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Navigating anatomical complexity in laparoscopic sigmoid cancer surgery:A three-dimension reconstruction protocol for intraoperative safety and efficiency
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作者 Zong-Xian Zhao Run-Dong Yao +3 位作者 Zong-Ju Hu Chao-Qian Chen Shu Zhu Yuan Yao 《World Journal of Gastrointestinal Surgery》 2025年第8期350-361,共12页
BACKGROUND Sigmoid colon cancer faces challenges due to anatomical diversity,including variable inferior mesenteric artery(IMA)branching and tumor localization complexities,which increase intraoperative risks.AIM To c... BACKGROUND Sigmoid colon cancer faces challenges due to anatomical diversity,including variable inferior mesenteric artery(IMA)branching and tumor localization complexities,which increase intraoperative risks.AIM To comprehensively evaluate the impact of three-dimensional(3D)visualization technology on enhancing surgical precision and safety,as well as optimizing perioperative outcomes in laparoscopic sigmoid cancer resection.METHODS A prospective cohort of 106 patients(January 2023 to December 2024)undergoing laparoscopic sigmoid cancer resection was divided into the 3D(n=55)group and the control(n=51)group.The 3D group underwent preoperative enhanced computed tomography reconstruction(3D Slicer 5.2.2&Mimics 19.0).3D reconstruction visualization navigation intraoperatively guided the following key steps:Tumor location,Toldt’s space dissection,IMA ligation level selection,regional lymph node dissection,and marginal artery preservation.Outcomes included operative parameters,lymph node yield,and recovery metrics.RESULTS The 3D group demonstrated a significantly shorter operative time(172.91±20.69 minutes vs 190.29±32.29 minutes;P=0.002),reduced blood loss(31.5±11.8 mL vs 44.1±23.4 mL,P=0.001),earlier postoperative flatus(2.23±0.54 days vs 2.53±0.61 days;P=0.013),shorter hospital length of stay(13.47±1.74 days vs 16.20±7.71 days;P=0.013),shorter postoperative length of stay(8.6±2.6 days vs 10.5±4.9 days;P=0.014),and earlier postoperative exhaust time(2.23±0.54 days vs 2.53±0.61 days;P=0.013).Furthermore,the 3D group exhibited a higher mean number of lymph nodes harvested(16.91±5.74 vs 14.45±5.66;P=0.030).CONCLUSION The 3D visualization technology effectively addresses sigmoid colon anatomical complexity through surgical navigation,improving procedural safety and efficiency. 展开更多
关键词 Three-dimension reconstruction sigmoid colon cancer Visualization Inferior mesenteric artery Anatomical complexity Intraoperative safety
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Chaotic time series prediction using fuzzy sigmoid kernel-based support vector machines 被引量:2
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作者 刘涵 刘丁 邓凌峰 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第6期1196-1200,共5页
Support vector machines (SVM) have been widely used in chaotic time series predictions in recent years. In order to enhance the prediction efficiency of this method and implement it in hardware, the sigmoid kernel i... Support vector machines (SVM) have been widely used in chaotic time series predictions in recent years. In order to enhance the prediction efficiency of this method and implement it in hardware, the sigmoid kernel in SVM is drawn in a more natural way by using the fuzzy logic method proposed in this paper. This method provides easy hardware implementation and straightforward interpretability. Experiments on two typical chaotic time series predictions have been carried out and the obtained results show that the average CPU time can be reduced significantly at the cost of a small decrease in prediction accuracy, which is favourable for the hardware implementation for chaotic time series prediction. 展开更多
关键词 support vector machines chaotic time series prediction fuzzy sigmoid kernel
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Constructive Approximation by Superposition of Sigmoidal Functions 被引量:2
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作者 Danilo Costarelli Renato Spigler 《Analysis in Theory and Applications》 2013年第2期169-196,共28页
In this paper, a constructive theory is developed for approximating func- tions of one or more variables by superposition of sigmoidal functions. This is done in the uniform norm as well as in the L^p norm. Results fo... In this paper, a constructive theory is developed for approximating func- tions of one or more variables by superposition of sigmoidal functions. This is done in the uniform norm as well as in the L^p norm. Results for the simultaneous approx- imation, with the same order of accuracy, of a function and its derivatives (whenever these exist), are obtained. The relation with neural networks and radial basis func- tions approximations is discussed. Numerical examples are given for the purpose of illustration. 展开更多
关键词 sigmoidal functions multivariate approximation L^p approximation neural net-works radial basis functions.
