Vegetation response to clearing of exotic invasive plants along the Sabie River, South Africa

Student Number : 9202137P - MSc Dissertation - School of Animal, Plant and Environmental Studies - Faculty of ScienceThe Reconstruction and Development Programme’s Mpumalanga Working for Water Programme (WWP) has cleared exotic and commercial weed species from the riverine environment since 1994. This study serves as an assessment of the impact and modification caused as a result of invasion and the subsequent clearing of the exotic vegetation on flora in the riverine zone of the Sabie River Catchment. The experimental design compares the before and after clearing effects and includes altitude and invasion intensity variables. The investigations included: in situ soil seed banks, environmental modification, vegetation structure, species diversity and effectiveness of clearing. Clearing and invasion by exotic species altered soil chemical, physical and ground cover parameters. The extent of these modifications was dependent on the extent of invasion and clearing done within the community. Clearing of exotic species however, acted as an additional disturbance to that caused by invasion. Environmental modifications that occurred with clearing and invasion within the study were positively related to percentage soil organic matter, and ground cover (soil, litter, vegetation). Invasion by exotic species alters the vegetation structure, the extent of which was directly related to the invasion intensity. The main source of vegetation structure modification is attributed to tall growing exotic species such as Eucalyptus grandis and Solanum mauritianum. Both of these species dominated the indigenous vegetation, E. grandis by expanding the upper canopy and S. mauritianum by dominating the mid canopy. Clearing of invasive vegetation resulted in an additional disturbance proportional to the extent of invasion intensity. Invasion did not result in any large changes to the vegetation at low intensity but clearing at this intensity increased the disturbance and altered the vegetation structure. Soil seed banks were limited in the number of species and dominated by two exotic species. The soil seed bank of woody species related positively to the community species richness. The total soil seed bank density did not relate to invasion intensity or clearing thereof but propagules of individual species within the soil seed banks did. The seeds of the exotic species, Acacia mearnsii and S. mauritianum, illustrated burial as prerequisite for persistence in the soil seed bank. A. mearnsii and S. mauritianum seeds were found to have half-life’s of up to 25 years and 13 months respectively. The species richness and diversity varied only marginally because of invasion and clearing. Species alpha diversity increased with clearing due to weedy and pioneer species establishment. Beta diversity effectively highlights the species turnover with clearing and invasion. Success in eradication of exotic species had mixed results. Clearing of high invasion sites was effective but in lower invasion categories a number of exotic individuals were missed. Clearing effectiveness was good for certain species such as E. grandis and Pinus patula, but poor for others such as S. mauritianum. Coppicing is a significant issue for E. grandis and S. mauritianum. The persistence of individuals (coppicing & missed individuals) coupled with very large persistent seed banks has repercussions for the clearing programme, as it may prevent effective eradication. Initially the WWP has been successful in removing exotic vegetation, however there is a failure to address the regenerative properties of some exotic species. Unless a rigid schedule of follow up clearing treatments occurs, an even larger invasion problem could exist

That Driving Sound: Use of Tempo in Traditional Cape Breton Fiddle Performance

In Cape Breton traditional dance fiddling, the intimate rhythmic relationship between fiddle and feet yields smooth transitions from one tune type to another in order to facilitate the steps. Through analysis of 17 recorded performances of march, strathspey, and reel sets, I measure minute tempo fluctuations as they correspond to the concert presentation of a medley of tunes to explain the mechanics and roots of the large-scale continuous tempo acceleration. This acceleration comes out of the music’s relationship to dance, shaping the performance and helping to define the sound of Cape Breton fiddling.Dans les airs traditionnels de danse joués au violon à Cap-Breton, la relation rythmique intime entre le violon et les pieds permet des transitions fluides d'un type d'air à l'autre afin de faciliter les pas de danse. En analysant 17 enregistrements d'airs de marche, de strathspeys et de reels, je mesure jusqu'aux plus petites fluctuations de tempo correspondant à l'exécution en concert d'un pot-pourri de chansons pour expliquer la mécanique et les racines de l'accélération continue et à grande échelle du rythme. Cette accélération provient de la relation de la musique à la danse, qui modèle l'exécution et qui contribue à définir le son du violon de Cap-Breton

The use of formative evaluation with online courses by teachers at the secondary level

This case study investigated the use of formative evaluation by three teachers who designed and delivered online courses at the secondary level. Formative evaluation involves collecting data that could be used to improve the effectiveness of the design and delivery of a course. Teachers were observed teaching the courses they designed for one quarter and then were given a workshop introducing them to formative evaluation techniques. They were observed for another quarter to determine if their delivery or design practices changed. Additional data were collected through interviews and through the analysis of course-related artifacts that included emails, journal entries by the teachers, and threaded web discussions. Data were entered into the ATLAS.ti qualitative analysis software to aid in the linking and reporting of the open and axial coding of the data. The following questions framed the study: (1) To what extent was the process of formative evaluation used by teachers who designed and delivered online courses at the secondary level in an online high school? (2) What changes in online teaching practice or course design resulted following the instruction and application of formative evaluation procedures by teachers who designed and delivered online courses at the secondary level in an online high school? (3) What standards, checklists, or other instructional design framework existed that influenced the use of formative evaluation by the participating teachers?;The results indicated that formative evaluation was used by all three teachers in varying degRees Only a few minor changes were evident in the design or delivery following the workshop. No framework at the school addressed the need for or value of formative evaluation. Due to curricular demands on the teachers, a lack of student compliance, and a lack of a formal or accountable framework, the feedback to improve the courses proved difficult for teachers to obtain. A framework, in the form of a checklist for conducting formative evaluation, was a product of this research

