2,909 research outputs found
Situations in traffic - how quickly they change
Spatio-temporal correlations of intensity of traffic are analysed for one
week data collected in the motorway M-30 around Madrid in January 2009. We
found that the lifetime of these correlations is the shortest in the evening,
between 6 and 8 p.m. This lifetime is a new indicator how much attention of
drivers is demanded in given traffic conditions.Comment: 9 pages, 6 figure
Localization Properties of Quantized Magnetostatic Modes in Nanocubes
We investigate the dynamical properties of a system of interacting magnetic
dipoles disposed in sites of an sc lattice and forming a cubic-shaped sample of
size determined by the cube edge length (N-1)a (a being the lattice constant, N
representing the number of dipolar planes). The dipolar field resulting from
the dipole-dipole interactions is calculated numerically in points of the axis
connecting opposite cube face centers (central axis) by collecting individual
contributions to this field coming from each of the N atomic planes
perpendicular to the central axis. The applied magnetic field is assumed to be
oriented along the central axis, magnetizing uniformly the whole sample, all
the dipoles being aligned parallelly in the direction of the applied field. The
frequency spectrum of magnetostatic waves propagating in the direction of the
applied field is found numerically by solving the Landau-Lifshitz equation of
motion including the local (nonhomogeneous) dipolar field component; the mode
amplitude spatial distributions (mode profiles) are depicted as well. It is
found that only the two energetically highest modes have bulk-extended
character. All the remaining modes are of localized nature; more precisely, the
modes forming the lower part of the spectrum are localized in the subsurface
region, while the upper-spectrum modes are localized around the sample center.
We show that the mode localization regions narrow down as the cube size, N,
increases (we investigated the range of N=21 to N=101), and in sufficiently
large cubes one obtains practically only center-localized and surface-localized
magnetostatic modes.Comment: 20 pages, 9 figures in postscript, useing Revtex4.cl
Finite-difference modelling to evaluate seismic P-wave and shear-wave field data
High-resolution reflection seismic methods are an established non-destructive
tool for engineering tasks. In the near surface, shear-wave reflection
seismic measurements usually offer a higher spatial resolution in the same
effective signal frequency spectrum than P-wave data, but data quality varies
more strongly.
To discuss the causes of these differences, we investigated a P-wave and a SH-wave
seismic reflection profile measured at the same location on the island of
Föhr, Germany and applied seismic reflection processing to the field data as well
as finite-difference modelling of the seismic wave field. The simulations
calculated were adapted to the acquisition field geometry, comprising 2 m
receiver distance (1 m for SH wave) and 4 m shot distance along the 1.5 km
long P-wave and 800 m long SH-wave profiles. A Ricker wavelet and the use of
absorbing frames were first-order model parameters. The petrophysical
parameters to populate the structural models down to 400 m depth were taken
from borehole data, VSP (vertical
seismic profile) measurements and cross-plot relations.
The simulation of the P-wave wave-field was based on interpretation of the
P-wave depth section that included a priori information from boreholes and
airborne electromagnetics. Velocities for 14 layers in the model were derived
from the analysis of five nearby VSPs (vP
=1600â2300 m s-1). Synthetic shot data were compared with the
field data and seismic sections were created. Major features like direct wave
and reflections are imaged. We reproduce the mayor reflectors in the depth
section of the field data, e.g. a prominent till layer and several deep
reflectors. The SH-wave model was adapted accordingly but only led to minor
correlation with the field data and produced a higher signal-to-noise ratio.
Therefore, we suggest to consider for future simulations additional features
like intrinsic damping, thin layering, or a near-surface weathering layer.
