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