Trophic ecology of the Endangered Darwin's frog inferred by stable isotopes

Indexación: Scopus.Acknowledgements. We thank Dr. Mauricio González-Chang for his contribution to invertebrate identification and Sally Wren for the revision of an earlier version of the manuscript. We are also extremely grateful to Tomás Elgueta Alvarez for providing Video S1. B.E.M.B. has a fellowship awarded by Universidad Andres Bello. This research project was approved by the Bioethics Committee at the Universi-dad Andres Bello, Chile (N°13/2015), and by permits N°5666/2013, N°230/2015, and N°212/2016 of the Chilean Agriculture and Livestock Service, and N°026/2013 and N°11/2015 IX of the Chilean National Forestry Corporation. This study was funded by the Dirección General de Investi-gación y Doctorados, Universidad Andres Bello, through grant N°DI-53-11/R and national funds through FONDE CYT N°11140902 and 1181758 (to C.S.A.).Darwin's frogs Rhinoderma spp. are the only known mouth-brooding frogs on Earth. The southern Darwin's frog, R. darwinii, is found in the temperate forests of southern South America, is listed as Endangered and could be the only extant representative of this genus. Based on stomach contents, invertebrate prey availability and stable isotope analysis, we determined for the first time trophic ecological parameters for this species. Our results showed that R. darwinii is a generalist sit-and-wait predator and a secondary consumer, with a trophic position of 2.9. Carbon and nitrogen isotope composition indicated that herbivore invertebrates are their main prey, detected in 68.1% of their assimilated food. The most consumed prey included mosquitoes, flies, crickets, grasshoppers and ants. Detritivore and carnivore invertebrates were also ingested, but in lower proportions. Our results contribute to a better understanding of the feeding habits of this fully terrestrial amphibian and provide the first insight into their role linking low forest trophic positions with intermediate predators. We provide valuable biological information for in situ and ex situ conservation which can be used when developing habitat protection, reintroduction and captive breeding programmes. As revealed here, stable isotope analysis is a valuable tool to study the trophic ecology of highly endangered and cryptic species. © The authors 2018.https://www.int-res.com/abstracts/esr/v36/p269-278

The influence of early literacy competences on later mathematical attainment: Evidence from TIMSS & PIRLS 2011

Children’s competence levels in numeracy and literacy before or at school onset are good predictors of their attainment over the school years. Nevertheless, there are large differences in the level of numeracy and literacy knowledge among children at school entry. This initial knowledge gap has long-lasting negative consequences for the poor performers. Here we used international secondary data from the PIRLS&TIMSS 2011 as well as TIMSS 2011, including background data collected with the Learning to Read Survey, to identify early literacy practices that predict later mathematical attainment. Previous studies conducted using the same dataset have reported that early numeracy and literacy abilities before school onset (as reported by parents) are associated with students’ later mathematical and reading attainment, respectively. Nevertheless recent theoretical frameworks of early mathematical development include certain literacy skills as an independent predictors of mathematical performance. Using ordinary least square regression models we found that early numeracy competences consistently predicted later mathematical attainment while the effects of early literacy competences were variable and not always significant for the individual countries. Results also showed a stronger influence of early reading abilities than of early writing abilities on later mathematical attainment. The identified effects were independent of children’s gender, home resources for learning, parents’ highest education and occupation level, student years of pre-school attendance and early numeracy abilities. This report complements and extents previous body of research by determining the relative impact that early literacy skills have on later mathematical attainment across EU countries. Findings highlight the importance of including numeracy and literacy practices in the preprimary curriculum as well as the challenges of implementing ECEC curricula on the basis of identified best practices from international research

Diseño de un observador y un controlador de velocidad de un motor DC por modos deslizantes

En este artículo se presenta una estructura de estimación y control de estados mediante modos deslizantes para un modelo lineal. Se presenta un sistema mecánico de un Motor DC, al cual se le diseñaran un observador y un controlador deslizante de primer y segundo orden. Los resultados se comparan con un diseño de un PID. Los dos diseños se prueban ante cambios de referencia, perturbaciones y ruido. In this paper a structure for estimation and control of states using sliding modes is presented for a linear model. A mechanical system of a DC motor is presented with a designed observer and a sliding controller of first and second order. The results are compared with a design of a PID. The two designs are tested against reference changes, disturbances and noise. — In this paper a structure for estimation and control of states using sliding modes is presented for a linear model. A mechanical system of a DC motor is presented with a designed observer and a sliding controller of first and second order. The results are compared with a design of a PID. The two designs are tested against reference changes, disturbances and noise. Keywords — Dc Motor, Observer, Sliding modes, State spaceUniversidad Nacional de ColombiaColciencia

Diseño de un Observador y un Controlador de velocidad de un motor DC por modos deslizantes

En este artículo se presenta una estructura de estimación y control de estados implementando las normas básicas de diseño de observadores y controladores mediante modos deslizantes para un modelo lineal. Se presenta un sistema mecánico de un Motor DC, al cual se le diseñaran un observador y un controlador deslizante de primero y segundo orden. Los resultados se comparan con un diseño de un PID. Los dos diseños se prueban ante cambios de referencia, perturbaciones y ruido.Universidad Nacional de ColombiaColcienciasBanco Mundia

