In this thesis, colloidal nanocrystalline silicon (ncSi) capped with allylbenzene (AB) groups, is created using a sol-gel method. This novel material, AB-ncSi, is size separated and its optical, structural, and electrical characteristics are investigated in detail. For optical characterization, the photoluminescence (PL) peak is located for each fraction of the nanoparticles to determine its diameter. The AB-ncSi samples have diameters ranging from 2.89 nm to 7.65 nm. Ellipsometry and scanning electron microscopy (SEM) are used to estimate the film thickness and average distance between the particles, respectively, for structural characterization. No correlation was found between AB-ncSi size and film thickness however the estimated average distance between the particles decreased with decreasing diameter. Finally, for electrical characterization, conductivity of size-separated samples is measured and the temperature dependent conductance is analyzed. The results emerging from these analyses suggest that the charge transport mechanism for AB-ncSi is nearest-neighbor hopping (NNH) albeit VRH is also a potential contributor.

In this thesis, colloidal nanocrystalline silicon (ncSi) capped with allylbenzene (AB) groups, is created using a sol-gel method. This novel material, AB-ncSi, is size separated and its optical, structural, and electrical characteristics are investigated in detail. For optical characterization, the photoluminescence (PL) peak is located for each fraction of the nanoparticles to determine its diameter. The AB-ncSi samples have diameters ranging from 2.89 nm to 7.65 nm. Ellipsometry and scanning electron microscopy (SEM) are used to estimate the film thickness and average distance between the particles, respectively, for structural characterization. No correlation was found between AB-ncSi size and film thickness however the estimated average distance between the particles decreased with decreasing diameter. Finally, for electrical characterization, conductivity of size-separated samples is measured and the temperature dependent conductance is analyzed. The results emerging from these analyses suggest that the charge transport mechanism for AB-ncSi is nearest-neighbor hopping (NNH) albeit VRH is also a potential contributor.

Evidence suggests that the variability in recruitment of adult Pacific salmon is related to smolt survival during the first ocean year. Specifically, the first few weeks and first marine winter may be two critical periods of high mortality during early marine life. Mortality during early marine residency has been attributed to predation and size-dependent factors while high mortality during the first winter may be due to energy deficits and failure to reach a certain size by the end of the growing season. My study assessed factors influencing overwinter mortality and early marine growth in juvenile Chinook salmon (Oncorhynchus tshawytscha) from Marble River, Quatsino Sound, British Columbia. Juvenile salmon were collected during November 2005 and 2006 (fall) and March 2006 and 2007(winter). Mortality rates over the first winter derived from catch per unit effort across seasons ranged between 80-90% in all years. These are the first estimations of overwinter mortality in juvenile Pacific salmon. Fish size distributions showed no evidence of size-selective overwinter mortality between fall and winter fish in either 2005-2006 or 2006-2007. Otolith microstructure analyses showed no significant difference in circulus increment widths during the first four weeks after marine entry. Similarities in increment width indicated that early marine growth did not differ between fall and winter fish during early marine residency in 2006. These observations show that the high overwinter mortality rates of juvenile Chinook salmon in Quatsino Sound are not size-dependent. Total plankton biomass was significantly lower in the winter season but size distribution, gut fullness and energy density data did not show evidence of starvation. No correlation was found between early marine growth, size, energy accumulation and high mortality in Marble River juvenile Chinook salmon during their first ocean winter in Quatsino Sound. Possible factors influencing these high mortality rates may include non size-selective predation, disease, local environmental influences or an as yet unknown source. Future work should continue to focus on understanding the relationship between early marine survival and adult recruitment. The expansion of growth comparisons geographically and chronologically while determining the effects of predatory mortality on juvenile Chinook salmon along the north Pacific continental shelf and beyond are imperative to fully understanding this complex marine life stage. / Graduate

Nanoflagellates were found to be abundant in a coastal area of the northern Bothnian Sea. The maximum concentration of nanoflagellates, approximately 8000 cells ml-1, was observed in July, coinciding with a decrease in the abundance of cyanobacteria. Pigmented and non-pigmented nanoflagellates were approximately equally distributed throughout the year. Most of the identified genera are known as being phagotrophic, independent if autotrophic or not. A non-cyst-forming pigmented flagellate, Ochromonas sp., was isolated and nutritionally characterized. This chrysophycean flagellate was shown to be a mainly heterotrophic organism: Photosynthesis was too poor to support multiplication of the cells, whereas when feeding on bacteria, high growth rates were obtained. The biological function of the photosynthetic apparatus is suggested to be a survival mechanism during poor bacterial conditions. The flagellate grazed bacteria selectively, preferring cyanobacteria and large cells of heterotrophic bacteria, presumably depending on size-selective grazing. Despite higher growth rates of the bacteria in the sea during summer (July) than spring (May), heterotrophic bacteria in the sea was observed to be smaller in the summer. Nanoflagellates showed a maximum in July, and by selective grazing of large bacteria they might have caused the decrease in the average size of the bacteria and the decrease in the abundance of cyanobacteria. During the consumption of bacteria the flagellate was shown to remineralize nutrients at high rates and excrete dissolved free amino acids. Assuming the existence of a protozoan predator-prey chain of several trophic levels, it seems likely that a significant part of the nutrients fixed by primary producers is remineralized in the euphotic zone. Furthermore, data from this work indicate that flagellate activity may be a significant source of dissolved free amino acids, utilizable for the heterotrophic bacteria. / digitalisering@umu

No description available.

