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Innovation in science curriculum a Sierra Leone case study
(The University of Waikato, 1991) Baimba, Andrew Augustine; Katterns, Robert; Kirkwood, Valda
Recent studies in philosophy of science and learning theory have identified elements that add a socio-cultural dimension to science curriculum debates. These suggest that effective science education must take account of the culture in which it is being offered. Accordingly, the present study conducted in Sierra Leone investigated the viability of a junior secondary school science curriculum that took into account the childrens’ traditional culture. The investigation involved two parts. The first was a case study examining the present state of junior secondary school science education in Sierra Leone using data derived from a survey which canvassed teachers’ perceptions of science and students’ attitudes towards it. The second involved action research in which a group of teachers worked with the researcher to develop, trial and self-evaluate teaching packages in physics based on the Science for All curriculum, an approach that is based on the constructivist view of learning. The main intent of the study was to investigate first, the effects on their professional development of the teachers’ interaction with the new curriculum and, secondly, their students’ attitudes towards science. The research instruments employed were interviews, classroom observation and an attitudes to science questionnaire. The initial case study showed that the present junior secondary school science programme in Sierra Leone was characterised by: 1. Unfavourable students’ attitudes towards science. 2. Low numbers of General Science teachers with subject expertise in Physics and Chemistry. 3. A lack of sense of direction in determining goals and objectives. 4. Inadequate pre-service teacher education preparation. 5. Limited teacher understanding of recent changes in the thinking about the nature of science and the ways of acquiring scientific knowledge. Successful use of the new curriculum to overcome these problems was hindered by the teachers’ scepticism about the new curriculum, a gap between their theoretical and practical understanding of the change process, and insufficient skills to implement the revised curriculum. Techniques employed to alleviate these problems during the action research suggested that teachers’ commitment could be increased by clarifying conceptually the need for innovation. The researcher’s support and encouragement throughout the curriculum trials significantly helped teachers to give practical expression to their theoretical understanding of the change process. Action research with the new curriculum brought about major changes in the teachers’ approach to teaching. They showed evidence of appreciating recent constructivist views about the nature of science and the ways of acquiring scientific knowledge. The development of their own effective and more relevant curriculum also enhanced the teachers’ self esteem. But even though the teachers with their new found confidence believed otherwise, post-test results showed that students’ attitudes to science were not enhanced by their interaction with the new curriculum. The results of the study suggest policy implications for Sierra Leone. The educational system and science curricula need to dwell far less on western-type syllabuses and public examinations and develop instead science curricula that bridge school science and students’ everyday application of scientific ideas in their traditional settings. Nevertheless, much research is required to identify cultural aspects that can be linked to the school science curriculum. Concomitantly, there is need to research the viability of both preservice and inservice teacher education programmes that can bring about the bridging referred to. The present action research study is a beginning.
The influence of subsoiling on soil physical properties and pasture production
(The University of Waikato, 1992) Chapman, Richard; Allbrook, R.F.
In many areas of New Zealand, soils under pasture have become compacted by a combination of livestock trampling, use of heavy machinery and natural processes, or in the case of sports fields, heavy use at high moisture levels. These processes create soil horizons that have a high resistance to a penetrometer, often a high bulk density and hence a lowered porosity. These horizons reduce hydraulic conductivity, change soil moisture characteristics and restrict root elongation and consequent pasture yield. An arable type subsoiler was re-designed for pasture use and its effects on five soils in the Hamilton Basin were investigated. Soil disturbance was assessed for differing operational depths, tip sizes, operating modes and soil moistures. Soil physical characteristics such as bulk density, soil strength, pore space, water tension and infiltration were measured at intervals after subsoiling. Root growth and yield response of pasture were quantified. Subsoiling in the vibrating mode under relatively dry soil conditions increased soil disturbance by 30% in comparison with non-vibrating; wide tips in comparison with narrow tips