2,721 research outputs found
Assessing the contribution of vegetation to slope stability
Many embankments and cuttings associated with the transportation infrastructure in the UK are only marginally stable. Engineering techniques such as soil nailing, geosynthetic reinforcement, improved drainage and ground improvement by stabilisation are available to improve stability but the cost can be high. A lower cost solution may be to utilise vegetation, either self seeded or planted. The benefits and drawbacks associated with vegetation have been the subject of some debate. The problems caused by vegetation in relation to building foundations are well documented and confirm that vegetation can have very significant influences on geotechnical parameters. Appropriate properly maintained vegetation can have the same significant influence to help provide additional stability to soil slopes. This paper considers the potential engineering influences of vegetation and how it can be characterised on site within a geotechnical framework for stability assessments. The direct reinforcement available from the roots of trees and shrubs is identified as providing one of the most significant contributions to slope stability. Case studies in the UK, Greece and Italy demonstrate how results from in-situ root pull out tests may be used to estimate the potential reinforcement forces available from the roots. A scheme is presented to designate zones of influence within the soil according to the size and nature of the vegetation
Assessment of stable coronary artery disease by cardiovascular magnetic resonance imaging: Current and emerging techniques
Coronary artery disease (CAD) is a leading cause of death and disability worldwide. Cardiovascular magnetic resonance (CMR) is established in clinical practice guidelines with a growing evidence base supporting its use to aid the diagnosis and management of patients with suspected or established CAD. CMR is a multi-parametric imaging modality that yields high spatial resolution images that can be acquired in any plane for the assessment of global and regional cardiac function, myocardial perfusion and viability, tissue characterisation and coronary artery anatomy, all within a single study protocol and without exposure to ionising radiation. Advances in technology and acquisition techniques continue to progress the utility of CMR across a wide spectrum of cardiovascular disease, and the publication of large scale clinical trials continues to strengthen the role of CMR in daily cardiology practice. This article aims to review current practice and explore the future directions of multi-parametric CMR imaging in the investigation of stable CAD
MS 029 Guide to James Greenwood Sr. and Jr., MD\u27s Papers, 1910-1983
The James Greenwood Sr. and Jr., MDs papers consists of article drafts and reprints, professional correspondence, patient notes, journals, and photographs that document the careers of James Greenwood Sr. and James Greenwood Jr. in the fields of neuropsychiatry and neurosurgery, respectively.
See more at https://archives.library.tmc.edu/ms-029
A Long-Term Study of Sex Differences in Attitudes towards Women’s Roles in the Military and in Combat
This study explored changes in attitudes towards women’s roles in society, particularly the military, from 1993 to 2004 using the Spence, Helmreich and Stapp (1973) Attitudes towards Women scale. The researchers surveyed 500 respondents in 1993 and 2,560 between 2002 and 2004, finding that, while both women and men became more equalitarian, women became even more equalitarian. Although both men and women believe that women belong in the military, female respondents felt that women would be just as good as men in combat while men felt that women should not be in combat occupations. The study concludes that traditional stereotypes have changed, but some stereotypes continue to exist, and these stereotypes are still marginalizing the value of women in the military
Improved models of upper-level wind for several astronomical observatories
An understanding of wind speed and direction as a function of height are
critical to the proper modeling of atmospheric turbulence. We have used
radiosonde data from launch sites near significant astronomical observatories
and created mean profiles of wind speed and direction and have also computed
Richardson number profiles. Using data from the last 30 years, we extend the
1977 Greenwood wind profile to include parameters that show seasonal variations
and differences in location. The added information from our models is useful
for the design of adaptive optics systems and other imaging systems. Our
analysis of the Richardson number suggests that persistent turbulent layers may
be inferred when low values are present in our long term averaged data.
Knowledge of the presence of these layers may help with planning for adaptive
optics and laser communications.Comment: 21 pages, 15 Figures, 8 table
Importance of the Doppler Effect to the Determination of the Deuteron Binding Energy
The deuteron binding energy extracted from the reaction
is reviewed with the exact relativistic formula, where
the initial kinetic energy and the Doppler effect are taken into account. We
find that the negligible initial kinetic energy of the neutron could cause a
significant uncertainty which is beyond the errors available up to now.
Therefore, we suggest an experiment which should include the detailed
informations about the initial kinetic energy and the detection angle. It could
reduce discrepancies among the recently reported values about the deuteron
binding energy and pin down the uncertainty due to the Doppler broadening of
ray.Comment: 5 page
Methane Post-Processing and Hydrogen Separation for Spacecraft Oxygen Loop Closure
State-of-the-art life support oxygen recovery technology on the International Space Station is based on the Sabatier reaction where only about half of the oxygen required for the crew is recovered from metabolic carbon dioxide (CO2). The Sabatier reaction produces water as the primary product and methane as a byproduct. Oxygen recovery is constrained by both the limited availability of reactant hydrogen from water electrolysis and Sabatier methane (CH4) being vented as a waste product resulting in a continuous loss of reactant hydrogen. Post-processing methane with the Plasma Pyrolysis Assembly (PPA) to recover this hydrogen has the potential to substantially increase oxygen recovery and thus dramatically reduce the logistical challenges associated with oxygen resupply. The PPA decomposes methane into predominantly hydrogen and acetylene. A purification system is necessary to purify hydrogen before it is recycled back to the Sabatier reactor. Testing and evaluation of acetylene removal systems and PPA system architectures are presented and discussed
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