Read by QxMD icon Read


José I Cardesa, Alberto Vela-Martín, Javier Jiménez
To the naked eye, turbulent flows exhibit whirls of many different sizes. To each size, or scale, corresponds a fraction of the total energy resulting from a cascade in five dimensions: scale, time, and three-dimensional space. Understanding this process is critical to strategies for modeling geophysical and industrial flows. By tracking the flow regions containing energy in different scales, we have detected the statistical predominance of a cross-scale link whereby fluid lumps of energy at scale Δ appear within lumps of scale 2Δ and die within those of scale Δ/2...
August 17, 2017: Science
Adrian F Tuck
Proposed Empirical Entropy and Gibbs Energy Based on Observations of Scale Invariance in Open Non-Equilibrium Systems Abstract There is no widely agreed definition of entropy, and consequently Gibbs energy, in open systems far from equilibrium. One recent approach has sought to formulate an entropy and Gibbs energy based on observed scale invariances in geophysical variables, particularly in atmospheric quantities, including the molecules constituting stratospheric chemistry. The Hamiltonian flux dynamics of energy in macroscopic open non-equilibrium systems maps to energy in equilibrium statistical thermodynamics, and corresponding equivalences of scale invariant variables with other relevant statistical mechanical variables such as entropy, Gibbs energy and 1/(kBoltzmannT) are not just formally analogous but are also mappings...
August 14, 2017: Journal of Physical Chemistry. A
Saikiran Tharimena, Catherine Rychert, Nicholas Harmon
Thick, rigid continents move over the weaker underlying mantle, although geophysical and geochemical constraints on the exact thickness and defining mechanism of the continental plates are widely discrepant. Xenoliths suggest a chemical continental lithosphere ~175 kilometers thick, whereas seismic tomography supports a much thicker root (>250 kilometers) and a gradual lithosphere-asthenosphere transition, consistent with a thermal definition. We modeled SS precursor waveforms from continental interiors and found a 7 to 9% velocity drop at depths of 130 to 190 kilometers...
August 11, 2017: Science
Xiao Liu, Hao Wang, Weimin Wang, Zhengyi Fu
An empirical model based on the bond valence model has been presented to predict the bulk modulus of crystal materials. The bond bulk modulus, in terms of bond valences and bond length, is introduced to describe the resisting ability of a chemical bond to compression. Both the bond bulk modulus and bond density are proposed to be the most important parameters related to the bulk modulus of crystals. For typical A(N)B(8-N) and AmBn type crystals, the calculated bulk modulus is in good agreement with experimental values...
August 10, 2017: Physical Chemistry Chemical Physics: PCCP
Bo Dang, Ling Yang, Na Du, Changzan Liu, Ruirong Dang, Bin Wang, Yan Xie
Transient electromagnetic (TEM) techniques are widely used in the field of geophysical prospecting. In borehole detection, the nondestructive inspection (NDI) of a metal pipe can be performed efficiently using the properties of eddy currents. However, with increasing concern for safety in oil and gas production, more than one string of pipe is used to protect wellbores, which complicates data interpretation. In this paper, an auxiliary sensor-based borehole TEM system for the NDI of multipipe strings is presented...
August 9, 2017: Sensors
Shi-Jin Feng, Zhen-Bai Bai, Ben-Yi Cao, Shi-Feng Lu, Shu-Gang Ai
Leachate is a polluting liquid which may cause harmful effects on human health or the environment without a tightly control manner. The leachate management is an important part of the design and operation of bioreactor landfills. To detect the leachate distribution in Laogang Landfill, China, the measurement of electrical resistivity tomography (ERT) was carried out in three areas with different ages. ERT method proved to be an effective non-invasive geophysical method in bioreactor landfills, and the physical properties of waste samples obtained by boreholes were tested in a laboratory...
August 9, 2017: Environmental Science and Pollution Research International
Clare Donaldson, Corentin Caudron, Robert G Green, Weston A Thelen, Robert S White
Seismic noise interferometry allows the continuous and real-time measurement of relative seismic velocity through a volcanic edifice. Because seismic velocity is sensitive to the pressurization state of the system, this method is an exciting new monitoring tool at active volcanoes. Despite the potential of this tool, no studies have yet comprehensively compared velocity to other geophysical observables on a short-term time scale at a volcano over a significant length of time. We use volcanic tremor (~0.3 to 1...
