旨在定量描述甬优中熟籼粳杂交稻栽后植株氮素养分积累动态变化,基于模型分析方法从氮素营养层面阐明甬优中熟籼粳杂交稻高产形成机制。2015—2016年,以甬优中熟籼粳杂交稻甬优2640和甬优1640、常规粳稻扬粳4038和扬粳4227、杂交籼稻新...旨在定量描述甬优中熟籼粳杂交稻栽后植株氮素养分积累动态变化,基于模型分析方法从氮素营养层面阐明甬优中熟籼粳杂交稻高产形成机制。2015—2016年,以甬优中熟籼粳杂交稻甬优2640和甬优1640、常规粳稻扬粳4038和扬粳4227、杂交籼稻新两优6380和扬两优6号为试材,比较研究其栽后植株氮素积累特征差异。籼粳杂交稻两年平均产量达11.65 t hm^-2,显著高于常规粳稻(10.74 t hm^-2)和杂交籼稻(10.01 t hm^-2)。成熟期植株氮素吸收量和百千克籽粒吸氮量亦高于常规粳稻和杂交籼稻。成熟期植株各器官氮素吸收量及其所占比例,籼粳杂交稻以穗部最多,叶片其次,茎鞘最少;常规粳稻和杂交籼稻则均以穗部最多,茎鞘其次,叶片最少。与常规粳稻和杂交籼稻相比,籼粳杂交稻成熟期叶片氮素吸收量占植株总吸氮量的比例较高,穗部氮素吸收量所占比例则较低。不同类型品种栽后植株氮素积累动态均以Gompertz方程拟合效果较好,拟合系数一般在0.995左右。与常规粳稻和杂交籼稻相比,甬优中熟籼粳杂交稻在各阶段氮素积累量均具优势,在快增期是由于其较高的持续天数和氮素积累速率,渐增期和缓增期是由于其较高的氮素积累速率。本文提出了符合不同类型水稻栽后植株群体氮素积累动态变化特征的Gompertz模型,并采用该模型分析了甬优中熟籼粳杂交稻栽后植株氮素积累优势。展开更多
This study aims to evaluate the effects of aflatoxins on growth performance and skeletal muscle of Cherry Valley meat male ducks as they grow and develop. One-day-old healthy meat male ducks(n = 180) were randomly div...This study aims to evaluate the effects of aflatoxins on growth performance and skeletal muscle of Cherry Valley meat male ducks as they grow and develop. One-day-old healthy meat male ducks(n = 180) were randomly divided into 2 groups; there were 6 replicates in each group and 15 ducks in each replicate. The control group was fed a basic diet, and the experimental group was fed a mold-exposed cottonseed meal diet containing aflatoxins instead of normal cottonseed meal. The experimental period was 35 days, and divided into two stages of 1 to 14 days(early stage) and 15 to 35 days(late stage). During the experimental period, live weight, breast muscle weight and thigh muscle weight of meat male ducks were measured weekly. Results showed as follows: 1) aflatoxins contained in the mold-exposed diet significantly reduced daily weight gain and feed intake, and increased feed-to-gain ratio of meat male ducks at different ages(P < 0.05); 2) the Gompertz equation(W_t = W_m exp {-exp [-B(t-t~*)]}) could successfully fit the growth curve and growth and developmental patterns of skeletal muscles of Cherry Valley meat male ducks(R^2≥0.97); 3) the relationship between chest muscle and live weight was the best described by a power regression and polynomial regression(R^2 = 0.99); the relationship between live weight and thigh muscle weight was the best described by linear regression, polynomial regression, and power regression(R^2 = 0.99); 4) aflatoxins in the mold-exposed diet significantly reduced live weight, breast muscle weight and thigh muscle weight of Cherry Valley meat male ducks at various ages; and 5) aflatoxins delayed the age at peak in growth of meat male ducks, and reduced weights at the peak for breast muscle, thigh muscle and whole body as well as the maximal daily weight gain. In summary,aflatoxins delayed growth of Cherry Valley meat male ducks and development of skeletal muscle.展开更多
This work presents an optimal harvesting problem associated with a single-species population governed by Gompertz law in a seasonally fluctuating environment.The influence of environmental fluctuation is accommodated ...This work presents an optimal harvesting problem associated with a single-species population governed by Gompertz law in a seasonally fluctuating environment.The influence of environmental fluctuation is accommodated by choosing the coefficients in the differential equation to be periodic functions with the same period and restriction on the harvesting effort is accommodated by considering binding constraints on the control variable.Hence,a linear optimal control problem has been considered where the state dynamics is governed by Gompertz equation and the control variable is subject to the binding constraints.With the help of maximum principle and the concept of blocked intervals,an optimal periodic solution has been obtained which is followed by the construe tion of optimal solution using the theory of most rapid approach.Important results of the study are demonstrated through numerical simulations.展开更多
