The waiting game: how long is long enough?
The time it takes to recruit patients into a clinical trial has a major impact on whether a drug development programme completes on time. Here Byron Jones explains how simple statistical models can be very useful in predicting the time to complete recruitment.
The Poisson Distribution
Many rare events occur at random in time or space, for example, the number of radioactive disintegrations per minute or the number of bacteria per unit area of Petri dish. The probability of obtaining 0, 1, 2, 3, etc., events follows a simple mathematical formula developed by Poisson. After presenting the basic information, the chapter describes methods for setting confidence limits, determining sample size, and comparing groups. Ways of determining cumulative probabilities are given, for example, how many nurses are needed to staff a delivery room that on average has 12 deliveries per day.
Morphological and molecular evidence for a new species of the genus Raphidascaris (Nematoda: Anisakidae) from marine fishes from the South China Sea
A new anisakid nematode, Raphidascaris (Ichthyascaris) longispicula sp. nov., is described from the intestine and stomach of the marine fish Uroconger lepturus (Richardson) (Anguilliformes: Congridae) from the South China Sea (Guangdong and Hainan Province, respectively). The new species differs from all congeners in the subgenus Ichthyascaris by the short ventricular appendix (0.36–0.49 mm long), the number and arrangement of caudal papillae (25–28 pairs of preanal, 1–2 pairs of paranal, and 6–8 pairs of postanal), and the very long spicules (1.13–1.32 mm long, representing 9.34–10.3% of body length). The sequences of the internal transcribed spacer of ribosomal DNA of R. (I.) longispicula sp. nov. are analyzed and compared with the closely related nematode sequences. Molecular analyses seem to support the validity of this new nematode species based on morphological observation.