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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
471

Low rates of nitrogen and phosphorus as fertilizer options for maize (Zea mays L.) in drier regions

Kgonyane, Mailula Cedric January 2010 (has links)
Thesis (M.Sc. (Agronomy))--University of Limpopo, 2010 / Refer to document.
472

Regional Differences in Demographic Characteristics, Professional Practices, and Employment Conditions of School Psychologists Across the United States

Abshier, Dama W 07 July 2008 (has links)
The field of school psychology has grown tremendously within the past 100 years, and legislation has played a major role in many changes related to the field. A review of the literature revealed that many studies have been conducted that explored demographic information, professional practices, and employment conditions. The studies tend to be somewhat narrow in focus (e.g., one study may look at demographic characteristics, while another considers only professional practices) and consider state differences rather than regional differences. In accordance with a policy established by the National Association of School Psychologists (NASP) that a study be conducted every five years, Graden and Curtis (1991) surveyed school psychologists who were members of the NASP for the purpose of developing a national database that reflected the demographic characteristics, employment conditions, and professional practices for the field during the 1989-1990 school year. Members of the NASP have been surveyed relative to the same information every five years since that initial study. The fourth national NASP study was initiated in June of 2005 using data based on the 2004-2005 school year. The database was created using survey data. The present study represented a secondary analysis of the database for the purpose of examining regional differences across the nine U.S. census regions. Regional differences in demographic characteristics, professional practices related to special education, direct and indirect services to students, and employment conditions were analyzed utilizing chi-square analyses and analyses of variance. When significant relationships were found, follow up t-tests were conducted to identify regions between which differences existed. Results indicated statistically significant regional differences for highest degree earned, licensure that allowed for independent practice in non-school settings, the number of re-evaluations conducted, the percentage of ethnic minority students in the district and served, the ratio of students to school psychologists for the district and based on caseloads, the number of days in respondents' contracts, salaries, and percentage of respondents who received clinical supervision.
473

Boundaries for use in wheat variety classification use in Australia

Williams, Richard Malcolm January 2006 (has links)
Suppliers of wheat must ensure that their products have the required quality profile demanded by customers and consistently deliver that quality in order to be competitive. Australia’s wheat industry is highly exposed to such competitive threats because it relies heavily on exports. An integral component in maintaining Australia’s competitiveness has been its classification system. The first step involves the complex process of determining a genotypic quality profile of each variety – a variety classification. At harvest, subsequent steps are the use of a statutory declaration and testing of physical quality traits. Together these steps determine how deliveries of wheat are segregated. A single variety can have different classifications across the 7 classification regions of Australia. Most classification regions are divided along state borders and these are not reflective of potential environmental influences. / The manner in which Australia wheat breeding programs now tackle their task has changed since 1999. The commercially focused companies of the current era have national targets to remain viable, and are focused on costs. Other evolutions associated with the change, are the introduction of different sources of parental material, and moving to more economic composite quality testing regimes instead of the individual site by site testing used in the past. Together, these factors, particularly variety adaptability and stability of performance, have the capacity to increase variability. The likelihood of variation is further increased given that the current classification regions upon which classification decisions are made do not adequately reflect environmental effects on the expression of quality. To determine whether better divisions of the Australian wheat-belt could be identified for variety classification purposes, a substantial spatial and temporal database of historical quality results was assembled. The creation of this relational database was unique, because never before had expansive sets of independent, state-based, quality sub-sets been joined together. However, the data were unbalanced and required alternative statistical tools to be analysed. The relational database was the platform from which three phases of research were conducted. / The first research phase investigated the extent of cross over, or re-ranking of results, statistically referred to as genotype x environment interaction. The approach was to assess balanced data sets, in a manner reminiscent of the most common method identified from the literature. The results of those analyses showed that the size of genotype and environment interaction was small compared with the main effects of genotype and environment. The second phase of research focused on identifying alternative boundaries for classification purposes. Test divisions were compared with the current set of 7 classification regions for the capacity to minimise environmental variance while maintaining differences between the zones of a set. Test divisions were based on fourteen published divisions of the Australian wheat-belt. Analyses were conducting using residual maximum likelihood because of the unbalanced structure of the data. Estimates of variance components, quality trait means and standard errors were calculated. Consideration of such estimates resulted in the identification of 4 different divisions of the wheat-belt that had low environmental variance levels for important quality traits such as maximum resistance, dough development time, and water absorption. / In addition, these 4 divisions of the wheat-belt had fewer number of zones compared with the existing set of classification regions because they linked separate parts of the wheat-belt together. In order of decreasing merit, the 4 divisions of the wheat-belt represented average October maximum temperatures; agro-ecological zones reported by Williams et al. (2002); average annual rainfall; and Departments of Agriculture recommendation zones. A final phase of crosschecking was performed to assess the veracity of the 4 identified divisions. A cluster analysis supported the orientation of their boundaries and it was also observed that the use of fixed boundaries for classification purposes would not be negatively affected by seasonal variation. The 4 divisions of the wheat-belt identified in this research support the use of environmentally focused classification boundaries. In addition to improving the capacity to segregate consistent quality, the linking of geographically separate production areas of the wheat-belt reduced the number of zones and this offers process efficiencies.
474

