31 research outputs found
On Dual Formulation of Gravity
In this paper we consider a possibility to construct dual formulation of
gravity where the main dynamical field is the Lorentz connection
\omega_\mu^{ab} and not that of tetrad e_\mu^a or metric g_\mu\nu. Our approach
is based on the usual dualization procedure which uses first order parent
Lagrangians but in (Anti) de Sitter space and not in the flat Minkowski one. It
turns out that in d=3 dimensions such dual formulation is related with the so
called exotic parity-violating interactions for massless spin-2 particles.Comment: 7 pages, plain LaTe
On Dual Formulation for Higher Spin Gauge Fields in
We obtain dual actions for spin massless fields in by
solving different algebraic constraints in the same first-order theory. Flat
space dual higher spin actions obtained by Boulanger, Cnockaert and Henneaux
\cite{BH} by solving differential constraints are shown to result from our
formulation in a sort of quasi-classical approximation for the flat limit. The
case of is considered in detail.Comment: LaTeX, 13 pages, no figure
Consistent interactions of dual linearized gravity in D=5: couplings with a topological BF model
Under some plausible assumptions, we find that the dual formulation of
linearized gravity in D=5 can be nontrivially coupled to the topological BF
model in such a way that the interacting theory exhibits a deformed gauge
algebra and some deformed, on-shell reducibility relations. Moreover, the
tensor field with the mixed symmetry (2,1) gains some shift gauge
transformations with parameters from the BF sector.Comment: 63 pages, accepted for publication in Eur. Phys. J.
First order gauge field theories from a superfield formulation
Recently, Batalin and Marnelius proposed a superfield algorithm for master
actions in the BV-formulation for a class of first order gauge field theories.
Possible theories are determined by a ghost number prescription and a simple
local master equation. We investigate consistent solutions of these local
master equations with emphasis on four and six dimensional theories.Comment: 18 pages, Latex, no figures, references and some comments adde
Effective Lagrangians and Universality Classes of Nonlinear Bigravity
We discuss the fully non-linear formulation of multigravity. The concept of
universality classes of effective Lagrangians describing bigravity, which is
the simplest form of multigravity, is introduced. We show that non-linear
multigravity theories can naturally arise in several different physical
contexts: brane configurations, certain Kaluza-Klein reductions and some
non-commutative geometry models. The formal and phenomenological aspects of
multigravity (including the problems linked to the linearized theory of massive
gravitons) are briefly discussed.Comment: 41 pages, 4 Figures, final version to be published in Phys.Rev.
Validation d'un test d'évaluation du comportement gestuel du patient lombalgique chronique
peer reviewe
Stable methylation at promoters distinguishes epiblast stem cells from embryonic stem cells and the in vivo epiblasts
Embryonic Stem Cells (ESCs) and Epiblast Stem Cells (EpiSCs) are the in vitro representatives of naïve and primed pluripotency, respectively. It is currently unclear how their epigenomes underpin the phenotypic and molecular characteristics of these distinct pluripotent states. Here, we performed a genome-wide comparison of DNA methylation between ESCs and EpiSCs by MethylCap-Seq. We observe that promoters are preferential targets for methylation in EpiSC compared to ESCs, in particular high CpG island promoters. This is in line with upregulation of the de novo methyltransferases Dnmt3a1 and Dnmt3b in EpiSC, and downregulation of the demethylases Tet1 and Tet2. Remarkably, the observed DNA methylation signature is specific to EpiSCs and differs from that of their in vivo counterpart, the postimplantation epiblast. Using a subset of promoters that are differentially methylated, we show that DNA methylation is established within a few days during in vitro outgrowth of the epiblast, and also occurs when ESCs are converted to EpiSCs in vitro. Once established, this methylation is stable, as ES-like cells obtained by in vitro reversion of EpiSCs display an epigenetic memory that only extensive passaging and sub-cloning are able to almost completely erase