These may lead to a better understanding of key parameters determining the
data quality of near-surface shear-wave seismic measurements
Optimal ratio between phase basis and bit basis in QKD
In the original BB84 protocol, the bit basis and the phase basis are used
with equal probability. Lo et al (J. of Cryptology, 18, 133-165 (2005))
proposed to modify the ratio between the two bases by increasing the final key
generation rate. However, the optimum ratio has not been derived. In this
letter, in order to examine this problem, the ratio between the two bases is
optimized for exponential constraints given Eve's information
distinguishability and the final error probability
Influence of nonmagnetic dielectric spacers on the spin wave response of one-dimensional planar magnonic crystals
The one-dimensional planar magnonic crystals are usually fabricated as a
sequence of stripes intentionally or accidentally separated by non-magnetic
spacers. The influence of spacers on shaping the spin wave spectra is complex
and still not completely clarified. We performed the detailed numerical studies
of the one-dimensional single- and bi-component magnonic crystals comprised of
a periodic array of thin ferromagnetic stripes separated by non-magnetic
spacers. We showed that the dynamic dipolar interactions between the stripes
mediated by non-magnetic spacer, even ultra-narrow, significantly shift up the
frequency of the ferromagnetic resonance and simultaneously reduce the spin
wave group velocity, which is manifested by the flattening of the magnonic
band. We attributed these changes in the spectra to the modifications of
dipolar pinning and shape anisotropy both dependent on the width of the spacers
and the thickness of the stripes, as well as to the dynamical magnetic volume
charges formed due to inhomogeneous spin wave amplitude
Shear wave reflection seismic yields subsurface dissolution and subrosion patterns: application to the Ghor Al-Haditha sinkhole site, Dead Sea, Jordan
Near-surface geophysical imaging of alluvial fan settings is a challenging task but crucial for understating geological processes in such settings. The alluvial fan of Ghor Al-Haditha at the southeast shore of the Dead Sea is strongly affected by localized subsidence and destructive sinkhole collapses, with a significantly increasing sinkhole formation rate since ca. 1983. A similar increase is observed also on the western shore of the Dead Sea, in correlation with an ongoing decline in the Dead Sea level. Since different structural models of the upper 50âm of the alluvial fan and varying hypothetical sinkhole processes have been suggested for the Ghor Al-Haditha area in the past, this study aimed to clarify the subsurface characteristics responsible for sinkhole development.
For this purpose, high-frequency shear wave reflection vibratory seismic surveys were carried out in the Ghor Al-Haditha area along several crossing and parallel profiles with a total length of 1.8 and 2.1âkm in 2013 and 2014, respectively. The sedimentary architecture of the alluvial fan at Ghor Al-Haditha is resolved down to a depth of nearly 200âm at a high resolution and is calibrated with the stratigraphic profiles of two boreholes located inside the survey area.
The most surprising result of the survey is the absence of evidence of a thick (>â2â10âm) compacted salt layer formerly suggested to lie at ca. 35â40âm depth. Instead, seismic reflection amplitudes and velocities image with good continuity a complex interlocking of alluvial fan deposits and lacustrine sediments of the Dead Sea between 0 and 200âm depth. Furthermore, the underground section of areas affected by sinkholes is characterized by highly scattering wave fields and reduced seismic interval velocities. We propose that the Dead Sea mud layers, which comprise distributed inclusions or lenses of evaporitic chloride, sulfate, and carbonate minerals as well as clay silicates, become increasingly exposed to unsaturated water as the sea level declines and are consequently destabilized and mobilized by both dissolution and physical erosion in the subsurface. This new interpretation of the underlying cause of sinkhole development is supported by surface observations in nearby channel systems. Overall, this study shows that shear wave seismic reflection technique is a promising method for enhanced near-surface imaging in such challenging alluvial fan settings
Nearâsurface fault detection using highâresolution shear wave reflection seismics at the CO2CRC Otway Project site, Australia
