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https://www.readbyqxmd.com/read/27924928/unified-rheology-of-vibro-fluidized-dry-granular-media-from-slow-dense-flows-to-fast-gas-like-regimes
#1
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
#2
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
https://www.readbyqxmd.com/read/27917410/time-lapse-in-situ-imaging-of-ice-crystal-growth-using-confocal-microscopy
#3
Moreno Marcellini, Cecile Noirjean, Dmytro Dedovets, Juliette Maria, Sylvain Deville
Ice crystals nucleate and grow when a water solution is cooled below its freezing point. The growth velocities and morphologies of the ice crystals depend on many parameters, such as the temperature of ice growth, the melting temperature, and the interactions of solutes with the growing crystals. Three types of morphologies may appear: dendritic, cellular (or fingerlike), or the faceted equilibrium form. Understanding and controlling which type of morphology is formed is essential in several domains, from biology to geophysics and materials science...
November 30, 2016: ACS Omega
https://www.readbyqxmd.com/read/27908033/an-axisymmetric-time-domain-spectral-element-method-for-full-wave-simulations-application-to-ocean-acoustics
#4
Alexis Bottero, Paul Cristini, Dimitri Komatitsch, Mark Asch
The numerical simulation of acoustic waves in complex three-dimensional (3D) media is a key topic in many branches of science, from exploration geophysics to non-destructive testing and medical imaging. With the drastic increase in computing capabilities this field has dramatically grown in the last 20 years. However many 3D computations, especially at high frequency and/or long range, are still far beyond current reach and force researchers to resort to approximations, for example, by working in two dimensions (plane strain) or by using a paraxial approximation...
November 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27908018/dynamics-and-transport-properties-of-three-surface-quasigeostrophic-point-vortices
#5
C K Taylor, Stefan G Llewellyn Smith
The surface quasi-geostrophic (SQG) equations are a model for low-Rossby number geophysical flows in which the dynamics are governed by potential temperature dynamics on the boundary. We examine point vortex solutions to this model as well as the chaotic flows induced by three point vortices. The chaotic transport induced by these flows is investigated using techniques of Poincaré maps and the Finite Time Braiding Exponent (FTBE). This chaotic transport is representative of the mixing in the flow, and these terms are used interchangeably in this work...
November 2016: Chaos
https://www.readbyqxmd.com/read/27905411/the-rapid-formation-of-sputnik-planitia-early-in-pluto-s-history
#6
Douglas P Hamilton, S A Stern, J M Moore, L A Young
Pluto's Sputnik Planitia is a bright, roughly circular feature that resembles a polar ice cap. It is approximately 1,000 kilometres across and is centred on a latitude of 25 degrees north and a longitude of 175 degrees, almost directly opposite the side of Pluto that always faces Charon as a result of tidal locking. One explanation for its location includes the formation of a basin in a giant impact, with subsequent upwelling of a dense interior ocean. Once the basin was established, ice would naturally have accumulated there...
November 30, 2016: Nature
https://www.readbyqxmd.com/read/27897168/stepwise-onset-of-the-icehouse-world-and-its-impact-on-oligo-miocene-central-asian-mammals
#7
Mathias Harzhauser, Gudrun Daxner-Höck, Paloma López-Guerrero, Olivier Maridet, Adriana Oliver, Werner E Piller, Sylvain Richoz, Margarita A Erbajeva, Thomas A Neubauer, Ursula B Göhlich
Central Asia is a key area to study the impact of Cenozoic climate cooling on continental ecosystems. One of the best places to search for rather continuous paleontological records is the Valley of Lakes in Mongolia with its outstandingly fossil-rich Oligocene and Miocene terrestrial sediments. Here, we investigate the response by mammal communities during the early stage of Earth's icehouse climate in Central Asia. Based on statistical analyses of occurrence and abundance data of 18608 specimens representing 175 mammal species and geochemical (carbon isotopes) and geophysical (magnetic susceptibility) data we link shifts in diversities with major climatic variations...
