27,072 research outputs found
Residual tensile strength in the presence of through cracks or surface cracks
Residual tensile strength in presence of through cracks or surface crack
Nonlinear optical response of hole-trion systems in quantum dots in tilted magnetic fields
We discuss, from a theoretical point of view, the four wave mixing
spectroscopy on an ensemble of p-doped quantum dots in a magnetic field
slightly tilted from the in-plane configuration. We describe the system
evolution in the density matrix formalism. In the limit of coherent ultrafast
optical driving, we obtain analytical formulas for the single system dynamics
and for the response of an inhomogeneously broadened ensemble. The results are
compared to the previously studied time-resolved Kerr rotation spectroscopy on
the same system. We show that the Kerr rotation and four wave mixing spectra
yield complementary information on the spin dynamics (precession and damping).Comment: 4 pages, 2 figures, conference NOEKS1
Assimilation via prices or quantities? Sources of immigrant earnings growth in Australia, Canada and the United States
Using 1980/81 and 1990/91 census data from Australia, Canada, and the United States, we
estimate the effects of time in the destination country on male immigrants’ wages,
employment, and earnings. We find that total earnings assimilation is greatest in the United
States and least in Australia. Employment assimilation explains all of the earnings progress
experienced by Australian immigrants, whereas wage assimilation plays the dominant role in
the United States, and Canada falls in-between. We argue that relatively inflexible wages and
generous unemployment insurance in countries like Australia may cause assimilation to occur
along the “quantity” rather than the price dimension
Understanding the truth about subjectivity
Results of two experiments show children’s understanding of diversity in personal preference is incomplete. Despite acknowledging diversity, in Experiment 1(N=108), 6-
and 8-year-old children were less likely than adults to see preference as a legitimate basis for personal tastes and more likely to say a single truth could be found about a matter of taste. In Experiment 2 (N=96), 7- and 9-year-olds were less likely than 11- and 13-yearolds to say a dispute about a matter of preference might not be resolved. These data suggest that acceptance of the possibility of diversity does not indicate an adult-like understanding of subjectivity. An understanding of the relative emphasis placed on objective and subjective factors in different contexts continues to develop into adolescence
Theory of the time-resolved Kerr rotation on trapped holes
We formulate a model of the time-resolved Kerr rotation experiment on a
single hole in a semiconductor nanostructure (e.g., a quantum dot) or on an
ensemble of trapped holes (e.g., in a quantum well) in a tilted magnetic field.
We use a generic Markovian description of the hole and trion dephasing and
focus on the interpretation of the time-resolved signal in terms of the
microscopic evolution of the spin polarization. We show that the signal in an
off-plane field contains components that reveal both the spin relaxation rate
and the spin coherence dephasing rate. We derive analytical formulas for the
hole spin polarization, which may be used to extract the two relevant rates by
fitting to the measurement data.Comment: 13 pages, 7 figure
Spin Structure of the Nucleon - Status and Recent Results
After the initial discovery of the so-called "spin crisis in the parton
model" in the 1980's, a large set of polarization data in deep inelastic
lepton-nucleon scattering was collected at labs like SLAC, DESY and CERN. More
recently, new high precision data at large x and in the resonance region have
come from experiments at Jefferson Lab. These data, in combination with the
earlier ones, allow us to study in detail the polarized parton densities, the
Q^2 dependence of various moments of spin structure functions, the duality
between deep inelastic and resonance data, and the nucleon structure in the
valence quark region. Together with complementary data from HERMES, RHIC and
COMPASS, we can put new limits on the flavor decomposition and the gluon
contribution to the nucleon spin. In this report, we provide an overview of our
present knowledge of the nucleon spin structure and give an outlook on future
experiments. We focus in particular on the spin structure functions g_1 and g_2
of the nucleon and their moments.Comment: 69 pages, 46 figures. Report to be published in "Progress in Particle
and Nuclear Physics". v2 with added references and minor edit
Kinetic Monte Carlo simulations of oscillatory shape evolution for electromigration-driven islands
The shape evolution of two-dimensional islands under electromigration-driven
periphery diffusion is studied by kinetic Monte Carlo (KMC) simulations and
continuum theory. The energetics of the KMC model is adapted to the Cu(100)
surface, and the continuum model is matched to the KMC model by a suitably
parametrized choice of the orientation-dependent step stiffness and step atom
mobility. At 700 K shape oscillations predicted by continuum theory are
quantitatively verified by the KMC simulations, while at 500 K qualitative
differences between the two modeling approaches are found.Comment: 7 pages, 6 figure
- …