Objective: Accurate detection and classification of breast lesions in early stage is crucial to timely formulate effective treatments for patients. We aim to develop a fully automatic system to detect and classify bre...Objective: Accurate detection and classification of breast lesions in early stage is crucial to timely formulate effective treatments for patients. We aim to develop a fully automatic system to detect and classify breast lesions using multiple contrast-enhanced mammography(CEM) images.Methods: In this study, a total of 1,903 females who underwent CEM examination from three hospitals were enrolled as the training set, internal testing set, pooled external testing set and prospective testing set. Here we developed a CEM-based multiprocess detection and classification system(MDCS) to perform the task of detection and classification of breast lesions. In this system, we introduced an innovative auxiliary feature fusion(AFF)algorithm that could intelligently incorporates multiple types of information from CEM images. The average freeresponse receiver operating characteristic score(AFROC-Score) was presented to validate system’s detection performance, and the performance of classification was evaluated by area under the receiver operating characteristic curve(AUC). Furthermore, we assessed the diagnostic value of MDCS through visual analysis of disputed cases,comparing its performance and efficiency with that of radiologists and exploring whether it could augment radiologists’ performance.Results: On the pooled external and prospective testing sets, MDCS always maintained a high standalone performance, with AFROC-Scores of 0.953 and 0.963 for detection task, and AUCs for classification were 0.909[95% confidence interval(95% CI): 0.822-0.996] and 0.912(95% CI: 0.840-0.985), respectively. It also achieved higher sensitivity than all senior radiologists and higher specificity than all junior radiologists on pooled external and prospective testing sets. Moreover, MDCS performed superior diagnostic efficiency with an average reading time of 5 seconds, compared to the radiologists’ average reading time of 3.2 min. The average performance of all radiologists was also improved to varying degrees with MDCS assistance.Conclusions: MDCS demonstrated excellent performance in the detection and classification of breast lesions,and greatly enhanced the overall performance of radiologists.展开更多
Wave energy is one of the most abundant renewable clean energy sources,and has been widely studied because of its advantages of continuity and low seasonal variation.However,its low capture efficiency and narrow captu...Wave energy is one of the most abundant renewable clean energy sources,and has been widely studied because of its advantages of continuity and low seasonal variation.However,its low capture efficiency and narrow capture frequency bandwidth are still technical bottlenecks that restrict the commercial application of wave energy converters(WECs).In recent years,using a nonlinear stiffness mechanism(NSM)for passive control has provided a new way to solve these technical bottlenecks.This literature review focuses on the research performed on the use of nonlinear mechanisms in wave energy device utilization,including the conceptual design of a mechanism,hydrodynamic models,dynamic characteristics,response mechanisms,and some examples of experimental verification.Finally,future research directions are discussed and recommended.展开更多
Let C be an extriangulated category and T be any n-cluster tilting subcategory of C.We consider the index with respect to T and introduce the index Grothendieck group of T.Using the index,we prove that the index Groth...Let C be an extriangulated category and T be any n-cluster tilting subcategory of C.We consider the index with respect to T and introduce the index Grothendieck group of T.Using the index,we prove that the index Grothendieck group of T is isomorphic to the Grothendieck group of C,which implies that the index Grothendieck groups of any two n-cluster tilting subcategories are isomorphic.In particular,we show that the split Grothendieck groups of any two 2-cluster tilting subcategories are isomorphic.Then we develop a general framework for c-vectors of 2-Calabi-Yau extriangulated categories with respect to arbitrary 2-cluster tilting subcategories.We show that the c-vectors have the sign-coherence property and provide some formulas for calculating c-vectors.展开更多
Background:Although soil erosion plays a key role in the carbon cycle,a holistic and mechanistic understanding of the soil erosion process within the cycle is still lacking.The aim of this study was therefore to impro...Background:Although soil erosion plays a key role in the carbon cycle,a holistic and mechanistic understanding of the soil erosion process within the cycle is still lacking.The aim of this study was therefore to improve our mechanistic understanding of soil organic carbon(SOC)and soil respiration dynamics through an experiment conducted in an eroding black soil farmland landscape in Northeast China.Results:The depositional profiles store 5.9 times more SOC than the eroding profiles and 3.3 times more SOC than the non-eroding profiles.A linear correlation between the SOC and 137Cs(Caesium-137)was observed in our study,suggesting that the SOC decreased with increased soil erosion.Furthermore,the