Ensuring a minimum operational level of road networks in the presence of unexpected incidents is becoming a hot subject in academic circles as well as industry. To this end, it is important to understand the degree to...Ensuring a minimum operational level of road networks in the presence of unexpected incidents is becoming a hot subject in academic circles as well as industry. To this end, it is important to understand the degree to which each single element of the network contributes to the operation and performance of a network. In other words, a road can become an ＂Achilles-heel＂ for the entire network if it is closed due to a simple incident. Such insight of the detrimental loss of the closure of the roads would help us to be more vigilant and prepared. In this study, we develop an index dubbed as Achilles-heel index to quantify detrimental loss of the closure of the respective roads. More precisely, the Achilles-heel index indicates how many drivers are affected by the closure of the respective roads （the number of affected drivers is also called travel demand coverage）. To this end,roads with maximum travel demand coverage are sorted as the most critical ones, for which a method known as ＂link analysis＂--is adopted. In an iterative process, first, a road with highest traffic volume is first labeled as ＂target link,＂ and second, a portion of travel demand which is captured by the target link is excluded from travel demand. For the next iteration, the trimmed travel demand is then assigned to the network where all links including the target links run on the initial travel times. The process carries on until all links are labeled. The proposed methodology is applied to a large- sized network of Winnipeg, Canada. The results shed light on also bottleneck points of the network which may warrant provision of additional capacity or parallel roads.展开更多
Sever’s disease—also known as calcaneal apophysitis—is a common cause of heel pain in pediatric patients typically aged 7 - 14 years old. Sever’s disease can be painful and limit a child’s function as well as par...Sever’s disease—also known as calcaneal apophysitis—is a common cause of heel pain in pediatric patients typically aged 7 - 14 years old. Sever’s disease can be painful and limit a child’s function as well as participation in physical activity. Herein, we described a case of delayed presentation of chronic Sever’s disease in a child who had been experiencing heel pain for over one year which worsened substantially when the child began to participate in sports. This is important for the emergency medicine physician because Sever’s disease represents an underdiagnosed cause of foot and heel pain in the pediatric patient and may be often missed. We describe the diagnosis and treatment options of Sever’s disease as well as associated controversies, e.g., whether activity is indeed the cause of Sever’s disease and whether imaging is needed for a diagnosis.展开更多
文摘Ensuring a minimum operational level of road networks in the presence of unexpected incidents is becoming a hot subject in academic circles as well as industry. To this end, it is important to understand the degree to which each single element of the network contributes to the operation and performance of a network. In other words, a road can become an ＂Achilles-heel＂ for the entire network if it is closed due to a simple incident. Such insight of the detrimental loss of the closure of the roads would help us to be more vigilant and prepared. In this study, we develop an index dubbed as Achilles-heel index to quantify detrimental loss of the closure of the respective roads. More precisely, the Achilles-heel index indicates how many drivers are affected by the closure of the respective roads （the number of affected drivers is also called travel demand coverage）. To this end,roads with maximum travel demand coverage are sorted as the most critical ones, for which a method known as ＂link analysis＂--is adopted. In an iterative process, first, a road with highest traffic volume is first labeled as ＂target link,＂ and second, a portion of travel demand which is captured by the target link is excluded from travel demand. For the next iteration, the trimmed travel demand is then assigned to the network where all links including the target links run on the initial travel times. The process carries on until all links are labeled. The proposed methodology is applied to a large- sized network of Winnipeg, Canada. The results shed light on also bottleneck points of the network which may warrant provision of additional capacity or parallel roads.
文摘Sever’s disease—also known as calcaneal apophysitis—is a common cause of heel pain in pediatric patients typically aged 7 - 14 years old. Sever’s disease can be painful and limit a child’s function as well as participation in physical activity. Herein, we described a case of delayed presentation of chronic Sever’s disease in a child who had been experiencing heel pain for over one year which worsened substantially when the child began to participate in sports. This is important for the emergency medicine physician because Sever’s disease represents an underdiagnosed cause of foot and heel pain in the pediatric patient and may be often missed. We describe the diagnosis and treatment options of Sever’s disease as well as associated controversies, e.g., whether activity is indeed the cause of Sever’s disease and whether imaging is needed for a diagnosis.
