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ABSTRACT In this thesis we deposit GaN films by magnetron rf sputtering with changes substrate temperature. The electron probe microscope analysis ( EPMA ), scanning electron microscope ( SEM ), photoluminescence measurement ( PL ) and X-ray diffraction ( XRD ) had been used to investigate these GaN films. We find GaN films crystalline quality deposit at low temperature is better then deposit at high temperature. From EPMA analysis we know higher substrate temperature lower oxygen amount of film. The ratio of Ga to N is 1.18 ~ 1.83 in average. The growth rate is about 0.30 £gm/h ~ 0.35 £gm/h in average. Thus changes substrate temperature do not influence growth rate obviously. From SEM and EDS analysis we find the roughness magnitude of films growth on sapphire substrate was smaller than the films growth on silicon substrate. We also find lower substrate temperature the roughness magnitude of films larger on silicon substrate.

No description available.

The Burdigalian Saumane-Venasque carbonate succession is located in the Rhodano-Provençal basin of southeastern France. These carbonates accumulated in a paleovalley that was flooded by marine waters. This marine embayment was filled by carbonates composed of twelve different facies. These sediments form two thick third-order sequences (S1 & S2) and several, thinner higher-order sequences (S1a, S1b, S1c). S1a is composed of quartzose grainstones with barnacles, echinoids, and bivalves derived from a rocky substrate paleocommunity in a high-energy, open-marine environment during the early phases of sea level rise. Compound dunes of S1a and S1b are composed of bryozoans and echinoids that are mixed with bioclasts from seagrass facies. Pervasive cross-bedded grainstones grade upward into low-energy mudstones and packstones of the S1 highstand. Bryozoan thickets populated sequence 2 during the second sea level cycle. Seven different phases of cement, including cloudy epitaxial, fibrous, isopachous columnar, isopachous equant, clear epitaxial, blocky, and pendant types, can be distinguished in these limestones. Marine hardgrounds are present throughout the area as steep, stepped margins in tidal channels. Marine cements are interpreted to have precipitated in the upper portion of subaqueous dunes with their location controlled by sedimentation rate and tidal pumping. Zoned epitaxial cements are interpreted to record shifts in the paleo-water table related to fluctuations in sea level throughout the Miocene in the Rhodano-Provençal basin. Shallow burial pressure dissolution features are present throughout the deposit. They are interpreted to result from extended exposure to fresh water, which produced grains that were particularly susceptible to compaction. The Saumane-Venasque temperate carbonates are different in that they were lithified without significant burial diagenesis, a situation that resulted from multiple sources of cement from marine and meteoric waters. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2009-09-04 16:00:33.914

The escalating threat of antimicrobial resistance has intensified the exploration of alternative treatments, with bacteriophage (phage) therapy emerging as a potential substitute for antibiotics. While strictly lytic phages rapidly kill bacteria, temperate phages can also go dormant in their hosts. Accordingly, despite their prevalence, they are considered unsuitable for therapy. My systematic review of phage therapy in urinary tract infections (UTIs) highlighted this. This review motivated me to explore how the potential of these phages could be leveraged. Chapter 3 introduces a novel strategy to do so, exploring whether the fluoroquinolone antibiotic ciprofloxacin could synergize with temperate phages. This innovative strategy exploits the ability of the antibiotic to awaken dormant temperate phages, driving a potent synergy (≥8 log reduction) able to result in bacterial eradication. This is a potential breakthrough in the use of phages. Chapter 4 expands on this finding, establishing that a synergy exists across various drug classes with diverse mechanisms of action. Surprisingly, the synergy extends beyond antibiotics triggering the bacterial SOS-response known to wake temperate phages and also includes protein synthesis inhibitors, offering a new approach to influence the phage lysis-lysogeny decision. Chapter 5 explores the identified synergy in antibiotic-resistant models, focusing on the impact of antibiotic resistance on the effect of combining temperate phages with antibiotics. While the majority of cases demonstrated synergy comparable to the absence of antibiotic resistance, an exception was noted in the acetylation-resistant models for both gentamicin and ciprofloxacin. These resistance genes abolished synergy with the temperate phage, emphasizing the importance of the resistance mechanism within temperate phage antibiotic synergy (tPAS). In conclusion, this thesis underscores the lack of interest in temperate phages for therapy and demonstrates a scalable strategy to overcome the major barriers to their use. I uncover the mechanisms underlying the synergy and show that these concepts are applicable even in the context of resistance to the synergizing antibiotic. These findings propose a remarkable shift in how antimicrobial therapy approaches are viewed. / Thesis / Doctor of Philosophy (PhD) / In the past decade, interest in viruses that only target bacteria (called “phages”) and their capacity to treat antibiotic-resistant infections has surged. Beginning with our systematic review on UTI treatments involving phages, we observed that none of the included studies explored the therapeutic use of the dormancy-capable “temperate” phages. This finding serves as motivation for the subsequent chapters of the thesis. In Chapter 3 I discovered temperate phage-antibiotic synergy (tPAS). An inventive strategy involving antibiotics activates temperate phages, demonstrating substantial synergy in eliminating bacterial infections and offering a potential breakthrough against antimicrobial resistance. In Chapter 4 I found that this synergy extends beyond antibiotics that result in a response to DNA damage within the bacteria (SOS response) to include protein synthesis inhibitors, providing an innovative approach to combat bacterial infections. Finally, in Chapter 5 I extended the study to antibiotic-resistant models. Across a wide array of mechanisms for antibiotic resistance, all but two supported the synergy we observed with temperate phage. This highlights the importance of the resistance mechanism in temperate phage antibiotic synergy (tPAS). The finding of this thesis paves the route for potentially integrating temperate phages into mainstream medical practices alongside antibiotic interventions.