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Current indications and role of surgery in the management of sigmoid diverticulitis 被引量:1
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作者 Luca Stocchi 《World Journal of Gastroenterology》 SCIE CAS CSCD 2010年第7期804-817,共14页
Sigmoid diverticulitis is a common disease which carries both a significant morbidity and a societal economic burden.This review article analyzes the current data regarding management of sigmoid diverticulitis in its ... Sigmoid diverticulitis is a common disease which carries both a significant morbidity and a societal economic burden.This review article analyzes the current data regarding management of sigmoid diverticulitis in its variable clinical presentations.Wide-spectrum antibiotics are the standard of care for uncomplicated diverticulitis.Recently published data indicate that sigmoid diverticulitis does not mandate surgical management after the second episode of uncomplicated disease as previously recommended.Rather,a more individualized approach,taking into account frequency,severity of the attacks and their impact on quality of life,should guide the indication for surgery.On the other hand,complicated diverticular disease still requires surgical treatment in patients with acceptable comorbidity risk and remains a life-threatening condition in the case of free peritoneal perforation.Laparoscopic surgery is increasingly accepted as the surgical approach of choice for most presentations of the disease and has also been proposed in the treatment of generalized peritonitis.There is not sufficient evidence supporting any changes in the approach to management in younger patients.Conversely,the available evidence suggests that surgery should be indicated after one attack of uncomplicated disease in immunocompromised individuals.Uncommon clinical presentations of sigmoid diverticulitis and their possible association with inflammatory bowel disease are also discussed. 展开更多
关键词 sigmoid diverticulitis Diverticulitis management Diverticulitis surgery Acute diverticulitis Complicated diverticulitis Perforated diverticulitis Laparoscopic colectomy
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Observations on a Giant Sigmoid Volvulus with Unusual Clinical Presentation and Challenging Postoperative Course: Case Report 被引量:1
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作者 Giuseppe Pisano Pietro Giorgio Calò +1 位作者 Stefano Piras Enrico Erdas 《Surgical Science》 2015年第11期499-505,共7页
Introduction: The present report describes a case of a giant sigmoid volvulus (SV) where acute respiratory distress was associated with toxic megacolon. Clinical features, surgical treatment and postoperative course d... Introduction: The present report describes a case of a giant sigmoid volvulus (SV) where acute respiratory distress was associated with toxic megacolon. Clinical features, surgical treatment and postoperative course deserved our attention and discussion. Presentation of Case: A 67-year-old man with psychiatric disturbances was admitted to our Department with severe respiratory distress due to an enormous abdominal distension caused by a sigmoid volvulus. Endoscopic derotation was unsuccessful and surgery immediately performed. After a wide colonic resection the patient underwent a prolonged treatment in the Intensive Care Unit. Death occurred 34 days after the operation for secondary infection of peritoneal effusion. Discussion: Main clinical features of SV pertain to abdominal compartment while in the present case acute respiratory distress was the prominent symptom;in the same time the severity of the case was due to the association of high abdominal pressure together with a toxic megacolon. Postoperative treatment consisted in ventilatory support, with a progressive shift from asssisted to spontaneous ventilation;repeated sessions of haemodialysis were necessary to manage renal failure up to recovery of the urine output. Bacterial trans location due to toxic megacolon was responsible of late infection of ascitic fluid. In spite of multiple antibiotic association according to bacterial cultures, intra-abdominal abscesses eventually developed causing fatal outcome 34 days after the first intervention. Conclusion: Severe clinical presentation required a prolonged and demanding postoperative course which was focused on the recovery of respiratory, cardiac and renal function even if fatal outcome was due to septic complications. Suspicion of late infection of ascitic fluid could arise from persistently high values of inflammation indexes and drive to an earlier drainage of the abdominal abscesses. 展开更多
关键词 sigmoid VOLVULUS Toxic MEGACOLON ABDOMINAL COMPARTMENT Syndrome
