460 research outputs found

    Consideration of probability of bacterial growth for Jovian planets and their satellites

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    Environmental parameters affecting growth of bacteria are compared with current atmospheric models for Jupiter and Saturn, and with the available physical data for their satellites. Different zones of relative probability of growth are identified for Jupiter and Saturn. Of the more than two dozen satellites, only the largest (Io, Europa, Ganymede, Callisto, and Titan) are found to be interesting biologically. Titan's atmosphere may produce a substantial greenhouse effect providing increased surface temperatures. Models predicting a dense atmosphere are compatible with microbial growth for a range of pressures at Titan's surface. For Titan's surface the probability of growth would be enhanced if: (1) the surface is entirely or partially liquid; (2) volcanism is present; or (3) access to internal heat sources is significant

    Lead Shot Deposition and Distribution In Southern Nevada

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    Densities of lead (Pb) shot in soil and the presence of Pb shot in waterfowl gizzards from past hunting activities at the Overton Wildlife Management Area (OWMA) in southern Nevada were determined. Soil shot densities in fields managed for doves, pheasants and geese, and adjacent fields strictly managed as waterfowl habitat were examined. Soil shot densities ranged from 2,691 to 107,642 Pb shot/ha in waterfowl areas to 649,085 to 862,275 Pb shot/ha in dove management areas. Pb shot deposition rates for the 1998-1999 dove hunting season were also calculated and ranged from 8,970 to 22,559 shot/ha in fields managed primarily for doves. Seventy-one waterfowl gizzards were collected from this management area and examined for the presence of shot. Five percent of the gizzards contained lead shot, with individual birds ranging from 0-5 shot per gizzard. Concentrations of lead shot in the soil at the OWMA are clearly elevated in the fields managed for dove habitat, and the use of Pb shot in these areas could be influencing elevated lead shot densities in the adjacent waterfowl management areas. Seasonal cultivation practices may be influencing the surface availability and depth of Pb shot present in the soil and should be more thoroughly examined before implementing their use as long-term management practices

    The Broken Wing

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    A propagation-separation approach to estimate the autocorrelation in a time-series

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    The paper presents an approach to estimate parameters of a local stationary AR(1) time series model by maximization of a local likelihood function. The method is based on a propagation-separation procedure that leads to data dependent weights defining the local model. Using free propagation of weights under homogeneity, the method is capable of separating the time series into intervals of approximate local stationarity. Parameters in different regions will be significantly different. Therefore the method also serves as a test for a stationary AR(1) model. The performance of the method is illustrated by applications to both synthetic data and real time-series of reconstructed NAO and ENSO indices and GRIP stable isotopes

    Effect of vitamin D metabolites on bone histomorphometry in healthy black and white women: An attempt to unravel the so-called vitamin D paradox in blacks

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    An apparent vitamin D paradox, characterized by lower serum 25-hydroxyvitamin D (25(OH)D) levels and higher bone mineral density, is present in black population. In contrast, blacks have higher serum 1,25-dihydroxyvitamin D (1,25(OH)(2)D) levels. The effect of 1,25(OH)(2)D on the skeleton is not fully understood. We examined serum 25(OH)D, 1,25(OH)(2)D and bone histomorphometry in 50 black and white women (25 each) matched for age, menstrual status, and BMI. Histomorphometric indices related to bone structure, remodeling and mineralization were measured in cancellous bone in iliac bone biopsies. Data analyses led to the following results: 1) serum 25(OH)D was significantly lower and 1,25(OH)(2)D was significantly higher in black than in white women, but neither blacks nor whites revealed significant correlation between these two vitamin D metabolites. 2) there was no significant difference in PTH levels between blacks and whites. 3) except for greater trabecular thickness (Tb.Th) in blacks, there were no significant differences in other histomorphometric variables between the two ethnic groups. 4) osteoid surface (OS/BS), unlabeled osteoid surface (ulOS/BS), and osteoblast surface (ObS/BS) significantly correlated with serum 1,25(OH)(2)D levels. We conclude that lower serum 25(OH)D levels in blacks do not impair bone structure and remodeling, nor decrease bone mineralization. Higher serum 1,25(OH)(2)D levels in blacks may help preserve bone mass by stimulating bone formation via increasing osteoblast number and function, but moderately inhibit terminal bone mineralization as shown by higher ulOS/BS

    Climate variability in the subarctic area for the last 2 millennia

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    To put recent climate change in perspective, it is necessary to extend the instrumental climate records with proxy data from paleoclimate archives. Arctic climate variability for the last 2 millennia has been investigated using statistical and signal analyses from three regionally averaged records from the North Atlantic, Siberia and Alaska based on many types of proxy data archived in the Arctic 2k database v1.1.1. In the North Atlantic and Alaska, the major climatic trend is characterized by long-term cooling interrupted by recent warming that started at the beginning of the 19th century. This cooling is visible in the Siberian region at two sites, warming at the others. The cooling of the Little Ice Age (LIA) was identified from the individual series, but it is characterized by wide-range spatial and temporal expression of climate variability, in contrary to the Medieval Climate Anomaly. The LIA started at the earliest by around AD 1200 and ended at the latest in the middle of the 20th century. The widespread temporal coverage of the LIA did not show regional consistency or particular spatial distribution and did not show a relationship with archive or proxy type either. A focus on the last 2 centuries shows a recent warming characterized by a well-marked warming trend parallel with increasing greenhouse gas emissions. It also shows a multidecadal variability likely due to natural processes acting on the internal climate system on a regional scale. A similar to 16-30-year cycle is found in Alaska and seems to be linked to the Pacific Decadal Oscillation, whereas similar to 20-30- and similar to 50-90-year periodicities characterize the North Atlantic climate variability, likely in relation with the Atlantic Multidecadal Oscillation. These regional features are probably linked to the sea ice cover fluctuations through ice-temperature positive feedback.Peer reviewe

