1,549 research outputs found
Valuable Information and Costly Liquidity: Evidence from Individual Mutual Fund Trades
Until recently, all Canadian mutual funds were required to disclose all their individual trades, offering a unique and ideal opportunity to measure and analyze the cost and performance of mutual funds\u27 trades. We find that active management delivers both cheaper trades and better subsequent performance, and that the dissipative effect of flow-driven transactions costs is primarily through forced sales. Fund size associates with both cheaper trades and better subsequent performance, and a series of trades predicts more price movement in the predicted direction, indicating the value to funds of keeping their trading anonymous
Clay Sediments from Basaltic Terrains: Implications for Sedimentary Processes on Mars
The Mars Science Laboratory (MSL) rover, Curiosity, has been traversing across fluvial, lacustrine, and eolian sedimentary rocks since it touched down in 2012. The CheMin X-ray diffractometer (XRD) on board Curiosity has revealed smectite clay minerals in most fluvio-lacustrine samples and abundant X-ray amorphous materials in all samples analyzed to date. For example, mudstones from the Sheepbed member at the base of the stratigraphic section and the lower part of the Murray formation contain on average ~7 to 20 wt% smectite and ~30 to 46 wt% X-ray amorphous abundances. On Earth, smectite and secondary X-ray amorphous materials are juvenile weathering products that are generated in sedimentary environments and ultimately record the interaction between primary igneous minerals and the hydrosphere, atmosphere, and biosphere. For this study, we investigated glacio-fluvio-eolian sediments generated in basaltic terrains as terrestrial analogs for the mudstones from Gale Crater, Mars. This work focuses on the clay sized sediments (<2 m) from these deposits as this grain size hosts the most mineralogically and geochemically altered detritus in sedimentary environments. The goal of investigating basaltic sedimentation is to create a terrestrial reference frame that sheds light on the paleoclimate and paleoaqueous conditions responsible for shaping the ancient sedimentary environments of Mars (e.g., Gale Crater and Jezero Crater)
Apolipoprotein M mediates sphingosine-1-phosphate efflux from erythrocytes
Abstract Sphingosine-1-phosphate (S1P) is a bioactive lipid implicated in e.g. angiogenesis, lymphocyte trafficking, and endothelial barrier function. Erythrocytes are a main source of plasma S1P together with platelets and endothelial cells. Apolipoprotein M (apoM) in HDL carries 70% of plasma S1P, whereas 30% is carried by albumin. The current aim was to investigate the role of apoM in export of S1P from human erythrocytes. Erythrocytes exported S1P more efficiently to HDL than to albumin, particularly when apoM was present in HDL. In contrast, export of sphingosine to HDL was unaffected by the presence of apoM. The specific ability of apoM to promote export of S1P was independent of apoM being bound in HDL particles. Treatment with MK-571, an inhibitor of the ABCC1 transporter, effectively reduced export of S1P from human erythrocytes to apoM, whereas the export was unaffected by inhibitors of ABCB1 or ATPase. Thus, ABCC1 could be involved in export of S1P from erythrocytes to apoM
Effect of maturational timing on bone health in male adolescent athletes engaged in different sports: The PRO-BONE study
This is the author accepted manuscript. the final version is available from Elsevier via the DOI in this recordObjectives: To describe differences in bone outcomes according to biological age in male athletes participating in osteogenic (OS) or non-osteogenic (NOS) sports. Design: Longitudinal (12-months). Methods: 104 adolescents (12â14 years) were measured at baseline and after 1y: OS group (n = 37 football or soccer players) and NOS group (n = 39 swimmers, n = 28 cyclists). Years from peak height velocity (PHV, â2 to +2) was used as a maturational landmark. Bone mineral content (BMC) was assessed using DXA. Hip structural analysis estimated cross-sectional area (CSA), cross-sectional moment of inertia (CSMI) and section modulus (Z) at the femoral neck (FN). Trabecular bone score (TBS) estimated lumbar spine (LS) texture. Quantitative ultrasound measured bone stiffness. Multilevel regression models adjusted by hours of training were fitted. Results: Compared to NOS, OS had significantly greater total body (less head) BMC from PHV to +2 years from PHV (from 9.5% to 11.3%, respectively); LS BMC from â1 years from PHV to PHV (from 9.8% to 9.9%); hip BMC (from 11.6% to 22.9%), FN BMC (from 12.0% to 15.9%), TBS (from 4.2% to 4.8%) and stiffness index (from 11.9% to 23.3%) from â1 years from PHV to +2 years from PHV; and CSA (from 8.4% to 18.8%), Z (from 5.5% to 22.9%) and CSMI (from 10.6% to 23.3%) from â2 years from PHV to +2 years from PHV. There was a significant trend for the between-group differences to increase with biological age except for LS BMC and TBS. Conclusions: These findings underline the differential bone response to different sports throughout the years surrounding PHV in male adolescent athletes. Clinical trial registration: ISRCTN17982776.European Union Seventh Framework ProgrammeUniversity of Castilla-La ManchaUniversity of Granad
