184 research outputs found

    Dynamics and pattern of a managed coniferous forest landscape in Oregon

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    We examined the process of fragmentation in a managed forest landscape by comparing rates and patterns of disturbance (primarily clear-cutting) and regrowth between 1972 and 1988 using Landsat imagery. A 2589-km(exp 2) managed forest landscape in western Oregon was classified into two forest types, closed-canopy conifer forest (CF) (typically, greater than 60% conifer cover) and other forest and nonforest types (OT) (typically, less than 40 yr old or deciduous forest). The percentage of CF declined from 71 to 58% between 1972 and 1988. Declines were greatest on private land, least in wilderness, and intermediate in public nonwilderness. High elevations (greater than 914 m) maintained a greater percentage of CF than lower elevations (less than 914 m). The percentage of the area at the edge of the two cover types increased on all ownerships and in both elevational zones, whereas the amount of interior habitat (defined as CF at least 100 m from OT) decreased on all ownerships and elevational zones. By 1988 public lands contained approximately 45% interior habitat while private lands had 12% interior habitat. Mean interior patch area declined from 160 to 62 ha. The annual rate of disturbance (primarily clear-cutting) for the entire area including the wilderness was 1.19%, which corresponds to a cutting rotation of 84 yr. The forest landscape was not in a steady state or regulated condition which is not projected to occur for at least 40 yr under current forest plans. Variability in cutting rates within ownerships was higher on private land than on nonreserve public land. However, despite the use of dispersed cutting patterns on public land, spatial patterns of cutting and remnant forest patches were nonuniform across the entire public ownership. Large remaining patches (less than 5000 ha) of contiguous interior forest were restricted to public lands designated for uses other than timber production such as wilderness areas and research natural areas

    Measuring forest landscape patterns in the Cascade Range of Oregon, USA

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    This paper describes the use of a set of spatial statistics to quantify the landscape pattern caused by the patchwork of clearcuts made over a 15-year period in the western Cascades of Oregon. Fifteen areas were selected at random to represent a diversity of landscape fragmentation patterns. Managed forest stands (patches) were digitized and analyzed to produce both tabular and mapped information describing patch size, shape, abundance and spacing, and matrix characteristics of a given area. In addition, a GIS fragmentation index was developed which was found to be sensitive to patch abundance and to the spatial distribution of patches. Use of the GIS-derived index provides an automated method of determining the level of forest fragmentation and can be used to facilitate spatial analysis of the landscape for later coordination with field and remotely sensed data. A comparison of the spatial statistics calculated for the two years indicates an increase in forest fragmentation as characterized by an increase in mean patch abundance and a decrease in interpatch distance, amount of interior natural forest habitat, and the GIS fragmentation index. Such statistics capable of quantifying patch shape and spatial distribution may prove important in the evaluation of the changing character of interior and edge habitats for wildlife

    Monitoring Vibration and Other Critical Machine Conditions

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    Outcomes and Complications With Off-Label Use of Drug-Eluting Stents Results From the STENT (Strategic Transcatheter Evaluation of New Therapies) Group

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    ObjectivesThis study evaluates outcomes and complications in patients treated with drug-eluting stents (DES) for “off-label” indications.BackgroundDrug-eluting stents have been effective in randomized trials, but their safety and efficacy for off-label indications has not been well studied.MethodsThe STENT (Strategic Transcatheter Evaluation of New Therapies) Registry is the largest multicenter U.S. registry evaluating outcomes of DES. Off-label indications included ostial, left main, long, bifurcation, and in-stent restenotic lesions, saphenous vein grafts, chronic total occlusions, small or large vessels, multilesion or multivessel percutaneous coronary interventions, and ST-segment elevation myocardial infarction. Outcomes were adjusted using Cox proportional hazards regression and propensity analyses.ResultsDrug-eluting stents were used in an off-label manner in 59% of patients. The patients who received off-label treatment were more often male, had a higher incidence of prior infarction and bypass surgery, and lower ejection fractions. Off-label versus “on-label” use of DES was associated with higher rates of death, myocardial infarction, target vessel revascularization, major adverse cardiac events, and stent thrombosis at 9 months and 2 years. Off-label use of DES compared with off-label use of bare-metal stents (BMS) had lower rates of death, myocardial infarction, target vessel revascularization, and major adverse cardiac events at 9 months and 2 years and lower rates of stent thrombosis at 9 months.ConclusionsOff-label use of DES is associated with higher event rates compared with on-label use of DES, which is consistent with a higher risk clinical and lesion profile. However, event rates with off-label use of DES are lower compared with off-label use of BMS. Pending results from randomized trials, our data support the use of DES for off-label indications in selected patients

    LSST: from Science Drivers to Reference Design and Anticipated Data Products

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    (Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg2^2 field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5σ\sigma point-source depth in a single visit in rr will be ∌24.5\sim 24.5 (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg2^2 with ÎŽ<+34.5∘\delta<+34.5^\circ, and will be imaged multiple times in six bands, ugrizyugrizy, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg2^2 region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to r∌27.5r\sim27.5. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie
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