Matrix Product States, Random Matrix Theory and the Principle of Maximum Entropy

Using random matrix techniques and the theory of Matrix Product States we show that reduced density matrices of quantum spin chains have generically maximum entropy.Comment: 11 pages, 4 figure

Natural Gauge and Gravitational Coupling Unification and the Superpartner Masses

The possibility to achieve unification at the string scale in the context of the simplest supersymmetric grand unified theory is investigated. We find conservative upper bounds on the superpartner masses consistent with the unification of gauge and gravitational couplings, M_{\tilde G} < 5 TeV and M_{\tilde f} < 3 \times 10^7 GeV, for the superparticles with spin one-half and zero, respectively. These bounds hint towards the possibility that this supersymmetric scenario could be tested at future colliders, and in particular, at the forthcoming LHC.Comment: 8 pages, 4 figures, version accepted in Physics Letters

Artificial ligninolytic secretome by S. cerevisiae: Building a white-rot yeast

The ligninolytic enzyme consortium secreted by white-rot fungi constitutes a rich source of oxidoreductases with potential applications in different areas of biotechnology. The last decade has witnessed the birth of several engineering strategies to meet ligninases with industrial needs, in many cases surpassing the boundaries of nature, by using Saccharomyces cerevisiae as heterologous host in directed evolution enterprises. By harnessing the efficient homologous DNA recombination device of yeast, the natural vanguard of ligninases formed by high redox potential peroxidases and laccases, unspecific peroxygenases and aryl–alcohol oxidases have been improved to work in a range of processes ranging from organic synthesis to biomedical applications. To meet all these oxidative activities within the same heterologous host is a milestone in synthetic biology of great value. In this work, a full set of ligninases was successfully co-secreted by S. cerevisiae. Expression cassettes were constructed to harbor laboratory evolved versions of versatile peroxidase, laccase, unspecific peroxygenase and aryl alcohol oxidase while a panel of different promoters/terminator pairs was used to circumvent metabolic burdens and expression constraints. As such, this artificial secretome produced by S. cerevisiae (white-rot yeast, WRY) could be used as laboratory model to help answer key questions in the deconstruction of lignin in nature at the time that could work like workhorse for the production of biofuels and biomaterials. Gonzalez-Perez, D. and Alcalde, M. (2014). Assembly of evolved ligninolytic genes in Saccharomyces cerevisiae. Bioengineered 5:254-263. Alcalde, M. (2015). Engineering the ligninolytic enzyme consortium. Trends in Biotechnology 33:155-162

Constructing topological models by symmetrization: A PEPS study

Symmetrization of topologically ordered wavefunctions is a powerful method for constructing new topological models. Here, we study wavefunctions obtained by symmetrizing quantum double models of a group $G$ in the Projected Entangled Pair States (PEPS) formalism. We show that symmetrization naturally gives rise to a larger symmetry group $\tilde G$ which is always non-abelian. We prove that by symmetrizing on sufficiently large blocks, one can always construct wavefunctions in the same phase as the double model of $\tilde G$. In order to understand the effect of symmetrization on smaller patches, we carry out numerical studies for the toric code model, where we find strong evidence that symmetrizing on individual spins gives rise to a critical model which is at the phase transitions of two inequivalent toric codes, obtained by anyon condensation from the double model of $\tilde G$.Comment: 10 pages. v2: accepted versio

Selección de conexiones de acero para zonas sísmicas con base en criterios de confiabilidad

Los hallazgos encontrados a raíz del terremoto de Northridge en 1994 han atraído actualmente la atención de los especialistas, sobre todo en cuanto a los problemas de diseño y seguridad de las conexiones soldadas para estructuras ubicadas en zonas sísmicas. Para equilibrar la seguridad requerida deben tomarse decisiones en relación con los costos para prevenir la posibilidad de excederse algún estado límite de servicio. Las técnicas de confiabilidad estructural proporcionan el marco adecuado para incluir las incertidumbres inherentes en el proceso de diseño. La formulación propuesta permite apoyar a diseñadores y a constructores para la selección del tipo de conexión más conveniente para las zonas sísmicas.Los hallazgos encontrados a raíz del terremoto de Northridge en 1994 han atraído actualmente la atención de los especialistas, sobre todo en cuanto a los problemas de diseño y seguridad de las conexiones soldadas para estructuras ubicadas en zonas sísmicas. Para equilibrar la seguridad requerida deben tomarse decisiones en relación con los costos para prevenir la posibilidad de excederse algún estado límite de servicio. Las técnicas de conÀabilidad estructural proporcionan el marco adecuado para incluir las incertidumbres inherentes en el proceso de diseño. La formulación propuesta permite apoyar a diseñadores y a constructores para la selección del tipo de conexión más conveniente para las zonas sísmicas