The goal of this work was to quantify the effects of eucalypt woodland blocks on the productivity of native pastures. This research was conducted on the Southern Tablelands of New South Wales. Tree planting or retention is seen by many as an important tool in addressing the problems of soil degradation resulting from clearing and pasture improvement that threaten the sustainability of pasture systems. In particular these are dry land salinity and erosion, both of which affect large areas of agricultural lands in the south east of Australia. Whilst native tree cover remains over substantial portions of Australian pasture lands, mainly on steeper slopes and poorer soils, little has been done to measure the effects of trees on pasture productivity and soil fertility on the Southern Tablelands. Previous studies in other areas have shown a range of effects�from facilitation to inhibition�of pasture growth in the presence of trees. Soil fertility beneath trees has been shown by a number of workers to be elevated in comparison with situations in the open. Given that the range of effects may be highly site dependent, application of results from one area to another may not be valid. Thus it is necessary to measure tree effects on a regional scale if results are to be reliable. Pasture productivity was assessed over a two year period on four sites in the vicinity of Bungendore, New South Wales. A pair of plots was selected on each site, one plot in a block of eucalypt woodland, and the other nearby in an exposed, open situation. Plots were chosen to be as similar to each other as possible with the exception of tree cover. Treed plots had a tree basal area of between 10 and 20 m2 ha-1 and plots had an area of 900 m2. Two of the sites were on granitic soils and had a tree cover consisting predominantly of Eucalyptus pauciflora. The remaining two sites were on soil derived from sedimentary rocks with tree cover consisting mainly of E. mannifera, E. dives and E. melliodora. Perennial native pasture species present were similar across all sites, although their relative contributions to standing biomass varied between sites. As the plots were grazed during the period of measurement, productivity and offtake were measured seasonally using exclosure cages on each plot. Pasture standing biomass was assessed using the comparative yield technique. Microclimate was monitored in each plot by automatic weather stations. Soil moisture to a depth of 45 cm was measured by time domain reflectometry using permanent probes in each plot. Ten additional survey plots on each site, covering the range of tree basal area from 0 - 30 m2 ha-1, were assessed each season in the second year for standing biomass, soil fertility and pasture quality; expressed by nitrogen content and dry matter digestibility. Pasture floristics were measured using the dry-weight-rank method. These additional plots were chosen to be as representative of the paddocks as possible. Over the two years that productivity was measured, it was found to be higher under trees than in the open. This was predominantly due to higher winter and spring growth within treed plots. Grazing offtake was also found to be higher under trees, partly accounting for lower standing biomass found in the treed plots. Wind run, evapotranspiration and photosynthetically active radiation were all reduced by the presence of trees. Beneficial effects of shelter from winds may largely explain the higher productivity observed in the treed plots, and could outweigh negative effects of below ground competition and radiation interception by tree canopies at low to moderate tree densities. Soil moisture was not affected by the presence of trees. Soil fertility also did not differ between treed and open plots nor was there any difference in pasture nitrogen content or dry matter digestibility. On the sites where soils were derived from sedimentary rocks, pasture floristics were found to be related to tree basal area. Themeda ausfralis biomass was negatively related to tree basal area, and was partially replaced by large tussock species such as Poa sieberiana and Chionochloa pallida. A reduction of pasture quality resulted, particularly as the latter species is not grazed to any significant extent. Given the desirability of having deep rooted perennial components in grazing lands, the results of this study indicate that it may be possible to utilise trees to assist in preventing or reducing a range of adverse environmental consequences arising from agricultural activities, without unduly compromising pasture productivity. Additionally, the wide range of environmental conditions provided by a mix of treed and open pasture promotes a higher degree of heterogeneity of the herbaceous layer. This may assist in maintaining productivity over a greater range of climatic conditions than would be the case with a more homogeneous pasture.

