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    Vegetation patterns in the northern jarrah forest of Western Australia in relation to dieback history and the current distribution of Phytophthora cinnamomi

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    Dieback, largely attributed to the fungal plant pathogen Phytophthora cinnamomi, is characterized in the northern jarrah forest by multiple deaths of many plant species, including the dominant, Eucalyptus marginata (jarrah), a species of great commercial importance. The wide host range of the pathogen has major implications for the biodiversity of the ecosystem. The first records of dieback in the jarrah forest were made in the 1920s.\ud \ud Despite the magnitude and long history of the impact in the jarrah forest, little is known about the vegetation changes that result from dieback. In this dissertation, I develop a model of vegetation change related to dieback by examining the vegetation of a range of dieback sites and relating the patterns identified to the current distribution of P. cinnamomi. The study is the first explicit investigation of floristic and structural patterns on dieback sites in the jarrah forest.\ud \ud Substantial floristic differences were found between dieback and unaffected vegetation. The patterns are strongly correlated with the age of the original dieback event. There was little difference, however, in the mean number of species I quadrat between dieback and unaffected vegetation. The time since the inception of dieback was estimated using aerial photography. The oldest dieback sites located had been affected prior to 1951. Of the species found less frequently on these old dieback sites, 64% had not previously been associated with P. cinnamomi infection. Some of these were assessed for their susceptibility in glasshouse pathogenicity tests. New records of susceptibility were made at the species, genus and family levels. Several species regarded as being highly susceptible to infection by P. cinnamomi were found as frequently on old dieback sites as in unaffected vegetation. Many of the species found more frequently on dieback sites were probably present at the time of the initial dieback event. Others, mostly annuals, may have been introduced from nearby vegetation types with open canopies, such as granite outcrops. If plant invasions have occurred following dieback, the small differences in species richness between dieback and unaffected vegetation may hide a great reduction in species richness due to dieback.\ud \ud Structural changes following dieback may have a profound effect on some species regardless of their susceptibility to infection. A spatial association with trees on dieback sites was demonstrated for a range of species. The apparent reliance of some understorey species on tree cover is discussed in relation to current theories of patch dynamics.\ud \ud Two methods were used to isolate P. cinnamomi from dieback sites. In situ Banksia grandis baits were more effective at detecting P. cinnamomi than ex situ baited soils, especially when P. cinnamomi was apparently rare.\ud \ud P. cinnamomi was frequently isolated from creek edges with a long history of dieback and from active dieback fronts but was rarely found on sloping dieback sites affected prior to 1980. It is not clear if the P. cinnamomi present on pre-1951 dieback sites has persisted there since the initial dieback event or been re-introduced from active dieback fronts upslope.\ud \ud Very few highly susceptible species appear to be totally eliminated by the pathogen at the time of the initial dieback event. The mass deaths at that time are followed by a period of recolonization of susceptible species with highly germinable seed. The survival of the new cohort of these species is a function of the time taken to produce another crop of seed.\ud \ud Susceptible species may persist on the pre-1951 dieback sites because of highly germinable seed, young reproductive age, copious seed production and animal dispersal. The rarity of P. cinnamomi on these sites must greatly contribute to their persistence.\ud \ud Pathogenicity testing in excised stems indicated that resistance to the movement of P. cinnamomi in plant tissue develops in jarrah populations on many dieback sites, although it is unlikely to be integral to regeneration. Evidence of resistance in other spec1es investigated could not be found.\ud \ud The key elements in the model of vegetation change developed in the thesis are (i) the on-going occurrence of P. cinnamomi on dieback sites, (ii) the susceptibility of plant species to infection by P. cinflamomi, (iii) the sensitivity of plant species to structural changes, (iv) the proportion of a plant population killed, (v) the capacity of plant species for rapid recruitment after dieback, (vi) the time taken for plant species from germination to reproduction, and (vii) the capacity of plant species to invade. Stochastic factors such as fire, logging, climatic perturbations, and diseases caused by other pathogens, cannot be quantified and easily incorporated into the model.\ud \ud Predictions are made about the future vegetation of dieback sites, contingent on intervention by forest managers. An epidemic - recovery cycle, involving concomitant fluctuations in pathogen and host populations, has been hypothesized by some authors for sites affected by P. cinnamomi. There is evidence of such a cycle on a small scale. On a larger scale, epidemics on dieback sites in the jarrah forest may be isolated in space and time.\ud \ud The importance of long-term ecological studies of jarrah forest vegetation to our understanding of natural forest processes and the effects of dieback is stressed

    Co-authorship and negotiation: The interview as act of creation

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    The impact of adding assistants in nursing to acute care hospital ward nurse staffing on adverse patient outcomes: An analysis of administrative health data

