7,863 research outputs found
A Maxwell-vector p-wave holographic superconductor in a particular background AdS black hole metric
We study the p-wave holographic superconductor for AdS black holes with
planar event horizon topology for a particular Lovelock gravity, in which the
action is characterized by a self-interacting scalar field nonminimally coupled
to the gravity theory which is labeled by an integer . As the Lovelock
theory of gravity is the most general metric theory of gravity based on the
fundamental assumptions of general relativity, it is a desirable theory to
describe the higher dimensional spacetime geometry. The present work is devoted
to studying the properties of the p-wave holographic superconductor by
including a Maxwell field which nonminimally couples to a complex vector field
in a higher dimensional background metric. In the probe limit, we find that the
critical temperature decreases with the increase of the index of the
background black hole metric, which shows that a larger makes it harder for
the condensation to form. We also observe that the index affects the
conductivity and the gap frequency of the holographic superconductors.Comment: 14 pages, 6 figure
p-wave holographic superconductor in scalar hairy black holes
We study the properties of the p-wave holographic superconductor for the
scalar hairy black holes in the probe limit. The black hole solutions in
question possess planar topology, which are derived from the Einstein gravity
theory minimally coupled to a scalar field with a generic scalar potential.
These solutions can be viewed as characterized by two independent parameters,
namely, and , where AdS vacuum is manifestly restored when
. Consequently, the p-wave holographic superconductor is
investigated by employing the above static planar black hole spacetime as the
background metric, where a Maxwell field is introduced to the model by
nonminimally coupling it to a complex vector field. The latter is shown to
condensate and furnish the superconducting phase when the temperature is below
a critical value. By numerical calculations, we examine in detail how the
scalar field in the background affects the properties of the superconductivity.
It is found that the critical temperature depends crucially on the parameters
and , which subsequently affects the condensation process. By
employing the Kubo formula, the real, as well as imaginary parts of the
conductivity, are calculated and presented as functions of frequency. The
results are discussed regarding the poles of the Green function, and the
typical values of the BCS theory.Comment: 15 pages, 6 figure
Prevalence of internet addiction disorder in Chinese university students: A comprehensive meta-analysis of observational studies
Background and aims: Internet addiction disorder (IAD) is common in university students. A number of studies have examined the prevalence of IAD in Chinese university students, but the results have been inconsistent. This is a meta-analysis of the prevalence of IAD and its associated factors in Chinese university students.
Methods: Both English (PubMed, PsycINFO, and Embase) and Chinese (Wan Fang Database and Chinese National Knowledge Infrastructure) databases were systematically and independently searched from their inception until January 16, 2017.
Results: Altogether 70 studies covering 122,454 university students were included in the meta-analysis. Using the random-effects model, the pooled overall prevalence of IAD was 11.3% (95% CI: 10.1%–12.5%). When using the 8-item Young Diagnostic Questionnaire, the 10-item modified Young Diagnostic Questionnaire, the 20-item Internet Addiction Test, and the 26-item Chen Internet Addiction Scale, the pooled prevalence of IAD was 8.4% (95% CI: 6.7%–10.4%), 9.3% (95% CI: 7.6%–11.4%), 11.2% (95% CI: 8.8%–14.3%), and 14.0% (95% CI: 10.6%–18.4%), respectively. Subgroup analyses revealed that the pooled prevalence of IAD was significantly associated with the measurement instrument (Q = 9.41, p = .024). Male gender, higher grade, and urban abode were also significantly associated with IAD. The prevalence of IAD was also higher in eastern and central of China than in its northern and western regions (10.7% vs. 8.1%, Q = 4.90, p = .027).
Conclusions: IAD is common among Chinese university students. Appropriate strategies for the prevention and treatment of IAD in this population need greater attention
Phosphorous Diffuser Diverged Blue Laser Diode for Indoor Lighting and Communication.