    Assessing the performance of the BARCAST climate field reconstruction technique for a climate with long-range memory

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    The skill of the state-of-the-art climate field reconstruction technique BARCAST (Bayesian Algorithm for Reconstructing Climate Anomalies in Space and Time) to reconstruct temperature with pronounced long-range memory (LRM) characteristics is tested. A novel technique for generating fields of target data has been developed and is used to provide ensembles of LRM stochastic processes with a prescribed spatial covariance structure. Based on different parameter setups, hypothesis testing in the spectral domain is used to investigate if the field and spatial mean reconstructions are consistent with either the fractional Gaussian noise (fGn) process null hypothesis used for generating the target data, or the autoregressive model of order 1 (AR(1)) process null hypothesis which is the assumed temporal evolution model for the reconstruction technique. The study reveals that the resulting field and spatial mean reconstructions are consistent with the fGn process hypothesis for some of the tested parameter configurations, while others are in better agreement with the AR(1) model. There are local differences in reconstruction skill and reconstructed scaling characteristics between individual grid cells, and the agreement with the fGn model is generally better for the spatial mean reconstruction than at individual locations. Our results demonstrate that the use of target data with a different spatiotemporal covariance structure than the BARCAST model assumption can lead to a potentially biased climate field reconstruction (CFR) and associated confidence intervals.</p

    Clinical Inertia in Type 2 Diabetes: A Retrospective Analysis of Pharmacist-Managed Diabetes Care vs. Usual Medical Care

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    Background: Evidence suggests that patients with type 2 diabetes (T2DM) suffer from a high rate of “clinical inertia” or “recognition of the problem but failure to act.” Objective: The aim of this study is to quantify the rate of clinical inertia between two models of care: Pharmacist-Managed Diabetes Clinic (PMDC) vs. Usual Medical Care (UMC). Methods: Patients in a university based medical clinic with type 2 diabetes (T2DM) were analyzed in this retrospective cohort study. Patients were exposed to either PMDC or UMC. The difference in days to intervention in response to suboptimal laboratory values and time to achieve goal hemoglobin A1c (A1c), systolic blood pressure (SBP) and low-density lipoprotein (LDL) was compared in the two models of care. Results: A total of 113 patients were included in the analysis of this study, 54 patients were in the PMDC and 59 patients were in the UMC group. Median time (days) to intervention for A1c values \u3e7% was 8 days and 9 days in the PMDC and UMC groups, respectively (p\u3e0.05). In patients with baseline A1c values \u3e8%, median time to achieving A1c Conclusions: Rates of clinical inertia, defined as time to intervention of suboptimal clinical values, did not differ significantly between patients enrolled in a PMDC compared to patients with UMC with respect to A1c, SBP and LDL. Participation in PMDC, however, was associated with achieving goal A1c, SBP, and LDL levels sooner compared to UMC

    Three-dimensional architecture and hydrostratigraphy of cross-cutting buried valleys using airborne electromagnetics, glaciated Central Lowlands, Nebraska, USA

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    Buried valleys are characteristic features of glaciated landscapes, and their deposits host important aquifers worldwide. Understanding the stratigraphic architecture of these deposits is essential for protecting groundwater and interpreting sedimentary processes in subglacial and ice-marginal environments. The relationships between depositional architecture, topography and hydrostratigraphy in dissected, pre-Illinoian till sheets is poorly understood. Boreholes alone are inadequate to characterize the complex geology of buried valleys, but airborne electromagnetic surveys have proven useful for this purpose. A key question is whether the sedimentary architecture of buried valleys can be interpreted from airborne electromagnetic profiles. This study employs airborne electromagnetic resistivity profiles to interpret the threedimensional sedimentary architecture of cross-cutting buried valleys in a ca 400 km2 area along the western margin of Laurentide glaciation in North America. A progenitor bedrock valley is succeeded by at least five generations of tunnel valleys that become progressively younger northward. Tunnel-valley infills are highly variable, reflecting under-filled and over-filled conditions. Under-filled tunnel valleys are expressed on the modern landscape and contain fine sediments that act as hydraulic barriers. Over-filled tunnel valleys are not recognized in the modern landscape, but where they are present they form hydraulic windows between deep aquifer units and the land surface. The interpretation of tunnel-valley genesis herein provides evidence of the relationships between depositional processes and glacial landforms in a dissected, pre-Illinoian till sheet, and contributes to the understanding of the complex physical hydrology of glacial aquifers in general
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