BACKGROUND： Laparoscopic pancreaticoduodenectomy（LPD）is a safe procedure. Oncological safety of LPD is still a matter for debate. This study aimed to compare the oncological outcomes,in terms of adequacy of resecti...BACKGROUND： Laparoscopic pancreaticoduodenectomy（LPD）is a safe procedure. Oncological safety of LPD is still a matter for debate. This study aimed to compare the oncological outcomes,in terms of adequacy of resection and recurrence rate following LPD and open pancreaticoduodenectomy（OPD）.METHODS： Between November 2005 and April 2009, 12LPDs（9 ampullary and 3 distal common bile duct tumors）were performed. A cohort of 12 OPDs were matched for age,gender, body mass index（BMI） and American Society of Anesthesiologists（ASA） score and tumor site.RESULTS： Mean tumor size LPD vs OPD（19.8 vs 19.2 mm,P=0.870）. R0 resection was achieved in 9 LPD vs 8 OPD（P=1.000）. The mean number of metastatic lymph nodes and total number resected for LPD vs OPD were 1.1 vs 2.1（P=0.140）and 20.7 vs 18.5（P=0.534） respectively. Clavien complications grade I/II（5 vs 8）, III/IV（2 vs 6） and pancreatic leak（2 vs 1）were statistically not significant（LPD vs OPD）. The mean high dependency unit（HDU） stay was longer in OPD（3.7 vs 1.4 days,P〈0.001）. There were 2 recurrences each in LPD and OPD（logrank,P=0.983）. Overall mortality for LPD vs OPD was 3 vs 6（log-rank, P=0.283） and recurrence-related mortality was 2 vs 1.There was one death within 30 days in the OPD group secondary to severe sepsis and none in the LPD group.CONCLUSIONS： Compared to open procedure, LPD achieved a similar rate of R0 resection, lymph node harvest and longterm recurrence for tumors less than 2 cm. Though technically challenging, LPD is safe and does not compromise oncological outcome.展开更多
AIM:To report our experience of gastrointestinal stromal tumors (GISTs) during the last 29 years. METHODS:Thirty two cases of GIST referred to our Institution from the 1st January 1981 to the 10th June 2010 were revie...AIM:To report our experience of gastrointestinal stromal tumors (GISTs) during the last 29 years. METHODS:Thirty two cases of GIST referred to our Institution from the 1st January 1981 to the 10th June 2010 were reviewed. Metastases,recurrence and survival data were collected in relation to age,history,clinical presentation,location,size,resection margins and cellular features. RESULTS:Mean age was 63.7 years (range,40-90) and incidence was slightly higher in males (56%). R0 resection was performed in 90.7% of cases,R1 in 6.2% (2 cases) and R2 in 3.1% (one case). Using Fletcher's classification 8/32 (25%) had high risk,9/32 (28%) intermediate and 15/32 (47%) low risk tumors. Follow-up varied from 1 mo to 29 years,with a median of 8 years; overall survival was 75% (24/32),disease-free survival was 72% and tumor-related mortality was 9.3%. Three patients with high risk GIST were treated with imatinib mesylate:one developed a recurrence after 36 mo,and 2 are free from disease at 41 mo. CONCLUSION:Surgical treatment remains the gold standard therapy for resectable GISTs. Pathological and biological features of the neoplasm represent the most important factors predicting the prognosis.展开更多
Oceanic lithosphere is generated at divergent plate boundaries and disappears at convergent plate boundaries.Seafloor spreading and plate subduction together constitute the physical coupling and mass conservation rela...Oceanic lithosphere is generated at divergent plate boundaries and disappears at convergent plate boundaries.Seafloor spreading and plate subduction together constitute the physical coupling and mass conservation relationships to the movement of lithospheres on Earth.Subduction zones are a key site for the transfer of both matter and energy at converging plate boundaries,and their study has been the hot spot and frontier of Earth system science since the development of plate tectonics theory.As far as the dynamic regime and geothermal gradient of convergent plate margins are concerned,they have different properties in different stages of the subduction zone evolution.In general,the early low-angle subduction leads to compressional tectonism dominated by low geothermal gradients at the plate interface,and the late high-angle subduction results in extensional tectonism dominated by high geothermal gradients at the plate interface and its hanging wall.Active rifts are produced along suture zones through not only slab rollback or slab breakoff in the terminal stage of oceanic subduction but also foundering and thinning of the lithosphere in the post-subduction stage.Due to the differences and changes in the geometric and thermobaric structures of convergent plate margins,a series of changes in the type of metamorphism and magmatism can occur in active and fossil subduction zones.Dehydration and melting of the subducting oceanic crust are prominent at subarc depths,giving rise to fluids that dissolve different concentrations of fluid-mobile incompatible elements.The subduction zone fluids at subarc depths would chemically react with the overlying mantle wedge peridotite,generating metasomatites as the mantle sources of mafic magmas in oceanic and continental arcs.However,these metasomatites did not partially melt immediately upon the fluid metasomatism to trigger arc magmatism,and they did not melt until they were heated by asthenospheric convection due to rollback of the subducting slab.Therefore,recognition of the c展开更多
As an effective tracer, nitrogen isotopes have been used to determine the source of ore materials in recent years. In this study, the nitrogen isotopes and contents were measured on K-feldspar and sericite of gold dep...As an effective tracer, nitrogen isotopes have been used to determine the source of ore materials in recent years. In this study, the nitrogen isotopes and contents were measured on K-feldspar and sericite of gold deposits and some related granitic intrusions in Jiaodong, Xiao-qinling-Xiong’ershan, west Qinling, the west part of North Qilian and the Zhangjiakou-Xuanhua district around the North China craton (NCC). Although the gold deposits around the NCC are hosted in Precambrian metamorphic rocks, Phanerozoic sedimentary rocks, mafic volcanic rocks or granite, comparison of which with the nitrogen contents and isotope data of previous studies on mantle-derived rocks, granites, metamorphic rocks and gold deposits indicates that those deposits are closely related to granitic rocks. In addition, mantle-derived materials may have been involved in the ore-forming processes to a certain degree. This conclusion is consistent with the result of previous hydrogen, oxygen and carbon isotopic studies of those gold deposits.展开更多
