Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 147-166). Also available via the Internet.

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 14, 2010). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Department of Biological Sciences, University of Alberta." Includes bibliographical references.

The harbour land fill in Halmstad has been described in the news as one of the most polluted areas in Halland County based on the a survey from the Swedish environmental protection agency. In order to identify the extent and severity of the situation several environmental investigations have been performed in this area. This report is based on available data from investigations and environmental reports from WSP, Höganäs AB, HEM and Halmstad municipality. This investigation focus on an “Area C” within the land fill where the main land fill material is i.a. slag from a steel work, construction waste, dredge spoil, waste from glass production and a casting shop. Of these material the focus have been on the metal rich slag from the steel work and its possible environmental impact. The environmental exposure of Hg, Pb, Cd, Cr, Zn, Ni, Mo and V have been calculated as an annual load from Area C. Unfortunately the data available for this investigation has not been complete, e.g. slag concentration data with corresponding leachate data was only obtained for one year. The groundwater data and land fill metal concentrations have been measured only once. This made it impossible to investigate e.g. annual variations like ageing effects of the material or weather variations, variation in the properties of the deposed slag material and statistical significance in differences could not be calculated. Further characterisation of the land fill would be worthwhile in order to be able to draw some conclusions. Calculations of the environmental load has been performed based on concentration in the slag, the land fill, the leachate data of the slag and groundwater concentrations. A model has been developed to calculate the weighted land fill metal concentration. The partitioning coefficient, Kd; between soil and liquid has been calculated and used to estimate the environmental load. It was assumed that the groundwater data was the most reliable data, which indicated that the exposure may be higher than from common soil, especially for Pb and Mo. Relating the environmental exposure values with guideline values based on MKM (less sensitive land use)-land using HQ (hazard quotient) indicates a decreasing risk in the order Pb>V>Mo. However, the exposure is well below that from MKM soil which could be assumed, according to Swedish environmental protection agency guideline values, to be an acceptable exposure.

Land surface covers only 30% of the global surface, but contributes largely to the intricacy of the climate system by exchanging water and energy with the overlying atmosphere. The partitioning of incident solar radiation among various components at the land surface, especially vegetation and underlying soil, determines the energy absorbed by vegetation, evapotranspiration, partitioning between surface sensible and latent heat fluxes, and the energy and water exchange between the land surface and the atmosphere. Because of its significance in climate model, land surface model solar radiation partitioning scheme should be evaluated in order to ensure its accuracy in reproducing these naturally complicated processes. However, few studies evaluated this part of climate model. This study examines a land surface solar radiation partitioning scheme, i.e., that of the Community Land Model version 4 (CLM4) with coupled carbon and nitrogen cycles. Taking advantage of multiple remote sensing fraction of absorbed photosynthetically active radiation (FPAR) datasets, ground observations and a unique 28-year FPAR dataset derived from the Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) dataset, we evaluated the CLM4 FPAR’s seasonal cycle, diurnal cycle, long-term trends and spatial patterns. Our findings show the model roughly agrees with observations in the seasonal cycle , long-tern trend and spatial patterns but does not reproduce the diurnal cycle. Discrepancies also exist in seasonality magnitudes, peak value months and spatial heterogeneity. We identified the discrepancy in the diurnal cycle as due to the absence of dependence on sun angle in the model. Implementation of sun angle dependence in a one-dimensional (1-D) model is proposed. The need for better relating vegetation to climate in the model indicated by long-term trends is also noted. Evaluation of the CLM4 land surface solar radiation partitioning scheme using remote sensing and site level FPAR datasets provides targets for future development in its representation of this naturally complicated process. / text

