BACKGROUND A growing body of research indicates significant differences between left-sided colon cancers(LCC)and right-sided colon cancers(RCC).Pan-immune-inflammation value(PIV)is a systemic immune response marker th...BACKGROUND A growing body of research indicates significant differences between left-sided colon cancers(LCC)and right-sided colon cancers(RCC).Pan-immune-inflammation value(PIV)is a systemic immune response marker that can predict the prognosis of patients with colon cancer.However,the specific distinction between PIV of LCC and RCC remains unclear.AIM To investigate the prognostic and clinical significance of PIV in LCC and RCC patients.METHODS This multicenter retrospective cohort study included 1510 patients with colon cancer,comprising 801 with LCC and 709 with RCC.We used generalized lifting regression analysis to evaluate the relative impact of PIV on disease-free survival(DFS)in these patients.Kaplan-Meier analysis,as well as univariate and multivariate analyses,were used to examine the risk factors for DFS.The correlation between PIV and the clinical characteristics was statistically analyzed in these patients.RESULTS A total of 1510 patients{872 female patients(58%);median age 63 years[interquartile ranges(IQR):54-71];patients with LCC 801(53%);median follow-up 44.17 months(IQR 29.67-62.32)}were identified.PIV was significantly higher in patients with RCC[median(IQR):214.34(121.78-386.72)vs 175.87(111.92-286.84),P<0.001].After propensity score matching,no difference in PIV was observed between patients with LCC and RCC[median(IQR):182.42(111.88-297.65)vs 189.45(109.44-316.02);P=0.987].PIV thresholds for DFS were 227.84 in LCC and 145.99 in RCC.High PIV(>227.84)was associated with worse DFS in LCC[PIV-high:Adjusted hazard ratio(aHR)=2.39;95%confidence interval:1.70-3.38;P<0.001]but not in RCC(PIV-high:aHR=0.72;95%confidence interval:0.48-1.08;P=0.114).CONCLUSION These findings suggest that PIV may predict recurrence in patients with LCC but not RCC,underscoring the importance of tumor location when using PIV as a colon cancer biomarker.展开更多
BACKGROUND According to the latest report,colorectal cancer is still one of the most prevalent cancers,with the third highest incidence and mortality worldwide.Treatment of advanced rectal cancer with distant metastas...BACKGROUND According to the latest report,colorectal cancer is still one of the most prevalent cancers,with the third highest incidence and mortality worldwide.Treatment of advanced rectal cancer with distant metastases is usually unsatisfactory,especially for mismatch repair proficient(pMMR)rectal cancer,which leads to poor prognosis and recurrence.CASE SUMMARY We report a case of a pMMR rectal adenocarcinoma with metastases of multiple lymph nodes,including the left supraclavicular lymph node,before treatment in a 70-year-old man.He received full courses of chemoradiotherapy(CRT)followed by 4 cycles of programmed death 1 inhibitor Tislelizumab,and a pathologic complete response(pCR)was achieved,and the lesion of the left supraclavicular lymph node also disappeared.CONCLUSION pMMR advanced rectal cancer with preserved intact distant metastatic lymph nodes may benefit from full-course CRT combined with immunotherapy.展开更多
BACKGROUND Gastric adenosquamous carcinoma(ASC)is rare and characterized by coexisting of adenocarcinoma andsquamous carcinoma within the same tumor.We present a female patient with gastric ASC who had an elevated ser...BACKGROUND Gastric adenosquamous carcinoma(ASC)is rare and characterized by coexisting of adenocarcinoma andsquamous carcinoma within the same tumor.We present a female patient with gastric ASC who had an elevated serum level of alpha-fetopro-tein(AFP),which decreased to normal levels after a laparoscopic distant radical gastrectomy in a short period.The clinicopathological features in AFP-producing gastric cancer(GC)are discussed,as well as potentially available prognostic predi-ctors.CASE SUMMARY A 50-year-old woman presented to our department with a chief complain of a 6-mo history of bloating.She had no basic diseases including heart diseases and respiratory diseases,and she also denied any prior history of dysphagia,hematemesis,melena,rectal bleeding,hematochezia,or unintentional weight loss.Based on her symptoms,an esophagogastroduodenoscopy was performed,showing