Crush Testing, Characterizing, and Modeling the Crashworthiness of Composite Laminates

Research in the field of crashworthiness of composite materials is presented. A new crush test method was produced to characterize the crush behavior of composite laminates. In addition, a model of the crush behavior and a method for rank ordering the energy absorption capability of various laminates were developed. The new crush test method was used for evaluating the crush behavior of flat carbon/epoxy composite specimens at quasi-static and dynamic rates. The University of Utah crush test fixture was designed to support the flat specimen against catastrophic buckling. A gap, where the specimen is unsupported, allowed unhindered crushing of the specimen. In addition, the specimen\u27s failure modes could be clearly observed during crush testing. Extensive crush testing was conducted wherein the crush force and displacement data were collected to calculate the energy absorption, and high speed video was captured during dynamic testing. Crush tests were also performed over a range of fixture gap heights. The basic failure modes were buckling, crack growth, and fracture. Gap height variations resulted in poorly, properly, and overly constrained specimens. In addition, guidelines for designing a composite laminate for crashworthiness were developed. Modeling of the crush behavior consisted of the delamination and fracture of a single ply or group of like plies during crushing. Delamination crack extension was modeled using the mode I energy release rate, G1c. where an elastica approach was used to obtain the strain energy. Variations in G1c were briefly explored with double cantilever beam tests wherein crack extension occurred along a multidirectional ply interface. The model correctly predicted the failure modes for most of the test cases, and offered insight into how the input parameters affect the model. The ranking method related coefficients of the laminate and sublaminate stiffness matrices, the ply locations within the laminate, and the laminate thickness. The ranking method correctly ordered the laminates tested in this study with respect to their energy absorption

Two Scales, One Methodology - Expenditure Based Equivalence Scales for the United States and Germany

Choosing an appropriate equivalence scale is a prerequisite for comparisons of economic wellbeing income distribution, inequality or poverty. This is true for country specific work or for cross-national comparisons. Researchers generally either use a country specific equivalence scale (social assistance, expert based, or poverty scales), or adopt a single scale for all comparison across countries. Here we follow a different approach. We use microdata to estimate equivalence scales based on a revealed preference consumption approach for West Germany and the United States. We review several approaches and rely on a complete demand system approach, which provides constant utility based equivalence scales using an extended linear expenditure system (ELES). The multiple equation expenditure system takes into account a full market basket with all its interdependencies and relative prices. Our consumption-based equivalence results are compared to alternative consumption based measures, expert based measures, and subjective based measures in use in both countries and to other scales used for cross-national comparisons.alternative equivalence scale, Germany, USA, distribution of income, inequality, poverty

The impact of mass deworming programmes on schooling and economic development: an appraisal of long-term studies

Background Documents from advocacy and fund-raising organizations for child mass deworming programmes in low and middle-income countries cite unpublished economic studies claiming long-term effects on health, schooling and economic development. Methods To summarise and appraise these studies, we searched for and included all long-term follow-up studies, based on cluster-randomized trials included in a 2015 Cochrane review on deworming. We used Cochrane methods to assess risk of bias, and appraised the credibility of the main findings. Where necessary we contacted study authors for clarifications. Results We identified three studies (Baird 2016, Ozier 2016, and Croke 2014), evaluating effects more than nine years after cluster-randomized trials in Kenya and Uganda. Baird and Croke evaluate short additional exposures to deworming programmes in settings where all children were dewormed multiple times. Ozier evaluates potential spin-off effects to infants living in areas with school-based deworming. None of the studies used pre-planned protocols, or blinded the analysis to treatment allocation. Baird 2016 has been presented on-line in six iterations. It is at high risk of reporting bias and selective reporting, and there are substantive changes between versions. The main cited effects on secondary school attendance and job sector allocation are from post-hoc sub-group analyses, which the study was not powered to assess. The study finds no evidence of effect on nutritional status, cognitive tests, or school grades achieved, but these are not reported in the abstracts. Ozier 2016 has been presented on-line in four iterations, without substantive differences between versions. Higher cognitive test scores were associated with deworming but were only beyond the play of chance with inclusion of the non-randomised data. The size of the stated effect seems inconsistent with the short and indirect nature of the exposure to deworming, and a causal pathway for this effect is unclear. Croke 2014 utilizes a data set unrelated to the base trial to report improvements in English and maths test scores. The analysis is at high risk of attrition bias, due to loss of clusters, and is substantially underpowered to assess these effects. Conclusion In the context of reliable epidemiological methods, all three studies are at risk of substantial methodological bias. They therefore help in generating hypothesis, but should not be considered reliable evidence of effects