10,182 research outputs found
Torus Models of the Outer Disc of the Milky Way using LAMOST Survey Data
With a sample of 48,161 K giant stars selected from the LAMOST DR 2
catalogue, we construct torus models in a large volume extending, for the first
time, from the solar vicinity to a Galactocentric distance of kpc,
reaching the outskirts of the Galactic disc. We show that the kinematics of the
K giant stars match conventional models, e.g. as created by Binney in 2012, in
the Solar vicinity. However such two-disc models fail if they are extended to
the outer regions, even if an additional disc component is utilised. If we
loosen constraints in the Sun's vicinity, we find that an effective thick disc
model could explain the anti-centre of the MW. The LAMOST data imply that the
sizes of the Galactic discs are much larger, and that the outer disc is much
thicker, than previously thought, or alternatively that the outer structure is
not a conventional disc at all. However, the velocity dispersion
of the kinematically thick disc in the best-fitting model is about 80 km
s and has a scale parameter for an exponential distribution
function of kpc. Such a height is strongly rejected by
current measurements in the solar neighbourhood, and thus a model beyond
quasi-thermal, two or three thin or thick discs is required.Comment: 11 pages, 7 figures and 3 tables, Accepted for publication in MNRA
Jointless gene of tomato
The present invention relates to the isolation and identification of a JOINTLESS gene from a tomato plant (genus Lycopersicon). More specifically, the invention relates to novel nucleic acid molecules isolated from a tomato plant, proteins encoded by such nucleic acid molecules, and antibodies raised against such proteins. The present invention is also directed to a nucleic acid homolog of a JOINTLESS gene and a method to identify a homolog in plants other than tomato
The subordinated processes controlled by a family of subordinators and corresponding Fokker-Planck type equations
In this work, we consider subordinated processes controlled by a family of
subordinators which consist of a power function of time variable and a negative
power function of stable random variable. The effect of parameters in
the subordinators on the subordinated process is discussed. By suitable
variable substitutions and Laplace transform technique, the corresponding
fractional Fokker-Planck-type equations are derived. We also compute their mean
square displacements in a free force field. By choosing suitable ranges of
parameters, the resulting subordinated processes may be subdiffusive, normal
diffusive or superdiffusive.Comment: 11 pages, accepted by J. Stat. Mech.: Theor. Ex
A WOA-based optimization approach for task scheduling in cloud Computing systems
Task scheduling in cloud computing can directly
affect the resource usage and operational cost of a system. To
improve the efficiency of task executions in a cloud, various
metaheuristic algorithms, as well as their variations, have been
proposed to optimize the scheduling. In this work, for the
first time, we apply the latest metaheuristics WOA (the whale
optimization algorithm) for cloud task scheduling with a multiobjective optimization model, aiming at improving the performance of a cloud system with given computing resources. On that
basis, we propose an advanced approach called IWC (Improved
WOA for Cloud task scheduling) to further improve the optimal
solution search capability of the WOA-based method. We present
the detailed implementation of IWC and our simulation-based
experiments show that the proposed IWC has better convergence
speed and accuracy in searching for the optimal task scheduling
plans, compared to the current metaheuristic algorithms. Moreover, it can also achieve better performance on system resource
utilization, in the presence of both small and large-scale tasks
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