Safety performance functions（SPFs） are crucial to science-based road safety management.Success in developing and applying SPFs, apart data quality and availability, depends fundamentally on two key factors： the val...Safety performance functions（SPFs） are crucial to science-based road safety management.Success in developing and applying SPFs, apart data quality and availability, depends fundamentally on two key factors： the validity of the statistical inferences for the available data and on how well the data can be organized into distinct homogeneous entities. The latter aspect plays a key role in the identification and treatment of road sections or corridors with problems related to safety. Indeed, the segmentation of a road network could be especially critical in the development of SPFs that could be used in safety management for roadway types, such as motorways（freeways in North America）, which have a large number of variables that could result in very short segments if these are desired to be homogeneous. This consequence, from an analytical point of view, can be a problem when the location of crashes is not precise and when there is an overabundance of segments with zero crashes. Lengthening the segments for developing and applying SPFs can mitigate this problem, but at a sacrifice of homogeneity. This paper seeks to address this dilemma by investigating four approaches for segmentation for motorways, using sample data from Italy. The best results were obtained for the segmentation based on two curves and two tangents within a segment and with fixed length segments. The segmentation characterized by a constant value of all original variables inside each segment was the poorest approach by all measures.展开更多
Ten outbred pigs were each operated on for three times. First, a 130 cm length of terminal ileum of each pig was isolated on its vascular pedicle as a Thiry-Vella loop. One week later, the solitary ileal segments were...Ten outbred pigs were each operated on for three times. First, a 130 cm length of terminal ileum of each pig was isolated on its vascular pedicle as a Thiry-Vella loop. One week later, the solitary ileal segments were transplanted heterotopically in two pigs. And after 28 days of heterotopic transplantation, the transplanted intestine was interposed into continuity of host intestine as orthotopic transplant. During the experiment, tests were made on 6th day after the first operation (period 1), the 14th (II), 28th (III) day after heterotopic transplantation, and 3 weeks after interposition (IV) respectively for the levels of glucose, palmitate and leucine. Additionally, at period I, III, and IV, a 3 cm length of intestinal mucosa was excised for morphologic observation and determination of DNA, RNA and protein contents. After heterotopic transplantation, the absorptive function of transplanted intestine was severely impaired for two weeks. The absorption of glucose! and palmitate was partially recovered by period III, at which time leucine level had return to normal. At period IV, the absorptive function of glucose and leucine had surpassed normal levels, while palmitate had risen to the level of pretransplantation. After transplantation, at period III, DNA, RNA and protein contents were well below normal. Three weeks after orthotopic transplantation, RNA and protein had risen to normal level, while DNA content remained below normal, The morphologic changes during the experiment were correlated with the changes of contents in RNA, protein and DNA. The area, height, width of villi and the area, depth, width:of crypt were below normal at III and recovered by 3 weeks after orthotopic transplantation (period IV), but were still lower than the levels at pretransplantation. Crypt depths were deeper than those of pretransplantation.展开更多
The quality of segment is very important to the service life of shield tunnel.Concerning the complex engineering environment of the Wuhan Yangtze River Shield Tunnel,the principle of functionally graded materials was ...The quality of segment is very important to the service life of shield tunnel.Concerning the complex engineering environment of the Wuhan Yangtze River Shield Tunnel,the principle of functionally graded materials was introduced to design and produce the functionally graded concrete segment(FGCS).Its key manufacturing technique was proposed and its performance was tested.展开更多
基金made possible by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (NSERC)
文摘Safety performance functions（SPFs） are crucial to science-based road safety management.Success in developing and applying SPFs, apart data quality and availability, depends fundamentally on two key factors： the validity of the statistical inferences for the available data and on how well the data can be organized into distinct homogeneous entities. The latter aspect plays a key role in the identification and treatment of road sections or corridors with problems related to safety. Indeed, the segmentation of a road network could be especially critical in the development of SPFs that could be used in safety management for roadway types, such as motorways（freeways in North America）, which have a large number of variables that could result in very short segments if these are desired to be homogeneous. This consequence, from an analytical point of view, can be a problem when the location of crashes is not precise and when there is an overabundance of segments with zero crashes. Lengthening the segments for developing and applying SPFs can mitigate this problem, but at a sacrifice of homogeneity. This paper seeks to address this dilemma by investigating four approaches for segmentation for motorways, using sample data from Italy. The best results were obtained for the segmentation based on two curves and two tangents within a segment and with fixed length segments. The segmentation characterized by a constant value of all original variables inside each segment was the poorest approach by all measures.
文摘Ten outbred pigs were each operated on for three times. First, a 130 cm length of terminal ileum of each pig was isolated on its vascular pedicle as a Thiry-Vella loop. One week later, the solitary ileal segments were transplanted heterotopically in two pigs. And after 28 days of heterotopic transplantation, the transplanted intestine was interposed into continuity of host intestine as orthotopic transplant. During the experiment, tests were made on 6th day after the first operation (period 1), the 14th (II), 28th (III) day after heterotopic transplantation, and 3 weeks after interposition (IV) respectively for the levels of glucose, palmitate and leucine. Additionally, at period I, III, and IV, a 3 cm length of intestinal mucosa was excised for morphologic observation and determination of DNA, RNA and protein contents. After heterotopic transplantation, the absorptive function of transplanted intestine was severely impaired for two weeks. The absorption of glucose! and palmitate was partially recovered by period III, at which time leucine level had return to normal. At period IV, the absorptive function of glucose and leucine had surpassed normal levels, while palmitate had risen to the level of pretransplantation. After transplantation, at period III, DNA, RNA and protein contents were well below normal. Three weeks after orthotopic transplantation, RNA and protein had risen to normal level, while DNA content remained below normal, The morphologic changes during the experiment were correlated with the changes of contents in RNA, protein and DNA. The area, height, width of villi and the area, depth, width:of crypt were below normal at III and recovered by 3 weeks after orthotopic transplantation (period IV), but were still lower than the levels at pretransplantation. Crypt depths were deeper than those of pretransplantation.
文摘The quality of segment is very important to the service life of shield tunnel.Concerning the complex engineering environment of the Wuhan Yangtze River Shield Tunnel,the principle of functionally graded materials was introduced to design and produce the functionally graded concrete segment(FGCS).Its key manufacturing technique was proposed and its performance was tested.
