10,478 research outputs found
Two-flux Colliding Plane Waves in String Theory
We construct the two-flux colliding plane wave solutions in higher
dimensional gravity theory with dilaton, and two complementary fluxes. Two
kinds of solutions has been obtained: Bell-Szekeres(BS) type and homogeneous
type. After imposing the junction condition, we find that only Bell-Szekeres
type solution is physically well-defined. Furthermore, we show that the future
curvature singularity is always developed for our solutions.Comment: 16 pages, Latex; typoes corrected; references added, minor
modification
Derivations of Atomic Ionization Effects Induced by Neutrino Magnetic Moments
A recent paper [M.B. Voloshin, Phys. Rev. Lett. 105, 201801 (2010)] pointed
out that our earlier derivations of atomic ionization cross-section due to
neutrino magnetic moments (arXiv:1001.2074v2) involved unjustified assumptions.
We confirm and elaborate on this comment with these notes. We caution that the
results of the sum-rule approach in this paper contradict the expected
behaviour in atomic transitions.Comment: V3 3 pages ; confirm and elaborate on unjustified assumptions in V1 &
V
Testing a new luminosity/redshift indicator for -ray bursts
We have tested a relative spectral lag (RSL) method suggested earlier as a
luminosity/redshift (or distance) estimator, using the generalized method by
Schaefer & Collazzi. We find the derivations from the luminosity/redshift-RSL
(L/R-RSL) relation are comparable with the corresponding observations. Applying
the luminosity-RSL relation to two different GRB samples, we find that there
exist no violators from the generalized test, namely the Nakar & Piran test and
Li test. We also find that about 36 per cent of Schaefer's sample are outliers
for the L/R-RSL relation within 1 confidence level, but no violators at
3 level within the current precision of L/R-RSL relation. An analysis
of several potential outliers for other luminosity relations shows they can
match the L/R-RSL relation well within an acceptable uncertainty. All the
coincident results seem to suggest that this relation could be a potential tool
for cosmological study.Comment: 7 pages, 6 figures and 1 table; Comments are welcom
Quantum theory for mesoscopic electric circuits
A quantum theory for mesoscopic electric circuits in accord with the
discreteness of electric charges is proposed. On the basis of the theory,
Schr\"{o}dinger equation for the quantum LC-design and L-design is solved
exactly. The uncertainty relation for electric charge and current is obtained
and a minimum uncertainty state is solved. By introducing a gauge field, a
formula for persistent current arising from magnetic flux is obtained from a
new point of view.Comment: revtex, no figure
Ranking Spaces for Predicting Human Movement in an Urban Environment
A city can be topologically represented as a connectivity graph, consisting
of nodes representing individual spaces and links if the corresponding spaces
are intersected. It turns out in the space syntax literature that some defined
topological metrics can capture human movement rates in individual spaces. In
other words, the topological metrics are significantly correlated to human
movement rates, and individual spaces can be ranked by the metrics for
predicting human movement. However, this correlation has never been well
justified. In this paper, we study the same issue by applying the weighted
PageRank algorithm to the connectivity graph or space-space topology for
ranking the individual spaces, and find surprisingly that (1) the PageRank
scores are better correlated to human movement rates than the space syntax
metrics, and (2) the underlying space-space topology demonstrates small world
and scale free properties. The findings provide a novel justification as to why
space syntax, or topological analysis in general, can be used to predict human
movement. We further conjecture that this kind of analysis is no more than
predicting a drunkard's walking on a small world and scale free network.
Keywords: Space syntax, topological analysis of networks, small world, scale
free, human movement, and PageRankComment: 11 pages, 5 figures, and 2 tables, English corrections from version 1
to version 2, major changes in the section of introduction from version 2 to
A Uniform Database of Teleseismic Shear-Wave Splitting Measurements for the Western and Central United States: December 2014 Update
We present a new version of a shear-wave splitting (SWS) database for the western and central United States (WCUS) using broadband seismic data recorded up to the end of 2014 to update a previous version that used data recorded prior to the end of 2012, when the USArray Transportable Array stations were still recording in the easternmost region of theWCUS. A total of 7452 pairs of additional measurements recorded by 1202 digital broadband seismic stations are obtained, and all the measurements in the previous database are rechecked. The resulting uniform SWS database contains a total of 23,448 pairs of well-defined SKS, SKKS, and PKS splitting parameters. Relative to the previous version of the database, the additional measurements notably improved the spatial and azimuthal coverages of the measurements, providing an improved dataset for constraining geodynamic models related to lithospheric deformation and asthenospheric flow, as well as for complex anisotropy recognition and characterization
Transition-Event Durations in One Dimensional Activated Processes
Despite their importance in activated processes, transition-event durations
-- which are much shorter than first passage times -- have not received a
complete theoretical treatment. We therefore study the distribution of
durations of transition events over a barrier in a one-dimensional system
undergoing over-damped Langevin dynamics.Comment: 39 pages, 11 figure
Estimating Blood Pressure from Photoplethysmogram Signal and Demographic Features using Machine Learning Techniques
Hypertension is a potentially unsafe health ailment, which can be indicated
directly from the Blood pressure (BP). Hypertension always leads to other
health complications. Continuous monitoring of BP is very important; however,
cuff-based BP measurements are discrete and uncomfortable to the user. To
address this need, a cuff-less, continuous and a non-invasive BP measurement
system is proposed using Photoplethysmogram (PPG) signal and demographic
features using machine learning (ML) algorithms. PPG signals were acquired from
219 subjects, which undergo pre-processing and feature extraction steps. Time,
frequency and time-frequency domain features were extracted from the PPG and
their derivative signals. Feature selection techniques were used to reduce the
computational complexity and to decrease the chance of over-fitting the ML
algorithms. The features were then used to train and evaluate ML algorithms.
The best regression models were selected for Systolic BP (SBP) and Diastolic BP
(DBP) estimation individually. Gaussian Process Regression (GPR) along with
ReliefF feature selection algorithm outperforms other algorithms in estimating
SBP and DBP with a root-mean-square error (RMSE) of 6.74 and 3.59 respectively.
This ML model can be implemented in hardware systems to continuously monitor BP
and avoid any critical health conditions due to sudden changes.Comment: Accepted for publication in Sensor, 14 Figures, 14 Table
Excitation function of nucleon and pion elliptic flow in relativistic heavy-ion collisions
Within a relativistic transport (ART) model for heavy-ion collisions, we show
that the recently observed characteristic change from out-of-plane to in-plane
elliptic flow of protons in mid-central Au+Au collisions as the incident energy
increases is consistent with the calculated results using a stiff nuclear
equation of state (K=380 MeV). We have also studied the elliptic flow of pions
and the transverse momentum dependence of both the nucleon and pion elliptic
flow in order to gain further insight about the collision dynamics.Comment: 8 pages, 2 figure
On the Conductance Sum Rule for the Hierarchical Edge States of the Fractional Quantum Hall Effect
The conductance sum rule for the hierarchical edge channel currents of a
Fractional Quantum Hall Effect state is derived analytically within the
Haldane-Halperin hierarchy scheme. We provide also an intuitive interpretation
for the hierarchical drift velocities of the edge excitations.Comment: 11 pages, no figure, Revtex 3.0, IC/93/329, ASITP-93-5
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