Search

John Lund's life and career were rich in the unexpected. Although his early education was deficient in science, he ultimately altered the character and practice of his adopted subject, especially in Britain. Different traditions in systematic and physiological ecology were absorbed from successive contacts with two leading authorities, and combined to good effect in his main work on the ecology of freshwater planktonic algae. Insistence on factual specifics and accuracy, and avoidance of over-generalization, were encouraged by a long wartime occupation in forensic science with consequent legal evidence. He was forthright in his opinions; he benefited and inspired a succession of younger scientists and assistants. Cooperative work with senior scientists led to some ground-breaking innovations, including that with his wife, Hilda, involving the extension of her mycological work to epidemics of chytrid parasitism in planktonic population dynamics. In retirement he devoted much time to acquiring uncommon fluency in the Russian language, which was put to good effect in private and official matters.

The majority of work done with Elektron 21 has been for sand cast applications. Investment casting, is a means of reducing wall thickness (and hence weight) of complex components. This process is generally restricted to small components for Magnesium due to metal mould reaction. Use of low reactivity Elektron 21 gave successful results during investment casting (using plaster and shell moulds). Using improved processing technology, it has been shown that large components can be made successfully in this alloy with out reaction. This opens new opportunities for further weight reduction in weight sensitive applications.

Agriculture in Northern Ireland depends on grass-based production, but since 1980, expansion of output has been effectively constrained by production limits set by the European Union agricultural policy. Despite this, long-term monitoring over several decades has shown significant degradation of water quality in Lough Neagh, with persistent high biomass of blue-green algae. Similar long-term studies have revealed a marked decline in the freshwater survival of salmon in the nearby River Bush. These changes may be related and reflect the impact of farming on water quality and salmonid production. Regular sampling of the inflowing rivers to Lough Neagh has shown that continued increase in lake phosphorus concentration has been primarily due to an increase in the soluble reactive phosphorus loading from agricultural diffuse sources. Similar diffuse inputs of agriculturally derived nutrients to the River Bush, leading to increased plant growth together with the accumulation of fine sediment in salmon spawning redds, are considered to be important in the decline of freshwater survival of salmon from egg to smolt. The impact of farming practices on lakes and rivers is considered in relation to understanding of the complex and interacting factors that link land use to water quality.

Energy dispersive X-ray microanalysis (XRMA) in a scanning electron microscope (SEM) was used as a method to measure elemental silicon (Si) and phosphorus (P) in dinoflagellate cysts. Cysts were prepared by quick deep freezing and then freeze-drying, thereby avoiding the addition of preservatives. Cysts of Ceratium hirundinella collected from Lake Erken, Sweden and Esthwaite Water, UK, and Ceratium furcoides collected from Esthwaite Water, were analysed and compared. The hypothesis that cysts are able to assimilate P during dormancy was tested in the laboratory by incubating newly collected cysts of C. hirundinella in medium with and without phosphate. The analyses showed that there was no difference in P content between C. hirundinella and C. furcoides, suggesting that P content reflects differences in physiological status rather than species. C. hirundinella had a significantly higher Si content than C. furcoides, which agrees with earlier studies. Comparison of cysts of C. hirundinella from different years – 1995 (stored for 1 year), 1996 and 1997 – showed that the P content in cysts from 1995 was higher than that in cysts from the following 2 years, which indicates either that P was higher during encystment in 1995 or that cysts accumulated P during dormancy. The P uptake experiment showed a very slightly, but significantly, higher, P content in cysts incubated in P-rich medium.

The clinical and radiological state of the hips of a group of children with cerebral palsy treated without operation is compared with that in a group treated by operation to correct adduction and flexion deformity and to obtain balanced action in the hip muscles. In the first group, 11 per cent of hips were dislocated, 28 per cent subluxated, 46 per cent dysplastic and 15 per cent normal. In the second group no hip was dislocated, 13 per cent were subluxated, 35 per cent dysplastic and 52 per cent normal. Surgical intervention is indicated clinically for a range of abduction diminishing to less than 45 degrees and–on radiological criteria–for early dysplastic changes, especially a break in Shenton's line, irrespective of the patient's age, severity of involvement or neurological maturity. Prevention of subluxation or dislocation improves function and diminishes the liability to develop a painful hip in adolescence or early adult life.

