4,382 research outputs found
Statutory Interpretation After Hively: Where Will the Seventh Circuit Go?
Fifty years ago, when Title VII was passed, no one thought that sexual orientation discrimination was unlawful sex discrimination. The Seventh Circuitâs decision to re-interpret Title VII challenges traditional approaches to statutory interpretation that should put Seventh Circuit litigants on notice of future uncertainty
Interfaces in driven Ising models: shear enhances confinement
We use a phase-separated driven two-dimensional Ising lattice gas to study
fluid interfaces exposed to shear flow parallel to the interface. The interface
is stabilized by two parallel walls with opposing surface fields and a driving
field parallel to the walls is applied which (i) either acts locally at the
walls or (ii) varies linearly with distance across the strip. Using computer
simulations with Kawasaki dynamics, we find that the system reaches a steady
state in which the magnetisation profile is the same as that in equilibrium,
but with a rescaled length implying a reduction of the interfacial width. An
analogous effect was recently observed in sheared phase-separated colloidal
dispersions. Pair correlation functions along the interface decay more rapidly
with distance under drive than in equilibrium and for cases of weak drive can
be rescaled to the equilibrium result.Comment: 4 pages, 3 figures Text modified, added Fig. 3b. To appear in Phys.
Rev. Letter
Tooth fracture frequency in gray wolves reflects prey availability.
Exceptionally high rates of tooth fracture in large Pleistocene carnivorans imply intensified interspecific competition, given that tooth fracture rises with increased bone consumption, a behavior that likely occurs when prey are difficult to acquire. To assess the link between prey availability and dental attrition, we documented dental fracture rates over decades among three well-studied populations of extant gray wolves that differed in prey:predator ratio and levels of carcass utilization. When prey:predator ratios declined, kills were more fully consumed, and rates of tooth fracture more than doubled. This supports tooth fracture frequency as a relative measure of the difficulty of acquiring prey, and reveals a rapid response to diminished food levels in large carnivores despite risks of infection and reduced fitness due to dental injuries. More broadly, large carnivore tooth fracture frequency likely reflects energetic stress, an aspect of predator success that is challenging to quantify in wild populations
Effect of Sociality and Season on Gray Wolf (Canis lupus) Foraging Behavior: Implications for Estimating Summer Kill Rate
BACKGROUND: Understanding how kill rates vary among seasons is required to understand predation by vertebrate species living in temperate climates. Unfortunately, kill rates are only rarely estimated during summer. METHODOLOGY/PRINCIPAL FINDINGS: For several wolf packs in Yellowstone National Park, we used pairs of collared wolves living in the same pack and the double-count method to estimate the probability of attendance (PA) for an individual wolf at a carcass. PA quantifies an important aspect of social foraging behavior (i.e., the cohesiveness of foraging). We used PA to estimate summer kill rates for packs containing GPS-collared wolves between 2004 and 2009. Estimated rates of daily prey acquisition (edible biomass per wolf) decreased from 8.4±0.9 kg (mean ± SE) in May to 4.1±0.4 kg in July. Failure to account for PA would have resulted in underestimating kill rate by 32%. PA was 0.72±0.05 for large ungulate prey and 0.46±0.04 for small ungulate prey. To assess seasonal differences in social foraging behavior, we also evaluated PA during winter for VHF-collared wolves between 1997 and 2009. During winter, PA was 0.95±0.01. PA was not influenced by prey size but was influenced by wolf age and pack size. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that seasonal patterns in the foraging behavior of social carnivores have important implications for understanding their social behavior and estimating kill rates. Synthesizing our findings with previous insights suggests that there is important seasonal variation in how and why social carnivores live in groups. Our findings are also important for applications of GPS collars to estimate kill rates. Specifically, because the factors affecting the PA of social carnivores likely differ between seasons, kill rates estimated through GPS collars should account for seasonal differences in social foraging behavior
Computational hyperspectral interferometry for studies of brain function: Proof of concept
Hyperspectral interferometric microscopy uses a unique combination of optics and algorithm design to extract information. Local brain activity rapidly changes local blood flow and red blood cell concentration (absorption) and oxygenation (color). We demonstrate that brain activity evoked during whisker stimulation can be detected with hyperspectral interferometric microscopy to identify the active whisker-barrel cortex in the rat brain. Information about constituent components is extracted across the entire spectral band. Algorithms can be flexibly optimized to discover, detect, quantify, and visualize a wide range of significant biological events, including changes relevant to the diagnosis and treatment of disease. © 2006 Optical Society of America
The Northeast Water polynya as an atmospheric CO2 sink: a seasonal rectification hypothesis
During the multidisciplinary âNEW92â cruise of the United States Coast Guard Cutter (USCGC) Polar Sea to the recurrent Northeast Water (NEW) Polynya (77â81°N, 6â17°W; JulyâAugust 1992), total dissolved inorganic carbon and total alkalinity in the water column were measured with high precision to determine the quantitative impact of biological processes on the regional air-sea flux of carbon. Biological processes depleted the total inorganic carbon of summer surface waters by up to 2 mol C mâ2 or about 3%. On a regional basis this depletion correlated with depth-integrated values of chlorophyll a, particulate organic carbon, and the inorganic nitrogen deficit. Replacement of this carbon through exchange with the atmosphere was stalled owing to the low wind speeds during the month of the cruise, although model calculations indicate that the depletion could be replenished by a few weeks of strong winds before ice forms in the autumn. These measurements and observations allowed formulation of a new hypothesis whereby seasonally ice-covered regions like the NEW Polynya promote a unique biologically and physically mediated ârectificationâ of the typical (ice free, low latitude) seasonal cycle of air-sea CO2 flux. The resulting carbon sink is consistent with other productivity estimates and represents an export of biologically cycled carbon either to local sediments or offshore. If this scenario is representative of seasonally ice-covered Arctic shelves, then the rectification process could provide a small, negative feedback to excess atmospheric CO2
Enhancing the osteogenic efficacy of human bone marrow aspirate: concentrating osteoprogenitors using wave-assisted filtration
Background: recent approaches have sought to harness the potential of stem cells to regenerate bone that is lost as a consequence of trauma or disease. Bone marrow aspirate (BMA) provides an autologous source of osteoprogenitors for such applications. However, previous studies indicated that the concentration of osteoprogenitors present in BMA is less than required for robust bone regeneration. We provide further evidence for the importance of BMA enrichment for skeletal tissue engineering strategies using a novel acoustic wave-facilitated filtration strategy to concentrate BMA for osteoprogenitors, clinically applicable for intraoperative orthopedic use.Methods: femoral BMA from 15 patients of an elderly cohort was concentrated for the nucleated cell fraction against erythrocytes and excess plasma volume via size exclusion filtration facilitated by acoustic agitation. The effect of aspirate concentration was assessed by assays for colony formation, flow cytometry, multilineage differentiation and scaffold seeding efficiency.Results: BMA was filtered to achieve a mean 4.2-fold reduction in volume with a corresponding enrichment of viable and functional osteoprogenitors, indicated by flow cytometry and assays for colony formation. Enhanced osteogenic and chondrogenic differentiation was observed using concentrated aspirate and enhanced cell-seeding efficiency onto allogeneic bone graft as an effect of osteoprogenitor concentration relative specifically to the concentration of erythrocytes in the aspirate.Conclusions: these studies provide evidence for the importance of BMA nucleated cell concentration for both cell differentiation and cell seeding efficiency and demonstrate the potential of this approach for intraoperative application to enhance bone healin
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