森林生态系统模型已经成为一门新兴的科学,可以为森林资源的管理利用、森林最大收益的获取提供科学依据。PnET模型是美国复杂系统研究中心(Complex System Research Center)开发研制的,最初是为了模拟森林生态系统碳水平衡而创建,目前...森林生态系统模型已经成为一门新兴的科学,可以为森林资源的管理利用、森林最大收益的获取提供科学依据。PnET模型是美国复杂系统研究中心(Complex System Research Center)开发研制的,最初是为了模拟森林生态系统碳水平衡而创建,目前该模型可以模拟完整的氮循环过程。PnET模型已经在美洲、欧洲以及亚洲的一些地区得到了验证和运用,可用于森林乃至陆地生态系统的模拟。PnET模型可用来分析森林林木生长规律,不同土壤类型及气候条件对森林生态系统碳氮通量变化的影响;还可用于估算森林生态系统最大生产潜力,对生长在不利条件以及地区的林木生长进行预测等。该模型对可持续林业的发展具有积极的指导作用。展开更多
A generalized, lumped-parameter ecological model PnET-CN was calibrated and validated for a subtropical coniferous plantation in southern China. PnET-CN model describes the biogeochemical cycles of carbon （C） and ni...A generalized, lumped-parameter ecological model PnET-CN was calibrated and validated for a subtropical coniferous plantation in southern China. PnET-CN model describes the biogeochemical cycles of carbon （C） and nitrogen （N） and can assist in estimating carbon sequestration potential. For validation of PnET-CN, data from coniferous forest plantations in southern China was used. Simulated daily gross primary productivity （GPP） from 2005 to 2007 agreed well with observations （R2=0.56, S.D.=0.009）. Simulations of monthly soil respiration （Rs） from 2005-2007 agreed well with Rs observations （R2=0.67, S.D. =0.03）. Simu- lated annual net primary productivity （NPP） from 1998-2006 was 803＋33 gCm 2a-1, about 4% higher than NPP observation （752＋51 gCm-2a-1）. Simulations of annual NEP from 2005-2007 only overestimate 9 gCm-2a-1 （4%）, 4 gCm 2a-1 （1%） and 34 gCm 2a-1 （8%） compared to NEP observations, respectively. Simulated annual foliar N concentration （FolNCon） （1.09%） is 10% lower than observed monthly FolNCon （0.87%-1.58%）. Simulated annual N leaching （0.26 gNm-2） is about 10% lower than leaching observation （0.29 gNm-2）. PnET-CN model validation indicates that PnET-CN is capable to simulate daily GPP, annual NPP, annual NEP, monthly Rs, annual FolNCon and annual nitrate N leaching for subtropical coniferous planta- tions in southern China. The results obtained from the validation test revealed that PnET-CN model can be used to simulate carbon sequestration of planted coniferous forests in southern China to a high level of precision. Sensitivity analysis suggests that great care should be taken in developing generalizations as to how forests will respond to a changing climate. PnET-CN performed satisfactorily in comparison to other models that have already been calibrated and validated in coniferous planted subtropical forests in China. Based on PnET-CN validation and its comparison to other models, future improvement of PnET-CN should focus on seasonal foliar N dynamics and the effects of water stress on autotrophic respirations in subtropical coniferous plantations in southern China.展开更多
Pancreatic neuroendocrine tumors(pNETs)are rare,presenting significant challenges in timely diagnosis and subsequent treatment.The clinical and pathobiological behavior of these tumors varies significantly,making foll...Pancreatic neuroendocrine tumors(pNETs)are rare,presenting significant challenges in timely diagnosis and subsequent treatment.The clinical and pathobiological behavior of these tumors varies significantly,making follow-up and therapeutic approaches challenging for clinicians.Although the majority of these neoplasms are hormonally inactive,some can be associated with endocrine dysfunction.Very rarely,a nonfunctional tumor can later become hormonally active,further complicating prognostication and management.Depending on the character of the disease,clinical picture and prognosis,different treatment modalities are instituted with varying effectivities.We recently came across a unique case of nonfunctioning malignant pNET at an advanced stage,metastatic disease upon diagnosis,managed medically with somatostatin analog therapy(Octreotide)and targeted therapy(Everolimus)with stable disease for 40 months that subsequently turned out to become functional(insulinoma).With the aid of this unique case,we update the current clinical,diagnostic and therapeutic approach to pNETs in this evidence-based review.展开更多
Pancreatic neuroendocrine tumors(PNETs)are the second most common neoplasm of the pancreas after ductal adenocarcinoma.The clinical behavior of PNETs is very difficult to predict,especially for well-differentiated PNE...Pancreatic neuroendocrine tumors(PNETs)are the second most common neoplasm of the pancreas after ductal adenocarcinoma.The clinical behavior of PNETs is very difficult to predict,especially for well-differentiated PNETs.Several classification systems have been developed to differentiate benign from malignant PNETs.The current 5th edition WHO(2019)updated the grading system of PNETs which is now entirely based on proliferative rate(either mitotic count or Ki-67 index).In this article,we systemically reviewed the evolution of the histologic classification and grading systems for well-differentiated PNETs.Meanwhile,we also report a comprehensive summary of immunohistochemical and molecular prognostic factors for PNETs patients,including CK19,KIT,PDL1/PD-L1,UCH-L1 and CNPY2.We believe that more reliable grading systems and prognostic markers are emerging and will change the landscape of treatment for well-differentiated PNETs.展开更多
