21,643 research outputs found
Spherical Hartree-Fock calculations with linear momentum projection before the variation.Part II: Spectral functions and spectroscopic factors
The hole--spectral functions and from these the spectroscopic factors have
been calculated in an Galilei--invariant way for the ground state wave
functions resulting from spherical Hartree--Fock calculations with projection
onto zero total linear momentum before the variation for the nuclei 4He, 12C,
16O, 28Si, 32S and 40Ca. The results are compared to those of the conventional
approach which uses the ground states resulting from usual spherical
Hartree--Fock calculations subtracting the kinetic energy of the center of mass
motion before the variation and to the results obtained analytically with
oscillator occupations.Comment: 16 pages, 22 postscript figure
Spherical Hartree-Fock calculations with linear momentum projection before the variation.Part I: Energies, form factors, charge densities and mathematical sum rules
Spherical Hartree--Fock calculations with projection onto zero total linear
momentum before the variation are performed for the nuclei 4He, 12C, 16O, 28Si,
32S and 40Ca using a density--independent effective nucleon--nucleon
interaction. The results are compared to those of usual spherical Hartree--Fock
calculations subtracting the kinetic energy of the center of mass motion either
before or after the variation and to the results obtained analytically with
oscillator occupations. Total energies, hole--energies, elastic charge form
factors and charge densities and the mathematical Coulomb sum rules are
discussed.Comment: 16 pages, 13 postscript figure
Spectral Estimates and Non-Selfadjoint Perturbations of Spheroidal Wave Operators
We derive a spectral representation for the oblate spheroidal wave operator
which is holomorphic in the aspherical parameter in a neighborhood of
the real line. For real , estimates are derived for all eigenvalue gaps
uniformly in .
The proof of the gap estimates is based on detailed estimates for complex
solutions of the Riccati equation. The spectral representation for complex
is derived using the theory of slightly non-selfadjoint perturbations.Comment: 33 pages, LaTeX, 3 figures, typo in Lemma 4.1 corrected (published
version
Ā« Implication des facteurs respectifs du donneur et du receveur dans l'eĢvolution aĢ court (30 jours) et aĢ moyen termes (1 an) de la transplantation pulmonaire. Etude reĢtrospective de 2004-2011 Ā»
Contexte: La transplantation pulmonaire est maintenant un traitement eĢtabli pour les patients au stade terminal de maladies pulmonaires chroniques. La disponibiliteĢ des poumons de donneurs approprieĢs est la cause d'un rationnement explicite limitant le nombre de transplantations possibles chez les patients au stade terminal des maladies pulmonaires et la liste d'attente des patients en attente de greffe s'allonge. C'est pourquoi, dans de nombreux centres de transplantation, l'utilisation des poumons marginaux est de plus en plus consideĢreĢe. Le but de ce travail de maitrise eĢtait d'analyser l'implication des facteurs respectifs du donneur et du receveur dans l'eĢvolution aĢ court (30 jours) et aĢ moyen termes (1 an) de la transplantation pulmonaire et d'identifier quelques parameĢtres cliniques pertinents impliqueĢs dans l'eĢvolution des 30 premiers jours et 1 anneĢe apreĢs une transplantation pulmonaire.
MeĢthodes : Le travail repreĢsente l'eĢtude reĢtrospective de 119 patients qui ont beĢneĢficieĢ d'une transplantation pulmonaire au CHUV dans le centre universitaire romand de transplantation durant la peĢriode du 18 Juin 2004 au 26 DeĢcembre 2011. Les parameĢtres suivants ont eĢteĢ choisis comme criteĢres principaux d'eĢvaluation : la survie aĢ court terme (30 jours), la survie aĢ moyen terme (1 anneĢe), la dureĢe de seĢjour aux soins intensifs, la dureĢe d'hospitalisation totale ainsi que la neĢcessiteĢ de theĢrapie de remplacement reĢnal (heĢmodialyse ou heĢmofiltration) pendant les premiers 30 jours apreĢs la transplantation pulmonaire. Les variables suggeĢreĢes significatives par l'analyse univarieĢe ont eĢteĢ incluses dans le modeĢle multivarieĢ de reĢgression logistique. Une valeur p de < 0,05 a eĢteĢ consideĢreĢe comme statistiquement significative.
