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This study is conducted with the aims to develop a new ranking method for multi-criteria decision making problem with conflicting criteria. Such a problem has a set of Pareto solutions, where the act of improving a value of one solution will result in depreciating some of the others. Thus, in this type of problem, there is no unique solution. However, out of many available options, the Decision Maker eventually has to choose only one solution. With this problem as the motivation, the current study develops a compromise ranking algorithm, namely a trade-off ranking method. The trade-off ranking method able to give a trade-off solution with the least compromise compared to other choices as the best solution. The properties of the algorithm are studied in the thesis on several test cases. The proposed method is compared against several multi-criteria decision making methods with ranking based on the distance measure, which are the TOPSIS, relative distance and VIKOR. The sensitivity analysis and uncertainty test are carried out to examine the methods robustness. A critical criteria analysis is also done to test for the most critical criterion in a multi-criteria problem. The decision making method is considered further in a fuzzy environment problem where the fuzzy trade-off ranking is developed and compared against existing fuzzy decision making methods.

Performance modelling and evaluation has long been considered of paramount importance to computer networks from design through development, tuning and upgrading. These networks, however, have evolved significantly since their first introduction a few decades ago. The Ubiquitous Web in particular with fast-emerging unprecedented services has become an integral part of everyday life. However, this all is coming at the cost of substantially increased security risks. Hence cybercrime is now a pervasive threat for today's internet-dependent societies. Given the frequency and variety of attacks as well as the threat of new, more sophisticated and destructive future attacks, security has become more prevalent and mounting concern in the design and management of computer networks. Therefore equally important if not more so is security. Unfortunately, there is no one-size-fits-all solution to security challenges. One security defence system can only help to battle against a certain class of security threats. For overall security, a holistic approach including both reactive and proactive security measures is commonly suggested. As such, network security may have to combine multiple layers of defence at the edge and in the network and in its constituent individual nodes. Performance and security, however, are inextricably intertwined as security measures require considerable amounts of computational resources to execute. Moreover, in the absence of appropriate security measures, frequent security failures are likely to occur, which may catastrophically affect network performance, not to mention serious data breaches among many other security related risks. In this thesis, we study optimisation problems for the trade-offs between performance and security as they exist between performance and dependability. While performance metrics are widely studied and well-established, those of security are rarely defined in a strict mathematical sense. We therefore aim to conceptualise and formulate security by analogy with dependability so that, like performance, it can be modelled and quantified. Having employed a stochastic modelling formalism, we propose a new model for a single node of a generic computer network that is subject to various security threats. We believe this nodal model captures both performance and security aspects of a computer node more realistically, in particular the intertwinements between them. We adopt a simulation-based modelling approach in order to identify, on the basis of combined metrics, optimal trade-offs between performance and security and facilitate more sophisticated trade-off optimisation studies in the field. We realise that system parameters can be found that optimise these abstract combined metrics, while they are optimal neither for performance nor for security individually. Based on the proposed simulation modelling framework, credible numerical experiments are carried out, indicating the scope for further work extensions for a systematic performance vs security tuning of computer networks.

In this thesis, I examine earnings management issues in the UK context. The thesis consists of three essays. The first chapter investigates whether managers base their trade-off decisions among real earnings management, accruals-based earnings management, and classification shifting, on the costs, constraints and timing of each strategy in the UK. The empirical evidence suggests that some, but not all, costs and constraints play a role in managers’ trade-off decisions. Further, contrasting between firms that are most likely to have manipulated earnings and firms that are not likely to have manipulated earnings, I find no difference in the relation of constraints towards all earnings management forms. This indicates that cost and constraints do not capture entirely what they are designed to, in the first place. Finally, I document evidence that is consistent with managers using real and accruals-based earnings management as substitutes but fail to find evidence that classification shifting acts as a substitute. The second essay studies the effect of income smoothing via accruals-based and real earnings management on the relationship between current stock returns, current earnings and future earnings. I measure income smoothing as the contemporaneous correlation between changes in earnings management proxies and pre-managed income. Using a sample of non-financial publicly listed firms in the UK, I show that both accruals-based and real income smoothing measures are associated with significantly positive share price anticipation of earnings. These results are robust to different stock returns specifications, income smoothing measure calculations, abnormal accruals models and accumulation periods of stock returns. In the third and final essay, I investigate the impact of the level of accruals-based and real earnings management on measures of the amount of performance commentary in annual reports for a large sample of UK public firms. I use automated textual analysis to construct disclosure scores based on the amount of performance and causal commentary. The results suggest that firms with higher levels of earnings management have lower levels of disclosure of performance and causal commentary. The presence of bad news for the firm (missed analyst forecast, underperformance or earnings decline) affects the relationship between disclosure and accruals-based earnings management but not the relationship between disclosure and real earnings management.