Satellite imagery such as Landsat has been in use for decades for many landscape and regional scale mapping applications, but has been too coarse for use in detailed forest inventories where stand level structural and compositional information is desired. Recently available high spatial resolution satellite imagery may be well suited to mapping fine-scale components of ecosystems, however, this remains an area of ongoing research. The first goal of this thesis was to assess the capacity of high spatial resolution satellite imagery to detect the variability in late seral coastal temperate rainforests in British Columbia, Canada. Using an object-based classifier, two hierarchical classification schemes are evaluated: a broad classification based on structural (successional) stage and a finer classification of late seral vegetation associations. The finer-scale classification also incorporates ancillary landscape positional variables (elevation and potential soil moisture) derived from Light Detection and Ranging (LiDAR) data, and the relative contribution of spectral, textural and landscape positional data for this classification is determined. Results indicate that late seral forests can be well distinguished from younger forests using QuickBird spectral and textural data. However, discrimination among late seral forest associations is challenging, especially in the absence of landscape positional variables. Classification accuracies were particularly low for rare forest associations. Given this finding, the objective of the third chapter was to explicitly examine the caveats of using high spatial resolution imagery to map rare classes. Classification accuracy is assessed in several different ways in order to examine the impact on perceived map accuracy. In addition, the effects on habitat extent and configuration resulting from post-classification implementation of a minimum mapping unit are examined. Results indicate that classification accuracies may vary considerably depending on the assessment technique used. Specifically, ignoring the presence of fine-scale heterogeneity in a classification during accuracy assessment falsely lowered the accuracy estimates. Further, post-classification smoothing had a large effect on the spatial pattern of rare classes. These findings suggest that routinely used image classification and assessment techniques can greatly impact mapping of rare classes.

Satellite imagery such as Landsat has been in use for decades for many landscape and regional scale mapping applications, but has been too coarse for use in detailed forest inventories where stand level structural and compositional information is desired. Recently available high spatial resolution satellite imagery may be well suited to mapping fine-scale components of ecosystems, however, this remains an area of ongoing research. The first goal of this thesis was to assess the capacity of high spatial resolution satellite imagery to detect the variability in late seral coastal temperate rainforests in British Columbia, Canada. Using an object-based classifier, two hierarchical classification schemes are evaluated: a broad classification based on structural (successional) stage and a finer classification of late seral vegetation associations. The finer-scale classification also incorporates ancillary landscape positional variables (elevation and potential soil moisture) derived from Light Detection and Ranging (LiDAR) data, and the relative contribution of spectral, textural and landscape positional data for this classification is determined. Results indicate that late seral forests can be well distinguished from younger forests using QuickBird spectral and textural data. However, discrimination among late seral forest associations is challenging, especially in the absence of landscape positional variables. Classification accuracies were particularly low for rare forest associations. Given this finding, the objective of the third chapter was to explicitly examine the caveats of using high spatial resolution imagery to map rare classes. Classification accuracy is assessed in several different ways in order to examine the impact on perceived map accuracy. In addition, the effects on habitat extent and configuration resulting from post-classification implementation of a minimum mapping unit are examined. Results indicate that classification accuracies may vary considerably depending on the assessment technique used. Specifically, ignoring the presence of fine-scale heterogeneity in a classification during accuracy assessment falsely lowered the accuracy estimates. Further, post-classification smoothing had a large effect on the spatial pattern of rare classes. These findings suggest that routinely used image classification and assessment techniques can greatly impact mapping of rare classes.

