Background and Objectives: The aim of this study was to evaluate the prognosis after treatment for femoral neck fracture, to assess the impact of delay to surgery, and to devise a clinical prediction rule and score. Methods: A prospective observational study was conducted in which 1780 patients treated surgically in two teaching hospitals between 1 November 1997 and 31 October 1999 were followed over 12 months. Logistic regression was used to distinguish the effects of predictor variables on survival. Using a probit transformation of the predicted posterior probabilities of death, a prognostic score was devised with scores constrained so that a nominal score of approximately 90 represented a 50:50 chance of survival over 12 months. Results: Mortality was 30.1% in men and 19.5% in women. Increasing age, male gender, longer pre-operative delay, a higher American Society of Anesthesiology score, a lower Mental Test score, and a lower activities of daily living (Barthel) score were associated with increased risks of death. Of those waiting between 1 and 5 days for surgery, approximately 8 medium-risk and 17 high-risk patients (with prognostic scores of 90 and 120, respectively) would have to have their delay reduced to Ͻ24 hours to yield one additional survivor. Conclusion: The application of prediction rules must be guided by ethical, social, and scientific concerns.

In this review we provide a detailed description of Darwin's prediction of the coevolution of a long-spurred orchid, Angraecum sesquipedale, and a long-tongued moth, his correspondence on the subject, the history of the moth and the subsequent literature. On seeing the long spur of A. sesquipedale, Darwin predicted that its pollinator would be a moth with a long proboscis. For more than a century following Darwin's prediction this was assumed to be the case. The pollinator was taken to be Xanthopan morganii praedicta, despite the fact that it had not been observed to visit A. sesquipedale flowers. Direct observations, infra-red cinematography and photographs published between 1993 and 1997 and a video made in 2004, all of which show X. morganii praedicta visiting A. sesquipedale flowers and removing pollinia, proved that Darwin's prediction was accurate. Recent research suggests that selection pressure exerted by predators on the pollinators, resulted in the evolution of extreme tongue lengths and a special hovering flight.

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The relatively rapid Desreux technique for polymer fractionation has been modified and applied to both linear and highly branched polyethylenes. The polymer is precipitated from p‐xylene solution onto a sand column by cooling from 127° to room temperature. After removal of solvent, the column temperature is again raised to 127° and fractions are eluted, using p‐xylene‐ethylene glycol monoethyl ether mixtures of increasing solvent power. Approximately 15 fractions are obtained and polymer recovery is essentially quantitative. The reproducibility of the integral distribution curves is within ±2% for a cumulative weight‐% of 85 or higher. In certain cases difficulty has been encountered in resolving the less soluble portion of the sample. The selective nature of the system is indicated by the fact that the reduced specific viscosities of the highest and lowest molecular weight fractions are generally in the ratio of 50 or higher.