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Sigmoid Colon Volvulus: Surgical Management at Kati BSS Hospital (Mali) 被引量:1
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作者 Koniba Keita Abdoulaye Diarra +14 位作者 Salia Coulibaly Sidiki Keita Issa Traore Moussa Doumbia Fadima Tall Daouda Diallo Oulematou Coulibaly Assitan Kone Boubacar Kone Daouda Konate Amadou Kassongue Moussa Salifou Diallo Ismael Konare Drissa Traore Nouhoum Ongoiba 《Surgical Science》 2019年第3期76-82,共7页
The objective of this study was to describe the therapeutic aspects and to evaluate the surgery results of sigmoid Volvulus in the Kati (MALIA) General Surgery Department. Patients and Methods: This was a descriptive ... The objective of this study was to describe the therapeutic aspects and to evaluate the surgery results of sigmoid Volvulus in the Kati (MALIA) General Surgery Department. Patients and Methods: This was a descriptive study conducted in our General Surgery Department. It took place in two phases for six years: A retrospective phase from January 1st, 2010 to December 31st, 2015 and a prospective phase from January 1st, 2016 to December 31st, 2017. This study has been approved by the Ethics Committee. It’s concerned all the patients operated in the department for colon Volvulus. Results: We collected 70 patients’ files. The Sigmoid Volvulus represented 7.8% of emergency surgery activities and 37.2% of intestinal obstruction. The male sex predominated with 98.57% against 1.43% of the female sex. The average age was 42.11 years old with limits of 18 to 70. The average deadline evolution was 2.53 days with limits of 1 to 3. The sigmoidectomy with immediate anastomosis was performed in 66% of patients, colectomy with 2-times anastomosis: according to Hartman 20% and Bouilly Volkman 11%, detorsion with colopexy 3%. The early morbidity rate was 5.71%. The average duration of hospitalization was 10.8 days with limits of 5 to 40 days. Two deaths were recorded. Conclusion: Sigmoid Volvulus is frequent in young adult sex male in Africa. We did not find any significant difference between the surgical technique and the advent of complications. The Colectomy with immediate anastomosis seems to be ideal to us that anytime the conditions are appropriate. 展开更多
关键词 VOLVULUS sigmoid COLECTOMY surgery
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DEGREE OF APPROXIMATION BY SUPERPOSITIONS OF A SIGMOIDAL FUNCTION 被引量:16
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作者 Chen Debao (University of Texas at Austin,USA) 《Analysis in Theory and Applications》 1993年第3期17-28,共12页
In this paper we study the degree of approximation by superpositions of a sigmoidal function.We mainly consider the univariate case.If f is a continuous function,we prove that for any bounded sigmoidal function σ,d_... In this paper we study the degree of approximation by superpositions of a sigmoidal function.We mainly consider the univariate case.If f is a continuous function,we prove that for any bounded sigmoidal function σ,d_(n,σ)(f)≤‖σ‖ω(f,1/(n+1)).For the Heaviside function H(x),we prove that d_(n,H)(f)≤ω(f,1/(2(n+1))). If f is a continuous funnction of bounded variation,we prove that d_(n,σ)(f)≤‖σ‖/(n+1)V(f)and d_(n,H)(f)≤ 1/(2(n+1))V(f).For he Heaviside function,the coefficient 1 and the approximation orders are the best possible.We compare these results with the classical Jackson and Bernstein theorems,and make some conjec- tures for further study. 展开更多
关键词 DEGREE OF APPROXIMATION BY suPERPOSITIONS OF A sigmoidAL FUNCTION
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SENP1通过PPARY去SUMO化修饰调控NF⁃κB信号通路参与糖尿病肾病进展的作用
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作者 陈淑娟 周丽明 +1 位作者 刘雪婷 李明政 《解剖学研究》 2025年第3期230-237,共8页
目的探讨小泛素样修饰体特异性肽酶1(SENP1)通过过氧化物酶体增殖物激活受体γ(PPARγ)去小泛素样修饰体(SUMO)化修饰调控核因子⁃κB(NF⁃κB)信号通路参与糖尿病肾病(DN)进展的作用和机制。方法取肾小球系膜细胞,分为肾小球系膜细胞(NC... 目的探讨小泛素样修饰体特异性肽酶1(SENP1)通过过氧化物酶体增殖物激活受体γ(PPARγ)去小泛素样修饰体(SUMO)化修饰调控核因子⁃κB(NF⁃κB)信号通路参与糖尿病肾病(DN)进展的作用和机制。方法取肾小球系膜细胞,分为肾小球系膜细胞(NC)组、高糖诱导的肾小球系膜细胞(HGMC组)、高糖诱导的肾小球系膜细胞+SENP1沉默质粒对照(si⁃NC1组)、高糖诱导的肾小球系膜细胞+SENP1沉默质粒(si⁃SENP1)组、高糖诱导的肾小球系膜细胞+SENP1过表达对照(mimic⁃NC1组)、高糖诱导的肾小球系膜细胞+SENP1过表达质粒(mimic⁃SENP1组)、高糖诱导的肾小球系膜细胞+PPARγ沉默对照(si⁃NC2组)、高糖诱导的肾小球系膜细胞+PPARγ沉默质粒(si⁃PPARγ组)、高糖诱导的肾小球系膜细胞+PPARγ过表达对照(mimic⁃NC2组)、高糖诱导的肾小球系膜细胞+PPARγ过表达质粒(mimic⁃PPARγ组)、高糖诱导的肾小球系膜细胞+SENP1过表达质粒+PPARγ过表达质粒(mimic⁃SENP1+mimic⁃PPARγ)。以qRT⁃PCR法检测各组SENP1、PPARγ表达;采用免疫印迹法检测NF⁃κB信号通路蛋白表达;TUNEL法检测细胞凋亡;免疫共沉淀验证SENP1可对PPARγ去SUMO化修饰。结果与NC组比,HGMC组SENP1及PPARγmRNA表达均显著降低(P<0.05),NF⁃κB1、IKKα1、IκBα蛋白1表达、细胞凋亡率均显著增加(P<0.05),与HGMC组或si⁃NC1组比,si⁃SENP1组的SENP1及PPARγmRNA表达均显著降低(P<0.05),NF⁃κB、IKKα、IκBα蛋白表达、细胞凋亡率均显著增加(P<0.05),与HGMC组或mimic⁃NC1组比,mimic⁃SENP1组的SENP1及PPARγmRNA表达均显著增加(P<0.05),NF⁃κB、IKKα、IκBα蛋白表达、细胞凋亡率均显著降低(P<0.05),与HGMC组或si⁃NC2组比,si⁃PPARγ组的PPARγmRNA达显著降低(P<0.05),NF⁃κB、IKKα、IκBα蛋白表达、细胞凋亡率均显著增加(P<0.05),与HGMC组或mimic⁃NC2组比,mimic⁃PPARγ组的PPARγmRNA表达显著增加(P<0.05),NF⁃κB、IKKα、IκBα蛋白表达、细胞凋亡率均显著降低(P<0.05),与mimic⁃SENP1组或mimic⁃PPARγ组比,mimic⁃SENP1+mimic⁃PPARγ组的SENP1及PPARγmRNA表达均显著增加(P<0.05),NF⁃κB、IKKα、IκBα蛋白表达、细胞凋亡率均显著降低(P<0.05)。结论SENP1可能通过PPARγ去SUMO化修饰抑制NF⁃κB信号通路参与DN进展。 展开更多
