168 research outputs found
CO16 270. Anillo Asimétrico IMR Para la Corrección de la Insuficiencia Mitral Isquémica
Introducciónla insuficiencia mitral (IM) isquémica secundaria a alteraciones segmentarias de la contracción del ventrículo izquierdo (VI) es debida a una restricción de la movilidad de los velos en sístole (tipo IIIb de Carpentier), impidiendo una correcta coaptación.Se han descrito múltiples técnicas para su corrección, pero un número significativo de pacientes presentan IM residual o recurrente.El anillo Edwards IMR es un anillo específicamente diseñado para la corrección de esta patología, aumentando específicamente la coaptación en la comisura posterior.Métodosdesde 2007 hasta 2011 hemos intervenido a 64 pacientes por IM isquémica, realizando revascularización coronaria e implante de anillo IMR en 58 pacientes y anuloplastia aislada en 6 (3 reintervenciones con puentes permeables). Se ha excluido 23 pacientes con IM por etiología mixta. La IM preoperatoria era superior a III en 21 pacientes (32,8%), III en 35 (54,7%), inferior a III en 8 (12,5%, en 5 realizándose una ecocardiografía transtorácica (ETT) de esfuerzo, demostrando incremento de la IM). LA fracción de eyección del ventrículo izquierdo (FEVI) preoperatoria media era 40,9%, presentando el 28% disfunción ventricular grave (≤ 30%).Resultadosla mortalidad operatoria fue 1 paciente (1,56%). La IM en el primer mes fue grado inferior a II en 57 pacientes (89%), grado II en 7 (8%), y grado III en 2 (3%), con un gradiente medio de 3,1mmHg. Ningún paciente ha sido reintervenido durante este periodo.Conclusionesla reparación de la IM isquémica con el anillo IMR ofrece unos buenos resultados clínicos con una excelente corrección de la IM. Es una técnica simple y reproductible en la mayoría de pacientes con disfunción tipo IIIb
Thermal Correlators in Holographic Models with Lifshitz scaling
We study finite temperature effects in two distinct holographic models that
exhibit Lifshitz scaling, looking to identify model independent features in the
dual strong coupling physics. We consider the thermodynamics of black branes
and find different low-temperature behavior of the specific heat. Deformation
away from criticality leads to non-trivial temperature dependence of
correlation functions and we study how the characteristic length scale in the
two point function of scalar operators varies as a function of temperature and
deformation parameters.Comment: 28 pages, 8 figures; typos corrected, references added, published
versio
Towards the high-accuracy determination of the 238U fission cross section at the threshold region at CERN - N-TOF
The 238U fission cross section is an international standard beyond 2 MeV where the fission plateau starts. However, due to its importance in fission reactors, this cross-section should be very accurately known also in the threshold region below 2 MeV. The 238U fission cross section has been measured relative to the 235U fission cross section at CERN - n-TOF with different detection systems. These datasets have been collected and suitably combined to increase the counting statistics in the threshold region from about 300 keV up to 3 MeV. The results are compared with other experimental data, evaluated libraries, and the IAEA standards
Charged Dilatonic AdS Black Branes in Arbitrary Dimensions
We study electromagnetically charged dilatonic black brane solutions in
arbitrary dimensions with flat transverse spaces, that are asymptotically AdS.
This class of solutions includes spacetimes which possess a bulk region where
the metric is approximately invariant under Lifshitz scalings. Given fixed
asymptotic boundary conditions, we analyze how the behavior of the bulk up to
the horizon varies with the charges and derive the extremality conditions for
these spacetimes.Comment: References update
Holographic Duals of Quark Gluon Plasmas with Unquenched Flavors
We review the construction of gravitational solutions holographically dual to
N=1 quiver gauge theories with dynamical flavor multiplets. We focus on the
D3-D7 construction and consider the finite temperature, finite quark chemical
potential case where there is a charged black hole in the dual solution.
