A Wake-Up Call: Lessons from Ebola for the World's Health Systems

The report ranks the world's poorest countries on the state of their public health systems, finding that 28 have weaker defenses in place than Sierra Leone where, alongside Liberia and Guinea, the current Ebola crisis has already claimed more than 9,500 lives. The report also advises that prevention is better than cure, finding that the international Ebola relief effort in West Africa has cost $4.3bn, whereas strengthening the health systems of those countries in the first place would have cost just$1.58bn. Ahead of an Ebola summit attended by world leaders in Brussels today, the charity warns that alongside immediate much needed support to Sierra Leone, Liberia and Guinea, lessons need to be learned and applied to other vulnerable countries around the world

Algorithme exact pour le problème de l'indépendant faiblement connexe de cardinalité minimum.

International audienceLa gestion des communications radios entre des capteurs sans fil dépend de la topologie mise en place sur le réseau. Généralement, on utilise des architectures basées sur des objets combinatoires issus de la théorie des graphes comme les arbres, les ensembles dominants connexes ou faiblement connexes. Dans cet exposé, nous étudions la structure alternative d'indépendant faiblement connexe (\emph{weakly connected independent set} ou $wcis$) et précisons ses propriétés. Nous décrivons une heuristique qui permet de trouver un $wcis$ rapidement dans un graphe des communications $G=(V,E)$ connexe, ainsi qu'un algorithme d'énumération pour la recherche d'un $wcis$ de cardinalité minimum. Nous donnons enfin des résultats d'expérimentations numériques

Point Contact Spectroscopy of Nb3Sn Crystals: Evidence of a CDW Gap Related to the Martensitic Transition

Two Single crystals of Nb3Sn presenting the martensitic anomaly at different temperature and shape, as observed with specific heat measurements, were used to study structural features in the electronic density of states with point contact spectroscopy. At high temperature below the martensitic anomaly, we observed different spectroscopic characteristics. One sample displaying a well marked specific heat peak, shows a clear defined structure in the differential conductance that evolves with temperature and may be associated with changes on the density of states due to the opening of a charge density wave gap. Those features are very depending on the crystallographics characteristics of the single crystal examined.Comment: 13 pages 6 figures. accepted in Solid State Communicatio

Scaling Laws for Magnetic Energy in Superconducting Quadrupoles

The stored energy in superconducting magnets is one of the main ingredients needed for the quench calculation and for designing quench protections. Here we propose an analytical formula based on the Fourier transformation of the current density flowing within the winding to determine the magnetic energy stored in superconducting quadrupoles made of sector coils. Two corrective coefficients allowing to estimate the energy enhancement produced either by current grading or by the presence of an unsaturated iron yoke are respectively derived from a numerical and an analytical study. This approach is applied to a set of real quadrupoles to test the validity limits of the scaling law, which are shown to be of ~10%

130 mm Aperture Quadrupoles for the LHC Luminosity Upgrade

Several studies for the LHC luminosity upgrade pointed out the need for low-beta quadrupoles with apertures larger than the present baseline (70 mm). In this paper we focus on the design issues of a 130 mm aperture quadrupole. We first consider the Nb-Ti option, presenting a magnetic design with the LHC dipole and quadrupole cables. We study the electromagnetic forces and we discuss the field quality constraints. For the Nb$_{3}$Sn option, we sketch three designs, two based on the LARP 10 mm width cable, and one on a larger cable with the same strand. The issue of the stress induced by the e.m. forces, which is critical for the Nb$_{3}$Sn, is discussed using both scaling laws and finite element models

Compensation magnétique de pesanteur dans des fluides : synthèse des performances et contraintes

La communication présente les principauxrésultats théoriques et expérimentaux obtenus depuis unequinzaine d'années dans le domaine de la compensationmagnétique de pesanteur. Cette technique, destinéeprincipalement à des études de comportement de fluides enenvironnement spatial, utilise des sources de champ magnétiquegénéralement élevé. Les avantages et les limites de la lévitationsont présentés ; son application à des problèmes decomportement de fluides sous forme diphasique est décrite.</p

