64,010 research outputs found
Foliated eight-manifolds for M-theory compactification
No full textWe characterize compact eight-manifolds M which arise as internal spaces in N = 1
flux compactifications of M-theory down to AdS3 using the theory of foliations, for the case when
the internal part ξ of the supersymmetry generator is everywhere non-chiral. We prove that specifying
such a supersymmetric background is equivalent with giving a codimension one foliation
F of M which carries a leafwise G2 structure, such that the O’Neill-Gray tensors, non-adapted
part of the normal connection and the torsion classes of the G2 structure are given in terms of
the supergravity four-form field strength by explicit formulas which we derive. We discuss the
topology of such foliations, showing that the C. algebra C(M/F) is a noncommutative torus
of dimension given by the irrationality rank of a certain cohomology class constructed from G,
which must satisfy the Latour obstruction. We also give a criterion in terms of this class for
when such foliations are fibrations over the circle. When the criterion is not satisfied, each leaf of F is dense in M. c The Authors.11181sciescopu
Foliated backgrounds for M-theory compactifications (II)
No full textWe summarize the foliation approach to compactifications of
eleven-dimensional supergravity on eight-manifolds down to
spaces for the case when the internal part of the supersymmetry generator
is chiral on some proper subset of . In this case, a topological
no-go theorem implies that the complement must be a dense
open subset, while admits a singular foliation (in the
sense of Haefliger) which is defined by a closed one-form
and is endowed with a longitudinal structure. The geometry of this
foliation is determined by the supersymmetry conditions. We also describe the
topology of in the case when is a Morse
form.Comment: 10 pages, conference proceedings -- "Quantum Field Theory and
Nonlinear Dynamics", 24-28 September 2014, Sinaia, Romani
The landscape of G-structures in eight-manifold compactifications of M-theory
No full textWe consider spaces of "virtual" constrained generalized Killing spinors, i.e. spaces of Majorana spinors which correspond to "off-shell" s-extended supersymmetry in compactifications of eleven-dimensional supergravity based on eight-manifolds M. Such spaces naturally induce two stratifications of M, called the chirality and stabilizer stratification. For the case s = 2, we describe the former using the canonical Whitney stratification of a three-dimensional semi-algebraic set R. We also show that the stabilizer stratification coincides with the rank stratification of a cosmooth generalized distribution D-0 and describe it explicitly using the Whitney stratification of a four-dimensional semi-algebraic set B. The stabilizer groups along the strata are isomorphic with SU(2), SU(3), G(2) or SU(4), where SU(2) corresponds to the open stratum, which is generically non-empty. We also determine the rank stratification of a larger generalized distribution D which turns out to be integrable in the case of compactifications down to AdS(3). Open Access, (c) The Authors.1111sciescopu
Low temperature preparation of optimized phosphates for Li-battery applications
No full textWe describe the thermodynamics and kinetics that govern the precipitation of pure powders of phosphates phases of interest for Li-battery applications. We found precise procedures for the formation of three distinct crystalline forms of FePO4.2H(2)O and of pure LiMnPO4. Our attempts to precipitate either LiCoPO4 or LiFePO4, on the other hand, failed. In this latter case, optimized electrodes for battery applications were synthesized through a chemical conductive carbon coating at the surface of LiFePO4 prepared by evaporation of an Fe-III-containing aqueous solution. (C) 2004 Elsevier B.V. All rights reserved
REAL PINOR BUNDLES AND REAL LIPSCHITZ STRUCTURES
No full text© 2019 International Press. Let (M, g) be a pseudo-Riemannian manifold of arbitrary dimension and signature. We prove that there exist mutually quasi-inverse equivalences between the groupoid of weakly faithful real pinor bundles on (M, g) and the groupoid of weakly faithful real Lipschitz structures on (M, g), from which follows that every bundle of weakly faithful real Clifford modules is associated to a real Lipschitz structure. The latter gives a generalization of spin structures based on certain groups which we call real Lipschitz groups. In the irreducible case, we classify real Lipschitz groups in all dimensions and signatures. Using this classification and the previous correspondence we obtain the topological obstruction to existence of a bundle of irreducible real Clifford modules over a pseudo-Riemannian manifold (M, g) of arbitrary dimension and signature. As a direct application of the previous results, we show that the supersymmetry generator of eleven-dimensional supergravity in "mostly plus" signature can be interpreted as a global section of a bundle of irreducible Clifford modules if and only if the underlying eleven-manifold is orientable and spin11Nsciescopu
The role of germline polymorphisms in the T-cell receptor in susceptibility to ankylosing spondylitis.