Discussed physical outputs of the model include its thermodynamics (with
susceptibilities) and general hydrodynamic properties.Comment: Lecture presented at the Workshop "AdS/CFT and Novel Approaches to
Hadron and Heavy Ion Physics", Kavli Institute of Theoretical Physics
(KITPC), Beijing, China, 13 October 2010. Review article to be published in
Communications in Theoretical Physics. 27 pages, 2 figure
Field theories with anisotropic scaling in 2D, solitons and the microscopic entropy of asymptotically Lifshitz black holes
Field theories with anisotropic scaling in 1+1 dimensions are considered. It
is shown that the isomorphism between Lifshitz algebras with dynamical
exponents z and 1/z naturally leads to a duality between low and high
temperature regimes. Assuming the existence of gap in the spectrum, this
duality allows to obtain a precise formula for the asymptotic growth of the
number of states with a fixed energy which depends on z and the energy of the
ground state, and reduces to the Cardy formula for z=1. The holographic
realization of the duality can be naturally inferred from the fact that
Euclidean Lifshitz spaces in three dimensions with dynamical exponents and
characteristic lengths given by z, l, and 1/z, l/z, respectively, are
diffeomorphic. The semiclassical entropy of black holes with Lifshitz
asymptotics can then be recovered from the generalization of Cardy formula,
where the ground state corresponds to a soliton. An explicit example is
provided by the existence of a purely gravitational soliton solution for BHT
massive gravity, which precisely has the required energy that reproduces the
entropy of the analytic asymptotically Lifshitz black hole with z=3.
Remarkably, neither the asymptotic symmetries nor central charges were
explicitly used in order to obtain these results.Comment: 17 pages, no figures, references corrected and update
Present Status and Future Programs of the n_TOF Experiment
This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial License 3.0, which permits unrestricted use, distribution, and reproduction in any noncommercial medium, provided the original work is properly citedThe neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology.The most relevant measurements performed up to now and foreseen for the future will be presented in this contribution. The overall efficiency of the experimental program and the range of possible measurements achievable with the construction of a second experimental area (EAR-2), vertically located 20 m on top of the n_TOF spallation target, might offer a substantial improvement in measurement sensitivities. A feasibility study of the possible realisation of the installation extension will be also presented
Generalized Holographic Quantum Criticality at Finite Density
We show that the near-extremal solutions of Einstein-Maxwell-Dilaton
theories, studied in ArXiv:1005.4690, provide IR quantum critical geometries,
by embedding classes of them in higher-dimensional AdS and Lifshitz solutions.
This explains the scaling of their thermodynamic functions and their IR
transport coefficients, the nature of their spectra, the Gubser bound, and
regulates their singularities. We propose that these are the most general
quantum critical IR asymptotics at finite density of EMD theories.Comment: v4: Corrected the scaling equation for the conductivity in section
9.
Asymptotically Lifshitz wormholes and black holes for Lovelock gravity in vacuum
Static asymptotically Lifshitz wormholes and black holes in vacuum are shown
to exist for a class of Lovelock theories in d=2n+1>7 dimensions, selected by
requiring that all but one of their n maximally symmetric vacua are AdS of
radius l and degenerate. The wormhole geometry is regular everywhere and
connects two Lifshitz spacetimes with a nontrivial geometry at the boundary.
The dynamical exponent z is determined by the quotient of the curvature radii
of the maximally symmetric vacua according to n(z^2-1)+1=(l/L)^2, where L
corresponds to the curvature radius of the nondegenerate vacuum. Light signals
are able to connect both asymptotic regions in finite time, and the
gravitational field pulls towards a fixed surface located at some arbitrary
proper distance to the neck. The asymptotically Lifshitz black hole possesses
the same dynamical exponent and a fixed Hawking temperature given by T=z/(2^z
pi l). Further analytic solutions, including pure Lifshitz spacetimes with a
nontrivial geometry at the spacelike boundary, and wormholes that interpolate
between asymptotically Lifshitz spacetimes with different dynamical exponents
are also found.Comment: 19 pages, 1 figur
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