环境敏感因子是沉积环境演化研究中的重要参数,其提取方法有多种,不同方法在海湾内应用成果相对较少。文章根据山东半岛威海湾WH-05岩心(钻探深度18.2 m)高分辨率(2 cm)粒度分析结果,采用基本端元模拟算法(BasEMMA)、粒级—标准偏差法...环境敏感因子是沉积环境演化研究中的重要参数,其提取方法有多种,不同方法在海湾内应用成果相对较少。文章根据山东半岛威海湾WH-05岩心(钻探深度18.2 m)高分辨率(2 cm)粒度分析结果,采用基本端元模拟算法(BasEMMA)、粒级—标准偏差法和粒级旋转主成分分析法(V-PCA)提取了环境敏感因子,结合AMS14C数据,对不同方法提取的环境敏感因子进行了对比分析,探讨了其对季风强度变化的响应关系。结果表明:8.4 ka B.P.以来威海湾沉积物类型均为粉砂,粉砂含量为主、黏土含量次之、砂含量较少,以跳跃组分为主,悬浮组分次之。BasEMMA和粒级—标准偏差法提取的3个敏感粒级范围(2.6~11.0μm、31.3~63.4μm、256.9~500.0μm)总体一致,能较好地反映东亚季风长周期变化事件(8.4~6.5 ka B.P.东亚季风强度减弱;6.5 ka B.P.至今东亚季风强度增强);V-PCA提取的环境敏感因子,能较好地反映东亚季风短周期变化事件(如明清小冰期、西汉小冰期事件等)。以上三种方法提取的环境敏感因子指示了研究区气候变化,对研究区沉积环境具有较好的指示作用。展开更多
In this paper, a disease transmission model with two treatment stages is proposed and analyzed. The results indicate that the basic reproduction number is a critical threshold for the prevalence of the disease. If the...In this paper, a disease transmission model with two treatment stages is proposed and analyzed. The results indicate that the basic reproduction number is a critical threshold for the prevalence of the disease. If the basic reproduction number is less than one, the disease free equilibrium is globally asymptotically stable. Otherwise, the endemic equilibrium is globally asymptotically stable. Therefore, besides the basic reproduction number, a new marker for characterizing the seriousness of the disease, named as dynamical final infective size, is proposed, which differs from traditional final size because the proposed model includes the natural birth and death. Finally, optimization strategies for limited medical resources are obtained from the perspectives of basic reproduction number and dynamical final infective size, and the real-world disease management scenarios are given based on these finding.展开更多
文摘环境敏感因子是沉积环境演化研究中的重要参数,其提取方法有多种,不同方法在海湾内应用成果相对较少。文章根据山东半岛威海湾WH-05岩心(钻探深度18.2 m)高分辨率(2 cm)粒度分析结果,采用基本端元模拟算法(BasEMMA)、粒级—标准偏差法和粒级旋转主成分分析法(V-PCA)提取了环境敏感因子,结合AMS14C数据,对不同方法提取的环境敏感因子进行了对比分析,探讨了其对季风强度变化的响应关系。结果表明:8.4 ka B.P.以来威海湾沉积物类型均为粉砂,粉砂含量为主、黏土含量次之、砂含量较少,以跳跃组分为主,悬浮组分次之。BasEMMA和粒级—标准偏差法提取的3个敏感粒级范围(2.6~11.0μm、31.3~63.4μm、256.9~500.0μm)总体一致,能较好地反映东亚季风长周期变化事件(8.4~6.5 ka B.P.东亚季风强度减弱;6.5 ka B.P.至今东亚季风强度增强);V-PCA提取的环境敏感因子,能较好地反映东亚季风短周期变化事件(如明清小冰期、西汉小冰期事件等)。以上三种方法提取的环境敏感因子指示了研究区气候变化,对研究区沉积环境具有较好的指示作用。
文摘In this paper, a disease transmission model with two treatment stages is proposed and analyzed. The results indicate that the basic reproduction number is a critical threshold for the prevalence of the disease. If the basic reproduction number is less than one, the disease free equilibrium is globally asymptotically stable. Otherwise, the endemic equilibrium is globally asymptotically stable. Therefore, besides the basic reproduction number, a new marker for characterizing the seriousness of the disease, named as dynamical final infective size, is proposed, which differs from traditional final size because the proposed model includes the natural birth and death. Finally, optimization strategies for limited medical resources are obtained from the perspectives of basic reproduction number and dynamical final infective size, and the real-world disease management scenarios are given based on these finding.
