Inflammatory bowel diseases(IBD),including ulcerative colitis(UC) and Crohn's disease(CD),are chronic,progressive and disabling disorders.Over the last few decades,new therapeutic approaches have been introduced w...Inflammatory bowel diseases(IBD),including ulcerative colitis(UC) and Crohn's disease(CD),are chronic,progressive and disabling disorders.Over the last few decades,new therapeutic approaches have been introduced which have led not only to a reduction in the mortality rate but also offered the possibility of a favorable modification in the natural history of IBD.The identification of clinical,genetic and serological prognostic factors has permitted a better stratification of the disease,thus allowing the opportunity to indicate the most appropriate therapy.Early treatment with immunosuppressive drugs and biologics has offered the opportunity to change,at least in the short term,the course of the disease by reducing,in a subset of patients with IBD,hospitalization and the need for surgery.In this review,the crucial steps in the natural history of both UC and CD will be discussed,as well as the factors that may change their clinical course.The methodological requirements for high quality studies on the course and prognosis of IBD,the true impact of environmental and dietary factors on the clinical course of IBD,the clinical,serological and genetic predictors of the IBD course(in particular,which of these are rel-evant and appropriate for use in clinical practice),the impact of the various forms of medical treatment on the IBD complication rate,the role of surgery for IBD in the biologic era,the true magnitude of risk of colorectal cancer associated with IBD,as well as the mortality rate related to IBD will be stressed;all topics that are extensively discussed in separate reviews included in this issue of World Journal of Gastroenterology.展开更多
The structure of plant communities at local scales depends on both the spatial heterogeneity of abiotic environmental factors and the biotic interactions within the community.However,although environmental filtering d...The structure of plant communities at local scales depends on both the spatial heterogeneity of abiotic environmental factors and the biotic interactions within the community.However,although environmental filtering due to microtopographic heterogeneity and resource competition among plants caused by spatial variation in tree density and size are considered to be very important in explaining the mechanisms of community assembly,their effects on the processes of individual mortality and recruitment in natural forest regeneration,as well as their relative contributions,are still poorly understood.To address this,we established a 12-ha permanent plot in a subtropical evergreen broad-leaved forest area and measured microtopographic variables such as elevation,slope,aspect,and terrain position index(TPI)using a total station.We monitored the individual mortality and recruitment in forest natural regeneration through repeated surveys at 5-year intervals.We fitted spatial covariance models to jointly use multiple factors from three groups of variables(microtopographic effect,neighborhood density effects,neighborhood size effects)as explanatory variables to analyze their roles in driving the mortality and recruitment of all individual and 12 dominant species in forest natural regeneration at the neighborhood scale.Our results show that:(1)In the crucial early stages of secondary forest restoration,natural regeneration is influenced by a synergy of environmental filtering,due to microtopographic heterogeneity,and resource competition among plants.(2)For distinct species responses,evergreen dominant species'mortality is largely explained by neighborhood effects,while deciduous species are more affected by topographic factors.Furthermore,the adverse effects of larger conspecific trees on younger trees indicate a pattern of competitive pressure leading to mortality among regenerating trees,such pattern emphasis the influence of parent trees on natural regeneration.(3)As trees grow,their interaction with these stressors evolv展开更多
Crohn’s disease (CD) is a multifactorial potentially debilitating disease. It has a variable disease course, but the majority of patients eventually develop penetrating or stricturing complications leading...Crohn’s disease (CD) is a multifactorial potentially debilitating disease. It has a variable disease course, but the majority of patients eventually develop penetrating or stricturing complications leading to repeated surgeries and disability. Studies on the natural history of CD provide invaluable data on its course and clinical predictors, and may help to identify patient subsets based on clinical phenotype. Most data are available from referral centers, however these outcomes may be different from those in population-based cohorts. New data suggest the possibility of a change in the natural history in Crohn’s disease, with an increasing percentage of patients diagnosed with inflammatory disease behavior. Hospitalization rates remain high, while surgery rates seem to have decreased in the last decade. In addition, mortality rates still exceed that of the general population. The impact of changes in treatment strategy, including increased, earlier use of immunosuppressives, biological therapy, and patient monitoring on the natural history of the disease are still conflictive. In this review article, the authors summarize the available evidence on the natural history, current trends, and predictive factors for evaluating the disease course of CD.展开更多
