This work detailed the physical and chemical characterization of oil water mixtures prepared using fresh and weathered Macondo related oils under different conditions of mixing energy/time and in the presence/absence of chemical dispersants. The results indicated that WAFs produced consistent, droplet free solutions for both source and weathered oils with concentration ranges that represented the soluble components of the oil used. Chemically enhanced WAFs prepared with the source oil generated a large amount of micron-size droplets; however the viscosity of the weathered oils were a limiting factor for the preparation of CEWAFs with weathered oils. Droplet size distributions were influenced by the amount of energy in the system and the oil weathering stage, when high energy WAFs were made the increase in weathering of the oil resulted in the formation of smaller droplets that were more stable over time.

Earth's species are disappearing at a rate unprecedented in human history, yet whether this loss will make the ecosystem "services" that support our civilisation more vulnerable to environmental change is poorly understood. This thesis investigates two different aspects of land surface modelling. It firstly models the role of biodiversity in ecosystem resilience using the Lotka-Volterra and single resource models to model diversity using competition coeffcients, stochastic noise and evolution inspired trait diffusion and then examines if higher diversity makes these simple models more resistant to temperature increases. It secondly develops a theoretical plant demography model, based on the continuity equation, to robustly represent forest size diversity. This avoids both the complexity and maintainability issues seen in Forest Gap models and improves the representation of land use and land cover change and of regrowth time-scales after disturbance, which can be unrealistic in some of the previous generation of Dynamic Global Vegetation Models (DGVMs), such as TRIFFID (Cox et al., 2001). While the Lotka-Volterra with competition coeffcients and the single resource with stochastic noise approaches are found to be impractical, the single resource model with trait diffusion successfully shows that higher diversity requires a faster critical rate of temperature change before system net primary productivity (NPP) collapses. The continuity equation model of vegetation demography is solved analytically with the size dependence of the growth rate approximated first by a power law and then with a quadratic. The power law solution can be reduced to a "self-thinning" trajectory, and the quadratic solution gives either a rotated sigmoid or 'U-shape' distribution of plant sizes, depending on the ratio of mortality to maximum growth gradient. The model is then extended to produce the basis of a new Dynamic Global Vegetation Model (DGVM) called "Robust Ecosystem Demography" (RED), adapting the plant physiology from TRIFFID DGVM to generate a size-dependent growth function. A proportion of the NPP from this growth is used for reproduction and the shading is modelled simply by random overlap. The model is found to better represent regrowth time-scales compared to TRIFFID and is also found to demonstrate an optimum proportion of NPP to reproduction which decreases with plant lifetime.

No description available.

The structure of phytoplankton communities was examined seasonally across five rivers with a focus on small cells and their relative importance. Picophytoplankton (0.2-2 μm), previously considered insignificant in rivers, reached densities as high as those observed in lakes and oceans (~ 10e4-10e5 cells/mL). Their relative importance was not a function of trophic state with the highest contribution to algal biomass found in the most eutrophic river. Body size distributions were analyzed from both chlorophyll-a size fractions and taxonomic enumerations; no significant effect of river or season was detected, suggesting that phytoplankton size distribution is not a useful metric of change in rivers. Unlike lake ecosystems, the rivers were uniformly dominated by small cells (< 20 μm). Taxonomic analyses of the seasonal succession did not reveal a common periodicity of particular divisions (e.g. diatoms). However, strong dominance was more typical of eutrophic rivers even though taxa richness was similar.