Changes in the annual population densities of Ceratium spp. in three adjacent English lakes, Windermere, Esthwaite Water and Blelham Tarn, are summarised over the 41 year period 1945–1985. In these lakes the genus is represented by two species, C. hirundinella (O.F. Müll) Bergh. and C. furcoides (Levander) Langhans. Although the species have not been distinguished over the entire study period, they have been shown by examination of preserved samples to undergo marked changes of relative abundance in Esthwaite Water. Both long-term (years) and short-term (within year) changes of populations densities of Ceratium spp. are considered in relation to possible controlling factors including recruitment of the inoculum, nutrient enrichment, physical stability and fungal epidemics. Given an early inoculum, the relative success of Ceratium populations in these lakes decreases along gradients of increasing mixed depths, increasing turbulence and decreasing retention times. The potential for good population growth is regulated by energy inputs, lake bathymetry and hydraulic characteristics. The realisation of such growth is governed by nutrient availability and microbial grazing. The significance of large between-year differences of populations of Ceratium spp. for general lake metabolism is illustrated for summers of contrasting production in Esthwaite Water.

A simple separation technique using polycarbonate membrane filters for purifying microalgae is described.

Large populations of the dinoflagellate Ceratium hirundinella occur regularly in a small productive lake and their decline during September and October is normally associated with mass encystment. Evidence for the major role of benthic cysts in providing the inoculum for subsequent growth is given from morphological and quantitative studies over two contrasting years of cyst production, 1980 and 1981.For both years there were two distinct phases of population increase in the plankton. Low winter densities were followed by rapid rates of increase during February and March at the same time as empty cysts appeared in the sediment. These changes occurred when water temperatures rose from approx. 3 to 5°C. After near-stationary periods in April and May 1980 and April to June 1981 there followed phases of exponential growth but at appreciably slower rates of population increase than during recruitment from excystment. That excystment was the major contributor to the rapid vernal increase of planktonic cells is supported by the observation in the plankton of high percentages of preceratium (recently excysted) cells and young vegetative cells with carbohydrate in their posterior halves. Moreover, a calculation of growth rate in situ, from the phasing of cell division when water temperatures were approx. 8°C, indicated that vegetative growth was very slow relative to the earlier observed rate of increase. Growth rates in culture at temperatures below 10°C were also very slow.Instead of the usual encystment in 1980 there was an early mass mortality of cells. This failure to form cysts did not prevent recruitment from benthic cysts in 1981 due to the large reservoir of viable cysts in the sediment from earlier years.

The diurnal vertical migration (DVM) behaviour of three species of cryptophytes of differing size (Rhodomonas minuta var. nannoplanctica and two species of Cryptomonas) was examined in 4 m tall laboratory columns in relation to gradients of light, temperature and nutrients. Differences were found in the DVM behaviour of the three species in relation to these environmental variables. Both species of Cryptomonas were able to cross steep thermal gradients whereas Rhodomonas did not. All three species avoided high levels of irradiance, especially when the cells were phosphorus-depleted. The large species of Cryptomonas made use of vertically separated resources of light and phosphorus by migrating from the illuminated, but phosphorus-depleted, upper layer during daytime to the phosphorus-rich hypolimnion at night. The smaller species of Cryptomonas had a reverse pattern of DVM swimming upwards during darkness, indicating a strong negative geotaxis. Moreover, downward migration of this smaller Cryptomonas ceased abruptly at the thermocline giving rise to well developed mid-water maxima in contrast to the larger species. The migration speeds of the Cryptomonas species were up to 0·7 m h-1 and cells were able to move quickly in response to environmental changes in the water column. The results demonstrate the importance of both the physiological state of the cells and the external physical and chemical conditions, particularly irradiance, as factors regulating the DVM behaviour of cryptophytes.