June 2017: Science Advances
Tina Hecksher, Darius H Torchinsky, Christoph Klieber, Jeremy A Johnson, Jeppe C Dyre, Keith A Nelson
Diverse material classes exhibit qualitatively similar behavior when made viscous upon cooling toward the glass transition, suggesting a common theoretical basis. We used seven different measurement methods to determine the mechanical relaxation kinetics of a prototype molecular glass former over a temporal range of 13 decades and over a temperature range spanning liquid to glassy states. The data conform to time-temperature superposition for the main (alpha) process and to a scaling relation of schematic mode-coupling theory...
August 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
Weizeng Shao, Yexin Sheng, Jian Sun
The Chinese Gaofen-3 (GF-3) synthetic aperture radar (SAR) launched by the China Academy of Space Technology (CAST) has operated at C-band since September 2016. To date, we have collected 16/42 images in vertical-vertical (VV)/horizontal-horizontal (HH) polarization, covering the National Data Buoy Center (NDBC) buoy measurements of the National Oceanic and Atmospheric Administration (NOAA) around U.S. western coastal waters. Wind speeds from NDBC in situ buoys are up to 15 m/s and buoy-measured significant wave height (SWH) has ranged from 0...
July 25, 2017: Sensors
Sergio S Rubin, Irma Marín, Manuel J Gómez, Eduardo A Morales, Ivar Zekker, Patxi San Martín, Nuria Rodríguez, Ricardo Amils
Salar de Uyuni (SdU), with a geological history that reflects 50,000 years of climate change, is the largest hypersaline salt flat on Earth and is estimated to be the biggest lithium reservoir in the world. Its salinity reaches saturation levels for NaCl, a kosmotropic salt, and high concentrations of MgCL2 and LiCl, both salts considered important chaotrophic stressors. In addition, extreme temperatures, anoxic conditions, high UV irradiance, high albedo, and extremely low concentrations of phosphorous, make SdU a unique natural extreme environment in which to contrast hypotheses about limiting factors of life diversification...
July 28, 2017: Environmental Microbiology
Johann P Klages, Gerhard Kuhn, Claus-Dieter Hillenbrand, James A Smith, Alastair G C Graham, Frank O Nitsche, Thomas Frederichs, Patrycja E Jernas, Karsten Gohl, Lukas Wacker
Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5-19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potential shelf refugia for Antarctic benthos during the last glacial period. However, reliable reconstructions are still lacking for many WAIS sectors, particularly for key areas on the outer continental shelf, where the LGM-ice sheet is assumed to have terminated...
2017: PloS One
Ronald Aznavourian, Tania Michelle Guenneau-Puvirajesinghe, Stephane Brule, Stefan Enoch, Sebastien Roger Guenneau
We begin with a brief historical survey of discoveries of quasi-crystals and graphene, and then introduce the concept of transformation crystallography, which consists of the application of geometric transforms to periodic structures. We consider motifs with three-fold, four-fold and six-fold symmetries according to the crystallographic restriction theorem. Furthermore, we define motifs with five-fold symmetry such as quasi-crystals generated by a cut-and-projection method from periodic structures in higher-dimensional space...
July 25, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
João Carlos Nascimento de Alencar, Mario André Leocardio-Miguel, Leandro Lourenção Duarte, Fernando Louzada, John Fontenele Araujo, Mario Pedrazzoli
BACKGROUND: Daylight Saving Time (DST) annually moves clocks one hour forward, when daytime is longer than night. Previous studies from medium and high latitude locations have pointed to a disruptive effect of DST on human circadian rhythms. Since Brazil is an equatorial country implementing DST, a different relationship between photic and social synchronizers may interfere with DST effects. AIM: To explore the prevalence and duration of self-reported discomfort related to DST among Brazilian residents (lat...
July 17, 2017: Annals of Human Biology
Yongchao Zhu, Kegen Yu, Jingui Zou, Jens Wickert
Global Navigation Satellite System (GNSS) signals can be exploited to remotely sense atmosphere and land and ocean surface to retrieve a range of geophysical parameters. This paper proposes two new methods, termed as power-summation of differential Delay-Doppler Maps (PS-D) and pixel-number of differential Delay-Doppler Maps (PN-D), to distinguish between sea ice and sea water using differential Delay-Doppler Maps (dDDMs). PS-D and PN-D make use of power-summation and pixel-number of dDDMs, respectively, to measure the degree of difference between two DDMs so as to determine the transition state (water-water, water-ice, ice-ice and ice-water) and hence ice and water are detected...
