3D Dynamics of 4D Topological BF Theory With Boundary

We consider the four dimensional abelian topological BF theory with a planar boundary introduced following the Symanzik's method. We find the most general boundary conditions compatible with the fields equations broken by the boundary. The residual gauge invariance is described by means of two Ward identities which generate an algebra of conserved currents. We interpret this algebra as canonical commutation relations of fields, which we use to construct a three dimensional Lagrangian. As a remarkable by-product, the (unique) boundary condition which we found, can be read as a duality relation between 3D dynamical variables.Comment: 22 pages, no figures, version to appear on New Journal of Physic

Non-Abelian BF theory for 2+1 dimensional topological states of matter

We present a field theoretical analysis of the 2+1 dimensional BF model with boundary in the Abelian and the non-Abelian case based on the Symanzik's separability condition. In both cases on the edges we obtain Ka\v{c}--Moody algebras with opposite chiralities reflecting the time reversal invariance of the theory. While the Abelian case presents an apparent arbitrariness in the value of the central charge, the physics on the boundary of the non-Abelian theory is completely determined by time reversal and gauge symmetry. The discussion of the non-Abelian BF model shows that time reversal symmetry on the boundary implies the existence of counter-propagating chiral currents.Comment: version to appear in New Journal of Physic

Different Assay Conditions for Detecting the Production and Release of Heat-Labile and Heat-Stable Toxins in Enterotoxigenic Escherichia coli Isolates

Enterotoxigenic Escherichia coli (ETEC) produce heat-labile (LT) and/or heat-stable enterotoxins (ST). Despite that, the mechanism of action of both toxins are well known, there is great controversy in the literature concerning the in vitro production and release of LT and, for ST, no major concerns have been discussed. Furthermore, the majority of published papers describe the use of only one or a few ETEC isolates to define the production and release of these toxins, which hinders the detection of ETEC by phenotypic approaches. Thus, the present study was undertaken to obtain a better understanding of ST and LT toxin production and release under laboratory conditions. Accordingly, a collection of 90 LT-, ST-, and ST/LT-producing ETEC isolates was used to determine a protocol for toxin production and release aimed at ETEC detection. for this, we used previously raised anti-LT antibodies and the anti-ST monoclonal and polyclonal antibodies described herein. the presence of bile salts and the use of certain antibiotics improved ETEC toxin production/release. Triton X-100, as chemical treatment, proved to be an alternative method for toxin release. Consequently, a common protocol that can increase the production and release of LT and ST toxins could facilitate and enhance the sensitivity of diagnostic tests for ETEC using the raised and described antibodies in the present work.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Butantan Inst, Bacteriol Lab, BR-05503900 São Paulo, BrazilSão Paulo Trop Med Inst, Seroepidemiol & Immunol Lab, BR-05403000 São Paulo, BrazilFleury Med & Hlth, BR-04344903 São Paulo, BrazilButantan Inst, Immunopathol Lab, BR-05503900 São Paulo, BrazilButantan Inst, Immunochem Lab, BR-05503900 São Paulo, BrazilAdolfo Lutz Inst, Bacteriol Sect, BR-01246000 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol, BR-04923062 São Paulo, SP, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol, BR-04923062 São Paulo, SP, BrazilWeb of Scienc

Building the genomic nation: ‘Homo Brasilis’ and the ‘Genoma Mexicano’ in comparative cultural perspective

This article explores the relationship between genetic research, nationalism and the construction of collective social identities in Latin America. It makes a comparative analysis of two research projects – the ‘Genoma Mexicano’ and the ‘Homo Brasilis’ – both of which sought to establish national and genetic profiles. Both have reproduced and strengthened the idea of their respective nations of focus, incorporating biological elements into debates on social identities. Also, both have placed the unifying figure of the mestizo/mestiço at the heart of national identity constructions, and in so doing have displaced alternative identity categories, such as those based on race. However, having been developed in different national contexts, these projects have had distinct scientific and social trajectories: in Mexico, the genomic mestizo is mobilized mainly in relation to health, while in Brazil the key arena is that of race. We show the importance of the nation as a frame for mobilizing genetic data in public policy debates, and demonstrate how race comes in and out of focus in different Latin American national contexts of genomic research, while never completely disappearing