关键词 糖尿病肾病 小泛素样修饰体特异性肽酶1 过氧化物酶体增殖物激活受体Γ su⁃MO化修饰 核因子⁃κB信号通路
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Outcomes of preoperative chemoradiotherapy followed by surgery in patients with unresectable locally advanced sigmoid colon cancer 被引量:16
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作者 Bo Qiu Pei-Rong Ding +10 位作者 Ling Cai Wei-Wei Xiao Zhi-Fan Zeng Gong Chen Zhen-Hai Lu Li-Ren Li Xiao-Jun Wu Rene-Olivier Mirimanoff Zhi-Zhong Pan Rui-Hua Xu Yuan-Hong Gao 《Chinese Journal of Cancer》 SCIE CAS CSCD 2016年第10期535-545,共11页
Background: Complete resection of locally advanced sigmoid colon cancer(LASCC) is sometimes difficult. Patients with LASCC have a dismal prognosis and poor quality of life, which has encouraged the evaluation of alter... Background: Complete resection of locally advanced sigmoid colon cancer(LASCC) is sometimes difficult. Patients with LASCC have a dismal prognosis and poor quality of life, which has encouraged the evaluation of alternative multimodality treatments. This prospective study aimed to assess the feasibility and efficacy of neoadjuvant chemora?diotherapy(neo CRT) followed by surgery as treatment of selected patients with unresectable LASCC.Methods: We studied the patients with unresectable LASCC who received neo CRT followed by surgery between October 2010 and December 2012. The neoadjuvant regimen consisted of external?beam radiotherapy to 50 Gy and capecitabine?based chemotherapy every 3 weeks. Surgery was scheduled 6–8 weeks after radiotherapy.Results: Twenty?one patients were included in this study. The median follow?up was 42 months(range, 17–57 months). All patients completed neo CRT and surgery. Resection with microscopically negative margins(R0 resection) was achieved in 20 patients(95.2%). Pathologic complete response was observed in 8 patients(38.1%). Multivisceral resection was necessary in only 7 patients(33.3%). Two patients(9.5%) experienced grade 2 postopera?tive complications. No patients died within 30 days after surgery. For 18 patients with pathologic M0(yp M0) disease, the cumulative probability of 3?year local recurrence?free survival, disease?free survival and overall survival was 100.0%, 88.9% and 100.0%, respectively. For all 21 patients, the cumulative probability of 3?year overall survival was 95.2% and bladder function was well preserved.Conclusion: For patients with unresectable LASCC, preoperative chemoradiotherapy and surgery can be performed safely and may result in an increased survival rate. 展开更多
关键词 手术切除 结肠癌 患者 化疗 晚期 前放 CRT 生存率
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Single-port laparoscopic surgery for sigmoid volvulus
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作者 Byung Jo Choi Won Jun Jeong +1 位作者 Say-June Kim Sang Chul Lee 《World Journal of Gastroenterology》 SCIE CAS 2015年第8期2381-2386,共6页
AIM:To report our experience with single-port laparoscopic surgery(SPLS)for sigmoid volvulus(SV).METHODS:Between October 2009 and April 2013,10patients underwent SPLS for SV.SPLS was performed transumbilically or thro... AIM:To report our experience with single-port laparoscopic surgery(SPLS)for sigmoid volvulus(SV).METHODS:Between October 2009 and April 2013,10patients underwent SPLS for SV.SPLS was performed transumbilically or through a predetermined stoma site.Conventional straight and rigid-type laparoscopic instruments were used.After intracorporeal,segmental resection of the affected sigmoid colon,the specimen was extracted through the single-incision site.Patientdemographics and perioperative data were analyzed.RESULTS:SPLS for SV was successful in all 10 patients(4,resection and primary anastomosis;6,Hartmann’s procedure).The median operative time and postoperative hospitalization period were 168(range,85-315)min and 6.5(range,4-29)d,respectively.No intraoperative complications were noted;there were 2 postoperative complications,including 1 anastomotic leak.CONCLUSION:SPLS was a safe and feasible therapeutic approach for SV,when performed by a surgeon experienced in conventional laparoscopic surgery. 展开更多
关键词 sigmoid VOLVULUS LAPAROSCOPY SINGLE-PORT Anastomos
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More patients should undergo surgery after sigmoid volvulus
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作者 Anne Kathrine Wewer Ifversen Daniel Willy Kjaer 《World Journal of Gastroenterology》 SCIE CAS 2014年第48期18384-18389,共6页
AIM: To assess the outcome of patients treated conservatively vs surgically during their first admission for sigmoid volvulus.
