7,138 research outputs found
A Noise-Robust Method with Smoothed \ell_1/\ell_2 Regularization for Sparse Moving-Source Mapping
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
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
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
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
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
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
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 200 cm irradiated with neutrons showed a radiation
hardness up to a fluence of ncm with a hit efficiency of
about 99% and a noise occupancy lower than hits in a LHC bunch
crossing of 25ns at 150V
Universal Fluctuation of the Hall Conductance in the Random Magnetic Field
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 , 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
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
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