931 research outputs found
La lutte contre les schistosomoses en Afrique de l'Ouest
Au Mali, la lutte contre les mollusques a Ă©tĂ© l'une des mĂ©thodes de lutte prĂ©conisĂ©es par le Programme National de Lutte en mĂȘme temps que la chimiothĂ©rapie de masse, l'assainissement et l'Ă©ducation pour la santĂ©. Des trois mĂ©thodes de lutte contre les mollusques, chimique, biologique et environnementale, seule la premiĂšre a vraiment Ă©tĂ© utilisĂ©e. Le niclosamide en poudre mouillable, Ă la dose de 1 Ă 8 ppm selon le site de transmission traitĂ©, a Ă©tĂ© recommandĂ© jusqu'en 1989. Le mĂ©diocre rapport coĂ»t/efficacitĂ© a fait abandonner cette stratĂ©gie. La recherche de plantes molluscicides est poursuivie pour proposer une technique alternative au niclosamide. La lutte environnementale, notamment le dĂ©sherbage des sites de transmission, est une recommandation du programme national de lutte. (RĂ©sumĂ© d'auteur
FEEDER CATTLE PRICE SLIDES
A theoretical model is developed to explain the economics of determining price slides for feeder cattle. The contract is viewed as a dynamic game with continuous strategies where the buyer and seller are the players. The model provides a solution for the price slide that guarantees an unbiased estimate of cattle weight. An empirical model using Superior Livestock Auction (SLA) data shows price slides used are smaller than those needed to cause the producer to give unbiased estimates of weight. Consistent with the model's predictions, producers slightly underestimate cattle weights.Demand and Price Analysis,
Cotton Price Policy and New Cereal Technology in the Malian Cotton Zone
During the last decade, cotton production and area have been declining as a result of depleting soil nutrients and low cotton prices in the cotton zone of Mali. This paper shows that the Malian governmentâs 2011 policy to increase the farm gate cotton price as a response to world cotton price increase enhances farm income but has less impact on cotton than on maize production. A complementary policy of introducing new sorghum technologies would have an equal impact on farmersâ incomes in the cotton zone of Mali.Cotton prices, improved sorghum technology, discrete stochastic programming, Mali, Agricultural and Food Policy, Farm Management, International Development, Production Economics, Risk and Uncertainty,
Spatiotemporal chaos induces extreme events in an extended microcavity laser
Extreme events such as rogue wave in optics and fluids are often associated
with the merging dynamics of coherent structures. We present experimental and
numerical results on the physics of extreme events appearance in a spatially
extended semiconductor microcavity laser with intracavity saturable absorber.
This system can display deterministic irregular dynamics only thanks to spatial
coupling through diffraction of light. We have identified parameter regions
where extreme events are encountered and established the origin of this
dynamics in the emergence of deterministic spatiotemporal chaos, through the
correspondence between the proportion of extreme events and the dimension of
the strange attractor
La lutte contre les schistosomoses en Afrique de l'Ouest
DeuxiĂšme endĂ©mie parasitaire du Mali, les schistosomoses sont irrĂ©guliĂšrement rĂ©parties dans le pays. #Schistosoma haematobium atteint 2 millions et demi de sujets et est assez largement rĂ©pandu. #S. mansoni est focalisĂ© dans les rĂ©gions rizicoles du centre du pays, le pays dogon et la rĂ©gion de Kayes. La lutte contre les schistosomoses a commencĂ© dans les annĂ©es soixante-dix par des programmes localisĂ©s. Ces programmes ont Ă©tĂ© rĂ©unis en un programme national de lutte en 1982. La dĂ©centralisation et l'intĂ©gration des activitĂ©s aux structures nationales de santĂ© a Ă©tĂ© dĂ©cidĂ©e en 1986. La mise en oeuvre du programme national de lutte a dĂ©butĂ© aussitĂŽt aprĂšs par la formation des Ă©quipes pĂ©riphĂ©riques et l'Ă©quipement des structures sanitaires. Les stratĂ©gies de base retenues sont le dĂ©pistage des cas et la chimiothĂ©rapie Ă la fois dans les centres de santĂ© et les Ă©coles. L'Ă©ducation pour la santĂ©, l'assainissement et l'approvisionnement en eau potable sont associĂ©s. Une surveillance Ă©pidĂ©miologique est organisĂ©e. Trois phases successives ont conduit le programme national de lutte Ă ĂȘtre intĂ©grĂ© Ă l'ensemble des activitĂ©s des structures de santĂ© pĂ©riphĂ©riques. Les difficultĂ©s rencontrĂ©es sont Ă©voquĂ©es. (RĂ©sumĂ© d'auteur
