Determinants of Rice Variety Diversity on Household Farms in the Terai Region of Nepal

Crop genetic resources are the building block of sustainable agricultural development as these can be used to develop crop varieties adaptable to heterogeneous environmental conditions. Nepal is considered the center of origin and diversity for Asian rice, which still has many landraces. However, there has been continuous loss of genetic diversity and concern over it has grown in recent years. The main objective of this paper is to identify the determinants of variety diversity on-farm in the rainfed ecosystem of Nepal by using two-limit Tobit procedure. The diversity on farm appeared to be quite high evaluated based on the number of named varieties grown by the farmers. Majority of the farmers cultivated both modern varieties and landraces simultaneously and the rice production is also getting commercialized gradually. The results showed that the motivating factors for variety diversification are the heterogeneous production environments, risk consideration and farmers' participation in the markets. However, the farmers' dependency on formal extension system for the seed of limited varieties led to reduction in diversity. Diverse crop genetic resources on-farm can generate both commercial and noncommercial benefits. As economies develop, markets play an important role in shaping farmers' choices and use of cultivars diversity. Therefore, the public investments are needed in developing the infrastructures to support the formation of niche markets and increasing the farmers' participation in crop breeding and improvement programs. Also, the formal extension system should be mobilized for the production and distribution of seeds of many varieties including the landraces.diversity, market, Nepal, rice, variety, Crop Production/Industries,

Energy transfer within phycocyanin trimers of Mastigocladus laminosus studied by picosecond time-resolved transient absorption spectroscopy

The transient absorption recovery induced in phycocyanin trimers by picosecond pulses of variable wavelength (570 — 620 nm) has been recorded and analyzed by applying a least-squares multi-exponential fit procedure. The results suggest that in native PC trimers the chromophores exhibit a microheterogeneity with the effect that the derived apparent lifetimes are functions of excitation and probing wavelength. It is suggested that, due to strong excitonic coupling between a-84 and ß-84 chromophores, the lifetime of the terminal acceptor state is reduced to about 900 ps; the apparent energy transfer time from chromophore β-155 to a-84 and ß-84 chromophores varies between 20—50 ps depending on the actual chromophore-protein arrangement (microheterogeneity)

Analytic expression for Taylor-Couette stability boundary

We analyze the mechanism that determines the boundary of stability in Taylor-Couette flow. By simple physical argument we derive an analytic expression to approximate the stability line for all radius ratios and all speed ratios, for co- and counterrotating cylinders. The expression includes viscosity and so generalizes Rayleigh's criterion. We achieve agreement with linear stability theory and with experiments in the whole parameter space. Explicit formulae are given for limiting cases.Comment: 6 pages (LaTeX with REVTEX) including 4 figures (Postscript) Revised, discussion of two additional references. See also http://staff-www.uni-marburg.de/~esse

A Concept for Attribute-Based Authorization on D-Grid Resources

In Germany's D-Grid project numerous Grid communities are working together to provide a common overarching Grid infrastructure. The major aims of D-Grid are the integration of existing Grid deployments and their interoperability. The challenge lies in the heterogeneity of the current implementations: three Grid middleware stacks and different Virtual Organization management approaches have to be embraced to achieve the intended goals. In this article we focus oil the implementation of an attribute-based authorization infrastructure that not only leverages the well-known VO attributes but also campus attributes managed by a Shibboleth federation

Principal noncommutative torus bundles

In this paper we study continuous bundles of C*-algebras which are non-commutative analogues of principal torus bundles. We show that all such bundles, although in general being very far away from being locally trivial bundles, are at least locally trivial with respect to a suitable bundle version of bivariant K-theory (denoted RKK-theory) due to Kasparov. Using earlier results of Echterhoff and Williams, we shall give a complete classification of principal non-commutative torus bundles up to equivariant Morita equivalence. We then study these bundles as topological fibrations (forgetting the group action) and give necessary and sufficient conditions for any non-commutative principal torus bundle being RKK-equivalent to a commutative one. As an application of our methods we shall also give a K-theoretic characterization of those principal torus-bundles with H-flux, as studied by Mathai and Rosenberg which possess "classical" T-duals.Comment: 33 pages, to appear in the Proceedings of the London Mathematical Societ