In antibiotic therapy design, conventional wisdom holds that higher antibiotic dosages always leads to the observation of fewer bacterial cells, resulting in a monotonic decay in cell number as a function of increasing antibiotic dose; accordingly, throughout this thesis, we will call this phenomenon a monotone dose-response profile. When we analysed the evolution of antibiotic resistance mediated by the multi-drug efflux pump AcrAB-TolC in Escherichia coli to study if such a monotone dose-response is maintained at all times, our analysis showed that higher dosages can, in fact, lead to higher bacterial loads. This is because selection for drug resistance is mediated by the duplication of the genes, AcrAB-TolC, that encode the aforementioned efflux pump. As explained in detail below, our work highlights the idea that Darwinian selection on additional copies of AcrAB-TolC is a non-linear function of antibiotic dose and that the observed transition from monotone to non-monotone dose-response is a consequence of AcrAB-TolC being strongly selected at very specific dosages. We term this phenomenon an ‘evolutionary hotspot’. Next, we extended the above experimental system to solid media to study how selection on resistance mediated by AcrAB-TolC leads to a ‘spatio-genomic patterning’ effect that we call a ‘bullseye’. Using a bespoke culture device developed as part of this PhD, we show that spatial selection on resistance also depends non-linearly on the distance of the cell from an antibiotic source, and that the non-linearity can be multi-modal as a function of distance, and therefore also of antibiotic dose. This result also contradicts the aforementioned principle that higher antibiotic dosages necessarily lead to fewer bacterial cells. Following on from this, we then studied the ability of microbial competitors for resources to modulate the antibiotic sensitivity of a particular strain of E. coli, namely Tets , using a range of multi-species experiments. We measured the sensitivity to antibiotics of Tets both with, and without, one bacterial or fungal competitor. When that competitor was equally sensitive to the antibiotic, we observed that Tets was less sensitive to it, in part due to an ‘antibiotic sinking’ effect carried out by the competitor strain. However, when the competitor was not sensitive to the antibiotic, Tets was, accordingly, more sensitive than in the absence of competition. In this latter case, the competitor seemed to reduce the growth of Tets by carbon theft as part of a phenomenon known as ‘competitive suppression’. Moreover, this ecological effect is one that synergises with the action of the antibiotic. Finally, we turned to a study of an ecological trade-off motivated by ribosome-binding antibiotics. So, by manipulating the content of ribosomal RNA in the E. coli cell, a large and essential molecule that is bound by antibiotics such as tetracycline or erythromycin, we could subsequently manipulate what is known as a metabolic trade-off between growth rate and growth yield. The latter is the number of cells produced per molecule of carbon found in the extracellular environment of the bacterial population. Using glucose as carbon source we therefore constructed an empirical fitness landscape that shows how the optimum number of ribosomal rRNA operons depends on extracellular glucose concentration. Whilst this study does not relate directly to the presence of an antibiotic, it does show that by altering the number of operons in a manner that is known to affect antibiotic susceptibility, we can also mediate important growth parameters like cell yield, aka efficiency, and growth rate.

