疟原虫入侵与红细胞内吞作用

用透射电镜观察红内期鼠疟原虫的入侵过程,发现红细胞在与裂殖子实际接触之前就发生很多种形状变化,主要有杯状和伪足两种类型。前者是红细胞与裂殖子相邻的一侧弯曲,形成与裂殖子表面相适应的凹陷;后者则是红细胞伸出突起或伪足逐渐接近裂殖子。附着之后,即逐渐扩展将其包围。在入侵中、后期,红细胞凹陷口周围呈波浪形突出,或者口部升高,凹陷壁逐渐变薄,有明显的前进趋势。这表明,红细胞在裂殖子诱导下,内吞活性增强了,有能力进行变形运动,包围裂殖子,从而以这种方式形成纳虫泡和使裂殖子进入其胞体内。     

INVASION OF THE SERENGETI NATIONAL PARK BY ELEPHANTS

1. Elephants were first recorded in the Serengeti in 1955 and were probably absent f or at least the previeras 40 years.
2. Elephant numbers have inereased, mainly through immigration, to their present level of approximately 2,000 and have remained at this level for the last three years.
3. Vegetation changes caused by elephants in the Serengeti include the destruction of the larger trees at the rate of at least six per cent, per year.
4. Recovery of the woodfends from the effeets of elephants is retarded by the inhibiting effeets of bush fires on the regeneration of young trees.
5. The policy and management implications of the elephant invasion are discussed.     

STATISTICAL ANALYSES FOR R-INDEX

R‐index is an important statistic for testing and measuring product effects. The validation and merits of R‐index are to a great extent due to the fact that it is closely related to the famous Mann–Whitney U statistic. Based on this fortunate relationship, statistical analyses for R‐index are explored. The statistical analyses include estimations of R‐index and its null and nonconditional variances with and without assuming continuity of data; difference and similarity tests using R‐index; powers and sample sizes for the tests; linking R‐index with Thurstonian δ (or d′). The new techniques developed in the paper extend greatly the original R‐index analysis for categorical ratings data. It is expected that the recognition of the profound theoretical origin of R‐index and the available statistical analyses for R‐index will provide the impetus for the resurgence of interest in using R‐index in sensory and consumer researches.