an annular cavity lesion 3 cm from the pylorus with a diameter of 6 cm.A biopsy of the lesion showed gastric ASC,whereas the pylorus biopsy showed normal mucosa.The patient further received an enhanced computed tomography scan which demonstrated an invasive lesion close to the pylorus with a still clear margin of the tumor to peripheral organs such as the pancreas and liver.Scattered lymph nodes were visible around,whereas no sign of liver metastasis was discovered.Serum tumor markers including carcinoembryonic antigen(CEA),cancer antigen 199(CA199),CA724,CA125,and CA242 were all normal,while the level of serum AFP increased to 172 ng/mL.A laparoscopic distant radical gastrectomy was performed after exclusion of surgical contraindications.Postoperative pathology results showed that the tumor displayed an ulcerated ASC phenotype(90%of medium to highly-differentiated squamous cell carcinoma,10%of poorly differentiated adenocarcinoma.Surprisingly,the serum level of AFP decreased to normal level on post operation day 5.The tumor cells were positive for CK5/6,p63,and CEA,and negative for AFP and Epstein-Barr encoding region.CONCLUSION We presented a rare case of gastric ASC with elevated serum AFP level,which may be new subtype of AFP-producing GC.Follow-up detection of serum AFP might be a useful tool to predict patient prognosis.展开更多
AIM: To investigate the safety and efficacy of anus-preserving rectectomy via telescopic colorectal mucosal anastomosis (TCMA) for low rectal cancer. METHODS: From August 1993 to October 2012, 420 patients including 2...AIM: To investigate the safety and efficacy of anus-preserving rectectomy via telescopic colorectal mucosal anastomosis (TCMA) for low rectal cancer. METHODS: From August 1993 to October 2012, 420 patients including 253 males and 167 females with low rectal cancer underwent transabdominal and transanal anterior resection, followed by TCMA. The distance be-tween the anus and inferior margin of the tumor ranged from 5 to 7 cm, and was 5 cm in 6 patients, 6 cm in 127, and 7 cm in 287 patients. Tumor-node-metastasis staging showed that 136 patients had stage Ⅰ, 252 had stage Ⅱ and 32 had stage Ⅲ. Fifty-six patients with T3 or over received preoperative neoadjuvant chemoradio-therapy. RESULTS: The postoperative follow-up rate was 91.9% (386/420) with a median time of 6.4 years. All 420 pa-tients underwent radical resection. No postoperativedeath occurred. Postoperative complications included anastomotic leakage in 13 (3.1%) patients and anas-tomotic stenosis in 7 (1.6%). The local recurrence rate after surgery was 6.2%, the hepatic metastasis rate was 13.2% and the pulmonary metastasis rate was 2.3%. The 5-year survival rate was 74.0% and the disease-free survival rate was 71.0%. Kirwan classification showed that continence was good in 94.4% of patients with stage I when scored 12 mo after resection. CONCLUSION: TCMA for patients with low rectal cancer leads to better quality of life and satisfactory defecation function, and lowers anastomotic leakage occurrence, and might be one of the safe operative procedures in anus-preserving rectectomy.展开更多
AIM:To assess laparoscopic radical resection of lower rectal cancer with telescopic anastomosis through transanal resection without abdominal incisions.METHODS:From March 2010 to June 2014, 30 patients(14 men and 16 w...AIM:To assess laparoscopic radical resection of lower rectal cancer with telescopic anastomosis through transanal resection without abdominal incisions.METHODS:From March 2010 to June 2014, 30 patients(14 men and 16 women, aged 36-78 years, mean age 59.8 years) underwent laparoscopic radical resection of lower rectal cancer with telescopic anastomosis through anus-preserving transanal resection.The tumors were 5-7 cm away from the anal margin in 24 cases, and 4 cm in six cases.In preoperative assessment, there were 21 cases of T1N0M0 and nine of T2N0M0.Through the middle approach, the sigmoid mesentery was freed at the root with an ultrasonic scalpel and the roots of the inferior mesenteric artery and vein were dissected, clamped and cut.Following the total mesorectal excision principle, the rectum was separated until the anorectal ring reached 3-5 cm from the distal end of the tumor.For perineal surgery, a ring incision was made 2 cm above the dentate line, and sharp dissection