关键词 sigmoid volvulus suRGERY RESECTION Percutaneous endoscopic colostomy RECURRENCE
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Volvulus of the Sigmoid Colon—Management in the Surgery “A” Department of the Teaching Hospital of Point G
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作者 Sidiki Keita Koniba Keita +7 位作者 Moussa Sissoko Mahamadou Coulibaly Lamine Soumare Oumar Sacko Sekou Koumare Adama K. Koita Soumaîla Keita Zimogo Zié Sanogo 《Surgical Science》 2020年第12期469-478,共10页
<strong>Introduction:</strong> The volvulus of the sigmoid colon is the twist of the sigmoid handle on its mesocolic axis, achieving a low occlusion by strangulation. <strong>Methodology:</strong&... <strong>Introduction:</strong> The volvulus of the sigmoid colon is the twist of the sigmoid handle on its mesocolic axis, achieving a low occlusion by strangulation. <strong>Methodology:</strong> The study was conducted in the surgery “A” department of the Teaching Hospital of Point G in Bamako. The study is retrospective and descriptive, over 5 years, ranging from January 2014 to December 2018. We conducted a comprehensive recruitment of all patients operated on for sigmoid volvulus during the study period. The only criterion for inclusion was patients operated on for volvulus of the sigmoid colon in the surgery “A” department of the Point G Hospital and the non-inclusion criteria were all patients operated on for other sigmoid pathologies without volvulation and patients operated on for other types of occlusions. <strong>Result:</strong> We conducted an exhaustive recruitment of 55 patients operated on for sigmoid volvulus during the study period. Sigmoid volvulus accounted for 13.75% of intestinal obstructions. The average age of patients was 48.013 ± 18.042 years with extremes of 24 years and 82 years. The age group 40 - 49 was the most represented at 21.8%. The sex ratio (M/F) was 8 in favour of male sex. The duration of the disease was less than 1-day in 50.94% of patients. There were two cases of ileo-sigmoid nodes. Immediate anastomosis resection was performed in 27 patients or 49.2% of cases. The time to restore continuity when specified was between 60 - 90 days and the median incision was the most common route of recovery at 80.8% of cases. The average length of hospitalization was 9 days with extremes of 2 days and 42 days. The morbidity rate was 7.3%. In our study we had 3 deaths or 5.5% of the cases. <strong>Conclusion:</strong> The volvulus of the sigmoid colon is the twist of the sigmoid handle on its mesocolic axis, achieving a low occlusion by strangulation. The volvulus of sigmoid is a serious surgical emergency that requires early diagnosis and management. In Mali, there is no validated consensus for the choice between immediate anastomosis resection if possible and multi-stage surgery. The purpose of this study is to evaluate the different surgical approaches carried out in the surgery “A” department of the Point G Hospital. 展开更多
关键词 VOLVULUS sigmoid sigmoidECTOMY Hartmann Bouilly-Volkmann ANASTOMOSIS