increased disturbance by up to 100%. Results indicated that the effectiveness of subsoiling at a standard speed, is a function of operational depth, tip size, pitch angle, soil type and soil moisture. Generally subsoiling below 45 cm depth resulted in a reduction in soil disturbance and was less effective under wet soil conditions at deeper than 35cm Increased water stress in and around the subsoiled slot resulted from summer subsoiling. The addition of press rollers reduced evaporation and reduced ground heave by 25%. Measurements of ground heave following subsoiling using a purpose built heaveometer enabled comparisons between different soils to be made. The more clayey Hamilton and Whatawhata soils showed greatest heave. Subsoiling reduced bulk density by up to 30% within 10 cm distance of the subsoil slot; significantly reduced levels were sustained at this distance in the more clayey soils for up to two years. The effect on bulk density decreased with distance from the subsoil slot. Bulk density estimations in situ showed greater changes in response to subsoiling than laboratory measurements. Penetrometer measurements provided additional crucial information on the extent of soil disturbance and its sustainability with time. Repeated measurements defined “envelopes” of soil disturbance emanating from the subsoiled shank and tip. The lowest soil penetration resistance was found down the slot, where strengths were commonly reduced from 4 MPa to 1 MPa. The depth of influence was shallower further from the slot following a 45 - 50° angle up from the subsoiler tip to the surface. In the more clayey soils a discrete zone of higher strength soil was occasionally identified contiguous to the lateral extremeties of disturbance. Subsoiling shattered large aggregates thus creating a larger volume of soil. Soil mixing was limited to a relatively small area around the subsoiler shank and tip where 17 - 19% of A and B horizon aggregates interchanged. Consequently a redistribution of soil texture and organic matter occurred within soil profiles. Pores >9.76 μm increased from 20 to 35% in A horizons and from 3 to 35% in B horizons. Increased porosity to the full depth of soil disturbance resulted in rapid movement of excess summer rain, and in the case of the poorly drained Whatawhata soil drier soil conditions prevailed in winter. Measurements of root elongation, together with SEM analysis showed that grass roots had difficulty penetrating high bulk density (1.35 - 1.50 Mg m⁻³), high strength (>5.00 MPa) soil layers. In these cases subsoiling facilitated increases of up to 20% in root length and a consequent increase in pasture yield of up to 17.7%. The more clayey soils derived greater benefits from subsoiling than sandy soils, both in the extent of soil disturbance and duration of reduced bulk density and soil strength. In the case of an artificially constructed soil, near surface compaction was ameliorated with a consequent improvement in turf. Provided that subsoiling was carried out under optimum conditions, a positive response in pasture yield could be expected, even where soil physical properties were not limiting. Re-compaction rates following subsoiling are a function of pasture management and soil physical properties, but provided subsoiling is carried out with optimal soil disturbance, then a subsoiling frequency of two years for sandy soils and three years for more silty and clayey soils is recommended.
Characterisation and fate of bleached kraft mill effluents from a New Zealand pulp and paper mill
(The University of Waikato, 1990) Stuthridge, Trevor Raymond; Langdon, Alan G.; Wilkins, Alistair L.
The wastewater discharges from the Kinleith mill, a New Zealand integrated bleached kraft pulp and paper mill, were characterised and their treatability assessed. The chlorination stage bleaching effluents from the mill’s second bleach plant [(C30D70)EoDED sequence] contained a group of novel chlorinated compounds. Fourteen compounds were isolated from the effluents by a combination of liquid-liquid extraction, column chromatography, and preparative gas chromatography. Mass spectral and ¹H and ¹³C NMR data showed these compounds to be hydroxylated and/or chlorinated derivatives of Pinus radiata monoterpenes. The major compounds were a dichlorobornane and four dichloro-p-menthane-1,8-diols. The chlorinated monoterpenes were detected in total concentrations of 1400-12 300 μg L⁻¹ [70-600 g air-dried tonne⁻¹ (ADT) bleached pulp] and they were the major class of low molecular weight extractable organic compounds present in the chlorination stage effluent. The principal factor determining their formation appeared to be the high concentration of monoterpenes remaining in the Pinus radiata brown stock produced in the mill’s continuous digester. The biological activity of the chlorinated monoterpenes was assessed. The chlorinated monoterpene alcohols were base labile with a 94% decrease in concentration being observed within 4 hours at pH 12. The chlorinated monoterpene hydrocarbons exhibited a lesser degree of alkaline lability. Acute toxicity tests on the monoterpene alcohols gave EC₅₀ concentrations of 60-200 mg L⁻¹, indicating that these compounds display