The impact on plant communities of an invasive alien herb, Oenothera drummondii, varies along the beach-coastal dune gradient

One of the major threats to the diversity of coastal dunes is the expansion of invasive species, such as Oenothera drummondii subsp. drummondii (Onagraceae). In southwestern Spain, we studied the impact of this American invasive on community structure and composition along a beach-dune gradient (beach, foredune, and inland dunes). Differences in density, biomass, and the cover of O. drummondii, the cover of perennial and annuals/biennials species, and Shannon diversity index H’ and dominance λ were compared between invaded and uninvaded sectors. We observed that the intensity and impact of the invasion by O. drummondii varies along the beach-dune gradient. The abundance of the invasive plant increased inland and in consequence, its impact on species richness and composition was highest in inland dunes. Here, plant cover of O. drummondii represented 57.9% of total plant cover; species richness was reduced (with 3.3 fewer species per 2 × 2m plot), diversity H’ was lower while dominance λ was higher. At a broader scale, species richness in the invaded sector was 25% larger than in the uninvaded sector, because of the presence of ruderal species. Species composition also was modified after the invasion. The abundance of a keystone native species was largely reduced (Ammophila arenaria), and some natives became locally extinct (Otanthus maritimus, Eryngium maritimum, Medicago marina and Elymus farctus). We conclude that the high environmental severity of the beach and foredunes results in a reduced invasion and impact of O. drummondii, whereas the milder conditions of inland dunes promote its expansion. The shift in community structure and composition can have an increasing domino effect and thus monitoring, and mitigation actions are necessary. When doing so, the environmental heterogeneity of the beach-dune gradient should be considered, given its relevance in the invasion process.Ministerio de Economía y Competitividad CGL2015-65058-RConsejo Nacional de Ciencia y Tecnología (CONACYT) 779

Multiple seed dispersal modes of an invasive plant species on coastal dunes

Beach evening-primrose (Oenothera drummondii subsp. drummondii) is a perennial herb native to the coastal dunes of the Gulf of Mexico and southeastern USA. During the last century, the species was unintentionally introduced into coastal dune systems around the world. The purpose of this study was to explore the means of dispersal of this invasive in the newly established populations on the coastal dunes of Spain and to determine if they contribute significantly to the invasion process. After reconstructing the history of its spread in Spain from available records, we tested whether dispersion by marine currents can be a mechanism of colonization at regional scale, and whether the presence of native vertebrate participate in the expansion process at local scale. Through laboratory experiments, we demonstrated that the seeds of O. drummondii can be dispersed by seawater, since 0.63% present both buoyancy in seawater and subsequent germination after being washed with fresh water. This capacity for dispersal by marine currents could explain both the expansion of the species along the southwestern coast of Spain and the maintenance of its populations following disturbances such as storms. We also demonstrated that Iberian Hares and European Rabbits can disperse the seeds by endozoochory; seeds recovered from faecal pellets of these species were capable of germination (73 and 63%, respectively). Oenothera drummondii has become an invader only in coastal dunes where these dispersers are present, and with no control actions to regulate their populations. In conclusion, O. drummondii is an alien species with varying dispersal methods, polychory. This helps maintain already established populations and disperses seeds at a regional level, depending on the incidence of storms and the presence or absence of rabbits and hares for efficient local seed dispersion. Thus, management actions that restrict marine and animal dispersal likely have the benefit of limiting the invasive potential of O. drummondii.Consejo Nacional de Ciencia y Tecnología (CONACYT) 7799Ministerio de Economía y Competitividad CGL2015-65058-

Recovery of Beach-Foredune Vegetation after Disturbance by Storms

Beaches and foredunes are characterized by being exposed to harsh environmental restrictions mainly due to salt spray, burial by sand and occasional storms. In response to this, plant species from these habitats have adaptations that allow them not only to survive in these environments, but also to recover after the impact of disturbances such as severe storms. In this study, we had the opportunity to study vegetation recovery on the coast of Huelva, Spain, after the impact of a strong winter storm in 2017 which severely affected the vegetation growing on the beach and foredune. Species composition and abundance of vegetation was compared before (2013) and after (2018) the storm hit the coast in 2017. The results show that the effects of the storm were still evident a year later. Native species, mainly perennials, were able to recover almost completely to predisturbance levels. In contrast, the invasive species, Oenothera drummondii, which was abundant before the storm, disappeared from the beach and its presence in the foredune was greatly reduced. Given the forecasts of sea level rise and the increased frequency and intensity of storms, it is necessary to sustain and reinforce the natural coastal sectors where native plant communities maintain the resilience of coastal ecosystems when impacted to these disturbances.Consejo Nacional de Ciencia y Tecnología (CONACYT) 7799Ministerio de Economía y Competitividad CGL2015-65058-

Biomechanical assessment of aerodynamic resistance in proffessional cyclists: methodological aspects

El objetivo de este estudio fue medir y comparar, a través de un túnel de viento, la resistencia aerodinámica (RA) en cinco ciclistas profesionales; y establecer modificaciones que mejoraran el rendimiento. Cinco ciclistas profesionales del equipo Kelme-Costa Blanca fueron objeto de estudio, cuatro en bicicleta aerodinámica y uno en bicicleta estándar. De nuestros resultados concluimos que estableciendo pequeñas modificaciones en los manillares, colocándolos en una posición más rentable, se puede reducir la R

Light scattering resonances in small particles with electric and magnetic properties

Lorenz–Mie resonances produced by small spheres are analyzed as a function of their size and optical properties ( ε≷0 , μ≷0 ). New generalized (μ≠1) approximate and compact expressions of the first four Lorenz–Mie coefficients ( a1 , b1 , a2 , and b2 ) are calculated. With these expressions and for small particles with various values of ε and μ, the extinction cross section (Qext) is calculated and analyzed, in particular for resonant conditions. The dependence on particle size of the extinction resonance, together with the resonance shape (FWHM), is also analyzed. In addition to the former analysis, a study of the scattering diagrams for some interesting values of ε and μ is also presented

