7,138 research outputs found

    A Noise-Robust Method with Smoothed \ell_1/\ell_2 Regularization for Sparse Moving-Source Mapping

    Full text link
    The method described here performs blind deconvolution of the beamforming output in the frequency domain. To provide accurate blind deconvolution, sparsity priors are introduced with a smooth \ell_1/\ell_2 regularization term. As the mean of the noise in the power spectrum domain is dependent on its variance in the time domain, the proposed method includes a variance estimation step, which allows more robust blind deconvolution. Validation of the method on both simulated and real data, and of its performance, are compared with two well-known methods from the literature: the deconvolution approach for the mapping of acoustic sources, and sound density modeling

    Decomposition of fractional quantum Hall states: New symmetries and approximations

    Full text link
    We provide a detailed description of a new symmetry structure of the monomial (Slater) expansion coefficients of bosonic (fermionic) fractional quantum Hall states first obtained in Ref. 1, which we now extend to spin-singlet states. We show that the Haldane-Rezayi spin-singlet state can be obtained without exact diagonalization through a differential equation method that we conjecture to be generic to other FQH model states. The symmetry rules in Ref. 1 as well as the ones we obtain for the spin singlet states allow us to build approximations of FQH states that exhibit increasing overlap with the exact state (as a function of system size). We show that these overlaps reach unity in the thermodynamic limit even though our approximation omits more than half of the Hilbert space. We show that the product rule is valid for any FQH state which can be written as an expectation value of parafermionic operators.Comment: 22 pages, 8 figure

    Severe tremor due to vancomycin therapy: a case report and literature review

    Get PDF
    SummaryVancomycin is a popular antimicrobial used to treat a variety of Gram-positive infections. Its side effect profile has been well defined due to its high global utilization as a result of the emergence of antimicrobial-resistant organisms in recent decades. Despite its widespread use, however, various idiosyncratic reactions may occur without adequate or universal reporting. We present a case of severe tremor due to vancomycin that has not been previously reported in the literature. Our patient might have been prone to this adverse effect given an underlying essential tremor. Causality is presumed based on the temporal association, while the pathophysiological link remains elusive

    Identifying Solar Flare Precursors Using Time Series of SDO/HMI Images and SHARP Parameters

    Full text link
    We present several methods towards construction of precursors, which show great promise towards early predictions, of solar flare events in this paper. A data pre-processing pipeline is built to extract useful data from multiple sources, Geostationary Operational Environmental Satellites (GOES) and Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI), to prepare inputs for machine learning algorithms. Two classification models are presented: classification of flares from quiet times for active regions and classification of strong versus weak flare events. We adopt deep learning algorithms to capture both the spatial and temporal information from HMI magnetogram data. Effective feature extraction and feature selection with raw magnetogram data using deep learning and statistical algorithms enable us to train classification models to achieve almost as good performance as using active region parameters provided in HMI/Space-Weather HMI-Active Region Patch (SHARP) data files. Case studies show a significant increase in the prediction score around 20 hours before strong solar flare events

    Plane-wave based electronic structure calculations for correlated materials using dynamical mean-field theory and projected local orbitals

    Full text link
    The description of realistic strongly correlated systems has recently advanced through the combination of density functional theory in the local density approximation (LDA) and dynamical mean field theory (DMFT). This LDA+DMFT method is able to treat both strongly correlated insulators and metals. Several interfaces between LDA and DMFT have been used, such as (N-th order) Linear Muffin Tin Orbitals or Maximally localized Wannier Functions. Such schemes are however either complex in use or additional simplifications are often performed (i.e., the atomic sphere approximation). We present an alternative implementation of LDA+DMFT, which keeps the precision of the Wannier implementation, but which is lighter. It relies on the projection of localized orbitals onto a restricted set of Kohn-Sham states to define the correlated subspace. The method is implemented within the Projector Augmented Wave (PAW) and within the Mixed Basis Pseudopotential (MBPP) frameworks. This opens the way to electronic structure calculations within LDA+DMFT for more complex structures with the precision of an all-electron method. We present an application to two correlated systems, namely SrVO3 and beta-NiS (a charge-transfer material), including ligand states in the basis-set. The results are compared to calculations done with Maximally Localized Wannier functions, and the physical features appearing in the orbitally resolved spectral functions are discussed.Comment: 15 pages, 17 figure