A modelling study into the effects of rainfall variability and vegetation patterns on surface runoff for semi-arid landscapes

Hearman, Amy January 2008 (has links)
[Truncated abstract] Generally hydrologic and ecologic models operate on arbitrary time and space scales, selected by the model developer or user based on the availability of field data. In reality rainfall is highly variable not only annually, seasonally and monthly but also the intensities within a rainfall event and infiltration properties on semi-arid hillslopes can also be highly variable as a result of discontinuous vegetation cover that form mosaics of areas with vegetation and areas of bare soil. This thesis is directed at improving our understanding of the impacts of the temporal representation of rainfall and spatial heterogeneity on model predictions of hydrologic thresholds and surface runoff coefficients on semi-arid landscapes at the point and hillslope scales. We firstly quantified within storm rainfall variability across a climate gradient in Western Australia by parameterizing the bounded random cascade rainfall model with one minute rainfall from 15 locations across Western Australia. This study revealed that rainfall activity generated in the tropics had more within storm variability and a larger proportion of the storm events received the majority of rain in the first half of the event. Rainfall generated from fontal activity in the south was less variable and more evenly distributed throughout the event. Parameters from the rainfall analysis were then used as inputs into a conceptual point scale surface runoff model to investigate the sensitivity of point scale surface runoff thresholds to the resolution of rainfall inputs. This study related maximum infiltration capacities to average storm intensities (k*) and showed where model predictions of infiltration excess were most sensitive to rainfall resolution (ln k* = 0.4) and where using time averaged rainfall data can lead to an under prediction of infiltration excess and an over prediction of the amount of water entering the soil (ln k* > 2). For soils susceptible to both infiltration excess and saturation excess, total runoff sensitivity was scaled by relating drainage coefficients to average storm intensities (g*) and parameter ranges where predicted runoff was dominated by infiltration excess or saturation excess depending on the resolution of rainfall data were determined (ln g* <2). The sensitivity of surface runoff predictions and the influence of specific within storm properties were then analysed on the hillslope scale. '...' It was found that using the flow model we still get threshold behaviour in surface runoff. Where conditions produce slow surface runoff velocities, spatial heterogeneity and temporal heterogeneity influences hillslope surface runoff amounts. Where conditions create higher surface runoff velocities, the temporal structure of within storm intensities has a larger influence on runoff amounts than spatial heterogeneity. Our results show that a general understanding of the prevailing rainfall conditions and the soil's infiltration capacity can help in deciding whether high rainfall resolutions (below 1 h) are required for accurate surface runoff predictions. The results of this study can be considered a contribution to understanding the way within storm properties effect the processes on the hillslope under a range of overall storm, slope and infiltration conditions as well as an improved understanding of how different vegetation patterns function to trap runoff at different total vegetation covers and rainfall intensities.
475

What's in the brew? A study of the molecular environment of methanol masers and UCHII regions.

