965 research outputs found

    The Effects of Aerobic, Concurrent, and Resistance Exercise on Compensatory Eating Behaviors

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    A parallel multigrid solver for multi-patch Isogeometric Analysis

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    Isogeometric Analysis (IgA) is a framework for setting up spline-based discretizations of partial differential equations, which has been introduced around a decade ago and has gained much attention since then. If large spline degrees are considered, one obtains the approximation power of a high-order method, but the number of degrees of freedom behaves like for a low-order method. One important ingredient to use a discretization with large spline degree, is a robust and preferably parallelizable solver. While numerical evidence shows that multigrid solvers with standard smoothers (like Gauss Seidel) does not perform well if the spline degree is increased, the multigrid solvers proposed by the authors and their co-workers proved to behave optimal both in the grid size and the spline degree. In the present paper, the authors want to show that those solvers are parallelizable and that they scale well in a parallel environment.Comment: The first author would like to thank the Austrian Science Fund (FWF) for the financial support through the DK W1214-04, while the second author was supported by the FWF grant NFN S117-0

    Towards Precision LSST Weak-Lensing Measurement - I: Impacts of Atmospheric Turbulence and Optical Aberration

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    The weak-lensing science of the LSST project drives the need to carefully model and separate the instrumental artifacts from the intrinsic lensing signal. The dominant source of the systematics for all ground based telescopes is the spatial correlation of the PSF modulated by both atmospheric turbulence and optical aberrations. In this paper, we present a full FOV simulation of the LSST images by modeling both the atmosphere and the telescope optics with the most current data for the telescope specifications and the environment. To simulate the effects of atmospheric turbulence, we generated six-layer phase screens with the parameters estimated from the on-site measurements. For the optics, we combined the ray-tracing tool ZEMAX and our simulated focal plane data to introduce realistic aberrations and focal plane height fluctuations. Although this expected flatness deviation for LSST is small compared with that of other existing cameras, the fast f-ratio of the LSST optics makes this focal plane flatness variation and the resulting PSF discontinuities across the CCD boundaries significant challenges in our removal of the systematics. We resolve this complication by performing PCA CCD-by-CCD, and interpolating the basis functions using conventional polynomials. We demonstrate that this PSF correction scheme reduces the residual PSF ellipticity correlation below 10^-7 over the cosmologically interesting scale. From a null test using HST/UDF galaxy images without input shear, we verify that the amplitude of the galaxy ellipticity correlation function, after the PSF correction, is consistent with the shot noise set by the finite number of objects. Therefore, we conclude that the current optical design and specification for the accuracy in the focal plane assembly are sufficient to enable the control of the PSF systematics required for weak-lensing science with the LSST.Comment: Accepted to PASP. High-resolution version is available at http://dls.physics.ucdavis.edu/~mkjee/LSST_weak_lensing_simulation.pd

    Conversion of Aniline to Azobenzene at Functionalized Carbon Nanotubes: A Possible Case of a Nanodimensional Reaction

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    Aniline is oxidized to nitrosobenzene as the initial product, which undergoes further oxidation to nitrobenzene. The nitrosobenzene formation is catalyzed by functionalized multiwalled carbon nanotubes (CNT) followed by a coupling reaction between nitrosobenzene and aniline to produce azobenzene. This coupling requires close proximity of the reactants. It proceeds rapidly resulting in the UV-VIS absorption spectrum showing maxima at 327 nm and 425 nm. The nitrosobenzene yield in the presence of CNTs is controlled by the amount present in the medium. As the reaction is not catalyzed by unfunctionalized CNTs or graphitic particles, the uniqueness of the functionalized multiwalled CNTs in this catalysis suggests a nanodimensional reaction pathway

    Comparison of the collagen haemostat Sangustop(R) versus a carrier-bound fibrin sealant during liver resection; ESSCALIVER-study

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    Background: Haemostasis in liver surgery remains a challenge despite improved resection techniques. Oozing from blood vessels too small to be ligated necessitate a treatment with haemostats in order to prevent complications attributed to bleeding. There is good evidence from randomised trials for the efficacy of fibrin sealants, on their own or in combination with a carrier material. A new haemostatic device is Sangustop(R). It is a collagen based material without any coagulation factors. Pre-clinical data for Sangustop(R) showed superior haemostatic effect. This present study aims to show that in the clinical situation Sangustop(R) is not inferior to a carrier-bound fibrin sealant (Tachosil(R)) as a haemostatic treatment in hepatic resection. Methods: This is a multi-centre, patient-blinded, intra-operatively randomised controlled trial. A total of 126 patients planned for an elective liver resection will be enrolled in eight surgical centres. The primary objective of this study is to show the non-inferiority of Sangustop(R) versus a carrier-bound fibrin sealant (Tachosil(R)) in achieving haemostasis after hepatic resection. The surgical intervention is standardised with regard to devices and techniques used for resection and primary haemostasis. Patients will be followed-up for three months for complications and adverse events. Discussion: This randomised controlled trial (ESSCALIVER) aims to compare the new collagen haemostat Sangustop(R) with a carrier-bound fibrin sealant which can be seen as a "gold standard" in hepatic and other visceral organ surgery. If non-inferiority is shown other criteria than the haemostatic efficacy (e.g. costs, adverse events rate) may be considered for the choice of the most appropriate treatment. Trial Registration: NCT0091861

    Spatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems

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    Polar deserts are characterized by severe spatial-temporal limitations of liquid water. In soil active layers of the Antarctic Dry Valleys, liquid water is infrequently available over most of the arid terrestrial landscape. However, soils on the margins of glacial melt-water streams and lakes are visibly wet during the brief Austral summer when temperatures permit the existence of liquid water. We examined the role of these hydrologic margins as preferential zones for the transformation and transport of nutrient elements and solutes in an environment where geochemical weathering and biological activity is strictly limited by the dearth of liquid water. We report on hydropedological investigations of aquatic-terrestrial transition zones adjacent to 11 stream and lake systems in the Antarctic Dry Valleys. Our results show that wetted zones extended 1–11 m from the edges of lotic and lentic systems. While capillary demand and surface evaporation drive a one-way flux of water through these zones, the scale of these transition zones is determined by the topography and physical characteristics of the surrounding soils. Nutrient concentrations and fluxes appear to be influenced by both the hydrology and microbial-mediated biogeochemical processes. Salt concentrations are enriched near the distal boundary of the wetted fronts due to evapo-concentration of pore water in lake margin soils, while organic matter, ammonium and phosphate concentrations are highest in stream channel sediments where potential for biological activity is greatest. Thus, in the Antarctic Dry Valleys, intermittently wet soils on the margins of streams and lakes are important zones of both geochemical cycling and biological activity
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