634 research outputs found

    The effective elastic thickness of the India Plate from receiver function imaging, gravity anomalies and thermomechanical modelling

    Get PDF
    The range and the meaning of the effective elastic thickness (EET) in continental areas have been subject to controversy over the last two decades. Here we take advantage of the new data set from the Hi-CLIMB seismological experiment to re-estimate the EET of the India Plate along a south-north profile extending from the Ganges basin to central Tibet. Receiver functions give a high-resolution image of the base of the foreland basin at similar to 5 km depth and constrain the crustal thickness, which increases northwards from similar to 35 km beneath the indo-gangetic plain to similar to 70 km in southern Tibet. Together with available data sets including seismic profiles, seismological images from both INDEPTH and HIMNT experiments, deep well measurements and Bouguer anomaly profiles, we interpret this new image with 2-D thermomechanical modelling solutions, using different type of crustal and mantle rheologies. We find that (1) the EET of the India Plate decreases northwards from 60-80 to 20-30 km as it is flexed down beneath Himalaya and Tibet, due to thermal and flexural weakening; (2) the only resistant layer of the India Plate beneath southern Tibet is the upper mantle, which serves as a support for the topographic load and (3) the most abrupt drop in the EET, located around 200 km south of the MFT, is associated with a gradual decoupling between the crust and the mantle. We show that our geometrical constraints do not allow to determine if the upper and lower crust are coupled or not. Our results clearly reveal that a rheology with a weak mantle is unable to explain the geometry of the lithosphere in this region, and they are in favour of a rheology in which the mantle is strong

    Computing the kk-coverage of a wireless network

    Full text link
    Coverage is one of the main quality of service of a wirelessnetwork. kk-coverage, that is to be covered simultaneously by kknetwork nodes, is synonym of reliability and numerous applicationssuch as multiple site MIMO features, or handovers. We introduce here anew algorithm for computing the kk-coverage of a wirelessnetwork. Our method is based on the observation that kk-coverage canbe interpreted as kk layers of 11-coverage, or simply coverage. Weuse simplicial homology to compute the network's topology and areduction algorithm to indentify the layers of 11-coverage. Weprovide figures and simulation results to illustrate our algorithm.Comment: Valuetools 2019, Mar 2019, Palma de Mallorca, Spain. 2019. arXiv admin note: text overlap with arXiv:1802.0844

    Organizational Adaptation

    Get PDF
    Organizational adaptation is equivocal. On the one hand, the concept is ubiquitous in management research and acts as the glue binding together the central issues of organizational change, performance, and survival. On the other hand, it lurks around in various guises (e.g., “fit,” “alignment,” “congruence,” and “strategic change”) studied from multiple theoretical streams (e.g., behavioral, resource based, and institutional) and at different levels of analysis (e.g., organization and industry levels). In a novel approach to reviewing 443 adaptation articles that leverages both computational and hand-coded analysis, we produce an interactive visual of the themes most studied by adaptation scholars. We inductively draw out a definition of adaptation as intentional decision making undertaken by organizational members, leading to observable actions that aim to reduce the distance between an organization and its economic and institutional environments. We then review the literature across three main areas of inquiry and six theoretical perspectives that surfaced from our analysis and identify 11 difficulties that have hampered adaptation research in the past 50 years. Our review suggests ways to address these difficulties to enable future research to develop and cumulate

    Decreased levels of serum platelet-activating factor acetylhydrolase in patients with rheumatic diseases

    Get PDF
    PAF is a potent inflammatory compound known to stimulate the release of various cytokines involved in rheumatic diseases. Elevated blood PAF levels are reported in these patients. We report that serum PAF acetylhydrolase activity (AHA) levels are decreased in patients with rheumatoid arthritis or osteoarthritis as compared to healthy controls. Serum and synovial fluid AHA levels were correlated in these patients. The present study suggests the potential role of AHA in controling systemic and/or local PAF levels in patients with rheumatic diseases

    Performance of a UV-A LED system for degradation of aflatoxins B1 and M1 in pure water: kinetics and cytotoxicity study

