26 research outputs found
Implementation and performance of adaptive mesh refinement in the Ice Sheet System Model (ISSM v4.14)
Accurate projections of the evolution of ice sheets in a changing climate
require a fine mesh/grid resolution in ice sheet models to correctly capture
fundamental physical processes, such as the evolution of the grounding line,
the region where grounded ice starts to float. The evolution of the grounding
line indeed plays a major role in ice sheet dynamics, as it is a fundamental
control on marine ice sheet stability. Numerical modeling of a grounding line
requires significant computational resources since the accuracy of its
position depends on grid or mesh resolution. A technique that improves
accuracy with reduced computational cost is the adaptive mesh refinement
(AMR) approach. We present here the implementation of the AMR technique in
the finite element Ice Sheet System Model (ISSM) to simulate grounding line
dynamics under two different benchmarks: MISMIP3d and MISMIP+. We test
different refinement criteria: (a)Â distance around the grounding line, (b)Â a
posteriori error estimator, the ZienkiewiczâZhu (ZZ) error estimator, and
(c) different combinations of (a) and (b). In both benchmarks, the ZZ error
estimator presents high values around the grounding line. In the MISMIP+ setup,
this estimator also presents high values in the grounded
part of the ice sheet, following the complex shape of the bedrock geometry.
The ZZ estimator helps guide the refinement procedure such that AMR
performance is improved. Our results show that computational time with AMR
depends on the required accuracy, but in all cases, it is significantly
shorter than for uniformly refined meshes. We conclude that AMR without an
associated error estimator should be avoided, especially for real glaciers
that have a complex bed geometry.</p
Stress related epigenetic changes may explain opportunistic success in biological invasions in Antipode mussels
Different environmental factors could induce epigenetic changes, which are likely involved in the biological invasion process. Some of these factors are driven by humans as, for example, the pollution and deliberate or accidental introductions and others are due to natural conditions such as salinity. In this study, we have analysed the relationship between different stress factors: time in the new location, pollution and salinity with the methylation changes that could be involved in the invasive species tolerance to new environments. For this purpose, we have analysed two different musselsâ species, reciprocally introduced in antipode areas: the Mediterranean blue mussel Mytilus galloprovincialis and the New Zealand pygmy mussel Xenostrobus securis, widely recognized invaders outside their native distribution ranges. The demetylathion was higher in more stressed population, supporting the idea of epigenetic is involved in plasticity process. These results can open a new management protocols, using the epigenetic signals as potential pollution monitoring tool. We could use these epigenetic marks to recognise the invasive status in a population and determine potential biopollutants
Persistent aggregates in apheresis platelet concentrates
Aggregates often appear during apheresis. Sometimes, these persist throughout storage, causing product wastage. This study assessed product quality of apheresis concentrates containing persistent aggregates (PA) and aimed to identify the factors that contribute to their formation.status: publishe
Riboflavin and amotosalen photochemical treatments of platelet concentrates reduce thrombus formation kinetics in vitro
Photochemical treatment (PCT) of platelet concentrates using photosensitizers and ultraviolet light illumination reduces the proliferation potential of pathogens by damaging biomolecules.status: publishe