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基于Sigmoid函数归一化的多光谱指数特征在油茶林遥感识别和样本迁移研究中的应用
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作者 章海亮 王宇 +5 位作者 胡梅 张译之 张晶 詹白勺 刘雪梅 罗微 《光谱学与光谱分析》 北大核心 2025年第4期1159-1167,共9页
遥感影像分析中,多光谱指数特征的归一化处理对于提高分类精度和模型的泛化能力至关重要。采用Google Earth Engine(GEE)平台,以Sentinel-1 SAR雷达遥感影像和Sentinel-2 A光学遥感影像为数据源,通过计算纹理特征、地形特征、极化特征和... 遥感影像分析中,多光谱指数特征的归一化处理对于提高分类精度和模型的泛化能力至关重要。采用Google Earth Engine(GEE)平台,以Sentinel-1 SAR雷达遥感影像和Sentinel-2 A光学遥感影像为数据源,通过计算纹理特征、地形特征、极化特征和Sigmoid函数归一化前后的多光谱指数特征构建不同的分类场景,采用随机森林、梯度提升树、支持向量机和朴素贝叶斯4种机器学习分类器进行分类实验,分析对光谱指数特征进行归一化处理是否有利于油茶林识别。将构建的卷积神经网络(CNN)和结合Bi-LSTM模块的深度学习模型与机器学习分类器进行比较,分析不同模型对油茶林识别效果。以吉安市2021年五种土地类型样本点为基础,将适合油茶林识别的分类场景应用到不同年份(2019年、2020年、2022年、2023年)的样本迁移中,分析各年份油茶林面积增量与空间分布。结果表明,归一化后的光谱指数特征与随机森林相结合对油茶林识别精度最高,整体精度(OA)为99.02%,Kappa系数为0.9837,油茶林用户精度(UA)为95.31%,油茶林生产者精度(PA)为93.74%;研究中CNN系列的深度学习模型对油茶林识别精度略低于随机森林分类器,其中结合Bi-LSTM模块的深度学习模型的整体精度(OA)为98.69%,Kappa系数为0.9713油茶林用户精度(UA)为94.96%,油茶林生产者精度(PA)为93.17%;2021年吉安市油茶林种植面积达184.4881万亩,其中遂川县占27.67%,为面积最大县;油茶林种植分布由地势高向地势低递减,种植地点多位于家庭农户附近的山坡地和自留地,油茶林种植面积逐年增加。研究所提出的油茶林提取方法能够为实现油茶林动态监测与管理提供帮助,所提出的样本迁移方法能有效减少样本采集和标注成本。 展开更多
关键词 Sentinel影像 油茶 sigmoid函数 Google Earth Engine 样本迁移
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Surgical treatment of pulsatile tinnitus related to the sigmoid sinus
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作者 Yuxuan Xing Song Gao +4 位作者 Yuchen Zhou Shenghua Song Ling Lu Jie Chen Yanhong Dai 《Journal of Otology》 CSCD 2023年第1期21-25,共5页
Objective: Tinnitus-a common clinical symptom-can be categorized into pulsatile tinnitus(PT) and non-PT. Among these, PT is usually associated with sigmoid sinus symptoms, such as sigmoid sinus wall defect or divertic... Objective: Tinnitus-a common clinical symptom-can be categorized into pulsatile tinnitus(PT) and non-PT. Among these, PT is usually associated with sigmoid sinus symptoms, such as sigmoid sinus wall defect or diverticulum, for which various surgical treatments are available. We have discussed the clinical efficacy of surgery for sigmoid sinus-associated PT via the transmastoid approach in this study.Methods: We conducted a retrospective review of 4 patients who underwent surgery for sigmoid sinusassociated PT via the transmastoid approach at Nanjing Drum Tower Hospital from January to December2020. Of these, 2 patients had sigmoid sinus wall defect and 2 had sigmoid sinus diverticulum. Postoperative tinnitus grading and surgical efficacy were determined.Results: After surgery, PT dissolved in 3 patients, while tinnitus significantly decreased in 1 patient.During the follow-up period of 12-18 months, none of the 4 patients showed complications related to increased intracranial pressure or venous sinus thrombosis, and tinnitus symptoms disappeared in 3patients without recurrence, although 1 patient occasionally developed tinnitus. Postoperative thin-slice CTA of the temporal bone indicated that the sigmoid sinus bone wall defect or diverticulum was completely repaired with a thick soft tissue coverage.Conclusion: Surgical repair of sigmoid sinus-associated PT via the transmastoid approach deserves clinical promotion as it exhibited better efficiency while being relatively less invasive. 展开更多