Diferencias biomecánicas entre jugadores principiantes y de alto rendimiento en el lanzamiento en salto en baloncesto

La valoración y el aprendizaje de la técnica del lanzamiento en salto en baloncesto están relacionados con el conocimiento de la diferencias existentes en la ejecución técnica de este gesto entre jugadores con diferente nivel de rendimiento. Las diferencias obtenidas en las variables biomecánicas, entre los tres niveles de rendimiento establecido, ha aportado los aspectos claves en los que debemos focalizar nuestra atención durante la ejecución de este gesto. La muestra que se ha utilizado para realizar esta investigación ha estado compuesta por jugadores representativos de tres niveles de rendimiento, analizándose los lanzamientos mediante la metodología de análisis tridimensionales de video (50 Hz). En general, se puede afirmar que las diferencias halladas entre jugadores de alto rendimiento y jugadores en fase de aprendizaje tienen su fin en la fase final de salida del balón, en donde los jugadores con menor nivel de rendimiento lanzan en trayectoria ascendente del centro de gravedad con el objeto de poder aplicar al balón una gran velocidad de salida. Por lo que se deduce que no existe un modelo teórico universal aplicable del alto rendimiento a jugadores en proceso formativo.Peer Reviewe

Quantum-limited time-frequency estimation through mode-selective photon measurement

By projecting onto complex optical mode profiles, it is possible to estimate arbitrarily small separations between objects with quantum-limited precision, free of uncertainty arising from overlapping intensity profiles. Here we extend these techniques to the time-frequency domain using mode-selective sum-frequency generation with shaped ultrafast pulses. We experimentally resolve temporal and spectral separations between incoherent mixtures of single-photon level signals ten times smaller than their optical bandwidths with a ten-fold improvement in precision over the intensity-only Cram\'er-Rao bound.Comment: Six pages, three figures. Comments welcome

Disseny d'una peça de plàstic reciclat: Metodologia i aplicació

El disseny d'una peça de plàstic és un procés complex que implica el coneixement de les característiques mecàniques, elèctriques i físiques de la peça, i també dels processos de transformació. La principal tasca del dissenyador és traduir una sèrie de requeriments i idees prèvies en les dimensions i formes finals de la peça. Per aconseguir-ho de manera òptima, el dissenyador ha de fer ús, a banda de l'experiència i els coneixements propis, d'una metodologia de disseny adquada. L'objectiu d'aquest article és posar de manifest els passos a seguir quan s'aborda un disseny i la seva aplicació a una peça de plàstic fabricada en material reciclat

Diseño de una pieza de plástico reciclado: Metodología y aplicación

El mecanismo por el que se diseña una pieza de plástico es un proceso complejo que implica el conocimiento de las características mecánicas, eléctricas y físicas de la pieza y también de los procesos de transformación. La principal tarea del diseñador es traducir una serie de requerimientos e ideas previas en las direcciones y formas finales que tendrá la pieza. Para conseguirlo de forma optimizada el diseñador debe hacer uso de su experiencia, conocimientos y de una metodología de diseño adecuada. El objeto de este trabajo es poner de manifiesto los pasos a seguir cuando se aborda un diseño y la aplicación a una pieza de plástico fabricada en material reciclad

Pilot plant for the capture of ammonia from the atmosphere of pig and poultry farms using gas-permeable membrane technology

Gas-permeable membrane (GPM) technology is a possible solution to reduce ammonia (NH3) emissions from livestock housing. This paper presents the results obtained with an NH3-capture prototype based on the use of expanded polytetrafluoroethylene (ePTFE) membranes in real conditions in a gestating sow house and a free-range laying hen house, comparing them with the results obtained in controlled laboratory conditions for the same type of waste. The NH3 present in the air of the livestock housing was captured by reaction with an acidic solution flowing inside the membranes. The periods of continuous operation of the pilot plant were 232 days at the pig farm and 256 days at the poultry farm. The NH3 recovery rate at the end of those periods was 2.3 and 0.4 g TAN·m−2·d−1 in the pig and the poultry farms, respectively. The limiting factor for the capture process was the NH3 concentration in the air, with the highest recovery occurring in the most concentrated atmosphere. Differences in NH3 capture were observed between seasons and farms, with capture efficiencies of 1.62 and 0.33 g·m−2·d−1 in summer and 3.85 and 1.20 g·m−2·d−1 in winter for pig and poultry farms, respectively. The observed differences were mainly due to the higher ventilation frequency in the summer months, which resulted in a lower NH3 concentration inside the houses compared to the winter months. This is especially important when considering the real applicability of this technology. The results obtained suggest that GPM technology holds promise for limiting NH3 emissions from livestock housing with NH3 ambient concentrations close to 20 ppm or as part of manure storage facilities, given that it allows for recovery of nitrogen in a stable and concentrated solution, which can be used as a fertilizer