1,505 research outputs found

    A simple sampling method for estimating the accuracy of large scale record linkage projects

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    Background: Record linkage techniques allow different data collections to be brought together to provide a wider picture of the health status of individuals. Ensuring high linkage quality is important to guarantee the quality and integrity of research. Current methods for measuring linkage quality typically focus on precision (the proportion of incorrect links), given the difficulty of measuring the proportion of false negatives. Objectives: The aim of this work is to introduce and evaluate a sampling based method to estimate both precision and recall following record linkage. Methods: In the sampling based method, record-pairs from each threshold (including those below the identified cut-off for acceptance) are sampled and clerically reviewed. These results are then applied to the entire set of record-pairs, providing estimates of false positives and false negatives. This method was evaluated on a synthetically generated dataset, where the true match status (which records belonged to the same person) was known. Results: The sampled estimates of linkage quality were relatively close to actual linkage quality metrics calculated for the whole synthetic dataset. The precision and recall measures for seven reviewers were very consistent with little variation in the clerical assessment results (overall agreement using the Fleiss Kappa statistics was 0.601). Conclusions: This method presents as a possible means of accurately estimating matching quality and refining linkages in population level linkage studies. The sampling approach is especially important for large project linkages where the number of record pairs produced may be very large often running into millions

    Submarine landslides on the upper southeast Australian passive continental margin – preliminary findings

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    The southeast Australian passive continental margin is narrow, steep and sediment-deficient, and characterized by relatively low rates of modern sedimentation. Upper slope (\u3c1200m) sediments comprise mixtures of calcareous and terrigenous sand and mud. Three of twelve sediment cores recovered from geologically-recent, submarine landslides located offshore New South Wales/Queensland (NSW/QLD) are interpreted to have sampled failure surfaces at depths of between 85 cm and 220 cm below the present-day seabed. Differences in sediment physical properties are recorded above and below the three slide-plane boundaries. Sediment taken directly above the inferred submarine landslide failure surfaces and presumed to be post-landslide, returned radiocarbon ages of 15.8 ka, 20.7 ka and 20.1 ka. The last two ages correspond to adjacent slide features, which are inferred to be consistent with their being triggered by a single event such as an earthquake. Slope stability models based on classical soil mechanics and measured sediment shearstrengths indicate that the upper slope sediments should be stable. However, multibeam sonar data reveal that many upper slope landslides occur across the margin and that submarine landsliding is a common process. We infer from these results that: a) an unidentified mechanism regularly acts to reduce the shear resistance of these sediments to the very low values required to enable slope failure, and/or b) the margin experiences seismic events that act to destabilise the slope sediments

    Autonomous docking ground demonstration (category 3)

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    The NASA Johnson Space Center (JSC) is involved in the development of an autonomous docking ground demonstration. The demonstration combines the technologies, expertise and facilities of the JSC Tracking and Communications Division (EE), Structures and Mechanics Division (ES), and the Navigation, Guidance and Control Division (EG) and their supporting contractors. The autonomous docking ground demonstration is an evaluation of the capabilities of the laser sensor system to support the docking phase (12ft to contact) when operated in conjunction with the Guidance, Navigation and Control Software. The docking mechanism being used was developed for the Apollo Soyuz Test Program. This demonstration will be conducted using the Six-Degrees of Freedom (6-DOF) Dynamic Test System (DTS). The DTS environment simulates the Space Station Freedom as the stationary or target vehicle and the Orbiter as the active or chase vehicle. For this demonstration the laser sensor will be mounted on the target vehicle and the retroreflectors on the chase vehicle. This arrangement was used to prevent potential damage to the laser. The sensor system. GN&C and 6-DOF DTS will be operated closed-loop. Initial condition to simulate vehicle misalignments, translational and rotational, will be introduced within the constraints of the systems involved. Detailed description of each of the demonstration components (e.g., Sensor System, GN&C, 6-DOF DTS and supporting computer configuration) including their capabilities and limitations will be discussed. A demonstration architecture drawing and photographs of the test configuration will be presented

    Historic Archeological Investigations at Roberts Cemetery Near Troy, Bell County, Texas

