7,946 research outputs found

    Assessment of Risks and Uncertainties in Poultry Farming in Kwara State, Nigeria

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    This study was designed to assess the risks and uncertainties encountered by poultry farmers in Kwara State, Nigeria. Specifically, the study describes the socio-economic characteristics of the farmers, identify the risks and uncertainties encountered by the farmers, determines the level of severity of the risks and uncertainties, and identifies the coping strategies employed by the farmers. Primary data obtained from 99 registered poultry farmers selected through multistage sampling technique were used for the study. These were complemented with data from published and grey literature. Descriptive statistics and 3-point Likert scale were used to analyze the data. The study shows that poultry farming in the study area is practiced mainly by young, small-scale farmers, who are married, with high level of formal education but had little access to extension services. The major sources of risks encountered by the farmers were severe weather fluctuation, lack of veterinary services, disease outbreak, transportation problems, parasites and severe price fluctuation of birds. The study further revealed that the severe risks encountered by the farmers were disease outbreak, poor parent stock, accumulation of dung, severe weather fluctuation, lack of veterinary services and transportation problems. The study therefore calls for improved extension services, good transportation facilities, adequate veterinary services, market information by government and relevant stakeholders as well as formation of cooperative socities by the farmers

    Elastic constants of borocarbides. New approach to acoustic Measurement technique

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    A new version of the phase method of determining the sound velocity is proposed and implemented. It utilizes the ``Nonius'' measurement technique and can give acceptable accuracy (~1%) in samples of submillimeter size. Measurements of the sound velocity are made in single-crystal samples of the borocarbides RNi2B2C (R = Y,Lu,Ho). The elastic constants and the Debye temperature are calculated.Comment: 5 figures, 2 table

    Muon-Spin-Rotation Measurements of the Penetration Depth in the Infinite-Layer Electron-Doped Cuprate Superconductor Sr0.9La0.1CuO2

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    Muon spin rotation (mSR) measurements of the in-plane penetration depth lambda_ab have been performed in the electron-doped infinite layer high-Tc superconductor (HTS) Sr0.9La0.1CuO2. Absence of the magnetic rare-earth ions in this compound allowed to measure for the first time the absolute value of lambda_ab(0) in electron-doped HTS using mSR. We found lambda_ab(0)=116(2) nm. The zero-temperature depolarization rate sigma(0)?1/lambda_ab(0)^2=4.6(1) MHz is more than four times higher than expected from the Uemura line. Therefore this electron-doped HTS does not follow the Uemura relation found for hole-doped HTS.Comment: to be published in Physical Review Letter

    Stellar Populations and the Local Group Membership of the Dwarf Galaxy DDO 210

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    We present deep BVI CCD photometry of the stars in the dwarf galaxy DDO 210. The color-magnitude diagrams of DDO 210 show a well-defined red giant branch (RGB) and a blue plume. The tip of the RGB is found to be at I_TRGB = 20.95 +/- 0.10 mag. From this the distance to DDO 210 is estimated to be d = 950 +/- 50 kpc. The corresponding distance of DDO 210 to the center of the Local Group is 870 kpc, showing that it is a member of the Local Group. The mean metallicity of the red giant branch stars is estimated to be [Fe/H] = -1.9 +/- 0.1 dex. Integrated magnitudes of DDO 210 within the Holmberg radius (r_H=110 arcsec = 505 pc) are derived to be M_B=-10.6 +/- 0.1 mag and M_V=-10.9 +/- 0.1 mag. B and V surface brightness profiles of DDO 210 are approximately consistent with an exponential law with scale lengths r_s(B) = 161 pc and r_s(V) = 175 pc. The brightest blue and red stars in DDO 210 (BSG and RSG) are found to be among the faintest in the nearby galaxies with young stellar populations: _{BSG} = -3.41 +/- 0.11 mag and _{RSG} = -4.69 +/- 0.13 mag. An enhancement of the star formation rate in the recent past (several hundred Myrs) is observed in the central region of DDO 210. The opposite trend is observed in the outer region of the galaxy, suggesting a possible two-component structure of the kind disk/halo found in spiral galaxies. The real nature of this two-component structure must, however, be confirmed with more detailed observations.Comment: Latex file, 17 pages with 9 figures, uses emulateapj.sty To appear in the AJ (in August 1999

    Caste- and pesticide-specific effects of neonicotinoid pesticide exposure on gene expression in bumblebees

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    Social bees are important insect pollinators of wildflowers and agricultural crops, making their reported declines a global concern. A major factor implicated in these declines is the widespread use of neonicotinoid pesticides. Indeed, recent research has demonstrated that exposure to low doses of these neurotoxic pesticides impairs bee behaviours important for colony function and survival. However, our understanding of the molecular‐genetic pathways that lead to such effects is limited, as is our knowledge of how effects may differ between colony members. To understand what genes and pathways are affected by exposure of bumblebee workers and queens to neonicotinoid pesticides, we implemented a transcriptome‐wide gene expression study. We chronically exposed Bombus terrestriscolonies to either clothianidin or imidacloprid at field‐realistic concentrations while controlling for factors including colony social environment and worker age. We reveal that genes involved in important biological processes including mitochondrial function are differentially expressed in response to neonicotinoid exposure. Additionally, clothianidin exposure had stronger effects on gene expression amplitude and alternative splicing than imidacloprid. Finally, exposure affected workers more strongly than queens. Our work demonstrates how RNA‐Seq transcriptome profiling can provide detailed novel insight on the mechanisms mediating pesticide toxicity to a key insect pollinator

    Phenomenological Theory of Superconductivity and Magnetism in Ho1x_{1-x}Dyx_xNi2_2B2_2C

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    The coexistence of the superconductivity and magnetism in the Ho1x_{1-x}Dyx_xNi2_2B2_2C is studied by using Ginzburg-Landau theory. This alloy shows the coexistence and complex interplay of superconducting and magnetic order. We propose a phenomenological model which includes two magnetic and two superconducting order parameters accounting for the multi-band structure of this material. We describe phenomenologically the magnetic fluctuations and order and demonstrate that they lead to anomalous behavior of the upper critical field. The doping dependence of TcT_c in Ho1x_{1-x}Dyx_xNi2_2B2_2C showing a reentrance behavior are analyzed yielding a very good agreement with experimental data.Comment: 4 pages, 3 figures, REVTeX, submitted to PR

    Phase-contrast microscopy at high x-ray energy with a laboratory setup

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    We report on the design and realization of an x-ray imaging system for quantitative phase-contrast microscopy at high x-ray energy with laboratory-scale instrumentation. Phase and amplitudewere separated quantitatively at x-ray energies up to 80 keV with micrometric spatial resolution. The accuracy of the results was tested against numerical simulations, and the spatial resolution was experimentally quantified by measuring a Siemens star phase object. This simple setup should find broad application in those areas of x-ray imaging where high energy and spatial resolution are simultaneously required and in those difficult cases where the sample contains materials with similar x-ray absorption
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