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https://www.readbyqxmd.com/read/28103552/extending-the-utility-of-the-parabolic-approximation-in-medical-ultrasound-using-wide-angle-diffraction-modeling
#1
Joshua E Soneson
Wide-angle parabolic models are commonly used in geophysics and underwater acoustics but have seen little application in medical ultrasound. Here a wide-angle model for continuous-wave high-intensity ultrasound beams is derived which approximates the diffraction process more accurately than the commonly-used Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation without increasing implementation complexity or computing time. A method for preventing the high spatial frequencies often present in source boundary conditions from corrupting the solution is presented...
January 16, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28096384/holocene-enso-related-cyclic-storms-recorded-by-magnetic-minerals-in-speleothems-of-central-china
#2
Zongmin Zhu, Joshua M Feinberg, Shucheng Xie, Mark D Bourne, Chunju Huang, Chaoyong Hu, Hai Cheng
Extreme hydrologic events such as storms and floods have the potential to severely impact modern human society. However, the frequency of storms and their underlying mechanisms are limited by a paucity of suitable proxies, especially in inland areas. Here we present a record of speleothem magnetic minerals to reconstruct paleoprecipitation, including storms, in the eastern Asian monsoon area over the last 8.6 ky. The geophysical parameter IRMsoft-flux represents the flux of soil-derived magnetic minerals preserved in stalagmite HS4, which we correlate with rainfall amount and intensity...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28091883/ground-penetrating-radar-gpr-responses-for-sub-surface-salt-contamination-and-solid-waste-modeling-and-controlled-lysimeter-studies
#3
Y N S Wijewardana, A T Shilpadi, M I M Mowjood, K Kawamoto, L W Galagedara
The assessment of polluted areas and municipal solid waste (MSW) sites using non-destructive geophysical methods is timely and much needed in the field of environmental monitoring and management. The objectives of this study are (i) to evaluate the ground-penetrating radar (GPR) wave responses as a result of different electrical conductivity (EC) in groundwater and (ii) to conduct MSW stratification using a controlled lysimeter and modeling approach. A GPR wave simulation was carried out using GprMax2D software, and the field test was done on two lysimeters that were filled with sand (Lysimeter-1) and MSW (Lysimeter-2)...
February 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28089534/in-situ-measurements-of-light-absorbing-impurities-in-snow-of-glacier-on-mt-yulong-and-implications-for-radiative-forcing-estimates
#4
Hewen Niu, Shichang Kang, Xiaofei Shi, Rukumesh Paudyal, Yuanqing He, Gang Li, Shijin Wang, Tao Pu, Xiaoyi Shi
The Tibetan Plateau (TP) or the third polar cryosphere borders geographical hotspots for discharges of black carbon (BC). BC and dust play important roles in climate system and Earth's energy budget, particularly after they are deposited on snow and glacial surfaces. BC and dust are two kinds of main light-absorbing impurities (LAIs) in snow and glaciers. Estimating concentrations and distribution of LAIs in snow and glacier ice in the TP is of great interest because this region is a global hotspot in geophysical research...
January 12, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28076657/geophysics-is-not-a-silver-bullet-but-worth-a-shot
#5
EDITORIAL
Kamini Singha
No abstract text is available yet for this article.
January 11, 2017: Ground Water
https://www.readbyqxmd.com/read/28071601/applications-of-nuclear-physics
#6
A C Hayes
Today the applications of nuclear physics span a very broad range of topics and fields. This review discusses a number of aspects of these applications, including selected topics and concepts in nuclear reactor physics, nuclear fusion, nuclear non-proliferation, nuclear-geophysics, and nuclear medicine. The review begins with a historic summary of the early years in applied nuclear physics, with an emphasis on the huge developments that took place around the time of World War II, and that underlie the physics involved in designs of nuclear explosions, controlled nuclear energy, and nuclear fusion...
February 2017: Reports on Progress in Physics
https://www.readbyqxmd.com/read/28059760/volcanic-tremor-and-plume-height-hysteresis-from-pavlof-volcano-alaska
#7
David Fee, Matthew M Haney, Robin S Matoza, Alexa R Eaton, Peter Cervelli, David J Schneider, Alexandra M Iezzi
The March 2016 eruption of Pavlof Volcano, Alaska, produced an ash plume that caused the cancellation of more than 100 flights in North America. The eruption generated strong tremor that was recorded by seismic and remote low-frequency acoustic (infrasound) stations, including the EarthScope Transportable Array. The relationship between the tremor amplitudes and plume height changes considerably between the waxing and waning portions of the eruption. Similar hysteresis has been observed between seismic river noise and discharge during storms, suggesting that flow and erosional processes in both rivers and volcanoes can produce irreversible structural changes that are detectable in geophysical data...
