2,475 research outputs found
Integrable models of galactic discs with double nuclei
We introduce a new class of 2-D mass models, whose potentials are of
St\"ackel form in elliptic coordinates. Our model galaxies have two separate
strong cusps that form double nuclei. The potential and surface density
distributions are locally axisymmetric near the nuclei and become {\it highly}
non-axisymmetric outside the nucleus. The surface density diverges toward the
cuspy nuclei with the law . Our model is sustained by
four general types of regular orbits: {\it butterfly}, {\it nucleuphilic
banana}, {\it horseshoe} and {\it aligned loop} orbits. Horseshoes and
nucleuphilic bananas support the existence of cuspy regions. Butterflies and
aligned loops control the non-axisymmetric shape of outer regions. Without any
need for central black holes, our distributed mass models resemble the nuclei
of M31 and NGC4486B. It is also shown that the self-gravity of the stellar disc
can prevent the double nucleus to collapse.Comment: 8 pages, accepted for publication in MNRA
Local Normal Mode Coupling and Energy Band Splitting in Elliptically Birefringent 1D Magnetophotonic Crystals
An analysis is presented of wave-vector dispersion in elliptically
birefringent stratified magneto-optic media having one-dimensional periodicity.
It is found that local normal-mode polarization-state differences between
adjacent layers lead to mode coupling and impact the wave-vector dispersion and
the character of the Bloch states of the system. This coupling produces extra
terms in the dispersion relation not present in uniform circularly birefringent
magneto-optic stratified media. Normal mode coupling lifts the degeneracy at
frequency band cross-over points under certain conditions and induces a
magnetization-dependent optical band gap. This study examines the conditions
for band gap formation in the system. It shows that such a frequency-split can
be characterized by a simple coupling parameter that depends on the relation
between polarization states of local normal modes in adjacent layers. The
character of the Bloch states and conditions for maximizing the strength of the
band splitting in these systems are analyzed.Comment: 15 pages, 4 figure
The Child is Father of the Man: Foresee the Success at the Early Stage
Understanding the dynamic mechanisms that drive the high-impact scientific
work (e.g., research papers, patents) is a long-debated research topic and has
many important implications, ranging from personal career development and
recruitment search, to the jurisdiction of research resources. Recent advances
in characterizing and modeling scientific success have made it possible to
forecast the long-term impact of scientific work, where data mining techniques,
supervised learning in particular, play an essential role. Despite much
progress, several key algorithmic challenges in relation to predicting
long-term scientific impact have largely remained open. In this paper, we
propose a joint predictive model to forecast the long-term scientific impact at
the early stage, which simultaneously addresses a number of these open
challenges, including the scholarly feature design, the non-linearity, the
domain-heterogeneity and dynamics. In particular, we formulate it as a
regularized optimization problem and propose effective and scalable algorithms
to solve it. We perform extensive empirical evaluations on large, real
scholarly data sets to validate the effectiveness and the efficiency of our
method.Comment: Correct some typos in our KDD pape
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