5,407,113 research outputs found
Relative Quantum Time
The need for a time-shift invariant formulation of quantum theory arises from
fundamental symmetry principles as well as heuristic cosmological
considerations. Such a description then leaves open the question of how to
reconcile global invariance with the perception of change, locally. By
introducing relative time observables, we are able to make rigorous the
Page-Wootters conditional probability formalism to show how local Heisenberg
evolution is compatible with global invariance
Time Dependent Relative Risk Aversion
Risk management and the thorough understanding of the relations between financial markets and the standard theory of macroeconomics have always been among the topics most addressed by researchers, both financial mathematicians and economists. This work aims at explaining investorsâ behavior from a macroeconomic aspect (modeled by the investorsâ pricing kernel and their relative risk aversion) using stocks and options data. Daily estimates of investorsâ pricing kernel and relative risk aversion are obtained and used to construct and analyze a three-year long time-series. The first four moments of these time-series as well as their values at the money are the starting point of a principal component analysis. The relation between changes in a major index level and implied volatility at the money and between the principal components of the changes in relative risk aversion is found to be linear. The relation of the same explanatory variables to the principal components of the changes in pricing kernels is found to be log-linear, although this relation is not significant for all of the examined maturities.risk aversion, pricing kernels, time dependent preferences
Crossover Time in Relative Fluctuations Characterizes the Longest Relaxation Time of Entangled Polymers
In entangled polymer systems, there are several characteristic time scales,
such as the entanglement time and the disengagement time. In molecular
simulations, the longest relaxation time (the disengagement time) can be
determined by the mean square displacement (MSD) of a segment or by the shear
relaxation modulus. Here, we propose the relative fluctuation analysis method,
which is originally developed for characterizing large fluctuations, to
determine the longest relaxation time from the center of mass trajectories of
polymer chains (the time-averaged MSDs). Applying the method to simulation data
of entangled polymers (by the slip-spring model and the simple reptation
model), we provide a clear evidence that the longest relaxation time is
estimated as the crossover time in the relative fluctuations.Comment: 17 pages, 9 figures, to appear in J. Chem. Phy
RELATIVE AGRICULTURAL PRICE CHANGES IN DIFFERENT TIME HORIZONS
Using a monthly data covering from 1974:1 to 2002:12, this paper explores the linkage between changes in macroeconomic variables (real exchange rate and inflation rate) and changes in relative agricultural prices in different time horizons (1, 12, 24, 36, 48, and 60 months). Controlling for factors likely to determine the long run trend of relative agricultural prices, the results show that long-term changes in real exchange rate has had a significant negative correlation with the long-term changes in relative agricultural prices. Conversely, changes of the general price have a role in explaining short-term changes in relative agricultural price at best.Demand and Price Analysis,
Relative entropy and waiting times for continuous-time Markov processes
For discrete-time stochastic processes, there is a close connection between
return/waiting times and entropy. Such a connection cannot be straightforwardly
extended to the continuous-time setting. Contrarily to the discrete-time case
one does need a reference measure and so the natural object is relative entropy
rather than entropy. In this paper we elaborate on this in the case of
continuous-time Markov processes with finite state space. A reference measure
of special interest is the one associated to the time-reversed process. In that
case relative entropy is interpreted as the entropy production rate. The main
results of this paper are: almost-sure convergence to relative entropy of
suitable waiting-times and their fluctuation properties (central limit theorem
and large deviation principle).Comment: 17 page
All-sky Relative Opacity Mapping Using Night Time Panoramic Images
An all-sky cloud monitoring system that generates relative opacity maps over
many of the world's premier astronomical observatories is described.
Photometric measurements of numerous background stars are combined with
simultaneous sky brightness measurements to differentiate thin clouds from sky
glow sources such as air glow and zodiacal light. The system takes a continuous
pipeline of all-sky images, and compares them to canonical images taken on
other nights at the same sidereal time. Data interpolation then yields
transmission maps covering almost the entire sky. An implementation of this
system is currently operating through the Night Sky Live network of CONCAM3s
located at Cerro Pachon (Chile), Mauna Kea (Hawaii), Haleakala (Hawaii), SALT
(South Africa) and the Canary Islands (Northwestern Africa).Comment: Accepted for publication in PAS
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