AIMTo determine how statins, testosterone (T) replacement therapy (TRT) and phosphodiesterase 5-inhibitors (PDE5I) influence age related mortality in diabetic men.METHODSWe studied 857 diabetic men screened for the BL...AIMTo determine how statins, testosterone (T) replacement therapy (TRT) and phosphodiesterase 5-inhibitors (PDE5I) influence age related mortality in diabetic men.METHODSWe studied 857 diabetic men screened for the BLAST study, stratifying them (mean follow-up = 3.8 years) into: (1) Normal T levels/untreated (total T > 12 nmol/L and free T > 0.25 nmol/L), Low T/untreated and Low T/treated; (2) PDE5I/untreated and PDE5I/treated; and (3) statin/untreated and statin/treated groups. The relationship between age and mortality, alone and with T/TRT, statin and PDE5I treatment was studied using logistic regression. Mortality probability and 95%CI were calculated from the above models for each individual.RESULTSAge was associated with mortality (logistic regression, OR = 1.10, 95%CI: 1.08-1.13, P < 0.001). With all factors included, age (OR = 1.08, 95%CI: 1.06-1.11, P < 0.001), Low T/treated (OR = 0.38, 95%CI: 0.15-0.92, P = 0.033), PDE5I/treated (OR = 0.17, 95%CI: 0.053-0.56, P = 0.004) and statin/treated (OR = 0.59, 95%CI: 0.36-0.97, P = 0.038) were associated with lower mortality. Age related mortality was as described by Gompertz, r<sup>2</sup> = 0.881 when Ln (mortality) was plotted against age. The probability of mortality and 95%CI (from logistic regression) of individuals, treated/untreated with the drugs, alone and in combination was plotted against age. Overlap of 95%CI lines was evident with statins and TRT. No overlap was evident with PDE5I alone and with statins and TRT, this suggesting a change in the relationship between age and mortality.CONCLUSIONWe show that statins, PDE5I and TRT reduce mortality in diabetes. PDE5I, alone and with the other treatments significantly alter age related mortality in diabetic men.展开更多
This paper mainly focus on the research of a predator⁃prey system with Gompertz growth of prey.When the system does not contain diffusion,the stability conditions of positive equilibrium and the occurring condition of...This paper mainly focus on the research of a predator⁃prey system with Gompertz growth of prey.When the system does not contain diffusion,the stability conditions of positive equilibrium and the occurring condition of the Hopf bifurcation are obtained.When the diffusion term of the system appears,the stable conditions of positive equilibrium and the Turing instability condition are also obtained.Turing instability is induced by the diffusion term through theoretical analysis.Thus,the region of parameters in which Turing instability occurs is presented.Then the amplitude equations are derived by the multiple scale method.The results will enrich the pattern dynamics in predator⁃prey systems.展开更多
