Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 192 for “"Rarity"”.
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Defining rarity and determining the mechanisms of rarity for North American freshwater fishes
… depends on sound information on the nature of rarity. Rarity is multidimensional, presenting the need for a quantitative classification scheme by which to label species as rare or common. I defined rarity for freshwater fishes based on the range extents, habitat breadths, and site abundance and …
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The causes of avian extinction and rarity
Biological extinction rates have escalated by as much as 1000 times the background extinction rate over the last 1500 years, causing concern over the long-term survival of many species. Avian extinctions since 1600 have been well documented relative to other taxa, as have current levels of avian …
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The causes of avian extinction and rarity
Biological extinction rates have escalated by as much as 1000 times the background extinction rate over the last 1500 years, causing concern over the long-term survival of many species. Avian extinctions since 1600 have been well documented relative to other taxa, as have current levels of avian …
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Rarity of Novel microRNAs in the Mouse Inner Ear
The vertebrate inner ear is a complex organ that is highly regulated throughout development by molecular and cellular factors such as morphogens and transcription factors. Another class of gene regulators whose function in the inner ear is essential but not well understood is microRNAs. Previous …
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Regional Rarity: Consequences of Dispersal Limitation and Strategies for Reintroduction
… mechanisms have been proposed to contribute to rarity, including species traits, propagule limitation, ecological requirements, and population level processes such as demographic and environmental stochasticity. Yet, our understanding of species rarity remains limited since few studies have …
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RETHINKING RARITY: ASSESSING CLINICAL REPORTS OF WORD FINAL DISFLUENCY (WFD)
Existing literature highlights that word-final disfluency (WFD), a type of atypical dysfluencyinvolving final sound/syllable repetition, is distinct from developmental stuttering. However, current research is limited primarily to case studies, restricting the generalizability of those findings. The …
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Vegetation, diversity and rarity on the Cape Peninsula, South Africa
The Cape Peninsula, (471 km²) with over 2285 vascular plant species, is characterised by the combination of a diversity of habitats supporting a mosaic of vegetation types. This study attempts to describe and explain some of the determinants of species pattern and distribution. The first part of …
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Vegetation, diversity and rarity on the Cape Peninsula, South Africa
… the flora is characterized by a high degree of rarity, a phenomenon that undoubtedly influences the turnover. Thus, the third part of this thesis analyses the biological and habitat correlates of plant rarity. Given the Jack of any general theory of University of Cape Town iii ' causality, …
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Causes of rarity in glade-endemic plants: Implications for responses to climate change
… between reproductive specialization and rarity that addresses additional factors influencing rare taxa, such as stress-adaptation, and that has important implications for species' responses to climate change.
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The preservation of the Cape flora : status, causes of rarity, ideals and priorities
… strategies are most strongly correlated with rarity, most specifically with distributional area. Using distributional data for the Proteaceae, this study estimates that 95 per cent of all vascular plant species in Fynbos can be preserved in 16 per cent of the area. It also identifies the sites …
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Environmental driver effects on population growth rates vary by rarity type and variation in demographic rate sensitivity
… their effects could vary by population or rarity type (range size, habitat specificity, and population density). I examined how the effects of drivers on vital rates could impact population growth due to variation of population growth sensitivity to demographic rates. I found significant …
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Investigating sources of phonological rarity and instability: a study of the palatal lateral approximant in Brazilian Portuguese
"The palatal lateral is a rare sound in the world's languages; a review of the literature reveals just 23 languages that currently possess the palatal lateral. Similarly, only 15 (or 3.33%) of the languages in the UCLA Phonological Segment Inventory Database (UPSID) (Maddieson and Precoda, 1991) …
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Rarity, cause or consequence: comparative landscape genomics of six lichenized fungi with contrasting range sizes, life histories, and morphologies
… bacteria, often exhibiting a high incidence of rarity. As an emergent trait, rarity encompasses the complexities of a species’ life-history traits and its environment. Using a comparative framework, we examined the population and landscape genetic patterns associated with rarity in related …
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Kidney stone rarity in South Africa's black population : investigation of the biochemical and physico-chemical properties of Tamm Horsfall Mucoprotein as a possible contributory factor
Tamm Horsfall mucoprotein (THP) is a powerful inhibitor of calcium oxalate crystallisation. Since urolithiasis in South African blacks is extremely rare, this study was undertaken to compare the relative inhibitory and biochemical properties of this protein in South African black and white healthy …
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An Investigation into L2 Lexical Proficiency of Norwegian Secondary Learners
… under examination, namely volume, variability, rarity, dispersion, evenness, and semantic disparity. Rarity in this study was examined based on the frequency information from three registers, which are general (i.e. frequency per million words), academic, and fiction. A total of 739 texts …
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Mediating chance encounters through opportunistic social matching
… of opportune personal context; and contextual rarity as an indicator of opportune relational context. The following study combining Experience Sampling Method (ESM) and participant interviews extends prior research on social matching by providing an empirical foundation for the design of …
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Effects of management practices on the ground beetle assemblages of grassland and related habitats (Coleoptera: Carabidae)
… Scotland found a general reduction in diversity, rarity and body size as management intensified, with silage fields having especially low values of WML. Diversity and rarity fell sharply between the second and third levels of management. Multivariate analysis of the species composition also made a …
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Rarity of kidney stones in South Africa's black population : studies of urinary macromolecules, crystal matrix extract containing osteopontin, and bone turnover markers in urine and serum from black and white subjects as a key to understanding this paradox
… physiological factors contributing towards the rarity of kidney stone disease in the South African black population. Healthy, age-matched male subjects from the black and white population groups were recruited for this purpose. In several of the studies, subjects followed a standardized diet and …
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Modelling mitigation of bird population declines in the UK through landscape-scale environmental management.
… of declining species, conservation priority, and rarity), as species richness and diversity alone can mask effects on more vulnerable species. Relationships with bird community composition and the habitat variables were also investigated using Multidimensional Scaling (MDS). Although bird …
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