关键词 Pulsatile tinnitus sigmoid sinus wall defect sigmoid sinus diverticulum Efficacy of surgery Transmastoid approach
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SUS301L不锈钢电阻点焊接头的微观组织和力学性能研究
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作者 杨亮 揣荣岩 +4 位作者 薛丹 刘芳 刘昆霖 刘畅 蔡桂喜 《材料研究学报》 北大核心 2025年第6期435-442,共8页
使用显微硬度仪、电子拉伸剪切试验机、SEM和IBIS等手段表征SUS301L不锈钢电阻点焊接头不同区域的微观组织、微区性能、断口形貌并研究其力学性能。结果表明,接头的熔核形貌呈椭圆形,分为母材区、热影响区和熔核区。接头熔核的边缘至核... 使用显微硬度仪、电子拉伸剪切试验机、SEM和IBIS等手段表征SUS301L不锈钢电阻点焊接头不同区域的微观组织、微区性能、断口形貌并研究其力学性能。结果表明,接头的熔核形貌呈椭圆形,分为母材区、热影响区和熔核区。接头熔核的边缘至核心区域的组织分布依次为柱状枝晶和等轴枝晶,接头的主要缺陷有熔核边缘的飞溅、熔核心部的缩孔和微裂纹,飞溅与缩孔的发生密切相关。熔核的直径是影响接头力学性能的关键因素,其力学性能与熔核直径呈正相关。随着双层板厚度的增加,单位熔核直径的增量产生的最大拉剪力增量随之显著增大。热影响区的硬度和强度均低于母材区和熔核区,导致在塑性环形成了一个软化区。这种软化区的强度较低,能承载的拉剪力较小,因此成为拉剪开裂的起始区域。拉剪断裂形式分为穿核断裂和沿核断裂,熔核的直径影响接头的断裂形式。 展开更多
关键词 金属材料 suS301L不锈钢 电阻点焊 力学性能 断裂机理 显微组织
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固体氧化物燃料电池用Ti_(3)SiC_(2)/SUS430复合双极板材料直接扩散焊接连接性能
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作者 韦守李 徐斌 +7 位作者 时婧 孙明月 程强 赵经香 常修亮 戴作强 李希超 郑莉莉 《材料科学与工程学报》 北大核心 2025年第1期62-67,共6页
本研究提出将一种Ti_(3)SiC_(2)/SUS430复合双极板材料的金属放置于阳极一侧,陶瓷放置于阴极一侧,从而避免“阴极毒化”现象。研究利用Gleeble 3500热模拟试验机在850~1150℃下对SUS430和Ti_(3)SiC_(2)进行直接扩散焊接,通过观察接头界... 本研究提出将一种Ti_(3)SiC_(2)/SUS430复合双极板材料的金属放置于阳极一侧,陶瓷放置于阴极一侧,从而避免“阴极毒化”现象。研究利用Gleeble 3500热模拟试验机在850~1150℃下对SUS430和Ti_(3)SiC_(2)进行直接扩散焊接,通过观察接头界面的微观形貌,研究了焊接温度对接头结构和组织的影响。研究结果表明,当焊接温度低于950℃时,基体元素并未发现明显的互扩散,难以获得可靠接头;当焊接温度为1050℃时,SUS430与Ti_(3)SiC_(2)陶瓷界面之间已经实现了紧密贴合,呈现出不连续的锯齿状;当焊接温度高于1150℃时,Si挥发向SUS430基体扩散,使得Ti_(3)SiC_(2)产生拓扑分解,同时Fe、Cr向Ti_(3)SiC_(2)基体扩散,界面处产生了反应层,两种材料基本实现了有效连接。由于两种材料的热膨胀性能不匹配,会出现焊接裂缝,可考虑添加中间层进行扩散焊接,以获得结合更紧密的复合双极板材料。 展开更多
关键词 固体氧化物燃料电池 Ti_(3)SiC_(2) suS430 扩散焊接 界面反应
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SUS304不锈钢极薄带电脉冲辅助拉伸试验研究
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作者 刘红艳 范婉婉 +3 位作者 杨亚玉 王炳超 和东平 王涛 《锻压技术》 北大核心 2025年第11期200-208,共9页
为了定量分析非热效应对SUS304不锈钢极薄带拉伸变形的影响,通过拉伸至相同应变(ε_(en)=30%),进行了室温拉伸、电脉冲辅助拉伸和相同温度下的加热拉伸试验。基于上述试验探究了SUS304不锈钢极薄带在不同脉冲电流下力学性能和微观组织... 为了定量分析非热效应对SUS304不锈钢极薄带拉伸变形的影响,通过拉伸至相同应变(ε_(en)=30%),进行了室温拉伸、电脉冲辅助拉伸和相同温度下的加热拉伸试验。基于上述试验探究了SUS304不锈钢极薄带在不同脉冲电流下力学性能和微观组织的变化规律。结果表明,非热效应可以使试样的加工硬化效果减弱。随着脉冲电流的增加,试样的屈服强度、抗拉强度和显微硬度逐渐降低。同时,非热效应可以使试样变形均匀,降低位错堆积,试样内晶粒尺寸逐渐增大,小角度晶界逐渐减少,孪晶界逐渐增加,促进了织构聚集。当脉冲电流增大至2.5 A时,变形晶粒的体积分数相比室温拉伸试样减少了57.5%,表明脉冲电流加速了变形晶粒在较低温度下的动态回复。 展开更多
关键词 suS304不锈钢 极薄带 脉冲电流辅助成形 非热效应 相同应变
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Adult sigmoid intussusception resembling rectal prolapse:A case report
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作者 Tsung-Jung Tsai Yu Shih Liu 《World Journal of Clinical Cases》 SCIE 2024年第6期1163-1168,共6页
