I rinnande vatten, så som bäckar och åar, har Gammarus pulex en viktig ställning i näringsväven. Arten bidrar till att bryta ner organiskt material och göra energin i detta tillgänglig för andra organismer. G. pulex är dessutom en viktig föda för ett stort antal predatorer. Flera studier visar att G. pulex reagerar på olika temperaturer. Tillväxthastighet, livslängd, reproduktion, aktivitet och syreförbrukning är exempel på karaktärer som påverkas av temperaturen. Ingen studie har tidigare behandlat om anläggningen av exokutikula påverkas av temperaturen. En höjd temperatur ökar tillväxthastigheten och detta skulle kunna ge minskade resurser till generering av exokutikula, såkallad ”trade off”. Min studie syftar till att undersöka hur G. pulex tvingas fördela sina resurser mellan tillväxt och exokutikulans tjocklek i förhållande till förändrade temperaturförhållande. Till undersökningen användes 80 djur från två naturliga system med en genomsnittlig temperaturskillnad på 1,9ºC. Säsongsvariation mellan höst och vinter studerades utifrån samma lokaler. Exokutikulans tjocklek mättes och kroppslängden användes som storleksreferens. Statistisk analys gjordes av kvoten exokutikulatjocklek/kroppslängd och ingen signifikant skillnad hittades mellan de olika grupperna. Denna studie visar att ingen ”trade off” finns mellan exokutikulans tjocklek och tillväxt hos G. pulex, varken i de två systemen, eller p.g.a. säsongsvariation, höst och vinter. Detta kan bero på Amfipoders möjligheter att återanvända kalcium för uppbyggnad av en ny exokutikula samt eventuell god tillgång på resurser. Dessutom ger en höjd metabolism vid ökad temperatur ökade möjligheter till en snabb generering av en ny exokutikula. Vidare studier bör göras i både naturliga och artificiella miljöer för att vidare undersöka en eventuell ”trade off” mellan tillväxt och exokutikula.

I studied nest characteristics, breeding dispersal, and nest defence behaviour of Northern Flickers (<i>Colaptes auratus</i>, hereafter flickers) in central interior British Columbia with respect to nest predation. My research focused on three questions: (1) Are there nest characteristics associated with the risk of nest predation and nest loss to European Starlings (<i>Sturnus vulgaris</i>)? (2) Does nest predation influence breeding dispersal? (3) Do parental attributes influence nest defence behaviour? <p> An examination of flicker nest-site characteristics at five spatial scales revealed that nests were safer from mammalian predators (N=81) when they were higher, concealed by vegetation, farther from continuous coniferous forest blocks, and contained fewer conifers within the nesting clump. Proximity to conifers increased predation risk, but nests safe from competitors (N=18) were closer to coniferous forest blocks and contained a higher percentage of conifers in the nesting clump. Flickers face a trade-off between being safe from predators and safe from competitors. <p> Nesting success did not influence between-year breeding dispersal by 159 male or 76 female flickers. Because nests and forest clumps were not predictably safe from predators, benefits of dispersing likely outweigh costs. Other factors such as mate-switching, nest ectoparasites, and a fluctuating food source may play larger roles in dispersal than nest predation. Within years, 73% of pairs switched nest sites after their first attempt failed due to predation (N=37); however, there was no reproductive advantage for these pairs compared to pairs that remained at their original nest. Stressful encounters with predators involving nest defence may trigger dispersal, although it seems to offer no greater nest success. Of 24 flicker pairs presented with a control model before egg-laying, 3 pairs abandoned their nest, whereas 4 out of 24 pairs presented with a squirrel model abandoned their nest. This suggests that a one-time encounter with a nest predator is not a sufficient deterrent against continued nesting. Rather, costs of finding and excavating or renovating a new cavity may cause individuals to tolerate some risk in nesting at a location with an active predator. <p> In experimental trials (N=94), intensity of nest defence behaviour against a model predator was not related to the sex, age, body size, and body condition of the defending adult(s). The sexes may have behaved similarly because they are similar in size and have similar survival patterns. Costs and benefits of nest defence for flickers of different ages may also be equal because flickers are relatively short-lived and their survival rate is not linked with age. Brood size of the defending adult was also unrelated to the intensity of nest defence. If flickers have adjusted their clutch size in relation to the number of young for which they can optimally provide care, then no effects of brood size on nest defence behaviour should be recorded, as was the case here.</p>