The rate of carbon turnover in soil is a balance between the input of carbon by plants through their roots and associated fungi and the loss of carbon due to plant and microbial respiration, oxidation and leaching. Soil carbon dynamics are notoriously difficult to measure, and being able to separate total soil respiration into its autotrophic and heterotrophic components would help understanding of carbon cycling processes. Where autotrophic respiration originates from roots and their associated mycorrhizal fungi, using newly fixed carbon, and heterotrophic respiration originates from the breakdown of older soil organic matter. By calculating the δ¹³C signature of respired CO₂ (the ratio of the abundances of C isotopes ¹²C and ¹³C) it is possible to determine whether it is of heterotrophic or autotrophic origin. In this study a 6 chamber, constant CO₂ concentration measuring apparatus was developed to determine both the rate of CO₂ efflux and to collect undisturbed CO₂ samples for isotope analysis. This apparatus was tested using live soil samples with different δ¹³C values (-22 ‰ to -27 ‰) and respiration rates (2 – 8 µmol m⁻² s⁻¹) obtained from various locations in New Zealand. Testing involved taking samples using the respiration apparatus, then incubating the same samples in a bag, and then comparing the two. There was no difference between the results from the soil respiration apparatus and the bags (R²=0.96, p=0.0002). Twelve microcosms including soil and grass were extracted from a newly converted dairy farm and placed into in growth cabinets. Diurnal courses of partitioned soil respiration were made over 24 hours with constant soil temperature to eliminate temperatures effect on soil respiration. Half were then covered with 90% shade cloth for 12 days to test if a reduction in light (and therefore newly fixed carbon) would have any effect on soil respiration. There was a significant reduction in soil respiration, yet no detectable change in the δ¹³C of soil respired CO₂ under heavily shaded treatment. There was however there was a shift towards heterotrophic dominated respiration. This shows that while L. perenne is resilient to surrounding conditions it is susceptible to change if exposed to different conditions for prolonged periods of time. The use of this new technique in the field will allow improved understanding of factors effecting soil C efflux.

The angiosperm order Malpighiales includes \(\sim 16,000\) species and constitutes up to 40% of the understory tree diversity in tropical rain forests. Despite remarkable progress in angiosperm phylogenetics during the last 20 years, relationships within Malpighiales have remained poorly resolved, possibly due to its rapid rise during the mid-Cretaceous. Using phylogenomic approaches, including analyses of 82 plastid genes from 58 species, we identified 12 new clades in Malpighiales and substantially increased resolution along the backbone (Chapter 1). This greatly improved phylogeny revealed a dynamic history of shifts in net species’ diversification rates across Malpighiales, with bursts of diversification noted in the Barbados cherries (Malpighiaceae), cocas (Erythroxylaceae), and passion flowers (Passifloraceae). We also found that commonly used a priori approaches for partitioning data in similar large-scale analyses, by gene or by codon position, performed poorly relative to the use of partitions identified a posteriori using a Bayesian mixture model. Another aspect of my thesis focused on investigating horizontal gene transfer (HGT) in Malpighiales. Recent studies have suggested that plant genomes have undergone potentially rampant HGT. Parasitic plants have provided the strongest evidence of HGT, which appears to be facilitated by the intimate physical association between the parasites and their hosts. Using phylogenomic approaches, we analyzed the nuclear transcriptome (Chapter 2) and mitochondrial genome (Chapter 3) of the holoparasite Rafflesiaceae, which represents an enigmatic subclade of Malpighiales. Our analyses show that several dozen actively transcribed nuclear genes, and as many as 34–47% of its mitochondrial gene sequences, show evidence of HGT depending on the species. Some of these HGTs appear to have maintained synteny with their donor and recipient lineages suggesting that vertically inherited genes have likely been displaced via homologous recombination, as is common in bacteria. Finally, our results establish for the first time that although the magnitude of HGT involving nuclear genes is appreciable in these parasitic plants, HGT involving mitochondrial genes is substantially higher. Moreover, the elevated rate of unidirectional host-to-parasite gene transfer raises the possibility that HGTs may provide a fitness benefit to Rafflesiaceae for maintaining these genes.

I quantified the bat assemblage associated with a Sonoran Desert riparian corridor at a wildland-urban interface using mist netting (2002-2005) to assess differential spatial and temporal resource use. My capture rate was high (17 species and 961 individuals) considering the aridity of the area; however, landscape complexity of this montane region undoubtedly contributes to foraging opportunities. I found that bats were distributed along the canyon when water was plentiful but their activity was concentrated at isolated pools during dry periods. I also found temporal variation in pool-use by the most frequently captured species. I conducted an acoustic study to measure bat-use between deciduous riparian and Sonoran desertscrub communities. I measured activity levels using number of acoustic call files. I found greater bat foraging in desertscrub and used a multidisciplinary approach to determine why bats might use the more arid environment. All capture data and supporting analyses are included in appendices.