relatively little toxicity. The monoterpene alcohols were also tested for mutagenicity and genotoxicity. Some of these compounds produced mutagenic and genotoxic responses. An assessment of the bioaccumulation potential of the chlorinated monoterpene alcohols showed them to have log Kₒw values of 1.37-2.1. Therefore, these compounds are unlikely to exhibit a significant bioaccumulation propensity. Treatment of the chlorination stage effluents in an aerated lagoon treatment system removed 80% of the chlorinated monoterpene alcohols but only a small fraction of the monoterpene hydrocarbons. It was concluded that these compounds were unlikely to produce significant environmental effects in the recipient. The mill has two secondary treatment systems. The relative effectiveness of each of these was assessed. The two systems operate in different configurations. Treatment system A, which receives general mill wastewaters and chlorination stage bleaching discharges utilises deep, aerated lagoons and has a 4.5 day retention time. Treatment system B, which receives alkali extraction bleaching wastewaters and foul condensates, uses a lagoon system with a retention time of 51 days. Detailed chemical analyses of the untreated and treated wastewaters were made. Mass balances were calculated for a range of physical parameters and for specific chlorinated and non-chlorinated organic constituents. Significant differences in the treatability of various constituents were found. In particular, while system A was able to reduce levels of adsorbable organic halide (AOX) by 65%, no significant reduction in AOX occurred in system B. In contrast, system B reduced levels of chloroacetic acids by 84% while system A did not achieve any statistically significant removal of these compounds. The treatability of chlorophenolic compounds also differed. System A was unable to remove chlorophenols and chloroguaiacols while system B did not reduce levels of chlorocatechols. The removal of AOX from effluents treated in system A was high compared to published data and an assessment was made of possible mechanisms for the observed AOX removal. Much of this removal took place in a short section (3.3 hr residence time) of the system’s main lagoon. The initial AOX decrease in the aqueous phase could be achieved in part by settling of AOX-containing suspended solids from the influent wastewaters. In addition, lime and bacterial solids present in the treatment system were able to adsorb AOX from the influent wastewaters. Only a small proportion of the organic chlorine removed was found in sludges. A mass balance of aqueous and solid phases indicated that over 99% of the removed AOX was mineralised.
Control of glucose and xylose utilization by Clostridium thermohydrosulfuricum Rt8.B1
(The University of Waikato, 1992) Cook, Gregory Murray; Morgan, Hugh W.; Janssen, P.H.
Five extremely thermophilic organisms representing the Eubacterial and Archaebacterial Kingdoms were studied for controlled expression of β-galactosidase, β-glucosidase and α-glucosidase synthesis. Under the culture conditions used, these organisms exhibited a high constitutive level of enzyme synthesis which was modulated in the presence of added carbohydrate. The lack of observed classical induction in these organisms could either reflect a lack of control or a less elaborate control of enzyme synthesis, which may be advantageous to these bacteria in environments low in nutrients. This absence of highly regulated control is common in thermophilic organisms and may be a reflection of the limited evolutionary divergence of thermophiles as is suggested by phylogenetic studies. Cl. thermohydrosulfuricum Rt8.B1 inhabits thermophilic environments where the natural concentrations of sugars would be expected to be quite low. The results of this study demonstrated that glucose and xylose were used simultaneously i.e. the bacterium exhibited hyperbolic growth when both glucose and xylose were supplied together at nonlimiting concentrations. Under conditions of hyperbolic growth, Cl. thermohydrosulfuricum Rt8.B1 exhibited neither catabolite repression nor inducer exclusion. Although classical control mechanisms were not seen, the utilization of glucose and xylose were tightly controlled at both low and high concentrations of single and multiple substrates. Such regulation to allow controlled hyperbolic growth is consistent with the idea of Cl. thermohydrosulfuricum Rt8.B1 being well adapted as an opportunist. The transport of glucose and xylose across the bacterial cell membrane of Cl. thermohydrosulfuricum Rt8.B1 was governed by permeases which did not catalyze concomitant substrate transport and phosphorylation, and thus was not a phosphoenolpyruvate-dependent carbohydrate: phosphotransferase system. Glucose and xylose transport was not driven by a proton motive force (ΔμH⁺) nor coupled to sodium and potassium ion gradients. An involvement of ATP in the uptake process was indicated by the reduction of glucose and xylose uptake by iodoacetate and sodium fluoride, both inhibitors of ATP synthesis. The phosphorylation of glucose was carried out by a constitutive ATP-dependent glucokinase and that of xylose by an inducible ATP-dependent