ReĢsultats : La survie aĢ 30 jours eĢtait de 93.2% et de 86.4% aĢ 1 anneĢe. La TRR a eĢteĢ utiliseĢe chez 11.2% de patients transplanteĢs durant les 30 premiers jours apreĢs l'intervention. Le recours aĢ la CEC peropeĢratoire a eĢteĢ identifieĢ comme un preĢdicteur indeĢpendant pour la survie aĢ 30 jours (95%CI (-5.05)-(-0.5) ; SE=1.14), pour la dureĢe de seĢjour aux soins intensifs (95% CI 0.64-2.77; SE=0.54), ainsi que pour la neĢcessiteĢ de theĢrapie de remplacement reĢnale durant le premier mois (95% CI 0.73-3.5 ; SE=0.72). Pour la survie aĢ moyen terme (1 an), le temps d'ischeĢmie maximale du poumon (95%CI (-0.02)-(-0.006) ; SE=0.005) a eĢteĢ identifieĢ comme le facteur preĢdictif indeĢpendant. Concernant la dureĢe totale de l'hospitalisation, 4 facteurs preĢdictifs indeĢpendants ont eĢteĢ identifieĢs, aĢ savoir la preĢsence d'une CEC (95% CI, 0.1-2.51 ; SE=0.61), la valeur de PaO2/FiO2 24 heures apreĢs la transplantation (95% CI (-0.41)-(-0.03) ; SE=0.09), le BMI du receveur (95% CI, 3.37-16.93; SE=3.45) ainsi que la preĢsence d'une Rx du thorax sans leĢsions chez le donneur (95% CI (- 2.38)-0.18) ; SE=0.56).
Conclusion: Dans notre eĢtude reĢtrospective monocentrique de 118 transplantations pulmonaires, nous avons identifieĢ que le recours aĢ la circulation extracorporelle (CEC) en peropeĢratoire, le temps d'ischeĢmie prolongeĢ, le BMI du receveur et le rapport PaO2/FiO2 aĢ 24 heures apreĢs l'intervention eĢtaient tous correĢleĢs avec des outcomes deĢfavorables, soit en termes de mortaliteĢ ou de morbiditeĢ. Ces parameĢtres sont concordants avec ceux deĢcrits dans la litteĢrature, et sont probablement des marqueurs de la seĢveĢriteĢ de l'atteinte du receveur. A relever qu'aucun parameĢtre concernant le donneur n'est correĢleĢ avec la survie post opeĢratoire
On the mechanism of trailing vortex wandering
The mechanism of trailing vortex wandering has long been debated and is often attributed to either wind-tunnel effects or an instability. Using particle image velocimetry data obtained in the wake of a NACA0012 airfoil, we remove the effect of wandering from the measured velocity field and, through a triple decomposition, recover the coherent wandering motion. Based on this wandering motion, the most energetic structures are computed using the proper orthogonal decomposition (POD) and exhibit a helical mode with an azimuthal wavenumber of |m|=1 whose kinetic energy grows monotonically in the downstream direction. To investigate the nature of the vortex wandering, we perform a spatial stability analysis of a matched Batchelor vortex. The primary stability mode is found to be marginally stable and nearly identical in both size and structure to the leading POD mode. The strikingly similar structure, coupled with the measured energy growth, supports the proposition that the vortex wandering is the result of an instability. We conclude that the cause of the wandering is the non-zero radial velocity of the |m|=1 mode on the vortex centreline, which acts to transversely displace the trailing vortex, as observed in experiments. However, the marginal nature of the stability mode prevents a definitive conclusion regarding the specific type of instability
Effect of long range forces on the interfacial profiles in thin binary polymer films
We study the effect of surface fields on the interfacial properties of a
binary polymer melt confined between two parallel walls. Each wall attracts a
different component of the blend by a non-retarded van der Waals potential. An
interface which runs parallel to the surfaces is stabilized in the center of
the film. Using extensive Monte Carlo simulations we study the interfacial
properties as a function of the film thickness, the strength of the surface
forces and the lateral size over which the profiles across the film are
averaged. We find evidence for capillary wave broadening of the apparent
interfacial profiles. However, the apparent interfacial width cannot be
described quantitatively by a simple logarithmic dependence on the film
thickness. The Monte Carlo simulations reveal that the surface fields give rise
to an additional reduction of the intrinsic interfacial width and an increase
of the effective interfacial tension upon decreasing the film thickness. These
modifications of the intrinsic interfacial properties are confirmed by
self-consistent field calculations. Taking account of the thickness dependence
of the intrinsic interfacial properties and the capillary wave broadening, we
can describe our simulation results quantitatively.Comment: to appear in J.Chem.Phy
Detectable inertial effects on Brownian transport through narrow pores
We investigate the transport of suspended Brownian particles dc driven along
corrugated narrow channels in a regime of finite damping. We demonstrate that
inertial corrections cannot be neglected as long as the width of the channel
bottlenecks is smaller than an appropriate particle diffusion length, which
depends on both, the temperature and the strength of the dc drive. Therefore,
transport through sufficiently narrow constrictions turns out to be sensitive
to the viscosity of the suspension fluid. Applications to colloidal systems are
discussed
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