AIM:To describe a modified technique for placement of a tracheobronchial self-expanding plastic stent(SEPS) in patients with benign refractory hypopharyngeal strictures in order to improve dysphagia and allow strictur...AIM:To describe a modified technique for placement of a tracheobronchial self-expanding plastic stent(SEPS) in patients with benign refractory hypopharyngeal strictures in order to improve dysphagia and allow stricture remodeling.METHODS:A case series of four consecutive patients with complex hypopharyngeal strictures after combinedtherapy for laryngeal cancer,previously submitted to multiple sessions of dilation without lasting improvement,is presented.All patients underwent placement of a small diameter and unflared tracheobronchial SEPS.Main outcome measurements were improvement of dysphagia and avoiding of repeated dilation.RESULTS:The modified introducer system allowed an easy and technically successful deployment of the tracheobronchial Polyflex stent through the stricture.All four patients developed complications related to stent placement.Two patients had stent migration(one proximal and one distal),two patients developed phanryngocutaneous fistulas and all patients with stents in situ for more than 8 wk had hyperplastic tissue growth at the upper end of the stent.Stricture recurrence was observed at 4 wk follow-up after stent removal in all patients CONCLUSION:Although technically feasible,placement of a tracheobronchial SEPS is associated with a high risk of complications.Small diameter stents must be kept in place for longer than 3 mo to allow adequate time for stricture remodeling.展开更多
This paper presents a description and analysis of the most important models to predict each of the Road User Costs components （Vehicle Operating Costs, Accident Costs and Value of Time） and proposes a model for esti...This paper presents a description and analysis of the most important models to predict each of the Road User Costs components （Vehicle Operating Costs, Accident Costs and Value of Time） and proposes a model for estimating RUC components suitable for the Portuguese road network. These results are part of a research which aimed to obtain a Road User Cost Model to be used as a tool in road management systems. This model is different from other models by the fact that it includes a simple formulation that allows calibration and calculation of cost parameters, for any year, in a simple and fast way, providing trustworthy results. The required data is already available in Portuguese institutions, allowing periodic revision of cost parameters to insure accuracy.展开更多
This paper considers the completion time and the interruption time of a job processed on an unreliable machine. By using the general theory of stochastic orderings, we obtain the closure properties of the distribution...This paper considers the completion time and the interruption time of a job processed on an unreliable machine. By using the general theory of stochastic orderings, we obtain the closure properties of the distribution of the completion time and the interruption time on L^+ and PH life distribution classes. We get an exponential bound for the tail probability of the interruption time.展开更多
文摘AIM:To describe a modified technique for placement of a tracheobronchial self-expanding plastic stent(SEPS) in patients with benign refractory hypopharyngeal strictures in order to improve dysphagia and allow stricture remodeling.METHODS:A case series of four consecutive patients with complex hypopharyngeal strictures after combinedtherapy for laryngeal cancer,previously submitted to multiple sessions of dilation without lasting improvement,is presented.All patients underwent placement of a small diameter and unflared tracheobronchial SEPS.Main outcome measurements were improvement of dysphagia and avoiding of repeated dilation.RESULTS:The modified introducer system allowed an easy and technically successful deployment of the tracheobronchial Polyflex stent through the stricture.All four patients developed complications related to stent placement.Two patients had stent migration(one proximal and one distal),two patients developed phanryngocutaneous fistulas and all patients with stents in situ for more than 8 wk had hyperplastic tissue growth at the upper end of the stent.Stricture recurrence was observed at 4 wk follow-up after stent removal in all patients CONCLUSION:Although technically feasible,placement of a tracheobronchial SEPS is associated with a high risk of complications.Small diameter stents must be kept in place for longer than 3 mo to allow adequate time for stricture remodeling.
文摘This paper presents a description and analysis of the most important models to predict each of the Road User Costs components （Vehicle Operating Costs, Accident Costs and Value of Time） and proposes a model for estimating RUC components suitable for the Portuguese road network. These results are part of a research which aimed to obtain a Road User Cost Model to be used as a tool in road management systems. This model is different from other models by the fact that it includes a simple formulation that allows calibration and calculation of cost parameters, for any year, in a simple and fast way, providing trustworthy results. The required data is already available in Portuguese institutions, allowing periodic revision of cost parameters to insure accuracy.
基金This work is partially supported by the National Natural Science Foundation of China(Grant No. 60074018,No. 10271102)the Natural Science Foundation of Hebei Province(Grant No. A2004000185)and the Doctoral Foundation of Hebei Province(Grant No. 2002131).
文摘This paper considers the completion time and the interruption time of a job processed on an unreliable machine. By using the general theory of stochastic orderings, we obtain the closure properties of the distribution of the completion time and the interruption time on L^+ and PH life distribution classes. We get an exponential bound for the tail probability of the interruption time.
