The role of an interactive Greenland ice sheet in the coupled climate-ice sheet model EC-Earth-PISM

AbstractIce sheet processes are often simplified in global climate models as changes in ice sheets have been assumed to occur over long time scales compared to ocean and atmospheric changes. However, numerous observations show an increasing rate of mass loss from the Greenland Ice Sheet and call for comprehensive process-based models to explore its role in climate change. Here, we present a new model system, EC-Earth-PISM, that includes an interactive Greenland Ice Sheet. The model is based on the EC-Earth v2.3 global climate model in which ice sheet surface processes are introduced. This model interacts with the Parallel Ice Sheet Model (PISM) without anomaly or flux corrections. Under pre-industrial climate conditions, the modeled climate and ice sheet are stable while keeping a realistic interannual variability. In model simulations forced into a warmer climate of four times the pre-industrial CO2 concentration, the total surface mass balance decreases and the ice sheet loses mass at a rate of about 500 Gt/year. In the climate warming experiments, the resulting freshwater flux from the Greenland Ice Sheet increases 55% more in the experiments with the interactive ice sheet and the climate response is significantly different: the Arctic near-surface air temperature is lower, substantially more winter sea ice covers the northern hemisphere, and the ocean circulation is weaker. Our results indicate that the melt-albedo feedback plays a key role for the response of the ice sheet and its influence on the changing climate in the Arctic. This emphasizes the importance of including interactive ice sheets in climate change projections.</jats:p

Distribution of Early Atherosclerotic Lesions in the Human Abdominal Aorta Correlates with Wall Shear Stresses MeasuredIn Vivo

AbstractObjectives: to study the relationship between wall shear stresses measured in vivo and early atherosclerotic lesions in the abdominal aorta. Materials: eight young volunteers for in vivo wall shear-stress measurements. Abdominal aortas from 10 young adults without signs or history of atherosclerotic disease were obtained by autopsy for histomorphometric measurements. Methods: wall shear stresses were measured in the abdominal aorta above and below the renal arteries using a magnetic resonance technique with high resolution for imaging and blood velocity mapping. At identical abdominal aortic locations, intimal thickness was measured blindly using histomorphometric techniques and correlated to wall shear-stress variables using linear-regression analysis. Results: intimal thickness showed a linear decrease with mean wall shear stress (r=−0.90, p<0.01) and with maximum wall shear stress (r=−0.86, p<0.01). Conclusions: intimal thickness in the normal abdominal aorta is associated with mean, maximum and oscillating wall shear stresses. These in vivo data corroborate previous in vitro studies suggesting that low and oscillating wall shear stresses are localising factors for intimal thickening and hence the early development of atherosclerosis

PprA Contributes to Deinococcus radiodurans Resistance to Nalidixic Acid, Genome Maintenance after DNA Damage and Interacts with Deinococcal Topoisomerases

PprA is known to contribute to Deinococcus radiodurans' remarkable capacity to survive a variety of genotoxic assaults. The molecular bases for PprA's role(s) in the maintenance of the damaged D. radiodurans genome are incompletely understood, but PprA is thought to promote D. radiodurans's capacity for DSB repair. PprA is found in a multiprotein DNA processing complex along with an ATP type DNA ligase, and the D. radiodurans toposiomerase IB (DraTopoIB) as well as other proteins. Here, we show that PprA is a key contributor to D. radiodurans resistance to nalidixic acid (Nal), an inhibitor of topoisomerase II. Growth of wild type D. radiodurans and a pprA mutant were similar in the absence of exogenous genotoxic insults; however, the pprA mutant exhibited marked growth delay and a higher frequency of anucleate cells following treatment with DNA-damaging agents. We show that PprA interacts with both DraTopoIB and the Gyrase A subunit (DraGyrA) in vivo and that purified PprA enhances DraTopoIB catalysed relaxation of supercoiled DNA. Thus, besides promoting DNA repair, our findings suggest that PprA also contributes to preserving the integrity of the D. radiodurans genome following DNA damage by interacting with DNA topoisomerases and by facilitating the actions of DraTopoIB

An Innovative Plate Concept for Rotational Guided Growth: A Porcine Pilot Study

BackgroundRotational deformities in children are currently treated with an osteotomy, acute de-rotation, and surgical fixation. Meanwhile, guided growth is now the gold standard in pediatric coronal deformity correction. This study aimed to evaluate the feasibility of a novel implant intended for rotational guided growth (RotOs Plate) in a large porcine animal model.MethodologyA submuscular plate was inserted on the medial and lateral aspect of the distal femoral physis of the left femur in 6 pigs. Each plate was anchored with a screw in the metaphysis and epiphysis respectively. The plates were expected to rotate the femur externally. The right femur acted as a control in a paired design. The animals were housed for 12 weeks after surgery. MRI scanning of both femora was performed before euthanasia after 12 weeks. Rotation was determined as the difference in the femoral version on MRI between the operated and non-operated femur after 12 weeks.ResultsExternal rotation in all operated femurs was observed. The mean difference in the femoral version on MRI between operated and non-operated femurs was 12.5° (range 9°-16°). No significant changes in axial growth were detected.ConclusionsThis study shows encouraging results regarding rotational guided growth, which may replace current invasive surgical treatment options for malrotation in children. However, further studies addressing potential secondary deformities are paramount and should be carried out

Chemotaxis cluster 1 proteins form cytoplasmatic arrays in Vibrio cholera and are stabilized by a double signaling domain receptor DosM

FWN – Publicaties zonder aanstelling Universiteit Leide

Repurposing a chemosensory macromolecular machine

Microbial Biotechnolog