451 research outputs found

    Effects of noise and vibration on commercial helicopter pilots. Results of Phase 1 research Final report

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    Noise and vibration effects on commercial helicopter pilot safety, performance, and comfor

    Head-up displays - A study of their applicability in civil aviation

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    Benefits and problems of using head-up displays in commercial and general aviation aircraf

    Paleomagnetism of Jurassic Rocks in the Western Sierra Nevada Metamorphic Belt and its Bearing on the Structural Evolution of the Sierra Nevada Block

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    The western metamorphic belt of the Sierra Nevada consists of two eugeosynclinal terranes separated by the Melones and Sonora faults. Subvertical, bedded Mesozoic volcanic rocks metamorphosed to low greenschist facies predominate to the west, whereas Paleozoic metamorphic rocks of higher grade and greater structural complexity predominate to the east. In order to study the structural development of the faults, 121 samples of basalt and diabase were collected for paleomagnetic analysis from three Jurassic formations, the Logtown Ridge and Penon Blanco formations west of the Melones fault and the Sonora dike swarm to the east of the Sonora fault. A northwesterly, downward directed magnetization occurs in each unit. Three fold tests and a conglomerate test on the two formations west of the faults show that the magnetization is secondary, postdating Nevadan (Late Jurassic) folding and is probably coeval with peak metamorphism. An average of five paleomagnetic poles from the Sierra Nevada, three derived from the secondary magnetizations given herein and two previously published, all of probable Kimmeridgian age, yields λ′=67.2°N, ϕ′=161.2°E, and α95 =6.5°. Southeasterly magnetizations also occur in the Logtown Ridge Formation and Sonora dike swarm. Directions from the Sonora dikes are approximately antipodal to the secondary directions and are reversed; magnetizations from the Logtown Ridge Formation yield similar results only if corrected for the tilt of bedding. The Logtown Ridge magnetizations (tilt-corrected) yield a pole position near to that expected for North America. The data from the Sonora dikes require a tilt correction of 25°-30° toward the south-southwest about a horizontal axis parallel to the regional structure in order to yield a North American pole position. We conclude that the eastern wall rocks of the Melones and Sonora faults have been rotated 25°-30° in response to Nevadan deformation in contrast to the western wall rocks, which have been rotated about 90°

    Evidence of Uppermost Proterozoic to Lower Cambrian miogeoclinal rocks and the Mojave-Snow Lake Fault: Snow Lake Pendant, central Sierra Nevada, California

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    This is the published version. Copyright 2010 American Geophysical Union. All Rights Reserved.Displaced uppermost Precambrian to Lower Cambrian miogeoclinal strata occur within Snow Lake pendant in the central Sierra Nevada. These rocks have been correlated with the Stirling Quartzite, the Wood Canyon Formation, the Zabriskie Quartzite, and the Carrara Formation in the western Mojave Desert and the San Bernardino Mountains (Lahren and Schweickert, 1989; Lahren, 1989). This correlation is based on new, updated, and previously reported data including (1) lithologic similarities, (2) overall stratigraphic sequence, (3) vertical sequence within individual formations, (4) approximate stratigraphic thicknesses, (5) Skolithos in the correct stratigraphie position, (6) depositional environments, and (7) petrographic character and provenance of quartz arenites. The correlation is strengthened by the fact that Snow Lake pendant and the western Mojave share many other close similarities including (1) initial 87Sr/86Sr ratios of associated granitic rocks >0.706, (2) passive margin tectonic setting of Precambrian to Cambrian miogeoclinal rocks, (3) dikes of the Independence dike swarm, (4) possible Lower Triassic overlap sequence, the Fairview Valley Formation, (5) petrographically similar gabbroic complexes of the same age, (6) associated eugeoclinal rocks, and (7) identical(?) pre-Tertiary structural configuration. New U/Pb zircon geochronology unequivocally shows that dikes at Snow Lake pendant are coeval with the Independence dike swarm of the eastern Sierra and the western Mojave desert and that associated gabbroic complexes in both the Mojave and Snow Lake pendant are the same age. Correlation of Snow Lake pendant with the western Mojave requires about 400 km of dextral displacement of the rocks of Snow Lake pendant, together with associated rocks (Snow Lake block), from the western Mojave Desert along the Mojave-Snow Lake fault. Displacement most likely occurred after 150 Ma, the age of the Independence dike swarm, and before about 110 Ma, the age of major plutons within the Sierra Nevada batholith. This interpretation, if correct, holds major implications for allochthonous terranes west of Snow Lake pendant, which were probably attached to the Snow Lake block before its northward transport. In addition, a number of Paleozoic and Mesozoic tectonic features in western Nevada and eastern California may have been offset dextrally along the proposed Mojave-Snow Lake fault