BACKGROUND Rectal prolapse arises from benign etiology.When symptoms of internal intussusception mirror those of rectal prolapse,a misdiagnosis is possible,especially under limited clinical presentation.It is crucial ... BACKGROUND Rectal prolapse arises from benign etiology.When symptoms of internal intussusception mirror those of rectal prolapse,a misdiagnosis is possible,especially under limited clinical presentation.It is crucial to recognize and differentiate rectal prolapse from internal intussusception because the two diagnoses have different prognoses.Here,we describe a case of adult sigmoid intussusception presenting as rectal prolapse.CASE SUMMARY A 64-year-old woman with no known medical history visited a gastrointestinal outpatient department due to hard bloody stool defecation for 1 wk followed by constipation for 3 d.Colonoscopy revealed a huge polypoid ulcerated tumor at the sigmoid colon with lumen stenosis.The patient was admitted due to postprocedural dull abdominal pain.Due to failed colonoscopy reduction and stent insertion,the patient underwent sigmoid colon resection with primary end-to-end anastomosis,with the transverse colostomy pathological report showing adenocarcinoma,pT3N0M0.She recovered well from the operation and was discharged with regular outpatient clinic follow-up.CONCLUSION Presentation and manifestation of sigmoid intussusception may resemble that of rectal prolapse,necessitating careful observation due to distinct prognostic implications. 展开更多
关键词 sigmoid intussusception Rectal prolapse Endoscopic reduction ADENOCARCINOMA Case report
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基于DBO-LSTM的磁粒研磨SUS304细长管内表面工艺参数优化研究
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作者 唐嘉斌 郭龙文 +3 位作者 王天 肖春芳 矫彦婷 韩冰 《电镀与精饰》 北大核心 2025年第7期64-73,共10页
利用磁粒研磨技术对SUS304不锈钢细长管内表面光整加工时,由于影响研磨效果的因素众多,导致最佳工艺参数难以确定。本文设计4因素4水平正交试验,分析主轴转速、磁极进给速度、粗精加工磨粒粒径组合和粗精加工时间比对表面粗糙度值的影... 利用磁粒研磨技术对SUS304不锈钢细长管内表面光整加工时,由于影响研磨效果的因素众多,导致最佳工艺参数难以确定。本文设计4因素4水平正交试验,分析主轴转速、磁极进给速度、粗精加工磨粒粒径组合和粗精加工时间比对表面粗糙度值的影响。并构建蜣螂算法(DBO)优化长短期记忆神经网络(LSTM)的表面粗糙度预测模型,预测模型的拟合优度R^(2)为0.9769,均方根误差(RMSE)为0.0179,平均绝对误差(MAE)为0.0162。再次利用DBO算法进行全局寻优,得到最佳工艺参数组合为:主轴转速2715 r/min,外部磁极进给速度为4 mm/s,粗精加工磨粒粒径组合为80目和100目,粗精加工时间比为1.35∶1,预测的表面粗糙度Ra为0.080μm。对上述工艺参数进行微调并进行试验,结果表明:得到的表面粗糙度Ra为0.078μm,与预测值的相对误差RE约为2.56%。应用最佳工艺参数组合进行试验,在降低SUS304细长管内表面粗糙度值的同时,还能改善其表面微观形貌,提升加工效率。 展开更多
关键词 磁粒研磨 suS304细长管 DBO-LSTM预测模型 表面粗糙度值 工艺参数
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统一视角下的几个物理概念:SU(1,1)群的启示
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作者 张仁 谢吉坤 +2 位作者 马胜利 吕辰威 张威 《物理与工程》 2025年第2期67-73,共7页
通过统一的视角重新审视物理学中看似不相关的多个概念,不仅为科学研究提供了新的思路,也可以极大促进物理教学的深度和广度。本文以SU(1,1)群为例,探讨了如何将这一数学工具应用于物理学的不同领域,从而揭示其在不同物理现象中的核心... 通过统一的视角重新审视物理学中看似不相关的多个概念,不仅为科学研究提供了新的思路,也可以极大促进物理教学的深度和广度。本文以SU(1,1)群为例,探讨了如何将这一数学工具应用于物理学的不同领域,从而揭示其在不同物理现象中的核心作用。采用对比分析的研究方法,本文首先通过狭义相对论中的洛伦兹变换展示了SU(1,1)群如何帮助我们更加深刻地理解这一变换的物理本质。然后,本文转向量子力学,探讨了SU(1,1)群在描述简谐振子问题中的应用,揭示了其在量子态演化中的关键作用。在凝聚态物理领域,文章讨论了波戈留波夫变换的统一描述,强调了SU(1,1)群在理解凝聚态系统相变中的重要性。最后,文章还探讨了量子光学中的压缩态,展示了SU(1,1)群在描述光场压缩态特性中的应用,进一步揭示了其在量子信息处理中的潜力。通过SU(1,1)群的视角,本文总结了这些物理概念共同的数学基础和普适的物理规律,不仅使学生加深了对这些物理概念的理解,也促进了他们对物理对称性思想的深入认识,从而为物理教育和研究提供了新的视角和方法。 展开更多
关键词 su(1 1)群 洛伦兹变换 简谐振子 波戈留波夫变换
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