41,760 research outputs found
The empirical process on Gaussian spherical harmonics
We establish weak convergence of the empirical process on the spherical
harmonics of a Gaussian random field in the presence of an unknown angular
power spectrum. This result suggests various Gaussianity tests with an
asymptotic justification. The issue of testing for Gaussianity on isotropic
spherical random fields has recently received strong empirical attention in the
cosmological literature, in connection with the statistical analysis of cosmic
microwave background radiation
Glaucoma and cigarette smoking: a review of narrative reviews
Background: Glaucoma is an optic neuropathy associated with visual field changes for which high intra-ocular pressure is a major
risk factor. Emerging research indicates that modifiable factors, among which the cigarette smoke, besides IOP may be associated with
the presence of glaucoma.
Objective: The objective of the study was to perform a review of narrative reviews to examine on the relationship between cigarette
smoking and glaucoma.
Methods: The results of all narrative reviews in the scientific literature about glaucoma and tobacco smoking were analyzed. A
quality assessment was performed according to an easy and convenient tool for the quality assessment of narrative reviews for
systematic reviews (International Narrative Systematic assessment) the INSA tool. Literature searches were performed using
PubMed.
Results: 20 studies about relation between glaucoma and smoke were collected, no restriction language was applied. 15 of these
studies have been excluded. We selected among them 5 reviews. With the INSA tool we measured the quality of the 5 selected
narrative reviews. Studies that had a highest score with the INSA tool were two: A. Coleman et al. “Risk Factors for Glaucoma
Needing More Attention” and R. Salowe et al. “Primary Open-Angle Glaucoma in Individuals of African Descent: A Review of Risk
Factors”.
Conclusion: The narrative reviews analyzed underline that there is no definitive association between cigarette smoking
Turbulent heat transfer in spacer-filled channels: Experimental and computational study and selection of turbulence models
Heat transfer in spacer-filled channels of the kind used in Membrane Distillation was studied in the Reynolds number range 100–2000, encompassing both steady laminar and early-turbulent flow conditions. Experimental data, including distributions of the local heat transfer coefficient h, were obtained by Liquid Crystal Thermography and Digital Image Processing. Alternative turbulence models, both of first order (k-ε, RNG k-ε, k-ω, BSL k-ω, SST k-ω) and of second order (LRR RS, SSG RS, ω RS, BSL RS), were tested for their ability to predict measured distributions and mean values of h. The best agreement with the experimental results was provided by first-order ω-based models able to resolve the viscous/conductive sublayer, while all other models, and particularly ε-based models using wall functions, yielded disappointing predictions
Evaporation Channel as a Tool to Study Fission Dynamics
The dynamics of the fission process is expected to affect the evaporation
residue cross section because of the fission hindrance due to the nuclear
viscosity. Systems of intermediate fissility constitute a suitable environment
for testing such hypothesis, since they are characterized by evaporation
residue cross sections comparable or larger than the fission ones. Observables
related to emitted charged particle, due to their relatively high emission
probability, can be used to put stringent constraints on models describing the
excited nucleus decay and to recognize the effects of fission dynamics. In this
work model simulations are compared with the experimental data collected via
the ^{32}S + ^{100}Mo reaction at E_{lab}= 200 MeV. By comparing an extended
set of evaporation channel observables the limits of the statistical model and
the large improvement coming by using a dynamical model are evidenced. The
importance of using a large angular covering apparatus to extract the
observable is stressed. The opportunity to measure more sensitive observables
by a new detection device in operation at LNL are also discussed.Comment: v1: 7 pages, 6 figure
Synchronization in interacting Scale Free Networks
We study the fluctuations of the interface, in the steady state, of the
Surface Relaxation Model (SRM) in two scale free interacting networks where a
fraction of nodes in both networks interact one to one through external
connections. We find that as increases the fluctuations on both networks
decrease and thus the synchronization reaches an improvement of nearly
when . The decrease of the fluctuations on both networks is due mainly to
the diffusion through external connections which allows to reducing the load in
nodes by sending their excess mostly to low-degree nodes, which we report have
the lowest heights. This effect enhances the matching of the heights of low-and
high-degree nodes as increases reducing the fluctuations. This effect is
almost independent of the degree distribution of the networks which means that
the interconnection governs the behavior of the process over its topology.Comment: 13 pages, 7 figures. Added a relevant reference.Typos fixe
Optimization of net power density in Reverse Electrodialysis
Reverse Electrodialysis (RED) extracts electrical energy from the salinity difference between two solutions using selective ion exchange membranes. In RED, conditions yielding a large net power density (NPD) are generally desired, due to the still large cost of the membranes. NPD depends on a large number of physical and geometric parameters. Some of these, for example the inlet concentrations of concentrate and diluate, can be regarded as “scenario” variables, imposed by external constraints (e.g., availability) or chosen by different criteria than NPD maximization. Others, namely the thicknesses HCONC, HDIL and the velocities UCONC, UDIL in the concentrate and diluate channels, can be regarded as free design parameters and can be chosen so as to maximize NPD. In the present study, a simplified model of a RED stack was coupled with an optimization algorithm in order to determine the conditions of maximum NPD in the space of the variables HCONC, HDIL,UCONC, UDIL for different sets of “scenario” variables. The study shows that an optimal choice of the free design parameters for any given scenario, as opposed to the adoption of standard fixed values for the same parameters, may provide significant improvements in NPD
Spectral properties of the narrow-line region in Seyfert galaxies selected from the SDSS-DR7
Although the properties of the narrow-line region (NLR) of active galactic
nuclei(AGN) have been deeply studied by many authors in the past three decades,
many questions are still open. The main goal of this work is to explore the NLR
of Seyfert galaxies by collecting a large statistical spectroscopic sample of
Seyfert 2 and Intermediate-type Seyfert galaxies having a high signal-to-noise
ratio in order to take advantage of a high number of emission-lines to be
accurately measured. 2153 Seyfert 2 and 521 Intermediate-type Seyfert spectra
were selected from Sloan Digital Sky Survey - Data Release 7 (SDSS-DR7) with a
diagnostic diagram based on the oxygen emission-line ratios. All the
emission-lines, broad components included, were measured by means of a
self-developed code, after the subtraction of the stellar component. Physical
parameters, such as internal reddening, ionization parameter, temperature,
density, gas and stellar velocity dispersion were determined for each object.
Furthermore, we estimated mass and radius of the NLR, kinetic energy of the
ionized gas, and black-hole accretion rate. From the emission-line analysis and
the estimated physical properties, it appears that the NLR is similar in
Seyfert 2 and Intermediate-Seyfert galaxies. The only differences, lower
extinction, gas kinematics in general not dominated by the host galaxy
gravitational potential and higher percentage of [O III]5007 blue asymmetries
in Intermediate-Seyfert can be ascribed to an effect of inclination of our line
of sight with respect to the torus axis.Comment: Accepted for publication in MNRA
Pain-motor integration in the primary motor cortex in Parkinson's disease
In Parkinson's disease (PD), the influence of chronic pain on motor features has never been investigated. We have recently designed a technique that combines nociceptive system activation by laser stimuli and primary motor cortex (M1) activation through transcranial magnetic stimulation (TMS), in a laser-paired associative stimulation design (Laser-PAS). In controls, Laser-PAS induces long-term changes in motor evoked potentials reflecting M1 long-term potentiation-like plasticity, arising from pain-motor integration
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