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

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

Il restauro dei dipinti 'olio su tela'

Il testo condensa la lunga ed eterogenea attivit\ue0 didattica relativa all\u2019argomento, innanzitutto quella svolta dai tre autori, a vario titolo, presso l\u2019Universit\ue0 di Bologna. Molte affermazioni, cos\u2019 come tutta l\u2019iconografia, derivano direttamente dalla poliedrica e trentennale attivit\ue0 dello \u201cStudio di Restauro G.M.Costanini\u201d. nel tempo, cambiano i materiali e le tecniche di restauro, ma ci\uf2 che dovrebbe rimanere saldo per chi \ue8 coinvolto in problemi di restauro \ue8 la capacit\ue0 di una lettura sistematica dell\u2019opera d\u2019arte e del suo stato di conservazione e la possibilit\ue0 di elaborare o valutare gli interventi adatti per rallentare l\u2019inevitabile 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\u2019approccio al restauro di altre categorie di opere d\u2019arte

Effect of laser irradiation on yeast fermentation in presence of dicarboxylic and tricarboxylic acids

Effect of laser irradiation on yeast fermentation in presence of dicarboxylic and tricarboxylic acid