17,781 research outputs found

    Space station stabilization and control study Final engineering report

    Get PDF
    Simulation of stabilization and control for spinning, manned space station to provide artificial gravity station environmen

    Temperature-dependent errors in nuclear lattice simulations

    Get PDF
    We study the temperature dependence of discretization errors in nuclear lattice simulations. We find that for systems with strong attractive interactions the predominant error arises from the breaking of Galilean invariance. We propose a local "well-tempered" lattice action which eliminates much of this error. The well-tempered action can be readily implemented in lattice simulations for nuclear systems as well as cold atomic Fermi systems.Comment: 33 pages, 17 figure

    Mn L2,3_{2,3} edge resonant x-ray scattering in manganites: Influence of the magnetic state

    Full text link
    We present an analysis of the dependence of the resonant orbital order and magnetic scattering spectra on the spin configuration. We consider an arbitrary spin direction with respect to the local crystal field axis, thus lowering significantly the local symmetry. To evaluate the atomic scattering in this case, we generalized the Hannon-Trammel formula and implemented it inside the framework of atomic multiplet calculations in a crystal field. For an illustration, we calculate the magnetic and orbital scattering in the CE phase of \lsmo in the cases when the spins are aligned with the crystal lattice vector a{\vec a} (or equivalently b{\vec b}) and when they are rotated in the abab-plane by 45^{\circ} with respect to this axis. Magnetic spectra differ for the two cases. For the orbital scattering, we show that for the former configuration there is a non negligible σσ\sigma \to \sigma' (ππ\pi \to \pi') scattering component, which vanishes in the 45^\circ case, while the σπ\sigma \to \pi' (πσ\pi \to \sigma') components are similar in the two cases. From the consideration of two 90^\circ spin canted structures, we conclude there is a significant dependence of the orbital scattering spectra on the spin arrangement. Recent experiments detected a sudden decrease of the orbital scattering intensity upon increasing the temperature above the N\' eel temperature in \lsmo. We discuss this behavior considering the effect of different types of misorientations of the spins on the orbital scattering spectrum.Comment: 8 figures. In the revised version, we added a note, a reference, and a few minor changes in Figure 1 and the text. Accepted in Physical Review

    Extremely low long‐term erosion rates around the Gamburtsev Mountains in interior East Antarctica

    Get PDF
    The high elevation and rugged relief (>3 km) of the Gamburtsev Subglacial Mountains (GSM) have long been considered enigmatic. Orogenesis normally occurs near plate boundaries, not cratonic interiors, and large‐scale tectonic activity last occurred in East Antarctica during the Pan‐African (480–600 Ma). We sampled detrital apatite from Eocene sands in Prydz Bay at the terminus of the Lambert Graben, which drained a large pre‐glacial basin including the northern Gamburtsev Mountains. Apatite fission‐track and (U‐Th)/He cooling ages constrain bedrock erosion rates throughout the catchment. We double‐dated apatites to resolve individual cooling histories. Erosion was very slow, averaging 0.01–0.02 km/Myr for >250 Myr, supporting the preservation of high elevation in interior East Antarctica since at least the cessation of Permian rifting. Long‐term topographic preservation lends credence to postulated high‐elevation mountain ice caps in East Antarctica since at least the Cretaceous and to the idea that cold‐based glaciation can preserve tectonically inactive topography

    Prevalence of HCV NS3 pre-treatment resistance associated amino acid variants within a Scottish cohort

