SPATIAL ANALYSIS OF SOIL FERTILITY MANAGEMENT USING INTEGRATED HOUSEHOLD AND GIS DATA FROM SMALLHOLDER KENYAN FARMS

Although soil fertility is recognized as a primary constraint to agricultural production in developing countries, use of fertilizer in Sub-Saharan Africa is declining. Smallholder farmers still rely heavily on livestock manure for soil fertility management. To explore the determinants of soil fertility management practices, including both the use of cattle manure and inorganic fertilizer, data are used from a sample of 3,330 geo-referenced farm households across Central and Western Kenya. A bivariate probit model is applied to jointly examine the use of the two technologies. Particular attention is given to measures of location related to market access and agroclimate, which in the adoption literature have typically been addressed using crude proxies. To avoid such proxies, GIS-derived variables are integrated into the household decision model. Their use also allows the spatial prediction of uptake based on parameter estimates. The results show clearly the derived-demand nature of soil fertility services, based on markets for farm outputs. They also illustrate that supply of manure for soil fertility amendments is conditioned by demand for livestock products, especially milk. The integration of GIS-derived variables is shown to better estimate the effects of location than the usual measures employed, and offers scope to wider use in technology adoption research.spatial analysis, soil fertility, market access, technology adoption., Farm Management, Land Economics/Use, Q12, Q16,

Mechanisms of linezolid resistance among coagulase-negative staphylococci determined by whole-genome sequencing.

UnlabelledLinezolid resistance is uncommon among staphylococci, but approximately 2% of clinical isolates of coagulase-negative staphylococci (CoNS) may exhibit resistance to linezolid (MIC, ≥8 µg/ml). We performed whole-genome sequencing (WGS) to characterize the resistance mechanisms and genetic backgrounds of 28 linezolid-resistant CoNS (21 Staphylococcus epidermidis isolates and 7 Staphylococcus haemolyticus isolates) obtained from blood cultures at a large teaching health system in California between 2007 and 2012. The following well-characterized mutations associated with linezolid resistance were identified in the 23S rRNA: G2576U, G2447U, and U2504A, along with the mutation C2534U. Mutations in the L3 and L4 riboproteins, at sites previously associated with linezolid resistance, were also identified in 20 isolates. The majority of isolates harbored more than one mutation in the 23S rRNA and L3 and L4 genes. In addition, the cfr methylase gene was found in almost half (48%) of S. epidermidis isolates. cfr had been only rarely identified in staphylococci in the United States prior to this study. Isolates of the same sequence type were identified with unique mutations associated with linezolid resistance, suggesting independent acquisition of linezolid resistance in each isolate.ImportanceLinezolid is one of a limited number of antimicrobials available to treat drug-resistant Gram-positive bacteria, but resistance has begun to emerge. We evaluated the genomes of 28 linezolid-resistant staphylococci isolated from patients. Multiple mutations in the rRNA and associated proteins previously associated with linezolid resistance were found in the isolates investigated, underscoring the multifocal nature of resistance to linezolid in Staphylococcus. Importantly, almost half the S. epidermidis isolates studied harbored a plasmid-borne cfr RNA methylase gene, suggesting that the incidence of cfr may be higher in the United States than previously documented. This finding has important implications for infection control practices in the United States. Further, cfr is commonly detected in bacteria isolated from livestock, where the use of phenicols, lincosamides, and pleuromutilins in veterinary medicine may provide selective pressure and lead to maintenance of this gene in animal bacteria

Research that matters: Outcome mapping for linking knowledge to poverty-reduction actions

An 'Outcome Mapping' approach was applied retrospectively to five diverse, highly collaborative research projects aimed at poverty reduction. Designed to help plan for, clarify, and document intended and actual changes in behaviour, actions, and relationships of groups and organisations that directly influence a project's intended beneficiaries, Outcome Mapping enabled us to identify and describe the strategies and actions that played important roles in the innovations achieved. Successful strategies observed included the use of champions, jointly producing high-profile outputs that enhanced the status of local partners, multiple communication strategies, targeting ongoing policy processes, and strong emphases on and investment in capacity building

