5,618 research outputs found

    Results of Dover Sole tagging in waters off Northern California, 1969-1971

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    Three seasonal trawl tagging cruises were undertaken by the California Department of Fish and Game between 1969 and 1971 to determine the distribution, abundance and stock identity of Dover sole (Microstomus pacificus)in the area between Cape Mendocino in northern California and Cape Blanco in southern Oregon. A total of 4730 Dover sole was tagged and released. Through 1984 26% (1235) were recovered. Recapture rates from the tagging cruises were 32% for the spring cruise, 28% for fall, and 15% for winter. Only 13 of 1235 tags were recaptured outside of PMFC 2A and 1C areas (Cape Blanco to Cape Mendocino). The mean north-south dispersion of tagged Dover sole from point of release was 10.2 nautical miles (nm). The maximum distances moved from tagging sites were 215 nm southward and 211 nm northward. A stock unique for management purposes is indicated by the tag recoveries. A seasonal migration by female Dover sole to deep-water grounds in fall and winter was demonstrated. Several estimates of total mortality (Z) were generated by regression of recoveries on time-at-liberty for all recoveries and for shallow- and deep-water returns, separately. Values were 0.41, 0.61, and 0.31, respectively. (84pp.

    The use of an airborne lidar for mapping cirrus clouds in FIRE, phase 2

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    The Univ. of Washington (UW) and Georgia Tech have recently built a dual wavelength airborne lidar for operation on the UW's Convair C-131A research aircraft. This lidar was used in studying aerosols and clouds. These studies demonstrated the utility of airborne lidar in a variety of atmospheric research and prompt the suggestion that this facility be included in the next FIRE cirrus experiment. The vertically pointing airborne lidar would be used as a complement to ground based lidars. The airborne lidar would ensure extended coverage of IFO cases that develop upwind of the surface lidars or which miss the ground based lidars while still being the focus of satellite and aircraft in situ studies. The airborne lidar would help assure that cirrus clouds were simultaneously viewed by satellite, sampled by aircraft, and structurally characterized by lidar. System specifications are listed and a schematic is shown of the lidar system aboard the C-131A

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    Spectral absorption of marine stratocumulus clouds derived from in situ cloud radiation measurements

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    A multiwavelength scanning radiometer was used to measure the angular distribution of scattered radiation deep within a cloud layer at discrete wavelengths between 0.5 and 2.3 microns. The relative angular distribution of the intensity field at each wavelength is used to determine the similarity parameter, and hence single scattering albedo, of the cloud at that wavelength using the diffusion domain method. In addition to the spectral similarity parameter, the analysis provides a good estimate of the optical thickness of the cloud beneath the aircraft. In addition to the radiation measurements, microphysical and thermodynamic measurements were obtained from which the expected similarity parameter spectrum was calculated using accepted values of the refractive index of liquid water and the transmission function of water vapor. An analysis is presented for the results obtained for a 50 km section of clean marine stratocumulus clouds on 10 July 1987. These observations were obtained off the coast of California from the University of Washington Convair C-131A aircraft as part of the First ISCCP Regional Experiment (FIRE). A comparison of the experimentally-derived similarity parameter spectrum with that expected theoretically from the cloud droplet size distribution measured simultaneously from the aircraft is presented. The measurements and theory are in very close agreement for this case of clean maritime clouds

    Cloud absorption properties as derived from airborne measurements of scattered radiation within clouds

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    Researchers briefly review the diffusion domain method for deriving the cloud similarity parameter and present preliminary analyses of the results thus far obtained. The presentation concentrates on the following points: (1) intercomparison of calibrated reflected intensities between the cloud absorption radiometer and the U.K. multispectral cloud radiometer; (2) quality control tests required to select those portions of an aircraft flight for which measurements are obtained within the diffusion domain; (3) case studies of the spectral similarity parameter of marine stratocumulus clouds; and comparisons of the experimentally-derived similarity parameter spectrum with that expected theoretically from the cloud droplet size distribution obtained from in situ observations

    In situ measurements of ship tracks

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    It has long been known that cloud droplet concentrations are strongly influenced by cloud condensation nuclei (CCN) and that anthropogenic sources of pollution can affect CCN concentrations. More recently it has been suggested that CCN may play an important role in climate through their effect on cloud albedo. A interesting example of the effect of anthropogenic CCN on cloud albedo is the so-called 'ship track' phenomenon. Ship tracks were first observed in satellite imagery when the ship's emissions were evidently needed for the formation of a visible cloud. However, they appear more frequently in satellite imagery as modifications to existing stratus and stratocumulus clouds. The tracks are seen most clearly in satellite imagery by comparing the radiance at 3.7 microns with that at 0.63 and 11 microns. To account for the observed change in radiance, droplet concentrations must be high, and the mean size of the droplets small, in ship tracks. Researchers describe what they believe to be the first in situ measurements in what appears to have been a ship track

    Biomechanical Model for Evaluation of Pediatric Upper Extremity Joint Dynamics During Wheelchair Mobility

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    Pediatric manual wheelchair users (MWU) require high joint demands on their upper extremity (UE) during wheelchair mobility, leading them to be at risk of developing pain and pathology. Studies have examined UE biomechanics during wheelchair mobility in the adult population; however, current methods for evaluating UE joint dynamics of pediatric MWU are limited. An inverse dynamics model is proposed to characterize three-dimensional UE joint kinematics and kinetics during pediatric wheelchair mobility using a SmartWheel instrumented handrim system. The bilateral model comprises thorax, clavicle, scapula, upper arm, forearm, and hand segments and includes the sternoclavicular, acromioclavicular, glenohumeral, elbow and wrist joints. A single 17 year-old male with a C7 spinal cord injury (SCI) was evaluated while propelling his wheelchair across a 15-meter walkway. The subject exhibited wrist extension angles up to 60°, large elbow ranges of motion and peak glenohumeral joint forces up to 10% body weight. Statistically significant asymmetry of the wrist, elbow, glenohumeral and acromioclavicular joints was detected by the model. As demonstrated, the custom bilateral UE pediatric model may provide considerable quantitative insight into UE joint dynamics to improve wheelchair prescription, training, rehabilitation and long-term care of children with orthopedic disabilities. Further research is warranted to evaluate pediatric wheelchair mobility in a larger population of children with SCI to investigate correlations to pain, function and transitional changes to adulthood

    Incidentally detected stenoses proximal to grafts originating below the common femoral artery: Do they affect graft patency or warrant repair in asymptomatic patients?