Liver resection is the treatment of choice for patients with colorectal liver metastases(CLM).However,major resections are often required to achieve R0 resection,which are associated with substantial rates of morbidit...Liver resection is the treatment of choice for patients with colorectal liver metastases(CLM).However,major resections are often required to achieve R0 resection,which are associated with substantial rates of morbidity and mortality.Maximizing the amount of residual liver gained increasing significance in modern liver surgery due to the high incidence of chemotherapyassociated parenchymal injury.This fact,along with the progressive expansion of resectability criteria,has led to the development of a surgical philosophy known as "parenchymal-sparing liver surgery"(PSLS).This philosophy includes a variety of resection strategies,either performed alone or in combination with ablative therapies.A profound knowledge of liver anatomy and expert intraoperative ultrasound skills are required to perform PSLS appropriately and safely.There is a clear trend toward PSLS in hepatobiliary centers worldwide as current evidence indicates that tumor biology is the most important predictor of intrahepatic recurrence and survival,rather than the extent of a negative resection margin.Tumor removal avoiding the unnecessary sacrifice of functional parenchyma has been associated with less surgical stress,fewer postoperative complications,uncompromised cancer-related outcomes and higher feasibility of future resections.The increasing evidence supporting PSLS prompts its consideration as the gold-standard surgical approach for CLM.展开更多
The Santanghu area is located on the northeastern margin of the Junggar Basin,northern Xinjiang,Northwest China.The Carboniferous volcanic rocks in this area are widely distributed in Kaokesaiergaishan,Santanghu,Dahei...The Santanghu area is located on the northeastern margin of the Junggar Basin,northern Xinjiang,Northwest China.The Carboniferous volcanic rocks in this area are widely distributed in Kaokesaiergaishan,Santanghu,Daheishan and Naomaohu districts,which are located to the north of the Kalameili Fault.These rocks,sourced from a cognate magma,consist of basic,intermediate,and acidic lavas,and pyroclastic rock.The basic volcanic rocks are enriched with large-ion lithophile elements(LILE),but are relatively depleted in high field strength elements(HFSE),and have an obvious negative Nb-Ta-Ti anomaly.They were most probably derived from a depleted mantle source,and during their ascent,these magmas were not contaminated by the crustal material as they underwent magma crystallization differentiation.Based on the Carboniferous volcanic assemblage and geochemical data,it is apparent that the early Carboniferous volcanism occurred in a subduction-related tectonic setting.New LA-ICP-MS zircon U-Pb analyses constrain the age of the andesite within the volcanic rocks as the early Carboniferous(328.9-331.3 Ma).Combined with the regional geological record,comprehensive analysis of the isotope geochronological data indicates that the subduction of the Junggar Ocean predates the early Carboniferous,and that the Santanghu island arc magmatism was induced by the subduction of the Junggar Ocean in the Carboniferous.展开更多
Concept-based orogenic gold exploration requires a scale-integrated approach using a robust mineral system model.Most genetic hypotheses for orogenic gold deposits that involve near-surface or magmatic-hydrothermal fl...Concept-based orogenic gold exploration requires a scale-integrated approach using a robust mineral system model.Most genetic hypotheses for orogenic gold deposits that involve near-surface or magmatic-hydrothermal fluids are now negated in terms of a global mineral system model.Plausible models involve metamorphic fluids,but the fluid source has been equivocal.Crustal metamorphic-fluid models are most widely-accepted but there are serious problems for Archean deposits,and numerous Chinese provinces,including Jiaodong,where the only feasible fluid source is sub-crustal.If all orogenic gold deposits define a coherent mineral system,there are only two realistic sources of fluid and gold,based on their syn-mineralization geodynamic settings.These are from devolatilization of a subducted oceanic slab with its overlying gold-bearing sulfide-rich sedimentary package,or release from mantle lithosphere that was metasomatized and fertilized during a subduction event,particularly adjacent to craton margins.In this model,CO_2 is generated during decarbonation and S and ore-related elements released from transformation of pyrite to pyrrhotite at about 500 ℃.This orogenic gold mineral system can be applied to conceptual exploration by first identifying the required settings at geodynamic to deposit scales.Within these settings,it is then possible to define the critical gold mineralization processes in the system:fertility,architecture,and preservation.The geological parameters that define these processes,and the geological,geophysical and geochemical proxies and responses for these critical parameters can then be identified.At the geodynamic to province scales,critical processes include a tectonic thermal engine and deep,effective,fluid plumbing system driven by seismic swarms up lithosphere-scale faults in an oblique-slip regime during uplift late in the orogenic cycle of a convergent margin.At the district to deposit scale,the important processes are fluid focussing into regions of complex structural geometry adjacent to 展开更多
