The Non--Ergodicity Threshold: Time Scale for Magnetic Reversal

We prove the existence of a non-ergodicity threshold for an anisotropic classical Heisenberg model with all-to-all couplings. Below the threshold, the energy surface is disconnected in two components with positive and negative magnetizations respectively. Above, in a fully chaotic regime, magnetization changes sign in a stochastic way and its behavior can be fully characterized by an average magnetization reversal time. We show that statistical mechanics predicts a phase--transition at an energy higher than the non-ergodicity threshold. We assess the dynamical relevance of the latter for finite systems through numerical simulations and analytical calculations. In particular, the time scale for magnetic reversal diverges as a power law at the ergodicity threshold with a size-dependent exponent, which could be a signature of the phenomenon.Comment: 4 pages 4 figure

Correlation between fibronectin binding protein A expression level at the surface of recombinant lactococcus lactis and plasmid transfer in vitro and in vivo

Background: Fibronectin Binding Protein A (FnBPA) is an invasin from Staphylococcus aureus that allows this pathogen to internalize into eukaryote cells. It was previously demonstrated that recombinant Lactococcus lactis expressing FnBPA were invasive and able to transfer a plasmid to eukaryotic cells in vitro and in vivo. In this study, the invasivity of recombinant strains of Lactococcus lactis that express FnBPA under the control of its constitutive promoter or driven by the strong nisin inducible expression system (NICE) were studied.Results: It was demonstrated that the nisA promoter allows an increase of FnBPA expression on the surface of Lactococcus lactis surface, as shown by flow cytometry, which subsequently enhanced internalization and plasmid transfer properties in vitro in Caco2 cells and Bone Marrow Dendritic Cells. In vivo, the use of nisA promoter increase the plasmid transfer in cells of both the small and large intestine of mice.Conclusion: FnBPA expression at the surface of recombinant L. lactis is positively correlated to internalization and DNA transfer properties. The recombinant strains of L. lactis that expresses FnBPA under the control of the nisin inducible expression system could thus be considered as an improved tool in the field of DNA transfer.Fil: Almeida, Juliana F.. Institut National de la Recherche Agronomique; Francia. Institut des sciences et industries du vivant et de l; FranciaFil: Mariat, Denis. Institut National de la Recherche Agronomique; Francia. Institut des sciences et industries du vivant et de l; FranciaFil: Azevedo, Vasco. Universidade Federal Do Minas Gerais;Fil: Miyoshi, Anderson. Universidade Federal Do Minas Gerais;Fil: de Moreno, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: del Carmen, Silvina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Martin, Rebeca. Institut National de la Recherche Agronomique; Francia. Institut des sciences et industries du vivant et de l; FranciaFil: Langella, Philippe. Institut National de la Recherche Agronomique; Francia. Institut des sciences et industries du vivant et de l; FranciaFil: Leblanc, Jean Guy Joseph. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Chatel, Jean Marc. Institut National de la Recherche Agronomique; Francia. Institut des sciences et industries du vivant et de l; Franci

BRSMG Curinga: cultivar de arroz de terras altas de ampla adaptação para o Brasil.

O objetivo deste trabalho é a apresentação das características da BRSMG Curinga, a sétima cultivar de arroz de terras altas originária da colaboração da Embrapa com o programa CIAT/CIRAD, lançada em 2005 para cultivo em condições de terras altas nos Estados de Minas Gerais, Goiás, Mato Grosso, Rondônia, Pará, Roraima, Maranhão, Piauí e Tocantins.bitstream/CNPAF/23577/1/comt_114.pd

Zinc finger proteins act as transcriptional repressors of alkaloid biosynthesis genes in Catharanthus roseus

Plant science

Formation and interactions of cold and ultracold molecules: new challenges for interdisciplinary physics

Progress on researches in the field of molecules at cold and ultracold temperatures is reported in this review. It covers extensively the experimental methods to produce, detect and characterize cold and ultracold molecules including association of ultracold atoms, deceleration by external fields and kinematic cooling. Confinement of molecules in different kinds of traps is also discussed. The basic theoretical issues related to the knowledge of the molecular structure, the atom-molecule and molecule-molecule mutual interactions, and to their possible manipulation and control with external fields, are reviewed. A short discussion on the broad area of applications completes the review.Comment: to appear in Reports on Progress in Physic