6,894 research outputs found

    Counting joints in vector spaces over arbitrary fields

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    We give a proof of the "folklore" theorem that the Kaplan--Sharir--Shustin/Quilodr\'an result on counting joints associated to a family of lines holds in vector spaces over arbitrary fields, not just the reals. We also discuss a distributional estimate on the multiplicities of the joints in the case that the family of lines is sufficiently generic.Comment: Not intended for publication. References added and other minor edits in this versio

    Are lines of arrested growth in bone indicative of seasonal metabolic suppression in bears?

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    2016 Spring.Includes bibliographical references.Large hibernators such as bears have seasonal metabolic suppression, hibernation (Tøien et al. 2012). During hibernation bear's activity is very low; to the point most other animals would exhibit disuse bone resorption. However bears do not exhibit disuse bone resorption during this time (McGeeLawrence et al. 2008). Are lines of arrested growth (LAGs) in bone indicative of seasonal metabolic suppression in bears? Through the use of toluidine blue stain light microscopy slides and backscattered scanning electron microscopy images (SEM), LAGs were counted and correlated with age. LAGs have a strong correlation with age. This is indicative of LAGs formation once per year, during set hibernation cycles. LAGs are metabolic markers, in bears with set hibernation cycles. These metabolic markers could be used to identify the specific time in which there is metabolic suppression, in bears. This identification could be used in the future to track blood serum and other chemical markers in an attempt to understand bear's natural resistance to disuse bone resorption. Bears ability to not exhibit disuse bone resorption could be biomimetically studied, in an attempt to adapt this protection to humans. Since humans experience disuse osteoporosis (extended bed rest and spaceflight) and osteoporosis (older population specifically women)

    The mammalian cone visual cycle promotes rapid M/L-cone pigment regeneration independently of the interphotoreceptor retinoid-binding protein

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    Rapid regeneration of the visual pigment following its photoactivation is critical for the function of cone photoreceptors throughout the day. Though the reactions of the visual cycle in the retinal pigment epithelium (RPE) that recycle chromophore for rod pigment regeneration are well characterized, the corresponding mechanisms that enable rapid regeneration of cone pigment are poorly understood. A key remaining question is the relative contribution of the recently discovered cone-specific retina visual cycle and the classic RPE-dependent visual cycle to mammalian cone pigment regeneration. In addition, it is not clear what role, if any, the abundant interphotoreceptor matrix protein, IRBP, presumed to facilitate the traffic of chromophore, plays in accelerating mammalian cone pigment regeneration. To address these issues we used transretinal recordings to evaluate M/L-cone pigment regeneration in isolated retinas and eyecups from control and IRBP-deficient mice. Remarkably, the mouse retina promoted M/L-cone dark adaptation 8-fold faster than the RPE. However, complete cone recovery required both visual cycles. We conclude that the retina visual cycle is critical for the initial rapid regeneration of mouse M/L-cone pigment during dark adaptation whereas the slower RPE visual cycle is required to complete the process. While the deletion of IRBP reduced the amplitude and slowed the kinetics of mouse M/L-cone photoresponses, cone adaptation in bright steady light and the kinetics of cone dark adaptation were not affected in isolated retina or in intact eyecup. Thus, IRBP does not accelerate cone pigment regeneration and is not critical for the function of mouse M/L-cones in bright light

    1st Annual Workshop Proceedings of the Collaborative Project "Fast / Instant Release of Safety Relevant Radionuclides from Spent Nuclear Fuel" (7th EC FP CP FIRST-Nuclides), Budapest 09 - 11 October 2012 (KIT Scientific Reports ; 7639)

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    These proceedings document the scientific-technical progress of the 1st year of the European project FIRST-Nuclides. The project is established with the overall objective to provide for improved understanding of the fast / instantly released radionuclides from high burn-up spent nuclear fuel (HBU-SNF) under conditions of geological disposal. 14 HBU-SNF samples, discharged from various European and US American light water reactors, are characterized and prepared for experimental investigations
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