BACKGROUND Gastrointestinal neurofibromas are commonly found in patients diagnosed with neurofibromatosis type 1.However,isolated gastrointestinal neurofibromas are a rare entity and only fourteen cases of isolated co...BACKGROUND Gastrointestinal neurofibromas are commonly found in patients diagnosed with neurofibromatosis type 1.However,isolated gastrointestinal neurofibromas are a rare entity and only fourteen cases of isolated colorectal neurofibromas have been documented in literature.Isolated gastrointestinal neurofibromas have not been associated with Lynch syndrome(LS).Patients with LS are at an increased risk of colorectal cancer,and are recommended to undergo screening colonoscopy.CASE SUMMARY A 33-year-old healthy female with a family history of LS was found to have unresectable polyp in the ascending colon on screening colonoscopy suspicious for malignancy.The patient was asymptomatic and had no stigmata of neurofibromatosis.A staging workup for colorectal cancer revealed no evidence of metastatic disease.A discussion with the patient resulted in the decision to undergo a segmental resection with ongoing surveillance.The patient underwent a laparoscopic right hemicolectomy.Histopathology was consistent with a gastrointestinal neurofibroma.Post-operatively,the patient recovered well.She will not require further treatment with regards to her colonic neurofibroma,but will continue to follow-up for ongoing surveillance of her LS.CONCLUSION We present the first case of an isolated colonic neurofibroma in a patient with LS.This case explores considerations for the management of isolated gastrointestinal neurofibromas given the lack of guidelines in literature.展开更多
Large thin walled cylindrical above ground tanks have become more susceptible to failure by buckling during earthquakes. In this study, three different geometries of tanks with H/D （height to diameter） ratios of 2.0...Large thin walled cylindrical above ground tanks have become more susceptible to failure by buckling during earthquakes. In this study, three different geometries of tanks with H/D （height to diameter） ratios of 2.0, 0.56, 1.0, and D/t （depth to thickness） ratios of 960.0, 1,706.67 and 640.0 respectively were analyzed for stability when subjected to the E1 Centro earthquake at the base. The Budiansky and Roth procedure was used to find the buckling loads when the tanks were empty and when they were filled with liquid up to 90% of their depth. Also, nonlinear time history analysis using ANSYS finite element computer program was performed. Analysis results show that the dynamic buckling occurs for empty tanks at very high PGA （peak ground accelerations） which are unrealistic even for major earthquakes. Furthermore, when the tanks filled with water up to 90% of its height, analysis results show that when the H/D ratio reduced by two times （i.e., from 2 to 1）, the PGA for the buckling increased by six times （increase from 0.25g to 1 .Sg）. Hence, H/D ratio plays an important role in the earthquake stability design of over ground steel tanks.展开更多
文摘BACKGROUND Gastrointestinal neurofibromas are commonly found in patients diagnosed with neurofibromatosis type 1.However,isolated gastrointestinal neurofibromas are a rare entity and only fourteen cases of isolated colorectal neurofibromas have been documented in literature.Isolated gastrointestinal neurofibromas have not been associated with Lynch syndrome(LS).Patients with LS are at an increased risk of colorectal cancer,and are recommended to undergo screening colonoscopy.CASE SUMMARY A 33-year-old healthy female with a family history of LS was found to have unresectable polyp in the ascending colon on screening colonoscopy suspicious for malignancy.The patient was asymptomatic and had no stigmata of neurofibromatosis.A staging workup for colorectal cancer revealed no evidence of metastatic disease.A discussion with the patient resulted in the decision to undergo a segmental resection with ongoing surveillance.The patient underwent a laparoscopic right hemicolectomy.Histopathology was consistent with a gastrointestinal neurofibroma.Post-operatively,the patient recovered well.She will not require further treatment with regards to her colonic neurofibroma,but will continue to follow-up for ongoing surveillance of her LS.CONCLUSION We present the first case of an isolated colonic neurofibroma in a patient with LS.This case explores considerations for the management of isolated gastrointestinal neurofibromas given the lack of guidelines in literature.
文摘Large thin walled cylindrical above ground tanks have become more susceptible to failure by buckling during earthquakes. In this study, three different geometries of tanks with H/D （height to diameter） ratios of 2.0, 0.56, 1.0, and D/t （depth to thickness） ratios of 960.0, 1,706.67 and 640.0 respectively were analyzed for stability when subjected to the E1 Centro earthquake at the base. The Budiansky and Roth procedure was used to find the buckling loads when the tanks were empty and when they were filled with liquid up to 90% of their depth. Also, nonlinear time history analysis using ANSYS finite element computer program was performed. Analysis results show that the dynamic buckling occurs for empty tanks at very high PGA （peak ground accelerations） which are unrealistic even for major earthquakes. Furthermore, when the tanks filled with water up to 90% of its height, analysis results show that when the H/D ratio reduced by two times （i.e., from 2 to 1）, the PGA for the buckling increased by six times （increase from 0.25g to 1 .Sg）. Hence, H/D ratio plays an important role in the earthquake stability design of over ground steel tanks.
