39,598 research outputs found
Interpretive discourses in South Africa\'s Education White Paper No. 6: Special Needs Education
No Abstract. South African Journal of EducationVol. 23(2) 2003: pp. 152-15
Minimax Estimation of Nonregular Parameters and Discontinuity in Minimax Risk
When a parameter of interest is nondifferentiable in the probability, the
existing theory of semiparametric efficient estimation is not applicable, as it
does not have an influence function. Song (2014) recently developed a local
asymptotic minimax estimation theory for a parameter that is a
nondifferentiable transform of a regular parameter, where the nondifferentiable
transform is a composite map of a continuous piecewise linear map with a single
kink point and a translation-scale equivariant map. The contribution of this
paper is two fold. First, this paper extends the local asymptotic minimax
theory to nondifferentiable transforms that are a composite map of a Lipschitz
continuous map having a finite set of nondifferentiability points and a
translation-scale equivariant map. Second, this paper investigates the
discontinuity of the local asymptotic minimax risk in the true probability and
shows that the proposed estimator remains to be optimal even when the risk is
locally robustified not only over the scores at the true probability, but also
over the true probability itself. However, the local robustification does not
resolve the issue of discontinuity in the local asymptotic minimax risk
Radiation of Optical Angular Momentum from a Dipole Source in a Magneto-birefringent Environment
We investigate the radiation of optical angular momentum by a dipole gas
under uniform magnetic field with an unpolarized source at its center.
Conservation of angular momentum implies that the radiation of angular momentum
results in a torque on both the source and the surrounding environment.
Moreover, we study the spin and orbital contributions to the radiated angular
momentum
Numerical Simulation of Radiative Transfer of Electromagnetic Angular Momentum
We present numerical simulations of light emitted by a source and scattered
by surrounding electric dipoles with Zeeman splitting. We calculate the leakage
of electromagnetic angular momentum to infinity.Comment: submitted to Acta Physica Polonica A: Conference Proceedings of 11th
Workshop on Quantum Chaos and Localisation Phenomena, May 202
Relativistic dynamical polarizability of hydrogen-like atoms
Using the operator representation of the Dirac Coulomb Green function the
analytical method in perturbation theory is employed in obtaining solutions of
the Dirac equation for a hydrogen-like atom in a time-dependent electric field.
The relativistic dynamical polarizability of hydrogen-like atoms is calculated
and analysed.Comment: 15 pages, 3 figures (not included, but hard copies are available upon
request
Imaging the dust sublimation front of a circumbinary disk
We present the first near-IR milli-arcsecond-scale image of a post-AGB binary
that is surrounded by hot circumbinary dust. A very rich interferometric data
set in six spectral channels was acquired of IRAS08544-4431 with the new RAPID
camera on the PIONIER beam combiner at the Very Large Telescope Interferometer
(VLTI). A broadband image in the \textit{H} band was reconstructed by combining
the data of all spectral channels using the SPARCO method. We spatially
separate all the building blocks of the IRAS08544-4431 system in our
milliarcsecond-resolution image. Our dissection reveals a dust sublimation
front that is strikingly similar to that expected in early-stage protoplanetary
disks, as well as an unexpected flux signal of 4\% from the secondary
star. The energy output from this companion indicates the presence of a compact
circum-companion accretion disk, which is likely the origin of the fast outflow
detected in H. Our image provides the most detailed view into the heart
of a dusty circumstellar disk to date. Our results demonstrate that binary
evolution processes and circumstellar disk evolution can be studied in detail
in space and over time.Comment: PR @ http://www.eso.org/public/news/eso1608
GSMBE growth of GaInAsP/InP 1.3 mu m-TM-lasers for monolithic integration with optical waveguide isolator
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