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

A Hybrid Time-Scaling Transformation for Time-Delay Optimal Control Problems

In this paper, we consider a class of nonlinear time-delay optimal control problems with canonical equality and inequality constraints. We propose a new computational approach, which combines the control parameterization technique with a hybrid time-scaling strategy, for solving this class of optimal control problems. The proposed approach involves approximating the control variables by piecewise constant functions, whose heights and switching times are decision variables to be optimized. Then, the resulting problem with varying switching times is transformed, via a new hybrid time-scaling strategy, into an equivalent problem with fixed switching times, which is much preferred for numerical computation. Our new time-scaling strategy is hybrid in the sense that it is related to two coupled time-delay systems—one defined on the original time scale, in which the switching times are variable, the other defined on the new time scale, in which the switching times are fixed. This is different from the conventional time-scaling transformation widely used in the literature, which is not applicable to systems with time-delays. To demonstrate the effectiveness of the proposed approach, we solve four numerical examples. The results show that the costs obtained by our new approach are lower, when compared with those obtained by existing optimal control methods

Improving Plant Growth and Alleviating Photosynthetic Inhibition and Oxidative Stress From Low-Light Stress With Exogenous GR24 in Tomato (Solanum lycopersicum L.) Seedlings

Low light (LL) is one of the main limiting factors that negatively affect tomato growth and yield. Techniques of chemical regulation are effective horticultural methods to improve stress resistance. Strigolactones (SLs), newly discovered phytohormones, are considered as important regulators of physiological responses. We investigated the effects of foliage spray of GR24, a synthesized SLs, on tomato seedlings grown under LL stress conditions. The results showed that application of GR24 effectively mitigated the inhibition of plant growth and increased the fresh and dry weight of tomato plants under LL. Additionally, GR24 also increased the chlorophyll content (Chla and Chlb), the net photosynthetic rate (Pn), the photochemical efficiency of photosystem (PS) II (Fv/Fm), and the effective quantum yield of PSII and I [Y(II) and Y(I)], but decreased the excitation pressure of PSII (1-qP), the non-regulatory quantum yield of energy dissipation [Y(NO)] and the donor side limitation of PSI [Y(ND)] under LL. Moreover, application of GR24 to LL-stressed tomato leaves increased the electron transport rate of PSII and PSI [ETR(II) and ETR(I)], the ratio of the quantum yield of cyclic electron flow (CEF) to Y(II) [Y(CEF)/Y(II)], the oxidized plastoquinone (PQ) pool size and the non-photochemical quenching. Besides, GR24 application increased the activity and gene expression of antioxidant enzymes, but it reduced malonaldehyde (MDA) and hydrogen peroxide (H2O2) content in LL-stressed plants. These results suggest that exogenous application of GR24 enhances plant tolerance to LL by promoting plant utilization of light energy to alleviate the photosystem injuries induced by excess light energy and ROS, and enhancing photosynthesis efficiency to improve plant growth

The Development of Spatial Attention U-Net for The Recovery of Ionospheric Measurements and The Extraction of Ionospheric Parameters

We train a deep learning artificial neural network model, Spatial Attention U-Net to recover useful ionospheric signals from noisy ionogram data measured by Hualien's Vertical Incidence Pulsed Ionospheric Radar. Our results show that the model can well identify F2 layer ordinary and extraordinary modes (F2o, F2x) and the combined signals of the E layer (ordinary and extraordinary modes and sporadic Es). The model is also capable of identifying some signals that were not labeled. The performance of the model can be significantly degraded by insufficient number of samples in the data set. From the recovered signals, we determine the critical frequencies of F2o and F2x and the intersection frequency between the two signals. The difference between the two critical frequencies is peaking at 0.63 MHz, with the uncertainty being 0.18 MHz.Comment: 17 pages, 7 figures, 3 table

Proteinlike behavior of a spin system near the transition between ferromagnet and spin glass

A simple spin system is studied as an analog for proteins. We investigate how the introduction of randomness and frustration into the system effects the designability and stability of ground state configurations. We observe that the spin system exhibits protein-like behavior in the vicinity of the transition between ferromagnet and spin glass. Our results illuminate some guiding principles in protein evolution.Comment: 12 pages, 4 figure

Chloridobis(1,10-phenanthroline)zinc(II) tetra­chlorido(1,10-phenan­throline)bis­muthate(III) monohydrate

In the crystal structure of the title monohydrate salt, [ZnCl(C12H8N2)2][BiCl4(C12H8N2)]·H2O, the ionic components are linked into three-dimensional supra­molecular channels by five pairs of C—H⋯Cl hydrogen bonds and π–π stacking inter­actions with an inter­planar distance of 3.643 (2) Å. The solvent water mol­ecules are lodged in the channels