The impulse to remain profitable by increasing agricultural production levels in view of the greater demand for food, provided impetus to production intensification. The aim of this review is to summarise current lite...The impulse to remain profitable by increasing agricultural production levels in view of the greater demand for food, provided impetus to production intensification. The aim of this review is to summarise current literature, reporting specifically on the impact of production intensification on habitats and yield constraints caused by weeds. Secondly, in alleviating these effects over the short term, ecological measures that enhance species diversity in conserved habitats and promote semi-natural habitats in the agricultural landscape, are discussed. In large-scale intensive agriculture, weed control is predominantly rooted in agrochemical applications in the form of herbicides. Long lasting intensive agricultural practices show discord both with the promotion of the biodiversity of microbes belowground and aboveground and with organisms involved in the breaking down of plant material. The presence of native species in the surroundings, in combination with hedgerows and field margins, with a comparatively intricate and balanced variety of plants in a sheltered environment, are essential for settlement of benign insects, particularly in the face of intensive agricultural production. The promising tactic of advantageous seed predators enables decreased herbicide applications. Crop mosaics arranged to advance compatibility at the landscape scale are important to bolster pollination services and insect management, while ecological variety in the surroundings acts as a safety net for habitat diversity. Weed control in combination with different tactics of vegetation use, comprising cover cropping, hedgerows and field margins, sets up safe havens in the landscape, and improves the diffusion of complementary life forms. Field margins perform a meaningful natural function as point of provision for forage, safe havens and distribution passageways for pollinators and insect predators. Production practices that promote more heterogeneity and combine high density semi-natural safe havens and habitat conservation in agro ecosy展开更多
The primary goal of breast-conserving surgery(BCS) is to obtain tumour-free resection margins. Margins positive or focally positive for tumour cells are associated with a high risk of local recurrence, and in the case...The primary goal of breast-conserving surgery(BCS) is to obtain tumour-free resection margins. Margins positive or focally positive for tumour cells are associated with a high risk of local recurrence, and in the case of tumour-positive margins, re-excision or even mastectomy are sometimes needed to achieve definite clear margins. Unfortunately, tumour-involved margins and re-excisions after lumpectomy are still reported in up to 40% of patients and additionally, unnecessary large excision volumes are described. A secondary goal of BCS is the cosmetic outcome and one of the main determinants of worse cosmetic outcome is a large excision volume. Up to 30% of unsatisfied cosm-etic outcome is reported. Therefore, the search for better surgical techniques to improve margin status, excision volume and consequently, cosmetic outcome has continued. Nowadays, the most commonly used localization methods for BCS of non-palpable breast cancers are wire-guided localization(WGL) and radioguided localization(RGL). WGL and RGL are invasive procedures that need to be performed pre-operatively with technical and scheduling difficulties. For palpable breast cancer, tumour excision is usually guided by tactile skills of the surgeon performing "blind" surgery. One of the surgical techniques pursuing the aims of radicality and small excision volumes includes intraoperative ultrasound(IOUS). The best evidence available demonstrates benefits of IOUS with a significantly high proportion of negative margins compared with other localization techniques in palpable and non-palpable breast cancer. Additionally, IOUS is non-invasive, easy to learn and can centralize the tumour in the excised specimen with low amount of healthy breast tissuebeing excised. This could lead to better cosmetic results of BCS. Despite the advantages of IOUS, only a small amount of surgeons are performing this technique. This review aims to highlight the position of ultrasoundguided surgery for malignant breast tumours in the search for better oncological and cosmet展开更多
The development of information and communications technologyv(ICT),particularly the Internet,has reduced trade costs.However,it remains unclear whether these reduced costs are reflected in the “extensive margins”of ...The development of information and communications technologyv(ICT),particularly the Internet,has reduced trade costs.However,it remains unclear whether these reduced costs are reflected in the “extensive margins”of firms'exports(which refer to the probability of firms exporting)or the “intensive margins”(which refer to the value of firms'export).To test this,we used the concepts of information cost and binary margins,an augmented trade model of firm heterogeneity,a two-stage Heckman estimation,and data from the World Bank Enterprise Survey of Chinese firms in 2012.The results revealed that reduced trade costs from the use of ICT were positively related to extensive margins but that the connection with intensive margins was not significant.The results lead to the conclusion that reduced information costs related to a firm's exporting behavior were primarily reflcted in variable trade cosis.This study offers theoretical and empirical evidence for China 3 policies towards the Internet,which are relevant for the export of manufactured goods.The government should encourage the use of ICT to enhance firms export opporunities while facing current trade policy uncerainty.展开更多
Uncertainty impact of random geometric variations on the aerodynamic performance of low-pressure turbine blades is considerable,which is further amplified by the current ultra-high-lift design trend for weight reducti...Uncertainty impact of random geometric variations on the aerodynamic performance of low-pressure turbine blades is considerable,which is further amplified by the current ultra-high-lift design trend for weight reduction.Therefore,this uncertainty impact on ultra-highly loaded blades under extreme operational conditions near the margins with potential large-scale open separation is focused on in this study.It is demonstrated that this impact is significant,unfavourable,and nonlinear,which is clearly severer under extreme conditions.In addition to the overall attenuation and notable scattering of specific performance,the operational margins with open separation are also notably scattered with great risk of significant reduction.This scattering and nonlinearity are dominated by the variations in leading-edge thickness.The thinning of leading edge triggers local transition,enhancing downstream friction and reducing resistance to open separation,which is further exacerbated by operational deterioration.However,the opposite thickening yields less benefit,implying nonlinearity.This unfavourable impact highlights the need for robust aerodynamic design,where both a safer operational condition and a more robust blade are indispensable,i.e.,a compromise among performance,weight,and robustness.Besides the necessary limitation of loading levels,a mid-loaded design is recommended to reduce adverse pressure gradients in both the leading edge and rear region of the suction side,which helps to decrease the susceptibility of the transition and open separation to random perturbations.Similar improvements can also be achieved by appropriately thickening the leading edge.展开更多