No full textThe role of germline polymorphisms of the T-cell receptor A/D and B loci in susceptibility to ankylosing spondylitis was investigated by linkage studies using microsatellite markers in 215 affected sibling pairs. The presence of a significant susceptibility gene (lambda > or = 1.6) at the TCRA/D locus was excluded (LOD score < -2.0). At the TCRB locus, there was weak evidence of the presence of a susceptibility gene (P = 0.01, LOD score 1.1). Further family studies will be required to determine whether this is a true or false-positive finding. It is unlikely that either the TCRA/D or TCRB loci contain genes responsible for more than a moderate proportion of the non-MHC genetic susceptibility to ankylosing spondylitis.M. A. Brown, M. Rudwaleit, K. D. Pile, L. G. Kennedy, J. Shatford, C. I. Amos, K. Siminovitch, L. Rubin, A. Calin and B. P. Wordswort
Restoration of fragile Histidine triad (FHIT) expression induces apoptosis and suppresses tumorigenicity in breast cancer cell lines
No full textThe fragile histidine triad (FHIT) gene at chromosome 3p14.2 is a tumor suppressor gene that is altered mainly by deletion in a large fraction of human tumors, including breast cancers. To evaluate the potential of FHIT gene therapy in this type of cancer, we have studied the biological effects of adenoviral FHIT transduction (Ad-FHIT) in breast cancer cell lines. The results showed that, after FHIT restoration in BT-549, MDA-MB-436, and HCC1806 cells, they underwent apoptosis by activation of the intrinsic pathway. In all three cell lines infected with Ad-FHIT, we have found activation of caspase-2, which is required for permeabilization of mitochondria, release of cytochrome c, and apoptosis. Furthermore, Fhit overexpression produces alteration in cell cycling properties, as well as reduction of the tumorigenic potential in nude mice
N = 1 Geometric Supergravity and Chiral Triples on Riemann Surfaces
No full textWe construct a global geometric model for the bosonic sector and Killing spinor equations of four-dimensional N = 1 supergravity coupled to a chiral non-linear sigma model and a Spinc 0 structure. The model involves a Lorentzian metric g on a four-manifold M, a complex chiral spinor and a map ϕ : M →Mfrom M to a complex
manifold M endowed with a novel geometric structure which we call a chiral triple.
Using this geometric model, we show that if M is spin then the Kähler-Hodge condition
on M suffices to guarantee the existence of an associated N = 1 chiral geometric
supergravity. This positively answers a conjecture proposed by D. Z. Freedman and
A. V. Proeyen. We dimensionally reduce the Killing spinor equations to a Riemann
surface X, obtaining a novel system of partial differential equations for a harmonic
map with potential ϕ : X → M. We characterize all Riemann surfaces X admitting
supersymmetric solutions with vanishing superpotential, showing that such solutions ϕ
are holomorphicmaps satisfying a certain condition involving the canonical bundle of X
and the chiral triple of the theory. Furthermore, we determine the biholomorphism type
of all Riemann surfaces carrying supersymmetric solutions with complete Riemannian
metric and finite-energy scalar map ϕ. © Springer-Verlag GmbH Germany, part of Springer Nature 201911Nsciescopu
Erratum to: Effect of moderate red wine intake on cardiac prognosis after recent acute myocardial infarction of subjects with Type 2 diabetes mellitus (Diabetic Medicine, (2006), 23, 9, (974-981), 10.1111/j.1464-5491.2006.01886.x)
No full textIn an article by Marfella et al, the author name C. Saron is incorrect and should be listed as C. Sardu. Therefore the correct author list is: R. Marfella, F. Cacciapuoti, M. Siniscalchi, F. C. Sasso, F. Marchese, F. Cinone, E. Musacchio, M. A. Marfella, L. Ruggiero, G. Chiorazzo, D. Liberti, G. Chiorazzo, G. F. Nicoletti, C. Sardu, F. D'Andrea, C. Ammendola, M. Verza and L. Coppola.In an article by Marfella et al, the author name C. Saron is incorrect and should be listed as C. Sardu. Therefore the correct author list is: R. Marfella, F. Cacciapuoti, M. Siniscalchi, F. C. Sasso, F. Marchese, F. Cinone, E. Musacchio, M. A. Marfella, L. Ruggiero, G. Chiorazzo, D. Liberti, G. Chiorazzo, G. F. Nicoletti, C. Sardu, F. D'Andrea, C. Ammendola, M. Verza and L. Coppola
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
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