fractions of intermediate C and the microaggregate C were lowest at the eroding position and highest at the depositional position.In the depositional topsoil,the input of labile materials plays a promotional role in soil respiration.Conversely,in the subsoil(i.e.,below 10 cm),the potential mineralization rates were lowest at the depositional position—due to effective stabilization by physical protection within soil microaggregates.The field results of soil surface respiration also suggest that the depositional topsoil SOC is prone to be mineralized and that SOC at this depositional context is stabilized at subsoil depth.In addition,the high water contents at the depositional position can limit the decomposition rates and stabilize the SOC at the same time.Conclusions:The findings from this study support that a majority of the SOC at footslope is stored within most of the soil profile(i.e.,below 10 cm)and submitted to long-term stabilization,and meanwhile support that the depositional profile emits more CO2 than the summit due to its high amount and quality of SOC.展开更多
Relationships among productivity,leaf phenology,and seasonal variation in moisture and light availability are poorly understood for evergreen broadleaved tropical/subtropical forests,which contribute 25% of terrestria...Relationships among productivity,leaf phenology,and seasonal variation in moisture and light availability are poorly understood for evergreen broadleaved tropical/subtropical forests,which contribute 25% of terrestrial productivity.On the one hand,as moisture availability declines,trees shed leaves to reduce transpiration and the risk of hydraulic failure.On the other hand,increases in light availability promote the replacement of senescent leaves to increase productivity.Here,we provide a comprehensive framework that relates the seasonality of climate,leaf abscission,and leaf productivity across the evergreen broadleaved tropical/subtropical forest biome.The seasonal correlation between rainfall and light availability varies from strongly negative to strongly positive across the tropics and maps onto the seasonal correlation between litterfall mass and productivity for 68 forests.Where rainfall and light covary positively,litterfall and productivity also covary positively and are always greater in the wetter sunnier season.Where rainfall and light covary negatively,litterfall and productivity are always greater in the drier and sunnier season if moisture supplies remain adequate;otherwise productivity is smaller in the drier sunnier season.This framework will improve the representation of tropical/subtropical forests in Earth system models and suggests how phenology and productivity will change as climate change alters the seasonality of cloud cover and rainfall across tropical/subtropical forests.展开更多
基金supported by the National Natural Science Foundation of China (No.82001775, 82371933)the Natural Science Foundation of Shandong Province of China (No.ZR2021MH120)+1 种基金the Special Fund for Breast Disease Research of Shandong Medical Association (No.YXH2021ZX055)the Taishan Scholar Foundation of Shandong Province of China (No.tsgn202211378)。
文摘Objective: Accurate detection and classification of breast lesions in early stage is crucial to timely formulate effective treatments for patients. We aim to develop a fully automatic system to detect and classify breast lesions using multiple contrast-enhanced mammography(CEM) images.Methods: In this study, a total of 1,903 females who underwent CEM examination from three hospitals were enrolled as the training set, internal testing set, pooled external testing set and prospective testing set. Here we developed a CEM-based multiprocess detection and classification system(MDCS) to perform the task of detection and classification of breast lesions. In this system, we introduced an innovative auxiliary feature fusion(AFF)algorithm that could intelligently incorporates multiple types of information from CEM images. The average freeresponse receiver operating characteristic score(AFROC-Score) was presented to validate system’s detection performance, and the performance of classification was evaluated by area under the receiver operating characteristic curve(AUC). Furthermore, we assessed the diagnostic value of MDCS through visual analysis of disputed cases,comparing its performance and efficiency with that of radiologists and exploring whether it could augment radiologists’ performance.Results: On the pooled external and prospective testing sets, MDCS always maintained a high standalone performance, with AFROC-Scores of 0.953 and 0.963 for detection task, and AUCs for classification were 0.909[95% confidence interval(95% CI): 0.822-0.996] and 0.912(95% CI: 0.840-0.985), respectively. It also achieved higher sensitivity than all senior radiologists and higher specificity than all junior radiologists on pooled external and prospective testing sets. Moreover, MDCS performed superior diagnostic efficiency with an average reading time of 5 seconds, compared to the radiologists’ average reading time of 3.2 min. The average performance of all radiologists was also improved to varying degrees with MDCS assistance.Conclusions: MDCS demonstrated excellent performance in the detection and classification of breast lesions,and greatly enhanced the overall performance of radiologists.