How do Chinese agricultural exports to ASEAN（Association of Southeast Asian Nations） evolve？ And what factors affected the evolution pattern？ This study measures the trade margins of Chinese agricultural exports t...How do Chinese agricultural exports to ASEAN（Association of Southeast Asian Nations） evolve？ And what factors affected the evolution pattern？ This study measures the trade margins of Chinese agricultural exports to ASEAN by utilizing the 2000-2015 Harmonized System＇s six-digit agricultural trade data, and further analyzes their determinants by developing an augmented gravity model of international trade. The results indicate that, the main growth source of Chinese agricultural exports to ASEAN has shifted from the extensive margin before the formal establishment of CAFTA（China-ASEAN Free Trade Area） in 2010 to the intensive margin since the formal establishment of CAFTA, but changes in Chinese agricultural exports to ASEAN have always mainly depended on the intensive margin. Since the formal establishment of CAFTA, the evolution pattern of Chinese agricultural exports to ASEAN has shifted from ＂more varieties, low price, and small quantity＂ to ＂less varieties, high price, and large quantity＂. Relative economic scale, relative population scale, capacity of agricultural export, trade integration, global financial crisis, and common border significantly affect the trade margins of Chinese agricultural exports to ASEAN.展开更多
Background Although many midterm oncologic data have been reported for extraperitoneal laparoscopic radical prostatectomy （ELRP） in western countries, few oncologic data of the extraperitoneal procedure was publish...Background Although many midterm oncologic data have been reported for extraperitoneal laparoscopic radical prostatectomy （ELRP） in western countries, few oncologic data of the extraperitoneal procedure was published in China. The aim of the study was to evaluate the oncologic outcomes of patients treated with ELRP in China.Methods From January 2005 to March 2010, a total of 152 consecutive patients diagnosed with clinically localized prostate cancer were included in this study and treated with ELRP. The patients were staged according to the TNM （tumor, nodes, metastases） system. Median and mean postoperative follow-up were 28.1 months and 27.0 months, respectively. The patients were retrospectively analyzed for progression-free survival.Results One hundred and twelve cases （73.7%） were postoperatively diagnosed as pT2 in, and 40 cases （26.3%） as pT3. Positive lymph nodes were shown in 5 patients （3.3%）. Gleason score was 〈7 in 49 men （32.2%）, 7 in 69 men （45.4%）, and 〉7 in 34 men （22.4%）. Positive surgical margins （PSM） were observed in 15 patients （9.9%）, which included 32.0% of all pT3a cases and 46.7% of all pT3b cases, respectively. The overall prostate-specific antigen recurrence-free survival rate was 86% in all patients. The recurrence-free survival rates were 91.8% and 62.2% in pT2N0 patients and pT3N0 patients, respectively. Preoperative prostate-specific antigen, surgical margins, tumor stage, and lymph nodal status were identified as independent predictors of biochemical recurrence-free survival using multivariate Cox proportional hazard model. Conclusions ELRP is a precise, safe and effective procedure at this particular Chinese institution. The prognostic power of prostate-specific antigen relapse after ELRP is not identical to that described previously with transperitoneal or open retropubic approaches.展开更多
Background: A reduced residual dentine thickness following crown preparation has a conceivable impact on pulp degeneration by increasing the pulp’s susceptibility to injury. In crown preparations, three different fin...Background: A reduced residual dentine thickness following crown preparation has a conceivable impact on pulp degeneration by increasing the pulp’s susceptibility to injury. In crown preparations, three different finishing lines are used. These are shoulder, chamfer, and knife edge. Each with its comparative advantages and disadvantages. There is inadequate scientific evidence on which of these finishing lines will leave the most amount of residual dentine, after standard crown preparations on mandibular incisors and maxillary lateral incisors to preserve their pulpal health. Objective: To evaluate residual dentine thickness following various cervical finishing lines of anterior crown preparations for zirconia full coverage. Materials and Methods: A prospective comparative study was conducted from September 2<sup>nd</sup> to November 5<sup>th</sup>, 2022, using mandibular incisors and maxillary laterals extracted from individuals between ages 18 to 30. Each of the three groups of teeth was randomly divided into three cervical margin preparations as follows: Shoulder (n = 15), chamfer (n = 15), and knife edge (n = 15). The teeth were disinfected and stored in 10% formalin. Silicone impressions followed by crown preparations were done on teeth mounted on phantom head manikins. The teeth were sectioned 0.5 mm coronal to the cemento-enamel junction using a separating disc and the mesial, distal, buccal, and lingual thickness were measured using a digital caliper. ANOVA analysis was applied to assess the difference in mean residual dentine thickness among the finishing lines and the Tukey test used for mean comparison. Results: Knife edge finishing lines had 2.05 mm of residual dentine thickness, for upper lateral incisors lingually and had an amount of 1.55 mm and 1.47 mm for lower central teeth mesially and distally respectively. Shoulder finishing lines had an amount of 0.58 mm for lower lateral incisors mesially. Interproximal areas had the least amounts of residual dentine for shoulder and chamfer finishing lin展开更多