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    A preliminary archeological investigation was conducted in 2008 at Roberts Cemetery near Troy, Texas, as part of the Texas Department of Transportation’s planned expansion of Interstate Highway 35. Mechanical trenching discovered one unmarked grave near the highway right of way, and this led to an extensive mechanical search of the eastern edge of the cemetery in 2012. Following the removal of the southbound access road and thick layer of artificial fill, five additional unmarked graves were discovered. Of the six unmarked graves, two are located in the cemetery property and were left in place, but the four burials inside the highway right of way were exhumed. They were reinterred in a nearby plot in Roberts Cemetery. Analyses of the mortuary items and skeletal remains indicate that the three adult males and one child were interred between 1895 and the late 1930s. DNA analyses were used to try and match the four interred individuals with possible living relatives, but the results were negative or inconclusive. Archival research provided historical context for Roberts Cemetery and defined the sequence of road expansions that impacted the east side of the cemetery in the twentieth century

    Multispectral imaging of organ viability during uterine transplantation surgery in rabbits and sheep

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    Uterine transplantation surgery (UTx) has been proposed as a treatment for permanent absolute uterine factor infertility (AUFI) in the case of the congenital absence or surgical removal of the uterus. Successful surgical attachment of the organ and its associated vasculature is essential for the organ’s reperfusion and long-term viability. Spectral imaging techniques have demonstrated the potential for the measurement of hemodynamics in medical applications. These involve the measurement of reflectance spectra by acquiring images of the tissue in different wavebands. Measures of tissue constituents at each pixel can then be extracted from these spectra through modeling of the light–tissue interaction. A multispectral imaging (MSI) laparoscope was used in sheep and rabbit UTx models to study short- and long-term changes in oxygen saturation following surgery. The whole organ was imaged in the donor and recipient animals in parallel with point measurements from a pulse oximeter. Imaging results confirmed the re-establishment of adequate perfusion in the transplanted organ after surgery. Cornual oxygenation trends measured with MSI are consistent with pulse oximeter readings, showing decreased StO2 immediately after anastomosis of the blood vessels. Long-term results show recovery of StO2 to preoperative levels

    Phase II Investigations at Prehistoric and Rock Art Sites, Justiceburg Reservoir, Garza and Kent Counties, Texas Volume I

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    Phase II cultural resources investigations at the proposed Justiceburg Reservoir in Garza and Kent counties, Texas, were conducted by Prewitt and Associates, Inc. in 19881989. This report documents the archeological work at 62 prehistoric and aboriginal rock art sites and the geoarcheological study conducted as part of the Phase II work. Investigations at 48 prehistoric sites, including open campsites, rockshelters, lithic procurement sites, faunal localities, and rock art sites, resulted in complete National Register assessments; 9 campsites, the 2 rockshelters, and 6 rock art sites are considered to be eligible for listing on the National Register of Historic Places. Less-intensive investigations at 14 prehistoric sites yielded insufficient data for full National Register assessments. The geoarcheological study resulted in the formulation of a model of the geomorphic history of the project area. Of considerable importance is the recognition of a period of catastrophic flushing of alluvial sediments Within the Double Mountain ~ork valley during the middle Holocene, followed by late Holocene sedimentation and stabilization. This supports the concept of a dry middle Holocene Altitherrnal period and helps explain the biased archeological record in the project area. The prehistoric site investigations indicate that most of the archeological remains present at Justiceburg Reservoir date to the late Archaic and Late Prehistoric periods, a phenomenon noted in similar settings elsewhere in the Lower Plains. Of the open campsites assessed as eligible for listing on the National Register, four are classified as late Archaic (4500-2000 B.P.), two are classified as Late Prehistoric I (2000-1000 8.P.), and three are classified as Late Prehistoric II (1000 B.P. to evidence of European contact). The two investigated rockshelters contain evidence of Late Prehistoric I and II occupations. Due to the paucity of regional archeological data and the lack of a well-defined cultural chronology, only two of these sites can be assigned tentatively to recognized cultural complexes. Site 4lGR291 yielded ceramics and arrow points indicating a Palo Duro Complex occupation, ca. A.D. 500, while ceramics and a distinctive hearth associated with the upper component at 41KTS3 suggest a Garza Complex occupation, ca. A.D. 1600-1700. No evidence of European contact was found at any of the habitation sites, but three of the rock art sites contain historic Plains Indian iconography. The investigations at the prehistoric sites resulted in the formulation of a late Holocene cuItural sequence for the project area. Analyses of the various classes of archeological evidence (e.g., artifacts, features, faunal remains) revealed broad cultural patterns that appear to reflect significant changes in subsistence strategies through time. It is suggested that these changes are related to late Holocene environmental conditions and corresponding shifts in the resource base. It is further suggested that bison were the most important resource controlling late Holocene human adaptations in the Texas Lower Plains

