An investigation of alternative bean seed marketing channels in Uganda

The distribution of newly released bean seed is often a weak link in the technology transfer process. To assist national commodity programs to devise cost-effective delivery systems, research was conducted in Uganda to test the appropriateness of bean seed distribution through four non-conventional channels: rural shops, a rural health clinic, women`s groups and an NGO. The findings confirm the feasibility of distributing seed packets through market and non-market channels and show that each delivery system has advantages and disadvantages which must be assessed by seed suppliers in a country-specific context. The paper offers guidelines for the distribution of new bean varieties by formal institution

African bean production environments: their definition, characteristics and constraints

Bean production in Africa is very heterogeneous with much variation in environmental conditions, cropping systems, preferences and constraints. This working document contains information on the many bean producing areas in Africa. The data were gleaned from numerous sources but a major part of these are from the observations of CIAT and national bean program researchers over the last ten years. Thirteen bean producing environments are defined from consideration of altitude, latitude, soil pH and seasonal rainfall. Seventy bean producing areas, having estimated annual bean production of between 2,000 and 220,000 hectares, are described on the bases of environmental and socio-economic characteristics, cropping systems, farmer and consumer preferences, and biotic and abiotic constraints. The importance of the constraints was evaluated both on a pan-African and a regional basis. Angular leaf spot, anthracnose, bean stem maggot, bruchids, low soil nitrogen and low soil phosphorus were determined to be the most important constraints to greater productivity on a pan-African basis

Spin-polarized tunneling between an antiferromagnet and a ferromagnet: First-principles calculations and transport theory

By combining first-principles calculations with transport theory we investigate the origin of the magnetoresistance of a magnetic tunnel junction consisting of a ferromagnetic and an antiferromagnetic lead. The (001) oriented Fe/vacuum/Cr planar junction serves as model junction. Even though the conduction electrons of antiferromagnetic Cr are spin-degenerate, it is possible to observe magnetoresistance due to two mechanisms: Firstly, the surface magnetism of Cr creates a spin-dependent potential barrier, and secondly, exchange-split surface states and resonances result in a tunneling conductance which depends on the relative orientation of the Fe and Cr magnetizations. Spin-dependent tunneling between a ferromagnet and an antiferromagnet happens frequently in tunneling setups such as in spin-polarized scanning tunneling microscopy or magnetic tunnel junctions for magnetic random access memory

Density of Phonon States in Superconducting FeSe as a Function of Temperature and Pressure

The temperature and pressure dependence of the partial density of phonon states of iron atoms in superconducting Fe1.01Se was studied by 57Fe nuclear inelastic scattering (NIS). The high energy resolution allows for a detailed observation of spectral properties. A sharpening of the optical phonon modes and shift of all spectral features towards higher energies by ~4% with decreasing temperature from 296 K to 10 K was found. However, no detectable change at the tetragonal - orthorhombic phase transition around 100 K was observed. Application of a pressure of 6.7 GPa, connected with an increase of the superconducting temperature from 8 K to 34 K, results in an increase of the optical phonon mode energies at 296 K by ~12%, and an even more pronounced increase for the lowest-lying transversal acoustic mode. Despite these strong pressure-induced modifications of the phonon-DOS we conclude that the pronounced increase of Tc in Fe1.01Se with pressure cannot be described in the framework of classical electron-phonon coupling. This result suggests the importance of spin fluctuations to the observed superconductivity

Atlas of common bean (Phaseolus vulgaris L.) production in Africa

The Bean atlas is a comprehensive map of the bean growing areas in Africa. The first version was first published in 1998 and in paper format. For the last four years, PABRA has been developing the second edition, which shows dramatic changes in bean production areas across Africa, where some have expanded and others have shifted. The new atlas will be digital and available online soon. The new edition contains information from bean producing areas in Eastern, Southern and Western Africa and represents a total of 22 countries. It overlays bean producing areas with information on: bean varieties grown in those regions; ongoing seed production and dissemination work; local, national and international bean markets; market routes; information on end users, farmers and bean consumption; bean constraints, both Biotic and abiotic; and more

Localized inhibition of protein phosphatase 1 by NUAK1 promotes spliceosome activity and reveals a MYC-sensitive feedback control of transcription.

Deregulated expression of MYC induces a dependence on the NUAK1 kinase, but the molecular mechanisms underlying this dependence have not been fully clarified. Here, we show that NUAK1 is a predominantly nuclear protein that associates with a network of nuclear protein phosphatase 1 (PP1) interactors and that PNUTS, a nuclear regulatory subunit of PP1, is phosphorylated by NUAK1. Both NUAK1 and PNUTS associate with the splicing machinery. Inhibition of NUAK1 abolishes chromatin association of PNUTS, reduces spliceosome activity, and suppresses nascent RNA synthesis. Activation of MYC does not bypass the requirement for NUAK1 for spliceosome activity but significantly attenuates transcription inhibition. Consequently, NUAK1 inhibition in MYC-transformed cells induces global accumulation of RNAPII both at the pause site and at the first exon-intron boundary but does not increase mRNA synthesis. We suggest that NUAK1 inhibition in the presence of deregulated MYC traps non-productive RNAPII because of the absence of correctly assembled spliceosomes