蜀柏毒蛾种群抽样技术的研究

根据蜀柏毒蛾的空间格局参数及株内分布规律,参照Morris(1960)的标准和Iwao(1971)的模型,对蜀柏毒蛾种群样本单元进行选择,确定以株为样本单元,并选择平行线式,Z字形式、棋盘式取样方法,列出了允许误差D=0.05,0.10,0.20,0.50时和不同虫口密度下的理论抽样数表。依照Kuno(1969)模型建立了序贯抽样表。     

Total observed error,total allowable error,and QC rules for canine serum and urine cortisol achievable with the Immulite 2000 Xpi cortisol immunoassay

Determining a simple quality control (QC) rule for daily performance monitoring depends on the desired total allowable error (TEa) for the measurand. When no consensus TEa exists, the classical approach of QC rule validation cannot be used. Using the results of previous canine serum and urine cortisol validation studies on the Immulite 2000 Xpi, we applied a reverse engineering approach to QC rule determination, arbitrarily imposing sigma = 5, and determining the resulting TEa for the QC material (QCM; TEa_QCM) and the resulting probability of error detection (P_ed) for each QC rule. For the simple QC rule 1_2.5S with P_ed = 0.96 and probability of false rejection (P_fr) = 0.03, the associated TEa_QCM were 20% and 35% for serum and 28% and 24% for urine QCM1 and QCM2. If these levels of TEa_QCM are acceptable for interpretation of patient sample results, then users can internally validate the 1_2.5S QC rule, provided that their QCM CVs and biases are similar to ours. Otherwise, more stringent QC rules can be validated by using a lower sigma to lower the TEa_QCM. With spiked samples (relevant cortisol concentrations in the veterinary patient matrix) at 38.6 and 552 nmol/L of cortisol, TEa_QCM at sigma = 5 were much higher (54% and 40% for serum; 90.3% and 42.8% for urine). Spiked samples generate TEa that is probably too high to be suitable for daily QC monitoring; however, it is crucial to verify spiked sample observed total error (TEo; 26% and 18% for serum, 60% and 30% for urine) < TEa_QCM, and to use spiked sample TEo for patient result interpretation. In the absence of consensus TEa for cortisol in dogs, we suggest the use of a 1_2.5S rule, provided that users accept the associated level of TEa_QCM also as clinical TEa for results interpretation.     

Faecal Sampling Underestimates the Actual Prevalence of Salmonella in Laying Hen Flocks

Summary In all European Union member states, Salmonella monitoring in poultry flocks is obligatory. In these monitoring programmes, a limited number of pooled faeces and/or dust samples are collected to determine whether Salmonella is present in the flocks or not. Whether these limited sampling protocols are sufficiently sensitive to detect expected low within‐flock prevalences of an intermittently shed pathogen is not yet clear. In this study, a comparison is made between different sampling procedures for the assessment of the between‐ and within‐flock prevalence of Salmonella in laying hens. In total, 19 farms were sampled. Using a comparable sampling methodology as in the official surveillance programmes, Salmonella could not be detected in any of the flocks. After transportation of the hens to the laboratory and subsequent analysis of cloacal swabs and caecal contents, Salmonella Enteritidis was detected in laying hens from five of 19 farms. The observed within‐flock prevalence ranged from 1% to 14%. Based on the results of this study, it can be expected that, depending on the sampling procedure, different estimates of the prevalence of Salmonella can be obtained and the proportion of Salmonella infected flocks is underestimated based on the results of the official monitoring programme.     

桃蛀螟幼虫在板栗上的空间分布型研究

通过对不同板栗园桃蛀螟Dichocrocis punctiferalis Guenee幼虫的调查,用昆虫分布型的4种常用理论公式分别进行配合适度的χ2检验,再用6种空间分布型聚集度指标、Taylor幂法则及Iwao回归法对桃蛀螟幼虫的空间分布型进行测定。结果表明:桃蛀螟幼虫种群在板栗园中全部呈聚集分布,而且均符合负二项分布,其聚集原因是由该虫习性与环境因素共同造成的。此外,还利用了分布型参数确定了桃蛀螟幼虫的理论抽样数。     

甘肃狭啮卵在花椒园中的空间分布型及抽样技术

应用6种分布型指数法分析判定了甘肃狭啮Stenopsocus gansuensis卵在花椒园中的空间分布型,利用Taylor幂法则和Iwao回归方程分析聚集原因,结果表明,田间甘肃狭啮卵呈聚集分布,kc值为2.7934,符合负二项分布;其种群聚集原因是由本身行为习性所致。在此基础上,应用Iwao的理论抽样数模型建立了甘肃狭啮卵的田间理论抽样数公式：N=（t/D）2（1.7673）/m＋0.19887;根据Kuno新的序贯抽样法通式建立了该种群序贯抽样公式：Tn=1.7673/（D20-0.19887/n）。     

A standardized procedure for surveillance and monitoring European habitats and provision of spatial data

Both science and policy require a practical, transmissible, and reproducible procedure for surveillance and monitoring of European habitats, which can produce statistics integrated at the landscape level. Over the last 30 years, landscape ecology has developed rapidly, and many studies now require spatial data on habitats. Without rigorous rules, changes from baseline records cannot be separated reliably from background noise. A procedure is described that satisfies these requirements and can provide consistent data for Europe, to support a range of policy initiatives and scientific projects. The methodology is based on classical plant life forms, used in biogeography since the nineteenth century, and on their statistical correlation with the primary environmental gradient. Further categories can therefore be identified for other continents to assist large scale comparisons and modelling. The model has been validated statistically and the recording procedure tested in the field throughout Europe. A total of 130 General Habitat Categories (GHCs) is defined. These are enhanced by recording environmental, site and management qualifiers to enable flexible database interrogation. The same categories are applied to areal, linear and point features to assist recording and subsequent interpretation at the landscape level. The distribution and change of landscape ecological parameters, such as connectivity and fragmentation, can then be derived and their significance interpreted.     

模型误差几种估计方法的比较及应用

本文对林业实践中模型预测误差、预测相对误差的估计方法进行了讨论和比较,从非参数性方法导出了预测误差、预测相对误差的简捷估计方法,这些方法具有明确的统计意义,可用来检验模型的适用性,评价模型优劣.文中给出了估测森林蓄积量不同模型评价的实例.     

五脑山枳椇天然种群分布格局研究

以麻城市五脑山枳椇天然种群为研究对象设置4块样地,采用相邻格子法进行每木调查,并采用Poisson分布拟合及χ^2检验等测度方式,对枳椇种群空间分布格局及聚集强度进行研究。结果表明:枳椇种群不同龄级植株均呈聚集分布;幼龄植株分布格局强度和种群聚集强度均高于中龄植株;随取样尺度的增大,种群分布格局升高,聚集强度下降,平均拥挤度上升;不同的取样尺度中,幼龄植株、中龄植株和全部种群植株分布格局均未出现分布拐点。     

经济不合格品率及其确定方法的研究

人们往往希望不合格品率为零，但本文认为对于工序不合格品率应控制在１个经济合理的水平，因此，本文通过经济抽检间隔数学模型的建立，给出经济不合格品率的计算公式，并指出了实现方法，从而为企业经济合理地进行工序质量控制提供帮助。