The assessment of Eastern Georges Bank cod with the assumption of a constant natural mortality of 0.2 has over-estimated stock productivity, resulting in a severe retrospective pattern since the late 2000 s. Comparing...The assessment of Eastern Georges Bank cod with the assumption of a constant natural mortality of 0.2 has over-estimated stock productivity, resulting in a severe retrospective pattern since the late 2000 s. Comparing relative exploitation rate(ratio of fishery catch at age to survey abundance indices at age) with total mortality calculated from the age distribution in surveys indicated a conflict when constant natural mortality was assumed. This inconsistency implies an increase in natural mortality since the mid-1990 s. In this paper, natural mortality estimated by Virtual Population Analysis(VPA) indicated that natural mortality for this stock has increased to 0.8 since the mid-1990 s for ages 6+. Potential factors contributing to this elevated natural mortality, including poor fish conditions and increased losses due to seal predation were discussed.展开更多
The objective of this study was to estimate natural, fishing and total mortality, survival and exploitation rates of Clupeonella engrauliformis in the southern Caspian Sea. Survival rate and natural mortality were cal...The objective of this study was to estimate natural, fishing and total mortality, survival and exploitation rates of Clupeonella engrauliformis in the southern Caspian Sea. Survival rate and natural mortality were calculated using catch curve and Pauly methods, respectively. Natural and fishing mortality have been estimated up to 0.633 yr^-1 and 0.437 yr^-1, respectively. According to catch curve method, the annual survival rate of anchovy kilka has been estimated up to 0.343 yr^-1. With owning this survival rate, the instantaneous coefficient of total mortality of anchovy kilka has been estimated up to 1.07 yr^-1. The exploitation rate of anchovy kilka has been estimated up to 0.408. The catch amounts of anchovy kilka decreased gradually mainly due to overfishing, predators and ecological disturbances occurred in the Caspian Sea. The results suggest that the population of anchovy kilka were overexploited in the past years and were vulnerable to their natural predators.展开更多
Estimation of parameters and random effects using true maximum likelihood methods is compared to the commonly used penalized maximum likelihood method. The simulated catch-at-age datasets have all conceivable noise in...Estimation of parameters and random effects using true maximum likelihood methods is compared to the commonly used penalized maximum likelihood method. The simulated catch-at-age datasets have all conceivable noise in stock and fishing dynamics in addition to the observation error on the catch. Improvement is modest in simple models but refinements that are only possible with these methods provide additional precision. Unbiased estimation of natural mortality is made possible with these methods, but precision is low unless variation in fishing effort between years is large and other variation small, in particular the uncertainty in the recruitment. Relatively unbiased estimates of all other in-put parameters and variances were obtained. Alternately the stock may be updated with the catches directly, rather than through the fishing mortality. This can be done exactly and such that bias in the final stock is small. Such a model will test a different error structure and may also be more appealing for presentation of results as the catches are in better agreement with the changes in the estimated stock.展开更多
The dead proportion of a calanoid copepod Calanus sinicus population was investigated monthly with neutral red staining method at 12 stations in the Jiaozhou Bay and the adjacent waters from December 2008 to November ...The dead proportion of a calanoid copepod Calanus sinicus population was investigated monthly with neutral red staining method at 12 stations in the Jiaozhou Bay and the adjacent waters from December 2008 to November 2009. C. sinicus could be observed through the whole year, with an evident numerical peak from February to April and an extremely low abundance in summer. Annual variation of the dead proportion differed greatly between adult females and copepodites. Dead females were observed only in the southern part and outside the bay sporadically in five months, when the egg production was the most active. Dead proportion of females was usually less than 5%. Dead copepodites could be observed in all but three months in summer in the whole study area, and the proportion varied between 3.8% – 18.2%. Death percentage of copepodites increased significantly in the northern part in January and June, when water temperature exceeded it's favorable limits;however, the fluctuated salinity had no significant effect on the survival of both females and copepodites. Thus the dead proportion of C. sinicus was relatively low in the Jiaozhou Bay, while difference could be observed between females and copepodites. Dead copepodites were common in all samples, but dead females were presented mainly as ‘reproduction cost' during generation alternation.展开更多
