Loire Valley Institute for Advanced Studies

Orléans, France

Loire Valley Institute for Advanced Studies

Orléans, France
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Chamseddine A.H.,American University of Beirut | Chamseddine A.H.,University of Tours | Chamseddine A.H.,Loire Valley Institute for Advanced Studies | Volkov M.S.,University of Tours
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We present solutions describing spatially closed, open, or flat cosmologies in the massive gravity theory within the recently proposed tetrad formulation. We find that the effect of the graviton mass is equivalent to introducing to the Einstein equations a matter source that can consist of several different matter types - a cosmological term, quintessence, gas of cosmic strings, and non-relativistic cold matter. © 2011 Elsevier B.V.

Gherardi F.,Loire Valley Institute for Advanced Studies | Gherardi F.,Bureau de Recherches Géologiques et Minières | Audigane P.,Bureau de Recherches Géologiques et Minières
Greenhouse Gases: Science and Technology | Year: 2013

We present numerical simulations of isothermal reactive flow which might be induced by fluid migration at the caprock-cement interface of an idealized abandoned well in an area considered for geological sequestration of CO 2 in the Paris Basin, France. The calculations are aimed at identifying the mineralogical transformations likely occurring in the cement during the working life and after the closure of the wells present in the area, before the injection of CO2. Field evidence, experimental data, and previous numerical simulations have been used to constrain the initial geochemical conditions and the hydraulic parameters of the model. Significant mineralogical transformations in the cement (portlandite and katoite dissolution, CSH, ettringite, hydrotalcite precipitation), and minor modifications of the initial clayrock mineralogical assemblage (quartz, montmorillonite and illite dissolution, and precipitation of cement-like phases) are predicted at the caprock-cement interface. Associated with these mineralogical transformations, measurable variations in porosity are also computed. Although Portland cement is predicted to retain its integrity at some distance from the interface, calculations confirm the general view that material alteration at the interfaces is of major concern for the minimization of the risks of CO2 leakage from storage zones. Numerical outputs are sensitive with respect to poorly constrained physical and transport parameters, such as the spatial distribution of interconnected porosity in the cement. Different degrees of portlandite dissolution/carbonate precipitation can be predicted during in situ ageing under conditions similar to the Paris Basin, depending on the adopted gridding scheme, i.e. on the conceptualization of the cement as a homogeneous or dual-porosity medium. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd.

Wertz F.,Bureau de Recherches Géologiques et Minières | Gherardi F.,Bureau de Recherches Géologiques et Minières | Gherardi F.,Loire Valley Institute for Advanced Studies | Blanc P.,Bureau de Recherches Géologiques et Minières | And 2 more authors.
International Journal of Greenhouse Gas Control | Year: 2013

A geochemical model of wellbore cement-caprock-reservoir interfaces is developed. The model predicts the mechanisms of chemical alteration of cement due to interaction with the acid brine obtained after the injection of supercritical CO2 into the reservoir rock. Numerical outputs indicate that, at the well-reservoir interface, intrusion into the cement phase of acid brine accompanied by aqueous CO2 quasi-instantaneously transforms Portlandite and CSH into Calcite and hydrated Si-gel, leading to a slight but moderate porosity decrease, from 28% to ∼20%. Conversely, at the well-caprock interface, Portlandite first leaches and the Ca2+ ions released from it migrate towards the caprock, where they eventually combine with slowly diffusing aqueous CO2 to form Calcite, up to the porosity collapse of the interface. This can significantly affect the sealing behaviour of the geological storage. We can finally deduce a time-space characterisation of the system enhancing the main chemical mechanisms in view of a future export to a geomechanical model. © 2012 Elsevier Ltd.

Zubkov M.A.,Loire Valley Institute for Advanced Studies | Zubkov M.A.,University of Tours | Zubkov M.A.,Institute of Theoretical and Experimental Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

We analyze the (3+1)D equilibrium chiral magnetic effect (CME). We apply derivative expansion to the Wigner transform of the two-point Green function. This technique allows us to express the response of electric current to the external electromagnetic field strength through the momentum space topological invariant. We consider the wide class of the lattice regularizations of quantum field theory (that includes, in particular, the regularization with Wilson fermions) and also certain lattice models of solid state physics (including those of Dirac semimetals). It appears that in these models the mentioned topological invariant vanishes identically at nonzero chiral chemical potential. That means that the bulk equilibrium CME is absent in those systems. © 2016 American Physical Society.

Chamseddine A.H.,American University of Beirut | Chamseddine A.H.,University of Tours | Chamseddine A.H.,Loire Valley Institute for Advanced Studies | Mukhanov V.,Ludwig Maximilians University of Munich | Mukhanov V.,New York University
Journal of High Energy Physics | Year: 2011

We present a simplified formulation of massive gravity where the Higgs fields have quadratic kinetic term. This new formulation allows us to prove in a very explicit way that all massive gravity theories considered so far inevitably have Boulware-Deser ghost in non-trivial fluctuations of background metric. © 2011 SISSA.

