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Champs-sur-Marne, France

The University Paris-Est Marne-la-Vallée is a French university, in the Academy of Créteil. Wikipedia.

Roth J.,University of Marne-la-Vallee
Journal of Geometry and Physics

We give spinorial characterizations of isometrically immersed surfaces into three-dimensional homogeneous manifolds with four-dimensional isometry group in terms of the existence of a particular spinor field. This generalizes works by Friedrich for R3 and Morel for S3 and H3. The main argument is the interpretation of the energy-momentum tensor of such a spinor field as the second fundamental form up to a tensor depending on the structure of the ambient space. © 2010 Elsevier B.V. Source

Houdayer C.,University of Marne-la-Vallee
Communications in Mathematical Physics

Let (Formula presented.) be a free product of arbitrary von Neumann algebras endowed with faithful normal states. Assume that the centralizer (Formula presented.) is diffuse. We first show that any intermediate subalgebra (Formula presented.) which has nontrivial central sequences in M is necessarily equal to M1. Then we obtain a general structural result for all the intermediate subalgebras (Formula presented.) with expectation. We deduce that any diffuse amenable von Neumann algebra can be concretely realized as a maximal amenable subalgebra with expectation inside a full nonamenable type III1 factor. This provides the first class of concrete maximal amenable subalgebras in the framework of type III factors. We finally strengthen all these results in the case of tracial free product von Neumann algebras. © 2014, Springer-Verlag Berlin Heidelberg. Source

Lassalle M.,University of Marne-la-Vallee
Journal of Combinatorial Theory. Series A

We prove the following conjecture of Zeilberger. Denoting by C n the Catalan number, define inductively A n by (-1) n-1A n=C n+∑ j=1 n-1(-1)j(2n-1 2j-1)A jC n-j and a n=2A n/C n. Then a n (hence A n) is a positive integer. © 2012 Elsevier Inc. Source

Morimae T.,Imperial College London | Morimae T.,University of Marne-la-Vallee
Physical Review A - Atomic, Molecular, and Optical Physics

String-net condensate is a new class of materials which exhibits quantum topological order. Here we study the measurement-based quantum computation on the simplest example of string-net condensate, namely the Z 2 gauge string-net condensate on the two-dimensional hexagonal lattice, by using the framework of quantum computational tensor network. We show that universal measurement-based quantum computation is possible by coupling two correlation space wires with a physical two-body interaction. We also show that universal measurement-based quantum computation is possible solely with single-qubit measurements if the sign of the coefficient of each closed-loop configuration in the state is tuned. These results suggest that even the simplest example of string-net condensate is equipped with the correlation space that has the capacity for the application to quantum information processing. © 2012 American Physical Society. Source

Loconto A.,University of Marne-la-Vallee
Science Technology and Human Values

Standards that codify sustainability, such as Ethical Trade, Fairtrade, Organic and Rainforest Alliance, have become a common means for value chain actors in the Global North to make statements about the values of their products and the practices of producers in the Global South. This case study of Tanzanian tea value chains takes a closer look at how sustainability, in the form of SustainabiliTea, is done by actors who did not participate in defining and standardizing the form of sustainability with which they are meant to comply. Based on data collected during a multisited ethnography, I explore the performative nature of sustainability standards. The analysis reveals sustainable projects, sustainable markets, sustainable farm management, and sustainable qualities. These multiple SustainabiliTeas work together to construct a single vision of SustainabiliTea, which is a means to sustain the enterprise. I argue that the use of standards to guide performances makes some technical and political stakes visible while rendering others invisible. By paying attention to the residual categories, the tensions between knowledge and materiality, and listening to those voices at the margins, we see what is at stake in the maintenance of SustainabiliTea: survival in the tea market. © The Author(s) 2014. Source

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