1,206 research outputs found

    AIGO: a southern hemisphere detector for the worldwide array of ground-based interferometric gravitational wave detectors

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    This paper describes the proposed AIGO detector for the worldwide array of interferometric gravitational wave detectors. The first part of the paper summarizes the benefits that AIGO provides to the worldwide array of detectors. The second part gives a technical description of the detector, which will follow closely the Advanced LIGO design. Possible technical variations in the design are discussed

    Investigation of single crystal ferrite thin film Semiannual report, 1 Feb. - 31 Jul. 1969

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    Vapor deposition of single crystal thin films of lithium ferrite utilizing ferric chlorid

    Investigation of single crystal ferrite thin films

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    Materials suitable for use in magnetic bubble domain memories were developed for aerospace applications. Practical techniques for the preparation of such materials in forms required for fabrication of computer memory devices were considered. The materials studied were epitaxial films of various compositions of the gallium-substituted yttrium gadolinium iron garnet system. The major emphasis was to determine their bubble properties and the conditions necessary for growing uncracked, high quality films

    Comparative attachment, growth and mortalities of oyster (Crassostrea virginica) spat on slate and oyster shell in the James River, Virginia

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    Slate was investigated as a substitute for oyster shells which are used as a substrate for oyster spat (Crassostrea virginica) settlement in James River, Virginia oyster repletion programs. Oyster shells and slate fragments were planted on adjacent plots in two submerged locations about 825 m apart in July 1984. Quantitative .093 m2 (one ft2) samples were collected by a diver on seven occasions through July 1985, with additional samples collected from teh natural oyster bottoms adjacent to the two areas. Percent mortality, growth and numbers of live spat and spat scars (dead spat) per unit area of bottom were determined. As the end of the study, the number of spat on shell was 4-5 times higher than on slate; however, slate had 5-6 times more spat per unit area of bottom than the shell on the natural bottom. During the July to October setting season mortalities were much higher on slate than on shell; during the remaining period they were high but about equal on both substances

    The use of sonic gear to chart locations of natural bars in lower Chesapeake Bay.

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    An underwater microphone has been developed to detect shell material on the bottom. The system is simple to use and easily constructed. It consists of a microphone encased in a PVC tube and suspended from an A-frame which is towed over the bottom. It is being used along with other methods to chart oyster bottoms in Virginia

    The Effect of Tropical Storm Agnes on Oysters, Hard Clams, Soft Clams, and Oyster Drills in VIrginia

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    Tropical Storm Agnes had a major effect on the molluscan fisheries of Virginia. One effect was the direct mortality of oysters, Crassostrea virginiaa, in the upper parts of many estuaries. Typical losses on leased bottoms were: the James River, 10%; the York River, 2%; the Rappahannock River, 50%; and the Potomac River tributaries (Virginia) 70%. Economic loss was in excess of 7.9 million dollars. There was a nearly complete absence of oyster larvae attachment (setting) in 1972. Other effects of Agnes included a nearly complete loss of soft clams, Mya arenaria, in the Rappahannock River. Hard clams, Meraenaria meraenaria, were killed in the upper part of the York River. Oyster drills, Urosalpinx ainerea, were eliminated from the Rappahannock and reduced greatly in numbers in the York and James Rivers.https://scholarworks.wm.edu/vimsbooks/1074/thumbnail.jp

    Settlement of oysters, Crassostrea virginica (Gmelin, 1791), on oyster shell, expanded shale and tire chips in the James River, Virginia

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    The effectiveness of oyster shell, expanded shale, and tire chips as substrates for settlement of oysters, Crassostrea virgi11ica (Gmelin), was compared at four locations in the James River, Virginia, over three two-week time intervals in August and September, 1988. Only differences between substrate were significant (P \u3c 0.001). Over all locations and time intervals, a significantly higher (P \u3c 0.001) proportion of total oyster settlement occurred on oyster shell (63.8%) than on either tire chips (22.1 %) or expanded shale (14.2%)

    Reliability of a Brief Intercept Survey for Trail Use Behaviors

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    Purpose: This study assessed test-retest reliability of an interviewer-administered trail survey. Methods: An intercept survey was conducted with adults using 2 paved trails in Indiana and South Carolina (N = 295; mean age = 46.9 ± 18 y). The survey included items on frequency and duration of trail use for recreation and transportation, other patterns of trail use, and sociodemographic characteristics. Fiftyfive adults completed the survey twice (2–16 d apart; mean = 7.4 ± 2.6 d). Test-retest reliability was assessed with Spearman rank correlation coefficients, Kappa coefficients, and percent agreement. Results: Kappa coefficients and percent agreement for 9 categorical items ranged from 0.65 to 0.96 and from 64.0% to 98.2%, respectively. Among these items, the lowest Kappas were found for perceived safety (0.65) and reported duration of visits for recreational purposes (0.67). Spearman rank correlation coefficients for travel distance to and on the trail and frequency of trail use during the past 7 days and past 4 weeks ranged from 0.62 to 0.93. Conclusion: Though further assessments of this survey with different populations and types of trails may be warranted, its overall high reliability indicates it can be used by researchers and practitioners in its current form

    Relationship of the 1979 Southern California Radon Anomaly to a possible regional strain event

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    During the second half of 1979, anomalously high emanation of radon was recorded at two stations of the automated radon-thoron monitoring network operated by the W. K. Kellogg Radiation Laboratory of the California Institute of Technology. The two stations exhibiting major anomalies, Kresge and Dalton Canyon, are located approximately 30 km apart on the frontal fault system of the Transverse Ranges of southern California. At Kresge the anomaly began on June 21, 1979, and continued through December 1979. At Dalton Canyon the anomaly started about 3 weeks later and also continued through December 1979. At both sites the anomalous levels of radon decreased (but did not return entirely to normal values) shortly before October 15, 1979. During the week of October 15, 1979, a 6.6-M earthquake occurred about 290 km to the southeast of the two stations, and later in that week, earthquakes of magnitude 4.2 and 4.1 occurred at Malibu and Lytle Creek. The latter two events were within 60 km of the monitors. A radon-thoron monitor at Lytle Creek recorded no long-term anomaly but did record a sharp spikelike decrease in the radon level on October 13, 1979. Coincident with our observations of anomalous radon levels, other investigators have reported anomalies or suspected anomalies in several other geodetic, geophysical, and geochemical signals from the same general region. The rapid temporal development of several of the anomalies together with the large area over which they were observed suggests that a large-scale strain event took place which may have been responsible both for the widespread anomalies and for the seismicity that occurred in the region subsequent to the onset of the anomalies
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