保险精算中双损失环境的"独立性"问题

保险精算中,双损失环境理论对于寿险风险分析和风险控制具有极其重要的意义,而且也是进行寿险产品设计的基础.本文在双损失环境理论的基础上,用概率论的方法,尝试对,P(τ)x等于tP'x(d)与tP'x(w)的乘积成立的独立性条件给出新的解释,并对一些学者的"独立性是矩估计成立的充分条件"等观点提出了不同的看法,并证明了基本矩关系不依赖于独立性的假设而恒成立.     

福建九龙江口凤鲚的生物学特征

利用2010年9月至2013年8月每季度从福建九龙江口的紫泥、岛美、浮宫3个站点的定置张网和流刺网渔获物中采集的凤鲚样本,分析凤鲚的生物学特性.结果表明:1)九龙江口凤鲚体长分布范围为44~239 mm,优势体长为140~160 mm,体重分布范围为0.20~69.10 g,优势体重为0.20~20 g,体长与体重的关系式为W=1.3×10-6 L3.23(R2=0.88,P<0.01,n=927),体长生长方程为Lt =246.75[1-e-0.65(t+0.21)],体重生长方程为Wt=64.94[1-e–0.65(t+0.21)]3.23 ,由此可将凤鲚看做匀速生长的鱼类;2)凤鲚夏季洄游至九龙江产卵,性成熟以Ⅴ期为主,冬季摄食强度最强;3)凤鲚的总死亡系数、自然死亡系数和捕捞死亡系数分别为2.0、0.67和1.33.结果说明九龙江口凤鲚资源已经处于过度开发状态,需要采取合理的保护和限制捕捞措施.     

基于森林资源清查数据的江西省主要森林类型净生产力研究

【目的】基于江西省2011年和2016年的森林资源清查数据,分别估算不同森林类型的净生产力,为森林资源科学经营提供依据。【方法】以江西省2011年和2016年两期森林资源清查数据为样本,采用生物量回归模型法,在样木水平上计算单木生物量、累计样地水平生物量并扩大到总体水平,测算乔木层生物量的生长量和枯损量,结合乔木层生物量结果估测灌木层和草本层,并估算不同森林类型的净生产力。【结果】综合考虑森林乔木层生长与枯损、林下灌木层、草本层生物量,基于复位样木,由单木生物量模型得到样地生物量,进而计算江西省主要森林类型的净生产力,得出阔叶混交林的净生产力最高,针阔混交林次之,而针叶林和阔叶纯林的净生产力较低。2011—2016年,江西省森林平均净生产力为7.28 t/(hm²·a),阔叶混交林净生产力最高为11.26 t/(hm²·a)。【结论】在国家标准框架下的森林净生产力估算模式,可为更大范围内、统一标准下客观准确评估森林净生产力提供参考。     

Two‐Dimensional Kernel Smoothing of Mortality Surface: An Evaluation of Cohort Strength

Accurate mortality forecasts are of primary interest to insurance companies, pension providers and government welfare systems owing to the rapid increase in life expectancy during the past few decades. Existing mortality models in the literature tend to project future mortality rates by extracting the observed patterns in the mortality surface. Patterns found in the cohort dimension have received a considerable amount of attention and are included in many models of mortality. However, to our knowledge very few studies have considered an evaluation and comparison of cohort patterns across different countries. Moreover, the answer to the question of how the incorporation of the cohort effect affects the forecasting performance of mortality models still remains unclear. In this paper we introduce a new way of incorporating the cohort effect at the beginning of the estimation stage via the implementation of kernel smoothing techniques. Bivariate standard normal kernel density is used and we capture the cohort effect by assigning greater weights along the diagonals of the mortality surface. Based on the results from our empirical study, we compare and discuss the differences in cohort strength across a range of developed countries. Further, the fitting and forecasting results demonstrate the superior performance of our model when compared to some well‐known mortality models in the literature under a majority of circumstances. Copyright © 2016 John Wiley & Sons, Ltd.     