was performed submucosally towards the superior direction, until the plane of the levator ani muscle, to transect the rectum.The rectum and distal sigmoid colon were removed together from the anus, followed by a telescopic anastomosis between the full thickness of the proximal colon and the mucosa and submucosal tissue of the rectum.RESULTS:For the present cohort of 30 cases,the mean operative time was 178 min,with an average of 13 positive lymph nodes detected.One case of postoperative anastomotic leak was observed,requiring temporary colostomy,which was closed and recovered3 mo later.The postoperative pathology showed T1-T2N0M0 in 19 cases and T2N1M0 in 11 cases.Twelve months after surgery,94.4%patients achieved anal function Kirwan grade 1,indicating that their analfunction returned to normal.The patients were followed up for 1-36 mo,with an average of 23 mo.There was no local recurrence,and 17 patients survived for>3years(with a survival rate of 100%).CONCLUSION:Laparoscopic radical resection of lower rectal cancer with telescopic anastomosis through transanal resection without abdominal incisions is safe and feasible.展开更多
Intestinal hemolymphangioma is a rare vascular and lymphatic malformation and is manifested as anaemia and recurrent alimentary tract hemorrhage. Few cases of hemolymphangioma occurring in small intestine, spleen, eso...Intestinal hemolymphangioma is a rare vascular and lymphatic malformation and is manifested as anaemia and recurrent alimentary tract hemorrhage. Few cases of hemolymphangioma occurring in small intestine, spleen, esophagus and other organs have been reported. We herein report a case of a 37-year-old man with severe rectal bleeding. Digital examination revealed nodular mucosa. No rectal mass was palpated, but bleeding in the ampulla was detected. Colonoscopy revealed an extensive hypervascular submucosal lesion arising from the rectosigmoid junction colon to the distal edge of the anus. Endoscopic ultrasonography demonstrated an extensive anechoic mass with clear edge. Magnetic resonance imaging (MRI) showed a significant thickness of the rectal wall, extending to the distal edge of the anus, with a narrowing lumen. A sphinctersaving rectal surgery was performed. Due to a lack of knowledge of the clinical, endoscopic and radiological features, preoperative recognition of hemolymphangioma is not easy. Computed tomography and MRI are helpful in confirming the diagnosis, and defining the extent and invasion of the lesion. For the low malignant potential tumors, a sphincter-saving rectal surgery is recommended after a full evaluation of the tumor.展开更多
Small bowel volvulus,which is torsion of the small bowel and its mesentery,is a medical emergency,and is categorized as primary or secondary type. Primary type often occurs without any apparent intrinsic anatomical an...Small bowel volvulus,which is torsion of the small bowel and its mesentery,is a medical emergency,and is categorized as primary or secondary type. Primary type often occurs without any apparent intrinsic anatomical anomalies,while the secondary type is common clinically and could be caused by numerous factors including postoperative adhesions,intestinal diverticulum,and/or tumors. Here,we report a rare case of a 60-year-old man diagnosed with small bowel volvulus using multidetector computed tomography(MDCT) angiography. Further discovery by laparotomy showed one jejunal diverticulum,longer corresponding mesentery with a narrower insertion,and a lack of mesenteric fat. This case report includes several etiological factors of small bowel volvulus,and we discuss the possible cause of small bowel volvulus in this patient. We also highlight the importance of MDCT angiography in the diagnosis of volvulus and share our experience in treating this disease.展开更多
This paper proposes a dual-motor configuration to enhance closed-loop performance of a telescope control system. Two identical motors are mounted on each side of a U-type frame to drive the telescope elevation axis in...This paper proposes a dual-motor configuration to enhance closed-loop performance of a telescope control system. Two identical motors are mounted on each side of a U-type frame to drive the telescope elevation axis instead of a single motor drive, which is usually used in a classical design. This new configuration and mechanism can reduce the motor to half the size used in the former design, and it also provides some other advantages. A master-slave current control mode is employed to synchronize the two motors. Acceleration feedback control is utilized to further enhance the servo performance. Extensive experiments are used to validate the effectiveness of the proposed control algorithm in synchronization, disturbance attenuation and low-velocity tracking.展开更多