Optimized synthesis of di, tri and tetrafused pyridazinium cations

By combining two complementary statistical techniques (fractional factorial experimental design and simplex operation) the synthesis of the parent pyrido[1,2-b]-pyridazinium cation has been successfully carried out (the yield was improved from less than 10 to 65%) by basic condensation of 2-methyl-1-aminopyridinium mesitylenesulfonate and [1,4]dioxane-2,3-diol. Using the optimized reaction conditions, other related heterocyclic cations could be prepared, and two interesting examples are now reported.Ministerio de Educación y CienciaUniversidad de Alcal

Update on atmospheric neutrinos

We discuss the impact of recent experimental results on the determination of atmospheric neutrino oscillation parameters. We use all published results on atmospheric neutrinos, including the preliminary large statistics data of Super-Kamiokande. We reanalyze the data in terms of both vμ → vτ and vμ → ve channels using new improved calculations of the atmospheric neutrino flux. We compare the sensitivity attained in atmospheric neutrino experiments with those of accelerator and reactor neutrino oscillation searches, including the recent CHOOZ experiment. We briefly comment on the implications of atmospheric neutrino data in relation to future searches for neutrino oscillations with long baselines, such as the K2K, MINOS, ICARUS, and NOE experiments.MC is obtained by folding a prediction for the atmospheric neutrino flux with the properties of every individual detector through a Monte Carlo ~MC! procedure. Apart from studying the impact of the new data, our motivation for the present reanalysis of atmospheric neutrino data is theoretical. In this regard, we first of all include the results of a recent calculation of the atmospheric neutrino fluxes as a function of zenith angles @11#, including the muon polarization effect @12#. Moreover, we develop an independent procedure for the comparison of results from different experiments. We demonstrate that our theoretical calculation of the energy distribution of the event rates is in good agreement with the MC expectations. The comparison of the experimental results presented below thus reflects the significance of the atmospheric neutrino anomaly and provides evidence for neutrino oscillations. In this paper we analyze the impact of recent experimental results on atmospheric neutrinos from Super-Kamiokande and Soudan2 on the determinations of atmospheric neutrin

Aptitud de los alumnos de pregrado de la carrera de Medicina ante dos modelos de evaluación: El caso de Endocrinología.

Antecedentes: La Facultad de Medicina de la UANL inició en agosto del 2006 un nuevo plan de estudios y un modelo educativo basado en el aprendizaje y en la participación más intensa del alumno. Esta modificación en la estrategia de formar a los futuros médicos requiere ser evaluada científicamente con el propósito de medir si los cambios esperados con la implementación del plan de estudios y del modelo educativo, están ocurriendo. Objetivo: Comparar la aptitud de los alumnos del curso de pregrado de endocrinología ante dos métodos de evaluación. Método: Comparación de dos exámenes como proceso de evaluación ante dos planteamientos académicos: el actual (basado en la aplicación del conocimiento, casos clínicos) y el próximo anterior (basado en la memorización de conocimientos). Se contrastó la aptitud de los alumnos del nuevo plan de estudios (n = 74) vs. los alumnos del plan anterior (n = 137), ante el mismo examen. Resultados: Los alumnos del nuevo plan de estudios tuvieron una aptitud casi idéntica al ser evaluados con el examen actual y con el aplicado en ciclos anteriores (73.4 + 7.8 vs. 72.9 + 10.7, respectivamente) p = 0.2553. El porcentaje de aprobación fue de un 71 vs. 67%. Al comparar la aptitud de los alumnos del plan actual y el anterior ante un mismo examen, la aptitud fue muy favorable en el grupo de alumnos del nuevo plan de estudios (74.7 ± 10.7 vs. 56.0 ± 9.3), p< 0.0001. Conclusiones: La combinación de un modelo educativo centrado en el aprendizaje, en una acentuada participación del alumno en la clase, en una forma de evaluación que incentiva el estudiar la clase diaria y en la aplicación de exámenes dirigidos a evaluar la aplicación del conocimiento como en la vida real de un médico, son los aspectos que debemos fortalecer en el proceso de formación de nuestros futuros médicos

Validity of lactic acid in an interval stress test (Probst test) to determine a soccer player´s anaerobic threshold

P. 3-17El objetivo fue comprobar la validez de un protocolo de esfuerzo incremental, progresivo, máximo y discontinuo (Test de Probst) para valorar el umbral anaeróbico (UAn), interválico y específico en futbolistas profesionales mediante un recorrido que simula el esfuerzo desarrollado en este deporte. Para ello se determinó el UAn de 23 jugadores de la Liga de Fútbol Profesional (1ª División Española) que realizaron el Test de Probst, y 48h después un Test Lactacidémico en el propio campo de fútbol y sobre el mismo recorrido. Los resultados muestran elevadas y significativas correlaciones (r=0.79 y p<0.001) entre las frecuencias cardiacas y velocidades en el UAn obtenidas en ambos tests. En el Test de Probst el UAn se identificó tanto de forma manual como matemática, siendo la primera la que mayor relación presentó con el Test Lactacidémico, sobre todo cuando se analiza la velocidad en el UAn. En conclusión, el Test de Probst es un test de campo válido para determinar el UAn interválico (UAnI) de jugadores de fútbol, como indicador del grado de resistencia específica propia del futbolista, y que permite establecer grupos de trabajo y determinar el porcentaje de mejora de la misma en periodos sensibles como la pretemporada o valorar su nivel de condición física a lo largo de la temporadaS