2,234 research outputs found
Stable non-uniform black strings below the critical dimension
The higher-dimensional vacuum Einstein equation admits translationally
non-uniform black string solutions. It has been argued that infinitesimally
non-uniform black strings should be unstable in 13 or fewer dimensions and
otherwise stable. We construct numerically non-uniform black string solutions
in 11, 12, 13, 14 and 15 dimensions. Their stability is investigated using
local Penrose inequalities. Weakly non-uniform solutions behave as expected.
However, in 12 and 13 dimensions, strongly non-uniform solutions appear to be
stable and can have greater horizon area than a uniform string of the same
mass. In 14 and 15 dimensions all non-uniform black strings appear to be
stable.Comment: 26 pages, 11 figures. V2: reference added, matches published versio
Self-Consistent Modeling of Gravitational Theories beyond General Relativity.
The majority of extensions to general relativity (GR) display mathematical pathologies-higher derivatives, character change in equations that can be classified within partial differential equation theory, and even unclassifiable ones-that cause severe difficulties to study them, especially in dynamical regimes. We present here an approach that enables their consistent treatment and extraction of physical consequences. We illustrate this method in the context of single and merging black holes in a highly challenging beyond GR theory
Evaluation of immunomodulatory effects of lactic acid bacteria in turbot (Scophthalmus maximus)
7 pages, 4 figures.In the present work, the effects of several lactic acid bacteria on the immune response of turbot (Scophthalmus
maximus) macrophages have been studied both in vitro and in vivo. Out of six lactic acid bacterial strains
tested, only heat-killed Lactococcus lactis significantly increased the turbot head kidney macrophage chemiluminescent
(CL) response after 24 h of incubation. Nitric oxide (NO) was also significantly enhanced by this
bacterium after 72 h of incubation with either viable (103 and 106 cells/ml) or heat-killed (106 cells/ml) bacteria.
Viable Leuconostoc mesenteroides (106 cells/ml) was also capable of significantly increasing NO production.
Since L. lactis proved to be the strain with more effects on the host immune function, further in vivo and in vitro
experiments were conducted with this bacterium. The in vitro capacity of L. lactis to adhere to turbot intestinal
mucus was positively confirmed. When orally administered, L. lactis significantly increased the macrophage CL
response and the serum NO concentration after 7 days of daily administration. The antibacterial effect of the
extracellular products from the six LAB strains against the fish-pathogenic bacterium Vibrio anguillarum was
also demonstrated in vitro.This work was partially supported by the project 1FD97-0044-C03-03 from FEDER funds and a grant from Caixa Galicia (Spain). L. Villamil acknowledges the University of Vigo for a research fellowship. C. Tafalla acknowledges the Consejo Superior de Investigaciones
CientÃficas (CSIC) for a research fellowship.Peer reviewe
PREFACE: The Milky Way Unravelled by Gaia: GREAT Science from the Gaia Data Releases
International audiencePREFAC
Test engineering education in Europe: the EuNICE-Test project
The paper deals with a European experience of education in industrial test of ICs and SoCs using remote testing facilities. The project addresses the problem of the shortage in microelectronics engineers aware with the new challenge of testing mixed-signal SoCs far multimedia/telecom market. It aims at providing test training facilities at a European scale in both initial and continuing education contexts. This is done by allowing the academic and industrial partners of the consortium to train engineers using the common test resources center (CRTC) hosted by LIRMM (Laboratoire d'Informatique, de Robotique et de Microelectronique de Montpellier, France). CRTC test tools include up-to-date/high-tech testers that are fully representative of real industrial testers as used on production testfloors. At the end of the project, it is aimed at reaching a cruising speed of about 16 trainees per year per center. Each trainee will have attend at least one one-week training using the remote test facilities of CRTC
Solving the initial conditions problem for modified gravity theories
Modified gravity theories such as Einstein scalar Gauss Bonnet contain higher-derivative terms in the spacetime curvature in their action, which results in modifications to the Hamiltonian and momentum constraints of the theory. In principle, such modifications may affect the principal part of the operator in the resulting elliptic equations, and so further complicate the already highly nonlinear, coupled constraints that apply to the initial data in numerical relativity simulations of curved spacetimes. However, since these are effective field theories, we expect the additional curvature terms to be small, which motivates treating them simply as an additional source in the constraints, and iterating to find a solution to the full problem. In this work we implement and test a modification to the CTT/CTTK methods of solving the constraints for the case of the most general four derivative, parity invariant scalar-tensor theory, and show that solutions can be found in both asymptotically flat/black hole and periodic/cosmological spacetimes, even up to couplings of order unity in the theory. Such methods will allow for numerical investigations of a much broader class of initial data than has previously been possible in these theories, and should be straightforward to extend to similar models in the Horndeski class
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