文摘旨在定量描述甬优中熟籼粳杂交稻栽后植株氮素养分积累动态变化,基于模型分析方法从氮素营养层面阐明甬优中熟籼粳杂交稻高产形成机制。2015—2016年,以甬优中熟籼粳杂交稻甬优2640和甬优1640、常规粳稻扬粳4038和扬粳4227、杂交籼稻新两优6380和扬两优6号为试材,比较研究其栽后植株氮素积累特征差异。籼粳杂交稻两年平均产量达11.65 t hm^-2,显著高于常规粳稻(10.74 t hm^-2)和杂交籼稻(10.01 t hm^-2)。成熟期植株氮素吸收量和百千克籽粒吸氮量亦高于常规粳稻和杂交籼稻。成熟期植株各器官氮素吸收量及其所占比例,籼粳杂交稻以穗部最多,叶片其次,茎鞘最少;常规粳稻和杂交籼稻则均以穗部最多,茎鞘其次,叶片最少。与常规粳稻和杂交籼稻相比,籼粳杂交稻成熟期叶片氮素吸收量占植株总吸氮量的比例较高,穗部氮素吸收量所占比例则较低。不同类型品种栽后植株氮素积累动态均以Gompertz方程拟合效果较好,拟合系数一般在0.995左右。与常规粳稻和杂交籼稻相比,甬优中熟籼粳杂交稻在各阶段氮素积累量均具优势,在快增期是由于其较高的持续天数和氮素积累速率,渐增期和缓增期是由于其较高的氮素积累速率。本文提出了符合不同类型水稻栽后植株群体氮素积累动态变化特征的Gompertz模型,并采用该模型分析了甬优中熟籼粳杂交稻栽后植株氮素积累优势。
基金supported by the Agricultural Science and Technology Innovation program in Chinese Academy of Agricultural Sciences (ASTIP)
文摘This study aims to evaluate the effects of aflatoxins on growth performance and skeletal muscle of Cherry Valley meat male ducks as they grow and develop. One-day-old healthy meat male ducks(n = 180) were randomly divided into 2 groups; there were 6 replicates in each group and 15 ducks in each replicate. The control group was fed a basic diet, and the experimental group was fed a mold-exposed cottonseed meal diet containing aflatoxins instead of normal cottonseed meal. The experimental period was 35 days, and divided into two stages of 1 to 14 days(early stage) and 15 to 35 days(late stage). During the experimental period, live weight, breast muscle weight and thigh muscle weight of meat male ducks were measured weekly. Results showed as follows: 1) aflatoxins contained in the mold-exposed diet significantly reduced daily weight gain and feed intake, and increased feed-to-gain ratio of meat male ducks at different ages(P < 0.05); 2) the Gompertz equation(W_t = W_m exp {-exp [-B(t-t~*)]}) could successfully fit the growth curve and growth and developmental patterns of skeletal muscles of Cherry Valley meat male ducks(R^2≥0.97); 3) the relationship between chest muscle and live weight was the best described by a power regression and polynomial regression(R^2 = 0.99); the relationship between live weight and thigh muscle weight was the best described by linear regression, polynomial regression, and power regression(R^2 = 0.99); 4) aflatoxins in the mold-exposed diet significantly reduced live weight, breast muscle weight and thigh muscle weight of Cherry Valley meat male ducks at various ages; and 5) aflatoxins delayed the age at peak in growth of meat male ducks, and reduced weights at the peak for breast muscle, thigh muscle and whole body as well as the maximal daily weight gain. In summary,aflatoxins delayed growth of Cherry Valley meat male ducks and development of skeletal muscle.
文摘This work presents an optimal harvesting problem associated with a single-species population governed by Gompertz law in a seasonally fluctuating environment.The influence of environmental fluctuation is accommodated by choosing the coefficients in the differential equation to be periodic functions with the same period and restriction on the harvesting effort is accommodated by considering binding constraints on the control variable.Hence,a linear optimal control problem has been considered where the state dynamics is governed by Gompertz equation and the control variable is subject to the binding constraints.With the help of maximum principle and the concept of blocked intervals,an optimal periodic solution has been obtained which is followed by the construe tion of optimal solution using the theory of most rapid approach.Important results of the study are demonstrated through numerical simulations.
