Nonclassical statistics of intracavity coupled χ(2)\chi^{(2)} waveguides: the quantum optical dimer

A model is proposed where two $\chi^{(2)}$ nonlinear waveguides are contained in a cavity suited for second-harmonic generation. The evanescent wave coupling between the waveguides is considered as weak, and the interplay between this coupling and the nonlinear interaction within the waveguides gives rise to quantum violations of the classical limit. These violations are particularly strong when two instabilities are competing, where twin-beam behavior is found as almost complete noise suppression in the difference of the fundamental intensities. Moreover, close to bistable transitions perfect twin-beam correlations are seen in the sum of the fundamental intensities, and also the self-pulsing instability as well as the transition from symmetric to asymmetric states display nonclassical twin-beam correlations of both fundamental and second-harmonic intensities. The results are based on the full quantum Langevin equations derived from the Hamiltonian and including cavity damping effects. The intensity correlations of the output fields are calculated semi-analytically using a linearized version of the Langevin equations derived through the positive-P representation. Confirmation of the analytical results are obtained by numerical simulations of the nonlinear Langevin equations derived using the truncated Wigner representation.Comment: 15 pages, 8 figures, submitted to Phys. Rev.

The Active Component of Aspirin, Salicylic Acid, Promotes Staphylococcus aureus Biofilm Formation in a PIA-dependent Manner

Aspirin has provided clear benefits to human health. But salicylic acid (SAL) -the main aspirin biometabolite- exerts several effects on eukaryote and prokaryote cells. SAL can affect, for instance, the expression of Staphyiococcus aureus virulence factors. SAL can also form complexes with iron cations and it has been shown that different iron chelating molecules diminished the formation of S. aureus biofilm. The aim of this study was to elucidate whether the iron content limitation caused by SAL can modify the S. aureus metabolism and/or metabolic regulators thus changing the expression of the main polysaccharides involved in biofilm formation. The exposure of biofilm to 2mM SAL induced a 27% reduction in the intracellular free Fe2+ concentration compared with the controls. In addition, SAL depleted 23% of the available free Fe2+ cation in culture media. These moderate iron-limited conditions promoted an intensificaron of biofilms formed by strain Newman and by S. aureus clinical isolates related to the USA300 and USA100 clones. The slight decrease in iron bioavailability generated by SAL was enough to induce the increase of PIA expression in biofilms formed by methicillin-resistant as well as methicillin-sensitive S. aureus strains. S. aureus did not produce capsular polysaccharide (CP) when it was forming biofilms under any of the experimental conditions tested. Furthermore, SAL diminished aconitase activity and stimulated the lactic fermentation pathway in bacteria forming biofilms. The polysaccharide composition of S. aureus biofilms was examined and FTIR spectroscopic analysis revealed a clear impact of SAL in a codY-dependent manner. Moreover, SAL negatively affected codY transcription in mature biofilms thus relieving the CodY repression of the ica operon. Treatment of mice with SAL induced a significant increase of S aureus colonization. It is suggested that the elevated PIA expression induced by SAL might be responsible for the high nasal colonization observed in mice. SAL-induced biofilms may contribute to S. aureus infection persistence in vegetarian individuals as well as in patients that frequently consume aspirin.Facultad de Ciencias Médica

Comentario sobre la reacción del iodo con la metionina. Técnicas iodimétricas para su valoración en muestras conteniendo proteínas

En este trabajo se estudian algunas técnicas iodimétricas para la dosificación d' e metionina. Después de haber ensayado diferentes pH y estudiado la.s posibles interferencias de las sustancias que más frecuentemente suelen ir asociadas a la metionina, se estabIecen los procedimientos para la valoración de metionina en medicamentos y otras muestras en cuya composición entra a formar parte alguna proteina. La determinación se practica a un pH 4,5 - 5 en un medio regulado con ácido acético-acetato sódico.Sorne iodimetric techniques are employed in this work for the purPose of evaluating of methionine. Arter having assayed various pH and studied the possible interference of sorne ·compounds that frequently accompany methionine the procedures are stablished for the titration of methionine in medicines and other samples in whose composition is integrated some protein. The determination is practised at pH 4,5 - 5 in a buffered solution with acetic acid and sodium acetate