    Phase II Investigations at Prehistoric and Rock Art Sites, Justiceburg Reservoir, Garza and Kent Counties, Texas Volume I

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    Phase II cultural resources investigations at the proposed Justiceburg Reservoir in Garza and Kent counties, Texas, were conducted by Prewitt and Associates, Inc. in 19881989. This report documents the archeological work at 62 prehistoric and aboriginal rock art sites and the geoarcheological study conducted as part of the Phase II work. Investigations at 48 prehistoric sites, including open campsites, rockshelters, lithic procurement sites, faunal localities, and rock art sites, resulted in complete National Register assessments; 9 campsites, the 2 rockshelters, and 6 rock art sites are considered to be eligible for listing on the National Register of Historic Places. Less-intensive investigations at 14 prehistoric sites yielded insufficient data for full National Register assessments. The geoarcheological study resulted in the formulation of a model of the geomorphic history of the project area. Of considerable importance is the recognition of a period of catastrophic flushing of alluvial sediments Within the Double Mountain ~ork valley during the middle Holocene, followed by late Holocene sedimentation and stabilization. This supports the concept of a dry middle Holocene Altitherrnal period and helps explain the biased archeological record in the project area. The prehistoric site investigations indicate that most of the archeological remains present at Justiceburg Reservoir date to the late Archaic and Late Prehistoric periods, a phenomenon noted in similar settings elsewhere in the Lower Plains. Of the open campsites assessed as eligible for listing on the National Register, four are classified as late Archaic (4500-2000 B.P.), two are classified as Late Prehistoric I (2000-1000 8.P.), and three are classified as Late Prehistoric II (1000 B.P. to evidence of European contact). The two investigated rockshelters contain evidence of Late Prehistoric I and II occupations. Due to the paucity of regional archeological data and the lack of a well-defined cultural chronology, only two of these sites can be assigned tentatively to recognized cultural complexes. Site 4lGR291 yielded ceramics and arrow points indicating a Palo Duro Complex occupation, ca. A.D. 500, while ceramics and a distinctive hearth associated with the upper component at 41KTS3 suggest a Garza Complex occupation, ca. A.D. 1600-1700. No evidence of European contact was found at any of the habitation sites, but three of the rock art sites contain historic Plains Indian iconography. The investigations at the prehistoric sites resulted in the formulation of a late Holocene cuItural sequence for the project area. Analyses of the various classes of archeological evidence (e.g., artifacts, features, faunal remains) revealed broad cultural patterns that appear to reflect significant changes in subsistence strategies through time. It is suggested that these changes are related to late Holocene environmental conditions and corresponding shifts in the resource base. It is further suggested that bison were the most important resource controlling late Holocene human adaptations in the Texas Lower Plains

    Phase II Investigations at Prehistoric and Rock Art Sites, Justiceburg Reservoir, Garza and Kent Counties, Texas Volume I

