Relationships between spawn quality and biochemical composition of eggs and hatchlings of Octopus vulgaris under different parental diets

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Regeneration niche of the Canarian juniper : the role of adults, shrubs and environmental conditions

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Valorización de ceniza de bagazo de caña de la industria azucarera Nicaragüense como sustituto parcial al cemento Portland

In this study, the use of the ashes of sugarcane bagasse (ASB) from Monte Rosa sugarcane mill (Nicaragua) as an alternative material to Portland Cement (PC) was evaluated. The evaluation was performed through studies of advanced characterization and mechanical properties in pastes with 15% and 45% substitution of PC. Moreover, 100% PC pastes were used as reference. The mechanical resistance (MR), the consumption of calcium hydroxide and the development of reaction products were measured. The results showed that the highest values of MR were obtained for the reference pastes, thus indicating that the MR decreased with increase in the degree of substitution. Through the analysis of X-ray diffraction (XRD) and thermal analysis TGA / DTA was found that the consumption of Ca(OH)2 gave rise to the formation of CSH gel as the main product of hydration and caused the gain in the mechanical properties. The reaction products were observed by scanning electron microscopy (SEM) where the mechanism in solid state was noticeable. From this result, it can be concluded that the ASB are pozzolanic material with a better reactivity to Ca(OH)2 with 15% of substitution. DOI: http://dx.doi.org/10.5377/nexo.v27i2.1944En este estudio, se presenta la valoración del uso de las cenizas de bagazo de caña (CBCA) proveniente del Ingenio Monte Rosa(Nicaragua) como material alternativo al cemento Portland (CP) mediante estudios de caracterización avanzada y propiedadesmecánicas, en pastas endurecidas de CP sustituidas en 15 y 45 % por CBCA; además se utilizó pastas de referencia con 100 %CP sobre las cuales se evaluó las resistencias mecánicas (RM), el consumo de hidróxido de calcio y el desarrollo de losproductos de reacción. Los resultados revelaron que los valores más altos de RM reportados fueron por el sistema de referencia,indicando que la RM disminuyó con el incremento en el porcentaje de sustitución. Por medio de los análisis de difracción derayos X (DRX) y análisis térmicos por ATG/ATD fue demostrado el consumo de Ca(OH)2 que dio lugar a la formación de gelCSH como principal producto de hidratación y responsable de la ganancia de las propiedades mecánicas. Los productos dereacción fueron observados también por microscopia electrónica de barrido (MEB) donde el mecanismo en estado sólido fuenotable. A partir de estos resultados se puede concluir que las CBCA son un material puzolánico con una mejor reactividadfrente al Ca(OH)2 con 15 % de sustitución.DOI: http://dx.doi.org/10.5377/nexo.v27i2.194

Active Galactic Nuclei at the Crossroads of Astrophysics

Over the last five decades, AGN studies have produced a number of spectacular examples of synergies and multifaceted approaches in astrophysics. The field of AGN research now spans the entire spectral range and covers more than twelve orders of magnitude in the spatial and temporal domains. The next generation of astrophysical facilities will open up new possibilities for AGN studies, especially in the areas of high-resolution and high-fidelity imaging and spectroscopy of nuclear regions in the X-ray, optical, and radio bands. These studies will address in detail a number of critical issues in AGN research such as processes in the immediate vicinity of supermassive black holes, physical conditions of broad-line and narrow-line regions, formation and evolution of accretion disks and relativistic outflows, and the connection between nuclear activity and galaxy evolution.Comment: 16 pages, 5 figures; review contribution; "Exploring the Cosmic Frontier: Astrophysical Instruments for the 21st Century", ESO Astrophysical Symposia Serie

Forest Biodiversity Assessment in Peruvian Andean Montane Cloud Forest

Cloud forests are unusual and fragile habitats, being one of the least studied and least understood ecosystems. The tropical Andean dominion is considered one of the most significant places in the world as rega rds biological diversity, with a very high level of endemism. The biodiversity was analysed in an isolated remnant area of a tropical montane cloud forest known as the ?Bosque de Neblina de Cuyas?, in the North of the Peruvian Andean range. Composition, structure and dead wood were measured or estimated. The values obtained were compared with other cloud forests. The study revealed a high level of forest biodiversity, although the level of biodiversity differs from one area to another: in the inner areas, where human pressure is almost inexistent, the biodiversity values increase. The high species richness and the low dominance among species bear testimony to this montane cloud forest as a real enclave of biodiversity

Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy

During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the Swift data into on- and off-anomaly spectra to characterize the soft excess via spectral fitting. The cause of the spectral differences is likely due to a change in the intrinsic spectrum rather than to variable obscuration or partial covering. The Chandra spectra have lower signal-to-noise ratios, but are consistent with the Swift data. Our preferred model of the soft excess is emission from an optically thick, warm Comptonizing corona, the effective optical depth of which increases during the anomaly. This model simultaneously explains all three observations: the UV emission-line flux decrease, the soft-excess increase, and the emission-line anomaly

Ecological determinants of species composition in the forest vegetation of Tuscany, Italy

Background and aims - Monitoring plots are important tools for forest management and can help to predict the directions of changes in species composition in a changing climate. Understanding ecological processes in forest communities is one of the most important goals for a proper management of these ecosystems and for biodiversity conservation. Methods - The compositional data recorded within an inventory were used here to describe plant community composition and investigate how it is affected by climatic or other ecological factors. Six large forests along an altitudinal gradient owned and managed by the regional administration of Tuscany were chosen as study sites. 109 plots of 400 m2 were randomly located according to a stratified sampling design, with the number of plots in each forest related to forest size. The number of stems and DBH of all plants with DBH > 3 cm were recorded for each woody species within each plot. In addition, the frequency of understory species was recorded by twelve subplots of 0.25 m2, randomly located within each quadrant of each plot. Key results - Elevation, soil water capacity, minimum precipitation, annual precipitation/temperature ratio and maximum temperature were found to be the explanatory variables for the gradient of woody species composition. After removing plantation plots from analyses, only elevation, soil water capacity and sum of temperature of the months over 5ºC were retained as explanatory variables of this gradient. Elevation, soil organic matter and the sum of winter precipitation were the only environmental variables that were related to the compositional gradient of understory species. Conclusions - Present species composition of these forests is unlikely to remain in a next future according to the IPCC climate predictions, whose moderate scenarios predict in the Mediterranean area a severe decrease in precipitations and a raise of 3-4 degrees on average temperature