July 12, 2017: Sensors
M C Strzelecki, M Kasprzak, M Lim, Z M Swirad, M Jaskólski, Ł Pawłowski, P Modzel
This paper presents the results of an investigation into the processes controlling development of a cryo-conditioned rock coast system in Hornsund, Svalbard. A suite of nested geomorphological and geophysical methods have been applied to characterise the functioning of rock cliffs and shore platforms influenced by lithological control and geomorphic processes driven by polar coast environments. Electrical resistivity tomography (ERT) surveys have been used to investigate permafrost control on rock coast dynamics and reveal the strong interaction with marine processes in High Arctic coastal settings...
July 26, 2017: Science of the Total Environment
G John Lapeyre, Marco Dentz
Understanding anomalous transport and reaction kinetics due to microscopic physical and chemical disorder is a long-standing goal in many fields including geophysics, biology, and engineering. We consider reaction-diffusion characterized by fluctuations in both transport times and decay rates. We introduce and analyze a model framework that explicitly connects microscopic fluctuations with the mescoscopic description. For broad distributions of transport and reaction time scales we compute the particle density and derive the equations governing its evolution, finding power-law decay of the survival probability, and spatially varying decay that leads to subdiffusion and an asymptotically stationary surviving-particle density...
July 26, 2017: Physical Chemistry Chemical Physics: PCCP
Eric C O'Quinn, Jacob Shamblin, Brandon Perlov, Rodney C Ewing, Joerg Neuefeind, Mikhail Feygenson, Igor Gussev, Maik Lang
A wide variety of compositions adopt the isometric spinel structure (AB2O4), in which the atomic-scale ordering is conventionally described according to only three structural degrees of freedom. One, the inversion parameter, is traditionally defined as the degree of cation exchange between the A- and B-sites. This exchange, a measure of intrinsic disorder, is fundamental to understanding the variation in the physical properties of different spinel compositions. Based on neutron total scattering experiments, we have determined that the local structure of Mg1-xNixAl2O4 spinel cannot be understood as simply being due to cation disorder...
July 21, 2017: Journal of the American Chemical Society
Jun Lin, Yang Zhang, Yujing Yang, Yong Sun, Tingting Lin
Compared to other geophysical techniques, the surface nuclear magnetic resonance (SNMR) method could provide unique insights into the hydrologic properties of groundwater in the subsurface. However, the SNMR signal is in the order of nanovolts (10(-9) V), and the complex environmental noise, i.e., the spike and the harmony noise (10(-4) V), can reach up to 10(5) times the signal amplitude. Saturation of the amplifier is therefore a serious problem in current SNMR systems. In this study, we propose an anti-saturation method based on an instantaneous floating-point amplifier...
June 2017: Review of Scientific Instruments
G Chiodini, J Selva, E Del Pezzo, D Marsan, L De Siena, L D'Auria, F Bianco, S Caliro, P De Martino, P Ricciolino, Z Petrillo
The inter-arrival times of the post 2000 seismicity at Campi Flegrei caldera are statistically distributed into different populations. The low inter-arrival times population represents swarm events, while the high inter-arrival times population marks background seismicity. Here, we show that the background seismicity is increasing at the same rate of (1) the ground uplift and (2) the concentration of the fumarolic gas specie more sensitive to temperature. The seismic temporal increase is strongly correlated with the results of recent simulations, modelling injection of magmatic fluids in the Campi Flegrei hydrothermal system...
June 30, 2017: Scientific Reports
Adam W DeMarco, Sukanta Basu
Utilizing synthetically generated random variates and laboratory measurements, we document the inherent limitations of the conventional structure function approach in limited sample size settings. We demonstrate that an alternative approach, based on the principle of maximum likelihood, can provide nearly unbiased structure function estimates with far less uncertainty under such unfavorable conditions. The superiority of this approach over the conventional approach does not diminish even in the case of strongly correlated samples...
May 2017: Physical Review. E
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"