3,445 research outputs found
A node-wise analysis of the uterine muscle networks for pregnancy monitoring
The recent past years have seen a noticeable increase of interest in the
correlation analysis of electrohysterographic (EHG) signals in the perspective
of improving the pregnancy monitoring. Here we propose a new approach based on
the functional connectivity between multichannel (4x4 matrix) EHG signals
recorded from the women abdomen. The proposed pipeline includes i) the
computation of the statistical couplings between the multichannel EHG signals,
ii) the characterization of the connectivity matrices, computed by using the
imaginary part of the coherence, based on the graph-theory analysis and iii)
the use of these measures for pregnancy monitoring. The method was evaluated on
a dataset of EHGs, in order to track the correlation between EHGs collected by
each electrode of the matrix (called node-wise analysis) and follow their
evolution along weeks before labor. Results showed that the strength of each
node significantly increases from pregnancy to labor. Electrodes located on the
median vertical axis of the uterus seemed to be the more discriminant. We
speculate that the network-based analysis can be a very promising tool to
improve pregnancy monitoring.Comment: 4 pages, 3 figures, accepted in the IEEE EMBC conferanc
Numerical Modelling for Process Investigation of a Single Coal Particle Combustion and Gasification
Combustion and Gasification are commercial
processes of coal utilization, and therefore continuous
improvement is needed for these applications. The difference
between these processes is the reaction mechanism, in the case
of combustion the reaction products are CO2 and H2O, whereas
in the case of gasification the products are CO, H2 and CH4. In
order to investigate these processes further, a single coal particle
model has been developed. The definition of the chemical
reactions for each process is key for model development. The
developed numerical model simulation uses CFD
(Computational Fluid Dynamic) techniques with an Eddy Break
Up (EBU) model and a kinetics parameter for controlling the
process reaction. The combustion model has been validated and
extended to model the gasification process by inclusion of an
additional chemical reaction. Finally, it is shown that the single
coal particle model could describe single coal particle
combustion and gasification. From the result, the difference
between single coal particle combustion and gasification can
clearly be seen. This simulation model can be considered for
further investigation of coal combustion and gasification
application processes
Limits to ion energy control in high density glow discharges: Measurement of absolute metastable ion concentrations
Unprecedented demands for uniformity, throughput, anisotropy, and damage control in submicron pattern transfer are spurring development of new, low pressure, high charge density plasma reactors. Wafer biasing, independent of plasma production in these new systems is intended to provide improved ion flux and energy control so that selectivity can be optimized and damage can be minimized. However, as we show here, an inherent property of such discharges is the generation of significant densities of excited, metastable ionic states that can bombard workpiece surfaces with higher translational and internal energy. Absolute metastable ion densities are measured using the technique of self-absorption, while the corresponding velocity distributions and density scaling with pressure and electron density are measured using laser-induced fluorescence. For a low pressure, helicon-wave excited plasma, the metastable ion flux is at least 24% of the total ion flux to device surfaces. Because the metastable ion density scales roughly as the reciprocal of the pressure and as the square of the electron density, the metastable flux is largest in low pressure, high charge density plasmas. This metastable ion energy flux effectively limits ion energy and flux control in these plasma reactors, but the consequences for etching and deposition of thin films depend on the material system and remain an open question
Dynamical Theory of Artificial Optical Magnetism Produced by Rings of Plasmonic Nanoparticles
We present a detailed analytical theory for the plasmonic nanoring
configuration first proposed in [A. Alu, A. Salandrino, N. Engheta, Opt. Expr.
14, 1557 (2006)], which is shown to provide negative magnetic permeability and
negative index of refraction at infrared and optical frequencies. We show
analytically how the nanoring configuration may provide superior performance
when compared to some other solutions for optical negative index materials,
offering a more 'pure' magnetic response at these high frequencies, which is
necessary for lowering the effects of radiation losses and absorption.
Sensitivity to losses and the bandwidth of operation of this magnetic inclusion
are also investigated in details and compared with other available setups.Comment: 34 pages, 3 figure
Circuit elements at optical frequencies: nano-inductors, nano-capacitors and nano-resistors
We present some ideas for synthesizing nanocircuit elements in the optical
domain using plasmonic and non-plasmonic nanoparticles. Three basic circuit
elements, i.e., nano-inductors, nano-capacitors, and nano-resistors, are
discussed in terms of small nanostructures with different material properties.
Coupled nanocircuits and parallel and series combinations are also envisioned,
which may provide road maps for the synthesis of more complex nanocircuits in
the IR and visible bands. Ideas for the optical implementation of right-handed
and left-handed nano-transmission lines are also forecasted.Comment: 14 pages, 5 figures, submitted to Physical Review Letter
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