基金the State Key Laboratory of Coastal and Offshore Engineering of China(No.LP2019)the 2020 Research Program of Sanya Yazhou Bay Science and Technology City of China(No.SKJC-2020-01-006)+1 种基金the Hainan Provincial Natural Science Foundation of China(No.520QN290)the High-tech Ship Research Projects Sponsored by MIIT of China(No.[2019]357)。
文摘Wave energy is one of the most abundant renewable clean energy sources,and has been widely studied because of its advantages of continuity and low seasonal variation.However,its low capture efficiency and narrow capture frequency bandwidth are still technical bottlenecks that restrict the commercial application of wave energy converters(WECs).In recent years,using a nonlinear stiffness mechanism(NSM)for passive control has provided a new way to solve these technical bottlenecks.This literature review focuses on the research performed on the use of nonlinear mechanisms in wave energy device utilization,including the conceptual design of a mechanism,hydrodynamic models,dynamic characteristics,response mechanisms,and some examples of experimental verification.Finally,future research directions are discussed and recommended.
基金supported by National Natural Science Foundation of China(Grant No.12271257)。
文摘Let C be an extriangulated category and T be any n-cluster tilting subcategory of C.We consider the index with respect to T and introduce the index Grothendieck group of T.Using the index,we prove that the index Grothendieck group of T is isomorphic to the Grothendieck group of C,which implies that the index Grothendieck groups of any two n-cluster tilting subcategories are isomorphic.In particular,we show that the split Grothendieck groups of any two 2-cluster tilting subcategories are isomorphic.Then we develop a general framework for c-vectors of 2-Calabi-Yau extriangulated categories with respect to arbitrary 2-cluster tilting subcategories.We show that the c-vectors have the sign-coherence property and provide some formulas for calculating c-vectors.
基金by the National Key Research and Development Program(2016YFA0602701)National Natural Science Foundation of China(31570468),Changjiang Young Scholars Programme of China(Q2016161)National Youth Top-Notch Talent Support Program,and Fok Ying Tung Education Foundation(151015).
文摘Background:Although soil erosion plays a key role in the carbon cycle,a holistic and mechanistic understanding of the soil erosion process within the cycle is still lacking.The aim of this study was therefore to improve our mechanistic understanding of soil organic carbon(SOC)and soil respiration dynamics through an experiment conducted in an eroding black soil farmland landscape in Northeast China.Results:The depositional profiles store 5.9 times more SOC than the eroding profiles and 3.3 times more SOC than the non-eroding profiles.A linear correlation between the SOC and 137Cs(Caesium-137)was observed in our study,suggesting that the SOC decreased with increased soil erosion.Furthermore,the fractions of intermediate C and the microaggregate C were lowest at the eroding position and highest at the depositional position.In the depositional topsoil,the input of labile materials plays a promotional role in soil respiration.Conversely,in the subsoil(i.e.,below 10 cm),the potential mineralization rates were lowest at the depositional position—due to effective stabilization by physical protection within soil microaggregates.The field results of soil surface respiration also suggest that the depositional topsoil SOC is prone to be mineralized and that SOC at this depositional context is stabilized at subsoil depth.In addition,the high water contents at the depositional position can limit the decomposition rates and stabilize the SOC at the same time.Conclusions:The findings from this study support that a majority of the SOC at footslope is stored within most of the soil profile(i.e.,below 10 cm)and submitted to long-term stabilization,and meanwhile support that the depositional profile emits more CO2 than the summit due to its high amount and quality of SOC.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(grant number 2020B0301030004)the National Natural Science Foundation of China(grant numbers 31971458,41971275)+3 种基金the Special highlevel plan project of Guangdong Province(grant number 2016TQ03Z354)Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(grant number 311021009)the Guangdong Basic and Applied Basic Research Foundation(grant number 2020A151501091)GDAS Special Project of Science and Technology Development(grant number 2020GDASYL-20200102002).
文摘Relationships among productivity,leaf phenology,and seasonal variation in moisture and light availability are poorly understood for evergreen broadleaved tropical/subtropical forests,which contribute 25% of terrestrial productivity.On the one hand,as moisture availability declines,trees shed leaves to reduce transpiration and the risk of hydraulic failure.On the other hand,increases in light availability promote the replacement of senescent leaves to increase productivity.Here,we provide a comprehensive framework that relates the seasonality of climate,leaf abscission,and leaf productivity across the evergreen broadleaved tropical/subtropical forest biome.The seasonal correlation between rainfall and light availability varies from strongly negative to strongly positive across the tropics and maps onto the seasonal correlation between litterfall mass and productivity for 68 forests.Where rainfall and light covary positively,litterfall and productivity also covary positively and are always greater in the wetter sunnier season.Where rainfall and light covary negatively,litterfall and productivity are always greater in the drier and sunnier season if moisture supplies remain adequate;otherwise productivity is smaller in the drier sunnier season.This framework will improve the representation of tropical/subtropical forests in Earth system models and suggests how phenology and productivity will change as climate change alters the seasonality of cloud cover and rainfall across tropical/subtropical forests.