11,619 research outputs found
Modelling the Incidence of Self-Employment: Individual and Employment Type Heterogeneity
Modelling the incidence of self-employment has traditionally proved problematic. Whilst the individual supply side characteristics of the self-employed are well documented, we argue that the literature has largely neglected demand-side aspects. We explore the determinants of self-employment using individual level data drawn from the U.S. Survey of Consumer Finances (SCF). We present results from an econometric framework, the Parameterised Dogit model, that allows us to separately, and simultaneously, model individual heterogeneity (i.e. supply side) and employment type heterogeneity (i.e. demand-side) influences that determine self-employment. Our findings suggest that whilst individual characteristics are important determinants of self-employment, there are also factors which are specific to the type of employment that influence whether an individual is self-employed
Local Eigenvalue Density for General MANOVA Matrices
We consider random n\times n matrices of the form
(XX*+YY*)^{-1/2}YY*(XX*+YY*)^{-1/2}, where X and Y have independent entries
with zero mean and variance one. These matrices are the natural generalization
of the Gaussian case, which are known as MANOVA matrices and which have joint
eigenvalue density given by the third classical ensemble, the Jacobi ensemble.
We show that, away from the spectral edge, the eigenvalue density converges to
the limiting density of the Jacobi ensemble even on the shortest possible
scales of order 1/n (up to \log n factors). This result is the analogue of the
local Wigner semicircle law and the local Marchenko-Pastur law for general
MANOVA matrices.Comment: Several small changes made to the tex
Data compression for the Cassini radio and plasma wave instrument
The Cassini Radio and Plasma Wave Science experiment will employ data compression to make effective use of the available data telemetry bandwidth. Some compression will be achieved by use of a lossless data compression chip and some by software in a dedicated 80C85 processor. A description of the instrument and data compression system are included in this report. Also, the selection of data compression systems and acceptability of data degradation is addressed
Further Observations of the Intermediate Mass Black Hole Candidate ESO 243-49 HLX-1
The brightest Ultra-Luminous X-ray source HLX-1 in the galaxy ESO 243-49
currently provides strong evidence for the existence of intermediate mass black
holes. Here we present the latest multi-wavelength results on this intriguing
source in X-ray, UV and radio bands. We have refined the X-ray position to
sub-arcsecond accuracy. We also report the detection of UV emission that could
indicate ongoing star formation in the region around HLX-1. The lack of
detectable radio emission at the X-ray position strengthens the argument
against a background AGN.Comment: 4 pages, 2 figures. Accepted 11th of Feb 2010. Contributed talk to
appear in Proceedings of "X-ray Astronomy 2009: Present Status,
Multi-Wavelength Approach and Future Perspectives", Bologna, Italy, September
7-11, 2009, AIP, eds. A. Comastri, M. Cappi, and L. Angelin
Formation of a Nematic Fluid at High Fields in Sr3Ru2O7
In principle, a complex assembly of strongly interacting electrons can
self-organise into a wide variety of collective states, but relatively few such
states have been identified in practice. We report that, in the close vicinity
of a metamagnetic quantum critical point, high purity Sr3Ru2O7 possesses a
large magnetoresistive anisotropy, consistent with the existence of an
electronic nematic fluid. We discuss a striking phenomenological similarity
between our observations and those made in high purity two-dimensional electron
fluids in GaAs devices.Comment: 14 pages, 3 figures, 11 extra pages of supplementary informatio
Prospective Memory Performance in Simulated Air Traffic Control: Robust to Interruptions but Impaired by Retention Interval
OBJECTIVE: To examine the effects of interruptions and retention interval on prospective memory for deferred tasks in simulated air traffic control. BACKGROUND: In many safety-critical environments, operators need to remember to perform a deferred task, which requires prospective memory. Laboratory experiments suggest that extended prospective memory retention intervals, and interruptions in those retention intervals, could impair prospective memory performance. METHOD: Participants managed a simulated air traffic control sector. Participants were sometimes instructed to perform a deferred handoff task, requiring them to deviate from a routine procedure. We manipulated whether an interruption occurred during the prospective memory retention interval or not, the length of the retention interval (37-117 s), and the temporal proximity of the interruption to deferred task encoding and execution. We also measured performance on ongoing tasks. RESULTS: Increasing retention intervals (37-117 s) decreased the probability of remembering to perform the deferred task. Costs to ongoing conflict detection accuracy and routine handoff speed were observed when a prospective memory intention had to be maintained. Interruptions did not affect individuals' speed or accuracy on the deferred task. CONCLUSION: Longer retention intervals increase risk of prospective memory error and of ongoing task performance being impaired by cognitive load; however, prospective memory can be robust to effects of interruptions when the task environment provides cuing and offloading. APPLICATION: To support operators in performing complex and dynamic tasks, prospective memory demands should be reduced, and the retention interval of deferred tasks should be kept as short as possible
Conditions for one-dimensional supersonic flow of quantum gases
One can use transsonic Bose-Einstein condensates of alkali atoms to establish
the laboratory analog of the event horizon and to measure the acoustic version
of Hawking radiation. We determine the conditions for supersonic flow and the
Hawking temperature for realistic condensates on waveguides where an external
potential plays the role of a supersonic nozzle. The transition to supersonic
speed occurs at the potential maximum and the Hawking temperature is entirely
determined by the curvature of the potential
A molecular-MNIST dataset for machine learning study on diffraction imaging and microscopy
An image dataset of 10 different size molecules, where each molecule has 2,000 structural variants, is generated from the 2D cross-sectional projection of Molecular Dynamics trajectories. The purpose of this dataset is to provide a benchmark dataset for the increasing need of machine learning, deep learning and image processing on the study of scattering, imaging and microscopy
First-Order Vortex Lattice Melting and Magnetization of YBaCuO$_{7-\delta}
We present the first non-mean-field calculation of the magnetization
of YBaCuO both above and below the flux-lattice melting
temperature . The results are in good agreement with experiment as a
function of transverse applied field . The effects of fluctuations in both
order parameter and magnetic induction are included in the
Ginzburg-Landau free energy functional: fluctuates within the
lowest Landau level in each layer, while fluctuates uniformly according to
the appropriate Boltzmann factor. The second derivative is predicted to be negative throughout the vortex liquid state and
positive in the solid state. The discontinuities in entropy and magnetization
at melting are calculated to be per flux line per layer and
~emu~cm at a field of 50 kOe.Comment: 11 pages, 4 PostScript figures in one uuencoded fil
- …