An advanced light-fidelity (Li-Fi) system based on the blue Gallium nitride (GaN) laser diode (LD) with a compact white-light phosphorous diffuser is demonstrated for fusing the indoor white-lighting and visible light communication (VLC). The phosphorous diffuser adhered blue GaN LD broadens luminescent spectrum and diverges beam spot to provide ample functionality including the completeness of Li-Fi feature and the quality of white-lighting. The phosphorous diffuser diverged white-light spot covers a radiant angle up to 120(o) with CIE coordinates of (0.34, 0.37). On the other hand, the degradation on throughput frequency response of the blue LD is mainly attributed to the self-feedback caused by the reflection from the phosphor-air interface. It represents the current state-of-the-art performance on carrying 5.2-Gbit/s orthogonal frequency-division multiplexed 16-quadrature-amplitude modulation (16-QAM OFDM) data with a bit error rate (BER) of 3.1 × 10(-3) over a 60-cm free-space link. This work aims to explore the plausibility of the phosphorous diffuser diverged blue GaN LD for future hybrid white-lighting and VLC systems
Nuciferine downregulates Per-Arnt-Sim kinase expression during its alleviation of lipogenesis and inflammation on oleic acid-induced hepatic steatosis in HepG2 cells
Nonalcoholic fatty liver disease (NAFLD) is a prevalent liver disease associated with lipotoxicity, lipid peroxidation, oxidative stress and inflammation. Nuciferine, an active ingredient extracted from the natural lotus leaf, has been reported to be effective for the prevention and treatment of NAFLD. Per-Arnt-Sim kinase (PASK) is a nutrient responsive protein kinase that regulates lipid and glucose metabolism, mitochondrial respiration and gene expression. The aim of the present study was to investigate the protective effect of nuciferine against NAFLD and its inhibitory effect on PASK, exploring the possible underlying mechanism of nuciferine-mediated inhibition on NAFLD. Relevant biochemical parameters (lipid accumulation, extent of oxidative stress and release of inflammation cytokines) in oleic acid (OA)-induced HepG2 cells that mimicked steatosis in vitro were measured and compared with the control. It was found that nuciferine and silenced-PASK (siRNA PASK) both inhibited triglyceride (TG) accumulation and was effective in decreasing fatty acid (FFAs). The content of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) were increased respectively by nuciferine and siRNA PASK without increase in glutathione (GSH). Malondialdehyde (MDA) was decreased respectively by nuciferine and siRNA PASK. In addition, nuciferine decreased TNF-a, IL-6 and IL-8 as well as the siRNA PASK group. IL-10 was increased by nuciferine and siRNA PASK respectively. Further investigation revealed that nuciferine and siRNA PASK could respectively regulate the expression of target genes involved in lipogenesis and inflammation, suggesting that nuciferine may be a potential therapeutic treatment for NAFLD. Furthermore, the modulated effect of nuciferine on (OA)-induced HepG2 cells lipogenesis and inflammation, which was accompanied with PASK inhibition, was also consistent with siRNA PASK, implying that PASK might play a role in nuciferine-mediated regulation on NAFLD
Why are the Performances of Business Groups Different? A Case Study of Formosa Plastics Group and Far Eastern Group
This study examines the difference in performances of two business groups, Formosa Plastics Group and Far Eastern Group, under the impact of financial tsunami (2007.10.29~2017.8.10). The aim of this study is to help investors understand the operating model of business groups and use the herding effect to enhance the trading performance in financial markets. The empirical evidence shows that for the Formosa Plastics Group, the news impact curve (based on EGARCH model) including the leading company is flatter when the news impact is less than zero (that is, negative news impact) than the news impact curve excluding the leading company. In contrast, the news impact curve of the Far Eastern Group is steeper when the leading company is included. Moreover, when the leading company is included as an endogeneous variable in the model as a filter for the program trading simulation, results show that investors can profit from the Formosa Plastics Group. Therefore, business groups that include the leading company have lower risks. It is beneficial to the stability of the market trading by incorporating the leverage effect of the leading company in business groups. On the contrary, the leading company of the Far Eastern Group does not have such an effect. The absolute profits and the increment of performance are both lower than that of the Formosa Plastics Group. The results suggest that the diversification strategy of Far Eastern Group is worse than the vertical integration strategy of the Formosa Plastics Group. The implication is that investors should carefully choose the business group for investment if they are to utilize the herding effect in investment
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