Background:Positive surgical margins are independent risk factor for biochemical recurrence,local recurrence,and distant metastasis after radical prostatectomy.However,limited predictive tools are available.This study...Background:Positive surgical margins are independent risk factor for biochemical recurrence,local recurrence,and distant metastasis after radical prostatectomy.However,limited predictive tools are available.This study aimed to develop and validate a preoperative nomogram for predicting positive surgical margins after laparoscopic radical prostatectomy(LRP).Methods:From January 2010 to March 2016,a total of 418 patients who underwent LRP without receiving neoadjuvant therapy at Peking University Third Hospital were retrospectively involved in this study.Clinical and pathological results of each patient were collected for further analysis.Univariable and multivariable logistic regression(backward stepwise method)were used for the nomogram development.The concordance index(CI),calibration curve analysis and decision curve analysis were used to evaluate the performance of our model.Results:Of 418 patients involved in this study,142 patients(34.0%)had a positive surgical margin on final pathology.Based on the backward selection,four variables were included in the final multivariable regression model,including the percentage of positive cores in preoperative biopsy,clinical stage,free prostate specific antigen(fPSA)/total PSA(tPSA),and age.A nomogram was developed using these four variables.The concordance index(C-index)of the nomogram was 0.722 in the development cohort and 0.700 in the bootstrap validations.The bias-corrected calibration plot showed a limited departure from the ideal line with a mean absolute error of 2.0%.In decision curve analyses,the nomogram showed net benefits in the range from 0.2 to 0.7.Conclusion:A nomogram to predict positive surgical margins after LRP was developed and validated,which could help urologists plan surgical procedures.展开更多
文摘BACKGROUND： Laparoscopic pancreaticoduodenectomy（LPD）is a safe procedure. Oncological safety of LPD is still a matter for debate. This study aimed to compare the oncological outcomes,in terms of adequacy of resection and recurrence rate following LPD and open pancreaticoduodenectomy（OPD）.METHODS： Between November 2005 and April 2009, 12LPDs（9 ampullary and 3 distal common bile duct tumors）were performed. A cohort of 12 OPDs were matched for age,gender, body mass index（BMI） and American Society of Anesthesiologists（ASA） score and tumor site.RESULTS： Mean tumor size LPD vs OPD（19.8 vs 19.2 mm,P=0.870）. R0 resection was achieved in 9 LPD vs 8 OPD（P=1.000）. The mean number of metastatic lymph nodes and total number resected for LPD vs OPD were 1.1 vs 2.1（P=0.140）and 20.7 vs 18.5（P=0.534） respectively. Clavien complications grade I/II（5 vs 8）, III/IV（2 vs 6） and pancreatic leak（2 vs 1）were statistically not significant（LPD vs OPD）. The mean high dependency unit（HDU） stay was longer in OPD（3.7 vs 1.4 days,P〈0.001）. There were 2 recurrences each in LPD and OPD（logrank,P=0.983）. Overall mortality for LPD vs OPD was 3 vs 6（log-rank, P=0.283） and recurrence-related mortality was 2 vs 1.There was one death within 30 days in the OPD group secondary to severe sepsis and none in the LPD group.CONCLUSIONS： Compared to open procedure, LPD achieved a similar rate of R0 resection, lymph node harvest and longterm recurrence for tumors less than 2 cm. Though technically challenging, LPD is safe and does not compromise oncological outcome.
文摘AIM:To report our experience of gastrointestinal stromal tumors (GISTs) during the last 29 years. METHODS:Thirty two cases of GIST referred to our Institution from the 1st January 1981 to the 10th June 2010 were reviewed. Metastases,recurrence and survival data were collected in relation to age,history,clinical presentation,location,size,resection margins and cellular features. RESULTS:Mean age was 63.7 years (range,40-90) and incidence was slightly higher in males (56%). R0 resection was performed in 90.7% of cases,R1 in 6.2% (2 cases) and R2 in 3.1% (one case). Using Fletcher's classification 8/32 (25%) had high risk,9/32 (28%) intermediate and 15/32 (47%) low risk tumors. Follow-up varied from 1 mo to 29 years,with a median of 8 years; overall survival was 75% (24/32),disease-free survival was 72% and tumor-related mortality was 9.3%. Three patients with high risk GIST were treated with imatinib mesylate:one developed a recurrence after 36 mo,and 2 are free from disease at 41 mo. CONCLUSION:Surgical treatment remains the gold standard therapy for resectable GISTs. Pathological and biological features of the neoplasm represent the most important factors predicting the prognosis.
基金the project on the development strategy of subduction zones that was supported not only by a fund from the Chinese Academy of Sciences(2015-2016)by a joint fund from the National Natural Science Foundation of China and the Chinese Academy of Sciences(2018-2019)supported by the National Natural Science Foundation of China(Grant No.92155306)。
文摘Oceanic lithosphere is generated at divergent plate boundaries and disappears at convergent plate boundaries.Seafloor spreading and plate subduction together constitute the physical coupling and mass conservation relationships to the movement of lithospheres on Earth.Subduction zones are a key site for the transfer of both matter and energy at converging plate boundaries,and their study has been the hot spot and frontier of Earth system science since the development of plate tectonics theory.As far as the dynamic regime and geothermal gradient of convergent plate margins are concerned,they have different properties in different stages of the subduction zone evolution.In general,the early low-angle subduction leads to compressional tectonism dominated by low geothermal gradients at the plate interface,and the late high-angle subduction results in extensional tectonism dominated by high geothermal gradients at the plate interface and its hanging wall.Active rifts are produced along suture zones through not only slab rollback or slab breakoff in the terminal stage of oceanic subduction but also foundering and thinning of the lithosphere in the post-subduction stage.Due to the differences and changes in the geometric and thermobaric structures of convergent plate margins,a series of changes in the type of metamorphism and magmatism can occur in active and fossil subduction zones.Dehydration and melting of the subducting oceanic crust are prominent at subarc depths,giving rise to fluids that dissolve different concentrations of fluid-mobile incompatible elements.The subduction zone fluids at subarc depths would chemically react with the overlying mantle wedge peridotite,generating metasomatites as the mantle sources of mafic magmas in oceanic and continental arcs.However,these metasomatites did not partially melt immediately upon the fluid metasomatism to trigger arc magmatism,and they did not melt until they were heated by asthenospheric convection due to rollback of the subducting slab.Therefore,recognition of the c
基金This work was supported by the Ministry of Science and Technology of China (Grant No. G1999043211).