November 29, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27889953/ecology-under-lake-ice
#8
REVIEW
Stephanie E Hampton, Aaron W E Galloway, Stephen M Powers, Ted Ozersky, Kara H Woo, Ryan D Batt, Stephanie G Labou, Catherine M O'Reilly, Sapna Sharma, Noah R Lottig, Emily H Stanley, Rebecca L North, Jason D Stockwell, Rita Adrian, Gesa A Weyhenmeyer, Lauri Arvola, Helen M Baulch, Isabella Bertani, Larry L Bowman, Cayelan C Carey, Jordi Catalan, William Colom-Montero, Leah M Domine, Marisol Felip, Ignacio Granados, Corinna Gries, Hans-Peter Grossart, Juta Haberman, Marina Haldna, Brian Hayden, Scott N Higgins, Jeff C Jolley, Kimmo K Kahilainen, Enn Kaup, Michael J Kehoe, Sally MacIntyre, Anson W Mackay, Heather L Mariash, Robert M McKay, Brigitte Nixdorf, Peeter Nõges, Tiina Nõges, Michelle Palmer, Don C Pierson, David M Post, Matthew J Pruett, Milla Rautio, Jordan S Read, Sarah L Roberts, Jacqueline Rücker, Steven Sadro, Eugene A Silow, Derek E Smith, Robert W Sterner, George E A Swann, Maxim A Timofeyev, Manuel Toro, Michael R Twiss, Richard J Vogt, Susan B Watson, Erika J Whiteford, Marguerite A Xenopoulos
Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors...
November 27, 2016: Ecology Letters
https://www.readbyqxmd.com/read/27886081/improved-goldstein-interferogram-filter-based-on-local-fringe-frequency-estimation
#9
Qingqing Feng, Huaping Xu, Zhefeng Wu, Yanan You, Wei Liu, Shiqi Ge
The quality of an interferogram, which is limited by various phase noise, will greatly affect the further processes of InSAR, such as phase unwrapping. Interferometric SAR (InSAR) geophysical measurements', such as height or displacement, phase filtering is therefore an essential step. In this work, an improved Goldstein interferogram filter is proposed to suppress the phase noise while preserving the fringe edges. First, the proposed adaptive filter step, performed before frequency estimation, is employed to improve the estimation accuracy...
November 23, 2016: Sensors
https://www.readbyqxmd.com/read/27885004/circadian-time-signatures-of-fitness-and-disease
#10
REVIEW
Joseph Bass, Mitchell A Lazar
Biological clocks are autonomous anticipatory oscillators that play a critical role in the organization and information processing from genome to whole organisms. Transformative advances into the clock system have opened insight into fundamental mechanisms through which clocks program energy transfer from sunlight into organic matter and potential energy, in addition to cell development and genotoxic stress response. The identification of clocks in nearly every single cell of the body raises questions as to how this gives rise to rhythmic physiology in multicellular organisms and how environmental signals entrain clocks to geophysical time...
November 25, 2016: Science
https://www.readbyqxmd.com/read/27881710/the-role-of-hedonic-behavior-in-reducing-perceived-risk-evidence-from-postearthquake-mobile-app-data
#11
Jayson S Jia, Jianmin Jia, Christopher K Hsee, Baba Shiv
Understanding how human populations naturally respond to and cope with risk is important for fields ranging from psychology to public health. We used geophysical and individual-level mobile-phone data (mobile-apps, telecommunications, and Web usage) of 157,358 victims of the 2013 Ya'an earthquake to diagnose the effects of the disaster and investigate how experiencing real risk (at different levels of intensity) changes behavior. Rather than limiting human activity, higher earthquake intensity resulted in graded increases in usage of communications apps (e...
November 23, 2016: Psychological Science
https://www.readbyqxmd.com/read/27872307/high-pressure-phase-of-brucite-stable-at-earth-s-mantle-transition-zone-and-lower-mantle-conditions
#12
Andreas Hermann, Mainak Mookherjee
We investigate the high-pressure phase diagram of the hydrous mineral brucite, Mg(OH)2, using structure search algorithms and ab initio simulations. We predict a high-pressure phase stable at pressure and temperature conditions found in cold subducting slabs in Earth's mantle transition zone and lower mantle. This prediction implies that brucite can play a much more important role in water transport and storage in Earth's interior than hitherto thought. The predicted high-pressure phase, stable in calculations between 20 and 35 GPa and up to 800 K, features MgO6 octahedral units arranged in the anatase-TiO2 structure...
November 21, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27870585/another-earth-2-0-not-so-fast
#13
Dirk Schulze-Makuch, Edward Guinan
The number of confirmed exoplanets now exceeds 3000, with an additional nearly 5000 exoplanet candidates awaiting confirmation in the NASA Exoplanet Archive ( 2016 ). Nearly weekly we hear about the detection of a new exoplanet similar in mass to Earth and located in the so-called habitable zone around its host star. The excitement is understandable given our desire to find a second Earth. However, the excitement should not lead to an over-interpretation of the findings, because the claim can only be to have some crude similarity to Earth based on a few selected geophysical parameters...
