Detection of equine atypical myopathy-associated hypoglycin A in plant material: Optimisation and validation of a novel LC-MS based method without derivatisation

Hypoglycin A (HGA) toxicity, following ingestion of material from certain plants, is linked to an acquired multiple acyl-CoA dehydrogenase deficiency known as atypical myopathy, a commonly fatal form of equine rhabdomyolysis seen worldwide. Whilst some plants are known to contain this toxin, little is known about its function or the mechanisms that lead to varied HGA concentrations between plants. Consequently, reliable tools to detect this amino acid in plant samples are needed. Analytical methods for HGA detection have previously been validated for the food industry, however, these techniques rely on chemical derivatisation to obtain accurate results at low HGA concentrations. In this work, we describe and validate a novel method, without need for chemical derivatisation (accuracy = 84–94%; precision = 3–16%; reproducibility = 3–6%; mean linear range R2 = 0.999). The current limit of quantitation for HGA in plant material was halved (from 1μg/g in previous studies) to 0.5μg/g. The method was tested in Acer pseudoplatanus material and other tree and plant species. We confirm that A. pseudoplatanus is most likely the only source of HGA in trees found within European pastures

Convergencia mediática digital : el uso y consumo de los nuevos medios por mujeres catalanas

El consumo y la dinámica de las pantallas de comunicación han experimentado en el mundo un marcado aumento en los últimos años y los medios de comunicación tradicionales, con sus gramáticas y mercados perfectamente definidos, han evolucionado como consecuencia del protagonismo de Internet. La convergencia mediática reduce la distancia entre el emisor y el receptor, desapareciendo así la unidireccionalidad y desarrollando una comunicación horizontal que deja la pasividad, ya que el receptor adopta una actitud activa. En este artículo se dibuja el consumo de contenidos que realizan las mujeres en Cataluña, y cuál es el soporte utilizado en el marco de la convergencia mediática digital. Se describen los resultados obtenidos a raíz de combinar 6 grupos de discusión con 6 entrevistas en profundidad en dos grupos segmentados de la población en función de la edad y su formación: grupo infantil y juvenil. Se ha dado prioridad a los colectivos infantil y juvenil porque son los que marcan de forma influyente las tendencias a medio plazo, los que se han socializado con una serie de soportes que no existían anteriormente y los que son más polivalentes en el uso de los diversos soportes disponibles en el mercado. La población adulta no ha sido examinada en el estudio porque posee determinadas barreras de entrada, como la falta de competencias técnicas para el uso de los nuevos dispositivos

On the convergence of multi-level Hermite-Pad\'e approximants

In the present paper we prove a Stieltjes type theorem on the convergence of a sequence of rational functions associated with a mixed type Hermite-Pad\'e approximation problem of a Nikishin system of functions and analyze the ratio asymptotic of the corresponding Hermite-Pad\'e polynomials.Comment: 24 page

Consumo de Medios Digitales por niños y preadolescentes en Cataluña, España

The focus of this study is patterns of use of digital media, which are the most popular platforms and what control that parents impose on the consumption of digital media. We analyzed children aged between 7 and 10 years old and pre-teenagers aged between 11 and 12 years old. These groups are those who influence the medium-term trends. The results show that digital media are present in the everyday life of children, who regularly consume their preferred contents. They can be powerful if they can recognize and use their power in this culture of convergence as users.El objetivo este estudio es conocer los patrones de uso de los medios digitales, las plataformas más usadas y entender los controles parentales que se ejercen sobre niños de entre 7 y 10 años y preadolescentes de entre 11 y 12 años, los grupos que serán influenciados a medio plazo por las nuevas tendencias. Los resultados muestran que los medios digitales están presentes en la vida cotidiana de los niños, que consumen regularmente sus contenidos preferidos. Estos resultados pueden ser de gran alcance si es posible reconocer y utilizar su poder como usuarios en esta cultura de la convergencia digital

Equilibration of Concentrated Hard Sphere Fluids

We report a systematic molecular dynamics study of the isochoric equilibration of hard-sphere fluids in their metastable regime close to the glass transition. The thermalization process starts with the system prepared in a non-equilibrium state with the desired final volume fraction {\phi} but with a prescribed non-equilibrium static structure factor S_0(k; {\phi}). The evolution of the {\alpha}- relaxation time {\tau}{\alpha} (k) and long-time self-diffusion coefficient DL as a function of the evolution time tw is then monitored for an array of volume fractions. For a given waiting time the plot of {\tau}{\alpha} (k; {\phi}, tw) as a function of {\phi} exhibits two regimes corresponding to samples that have fully equilibrated within this waiting time ({\phi} \leq {\phi}(c) (tw)), and to samples for which equilibration is not yet complete ({\phi} \geq {\phi}(c) (tw)). The crossover volume fraction {\phi}(c) (tw) increases with tw but seems to saturate to a value {\phi}(a) \equiv {\phi}(c) (tw \rightarrow \infty) \approx 0.582. We also find that the waiting time t^(eq)_w({\phi}) required to equilibrate a system grows faster than the corresponding equilibrium relaxation time, t^(eq)({\phi}) \approx 0.27 \times [{\tau}{\alpha} (k; {\phi})]^1.43, and that both characteristic times increase strongly as {\phi} approaches {\phi}^(a), thus suggesting that the measurement of equilibrium properties at and above {\phi}(a) is experimentally impossible