Based on the characteristics of urban-rural dual economic structure in China,we build a dynamic endogenous urban-rural dual economic model closely linked to China's reality,and carry out mathematical economics ana...Based on the characteristics of urban-rural dual economic structure in China,we build a dynamic endogenous urban-rural dual economic model closely linked to China's reality,and carry out mathematical economics analysis of optimized conditions for urban and rural sectors. The main results show that:(i) The labor growth rate of urban-rural sectors must be greater than the time discount rate,or else there would be a vicious cycle of diminishing returns in the sectors;(ii) The accumulation rate of physical capital and human capital of urban-rural sectors,and the rate of technological progress,need to be greater than the corresponding depreciation rate plus the time discount rate,otherwise there would be a vicious cycle of diminishing returns in the sectors;(iii) The low accumulation rate in the rural sector,and the occurrence of labor outflow,human capital loss and lack of investment,will expand income gap between urban and rural areas,which is a reason for solidification of urban-rural dual economic structure.展开更多
Objective： The combination of both nuclear and fluorescent reporters provides unique opportunities for noninvasive nuclear imaging with subsequent fluorescence image-guided resection and pathology. Our objective was ...Objective： The combination of both nuclear and fluorescent reporters provides unique opportunities for noninvasive nuclear imaging with subsequent fluorescence image-guided resection and pathology. Our objective was to synthesize and optimize a dual-labeled trastuzumab-based imaging agent that can be used to validate an optical imaging agent with potential use in identifying tumor metastases in human epidermal growth factor receptor 2 （HER2） positive breast cancer patients. Methods： [111In]-DTPA-trastuzumab-IRDye 800 was synthesized by a three-step procedure. Purity, stability, immunoreactivity, internalization and biodistribution were explored in HER2＋ SKBR-3 cells. Biodistribution of [111In]-DTPA-trastuzumab-IRDye 800 was performed in a SKBR-3 xenograft model. Results： [111In]-DTPA-trastuzumab-IRDye 800 demonstrated high purity by both chemical and fluorometric determinations. Both flow cytometry and the Lindmo assay demonstrated a high binding affinity of [111In]-DTPA-trastuzumab-IRDye 800 to HER2-overexpressing cells. The dual-labeled conjugate was stable in PBS, but not in serum after 24 h at 37 ℃. Larger molecules （〉150 kD） were seen after a 24 h-incubation in human serum. Biodistribution studies revealed tumor-specific accumulation of [111In]-DTPA- trastuzumab-IRDye 800 in SKBR-3 tumors, and tumor uptakes at 24 and 48 h were （12.42±1.72）% and （9.96±1.05） %, respectively, following intravenous administration. The tumor-to-muscle ratio was 9.13±1.68 at 24 h, and increased to 12.79±2.13 at 48 h. Liver and kidney showed marked uptake of the dual-labeled imaging agent. Conclusions： [111In]-DTPA-trastuzumab-IRDye 800 is an effective diagnostic biomarker that can be used to validate dual-labeled, molecularly targeted imaging agents and can allow these agents to be translated into clinical practice for identifying HER2＋ lesions.展开更多
We compare the effects of interactive and noninteractive complementary nutrients on the growth of an organism in the chemostat. We also compare these two situations to the case when the nutrients are substitutable. In...We compare the effects of interactive and noninteractive complementary nutrients on the growth of an organism in the chemostat. We also compare these two situations to the case when the nutrients are substitutable. In previous studies, complementary nutrients have been assumed to be noninteractive. However, more recent research indicates that some complementary nutrient relationships are interactive. We show that interactive complementary and substitutable nutrients can lead to higher population densities than do noninteractive complementary nutrients. We numerically illustrate that if the washout rate is high, an organism can persist at higher densities when the complementary nutrients are interactive than when they are noninteractive, which can result in the extinction of the organism. Finally, we present an example by making a small adjustment to the model that leads to a single nutrient model with an intermediate metabolite of the original substrate as the nutrient for the organism.展开更多