The Dungeness crab (Cancer magister Dana) trap fishery in British Columbia has been regulated by a minimum legal size limit of 165 mm spine-to-spine carapace width (CW, 154 mm notch-to-notch CW) since early this century. Evaluation of the size limit by yield- and eggs-per-recruit analyses has been precluded by a lack of information on basic population variables such as growth, mortality, movement and mating behavior. Information on these variables was obtained in an intensive two year study of the Dungeness crab fishery near Tofino, B.C. from April 1985 until March 1987. A cohort of pre-recruit males and females was followed as the males entered the fishery and were subsequently exploited, yielding information on moult increments-at-size , length of intermoult periods, size-at-maturity, size of mating pairs, mortality, movement, commercial fishing success and exploitation rates. Male C .magister entered the fishery during their fourth year after settlement. Size frequency analysis revealed that nearly all legal-sized (>154 mm notch-to-notch CW) males are within the 155.0±11.2 mm instar (≈50% of this instar). Sublegal-sized males in this instar have a high annual natural mortality rate (M=2.8-4.5), hence a low probability (<10%) of surviving to legal size. Legal-sized males have a high annual fishing mortality rate (F=5.1-6.9). Consequently, a small component of the commercial catch is composed of males in larger instars. Despite females not being landed, the negative slope of female catch curves from four regional fisheries was steepest for the most heavily fished region and shallowest for the most lightly fished region. Females mate after moulting while accompanied by a larger male, and in a heavily fished population larger males may be absent. Thus, the catch curves suggested the possibility of reduced mating and moulting, and consequently fewer large females, in heavily fished populations. Yield-per-recruit analysis suggests landings might be markedly improved by lowering the minimum legal size limit. However, eggs-per-recruit analysis, which modeled the possible consequences of removing large males, suggests that for a heavily fished population the current size limit may result in up to a 50% decline in population egg production relative to an unfished population. The historical presumption that the current minimum legal size limit for males does not impact on population egg production should be reconsidered. To facilitate calibration of trap samples biased by differences in soak times, parameters for models describing changes in bait effectiveness over time, and agonistic interactions between crabs within a trap and those attempting to enter that trap, were estimated. Parameter estimates were obtained by simulating the entry and exit of crabs into and out of traps based on experiments which (1) emphasized the above two processes, and (2) estimated the daily probabilities of crabs of different sizes escaping traps. / Science, Faculty of / Zoology, Department of / Graduate

In 2005 and 2010, high sea surface temperatures caused widespread coral bleaching on Jamaica’s north coast reefs. Three shallow (9m) reef sites were surveyed during each event to quantify the prevalence and intensity of coral bleaching. In October 2005, 29-57% of the colonies surveyed were bleached. By April 2006, 10% of the corals remained pale/partially bleached. Similarly, in October 2010, 23-51% of corals surveyed at the same sites were bleached. By April 2011, 12% of the colonies remained pale/partially bleached. Follow-up surveys revealed low coral mortality following both events, with an overall mean of 4% partial colony mortality across all species and sites observed in April 2006, and 2% in April 2011. Mixed effects models were used to quantify the relationship between colony size and (a) bleaching intensity, and (b) bleaching related mortality among coral species. The bleaching intensity model explained 51% of the variance in the bleaching response observed during the two events. Of this 51%, fixed effects accounted for ~26% of the variance, 17% of which was attributed to species-specific susceptibility to bleaching , 5% to colony size, <1% colony morphology and 4% to the difference in bleaching intensity between the two events. The random factor (site) accounted for the remaining ~25% of the variance. The mortality model explained 16% of the variance in post bleaching mortality with fixed effects, including colony size, morphology and species explaining ~11% of the variance, and the random effect (site) explaining 5%. On average, there was a twofold difference in bleaching intensity between the smallest and the largest size classes. Modelling the relationship between colony level characteristics and site-specific environmental factors on coral species’ susceptibility to thermal stress can shed light on community level responses to future disturbances.

