5,775 research outputs found
Colonialism, Justice and the Rule of Law: A Southern African and Australian Narrative
Colonialism has had a huge impact upon the legal systems of countries around the world. The historical impact of the British Empire can still be felt today in countries as diverse as Australia and South Africa. This effect is explored in both these countries, both in its historical form of racial discrimination, as well as the modern consequences of this colonial past. This article analyses how formal conceptions of the Rule of Law and legal certainty can undermine efforts to achieve justice for past historical wrongs. Examples of this are found in the Aboriginal land rights litigation in Australia, as well as litigation under the Alien Tort Statute in the United States of America
Astrometric Method to Break the Photometric Degeneracy between Binary-source and Planetary Microlensing Perturbations
An extra-solar planet can be detected by microlensing because the planet can
perturb the smooth lensing light curve created by the primary lens. However, it
was shown by Gaudi that a subset of binary-source events can produce light
curves that closely resemble those produced by a significant fraction of
planet/star lens systems, causing serious contamination of a sample of
suspected planetary systems detected via microlensing. In this paper, we show
that if a lensing event is observed astrometrically, one can unambiguously
break the photometric degeneracy between binary-source and planetary lensing
perturbations. This is possible because while the planet-induced perturbation
in the trajectory of the lensed source image centroid shifts points away from
the opening of the unperturbed elliptical trajectory, while the perturbation
induced by the binary source companion points always towards the opening.
Therefore, astrometric microlensing observations by using future high-precision
interferometers will be important for solid confirmation of microlensing planet
detections.Comment: total 5 pages, including 1 figure and no table, ApJ, submitted,
better quality pdf file is avalilable at
http://astroph.chungbuk.ac.kr/~cheongho/publication.htm
Directed percolation in aerodynamics: resolving laminar separation bubble on airfoils
In nature, phase transitions prevail amongst inherently different systems,
while frequently showing a universal behavior at their critical point. As a
fundamental phenomenon of fluid mechanics, recent studies suggested
laminar-turbulent transition belonging to the universality class of directed
percolation. Beyond, no indication was yet found that directed percolation is
encountered in technical relevant fluid mechanics. Here, we present first
evidence that the onset of a laminar separation bubble on an airfoil can be
well characterized employing the directed percolation model on high fidelity
particle image velocimetry data. In an extensive analysis, we show that the
obtained critical exponents are robust against parameter fluctuations, namely
threshold of turbulence intensity that distinguishes between ambient flow and
laminar separation bubble. Our findings indicate a comprehensive significance
of percolation models in fluid mechanics beyond fundamental flow phenomena, in
particular, it enables the precise determination of the transition point of the
laminar separation bubble. This opens a broad variety of new fields of
application, ranging from experimental airfoil aerodynamics to computational
fluid dynamics.Comment: 8 pages, 11 figure
Scattered light mapping of protoplanetary disks
High-contrast scattered light observations have revealed the surface
morphology of several dozens of protoplanetary disks at optical and
near-infrared wavelengths. Inclined disks offer the opportunity to measure part
of the phase function of the dust grains that reside in the disk surface which
is essential for our understanding of protoplanetary dust properties and the
early stages of planet formation. We aim to construct a method which takes into
account how the flaring shape of the scattering surface of an (optically thick)
protoplanetary disk projects onto the image plane of the observer. This allows
us to map physical quantities (scattering radius and scattering angle) onto
scattered light images and retrieve stellar irradiation corrected (r^2-scaled)
images and dust phase functions. We apply the method on archival polarized
intensity images of the protoplanetary disk around HD 100546 that were obtained
with VLT/SPHERE in R'-band and VLT/NACO in H- and Ks-band. The brightest side
of the r^2-scaled R'-band polarized intensity image of HD 100546 changes from
the far to the near side of the disk when a flaring instead of a geometrically
flat disk surface is used for the r^2-scaling. The decrease in polarized
surface brightness in the scattering angle range of ~40-70 deg is likely a
result of the dust phase function and degree of polarization which peak in
different scattering angle regimes. The derived phase functions show part of a
forward scattering peak which indicates that large, aggregate dust grains
dominate the scattering opacity in the disk surface. Projection effects of a
protoplanetary disk surface need to be taken into account to correctly
interpret scattered light images. Applying the correct scaling for the
correction of stellar irradiation is crucial for the interpretation of the
images and the derivation of the dust properties in the disk surface layer.Comment: Accepted for publication in A&A, 6 pages, 3 figure
- …