xylulokinase following isomerization by xylose isomerase. These enzymes not only initiated the metabolism of glucose and xylose in Cl. thermohydrosulfuricum Rt8.B1, but also served to “capture” sugars from the cytoplasm through their phosphorylation. Since glucokinase was regulated primarily by the concentration of ATP, ADP, and AMP, both glucose phosphorylation and uptake appeared to be dependent upon the energy status of the cell. Xylulose inhibited glucokinase activity, indicating that xylose metabolism may regulate the activity of glucokinase in glucose and xylose-grown cells. Xylose utilization by Cl. thermohydrosulfuricum Rt8.B1 was mediated by two systems. Both systems were inducible and dependent on the xylose concentration used for cell growth. Cells grown on 5 mM xylose had a high-affinity, low-capacity system for xylose uptake which was saturable (low Vₘₐₓ). Cells grown on 50 mM xylose had a low-affinity, high-capacity (high Vₘₐₓ) system for xylose uptake and the kinetics were indicative of facilitated diffusion. The xylose isomerase of Cl. thermohydrosulfuricum Rt8.B1 had a high Kₘ for xylose (low-affinity) and xylulokinase had a low Kₘ for xylose (high-affinity). The Kₘ for xylulokinase was lower than the Kₜ for the high-affinity xylose permease; this indicated that the xylulokinase phosphorylating system was fully saturated at external xylose concentrations near or above the Kₜ concentration for uptake and that the affinity of xylulokinase regulated both the rate of xylose uptake and its subsequent utilization. When Cl. thermohydrosulfuricum Rt8.B1 was grown on high concentrations of xylose (low-affinity), xylulose leaked from the cell. This indicated that a futile cycle for xylose may be operative under conditions of high xylose and may explain the facilitated diffusion kinetics observed. A semi-defined minimal medium for the growth of Clostridium thermohydrosulfuricum Rt8.B1 was developed in this study. This medium was able to support the growth of several thermophilic anaerobes. Most strains studied showed morphological changes. In one instance, spores were seen in an apparently nonsporulating strain of Thermoanaerobium brockii DSM 1457 which could not be attributed to a contaminant. This observation has resulted in the species being renamed Thermoanaerobacter brockii comb. nov. and the genus Thermoanaerobium being removed due to the removal of the type strain.
The fluvial biology of Lake Taupo rainbow trout
(The University of Waikato, 1991) Rosenau, Marvin Leslie; Chapman, M. Ann; Green, John D.; Swales, Steve
The riverine biology of adfluvial-lacustrine rainbow trout (Oncorhynchus mykiss, previously Salmo gairdneri) from the Waimarino, Tokaanu, and Hinemaiaia Rivers was investigated. These three streams are important spawning and rearing habitats for rainbow trout recruiting to an economically important sport fishery in Lake Taupo, New Zealand, yet each has very different bio-physical characteristics; the Waimarino River is an unregulated stream with seasonally varying flow and temperature regimes; the Hinemaiaia River is an hydro-electric flow-controlled stream having a seasonally varying temperature regime and daily flow fluctuations; the Tokaanu River is an unregulated groundwater-fed stream with stable flows and temperatures. Nutrient concentrations and spawning and rearing habitats also vary considerably among these streams. Scales were taken from adult rainbow trout from these streams and examined; they showed both widely-spaced outer, and narrowly-spaced inner, circulus zones. While there were no among-population differences in average circulus-spacing in the outer-growth zone, there were significant among-population differences in the inner zone; these two zones are suggested to represent (common) lake and natal stream rearing, respectively. The back-calculated minimum and average lengths at migration of juveniles from stream to lake was similar for all three populations (ca. 94 mm and ca. 140 mm, respectively) but there were significant among-population differences in age at emigration. The scale patterns and stream sampling suggested that most Hinemaiaia River rainbow trout left the river within the first year of growth (64%) whilst much higher proportions of juveniles surviving to adulthood in the other two streams overwintered before emigrating in their second year (up to 70%). Scales were also taken from juvenile rainbow trout captured from the Waimarino and Tokaanu Rivers. The patterns on these scales corresponded closely with the features seen on the inner-growth zone of the adult scales. This further strengthened the assertion that the inner-growth zone on the adult scales reflects a period of juvenile natal-stream growth before the fish go to Lake Taupo. The utilization of fluvial habitat by juvenile rainbow trout, common bullies and koaro in the Waimarino River was examined using minnow trapping as a methodology. There was segregation of habitat by these three species with regards to one or more of the following variables: 1) water depth, 2) water velocity, 3) substrate size, and 4) instream cover. Except in winter when the habitat choices by fingerlings (45-93 mm fork length) and smolts (>93 mm fork