61,112 research outputs found
Dynamic scaling approach to study time series fluctuations
We propose a new approach for properly analyzing stochastic time series by
mapping the dynamics of time series fluctuations onto a suitable nonequilibrium
surface-growth problem. In this framework, the fluctuation sampling time
interval plays the role of time variable, whereas the physical time is treated
as the analog of spatial variable. In this way we found that the fluctuations
of many real-world time series satisfy the analog of the Family-Viscek dynamic
scaling ansatz. This finding permits to use the powerful tools of kinetic
roughening theory to classify, model, and forecast the fluctuations of
real-world time series.Comment: 25 pages, 7 figures, 1 tabl
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Speckle-visibility spectroscopy: A tool to study time-varying dynamics
We describe a multispeckle dynamic light scattering technique capable of
resolving the motion of scattering sites in cases that this motion changes
systematically with time. The method is based on the visibility of the speckle
pattern formed by the scattered light as detected by a single exposure of a
digital camera. Whereas previous multispeckle methods rely on correlations
between images, here the connection with scattering site dynamics is made more
simply in terms of the variance of intensity among the pixels of the camera for
the specified exposure duration. The essence is that the speckle pattern is
more visible, i.e. the variance of detected intensity levels is greater, when
the dynamics of the scattering site motion is slow compared to the exposure
time of the camera. The theory for analyzing the moments of the spatial
intensity distribution in terms of the electric field autocorrelation is
presented. It is demonstrated for two well-understood samples, a colloidal
suspension of Brownian particles and a coarsening foam, where the dynamics can
be treated as stationary. However, the method is particularly appropriate for
samples in which the dynamics vary with time, either slowly or rapidly, limited
only by the exposure time fidelity of the camera. Potential applications range
from soft-glassy materials, to granular avalanches, to flowmetry of living
tissue.Comment: review - theory and experimen
Limit theorem for a time-dependent coined quantum walk on the line
We study time-dependent discrete-time quantum walks on the one-dimensional
lattice. We compute the limit distribution of a two-period quantum walk defined
by two orthogonal matrices. For the symmetric case, the distribution is
determined by one of two matrices. Moreover, limit theorems for two special
cases are presented
Dynamics of Anderson localization in open 3D media
We develop a self-consistent theoretical approach to the dynamics of Anderson
localization in open three-dimensional (3D) disordered media. The approach
allows us to study time-dependent transmission and reflection, and the
distribution of decay rates of quasi-modes of 3D disordered slabs near the
Anderson mobility edge.Comment: 4 pages, 4 figure
Impatience, Anticipatory Feelings and Uncertainty: A Dynamic Experiment on Time Preferences
We study time preferences in a real-effort experiment with a one-month horizon. We report that two thirds of choices suggest negative time preferences. Moreover, choice reversal over time is common even if temptation plays no role. We propose and measure three distinct concepts of choice reversal over time to study time consistency. This evidence calls for an important role for anticipatory feelings and uncertainty in intertemporal behavior.negative time preferences, choice reversal, risk, time inconsistency, real-effort experiment
Merging for inhomogeneous finite Markov chains, part II: Nash and log-Sobolev inequalities
We study time-inhomogeneous Markov chains with finite state spaces using Nash
and logarithmic-Sobolev inequalities, and the notion of -stability. We
develop the basic theory of such functional inequalities in the
time-inhomogeneous context and provide illustrating examples.Comment: Published in at http://dx.doi.org/10.1214/10-AOP572 the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
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