Precipitation, more than any other environmental factor, controls patterns of ecosystem production and biogeochemical cycling in arid and semiarid environments. Growing-season rains in these regions are highly unpredictable as they come in intermittent pulses varying in size, frequency and spatial extent, thereby producing unique hydrological patterns that constrain the location and residence time of soil water available for biological activity. In order to understand how arid and semiarid ecosystems respond to inputs of precipitation within the context of ecosystem science and global change studies, knowledge is needed on how plants and other organisms respond as an integrated system to such environmental control. The focus of my research was to understand how the distribution of precipitation events influences the dynamics of carbon cycling in semiarid ecosystems. At a semiarid riparian woodland, measurements of CO2 exchange and evapotranspiration revealed that following precipitation events occurring soon after prolonged dry periods the efficiency of rain-use (amount of carbon gain per unit of precipitation over a specific period time) was low. Precipitation did not readily stimulate primary productivity, water was mainly lost as soil evaporation and large respiratory CO2 effluxes were observed. This commonly observed features in seasonally dry ecosystems might have profound consequences for the seasonal and annual carbon balance. In this woodland, 47% of the precipitation within a single growing season (May-October) was returned to atmosphere as soil evaporation and the CO2 efflux observed just during the first rainy month (July) was equivalent to almost 50% of the net carbon gain observed over the six-month growing season. Results from experimental irrigations in understory plots of riparian mesquite woodland revealed that the magnitude and duration of the large CO2 fluxes occurring soon after rainfall was higher in plots located under tree canopies where, relative to intercanopy plots, the amount of plant litter was higher, soil evaporation and plant photosynthetic rates were lower. Efficiency of rain-use in semiarid ecosystems during the growing season apparently was determined by the degree of coupling between gross photosynthesis and ecosystem respiration, by the fraction of precipitation lost as soil evaporation and by the water-use efficiency of the component vegetation.

WiMax or the IEEE 802.16 standard is one of the most promising broadband wireless technologies nowadays. It is characterized by its high data rates, large coverage area, flexible design and QoS support. The standard defines two modes of operation: Point-to- Multi-Point (PMP) and the Mesh Mode. In the first mode, all nodes are connected directly to the base station and communication is not allowed amongst nodes. In the mesh mode, nodes are placed in an ad hoc manner communicating to neighbors and relaying the traffic of other nodes. The goal of this thesis is to design a partitioning scheme for the frame structure of the Mesh mode. Increasing the frame utilization would result in better support for QoS applications and optimized resource allocation, and thus revenue increase from the service provider’s perspective. The mesh frame is divided into control and data, which are further divided into centralized and distributed portions. We propose a novel and efficient scheme for partitioning the data subframe between the two schedulers. We use a Markovian model that studies the system behavior in the long run, and provides predictions based on analysis of previous window of frames. We further enhance the decision by tuning the partitioning through statistical analysis of smaller windows to accommodate demand changes. Our simulations show that the proposed scheme achieves high utilization under different network and traffic conditions and decreases the packet overflow. / Thesis (Master, Computing) -- Queen's University, 2008-10-02 18:41:36.551

Abstract Isobaric (200 MPa) experiments have been performed to investigate the effects of H2O alone or in combination with P, S, F or Cl on the phase relations and elemental and oxygen isotopic partitioning between immiscible silicate melts in the systems Fe2SiO4-Fe3O4-KAlSi2O6-SiO2, Fe3O4-KAlSi2O6-SiO2 and Fe3O4-Fe2O3-KAlSi2O6-SiO2 +/- plagioclase (An50). Experiments were heated in a newly-designed rapid-quench internally-heated pressure vessel at 1075, 1150 or 1200 oC for 2 hours. Water alone or in combination with P, S, or F significantly increases the temperature and composition range of two-liquid fields at fO2= NNO and MH buffers. Water-induced suppression of liquidus temperatures, considered with the effects of pressure on two-liquid fields stability in silicate melts, suggests that liquid phase separation may occur in some volatile-rich silicate magmas at pressures up to 2GPa. Two-liquid partition coefficients for Fe, Si, P and S correlate well with the degree of polymerization of the SiO2-rich conjugate melts and the data can be applied to assess the involvement of liquid-phase separation in the genesis of coexisting volatile-rich magmas. The partitioning of trace concentrations of selected HFSE, REE and transition elements between immiscible experimental volatile-rich melts at 1200 oC, 200 MPa has been determined at QFM, NNO and MH oxygen buffers. Water generally increases the partitioning of HFSE, REE and transition elements into the Fe-rich melt. Water alone, or combined with P or S, produces nearly parallel partitioning trends for HFSE and REE. Absolute partitioning values of transition elements are strongly dependent on the network-modifier composition of the melt. 18O in experimental immiscible melts with H2O or H2O and P or S partitions preferentially into the felsic conjugate melt (δ18O felsic melt- δ18O mafic melt values range from 0.4 to 0.8 permil) consistent with observations in anhydrous immiscible silicate melts. The expansion of the P-T-X-fO2 stability ranges of two- or three-liquid fields observed in the experimental melts demonstrates that liquid-immiscibility may be an important process in the evolution of some volatile-rich natural magmas. The results support an immiscible petrogenetic origin for some iron-oxide dominated, Kiruna-type, ore-deposits. / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2012-04-10 15:06:35.797