8,691 research outputs found
A general resonance theory based on Mourre's inequality
We study the perturbation of bound states embedded in the continuous spectrum
which are unstable by the Fermi Golden Rule. The approach to resonance theory
based on spectral deformation is extended to a more general class of quantum
systems characterized by Mourre's inequality and smoothness of the resolvent.
Within the framework of perturbation theory it is still possible to give a
definite meaning to the notion of complex resonance energies and of
corresponding metastable states. The main result is a quasi-exponential decay
estimate up to a controlled error of higher order in perturbation theory.Comment: 17 page
Analyse de la qualité de vie dans le cadre d'une étude prospective randomisée sur le prélèvement des ganglions sentinelle dans les cancers du col de l'utérus.
Objectif: Le cancer du col utérin reste un problème très actuel avec une grande prévalence et mortalité à travers le monde. Ce cancer est à dissémination lymphatique préférentielle, et l'existence de métastases ganglionnaires est le facteur pronostique le plus important dans les stades précoces. Jusqu'à présent la prise en charge de patientes avec un stade débutant reposait sur la lymphadénectomie pelvienne complète, technique qui entraine une importante morbidité per et post opératoire, et n'est utile que seulement pour les femmes avec des métastases ganglionnaires. Le concept du ganglion sentinelle est une méthode diagnostique qui permet d'identifier la présence ou l'absence de la tumeur au niveau du premier relais ganglionnaire lymphatique et par conséquence estimer le risque de métastase ganglionnaire régionale. Ainsi, en cas d'absence de cellules cancéreuses dans les ganglions sentinelles, on pourrait se dispenser d'un curage régional complet. Ce travail compare la technique du ganglion sentinelle seul par rapport à une lymphadénectomie pelvienne complète du point de vue des complications et de la qualité de vie qui résultent de la prise en charge thérapeutique.
Méthodologie : Il s'agit d'une étude prospective, contrôlée, randomisée, ouverte, en groupes parallèles. 206 patientes avec un stade débutant de cancer du col de l'utérus ayant bénéficié d'une recherche du ganglion sentinelle et provenant de 23 centres investigateurs en France sont randomisées en deux groupes (avec ou sans lymphadénectomie pelvienne complète). Chaque patiente est suivie du point de vue des complications per et post opératoires et remplit un questionnaire de qualité de vie (SF36) avant le traitement puis 1 mois, 3 mois et 6 mois après. Une analyse quantitative des questionnaires est réalisée et les résultats sont comparés entre les 2 bras de randomisation en tenant compte des biais.
Résultats : 267 patientes ont étés enrôlées, et 206 patientes ont étés randomisées en 2 bras. 105 dans le bras test (sans lymphadénectomie), 101 dans le bras contrôle (avec lymphadénectomie). Les deux groups sont comparables pour les données des patientes, les caractéristiques tumorales et les traitements complémentaires. Un biais de répartition pour les items de « santé perçue » et de « vie et relations » a été mis en évidence avant la chirurgie. Les items d'« activité physique », « santé psychique » et le « score résumé psychique » sont significativement différents entre les deux groupes après la chirurgie en faveur du bras test. Les scores des deux bras suivent la même évolution dans le temps.
Conclusions : La technique du ganglion sentinelle améliore la qualité de vie à court terme des patientes avec un cancer du col de l'utérus de stade débutant, en particulier dans les domaines de l'activité physique et la santé psychique. Ce gain reste à vérifier sur le long terme
The Relative Space: Space Measurements on a Rotating Platform
We introduce here the concept of relative space, an extended 3-space which is
recognized as the only space having an operational meaning in the study of the
space geometry of a rotating disk. Accordingly, we illustrate how space
measurements are performed in the relative space, and we show that an old-aged
puzzling problem, that is the Ehrenfest's paradox, is explained in this purely
relativistic context. Furthermore, we illustrate the kinematical origin of the
tangential dilation which is responsible for the solution of the Ehrenfest's
paradox.Comment: 14 pages, 2 EPS figures, LaTeX, to appear in the European Journal of
Physic
Hawking Radiation as Tunneling: the D-dimensional rotating case
The tunneling method for the Hawking radiation is revisited and applied to
the dimensional rotating case. Emphasis is given to covariance of results.
Certain ambiguities afflicting the procedure are resolved.Comment: Talk delivered at the Seventh International Workshop Quantum Field
Theory under the influence of External Conditions, QFEXT'05, september
05,Barcelona, Spain. To appear in Journal of Phys.
