Microscopic and non-adiabatic Schr\"odinger equation derived from the Generator Coordinate Method based on 0 and 2 quasiparticle HFB states

A new approach called the Schr\"odinger Collective Intrinsic Model (SCIM) has been developed to achieve a microscopic description of the coupling between collective and intrinsic excitations. The derivation of the SCIM proceeds in two steps. The first step is based on a generalization of the symmetric moment expansion of the equations derived in the framework of the Generator Coordinate Method (GCM), when both Hartree-Fock-Bogoliubov (HFB) states and two-quasi-particle excitations are taken into account as basis states. The second step consists in reducing the generalized Hill and Wheeler equation to a simpler form to extract a Schr\"odinger-like equation. The validity of the approach is discussed by means of results obtained for the overlap kernel between HFB states and two-quasi-particle excitations at different deformations.Comment: 27 pages, 12 figures, submitted to Phys. Rev.

Aliasing phenomenon due to CCD sensors

This article deals with the aliasing phenomenon due to CCD sensors . Those detectors inherently carry out a sampling and a low pass filtering process . We propose a superresolution technique reducing aliasing, and allowing a deconvolution over an extended spectral support to diminish the low pass filtering of CCD cells . This method improves the two restricting factors (low pass filtering and perturbation of low frequencies by folded high frequencies) inherent to this type of detector .Nous montrons dans cet article l'importance du repliement spectral lié à l'utilisation des détecteurs constitués de cellules CCD . Pour cela nous rappelons l'effet sur son spectre de l'échantillonnage et du lissage d'un signal ; ce sont les deux particularités de ces capteurs . Nous proposons une méthode de superrésolution qui réduit l'effet du repliement spectral, et qui permet de déconvoluer le signal sur un support spectral plus étendu afin de diminuer l'effet de lissage des cellules CCD . La méthode proposée permet donc d'améliorer les deux facteurs limitatifs (filtrage passe bas et perturbation de ces basses fréquences par les hautes fréquences) liés à la nature même de ce type de détecteur

Ground state correlations and mean-field in 16^{16}O

We use the coupled cluster expansion ($\exp(S)$ method) to generate the complete ground state correlations due to the NN interaction. Part of this procedure is the calculation of the two-body G matrix inside the nucleus in which it is being used. This formalism is being applied to $^{16}O$ in a configuration space of 50 $\hbar\omega$. The resulting ground state wave function is used to calculate the binding energy and one- and two-body densities for the ground state of $^{16}O$.Comment: 9 pages, 9 figures, LaTe

Description of a three-dimensional deconvolution reconstruction algorithm from cone beam projection

This paper presents the discretization and the application of a 3D reconstruction method front cone beam X-ray projections . The generalized back projection theorem, established in a previous work, is the theoretical basis for the method. It allows to reduce the reconstruction problem to a 3D deconvolution problem . The proposed algorithm essentially consists in two steps : (i) computation of the discrete corrected back projection of all the cone beam projections ; (ii) deconvolution of the result . After vectorization, this algorithm has been implemented on a CDC CYBER 205 computer. A simple and comprehensive test function is proposed to evaluate the algorithm relatively to various error criteria . The first simulations show that the reconstruction results are very satisfying when the X-ray sources are located in the whole space around the object, in accordance with the theory (4 it geometry). Furthermore, even in poor acquisition conditions the algorithm seems to give a first approximation of the object which can be sufficient to study its morphological aspect .Cet article présente la discrétisation et la mise en oeuvre d'une méthode de reconstruction 3D à partir de projections coniques . Le théorème de la rétroprojection, établi dans un travail précédent, est la base théorique de la méthode. Il permet de ramener le problème de reconstruction à un problème de déconvolution 3D. L'algorithme proposé comporte essentiellement deux étapes, consistant tout d'abord à calculer une rétroprojection corrigée des projections coniques, puis à déconvoluer le résultat obtenu. Cet algorithme a été implanté sur le CYBER 205 de Control Data après avoir été complètement vectorisé . Un exemple simple de simulation et différents critères d'écarts sont proposés pour l'évaluer . Les premières simulations montrent que les résultats obtenus sont très satisfaisants si les sources sont réparties dans l'espace tout autour de l'objet (géométie 4 7t) . De plus, même dans des conditions d'acquisition assez défavorables, l'algorithme semble donner une première approximation de l'objet qui peut être suffisante pour étudier son aspect morphologique

Etude comparative de méthodes de restauration d'images dans le cas d'un modèle de dégradation spatialement variant

Nous proposons une comparaison des méthodes de : Tikhonov-Miller, Tikhonov-Miller avec modèle a priori de la solution, Markov et Maximum d'Entropie, dans le cas d'un système de dégradation spatialement variant. L'approximation du modèle variant par un modèle invariant est précisée. Il est montré que le choix d'une méthode de restauration sera fonction du type d'information a priori disponible et des caractéristiques de la PSF (Point Spread Function). Dans le cas de l'imagerie par sténopé, il est indispensable de prendre en compte la variabilité spatiale

