1,449 research outputs found
Variations in agronomic and grain quality traits of rice grown under irrigated lowland conditions in West Africa
Rice breeding in West Africa has been largely skewed toward yield enhancement and stress tolerance. This has led to the variable grain quality of locally produced rice in the region. This study sought to assess variations in the agronomic and grain quality traits of some rice varieties grown in this region, with a view to identifying sources of high grain yield and quality that could serve as potential donors in their breeding programs. Forty‐five varieties were grown under irrigated conditions in Benin and Senegal with two trials in each country. There were wide variations in agronomic and grain quality traits among the varieties across the trials. Cluster analysis using paddy yield, head rice yield, and chalkiness revealed that 68% of the total variation could be explained by five varietal groupings. One group comprising seven varieties (Afrihikari, BG90‐2, IR64, Sahel 108, WAT311‐WAS‐B‐B‐23‐7‐1, WAT339‐TGR‐5‐2, and WITA 10) had high head rice yield and low chalkiness. Of the varieties in this group, Sahel 108 had the highest paddy yield in three of the four trials. IR64 and Afrihikari had intermediate and low amylose content, respectively, with the rest being high‐amylose varieties. Another group of varieties consisting of B6144F‐MR‐6‐0‐0, C74, IR31851‐96‐2‐3‐2‐1, ITA222, Jaya, Sahel 305, WITA 1, and WITA 2 had high paddy yield but poor head rice yield and chalkiness. The use of materials from these two groups of varieties could accelerate breeding for high yielding rice varieties with better grain quality for local production in West Africa
Paramètres morphobiométriques et biochimiques des chevaux de traction au Sénégal
Le cheval de traction joue un important rôle dans l'agriculture et le transport interurbain. Cependant, il existe peu de données sur les paramètres morphobiométriques et biochimiques des chevaux locaux. Ces données sont pourtant nécessaires pour une prise en charge clinique. Cette étude visait la détermination de ces paramètres. Pour ce faire, 97 chevaux mâles ont été sélectionnés dans les Régions de Kaolack et Saint-Louis. Les chevaux étaient répartis en 3 groupes d’âge : G1 [2-3ans], G2 [4-9ans] et G3 [10-27ans] et en deux groupes selon la note d’état corporel (NEC). Les paramètres morphobiométiques ont été mesurés à l’aide d’une toise et d’un mètre-ruban. Tandis que les paramètres biochimiques ont été dosés à l’aide de kits commerciaux (Biosystem®). Des variations ont été notées dans les valeurs des paramètres biochimiques et orphobiométriques. Ainsi, les valeurs du phosphore, du calcium, du cholestérol, de l’urée, de l’ASAT et de la créatinine ont varié significativement selon la région (p<0,05). De même, la hauteur au garrot et de la Longueur du tronc ont varié en fonction de la localité (p<0,001). Les valeurs de l’urée, de la créatinine, du calcium et du phosphore ont varié significativement avec l’âge (p<0,05). L’établissement des paramètres biochimiques permettra une meilleure prise en charge clinique des chevaux de traction au Sénégal.Mots clés : Cheval de traction, paramètres morphobiométriques, paramètres biochimiques, Sénégal
Characterization of virulence factors in the newly described <i>Salmonella enterica</i> serotype Keurmassar emerging in Senegal (sub-Saharan Africa)
From 2000 to 2001, nine strains of Salmonella enterica belonging to the new serotype Keurmassar
have been isolated from human and poultry samples at the Senegalese National Salmonella and
Shigella Reference Laboratory at the Pasteur Institute, in Dakar. All strains carried virulence
factors including Salmonella Pathogenicity Islands (SPI)-1, -2, -3 and -5 encoded genes. Strains
did not harbour virulence plasmid. Ribotyping analysis revealed a single clone identical to
Salmonella Decatur isolated in Zimbabwe. These data suggest that strains are closely related,
and may have been spread clonally. In this new serotype, insertion sequence IS200 is not present
Public-private partnership for inclusive sanitation in informal and peri-urban areas of Ouagadougou
21% of the total population of the capital city live in settlements in peri urban areas of Ouagadougou which are illegal and informal and hence, pose a challenge to the traditional way of delivering basic services in urban areas. Around 94% of this population lack access to improved latrines and nearly 19% practice open defecation. As a result, water borne diseases are the main cause of consultations in health centres. To improve access to sanitation, WaterAid has worked with the municipality of Ouagadougou and the water utility, to initiate a project allowing private operators to provide informal settlements with the same services as the formal sectors. The project helped move the household sanitation access rate from 6.1% to 9.4% in 3 years. The learning gathered provides insights into the institutionalization and sustainability of this approach as a means to achieve universal access to sanitation
Visualizing Profiles of Large Datasets of Weighted and Mixed Data
This work provides a procedure with which to construct and visualize profiles, i.e., groups of individuals with similar characteristics, for weighted and mixed data by combining two classical multivariate techniques, multidimensional scaling (MDS) and the k-prototypes clustering algorithm. The well-known drawback of classical MDS in large datasets is circumvented by selecting a small random sample of the dataset, whose individuals are clustered by means of an adapted version of the k-prototypes algorithm and mapped via classical MDS. Gower’s interpolation formula is used to project remaining individuals onto the previous configuration. In all the process, Gower’s distance is used to measure the proximity between individuals. The methodology is illustrated on a real dataset, obtained from the Survey of Health, Ageing and Retirement in Europe (SHARE), which was carried out in 19 countries and represents over 124 million aged individuals in Europe. The performance of the method was evaluated through a simulation study, whose results point out that the new proposal solves the high computational cost of the classical MDS with low error.This research was funded by the Spanish Ministry of Economy and Competitiveness, grant number MTM2014-56535-R; and the V Regional Plan for Scientific Research and Technological Innovation 2016-2020 of the Community of Madrid, an agreement with Universidad Carlos III de Madrid in the action of "Excellence for University Professors.
