17,453 research outputs found
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Mineralogy and Geochemistry of Shergottite RBT 04262
This abstract presents mineralogical and geochemical data on newly discovered shergottite RBT 04262 and compares it with other known shergottites
Effects of non-universal large scales on conditional structure functions in turbulence
We report measurements of conditional Eulerian and Lagrangian structure
functions in order to assess the effects of non-universal properties of the
large scales on the small scales in turbulence. We study a 1m 1m
1.5m flow between oscillating grids which produces
while containing regions of nearly homogeneous and highly inhomogeneous
turbulence. Large data sets of three-dimensional tracer particle velocities
have been collected using stereoscopic high speed cameras with real-time image
compression technology. Eulerian and Lagrangian structure functions are
measured in both homogeneous and inhomogeneous regions of the flow. We
condition the structure functions on the instantaneous large scale velocity or
on the grid phase. At all scales, the structure functions depend strongly on
the large scale velocity, but are independent of the grid phase. We see clear
signatures of inhomogeneity near the oscillating grids, but even in the
homogeneous region in the center we see a surprisingly strong dependence on the
large scale velocity that remains at all scales. Previous work has shown that
similar correlations extend to very high Reynolds numbers. Comprehensive
measurements of these effects in a laboratory flow provide a powerful tool for
assessing the effects of shear, inhomogeneity and intermittency of the large
scales on the small scales in turbulence
Purified Human Pancreatic Duct Cell Culture Conditions Defined by Serum-Free High-Content Growth Factor Screening
The proliferation of pancreatic duct-like CK19+ cells has implications for multiple disease states including pancreatic cancer and diabetes mellitus. The in vitro study of this important cell type has been hampered by their limited expansion compared to fibroblast-like vimentin+ cells that overgrow primary cultures. We aimed to develop a screening platform for duct cell mitogens after depletion of the vimentin+ population. The CD90 cell surface marker was used to remove the vimentin+ cells from islet-depleted human pancreas cell cultures by magnetic-activated cell sorting. Cell sorting decreased CD90+ cell contamination of the cultures from 34±20% to 1.3±0.6%, yielding purified CK19+ cultures with epithelial morphology. A full-factorial experimental design was then applied to test the mitogenic effects of bFGF, EGF, HGF, KGF and VEGF. After 6 days in test conditions, the cells were labelled with BrdU, stained and analyzed by high-throughput imaging. This screening assay confirmed the expected mitogenic effects of bFGF, EGF, HGF and KGF on CK19+ cells and additionally revealed interactions between these factors and VEGF. A serum-free medium containing bFGF, EGF, HGF and KGF led to CK19+ cell expansion comparable to the addition of 10% serum. The methods developed in this work should advance pancreatic cancer and diabetes research by providing effective cell culture and high-throughput screening platforms to study purified primary pancreatic CK19+ cells
Used-habitat calibration plots: a new procedure for validating species distribution, resource selection, and step-selection models
“Species distribution modeling” was recently ranked as one of the top five “research fronts” in ecology and the environmental sciences by ISI's Essential Science Indicators (Renner and Warton 2013), reflecting the importance of predicting how species distributions will respond to anthropogenic change. Unfortunately, species distribution models (SDMs) often perform poorly when applied to novel environments. Compounding on this problem is the shortage of methods for evaluating SDMs (hence, we may be getting our predictions wrong and not even know it). Traditional methods for validating SDMs quantify a model's ability to classify locations as used or unused. Instead, we propose to focus on how well SDMs can predict the characteristics of used locations. This subtle shift in viewpoint leads to a more natural and informative evaluation and validation of models across the entire spectrum of SDMs. Through a series of examples, we show how simple graphical methods can help with three fundamental challenges of habitat modeling: identifying missing covariates, non-linearity, and multicollinearity. Identifying habitat characteristics that are not well-predicted by the model can provide insights into variables affecting the distribution of species, suggest appropriate model modifications, and ultimately improve the reliability and generality of conservation and management recommendations
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Spatial epidemiological patterns suggest mechanisms of land-sea transmission for Sarcocystis neurona in a coastal marine mammal.
Sarcocystis neurona was recognised as an important cause of mortality in southern sea otters (Enhydra lutris nereis) after an outbreak in April 2004 and has since been detected in many marine mammal species in the Northeast Pacific Ocean. Risk of S. neurona exposure in sea otters is associated with consumption of clams and soft-sediment prey and is temporally associated with runoff events. We examined the spatial distribution of S. neurona exposure risk based on serum antibody testing and assessed risk factors for exposure in animals from California, Washington, British Columbia and Alaska. Significant spatial clustering of seropositive animals was observed in California and Washington, compared with British Columbia and Alaska. Adult males were at greatest risk for exposure to S. neurona, and there were strong associations with terrestrial features (wetlands, cropland, high human housing-unit density). In California, habitats containing soft sediment exhibited greater risk than hard substrate or kelp beds. Consuming a diet rich in clams was also associated with increased exposure risk. These findings suggest a transmission pathway analogous to that described for Toxoplasma gondii, with infectious stages traveling in freshwater runoff and being concentrated in particular locations by marine habitat features, ocean physical processes, and invertebrate bioconcentration
Morphology of the Acromion and Scapular Spine with Special Interest in the Strength & Failure Prediction after Reverse Total Shoulder Replacement
Scapular spine fractures following a reverse arthroplasty are a significant clinical concern. This ongoing study looks at the morphology of the acromion and scapular spine with an interest in the strength and failure prediction of the bone. Digital 3D models of the scapular spine were created from cadaver CTs, then bone density and distribution data was obtained. It was found that the cortical bone was most dense just medial of the lateral angle. The cross-sectional area here was also the largest and decreased medially. This has important implications for implant fixation hardware as cortical bone --compared to cancellous bone-- is stronger, denser, and therefore a better option for fixation hardware
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