A decline in the size of fish within a population is concerning. Large-sized fish are ecologically important and valued for social and economic reasons. Following widespread collapses from angling overharvest, the densities of Walleyes Sander vitreus in Albertas lakes increased rapidly with large-minimum-size limits. Anglers were unhappy, however, as catch rates increased (>1 Walleyes*hour-1) but fish remained small and did not exceed the minimum size limit. The two alternate explanations for the small, yet old Walleyes were either compensatory growth because of high density (stunting) or size-selective mortality (overfishing). Size-selective mortality has evolutionary consequences. Paradoxically, the management solutions for these problems are in opposition (more harvest versus less harvest), and a wrong diagnosis could exacerbate the problem. I used nested hypotheses, and implemented active adaptive management at several Alberta lakes, to diagnose the causal mechanism creating the small fish problem. For inferences on the source of the mortality, I analysed backcalculated growth rates from pelvic fins. Walleyes that had fast-growth to an early maturity, and then subsequent slow-growth, had greater survival. This hockey stick-shaped growth allows for successful reproduction while the Walleyes remain below the minimum size limit, avoiding harvest. Using changes to sport fishing regulations, I then modified angler effort and harvest at four different Alberta lakes to increase or decrease size-selective harvest and Walleye densities. I found that size-selective mortality from angling rapidly truncated the population-size structure. With concerns of evolutionary consequences because of evidence of size selective harvest, I used an age- and size-structured, single-species model, parameterized with data from Albertas Walleye fisheries, to evaluate the selectiveness of various management regulations. I found that the 50-cm minimum size limit used to recover Albertas Walleye populations did indeed select for the hockey stick life history, although this regulation allowed for sustainable populations (>5 Walleyes*hectare-1) and angler effort up to 16 angler-hours*ha-1*year-1. The optimal regulation to reduce life history selection and allow for population sustainability was a 40-50 cm harvest-tag regulation. This regulation reversed the selection for the hockey stick life history, yet produced sustainable fish densities and allowed angler effort up to 30 angler-hours*ha-1*year-1. However, increasing angler-noncompliance reduced the sustainability of this regulation. / Wildlife Ecology and Management

Spray Polyurethane Foam insulation (SPF) kits are currently being marketed and sold to do-it-yourselfers to meet various insulating needs. Like commercial SPF systems, the primary health concern with SPF kits is user overexposure to the isocyanates during product application. The potential health risk associated with SPF applications is driven by several factors including (but not limited to): the toxicity of isocyanates; the potentially high exposure intensity; the quantity of isocyanates used in the process; the enclosed nature of the environment in which the product could be applied; the potentially high exposure duration/frequency; and the limited availability of control measures to reduce agent intensity (e.g., personal protective equipment, dilution ventilation). To better understand the potential hazards associated with the use of SPF kits, the current study was designed to provide an initial characterization of user exposure to airborne particulate during the application process. Specifically, the study would aim to answer the following: * What is the particle size distribution of the aerosol a SPF kit user is exposed to during application? * What is the airborne particle mass concentration a SPF kit user is exposed to during application? To answer these questions, a single commercially available SPF kit was selected for use and a mock residential environment was constructed to support repeated applications of SPF. Size-selective and total dust air sampling were conducted during the applications to determine the particle size distribution and mass concentration of aerosols generated by the selected kit. The particle size distributions developed from the size selective sampling results showed the presence of airborne particulate capable of penetration to the gas exchange regions of the respiratory tract. The average mass median diameter and geometric standard deviation of the particle size distributions were 4.6 µm and 2.7 respectively. The total dust sampling results showed mean airborne concentrations of 10.40 mg/m3. Based on the sampling results the study, personal air monitoring is needed to assess the degree of user exposure to methylene diphenyl diisocyanate (MDI) and to provide information for the selection of exposure control methods.

This study investigates size-selective predation of four groups predaceous aquatic insects: adults and larvae of diving beetles (Dytiscidae), larvae of dragonflies (Odonata) and aquatic true bugs (Heteroptera) using laboratory feeding experiments and relates the results to morphometric data obtained for each predator.

