Light-related variation in sapling architecture of three shade-tolerant tree species of the Mexican rain forest

The crown architecture of three shade-tolerant tree species (two subcanopy and one mid-canopy) was analyzed in relation to the light regime of the forest understorey. The aim was to examine to which extent shade-tolerant species variate in their crown architecture. Tree saplings (265) between 50 and 300 cm height, and distributed from understorey to variously-sized canopy gaps, were measured for 13 architectural traits in the lowland rain forest of Los Tuxtlas, Mexico. The analysis showed that the three species changed their architecture as light increased but in a different way. No species conformed to the typical wide-crown type expected for shade-tolerant species, and in contrast they presented some traits of light demanding species. The two sub-canopy species tended to adopt a crown form between a narrow- and wide-crown type, and the mid-canopy species showed more traits of a narrow-crown type. The horizontal crown area appeared as the more related trait to the light and sapling height. It is concluded that despite being shade-tolerant, the Studied species make use of better-lit environments in the forest understorey. The crown architecture of shade-tolerant species is not Lis rigid Lis originally conceived

Biology, fisheries and culture of tropical groupers and snappers

Groupers and snappers are important fishery resources of the tropics and subtropics, where their high values have caused most of their stocks to be heavily exploited, some even to the point of collapse. Trends towards heavy demand and decreasing natural supply, which are accelerating in several parts of the world, prompted various mariculture ventures. Focused research on biology and the population dynamics of groupers and snappers, and on their reproduction and growth under controlled condition will remain essential for dealing with the questions on how to better manage their fisheries. This volume of papers presents important scientific findings and views on these two important groups of fish.Percoid fisheries, Fishery biology, Fishery management, Conferences

Sacrectomía en bloque para tumores gigantes del sacro preservando las raíces de S1. Reporte de nueva técnica quirúrgica y resultado funcional

Los tumores primarios de sacro son lesiones raras que se caracterizan por ser localmente agresivos, de naturaleza osteolítica y con gran potencial para recurrir a corto plazo. Se han descrito mútiples opciones de manejo y tratamiento de los mismos, incluyendo quimioterapia y radioterapia además de resección quirúrgica con el fin de proveer control a largo plazo sobre el crecimiento tumoral y/o cura definitiva. (5, 6, 7) Dada la naturaleza histológica de dichas lesiones, la sacrectomía en bloque es la técnica quirúrgica que menos recurrencia local implica (8) sin embargo, dado el compromiso extenso que presentan los tumores sacros en el momento del diagnóstico, usualmente la resección quirurgica implica el sacrificio de raíces nerviosas, impactando directamente en morbilidad a largo plazo. Las complicaciones mayores secundarias que más frecuentemente se observan incluyen alteración para la deambulación, función genitourinaria y gastrointestinal, y finalmente, función sexual. (4). El objetivo del presente articulo es describir tres casos en donde se realizan sacrectomía en bloque de tumores primarios de sacro con preservación de raices nerviosas y sus desenlaces a 36 meses de seguimiento postquirúrgico.Sacral primary tumors are rare lesiones that are characterized to be locally expansive and agressive, often present with osteolysis and with great chances to recurr at short-run term after a first surgical reseccion. There are multiple described options for management and treatment, including radiotherapy and chemotherapy for the relief of pain and surgical reseccion in order to provide long-term control over tumor growth or definitive cure. Given the nature of such lesions, en bloc sacrectomy is the surgical technique that involves less local recurrence, however, given the extensión of sacral tumors at diagnosis, usually surgical resection means sacrificing nerve roots, directly impacting over long-term morbidity. Secondary major complicactions most frequently observed include impaired ambulation, genitourinary, gastrointestinal and sexual function. The aim of this article is to describe three cases where en bloc sacrectomy were performed for management of primary sacral tumors (two gigant cell tumors and one hemangioma) with preservation of nerve roots and their outcome up tu 36 months of postoperative follow-up

Modelling the photo-Fenton oxidation of the pharmaceutical paracetamol in water including the effect of photon absorption (VRPA)

A new model is proposed for the photo-Fenton oxidation of water contaminants including the effect of photon absorption (volumetric rate of photon absorption, VRPA), the effect of the geometry of the reactor and the illuminated volume to total volume ratio (Ri) in the reaction system. Fe(III) was found to be the main species in the aqueous solution responsible for photon absorption provided that hydrogen peroxide was not totally consumed. Paracetamol was used as model pollutant at a concentration of 1 mM to validate the model. The illuminated part of the raceway reactor configuration (total length of 80 cm) was operated at two liquid depths (5.0 and 2.5 cm) equivalent to two irradiated reactor volumes (2 and 1 L) and using Ri ratios in the range 0.30–0.65, which changed the dark reactor volume. These values are commonly found in photo-Fenton pilot plants for water treatment and purification. The model successfully fitted the temporal evolution of the dissolved oxygen (O2) and the hydrogen peroxide (H2O2) concentrations and the evolution of the total organic carbon (TOC) in solution in both reactor geometries and for different illuminated volume to total volume ratios. The model can be easily extended to model other water contaminants and provides a robust method for process design, process control and optimization

Adaptive simulation of unsteady flow past the submerged part of a floating wind turbine platform

Offshore floating platforms for wind turbines represent challenging concepts for designers trying to combine an optimal compromise between cost effectiveness and performance. Modelling of the hydrodynamic behaviour of the structure is still the subject of wide debate in the technical communities. The assessment of the hydrodynamics of the support structure is not an easy task as the floaters consist of an assembly of columns, braces and pontoons, commonly also with heave plates: Each of these components corresponds to a different hydrodynamic model and it further interacts with the other elements. This results in very complex non-linear modeling, which makes it necessary to resort to computational fluid dynamics (CFD) methods for the evaluation of the combined hydrodynamics. In the framework of the collaboration between the Basque Centre for Applied Mathematics (BCAM) and Tecnalia R&I, the interaction of the sea flow with a semisubmersible floating offshore wind platform have been calculated by using the open source solver Unicorn in the FEniCS-HPC framework when subject to a steady inflow. The prototype of the platform consists in a semi-submersible 4-columns column stabilized platform - NAUTILUS Floating Solutions concept-; columns are connected by a rigid ring pontoon provided with heave damping plates at the bottom. The novelty of the approach in FEniCS-HPC hinges upon an implicit formulation for the turbulence, a cheap free slip model of the boundary layer and goal-oriented mesh adaptivity [8, 6, 9, 20, 1]. We find that the results are consistent with experimental results for cylinders at high Reynolds number

On the deflection of asteroids with mirrors

This paper presents an analysis of an asteroid deflection method based on multiple solar concentrators. A model of the deflection through the sublimation of the surface material of an asteroid is presented, with simulation results showing the achievable orbital deflection with, and without, accounting for the effects of mirror contamination due to the ejected debris plume. A second model with simulation results is presented analyzing an enhancement of the Yarkovsky effect, which provides a significant deflection even when the surface temperature is not high enough to sublimate. Finally the dynamical model of solar concentrators in the proximity of an irregular celestial body are discussed, together with a Lyapunov-based controller to maintain the spacecraft concentrators at a required distance from the asteroid