Surgical complications of Pica syndrome: About 3 cases
The Pica syndrome is an eating disorder characterized by an excessive or abnormal desire to consume a non-nourishing substance which can be relatively harmless, or potentially harmful for the health. It is a rare affection secondary to the accumulation of diverse natured foreign bodies inside the digestive tract and more especially at the stomach level. Gastro-intestinal localization is the most frequent, and can remain asymptomatic for a long time. Treatment is surgical. We report 3 cases of digestive complications of Pica syndrome
Evaluation de lâeffet repulsif dâextraits de neem (Azadirachta indica A. Juss., 1830) sur le charançon de la patate douce (Cylas puncticollis Boheman, 1833) en condition de laboratoire a Korhogo, nord de la Cote dâIvoire
Une stratĂ©gie de gestion intĂ©grĂ©e des insectes nuisibles Ă la culture de la patate douce a Ă©tĂ© Ă©laborĂ©e pour rĂ©duire les pertes dues Ă ceux-ci. Ainsi, les propriĂ©tĂ©s rĂ©pulsives des extraits de feuilles et dâamandes de neem ont Ă©tĂ© Ă©valuĂ©es sur Cylas puncticollis, un charançon de la patate douce. Pour ce faire, quatre concentrations dâextraits ont Ă©tĂ© prĂ©parĂ©es Ă raison de quatre rĂ©pĂ©titions par concentration. Le test a consistĂ© Ă la dĂ©termination du pourcentage de charançons prĂ©sents dans la zone traitĂ©e. Chacune des concentrations dâextraits a Ă©tĂ© appliquĂ©e sur la moitiĂ© dâun papier buvard placĂ© dans une boite de PĂ©tri de 9 cm de diamĂštre et sur lequel 10 charançons ont Ă©tĂ© posĂ©s. Les effets rĂ©pulsifs des extraits ont Ă©tĂ© comparĂ©s Ă ceux dâun insecticide chimique et lâeau distillĂ©e. Le test avec 20 cL/L dâextraits de feuilles a causĂ© 85 % de rĂ©pulsion contre 45 % pour les amandes Ă 25 g/L. Les extraits ont significativement causĂ© plus de rĂ©pulsion que lâeau distillĂ©e et lâinsecticide chimique. Les tests ont rĂ©vĂ©lĂ© un potentiel plus rĂ©pulsif des extraits de feuilles comparĂ© Ă celui des amandes. Les extraits de neem pourraient constituer une alternative crĂ©dible Ă la lutte chimique pour la protection de la patate douce contre ce charançon.
English title: Evaluation of the repellent effect of neem extracts (Azadirachta indica A. Juss., 1830) on the sweet potato weevil (Cylas puncticollis Boheman, 1833) under laboratory conditions in Korhogo, northern CĂŽte dâIvoire
Abstract
An integrated pest management strategy for sweet potatoes has been developed to reduce pest losses. Thus, the repellent properties of neem leaf and kernel extracts were evaluated on Cylas puncticollis, a sweet potato weevil. For this purpose, four concentrations of extracts were prepared with four replicates per concentration. The test consisted of determining the percentage of weevils in the treated area. Each of the extract concentrations was applied to half of a blotting paper placed in 9 cm diameter Petri dishes on which 10 weevils were placed. The repellent effects of the extracts were compared to those of a chemical insecticide and distilled water. Test with 20 cL/L leaf extract caused 85% repellence compared to 45% for almonds at 25 g/L. Compared to the chemical insecticide and distilled water, the extracts caused significantly more repellence. The tests revealed a higher repellent potential of the leaf extracts compared to those of almonds. Neem extracts could be a credible alternative to chemical control for the protection of sweet potato against this weevil.