文摘Inflammatory bowel diseases(IBD),including ulcerative colitis(UC) and Crohn's disease(CD),are chronic,progressive and disabling disorders.Over the last few decades,new therapeutic approaches have been introduced which have led not only to a reduction in the mortality rate but also offered the possibility of a favorable modification in the natural history of IBD.The identification of clinical,genetic and serological prognostic factors has permitted a better stratification of the disease,thus allowing the opportunity to indicate the most appropriate therapy.Early treatment with immunosuppressive drugs and biologics has offered the opportunity to change,at least in the short term,the course of the disease by reducing,in a subset of patients with IBD,hospitalization and the need for surgery.In this review,the crucial steps in the natural history of both UC and CD will be discussed,as well as the factors that may change their clinical course.The methodological requirements for high quality studies on the course and prognosis of IBD,the true impact of environmental and dietary factors on the clinical course of IBD,the clinical,serological and genetic predictors of the IBD course(in particular,which of these are rel-evant and appropriate for use in clinical practice),the impact of the various forms of medical treatment on the IBD complication rate,the role of surgery for IBD in the biologic era,the true magnitude of risk of colorectal cancer associated with IBD,as well as the mortality rate related to IBD will be stressed;all topics that are extensively discussed in separate reviews included in this issue of World Journal of Gastroenterology.
基金the Innovative Team Project of Nanjing Institute of Environmental Sciences MEE(ZX2023QT022)Sino-German Environmental Partnership PhaseⅢ:Strengthening Chinese environmental and nature conservation policy through dialogue+2 种基金The Central Public Welfare Scientific Institution Basal Research Fund,MEE(GYZX210302)Biodiversity Survey,Observation and Assessment Program of Ministry of Ecology and Environment of ChinaThe National Environmental Protection Public Welfare Industry Targeted Research Fund:Research and demonstration of key technologies for dynamic supervision of nature reserves(201509042)。
文摘The structure of plant communities at local scales depends on both the spatial heterogeneity of abiotic environmental factors and the biotic interactions within the community.However,although environmental filtering due to microtopographic heterogeneity and resource competition among plants caused by spatial variation in tree density and size are considered to be very important in explaining the mechanisms of community assembly,their effects on the processes of individual mortality and recruitment in natural forest regeneration,as well as their relative contributions,are still poorly understood.To address this,we established a 12-ha permanent plot in a subtropical evergreen broad-leaved forest area and measured microtopographic variables such as elevation,slope,aspect,and terrain position index(TPI)using a total station.We monitored the individual mortality and recruitment in forest natural regeneration through repeated surveys at 5-year intervals.We fitted spatial covariance models to jointly use multiple factors from three groups of variables(microtopographic effect,neighborhood density effects,neighborhood size effects)as explanatory variables to analyze their roles in driving the mortality and recruitment of all individual and 12 dominant species in forest natural regeneration at the neighborhood scale.Our results show that:(1)In the crucial early stages of secondary forest restoration,natural regeneration is influenced by a synergy of environmental filtering,due to microtopographic heterogeneity,and resource competition among plants.(2)For distinct species responses,evergreen dominant species'mortality is largely explained by neighborhood effects,while deciduous species are more affected by topographic factors.Furthermore,the adverse effects of larger conspecific trees on younger trees indicate a pattern of competitive pressure leading to mortality among regenerating trees,such pattern emphasis the influence of parent trees on natural regeneration.(3)As trees grow,their interaction with these stressors evolv
文摘Crohn’s disease (CD) is a multifactorial potentially debilitating disease. It has a variable disease course, but the majority of patients eventually develop penetrating or stricturing complications leading to repeated surgeries and disability. Studies on the natural history of CD provide invaluable data on its course and clinical predictors, and may help to identify patient subsets based on clinical phenotype. Most data are available from referral centers, however these outcomes may be different from those in population-based cohorts. New data suggest the possibility of a change in the natural history in Crohn’s disease, with an increasing percentage of patients diagnosed with inflammatory disease behavior. Hospitalization rates remain high, while surgery rates seem to have decreased in the last decade. In addition, mortality rates still exceed that of the general population. The impact of changes in treatment strategy, including increased, earlier use of immunosuppressives, biological therapy, and patient monitoring on the natural history of the disease are still conflictive. In this review article, the authors summarize the available evidence on the natural history, current trends, and predictive factors for evaluating the disease course of CD.
