AIMTo define the role of small-bowel transit time in the detection rate of significant small-bowel lesions.METHODSSmall-bowel capsule endoscopy records, prospectively collected from 30 participating centers in the Lom...AIMTo define the role of small-bowel transit time in the detection rate of significant small-bowel lesions.METHODSSmall-bowel capsule endoscopy records, prospectively collected from 30 participating centers in the Lombardy Registry from October 2011 to December 2013, were included in the study if the clinical indication was obscure gastrointestinal bleeding and the capsule reached the cecum. Based on capsule findings, we created two groups: P2 (significant findings) and P0-1 (normal/negligible findings). Groups were compared for age, gender, small-bowel transit time, type of instrument, modality of capsule performance (outpatients vs inpatients), bowel cleanliness, and center volume.RESULTSWe retrieved and scrutinized 1,433 out of 2,295 capsule endoscopy records (62.4%) fulfilling the inclusion criteria. Patients were 67 ± 15 years old, and 815 (57%) were males. In comparison with patients in the P0-1 group, those in the P2 group (n = 776, 54%) were older (P < 0.0001), had a longer small-bowel transit time (P = 0.0015), and were more frequently examined in low-volume centers (P < 0.001). Age and small-bowel transit time were correlated (P < 0.001), with age as the sole independent predictor on multivariable analysis. Findings of the P2 group were artero-venous malformations (54.5%), inflammatory (23.6%) and protruding (10.4%) lesions, and luminal blood (11.5%).CONCLUSIONIn this selected, prospectively collected cohort of small-bowel capsule endoscopy performed for obscure gastrointestinal bleeding, a longer small-bowel transit time was associated with a higher detection rate of significant lesions, along with age and a low center volume, with age serving as an independent predictor.展开更多
Bled air from the high pressure compressor takes up 3%—5% in the air system.However,there are not many studies on the compressor performance after bleeding.By analyzing the low-speed single-stage compressors,six blee...Bled air from the high pressure compressor takes up 3%—5% in the air system.However,there are not many studies on the compressor performance after bleeding.By analyzing the low-speed single-stage compressors,six bleeding structures are presented according to their influence mechanism on the compressor performance,and five kinds of bleeding rate are applied to one of the structures.A numerical simulation is performed to study the influence of bleeding rates and structures on the compressor performance.The results show that for the stators with the large flow separation in the corner,bleeding a small amount of air from the end-wall region can improve the total pressure increase and the stability margin.Moreover there is an optimum value of the bleeding rate in the stator casing.展开更多
The gridless method coupled with finite rate chemistry model is employed to simulate the external combustion flow fields of M864 base bleed projectile. The fluid dynamics process is described by Euler Equation in 2-D ...The gridless method coupled with finite rate chemistry model is employed to simulate the external combustion flow fields of M864 base bleed projectile. The fluid dynamics process is described by Euler Equation in 2-D axisymmetric coordinate. The numerical method is based on least-square gridless method,and the inviscid flux is calculated by multi-component HLLC( Harten-Lax-van Leer-Contact) scheme,and a H2-CO reaction mechanism involving 9 species and 11 reactions is used. The computations are performed for the full projectile configuration of Ma = 1. 5,2,and 3. The hot air injection cases and inert cases are simulated for comparison. The numerical results show that due to the combustion in the weak region,the recirculation zone enlarges and moves downstream,the base pressure increases and the total drag force coefficient decreases. At Ma = 3. 0,the rear stagnation point shifts downstream approximate 0. 26 caliber,and the base pressure increases about 53. 4%,and the total drag force coefficient decreases to 0. 182 which agrees well with the trajectory model prediction. Due to neglecting the effects of viscosity and turbulence,there exists a certain difference at Ma = 1. 5,2. 0.展开更多
BACKGROUND Small bowel tumors(SBTs)are a heterogeneous group of difficult-to-diagnose tumors that account for 2%-5%of all gastrointestinal tumors.Single-balloon enteroscopy greatly enhances the diagnosis and treatment...BACKGROUND Small bowel tumors(SBTs)are a heterogeneous group of difficult-to-diagnose tumors that account for 2%-5%of all gastrointestinal tumors.Single-balloon enteroscopy greatly enhances the diagnosis and treatment of SBTs.However,few epidemiological studies have been conducted in Taiwan to determine the clinical profile of SBTs.AIM To investigate the clinical characteristics,managements and prognosis of SBTs in a medical center in Taiwan.METHODS The study enrolled 51 patients aged 58.9±8.8 years(range,22-93)diagnosed with SBTs from November 2009 to July 2021.We retrospectively recorded clinical characteristics,indications,endoscopic findings,pathological results,management,and outcomes for further analysis.RESULTS A male preponderance was observed(56.8%).The most common indications were suspected small intestinal tumors(52.9%)and obscure gastrointestinal bleeding(39.2%).The most common tumor location was the ileum(41.2%).The performance of imaging studies(P=0.004)and the types of findings(P=0.005)differed significantly between malignant and benign SBTs.The most frequent imaging finding was a small intestinal mass(43.1%).The top three malignant tumor types were gastrointestinal stromal tumors(GISTs),adenocarcinomas,and lymphomas.Moreover,the proportions of benign and malignant tumors were 27.5%and 72.5%,respectively.The survival rates of patients with malignant tumors in the GIST and non-GIST groups differed significantly(P=0.015).Kaplan–Meier survival analysis showed a significant difference in survival between patients in the malignant and benign groups(P=0.04).All patients with lymphoma underwent chemotherapy(n=7/8,87.5%),whereas most patients with GISTs underwent surgery(n=13/14,92.8%).CONCLUSION Patients with GISTs have a significantly higher survival rate than those with other malignant SBTs.Therefore,a large-scale nationwide study is warranted to evaluate the population-based epidemiology of SBTs.展开更多