    Get PDF
    Phase II cultural resources investigations at the proposed Justiceburg Reservoir in Garza and Kent counties, Texas, were conducted by Prewitt and Associates, Inc. in 19881989. This report documents the archeological work at 62 prehistoric and aboriginal rock art sites and the geoarcheological study conducted as part of the Phase II work. Investigations at 48 prehistoric sites, including open campsites, rockshelters, lithic procurement sites, faunal localities, and rock art sites, resulted in complete National Register assessments; 9 campsites, the 2 rockshelters, and 6 rock art sites are considered to be eligible for listing on the National Register of Historic Places. Less-intensive investigations at 14 prehistoric sites yielded insufficient data for full National Register assessments. The geoarcheological study resulted in the formulation of a model of the geomorphic history of the project area. Of considerable importance is the recognition of a period of catastrophic flushing of alluvial sediments Within the Double Mountain ~ork valley during the middle Holocene, followed by late Holocene sedimentation and stabilization. This supports the concept of a dry middle Holocene Altitherrnal period and helps explain the biased archeological record in the project area. The prehistoric site investigations indicate that most of the archeological remains present at Justiceburg Reservoir date to the late Archaic and Late Prehistoric periods, a phenomenon noted in similar settings elsewhere in the Lower Plains. Of the open campsites assessed as eligible for listing on the National Register, four are classified as late Archaic (4500-2000 B.P.), two are classified as Late Prehistoric I (2000-1000 8.P.), and three are classified as Late Prehistoric II (1000 B.P. to evidence of European contact). The two investigated rockshelters contain evidence of Late Prehistoric I and II occupations. Due to the paucity of regional archeological data and the lack of a well-defined cultural chronology, only two of these sites can be assigned tentatively to recognized cultural complexes. Site 4lGR291 yielded ceramics and arrow points indicating a Palo Duro Complex occupation, ca. A.D. 500, while ceramics and a distinctive hearth associated with the upper component at 41KTS3 suggest a Garza Complex occupation, ca. A.D. 1600-1700. No evidence of European contact was found at any of the habitation sites, but three of the rock art sites contain historic Plains Indian iconography. The investigations at the prehistoric sites resulted in the formulation of a late Holocene cuItural sequence for the project area. Analyses of the various classes of archeological evidence (e.g., artifacts, features, faunal remains) revealed broad cultural patterns that appear to reflect significant changes in subsistence strategies through time. It is suggested that these changes are related to late Holocene environmental conditions and corresponding shifts in the resource base. It is further suggested that bison were the most important resource controlling late Holocene human adaptations in the Texas Lower Plains

    Phase II Investigations at Prehistoric and Rock Art Sites, Justiceburg Reservoir, Garza and Kent Counties, Texas Volume I

    Get PDF
    Phase II cultural resources investigations at the proposed Justiceburg Reservoir in Garza and Kent counties, Texas, were conducted by Prewitt and Associates, Inc. in 19881989. This report documents the archeological work at 62 prehistoric and aboriginal rock art sites and the geoarcheological study conducted as part of the Phase II work. Investigations at 48 prehistoric sites, including open campsites, rockshelters, lithic procurement sites, faunal localities, and rock art sites, resulted in complete National Register assessments; 9 campsites, the 2 rockshelters, and 6 rock art sites are considered to be eligible for listing on the National Register of Historic Places. Less-intensive investigations at 14 prehistoric sites yielded insufficient data for full National Register assessments. The geoarcheological study resulted in the formulation of a model of the geomorphic history of the project area. Of considerable importance is the recognition of a period of catastrophic flushing of alluvial sediments Within the Double Mountain ~ork valley during the middle Holocene, followed by late Holocene sedimentation and stabilization. This supports the concept of a dry middle Holocene Altitherrnal period and helps explain the biased archeological record in the project area. The prehistoric site investigations indicate that most of the archeological remains present at Justiceburg Reservoir date to the late Archaic and Late Prehistoric periods, a phenomenon noted in similar settings elsewhere in the Lower Plains. Of the open campsites assessed as eligible for listing on the National Register, four are classified as late Archaic (4500-2000 B.P.), two are classified as Late Prehistoric I (2000-1000 8.P.), and three are classified as Late Prehistoric II (1000 B.P. to evidence of European contact). The two investigated rockshelters contain evidence of Late Prehistoric I and II occupations. Due to the paucity of regional archeological data and the lack of a well-defined cultural chronology, only two of these sites can be assigned tentatively to recognized cultural complexes. Site 4lGR291 yielded ceramics and arrow points indicating a Palo Duro Complex occupation, ca. A.D. 500, while ceramics and a distinctive hearth associated with the upper component at 41KTS3 suggest a Garza Complex occupation, ca. A.D. 1600-1700. No evidence of European contact was found at any of the habitation sites, but three of the rock art sites contain historic Plains Indian iconography. The investigations at the prehistoric sites resulted in the formulation of a late Holocene cuItural sequence for the project area. Analyses of the various classes of archeological evidence (e.g., artifacts, features, faunal remains) revealed broad cultural patterns that appear to reflect significant changes in subsistence strategies through time. It is suggested that these changes are related to late Holocene environmental conditions and corresponding shifts in the resource base. It is further suggested that bison were the most important resource controlling late Holocene human adaptations in the Texas Lower Plains
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