Multi-Disciplinary North-South Collaboration in Participatory Action Research on Food Value Chains: a German-Tanzanian Case Study on Perceptions,Experiences and Challenges

Systemic Practice and Action Research - Upgrading local food value chains is a promising approach to invigorating African food systems. This endeavour warrants multi-disciplinary North-South...     

Arsenic removal from water by iron-sulphide minerals

In bench-scaled experiments, iron-sulphide minerals, pyrite and pyrrhotite are used as adsorbents for arsenic removal from As-spiked water of As⁵⁺ and As³⁺ species. The adsorption rate, efficiency, As-adsorption stability and the associated pH conditions have been examined. Observations indicate that these iron-sulphide minerals are very efficient to adsorb arsenic from water for both As⁵⁺ and As³⁺ species. Similar to other studies, As³⁺-adsorption shows a slower rate than As³⁺. The stability of the adsorbed arsenic seems closety retated to the pH values of the solution. A lower pH levet commonly less than 4.0 is required to protect the adsorbed arsenic from serious oxidation and backward retease. Fining of the mineral powders and shaking of the solution during adsorption enhance the adsorption efficiency and adsorption rate. For practical use of the method presented in this study, the waste produced should be managed with great care to keep it from redistribution over water system. A further study of the protection for the waste from oxidation on real water systems will greatly enhance the application of the strong ability of arsenic adsorption by these minerals, which is observed from this study.     

Molecular verification of the integration of Tripsacum dactyloides DNA into wheat genome through wide hybridization

RAPD and RFLP analyses of double haploid lines which derived from hybridization between hexaploid wheat (Triticum aestivum L.2n=42) and eastern gamagrass (Tripsacum dactyloides L.2n=4x=72) are reported.Two of the 340 Operon primers have been screened,which stably amplified Tripsacum dactyloides (male parent) specific bands in the double haploid lines.These results confirm the fact that Tripsacum dactyloides DNA has been integrated into wheat genome by sexual hybridization at molecular level.This idea has been further testified by RFLP analysis.Application and potentials of transferring Tripsacum dactyloides DNA into wheat genome by sexual hybridization in wheat breeding are discussed.     

Merlin--rapid analysis of dense genetic maps using sparse gene flow trees.

Efforts to find disease genes using high-density single-nucleotide polymorphism (SNP) maps will produce data sets that exceed the limitations of current computational tools. Here we describe a new, efficient method for the analysis of dense genetic maps in pedigree data that provides extremely fast solutions to common problems such as allele-sharing analyses and haplotyping. We show that sparse binary trees represent patterns of gene flow in general pedigrees in a parsimonious manner, and derive a family of related algorithms for pedigree traversal. With these trees, exact likelihood calculations can be carried out efficiently for single markers or for multiple linked markers. Using an approximate multipoint calculation that ignores the unlikely possibility of a large number of recombinants further improves speed and provides accurate solutions in dense maps with thousands of markers. Our multipoint engine for rapid likelihood inference (Merlin) is a computer program that uses sparse inheritance trees for pedigree analysis; it performs rapid haplotyping, genotype error detection and affected pair linkage analyses and can handle more markers than other pedigree analysis packages.     

Parameters for reliable results in genetic association studies in common disease.

It is increasingly apparent that the identification of true genetic associations in common multifactorial disease will require studies comprising thousands rather than the hundreds of individuals employed to date. Using 2,873 families, we were unable to confirm a recently published association of the interleukin 12B gene in 422 type I diabetic families. These results emphasize the need for large datasets, small P values and independent replication if results are to be reliable.     

Modelling the advertising-sales relationship through use of multiple time series techniques

When time series data are available for both advertising and sales, it may be worth while to model the two series jointly. Such an analysis may contribute to our understanding of the dynamic relationships among the series and may improve the accuracy of forecasts. Multiple time series techniques are applied to the well-known Lydia Pinkham data to illustrate their use in modelling the advertising-sales relationship. In analysing the Lydia Pinkham data the need for a joint model is established and a bivariate model is identified, estimated and checked. Its forecasting properties are discussed and compared to other time series approaches.     

Clonal analysis reveals a common progenitor for thymic cortical and medullary epithelium

The thymus provides an essential environment for the development of T cells from haemopoietic progenitors. This environment is separated into cortical and medullary regions, each containing functionally distinct epithelial populations that are important at successive stages of T-cell development and selection. However, the developmental origin and lineage relationships between cortical and medullary epithelial cell types remain controversial. Here we describe a clonal assay to investigate the developmental potential of single, individually selected, thymic epithelial progenitors (marked with enhanced yellow fluorescent protein) developing within the normal architecture of the thymus. Using this approach, we show that cortical and medullary epithelial cells share a common origin in bipotent precursors, providing definitive evidence that they have a single rather than dual germ layer origin during embryogenesis. Our findings resolve a long-standing issue in thymus development, and are important in relation to the development of cell-based strategies for thymus disorders and the possibility of restoring function of the atrophied adult thymus.