The primary objective of this investigation was to scrutinize the prepregnancy conditions and lifestyles of 2046 women residing in Liuzhou City, with the aim of delineating the determinants of delivery methods. Eviden...The primary objective of this investigation was to scrutinize the prepregnancy conditions and lifestyles of 2046 women residing in Liuzhou City, with the aim of delineating the determinants of delivery methods. Evidently, the study unearthed substantial correlations between prepregnancy body mass index, educational attainment, exposure to passive smoking, medical history, and other variables with the mode of delivery. Furthermore, a predictive nomogram model was formulated to accurately forecast the likelihood of cesarean section. These discernments equip pertinent authorities with the means to institute targeted screening and supportive measures for women contemplating pregnancy based on these identified factors. Moreover, provision of services such as prepregnancy counseling and clinical risk assessments could be instrumental in curbing the incidence of cesarean section.展开更多
In China,the vertical coordination development mode of agricultural products can be divided into traditional market-oriented transaction mode with fluctuation according to market conditions,made-to-order on the basis ...In China,the vertical coordination development mode of agricultural products can be divided into traditional market-oriented transaction mode with fluctuation according to market conditions,made-to-order on the basis of farmer organization,company leading cooperative mode,share or shareholding cooperative mode,and vertical integration mode. There are differences in coordination characteristics,advantages and disadvantages,and adaptability between different modes. Traditional vertical coordination mode is transforming and upgrading to close and high-efficient mode. In this process,it is influenced by factors such as cost-benefit balance between farmers and agricultural product processing enterprises,special use of agricultural product processing,structure of agricultural product industry chain,and action of local government.展开更多
The properties of the ionosphere Alfvén resonator (IAR) in the general case of an oblique geomagnetic field are investigated. The modes at the frequencies f = 0.2 - 10 Hz well localized within the ionosphere are ...The properties of the ionosphere Alfvén resonator (IAR) in the general case of an oblique geomagnetic field are investigated. The modes at the frequencies f = 0.2 - 10 Hz well localized within the ionosphere are considered, which are important for the lithosphere—ionosphere coupling. An attention is paid to the modes with quite high quality factors , where . A proper selection of calculated eigenfrequencies has been realized. Two independent simulation algorithms have been proposed. The resonant frequencies and the profiles of magnetic field components of the modes have been calculated. The modulation of electron and ion concentrations at the heights 170 - 230 km leads to essential shifting the resonant frequencies.展开更多
We have investigated the transverse mode pattern and the optical field confinement factor of gallium nitride （GaN） laser diodes （LDs） theoretically. For the particular LD structure, composed of approximate 4 μm t...We have investigated the transverse mode pattern and the optical field confinement factor of gallium nitride （GaN） laser diodes （LDs） theoretically. For the particular LD structure, composed of approximate 4 μm thick n-GaN substrate layer, the maximum optical confinement factor was found to be corresponding to the 5^th order transverse mode, the so-called lasing mode. Moreover, the value of the maximum confinement factor varies periodically when increasing the n-side GaN layer thickness, which simultaneously changes and increases the oscillation mode order of the GaN LD caused by the effects of mode coupling. The effects of the thickness and the average composition of Al in the AlGaN/GaN superlat.tice on the optical confinement factor are also presented. Finally, the mode coupling and optimization of the layers in the GaN-based LD are discussed.展开更多
A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input volta...A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.展开更多
A novel evaluation term and a more reasonable criterion,which is described by a new parameter of brightness factor for active large mode area fiber design,are presented.The brightness factor evaluation method is based...A novel evaluation term and a more reasonable criterion,which is described by a new parameter of brightness factor for active large mode area fiber design,are presented.The brightness factor evaluation method is based on the transverse mode competition mechanism in fiber lasers and amplifiers.The brightness factor can be seen as a description of fiber general property since it can represent the output laser brightness of the fiber laser system and because of its ability to resist the nonlinear effect.A core-doped active large pitch fiber with a core diameter of 190 μm and a mode-field diameter of180 μm is designed by this method,and the designed fiber allows effective single-mode operation.展开更多
Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is...Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far field uniform uniaxial tensile or compressive stress.展开更多
文摘The primary objective of this investigation was to scrutinize the prepregnancy conditions and lifestyles of 2046 women residing in Liuzhou City, with the aim of delineating the determinants of delivery methods. Evidently, the study unearthed substantial correlations between prepregnancy body mass index, educational attainment, exposure to passive smoking, medical history, and other variables with the mode of delivery. Furthermore, a predictive nomogram model was formulated to accurately forecast the likelihood of cesarean section. These discernments equip pertinent authorities with the means to institute targeted screening and supportive measures for women contemplating pregnancy based on these identified factors. Moreover, provision of services such as prepregnancy counseling and clinical risk assessments could be instrumental in curbing the incidence of cesarean section.