Classical BV theories on manifolds with boundary
In this paper we extend the classical BV framework to gauge theories on
spacetime manifolds with boundary. In particular, we connect the BV
construction in the bulk with the BFV construction on the boundary and we
develop its extension to strata of higher codimension in the case of manifolds
with corners. We present several examples including electrodynamics, Yang-Mills
theory and topological field theories coming from the AKSZ construction, in
particular, the Chern-Simons theory, the theory, and the Poisson sigma
model. This paper is the first step towards developing the perturbative
quantization of such theories on manifolds with boundary in a way consistent
with gluing.Comment: The second version has many typos corrected, references added. Some
typos are probably still there, in particular, signs in examples. In the
third version more typoes are corrected and the exposition is slightly
change
Is AGN feedback necessary to form red elliptical galaxies?
We have used GADGET2 to simulate the formation of an elliptical galaxy in a
cosmological dark matter halo with mass 3x10^12M_Sun/h. Using a stellar
population synthesis model has allowed us to compute magnitudes, colours and
surface brightness profiles. We have included a model to follow the growth of a
central black hole and we have compared the results of simulations with and
without feedback from AGNs. We have studied the interplay between cold gas
accretion and merging in the development of galactic morphologies, the link
between colour and morphology evolution, the effect of AGN feedback on the
photometry of early type galaxies, the redshift evolution in the properties of
quasar hosts, and the impact of AGN winds on the chemical enrichment of the
intergalactic medium (IGM). We have found that the early phases of galaxy
formation are driven by the accretion of cold filamentary flows, which form a
disc at the centre of the dark matter halo. When the dark matter halo is
sufficiently massive to support the propagation of a stable shock, cold
accretion is shut down, and the star formation rate begins to decline. Mergers
transform the disc into an elliptical galaxy, but also bring gas into the
galaxy. Without a mechanism that removes gas from the merger remnants, the
galaxy ends up with blue colours, atypical for its elliptical morphology. AGN
feedback can solve this problem even with a fairly low heating efficiency. We
have also demonstrated that AGN winds are potentially important for the metal
enrichment of the IGM a high redshift.(abridged)Comment: 19 pages and 17 figures, accepted to MNRAS ID: MN-07-1954-MJ.R1 . For
high resolution images please check following link:
http://www.aip.de/People/AKhalatyan/COSMOLOGY/BHCOSMO
Microscopic Derivation of Causal Diffusion Equation using Projection Operator Method
We derive a coarse-grained equation of motion of a number density by applying
the projection operator method to a non-relativistic model. The derived
equation is an integrodifferential equation and contains the memory effect. The
equation is consistent with causality and the sum rule associated with the
number conservation in the low momentum limit, in contrast to usual acausal
diffusion equations given by using the Fick's law. After employing the Markov
approximation, we find that the equation has the similar form to the causal
diffusion equation. Our result suggests that current-current correlations are
not necessarily adequate as the definition of diffusion constants.Comment: 10 pages, 1 figure, Final version published in Phys. Rev.
Symplectic Microgeometry II: Generating functions
We adapt the notion of generating functions for lagrangian submanifolds to
symplectic microgeometry. We show that a symplectic micromorphism always admits
a global generating function. As an application, we describe hamiltonian flows
as special symplectic micromorphisms whose local generating functions are the
solutions of Hamilton-Jacobi equations. We obtain a purely categorical
formulation of the temporal evolution in classical mechanics.Comment: 27 pages, 1 figur
Bimodal AGNs in Bimodal Galaxies
By their star content, the galaxies split out into a red and a blue
population; their color index peaked around u-r=2.5 or u-r=1, respectively,
quantifies the ratio of the blue stars newly formed from cold galactic gas, to
the redder ones left over by past generations. On the other hand, upon
accreting substantial gas amounts the central massive black holes energize
active galactic nuclei (AGNs); here we investigate whether these show a
similar, and possibly related, bimodal partition as for current accretion
activity relative to the past. To this aim we use an updated semianalytic
model; based on Monte Carlo simulations, this follows with a large statistics
the galaxy assemblage, the star generations and the black hole accretions in
the cosmological framework over the redshift span from z=10 to z=0. We test our
simulations for yielding in close detail the observed split of galaxies into a
red, early and a blue, late population. We find that the black hole accretion
activities likewise give rise to two source populations: early, bright quasars
and later, dimmer AGNs. We predict for their Eddington parameter --
the ratio of the current to the past black hole accretions -- a bimodal
distribution; the two branches sit now under (mainly
contributed by low-luminosity AGNs) and around . These
not only mark out the two populations of AGNs, but also will turn out to
correlate strongly with the red or blue color of their host galaxies.Comment: 7 pages, accepted for publication in the Astrophysical Journa
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