Self-harm and drinking are both serious problems in adolescents and many studies presented evidence of their association. However, gender differences in this association are seldom deeply discussed. ...Our study aimed to evaluate the prevalence of self-harm and explore its association with drinking behaviors by gender and investigate the extent to which the gender differences exist in the association between self-harm and drinking.
A total of 32,362 students in grades 7 to 12 in Beijing, China were anonymously surveyed and included in our study using two-stage, stratified probability proportion sampling. Self-harm, drinking behaviors and other basic information were obtained from an anonymous questionnaire. Demographic variables, self-harm and drinking behaviors were analyzed using the Chi-square test and the Gamma test between genders and the gender differences in this association were analyzed by Log-binomial regression.
The total prevalence of self-harm was 13.7% with no significant gender difference (χ
=0.352, P = 0.553). The prevalence of self-harm in girls decreased with age (G = -0.163, P < 0.001). Self-harm was associated with drinking behaviors in both boys and girls. The Log-binomial regression demonstrated that girls in the 16-19 years old group were at lower risk of self-harm than girls in the 12-15 years old group while this association was weaker in boys (1.493 vs 1.128). The higher OR for self-harm was found among girls with early drinking experiences compared with boys (2.565 vs 1.863). Girls who had previously drunk (i.e. drunk at least once) (2.211 vs 1.636), were currently drinking (3.400 vs 2.122) and performed binge drinking (6.357 vs 3.924) were at greater risk of self-harm than boys.
Among high school students, self-harm has a significant positive association with drinking and girls with drinking behaviors are at higher risk of suffering self-harm. Identifying adolescents' drinking behaviors is of vital importance to self-harm prevention and special attention should be focused on younger girls.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We propose a new hollow ring core silica photonic crystal fiber that can support 101 orbital angular momentum (OAM) modes, maintaining a high mode quality without phase distortion, a low confinement ...loss, and a large effective index difference between the adjacent modes, which could open a new avenue of OAM mode multiplexing applications. The fiber consists of three layers: the circular central air hole, silica ring core, and circumferencing silica-air hole porous inner cladding. Using the full-vectorial finite element method (FEM), the modal characteristics of individual OAM modes in the proposed fiber were thoroughly analyzed by varying the number of air-holes in the circularly symmetric cladding. We found a general selection rule for the number of air-holes in the first layer and the topological charge to cause the phase distortion of OAM modes, for the first time. The phase distribution of the guided OAM modes was thoroughly investigated to select usable modes for mode division multiplexing. Parametric analyses of the proposed PCF are reported to optimize optical properties of the OAM modes.
A new directional bending sensor based on a dual side-hole fiber (DSHF) that can detect both the direction and magnitude of bending in a self-temperature compensated manner is described and ...experimentally demonstrated. The sensor is based on an in-fiber Mach-Zehnder interferometer (MZI), where a DSHF segment was spliced between two standard single-mode fibers (SMFs) as input and output. The sensor has two orthogonal axes which are formed by both the asymmetry in the side-hole location in DSHF and an offset in the fusion splice between the SMF and DSHF. The visibility in the MZI output intensity and the spectral shifts of MZI fringes show separate responses to the bending curvature and direction, which is a key feature of the directional curvature sensor. An inscribed fiber Bragg grating in the DSHF measure allows the temperature to be measured independently. The sensor can provide salient advantages in its unique capability to precisely quantify the direction and magnitude of bending along with its reproducibility, compactness, and suitability for mass production, which makes it suitable for many practical bending sensing applications.
An ultrabroadband near-infrared (NIR) emission of Ni2+ is demonstrated in a highly transparent nanoglass ceramic (nano-GC) containing Ga2O3 nanocrystals with an 808 nm excitation of Nd3+. It is also ...shown that by adding Yb3+ as an energy-transfer (ET) bridge, the Ni2+ emission could be substantially enhanced. The dopant distribution was studied using advanced analytical transmission electron microscopy. This, together with optical transmission measurements and steady-state and time-resolved emission spectra, is utilized to understand the underlying ET mechanisms between Nd3+, Yb3+, and Ni2+. The feasibility of this device as a viable source is demonstrated using dual-laser pumping at 808 and 980 nm for the greatest Ni2+ emission enhancement reported to date. The Nd3+/Yb3+/Ni2+ triply doped nano-GC offers a promising gain medium for broadband and tunable NIR fiber amplifiers.
