Running Economy: Reproductibility at submaximal high speed

INTRODUCTION: The running economy (RE) has been traditionally determined by measuring the steady-state consumption of oxygen at a specific speed; however few studies has been designed to evaluate the reproductibility of the RE at a high rate of maximum oxygen consumption after repeated submaximal efforts within the same session. PURPOSE: The purpose of this study was valuate if the reproductibility of running economy at submaximal high speed could be affected by two previous submaximal efforts. METHODS: In this study participated 19 subjects (mean±SD; age, 21.8±2.5 years; body mass, 71.0±10.6 and height, 175.2±8.1). During three days of assessment separately for at least 24h of recovery, subjects performed the following tests. Day 1 a maximum incremental test, to determine the intensities. Day 2 a test of running economy at 80% of VO2max. Day 3 a test of running economy at 30, 70 and 80% of VO2max separated by 5 min of recovery. t-student test was conducted to measure test-retest differences in RE the p value were set al ≤0.05. RESULTS: No significant differences were found in the Running Economy at 80% of VO2max determined in both economy tests RE 220.1± 21.6vs 219.6±20.6 (ml·kg-1·km-1), ICC; 0.92, CV; 4.4 ± 2.6. CONCLUSION: The results of the present study showed exercises sessions at 30 and 70 of VO2max performed before the submaximal exercise test (80% of VO2max) did not affected the RE during an exercise test performed at 80% of VO2max

Life on the ice-edge: Paleoenvironmental significance of the radiolarian species Amphimelissa setosa in the northern hemisphere

The high-latitude Northern Hemisphere is a key region in the global climate balance. Variations in sea-ice extent affect biological productivity, CO2 exchange and carbon drawdown. Marine proxies indicative of proximity of the ice-marginal zone are therefore essential to understand these processes. Amphimelissa setosa is nowadays a dominant radiolarian species in the Arctic basin and very abundant in the high-latitude North Atlantic. This species, now absent from the North Pacific, has been widely used as a qualitative proxy of modern and past environmental conditions in the high-latitude Northern Hemisphere. Using our new and published data on the distribution of A. setosa in plankton, sediment trap, surface sediment and downcore samples, we provide a quantitative ecological context for the occurrence of this species. We find that the optimal depth and season of A. setosa in the modern North Atlantic and the Chukchi Sea are 160 m and the late boreal summer/early fall (August–October), respectively. A regression model combining environmental variables (temperature, salinity, silicate and chlorophyll-a concentrations, apparent oxygen utilization, sea-ice) at that season and depth, are able to explain 43% of the distribution of this species in surface sediments. Based on these new findings, we conclude that the presence of A. setosa in surface sediments is closely related to high primary production in the proximity of the sea-ice and areas of ice rafting. The onset of this species started at ca. 1.5 Ma in the North Pacific, linked to a gradual cooling, increased silica availability and southward advance of the ice-margins since the Early Pleistocene. Amphimelissa setosa’s decline in this region was likely caused by the development of a quasi-permanent halocline, perennial sea-ice and depletion of silica during marine isotope stage 4. In the high-latitude North Atlantic, the relative abundance of A. setosa appears to be related to cooling and supply of dissolved silica from the continent during ice-rafting events. The comprehensive approach taken in this study suggest that A. setosa is a useful proxy to explore past variations in the ice-cover in the high-latitude Northern Hemisphere.Shirshov Institute of Oceanology | Ref. 0149-2019-000

Potencial energético undimotriz en nodos costeros de México Parte 1: estimación energética

González-Ramírez, X., Hernández-Robles, I. A., & Barrios- Piña, H. (noviembre-diciembre, 2017). Potencial energético undimotriz en nodos costeros de México. Parte 1: estimación energética. Tecnología y Ciencias del Agua, 8(6), 5-22, DOI: 10.24850/j-tyca-2017-06-01.   En esta primera etapa de la investigación se explora, analiza y estima el potencial energético del oleaje en aguas costeras mexicanas. La estimación del potencial energético undimotriz desarrollado en este trabajo proporciona un panorama preliminar para el diseño de sistemas de generación distribuida, considerados como sistemas oportunos para el desarrollo regional sustentable. Actualmente la tecnología para el uso de energías renovables a partir de fuentes oceánicas es emergente, lo cual la convierte en una alternativa atractiva para la sustentabilidad energética. México está rodeado por dos océanos, lo que le permite contar con un gran recurso natural, económico y energético; su mar territorial se extiende aproximadamente hasta unos 22.2 km (12 millas náuticas) mar adentro a partir de la línea de costa, por lo que es primordial el análisis y la investigación del potencial energético del oleaje en su mar territorial en la búsqueda del aprovechamiento óptimo para la conversión de energía por oleaje (CEO) a eléctrica; así como proporcionar una perspectiva de lugares atractivos para el reto de implementación y diseño óptimo de microredes eléctricas. La estimación de potencia y parámetros, como altura significativa y periodicidad del oleaje obtenidos en este trabajo, se utilizan como datos de entrada para el diseño de generadores eléctricos lineales, dispositivos necesarios para la conversión de energía

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Spatiotemporal effects of Hurricane Ivan on an endemic epiphytic orchid: 10 years of follow-up

Background: Hurricanes have a strong influence on the ecological dynamics and structure of tropical forests. Orchid populations are especially vulnerable to these perturbations due to their canopy exposure and lack of underground storage organs and seed banks. Aims: We evaluated the effects of Hurricane Ivan on the population of the endemic epiphytic orchid Encyclia bocourtii to propose a management strategy. Methods: Using a pre- and post-hurricane dataset (2003–2013), we assessed the population asymptotic and transient dynamics. We also identified the individual size-stages that maximise population inertia and E. bocourtii’s spatial arrangement relative to phorophytes and other epiphytes. Results: Hurricane Ivan severely affected the survival and growth of individuals of E. bocourtii, and caused an immediate decline of the population growth rate from λ = 1.05 to λ = 0.32, which was buffered by a population reactivity of ρ1 = 1.42. Our stochastic model predicted an annual population decrease of 14%. We found an aggregated spatial pattern between E. bocourtii and its host trees, and a random pattern relative to other epiphytes. Conclusion: Our findings suggest that E. bocourtii is not safe from local extinction. We propose the propagation and reintroduction of reproductive specimens, the relocation of surviving individuals, and the establishment of new plantations of phorophytes.This work was supported by the Inter-ministerial Commission for Science and Technology under Grant [CICYT-Spain, Project CGL2015-69985-R]; and the Havana Project of the University of Alicante