The electronic spectra of protonated PANH molecules

Aims. This study was designed to examine the viability of protonated nitrogen-substituted polycyclic aromatic hydrocarbons (H+PANHs) as candidates for the carriers of the diffuse interstellar bands (DIBs). Methods. We obtained the electronic spectra of two protonated PANH cations, protonated acridine and phenanthridine, using parent ion photo-fragment spectroscopy and generated theoretical electronic spectra using ab initio calculations. Results. We show that the spectra of the two species studied here do not correspond to known DIBs. However, based on the general properties derived from the spectra of these small protonated nitrogen-substituted PAHs, we propose that larger H+PANH cations represent good candidates for DIB carriers due to the expected positions of their electronic transitions in the UV-visible and their narrow spectral bands.Comment: 7 pages, 2 figures, accepted for publication in A&

An adaptive Newton multigrid method for a model of marine ice sheets

In this paper, we consider a model for the time evolution of three-dimensional marine ice sheets. This model combines the Shallow Ice Approximation (SIA) for the ice deformation, the Shallow Shelf Approximation (SSA) for the basal sliding, and the mass conservation principle. At each time step, we solve a scalar p-Laplace minimization-type problem with obstacle (SIA), a vectorial p-Laplace minimization-type problem (SSA) and a transport equation (mass conservation). The two minimization problems are solved using a truncated nonsmooth Newton multigrid method while the transport equation is solved using a vertex-centred finite volume method. Our approach is combined to an heuristic mesh adaptive refinement procedure to face the large gradients of the solution that are expected between the ice sheet and the ice shelf. As applications, we present some simulations of the Marine Ice Sheet Model Intercomparison Project MISMIP (2D and 3D) and validate our results against an analytic solution (2D) and other participant model results (3D). Further numerical results show that the convergence of our Newton multigrid method is insensitive to local refinements making our overall adaptive strategy fully efficient

A nonsmooth Newton multigrid method for a hybrid, shallow model of marine ice sheets

The time evolution of ice sheets and ice shelves is model by combining a shallow lubrication approximation for shear deformation with the shallow shelf approximation for basal sliding, along with the mass conservation principle. At each time step two p-Laplace problems and one transport problem are solved. Both p-Laplace problems are formulated as minimisation problems. They are approximated by a finite element truncated nonsmooth Newton multigrid method. As an illustration, we compute the steady state shape of an idealized ice sheet/shelf system

Numerical analysis and simulation of the dynamics of mountain glaciers

In this chapter, we analyze and approximate a nonlinear stationary Stokes problem that describes the motion of glacier ice. The existence and uniqueness of solutions are proved and an a priori error estimate for the finite element approximation is found. In a second time, we combine the Stokes problem with a transport equation for the volume fraction of ice, which describes the time evolution of a glacier. The accumulation due to snow precipitation and melting are accounted for in the source term of the transport equation. A decoupling algorithm allows the diffusion and the advection problems to be solved using a two-grids method. As an illustration, we simulate the evolution of Aletsch glacier, Switzerland, over the 21st century by using realistic climatic conditions

Speech recognition and statistical approach : CNET's experience

This paper presents the work done at the CNET in speech recognition during the last few years. The authors present the recent generation of speaker-independent systems, based on statistical modeling using the Markov models (PHIL86 software) . Several applications of these systems in the Telecommunications area are described, as well as the lessons drawn front them .Cet article décrit les travaux menés au CNET ces dernières années, dans le domaine de la reconnaissance de la parole. Après avoir rappelé le contexte de cette recherche, on décrit le logiciel PHIL86 destiné à reconnaître des vocabulaires de petite taille, indépendamment du locuteur, et les développements matériels qui lui ont été associés . Deux expérimentations de la reconnaissance dans - le domaine des Télécommunications sont ensuite présentées, en insistant principalement sur les enseignements qui en ont été tirés et les résultats des évaluations menées sur le terrain

Analyses spectroscopiques du liquide céphalo-rachidien de rat en ex vivo et du noyau du raphé dorsal in vivo