Photoperiod-sensitivity genes (Ppd-1) : quantifying their effect on the photoperiod response model in wheat

Coupling anthesis date to the most suitable environmental conditions is critical for wheat (Triticum aestivum L.) adaptation and yield potential. Development to anthesis is controlled by temperature and photoperiod. Response to photoperiod is chiefly modulated by Ppd-1 genes, but their effect on the quantitative response to photoperiod of (i) time to anthesis and (ii) pre-anthesis phases remains largely unknown. A photoperiod-sensitive spring cultivar, Paragon, and near-isogenic lines of it carrying different combinations of Ppd-1a insensitivity alleles were tested under a wide range of photoperiods, including switches in photoperiod at the onset of stem elongation. Using multimodel inference we found that Ppd-1a alleles reduced photoperiod sensitivity of (i) emergence to anthesis and (ii) emergence to onset of stem elongation, both in a less than additive manner, while threshold photoperiod and intrinsic earliness were unaffected. Sensitivity to current photoperiod from onset of stem elongation to flag leaf and from then to anthesis was milder than for previous phases and was not related to variability in Ppd-1. However, ‘memory’ effects of previously experienced photoperiod on the duration from onset of stem elongation to flag leaf were related to variability in Ppd-1. The characterization and quantification provided here of the effects on development of Ppd-1 allelic combinations should help increase accuracy of genotype-to-phenotype models in predicting wheat phenology.EEA PergaminoFil: Perez Gianmarco, Thomas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección Ecofisiología; Argentina. CONICET-UNNOBA.CITNOBA; ArgentinaFil: Severini, Alan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección Ecofisiología; ArgentinaFil: González, Fernanda G. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección Ecofisiología; Argentina. CONICET-UNNOBA.CITNOBA; Argentin

Wheat Ppd-1 allelic combination modulates photoperiod sensitivity

ABSTRACT: a model linking Ppd-1 allelic composition to photoperiod response curve would allow replacing expensive and time consuming phenologic trials. In Ppd-1 near isogenic lines grown under different photoperiods we observed that Ppd-1a “insensitivity” alleles decreased photoperiod sensitivity for the whole cycle to anthesis, with negligible effect on threshold photoperiod or intrinsic earliness. Photoperiod sensitivity for the first half of the cycle (emergence to onset of stem elongation) responded similarly. Photoperiod response for the second half (onset of stem elongation to anthesis) was milder. After validation, this model would allow to predict photoperiod response of any genotype, given its Ppd-1 allelic combination.EEA PergaminoFil: Perez Gianmarco, Thomas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; ArgentinaFil: Severini, Alan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; ArgentinaFil: González, Fernanda. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; Argentin

Confiabilidad de puentes de concreto presforzado dañados por corrosión

Los puentes vehiculares con frecuencia sufren daños por corrosión, sobre todo, si están ubicados en la costa o si están expuestos a la humedad o impactos químicos. Por tanto, es conveniente contar con recomendaciones técnicas para evaluar su efecto en la seguridad estructural y proveer condiciones aceptables para la operación y el mantenimiento del puente. En este artículo se determina la variación del índice de confiabilidad de Cornell en función del tiempo en una viga en un puente vehicular simplemente apoyado, mediante el análisis del comportamiento en los cambios en los momentos de agrietamiento de las secciones transversales de una viga de concreto presforzado de sección cajón, obtenidos a partir de sus diagramas momento-curvatura. El análisis estadístico se realizó mediante simulación de Monte Carlo considerando como variables aleatorias la resistencia del concreto, el área transversal de acero de presfuerzo y la carga viva, y como variables deterministas las dimensiones de los elementos y la carga muerta. De los resultados obtenidos se observa que, a partir del inicio de la corrosión del acero de presfuerzo, en los primeros 4 años la variación en el índice de confiabilidad resultó poco significativa, mientras que en los años subsecuentes se presenta lo contrario disminuyendo a valores menores de 1.75 a partir de 6 años de iniciada la corrosión, lo cual no garantiza condiciones de operación aceptables para la estructura

How to enhance labor provisions in IIAs

Labor provisions in IIAs should focus on corporate activity rather than governmental action. In order to encourage corporations to embrace the highest available international standards, labor provisions in IIAs should make reference to multilateral instruments that entail market-based incentives to promote labor rights on a CSR basis