文摘As an effective tracer, nitrogen isotopes have been used to determine the source of ore materials in recent years. In this study, the nitrogen isotopes and contents were measured on K-feldspar and sericite of gold deposits and some related granitic intrusions in Jiaodong, Xiao-qinling-Xiong’ershan, west Qinling, the west part of North Qilian and the Zhangjiakou-Xuanhua district around the North China craton (NCC). Although the gold deposits around the NCC are hosted in Precambrian metamorphic rocks, Phanerozoic sedimentary rocks, mafic volcanic rocks or granite, comparison of which with the nitrogen contents and isotope data of previous studies on mantle-derived rocks, granites, metamorphic rocks and gold deposits indicates that those deposits are closely related to granitic rocks. In addition, mantle-derived materials may have been involved in the ore-forming processes to a certain degree. This conclusion is consistent with the result of previous hydrogen, oxygen and carbon isotopic studies of those gold deposits.
文摘Liver resection is the treatment of choice for patients with colorectal liver metastases(CLM).However,major resections are often required to achieve R0 resection,which are associated with substantial rates of morbidity and mortality.Maximizing the amount of residual liver gained increasing significance in modern liver surgery due to the high incidence of chemotherapyassociated parenchymal injury.This fact,along with the progressive expansion of resectability criteria,has led to the development of a surgical philosophy known as "parenchymal-sparing liver surgery"(PSLS).This philosophy includes a variety of resection strategies,either performed alone or in combination with ablative therapies.A profound knowledge of liver anatomy and expert intraoperative ultrasound skills are required to perform PSLS appropriately and safely.There is a clear trend toward PSLS in hepatobiliary centers worldwide as current evidence indicates that tumor biology is the most important predictor of intrahepatic recurrence and survival,rather than the extent of a negative resection margin.Tumor removal avoiding the unnecessary sacrifice of functional parenchyma has been associated with less surgical stress,fewer postoperative complications,uncompromised cancer-related outcomes and higher feasibility of future resections.The increasing evidence supporting PSLS prompts its consideration as the gold-standard surgical approach for CLM.
基金supported by Land and Resources Survey Project of China(Grant No. 1212011085009)the Sinopec Project "Study and Map Compilation for Structure,Lithofacies,and Paleogeography in Northwestern China" (Grant No. YPH08103)National Natural Science Foundation of China (Grant No. 40802051)
文摘The Santanghu area is located on the northeastern margin of the Junggar Basin,northern Xinjiang,Northwest China.The Carboniferous volcanic rocks in this area are widely distributed in Kaokesaiergaishan,Santanghu,Daheishan and Naomaohu districts,which are located to the north of the Kalameili Fault.These rocks,sourced from a cognate magma,consist of basic,intermediate,and acidic lavas,and pyroclastic rock.The basic volcanic rocks are enriched with large-ion lithophile elements(LILE),but are relatively depleted in high field strength elements(HFSE),and have an obvious negative Nb-Ta-Ti anomaly.They were most probably derived from a depleted mantle source,and during their ascent,these magmas were not contaminated by the crustal material as they underwent magma crystallization differentiation.Based on the Carboniferous volcanic assemblage and geochemical data,it is apparent that the early Carboniferous volcanism occurred in a subduction-related tectonic setting.New LA-ICP-MS zircon U-Pb analyses constrain the age of the andesite within the volcanic rocks as the early Carboniferous(328.9-331.3 Ma).Combined with the regional geological record,comprehensive analysis of the isotope geochronological data indicates that the subduction of the Junggar Ocean predates the early Carboniferous,and that the Santanghu island arc magmatism was induced by the subduction of the Junggar Ocean in the Carboniferous.
基金partly funded by the National Natural Science Foundation of China(Grant Nos.41230311,41572069,41702070)the National Key Research and Development Project of China(2016YFC0600307)+2 种基金the National Key Research Program of China(Grant Nos.2016YFC0600107-4 and 2016YFC0600307)the MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(Grant No.MSFGPMR201804)the 111 Project of the Ministry of Science and Technology,China(Grant No.BP0719021)。
文摘Concept-based orogenic gold exploration requires a scale-integrated approach using a robust mineral system model.Most genetic hypotheses for orogenic gold deposits that involve near-surface or magmatic-hydrothermal fluids are now negated in terms of a global mineral system model.Plausible models involve metamorphic fluids,but the fluid source has been equivocal.Crustal metamorphic-fluid models are most widely-accepted but there are serious problems for Archean deposits,and numerous Chinese provinces,including Jiaodong,where the only feasible fluid source is sub-crustal.If all orogenic gold deposits define a coherent mineral system,there are only two realistic sources of fluid and gold,based on their syn-mineralization geodynamic settings.These are from devolatilization of a subducted oceanic slab with its overlying gold-bearing sulfide-rich sedimentary package,or release from mantle lithosphere that was metasomatized and fertilized during a subduction event,particularly adjacent to craton margins.In this model,CO_2 is generated during decarbonation and S and ore-related elements released from transformation of pyrite to pyrrhotite at about 500 ℃.This orogenic gold mineral system can be applied to conceptual exploration by first identifying the required settings at geodynamic to deposit scales.Within these settings,it is then possible to define the critical gold mineralization processes in the system:fertility,architecture,and preservation.The geological parameters that define these processes,and the geological,geophysical and geochemical proxies and responses for these critical parameters can then be identified.At the geodynamic to province scales,critical processes include a tectonic thermal engine and deep,effective,fluid plumbing system driven by seismic swarms up lithosphere-scale faults in an oblique-slip regime during uplift late in the orogenic cycle of a convergent margin.At the district to deposit scale,the important processes are fluid focussing into regions of complex structural geometry adjacent to