Distributed Acoustic Sensing of Seismic Properties in a Borehole Drilled on a FastâFlowing Greenlandic Outlet Glacier
Abstract
Distributed Acoustic Sensing (DAS) is a new technology in which seismic energy is detected, at high spatial and temporal resolution, using the propagation of laser pulses in a fiberâoptic cable. We show analyses from the first glaciological borehole DAS deployment to measure the englacial and subglacial seismic properties of Store Glacier, a fastâflowing outlet of the Greenland Ice Sheet. We record compressional and shear waves in 1,043 mâdeep vertical seismic profiles, sampled at 10 m vertical resolution, and detect a transition from isotropic to anisotropic ice at 84% of ice thickness, consistent with the HoloceneâWisconsin transition. We identify subglacial reflections originating from the base of a 20 mâthick layer of consolidated sediment and, from attenuation measurements, interpret temperate ice in the lowermost 100 m of the glacier. Our findings highlight the promising potential of DAS technology to constrain the seismic properties of glaciers and ice sheets.
Plain Language Summary
Distributed Acoustic Sensing (DAS) is a new technology for seismic surveying in which the transmission of light through fiberâoptic cables is used to record seismic energy, with unprecedented spatial resolution compared to traditional techniques. Our paper presents data from the first boreholeâglaciological deployment of DAS, in which fiberâoptic cable was installed in a 1,043 mâdeep vertical borehole on Store Glacier, a fastâflowing outlet of the Greenland Ice Sheet. The detailed seismic anatomy of the glacier that our survey providesâan independent measurement of the seismic response every 10 mâgives new insights about its internal flow regime and temperature and even allows us to detect layers of sediment underlying it. We predict that DAS surveying will play an increasingly large role in future glaciological investigations as the recognition of its promising potential grows
Xanthelasmata, arcus corneae, and ischaemic vascular disease and death in general population: prospective cohort study
Objective To test the hypothesis that xanthelasmata and arcus corneae, individually and combined, predict risk of ischaemic vascular disease and death in the general population
Physical Conditions of Fast Glacier Flow 2:Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland
Outlet glaciers of the Greenland Ice Sheet transport ice from the interior to the ocean and contribute directly to sea level rise because because discharge and ablation often exceed the accumulation. To develop a better understanding of these fast flowing glaciers, we investigate the basal conditions of Store Glacier, a large outlet glacier flowing into Uummannaq Fjord in West Greenland. We use two crossing seismic profiles acquired near the centreline, 30 km upstream of the calving front, to interpret the physical nature of the ice and bed. We identify one notably englacial and two notably subglacial seismic reflections on both profiles. The englacial reflection represents a change in crystal orientation fabric, interpreted to be the Holocene?Wisconsin transition. From Amplitude Versus Angle (AVA) analysis we infer that the deepest ?80 m of ice of the parallel-flow profile below this reflection is anisotropic with an enhancement of simple shear of ?2. The ice is underlain by ?45 m of unconsolidated sediments, below which there is a strong reflection caused by the transition to consolidated sediments. In the across-flow profile subglacial properties vary over small scale and the polarity of the ice?bed reflection switches from positive to negative. We interpret these as patches of different basal slipperiness associated with variable amounts of water. Our results illustrate variability in basal properties, and hence ice-bed coupling, at a spatial scale of ?100 m, highlighting the need for direct observations of the bed to improve the basal boundary conditions in ice-dynamic modelspublishersversionPeer reviewe
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