Copernicus: the European Earth Observation programme

[EN] The European Union-led Copernicus programme, born with the aim of developing space-based global environmental monitoring services to ensure a European autonomous capacity for Earth Observation, comprises a Space Component, Core Services, and In-situ measurements. The Space Component, coordinated by ESA, has seven Sentinel satellites in orbit, with further missions planned, and is complemented by contributing missions, in-situ sensors and numerical models, and delivers many terabytes of accurate climate and environmental data, free and open, every day to hundreds of thousands of users. This makes Copernicus the biggest provider of Earth Observation data in the world.Jutz, S.; Milagro-Pérez, M. (2020). Copernicus: the European Earth Observation programme. https://doi.org/10.4995/raet.2020.14346OJ

Biomechanical evaluation of tibial bone adaptation after revision total knee arthroplasty: A comparison of different implant systems

The best methods to manage tibial bone defects following total knee arthroplasty remain under debate. Different fixation systems exist to help surgeons reconstruct knee osseous bone loss (such as tantalum cones, cement, modular metal augments, autografts, allografts and porous metaphyseal sleeves) However, the effects of the various solutions on the long-term outcome remain unknown. In the present work, a bone remodeling mathematical model was used to predict bone remodeling after total knee arthroplasty (TKA) revision. Five different types of prostheses were analyzed: one with a straight stem; two with offset stems, with and without supplements; and two with sleeves, with and without stems. Alterations in tibia bone density distribution and implant Von Mises stresses were quantified. In all cases, the bone density decreased in the proximal epiphysis and medullary channels, and an increase in bone density was predicted in the diaphysis and around stem tips. The highest bone resorption was predicted for the offset prosthesis without the supplement, and the highest bone formation was computed for the straight stem. The highest Von Mises stress was obtained for the straight tibial stem, and the lowest was observed for the stemless metaphyseal sleeves prosthesis. The computational model predicted different behaviors among the five systems. We were able to demonstrate the importance of choosing an adequate revision system and that in silico models may help surgeons choose patient-specific treatments

2-Engel relations between subgroups

In this paper we study groups G generated by two subgroups A and B such that is nilpotent of class at most 2 for all a¿. A and b¿. B. A detailed description of the structure of such groups is obtained, generalizing the classical result of Hopkins and Levi on 2-Engel groups

Depth differential colonization by mycorrhizal fungi in prairie grasses

Non-Peer ReviewedA research was conducted in field plots to evaluate types of mycorrhizal fungi colonization in monocultures of green needlegrass (G), switch grass (S), western wheatgrass (W), Russian wild rye (R), crested wheatgrass (C) or mixtures of grasses. A root sampling strategy based on different soil depth (0-15, 15-30 and 30-45 cm) revealed a significant effect of depth on root colonization by different types of mycorrhizal fungi, but no significant differences were found between plant communities

High and low plant biodiversity: two strategies encountered in southwest Saskatchewan prairie

Non-Peer Reviewe

Grass growth promotion by dark septate endophytic fungi is host specific

Non-Peer ReviewedIsolates of dark septate endophytic fungi (DSE) were obtained from healthy looking roots of two early season grasses [crested wheatgrass (Agropyron cristatum L), Russian wildrye (Elymus junceus Fisch)] and one late season grass [blue gramma (Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths] growing in southwest Saskatchewan. The capacity of some fungal isolates to colonize the roots or to promote the growth of these grasses was tested under controlled conditions. A first study revealed that DSE isolates AC 1 and EJ 5 colonize with more intensity the roots of the grass species from which they were isolated. A second study showed that the ability of each fungal isolate to promote plant growth depended on the plant species inoculated. Inoculation with four out of five isolates reduced B. gracilis growth, but increased the growth of one of the early season grasses. The results indicate that DSE fungal isolates are not species specific colonizers but have a strong preference for certain plant species, and some isolates can promote or depress plant growth depending on specific DSE isolate-grass combinations

Depth differential colonization and biodiversity of mycorrhizal fungi in four prairie grass species

Non-Peer ReviewedThe biodiversity of AMF at different soil depths was studied in pure stands of the grasses crested wheatgrass (Agropyron cristatum (L.) Gaertn.), switchgrass (Panicum virgatum L.), green needlegrass (Nassella viridula Trin.) and western wheatgrass (Pascopyrum smithii (Rydb.) A. Löve), growing in southwest Saskatchewan. The biodiversity of AMF was described in roots from 3 to 15, and 30 to 45 cm depth sampled in 2006 using phylogenetic and molecular tools. Soil depth reduced root colonization and influenced AMF community composition, which was dominated by six AMF phylotypes of the genus Glomus. Three AMF phylotypes were common colonizers and three were preferentially associated with some grasses. AMF communities at different depths differed from each other in all plant stands, and diversity and richness of AMF phylotypes was higher at shallow depth, except in N. viridula which showed higher richness of AMF in deeper root samples. We conclude that although some AMF are general colonizers, some AMF have a strong host preference. Our results also indicate that soil depth is a important driver of AMF phylotype distribution, and suggest the existence of niche specialization in AMF along the soil profile, which is influenced by the host plant