15,221 research outputs found
Average Rate of Downlink Heterogeneous Cellular Networks over Generalized Fading Channels - A Stochastic Geometry Approach
In this paper, we introduce an analytical framework to compute the average
rate of downlink heterogeneous cellular networks. The framework leverages
recent application of stochastic geometry to other-cell interference modeling
and analysis. The heterogeneous cellular network is modeled as the
superposition of many tiers of Base Stations (BSs) having different transmit
power, density, path-loss exponent, fading parameters and distribution, and
unequal biasing for flexible tier association. A long-term averaged maximum
biased-received-power tier association is considered. The positions of the BSs
in each tier are modeled as points of an independent Poisson Point Process
(PPP). Under these assumptions, we introduce a new analytical methodology to
evaluate the average rate, which avoids the computation of the Coverage
Probability (Pcov) and needs only the Moment Generating Function (MGF) of the
aggregate interference at the probe mobile terminal. The distinguishable
characteristic of our analytical methodology consists in providing a tractable
and numerically efficient framework that is applicable to general fading
distributions, including composite fading channels with small- and mid-scale
fluctuations. In addition, our method can efficiently handle correlated
Log-Normal shadowing with little increase of the computational complexity. The
proposed MGF-based approach needs the computation of either a single or a
two-fold numerical integral, thus reducing the complexity of Pcov-based
frameworks, which require, for general fading distributions, the computation of
a four-fold integral.Comment: Accepted for publication in IEEE Transactions on Communications, to
appea
Searches for the Higgs boson with H â WW â 2l2Îœ and H â ZZ â 4l at CMS
Searches for the standard model Higgs boson using approximatively 5 fbâ1 of 7TeV and 19.6 fbâ1 of 8TeV pp collisions data collected with the CMS detector at LHC in the fully leptonic channels H â WW â 2l2Îœ and H â ZZ â 4l
have been performed. In the former channel, an excess of events is observed above background, consistent with the expectations from a Higgs boson of mass around 125 GeV with a statistical significance of 4.0Ï. In the latter channel, the boson is observed with a local significance of 6.7Ï, with the mass 125.8 ± 0.5 (stat.) ±0.2 (syst.) GeV. In both channels the observed signal strength ÎŒ = Ï/ÏSM, relative to
the expectation for the standard model Higgs boson, is consistent with one
Phantom Membrane Microfluidic Cross-Flow Filtration Device for the Direct Optical Detection of Water Pollutants
The diffusion of autonomous sensing platforms capable of a remote large-scale surveillance of environmental water basins is currently limited by the cost and complexity of standard analytical methods. In order to create a new generation of water analysis systems suitable for continuous monitoring of a large number of sites, novel technical solutions for fluid handling and detection are needed. Here we present a microfluidic device hosting a perfluorinated microporous membrane with refractive index similar to that of water, which enables the combination of filtration and label-free sensing of adsorbing substances, mainly pollutants, in environmental water samples. The cross-flow design of the microfluidic device avoids the clogging of the membrane due to particulate, whereas molecules with some hydrophobic moiety contained in the crossing flow are partially retained and their adhesion on the inner surface of the membrane yields an increase of light scattering intensity, which can be easily measured using a simple instrument based on Light Emitting Diode illumination. By cycling sample water and pure water as a reference, we demonstrate the detection of 0.5 microM of a model cationic surfactant and regeneration of the sensing surface. The optical response of the membrane sensor was characterized using a simple theoretical model that enables to quantify the concentration of target molecules from the amplitude and kinetics of the measured binding curves. The device was tested with real water samples containing large amount of environmental particles, without showing clogging of the membrane, and enabling nonspecific quantification of adsorbing substances in a few minutes.This project has received funding from the European Unionâs Seventh Framework Programme (FP7) for Research, Technological Development and Demonstration through the NAPES project(grant agreement no. 604241). FBL acknowledges the RamĂłn y CajalProgramme (Ministerio de EconomĂa y Competitividad), Spain. FBL personally acknowledges to Elkartek (KK-2015/00088) Grant from the Gobierno Vasco and funding support from Gobierno de España, Ministerio de Economia y Competitividad, with Grant No. BIO2016-80417-P and to Marian M. De Pancorbo for letting him to use her laboratory facilities at UPV/EHU. PSA was generously provided byAdhesive Research, Ireland. We thank Aurora Giavazzi for helping in the collection of river water samples
Analytic continuation by averaging Pad\'e approximants
The ill-posed analytic continuation problem for Green's functions and
self-energies is investigated by revisiting the Pad\'{e} approximants
technique. We propose to remedy the well-known problems of the Pad\'{e}
approximants by performing an average of several continuations, obtained by
varying the number of fitted input points and Pad\'{e} coefficients
independently. The suggested approach is then applied to several test cases,
including Sm and Pr atomic self-energies, the Green's functions of the Hubbard
model for a Bethe lattice and of the Haldane model for a nano-ribbon, as well
as two special test functions. The sensitivity to numerical noise and the
dependence on the precision of the numerical libraries are analysed in detail.