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    AbstractObjective: Stenoses in infrainguinal arteries proximal to a lower extremity vein graft may reduce flow velocity through the bypass graft and are thought to predispose to graft occlusion. Repair of these lesions has been recommended to preserve graft function. This study was undertaken to better define the natural history of grafts below inflow lesions and to evaluate the necessity of repair to preserve graft patency. Methods: From 1994 through 1999, patients undergoing lower extremity vein grafts by a single surgeon at a university hospital and an affiliated teaching hospital were placed in a prospective protocol for proximal infrainguinal native artery and graft surveillance through use of duplex scanning. The records of those patients with grafts originating distal to the common femoral artery were evaluated; they form the basis for this report. Arteriograms were obtained before bypass grafting, and no patient had a stenosis greater than 50% diameter reduction proximal to the graft origin. Follow-up scans were obtained from the common femoral artery through the graft and outflow artery. The peak systolic velocity and velocity ratio in an infrainguinal native artery proximal to the graft origin were recorded, as were the location and the time interval since the bypass graft. Repair of these proximal lesions was not performed during the course of this study. Revision of the bypass graft or its anastomoses was undertaken according to preestablished duplex scan criteria. Results: During this time, 288 autogenous infrainguinal bypass grafts were performed, of which 159 originated below the common femoral artery; of these, 74 were from the superficial femoral artery, 29 from the profunda femoris artery, 49 from the popliteal artery, and 7 from a tibial artery. The maximum peak systolic velocity proximal to the graft origin was more than 250 in 38 arteries (25%) and more than 300 in 26 arteries (16%). The velocity ratio was 3.0 or more in 32 arteries at the same location as the peak systolic velocity and 3.5 or more in 23 arteries (15%), confirming hemodynamically significant stenoses at these sites. The location of peak systolic velocity was the common femoral artery in 81 patients (51%), the superficial femoral artery in 50 (31%), the popliteal artery in 22 (14%), and a tibial artery in 6 (4%). Follow-up ranged from 8 to 60 months (mean, 35 months). During follow-up, 19 patients died, 18 with patent grafts. Overall, nine grafts occluded. One of the occluded grafts had a velocity ratio greater than 3.0; this may have contributed to graft thrombosis. The other occlusions resulted from an unrepaired graft lesion in 2 patients, graft infection in 2 patients, and graft ligation necessitated by below-knee amputation in 2 patients. No cause for the occlusion could be identified in two of the grafts (neither had evidence of proximal arterial stenosis). Assisted primary patency rates were 95% and 91% at 3 and 5 years, respectively. Conclusions: For grafts originating distal to the common femoral artery, stenoses proximal to the graft do not affect bypass graft patency and do not require repair to prevent graft occlusion. Surveillance of these lesions may therefore be unnecessary, inasmuch as the repair of proximal lesions should not be undertaken to preserve graft function. (J Vasc Surg 2000;32:1180-9.

    A refutation to 'A new A-P compartment boundary and organizer in holometabolous insect wings'.

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    We respond to a recent report by Abbasi and Marcus who present two main findings: first they argue that there is an organiser and a compartment boundary within the posterior compartment of the butterfly wing. Second, they present evidence for a previously undiscovered lineage boundary near wing vein 5 in Drosophila, a boundary that delineates a "far posterior" compartment. Clones of cells were marked with the yellow mutation and they reported that these clones always fail to cross a line close to vein 5 on the Drosophila wing. In our hands yellow proved an unusable marker for clones in the wing blade and therefore we reexamined the matter. We marked clones of cells with multiple wing hairs or forked and found a substantial proportion of these clones cross the proposed lineage boundary near vein 5, in conflict with their findings and conclusion. As internal controls we showed that these same clones respect the other two well established compartment boundaries: the anteroposterior compartment boundary is always respected. The dorsoventral boundary is mostly respected, and is crossed only by clones that are induced early in development, consistent with many reports. We question the validity of Abbasi and Marcus' conclusions regarding the butterfly wing but present no new data.Arising from: R. Abbasi and J. M. Marcus Sci. Rep. 7, 16337 (2017); https://doi.org/10.1038/s41598-017-16553-5 .WELLCOME TRUST 107060/Z/15/

    Agricultural Water Conservation and Efficiency in California - A Commentary

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    This is a Commentary on some of the key points that are presented in “More with Less: Agricultural Water Conservation and Efficiency in California” by Cooley, ChristianSmith, and Gleick of the Pacific Institute, September 2008 (referred to as the “PacInst Paper” in the remainder of this discussion). The authors of this Commentary have over 120 years combined of experience in agricultural and landscape irrigation. They have worked world-wide in design and installation of all types of irrigation systems (including automated drip systems from 1975 on), design and implementation of irrigation scheduling programs since 1977; design and implementation of water conservation programs at state, water district, and farm levels; teaching programs regarding water-related energy efficiency in both university and extension environments; and basic and applied research. Summary biographies are attached at the end of this discussio
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