Platforms and software systems for an autonomic internet

The current Internet does not enable easy introduction and deployment of new network technologies and services. This paper aims to progress the Future Internet (FI) by introduction of a service composition and execution environment that re-use existing components of access and core networks. This paper presents essential service-centric platforms and software systems that have been developed with the aim to create a flexible environment for an Autonomic Internet.Peer ReviewedPostprint (published version

Combining estimates of interest in prognostic modelling studies after multiple imputation: current practice and guidelines

Background: Multiple imputation (MI) provides an effective approach to handle missing covariate data within prognostic modelling studies, as it can properly account for the missing data uncertainty. The multiply imputed datasets are each analysed using standard prognostic modelling techniques to obtain the estimates of interest. The estimates from each imputed dataset are then combined into one overall estimate and variance, incorporating both the within and between imputation variability. Rubin's rules for combining these multiply imputed estimates are based on asymptotic theory. The resulting combined estimates may be more accurate if the posterior distribution of the population parameter of interest is better approximated by the normal distribution. However, the normality assumption may not be appropriate for all the parameters of interest when analysing prognostic modelling studies, such as predicted survival probabilities and model performance measures. Methods: Guidelines for combining the estimates of interest when analysing prognostic modelling studies are provided. A literature review is performed to identify current practice for combining such estimates in prognostic modelling studies. Results: Methods for combining all reported estimates after MI were not well reported in the current literature. Rubin's rules without applying any transformations were the standard approach used, when any method was stated. Conclusion: The proposed simple guidelines for combining estimates after MI may lead to a wider and more appropriate use of MI in future prognostic modelling studies

Competències i habilitats transversals entre geologia i arqueologia prehistòrica

En aquest treball es desenvolupa una proposta concreta per abordar alguns dels objectius pedagògics, com ara la transversalitat, el treball en equip o la necessitat d'incrementar els coneixements pràctics. La perspectiva des de la que s'ha realitzat ha estat la de la col·laboració interdisciplinària entre docents universitaris que treballen en dos àmbits científics ben diferents: geologia i arqueologia prehistòrica.S'ha desenvolupat una eina pedagògica on els estudiants poden desenvolupar habilitats i capacitats com les esmentades a partir del seguiment d'un cas d'estudi concret: la determinació i procedència dels elements petris utilitzats en la construcció del sepulcre megalític de Puigseslloses (Osona). La proposta es basa en el seguiment i la participació dels estudiants en tot el procés de la recerca: el plantejament del problema historicoarqueològic, la definició de les vies d'estudi concretes, el seu desenvolupament, l'obtenció de resultats i la seva discussió interdisciplinària.En este trabajo se desarrolla una propuesta concreta para abordar algunos de los objetivos pedagógicos, como la transversalidad, el trabajo en equipo o la necesidad de incrementar los conocimientos prácticos. La perspectiva desde la que se ha realizado ha sido la de la colaboración interdisciplinaria entre docentes universitarios que trabajan en dos ámbitos científicos bien distintos: Geología y Arqueología Prehistórica. Se ha desarrollado una herramienta pedagógica a través de la cual los estudiantes pueden desarrollar habilidades y capacidades como las mencionadas a partir del seguimiento de un caso de estudio concreto: la determinación y procedencia de los elementos pétreos utilizados en la construcción del sepulcro megalítico de Puigseslloses (Osona). La propuesta se basa en que los estudiantes sigan y participen en todo el proceso de la investigación, desde el planteamiento del problema histórico-arqueológico, la definición de las vías de estudio concretas, su desarrollo y la obtención de resultados, hasta su discusión interdisciplinaria.This study develops a specific proposal for addressing some of the educational goals of the EHEA such as transversality, teamwork and the need to increase practical knowledge. The perspective from which the study was conducted was interdisciplinary cooperation among university professors who work in two quite different fields of science: geology and prehistoric archaeology. A pedagogical tool was developed in which students can develop skills and abilities such as the ones mentioned above by pursuing a specific case study: the description and provenance of stone elements used to build the megalithic sepulchre in Puigseslloses (Osona). The proposal is based on students' following and participating in the entire research process: posing the historical-archaeological problem, defining the specific avenues of study, conducting the study, getting the results and holding an interdisciplinary discussion of these results