Pax6 plays a key role in visual system development throughout the metazoa and the function of Pax6 is evolutionarily conserved. However, the regulation of Pax6 expression during eye development is largely unknown. We have identified two physically distinct promoters in mouse Pax6, P0 and P1, that direct differential Pax6 expression in the developing eye. P0-initiated transcripts predominate in lens placode and corneal and conjunctival epithelia, whereas P1-initiated transcripts are expressed in lens placode, optic vesicle and CNS, and only weakly in corneal and conjunctival epithelia. To further investigate their tissue-specific expression, a series of constructs for each promoter were examined in transgenic mice. We identified three different regulatory regions which direct distinct domains of Pax6 expression in the eye. A regulatory element upstream of the Pax6 P0 promoter is required for expression in a subpopulation of retinal progenitors and in the developing pancreas, while a second regulatory element upstream of the Pax6 P1 promoter is sufficient to direct expression in a subset of post-mitotic, non-terminally differentiated photoreceptors. A third element in Pax6 intron 4, when combined with either the P0 or P1 promoter, accurately directs expression in amacrine cells, ciliary body and iris. These results indicate that the complex expression pattern of Pax6 is differentially regulated by two promoters acting in combination with multiple cis-acting elements. We have also tested whether the regulatory mechanisms that direct Pax6 ocular expression are conserved between mice and flies. Remarkably, when inserted upstream of either the mouse Pax6 P1 or P0 promoter, an eye-enhancer region of the Drosophila eyeless gene, a Pax6 homolog, directs eye- and CNS-specific expression in transgenic mice that accurately reproduces features of endogenous Pax6 expression. These results suggest that in addition to conservation of Pax6 function, the upstream regulation of Pax6 has also been conserved during evolution.

Energy dispersive X-ray microanalysis (XRMA) in a scanning electron microscope (SEM) was used as a method to measure elemental silicon (Si) and phosphorus (P) in dinoflagellate cysts. Cysts were prepared by quick deep freezing and then freeze-drying, thereby avoiding the addition of preservatives. Cysts of Ceratium hirundinella collected from Lake Erken, Sweden and Esthwaite Water, UK, and Ceratium furcoides collected from Esthwaite Water, were analysed and compared. The hypothesis that cysts are able to assimilate P during dormancy was tested in the laboratory by incubating newly collected cysts of C. hirundinella in medium with and without phosphate. The analyses showed that there was no difference in P content between C. hirundinella and C. furcoides, suggesting that P content reflects differences in physiological status rather than species. C. hirundinella had a significantly higher Si content than C. furcoides, which agrees with earlier studies. Comparison of cysts of C. hirundinella from different years - 1995 (stored for 1 year), 1996 and 1997 - showed that the P content in cysts from 1995 was higher than that in cysts from the following 2 years, which indicates either that P was higher during encystment in 1995 or that cysts accumulated P during dormancy. The P uptake experiment showed a very slightly, but significantly, higher, P content in cysts incubated in P-rich medium.

Measurements of ferrous iron, in water containing both ferrous and ferric iron, by the 2,2′ bipyridyl method and polarography are compared. When samples are protected from strong solar irradiation and contact with air, and measurements are made quickly, the 2,2′ bipyridyl method can distinguish the oxidation states of iron in anoxic waters containing ferrous iron.