Purcell, Cormac, Physics, Faculty of Science, UNSW January 2006 (has links)
In recent years the 6.67 GHz masing transition of CH3OH has proven to be a superior tracer of massive star formation (see Minier 2001). Maser sites often occur in proximity to UCHII regions, however, up to 75 per cent of sites have no detectable radio counterpart (Walsh 1998) and are instead hypothesised to trace the less evolved 'hot molecular core' phase of stellar evolution. This has been confirmed for a only handful of well known sources (e.g., Cesaroni 1994). Presented here are the results of multi-species molecular line observations towards warm, dusty clumps, undertaken with the goal of investigating the relationship between hot cores, UCHII regions and CH3OH masers. Data from the 22-m Mopra telescope is used extensively in this thesis and substantial efforts were made to calibrate the brightness temperature scale. Measurements conducted on SiO masers and planets show that the beam pattern is divided into a Gaussian main beam plus an inner error lobe, which in 2004 contained 1/3 of the power in the main beam. Full-width half-maximum beam sizes were measured from the data and the beam efficiencies were derived for the years 2000-2004. A 3-mm wavelength molecular line survey was conducted, using Mopra, towards 83 massive star-forming clumps associated with CH3OH masers. Emission from the transitions 13CO (1-0), N2H+ (1-0), HCO+ (1-0), HCN (1-0) and HNC (1-0) was detected towards 82 sources (99 per cent), while CH3OH emission was detected towards 78 sources (94 per cent). The warm gas tracer CH3CN was observed specifically to search for hot core chemistry, and was detected towards 58 sources (70 per cent), confirming that CH3OH masers are excellent tracers of hot cores. CH3CN is found to be brighter and more commonly detected towards masers associated with UCHII regions compared to 'isolated' masers. That CH3CN is detected towards isolated maser sources strongly suggests that these objects are internally heated. The molecular line data have been used to derive rotational temperatures and chemical abundances in the clumps and these properties have been compared between sub-samples associated with different indicators of evolution. In particular, CH3OH is found to be brighter and more abundant in UCHII regions and in sources with detected CH3CN, and may constitute a crude molecular clock in single dish observations. Gas-kinematics were analysed via asymmetries in the HCO+ line profiles. Approximately equal numbers of red and blue-skewed profiles, indicative of inward or outward motions, respectively, are found among all classes of object. Bolometric luminosities were derived via greybody fits to the sub-millimetre and mid-infrared spectral energy distributions, and an empirical gas-mass to luminosity relation of L proportional to M^0.68 was fit to the sample. This is a considerably shallower power law than L proportional to M^3 for massive main-sequence stars. In the mid-infrared, 12 sources were identified as 'infrared dark clouds' (IRDCs). Such objects have been hypothesised as precursors to the hot core phase of evolution, however, we find these sources have greater linewidths and rotational temperatures than the bulk of the sample, and one contains an embedded HII region The filamentary star forming region NGC3576 was also investigated via a molecular line and 23 GHz continuum mapping survey, utilising the ATCA, Mopra and Tidbinbilla telescopes. The results of these observations provide detailed information on the morphology, masses, kinematics, and physical and chemical conditions along the cloud. Analysis of NH3 data has revealed that the temperature and linewidth gradients exist in the western arm of the filament. Values are highest near to the central HII region, indicating that the embedded cluster of young stars is influencing the conditions in the bulk of the gas. Six new H2O masers were detected in the arms of the filament, all associated with clumps of NH3 emission. Star formation is clearly underway, however, clump masses range from 1 to 128 solar masses, possibly too low to harbour very massive stars. The lack of detected 23 GHz continuum emission in the arms supports this assertion.
476

Pre-settlement paleoecology of Central Otago�s semi-arid lowlands, with emphasis on the pre-settlement role of avian herbivory in South Island dryland ecosystems, New Zealand

Wood, Jamie Russell, n/a January 2008 (has links)
The vegetation communities that existed in the semi-arid intermontane basins and gorges of Central Otago prior to human settlement ~750 years B.P. are poorly understood. This is because of a lack of fossil evidence and complex restructuring by anthropogenic factors, especially increased fire frequency, and more recently mammalian grazing. There is also little information regarding the effect of the lost fauna on maintaining and structuring presettlement communities, both in Central Otago and throughout the eastern South Island dryland zone. This study aims to provide a clearer understanding of the functioning of pre-settlement ecosystems in dryland Central Otago, particularly the role of the largest vertebrate herbivores, the moa (Aves: Dinornithiformes), and to explore the implications of the extinct fauna for land conservation management across New Zealand. Late Pleistocene and Holocene vegetation communities of the Central Otago lowlands were reconstructed from plant macrofossils, including seeds, leaves, and wood, excavated from rockshelter, cave, and swamp deposits throughout the region. The macrofossils represent three main vegetation types: late Pleistocene to mid (late?) Holocene basin floor wetland herb associations, Olearia-shrublands surrounding these wetlands, and mid to late Holocene open scrubland and woodland in gorges and on low altitude slopes, dominated by filiramulate Olearia, Coprosma, and Corokia, with abundant lianes (Muehlenbeckia spp. and Rubus spp.) and understorey herbs. Many native tree and shrub species that are presently widespread in the Central Otago lowlands were rare or absent prior to anthropogenic fires (e.g. Discaria toumatou, Kunzea ericoides, Leptospermum scoparium). Other tree and shrub species once present are now extinct in the region (e.g. Coprosma obconica, Plagianthus regius, Pseudopanax ferox). The loss of these indigenous woody vegetation communities was a major factor contributing to the extirpation of many small bird species, and undoubtedly also reptile and invertebrate species, from the region. Plant macrofossils from rockshelters included remains of bird nests, identifiable by desiccated feathers and eggshell amongst them. These macrofossils include the first described plant remains from the nests of moa, which were constructed from a shallow bed of twigs of locally available shrubs and lianes. Many of the twigs are 25-30 mm in length and show evidence of having been clipped by moa bills. Desiccated coprolites, mostly of moa, but also specimens attributed to Finsch�s duck (Chenonetta finschi) and red-crowned parakeet (Cyanoramphus novaezelandiae), were recovered from rockshelter excavations. Moa species associated with a sample of coprolites were identified using ancient DNA analysis, and plant macrofossils from these were examined, together with previously unexamined moa gizzard content samples excavated from mires in the eastern South Island dryland zone. The results indicate that, in addition to previously reported browsing, upland moa (Megalapteryx didinus) and heavy-footed moa (Pachyornis elephantopus) also functioned as grazers, and seeds in their coprolites are dominantly of low shrubs and ground-cover herbs. Of particular interest was the higher than expected frequency of seeds from the currently rare and threatened 'spring annual' herbs; Ceratocephala pungens and Myosurus minimus subsp. novae-zelandiae (Ranunculaceae), suggesting further research on potential ecological relationships between moa and these plants would be worthwhile. The results of this study have provided a baseline for future conservation and restoration projects in the Central Otago lowlands.
477

