22,598 research outputs found
Mantle flow and lithosphere-asthenosphere coupling beneath the southwestern edge of the North American craton: constraints from shear-wave splitting measurements
High-quality broadband seismic data recorded by the USArray and other stations in the southwestern United States provide a unique opportunity to test different models of anisotropy-forming mechanisms in the vicinity of a cratonic edge. Systematic spatial variations of anisotropic characteristics are revealed by 3027 pairs of splitting parameters measured at 547 broadband seismic stations. The western and southern edges of the North American craton show edge-parallel fast directions with larger-than-normal splitting times, and the continental interior is characterized by smaller splitting times spatially consistent fast directions that are mostly parallel to the absolute plate motion direction of North America. Except for a small area in the vicinity of the Llano Uplift in central Texas, no systematic azimuthal variations of the splitting parameters are observed, suggesting that a single layer of anisotropy with horizontal axis of symmetry can adequately explain the observations. Estimation of the depth of the source of the observed anisotropy using spatial coherency of the splitting parameters indicates that the observed anisotropy mostly originate from the upper asthenosphere, through simple shear between the partially coupled lithosphere and asthenosphere --Abstract, page iv
Comparison of different measures for quantum discord under non-Markovian noise
Two geometric measures for quantum discord were recently proposed by Modi et
al. [Phys. Rev. Lett. 104, 080501 (2010)] and Dakic et al. [Phys. Rev. Lett.
105, 190502 (2010)]. We study the similarities and differences for total
quantum correlations of Bell-diagonal states using these two geometry-based
quantum discord and the original quantum discord. We show that, under
non-Markovian dephasing channels, quantum discord and one of the geometric
measures stay constant for a finite amount of time, but not the other geometric
measure. However, all the three measures share a common sudden change point.
Our study on critical point of sudden transition might be useful for keeping
long time total quantum correlations under decoherence.Comment: 10 pages, 3 figures submitted for publicatio
A Corpus-Based, Pilot Study of Lexical Stress Variation in American English
Phonological free variation describes the phenomenon of there being more than one pronunciation for a word without any change in meaning (e.g. because, schedule, vehicle). The term also applies to words that exhibit different stress patterns (e.g. academic, resources, comparable) with no change in meaning or grammatical category. A corpus-based analysis of free variation is a useful tool for testing the validity of surveys of speakers' pronunciation preferences for certain variants. The current paper presents the results of a corpus-based pilot study of American English, in an attempt to replicate Mompéan's 2009 study of British English
Hard-Sphere Fluids in Contact with Curved Substrates
The properties of a hard-sphere fluid in contact with hard spherical and
cylindrical walls are studied. Rosenfeld's density functional theory (DFT) is
applied to determine the density profile and surface tension for wide
ranges of radii of the curved walls and densities of the hard-sphere fluid.
Particular attention is paid to investigate the curvature dependence and the
possible existence of a contribution to that is proportional to the
logarithm of the radius of curvature. Moreover, by treating the curved wall as
a second component at infinite dilution we provide an analytical expression for
the surface tension of a hard-sphere fluid close to arbitrary hard convex
walls. The agreement between the analytical expression and DFT is good. Our
results show no signs for the existence of a logarithmic term in the curvature
dependence of .Comment: 15 pages, 6 figure
Flow Induced Organization and Memory of a Vortex Lattice
We report on experiments probing the evolution of a vortex state in response
to a driving current in 2H-NbSe crystals. By following the vortex motion
with fast transport measurements we find that the current enables the system to
reorganize and access new configurations. During this process the system
exhibits a long-term memory: if the current is turned off the vortices freeze
in place remembering their prior motion. When the current is restored the
motion resumes where it stopped. The experiments provide evidence for a
dynamically driven structural change of the vortex lattice and a corresponding
dynamic phase diagram that contains a previously unknown regime where the
critical current can be either or by applying an
appropriate driving current.Comment: 5 pages, 4figure
Discovery of Griffiths phase in itinerant magnetic semiconductor Fe_{1-x}Co_xS_2
Critical points that can be suppressed to zero temperature are interesting
because quantum fluctuations have been shown to dramatically alter electron gas
properties. Here, the metal formed by Co doping the paramagnetic insulator
FeS, FeCoS, is demonstrated to order ferromagnetically at
where we observe unusual transport, magnetic, and
thermodynamic properties. We show that this magnetic semiconductor undergoes a
percolative magnetic transition with distinct similarities to the Griffiths
phase, including singular behavior at and zero temperature.Comment: 10 pages, 4 figure
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