14,385 research outputs found
Dust outflows and inner gaps generated by massive planets in debris disks
Main sequence stars are commonly surrounded by debris disks, formed by cold
far-IR-emitting dust that is thought to be continuously replenished by a
reservoir of undetected dust-producing planetesimals. We have investigated the
orbital evolution of dust particles in debris disks harboring massive planets.
Small dust grains are blown out by radiation pressure, as is well known; in
addition, gravitational scattering by the giant planets also creates an outflow
of large grains. We describe the characteristics of this large-particle outflow
in different planetary architectures and for different particle sizes. In
addition, the ejection of particles is responsible for the clearing of dust
inside the orbit of the planet. We study the efficiency of particle ejection
and the resulting dust density contrast inside and outside the orbit of the
planet, as a function of the planet's mass and orbital elements and the
particle size. We discuss its implications for exo-planetary debris disks and
for the interpretation of in-situ dust detection experiments on space probes
traveling in the outer solar system.Comment: 32 pages (pre-print format), including 12 figures. Accepted to ApJ
(2005). Due to space constrains Fig. 3-6 are at very low resolutio
Dynamics of the Kuiper Belt
Our current knowledge of the dynamical structure of the Kuiper Belt is
reviewed here. Numerical results on long term orbital evolution and dynamical
mechanisms underlying the transport of objects out of the Kuiper Belt are
discussed. Scenarios about the origin of the highly non-uniform orbital
distribution of Kuiper Belt objects are described, as well as the constraints
these provide on the formation and long term dynamical evolution of the outer
Solar system. Possible mechanisms include an early history of orbital migration
of the outer planets, a mass loss phase in the outer Solar system and
scattering by large planetesimals. The origin and dynamics of the scattered
component of the Kuiper Belt is discussed. Inferences about the primordial mass
distribution in the trans-Neptune region are reviewed. Outstanding questions
about Kuiper Belt dynamics are listed.Comment: 22 pages plus 8 figures added footnote, figure
A study of mitochondrial membranes in relation to elementary particles
Elementary particles that commonly have been seen by electron microscopy to be attached by stalks to mitochondrial cristae in negatively stained preparations, were not apparent in similarly stained mitochondria from exponentially growing wild-type Neurospora crassa when these were isolated in sucrose solution containing 1 x 10^-3 M EDTA. However, elementary particles were easily demonstrable in electron micrographs if the mitochondria were isolated without EDTA in the sucrose solution. A biochemical study indicated that both kinds of mitochondrial preparations, isolated in the presence or absence of EDTA, had about the same capacity for oxidative phosphorylation. Observations on rat-liver mitochondria also suggested that the stalked elementary particles were more easily demonstrated if the preparation was made in the absence of EDTA. It was difficult to demonstrate elementary particles in wild-type Neurospora mitochondria isolated with or without EDTA and subsequently prepared for electron microscopy by spreading on the surface of an aqueous solution of potassium phosphotungstate. Elementary particles could be demonstrated in poky Neurospora mitochondria isolated with EDTA if the mitochondria were spread on the surface of an aqueous solution of phosphotungstate. It was concluded that biochemical functions associated with elementary particles are independent of structural configuration as seen by electron microscopy
Dynamic Resonance Effects in the Statistical Distributions of Asteroids and Comets
Some principles in the distribution of Centaurs and the "Scattered Disk"
objects, as well as the Kuiper belt objects for its semi-major axes,
eccentricities and inclinations of the orbits have been investigated. It has
been established, that more than a half from them move on the resonant orbits
and that is what has been predicted earlier. The divergence of the maximum in
the observable distribution of the objects of the Kuiper belt for the
semi-major axes with an exact orbital resonance has been interpreted.Comment: 7 pages, 5 figures, 1 table. International Conference "100 years
since Tunguska phenomenon: Past, present and future", (June 26-28, 2008.
Russia, Moscow), International Conference "Modern problems of astronomy"
(August 12-18, 2007, Ukraine, Odessa
Creating Intelligent Linking for Information Threading in Knowledge Networks
Informledge System (ILS) is a knowledge network with autonomous nodes and
intelligent links that integrate and structure the pieces of knowledge. In this
paper, we aim to put forward the link dynamics involved in intelligent
processing of information in ILS. There has been advancement in knowledge
management field which involve managing information in databases from a single
domain. ILS works with information from multiple domains stored in distributed
way in the autonomous nodes termed as Knowledge Network Node (KNN). Along with
the concept under consideration, KNNs store the processed information linking
concepts and processors leading to the appropriate processing of information.Comment: 5 Pages, 6 Figures, 2 Tables, India Conference (INDICON), 201
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