Radio Jet-Ambient Medium Interactions on Parsec Scales in the Blazar 1055+018

As part of our study of the magnetic fields of AGN we have recently observed a large sample of blazars with the Very Long Baseline Array. Here we report the discovery of a striking two-component jet in the source 1055+018, consisting of an inner spine with a transverse magnetic field, and a fragmentary but distinct boundary layer with a longitudinal magnetic field. The polarization distribution in the spine strongly supports shocked-jet models while that in the boundary layer suggests interaction with the surrounding medium. This behavior suggests a new way to understand the differing polarization properties of strong- and weak-lined blazars.Comment: LaTex; 10 pages; 6 figures; reference fix; to appear in ApJL, 518, 1999 June 2

Factors influencing farmer-to-farmer extension of forage legume technology

Forage legumes have been introduced to farmers in Central Kenya between 1980 and 2002 through various Institutional and Projects’ efforts. The adoption rate of these forages among farmers has been found to be rather low, with the NDDP reporting only 1.9 % of farms surveyed and an ICRAF report indicating that the technology was only reaching 1 % of smallholder farms. An evaluation of adoption of Calliandra and Desmodium was conducted to identify farm characteristics affecting the likelihood of sharing of Desmodium and Calliandra technologies as well as to characterise the spread or diffusion of the technology from the original contact groups and the effect of distance from those groups. Three groups of farmers were approached. A first generation who received planting material from the distributors, a second generation who received planting materials from the former, and a randomly selected group of farmers at various distances from the first contacts. Informal discussions were held with the farmers and formal questionnaires filled. Out of the 133 first generation farmers contacted 64.7% still had Desmodium and 89.5% still had Calliandra. More farms in the contact sub-locations had the plants than the sub-locations further away. The small sample size of those with the forages could not allow effect of distance to be worked out. Tobit estimates of effects of farmer attributes influencing sharing of planting materials shows that the status of the household head in the community positively affected the likelihood of giving out planting material. The technology has a rather slow spread as indicated by percentages of farms with the forages. For better adoption and spread proponents of the technology should have the technology introduced to farmers who have substantial positions in farmer groups or have been bestowed community responsibility

DiFX2: A more flexible, efficient, robust and powerful software correlator

Software correlation, where a correlation algorithm written in a high-level language such as C++ is run on commodity computer hardware, has become increasingly attractive for small to medium sized and/or bandwidth constrained radio interferometers. In particular, many long baseline arrays (which typically have fewer than 20 elements and are restricted in observing bandwidth by costly recording hardware and media) have utilized software correlators for rapid, cost-effective correlator upgrades to allow compatibility with new, wider bandwidth recording systems and improve correlator flexibility. The DiFX correlator, made publicly available in 2007, has been a popular choice in such upgrades and is now used for production correlation by a number of observatories and research groups worldwide. Here we describe the evolution in the capabilities of the DiFX correlator over the past three years, including a number of new capabilities, substantial performance improvements, and a large amount of supporting infrastructure to ease use of the code. New capabilities include the ability to correlate a large number of phase centers in a single correlation pass, the extraction of phase calibration tones, correlation of disparate but overlapping sub-bands, the production of rapidly sampled filterbank and kurtosis data at minimal cost, and many more. The latest version of the code is at least 15% faster than the original, and in certain situations many times this value. Finally, we also present detailed test results validating the correctness of the new code.Comment: 28 pages, 9 figures, accepted for publication in PAS

Fodder legumes technology and farmer to farmer extension: a case of Desmodium and Calliandra in central Kenya

Adoption studies on fodders legume technologies have shown that spread of the technology is significantly enhanced by informal methods of dissemination especially farmer-to-farmer extension. It is not known which type of farmers are involved in this dissemination. The objective of this study was to identify farm and farmer characteristics that influence farmer-to farmer extension hence identify the type of farmers that can disseminate fodder legume technologies. A random sample of 130 farmers who had been given calliandra in central Kenya responded to a structured questionnaire. Information collected included farm and farmer characteristics and the number of farmers the original farmer had given Calliandra outside the original group. A tobit model was used to analyze the data to get the magnitude of the effects of factors affecting the probability and the intensity of giving out the fodder. Results showed that farmers with positions in farmer groups** , community responsibility**, larger amounts of desmodium on the their farms** , more years of the fodder on their farms***; low access to markets* and off farm income* , were positively involved in spread of the fodder legume. It was recommended that this type of farmers be targeted with support to increase spread of the technology