400 research outputs found
Propagating quality planting material to improve plant health and crop performance. Key practices for dessert banana, plantain and cooking banana: Illustrated guide.
This illustrated guide summarizes the key practices for producing clean planting material of banana with a high yield potential for smallholders, depending on the pests and diseases which are present.
The guide is also designed to contribute to better planning of the propagation of planting material for rural development and disaster relief projects
Reduction and reconstruction of stochastic differential equations via symmetries
An algorithmic method to exploit a general class of infinitesimal symmetries
for reducing stochastic differential equations is presented and a natural
definition of reconstruction, inspired by the classical reconstruction by
quadratures, is proposed. As a side result the well-known solution formula for
linear one-dimensional stochastic differential equations is obtained within
this symmetry approach. The complete procedure is applied to several examples
with both theoretical and applied relevance
Méningoencéphalite aprÚs vaccination antigrippale
RĂ©sumĂ©Nous rapportons le cas dâun homme de 82 ans atteint dâune mĂ©ningoencĂ©phalite aprĂšs vaccination antigrippale rĂ©vĂ©lĂ©e par un Ă©tat de mal Ă©pileptique et dâĂ©volution favorable. Bien quâil nâexiste aucun examen de confirmation, le diagnostic repose sur des critĂšres dâimputabilitĂ© comprenant un bilan Ă©tiologique complet notamment microbiologique. Ce cas, illustrĂ© par des techniques modernes de biologie et dâimagerie, complĂšte les rares et anciens cas dĂ©jĂ dĂ©crits dans la littĂ©rature
Genetically engineered bananas resistant to Xanthomonas wilt disease and nematodes
Banana is an important staple food crop feeding more than 100 million Africans, but is subject to severe productivity constraints due to a range of pests and diseases. Banana Xanthomonas wilt caused by Xanthomonas campestris pv. musacearum is capable of entirely destroying a plantation while nematodes can cause losses up to 50% and increase susceptibility to other pests and diseases. Development of improved varieties of banana is fundamental in order to tackle these challenges. However, the sterile nature of the crop and the lack of resistance in Musa germplasm make improvement by traditional breeding techniques either impossible or extremely slow. Recent developments using genetic engineering have begun to address these problems. Transgenic banana expressing sweet pepper Hrap and Pflp genes have demonstrated complete resistance against X. campestris pv. musacearum in the field. Transgenic plantains expressing a cysteine proteinase inhibitors and/or synthetic peptide showed enhanced resistance to a mixed species population of nematodes in the field. Here, we review the genetic engineering technologies which have potential to improve agriculture and food security in Africa
Boundary-crossing identities for diffusions having the time-inversion property
We review and study a one-parameter family of functional transformations, denoted by (S (ÎČ)) ÎČââ, which, in the case ÎČ<0, provides a path realization of bridges associated to the family of diffusion processes enjoying the time-inversion property. This family includes Brownian motions, Bessel processes with a positive dimension and their conservative h-transforms. By means of these transformations, we derive an explicit and simple expression which relates the law of the boundary-crossing times for these diffusions over a given function f to those over the image of f by the mapping S (ÎČ), for some fixed ÎČââ. We give some new examples of boundary-crossing problems for the Brownian motion and the family of Bessel processes. We also provide, in the Brownian case, an interpretation of the results obtained by the standard method of images and establish connections between the exact asymptotics for large time of the densities corresponding to various curves of each family
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