To the Editor:Laparoscopic radical nephrectomy(LRN)is the standard of care for patients with T2 tumors and localized masses not treatable by partial nephrectomy according to the European Association of Urology Guideli...To the Editor:Laparoscopic radical nephrectomy(LRN)is the standard of care for patients with T2 tumors and localized masses not treatable by partial nephrectomy according to the European Association of Urology Guidelines on renal cell carcinoma.[1]Transperitoneal and retroperitoneal are two main approaches in LRN.With the advantages of easier hilar control,shorter operation time,and less bowel irritation,retroperitoneal approach is preferable in our center.The peritoneal tear is a common intraoperative complication during retroperitoneoscopic procedures,leading to the collapse of the retroperitoneal space.展开更多
We study a generalization of the vertex cover problem. For a given graph with weights on the vertices and an integer k, we aim to find a subset of the vertices with minimum total weight, so that at least k edges in th...We study a generalization of the vertex cover problem. For a given graph with weights on the vertices and an integer k, we aim to find a subset of the vertices with minimum total weight, so that at least k edges in the graph are covered. The problem is called the k-partial vertex cover problem. There are some 2-approximation algorithms for the problem. In the paper we do not improve on the approximation ratios of the previous algorithms, but we derive an iterative rounding algorithm. We present our technique in two algorithms. The first is an iterative rounding algorithm and gives a （2 ＋ Q/OPT ）-approximation for the k-partial vertex cover problem where Q is the largest finite weight in the problem definition and OPT is the optimal value for the instance. The second algorithm uses the first as a subroutine and achieves an approximation ratio of 2.展开更多
基金Supported by National High Level Hospital Clinical Research Funding,No.2022-PUMCH-B-003.
文摘BACKGROUND A growing body of research indicates significant differences between left-sided colon cancers(LCC)and right-sided colon cancers(RCC).Pan-immune-inflammation value(PIV)is a systemic immune response marker that can predict the prognosis of patients with colon cancer.However,the specific distinction between PIV of LCC and RCC remains unclear.AIM To investigate the prognostic and clinical significance of PIV in LCC and RCC patients.METHODS This multicenter retrospective cohort study included 1510 patients with colon cancer,comprising 801 with LCC and 709 with RCC.We used generalized lifting regression analysis to evaluate the relative impact of PIV on disease-free survival(DFS)in these patients.Kaplan-Meier analysis,as well as univariate and multivariate analyses,were used to examine the risk factors for DFS.The correlation between PIV and the clinical characteristics was statistically analyzed in these patients.RESULTS A total of 1510 patients{872 female patients(58%);median age 63 years[interquartile ranges(IQR):54-71];patients with LCC 801(53%);median follow-up 44.17 months(IQR 29.67-62.32)}were identified.PIV was significantly higher in patients with RCC[median(IQR):214.34(121.78-386.72)vs 175.87(111.92-286.84),P<0.001].After propensity score matching,no difference in PIV was observed between patients with LCC and RCC[median(IQR):182.42(111.88-297.65)vs 189.45(109.44-316.02);P=0.987].PIV thresholds for DFS were 227.84 in LCC and 145.99 in RCC.High PIV(>227.84)was associated with worse DFS in LCC[PIV-high:Adjusted hazard ratio(aHR)=2.39;95%confidence interval:1.70-3.38;P<0.001]but not in RCC(PIV-high:aHR=0.72;95%confidence interval:0.48-1.08;P=0.114).CONCLUSION These findings suggest that PIV may predict recurrence in patients with LCC but not RCC,underscoring the importance of tumor location when using PIV as a colon cancer biomarker.
