The dynamics of Themeda Triandra tillers in relation to burning in the natal Drakensberg

Abstract

Marked tillers of Themeda triandra were sampled regularly over a two year period in Highland Sourveld burnt annually in winter, biennially in spring and after a single summer and early winter burning treatment. Parameters recorded were height of shoot apex, tiller mass, number of new lateral tillers and time of flowering. Monitoring of marked tillers before and after each burn enabled the life history of populations of tillers to be followed.

There were no significant differences in survivorship between tillers in the annual winter and biennial spring burn treatments but winter burning stimulated the development of a greater number of daughters per parent. Both populations exhibited a constant death rate over the two year period. Only 8% of the marked T. triandra tillers survived the single summer burning treatment.     

Characteristics of mature oocytes from four species of marine teleosts

The morphology and histology of the digestive tract of the branchiuran crustacean, Chonopeltis australis Box shall, 1976 are described from serial sections. The foregut is differentiated into a preoral cavity, containing the mandibles and tongue, an ascending oesophagus, with an H-shaped lumen invested with longitudinal, circular and dilator muscles, a horizontal oesophagus with a star-shaped lumen and lacking longitudinal and dilator muscles, and an oesophageal funnel consisting of inner and recurrent walls. The midgut is differentiated into anterior and posterior chambers, separated by an S-shaped muscular tube. The arborescent midgut glands open laterally into the anterior part of the anterior midgut. Columnar epithelial cells line the anterior midgut whereas tall, papilliform cells are present in the epithelium of the posterior midgut. The transition from posterior midgut to hindgut is marked by the presence of very tall epithelial cells. The terminology describing the various parts of the digestive tract of branchiurans is discussed.     

The prevalence of Proctoeces (Trematoda: Fellodistomidae) metacercarial infections in the brown mussel Perna perna (Bivalvia: Mytilidae) around the southern African coast

Unencysted trematode metacercariae of the genus Proctoeces were found embedded in the mantle tissue and visceral mass of the intertidal mussel Pema pema. Data on the prevalence and intensity of infection in southern African populations of Pema are presented. Results from a geographic survey indicated that Proctoeces infections were more prevalent in the region Port Elizabeth to Isilaka. At the majority of sites both prevalence and intensity of infection increased in conjunction with host size. Detailed studies of mussels from Dwesa failed to show seasonal changes in metacercarial infection. A strong relationship, however, was found between sex of host and parasitic infection, with female mussels harbouring the most metacercariae. The most heavily infected mussels examined came, ironically, from two nature reserves situated on a stretch of coastline where otherwise unprotected mussel stocks are subjected to intense exploitation by man. The possible pathogenic effects of Proctoeces on such highly stressed mussel populations clearly merits further attention.     

Aspects of the biology of three benthic-feeding teleosts from King’s Beach,Algoa Bay

The lengths, abundance patterns and feeding habits of three species of benthic-feeding teleosts, Lithognathus mormyrus, Lithognathus lithognathus and Umbrina capensis from King’s Beach, Algoa Bay are presented. Multiple regression analysis was used to elucidate the influence of the physical environment on the abundance of L. mormyrus. The feeding habits of these species were analysed on a quantitative basis by means of gravimetry and the frequency of occurrence of prey items.     

Observations on the reproductive cycles of Cellana capensis (Gmelin, 1791) and Patella concolor Krauss, 1848 (Gastropoda: Prosobranchia: Patellidae)

The reproductive periodicities of the patellid limpets Cellana capensis and Patella concolor were determined from changes in macro-and microscopic appearance of the gonads over a 14-month period. Both species appear to have protracted breeding periods with several peaks in spawning activity. Problems encountered with the application of standard sampling and analytical methods to species with such cycles are discussed.     

Recovery of live immature cyathostome larvae from the faeces of horses by Baermann technique

It was demonstrated in the present study that a simple Baermann technique using disposable materials, was successful in detecting living, motile cyathostome larvae in the faeces of horses.     

New technology imperatives in medical education

A great deal of effort has been expended on trying to determine whether traditional instruction, online learning, or some combination of the two is of greater educational effectiveness.1, 2 This may be the wrong question. Rather than determining whether one delivery mechanism is superior to another, it is more important to choose the best method(s) of delivery to achieve specific educational objectives, taking into consideration the different learning styles and circumstances of the target audience. Although appropriate use of technology offers potential for improved learning, there are other compelling reasons to use technology in medical education, such as reaching a different audience or accessing unique expertise that would otherwise be unavailable. This article explores the ramifications of three important drivers of technology adoption for medical education: (1) public access to medical knowledge on the Internet; (2) change in what constitutes medical knowledge; and (3) the impending shortage of educators. Some approaches are proposed, including veterinary examples, to the challenges presented by these changes.     

Progress in the capture, manipulation, and delivery of medical media and its impact on education, clinical care, and research

In this article, advances in the application of medical media to education, clinical care, and research are explored and illustrated with examples, and their future potential is discussed. Impact is framed in terms of the Sloan Consortium's five pillars of quality education: access; student and faculty satisfaction; learning effectiveness; and cost effectiveness. (Hiltz SR, Zhang Y, Turoff M. Studies of effectiveness of learning networks. In Bourne J, Moore J, ed. Elements of Quality Online Education. Needham, MA: Sloan-Consortium, 2002:15-45). The alternatives for converting analog media (text, photos, graphics, sound, video, animations, radiographs) to digital media and direct digital capture are covered, as are options for storing, manipulating, retrieving, and sharing digital collections. Diagnostic imaging is given particular attention, clarifying the difference between computerized radiography and digital radiography and explaining the accepted standard (DICOM) and the advantages of Web PACS. Some novel research applications of medical media are presented.     

Attitudes of veterinary medical students and medical students toward collaborative learning: an experiment

This study measured the attitudes of 55 medical students and 30 veterinary medical students as they participated in an experiment of collaborative teaching and learning about basic surgical skills. Two parallel forms of an attitude questionnaire were developed, with three subscales: confidence in one's own surgical skill; collaboration with the other type of student; and inter-professional collaboration in general. These attitude scales were administered before and after an experiment involving the veterinary medical students teaching the medical students incision and exploratory laparoscopy in a laboratory setting using live rabbits. After the experiment, measures of the medical students' attitudes had increased significantly on all three subscales. Measures of the veterinary students' attitudes increased significantly on two subscales but declined on the subscale of inter-professional collaboration.