Perturbative Gravity in the Causal Approach

Quantum theory of the gravitation in the causal approach is studied up to the second order of perturbation theory. We prove gauge invariance and renormalizability in the second order of perturbation theory for the pure gravity system (massless and massive). Then we investigate the interaction of massless gravity with matter (described by scalars and spinors) and massless Yang-Mills fields. We obtain a difference with respect to the classical field theory due to the fact that in quantum field theory one cannot enforce the divergenceless property on the vector potential and this spoils the divergenceless property of the usual energy-momentum tensor. To correct this one needs a supplementary ghost term in the interaction Lagrangian.Comment: 50 pages, no figures, some changes in the last sectio

The Interaction of Quantum Gravity with Matter

The interaction of (linearized) gravitation with matter is studied in the causal approach up to the second order of perturbation theory. We consider the generic case and prove that gravitation is universal in the sense that the existence of the interaction with gravitation does not put new constraints on the Lagrangian for lower spin fields. We use the formalism of quantum off-shell fields which makes our computation more straightforward and simpler.Comment: 25 page

The Use of Single-Sided NMR to Study Moisture Behaviour in an Activated Carbon Fibre/Phenolic Composite

Nuclear Magnetic Resonance (NMR) has been shown to be a useful technique to study the form and content of water in polymer composites. Composites using activated carbon fibres with phenolic resin have complex water absorption behaviour which would benefit from such investigation; however, the presence of the conductive fibres can make NMR problematic. In this study, single-sided NMR has been successfully used on such material by developing a method for sample-to-sample compensation for the effect of conductivity. Transverse relaxation curves showed water to be primarily in two states in the resin, corresponding to "bound" and "mobile" molecules. In addition, two much less bound states were identified in the composite, associated firstly with water adsorbed on to the fibre surface and secondly with clusters of water molecules moving more freely within the fibre pores

Desamidation acide et modification enzymatique a pH 10 de gliadines de ble : influence sur leurs proprietes fonctionnelles

24 ref. * communication oraleInternational audienc

Caracterisation biochimique et fonctionnelle des proteines de gluten desamidees partiellement en conditions menagees

17 ref.National audienc