Employing a design solution can satisfy some requirements while having negative side-effects on some other software requirements and project objectives. Ultimately, selecting a design solution among multiple options involves making trade-offs among competing requirements. These trade-offs, especially at the early stages of software development, are often hard to identify or quantify, and can be subjective. Security is one critical requirement among many, which can cause critical trade-offs and severe costs. Damages from security attacks can be overwhelming and the costs increase every year. The threat of vulnerabilities and their exploitation by potential adversaries calls for careful analysis of security risks and trade-offs that security solutions impose, from the viewpoints of both defenders and attackers. Since software developers and analysts are usually not security experts, detecting potential threats within software systems can be problematic. Even when threats are known, the risk factors, either the probability of a successful attack or the resulting damage of a successful attack, are not always known or numerically measurable. In this situation, selecting proper security solutions can be challenging, when mitigating impacts and side-effects of solutions are often not quantifiable. This thesis addresses such challenges in identifying and making trade-offs among security and other system requirements and stakeholders' goals. This work introduces a framework for identifying and modeling security risks and requirements trade-offs. The central idea in this thesis is analyzing security requirements on the basis of predicting software vulnerabilities, weaknesses or flaws that can be exploited to break into the system. Vulnerabilities and exploitation scenarios are specified within goal-oriented requirements models of the system. This approach enables analysis of vulnerability exploitations and their impacts on the running system. The structure of goal-oriented security requirements models enables tracing the ultimate impacts of the exploitations on high-level goals of stakeholders and design objectives. In order to evaluate the risk of vulnerabilities, this framework intertwines the Common Vulnerability Scoring System (CVSS) with security requirements risk assessment. The proposed framework provides a decision aid method that takes into the account risks, competing requirements, security solutions, their impacts on risks, and their side-effects on other requirements, to aid decision makers to select a solution among alternative security solutions. The proposed decision analysis method helps analysts to make requirements trade-offs systematically, in the absence of quantitative data, or when a mixture of both quantitative and qualitative data are available.

A common problem encountered in mobile hydraulics is the desire to automate motion control functions in a restricted-cost and restricted-sensor environment. In this thesis a solution to this problem is presented. A velocity control scheme based on a novel single component pressure compensated ow controller was developed and evaluated. <p> The development of the controller involved solving several distinct technical challenges. First, a model reference control scheme was developed to provide control of the valve spool displacement for a particular electrohydraulic proportional valve. The control scheme had the effect of desensitizing the transient behaviour of the valve dynamics to changes in operating condition. Next, the pressure/flow relationship of the same valve was examined. A general approach for the mathematical characterization of this relationship was developed. This method was based on a modification of the so-called turbulent orifice equation. The general approach included a self-tuning algorithm. Next, the modified turbulent orifice equation was applied in conjunction with the model reference valve controller to create a single component pressure compensated flow control device. This required an inverse solution to the modified orifice equation. Finally, the kinematics of a specific single link hydraulically actuated mechanism were solved. Integration of the kinematic solution with the flow control device allowed for predictive velocity control of the single link mechanism.

A common problem encountered in mobile hydraulics is the desire to automate motion control functions in a restricted-cost and restricted-sensor environment. In this thesis a solution to this problem is presented. A velocity control scheme based on a novel single component pressure compensated ow controller was developed and evaluated. <p> The development of the controller involved solving several distinct technical challenges. First, a model reference control scheme was developed to provide control of the valve spool displacement for a particular electrohydraulic proportional valve. The control scheme had the effect of desensitizing the transient behaviour of the valve dynamics to changes in operating condition. Next, the pressure/flow relationship of the same valve was examined. A general approach for the mathematical characterization of this relationship was developed. This method was based on a modification of the so-called turbulent orifice equation. The general approach included a self-tuning algorithm. Next, the modified turbulent orifice equation was applied in conjunction with the model reference valve controller to create a single component pressure compensated flow control device. This required an inverse solution to the modified orifice equation. Finally, the kinematics of a specific single link hydraulically actuated mechanism were solved. Integration of the kinematic solution with the flow control device allowed for predictive velocity control of the single link mechanism.