    Magnitude of crustal extension across the northern Basin and Range province: constraints from paleomagnetism

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    The magnitude of crustal extension across the northern Basin and Range province is a matter of longstanding controversy; estimates range from 10 to 300%. Recently published estimates of extension across the southern Basin and Range province (36[deg]N) are in the range of 80-100%. Thus, the larger values suggested for the northern part of the province (40[deg]N) seem to require substantial counterclockwise rotation of the Sierra Nevada during Tertiary extension. Paleomagnetic data from the range, however, limit rotation to 4 +/- 10[deg] at the 95% confidence level. These limits, combined with estimates of extension near the Garlock fault, allow severe constraints to be placed on the magnitude of extension across more northerly parts of the province. We conclude that the maximum extension at 40[deg]N is about 50% and that values of 39 +/- 12% (188 +/- 43 km) are likely.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25578/1/0000122.pd

    An Overview of Antithrombotics in Ischemic Stroke

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    The use of antithrombotic medications is an important component of ischemic stroke treatment and prevention. This article reviews the evidence for best practices for antithrombotic use in stroke with focused discussion on the specific agents used to treat and prevent stroke

    Mobility deficit – Rehabilitate, an opportunity for functionality

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    There are many pathological conditions that cause mobility deficits and that ultimately influence someone’s autonomy.Aims: to evaluate patients with mobility deficits functional status; to implement a Rehabilitation Nursing intervention plan; to monitor health gains through mobility deficits rehabilitation.Conclusion: Early intervention and the implementation of a nursing rehabilitation intervention plan results in health gains (direct or indirect), decreases the risk of developing Pressure Ulcers (PU) and the risk of developing a situation of immobility that affects patients’ autonomy and quality of life

    Telehealth Stroke Education For Rural Elderly Virginians

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    Objective: Stroke is a prevalent condition found in elderly, rural populations. However, stroke education, which can be effective in addressing the risks, is often difficult to provide in these remote regions. The objective of this study is to evaluate the effectiveness of delivering stroke education to elderly individuals through telehealth versus in-person stroke prevention education methods. Materials and Methods: A quasi-experimental nonequivalent control group design was used in this study. A convenience sample of 11 elderly adults (36% men, 64% women) with a mean age of 70 was selected from an Appalachian Program for All Inclusive Care for the Elderly (day care) facility. Subjects completed preintervention surveys, received a 20-min group in-person or telehealth delivered education session, and then completed the postintervention surveys. Results: Satisfaction with delivery method and post-education knowledge was equivalent between the two groups. Knowledge increased in both groups after the educational programs. Likelihood of reducing risk factors showed no differences pre-posttest. However, there were significant improvements in the pre-post likelihood scores of the telehealth group in contrast to the in-person group. Conclusions: This project provided a rural, high-risk population access to telehealth stroke education, thus enabling these individuals to receive education at a distance from experts in the field. The telehealth program was found to be equivalent to in-person stroke education in regards to satisfaction, knowledge, and likelihood of making changes to decrease vascular risk factors. The study demonstrated feasibility in providing effective stroke education through telehealth, thus suggesting an often overlooked route for providing patient education at a distance
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