文摘The impulse to remain profitable by increasing agricultural production levels in view of the greater demand for food, provided impetus to production intensification. The aim of this review is to summarise current literature, reporting specifically on the impact of production intensification on habitats and yield constraints caused by weeds. Secondly, in alleviating these effects over the short term, ecological measures that enhance species diversity in conserved habitats and promote semi-natural habitats in the agricultural landscape, are discussed. In large-scale intensive agriculture, weed control is predominantly rooted in agrochemical applications in the form of herbicides. Long lasting intensive agricultural practices show discord both with the promotion of the biodiversity of microbes belowground and aboveground and with organisms involved in the breaking down of plant material. The presence of native species in the surroundings, in combination with hedgerows and field margins, with a comparatively intricate and balanced variety of plants in a sheltered environment, are essential for settlement of benign insects, particularly in the face of intensive agricultural production. The promising tactic of advantageous seed predators enables decreased herbicide applications. Crop mosaics arranged to advance compatibility at the landscape scale are important to bolster pollination services and insect management, while ecological variety in the surroundings acts as a safety net for habitat diversity. Weed control in combination with different tactics of vegetation use, comprising cover cropping, hedgerows and field margins, sets up safe havens in the landscape, and improves the diffusion of complementary life forms. Field margins perform a meaningful natural function as point of provision for forage, safe havens and distribution passageways for pollinators and insect predators. Production practices that promote more heterogeneity and combine high density semi-natural safe havens and habitat conservation in agro ecosy
文摘The primary goal of breast-conserving surgery(BCS) is to obtain tumour-free resection margins. Margins positive or focally positive for tumour cells are associated with a high risk of local recurrence, and in the case of tumour-positive margins, re-excision or even mastectomy are sometimes needed to achieve definite clear margins. Unfortunately, tumour-involved margins and re-excisions after lumpectomy are still reported in up to 40% of patients and additionally, unnecessary large excision volumes are described. A secondary goal of BCS is the cosmetic outcome and one of the main determinants of worse cosmetic outcome is a large excision volume. Up to 30% of unsatisfied cosm-etic outcome is reported. Therefore, the search for better surgical techniques to improve margin status, excision volume and consequently, cosmetic outcome has continued. Nowadays, the most commonly used localization methods for BCS of non-palpable breast cancers are wire-guided localization(WGL) and radioguided localization(RGL). WGL and RGL are invasive procedures that need to be performed pre-operatively with technical and scheduling difficulties. For palpable breast cancer, tumour excision is usually guided by tactile skills of the surgeon performing "blind" surgery. One of the surgical techniques pursuing the aims of radicality and small excision volumes includes intraoperative ultrasound(IOUS). The best evidence available demonstrates benefits of IOUS with a significantly high proportion of negative margins compared with other localization techniques in palpable and non-palpable breast cancer. Additionally, IOUS is non-invasive, easy to learn and can centralize the tumour in the excised specimen with low amount of healthy breast tissuebeing excised. This could lead to better cosmetic results of BCS. Despite the advantages of IOUS, only a small amount of surgeons are performing this technique. This review aims to highlight the position of ultrasoundguided surgery for malignant breast tumours in the search for better oncological and cosmet
基金the Major Programs of National Social Science Foundation of China(Nos.18ZDA095 and 17VDL012)the Ministary of Education of China Youth Fund Program(No.17YJC790110)the Department of Education of Liaoning Province's Youth Fund Program(No.LN2017QN017).
文摘The development of information and communications technologyv(ICT),particularly the Internet,has reduced trade costs.However,it remains unclear whether these reduced costs are reflected in the “extensive margins”of firms'exports(which refer to the probability of firms exporting)or the “intensive margins”(which refer to the value of firms'export).To test this,we used the concepts of information cost and binary margins,an augmented trade model of firm heterogeneity,a two-stage Heckman estimation,and data from the World Bank Enterprise Survey of Chinese firms in 2012.The results revealed that reduced trade costs from the use of ICT were positively related to extensive margins but that the connection with intensive margins was not significant.The results lead to the conclusion that reduced information costs related to a firm's exporting behavior were primarily reflcted in variable trade cosis.This study offers theoretical and empirical evidence for China 3 policies towards the Internet,which are relevant for the export of manufactured goods.The government should encourage the use of ICT to enhance firms export opporunities while facing current trade policy uncerainty.
基金This study was supported by the National Science and Technology Major Project,China(No.J2019-II-0012-0032),which is gratefully acknowledged.
文摘Uncertainty impact of random geometric variations on the aerodynamic performance of low-pressure turbine blades is considerable,which is further amplified by the current ultra-high-lift design trend for weight reduction.Therefore,this uncertainty impact on ultra-highly loaded blades under extreme operational conditions near the margins with potential large-scale open separation is focused on in this study.It is demonstrated that this impact is significant,unfavourable,and nonlinear,which is clearly severer under extreme conditions.In addition to the overall attenuation and notable scattering of specific performance,the operational margins with open separation are also notably scattered with great risk of significant reduction.This scattering and nonlinearity are dominated by the variations in leading-edge thickness.The thinning of leading edge triggers local transition,enhancing downstream friction and reducing resistance to open separation,which is further exacerbated by operational deterioration.However,the opposite thickening yields less benefit,implying nonlinearity.This unfavourable impact highlights the need for robust aerodynamic design,where both a safer operational condition and a more robust blade are indispensable,i.e.,a compromise among performance,weight,and robustness.Besides the necessary limitation of loading levels,a mid-loaded design is recommended to reduce adverse pressure gradients in both the leading edge and rear region of the suction side,which helps to decrease the susceptibility of the transition and open separation to random perturbations.Similar improvements can also be achieved by appropriately thickening the leading edge.