In order to meet their energy budget animals must often increase their risk of predation, either through their choice of foraging location or by decreasing anti-predation behaviours, which are incompatible with foraging. I investigated the starvation-predation risk trade-off in redshanks overwintering in the area of the Firth of Forth in Scotland over different spatial scales. On a small spatial scale, where redshanks foraged in an area where risk of attack was high I investigated the role of competition for food and decreased individual vigilance within groups and how this related to predation risk, additionally I looked at the relative roles of individual variation in time spent exposed to risk and variation in anti-predation behaviours on individual survival time. On larger spatial scales of 100s of meters and over several kilometres, I considered how choice of overwintering site was affected by predation risk, profitability and population density. Time available to feed increased with increased group size, allowing redshanks to compensate for increased competition and allowing large groups to form, thus decreasing individual predation risk. Individuals that spent less time exposed to attacking predators survived for longer, however individuals constrained by cold weather to spend long periods exposed to risk could increase their survival through increased intake rates and vigilance. On an intermediate spatial scale redshanks selected overwintering sites based on profitability rather than risk, and only used less profitable site when population density was high. On a large spatial scale redshanks increased their use of less profitable sites in warmer weather, but did this without increasing their risk of predation. Overall this suggests that across most spatial scales redshanks can minimise their predation risk by their choice of foraging location, but when forced by weather conditions or competition to be exposed to attack, capture reducing behaviours also reduce predation risk.

Mounting immune responses against pathogens and parasites is a notoriously costly endeavor. And thus, immune responses are subject to physiological trade-offs that balance resource and energy investment between immunity and other life history traits.While the immune system is considered a critical component of organismal life history, we know little about how life history trade-offs shape the various immune phenotypes we see in nature. In this dissertation, I explore what shapes immune defenses from three perspectives: drivers of within-population variation in immune function, drivers of between-population variation in immune function, and how environmental conditions shape the development of immune defenses. Throughout this work, I measured bacteria killing ability (BKA) to measure the effectiveness of immune function in tree swallows (Tachycineta bicolor). In chapters 1 and 2, I show that life history traits like timing of breeding can determine whether immune function is subject to a trade-off with reproduction, and how responsive it is to chronic elevations of glucocorticoids, the main hormonal mediator of the stress response. In chapter 3, I investigate how bacteria killing ability varies geographically along a gradient of environmental unpredictability. In this study, I show that immune function declines with increasing environmental unpredictability, potentially due to increasing brood reproductive value in locations with more unpredictable environmental conditions. Locations with higher reproductive value are more likely to allocate more resources in reproduction than immunity because elevated environmental unpredictability would reduce the chances to breed again later. Finally, in chapter 4, I investigate how environmental conditions during development, specifically exposure to cold temperatures - one of the outcomes of increased environmental unpredictability - drives resource allocation strategies that prioritize thermoregulation at the cost of immune investment. I found that cold-exposure during incubation made nestlings better thermoregulators, which had not been observed in altricial birds like tree swallows, but that it did not come at a cost to immune function. Overall, I show that immune investment and function is broadly dependent on life history strategies that may vary among individuals and across populations. Thus, my work suggests that life history can shape disease vulnerability, reinforcing the role of immunity as a life history component.

Trade-offs between reproduction and immunity are common among animals, potentially due to preferential allocation of limiting resources. In Drosophila melanogaster, mating increases egg production, but also triggers a rapid decrease in female immune defense. Here, I examine the dynamics of post-mating immune defense and identify how allocation of resources to oogenesis drives the trade-off between egg production and immunity.First, I found that mating continuously suppressed female immune defense for up to 10 days after mating as compared to age-matched unmated females. I additionally found that females mated either once or twice before infection survived at equal proportions, both with significantly lower probability than unmated females. I conclude that a single mating triggers a binary switch from mated to unmated state to persistently suppress the female immune system. Second, I hypothesized that direct resource allocation to yolk protein production and vitellogenesis limits female immune defense. I found that four mutants which arrest egg development prior to vitellogenesis maintain immune capacity after mating. I found that mating reduced the immune defense of okra females that complete vitellogenesis, but produce non-viable embryos. However, retained females, who complete egg development but do not oviposit, were not immune suppressed after mating. Additionally, I found that loss of yolk proteins increased immune performance relative to controls, but yolk protein mutants still experienced a reduction in immune capacity after mating. I conclude that production and incorporation of yolk proteins during sustained egg production limits female immune defense, but that other post-mating signaling mechanisms could also suppress immunity. Together, these results are consistent with the hypothesis that the dual demands of yolk protein production and immune defense places stress on the fat body, limiting timely and effective immune defense. Finally, I present evidence from collaborative projects investigating new potential genes involved in female immune defense and male reproduction. I find no evidence that dTCERG1, whose homolog inhibits immunity to promote reproduction in C. elegans, suppresses mated female D. melanogaster immune defense. I additionally found no evidence that dArc1, a gene annotated as regulating memory and metabolism and highly expressed in male accessory glands, influences competitive sperm fitness.