November 2016: Astrobiology
https://www.readbyqxmd.com/read/27867797/source-of-the-dayside-cusp-aurora
#14
S B Mende, H U Frey, V Angelopoulos
Monochromatic all-sky imagers at South Pole and other Antarctic stations of the Automatic Geophysical Observatory chain recorded the aurora in the region where the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites crossed the dayside magnetopause. In several cases the magnetic field lines threading the satellites when mapped to the atmosphere were inside the imagers' field of view. From the THEMIS magnetic field and the plasma density measurements, we were able to locate the position of the magnetopause crossings and map it to the ionosphere using the Tsyganenko-96 field model...
August 2016: Journal of Geophysical Research. Space Physics
https://www.readbyqxmd.com/read/27851735/reorientation-of-sputnik-planitia-implies-a-subsurface-ocean-on-pluto
#15
F Nimmo, D P Hamilton, W B McKinnon, P M Schenk, R P Binzel, C J Bierson, R A Beyer, J M Moore, S A Stern, H A Weaver, C B Olkin, L A Young, K E Smith
The deep nitrogen-covered basin on Pluto, informally named Sputnik Planitia, is located very close to the longitude of Pluto's tidal axis and may be an impact feature, by analogy with other large basins in the Solar System. Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basin's present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography. Here we argue that if Sputnik Planitia did indeed form as a result of an impact and if Pluto possesses a subsurface ocean, the required positive gravity anomaly would naturally result because of shell thinning and ocean uplift, followed by later modest nitrogen deposition...
December 1, 2016: Nature
https://www.readbyqxmd.com/read/27834995/vertically-bounded-double-diffusive-convection-in-the-finger-regime-comparing-no-slip-versus-free-slip-boundary-conditions
#16
Yantao Yang, Roberto Verzicco, Detlef Lohse
Vertically bounded fingering double diffusive convection is numerically investigated, focusing on the influences of different velocity boundary conditions, i.e., the no-slip condition, which is inevitable in the lab-scale experimental researches, and the free-slip condition, which is an approximation for the interfaces in many natural environments, such as the oceans. For both boundary conditions the flow is dominated by fingers and the global responses follow the same scaling laws, with enhanced prefactors for the free-slip cases...
October 28, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27831865/the-spurs-algorithm-for-resampling-an-irregularly-sampled-signal-onto-a-cartesian-grid
#17
Amir Kiperwas, Daniel Rosenfeld, Yonina C Eldar
We present an algorithm for resampling a function from its values on a non-Cartesian grid onto a Cartesian grid. This problem arises in many applications such as MRI, CT, radio astronomy and geophysics. Our algorithm, termed SParse Uniform ReSampling (SPURS), employs methods from modern sampling theory to achieve a small approximation error while maintaining low computational cost. The given non-Cartesian samples are projected onto a selected intermediate subspace, spanned by integer translations of a compactly supported kernel function...
November 1, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/27830783/geophysics-volcano-sneaks-in-magma-sideways
#18
(no author information available yet)
No abstract text is available yet for this article.
November 9, 2016: Nature
https://www.readbyqxmd.com/read/27820946/magnetic-reversals-from-planetary-dynamo-waves
#19
Andrey Sheyko, Christopher C Finlay, Andrew Jackson
A striking feature of many natural dynamos is their ability to undergo polarity reversals. The best documented example is Earth's magnetic field, which has reversed hundreds of times during its history. The origin of geomagnetic polarity reversals lies in a magnetohydrodynamic process that takes place in Earth's core, but the precise mechanism is debated. The majority of numerical geodynamo simulations that exhibit reversals operate in a regime in which the viscosity of the fluid remains important, and in which the dynamo mechanism primarily involves stretching and twisting of field lines by columnar convection...
November 7, 2016: Nature
https://www.readbyqxmd.com/read/27802675/performance-of-lagrangian-descriptors-and-their-variants-in-incompressible-flows
#20
Alfonso Ruiz-Herrera
The method of Lagrangian Descriptors has been applied in many different contexts, specially in geophysical flows. In this paper, we analyze their performance in incompressible flows. We construct broad families of systems where this diagnostic fails in the detection of barriers to transport. Another aim of this manuscript is to illustrate the same deficiencies in the recent diagnostic proposed by Craven and Hernández.
October 2016: Chaos
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