2,922 research outputs found
Quantum state transfer from light to molecules via coherent two-color photo-association in an atomic Bose-Einstein condensate
By using a quantized input light, we theoretically revisit the coherent
two-color photo-association process in an atomic Bose-Einstein condensate.
Under the single-mode approximations, we show two interesting regimes of the
light transmission and the molecular generation. The quantum state transfer
from light to molecules is exhibited, without or with the depletion of trapped
atoms.Comment: 1 figure, accepted by Eur.Phys.J.D on Dec.15,200
Distance, Growth Factor, and Dark Energy Constraints from Photometric Baryon Acoustic Oscillation and Weak Lensing Measurements
Baryon acoustic oscillations (BAOs) and weak lensing (WL) are complementary
probes of cosmology. We explore the distance and growth factor measurements
from photometric BAO and WL techniques and investigate the roles of the
distance and growth factor in constraining dark energy. We find for WL that the
growth factor has a great impact on dark energy constraints but is much less
powerful than the distance. Dark energy constraints from WL are concentrated in
considerably fewer distance eigenmodes than those from BAO, with the largest
contributions from modes that are sensitive to the absolute distance. Both
techniques have some well determined distance eigenmodes that are not very
sensitive to the dark energy equation of state parameters w_0 and w_a,
suggesting that they can accommodate additional parameters for dark energy and
for the control of systematic uncertainties. A joint analysis of BAO and WL is
far more powerful than either technique alone, and the resulting constraints on
the distance and growth factor will be useful for distinguishing dark energy
and modified gravity models. The Large Synoptic Survey Telescope (LSST) will
yield both WL and angular BAO over a sample of several billion galaxies. Joint
LSST BAO and WL can yield 0.5% level precision on ten comoving distances evenly
spaced in log(1+z) between redshift 0.3 and 3 with cosmic microwave background
priors from Planck. In addition, since the angular diameter distance, which
directly affects the observables, is linked to the comoving distance solely by
the curvature radius in the Friedmann-Robertson-Walker metric solution, LSST
can achieve a pure metric constraint of 0.017 on the mean curvature parameter
Omega_k of the universe simultaneously with the constraints on the comoving
distances.Comment: 15 pages, 9 figures, details and references added, ApJ accepte
Government Regulation of Online Game Addiction
While the Internet has changed the world with online knowledge, communication, and collaboration, it has also introduced online addiction. Online game addiction can be severe with tragic outcomes. Most governments and organizations are yet to recognize the severity of online game addiction and the need for intervention. We briefly review the literature on online game addiction. We also summarize the limited attempts of governments to develop regulations aimed at preventing online game addiction. Special attention is paid to China and its efforts to reduce the number of hours that young people can play online. We present evidence suggesting that online game addiction is an issue that should be considered by governments everywhere and that information systems researchers can play an important role in analyzing the impacts of government regulation of online addiction and shaping regulation improvements
Coupled atomic-molecular condensates in a double-well potential: decaying molecular oscillations
We present a four-mode model that describes coherent photo-association (PA)
in a double-well Bose-Einstein condensate, focusing on the molecular
populations in certain parameters. Our numerical results predict an interesting
strong-damping effect of molecular oscillations by controlling the particle
tunnellings and PA light strength, which may provide a promising way for
creating a stable molecular condensate via coherent PA in a magnetic
double-well potential.Comment: 6 pages, 4 figures, submitte
Deadline Constrained Cloud Computing Resources Scheduling through an Ant Colony System Approach
Cloud computing resources scheduling is essential for executing workflows in the cloud platform because it relates to both execution time and execution cost. In this paper, we adopt a model that optimizes the execution cost while meeting deadline constraints. In solving this problem, we propose an Improved Ant Colony System (IACS) approach featuring two novel strategies. Firstly, a dynamic heuristic strategy is used to calculate a heuristic value during an evolutionary process by taking the workflow topological structure into consideration. Secondly, a double search strategy is used to initialize the pheromone and calculate the heuristic value according to the execution time at the beginning and to initialize the pheromone and calculate heuristic value according to the execution cost after a feasible solution is found. Therefore, the proposed IACS is adaptive to the search environment and to different objectives. We have conducted extensive experiments based on workflows with different scales and different cloud resources. We compare the result with a particle swarm optimization (PSO) approach and a dynamic objective genetic algorithm (DOGA) approach. Experimental results show that IACS is able to find better solutions with a lower cost than both PSO and DOGA do on various scheduling scales and deadline conditions
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