Study of fluid behaviour under gravity compensated by a magnetic field

International audienceFluids, and especially cryogenic fluids like Hydrogen H2 and Oxygen O2 , are widely used in space technology for propulsion and cooling. The knowledge of fluid behaviour during the acceleration variation and under reduced gravity is necessary for an efficient management of fluids in space. Such a management also asks fundamental questions about thermo-hydrodynamics and phase change once buoyancy forces are cancelled. For security reasons, it is nearly impossible to use the classical microgravity means to experiment with such cryofluids. However, it is possible to counterbalance gravity by using the paramagnetic (O2) or diamagnetic (H2) properties of fluids. By applying a magnetic field gradient on these materials, a volume force is created that is able to impose to the fluid a varying effective gravity, including microgravity. We have set up a magnetic levitation facility for H2 in which many experiments have been performed. A new facility for O2 is under construction that will enable fast change in the effective gravity by quenching down the magnetic field. The facilities and some particularly representative experimental results are presented

The k-edge connected subgraph problem: Valid inequalities and Branch-and-Cut

International audienceIn this paper we consider the k-edge connected subgraph problem from a polyhedral point of view. We introduce further classes of valid inequalities for the associated polytope, and describe sufficient conditions for these inequalities to be facet defining. We also devise separation routines for these inequalities, and discuss some reduction operations that can be used in a preprocessing phase for the separation. Using these results, we develop a Branch-and-Cut algorithm and present some computational results

Physiological Epidermal Growth Factor Concentrations Activate High Affinity Receptors to Elicit Calcium Oscillations

International audienceSignaling mediated by the epidermal growth factor (EGF) is crucial in tissue development, homeostasis and tumorigenesis. EGF is mitogenic at picomolar concentrations and is known to bind its receptor on high affinity binding sites depending of the oligomerization state of the receptor (monomer or dimer). In spite of these observations, the cellular response induced by EGF has been mainly characterized for nanomolar concentrations of the growth factor, and a clear definition of the cellular response to circulating (picomolar) concentrations is still lacking. We investigated Ca 2+ signaling, an early event in EGF responses, in response to picomolar doses in COS-7 cells where the monomer/dimer equilibrium is unaltered by the synthesis of exogenous EGFR. Using the fluo5F Ca 2+ indicator, we found that picomolar concentrations of EGF induced in 50% of the cells a robust oscillatory Ca 2+ signal quantitatively similar to the Ca 2+ signal induced by nanomolar concentrations. However, responses to nanomolar and picomolar concentrations differed in their underlying mechanisms as the picomolar EGF response involved essentially plasma membrane Ca 2+ channels that are not activated by internal Ca 2+ store depletion, while the nanomolar EGF response involved internal Ca 2+ release. Moreover, while the picomolar EGF response was modulated by charybdotoxin-sensitive K + channels, the nanomolar response was insensitive to the blockade of these ion channels

A Review of the Properties of Nb3Sn and Their Variation with A15 Composition, Morphology and Strain State

This article gives an overview of the available literature on simplified, well defined (quasi-)homogeneous laboratory samples. After more than 50 years of research on superconductivity in Nb3Sn, a significant amount of results are available, but these are scattered over a multitude of publications. Two reviews exist on the basic properties of A15 materials in general, but no specific review for Nb3Sn is available. This article is intended to provide such an overview. It starts with a basic description of the Niobium-Tin intermetallic. After this it maps the influence of Sn content on the the electron-phonon interaction strength and on the field-temperature phase boundary. The literature on the influence of Cu, Ti and Ta additions will then be briefly summarized. This is followed by a review on the effects of grain size and strain. The article is concluded with a summary of the main results.Comment: Invited Topical Review for Superconductor, Science and Technology. Provisionally scheduled for July 200