The main goal of the thesis is to assess factoring as a tool for small and medium size enterprises financing. Factoring offers receivables management, securing of debtors risk and support of national and international trade. The target is to sum up theoretical approaches in Czech as well as international literature and connect them with practice knowledge and experience that the author have learned during expert experience. Factoring was successfully offered in course of bad economic times during worldwide recession mainly to due easy availability in the markets. Financing via factoring expresses lower risk for financing party, due to transaction risk spread being on the more debtors. In contrast, there is higher demand on administration of every single invoice of company to its debtors. This logically brings higher cost of manpower on the financing party site that has to deal with high proportion of invoices. The thesis is divided into five parts. First parts is taking care about state and private trade supporting tools including Czech Export Bank and its role in creating space for national exporters. Second part deals with forms, in which small and medium size enterprise can find the suitable financial tools and products. Receivables and its main features, receivables live cycle and tools for effective use of receivable in asset based financing, that is all proceeded in part with number three. Whereas chapter four analyze current latest experience with factoring, its forms and way of use including legal and accountancy view. Fifth chapter summarizes theoretical background and uses the application of theory in practice and presents examples, how factoring can help. The thesis found out, that factoring is a suitable financing tool in times of economic crisis and general downturn. The number of factoring transaction grew, as well as the total turnover, but average transaction price went down due to lower cost of traded goods, that was financed via factoring. Thesis also proved that factoring financing is easy to get in the market, as there is large scale of big and small factoring financing providers. Factoring did not improve all significant financial ratios, but increased turnover of assets, mainly receivables, decreased the ratio of indebtedness. Thesis introduced the factoring financing, its use, forms and pros as well as cons. Factoring provided to be sufficient substitute for conventional credit, but bears differences, that have to be taken into account, when deciding on suitable form of receivable financing.

In the 20th century, we were witnesses an unprecedented growth of public expenditure across all the developed countries of the world. With this phenomenon was created a hypothesis about the negative impact of public expenditure on economic growth and in response to it, economists did many studies which tried to verify this negative effect. In the 80ties the first studies which confirmed the negative linear dependence of these two macroeconomic aggregates. It means greater public sector has negative impact to economic growth of countries. In the 90ties the studies which verify the nonlinear dependence of the inverted U-shaped curve with a peak where is the optimal size of public sector. This concept is collectively called "Armey curve" or "BARS curve" and my final thesis deals by this concept and my goal is to introduce BARS concept to Czech readers. It reflects the evolution of public expenditure in the 20th century and describes the theoretical and empirical development of the whole concept until now. It means a hypothesis about the positive benefits of government activities in the economy to a certain point - "optimal point" and the negative after this point. The final thesis also offers custom research on a sample of the Visegrad Four countries in years from 1995 to 2012. The aim of the research is to verify the linear dependence of growth of GDP and the share of public expenditure in GDP and the existence BARS curve and the optimal size of public spending across countries.

We address the problem of stochastic simulation of soil particle-size curves (PSCs) in heterogeneous aquifer systems. Unlike traditional approaches that focus solely on a few selected features of PSCs (e.g., selected quantiles), our approach considers the entire particle-size curves and can optionally include conditioning on available data. We rely on our prior work to model PSCs as cumulative distribution functions and interpret their density functions as functional compositions. We thus approximate the latter through an expansion over an appropriate basis of functions. This enables us to (a) effectively deal with the data dimensionality and constraints and (b) to develop a simulation method for PSCs based upon a suitable and well defined projection procedure. The new theoretical framework allows representing and reproducing the complete information content embedded in PSC data. As a first field application, we demonstrate the quality of unconditional and conditional simulations obtained with our methodology by considering a set of particle-size curves collected within a shallow alluvial aquifer in the Neckar river valley, Germany.

Research pertaining to the distortion of the squared canonical correlation coefficient has traditionally been limited to the effects of sampling error and associated correction formulas. The purpose of this study was to compare the degree of attenuation of the squared canonical correlation coefficient under varying conditions of score reliability. Monte Carlo simulation methodology was used to fulfill the purpose of this study. Initially, data populations with various manipulated conditions were generated (N = 100,000). Subsequently, 500 random samples were drawn with replacement from each population, and data was subjected to canonical correlation analyses. The canonical correlation results were then analyzed using descriptive statistics and an ANOVA design to determine under which condition(s) the squared canonical correlation coefficient was most attenuated when compared to population Rc2 values. This information was analyzed and used to determine what effect, if any, the different conditions considered in this study had on Rc2. The results from this Monte Carlo investigation clearly illustrated the importance of score reliability when interpreting study results. As evidenced by the outcomes presented, the more measurement error (lower reliability) present in the variables included in an analysis, the more attenuation experienced by the effect size(s) produced in the analysis, in this case Rc2. These results also demonstrated the role between and within set correlation, variable set size, and sample size played in the attenuation levels of the squared canonical correlation coefficient.