4,108 research outputs found

    A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure

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    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 Λ\LambdaCDM 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., Q1=βHρcQ_1=\beta H\rho_c and Q2=βHρdeQ_2=\beta H\rho_{de}, with β\beta being the dimensionless coupling parameter. Our focus is the IΛ\LambdaCDM model that is a one-parameter extension to Λ\LambdaCDM by considering a direct coupling between the vacuum energy (Λ\Lambda) and cold dark matter (CDM), with the only additional parameter β\beta. But we begin with a more general case by considering the IwwCDM model in which dark energy has a constant ww (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 ϵ(z)\epsilon(z) values for the models. We show that in both geometrical and structural diagnostics the impact of ww is much stronger than that of β\beta in the IwwCDM model. We thus wish to have a closer look at the IΛ\LambdaCDM model by combining the geometrical and structural diagnostics. We find that the evolutionary trajectories in the S3(1)S^{(1)}_3--ϵ\epsilon plane exhibit distinctive features and the departures from Λ\LambdaCDM could be well evaluated, theoretically, indicating that the composite null diagnostic {S3(1),ϵ}\{S^{(1)}_3, \epsilon\} 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

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    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 R3×R3\mathbb{R}^3\times\mathbb{R}^3. 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 00, 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

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    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

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    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)

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    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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