608 research outputs found

    Regulatory SPS instruments in meat trade

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    Policy makers have to choose between different potentially risk-reducing instruments regulating agri-food trade. Analysing the meat sector, the paper aims at identifying least trade distorting regulations for different policy goals relevant to the SPS agreement. For this purpose, a non-linear gravity model is estimated by Poisson pseudo-maximum likelihood and applied to a panel data set at HS 4-digit level. Regulations are distinguished by a frequency approach allowing to identify the least trade distorting regulation for each policy objective. The results suggest significant differences of trade impacts between types of sanitary regulations.agri-food trade, gravity model, Poisson regression, Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety, International Relations/Trade, C23, F14, Q17,

    First experiences with the H-maser EFOS 1

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    The results are given on the performance measurements, on the dependence on external temperature, and on external magnetic field of a hydrogen maser. It is compared with another hydrogen maser. Details of the transportation and installation of the maser are given. The hydrogen maser frequency is compared with cesium oscillators to derive long-term behavior

    Study made of corrosion resistance of stainless steel and nickel alloys in nuclear reactor superheaters

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    Experiments performed under conditions found in nuclear reactor superheaters determine the corrosion rate of stainless steel and nickel alloys used in them. Electropolishing was the primary surface treatment before the corrosion test. Corrosion is determined by weight loss of specimens after defilming

    WLRS

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    This status-report of the Wettzell Laser Ranging System (WLRS) gives an overview of its set up and the developments necessary to make the system operational

    Insulin-like growth factor receptor 1b is required for zebrafish primordial germ cell migration and survival

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    AbstractInsulin-like growth factor (IGF) signaling is a critical regulator of somatic growth during fetal and adult development, primarily through its stimulatory effects on cell proliferation and survival. IGF signaling is also required for development of the reproductive system, although its precise role in this regard remains unclear. We have hypothesized that IGF signaling is required for embryonic germline development, which requires the specification and proliferation of primordial germ cells (PGCs) in an extragonadal location, followed by directed migration to the genital ridges. We tested this hypothesis using loss-of-function studies in the zebrafish embryo, which possesses two functional copies of the Type-1 IGF receptor gene (igf1ra, igf1rb). Knockdown of IGF1Rb by morpholino oligonucleotides (MO) results in mismigration and elimination of primordial germ cells (PGCs), resulting in fewer PGCs colonizing the genital ridges. In contrast, knockdown of IGF1Ra has no effect on PGC migration or number despite inducing widespread somatic cell apoptosis. Ablation of both receptors, using combined MO injections or overexpression of a dominant-negative IGF1R, yields embryos with a PGC-deficient phenotype similar to IGF1Rb knockdown. TUNEL analyses revealed that mismigrated PGCs in IGF1Rb-deficient embryos are eliminated by apoptosis; overexpression of an antiapoptotic gene (Bcl2l) rescues ectopic PGCs from apoptosis but fails to rescue migration defects. Lastly, we show that suppression of IGF signaling leads to quantitative changes in the expression of genes encoding CXCL-family chemokine ligands and receptors involved in PGC migration. Collectively, these data suggest a novel role for IGF signaling in early germline development, potentially via cross-talk with chemokine signaling pathways

    Doping and Irradiation Controlled Vortex Pinning Behavior in BaFe2(As1-xPx)2 Single Crystals

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    We report on the systematic evolution of vortex pinning behavior in isovalent doped single crystals of BaFe2(As1-xPx)2. Proceeding from optimal doped to ovedoped samples, we find a clear transfor- mation of the magnetization hysteresis from a fishtail behavior to a distinct peak effect followed by a reversible magnetization and Bean Livingston surface barriers. Strong point pinning dominates the vortex behavior at low fields whereas weak collective pinning determines the behavior at higher fields. In addition to doping effects, we show that particle irradiation by energetic protons can tune vortex pinning in these materials.Comment: 4 pages, 4 figures,significant change of eraly version, accepted by PRB rapid communication
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