基金supported by the National Natural Science Foundation of China (71703157)the National Statistical Science Research Program of China (2016LY29)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences,China (ASTIP-IAED-2018-06)
文摘How do Chinese agricultural exports to ASEAN（Association of Southeast Asian Nations） evolve？ And what factors affected the evolution pattern？ This study measures the trade margins of Chinese agricultural exports to ASEAN by utilizing the 2000-2015 Harmonized System＇s six-digit agricultural trade data, and further analyzes their determinants by developing an augmented gravity model of international trade. The results indicate that, the main growth source of Chinese agricultural exports to ASEAN has shifted from the extensive margin before the formal establishment of CAFTA（China-ASEAN Free Trade Area） in 2010 to the intensive margin since the formal establishment of CAFTA, but changes in Chinese agricultural exports to ASEAN have always mainly depended on the intensive margin. Since the formal establishment of CAFTA, the evolution pattern of Chinese agricultural exports to ASEAN has shifted from ＂more varieties, low price, and small quantity＂ to ＂less varieties, high price, and large quantity＂. Relative economic scale, relative population scale, capacity of agricultural export, trade integration, global financial crisis, and common border significantly affect the trade margins of Chinese agricultural exports to ASEAN.
基金This study was supported by the grants from the National Natural Science Foundation of China （No. 81001136 and No. 30973006） and Shanghai Committee of Science and Technology General Program for Medicine （No. 10411963600）.
文摘Background Although many midterm oncologic data have been reported for extraperitoneal laparoscopic radical prostatectomy （ELRP） in western countries, few oncologic data of the extraperitoneal procedure was published in China. The aim of the study was to evaluate the oncologic outcomes of patients treated with ELRP in China.Methods From January 2005 to March 2010, a total of 152 consecutive patients diagnosed with clinically localized prostate cancer were included in this study and treated with ELRP. The patients were staged according to the TNM （tumor, nodes, metastases） system. Median and mean postoperative follow-up were 28.1 months and 27.0 months, respectively. The patients were retrospectively analyzed for progression-free survival.Results One hundred and twelve cases （73.7%） were postoperatively diagnosed as pT2 in, and 40 cases （26.3%） as pT3. Positive lymph nodes were shown in 5 patients （3.3%）. Gleason score was 〈7 in 49 men （32.2%）, 7 in 69 men （45.4%）, and 〉7 in 34 men （22.4%）. Positive surgical margins （PSM） were observed in 15 patients （9.9%）, which included 32.0% of all pT3a cases and 46.7% of all pT3b cases, respectively. The overall prostate-specific antigen recurrence-free survival rate was 86% in all patients. The recurrence-free survival rates were 91.8% and 62.2% in pT2N0 patients and pT3N0 patients, respectively. Preoperative prostate-specific antigen, surgical margins, tumor stage, and lymph nodal status were identified as independent predictors of biochemical recurrence-free survival using multivariate Cox proportional hazard model. Conclusions ELRP is a precise, safe and effective procedure at this particular Chinese institution. The prognostic power of prostate-specific antigen relapse after ELRP is not identical to that described previously with transperitoneal or open retropubic approaches.
文摘Background: A reduced residual dentine thickness following crown preparation has a conceivable impact on pulp degeneration by increasing the pulp’s susceptibility to injury. In crown preparations, three different finishing lines are used. These are shoulder, chamfer, and knife edge. Each with its comparative advantages and disadvantages. There is inadequate scientific evidence on which of these finishing lines will leave the most amount of residual dentine, after standard crown preparations on mandibular incisors and maxillary lateral incisors to preserve their pulpal health. Objective: To evaluate residual dentine thickness following various cervical finishing lines of anterior crown preparations for zirconia full coverage. Materials and Methods: A prospective comparative study was conducted from September 2<sup>nd</sup> to November 5<sup>th</sup>, 2022, using mandibular incisors and maxillary laterals extracted from individuals between ages 18 to 30. Each of the three groups of teeth was randomly divided into three cervical margin preparations as follows: Shoulder (n = 15), chamfer (n = 15), and knife edge (n = 15). The teeth were disinfected and stored in 10% formalin. Silicone impressions followed by crown preparations were done on teeth mounted on phantom head manikins. The teeth were sectioned 0.5 mm coronal to the cemento-enamel junction using a separating disc and the mesial, distal, buccal, and lingual thickness were measured using a digital caliper. ANOVA analysis was applied to assess the difference in mean residual dentine thickness among the finishing lines and the Tukey test used for mean comparison. Results: Knife edge finishing lines had 2.05 mm of residual dentine thickness, for upper lateral incisors lingually and had an amount of 1.55 mm and 1.47 mm for lower central teeth mesially and distally respectively. Shoulder finishing lines had an amount of 0.58 mm for lower lateral incisors mesially. Interproximal areas had the least amounts of residual dentine for shoulder and chamfer finishing lin
文摘Background:Positive surgical margins are independent risk factor for biochemical recurrence,local recurrence,and distant metastasis after radical prostatectomy.However,limited predictive tools are available.This study aimed to develop and validate a preoperative nomogram for predicting positive surgical margins after laparoscopic radical prostatectomy(LRP).Methods:From January 2010 to March 2016,a total of 418 patients who underwent LRP without receiving neoadjuvant therapy at Peking University Third Hospital were retrospectively involved in this study.Clinical and pathological results of each patient were collected for further analysis.Univariable and multivariable logistic regression(backward stepwise method)were used for the nomogram development.The concordance index(CI),calibration curve analysis and decision curve analysis were used to evaluate the performance of our model.Results:Of 418 patients involved in this study,142 patients(34.0%)had a positive surgical margin on final pathology.Based on the backward selection,four variables were included in the final multivariable regression model,including the percentage of positive cores in preoperative biopsy,clinical stage,free prostate specific antigen(fPSA)/total PSA(tPSA),and age.A nomogram was developed using these four variables.The concordance index(C-index)of the nomogram was 0.722 in the development cohort and 0.700 in the bootstrap validations.The bias-corrected calibration plot showed a limited departure from the ideal line with a mean absolute error of 2.0%.In decision curve analyses,the nomogram showed net benefits in the range from 0.2 to 0.7.Conclusion:A nomogram to predict positive surgical margins after LRP was developed and validated,which could help urologists plan surgical procedures.
