Growth, respiration and photophysiology of coral massive Porites spp. in the experiment of Moorea

I tested the hypothesis that high pCO2 (76.6 Pa and 87.2 Pa vs. 42.9 Pa) has no effect on the metabolism of juvenile massive Porites spp. after 11 days at 28 °C and 545 µmol quanta/m**2/s. The response was assessed as aerobic dark respiration, skeletal weight (i.e., calcification), biomass, and chlorophyll fluorescence. Corals were collected from the shallow (3-4 m) back reef of Moorea, French Polynesia (17°28.614'S, 149°48.917'W), and experiments conducted during April and May 2011. An increase in pCO2 to 76.6 Pa had no effect on any dependent variable, but 87.2 Pa pCO2 reduced area-normalized (but not biomass-normalized) respiration 36 %, as well as maximum photochemical efficiency (Fv/Fm) of open RCIIs and effective photochemical efficiency of RCIIs in actinic light (Delta F/F'm ); neither biomass, calcification, nor the energy expenditure coincident with calcification (J/g) was effected. These results do not support the hypothesis that high pCO2 reduces coral calcification through increased metabolic costs and, instead, suggest that high pCO2 causes metabolic depression and photochemical impairment similar to that associated with bleaching. Evidence of a pCO2 threshold between 76.6 and 87.2 Pa for inhibitory effects on respiration and photochemistry deserves further attention as it might signal the presence of unpredictable effects of rising pCO2.

Microsensor studies on Padina from a natural CO2 seep: implications of morphology on acclimation to low pH

Low seawater pH can be harmful to many calcifying marine organisms, but the calcifying macroalgae Padina spp. flourish at natural submarine carbon dioxide seeps where seawater pH is low. We show that the microenvironment created by the rolled thallus margin of Padina australis facilitates supersaturation of CaCO3 and calcifi-cation via photosynthesis-induced elevated pH. Using microsensors to investigate oxygen and pH dynamics in the microenvironment of P. australis at a shallow CO2 seep, we found that, under saturating light, the pH inside the microenvironment (pHME) was higher than the external seawater (pHSW) at all pHSW levels investigated, and the difference (i.e., pHME-pHSW) increased with decreasing pHSW (0.9 units at pHSW 7.0). Gross photosynthesis (Pg) inside the microenvironment increased with decreasing pHSW, but algae from the control site reached a threshold at pH 6.5. Seep algae showed no pH threshold with respect to Pg within the pHSW range investigated. The external carbonic anhydrase (CA) inhibitor, acetazolamide, strongly inhibited Pg of P. australis at pHSW 8.2, but the effect was diminished under low pHSW (6.4-7.5), suggesting a greater dependence on membrane-bound CA for the dehydration of HCO3- ions during dissolved inorganic carbon uptake at the higher pHSW. In comparison, a calcifying green alga, Halimeda cuneata f. digitata, was not inhibited by AZ, suggesting efficient bicarbonate transport. The ability of P. australis to elevate pHME at the site of calcification and its strong dependence on CA may explain why it can thrive at low pHSW.

Measuring fixed costs for firms' use of a free trade agreement : threshold regression approach

In this paper, by employing the threshold regression method, we estimate the average tariff equivalent of fixed costs for the use of a free trade agreement (FTA) among all existing FTAs in the world. It is estimated to be 3.2%. This global estimate serves as a reference rate in the evaluation of each FTA’s fixed costs.

Temperature and time dependent threshold voltage characterization of AlGaN/GaN high electron mobility transistors

Relacionado con línea de investigación del GDS del ISOM ver http://www.isom.upm.es/dsemiconductores.php

The estimation of truncation error by tau-estimation revisited

The aim of this paper was to accurately estimate the local truncation error of partial differential equations, that are numerically solved using a finite difference or finite volume approach on structured and unstructured meshes. In this work, we approximated the local truncation error using the @t-estimation procedure, which aims to compare the residuals on a sequence of grids with different spacing. First, we focused the analysis on one-dimensional scalar linear and non-linear test cases to examine the accuracy of the estimation of the truncation error for both finite difference and finite volume approaches on different grid topologies. Then, we extended the analysis to two-dimensional problems: first on linear and non-linear scalar equations and finally on the Euler equations. We demonstrated that this approach yields a highly accurate estimation of the truncation error if some conditions are fulfilled. These conditions are related to the accuracy of the restriction operators, the choice of the boundary conditions, the distortion of the grids and the magnitude of the iteration error.

Video Prioritization for Unequal Error Protection

We analyze the effect of packet losses in video sequences and propose a lightweight Unequal Error Protection strategy which, by choosing which packet is discarded, reduces strongly the Mean Square Error of the received sequence

ITEM: Inter-Texture Error Measurement for 3D Meshes

We introduce a simple and innovative method to compare any two texture maps, regardless of their sizes, aspect ratios, or even masks, as long as they are both meant to be mapped onto the same 3D mesh. Our system is based on a zero-distortion 3D mesh unwrapping technique which compares two new adapted texture atlases with the same mask but different texel colors, and whose every texel covers the same area in 3D. Once these adapted atlases are created, we measure their difference with ITEM-RMSE, a slightly modified version of the standard RMSE defined for images. ITEM-RMSE is more meaningful and reliable than RMSE because it only takes into account the texels inside the mask, since they are the only ones that will actually be used during rendering. Our method is not only very useful to compare the space efficiency of different texture atlas generation algorithms, but also to quantify texture loss in compression schemes for multi-resolution textured 3D meshes.

Percolation in soils at Different Bulk Densities: Porosity, Connectivity and Grey Threshold.

To improve percolation modelling on soils the geometrical properties of the pore space must be understood; this includes porosity, particle and pore size distribution and connectivity of the pores. A study was conducted with a soil at different bulk densities based on 3D grey images acquired by X-ray computed tomography. The objective was to analyze the effect in percolation of aspects of pore network geometry and discuss the influence of the grey threshold applied to the images. A model based on random walk algorithms was applied to the images, combining five bulk densities with up to six threshold values per density. This allowed for a dynamical perspective of soil structure in relation to water transport through the inclusion of percolation speed in the analyses. To evaluate separately connectivity and isolate the effect of the grey threshold, a critical value of 35% of porosity was selected for every density. This value was the smallest at which total-percolation walks appeared for the all images of the same porosity and may represent a situation of percolation comparable among bulks densities. This criterion avoided an arbitrary decision in grey thresholds. Besides, a random matrix simulation at 35% of porosity with real images was used to test the existence of pore connectivity as a consequence of a non-random soil structure.

Automatic binding-related error diagnosis in logic programs

This paper proposes a diagnosis algorithm for locating a certain kind of errors in logic programs: variable binding errors that result in abstract symptoms during compile-time checking of assertions based on abstract interpretation. The diagnoser analyzes the graph generated by the abstract interpreter, which is a provably safe approximation of the program semantics. The proposed algorithm traverses this graph to find the point where the actual error originates (a reason of the symptom), leading to the point the error has been reported (the symptom). The procedure is fully automatic, not requiring any interaction with the user. A prototype diagnoser has been implemented and preliminary results are encouraging.