105,110 research outputs found
Microscopic Description of Band Structure at Very Extended Shapes in the A ~ 110 Mass Region
Recent experiments have confirmed the existence of rotational bands in the A
\~ 110 mass region with very extended shapes lying between super- and
hyper-deformation. Using the projected shell model, we make a first attempt to
describe quantitatively such a band structure in 108Cd. Excellent agreement is
achieved in the dynamic moment of inertia J(2) calculation. This allows us to
suggest the spin values for the energy levels, which are experimentally
unknown. It is found that at this large deformation, the sharply down-sloping
orbitals in the proton i_{13/2} subshell are responsible for the irregularity
in the experimental J(2), and the wave functions of the observed states have a
dominant component of two-quasiparticles from these orbitals. Measurement of
transition quadrupole moments and g-factors will test these findings, and thus
can provide a deeper understanding of the band structure at very extended
shapes.Comment: 4 pages, 3 eps figures, final version accepted by Phys. Rev. C as a
Rapid Communicatio
Coronal magnetic topology and the production of solar impulsive energetic electrons
We investigate two candidate solar sources or active regions (ARs) in
association with a solar impulsive energetic electron (SIEE) event on 2002
October 20. The solar particle release (SPR) times of SIEEs are derived by
using their velocity dispersion with consideration of the instrumental effect.
It is found that there are double electron injections at the Sun. The
low-energy (<13 keV) electron injection coincides with a C6.6 flare in AR10154
and is accompanied with prominent type III radio bursts rather than a stronger
M1.8 flare in AR10160. The M1.8 flare produces, however, faint type III radio
bursts. Whereas electrons of 25 to 300 keV are released 9 min later when a
jet-like CME travels to 2.6 solar radii. We further examine the coronal
magnetic configurations above the two ARs based on the potential field source
surface (PFSS) model. It is found that open field lines, rooted in AR10154 and
well connected to the Earth, provide escaping channels for energetic electrons.
Only a small portion of magnetic fields are opened above AR10160, being
responsible for the faint type III radio bursts. These lines are, however, not
well connected, making it impossible for SIEEs detection by near-Earth
spacecraft. The results appear to establish a physical link between coronal
magnetic topology, formation of type III radio bursts, and production of SIEEs.Comment: A&A Letters, accepte
Melham's Conjecture on Odd Power Sums of Fibonacci Numbers
Ozeki and Prodinger showed that the odd power sum of the first several
consecutive Fibonacci numbers of even order is equal to a polynomial evaluated
at certain Fibonacci number of odd order. We prove that this polynomial and its
derivative both vanish at , and will be an integer polynomial after
multiplying it by a product of the first consecutive Lucas numbers of odd
order. This presents an affirmative answer to a conjecture of Melham.Comment: 15page
Enumeration of Corners in Tree-like Tableaux
In this paper, we confirm conjectures of Laborde-Zubieta on the enumeration
of corners in tree-like tableaux and in symmetric tree-like tableaux. In the
process, we also enumerate corners in (type ) permutation tableaux and
(symmetric) alternative tableaux. The proof is based on Corteel and Nadeau's
bijection between permutation tableaux and permutations. It allows us to
interpret the number of corners as a statistic over permutations that is easier
to count. The type case uses the bijection of Corteel and Kim between type
permutation tableaux and signed permutations. Moreover, we give a bijection
between corners and runs of size 1 in permutations, which gives an alternative
proof of the enumeration of corners. Finally, we introduce conjectural
polynomial analogues of these enumerations, and explain the implications on the
PASEP.Comment: 26 pages, 11 figures. This is the final version for publicatio
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