On the latent state estimation of nonlinear population dynamics using Bayesian and non-Bayesian state-space models

Nonlinear state-space models have been increasingly applied to study population dynamics and data assimilation in environmental sciences. State-space models can account for process error and measurement error simultaneously to correct for the bias in the estimates of system state and model parameters. However, few studies have compared the performance of different nonlinear state-space models for reconstructing the state of population dynamics from noisy time series. This study compared the performance of the extended Kalman filter (EKF), unscented Kalman filter (UKF) and Bayesian nonlinear state-space models (BNSSM) through simulations. Synthetic population time series were generated using the theta logistic model with known parameters, and normally distributed process and measurement errors were introduced using the Monte Carlo simulations. At higher levels of nonlinearity, the UKF and BNSSM had lower root mean square error (RMSE) than the EKF. The BNSSM performed reliably across all levels of nonlinearity, whereas increased levels of nonlinearity resulted in higher RMSE of the EKF. The Metropolis–Hastings algorithm within the Gibbs algorithm was used to fit the theta logistic model to synthetic time series to estimate model parameters. The estimated posterior distribution of the parameter θ indicated that the 95% credible intervals included the true values of θ (=0.5 and 1.5), but did not include 1.0 and 0.0. Future studies need to incorporate the adaptive Metropolis algorithm to estimate unknown model parameters for broad applications of Bayesian nonlinear state-space models in ecological studies.     

Estimating the complexity of bird song by using capture-recapture approaches from community ecology

Repertoire size, the number of unique song or syllable types in the repertoire, is a widely used measure of song complexity in birds, but it is difficult to calculate this exactly in species with large repertoires. A new method of repertoire size estimation applies species richness estimation procedures from community ecology, but such capture-recapture approaches have not been much tested. Here, we establish standardized sampling schemes and estimation procedures using capture-recapture models for syllable repertoires from 18 bird species, and suggest how these may be used to tackle problems of repertoire estimation. Different models, with different assumptions regarding the heterogeneity of the use of syllable types, performed best for different species with different song organizations. For most species, models assuming heterogeneous probability of occurrence of syllables (so-called detection probability) were selected due to the presence of both rare and frequent syllables. Capture-recapture estimates of syllable repertoire size from our small sample did not differ significantly from previous estimates using larger samples of count data. However, the enumeration of syllables in 15 songs yielded significantly lower estimates than previous reports. Hence, heterogeneity in detection probability of syllables should be addressed when estimating repertoire size. This is neglected using simple enumeration procedures, but is taken into account when repertoire size is estimated by appropriate capture-recapture models adjusted for species-specific song organization characteristics. We suggest that such approaches, in combination with standardized sampling, should be applied in species with potentially large repertoire size. On the other hand, in species with small repertoire size and homogenous syllable usage, enumerations may be satisfactory. Although researchers often use repertoire size as a measure of song complexity, listeners to songs are unlikely to count entire repertoires and they may rely on other cues, such as syllable detection probability.Communicated by A. Cockburn     

白菜叶绿体DNA快速提取及分析

采用SDS-蛋白酶法提取了白菜的叶绿体DNA.琼脂糖电泳及紫外分光光度分析表明,所提取的叶绿体DNA质量高,除cpDNA主环外,在胞质雄性不育新种质及原不育系中还存在约1375bp和831bp的两条质粒分子.用所提取的叶绿体DNA作为模板进行RAPD扩增,获得了清晰的扩增图谱.该方法与传统的提取方法相比省时、高效、无污染.图2表1参14     

一种提取氧化葡萄糖酸杆菌山梨糖脱氢酶的简单方法

利用表面活性剂TritonX-100建立一种提取和测定氧化葡萄糖酸杆菌（Gluconobacter oxydans)L-山梨糖脱氢酶（L-sorbose dehydrogenaseSDH)活性的简便方法，最适提取条件为：TritonX-100浓度ψ（Triton)/%=0.3。提取温度θ=4℃，处理时间t/h=6-10h；用于提取的菌悬液D550nm范围0.090-0.252。该方法提取效率为细胞碎片法的97.83%。图2表2参7     