    Get PDF
    The efficacy of a UV-A light emitting diode system (LED) to reduce the concentrations of aflatoxin B1, aflatoxin M1 (AFB1, AFM1) in pure water was studied. This work investigates and reveals the kinetics and main mechanism(s) responsible for the destruction of aflatoxins in pure water and assesses the cytotoxicity in liver hepatocellular cells. Irradiation experiments were conducted using an LED system operating at 365 nm (monochromatic wave-length). Known concentrations of aflatoxins were spiked in water and irradiated at UV-A doses ranging from 0 to 1,200 mJ/cm2. The concentration of AFB1 and AFM1 was determined by HPLC with fluorescence detection. LC–MS/MS product ion scans were used to identify and semi-quantify degraded products of AFB1 and AFM1. It was observed that UV-A irradiation significantly reduced aflatoxins in pure water. In comparison to control, at dose of 1,200 mJ/cm2 UV-A irradiation reduced AFB1 and AFM1 concentrations by 70 ± 0.27 and 84 ± 1.95%, respectively. We hypothesize that the formation of reactive species initiated by UV-A light may have caused photolysis of AFB1 and AFM1 molecules in water. In cell culture studies, our results demonstrated that the increase of UV-A dosage decreased the aflatoxins-induced cytotoxicity in HepG2 cells, and no significant aflatoxin-induced cytotoxicity was observed at UV-A dose of 1,200 mJ/cm2. Further results from this study will be used to compare aflatoxins detoxification kinetics and mechanisms involved in liquid foods such as milk and vegetable oils

    Sharp error terms for return time statistics under mixing conditions

    Get PDF
    We describe the statistics of repetition times of a string of symbols in a stochastic process. Denote by T(A) the time elapsed until the process spells the finite string A and by S(A) the number of consecutive repetitions of A. We prove that, if the length of the string grows unbondedly, (1) the distribution of T(A), when the process starts with A, is well aproximated by a certain mixture of the point measure at the origin and an exponential law, and (2) S(A) is approximately geometrically distributed. We provide sharp error terms for each of these approximations. The errors we obtain are point-wise and allow to get also approximations for all the moments of T(A) and S(A). To obtain (1) we assume that the process is phi-mixing while to obtain (2) we assume the convergence of certain contidional probabilities

    Polarimetry of an Intermediate-age Open Cluster: NGC 5617

    Get PDF
    We present polarimetric observations in the UBVRI bands of 72 stars located in the direction of the medium age open cluster NGC 5617. Our intention is to use polarimetry as a tool membership identification, by building on previous investigations intended mainly to determine the cluster's general characteristics rather than provide membership suitable for studies such as stellar content and metallicity, as well as study the characteristics of the dust lying between the Sun and the cluster. The obsevations were carried out using the five-channel photopolarimeter of the Torino Astronomical Observatory attached to the 2.15m telescope at the Complejo Astron\'omico El Leoncito (CASLEO; Argentina. We are able to add 32 stars to the list of members of NGC 5617, and review the situation for others listed in the literature. In particular, we find that five blue straggler stars in the region of the cluster are located behind the same dust as the member stars are and we confirm the membership of two red giants. The proposed polarimetric memberships are compared with those derived by photometric and kinematical methods, with excellent results. Among the observed stars, we identify 10 with intrinsic polarization in their light. NGC 5617 can be polarimetrically characterized with Pmax=4.40P_{max}= 4.40% and θv=73.1 \theta_{v}= 73^\circ.1. The spread in polarization values for the stars observed in the direction of the cluster seems to be caused by the uneven distribution of dust in front of the cluster's face. Finally, we find that in the direction of the cluster, the interstellar medium is apparently free of dust, from the Sun's position up to the Carina-Sagittarius arm, where NGC 5617 seems to be located at its farthest border

    On the use of dislocations to model interseismic strain and stress build-up at intracontinental thrust faults

    Get PDF
    Creeping dislocations in an elastic half-space are commonly used to model interseismic deformation at subduction zones, and might also apply to major intracontinental thrust faults such as the Main Himalayan Thrust. Here, we compare such models with a more realistic 2-D finite element model that accounts for the mechanical layering of the continental lithosphere and surface processes, and that was found to fit all available constraints on interseismic and long-term surface displacements. These can also be fitted satisfactorily from dislocation models. The conventional back-slip model, commonly used for subduction zones, may, however, lead to a biased inference about the geometry of the locked portion of the thrust fault. We therefore favour the use of a creeping buried dislocation that simulates the ductile shear zone in the lower crust. A limitation of dislocation models is that the mechanical response of the lithosphere to the growth of the topography by bending of the elastic cores and ductile flow in the lower crust cannot be easily introduced. Fortunately these effects can be neglected because we may assume, to first order, a stationary topography. Moreover, we show that not only can dislocation models be used to adjust surface displacements but, with some caution, they can also provide a physically sound rationale to interpret interseismic microseismicity in terms of stress variations

    Invariants of solvable rigid Lie algebras up to dimension 8

    Get PDF
    The invariants of all complex solvable rigid Lie algebras up to dimension eight are computed. Moreover we show, for rank one solvable algebras, some criteria to deduce to non-existence of non-trivial invariants or the existence of fundamental sets of invariants formed by rational functions of the Casimir invariants of the associated nilradical.Comment: 16 pages, 7 table
    corecore