2,354 research outputs found
Grothendieck-Messing deformation theory for varieties of K3-type
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
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 s 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
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Nanoporous Morphogenesis in Amorphous Carbon Layers: Experiments and Modeling on Energetic Ion Induced SelfâOrganization
Nanoporous amorphous carbon constitutes a highly relevant material for a multitude of applications ranging from energy to environmental and biomedical systems. In the present work, it is demonstrated experimentally how energetic ions can be utilized to tailor porosity of thin sputter deposited amorphous carbon films. The physical mechanisms underlying self-organized nanoporous morphogenesis are unraveled by employing extensive molecular dynamics and phase field models across different length scales. It is demonstrated that pore formation is a defect induced phenomenon, in which vacancies cluster in a spinodal decomposition type of self-organization process, while interstitials are absorbed by the amorphous matrix, leading to additional volume increase and radiation induced viscous flow. The proposed modeling framework is capable to reproduce and predict the experimental observations from first principles and thus opens the venue for computer assisted design of nanoporous frameworks
Flight simulation of the longitudinal motions of another aircraft
http://www.archive.org/details/flightsimulation00zinkU.S. Navy (U.S.N.) author.U.S. Marine Corps. (U.S.M.C.) author
The analysis of injection molding defects caused by gate vestiges
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
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
Circle talks as situated experiential learning: Context, identity, and knowledgeability in \u27learning from reflection\u27
This article presents research that used ethnographic and sociolinguistic methods to study ways participants learn through reflection when carried out as a âcircle talk.â 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 conceptualizationâthe ideational role âreflectionâ 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
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