44,835 research outputs found
Lagrangian acceleration statistics in turbulent flows
We show that the probability densities af accelerations of Lagrangian test
particles in turbulent flows as measured by Bodenschatz et al. [Nature 409,
1017 (2001)] are in excellent agreement with the predictions of a stochastic
model introduced in [C. Beck, PRL 87, 180601 (2001)] if the fluctuating
friction parameter is assumed to be log-normally distributed. In a generalized
statistical mechanics setting, this corresponds to a superstatistics of
log-normal type. We analytically evaluate all hyperflatnes factors for this
model and obtain a flatness prediction in good agreement with the experimental
data. There is also good agreement with DNS data of Gotoh et al. We relate the
model to a generalized Sawford model with fluctuating parameters, and discuss a
possible universality of the small-scale statistics.Comment: 10 pages, 2 figure
Study reveals effect of aluminum on saturation moment of Fe-Ni alloys
Study of saturation magnetization, important in the investigation of the electronic structure of alloys, reveals the effect of aluminum on the saturation moments of iron-nickel alloys. The saturation magnetizations were extrapolated to the absolute zero of temperature for calculating average atomic moments
Characterization of a microwave frequency resonator via a nearby quantum dot
We present measurements of a hybrid system consisting of a microwave
transmission-line resonator and a lateral quantum dot defined on a GaAs
heterostructure. The two subsystems are separately characterized and their
interaction is studied by monitoring the electrical conductance through the
quantum dot. The presence of a strong microwave field in the resonator is found
to reduce the resonant conductance through the quantum dot, and is attributed
to electron heating and modulation of the dot potential. We use this
interaction to demonstrate a measurement of the resonator transmission spectrum
using the quantum dot.Comment: 3 pages, 3 figure
Red-giant stars in eccentric binaries
The unparalleled photometric data obtained by NASA’s Kepler Space Telescope has led to improved understanding of red-giant stars and binary stars. We discuss the characterization of known eccentric system, containing a solar-like oscillating red-giant primary component. We also report several new binary systems that are candidates for hosting an oscillating companion. A powerful approach to study binary stars is to combine asteroseimic techniques with light curve fitting. Seismology allows us to deduce the properties of red giants. In addition, by modeling the ellipsoidal modulations we can constrain the parameters of the binary system. An valuable independent source are ground-bases, high-resolution spectrographs
Prospective cognitions in anxiety and depression: Replication and methodological extension
The present study presents a replication and methodological extension of MacLeod, Tata, Kentish, and Jacobsen (1997) with a nonclinical sample, using future-directed imagery to assess prospective cognitions. Results showed that only anxiety (but not depression) was related to enhanced imagery for future negative events. Both anxiety and depression showed significant zero-order correlations with reduced imagery for future positive events. However, when the overlap between anxiety and depression was controlled for, only depression (but not anxiety) showed a unique association with reduced imagery for positive events. Implications of these findings for cognitive models of anxiety and depression are discussed
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