Oligodendrocytes (OLs) are the glial cells responsible for the synthesis and maintenance of myelin in the central nervous system. Recently, Hoxa2 was found by our laboratory to be expressed by OLs and down-regulated at the terminal differentiation stage during oligodendrogenesis in mice (Nicolay et al., 2004b). To further investigate the role of Hoxa2 in oligodendroglial development, a tetracycline regulated controllable expression system was utilized to establish two stable cell lines where the expression level of Hoxa2 gene could be up-regulated (CG4-SHoxa2 [sense Hoxa2]) or down-regulated (CG4-ASHoxa2 [Antisense Hoxa2]) in CG4 glial cells. Morphologically, no obvious differences were observed between CG4-SHoxa2 and CG4 wild-type cells, whereas CG4-ASHoxa2 cells exhibited much shorter processes compared with those of CG4 wild-type cells. Data from BrdU uptake assays indicated that an up-regulation of Hoxa2 gene promoted the proliferation of CG4-SHoxa2 cells. PDGF&alphaR (Platelet-derived growth factor [PDGF] receptor alpha), a receptor for the mitogen PDGF that enhances the survival and proliferation of OLs, was assessed at the mRNA level in both CG4 and CG4-SHoxa2 cells, but no significant differences were observed between Hoxa2 up-regulated cells and wild-type CG4 cells with respect to the mRNA level of PDGF&alphaR. In addition, specific investigations of the differentiation of CG4-SHoxa2 cells were carried out by characterizing the composition of stage specific oligodendroglial subpopulations in culture. Our immunocytochemical study did not indicate the differentiation course of the genetically engineered cells was significantly altered compared to CG4 wild-type cells, although results from semi-quantitative RT-PCR of oligodendrocyte-specific ceramide galactosyltransferase (CGT) and myelin basic protein (MBP) indicate that the differentiation of CG4-SHoxa2 cells was delayed when Hoxa2 gene was up-regulated.

Employing a design solution can satisfy some requirements while having negative side-effects on some other software requirements and project objectives. Ultimately, selecting a design solution among multiple options involves making trade-offs among competing requirements. These trade-offs, especially at the early stages of software development, are often hard to identify or quantify, and can be subjective. Security is one critical requirement among many, which can cause critical trade-offs and severe costs. Damages from security attacks can be overwhelming and the costs increase every year. The threat of vulnerabilities and their exploitation by potential adversaries calls for careful analysis of security risks and trade-offs that security solutions impose, from the viewpoints of both defenders and attackers. Since software developers and analysts are usually not security experts, detecting potential threats within software systems can be problematic. Even when threats are known, the risk factors, either the probability of a successful attack or the resulting damage of a successful attack, are not always known or numerically measurable. In this situation, selecting proper security solutions can be challenging, when mitigating impacts and side-effects of solutions are often not quantifiable. This thesis addresses such challenges in identifying and making trade-offs among security and other system requirements and stakeholders' goals. This work introduces a framework for identifying and modeling security risks and requirements trade-offs. The central idea in this thesis is analyzing security requirements on the basis of predicting software vulnerabilities, weaknesses or flaws that can be exploited to break into the system. Vulnerabilities and exploitation scenarios are specified within goal-oriented requirements models of the system. This approach enables analysis of vulnerability exploitations and their impacts on the running system. The structure of goal-oriented security requirements models enables tracing the ultimate impacts of the exploitations on high-level goals of stakeholders and design objectives. In order to evaluate the risk of vulnerabilities, this framework intertwines the Common Vulnerability Scoring System (CVSS) with security requirements risk assessment. The proposed framework provides a decision aid method that takes into the account risks, competing requirements, security solutions, their impacts on risks, and their side-effects on other requirements, to aid decision makers to select a solution among alternative security solutions. The proposed decision analysis method helps analysts to make requirements trade-offs systematically, in the absence of quantitative data, or when a mixture of both quantitative and qualitative data are available.