GIS支持下的红壤丘陵区脆弱生态环境综合评价--以长沙市为例

遥感和地理信息系统技术的发展为研究区域生态环境变化提供了有效的手段。针对红壤丘陵区这一特定区域，在地理信息系统的支持下，建立了红壤丘陵区环境信息系统数据库；同时结合特尔斐法、层次分析法及环境质量综合指数法，对红壤丘陵区的典型区域——长沙市的生态环境质量进行综合评价。研究结果表明，由于人类活动的强烈影响，长沙市环境质量状况良好以上级别的区域面积仅有827．64km^2，占总面积的7．0％；而生态环境较差的区域其面积达到6187．14km^2，占总面积的52．4％，这说明长沙市总体生态环境质量有待进一步提高。     

能源甘蔗主要经济和光合性状的遗传分析

以 4× 5不完全双列杂交 (NcII)衍生的 2 0个家系实生苗为材料 ,对其主要经济和光合性状的遗传力和配合力进行分析 .结果表明 :(1)锤度、株高和茎径的遗传主要由加性基因效应引起 ,而丛有效茎数、丛重、锤重和地上部鲜重的遗传主要由非加性基因效应引起 ;(2 )配合力分析表明 ,CP84 / 1198、CP74 / 383、崖 90 / 3、桂 73/ 16 7和科 5各性状 gca较大 ,是较好的高生物量高光效亲本 ,CP84 / 1198×Ya 90 / 3、CP85 / 14 32×桂 73/ 16 7、CP74 / 383×桂 73/ 16 7、CP85 /14 32×科 5各性状sca和tca较大 ,为较好的高生物量高光效组合 ;(3)茎径、锤度和丛重母本gca方差大于父本 gca方差 ,丛有效茎数、锤度和地上部鲜重的广义遗传力在 5 0 %以上 .表 7参 16     

Variance estimation in the EMAP strategy for sampling discrete ecological resources

The United States Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) is designed to describe status, trends and spatial pattern of indicators of condition of the nation's ecological resources. The proposed sampling design for EMAP is based on a triangular systematic grid and employs both variable probability and double sampling. The Horvitz-Thompson estimator provides the foundation of the design-based estimation strategy used in EMAP. However, special features of EMAP designed to accommodate the complexity of sampling environmental resources on a national scale require modifications of standard variance estimation procedures as well as development of new techniques. An overview of variance estimation methods proposed for application to EMAP's sampling strategy for discrete resources is presented.     

城市人居环境评价体系的研究及应用

在国内外人居环境理论研究及实践的基础上,提出了由系统层、子系统层和指标层构成的城市人居环境评价指标体系,其中系统层由社会经济环境、自然生态环境、公共设施建设、环境资源保护和环境管理能力五部分组成,子系统层由16个指标组成,指标层由43个具体指标组成。利用统计分析法(Delphi)确定各指标的权值。同时,针对本指标体系结构提出了单项评价和综合评价相结合的评价模式,并设置了城市人居环境质量指数和系统协调度两个综合性指标来全面评价城市人居环境质量。通过对重庆市渝北城区的综合评价,评价结果较客观地反映了该城区的实际。     

用同位素标记LZF—1 DNA指纹探针进行人的DNA指纹分析

同位素γ－32P－ATP对LZF－1DNA指纹探针作5＇末端标记后，检测成都地区人群中84名随机个体的DNA指纹，获得了清晰易辨的具有高度个体特异性的DNA指纹图谱．谱带平均数为17．667条，平均等位基因频率为0．167，探针的鉴别机率为4．862×10－10．表明LZF－1DNA指纹探针完全达到了法医学检验中鉴别个体的目的．     

双波长标准加入法同时测定水中硝酸盐和亚硝酸盐

本文应用双波长标准加入法同时测定了硝酸盐和亚硝酸盐，在研究硝酸盐和亚硝酸盐紫外光谱的基础上，精确选择亚硝酸盐等吸收点波长２０２．５ｎｍ，２１６．５ｎｍ为测定波长。亚硝酸盐含量回归方程经推导得Ｃ＝－３．８４１＋１５６．６Ａ，相关系Ｒ＝１．０００。将该法用于合成样品及实际水样分析，所得结果较满意。