Search

Grading students’ practice in the UK is a mandatory requirement of midwifery programmes regulated by the Nursing and Midwifery Council. This thesis explores how grading affects midwifery students, mentors and lecturers’ relationships, identity and authority. Individual and group interviews with fifty-one students, fifteen mentors and five lecturers, recruited from three local NHS Hospital Trusts and a university provided a diversity of views and experiences. This was complemented with documentary data from student practice grades, practice assessment documents and action plans from underperforming students. The analytical framework for this case study draws on Basil Bernstein's pedagogic codes using the concepts of classification and framing. This enabled an exploration of what counted as valid practice knowledge, teaching and learning in clinical practice and the evaluation of learning. Differences between students, with respect to their orientation to midwifery knowledge, types of practice knowledge and relationships between the hospital and community mentors were identified. Despite these, students were consistently awarded high practice grades. The environment seemed to affect the structural and interactional practices between students and mentors and, according to Bernstein’s theory, should have affected the practice grade. However, there was limited stratification of grades. Therefore, the grades have been interpreted as competence rather than performance of midwifery and symbolise acceptance into the profession. Reasons for this were offered. This study provides a unique insight into grading students’ practice, resulting in recommendations such as the separation of the role of mentor from assessor as well as a call for greater assessment of communication skills and evidence to inform midwifery practice. New models of teaching and assessment in clinical practice may enable a change of pedagogic code. Understanding the complexity of the practice area and the types of discourses it produces is necessary to enable all students equal access to midwifery specific knowledge.

During the last decade, Campylobacter jejuni has become recognised as one of the most common causes of human bacterial gastroenteritis in both the UK and the developing world, with over 46,000 cases of Campylobacter infection reported in England and Wales during 2002 alone. The actual number of cases is estimated to be nearer 354,000, and in addition, infection with C. jejuni has been linked to more severe conditions such as Guillain-Barré syndrome, reactive arthritis, and inflammatory bowel disease. However, despite nearly 30 years of research, the pathogenic mechanisms used to initiate disease have not been fully documented, and although it is accepted that C. jejuni produces a number of toxins, the current understanding is poorly defined and often contradictory. The aim of this research was to investigate and characterise these toxin(s), and to study potential toxins produced by the related pathogen Arcobacter butzleri, a recognised veterinary pathogen that recent research indicates may also be an important human pathogen. Cytotoxic effects were detected when cell free extracts of C. jejuni were applied to cultured cells in vitro, and it is suggested that most of this cytotoxicity was a result of LPS activity, either acting on its own, or complexed with the major outer membrane protein (MOMP). In addition, both C. jejuni and A. butzleri produced at least one haemolysin that was able to lyse equine erythrocytes in vitro. Characterisation of this activity has shown that the majority of the haemolysis was cell-associated, calcium dependent, partially destroyed by heat, and not regulated by iron. It was proposed that this was due to the activity of phospholipase A (PldA). A phospholipase A mutant was constructed from C. jejuni NCTC 11168 using inverse PCR mutagenesis. The mutant showed a markedly reduced haemolytic activity when tested in vitro, although not all of the activity was inhibited. It was demonstrated that PldA was responsible for the majority of the haemolysis detected, and the pldA gene was found to be highly conserved amongst a range of C. jejuni strains. It is likely that PldA is not the sole haemolytic factor in C. jejuni, and the remaining haemolytic activity may be due to a calcium independent, pore-forming toxin.

Evidence has shown that changes in land-use can affect the potential of the soil to act as a methane sink. The Lakenheath site consists of drained fenland peat, which is being re-converted to wetland. At the time of this study the site consisted of four land-use types, an intensively cultivated plot, unmanaged grassland, woodland, and wetland. Peat cores were taken from the four plots and compared for their ability to act as a methane sink. CH4 uptake was measured throughout the depth profiles using gas chromatography. Clear differences in methane oxidation rates were recorded with depth and land-use. The woodland soil showed the highest capacity for atmospheric methane oxidation, and the wetland soil was only profile that had a distinct peak of methane oxidation activity (just above the water table). Despite the change in land-use, all four soils had the capacity to oxidise both high and low concentrations of methane and so acted as a methane sink. The only exception to this was the wetland soil after persistent rainfall. The uppermost layers were water saturated and all soil sections failed to oxidise methane. Methanotroph diversity in the four soils was compared using molecular biological and enrichment techniques. Total DNA was extracted from depth profiles of the four soils and PCR amplified with 16S rRNA methanotroph group-specific primers and primers specific to subunits of the pMMO and AMO (pmoA and amoA), sMMO (mmoX) and MDH (methanol dehydrogenase, mxaF). In addition, DNA was extracted from the top 5 cm of the cultivated (drained) and flooded soil and PCR amplified with primers specific to subunits of the pMMO and AMO. These PCR products were cloned and gene libraries constructed for each soil. No significant differences were observed in retrieved methanotroph sequences from these two soils, suggesting that the methanotroph population had not altered after flooding. The sequences obtained in the molecular study were predominantly amoA sequences from nitrifiers and pmoA sequences from type II methanotrophs. No type I pmoA sequences were retrieved. Type I methanotrophs, however, were isolated directly from the peat soil in the enrichment study.