4,604 research outputs found
The Stochastic Dynamics of Rectangular and V-shaped Atomic Force Microscope Cantilevers in a Viscous Fluid and Near a Solid Boundary
Using a thermodynamic approach based upon the fluctuation-dissipation theorem
we quantify the stochastic dynamics of rectangular and V-shaped microscale
cantilevers immersed in a viscous fluid. We show that the stochastic cantilever
dynamics as measured by the displacement of the cantilever tip or by the angle
of the cantilever tip are different. We trace this difference to contributions
from the higher modes of the cantilever. We find that contributions from the
higher modes are significant in the dynamics of the cantilever tip-angle. For
the V-shaped cantilever the resulting flow field is three-dimensional and
complex in contrast to what is found for a long and slender rectangular
cantilever. Despite this complexity the stochastic dynamics can be predicted
using a two-dimensional model with an appropriately chosen length scale. We
also quantify the increased fluid dissipation that results as a V-shaped
cantilever is brought near a solid planar boundary.Comment: 10 pages, 15 images, corrected equation (8
Quantum mutual information of an entangled state propagating through a fast-light medium
Although it is widely accepted that classical information cannot travel
faster than the speed of light in vacuum, the behavior of quantum correlations
and quantum information propagating through actively-pumped fast-light media
has not been studied in detail. To investigate this behavior, we send one half
of an entangled state of light through a gain-assisted fast-light medium and
detect the remaining quantum correlations. We show that the quantum
correlations can be advanced by a small fraction of the correlation time while
the entanglement is preserved even in the presence of noise added by
phase-insensitive gain. Additionally, although we observe an advance of the
peak of the quantum mutual information between the modes, we find that the
degradation of the mutual information due to the added noise appears to prevent
an advancement of the leading edge. In contrast, we show that both the leading
and trailing edges of the mutual information in a slow-light system can be
significantly delayed
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Range Cattle Production, I: Reproduction: A Literature Review
This item is part of the Agricultural Experiment Station archive. It was digitized from a physical copy provided by the University Libraries at the University of Arizona. For more information, please email CALS Publications at [email protected]
The stochastic dynamics of micron and nanoscale elastic cantilevers in fluid: fluctuations from dissipation
The stochastic dynamics of micron and nanoscale cantilevers immersed in a
viscous fluid are quantified. Analytical results are presented for long slender
cantilevers driven by Brownian noise. The spectral density of the noise force
is not assumed to be white and the frequency dependence is determined from the
fluctuation-dissipation theorem. The analytical results are shown to be useful
for the micron scale cantilevers that are commonly used in atomic force
microscopy. A general thermodynamic approach is developed that is valid for
cantilevers of arbitrary geometry as well as for arrays of multiple cantilevers
whose stochastic motion is coupled through the fluid. It is shown that the
fluctuation-dissipation theorem permits the calculation of stochastic
quantities via straightforward deterministic methods. The thermodynamic
approach is used with deterministic finite element numerical simulations to
quantify the autocorrelation and noise spectrum of cantilever fluctuations for
a single micron scale cantilever and the cross-correlations and noise spectra
of fluctuations for an array of two experimentally motivated nanoscale
cantilevers as a function of cantilever separation. The results are used to
quantify the noise reduction possible using correlated measurements with two
closely spaced nanoscale cantilevers.Comment: Submitted to Nanotechnology April 26, 200
Union Administrative Practices: A Comparative Analysis
In response to growing challenges, many labor organizations are reevaluating themselves in an effort to become more efficient and effective. Their efforts, however, are limited by their frames of reference. Seldom do unions compare practices across labor movements. To expand these frames of reference we compare union administrative practices in three countries: Canada, the United Kingdom, and the United States. Two specific areas of union administration are examined — human resource/personnel practices and strategic planning. Results from these countries are presented and analyzed to identify and explain similarities and differences
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