January 6, 2017: Science
https://www.readbyqxmd.com/read/28018798/exact-solutions-for-unsteady-free-convection-flow-over-an-oscillating-plate-due-to-non-coaxial-rotation
#8
Ahmad Qushairi Mohamad, Ilyas Khan, Zulkhibri Ismail, Sharidan Shafie
BACKGROUND: Non-coaxial rotation has wide applications in engineering devices, e.g. in food processing such as mixer machines and stirrers with a two-axis kneader, in cooling turbine blades, jet engines, pumps and vacuum cleaners, in designing thermal syphon tubes, and in geophysical flows. Therefore, this study aims to investigate unsteady free convection flow of viscous fluid due to non-coaxial rotation and fluid at infinity over an oscillating vertical plate with constant wall temperature...
2016: SpringerPlus
https://www.readbyqxmd.com/read/28018749/focused-training-for-humanitarian-responders-in-regional-anesthesia-techniques-for-a-planned-randomized-controlled-trial-in-a-disaster-setting
#9
Adam R Aluisio, Carrei Teicher, Tess Wiskel, Allysia Guy, Adam Levine
BACKGROUND: Lower extremity trauma during earthquakes accounts for the largest burden of geophysical disaster-related injuries. Insufficient pain management is common in disaster settings, and regional anesthesia (RA) has the potential to reduce pain in injured patients beyond current standards. To date, no prospective research has evaluated the use of RA in a disaster setting. This cross-sectional study assesses knowledge translation and skill acquisition outcomes for lower extremity RA performed with and without ultrasound guidance among a cohort of Médecins Sans Frontières (MSF) volunteers who will function as proceduralists in a planned randomized controlled trial evaluating the efficacy of RA for pain management in an earthquake setting...
November 16, 2016: PLoS Currents
https://www.readbyqxmd.com/read/27999307/autonomous-aeromagnetic-surveys-using-a-fluxgate-magnetometer
#10
Douglas G Macharet, Héctor I A Perez-Imaz, Paulo A F Rezeck, Guilherme A Potje, Luiz C C Benyosef, André Wiermann, Gustavo M Freitas, Luis G U Garcia, Mario F M Campos
Recent advances in the research of autonomous vehicles have showed a vast range of applications, such as exploration, surveillance and environmental monitoring. Considering the mining industry, it is possible to use such vehicles in the prospection of minerals of commercial interest beneath the ground. However, tasks such as geophysical surveys are highly dependent on specific sensors, which mostly are not designed to be used in these new range of autonomous vehicles. In this work, we propose a novel magnetic survey pipeline that aims to increase versatility, speed and robustness by using autonomous rotary-wing Unmanned Aerial Vehicles (UAVs)...
December 17, 2016: Sensors
https://www.readbyqxmd.com/read/27996242/coupled-hydro-biogeochemical-processes-controlling-cr-reductive-immobilization-in-columbia-river-hyporheic-zone
#11
Yuanyuan Liu, Fen Xu, Chongxuan Liu
An experiment and modeling study was conducted to investigate coupled hydro-biogeochemical processes controlling reductive immobilization of groundwater Cr in the hyporheic zone (HZ) at U.S. Department of Energy's Hanford Site, where dynamic surface water-groundwater exchange occurs on a daily basis. Experiments were performed to calibrate kinetic models and the calibrated models were incorporated into a multicomponent reactive transport model to simulate Cr redox transformation and immobilization under field hydrological conditions...
December 20, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27981466/multiple-geophysical-surveys-for-old-landfill-monitoring-in-singapore
#12
Ke Yin, Huanhuan Tong, Apostolos Giannis, Jing-Yuan Wang, Victor W-C Chang
One-dimensional boring presents limitations on mapping the refuse profile in old landfills owning to waste heterogeneity. Electrical imaging (EI) and multiple-analysis of surface wave (MASW) were hereby deployed at an old dumping ground in Singapore to explore the subsurface in relation to geotechnical analysis. MASW estimated the refuse boundary with a higher precision as compared to EI, due to its endurance for moisture variation. EI and MASW transection profiles suggested spots of interest, e.g., refuse pockets and leachate mounds...
January 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/27969550/characterizing-flow-pathways-in-a-sandstone-aquifer-tectonic-vs-sedimentary-heterogeneities
#13
G Medici, L J West, N P Mountney
Sandstone aquifers are commonly assumed to represent porous media characterized by a permeable matrix. However, such aquifers may be heavy fractured when rock properties and timing of deformation favour brittle failure and crack opening. In many aquifer types, fractures associated with faults, bedding planes and stratabound joints represent preferential pathways for fluids and contaminants. In this paper, well test and outcrop-scale studies reveal how strongly lithified siliciclastic rocks may be entirely dominated by fracture flow at shallow depths (≤180m), similar to limestone and crystalline aquifers...