Highâresolution, nearâsurface, shear wave reflection seismic measurements were carried out in November 2013 at the CO2CRC Otway Project site, Victoria, Australia, with the aim to determine whether and, if so, where deeper faults reach the near subsurface. From a previous P wave 3âD reflection seismic data set that was concentrated on a reservoir at 2 km depth, we can only interpret faults up to 400 m below sea level. For the future monitoring in the overburden of the CO2 reservoir it is important to know whether and how the faults continue in the subsurface. We prove that two regional fault zones do in fact reach the surface instead of dying out at depth. Individual firstâbreak signatures in the shot gathers along the profiles support this interpretation. However, this finding does not imply perforce communication between the reservoir and the surface in the framework of CO2 injection. The shear wave seismic sections are complementary to existing P wave volumes. They image with high resolution (better than 3 m vertically) different tectonic structures. Similar structures also outcrop on the southern coast of the Otway Basin. Both the seismic and the outcrops evidence the complex youngest structural history of the area.BMBF, 03G0797A, Verbundprojekt UR VI: PROTECT; Vorhersage von Deformation fĂŒr eine abgesicherte Speicherung von Kohlenstoff (PRediction Of deformation To Ensure Carbon Traps); Vorhaben: Subseismische Deformationsvorhersage potentieller Wegsamkeiten und ihre seismische Validierung - Sonderprogramm GEOTECHNOLOGIE
Faultâcontrolled lithospheric detachment of the volcanic southern South Atlantic rift
© 2016. American Geophysical Union.We present structural models of two exemplary conjugate seismic lines of the southernmost South Atlantic margins to examine their initial evolution, especially the seawardâdipping reflectors (SDRs). Modeling illustrates the different structure and inclination angles of the SDRs, which therefore require different subsidence histories. Since typical symmetrical subsidence models are not applicable, we suggest a model with a westwardâdipping detachment fault that offsets the SDRs on the South American margin and we speculate on passively subsided SDRs on the South African margin. We propose a simpleâshear rifting mechanism to explain the initial breakâup of the South Atlantic.DFG, 61089689, SPP 1375: SAMPLE: South Atlantic Margin Processes and Links with onshore Evolutio
CP violation through particle mixing and the H-A lineshape
We consider the possibility of looking for CP-mixing effects in two-Higgs
doublet models (and particularly in the MSSM) by studying the lineshape of the
CP-even (H) and CP-odd (A) neutral scalars. In most cases H and A come quite
degenerate in mass, and their s-channel production would lead to nearly
overlapping resonances. CP-violating effects may connect these two Higgs
bosons, giving origin to one-loop particle mixing, which, due to their mass
proximity, can be resonantly enhanced. The corresponding transition amplitude
contains then CP-even and CP-odd components; besides the signal of
intereference between both amplitudes, leading to a CP-odd asymmetry, we
propose to look for the mixing probability itself, a quantity which, although
CP-even, can originate only from a CP-odd amplitude. We show that, in general,
the effect of such a mixing probability cannot be mimicked by (or be
re-absorbed into) a simple redefinition of the H and A masses in the context of
a CP-conserving model. Specifically, the effects of the CP-mixing are such
that, either the mass-splitting of the H and A bosons cannot be accounted for
in the absence of CP-mixing, and/or the detailed energy dependence of the
produced lineshape is clearly different from the one obtained by redefining the
masses, but not allowing any mixing. This analysis suggests that the detailed
study of the lineshape of this Higgs system may provide valuable information on
the CP nature of the underlying theory.Comment: 16 pages, 13 figures; v2: added one reference; v3: radiative
corrections taken into account, agreement now with CP-SuperH, conclusions
unchanged. v3 matches the paper version accepted for publication in JHE
Culture in embryonic kidney serum and xeno-free media as renal cell carcinoma and renal cell carcinoma cancer stem cells research model
The use of fetal bovine serum hinders obtaining reproducible experimental results and should also be removed in hormone and growth factor studies. In particular hormones found in FBS act globally on cancer cell physiology and influence transcriptome and metabolome. The aim of our study was to develop a renal carcinoma serum free culture model optimized for (embryonal) renal cells in order to select the best study model for downstream auto-, para- or endocrine research. Secondary aim was to verify renal carcinoma stem cell culture for this application. In the study, we have cultured renal cell carcinoma primary tumour cell line (786-0) as well as human kidney cancer stem cells in standard 2D monolayer cultures in Roswell Park Memorial Institute Medium or Dulbeccoâs Modified Eagleâs Medium and Complete Human Kidney Cancer Stem Cell Medium, respectively. Serum-free, animal-component free Human Embryonic Kidney 293 media were tested. Our results revealed that xeno-free embryonal renal cells optimized culture media provide a useful tool in RCC cancer biology research and at the same time enable effective growth of RCC. We propose bio-mimic RCC cell culture model with specific serum-free and xeno-free medium that promote RCC cell viability
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