Linear free divisors and Frobenius manifolds

We study linear functions on fibrations whose central fibre is a linear free divisor. We analyse the Gauß–Manin system associated to these functions, and prove the existence of a primitive and homogenous form. As a consequence, we show that the base space of the semi-universal unfolding of such a function carries a Frobenius manifold structure

A quasi-static nonlinear analysis for assessing the fire resistance of 3d frames exploiting time-dependent yield surface

In this work an automatic procedure for evaluating the axial force-biaxial bending yield surface of reinforced concrete sections in fire is proposed. It provides an accurate time-dependent expression of the yield condition by a section analysis carried out once and for all, accounting for the strength reduction of the materials, which is a function of the fire duration. The equilibrium state of 3D frames with such yield conditions, once discretized using beam finite elements, is formulated as a nonlinear vectorial equation defining a curve in the hyperspace of the discrete variables and the fire duration. A generalized path-following strategy is proposed for tracing this curve and evaluating, if it exists, the limit fire duration, that is the time of exposure which leads to structural collapse. Compared to the previous proposals on the topic, which are limited to local sectional checks, this work is the first to present a global analysis for assessing the fire resistance of 3D frames, providing a time history of the fire event and taking account of the stress redistribution. Numerical examples are given to illustrate and validate the proposal

Amélioration de la teneur en fer et en zinc du riz pour l'alimentation humaine

La carence en oligoéléments touche plus de 3,7 milliards de personnes dans le monde, essentiellement des femmes et des enfants en raison de leurs besoins physiologiques. Les carences en fer et en zinc sont à l'origine de déficiences immunitaires, de complications au niveau de la grossesse et de l'enfantement, d'un développement difficile chez l'enfant, de capacités d'apprentissage et d'une productivité moindres. En 1992, l'Irri a débuté des recherches sur l'influence de certaines caractéristiques du sol sur la teneur en fer des céréales, recherche qu'il a étendue au zinc en 1995 en collaboration avec l'université d'Adélaïde, en Australie, concernant l'analyse des minéraux. Le criblage du germoplasme a révélé une importante variabilité génétique concernant le fer et le zinc du riz complet. Les teneurs en fer et en zinc des variétés couramment cultivées sont de l'ordre de 12 milligrammes par kilogramme et 25 milligrammes par kilogramme, respectivement ; certaines variétés traditionnelles présentent des valeurs doubles de celles-ci. L'étude génétique du caractère de teneur élevée en fer a montré l'importance des effets de dominance et d'additivité et l'incidence moindre de l'environnement. Par ailleurs, trois QTL de teneur élevée en fer ont été marqués sur des chromosomes de riz. Les teneurs élevées en fer et en zinc peuvent être combinées avec des caractères agronomiques améliorés. L'Irri a identifié du riz amélioré associant une bonne aptitude au rendement et des grains à concentration élevée en fer et en zinc dans les grains. Compte tenu de l'importance de la consommation de riz dans les pays en développement, des variétés à teneurs élevées en fer et en zinc pourraient avoir un impact significatif sur la nutrition et la santé des populations concernée

Improving iron and zinc value of rice for human nutrition

Micronutrient deficiency 'hidden hunge' + affects more than 3.7 billion people worldwide, predominantly women and children because of their physiological needs. Iron and zinc deficiencies cause impaired immune function, complications in pregnancy and childbirth, poor child growth and learning ability, and reduce labor productivity. In 1992, IRRI began to examine the effect of certain soil characteristics on the iron content in the grain and was expanded in 1995 to include zinc and collaboration with university of Adelaide, Australia for mineral analysis. Germplasm screening showed large genetic variation for Fe and Zn in brown rice. Common cultivars contain about 12mg kg-1 of iron and 25mg kg-1 Zn. Some traditional varieties have doubled these amounts. Genetics of high Fe trait showed the importance of additive and dominance gene action but less affected by environment. Moreover three QTLS for high Fe trait were tagged in rice chromosomes. High iron and zinc traits can be combined with improved agronomic traits. IRRI identified improved rice with good yielding ability and high concentration of iron and zinc in the grain. Because of the high consumption of rice in developing countries, the extra iron and zinc would have meaningful impact on human nutrition and healt

Is ALT control really necessary for routine ART monitoring in resource poor settings?