文摘AIMTo define the role of small-bowel transit time in the detection rate of significant small-bowel lesions.METHODSSmall-bowel capsule endoscopy records, prospectively collected from 30 participating centers in the Lombardy Registry from October 2011 to December 2013, were included in the study if the clinical indication was obscure gastrointestinal bleeding and the capsule reached the cecum. Based on capsule findings, we created two groups: P2 (significant findings) and P0-1 (normal/negligible findings). Groups were compared for age, gender, small-bowel transit time, type of instrument, modality of capsule performance (outpatients vs inpatients), bowel cleanliness, and center volume.RESULTSWe retrieved and scrutinized 1,433 out of 2,295 capsule endoscopy records (62.4%) fulfilling the inclusion criteria. Patients were 67 ± 15 years old, and 815 (57%) were males. In comparison with patients in the P0-1 group, those in the P2 group (n = 776, 54%) were older (P < 0.0001), had a longer small-bowel transit time (P = 0.0015), and were more frequently examined in low-volume centers (P < 0.001). Age and small-bowel transit time were correlated (P < 0.001), with age as the sole independent predictor on multivariable analysis. Findings of the P2 group were artero-venous malformations (54.5%), inflammatory (23.6%) and protruding (10.4%) lesions, and luminal blood (11.5%).CONCLUSIONIn this selected, prospectively collected cohort of small-bowel capsule endoscopy performed for obscure gastrointestinal bleeding, a longer small-bowel transit time was associated with a higher detection rate of significant lesions, along with age and a low center volume, with age serving as an independent predictor.
基金Supported by the National Natural Science Foundation of China(60934001)~~
文摘Bled air from the high pressure compressor takes up 3%—5% in the air system.However,there are not many studies on the compressor performance after bleeding.By analyzing the low-speed single-stage compressors,six bleeding structures are presented according to their influence mechanism on the compressor performance,and five kinds of bleeding rate are applied to one of the structures.A numerical simulation is performed to study the influence of bleeding rates and structures on the compressor performance.The results show that for the stators with the large flow separation in the corner,bleeding a small amount of air from the end-wall region can improve the total pressure increase and the stability margin.Moreover there is an optimum value of the bleeding rate in the stator casing.
文摘The gridless method coupled with finite rate chemistry model is employed to simulate the external combustion flow fields of M864 base bleed projectile. The fluid dynamics process is described by Euler Equation in 2-D axisymmetric coordinate. The numerical method is based on least-square gridless method,and the inviscid flux is calculated by multi-component HLLC( Harten-Lax-van Leer-Contact) scheme,and a H2-CO reaction mechanism involving 9 species and 11 reactions is used. The computations are performed for the full projectile configuration of Ma = 1. 5,2,and 3. The hot air injection cases and inert cases are simulated for comparison. The numerical results show that due to the combustion in the weak region,the recirculation zone enlarges and moves downstream,the base pressure increases and the total drag force coefficient decreases. At Ma = 3. 0,the rear stagnation point shifts downstream approximate 0. 26 caliber,and the base pressure increases about 53. 4%,and the total drag force coefficient decreases to 0. 182 which agrees well with the trajectory model prediction. Due to neglecting the effects of viscosity and turbulence,there exists a certain difference at Ma = 1. 5,2. 0.
文摘BACKGROUND Small bowel tumors(SBTs)are a heterogeneous group of difficult-to-diagnose tumors that account for 2%-5%of all gastrointestinal tumors.Single-balloon enteroscopy greatly enhances the diagnosis and treatment of SBTs.However,few epidemiological studies have been conducted in Taiwan to determine the clinical profile of SBTs.AIM To investigate the clinical characteristics,managements and prognosis of SBTs in a medical center in Taiwan.METHODS The study enrolled 51 patients aged 58.9±8.8 years(range,22-93)diagnosed with SBTs from November 2009 to July 2021.We retrospectively recorded clinical characteristics,indications,endoscopic findings,pathological results,management,and outcomes for further analysis.RESULTS A male preponderance was observed(56.8%).The most common indications were suspected small intestinal tumors(52.9%)and obscure gastrointestinal bleeding(39.2%).The most common tumor location was the ileum(41.2%).The performance of imaging studies(P=0.004)and the types of findings(P=0.005)differed significantly between malignant and benign SBTs.The most frequent imaging finding was a small intestinal mass(43.1%).The top three malignant tumor types were gastrointestinal stromal tumors(GISTs),adenocarcinomas,and lymphomas.Moreover,the proportions of benign and malignant tumors were 27.5%and 72.5%,respectively.The survival rates of patients with malignant tumors in the GIST and non-GIST groups differed significantly(P=0.015).Kaplan–Meier survival analysis showed a significant difference in survival between patients in the malignant and benign groups(P=0.04).All patients with lymphoma underwent chemotherapy(n=7/8,87.5%),whereas most patients with GISTs underwent surgery(n=13/14,92.8%).CONCLUSION Patients with GISTs have a significantly higher survival rate than those with other malignant SBTs.Therefore,a large-scale nationwide study is warranted to evaluate the population-based epidemiology of SBTs.