Eight methods for estimating algal biomass were compared, using the colonial diatom Asterionella formosa as a test organism. They were based on (i) cell counts by visual microscopy and electronic means, (ii) optical properties in vivo of scattering, attenuance and fluorescence and (iii) chemical estimations, on filtered cell-aliquots, of reducing capacity (C-equivalent) and solvent-extracted chlorophyll a. The main criteria were the parameters of precision, sensitivity, limit of detection plus time taken and sample quantity required.Most methods yielded an acceptable precision over wide ranges of algal concentrations although for visual counting and nephelometry the coefficient of variation typically exceeded 10%. The estimations in vivo were the most rapid, but were unsuitable for very low biomass concentrations. The chemical methods and (on undiluted samples) electronic counting generally required the larger quantities of sample - with the notable exception of extract fluorometry. The chemical methods were relatively slow but they allowed batches of samples to be processed together and gave more generalized measures of algal biomass (e.g. C-equivalent, chlorophyll a). Visual cell counts, although relatively slow and fatiguing, were unsurpassed for low limit of detection, economy of sample, and assessment of cell condition.

Growth in relation to CO2-depletion and CO2-enrichment was investigated for the freshwater diatoms Asterionella formosa and Fragilaria crotonensis in batch cultures. Algal concentration and pH were measured during growth cycles, and inorganic carbon quantities determined by potentiometric Gran titrations and from pH-alkalinity relationships. After the primary growth with CO2-depletion and pH increase, successive CO2-enrichments induced further such cycles and produced a final three- to fivefold increase in algal biomass over that of unenriched controls. The extent of CO2-depletion, and pH rise, was greater in later cycles, indicative of some cellular adaptation. Values of pH reached 9·7 for Asterionella and 9·9 for Fragilaria. The lowest residual quantities of free CO2 were 0·1 and 0·03 μmol 1-1 for Asterionella and Fragilaria respectively, which were less than 0·05% of the corresponding residual quantities of total CO2. The primary limitation of CO2-uptake and growth was probably related to the concentration of free CO2, given the relative excess of other major nutrients (N, P, Si) in he media used. Limited of CO2-uptake could be restored without CO2 additions if the CO2 present was redistributed between its several forms (increasing free CO2) by the addition of strong acid, although growth was still restricted.Limitation of CO2-uptake, either by CO2-depletion or the addition of an inhibitor of photo-synthesis (DCMU), increased the sinking rate of Asterionella cells from 0·3 to 1 m day-1. The possible ecological implications of CO2-pH-growth and CO2-pH-buoyancy relationships are discussed, which may contribute to the frequent paucity of diatoms during summer in manv productive lakes.

Abstract: The seasonal and depth distributions of the concentrations of total and soluble iron in a seasonally anoxic lake basin are described for two years. Transport of iron is related to hydrodynamics and fluxes of iron both within and to and from the lake are calculated. The results enabled the construction of a schematic model for iron movement; it is critically dependent upon the many rate processes involved.

A method is described for the measurement of the carbon and nitrogen content of particulate material in natural waters. Particulate material is separated by filtration through GF/C filters. The dried filter is encapsulated in silver foil using a purpose made press. Analysis is carried out using high temperature combustion with thermal conductivity detection of emission gasses. Analytical performance characteristics obtained with both standards and natural materials are given.

Background. Violence directed towards GPs has been recognized as a significant problem in the UK. In Australian urban general practice, no study has previously examined this topic. Objective. The objective of this study was to investigate the responses of Australian urban GPs to experiences of violence and to perceptions of risk of violence. Methods. Design: A qualitative study of data collected from two sources—focus group discussions and qualitative questionnaire responses. Focus group discussions were audiotaped and transcribed. Questionnaires offered the opportunity for respondents to make qualitative comments. The focus group transcripts and qualitative questionnaire responses were coded independently by members of the research team and subjected to thematic analysis. Setting: Three urban Divisions of General Practice in New South Wales, Australia. Subjects: Focus groups were conducted with male and female GPs comprising a range of ages, socio-economic practice catchments and practice structures. Questionnaires were distributed to all GPs in the three divisions. Results. The GPs in this study perceived themselves as being at significant risk of occupational violence. Despite responses to violence being largely ad hoc and uncoordinated, a coherent schema of GPs responses to the threat of violence is apparent in the data. This has been characterized as encompassing primary, secondary and tertiary responses, and reflects a continuum of proactive to reactive responses. Conclusion. The findings will have implications for further research and for policy in the area.