2006 AIDS Conference in Toront

Clarification of the Bootstrap Percolation Paradox

We study the onset of the bootstrap percolation transition as a model of generalized dynamical arrest. We develop a new importance-sampling procedure in simulation, based on rare events around "holes", that enables us to access bootstrap lengths beyond those previously studied. By framing a new theory in terms of paths or processes that lead to emptying of the lattice we are able to develop systematic corrections to the existing theory, and compare them to simulations. Thereby, for the first time in the literature, it is possible to obtain credible comparisons between theory and simulation in the accessible density range.Comment: 4 pages with 3 figure

Fossil biomass preserved as graphitic carbon in a late paleoproterozoic banded iron formation metamorphosed at more than 550°C

Metamorphism is thought to destroy microfossils, partly through devolatilization and graphitization of biogenic organic matter. However, the extent to which there is a loss of molecular, elemental and isotope signatures from biomass during high-temperature metamorphism is not clearly established. We report on graphitic structures inside and coating apatite grains from the c. 1850 Ma Michigamme silicate banded iron formation from Michigan, metamorphosed above 550°C. Traces of N, S, O, H, Ca and Fe are preserved in this graphitic carbon and X-ray spectra show traces of aliphatic groups. Graphitic carbon has an expanded lattice around 3.6 Å, forms microscopic concentrically-layered and radiating polygonal flakes and has homogeneous δ13C values around −22‰, identical to bulk analyses. Graphitic carbon inside apatite is associated with nanometre-size ammoniated phyllosilicate. Precursors of these metamorphic minerals and graphitic carbon originated from ferruginous clayrich sediments with biomass. We conclude that graphite coatings and inclusions in apatite grains indicate fluid remobilization during amphibolite-facies metamorphism of precursor biomass. This new evidence fills in observational gaps of metamorphosed biomass into graphite and supports the existence of biosignatures in the highly metamorphosed iron formation from the Eoarchean Akilia Association, which dates from the beginning of the sedimentary rock record

On Singularity Formation of a Nonlinear Nonlocal System

We investigate the singularity formation of a nonlinear nonlocal system. This nonlocal system is a simplified one-dimensional system of the 3D model that was recently proposed by Hou and Lei in [13] for axisymmetric 3D incompressible Navier-Stokes equations with swirl. The main difference between the 3D model of Hou and Lei and the reformulated 3D Navier-Stokes equations is that the convection term is neglected in the 3D model. In the nonlocal system we consider in this paper, we replace the Riesz operator in the 3D model by the Hilbert transform. One of the main results of this paper is that we prove rigorously the finite time singularity formation of the nonlocal system for a large class of smooth initial data with finite energy. We also prove the global regularity for a class of smooth initial data. Numerical results will be presented to demonstrate the asymptotically self-similar blow-up of the solution. The blowup rate of the self-similar singularity of the nonlocal system is similar to that of the 3D model.Comment: 28 pages, 9 figure

A submillimeter search for pre- and proto-brown dwarfs in Chamaeleon II

Context. Chamaeleon II molecular cloud is an active star forming region that offers an excellent opportunity for studying the formation of brown dwarfs in the southern hemisphere. Aims. Our aims are to identify a population of pre- and proto- brown dwarfs (5 sigma mass limit threshold of ~0.015 Msun) and provide information on the formation mechanisms of substellar objects. Methods. We performed high sensitivity observations at 870 microns using the LABOCA bolometer at the APEX telescope towards an active star forming region in Chamaeleon II. The data are complemented with an extensive multiwavelength catalogue of sources from the optical to the far-infrared to study the nature of the LABOCA detections. Results. We detect fifteen cores at 870 microns, and eleven of them show masses in the substellar regime. The most intense objects in the surveyed field correspond to the submillimeter counterparts of the well known young stellar objects DK Cha and IRAS 12500-7658. We identify a possible proto-brown dwarf candidate (ChaII-APEX-L) with IRAC emission at 3.6 and 4.5 microns. Conclusions. Our analysis indicates that most of the spatially resolved cores are transient, and that the point-like starless cores in the sub-stellar regime (with masses between 0.016 Msun and 0.066 Msun) could be pre-brown dwarfs cores gravitationally unstable if they have radii smaller than 220 AU to 907 AU (1.2" to 5" at 178 pc) respectively for different masses. ALMA observations will be the key to reveal the energetic state of these pre-brown dwarfs candidates.Comment: 11 pages, 6 figure

Nursery management in relation to root deformation, sowing and shading

The polybag is widely used for seedling production in the Philippines. Seedlings commonly have root deformation which has adverse effects as they grow and develop into mature trees. This study assessed the influence of potting technique and hardening intensity on the growth performance of seedlings in nursery and field conditions. Seedlings of bagras (Eucalyptus deglupta) and mangium (Acacia mangium) were grown in hiko trays and 4" x 6" polybags at the College of Forestry nursery, Leyte State University (LSU). Kalumpit (Terminalia microcarpa) and pellita (Eucalyptus pellita) were used for a trial in the Conalum Agroforestry Farmers Association (CAFA) nursery in Inopacan, Leyte, aimed at validating LSU results and at the same time evaluating farmers' perceptions on the use of hiko trays and polybags in seedling production. It was found that seedlings of bagras, mangium, kalumpit and pellita grown in hiko trays have smaller diameter and height compared with those in polybags at 12 weeks. Root deformation of seedlings was absent in hiko trays but high with seedlings in polybags. As perceived by both farmers and ACIAR researchers, hiko tray seedlings are of high quality exhibiting sturdy shoot, trained roots and homogenous growth