The present approach is compared to a number of other techniques, i.e. the
non-negative least-square method, the non-negative Tikhonov method and the
maximum entropy method, and is shown to perform well for the chosen test cases.
This conclusion holds even when the noise on the input data is increased to
reach values typical for quantum Monte Carlo simulations. The ability of the
algorithm to resolve fine structures is finally illustrated for two relevant
test functions.Comment: 10 figure
Rotational sensitivity of the "G-Pisa" gyrolaser
G-Pisa is an experiment investigating the possibility to operate a high
sensitivity laser gyroscope with area less than for improving the
performances of the mirrors suspensions of the gravitational wave antenna
Virgo. The experimental set-up consists in a He-Ne ring laser with a 4 mirrors
square cavity. The laser is pumped by an RF discharge where the RF oscillator
includes the laser plasma in order to reach a better stability. The contrast of
the Sagnac fringes is typically above 50% and a stable regime has been reached
with the laser operating both single mode or multimode. The effect of hydrogen
contamination on the laser was also checked. A low-frequency sensitivity, below
, in the range of has been
measured.Comment: 6 pages, 6 figures, presented at the EFTF-IFCS joint conference 200
COVID-19 emergency in the hospital: How the clinical psychology unit is responding
The present commentary describes the main care services implemented by the clinical psychology unit of an Italian hospital to cope with the COVID-19 emergency outbreak. The unit's main goal has been to support and protect health care professionals, relatives of hospitalized patients, and patients themselves from further psychological distress. Details and insights are shared. (PsycInfo Database Record (c) 2020 APA, all rights reserved)
Carbon nanotubes as target for directional detection of light WIMP
In this paper I will briefly introduce the idea of using Carbon Nanotubes
(CNT) as target for the detection of low mass WIMPs with the additional
information of directionality. I will also present the experimental efforts of
developing a Time Projection Chamber with a CNT target inside and the results
of a test beam at the Beam Test Facility of INFN-LNF.Comment: 3 figures, IFAE2017 poster session proceeding
Fast Ultrahigh-Density Writing of Low Conductivity Patterns on Semiconducting Polymers
The exceptional interest in improving the limitations of data storage,
molecular electronics, and optoelectronics has promoted the development of an
ever increasing number of techniques used to pattern polymers at micro and
nanoscale. Most of them rely on Atomic Force Microscopy to thermally or
electrostatically induce mass transport, thereby creating topographic features.
Here we show that the mechanical interaction of the tip of the Atomic Force
Microscope with the surface of a class of conjugate polymers produces a local
increase of molecular disorder, inducing a localized lowering of the
semiconductor conductivity, not associated to detectable modifications in the
surface topography. This phenomenon allows for the swift production of low
conductivity patterns on the polymer surface at an unprecedented speed
exceeding 20 ; paths have a resolution in the order of the tip
size (20 nm) and are detected by a Conducting-Atomic Force Microscopy tip in
the conductivity maps.Comment: 22 pages, 6 figures, published in Nature Communications as Article (8
pages
Almost cyclic elements in cross-characteristic representations of finite groups of Lie type
This paper is a significant contribution to a general programme aimed to
classify all projective irreducible representations of finite simple groups
over an algebraically closed field, in which the image of at least one element
is represented by an almost cyclic matrix (that is, a square matrix of size
over a field with the property that there exists such
that is similar to , where is cyclic
and ). While a previous paper dealt with the Weil
representations of finite classical groups, which play a key role in the
general picture, the present paper provides a conclusive answer for all
cross-characteristic projective irreducible representations of the finite
quasi-simple groups of Lie type and their automorphism groups.Comment: To appear on Journal of Group Theor
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