6,184 research outputs found

    Orientational Ordering in Athermally Sheared, Aspherical, Frictionless Particles

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    We numerically simulate the uniform athermal shearing of bidisperse, frictionless, two dimensional spherocylinders and three dimensional prolate ellipsoids. We focus on the orientational ordering of particles as an asphericity parameter α0\alpha\to 0 and particles approach spherical. We find that the nematic order parameter S2S_2 is non-monotonic in the packing fraction ϕ\phi, and that as α0\alpha\to 0 S2S_{2} stays finite at jamming and above. The approach to spherical particles thus appears to be singular. We also find that sheared particles continue to rotate above jamming, and that particle contacts preferentially lie along the narrowest width of the particles, even as α0\alpha\to 0.Comment: updated to published version with greatly expanded supplemental material: 5 pages, 5 figures, plus supplemental material of 7 pages, 11 figure

    Expression of plasma prekallikrein mRNA in human nonhepatic tissues and cell lineages suggests special local functions of the enzyme

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    At present it is generally accepted that plasma prekallikrein (PPK) is synthesized in the liver and secreted into the bloodstream. Surprisingly, it has recently been shown that PPK mRNA is present also in RNA from the kidney, adrenal gland and placenta. In spite of its novelty and possible important physiological implications this finding has been neglected. Here we report that PPK mRNA is expressed also in the human brain, heart, lung, trachea, endothelial cells and leukocytes as well as in a variety of fibroblast and epithelial cell lines. Expression of PPK mRNA in fibroblasts, endothelial cells and leukocytes suggests that PPK mRNA detected in RNA preparations from whole tissue may originate solely from these ubiquitously occurring cells. However, PPK mRNA expression in various epithelial cell lines demonstrates that tissue-specific cells also transcribe the PPK gene. The presence of PPK mRNA in nonhepatic tissues and cells indicates that they have the capacity to synthesize the protein. The physiological role of PPK synthesized in extrahepatic tissue is unknown. It may participate in local actions within tissues as well as contributing to the PPK pool in blood plasma. Cultured cells will provide a valuable model for exploring the physiological significance of extrahepatic PPK expression

    Anthelmintic resistance of gastrointestinal cattle nematodes

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    Anthelmintic resistance of parasites in small ruminants, cattle and horses is increasing worldwide as a consequence of the over usage of the currently available products. In Belgium, Cooperia oncophora is the most common cattle nematode in which resistance, especially against macrocyclic lactones, occurs. Once resistance has been diagnosed, a change to another drug with a different mode of action is advised. However, effective anthelmintics will be hardly available in the near future. Therefore, it is important that farmers and veterinarians find a balance between achieving good parasite control and the sustainability of their control strategies. In this way, anthelmintic resistance may be delayed, and the effectiveness of anthelmintic drugs may be prolonged. This requires sensitive detection tools. With a sensitive detection technique, anthelmintic resistance can be diagnosed in a very early stage. Hence, the spread of resistance alleles in the parasite population may be prevented. In this review, different diagnostic assays for the detection of anthelmintic resistance are discussed, an overview is given of the current status of anthelmintic resistance in Belgian cattle, and measures are suggested to avoid or delay the development of anthelmintic resistance

    Inverse scattering and solitons in An1A_{n-1} affine Toda field theories II

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    New single soliton solutions to the affine Toda field theories are constructed, exhibiting previously unobserved topological charges. This goes some of the way in filling the weights of the fundamental representations, but nevertheless holes in the representations remain. We use the group doublecross product form of the inverse scattering method, and restrict ourselves to the rank one solutions.Comment: 19 pages, latex, 12 fig
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