-, and RA schemes, respectively, using the Weather Research and Forecasting (WRF) model for the period 2006â2010 in a horizontal resolution of approximately 9 km. Based on different evaluation strategies including traditional (Taylor diagram, probability densities) and more innovative validation metrics (ensemble structure-amplitude-location (eSAL) analysis, Copula functions) and by means of different observation data for precipitation (P) and temperature (T), the impact of different physics combinations on the representation skill of P and T has been analyzed and discussed in the context of subsequent impact modeling. With the specific experimental setup, we found that the selection of the CU scheme has resulted in the highest impact with respect to the representation of P and T, followed by the RA parameterization scheme. Both, PBL and MP schemes showed much less impact. We conclude that a multi-facet evaluation can finally lead to better choices about good physics scheme combinations
Joint distribution of the first and second eigenvalues at the soft edge of unitary ensembles
The density function for the joint distribution of the first and second
eigenvalues at the soft edge of unitary ensembles is found in terms of a
Painlev\'e II transcendent and its associated isomonodromic system. As a
corollary, the density function for the spacing between these two eigenvalues
is similarly characterized.The particular solution of Painlev\'e II that arises
is a double shifted B\"acklund transformation of the Hasting-McLeod solution,
which applies in the case of the distribution of the largest eigenvalue at the
soft edge. Our deductions are made by employing the hard-to-soft edge
transitions to existing results for the joint distribution of the first and
second eigenvalue at the hard edge \cite{FW_2007}. In addition recursions under
of quantities specifying the latter are obtained. A Fredholm
determinant type characterisation is used to provide accurate numerics for the
distribution of the spacing between the two largest eigenvalues.Comment: 26 pages, 1 Figure, 2 Table
Finite-size scaling analysis of the distributions of pseudo-critical temperatures in spin glasses
Using the results of large scale numerical simulations we study the
probability distribution of the pseudo critical temperature for the
three-dimensional Edwards-Anderson Ising spin glass and for the fully connected
Sherrington-Kirkpatrick model. We find that the behavior of our data is nicely
described by straightforward finite-size scaling relations.Comment: 23 pages, 9 figures. Version accepted for publication in J. Stat.
Mec
Transport and Deposition of Saharan Dust Observed from Satellite Images and Ground Measurements
Haboob occurrence strongly impacts the annual variability of airborne desert dust in North Africa. In fact, more dust is raised from erodible surfaces in the early summer (monsoon) season when deep convective storms are common but soil moisture and vegetation cover are low. On 27 June 2018, a large dust storm is initiated over North Africa associated with an intensive westward dust transport. Far away from emission sources, dust is transported over the Atlantic for the long distance. Dust plume is emitted by a strong surface wind and further becomes a type of haboob when it merges with the southwestward deep convective system in central Mali at 0200 UTC (27 June). We use satellite observations to describe and estimate the dust mass concentration during the event. Approximately 93% of emitted dust is removed the dry deposition from the atmosphere between sources (10°Nâ25°N; 1°Wâ8°E) and the African coast (6°Nâ21°N; 16°Wâ10°W). The convective cold pool has induced large economic and healthy damages, and death of animals in the northeastern side of Senegal. ERA5 reanalysis has shown that the convective mesoscale impacts strongly the climatological location of the Saharan heat low (SHL)
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