Keywords: Neem extracts, Repellent effect, Sweet potato, Cylas puncticolli
Etude contributive Ă la connaissance des populations de simulies dans la commune de BouaflĂ©, Centre-Ouest de la CĂŽte dâIvoire
AprĂšs lâarrĂȘt des activitĂ©s du programme de lutte contre lâonchocercose en Afrique de lâOuest (OCP) en 2002, la CĂŽte dâIvoire nâa pu conduire rĂ©guliĂšrement les activitĂ©s de lutte du fait de la crise socio-politique qui a dĂ©marrĂ© en 2002. La recolonisation abondante des cours dâeau par les simulies et son corollaire la nuisance simulidienne le long de certains bassins versants, est due au fait que de vastes rĂ©gions plus ou moins forestiĂšres nâont jamais Ă©tĂ© traitĂ©es rĂ©guliĂšrement par les insecticides contre les populations larvaires de simulies vectrices. Lâobjectif gĂ©nĂ©ral du travail est de contribuer Ă la connaissance de la dynamique des populations de simulies et de la transmission de lâonchocercose en CĂŽte dâIvoire et particuliĂšrement aux alentours du fleuve MarahouĂ©Â dans la commune de BouaflĂ©. La technique de capture des simulies sur appĂąt humain a Ă©tĂ© utilisĂ©e. Les rĂ©sultats indiquent une forte nuisance simulidienne (117 piqĂ»res / Homme / Jour) avec un pic lâaprĂšs-midi. Les simulies capturĂ©es sont essentiellement (99,1%) des espĂšces savanicoles ; elles prĂ©sentent une grande longĂ©vitĂ©Â (64.44%). Du point de vue transmission, aucune simulie femelle infectĂ©e ou infectieuse nâa Ă©tĂ© dĂ©celĂ©e pendant la durĂ©e de lâĂ©tude.Mots clĂ©s : Onchocercose, espĂšces savanicoles, dynamique de populations, nuisance simulidienne, transmission
Stacking tolerance to drought and resistance to a parasitic weed in tropical hybrid maize for enhancing resilience to stress combinations
Open Access JournalMaize is a food security crop cultivated in the African savannas that are vulnerable to the occurrence of drought stress and Striga hermonthica infestation. The co-occurrence of these stresses can severely damage crop growth and productivity of maize. Until recently, maize breeding in International Institute of Tropical Agriculture (IITA) has focused on the development of either drought tolerant or S. hermonthica resistant germplasm using independent screening protocols. The present study was therefore conducted to examine the extent to which maize hybrids simultaneously expressing resistance to S. hermonthica and tolerance to drought (DTSTR) could be developed through sequential selection of parental lines using the two screening protocols. Regional trials involving 77 DTSTR and 22 commercial benchmark hybrids (STR and non-DTSTR) were then conducted under Striga-infested and non-infested conditions, managed drought stress and fully irrigated conditions as well as in multiple rainfed environments for 5 years. The observed yield reductions of 61% under managed drought stress and 23% under Striga-infestation created desirable stress levels leading to the detection of significant differences in grain yield among hybrids at individual stress and non-stress conditions. On average, the DTSTR hybrids out-yielded the STR and non-DTSTR commercial hybrids by 13â19% under managed drought stress and fully irrigated conditions and by â4 to 70% under Striga-infested and non-infested conditions. Among the DTSTR hybrids included in the regional trials, 33 were high yielders with better adaptability across environments under all stressful and non-stressful testing conditions. Twenty-four of the 33 DTSTR hybrids also yielded well across diverse rainfed environments. The genetic correlations of grain yield under managed drought stress with yield under Striga-infestation and multiple rainfed environments were 0.51 and 0.57, respectively. Also, a genetic correlation between yields under Striga-infestation with that recorded in multiple rainfed environments was 0.58. These results suggest that the sequential selection scheme offers an opportunity to accumulate desirable stress-related traits in parents contributing to superior agronomic performance in hybrids across stressful and diverse rainfed field environments that are commonly encountered in the tropical savannas of Africa
Extreme events prediction from nonlocal partial information in a spatiotemporally chaotic microcavity laser
The forecasting of high-dimensional, spatiotemporal nonlinear systems has
made tremendous progress with the advent of model-free machine learning
techniques. However, in real systems it is not always possible to have all the
information needed; only partial information is available for learning and
forecasting. This can be due to insufficient temporal or spatial samplings, to
inaccessible variables or to noisy training data. Here, we show that it is
nevertheless possible to forecast extreme events occurrence in incomplete
experimental recordings from a spatiotemporally chaotic microcavity laser using
reservoir computing. Selecting regions of maximum transfer entropy, we show
that it is possible to get higher forecasting accuracy using nonlocal data vs
local data thus allowing greater warning times, at least twice the time horizon
predicted from the nonlinear local Lyapunov exponent
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