2,348 research outputs found

    Grothendieck-Messing deformation theory for varieties of K3-type

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    This is the final version. Available from Tunisian Mathematical Society / MSP via the DOI in this record.Let R be an artinian local ring with perfect residue class eld k. We associate to certain 2-displays over the small ring of Witt vectors ^W (R) a crystal on SpecR. Let X be a scheme of K3-type over SpecR. We de ne a perfect bilinear form on the second crystalline cohomology group X which generalizes the Beauville-Bogomolov form for hyper-K ahler varieties over C. We use this form to prove a lifting criterion of Grothendieck- Messing type for schemes of K3-type. The crystalline cohomology H2 crys(X= ^W (R)) is endowed with the structure of a 2-display such that the Beauville-Bogomolov form becomes a bilinear form in the sense of displays. If X is ordinary the in nitesimal deformations of X correspond bijectively to in nitesimal deformations of the 2-display of X with its Beauville-Bogomolov form. For ordinary K3-surfaces X=R we prove that the slope spectral sequence of the de Rham-Witt complex degenerates and that H2 crys(X=W(R)) has a canonical Hodge- Witt decomposition

    TARGET: toward a solution for the readout electronics of the Cherenkov Telescope Array

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    TARGET is an application specific integrated circuit (ASIC) designed to read out signals recorded by the photosensors in cameras of very-high-energy gamma-ray telescopes exploiting the imaging of Cherenkov radiation from atmospheric showers. TARGET capabilities include sampling at a high rate (typically 1 GSample/s), digitization, and triggering on the sum of four adjacent pixels. The small size, large number of channels read out per ASIC (16), low cost per channel, and deep buffer for trigger latency (~16 Ό\mus at 1 GSample/s) make TARGET ideally suited for the readout in systems with a large number of telescopes instrumented with compact photosensors like multi-anode or silicon photomultipliers combined with dual-mirror optics. The possible advantages of such systems are better sensitivity, a larger field of view, and improved angular resolution. The two latest generations of TARGET ASICs, TARGET 5 and TARGET 7, are soon to be used for the first time in two prototypes of small-sized and medium-sized dual-mirror telescopes proposed in the framework of the Cherenkov Telescope Array (CTA) project. In this contribution we report on the performance of the TARGET ASICs and discuss future developments.Comment: 8 pages, 3 figures. In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

    Radiation protection related x-ray spectrometry at PHELIX

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    Influence of the distal fall-off on the biological effective proton range

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    Flight simulation of the longitudinal motions of another aircraft

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    http://www.archive.org/details/flightsimulation00zinkU.S. Navy (U.S.N.) author.U.S. Marine Corps. (U.S.M.C.) author

    Circle talks as situated experiential learning: Context, identity, and knowledgeability in \u27learning from reflection\u27

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    This article presents research that used ethnographic and sociolinguistic methods to study ways participants learn through reflection when carried out as a “circle talk.” The data indicate that participants in the event (a) invoked different contextual frames that (b) implicated them in various identity positions, which (c) affected how they could express their knowledge. These features worked together to generate socially shared meanings that enabled participants to jointly achieve conceptualization—the ideational role “reflection” is presumed to play in the experiential learning process. The analysis supports the claim that participants generate new knowledge in reflection, but challenges individualistic and cognitive assumptions regarding how this occurs. The article builds on situated views of experiential learning by showing how knowledge can be understood as socially shared and how learning and identity formation are mutually entailing processes

    The analysis of injection molding defects caused by gate vestiges

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    Issues of product safety are the most serious problems of an injection molded product due to their risk to human health. Such a safety problem can be the needle-shaped vestige at the gate zone of injection molded products, called a gate vestige. Only observations of the formation of gate vestiges can be found in the literature, but the processing parameters influencing their dimensions, especially their height have not been studied yet. Our goal was to study the effect of various injection molding processing parameters and gate constructions on gate vestige formation

    Acute Beetroot Juice Ingestion Increases Nitric Oxide Bioavailability Without Changing Oral Microbial Composition in Healthy Young Women

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    Dietary nitrate supplementation can elicit beneficial health and exercise performance effects. Oral microbiota are critical for the metabolism of exogenously consumed nitrate; however, limited data are available on the influence of dietary nitrate ingestion on bacterial taxa and in women. PURPOSE: To investigate if acute dietary nitrate ingestion alters the oral microbiota in young healthy women compared to a nitrate-depleted placebo. METHODS: In a randomized double-blinded crossover design, fifteen recreationally active women (mean ± SD: age 20 ± 1 years; body mass 63 ± 10 kg; height 1.68 ± 0.1 m) participated in two conditions to ingest nitrate-rich beetroot juice (BR; 12 mmol of nitrate) and nitrate-depleted beetroot juice (PL, negligible nitrate), 2.5 hours prior to a resting blood draw and buccal swab sample. Plasma [nitrate] and [nitrite] were analyzed using gas phase chemiluminescence. Buccal swab samples were used for DNA extraction and isolation. DNA was amplified using polymerase chain reaction targeting the V3 - V4 region of the 16S rRNA gene. Following index PCR, amplicons were pooled and sequenced using the iSeq Illumina NGS sequencer. Reads were clustered into amplicon sequence variants and analyzed for alpha and beta diversity and relative abundance. RESULTS: BR increased plasma [nitrate] (PL: 52 ± 14 ”M vs. BR: 629 ± 132 ”M, P \u3c 0.001) and plasma [nitrite] (PL: 276 ± 286 nM vs. BR: 703 ± 391 nM, P \u3c 0.001). One sample had insufficient DNA and thus, a subset of samples was analyzed for oral microbial composition (n = 14). Alpha (i.e., species richness or evenness) and beta diversity was not different between PL and BR (P \u3e 0.05). The relative abundance of the phylum and genus were not influenced by BR (P \u3e 0.05). CONCLUSION: Acute nitrate ingestion did not improve or worsen the composition of global or lower taxonomic levels of bacteria in young recreationally active women. These data indicate that acute nitrate ingestion is an intervention to rapidly increase nitric oxide bioavailability in young recreationally active women, which is an effect that did not require changes to the oral microbial community. Further research is required to understand the impact of dosing regimen and population on oral bacterial taxa and the efficacy of nitrate on nitrate-induced effects
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