基金Supported by National Natural Science Foundation of China,No.81870393.
文摘BACKGROUND According to the latest report,colorectal cancer is still one of the most prevalent cancers,with the third highest incidence and mortality worldwide.Treatment of advanced rectal cancer with distant metastases is usually unsatisfactory,especially for mismatch repair proficient(pMMR)rectal cancer,which leads to poor prognosis and recurrence.CASE SUMMARY We report a case of a pMMR rectal adenocarcinoma with metastases of multiple lymph nodes,including the left supraclavicular lymph node,before treatment in a 70-year-old man.He received full courses of chemoradiotherapy(CRT)followed by 4 cycles of programmed death 1 inhibitor Tislelizumab,and a pathologic complete response(pCR)was achieved,and the lesion of the left supraclavicular lymph node also disappeared.CONCLUSION pMMR advanced rectal cancer with preserved intact distant metastatic lymph nodes may benefit from full-course CRT combined with immunotherapy.
基金the National Natural Science Foundation of China,No.81970500,81571563 and 81870393.
文摘BACKGROUND Gastric adenosquamous carcinoma(ASC)is rare and characterized by coexisting of adenocarcinoma andsquamous carcinoma within the same tumor.We present a female patient with gastric ASC who had an elevated serum level of alpha-fetopro-tein(AFP),which decreased to normal levels after a laparoscopic distant radical gastrectomy in a short period.The clinicopathological features in AFP-producing gastric cancer(GC)are discussed,as well as potentially available prognostic predi-ctors.CASE SUMMARY A 50-year-old woman presented to our department with a chief complain of a 6-mo history of bloating.She had no basic diseases including heart diseases and respiratory diseases,and she also denied any prior history of dysphagia,hematemesis,melena,rectal bleeding,hematochezia,or unintentional weight loss.Based on her symptoms,an esophagogastroduodenoscopy was performed,showing an annular cavity lesion 3 cm from the pylorus with a diameter of 6 cm.A biopsy of the lesion showed gastric ASC,whereas the pylorus biopsy showed normal mucosa.The patient further received an enhanced computed tomography scan which demonstrated an invasive lesion close to the pylorus with a still clear margin of the tumor to peripheral organs such as the pancreas and liver.Scattered lymph nodes were visible around,whereas no sign of liver metastasis was discovered.Serum tumor markers including carcinoembryonic antigen(CEA),cancer antigen 199(CA199),CA724,CA125,and CA242 were all normal,while the level of serum AFP increased to 172 ng/mL.A laparoscopic distant radical gastrectomy was performed after exclusion of surgical contraindications.Postoperative pathology results showed that the tumor displayed an ulcerated ASC phenotype(90%of medium to highly-differentiated squamous cell carcinoma,10%of poorly differentiated adenocarcinoma.Surprisingly,the serum level of AFP decreased to normal level on post operation day 5.The tumor cells were positive for CK5/6,p63,and CEA,and negative for AFP and Epstein-Barr encoding region.CONCLUSION We presented a rare case of gastric ASC with elevated serum AFP level,which may be new subtype of AFP-producing GC.Follow-up detection of serum AFP might be a useful tool to predict patient prognosis.