基金Supported by Bayer plc to University of Bedfordshire(ref:SOP ID:BSP-SOP-040)Bayer plc played no part in the design,conduct of the study,data collection,statistical analyses or preparation of the manuscript
文摘AIMTo determine how statins, testosterone (T) replacement therapy (TRT) and phosphodiesterase 5-inhibitors (PDE5I) influence age related mortality in diabetic men.METHODSWe studied 857 diabetic men screened for the BLAST study, stratifying them (mean follow-up = 3.8 years) into: (1) Normal T levels/untreated (total T > 12 nmol/L and free T > 0.25 nmol/L), Low T/untreated and Low T/treated; (2) PDE5I/untreated and PDE5I/treated; and (3) statin/untreated and statin/treated groups. The relationship between age and mortality, alone and with T/TRT, statin and PDE5I treatment was studied using logistic regression. Mortality probability and 95%CI were calculated from the above models for each individual.RESULTSAge was associated with mortality (logistic regression, OR = 1.10, 95%CI: 1.08-1.13, P < 0.001). With all factors included, age (OR = 1.08, 95%CI: 1.06-1.11, P < 0.001), Low T/treated (OR = 0.38, 95%CI: 0.15-0.92, P = 0.033), PDE5I/treated (OR = 0.17, 95%CI: 0.053-0.56, P = 0.004) and statin/treated (OR = 0.59, 95%CI: 0.36-0.97, P = 0.038) were associated with lower mortality. Age related mortality was as described by Gompertz, r<sup>2</sup> = 0.881 when Ln (mortality) was plotted against age. The probability of mortality and 95%CI (from logistic regression) of individuals, treated/untreated with the drugs, alone and in combination was plotted against age. Overlap of 95%CI lines was evident with statins and TRT. No overlap was evident with PDE5I alone and with statins and TRT, this suggesting a change in the relationship between age and mortality.CONCLUSIONWe show that statins, PDE5I and TRT reduce mortality in diabetes. PDE5I, alone and with the other treatments significantly alter age related mortality in diabetic men.
基金National Natural Science Foundation of China(No.11971143)。
文摘This paper mainly focus on the research of a predator⁃prey system with Gompertz growth of prey.When the system does not contain diffusion,the stability conditions of positive equilibrium and the occurring condition of the Hopf bifurcation are obtained.When the diffusion term of the system appears,the stable conditions of positive equilibrium and the Turing instability condition are also obtained.Turing instability is induced by the diffusion term through theoretical analysis.Thus,the region of parameters in which Turing instability occurs is presented.Then the amplitude equations are derived by the multiple scale method.The results will enrich the pattern dynamics in predator⁃prey systems.
文摘本研究通过对2022、2023年在黄河干流甘肃、宁夏段采集的274个硬刺高原鳅样本进行分析,旨在深入理解其生长特性,并丰富硬刺高原鳅的生物学研究内容。研究采用Von Bertalanffy生长方程(VBGF)、逻辑斯谛生长方程(Logistic GF)、Gompertz生长方程和幂指数生长方程对样本进行生长模拟,使用最大似然法估算模型参数,并依据AIC准则(Akaike Information Criterion)评估各模型的拟合效果,选择最佳模型,分析硬刺高原鳅的年龄组成及其生长特性。结果显示,VBGF生长方程(AIC值:63.74)为硬刺高原鳅的最适生长模型,其次为Gompertz生长方程(AIC值:64.11)、幂指数生长方程(AIC值:64.12),拟合效果最差的为Logistic生长方程(AIC值:65.05),其中硬刺高原鳅全长VBGF生长方程为:L_(t)=28.986·[1-e^(-0.097·(t_(1)+1.258))];体质量生长方程为:W_(t)=194.721·[1-e^(-0.097·(t_(1)+1.258))]^(2.9889)。研究结果可为硬刺高原鳅资源保护提供科学依据。