length) overlapped, there was also a segregation of habitat by the various size classes of juvenile trout, including fry (<45 mm fork length). Furthermore, there were ontogenetic trends and larger juvenile trout choose habitats with faster and deeper water and having substrates with larger diameters than did the smaller size classes of fish; larger juvenile trout were also more closely associated with instream cover. Woody and herbaceous cover were generally important for all species and size classes of fish in the Waimarino River. The distributions of juvenile trout and koaro and common bullies in the Waimarino, Tokaanu and Hinemaiaia Rivers was investigated. The species composition varied considerably among seasons, study sites and rivers. More bullies were found in the downstream reaches of these streams and this appeared to be positively related to water column depths and inversely related to velocities. There was a negative relationship between the catch rates of rainbow trout juveniles and koaro. The hydro-electric dam overflow channel on the Hinemaiaia River contained exceptional numbers of koaro. I also examined the inherited variability in parr mark numbers in juvenile rainbow trout from the Tokaanu and Waimarino Rivers. Ripe male and ovulated female trout were obtained from each of the study streams and reciprocal and pure crosses were made from the pooled gametes. The resulting juveniles were reared to fingerling size in separate tanks under similar conditions. The parr marks bisecting the lateral tine on the left side of the fish were counted and there were significant differences between the two pure crosses; the reciprocal hybrid crosses were intermediate in number. This suggests that there was a genetic difference controlling parr-mark number in these fish. The parr marks of wild-caught fingerling rainbow trout from the two study populations were also counted and there were no significant differences in number between these groups but the wild caught fish had intermediate numbers of parr marks compared to the laboratory fish. This suggests that either 1) there were genetic differences controlling parr-mark number between the laboratory and the wild fish with regards to the genetic control of parr mark number in these groups, or 2) population specific environmental influences (e.g., temperature) were modifying the parr-mark number of the genetically different wild juvenile trout, during their embryonic development in their respective natal streams, to produce a similar parr-mark number in these stocks of fish. Genetic differences in agonistic behaviour were also investigated in laboratory incubated juvenile rainbow trout from the Waimarino and Tokaanu Rivers. Because of the small sample sizes involved in this experiment, the results are considered to be only preliminary. However, if the observations reflect the behaviours in the wild populations, this genetic difference is likely to be adaptive and have evolved in response to the very different conditions in these two rearing streams. Finally, embryo and alevin development and survival rates were examined for fish from the Waimarino and Tokaanu Rivers. Two pure and two reciprocal-hybrid crosses were made and the resulting groups were incubated at the same time and under identical conditions at target temperatures of either 12 or 7°C. Within temperatures, the hatching date was the same for all crosses (12°C, 27 d; 7°C, 51 d). However, there were significant among-cross differences, within temperatures, with respect to emergence date; these differences were a result of phenotypic (egg size) and genotypic variability. Alevins from smaller eggs emerged earlier than equivalent crosses from larger eggs; alevins sired by Tokaanu River males emerged earlier than equivalent crosses of Waimarino River males. Samples of eggs were also taken ovulated rainbow trout from each population and the Tokaanu rainbow trout had lower egg weights at standard female lengths. These population differences in egg-size and rates of development are thought to be adaptive and to have evolved in response to conditions encountered by the incubating fish m their respective natal streams. The Tokaanu river has an inferior spawning environment, with lower intra-redd dissolved oxygen levels and poorer quality gravel; thus, selection has produced a population of rainbow trout having small eggs, fast developing alevins in order to maximize survival under adverse incubation conditions. Survival rates from fertilization to hatch in the experimental crosses were above 90% for all groups at both 7 and 12°C; however, embryos of larger eggs had slightly, but consistently, lower survival rates than embryos from smaller eggs, at both temperatures. Likewise, survival from hatch to emergence was also above 90% for all crosses at 12°C; however, there were substantial among cross differences in alevin survival rates at 7°C and this was the result of phenotypic (egg size) and genotypic (population) effects. These differences are also thought to be adaptive and appear to reflect selection resulting from water temperature differences that these alevins would normally encounter under natural conditions in their respective natal streams.