4,108 research outputs found
A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure
We investigate the interacting dark energy models by using the diagnostics of
statefinder hierarchy and growth rate of structure. We wish to explore the
deviations from CDM and to differentiate possible degeneracies in the
interacting dark energy models with the geometrical and structure growth
diagnostics. We consider two interacting forms for the models, i.e., and , with being the dimensionless
coupling parameter. Our focus is the ICDM model that is a
one-parameter extension to CDM by considering a direct coupling
between the vacuum energy () and cold dark matter (CDM), with the only
additional parameter . But we begin with a more general case by
considering the ICDM model in which dark energy has a constant
(equation-of-state parameter). For calculating the growth rate of structure, we
employ the "parametrized post-Friedmann" theoretical framework for interacting
dark energy to numerically obtain the values for the models. We
show that in both geometrical and structural diagnostics the impact of is
much stronger than that of in the ICDM model. We thus wish to have a
closer look at the ICDM model by combining the geometrical and
structural diagnostics. We find that the evolutionary trajectories in the
-- plane exhibit distinctive features and the departures
from CDM could be well evaluated, theoretically, indicating that the
composite null diagnostic is a promising tool for
investigating the interacting dark energy models.Comment: 17 pages, 4 figures; accepted for publication in JCA
Exponential Stability of the Inhomogeneous Navier-Stokes-Vlasov System in Vacuum
The main purpose of the present paper is to study the influence of the vacuum
on the asymptotic behaviors of solutions to the inhomogeneous
Navier-Stokes-Vlasov system in . To this end,
we establish the uniform bound of the macroscopic density associated with the
distribution function and prove the global existence and uniqueness of strong
solutions to the Cauchy problem with vacuum for either small initial energy or
large viscosity coefficient. The uniform boundedness and the presence of vacuum
enable us to show that as the time evolves, the fluid velocity decays, while
the distribution function concentrates towards a Dirac measure in velocity
centred at , with an exponential rate
The Influence of Augmented Reality Technology on the Learning Interest, Achievement of Learning Goals and Cognitive Load of Middle School Students
In order to test the influence of augmented reality technology on the learning interest achievement of learning goals and cognitive load the instruction of topographic map was taken as an example for experimental study This paper selected 427 students from 8 classes of Grade one who all come from Zhantan Middle School in Xindu District of Chengdu as experimental samples set two classes with similar level in learning as one group the one is the experimental class and the other is the control class and formed 4 groups in total The experimental classes adopted AR three-dimensional videos as teaching aids to give new lessons and the control classes adopted traditional two- dimensional videos and then the students learning interest level achievement of learning goals and cognitive load were measured The results showed that the application of AR technology in teaching could improve students learning interest and achievement of learning goals but had no effect on reducing cognitive loa
FIRM CELEBRITY, REPUTATION AND PERFORMANCE: A SOCIAL MEDIA PERSPECTIVE
Firm celebrity and reputation are considered as valuable intangible resources leading to competitive advantages. Past research usually uses indirect measures, such as Fortune ratings or questionnaire surveys to examine the relationship between celebrity and reputation with firm financial performance. The follow-ship on microblogging services, such as Twitter, provides us an opportunity to measure the two assets directly. Constructing firm celebrity as the number of followers a firm has and firm eputation as the PageRank score of the firm, we discovered that both reputation and celebrity derived from social media have shown negative effects on firms\u27 return on assets, but have positive relationships with market capitalization. This is to say, despite of their relative inabilities to generate profits, the management of firms with high reputation and level of celebrity achieved higher market values, which is one of the most important goals for all companies. Furthermore, we also compared the different effects between reputation and celebrity on firm financial performance. The results showed that the level of celebrity has a stronger positive relation with market capitalization than firm reputation. On the other hand, firm reputation has a stronger impact on cost of goods sold than celebrity
Aquachlorido{1-[1-(4-hydroxyphenyl)-1H-tetrazol-5-ylsulfanyl]acetato}(methanol)(1,10-phenanthroline)manganese(II)
The title complex, [Mn(C9H7N4O3S)Cl(C12H8N2)(CH4O)(H2O)], contains an MnII ion six-coordinated by one O atom from the 2-[1-(4-hydroxyphenyl)-1H-tetrazol-5-ylsulfanyl]acetate ligand, two N atoms from a chelating 1,10-phenanthroline ligand, one O atom from a methanol molecule, one Cl atom and one water molecule in a distorted octahedral coordination geometry. The existence of O—H⋯Cl, O—H⋯N and O—H⋯O hydrogen bonds further produces a two-dimensional structure
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