基金Supported by Grants from the National Natural Science Foundation of China,No.81041025 and 81000189
文摘AIM: To investigate the safety and efficacy of anus-preserving rectectomy via telescopic colorectal mucosal anastomosis (TCMA) for low rectal cancer. METHODS: From August 1993 to October 2012, 420 patients including 253 males and 167 females with low rectal cancer underwent transabdominal and transanal anterior resection, followed by TCMA. The distance be-tween the anus and inferior margin of the tumor ranged from 5 to 7 cm, and was 5 cm in 6 patients, 6 cm in 127, and 7 cm in 287 patients. Tumor-node-metastasis staging showed that 136 patients had stage Ⅰ, 252 had stage Ⅱ and 32 had stage Ⅲ. Fifty-six patients with T3 or over received preoperative neoadjuvant chemoradio-therapy. RESULTS: The postoperative follow-up rate was 91.9% (386/420) with a median time of 6.4 years. All 420 pa-tients underwent radical resection. No postoperativedeath occurred. Postoperative complications included anastomotic leakage in 13 (3.1%) patients and anas-tomotic stenosis in 7 (1.6%). The local recurrence rate after surgery was 6.2%, the hepatic metastasis rate was 13.2% and the pulmonary metastasis rate was 2.3%. The 5-year survival rate was 74.0% and the disease-free survival rate was 71.0%. Kirwan classification showed that continence was good in 94.4% of patients with stage I when scored 12 mo after resection. CONCLUSION: TCMA for patients with low rectal cancer leads to better quality of life and satisfactory defecation function, and lowers anastomotic leakage occurrence, and might be one of the safe operative procedures in anus-preserving rectectomy.
基金Supported by National Natural Science Foundation of China,No.81041025 and No.81000189
文摘AIM:To assess laparoscopic radical resection of lower rectal cancer with telescopic anastomosis through transanal resection without abdominal incisions.METHODS:From March 2010 to June 2014, 30 patients(14 men and 16 women, aged 36-78 years, mean age 59.8 years) underwent laparoscopic radical resection of lower rectal cancer with telescopic anastomosis through anus-preserving transanal resection.The tumors were 5-7 cm away from the anal margin in 24 cases, and 4 cm in six cases.In preoperative assessment, there were 21 cases of T1N0M0 and nine of T2N0M0.Through the middle approach, the sigmoid mesentery was freed at the root with an ultrasonic scalpel and the roots of the inferior mesenteric artery and vein were dissected, clamped and cut.Following the total mesorectal excision principle, the rectum was separated until the anorectal ring reached 3-5 cm from the distal end of the tumor.For perineal surgery, a ring incision was made 2 cm above the dentate line, and sharp dissection was performed submucosally towards the superior direction, until the plane of the levator ani muscle, to transect the rectum.The rectum and distal sigmoid colon were removed together from the anus, followed by a telescopic anastomosis between the full thickness of the proximal colon and the mucosa and submucosal tissue of the rectum.RESULTS:For the present cohort of 30 cases,the mean operative time was 178 min,with an average of 13 positive lymph nodes detected.One case of postoperative anastomotic leak was observed,requiring temporary colostomy,which was closed and recovered3 mo later.The postoperative pathology showed T1-T2N0M0 in 19 cases and T2N1M0 in 11 cases.Twelve months after surgery,94.4%patients achieved anal function Kirwan grade 1,indicating that their analfunction returned to normal.The patients were followed up for 1-36 mo,with an average of 23 mo.There was no local recurrence,and 17 patients survived for>3years(with a survival rate of 100%).CONCLUSION:Laparoscopic radical resection of lower rectal cancer with telescopic anastomosis through transanal resection without abdominal incisions is safe and feasible.