    Get PDF
    Background: Protease inhibitors (PI) including boceprevir, telaprevir and simeprevir have revolutionised HCV genotype 1 treatment since their introduction. A number of pre-treatment resistance associated amino acid variants (RAVs) and polymorphisms have been associated with reduced response to treatment. Objectives: We measured the prevalence of RAVs/polymorphisms in a PI treatment-naïve HCV genotype 1 Scottish cohort using Sanger sequencing. Study design: Chronically infected, treatment-naïve, HCV genotype 1 patients (n = 146) attending NHS Greater Glasgow and Clyde clinics were investigated for RAVs/polymorphisms to the PIs boceprevir, telaprevir and simeprevir. The NS3/4A region was amplified by nested polymerase chain reaction. The 1.4 kb amplified product was sequenced using an ABI 3710XL DNA sequencer. Sequence analysis was performed using web-based ReCall (beta 2.10). Amino acid positions 36, 41, 43, 54, 55, 80, 109, 122, 155, 156, 168 and 170 were analysed for RAVs/polymorphisms. Results: Overall, 23.29% (34/146) of patients had an RAV or polymorphism detected. Overall, 13.69% (20/146) of patients had HCV virus that contained the Q8 K polymorphism. Other RAVs detected were: V36 M 0.70% (1/146), V36L 0.70% (1/146), T54S 6.85% (10/146), V55A 3.42% (5/146) and V/I170A 0.68% (1/146). Four patients had dual combinations of mutations (T54S + V36L; T54S + V55A and 2 patients with T54S + Q80K). Conclusions: Q80K was the most prevalent baseline polymorphism detected in the Scottish cohort. Simeprevir treatment is not recommended in patients infected with the Q80K genotype 1a variant. This highlights the need for baseline sequencing prior to administration of this drug in this population

    The 2004 Sumatra tsunami as recorded on the Atlantic coast of South America

    Get PDF
    The 2004 Sumatra tsunami propagated throughout the World Ocean and was clearly recorded by tide gauges on the Atlantic coast of South America. A total of 17 tsunami records were found and subsequently examined for this region. Tsunami wave heights and arrival times are generally consistent with numerical modeling results. Maximum wave heights of more than 1.2 m were observed on the coasts of Uruguay and southeastern Brazil. Marked differences in tsunami height from pairs of closely located tide gauge sites on the coast of Argentina illustrate the importance that local topographic resonance effects can have on the observed wave response. Findings reveal that, outside the Indian Ocean, the highest waves were recorded in the South Atlantic and not in the Pacific as has been previously suggested

    Rapid Evidence Review of Community Engagement and Resources in the UK during the COVID-19 Pandemic: How Can Community Assets Redress Health Inequities?

    Get PDF
    Community engagement, such as participating in arts, nature or leisurely activities, is positively associated with psychological and physiological wellbeing. Community-based engagement during the COVID-19 pandemic facilitated informal and local mutual aid between individuals. This rapid evidence review assesses the emergence of community-based arts, nature, music, theatre and other types of cultural engagement amongst UK communities in response to the COVID-19 pandemic. Here, we focus on all community engagement with a sub-focus on provisions accessed by and targeted towards vulnerable groups. Two hundred and fifty-six resources were included that had been created between February 2020 and January 2021. Resources were identified through Google Scholar, PubMed, Web of Science, MedRXic, PsycharXiv and searches for grey literature and items in the public domain. The majority reported services that had been adapted to become online, telephone-based or delivered at a distance from doorsteps. Several quality assessment frameworks were used to evaluate the quality of data. Whilst a number of peer-reviewed, grey literature and public domain articles were identified, less than half of the identified literature met quality thresholds. The pace of the response to the pandemic may have meant that robust evaluation procedures were not always in place

    ROSAT HRI observations of Centaurus A

    Get PDF
    We present results from a sensitive high-resolution X-ray observation of the nearby active galaxy Centaurus A (NGC 5128) with the ROSAT HRI. The 65~ksec X-ray image clearly distinguishes different components of the X-ray emission from Cen A: the nucleus and the jet, the diffuse galaxy halo, and a number of individual sources associated with the galaxy. The luminosity of the nucleus increased by a factor of two compared to an earlier ROSAT observation in 1990. The high spatial resolution of the ROSAT HRI shows that most of the knots in the jet are extended both along and perpendicular to the jet axis. We report the detection of a new X-ray feature, at the opposite side of the X-ray jet which is probably due to compression of hot interstellar gas by the expanding southwestern inner radio lobe.Comment: To be published in Astrophys. Journal Letters. 4 pages, 3 plate

    Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity

    Get PDF
    corecore