6,489 research outputs found
Antenna Technology for QUASAT application
A hybrid growth version of the advanced Sunflower, or precision deployable, antenna was adopted as the configuration proposed for the QUASAT very long baseline interferometry mission. The antenna consists of rigid panels of graphite-epoxy facesheets covering aluminum honeycomb sandwich. The six main folding panels are hinged to a cantilevered support ring attached to the periphery of the center section. Six pairs of intermediate panels are located between these panels and are hinged to each other and to the main panels. The flight configuration, antenna weight, a mass properties, frequency, and contour tolerance are discussed. The advantages of the solid antenna surface cover an all-mesh contour are examined
Origins and Prospects for Employee Life and Health Trusts in Canada
A discussion of the events and factors behind the establishment of pre-funded health benefit plans in Canada with reference to the experience of voluntary employee benefit associations in the United States and the auto sector restructuring in North America during 2008-2009. It is argued that employee life and health trusts are used in effect to defease legacy cost liabilities of employers and only likely to be used in the context of restructuring of a workplace or industry. their structure is compared to other target benefit programs currently being proposed in Canada and elsewhere. The key issues in their negotiation and administration are summarized
The BCE Decision: Reflections on the Firm as a Contractual Organization
The authors discuss the decision of the Supreme Court of Canada to approve a plan of arrangement privatizing BCE Inc. over the objections of bondholders. Summarizing the arguments for shareholder primacy and debenture covenants delimiting contractual rights against boards and management, they argue that an expanded conception of relational contract theory is useful in analyzing the competing claims in the BCE deal and litigation. This approach requires that broader contextual factors are necessary to consider in the functioning of the corporation, especially by after-the-fact decision-makers
The BCE Decision: Reflections on the Firm as a Contractual Organization
The authors discuss the decision of the Supreme Court of Canada to approve a plan of arrangement privatizing BCE Inc. over the objections of bondholders. Summarizing the arguments for shareholder primacy and debenture covenants delimiting contractual rights against boards and management, they argue that an expanded conception of relational contract theory is useful in analyzing the competing claims in the BCE deal and litigation. This approach requires that broader contextual factors are necessary to consider in the functioning of the corporation, especially by after-the-fact decision-makers
Modelling the evaporation of thin films of colloidal suspensions using Dynamical Density Functional Theory
Recent experiments have shown that various structures may be formed during
the evaporative dewetting of thin films of colloidal suspensions. Nano-particle
deposits of strongly branched `flower-like', labyrinthine and network
structures are observed. They are caused by the different transport processes
and the rich phase behaviour of the system. We develop a model for the system,
based on a dynamical density functional theory, which reproduces these
structures. The model is employed to determine the influences of the solvent
evaporation and of the diffusion of the colloidal particles and of the liquid
over the surface. Finally, we investigate the conditions needed for
`liquid-particle' phase separation to occur and discuss its effect on the
self-organised nano-structures
Collective shuttling of attracting particles in asymmetric narrow channels
The rectification of a single file of attracting particles subjected to a low
frequency ac drive is proposed as a working mechanism for particle shuttling in
an asymmetric narrow channel. Increasing the particle attraction results in the
file condensing, as signalled by the dramatic enhancement of the net particle
current. Magnitude and direction of the current become extremely sensitive to
the actual size of the condensate, which can then be made to shuttle between
two docking stations, transporting particles in one direction, with an
efficiency much larger than conventional diffusive models predict
Exceptionally strong magnetism in 4d perovskites RTcO3 (R=Ca,Sr,Ba)
The evolution of the magnetic ordering temperature of the 4d3 perovskites
RTcO3 (R=Ca,Sr,Ba) and its relation with its electronic and structural
properties has been studied by means of hybrid density functional theory and
Monte Carlo simulations. When compared to the most widely studied 3d
perovskites the large spatial extent of the 4d shells and their relatively
strong hybridization with oxygen weaken the tendency to form Jahn-Teller like
orbital ordering. This strengthens the superexchange interaction. The resulting
insulating G-type antiferromagnetic ground state is characterized by large
superexchange coupling constants (26-35 meV) and Neel temperatures (750-1200
K). These monotonically increase as a function of the R ionic radius due to the
progressive enhancement of the volume and the associated decrease of the
cooperative rotation of the TcO6 octahedra.Comment: 4 pages, 3 figure
Revision of basal macropodids from the Riversleigh World Heritage Area with descriptions of new material of Ganguroo bilamina Cooke, 1997 and a new species
The relationship of basal macropodids (Marsupialia: Macropodoidea) from the Oligo-Miocene of Australia have been unclear. Here, we describe a new species from the Bitesantennary Site within the Riversleigh's World Heritage Area (WHA), Ganguroo bites n. sp., new cranial and dental material of G. bilamina, and reassess material previously described as Bulungamaya delicata and 'Nowidgee matrix'. We performed a metric analysis of dental measurements on species of Thylogale which we then used, in combination with morphological features, to determine species boundaries in the fossils. We also performed a phylogenetic analysis to clarify the relationships of basal macropodid species within Macropodoidea. Our results support the distinction of G. bilamina, G. bites and B. delicata, but 'Nowidgee matrix' appears to be a synonym of B. delicata. The results of our phylogenetic analysis are inconclusive, but dental and cranial features suggest a close affinity between G. bilamina and macropodids. Finally, we revise the current understanding of basal macropodid diversity in Oligocene and Miocene sites at Riversleigh WHA
Atomic self-interaction correction for molecules and solids
We present an atomic orbital based approximate scheme for self-interaction
correction (SIC) to the local density approximation of density functional
theory. The method, based on the idea of Filippetti and Spaldin [Phys. Rev. B
67, 125109 (2003)], is implemented in a code using localized numerical atomic
orbital basis sets and is now suitable for both molecules and extended solids.
After deriving the fundamental equations as a non-variational approximation of
the self-consistent SIC theory, we present results for a wide range of
molecules and insulators. In particular, we investigate the effect of
re-scaling the self-interaction correction and we establish a link with the
existing atomic-like corrective scheme LDA+U. We find that when no re-scaling
is applied, i.e. when we consider the entire atomic correction, the Kohn-Sham
HOMO eigenvalue is a rather good approximation to the experimental ionization
potential for molecules. Similarly the HOMO eigenvalues of negatively charged
molecules reproduce closely the molecular affinities. In contrast a re-scaling
of about 50% is necessary to reproduce insulator bandgaps in solids, which
otherwise are largely overestimated. The method therefore represents a
Kohn-Sham based single-particle theory and offers good prospects for
applications where the actual position of the Kohn-Sham eigenvalues is
important, such as quantum transport.Comment: 16 pages, 7 figure
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