    Searching for the Annual Modulation of Dark Matter signal with the GENIUS-TF experiment

    Full text link
    The annual modulation of the recoil spectrum observed in an underground detector is well known as the main signature of a possible WIMP signal. The GENIUS-TF experiment, under construction in the Gran Sasso National Laboratory, can search for the annual modulation of the Dark Matter signal using 40 kg of naked-Ge detectors in liquid nitrogen. Starting from a set of data simulated under the hypothesis of modulation and using different methods, we show the potential of GENIUS-TF for extracting the modulated signal and the expected WIMP mass and WIMP cross section.Comment: In press, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment (2003) and in Proc. of IDM2002, York Minster, England, 2-6 September, 2002, World Scientific 200

    Characterisation of AMS H35 HV-CMOS monolithic active pixel sensor prototypes for HEP applications

    Full text link
    Monolithic active pixel sensors produced in High Voltage CMOS (HV-CMOS) technology are being considered for High Energy Physics applications due to the ease of production and the reduced costs. Such technology is especially appealing when large areas to be covered and material budget are concerned. This is the case of the outermost pixel layers of the future ATLAS tracking detector for the HL-LHC. For experiments at hadron colliders, radiation hardness is a key requirement which is not fulfilled by standard CMOS sensor designs that collect charge by diffusion. This issue has been addressed by depleted active pixel sensors in which electronics are embedded into a large deep implantation ensuring uniform charge collection by drift. Very first small prototypes of hybrid depleted active pixel sensors have already shown a radiation hardness compatible with the ATLAS requirements. Nevertheless, to compete with the present hybrid solutions a further reduction in costs achievable by a fully monolithic design is desirable. The H35DEMO is a large electrode full reticle demonstrator chip produced in AMS 350 nm HV-CMOS technology by the collaboration of Karlsruher Institut f\"ur Technologie (KIT), Institut de F\'isica d'Altes Energies (IFAE), University of Liverpool and University of Geneva. It includes two large monolithic pixel matrices which can be operated standalone. One of these two matrices has been characterised at beam test before and after irradiation with protons and neutrons. Results demonstrated the feasibility of producing radiation hard large area fully monolithic pixel sensors in HV-CMOS technology. H35DEMO chips with a substrate resistivity of 200Ω\Omega cm irradiated with neutrons showed a radiation hardness up to a fluence of 101510^{15}neq_{eq}cm−2^{-2} with a hit efficiency of about 99% and a noise occupancy lower than 10−610^{-6} hits in a LHC bunch crossing of 25ns at 150V

    Universal Fluctuation of the Hall Conductance in the Random Magnetic Field

    Full text link
    We show that the RMS fluctuation of the antisymmetric part of the Hall conductance of a planar mesoscopic metal in a random magnetic field with zero average is universal, of the order of e2/he^2/h, independent of the amplitude of the random magnetic field and the diffusion coefficient even in the weak field limit. This quantity is exactly zero in the case of ordinary scalar disorder. We propose an experiment to measure this surprising effect, and also discuss its implications on the localization physics of this system. Our result applies to some other systems with broken time-reversal ({\bf T}) symmetry.Comment: 4 pages, Revtex 3.0; added the paragraph regarding applicability to other systems with broken T-invariance, misc. minor change

    Learning from health care in other countries: the prospect of comparative research

    Get PDF
    It is widely accepted that policy-makers (in Nepal and elsewhere) can learn valuable lessons from the way other countries run their health and social services. We highlight some of the specific contributions the discipline of sociology can make to cross-national comparative research in the public health field. Sociologists call attention to often unnoticed social and cultural factors that influence the way national reproductive health care systems are created and operated. In this paper we address questions such as: ‘Why do these health services appear to be operating successfully in one country, but not another?’; ‘What is it in one country that makes a particular public health intervention successful and how is the cultural context different in a neighbouring country?’ The key examples in this paper focus on maternity care and sex education in the Netherlands and the UK, as examples to highlight the power of cross-national research. Our key messages are: a) Cross-national comparative research can help us to understand the design and running of health services in one country, say Nepal, by learning from a comparison with other countries, for example Sri Lanka or India. b) Cultural factors unique to a country affect the way that reproductive health care systems operate. c) Therefore, we need to understand why and how services work in a certain cultural context before we start trying to implement them in another cultural context
    • …
    corecore