文摘The assessment of Eastern Georges Bank cod with the assumption of a constant natural mortality of 0.2 has over-estimated stock productivity, resulting in a severe retrospective pattern since the late 2000 s. Comparing relative exploitation rate(ratio of fishery catch at age to survey abundance indices at age) with total mortality calculated from the age distribution in surveys indicated a conflict when constant natural mortality was assumed. This inconsistency implies an increase in natural mortality since the mid-1990 s. In this paper, natural mortality estimated by Virtual Population Analysis(VPA) indicated that natural mortality for this stock has increased to 0.8 since the mid-1990 s for ages 6+. Potential factors contributing to this elevated natural mortality, including poor fish conditions and increased losses due to seal predation were discussed.
文摘The objective of this study was to estimate natural, fishing and total mortality, survival and exploitation rates of Clupeonella engrauliformis in the southern Caspian Sea. Survival rate and natural mortality were calculated using catch curve and Pauly methods, respectively. Natural and fishing mortality have been estimated up to 0.633 yr^-1 and 0.437 yr^-1, respectively. According to catch curve method, the annual survival rate of anchovy kilka has been estimated up to 0.343 yr^-1. With owning this survival rate, the instantaneous coefficient of total mortality of anchovy kilka has been estimated up to 1.07 yr^-1. The exploitation rate of anchovy kilka has been estimated up to 0.408. The catch amounts of anchovy kilka decreased gradually mainly due to overfishing, predators and ecological disturbances occurred in the Caspian Sea. The results suggest that the population of anchovy kilka were overexploited in the past years and were vulnerable to their natural predators.
文摘Estimation of parameters and random effects using true maximum likelihood methods is compared to the commonly used penalized maximum likelihood method. The simulated catch-at-age datasets have all conceivable noise in stock and fishing dynamics in addition to the observation error on the catch. Improvement is modest in simple models but refinements that are only possible with these methods provide additional precision. Unbiased estimation of natural mortality is made possible with these methods, but precision is low unless variation in fishing effort between years is large and other variation small, in particular the uncertainty in the recruitment. Relatively unbiased estimates of all other in-put parameters and variances were obtained. Alternately the stock may be updated with the catches directly, rather than through the fishing mortality. This can be done exactly and such that bias in the final stock is small. Such a model will test a different error structure and may also be more appealing for presentation of results as the catches are in better agreement with the changes in the estimated stock.
基金supported by the National Key Research and Development Program of China (No. 2017YFE111100)the Aoshan Science and Technology Innovation Project (No. 2016ASKJ0202)the National Natural Science Foundation of China (Nos. 41406148,40830854)。
文摘The dead proportion of a calanoid copepod Calanus sinicus population was investigated monthly with neutral red staining method at 12 stations in the Jiaozhou Bay and the adjacent waters from December 2008 to November 2009. C. sinicus could be observed through the whole year, with an evident numerical peak from February to April and an extremely low abundance in summer. Annual variation of the dead proportion differed greatly between adult females and copepodites. Dead females were observed only in the southern part and outside the bay sporadically in five months, when the egg production was the most active. Dead proportion of females was usually less than 5%. Dead copepodites could be observed in all but three months in summer in the whole study area, and the proportion varied between 3.8% – 18.2%. Death percentage of copepodites increased significantly in the northern part in January and June, when water temperature exceeded it's favorable limits;however, the fluctuated salinity had no significant effect on the survival of both females and copepodites. Thus the dead proportion of C. sinicus was relatively low in the Jiaozhou Bay, while difference could be observed between females and copepodites. Dead copepodites were common in all samples, but dead females were presented mainly as ‘reproduction cost' during generation alternation.
