Search results for " Methods"

Ca(u)se di bellezza / Beauty’s causes

2018

Efficace, come dicono i vocabolari, è sinonimo di adeguato o adatto e sembrerebbe riferirsi ad aspetti funzionali; ma basta poco per accorgersi che li oltrepassa per riguardare questioni più ampie che sono relative ai processi, includendo le premesse e gli esiti, attraversando i metodi e le procedure. Il termine deriva infatti dal latino efficere - che significa fare (facere) del tutto (ex-) - con il valore di fare o produrre, ma anche di portare a compimento, di operare in modo che una cosa produca il suo effetto o che sia di effetto. Sul significato di efficace (nello specifico dell’architettura), attraverso il fascino delle parole e la profondità di senso che esse possiedono, si possono …

The Time Response of Glass Resistive Plate Chambers to Heavily Ionizing Particles

2007

The HARP system of resistive plate chambers (RPCs) was designed to perform particle identification by the measurement of the difference in the time-of-flight of different particles. In previous papers an apparent discrepancy was shown between the response of the RPCs to minimum ionizing pions and heavily ionizing protons. Using the kinematics of elastic scattering off a hydrogen target a controlled beam of low momentum recoil protons was directed onto the chambers. With this method the trajectory and momentum, and hence the time-of-flight of the protons can be precisely predicted without need for a measurement of momentum of the protons. It is demonstrated that the measurement of the time-o…

ELECTROCHEMICAL MICROREACTORS FOR THE ABATEMENT OF ORGANIC POLLUTANTS IN WATER SOLUTION

2015

Electrochemical methods can offer new sustainable routes for the abatement of organic pollutants resistant to biological processes. These methods use a clean reagent, the electron, and very mild operative conditions (ambient temperature and atmospheric pressure) with limited operative costs. However, electrochemical processes present some important disadvantages when performed in conventional reactors. In particular, to achieve reasonable cell voltages when the medium has not an adequate conductivity, one needs adding to the system a supporting electrolyte. This is certainly a main obstacle for a wide application of electrochemical tools. Indeed, adding chemicals is often a problematic issu…

Electrochemical methods for carrier type identification of ZnO films grown by pulsed laser deposition on InP.

2013

The renormalized electron mass in non-relativistic quantum electrodynamics

2007

This work addresses the problem of infrared mass renormalization for a scalar electron in a translation-invariant model of non-relativistic QED. We assume that the interaction of the electron with the quantized electromagnetic field comprises a fixed ultraviolet regularization and an infrared regularization parametrized by $\sigma>0$. For the value $p=0$ of the conserved total momentum of electron and photon field, bounds on the renormalized mass are established which are uniform in $\sigma\to0$, and the existence of a ground state is proved. For $|p|>0$ sufficiently small, bounds on the renormalized mass are derived for any fixed $\sigma>0$. A key ingredient of our proofs is the operator-t…

A deep study of the high–energy transient sky

2021

This is an open access article. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds t…

Compensation of missing wedge effects with sequential statistical reconstruction in electron tomography.

2014

Electron tomography (ET) of biological samples is used to study the organization and the structure of the whole cell and subcellular complexes in great detail. However, projections cannot be acquired over full tilt angle range with biological samples in electron microscopy. ET image reconstruction can be considered an ill-posed problem because of this missing information. This results in artifacts, seen as the loss of three-dimensional (3D) resolution in the reconstructed images. The goal of this study was to achieve isotropic resolution with a statistical reconstruction method, sequential maximum a posteriori expectation maximization (sMAP-EM), using no prior morphological knowledge about …

Modelling of silver adhesion on MgO(100) surface with defects

1999

We show how surface defects (especially Fs 0 and Vs 0 centres) can play a major role in the adhesion of Ag (at 1:4 and 1:1 coverages) on the MgO(100) surface. Our calculations use a periodic (slab) model and an ab initio Hartree-Fock approach with a posteriori electron correlation corrections. We are able to analyse the interatomic bond populations, effective charges and multipole moments of ions, in combination with the interface binding energy and the equilibrium distances. Both surface defects cause strong redistributions of the electron density which increase the binding energy of metal atoms by more than an order of magnitude. This implies radiation-induced strengthening of metal adhes…

Theoretical study of the molecular structure and the stability of neutral and reduced tetracyanoethylene

2003

Abstract The molecular structure and the stability of neutral, anionic, and dianionic tetracyanoethylene (TCNE) have been studied with MP2, coupled-cluster (CC), and density functional theory (DFT) procedures. The optimized geometries are in agreement with the available experimental data, although significant deviations for the CN bond distance have been obtained at the MP2 level. The adiabatic electron affinity of TCNE calculated with the B3LYP method is overestimated by 0.32 eV. In the light of the CC results, the source of such an overestimation is suggested to lie on the theoretical approach, rather than on a too low experimental value.

Electronic Properties of Layered Ba0.5Sr0.5TiO3 Heterostructure: Ab initio Hybrid Density Functional Calculations

2005

Ab initio calculations of the BST heterostructure with equiatomic constituent of Sr and Ba species has been carried out within hybrid functional B3PW involving a hybrid of non-local Fock exchange and Becke's gradient corrected exchange functional combined with the non-local gradient corrected correlation potential by Perdew and Wang. The suggested scheme of calculations reproduces experimental lattice parameters of both pure BaTiO3 and SrTiO3. The calculated optical band gap for the pure SrTiO3 (BaTiO3) is 3.56 (3.46) eV (expt. 3.25 and 3.20 eV, respectively), i.e. agreement is much better than in the standard LDA or HF calculations. In the Ba0.5Sr0.5TiO3 solid solution the gap is reduced b…