基金Supported by National Natural Science Foundation of China,No. 81000189
文摘Intestinal hemolymphangioma is a rare vascular and lymphatic malformation and is manifested as anaemia and recurrent alimentary tract hemorrhage. Few cases of hemolymphangioma occurring in small intestine, spleen, esophagus and other organs have been reported. We herein report a case of a 37-year-old man with severe rectal bleeding. Digital examination revealed nodular mucosa. No rectal mass was palpated, but bleeding in the ampulla was detected. Colonoscopy revealed an extensive hypervascular submucosal lesion arising from the rectosigmoid junction colon to the distal edge of the anus. Endoscopic ultrasonography demonstrated an extensive anechoic mass with clear edge. Magnetic resonance imaging (MRI) showed a significant thickness of the rectal wall, extending to the distal edge of the anus, with a narrowing lumen. A sphinctersaving rectal surgery was performed. Due to a lack of knowledge of the clinical, endoscopic and radiological features, preoperative recognition of hemolymphangioma is not easy. Computed tomography and MRI are helpful in confirming the diagnosis, and defining the extent and invasion of the lesion. For the low malignant potential tumors, a sphincter-saving rectal surgery is recommended after a full evaluation of the tumor.
基金Supported by National Natural Science Foundation of China,No.81372364 and No.81000189General Financial Grant from the China Postdoctoral Science Foundation,No.2014M552695
文摘Small bowel volvulus,which is torsion of the small bowel and its mesentery,is a medical emergency,and is categorized as primary or secondary type. Primary type often occurs without any apparent intrinsic anatomical anomalies,while the secondary type is common clinically and could be caused by numerous factors including postoperative adhesions,intestinal diverticulum,and/or tumors. Here,we report a rare case of a 60-year-old man diagnosed with small bowel volvulus using multidetector computed tomography(MDCT) angiography. Further discovery by laparotomy showed one jejunal diverticulum,longer corresponding mesentery with a narrower insertion,and a lack of mesenteric fat. This case report includes several etiological factors of small bowel volvulus,and we discuss the possible cause of small bowel volvulus in this patient. We also highlight the importance of MDCT angiography in the diagnosis of volvulus and share our experience in treating this disease.
文摘This paper proposes a dual-motor configuration to enhance closed-loop performance of a telescope control system. Two identical motors are mounted on each side of a U-type frame to drive the telescope elevation axis instead of a single motor drive, which is usually used in a classical design. This new configuration and mechanism can reduce the motor to half the size used in the former design, and it also provides some other advantages. A master-slave current control mode is employed to synchronize the two motors. Acceleration feedback control is utilized to further enhance the servo performance. Extensive experiments are used to validate the effectiveness of the proposed control algorithm in synchronization, disturbance attenuation and low-velocity tracking.
基金National Natural Science Foundation of China(No.81400701)。
文摘To the Editor:Laparoscopic radical nephrectomy(LRN)is the standard of care for patients with T2 tumors and localized masses not treatable by partial nephrectomy according to the European Association of Urology Guidelines on renal cell carcinoma.[1]Transperitoneal and retroperitoneal are two main approaches in LRN.With the advantages of easier hilar control,shorter operation time,and less bowel irritation,retroperitoneal approach is preferable in our center.The peritoneal tear is a common intraoperative complication during retroperitoneoscopic procedures,leading to the collapse of the retroperitoneal space.
基金Supported by the National Natural Science Foundation of China(No.11201021)
文摘We study a generalization of the vertex cover problem. For a given graph with weights on the vertices and an integer k, we aim to find a subset of the vertices with minimum total weight, so that at least k edges in the graph are covered. The problem is called the k-partial vertex cover problem. There are some 2-approximation algorithms for the problem. In the paper we do not improve on the approximation ratios of the previous algorithms, but we derive an iterative rounding algorithm. We present our technique in two algorithms. The first is an iterative rounding algorithm and gives a （2 ＋ Q/OPT ）-approximation for the k-partial vertex cover problem where Q is the largest finite weight in the problem definition and OPT is the optimal value for the instance. The second algorithm uses the first as a subroutine and achieves an approximation ratio of 2.
