Gap-based inverse sampling

We present a new inverse sampling design for surveys of rare events, Gap-Based Inverse Sampling. In the design, sampling stops if after a predetermined interval, or gap, no new rare events are found. The length of the gap that follows after finding a rare event is used as a way of limiting sample effort. We present stopping rules using decisions based on the gap length, the total number of rare events found, and a fixed upper limit of survey effort. We illustrate the use of the design with stratified sampling of two biological populations. The design uses the intuitive behavior of a field biologist in stratified sampling, where if in a stratum nothing is found after a long search, the field surveyor would like to consider the stratum is empty and stop searching. Our design has appeal for surveying rare events (for example, a rare species) with stratified sampling where there are likely to be some completely empty strata.     

自身免疫研究进展

自身免疫是一种述人和复杂的现象。自身耐受、自身免疫性疾病以及细胞凋亡，与自身免疫有着密切的关系。这以上各种机制正处于研究阶段，此文就该领域的一些进展作些报道。     

鄂北高贵山珍稀树木及其保护对策

统计了鄂北高贵山珍用然濒危树木21种,其中 ,有国家I级保护植物1种,I保护植物60种,分布有青檀群落4hm2,香果树群落0．5hm2和小片的闽楠群,本文在对各种珍稀树木的生态,分布,保护价值进行描述的基础上,提出了保护措施。     

高Hcy在缺血性脑血管病中的临床意义

目的观察探讨缺血性脑血管病患者血同型半胱氨酸（Hcy）水平与颈动脉粥样硬化（CAAs）程度的关系,探讨Hcy在缺血性脑血管病中的临床意义。方法对108名缺血性脑血管病患者以血管超声检查双侧颈总动脉、颈内动脉,按照颈动脉斑块大小分为A、B两组;取空腹静脉血,测定胆固醇、甘油三酯、血糖、纤维蛋白原、叶酸、VitB12及Hcy水平,对Hcy水平与CAAs、叶酸、VitB12及其他因素进行相关分析。结果随着CAAs程度的加重,Hcy水平升高,两组之间存在统计学差异（P〈0.01）;统计学分析表明Hcy与叶酸、VitB12水平呈负相关（P〈0.05）,叶酸、VitB12水平随CCAs的加重而降低。结论高Hcy血症是CAAs的一个重要的危险因素,是缺血性脑血管病的独立危险因素。     

Forecasting the cost of U.S. Health Care in 2040

One of the most important debates among health economists in rich nations is whether advances in biotechnology will spare their health care systems from a financial crisis. We must consider that prevalence rates of chronic diseases declined during the twentieth century and that this rate of decline has accelerated. However, health care costs may continue to increase even as the age of onset of chronic diseases is delayed, because the proportion of a cohort living to late ages will increase. The accelerating decline in the prevalence of chronic diseases during the course of the twentieth century supports the proposition that increases in life expectancy during the twenty-first century will be fairly large, but the effect on health care in the U.S. will be modest. The income elasticity for health services is calculated at 1.6, meaning that income expenditures on health care in the U.S. are likely to rise from a current level of about 15 percent to about 29 percent of GDP in 2040.     

Revisit of a randomized response model for estimating a rare sensitive attribute under probability proportional to size sampling using Poisson probability distribution

The present article deals with the estimation of mean number of individuals possess a rare sensitive attribute using Poisson probability distribution, when the population consists of clusters. Unbiased estimation procedures for the mean number of individuals have been suggested and their properties are discussed when the parameter of a rare non-sensitive unrelated attribute is assumed to be known as well as unknown. The suggested estimation procedure is further discussed for situation of stratified cluster population. Empirical studies are carried out to show the dominance of proposed method and resultant estimators over a well-known contemporary estimator.     

F-tests with a rare pathology

ANOVA is routinely used to compare pathologies. Nevertheless, in many situations, the sample dimensions may not be known when planning the study. This is specially relevant when one of the pathologies is rare. Thus, the sample size for that pathology or for all pathologies must be considered as random. Sample selection for the non-rare pathologies may be carried out to increase the balance of the model. This leads to F-tests with random non-centrality parameters and random degrees of freedom for the errors. The distribution of such tests statistics is obtained.     

浙江缙云骨洞坑萤石矿床成矿流体特征

浙江缙云骨洞坑大型萤石矿床位于华夏古板块北东端，紧邻钦杭结合带。矿床产出于下白垩统馆头组与燕山晚期花岗岩的接触带中，矿体严格受NW向断裂控制。在系统的地质调查基础上，对其微量和稀土元素及流体包裹体开展研究。结果表明，缙云骨洞坑萤石矿轻稀土相对弱富集，重稀土相对弱亏损，具有较强的Eu负异常以及较弱的Ce负异常，配分曲线表现出典型的“V”字特征。La/Ho-Y/Ho图解表明，不同位置萤石样品表现出重结晶方向演化的趋势。Tb/Ca-Tb/La成因图解表明骨洞坑萤石矿属于热液成因类型矿床。流体包裹体测温结果表明，成矿均一温度主要在150~190℃，盐度主要在0.3%~1.5% NaCleqv，密度平均值为0.86 g/m³，成矿流体应属于中-低温、低盐度、低密度的NaCl-H₂O体系。结合地质特征认为，缙云骨洞坑萤石矿床属中低温热液裂隙充填型矿床。     

Vaginal Douching Practices Among Women Attending a University in the Southern United States

Abstract

The authors assessed the frequency, characteristics, and motivational antecedents of vaginal douching practices among 125 White and 155 Black female college students. Overall, 40% of the students had ever douched and half of those women currently douche. Black women were most likely to be encouraged to douche by their mothers, whereas White women were more influenced by television advertisements. Among the sexually active women, being Black, using oral contraceptives, using spermicides, and being encouraged to douche by their mothers or by the media were independently associated with ever having douched. These associations were present among both Black and White women and were stronger when current douching was compared with never having douched. Women who were discouraged from douching by a physician or nurse were more likely to have stopped the practice. Douching is common, even among educated young women; nurses' and physicians' advice to stop douching appears to have a salutary effect.     

Factors Influencing Condom Use and STD Acquisition Among African American College Women

Abstract

To identify factors that influence condom use and the risk of acquiring sexually transmitted diseases (STDs) among African American college women, the authors surveyed a sample of 123 sexually experienced undergraduate women at a state university. The college women who were older, had initiated sex earlier, or had more recent sexual partners were more likely than others in the study to report a history of an STD. The findings have implications for prevention and intervention programs for African American college women.