基金Supported by Youth Project of Chinese National Social Science Fund(13CGL086)
文摘In China,the vertical coordination development mode of agricultural products can be divided into traditional market-oriented transaction mode with fluctuation according to market conditions,made-to-order on the basis of farmer organization,company leading cooperative mode,share or shareholding cooperative mode,and vertical integration mode. There are differences in coordination characteristics,advantages and disadvantages,and adaptability between different modes. Traditional vertical coordination mode is transforming and upgrading to close and high-efficient mode. In this process,it is influenced by factors such as cost-benefit balance between farmers and agricultural product processing enterprises,special use of agricultural product processing,structure of agricultural product industry chain,and action of local government.
文摘The properties of the ionosphere Alfvén resonator (IAR) in the general case of an oblique geomagnetic field are investigated. The modes at the frequencies f = 0.2 - 10 Hz well localized within the ionosphere are considered, which are important for the lithosphere—ionosphere coupling. An attention is paid to the modes with quite high quality factors , where . A proper selection of calculated eigenfrequencies has been realized. Two independent simulation algorithms have been proposed. The resonant frequencies and the profiles of magnetic field components of the modes have been calculated. The modulation of electron and ion concentrations at the heights 170 - 230 km leads to essential shifting the resonant frequencies.
基金Project supported by the Wang Faculty Fellowship at Peking University,Beijing,China,2006-2007 through California State University (CSU) International Programs USAthe National Basic Research Program of China (Grant No 2007CB307004)+1 种基金the National High Technology Research and Development Program of China (Grant No 2006AA03A113)the National Natural Science Foundation of China (Grant Nos 60276034,60577030 and 60607003)
文摘We have investigated the transverse mode pattern and the optical field confinement factor of gallium nitride （GaN） laser diodes （LDs） theoretically. For the particular LD structure, composed of approximate 4 μm thick n-GaN substrate layer, the maximum optical confinement factor was found to be corresponding to the 5^th order transverse mode, the so-called lasing mode. Moreover, the value of the maximum confinement factor varies periodically when increasing the n-side GaN layer thickness, which simultaneously changes and increases the oscillation mode order of the GaN LD caused by the effects of mode coupling. The effects of the thickness and the average composition of Al in the AlGaN/GaN superlat.tice on the optical confinement factor are also presented. Finally, the mode coupling and optimization of the layers in the GaN-based LD are discussed.
文摘A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.
基金supported by the National Natural Science Foundation of China(Grant No.61475081)
文摘A novel evaluation term and a more reasonable criterion,which is described by a new parameter of brightness factor for active large mode area fiber design,are presented.The brightness factor evaluation method is based on the transverse mode competition mechanism in fiber lasers and amplifiers.The brightness factor can be seen as a description of fiber general property since it can represent the output laser brightness of the fiber laser system and because of its ability to resist the nonlinear effect.A core-doped active large pitch fiber with a core diameter of 190 μm and a mode-field diameter of180 μm is designed by this method,and the designed fiber allows effective single-mode operation.
文摘Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far field uniform uniaxial tensile or compressive stress.
文摘目的探讨脑膜瘤患者术后静脉血栓栓塞症(Venous thrombus embolism,VTE)形成的风险因素,构建VTE形成列线图模型并进行验证。方法选取2020年1月-2022年12月新疆医科大学第一附属医院神经外科接受手术治疗的417例脑膜瘤患者为研究对象,采用单因素分析和多因素Logistic回归分析筛选417例脑膜瘤患者术后发生VTE的影响因素,构建列线图模型,并对模型进行内部验证。结果417例患者中150例(36%)发生了VTE,Logistic回归分析显示,年龄大于60岁、住院天数、D-二聚体、术后血钠、低密度脂蛋白为独立风险因素(P<0.05)。基于上述独立风险因素所构建的列线图模型,校准度(χ^(2)=6.424,P=0.781)和区分度[曲线下面积(Area under curve,AUC)=0.841,95%CI:0.800~0.882]良好。校准曲线与决策曲线显示,模型一致性及获益良好。结论以年龄大于60岁、住院天数、D-二聚体、术后血钠、低密度脂蛋白构建的脑膜瘤患者术后VTE发生的列线图模型具有较高的预测价值,可为脑膜瘤患者术后VTE的护理措施提供依据。
