108,148 research outputs found
Nonuniversal Effects in the Homogeneous Bose Gas
Effective field theory predicts that the leading nonuniversal effects in the
homogeneous Bose gas arise from the effective range for S-wave scattering and
from an effective three-body contact interaction. We calculate the leading
nonuniversal contributions to the energy density and condensate fraction and
compare the predictions with results from diffusion Monte Carlo calculations by
Giorgini, Boronat, and Casulleras. We give a crude determination of the
strength of the three-body contact interaction for various model potentials.
Accurate determinations could be obtained from diffusion Monte Carlo
calculations of the energy density with higher statistics.Comment: 24 pages, RevTex, 5 ps figures, included with epsf.te
Software-Engineering Process Simulation (SEPS) model
The Software Engineering Process Simulation (SEPS) model is described which was developed at JPL. SEPS is a dynamic simulation model of the software project development process. It uses the feedback principles of system dynamics to simulate the dynamic interactions among various software life cycle development activities and management decision making processes. The model is designed to be a planning tool to examine tradeoffs of cost, schedule, and functionality, and to test the implications of different managerial policies on a project's outcome. Furthermore, SEPS will enable software managers to gain a better understanding of the dynamics of software project development and perform postmodern assessments
Controlled enhancement or suppression of exchange biasing using impurity -layers
The effects of inserting impurity -layers of various elements into a
Co/IrMn exchange biased bilayer, at both the interface, and at given points
within the IrMn layer a distance from the interface, has been investigated.
Depending on the chemical species of dopant, and its position, we found that
the exchange biasing can be either strongly enhanced or suppressed. We show
that biasing is enhanced with a dusting of certain magnetic impurities, present
at either at the interface or sufficiently far away from the Co/IrMn interface.
This illustrates that the final spin structure at the Co/IrMn interface is not
only governed by interface structure/roughness but is also mediated by local
exchange or anisotropy variations within the bulk of the IrMn
Observation of strong electron dephasing in disordered CuGeAu thin films
We report the observation of strong electron dephasing in a series of
disordered CuGeAu thin films. A very short electron dephasing
time possessing very weak temperature dependence around 6 K, followed by an
upturn with further decrease in temperature below 4 K, is found. The upturn is
progressively more pronounced in more disordered samples. Moreover, a ln
dependent, but high-magnetic-field-insensitive, resistance rise persisting from
above 10 K down to 30 mK is observed in the films. These results suggest a
nonmagnetic dephasing process which is stronger than any known mechanism and
may originate from the coupling of conduction electrons to dynamic defects.Comment: to appear in Phys. Rev. Let
Electrical impedance imaging in two-phase, gas-liquid flows: 1. Initial investigation
The determination of interfacial area density in two-phase, gas-liquid flows is one of the major elements impeding significant development of predictive tools based on the two-fluid model. Currently, these models require coupling of liquid and vapor at interfaces using constitutive equations which do not exist in any but the most rudimentary form. Work described herein represents the first step towards the development of Electrical Impedance Computed Tomography (EICT) for nonintrusive determination of interfacial structure and evolution in such flows
Pair Interaction Potentials of Colloids by Extrapolation of Confocal Microscopy Measurements of Collective Structure
A method for measuring the pair interaction potential between colloidal
particles by extrapolation measurement of collective structure to infinite
dilution is presented and explored using simulation and experiment. The method
is particularly well suited to systems in which the colloid is fluorescent and
refractive index matched with the solvent. The method involves characterizing
the potential of mean force between colloidal particles in suspension by
measurement of the radial distribution function using 3D direct visualization.
The potentials of mean force are extrapolated to infinite dilution to yield an
estimate of the pair interaction potential, . We use Monte Carlo (MC)
simulation to test and establish our methodology as well as to explore the
effects of polydispersity on the accuracy. We use poly-12-hydroxystearic
acid-stabilized poly(methyl methacrylate) (PHSA-PMMA) particles dispersed in
the solvent dioctyl phthalate (DOP) to test the method and assess its accuracy
for three different repulsive systems for which the range has been manipulated
by addition of electrolyte.Comment: 35 pages, 14 figure
Adiabatic self-tuning in a silicon microdisk optical resonator
We demonstrate a method for adiabatically self-tuning a silicon microdisk resonator. This mechanism is not only able to sensitively probe the fast nonlinear cavity dynamics, but also provides various optical functionalities like pulse compression, shaping, and tunable time delay
Matrix elements of the complete set of \Delta B = 2 and \Delta C = 2 operators in heavy meson chiral perturbation theory
Using heavy meson chiral perturbation theory, we consider the light
quark-mass and spatial volume dependence of the matrix elements of \Delta B=2
and \Delta C=2 four-quark operators relevant for
B^{0}_{(s)}{-}\bar{B}^{0}_{(s)} and D^{0}{-}\bar{D}^{0} mixing, and the B_{s}
meson width difference. Our results for these matrix elements are obtained in
the N_{f}=2+1 partially quenched theory, which becomes full QCD in the limit
where sea and valence quark masses become equal. They can be used in
extrapolation of lattice calculations of these matrix elements to the physical
light quark masses and to infinite volume. An important conclusion of this
paper is that the chiral extrapolations for matrix elements of heavy-light
meson mixing beyond the Standard Model, and those relevant for the B_s width
difference are more complicated than that for the Standard Model mixing matrix
elements.Comment: 13 pages; version accepted for publicatio
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