Search results for " magnitude"
showing 10 items of 407 documents
The relaxation dynamics of a simple glass former confined in a pore
2000
We use molecular dynamics computer simulations to investigate the relaxation dynamics of a binary Lennard-Jones liquid confined in a narrow pore. We find that the average dynamics is strongly influenced by the confinement in that time correlation functions are much more stretched than in the bulk. By investigating the dynamics of the particles as a function of their distance from the wall, we can show that this stretching is due to a strong dependence of the relaxation time on this distance, i.e. that the dynamics is spatially very heterogeneous. In particular we find that the typical relaxation time of the particles close to the wall is orders of magnitude larger than the one of particles …
Comparative study of techniques for large-scale feature selection* *This work was suported by a SERC grant GR/E 97549. The first author was also supp…
1994
The combinatorial search problem arising in feature selection in high dimensional spaces is considered. Recently developed techniques based on the classical sequential methods and the (l, r) search called Floating search algorithms are compared against the Genetic approach to feature subset search. Both approaches have been designed with the view to give a good compromise between efficiency and effectiveness for large problems. The purpose of this paper is to investigate the applicability of these techniques to high dimensional problems of feature selection. The aim is to establish whether the properties inferred for these techniques from medium scale experiments involving up to a few tens …
Microstructural modifications resulting from the dehydration of gypsum
2001
Various faces of dehydrated gypsum-cleaved blocks and single crystals have been investigated using optical microscopy, SEM, and TEM. The orientation of the cracks with respect to the initial gypsum structure and the Miller indices of all possible crack planes have been determined. These crack planes have been found to be few and to correspond to planes of high atomic density in the initial and final structures, therefore characterised by a low surface tension. These observations allow us to propose cracking criteria based on general concepts of crystal growth. The cracks' dimensions measured on different faces of the pseudomorph are distributed over several orders of magnitude and seems to …
Solid sediment transport in turbulent channel flow over irregular rough boundaries
2017
Abstract The presence of a loading of dispersed particles in a turbulent flow affects the dynamics of the carrier flow field which, in turn, drives grains movement. The focus of the paper is on the analysis of the coupling effects between near-bed turbulence structures and the dynamics of dispersed suspended solid particles in wall-bounded turbulent multiphase flows. We consider turbulent horizontal channel flows bounded by rough boundaries. The friction Reynolds number of the unladen flow is R e τ = 180 and the dispersed phase spans one order of magnitude of particle diameter. To analyze sedimentation and suspended phase transport, we adopt concepts and modeling ideas derived from the Eule…
New Results from the NUMEN Project
2018
International audience; NUMEN aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0νββ), by high-accuracy measurements of the cross sections of Heavy Ion (HI) induced Double Charge Exchange (DCE) reactions. First evidence about the possibility to get quantitative information about NME from experiments is found for the (^18O,^18Ne) and (^20Ne,^20O) reactions. Moreover, to infer the neutrino average masses from the possible measurement of the half-life of 0νββ decay, the knowledge of the NME is a crucial aspect. The key tools for this project are the high resolution Superconducting Cyclotron beam…
STUDIO DI UN AMMORTIZZATORE ELETTROMAGNETICO A RECUPERO DI ENERGIA
2013
Questo lavoro ha come obiettivo principale lo studio teorico e con supporto di software F.E.M. di un dispositivo che consenta recupero energetico da una sospensione automobilistica. In sostituzione allo smorzatore viscoso, che dissipa l’energia cinetica del veicolo a seguito dell’attraversamento di strade sconnesse o ostacoli più marcati, si è usato uno smorzatore elettromagnetico che svolga le funzioni dello smorzatore viscoso consentendo un recupero di energia elettrica. Lo smorzatore elettromagnetico è di tipo a magneti permanenti e il suo funzionamento si basa sul fenomeno dell’induzione elettromagnetica. Il modello matematico descrive il funzionamento dello smorzatore, restituendo i va…
High efficacy of face masks explained by characteristic regimes of airborne SARS-CoV-2 virus abundance
2021
Abstract Airborne transmission is an important transmission pathway for viruses, including SARS-CoV-2. Regions with a higher proportion of people wearing masks show better control of COVID-19, but the effectiveness of masks is still under debate due to their limited and variable efficiencies in removing respiratory particles. Here, we analyze experimental data and perform model calculations to show that this contrast can be explained by the different regimes of abundance of particles and viruses. Because of the large number of particles exhaled during human respiration and vocalization, indoor environments are usually in a particle-rich regime which means that masks cannot prevent the inhal…
Ag2 and Ag3 clusters: synthesis, characterization, and interaction with DNA.
2015
Subnanometric samples, containing exclusively Ag2 and Ag3 clusters, were synthesized for the first time by kinetic control using an electrochemical technique without the use of surfactants or capping agents. By combination of thermodynamic and kinetic measurements and theoretical calculations, we show herein that Ag3 clusters interact with DNA through intercalation, inducing significant structural distortion to the DNA. The lifetime of Ag3 clusters in the intercalated position is two to three orders of magnitude longer than for classical organic intercalators, such as ethidium bromide or proflavine. Fil: Buceta, David. Universidad de Santiago de Compostela; España Fil: Busto, Natalia. Unive…
The performance of the cryogenic buffer-gas stopping cell of SHIPTRAP
2018
Direct high-precision mass spectrometry of the heaviest elements with SHIPTRAP, at GSI in Darmstadt, Germany, requires high efficiency to deal with the low production rates of such exotic nuclides. A second-generation gas stopping cell, operating at cryogenic temperatures, was developed and recently integrated into the relocated system to boost the overall efficiency. Offline measurements using 223Ra and 225Ac recoil-ion sources placed inside the gas volume were performed to characterize the gas stopping cell with respect to purity and extraction efficiency. In addition, a first online test using the fusion-evaporation residue 254No was performed, resulting in a combined stopping and extrac…
Lysozyme crystallization rates controlled by anomalous fluctuations
2005
Abstract Nucleation of protein aggregates and crystals is a process activated by statistical fluctuations of concentration. Nucleation rates may change by several orders of magnitude upon apparently minor changes in the multidimensional space of parameters (temperature, pH, protein concentration, salt type and concentrations, additives). We use available data on hen egg lysozyme crystal induction times in different solution conditions. We measure by static and dynamic light scattering the amplitudes and lifetimes of anomalously ample and long-lived fluctuations occurring in proximity of the liquid–liquid demixing region of the given lysozyme solutions. This allows determining the related sp…