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    Objectives The aim of this study was to assess the impact of adding assistants in nursing to acute care hospital ward nurse staffing on adverse patient outcomes using administrative health data. Design Logistic regression modelling was used with linked administrative health data to examine the association between seven adverse patient outcomes and use of assistants in nursing utilising a pre-test/post-test design. Outcomes included were in-hospital 30-day mortality, failure to rescue, urinary tract infection, pressure injury, pneumonia, sepsis and falls with injury. Setting Eleven acute care metropolitan hospitals in Western Australia. Sample Patients were retained in the dataset if they spent any time on a medical, surgical or rehabilitation ward during their admission and excluded if they only spent time on other ward types, as the outcomes used in this study are only validated for these patient populations. There were 256,302 patient records in the total sample with 125,762 in the pre-test period (2006–2007) and 130,540 in the post-test period (2009–2010). Results The results showed three significant increases in observed to expected adverse outcomes on the assistant in nursing wards (failure to rescue, urinary tract infection, falls with injury), with one significant decrease (mortality). On the non-assistant in nursing wards there was one significant decrease (pneumonia) in the observed to expected adverse outcomes and one significant increase (falls with injury). Post-test analysis showed that spending time on assistant in nursing wards was a significant predictor for urinary tract infection and pneumonia. For every 10% of extra time patients spent on assistant in nursing wards they had a 1% increase in the odds of developing a urinary tract infection and a 2% increase in the odds of developing pneumonia. Conclusion The results suggest that the introduction of assistants in nursing into ward staffing in an additive role should be done under a protocol which clearly defines their role, scope of practice, and working relationship with registered nurses, and the impact on patient care should be monitored

    The effect of use 'viva' assessment and perceptions of ability on student's approaches to study in higher education

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    This study explores the concept of constructively aligned approaches to teaching and assessment, and the effect this has on students' approaches to learning and motivation. The theory of constructive alignment states that teaching methodologies, learning outcomes and methods of assessment should all support and complement each other, in order to create an effective learning environment (Biggs, 2000). The study also investigates students' conceptions of ability, i.e. fixed or incremental, to test whether this factor has an impact on their motivation and approach to study. The rationale for this work is to inform educational practitioners, encouraging teaching practices that foster deeper levels of understanding and higher levels of engagement for students. This work has arisen from earlier studies that report a decrease in deep approaches at the end of the module (Newstead, 1998; Solominides & Swannell, 1995). Newstead attributed the increase in surface scores as a response to the proximity of formal examination, suggesting that approach might change in relation to particular demands within a module such as assessment. Fazey & Lawson's (2000) study investigated the use of a teaching approach that fosters a deep approach to learning through interactive learning. This was supported by an assessment methodology (viva voce) that required students to demonstrate a deep understanding of the subject. They found that students taught using this constructively aligned methodology that encouraged understanding, maintained their deep approach to study and significantly decreased their surface approach at the assessment period of the module

    International typing study of Clostridium difficile

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    We report the results of an international Clostridium difficile typing study to cross reference strain designations for seven typing methodologies and facilitate inter-laboratory communication. Four genotypic and three phenotypic methods were used to type 100 isolates and compare the results to 39 PCR ribotypes identified among the collection

    Movement and human existence: Mysterium of mundanity - whence to where

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    This work develops a few simple ideas demanding a rather complex manner of exposition and demonstration..

    The production of this and that by young children

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    Many studies have considered the child's developing comprehension of the deictic terms this and that, used to refer to spatial proximity and distance. This is in contrast with the paucity of research into the child's early use of these terms. In the present study, three-year-old children produced both of these deictic terms and each was accompanied by characteristic specific gestures. This was accompanied by a picking up and handling of the object being referred to, while the gestural support for that was either a point or a proffering of the object, depending on spatial contextual restrictions. From this evidence, it is argued that children can use a pragmatic system of deictic contrasts, integrating both verbal and gestural aspects

    Article acquisition: Theoretical and empirical issues

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    Two theoretical approaches to the study of the acquisition of the determiners, including the articles, in English can be identified. The definite and indefinite articles (the and a) are usually regarded as a contrastive system. Either form is required with a noun, depending on certain semantic and pragmatic considerations. However, both historical and recent developmental psycholinguistic evidence suggest that the articles should be incorporated into a total system of determination. These approaches have influenced the interpretation of research into children's use and understanding of the articles. The contrastive approach considers the acquisition process as one of attaining adult usage, and experimentally, the articles produced by children can be correct or incorrect. The functional approach considers all article forms elicited in an experiment, and discusses why such forms were used and the functions they fulfill. An experiment is described to show 3-year-old children's use of the articles within specific contexts. It argued that instead of regarding the child's use of the and a as correct or incorrect with respect to appropriate adult use, we should look at the functions of those determiners used by the young child, particularly those that are dependent on the linguistic input

    The tuning of auditory receptors in bushcrickets

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    The auditory organ of bushcrickets consists of an array of chordotonal sensilla in the insect's foreleg. Physiological recordings from these sensilla demonstrate that the individual receptors are tuned to specific sound frequencies and that the array is tonotopically organised. This frequency selectivity and tonotopic organisation are not altered by severely disrupting the integrity of the receptor array. Since the tuning of the individual receptors is not dependent on resonance in the auditory canal (prothoracic trachea), tympanal membranes or receptor array it is proposed that it is due to mechanical and/or electrical properties of the individual receptors
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