Feathers are complex structures essential to a bird’s survival which must be periodically replaced by molting. The process of molt in birds is characterized by multiple physiological changes and is known to be expensive in terms of the nutrients required to produce quality feathers quickly. However, little is understood about the relationship between the costly processes of molt and immune function. The overall objective of this dissertation was to determine how molt affects the immune system in regard to both systemic shifts and a potential trade-off between molt and mounting an innate immune response. In the first experiment, we investigated how the spleen, thymus, and inflammatory state of the domestic chicken (Gallus domesticus) shifts over the course of molt. Half of the adult laying hens (N = 36) were induced to molt using a combination of oral thyroxine (T4), a reduced calorie diet and a shift from a long day to a short-day schedule. Blood, liver, spleen, and thymus samples were collected weekly to assess changes over the course of molt. To determine if molt induced either a pro- or anti-inflammatory state, the level of key pro- and anti-inflammatory cytokines were evaluated via qPCR and ELISA. The spleens of molting birds were 63% heavier than the spleens of non-molting birds, and the thymus weight of molting birds increased 6.8-fold (P < 0.01). Upon histological examination, the thymus of molting birds had clearly defined lobules and an increase in cortex and medulla tissue (P < 0.01). Molting birds had a significantly higher proportion of double-positive T cells in the thymus than non-molting birds (P < 0.01). Overall, the increase in mass of both the thymus and the spleen resulted in molting birds having a greater number of T cells. Both IL-8 and TNF-alpha expression increased in the liver during molt, but overall, there was no clear indication that molt leads to an increase in inflammation during feather growth. During molt, there are marked changes in the weight and lymphocyte populations of the spleen and thymus which may be driven by molt or triggered by the hormonal shifts that occur with molt. In the second experiment, molting birds were subjected to an innate immune challenge to clarify how the nutritional requirements of molt may alter investment in an immune response. Adult hens (N = 16) were induced to molt using the same combination of cues described for experiment one. During week four of molt, birds were challenged with an intra-abdominal injection of lipopolysaccharide (1.5 mg/kg) to induce an innate immune response. Four hours post injection, liver, spleen, and blood samples were collected to evaluate changes in the expression levels and plasma concentration of key pro- and anti-inflammatory cytokines. The weight of the spleen and thymus were measured to assess changes in lymphoid tissue mass during molt. The spleen and thymus were both significantly heavier in molting birds than non-molting birds (P < 0.01). Based on inflammatory cytokine expression levels in the liver and spleen, both molting and non-molting birds mounted an innate immune response to LPS, but the response was dampened in molting birds. The expression levels of IL-6 and IL-8 were significantly reduced in molting birds. The concentration of IL-1-Beta and IL-6 in the plasma of molting birds was also significantly reduced compared non-molting birds indicating that production of protein as part of the inflammatory response may be attenuated due to competing demands for protein deposition in feathers. The third experiment used a unique genetic line, the Scaleless High (ScHi) line, to further examine the trade-off between molt and an innate immune response by mitigating the cost of feather production. ScHi birds have reduced feathering due to a genetic mutation and were used to determine if the trade-off between molt and the immune system is driven mainly by the mass of feathers grown during molt or by the broader process of molt and the accompanying hormonal and metabolic changes. Adult hens from both genetic lines (N = 32) were