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A time-dependent logit-based taxi customer-search model
Wai Yuen Szeto,Ryan Cheuk Pong Wong,Sze Chun Wong,HaiYang 서울시립대학교 도시과학연구원 2013 도시과학국제저널 Vol.17 No.2
In this study, global positioning system data from 460 urban taxis are used to develop a time-dependent logit model. The rate of return (ROR, also known as profit per unit time) is used as a factor underlying taxi drivers’ searching behaviour for customers. The data also reveal that the search behaviour across districts as well as the decisions towards a particular district in customer-search is strongly related to the daily profile of passenger demand, and that when the overall passenger demand is high, vacant taxi drivers tend to circulate within or wait at the area where their preceding customers got off to find their next customer. The results also show that the ROR is a significant factor that affects the customer-searching strategies of vacant taxi drivers over a day, and is inversely related to the percentage of taxi idling time. More importantly, this paper illustrates that there is a change in searching behaviour over time of day.
Ying-Jie Chen,Jia-Ying Wu,Yu-Yi Deng,Ying Wu,Xiao-Qi Wang,Amy Sze-man Li,Lut Yi Wong,Xiuqiong Fu,Zhi-Ling Yu,Chun Liang 고려인삼학회 2022 Journal of Ginseng Research Vol.46 No.3
Sorafenib is effective in treating hepatoma, but most patients develop resistance to it. STAT3signaling has been implicated in sorafenib resistance. Artesunate (ART) and 20(R)-ginsenoside Rg3 (Rg3)have anti-hepatoma effects and can inhibit STAT3 signaling in cancer cells. This study aimed to evaluatethe effects of Rg3 in combination with ART (Rg3-plus-ART) in overcoming sorafenib resistance, and toexamine the involvement of STAT3 signaling in these effects. Methods: Sorafenib-resistant HepG2 cells (HepG2-SR) were used to evaluate the in vitro anti-hepatomaeffects of Rg3-plus-ART. A HepG2-SR hepatoma-bearing BALB/c-nu/nu mouse model was used to assessthe in vivo anti-hepatoma effects of Rg3-plus-ART. CCK-8 assays and Annexin V-FITC/PI double stainingwere used to examine cell proliferation and apoptosis, respectively. Immunoblotting was employed toexamine protein levels. ROS generation was examined by measuring DCF-DA fluorescence. Results: Rg3-plus-ART synergistically reduced viability of, and evoked apoptosis in HepG2-SR cells, andsuppressed HepG2-SR tumor growth in mice. Mechanistic studies revealed that Rg3-plus-ART inhibitedactivation/phosphorylation of Src and STAT3 in HepG2-SR cultures and tumors. The combination alsodecreased the STAT3 nuclear level and induced ROS production in HepG2-SR cultures. Furthermore, overactivation of STAT3 or removal of ROS diminished the anti-proliferative effects of Rg3-plus-ART, andremoval of ROS diminished Rg3-plus-ART's inhibitory effects on STAT3 activation in HepG2-SR cells. Conclusions: Rg3-plus-ART overcomes sorafenib resistance in experimental models, and inhibition of Src/STAT3 signaling and modulation of ROS/STAT3 signaling contribute to the underlying mechanisms. Thisstudy provides a pharmacological basis for developing Rg3-plus-ART into a novel modality for treatingsorafenib-resistant hepatoma.