文摘森林生态系统模型已经成为一门新兴的科学,可以为森林资源的管理利用、森林最大收益的获取提供科学依据。PnET模型是美国复杂系统研究中心(Complex System Research Center)开发研制的,最初是为了模拟森林生态系统碳水平衡而创建,目前该模型可以模拟完整的氮循环过程。PnET模型已经在美洲、欧洲以及亚洲的一些地区得到了验证和运用,可用于森林乃至陆地生态系统的模拟。PnET模型可用来分析森林林木生长规律,不同土壤类型及气候条件对森林生态系统碳氮通量变化的影响;还可用于估算森林生态系统最大生产潜力,对生长在不利条件以及地区的林木生长进行预测等。该模型对可持续林业的发展具有积极的指导作用。
基金National Natural Science Foundation of China, No.31070438 The Key Project of CAS Knowledge Innovation Program, No.KZCX2-YW-305-3+1 种基金 No.KZCX2-YW-QN301 State Key Basic Research Development Proiect, No.2010CB833503
文摘A generalized, lumped-parameter ecological model PnET-CN was calibrated and validated for a subtropical coniferous plantation in southern China. PnET-CN model describes the biogeochemical cycles of carbon （C） and nitrogen （N） and can assist in estimating carbon sequestration potential. For validation of PnET-CN, data from coniferous forest plantations in southern China was used. Simulated daily gross primary productivity （GPP） from 2005 to 2007 agreed well with observations （R2=0.56, S.D.=0.009）. Simulations of monthly soil respiration （Rs） from 2005-2007 agreed well with Rs observations （R2=0.67, S.D. =0.03）. Simu- lated annual net primary productivity （NPP） from 1998-2006 was 803＋33 gCm 2a-1, about 4% higher than NPP observation （752＋51 gCm-2a-1）. Simulations of annual NEP from 2005-2007 only overestimate 9 gCm-2a-1 （4%）, 4 gCm 2a-1 （1%） and 34 gCm 2a-1 （8%） compared to NEP observations, respectively. Simulated annual foliar N concentration （FolNCon） （1.09%） is 10% lower than observed monthly FolNCon （0.87%-1.58%）. Simulated annual N leaching （0.26 gNm-2） is about 10% lower than leaching observation （0.29 gNm-2）. PnET-CN model validation indicates that PnET-CN is capable to simulate daily GPP, annual NPP, annual NEP, monthly Rs, annual FolNCon and annual nitrate N leaching for subtropical coniferous planta- tions in southern China. The results obtained from the validation test revealed that PnET-CN model can be used to simulate carbon sequestration of planted coniferous forests in southern China to a high level of precision. Sensitivity analysis suggests that great care should be taken in developing generalizations as to how forests will respond to a changing climate. PnET-CN performed satisfactorily in comparison to other models that have already been calibrated and validated in coniferous planted subtropical forests in China. Based on PnET-CN validation and its comparison to other models, future improvement of PnET-CN should focus on seasonal foliar N dynamics and the effects of water stress on autotrophic respirations in subtropical coniferous plantations in southern China.
文摘Pancreatic neuroendocrine tumors(pNETs)are rare,presenting significant challenges in timely diagnosis and subsequent treatment.The clinical and pathobiological behavior of these tumors varies significantly,making follow-up and therapeutic approaches challenging for clinicians.Although the majority of these neoplasms are hormonally inactive,some can be associated with endocrine dysfunction.Very rarely,a nonfunctional tumor can later become hormonally active,further complicating prognostication and management.Depending on the character of the disease,clinical picture and prognosis,different treatment modalities are instituted with varying effectivities.We recently came across a unique case of nonfunctioning malignant pNET at an advanced stage,metastatic disease upon diagnosis,managed medically with somatostatin analog therapy(Octreotide)and targeted therapy(Everolimus)with stable disease for 40 months that subsequently turned out to become functional(insulinoma).With the aid of this unique case,we update the current clinical,diagnostic and therapeutic approach to pNETs in this evidence-based review.
文摘Pancreatic neuroendocrine tumors(PNETs)are the second most common neoplasm of the pancreas after ductal adenocarcinoma.The clinical behavior of PNETs is very difficult to predict,especially for well-differentiated PNETs.Several classification systems have been developed to differentiate benign from malignant PNETs.The current 5th edition WHO(2019)updated the grading system of PNETs which is now entirely based on proliferative rate(either mitotic count or Ki-67 index).In this article,we systemically reviewed the evolution of the histologic classification and grading systems for well-differentiated PNETs.Meanwhile,we also report a comprehensive summary of immunohistochemical and molecular prognostic factors for PNETs patients,including CK19,KIT,PDL1/PD-L1,UCH-L1 and CNPY2.We believe that more reliable grading systems and prognostic markers are emerging and will change the landscape of treatment for well-differentiated PNETs.