基金Supported by Chongqing Social Science Planning Project(2010YBJJ13)the Fundamental Research Funds for the Central Universities(XDJK2010C103)+1 种基金Humanities and Social Sciences Youth Project,the Ministry of Education(10YJC630205)Chongqing Key Humanities and Social Sciences Project(SWU 0810026)
文摘Based on the characteristics of urban-rural dual economic structure in China,we build a dynamic endogenous urban-rural dual economic model closely linked to China's reality,and carry out mathematical economics analysis of optimized conditions for urban and rural sectors. The main results show that:(i) The labor growth rate of urban-rural sectors must be greater than the time discount rate,or else there would be a vicious cycle of diminishing returns in the sectors;(ii) The accumulation rate of physical capital and human capital of urban-rural sectors,and the rate of technological progress,need to be greater than the corresponding depreciation rate plus the time discount rate,otherwise there would be a vicious cycle of diminishing returns in the sectors;(iii) The low accumulation rate in the rural sector,and the occurrence of labor outflow,human capital loss and lack of investment,will expand income gap between urban and rural areas,which is a reason for solidification of urban-rural dual economic structure.
基金supported by Beijing Natural Science Foundation (No. 7132037)NIH R01
文摘Objective： The combination of both nuclear and fluorescent reporters provides unique opportunities for noninvasive nuclear imaging with subsequent fluorescence image-guided resection and pathology. Our objective was to synthesize and optimize a dual-labeled trastuzumab-based imaging agent that can be used to validate an optical imaging agent with potential use in identifying tumor metastases in human epidermal growth factor receptor 2 （HER2） positive breast cancer patients. Methods： [111In]-DTPA-trastuzumab-IRDye 800 was synthesized by a three-step procedure. Purity, stability, immunoreactivity, internalization and biodistribution were explored in HER2＋ SKBR-3 cells. Biodistribution of [111In]-DTPA-trastuzumab-IRDye 800 was performed in a SKBR-3 xenograft model. Results： [111In]-DTPA-trastuzumab-IRDye 800 demonstrated high purity by both chemical and fluorometric determinations. Both flow cytometry and the Lindmo assay demonstrated a high binding affinity of [111In]-DTPA-trastuzumab-IRDye 800 to HER2-overexpressing cells. The dual-labeled conjugate was stable in PBS, but not in serum after 24 h at 37 ℃. Larger molecules （〉150 kD） were seen after a 24 h-incubation in human serum. Biodistribution studies revealed tumor-specific accumulation of [111In]-DTPA- trastuzumab-IRDye 800 in SKBR-3 tumors, and tumor uptakes at 24 and 48 h were （12.42±1.72）% and （9.96±1.05） %, respectively, following intravenous administration. The tumor-to-muscle ratio was 9.13±1.68 at 24 h, and increased to 12.79±2.13 at 48 h. Liver and kidney showed marked uptake of the dual-labeled imaging agent. Conclusions： [111In]-DTPA-trastuzumab-IRDye 800 is an effective diagnostic biomarker that can be used to validate dual-labeled, molecularly targeted imaging agents and can allow these agents to be translated into clinical practice for identifying HER2＋ lesions.
文摘We compare the effects of interactive and noninteractive complementary nutrients on the growth of an organism in the chemostat. We also compare these two situations to the case when the nutrients are substitutable. In previous studies, complementary nutrients have been assumed to be noninteractive. However, more recent research indicates that some complementary nutrient relationships are interactive. We show that interactive complementary and substitutable nutrients can lead to higher population densities than do noninteractive complementary nutrients. We numerically illustrate that if the washout rate is high, an organism can persist at higher densities when the complementary nutrients are interactive than when they are noninteractive, which can result in the extinction of the organism. Finally, we present an example by making a small adjustment to the model that leads to a single nutrient model with an intermediate metabolite of the original substrate as the nutrient for the organism.