September 24, 2016: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/27958422/first-mesospheric-wind-images-using-the-michelson-interferometer-for-airglow-dynamics-imaging
#14
J A Langille, W E Ward, T Nakamura
The Michelson interferometer for airglow dynamics imaging (MIADI) is a ground-based instrument that combines an imaging capability with the Doppler Michelson interferometry in order to remotely detect motions in the mesopause region using spectrally isolated airglow emissions: the O(S1) emission at 557.73 nm and the OH (6, 2) P1 (2) at 839.918 nm. A measurement and analysis approach has been developed that allows simultaneous images of the line-of-sight Doppler wind field and irradiance field to be obtained...
December 10, 2016: Applied Optics
https://www.readbyqxmd.com/read/27941823/meandering-instability-of-air-flow-in-a-granular-bed-self-similarity-and-fluid-solid-duality
#15
Yuki Yoshimura, Yui Yagisawa, Ko Okumura
Meandering instability is familiar to everyone through river meandering or small rivulets of rain flowing down a windshield. However, its physical understanding is still premature, although it could inspire researchers in various fields, such as nonlinear science, fluid mechanics and geophysics, to resolve their long-standing problems. Here, we perform a small-scale experiment in which air flow is created in a thin granular bed to successfully find a meandering regime, together with other remarkable fluidized regimes, such as a turbulent regime...
December 12, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27935944/novel-and-lost-forests-in-the-upper-midwestern-united-states-from-new-estimates-of-settlement-era-composition-stem-density-and-biomass
#16
Simon J Goring, David J Mladenoff, Charles V Cogbill, Sydne Record, Christopher J Paciorek, Stephen T Jackson, Michael C Dietze, Andria Dawson, Jaclyn Hatala Matthes, Jason S McLachlan, John W Williams
BACKGROUND: EuroAmerican land-use and its legacies have transformed forest structure and composition across the United States (US). More accurate reconstructions of historical states are critical to understanding the processes governing past, current, and future forest dynamics. Here we present new gridded (8x8km) reconstructions of pre-settlement (1800s) forest composition and structure from the upper Midwestern US (Minnesota, Wisconsin, and most of Michigan), using 19th Century Public Land Survey System (PLSS), with estimates of relative composition, above-ground biomass, stem density, and basal area for 28 tree types...
2016: PloS One
https://www.readbyqxmd.com/read/27930332/state-estimation-and-prediction-using-clustered-particle-filters
#17
Yoonsang Lee, Andrew J Majda
Particle filtering is an essential tool to improve uncertain model predictions by incorporating noisy observational data from complex systems including non-Gaussian features. A class of particle filters, clustered particle filters, is introduced for high-dimensional nonlinear systems, which uses relatively few particles compared with the standard particle filter. The clustered particle filter captures non-Gaussian features of the true signal, which are typical in complex nonlinear dynamical systems such as geophysical systems...
December 20, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27929057/the-importance-of-structural-softening-for-the-evolution-and-architecture-of-passive-margins
#18
T Duretz, B Petri, G Mohn, S M Schmalholz, F L Schenker, O Müntener
Lithospheric extension can generate passive margins that bound oceans worldwide. Detailed geological and geophysical studies in present and fossil passive margins have highlighted the complexity of their architecture and their multi-stage deformation history. Previous modeling studies have shown the significant impact of coarse mechanical layering of the lithosphere (2 to 4 layer crust and mantle) on passive margin formation. We built upon these studies and design high-resolution (~100-300 m) thermo-mechanical numerical models that incorporate finer mechanical layering (kilometer scale) mimicking tectonically inherited heterogeneities...
December 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27924928/unified-rheology-of-vibro-fluidized-dry-granular-media-from-slow-dense-flows-to-fast-gas-like-regimes
#19
Andrea Gnoli, Antonio Lasanta, Alessandro Sarracino, Andrea Puglisi
Granular media take on great importance in industry and geophysics, posing a severe challenge to materials science. Their response properties elude known soft rheological models, even when the yield-stress discontinuity is blurred by vibro-fluidization. Here we propose a broad rheological scenario where average stress sums up a frictional contribution, generalizing conventional μ(I)-rheology, and a kinetic collisional term dominating at fast fluidization. Our conjecture fairly describes a wide series of experiments in a vibrofluidized vane setup, whose phenomenology includes velocity weakening, shear thinning, a discontinuous thinning transition, and gaseous shear thickening...
December 7, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27922007/generation-of-internal-solitary-waves-by-frontally-forced-intrusions-in-geophysical-flows
#20
Daniel Bourgault, Peter S Galbraith, Cédric Chavanne
Internal solitary waves are hump-shaped, large-amplitude waves that are physically analogous to surface waves except that they propagate within the fluid, along density steps that typically characterize the layered vertical structure of lakes, oceans and the atmosphere. As do surface waves, internal solitary waves may overturn and break, and the process is thought to provide a globally significant source of turbulent mixing and energy dissipation. Although commonly observed in geophysical fluids, the origins of internal solitary waves remain unclear...
December 6, 2016: Nature Communications
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