induced to molt using the combination of hormonal, light, and dietary signals. During week four of molt, half of the birds in each genetic line were challenged with an intra-abdominal injection of lipopolysaccharide (1.5 mg/kg) to induce an innate immune response. Five hours after the LPS injection, samples were collected from the liver and spleen to evaluate the expression of pro- and anti-inflammatory cytokines. The weights of the spleen and thymus were measured to determine if systemic changes in these lymphoid tissues during molt were dependent on the mass of feathers growing during molt. The spleen and thymus significantly increased in weight during molt in both genetic lines (P < 0.01). The thymus weight increased 7.8-fold while the spleen weight increased an average of 48% across molting birds from both genetic lines. The area of cortex in the thymus unexpectedly increased more in molting reduced feathering ScHi birds than in the fully feathered UCD-003 birds. The inflammatory response to LPS was dampened in both genetic lines, especially the expression levels of IL-6 and IL-8. The overall process of molt, rather than the mass of feathers grown, appears to drive the trade-off between molt and the immune system when both processes must occur concurrently. This research helps clarify how a nutritionally expensive component of immunity, the inflammatory response, is affected by molt when birds must balance the costs of the immune system with the costs of molting. When molt and an innate immune response must occur concurrently, the inflammatory response is dampened, likely as a mechanism to allow both molt and an innate immune response to progress during an energetic or nutritional bottleneck.

Pharmaceutical companies have slowed the discovery and development of antibiotics due to low-profit margins. Therefore, antibiotic discovery is at an all-time low, and pathogens have evolved resistance to all currently available drugs. As a result, multi-drug resistant (MDR) bacterial infections are becoming more difficult to treat, especially in individuals at a high risk for infection such as cystic fibrosis (CF) patients. CF is a genetically inherited disease that inhibits or decreases chloride ion transport across epithelial cell membranes, resulting increased mucus viscosity, impairing normal clearance in the lungs. This environment is ideal for bacterial colonization and leads to a chronic lung infection. A major pathogen that colonizes the CF lung over time is Pseudomonas aeruginosa. A promising alternative treatment against MDR P. aeruginosa is bacteriophage therapy which has several advantages compared to antibiotics. First, phage therapy exhibits minimal side effects because phage are highly host-specific and do not inhibit other bacteria that are part of the human microbiome. Second, phage replicate itself exponentially when killing its host; and third, phage can be applied directly to the site of infection. However, like antibiotics, bacteria can evolve resistance to phage. To circumvent the problem of phage and drug resistance, trade-off effects may promote opportunities against both entities that may be exploited to treat MDR infections. I hypothesize that the effectiveness of antibiotics can be restored after selective pressure from bacteriophage. To test this hypothesis, MDR P. aeruginosa strains were exposed to phage in trade-off experiments, and results showed that the evolved phage resistant P. aeruginosa strain became antibiotic susceptible. In one trade-off experiment, a temperate phage recombined in the P. aeruginosa pathogen at a location downstream of a multidrug resistance efflux pump that may directly affect antibiotic susceptibility. In another experiment, a lytic phage was used, and the selected P. aeruginosa strain also showed increased antibiotic sensitivity. It is likely this resistance reflects underlying genetic mechanisms distinct to those that occurred with the temperate phage. Thus, selective pressure from phage may be utilized to evolve MDR pathogens towards antibiotic susceptibility.