Role of deformation on giant resonances within the QRPA approach and the Gogny force

Fully consistent axially-symmetric-deformed Quasi-particle Random Phase Approximation (QRPA) calculations have been performed, in which the same Gogny D1S effective force has been used for both the Hartree-Fock-Bogolyubov mean field and the QRPA approaches. Giant resonances calculated in deformed $^{26-28}$Si and $^{22-24}$Mg nuclei as well as in the spherical $^{30}$Si and $^{28}$Mg isotopes are presented. Theoretical results for isovector-dipole and isoscalar monopole, quadrupole, and octupole responses are presented and the impact of the intrinsic nuclear deformation is discussed.Comment: 12 pages, 6 figures and 4 tables, accepted in PR

Local spatial-frequency analysis of images using Wigner-Ville distribution

Local spectrum analysis is an interesting method to extract pertinent features of an image . This paper proposes a new local spectrum analysis method allowing to accurately characterize the local spatial frequency content of an image. It is based on the use of the two-dimensional Wigner-Ville distribution (2D WVD), which permits to separately control spatial and frequential analysis resolutions. The application of this method to texture feature extraction and discrimination is illustrated, and a comparison with the classical 2D spectrogram method is also given.L'analyse spectrale locale est une méthode intéressante pour obtenir des caractéristiques pertinentes d'une image. Cet article propose une nouvelle méthode d'analyse spectrale locale permettant de caractériser de manière précise les propriétés fréquentielles locales d'une image. Cette méthode est basée sur la transformation de Wigner-Ville bidimensionnelle (TWV 2D), qui permet de contrôler, de façon souple, séparement les résolutions spatiale et fréquentielle. L'application de cette technique à la caractérisation d'images de textures est illustrée, et une comparaison de sa performance par rapport à la méthode classique de spectrogramme 2D est également montré

Magnetic Moment of the Fragmentation Aligned 61Fe(9/2)+ Isomer

We report on the g factor measurement of the isomer in $^{61}Fe$ ($E^{*}=861 keV$). The isomer was produced and spin-aligned via a projectile-fragmentation reaction at intermediate energy, the Time Dependent Perturbed Angular Distribution (TDPAD) method being used for the measurement of the g factor. For the first time, due to significant improvements of the experimental technique, an appreciable residual alignment of the isomer has been observed, allowing a precise determination of its g factor: $g=-0.229(2)$. Comparison of the experimental g factor with shell-model and mean field calculations confirms the $9/2^+$ spin and parity assignments and suggests the onset of deformation due to the intrusion of Nilsson orbitals emerging from the $\nu g_{9/2}$.Comment: 4 figures. Submitted to Phys. Rev. Let

The continuing evolution of Energy Policy

As the world confronts the Covid-19 pandemic, we hope that all of you are doing well. We know that many lives have been greatly disrupted, and that world economic activity is slowing and maybe declining in some places. We have read reports that energy consumption has been greatly affected by the slowdown in world economic activity—likely contributing to the sharp plunge in oil prices earlier this year. We do not know how long this pandemic may last. As we look forward to the end of the pandemic and a recovering world economy, however, we wonder if and how energy systems may have to be transformed, and whether new energy policy needs and approaches will emerge. Will we see any change in the trajectory of adopting sustainable energy systems and reducing carbon emissions?In the academic world, many of us are now teleworking and teaching our courses online. This transition has proved time consuming—so we want to thank our many reviewers who are staying on or close to schedule. So far, Energy Policy has been mostly unaffected by the pandemic, but we must recognize that the Elsevier employees who are responsible for the operations side of the journal may at some time be affected by Covid-19.In the meantime, we want to keep you informed about some recent developments regarding Energy Policy, including a little about its history and our editorial priorities

Quality control of MATa1 splicing and exon skipping by nuclear RNA degradation

The MATa1 gene encodes a transcriptional repressor that is an important modulator of sex-specific gene expression in Saccharomyces cerevisiae. MATa1 contains two small introns, both of which need to be accurately excised for proper expression of a functional MATa1 product and to avoid production of aberrant forms of the repressor. Here, we show that unspliced and partially spliced forms of the MATa1 mRNA are degraded by the nuclear exonuclease Rat1p, the nuclear exosome and by the nuclear RNase III endonuclease Rnt1p to prevent undesired expression of non-functional a1 proteins. In addition, we show that mis-spliced forms of MATa1 in which the splicing machinery has skipped exon2 and generated exon1–exon3 products are degraded by the nuclear 5′–3′ exonuclease Rat1p and by the nuclear exosome. This function for Rat1p and the nuclear exosome in the degradation of exon-skipped products is also observed for three other genes that contain two introns (DYN2, SUS1, YOS1), identifying a novel nuclear quality control pathway for aberrantly spliced RNAs that have skipped exons