156 research outputs found
Il restauro dei dipinti "olio su tela"
none3Il testo condensa la lunga ed eterogenea attività didattica relativa all’argomento, innanzitutto quella svolta dai tre autori, a vario titolo, presso l’Università di Bologna. Molte affermazioni, cos’ come tutta l’iconografia, derivano direttamente dalla poliedrica e trentennale attività dello “Studio di Restauro G.M.Costanini”. nel tempo, cambiano i materiali e le tecniche di restauro, ma ciò che dovrebbe rimanere saldo per chi è coinvolto in problemi di restauro è la capacità di una lettura sistematica dell’opera d’arte e del suo stato di conservazione e la possibilità di elaborare o valutare gli interventi adatti per rallentare l’inevitabile degrado dei materiali. Per queste ragioni, tutto quello che qui riguarda direttamente i dipinti olio su tela, nella sua articolazione e sistemazione, risulta certamente proficuo anche nell’approccio al restauro di altre categorie di opere d’arte.noneCostantini G.M.; Costato Costantini R.; Fiori C.Costantini G.M.; Costato Costantini R.; Fiori C
Scattering states of coupled valence-band holes in point defect potential derived from variable phase theory
In this article we present a method to compute the scattering states of holes
in spherical bands in the strong spin-orbit coupling regime. More precisely, we
calculate scattering phase shifts and amplitudes of holes induced by defects in
a semiconductor crystal. We follow a previous work done on this topic by Ralph
[H. I. Ralph, Philips Res. Rept. 32 160 (1977)] to account for the p-wave
nature and the coupling of valence band states. We extend Ralph's analysis to
incorporate finite-range potentials in the scattering problem. We find that the
variable phase method provides a very convenient framework for our purposes and
show in detail how scattering amplitudes and phase shifts are obtained. The
Green's matrix of the Schroedinger equation, the Lippmann-Schwinger equation
and the Born approximation are also discussed. Examples are provided to
illustrate our calculations with Yukawa type potentials.Comment: 16 pages and 9 figure
Formation of the X-ray line emission spectrum of excimer laser-produced plasmas
Time- and space-integrated emission spectra measurements have been performed in plasma produced by 308 nm wavelength XeCl laser radiation (IL = (4–10)·1012 W/cm2, τ = 10 ns) and by 248 nm wavelength KrF laser pulse train radiation (IL = 5·1015 W/cm2, τ = 7 ps, 16 pulses in train) on CF2 plane target. Theoretical modelling of Lyman series and He-like ion resonance series of fluorine and its fit of experimental data show considerable differences in the absorption of laser radiation in the two plasmas
Impact of Chronic Lung Disease on Very Low Birth Weight infants: a collaborative study of the Italian Group of Neonatal Pneumology
Objective. To evaluate the incidence and risk factors for chronic lung disease in a population
of very low birth weight infants.
Methods. In a prospective multicentric trial all very low birth weight infants (< 1500 g)
accepted in 36 Italian Neonatal Intensive care units were studied from February 89 to
January 99. For each patient were recorded maternal history, perinatal events, respiratory
disease, infections, patent ductus arteriosus, retinopathy of prematurity, intraventricular
haemorrhage and final outcome. Logistic regression analysis was performed in
a multivariate assessment of risk factors for chronic lung disease.
Results. In the study were included 1634 patients: 1387 infants survived beyond 36
weeks and 6.9% of them still oxygen dependent.
The incidence of chronic lung disease was higher among babies with a gestational age
of < 28 weeks and weight \ub2 1000 g. The multivariate analysis showed that low birth
weight, respiratory distress syndrome, persistent ductus arteriosus and sepsis were the
main risk factors.
Conclusions. In our study the incidence of chronic lung disease was relatively lo
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