Contribution of spicules to solar coronal emission
Recent high-resolution imaging and spectroscopic observations have generated
renewed interest in spicules' role in explaining the hot corona. Some studies
suggest that some spicules, often classified as type II, may provide
significant mass and energy to the corona. Here we use numerical simulations to
investigate whether such spicules can produce the observed coronal emission
without any additional coronal heating agent. Model spicules consisting of a
cold body and hot tip are injected into the base of a warm ( MK)
equilibrium loop with different tip temperatures and injection velocities. Both
piston- and pressure-driven shocks are produced. We find that the hot tip cools
rapidly and disappears from coronal emission lines such as Fe XII and Fe
XIV . Prolonged hot emission is produced by pre-existing loop material
heated by the shock and by thermal conduction from the shock. However, the
shapes and Doppler shifts of synthetic line profiles show significant
discrepancies with observations. Furthermore, spatially and temporally averaged
intensities are extremely low, suggesting that if the observed intensities from
the quiet Sun and active regions were solely due to type II spicules, one to
several orders of magnitude more spicules would be required than have been
reported in the literature. This conclusion applies strictly to the ejected
spicular material. We make no claims about emissions connected with waves or
coronal currents that may be generated during the ejection process and heat the
surrounding area.Comment: Accepted for publication in the Astrophysical Journal, 16 pages, 17
figure
Étude des caractéristiques des peuplements et des noix de Cocos nucifera L. au Sénégal
Cocos nucifera est l’un des arbres cultivés le plus répandu. Il se propage par graine avec un long cycle biologique. Cette étude qui avait pour objectif de caractériser les populations naturelles de cocotiers des Niayes (Sénégal), notamment leur structure et leur fruit, a montré que les arbres sont âgés et leur régénération quasi inexistante. Les hauteurs variaient de 7 à 17,5 m et les circonférences à 1,30 m de 60 à 182 cm. Les arbres étaient sains et présentaient un faible taux de mortalité (2 à 5%). La morphologie des noix de coco, leur poids et celui de leurs constituants (eau, coprah), étaient variables selon les sites de récolte. Les noix avaient un poids moyen de 1,5 kg. Leur volume d’eau a varié avec le stade de maturité: 350 à 430 ml pour les «noix à eau et sans coprah» et 38 à 70 ml pour les «noix mûres». Le poids de coprah frais a varié entre les sites de 170 à 210 g. En perspective, il serait intéressant d’analyser la variabilité existante afin de l’exploiter dans un programme d’amélioration. Dans le souci de préserver le cocotier dans les Niayes, il faudrait envisager des plantations dans toute cette zone.Mots clés : Cocos nucifera, cocotier, coprah, niayes, palmie
Determining Pair Interactions from Structural Correlations
We examine metastable configurations of a two-dimensional system of
interacting particles on a quenched random potential landscape and ask how the
configurational pair correlation function is related to the particle
interactions and the statistical properties of the potential landscape.
Understanding this relation facilitates quantitative studies of magnetic flux
line interactions in type II superconductors, using structural information
available from Lorentz microscope images or Bitter decorations.
Previous work by some of us supported the conjecture that the relationship
between pair correlations and interactions in pinned flux line ensembles is
analogous to the corresponding relationship in the theory of simple liquids.
The present paper aims at a more thorough understanding of this relation. We
report the results of numerical simulations and present a theory for the low
density behavior of the pair correlation function which agrees well with our
simulations and captures features observed in experiments. In particular, we
find that the resulting description goes beyond the conjectured classical
liquid type relation and we remark on the differences.Comment: 7 pages, 6 figures. See also http://rainbow.uchicago.edu/~grier
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