The spectral characteristics of the relative intensity noise (RIN) of two amplified spontaneous emission (ASE) sources are experimentally measured. An Er-doped fiber superfluorescent source (EDF-SFS) ...is investigated and compared with a super-luminescent diode (SLD) source, using a simple tunable fiber Bragg grating filter-based system. Experimental results based on normal ASE operation conditions showed that the RIN distribution of the EDF-SFS is correlated with its emission spectral profile, which is different from the results observed using the SLD source. This finding shows for the first time that an EDF-SFS based ASE has fundamentally different RIN characteristics from other known existing spontaneous emission broadband sources. The amplifying process of the EDF-SFS is discussed and confirmed using a rate equation-based simulation.
In this study, a new simulation method is proposed and verified for fiber Bragg grating patterned on polarization maintaining fiber(PM-FBG) using the transfer matrix approach. The method is designed ...to solve the twisted PM-FBG simulation. The four mode matrix element of a period grating is derived from the S matrix element and the method only involves the torsion-induced shear strain entry exy which can be considered as the rotation of the principal axis of the polarization maintaining fiber and ignores the torsion-induced shear strain entries exz and eyz. The validity of the method is confirmed by numerical simulation of the twisted PM-FBG. The novel method provides the ability to analyze any type of PM-FBG.
A novel and simple overlap-splicing-based scheme is described to realize a shape-controllable Fabry-Perot cavity in a fiber bragg grating (FBG). A Gaussian function with a constant waist width is ...used to fit the cavity shape and its maximum value is decided by the overlap value. Non-uniform strain distribution along the FBG is introduced by the Gaussian shape cavity when stress is applied on the FBG. Using this method, it is possible to optimize the discrimination capability of the strain and temperature response of the FBG device. Experimental and simulation results are provided to support the feasibility of this method.
A regenerated fiber Bragg grating (RFBG) in silica fiber was used to observe the viscous relaxation process of the host silica fiber at high temperatures of around 1000 °C. Two factors, preannealing ...time and loaded tension, which affect viscous relaxation, were observed. When an RFBG is stretched after a longer preannealing, the measured viscosity of the optical fiber was observed to reach equilibrium faster, which means that preannealing accelerates viscous relaxation. A similar acceleration phenomenon was also observed when a larger load was applied to stretch the optical fiber, although the acceleration effect of loaded tension was not as strong as in the preannealing case. The results play an active role in establishing effective optical-fiber devices for application in high-temperature environments.
One new cyclonerane sesquiterpene, 9,11-cycloneren-3,7-diol (1), along with four known ones, 11-cycloneren-3,7,10-triol (2), 9-cycloneren-3,7,11-triol (3), 11-methoxy-9-cycloneren-3,7-diol (4), and ...cyclonerodiol (5), were obtained from the extract of marine-derived fungus Trichoderma harzianum WH-22. The structure of 9,11-cycloneren-3,7-diol (1) was elucidated by comprehensive spectroscopic analysis, including 1D/2D NMR and HRESIMS data. 9,11-Cycloneren-3,7-diol (1) exhibited weak cytotoxicity against HeLa and HepG2 cancer cell lines with IC50 values of 68.2 and 59.7 μM, respectively.
An adaptive fuzzy sliding mode strategy is developed for the generalized projective synchronization of a fractional- order chaotic system, where the slave system is not necessarily known in advance. ...Based on the designed adaptive update laws and the linear feedback method, the adaptive fuzzy sliding controllers are proposed via the fuzzy design, and the strength of the designed controllers can he adaptively adjusted according to the external disturbances. Based on the Lya- punov stability theorem, the stability and the robustness of the controlled system are proved theoretically. Numerical simu- lations further support the theoretical results of the paper and demonstrate the efficiency of the proposed method. Moreover, it is revealed that the proposed method allows us to manipulate arbitrarily the response dynamics of the slave system by adjusting the desired scaling factor λi and the desired translating factor ηi, which may be used in a channel-independent chaotic secure communication.
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