具脉冲出生单种群模型的脉冲收获阈值分析

讨论了与生物资源管理相关的具脉冲出生与脉冲收获的单种群动力学模型,利用离散动力系统频闪映射理论,得到了生物资源管理控制阈值的充分条件.结论为现实的生物资源管理提供了可靠的策略依据,也丰富了脉冲微分方程理论.     

具脉冲出生和脉冲收获的基因突变单种群动力学模型分析

建立了具脉冲出生和脉冲收获的基因突变单种群动力学模型.利用离散动力系统的频闪映射理论,得到了生物资源管理控制阈值的充分条件.     

具有脉冲接种的时滞SEIR传染病模型

研究了一类具有饱和发生率及脉冲接种的时滞SEIR传染病模型,得到了基本再生数,运用脉冲微分方程的比较原理证明了无病周期解的全局吸引性,获得了疾病持久性的充分条件.通过数值模拟验证了结论的准确性.     

一类带有脉冲出生、脉冲接种和垂直传染的时滞SEIR传染病模型

主要讨论了对一类带有脉冲出生、脉冲接种、水平传染和垂直传染的含有时滞的SEIR传染病模型.首先,通过对模型的计算得到了无病周期解的存在性以及临界值R~*和R_*,假设R~*1时,由脉冲微分方程比较定理证明了无病周期解的全局吸引性;然后假设R_*1时,用Lyapunov方法和脉冲微分方程比较定理证明了疾病传染的持久性.     

具脉冲出生的Leslie-Gower捕食者-食饵系统的动力学分析

研究了一个具有脉冲出生的Leslie-Gower捕食者一食饵系统的动力学性质．利用频闪映射。得到了带有Ricker和Beverton-Holt函数的脉冲系统准确的周期解．通过Floquet定理和脉冲比较定理,讨论了该系统的灭绝和持久生存．最后,数值分析了以b（p）为分支参数的分支图,得到的结论是脉冲出生会带给系统倍周期分支、混沌以及在混沌带中出现周期窗口等复杂的动力学行为．     

一类生态系统的脉冲控制

利用脉冲系统的线性近似判定的方法对一个具有脉冲控制的生物模型进行研究,得到了使其渐近稳定到原先不稳定的平衡点的充要条件并给出了生态解释。     

一类具饱和传染力和常数输入的SIRS脉冲接种模型研究

利用Floquet乘子理论,研究了一类具饱和传染力和常数输入的SIRS脉冲接种模型,得到了无病周期解全局渐近稳定和系统持久的充分条件.     

一类带有脉冲出生和垂直传染的时滞SEIS传染病模型

建立并分析了一个带有脉冲出生、垂直传染和时滞的SEIS传染病模型.利用频闪映射得到了无病周期解的存在性,并得到了两个临界值R~*和R_*,当R~*<1时,无病周期解全局吸引,疾病消失;当R_*>1时,疾病持续.     

具脉冲收获与脉冲单边扩散的单种群动力学模型研究

建立了一类具脉冲收获与脉冲单边扩散在不同固定脉冲时刻的单种群动力学模型利用离散动力系统频闪映射理论,得到了脉冲收获的阈值.该结论说明只要收获量不超过其阈值通过扩散则种群可以保持持续生存.     

具有连续接种和脉冲接种的SIVR模型研究

考虑了具有连续接种和脉冲接种的SIVR传染病模型,得到了模型的基本再生数.对于连续接种模型,证明了当基本再生数R_0~c≤1时无病平衡点是全局稳定的;当R_0~c1时,无病平衡点是不稳定的,模型存在地方病平衡点,并且当δ=0时,地方病平衡点是全局渐近稳定的.对于脉冲接种模型,得到了无病周期解的存在性和稳定性.最后,对连续接种和脉冲接种进行了比较.     

Pulse vaccination strategy in the SIR epidemic model

Theoretical results show that the measles ‘pulse’ vaccination strategy can be distinguished from the conventional strategies in leading to disease eradication at relatively low values of vaccination. Using the SIR epidemic model we showed that under a planned pulse vaccination regime the system converges to a stable solution with the number of infectious individuals equal to zero. We showed that pulse vaccination leads to epidemics eradication if certain conditions regarding the magnitude of vaccination proportion and on the period of the pulses are adhered to. Our theoretical results are confirmed by numerical simulations. The introduction of seasonal variation into the basic SIR model leads to periodic and chaotic dynamics of epidemics. We showed that under seasonal variation, in spite of the complex dynamics of the system, pulse vaccination still leads to epidemic eradication. We derived the conditions for epidemic eradication under various constraints and showed their dependence on the parameters of the epidemic. We compared effectiveness and cost of constant, pulse and mixed vaccination policies.     

A State Dependent Pulse Control Strategy for a SIRS Epidemic System

With the consideration of mechanism of prevention and control for the spread of infectious diseases, we propose, in this paper, a state dependent pulse vaccination and medication control strategy for a SIRS type epidemic dynamic system. The sufficient conditions on the existence and orbital stability of positive order-1 or order-2 periodic solution are presented. Numerical simulations are carried out to illustrate the main results and compare numerically the state dependent vaccination strategy and the fixed time pulse vaccination strategy.     