Cross-shore bathymetric evolution in the nearshore zone often leads to threatening consequences such as beach erosion and shoreline retreat that concern the coastal community. A new, comprehensive cross-shore morphodynamic model was developed that can be used to describe and predict these phenomena. The study included both physical and numerical models that were designed to focus on the influence of sediment size characteristics on the cross-shore sediment transport process. For a profile equilibrium timescale, three types of beach profiles with different sediment mixtures were simulated in a small-scale, random-wave flume laboratory using erosive, storm, and accretive wave conditions. Dynamic relationships between the sediment grain sorting and beach profile changes were found to be evident as size-graded sediment fractions tended to relocate to different energetic zones along the cross-shore profiles. Existing phase-averaged wave and circulation models were utilized together with several new intra-wave modules for predicting important hydrodynamic parameters that were validated using the experimental data. A novel, multi-size sediment transport model was formulated to compute individual transport rates of size-graded sediment fractions while accounting for their interaction and non-linear size dependencies. The model was coupled with a new grain sorting model that resolves cross-shore grain sorting and vertical grain lamination. Compared to a traditional modeling approach, the new comprehensive model proved to offer superior modeling accuracy for both profile evolution and sediment grain size change. The use of the model is most advantageous for a condition with intensive grain sorting, a common scenario on a natural beach profile. Equilibrium beach profile is also better simulated by the model as size-graded fractions are predicted to relocate to different zones where they could withstand local hydrodynamics. Other new components that also help improve the modeling capability include the terms for wave-breaking and bed-slope effects, wave-crest sediment flux, and acceleration-induced bottom-shear stress. Besides superior profile modeling accuracy, sediment size characteristics and their spatial and temporal variations are also a useful set of information provided by the new model.

Die Körpergröße ist von großer Bedeutung für die Fitness vieler Tiere, weil sie positiv mit Überleben und Reproduktionserfolg korreliert ist. Große Rogner vieler Fischarten sind fruchtbarer und produzieren Nachkommen von höherer Qualität verglichen mit kleineren Weibchen. Auch für Milchner einiger Fischarten wurde ein Einfluss der Körpergröße auf frühe Lebensstadien nachgewiesen. Der größenabhängige paternale Effekt verglichen mit maternalen Effekten ist weniger gut untersucht. Das Verständnis der Variation im Reproduktionserfolg als Funktion der Körpergröße der Laicher ist wichtig, weil die Fischerei die Durchschnittsgröße des Laicherbestands reduziert. In vorliegender Dissertation wurden in Laborversuchen an Zebrafischen (Danio rerio) größenabhängige paternale und maternale Effekte auf den Reproduktionserfolg und die Auswirkungen größenselektiver Entnahme auf Körperlänge, Reifung und Reproduktionserfolg untersucht. Die Köperlänge und Kondition waren wichtige Determinanten der Reifung bei Zebrafischen. Größere Rogner zeigten höheren Reproduktionserfolg als kleinere Fische und ein signifikanter Einfluss der Milchnerkörperlänge auf die frühen Lebensstadien ihrer Nachkommen wurde dokumentiert. Längere Männchen wurden von Rognern auch bei der Paarung bevorzugt. Die größenabhängigen maternalen und paternalen Effekte waren ausschlaggebend für den erhöhten Reproduktionserfolg von Zebrafischlaichbeständen, die, verglichen mit kleinen Laichern, aus großen oder zufällig zusammengesetzten Individuen zusammengesetzt waren. Die größenselektive Entnahme führte zu phänotypischen und genetischen Veränderungen, die nach Einstellung der experimentellen Befischung persistierten. Das deutet an, dass die durch die Fischerei ausgelöste Evolution schwierig umkehrbar sein könnte. Die Köpergröße ist von überragender Bedeutung in der Reproduktionsbiologie des Zebrafisches und der Schutz großer Laichfische kann wichtig für den Erhalt der Reproduktionskapazität von befischten Beständen sein. / Body size is a fundamentally important trait for fitness in many animal species because it correlates positively with survival and reproductive success. In many fish species, large females exhibit higher fecundity and produce higher quality offspring compared to small females. Similarly, male body size can affect offspring quality and early life-history traits but the importance of these effects to the reproductive biology of fish is poorly studied. The extent to which variation in reproductive success is explained by parental body size is an important research topic because size-selective fishing usually reduces the average size of reproducing adults in a population. In my dissertation, I studied the parental size effects on reproductive success in a model species (zebrafish, Danio rerio). I also studied the effects of size-selective harvesting on body size, maturation and reproductive output. Body size and condition factor were important determinants of the initiation of maturation in zebrafish. Large females were found to have higher reproductive success compared to small females and a significant effect of male body size on early life-history traits was documented. I found that large males were also favored by the females resulting to differential allocation of reproductive resources toward large males. The maternal- and paternal-size effects ultimately led to elevated reproductive success of experimental spawning stocks consisting of large or random-sized individuals compared to spawning stocks consisting of small individuals. Size-selective harvesting induced rapid phenotypic and genetic changes, which persisted after selection was halted. This suggests that fishing-induced changes might be hard to reverse. My results emphasize the importance of body size to the reproductive biology of zebrafish and suggest that protecting large fish might be important to maintain the reproductive potential of exploited fish stocks.