According to 20/80 principle, retaining VIP customers is one of the most critical challenges in the maturing mobile telecommunications service market. However, there are little literatures to explain why the VIP customers churn. Using mobile VIP customers' huge transaction and billing database, this study investigates determinants of mobile VIP customer churn. The results indicate that the switching cost: virtual private mobile network (VPMN) and family package are the most important factors in VIP customers churn. However, some marketing tools on ordinary users such as accumulated loyalty points, terminal bound contract do not work on VIP customers, which raise the questions about this marketing programme effectiveness. This study provides implications for the competition policies of mobile telephony market.
Background Relatively few studies have been made on neurobehavioral outcomes of prenatal maternal stress during the newborn period, and little research has focused on umbilical cord stress hormones including cortisol, adrenocorticotropic hormone (ACTH), norepinephrine, and epinephrine. Our objective was to investigate the effects of prenatal maternal life stressors on neonatal birth outcomes, neurobehavioral development, and stress-related hormones levels. Methods Participants were 142 mothers and their infants; 71 were selected as the prenatal life stressor exposed group and 71 as the control group matched on maternal age, gestational week, delivery type, socioeconomic and education status, and newborns' sex. Maternal life stressors during pregnancy were determined using the Life Events Scale for Pregnant Women. Neonatal neurobehavioral development was assessed with the Neonatal Behavioral Neurological Assessment. Umbilical cord plasma stress-related hormones, including ACTH, cortisol, norepinephrine, and epinephrine were measured using an enzyme-linked immunosorbent assay. Results In the prenatal life stressors exposed group, newborns had significantly lower birth weight, smaller head circumference (p < 0.01, p < 0.01, respectively). Scores of Neonatal Behavioral Neurological Assessment were significantly reduced (p < 0.001). Cord plasma ACTH, norepinephrine, and epinephrine levels were significantly increased (p < 0.001), but cortisol levels were reduced (p < 0.001). Conclusion Prenatal maternal stress may negatively affect fetal birth outcomes, neurobehavioral development and affect neonates' cord plasma ACTH, cortisol, norepinephrine, and epinephrine.
Three problems remained to be solved in the analysis of the seismic stability of high-fill embankment:the pseudo-static method was defective, the embankment damage model was not clear, and the stability evaluation index wasstill to be discussed. It analyzed the dynamic response of a typical transect of high embankment with FEM to find out its instability mechanism. Thenit chose the most dangerous sliding surface and analyzed its stability. The selection of the evaluation index of the seismic stability of high-fill embankment was discussed at last. The results show thatthe upper embankment, especially the shoulder is easily to be damaged. It is too conservative to use the safety factor as the involution index of the seismic stability of high-fill embankment, and the permanent displacement is a better choice.
Subway shield lining segments are highly sensitive to peripheral soil disturbance. Shield displacement may destroy the whole structure which can not be repaired, and directly affects the subway operation safety at the worst. Therefore, it is necessary to reasonably determine the construction technology, in order to avoid the unfavorable influences caused by construction disturbance. According to the pile-board subgrade scheme which is adopted by the comparison of schemes, also considering the high risk of over-shallow-embedded metro construction, we put forward the key construction technique of pile-board subgrade, including: technique of casing tube bored pile, construction process of pile-board structure and monitoring of settlement and deformation which are important to guide the similar projects.
Yao, Jun Kai
Yang, Ling Ling
The paper took Taiyuan-Zhongwei-Yinchuan Railway as a background and the study focused on the frost damage there. First of all, the influence on the line operation was mentioned, discussing the status quo and the characteristics of the damage; next, by means of on-site investigation and testing, the phenomenon in the typical frost damage zone along the Railway was analyzed with the damages being classified; simultaneously, taking the track bed and the subgrade bed as the objectives, the damages were studied from the aspect of soil, water and temperature; last, the genesis and mechanism of the frost damage to the Lanzhou-Xinjiang Railway subgrade was generalized, offering the basis of the treatment.
Peng, Chang Sheng
Yu, Hong Jun
Xu, Xing Yong
Xu, Xiu Li
under the background of global environmental change and the influence of human activities on the environment increasingly significant, the research of continental-oceanic interaction has become the current hot issues in geological field research. The continuous dynamic monitoring of groundwater will be conducted, and technology validation about the dynamic changes of groundwater vary with tidal interactions will be studied in the seawater intrusion area of the laizhou bay using high density electrical method in this research. The results suggest that, If we obtain the value of electrical characteristics of the fresh-saline groundwater by numerically or laboratory experiments, Such as we choose 15 Omega m in Laizhou Bay, we can use high-density electrical to continuous monitor to solve the Scientific Problems of the interface of the fresh-saline groundwater with the effect of tidal variation.