The ecological effects of sealed roads in arid ecosystems

Lee, Enhua. January 2006 (has links)
Thesis (Ph. D.)--University of New South Wales, 2006. / Title from PDF title page (viewed on Dec. 11, 2007). Includes bibliographical references (p. 179-201).
478

Ecological studies of arid rangelands in South Australia

Lay, Brendan G. January 1972 (has links) (PDF)
No description available.
479

L'oxygene dans le milieu interstellaire: l'apport des donnees spectroscopiques ISO/LWS

Vastel, Charlotte 18 December 2001 (has links) (PDF)
L'oxygene est l'un des elements les plus abondants dans le milieu interstellaire. Il est par consequent primordial de chercher a comprendre sa chimie et sous quelle forme il se trouve dans les differentes phases de ce milieu. Les contraintes imposees par les observations SWAS et ISO representent un defi pour les theoriciens car elles mettent en defaut les modeles etablis jusqu'a ce jour. Sous quelles formes se trouvent l'oxygene dans les nuages moleculaires et quelles sont les principales especes porteuses d'oxygene responsables du refroidissement? L'oxygene atomique est l'un des principaux agents de refroidissement du milieu interstellaire a travers ses transitions fondamentales dans l'infrarouge. Je presenterai dans un premier temps les outils utilises au cours de mon travail de recherche et particulierement l'instrument ISO/LWS utilise pour les observations de l'oxygene atomique. J'introduirai alors les observations obtenues en direction de complexes de formations d'etoiles (regions HII) lointaines dans notre Galaxie. Le rayonnement ultraviolet lointain des etoiles massives illumine et photo-dissocie la matiere environnante en creant une region de photo-dissociation (PDR). Les raies infrarouges emises par le gaz dans ces regions ([OI] 63 microns, [OI] 145 microns et [CII] 158 microns) dominent le refroidissement dans le milieu interstellaire. L'absorption du rayonnement continu intense emit par ces regions sur la ligne de visee va permettre de tracer les nuages moleculaires presents dans les bras spiraux de la Galaxie. Je presenterai le travail de modelisation des spectres infrarouges en direction de deux PDRs spectaculaires W49N et Sagittarius B2 afin de caracteriser a la fois la PDR emettrice et les nuages moleculaires presents sur la ligne de visee. Une des conclusions de ce travail, en desaccord avec les modeles theoriques, implique que la majeure partie de l'oxygene en phase gazeuse dans les nuages moleculaires se trouve sous forme atomique. Ces observations sont en accord avec celles du satellite SWAS qui montrent que l'abondance du dioxygene (O2) est beaucoup plus faible que celle predite par les modeles. Ces resultats devraient permettre de mieux contraindre les futurs modeles theoriques. Ce travail a permis de mettre en evidence le caractere spectaculaire du complexe de formation d'etoiles W49N qui apparait comme l'une des regions HII les plus lumineuses de la Galaxie. Cette region est tres jeune et les proto-etoiles massives recemment formees et enfouies dans leur cocon n'ont pas eu le temps de disperser les nuages moleculaires environnants.
480

Vad är regionalism? : En jämförande studie av regionala partier i två svenska regioner; Skåne och Norrbotten / What is regionalism? : A comparative study of regional parties in two Swedish regions; Skåne och Norrbotten

Terzic, Zana January 2006 (has links)
<p>Regionalism is a concept of extensive proportions and as such is complex to define. This phenomenon becomes much clearer by studying it from different perspectives. This paper focuses on regional political parties and description of their political ideas. The goal of this paper is to examine and compare regional political parties in two Swedish regions: Norrbotten and Skåne. By studying two biggest regional parties in these regions, namely Norrbottensparti and Skånepartiet, I will try to get an insight into the regional politics, as well as illustrate regionalism and its meaning. My primary intention is to examine how these two regional parties experience their regions and what they consider of importance in regional development. By studying these regional parties and their opinion/apprehension about regional politics and their ideological/political affiliation, I will try to illustrate an ideological dimension of regionalism. My intention is to point out differences and similarities between politics of these regional parties, as well as to illustrate approach to the regionalism and its meaning.</p>

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