The Active Component of Aspirin, Salicylic Acid, Promotes Staphylococcus aureus Biofilm Formation in a PIA-dependent Manner

Aspirin has provided clear benefits to human health. But salicylic acid (SAL) -the main aspirin biometabolite- exerts several effects on eukaryote and prokaryote cells. SAL can affect, for instance, the expression of Staphyiococcus aureus virulence factors. SAL can also form complexes with iron cations and it has been shown that different iron chelating molecules diminished the formation of S. aureus biofilm. The aim of this study was to elucidate whether the iron content limitation caused by SAL can modify the S. aureus metabolism and/or metabolic regulators thus changing the expression of the main polysaccharides involved in biofilm formation. The exposure of biofilm to 2mM SAL induced a 27% reduction in the intracellular free Fe2+ concentration compared with the controls. In addition, SAL depleted 23% of the available free Fe2+ cation in culture media. These moderate iron-limited conditions promoted an intensificaron of biofilms formed by strain Newman and by S. aureus clinical isolates related to the USA300 and USA100 clones. The slight decrease in iron bioavailability generated by SAL was enough to induce the increase of PIA expression in biofilms formed by methicillin-resistant as well as methicillin-sensitive S. aureus strains. S. aureus did not produce capsular polysaccharide (CP) when it was forming biofilms under any of the experimental conditions tested. Furthermore, SAL diminished aconitase activity and stimulated the lactic fermentation pathway in bacteria forming biofilms. The polysaccharide composition of S. aureus biofilms was examined and FTIR spectroscopic analysis revealed a clear impact of SAL in a codY-dependent manner. Moreover, SAL negatively affected codY transcription in mature biofilms thus relieving the CodY repression of the ica operon. Treatment of mice with SAL induced a significant increase of S aureus colonization. It is suggested that the elevated PIA expression induced by SAL might be responsible for the high nasal colonization observed in mice. SAL-induced biofilms may contribute to S. aureus infection persistence in vegetarian individuals as well as in patients that frequently consume aspirin.Facultad de Ciencias Médica

Induction of defensive responses in sugarcane against Sugarcane mosaic virus with two bioproducts

Sugarcane (Saccharum spp.), main sugar crop worldwide, is affected by multiple pathogens. One of the most important viral diseases in this crop is mosaic, caused by Sugarcane mosaic virus (SCMV). This research was conducted with the objective of demonstrating the ability of two bioproducts to induce defenses response against this virus. The first based on the encapsulation of the endopolygalacturonase enzyme of the yeast Kluyveromyces marxianus CCEBI 2011 and another whose active principle is constituted by phenolic compounds produced by sugarcane in temporary immersion bioreactors. SP70-1284 cultivars susceptible to SCMV and resistant C323-68 were treated with the bioproducts and inoculated with SCMV. The severity of the infection, the accumulation of superoxide radicals and the expression of 10 defense-related genes were evaluated. The resistant cultivar did not show symptoms of infection during the development of the experiment, while in the susceptible the application of both bioproducts decreased the severity of the infection between 38.9 and 44.4% with respect to the control. The presence of superoxide radicals was observed in the first hours of sugarcane-SCMV interaction, while at 28 days’ post inoculation, a differentiated expression of three genes related to antiviral defense was observed. The ability of both bioproducts to induce defensive responses in sugarcane against SCMV was demonstrated