39,684 research outputs found
The 2MASS Tully-Fisher Survey : Mapping the Mass in the Universe
The 2MASS Tully-Fisher Survey (2MTF) aims to measure Tully-Fisher (TF)
distances for all bright inclined spirals in the 2MASS Redshift Survey (2MRS)
using high quality HI widths and 2MASS photometry. Compared with previous
peculiar velocity surveys, the 2MTF survey provides more accurate width
measurements and more uniform sky coverage, combining observations with the
Green Bank, Arecibo and Parkes telescopes. With this new redshift-independent
distance database, we will significantly improve our understanding of the mass
distribution in the local universe.Comment: 4 pages, 3 figures, IAU Symposium 289 proceedin
Flavor symmetry breaking effects on SU(3) Skyrmion
We study the massive SU(3) Skyrmion model to investigate the flavor symmetry
breaking (FSB) effects on the static properties of the strange baryons in the
framework of the rigid rotator quantization scheme combined with the improved
Dirac quantization one. Both the chiral symmetry breaking pion mass and FSB
kinetic terms are shown to improve the ratio of the strange-light to
light-light interaction strengths and that of the strange-strange to
light-light.Comment: 12 pages, latex, no figure
Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Sections for 6Li + 208Pb System at Near-Coulomb-Barrier Energies by using Folding Potential
Based on the extended optical model approach in which the polarization
potential is decomposed into direct reaction (DR) and fusion parts,
simultaneous analyses are performed for elastic scattering and
fusion cross section data for the Li+Pb system at
near-Coulomb-barrier energies. A folding potential is used as the bare
potential. It is found that the real part of the resultant DR part of the
polarization potential is repulsive, which is consistent with the results from
the Continuum Discretized Coupled Channel (CDCC) calculations and the
normalization factors needed for the folding potentials. Further, it is found
that both DR and fusion parts of the polarization potential satisfy separately
the dispersion relation.Comment: 6 figure
Young tableaux and crystal for finite simple Lie algebras
We study the crystal base of the negative part of a quantum group. An
explicit realization of the crystal is given in terms of Young tableaux for
types , , , , and . Connection between our realization
and a previous realization of Cliff is also given
Statics and dynamics of an incommensurate spin order in a geometrically frustrated antiferromagnet CdCrO
Using elastic and inelastic neutron scattering we show that a cubic spinel,
CdCrO, undergoes an elongation along the c-axis () at its
spin-Peierls-like phase transition at = 7.8 K. The N\'{e}el phase () has an incommesurate spin structure with a characteristic wave vector
\textbf{Q} = (0,,1) with 0.09 and with spins lying on
the -plane. This is in stark contrast to another well-known Cr-based
spinel, ZnCrO, that undergoes a c-axis contraction and a commensurate
spin order. The magnetic excitations of the incommensurate N\'{e}el state has a
weak anisotropy gap of 0.6 meV and it consists of at least three bands
extending up to 5 meV.Comment: PRL in pres
Hydrodynamic Description of Granular Convection
We present a hydrodynamic model that captures the essence of granular
dynamics in a vibrating bed. We carry out the linear stability analysis and
uncover the instability mechanism that leads to the appearance of the
convective rolls via a supercritical bifurcation of a bouncing solution. We
also explicitly determine the onset of convection as a function of control
parameters and confirm our picture by numerical simulations of the continuum
equations.Comment: 14 pages, RevTex 11pages + 3 pages figures (Type csh
The radio structure of 3C 316, a galaxy with double-peaked narrow optical emission lines
The galaxy 3C\,316 is the brightest in the radio band among the
optically-selected candidates exhibiting double-peaked narrow optical emission
lines. Observations with the Very Large Array (VLA), Multi-Element Remotely
Linked Interferometer Network (e-MERLIN), and the European VLBI Network (EVN)
at 5\,GHz have been used to study the radio structure of the source in order to
determine the nature of the nuclear components and to determine the presence of
radio cores. The e-MERLIN image of 3C 316 reveals a collimated coherent
east-west emission structure with a total extent of about 3 kpc. The EVN image
shows seven discrete compact knots on an S-shaped line. However, none of these
knots could be unambiguously identified as an AGN core. The observations
suggest that the majority of the radio structure belongs to a powerful radio
AGN, whose physical size and radio spectrum classify it as a compact
steep-spectrum source. Given the complex radio structure with radio blobs and
knots, the possibility of a kpc-separation dual AGN cannot be excluded if the
secondary is either a naked core or radio quiet.Comment: 12 pages, 3 figures, 2 tables. Accepted for publication in the MNRA
Multi-pair massive MIMO relay networks: power scaling laws and user scheduling strategy
This study studies a multi-pair massive multiple-input multiple-output (MIMO) relaying network, where multiple pairs of users are served by a single relay station with a large number of antennas, and the amplify-and-forward protocol and zero-forcing (ZF) beamforming are used at the relay. The authors investigate the ergodic achievable rates for the users and obtain tight approximations in closed form for finite number of antennas. The rate performance and power efficiency are studied based on the analytical results for asymptotic scenarios, and the effect of scaling factors of transmit powers for users and relay are discussed. The closed-form expressions enable us to determine the optimal user scheduling which maximizes the ergodic sum-rate for the selected pairs. A simplified user scheduling algorithm is proposed which greatly reduces the average complexity of the optimal use pair search without any rate loss. Moreover, the complexity reduction for the proposed algorithm increases nonlinearly with the increase of the number of user pairs, which indicates that the simplified scheduling algorithm has notable advantages when the number of users is increased. The tightness for the analytical approximations and the superiority of the proposed algorithm are verified by Monte-Carlo simulation results
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