Mahogany as a genetic resource

The development of a strategy for the sustainable management and conservation of mahogany is an urgent priority. Such a strategy should be based upon clear information about the extent of genetic differentiation within and between populations, and on an understanding of the processes maintaining this variation. At present, such information is very limited for mahogany. Preliminary data are presented from two genetic tests of Swietenia macrophylla King (Meliaceae), indicating significant differences between provenances and half-sib progenies in both growth and form characteristics. In addition, the use of molecular markers for the characterization of genetic resources of mahogany is discussed. On the basis of the results available, the impacts of deforestation and logging activities on genetic resources are evaluated. Although both deforestation and selective logging may deplete genetic resources, no quantitative information on the extent of such depletion in mahogany is currently available. Additional research is therefore required before clear guidelines can be provided for the sustainable management of mahogany.     

Motion Analysis in the Assessment of Surgical Skill

Abstract

Manual skill is now widely recognised as an important aspect of training in surgery. However, measurement of the skill of a surgeon has in the past been rather subjective in nature, relying on the judgement of experts in the analysis of videotapes. Objective measurements can be made by analysing the velocities of a surgeon's hands during a procedure. In particular, we have found that the number of movements made during a typical procedure will decrease as the surgeon's skill increases. Velocity traces display purposeful movements corrupted by uncorrelated noise from sources such as hand tremor and measurement artefacts. However, we have found that it is possible to filter the noise effectively. Furthermore, we have shown that the skill measurement obtained by counting movements is highly robust to over or under filtering.     

Three new species of Elassoneuria (Ephemeroptera: Oligoneuriidae) from tropical Africa

Three new species of Elassoneuria are described, E.disneyi from the Cameroons, and E.grandis and E.kidahi from Tanzania. The taxonomy of the nymphs is discussed, and E.congolana Navas is redescribed.