Les propriétés d'absorption et de fluorescence du liquide céphalo-rachidien (LCR) ponctionné au niveau de la cisterna magna du rat, sont analysées puis comparées à l'émission mesurée in situ dans le noyau du raphe dorsal du rat libre de tous mouvements. Les mesures de fluorescence en ex vivo du LCR et in vivo du noyau raphé dorsal, ont été réalisées par la mise en œuvre d'un microcapteur à fibre optique (FOCS). La fluorescence mesurée in vivo sous excitation à 337 nm, présente 2 pics d'émission situés vers 410 et 460 nm. Les spectres d'absorption, d'émission en fluorescence statique et en fluorescence induite par laser sont rapportés. Avec des domaines de longueur d'onde d'excitation de 300-315 nm, 320-355 nm et 360-470 nm, les spectres d'émission du LCR en ex vivo montrent respectivement des pics centrés vers 340 nm, 390 nm et 530 nm. Malgré les limites liées aux différences de localisation anatomique, ces approches ainsi que celles de la littérature permettent de suggérer que le signal de fluorescence mesuré in vivo à 460nm pourrait dépendre pour une grande partie du NADH intracellulaire

Excited state hydrogen transfer dynamics in substituted phenols and their complexes with ammonia: π π * -π σ*energy gap propensity and ortho-substitution effect

Lifetimes of the first electronic excited state (S1) of fluorine and methyl (o-, m-, and p-) substituted phenols and their complexes with one ammonia molecule have been measured for the 00 transition and for the intermolecular stretching σ1 levels in complexes using picosecond pump-probe spectroscopy. Excitation energies to the S1 (π π *) and S2 (π σ*) states are obtained by quantum chemical calculations at the MP2 and CC2 level using the aug-cc-pVDZ basis set for the ground-state and the S1 optimized geometries. The observed lifetimes and the energy gaps between the π π * and π σ* states show a good correlation, the lifetime being shorter for a smaller energy gap. This propensity suggests that the major dynamics in the excited state concerns an excited state hydrogen detachment or transfer (ESHD/T) promoted directly by a S1 / S2 conical intersection, rather than via internal conversion to the ground-state. A specific shortening of lifetime is found in the o-fluorophenol-ammonia complex and explained in terms of the vibronic coupling between the π π * and π σ* states occurring through the out-of-plane distortion of the C-F bond.Fil: Pino, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Oldani, Andres Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Marceca, Ernesto José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Fujii, M.. Tokyo Institute of Technology; JapónFil: Ishiuchi, S.-I.. Tokyo Institute of Technology; JapónFil: Miyazaki, M.. Tokyo Institute of Technology; JapónFil: Broquier, M.. Centre National de la Recherche Scientifique; Francia. Universite Paris-Saclay;Fil: Dedonder, C.. Centre National de la Recherche Scientifique; Francia. Universite Paris-Saclay;Fil: Jouvet, C.. Universite Paris-Saclay; . Centre National de la Recherche Scientifique; Franci

One-Parameter GHG Emission Policy with R&D-based Growth

This document examines the GHG emission policy of regions which use land, labor and emitting inputs in production and enhance their productivity by devoting labor to R&D, but with different endowments and technology. The regions also have different impacts on global pollution. The problem is to organize common emission policy, if the regions cannot form a federation with a common budget and the policy parameters must be uniform for all regions. The results are the following. If a self-interested central planner allocate emission caps in fixed proportion to past emissions (i.e. grandfathering), then it establishes the Pareto optimum, decreasing emissions and promoting R&D and economic growth

The 2007 WHO Classification of Tumours of the Central Nervous System

The fourth edition of the World Health Organization (WHO) classification of tumours of the central nervous system, published in 2007, lists several new entities, including angiocentric glioma, papillary glioneuronal tumour, rosette-forming glioneuronal tumour of the fourth ventricle, papillary tumour of the pineal region, pituicytoma and spindle cell oncocytoma of the adenohypophysis. Histological variants were added if there was evidence of a different age distribution, location, genetic profile or clinical behaviour; these included pilomyxoid astrocytoma, anaplastic medulloblastoma and medulloblastoma with extensive nodularity. The WHO grading scheme and the sections on genetic profiles were updated and the rhabdoid tumour predisposition syndrome was added to the list of familial tumour syndromes typically involving the nervous system. As in the previous, 2000 edition of the WHO ‘Blue Book’, the classification is accompanied by a concise commentary on clinico-pathological characteristics of each tumour type. The 2007 WHO classification is based on the consensus of an international Working Group of 25 pathologists and geneticists, as well as contributions from more than 70 international experts overall, and is presented as the standard for the definition of brain tumours to the clinical oncology and cancer research communities world-wide