Cvetic M.,University of Pennsylvania | Cvetic M.,University of Maribor | Gibbons G.W.,University of Cambridge | Gibbons G.W.,University of Tours | And 3 more authors.
Physical Review Letters | Year: 2015

We study the thermodynamical properties of a class of asymptotically conical geometries known as "subtracted geometries." We derive the mass and angular momentum from the regulated Komar integral and the Hawking-Horowitz prescription and show that they are equivalent. By deriving the asymptotic charges, we show that the Smarr formula and the first law of thermodynamics hold. We also propose an analog of Christodulou-Ruffini inequality. The analysis can be generalized to other asymptotically conical geometries. © 2015 American Physical Society.

Duval C.,Aix - Marseille University | Duval C.,University of Toulon | Gibbons G.W.,University of Cambridge | Gibbons G.W.,University of Tours | And 2 more authors.
Classical and Quantum Gravity | Year: 2014

The Bondi-Metzner-Sachs group is shown to be the conformal extension of Lévy-Leblond's 'Carroll' group. Further extension to the Newman-Unti group is also discussed in the Carroll framework. © 2014 IOP Publishing Ltd.

Foucault-Collet A.,CNRS Center for Molecular Biophysics | Shade C.M.,University of Pittsburgh | Nazarenko I.,CNRS Center for Molecular Biophysics | Petoud S.,CNRS Center for Molecular Biophysics | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2014

We report herein the synthesis of a luminescent polynuclear dendritic structure (SmIII-G3P-2,3Nap) in which eight SmIII ions are sensitized by thirty-two 2,3-naphthalimide chromophores. Upon a single excitation wavelength, the dendrimer complex exhibits two types of emission in the visible and in the near-infrared (NIR) ranges. SmIII-G3P-2,3Nap was non-cytotoxic after 24 h of incubation and up to 2.5 μM. The ability of the SmIII-based probe to be taken up by cells was confirmed by confocal microscopy. Epifluorescence microscopy validated SmIII-G3P- 2,3Nap as a versatile probe, capable of performing interchangeably in the visible or NIR for live-cell imaging. As both emissions are obtained from a single complex, the cytotoxicity and biodistribution are inherently the same. The possibility for discriminating the sharp SmIII signals from autofluorescence in two spectral ranges increases the reliability of analysis and reduces the probability of artifacts and instrumental errors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Matejuk A.,CNRS Center for Molecular Biophysics | Matejuk A.,Loire Valley Institute for Advanced Studies | Collet G.,CNRS Center for Molecular Biophysics | Nadim M.,CNRS Center for Molecular Biophysics | And 3 more authors.
Archivum Immunologiae et Therapiae Experimentalis | Year: 2013

Inefficient immune response is a major glitch during tumor growth and progression. Chaotic and leaky blood vessels created in the process of angiogenesis allow tumor cells to escape and extricate anti-cancer immunity. Proangiogenic characteristics of hypoxic tumor microenvironment maintained by low oxygen tension attract endothelial progenitor cells, drive expansion of cancer stem cells, and deviantly differentiate monocyte descendants. Such cellular milieu further boosts immune tolerance and eventually appoint immunity for cancer advantage. Blood vessel normalization strategies that equilibrate oxygen levels within tumor and fix abnormal vasculature bring exciting promises to future anticancer therapies especially when combined with conventional chemotherapy. Recently, a new group of microRNAs (miRs) engaged in angiogenesis, called angiomiRs and hypoxamiRs, emerged as new therapeutic targets in cancer. Some of those miRs were found to efficiently regulate cancer immunity and their dysregulation efficiently programs aberrant angiogenesis and cancer metastasis. The present review highlights new findings in the field of miRs proficiency to normalize aberrant angiogenesis and to restore anti-tumor immune responses. © 2013 L. Hirszfeld Institute of Immunology and Experimental Therapy, Wroclaw, Poland.

Faraji Astaneh A.,Sharif University of Technology | Faraji Astaneh A.,Institute for Research in Fundamental Sciences | Faraji Astaneh A.,University of Tours | Gibbons G.,University of Cambridge | And 3 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

For a given quantum field theory, provided the area of the entangling surface is fixed, what surface maximizes entanglement entropy? We analyze the answer to this question in four and higher dimensions. Surprisingly, in four dimensions the answer is related to a mathematical problem of finding surfaces that minimize the Willmore (bending) energy and eventually to the Willmore conjecture. We propose a generalization of the Willmore energy in higher dimensions and analyze its minimizers in a general class of topologies Sm×Sn and make certain observations and conjectures that may have some mathematical significance. © 2014 American Physical Society.

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