河北省仔猪黄白痢流行病学调查及致病菌的分离与鉴定

仔猪黄白痢是危害养猪业的一种常见疾病.通过对河北省不同地区17家猪场的走访调查,探讨仔猪黄白痢大规模爆发的原因和防治对策,并从某猪场发病仔猪的排泄物中分离得到1株菌,经形态学、生物化学和分子生物学实验鉴定,该分离株为革兰氏阴性菌,克氏三糖铁培养产酸产气,LTB与M17873核苷酸序列同源性为100 %,该菌株确定为产肠毒素型大肠杆菌.     

婴儿死亡率的曲面拟合探讨

以出生体重和孕周信息描述婴儿死亡率,且用样条函数进行曲面拟合,获得最低死亡率．     

北部湾多鳞鱚生长与死亡参数的估算

利用2008年3-9月北部湾底拖网和刺网渔获物中采集的样本,对北部湾多鳞鱚的生长、死亡特性进行了初步研究,并利用单位补充量产量模型对多鳞鱚渔业的开发状态进行了评估。结果表明:北部湾多鳞鱚优势体长为100～130mm,占60.71%;优势体重为5～25g,占83.96%;雌性个体略大于雄性个体,性比为1:1.36,雌雄个体数量不平衡;von Bertalanffy生长方程的参数分别为:L∞=188.6mm,K=0.51,t0=-0.32;体重的生长拐点年龄为1.86龄;总死亡系数、自然死亡系数和捕捞死亡系数分别为2.58、1.217和1.36;渔业生物学参考点F0.1和Fmax的值分别为0.34和0.50,渔业资源已处于过度利用状态。     

胆红素对小鼠腹水型肝癌细胞与人肝癌细胞光敏反应的比较

不同浓度（３８,３．８,０．３８,０．０３８μｍｏｌ／Ｌ）的胆红素光敏反应能使得水型肝癌细胞和人肝癌细胞致死,死亡率随温度的增加和照光时间的延长而加剧,Ｈｅｐ Ｈ细胞死亡率明显高于人肝癌细胞,避光细胞也有一定的死亡,说明胆红素本身对细胞也有一定的损伤。     

Effects of water acidification on the distribution pattern and the reproductive success of amphibians

Summary Nine amphibian species were encountered in poorly buffered waters of The Netherlands (alkalinity 1 meq·l^–1). These soft water systems are highly sensitive to acidifying precipitation. The number of species as well as the percentage of waters which harbour amphibian populations are strongly reduced in the extremely acid pH-class . The reproductive success of amphibians is negatively affected by low pH. The eggs become heavily infested with fungi (Saprolegniaceae). In acidifying systems many physico-chemical parameters are significantly correlated with the pH of the water. Strongly acidified waters are characterized by low alkalinity, conductivity and ionic content but high acidity and high concentrations of (heavy) metals and ammonium and a high relative sulphate concentration. Culture experiments with eggs and larvae ofRana arvalis. Rana esculenta, Rana temporaria andBufo bufo show that apart from the pH, elevated aluminium, cadmium and ammonium contents may also affect the reproductive success of amphibians.     

昆明市2005年—2007年省、市级医院住院病人疾病分析

目的：了解昆明市省级、市级综合性医院住院的病人疾病谱的变化情况及疾病谱前5位疾病治疗转归情况。方法：回顾性分析昆明市省级、市级医院2005年—2007年住院病人前12位疾病构成及顺位,分析前5位疾病的治愈率、好转率、未愈率及死亡率等情况,疾病分类按ICD—10统计分类。结果：呼吸系统疾病,循环系统疾病,消化系统疾病,肿瘤,妊娠、分娩和产褥期疾病,位于疾病谱的前5位。妊娠分娩的疾病治愈率较高,循环系统好转率较高,肿瘤死亡率较高。结论：应加强对呼吸系统、循环系统及肿瘤等疾病的预防和诊治,找出疾病分布规律,更好地提供卫生医疗服务。