19,786 research outputs found
The effect of temperature evolution on the interior structure of HO-rich planets
For most planets in the range of radii from 1 to 4 R, water is a
major component of the interior composition. At high pressure HO can be
solid, but for larger planets, like Neptune, the temperature can be too high
for this. Mass and age play a role in determining the transition between solid
and fluid (and mixed) water-rich super-Earth. We use the latest high-pressure
and ultra-high-pressure phase diagrams of HO, and by comparing them
with the interior adiabats of various planet models, the temperature evolution
of the planet interior is shown, especially for the state of HO. It
turns out that the bulk of HO in a planet's interior may exist in
various states such as plasma, superionic, ionic, Ice VII, Ice X, etc.,
depending on the size, age and cooling rate of the planet. Different regions of
the mass-radius phase space are also identified to correspond to different
planet structures. In general, super-Earth-size planets (isolated or without
significant parent star irradiation effects) older than about 3 Gyr would be
mostly solid.Comment: Accepted by ApJ, in print for March 2014 (14 pages, 3 colored
figures, 1 table
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Self-routing lowest common ancestor networks
Multistage interconnection networks (MIN's) allow communication between terminals on opposing sides of a network. Lowest Common Ancestor Networks (LCAN's) [1] have switches capable of connecting bi-directional links in a permutation pattern that additionally permits communication between terminals on the same side. Self-routing LCAN's have interesting permutation routing capabilities and are highly partionable. This paper characterizes self-routing LCAN's and analyzes their permutation routing capabilities. It is shown that the routing network of the CM-5 is a particular instance of an LCAN
Quantum Coins, Dice and Children: Probability and Quantum Statistics
We discuss counterintuitive aspects of probabilities for systems of identical
particles obeying quantum statistics. Quantum coins and children (two level
systems) and quantum dice (many level systems) are used as examples. It is
emphasized that, even in the absence of interactions, (anti)symmetrizations of
multi-particle wavefunctions destroy statistical independences and often lead
to dramatic departures from our intuitive expectations.Comment: 8 pages in REVTe
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Lowest common ancestor interconnection networks
Lowest Common Ancestor (LCA) networks are built using switches capable of connecting u + d inputs/outputs in a permutation pattern. For n source nodes and I stages of switches, n/d switches are used in stage l - n/d - u/d in stage l - 2, and in general , n-u^l-i-l/d^l-i switches in stage i. The resulting hierarchical structure possesses interesting connectivity and permutational properties. A full characterization of LCA networks is presented together with a permutation routing algorithm for a family of LCA networks. The algorithm uses the network itself to collect and disseminate information about the permutation. A schedule of O(dp log_d/u n) passes is obtained with a switch set-up cost factor of O(log_d/u n) (p is the minimum number of passes that an algorithm with global knowledge schedules)
Propagation of the 2012 March Coronal Mass Ejections from the Sun to Heliopause
In 2012 March the Sun exhibited extraordinary activities. In particular, the
active region NOAA AR 11429 emitted a series of large coronal mass ejections
(CMEs) which were imaged by STEREO as it rotated with the Sun from the east to
west. These sustained eruptions are expected to generate a global shell of
disturbed material sweeping through the heliosphere. A cluster of shocks and
interplanetary CMEs (ICMEs) were observed near the Earth, and are propagated
outward from 1 AU using an MHD model. The transient streams interact with each
other, which erases memory of the source and results in a large merged
interaction region (MIR) with a preceding shock. The MHD model predicts that
the shock and MIR would reach 120 AU around 2013 April 22, which agrees well
with the period of radio emissions and the time of a transient disturbance in
galactic cosmic rays detected by Voyager 1. These results are important for
understanding the "fate" of CMEs in the outer heliosphere and provide
confidence that the heliopause is located around 120 AU from the Sun.Comment: 13 pages, 5 figures, accepted for publication in ApJ Letter
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