Understanding why organisms possess certain combinations of life-history traits is important to our understanding of how natural selection operates. Combinations of life-history traits evolve in response to the costs of current reproduction to both survival and future reproduction. Reproductive costs have been broadly categorised into two types: 1) survival costs, and 2) potential fecundity costs. As a means of predicting and explaining variation in reproductive investment in lizards and snakes, Shine and Schwarzkopf (1992) attempted to determine the relative importance of the two kinds of costs to individual lifetime fitness (the SS model). They concluded that most lizard species are unlikely to make trade-offs between current and future reproduction (fecundity costs). In this study of a temperate-zone lizard, Elgaria coerulea, I have three main objectives: 1) to provide the first natural history data for a Canadian population of this species, 2) to describe life-history traits for this population, and 3) to formally test the predictions of the SS model and discuss its potential predictive power. Individual Elgaria coerulea occupy relatively small areas, thus minimising costs associated with a long-distance migration. In addition to having limited movement, Elgaria coerulea rely on hiding as one of their main anti-predator strategies, although there is sex-dependent variation in their retreat-site selection. Emergence patterns of male Elgaria coerulea did not change over their reproductive cycle. In contrast, the probability of capturing an adult female in the open steadily increased over the summer. These results suggest that the benefits of emerging from cover outweigh the costa in females, but not males. Annual survival rate of adult females was 44% and juvenile survival rate was 22%. The survival rate of adult males likely fell in between these values, but I was not able to estimate it directly because of small sample sizes. I infer from the female’s relatively high survival rate that the necessity for gravid females to spend more time in the open during gestation does not translate simply to increased mortality. Gravid females have reduced sprint speed and sprint speed was inversely related to the burden of the clutch. Therefore, gravid females presumably could reduce their predation risk by remaining closer to cover than males or juveniles. However, this is not the case; all northern alligator lizards remained close to cover. Thus, the lack of shift in anti-predator behaviour of gravid females may be a result of all Elgaria coerulea relying on crypsis rather than sprinting as an anti-predator defence. I did detect a difference in body coloration. Gravid females had more black pigmentation than males or juveniles. The black pigmentation may help females blend in with their background better than males, thereby reducing predation risk, or help increase their body temperature at a quicker rate. Another important anti-predator strategy in Elgaria coerulea is tail autotomy, and once again I measured variation in this trait between males and females. Gravid females never lose small parts of their tails, perhaps giving them extra time to escape from a predator. Furthermore, recent tail loss was not seen in gravid females during late gestation. By contrast, males were equally likely to autotomise at any time of the year. Females may be less likely than males to lose their tails because of the potential reproductive gain by females with intact tails. Females with intact tails had a higher probability of being reproductive and females with longer tails had larger newborn. Finally, I show that some Elgaria coerulea trade current reproduction for growth. Examination of reproductive costs in Elgaria coerulea revealed problems with incorporating cold-climate reptile species into the SS model. Because cold-climate species spend significant time in hibernation each year they have relatively short interclutch intervals. For these species the SS model predicts that trade-offs between current and future reproduction are more likely. The likelihood of fecundity costs also increases, even that concurrent growth and reproduction may be more prevalent than previously believed, as is evident in Elgaria coerulea. Both of these factors need to be incorporated into the SS model is increase our ability to make predictions about the evolution of reproductive effort in cold-climate species. / Graduate

Satellite imagery such as Landsat has been in use for decades for many landscape and regional scale mapping applications, but has been too coarse for use in detailed forest inventories where stand level structural and compositional information is desired. Recently available high spatial resolution satellite imagery may be well suited to mapping fine-scale components of ecosystems, however, this remains an area of ongoing research. The first goal of this thesis was to assess the capacity of high spatial resolution satellite imagery to detect the variability in late seral coastal temperate rainforests in British Columbia, Canada. Using an object-based classifier, two hierarchical classification schemes are evaluated: a broad classification based on structural (successional) stage and a finer classification of late seral vegetation associations. The finer-scale classification also incorporates ancillary landscape positional variables (elevation and potential soil moisture) derived from Light Detection and Ranging (LiDAR) data, and the relative contribution of spectral, textural and landscape positional data for this classification is determined. Results indicate that late seral forests can be well distinguished from younger forests using QuickBird spectral and textural data. However, discrimination among late seral forest associations is challenging, especially in the absence of landscape positional variables. Classification accuracies were particularly low for rare forest associations. Given this finding, the objective of the third chapter was to explicitly examine the caveats of using high spatial resolution imagery to map rare classes. Classification accuracy is assessed in several different ways in order to examine the impact on perceived map accuracy. In addition, the effects on habitat extent and configuration resulting from post-classification implementation of a minimum mapping unit are examined. Results indicate that classification accuracies may vary considerably depending on the assessment technique used. Specifically, ignoring the presence of fine-scale heterogeneity in a classification during accuracy assessment falsely lowered the accuracy estimates. Further, post-classification smoothing had a large effect on the spatial pattern of rare classes. These findings suggest that routinely used image classification and assessment techniques can greatly impact mapping of rare classes. / Forestry, Faculty of / Graduate