Search results for "four"

Analyzing chemical changes in verdigris pictorial specimens upon bacteria and fungi biodeterioration using voltammetry of microparticles

2017

[EN] It is reported the application of the voltammetry of microparticles (VMP), complemented with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and field emission scanning electron microscopy (FESEM) techniques, to monitor the deterioration of verdigris pictorial specimens under the action of different biological agents. This methodology would be of application for identifying the type of biological agent causing deterioration of paintings, which is an important problem affecting cultural heritage. The analysis of biodeterioration processes is complicated by the fact that the action of microorganisms can affect both pigment and binding media. The deteriorat…

Investigation on four centuripe vases (late 3rd-2nd cent. B.C.) by portable X-ray fluorescence and total reflectance-FTIR

2021

Abstract Four Centuripe vases dated back to the late 3rd-2nd centuries B.C. were analysed using imaging under visible and ultra-violet illumination as well as complementary non-invasive and non-destructive portable X-Ray Fluorescence (XRF) and Total Reflectance – Fourier Transform InfraRed (TR-FTIR) spectroscopies. The vases are of great importance since they represent a rare expression of the Hellenistic vase painting. Four specimens, a “pyxis”, a “lebes gamikos” and two “lekanides” decorated with figures of different type, are exhibited in the Antonino Salinas Archaeological Museum in Palermo-Italy. The investigation was aimed to identify the used pigments and the painting technique, to r…

Riflessioni "a margine". Il workshop "Sul margine dell'Orto Botanico di Palermo" dal punto di vista di una storica dell'arte

2020

The paper is the result of a historical research conducted during the Architecture workshop "Sul margine dell'Orto Botanico di Palermo. Spazi per Visiting Professor" ("On the edge of the Botanical Garden of Palermo. Spaces for Visiting Professor"), organized from 24 to 27 September 2018 by the Professors of the University of Palermo Andrea Sciascia, Giuseppe Di Benedetto, Giuseppe Marsala and Antonino Margagliotta and included in the teaching activities of the PhD in Architecture, Arts and Planning. It consists of a descriptive part of the Manifesta12 interventions – the prestigious nomadic Biennial of contemporary art whose last edition took place in Palermo – at the Botanical Garden. This…

2019

Structural changes of glycolic acid (GA) complex with nitrogen induced by selective overtone excitation of the νOH mode were followed in argon matrices using FTIR spectroscopy. For the most stable SSC1 complex present in different trapping sites directly upon deposition site, selective changes in the νOH region were achieved upon near-infrared irradiation. Simultaneously, new conformers of the GA…N2 complex were formed, giving rise to several sets of bands in the νOH and νC=O regions of the spectra. Both position and intensity of new absorptions appeared to be highly sensitive on the wavelength of radiation used, as well as on the annealing of the matrix. Based on theoretical calculations a…

High resolution Fourier transform infrared spectroscopy and analysis of the ν 6 band of jet-cooled Mo(CO) 6

2000

Abstract Rovibrational FTIR spectra of Mo(CO) 6 have been recorded in supersonic argon expansions at 0.004 cm −1 resolution. Rotational constants have been determined for the ν 6 fundamental band of Mo( 12 CO) 6 and for the parallel band of the symmetric top isotopomer Mo( 13 CO)( 12 CO) 5 . From these results, a precise estimate of the Coriolis parameter for the ν 6 band of the main isotopomer Mo( 12 CO) 6 is derived, necessary for the analysis of the ν 6 spectrum. The observation of an octahedral splitting clearly resolved for the highest J-lines in the R branch prompted the use of a specific treatment based on the tensorial formalism developed by J.P. Champion, M. Loete, G. Pierre (Spher…

Localization Operators and an Uncertainty Principle for the Discrete Short Time Fourier Transform

2014

Localization operators in the discrete setting are used to obtain information on a signalffrom the knowledge on the support of its short time Fourier transform. In particular, the extremal functions of the uncertainty principle for the discrete short time Fourier transform are characterized and their connection with functions that generate a time-frequency basis is studied.

Image quality with multifocal intraocular lenses and the effect of pupil size

2007

Purpose To analyze the image quality with a refractive and 2 hybrid refractive–diffractive multifocal intraocular lenses (IOLs) in vitro to determine the IOL modulation transfer function (MTF) following the EN-ISO international standard for distance and near vision and to study the IOLs' behavior with different pupil sizes. Setting Fundacion Oftalmologica del Mediterraneo, Valencia, Spain. Methods This study evaluated 4 IOLs: the hybrid refractive–diffractive AcrySof ReSTOR SN60D3 (Alcon) and Tecnis ZM900 (AMO), the refractive ReZoom NXG (AMO), and the monofocal AcrySof SN60WF (Alcon). The MTF was calculated from the cross-line spread function recorded with the OPAL Vector System (Image Sci…

A neural network-based approach to determine FDTD eigenfunctions in quantum devices

2009

This article combines a Neural Network (NN) algorithm with the Finite Difference Time Domain (FDTD) technique to estimate the eigenfunctions in quantum devices. A NN based on the Least Mean Squares (LMS) algorithm is combined with the FDTD technique to provide a first approach to the confined states in quantum wires. The proposed technique is in good agreement with analytical results and is more efficient than FDTD combined with the Fourier Transform. This technique is used to cal- culate a numerical approximation to the eigenfunctions associated to quan- tum wire potentials. The performance and convergence of the proposed technique are also presented in this article. © 2009 Wiley Periodica…

Distributed Consensus in Networks of Dynamic Agents

2006

Stationary and distributed consensus protocols for a network of n dynamic agents under local information is considered. Consensus must be reached on a group decision value returned by a function of the agents' initial state values. As a main contribution we show that the agents can reach consensus if the value of such a function computed over the agents' state trajectories is time invariant. We use this basic result to introduce a protocol design rule allowing consensus on a quite general set of values. Such a set includes, e.g., any generalized mean of order p of the agents' initial states. We demonstrate that the asymptotical consensus is reached via a Lyapunov approach. Finally we perfor…

Retrieval of atmospheric CH4profiles from Fourier transform infrared data using dimension reduction and MCMC

2016

We introduce an inversion method that uses dimension reduction for the retrieval of atmospheric methane (CH4) profiles. Uncertainty analysis is performed using the Markov chain Monte Carlo (MCMC) statistical estimation. These techniques are used to retrieve CH4 profiles from the ground-based spectral measurements by the Fourier Transform Spectrometer (FTS) instrument at Sodankyla (67.4 degrees N, 26.6 degrees E), Northern Finland. The Sodankyla FTS is part of the Total Carbon Column Observing Network (TCCON), a global network that observes solar spectra in near-infrared wavelengths. The high spectral resolution of the data provides approximately 3 degrees of freedom about the vertical struc…