Syftet med denna studie är att utifrån teoretiska ansatser och tidigare forskning som rör kapitalstruktur, visa om de tre valda finansiella företagsegenskaperna förklarar kapitalstrukturen i små onoterade svenska företag. De teoretiska ansatser som testas är främst pecking-order och trade-off. En kvantitativ ansats har använts i uppsatsen där sex hypoteser bildats utifrån de teoretiska ansatserna. Uppsatsen är av positivistisk karaktär och har en deduktiv ansats. Analysen baseras på både enkla och multipla regressionsanalyser av nyckeltal som beräknades från material som hämtats i årsredovisningar från de 220 utvalda företagen. Samtliga av de utvalda företagen slumpades fram från en lista över små företag som ej är registrerade på någon börslista. Resultaten indikerar att de teoretiska ansatserna som utformats för att förklara kapitalstrukturen i stora företag inte förklarar densamma för svenska små företag. Det finns samband som stödjer de teoretiska ansatserna och hypoteserna men förklaringsgraderna för de finansiella företagsegenskaperna i relation till skuldsättningen i företagen påvisar att sambanden är svaga. / The purpose of this study is to use theoretical approaches and previous research related to capital structure to show if the three selected firm characteristics explain the capital structure of small unlisted Swedish firms. The theories that are tested are primarily Pecking-order theory and the Trade-off theory. A quantitative approach has been used in our thesis where six hypotheses are formed according to the theoretical approaches. The thesis has a positivistic research philosophy and a deductive approach. The analysis is based on both simple and multiple regression analyzes that were calculated from the material obtained in the annual reports of the 220 selected firms. All of the selected firms were randomly chosen from a list of small businesses that are not listed on any exchange list. The results indicate that the theoretical approaches developed to describe the choice of capital structure of large firms do not explain the same for Swedish small businesses. However, there are relationships that support the theoretical approaches and hypotheses, but the coefficient of determination for the explanatory firm characteristics related to small firms leverage indicate that the correlation is weak. The study provides a snapshot of the relationship between leverage and the selected explanatory firm characteristics: asset structure, profitability and growth, based on firms´ annual reports for the year 2011.

An experimental study of condensate was performed by exposing a sheet of glass, cooled at its bottom edge, to an enclosure with a controlled environment. The air in the enclosure was maintained at a constant relative humidity (RH) and a constant dry bulb temperature (Tdb). Experiments were conducted at Tdb = 22.1°C and RH of 30%, 35%, 40%, 45%, and 50%. It was found that the time until initial condensation run-off was sensitive to low RH (RH = 30%, 35%, 40%) and insensitive to high RH (RH = 45%, 50%). Time until run-off decreased with increasing RH. It was found that, at first, condensation run-off occurred near the bottom of the glass and left one to believe that the remaining condensate was in steady state with the enclosure. Over a 16 hour period however, it was found that the condensation run-off front, in every case, progressed upward to include the entire condensate area. Similar to time of initial run-off, speed of condensation front movement increased with RH and was also insensitive at high RH. A summary plot showing run-off front position is presented. This chart can be used to predict initial run-off and front progression at the bottom edge of any window if the surface temperature profile is known.

Vid implementering av realtidsapplikationer krävs det att man kan använda hårdvaran på ett deterministiskt vis. En realtidsapplikation ställer stora krav på körtider och hur applikationen schemaläggs. Det är därför av största vikt att kontrollera om de uppfyller dessa krav. I detta examensarbete har tre system för realtidsapplikationer jämförts och en analys av framförallt sina beräkningsförmågor och hur pass deterministiskt de uppför sig gällande körtider har gjorts. Även andra aspekter så som utvecklingsmiljöer för mjukvara, tillbehör och effektförbrukning har jämförts.