一类具有饱和反应率的脉冲免疫接种的SIS模型

研究了具饱和传染率的脉冲免疫接种SIS模型,得到了无病周期解全局渐近稳定的充分条件和系统持续生存的充分条件．     

青藏高原人体脉搏测量及几种脉图对比分析

脉搏信息反映人体内部各器官的健康状况,利用PVDF压力传感器并垫一水囊间接接触法拾取脉搏信息,通过调理放大硬件电路对脉搏信号进行调理放大,借助虚拟仪器软件LabVIEW在PC机上架构虚拟脉搏测试系统,测试并采集了青藏高原地区大量不同人群的脉搏信息数据,给出了几种具有地域特征的脉图,并结合中医脉诊理论进行了对比分析。     

脉搏波时标对臂踝脉搏波传播速度测量的影响

臂踝脉搏波传播速度(brachial-ankle pulse wave velocity,baPWV)测量是一种便捷、无创的方法,可用于人体动脉硬化度的评估,在临床和科学研究中广泛应用于血管早期病变的筛查和心血管系统风险的评估。本文设计开发了人体上臂和踝部脉搏波波形采集系统,并利用该系统对59名健康成年人进行实验,研究了目前三种最常用的脉搏波时标(pulse timing mark,PTM)定义方法对baPWV测量的影响。实验结果表明,选用不同的PTM方法所测得的baPWV结果具有显著的差异性(P0.001)。而且,PTM方法的不同还影响到了baPWV与年龄、血压的相互关系。     

高血压患者脉搏波参数与脉搏波传导速度的相关性研究

目的:探讨高血压患者脉搏波参数与脉搏波传导速度的相关性,为从脉图上辨识高血压病及脉搏波参数的拓展应用提供参考。方法:选择2012年6月至2013年6月在北京安贞医院和北京人民医院门诊和住院确诊的原发性高血压患者32例作为实验组,并招募健康成人志愿者29例作为对照组。利用中医四诊合参辅助诊疗仪与皮尺分别采集两组受试者的左侧寸口脉图信息和主动脉至桡动脉的血管长度,计算脉搏波参数及脉搏波传导速度,采用方差分析和皮尔逊简单相关的统计方法分析高血压患者不同的脉搏波参数与其脉搏波传导速度的相关性。结果:与对照组比较,实验组的PWV显著升高,有显著性差异(P0.05)。实验组H2/H1明显高于对照组(P0.05),但H4/H1、T1/T、T2/T比值均显著低于对照组(P0.05),差异均有显著性意义(P0.05)。高血压患者的H2/H1、T1/T、T2/T、H4/H1均与其PWV相关,其中H2/H1与PWV呈显著正相关(P0.05),T1/T、T2/T与PWV呈显著负相关(P0.05),H4/H1与PWV呈一般正相关(P0.05)。结论:高血压患者的脉搏波参数与脉搏波传导速度具有显著相关性,且潮波出现的幅值与脉搏波传导速度有显著正相关;脉搏波上升支和潮波的时值与脉搏波传导速度具有显著负相关,重搏波相对高度与脉搏波传导速度具有一般相关关系,因而可通过脉搏波参数的变化了解高血压患者血管弹性的状态。     

Pulse domestication before cultivation

Comparative studies of the pulses of the Middle East and of their wild progenitors indicate that the pattern of pulse domestication is completely different from that of cereals in the same region. Wild legumes are not suitable for cultivation because of their conspicuous seed dormancy. Pre-adaptation of wild pulses for cultivation through loss of the seed dormancy mechanism apparently occurred in wild populations and may have been influenced by the gathering practices of man in pre-agricultural times. Pod indehiscence was of low value in pulse domestication and had evolved after the crop was well established and widespread.     

Impulsive Vaccination of an SEIRS Model with Time Delay and Varying Total Population Size

Pulse vaccination is an effective and important strategy for the elimination of infectious diseases. A delayed SEIRS epidemic model with pulse vaccination and varying total population size is proposed in this paper. We point out, if R* < 1, the infectious population disappear so the disease dies out, while if R _*; > 1, the infectious population persist. Our results indicate that a long period of pulsing or a small pulse vaccination rate is sufficient condition for the permanence of the model.     

Population dynamics of live-attenuated virus vaccines

Viruses contained in live-attenuated virus vaccines (LAVV) can be transmitted between individuals, resulting in secondary or contact vaccinations. This fact has been exploited successfully in the use of the Oral Polio Vaccine (OPV) to better control wild-type polio viruses. In this work we analyze general LAVV vaccination models for infections that confer lifelong immunity. We consider both standard (continuous) vaccination strategies and pulse vaccination programs (where mass vaccination is carried out at regular intervals). For continuous vaccination, we provide a complete global analysis of a very general compartmental ordinary differential equation LAVV model. We find that the threshold vaccination level required for the eradication of wild-type virus depends on the basic reproduction numbers of both the wild-type and vaccine viruses, but is otherwise independent of the distributions of the durations in each of the sequence of stages of disease progression (e.g., latent, infectious, etc.). Furthermore, even for vaccine viruses with reproduction numbers below one, which would naturally fade from the population upon cessation of vaccination, there can be a significant reduction in the threshold vaccination level. The dependence of the threshold vaccination level on the virus reproduction numbers largely generalizes to the pulse vaccination model. For shorter pulsing periods there is negligible difference in threshold vaccination level as compared to continuous vaccination campaigns. Thus, we conclude that current policy in many countries to employ annual pulsed OPV vaccination does not significantly diminish the benefits of contact vaccination.     

不同年龄段人体脉搏的测量与分析

人体内部各器官的健康状态可以在脉搏信息中反映出来,要使脉诊技术客观化,除了获取准确的脉搏信息外,还必须对大量不同人群的脉搏信息进行对比分析,提取有关的特征参量。利用PVDF压力传感器并垫一水囊间接接触法拾取脉搏信息,通过调理放大硬件电路和数据采集处理系统实现人体脉搏的测量,给出了不同年龄段人群的脉图及对应的频谱图,并进行了对比分析。