40 research outputs found
Nematode distribution and damage to yam in central and eastern Uganda
Yams (Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunately, nematodes are major pests to their production. A study was undertaken in major yam growing areas of Uganda to investigate the association of plant parasitic nematodes with damage symptoms. Nematodes were assessed from tubers, roots and surrounding soil for seven cultivars belonging to Dioscorea alata, D. bulbisiana, D. burkilliana and D. cayenensis at harvest. Pratylenchus sudanensis was found in the greatest density and was followed byMeloidogyne spp. Higher densities of both nematodes were observed in the tubers rather than roots. Although symptoms of cracking and galling were relatively low, P. sudanensis incidence was strongly associated with cracking and Meloidogyne spp. with galling. Pratylenchus sudanensis and Meloidogyne spp. incidence their associated damage were, however, negatively correlated, suggesting inter-species competition. Principal components analysis of data suggested that differences in susceptibility to P. sudanensis occur between yam cultivars and species
Combined exome and whole-genome sequencing identifies mutations in ARMC4 as a cause of primary ciliary dyskinesia with defects in the outer dynein arm
Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous ciliopathy disorder affecting cilia and sperm motility. A range of ultrastructural defects of the axoneme underlie the disease, which is characterised by chronic respiratory symptoms and obstructive lung disease, infertility and body axis laterality defects. We applied a next-generation sequencing approach to identify the gene responsible for this phenotype in two consanguineous families
Nematode distribution and damage to yam in Central and Eastern Uganda
Yams (Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunately, nematodes are major pests to their production. A study was undertaken in major yam growing areas of Uganda to investigate the association of plant parasitic nematodes with damage symptoms. Nematodes were assessed from tubers, roots and surrounding soil for seven cultivars belonging to Dioscorea alata, D. bulbisiana, D.burkilliana and D. cayenensis at harvest. Pratylenchus sudanensis was found in the greatest density and was followed by Meloidogyne spp. Higher densities of both nematodes were observed in the tubers rather than roots. Although symptoms of cracking and galling were relatively low, P. sudanensis incidence was strongly associated with cracking and Meloidogyne spp. with galling. Pratylenchus sudanensis and Meloidogyne spp. incidence their associated damage were, however, negatively correlated, suggesting inter-species competition. Principal components analysis of data suggested that differences in susceptibility to P. sudanensis occur between yam cultivars and species.Les ignames (Dioscorea spp.) sont une culture alimentaire dâimportance croissante en Afrique subâsaharienne.Malheureusement, les nĂ©matodes sont des parasites majeurs qui gĂȘnent sa production. Une Ă©tude Ă©tait menĂ©edans les principales rĂ©gions productrices de lâigname en Ouganda en vue de pouvoir mener investigation surlâassociation des nĂ©matodes parasitant les plantes avec les symptĂŽmes de dommages. Les nĂ©matodes Ă©taientĂ©valuĂ©s Ă partir des racines, tubercules, et sol environnant pour 7 cultivars appartenant Ă Dioscorea alata, D.bulbisiana, D. burkilliana et D. cayenensis Ă la rĂ©colte. Pratylenchus sudanensis Ă©tait considĂ©rĂ©e lâespĂšce Ă plushaute densitĂ© et Ă©tait suivie par Meloidogyne spp. Des densitĂ©s plus Ă©levĂ©es des nĂ©matodes Ă©taient observĂ©esplus dans les tubercules que dans les racines. Bien que les symptĂŽmes de craquelures et dâirritations Ă©taientrelativement bas, P.Sudanensis et Meloidogyne spp. Ă©taient respectivement associĂ©es Ă la craquelure et Ă lâirritation.Pratylenctus Sudanensis et Meloidogyne spp. prĂ©sentaient des damages associĂ©s, qui Ă©taient cependant nĂ©gativementcorrĂ©lĂ©s suggĂ©rant une compĂ©tition inter-espĂšces. Lâanalyse principale des donnĂ©es a suggĂ©rĂ© des diffĂ©rences Ă lasusceptibilitĂ© du P. Sudanensis surviennent entre cultivars et espĂšces dâignames
Electrochemical Stability and Postmortem Studies of Pt/SiC Catalysts for Polymer Electrolyte Membrane Fuel Cells
In the presented work, the electrochemical
stability of platinized silicon carbide is studied. Postmortem transmission
electron microscopy and X-ray photoelectron spectroscopy were used
to document the change in the morphology and structure upon potential
cycling of Pt/SiC catalysts. Two different potential cycle aging tests
were used in order to accelerate the support corrosion, simulating
start-up/shutdown and load cycling. On the basis of the results, we
draw two main conclusions. First, platinized silicon carbide exhibits
improved electrochemical stability over platinized active carbons.
Second, silicon carbide undergoes at least mild oxidation if not even
silicon leaching
Core-level XPS spectra of supported 3d-metal ultrathin layers : experimental and theoretical studies
In order to discuss the relation between the core level c-XPS spectra and the local electronic and magnetic properties of supported 3d transition metal atoms, we incorporate the various Coulomb and exchange interactions into a generalized impurity Anderson Hamiltonian, both in the initial state (Udd, Jdd) and final state (Udc, Jdc) of the c-XPS process. Then we discuss recent experimental 3s-XPS spectra of Fe and Co ultrathin-layers upon Cr(100) as well as V clusters upon graphite in terms of the two limits of the preceding Hamiltonian : (1) the exchange splitting limit (Jdc) and (2) the dielectric relaxation limit (Udc)
The Native Oxide on Titanium Metal as a Conductive Model Substrate for Oxygen Reduction Reaction Studies
Theory of Angle-Resolved X-Ray Photoemission by Multiple-Scattering Cluster Method. V. Spherical Wave Effects on ARXPS Debye-Waller Factors
Proper direction of male genitalia is prerequisite for copulation in Drosophila, implying cooperative evolution between genitalia rotation and mating behavior
Equisingularity and Simultaneous Resolution of Singularities
Zariski defined equisingularity on an n-dimensional hypersurface V via stratification by "dimensionality type," an integer associated to a point by means of a generic local projection to affine n-space. A possibly more intuitive concept of equisingularity can be based on stratification by simultaneous resolvability of singularities. The two approaches are known to be equivalent for families of plane curve singularities. In higher dimension we ask whether constancy of dimensionality type along a smooth subvariety W of V implies the existence of a simultaneous resolution of the singularities of V along W. (The converse is false.) The underlying idea is to follow the classical inductive strategy of Jung -- begin by desingularizing the discriminant of a generic projection -- to reduce to asking if there is a canonical resolution process which when applied to quasi-ordinary singularities depends only on their characteristic monomials. This appears to be so in dimension 2. In higher dimensions the question i