Energy available for life history allocations or investments into growth, reproduction, activity, and somatic maintenance depends on how much and what type of resources organisms acquire from the environment, combined with how acquired resources are processed through metabolic pathways. Consequently, both environmental (e.g. resource availability) and physiological (e.g. metabolic) constraints on energy availability directly contribute to the maintenance of widescale variation in life histories across the tree of life. Variation in life history spans a single continuum from a fast (fast growth, early reproduction, and short lifespan) to slow (slow growth, late reproduction, and long lifespan) “pace-of-life” that shapes population and ecosystem dynamics. The timing of life history allocations evolves to maximize fitness based on environmental conditions, but environments are becoming more variable, due to global climate change. Organisms may be able to adapt to novel environments by changing their life history but, predicting if and how life history evolution will buffer species from consequences of global change requires a mechanistic understanding of life history, motivating this dissertation work. Decades of work has investigated the roles of energetic constraints in shaping life history allocations, but environmental constraints on resource acquisition and physiological constraints on metabolism are often considered independent of one another. Therefore, complex interactions between resource acquisition, metabolism, and life history allocations, along with their role in governing life history evolution, remains uncharacterized in any single system. This dissertation sheds new light on the mechanistic underpinnings of life history by testing the central hypothesis that to meet changing energetic demands of life history allocations through the life cycle, coordinated shifts in resource acquisition and metabolism are required, and therefore underpin the expression of alternative life histories. While large-scale diversity in life histories is found across the tree of life, variation in life history strategies is also present among individuals in species with life history polymorphisms. I leveraged one model system with a life history polymorphism, wing-polymorphic field crickets (Gryllus spp.). Within populations of wing-polymorphic field cricket species, individuals are either flight-capable (long-winged, LW) or flightless (short-winged, SW) in early adulthood. The polymorphism is maintained by an allocation-based trade-off between flight and oogenesis: long-winged crickets preferentially allocate resources to support flight muscle maintenance and somatic fat storage, enhancing dispersal capability, while short-winged crickets preferentially allocate resources to support oogenesis at a younger age, enhancing early life fecundity. Both long- and short-winged forms (morphs) co-occur within populations and the polymorphism is present in multiple independently evolving lineages of field crickets. Thus, this system provides a powerful model in which we can investigate mechanisms of life history evolution acting on genetically similar organisms, both within and across species. I studied two closely related wing-polymorphic cricket species, the variable field cricket (Gryllus lineaticeps) (Chapter 1 and 3) and the sand field cricket (Gryllus firmus) (Chapter 2 and 3). The variable field crickets (G. lineaticeps) that I worked with were derived from wild-collected individuals and maintained in a genetically polymorphic laboratory population, providing morphs with a mixed genetic background and naturally segregating combinations of alleles that evolved under natural selection. In complement, the sand field crickets (G. firmus) that I worked with were derived from family lines following long-term artificial selection on wing-length, which maximized phenotypic and genetic differences between flight-capable and flightless crickets. In these species, I advanced our understanding of the behavioral and physiological basis of life history, by characterizing the associations between resource acquisition, metabolism, and life history allocations in crickets investing in either flight or reproduction. To do so, I applied an integrative approach that spanned levels of the biological hierarchy (whole organism, tissues, cells, and organelles) on variable timescales (within and across life stages). Combined, my findings suggest that both resource acquisition and metabolism are fine-tuned based on energetic demands of life history, and thus represent fundamental processes that have evolved to enable organisms to alter the timing of major life history events.In Chapter 1, I disentangled the reciprocal interaction between resource acquisition and life history allocations, by using a geometric framework of nutrition experimental approach. I hypothesized that high demands of biosynthesis for life history allocations drive elevated resource acquisition requirements and increase performance costs of resource limitations. To test this hypothesis, I characterized resource acquisition (dietary preferences and intake) and life history allocations, across the juvenile to adulthood transition in both male and female variable field crickets (Gryllus lineaticeps), when feeding on artificial diets varying in nutrient composition (carbohydrate- or protein-biased). I used Gryllus lineaticeps crickets recently derived from natural populations for this study, to avoid potential effects of long-term lab adaptation on nutritional preferences and feeding behavior. Consistent with my hypothesis, long-winged crickets increase feeding as juveniles to meet elevated caloric requirements associated with flight muscle synthesis. However, nutritionally imbalanced diets did not affect allocations to flight because long-winged juveniles behaviorally adjusted feeding to meet caloric requirements irrespective of diet composition and palatability. As adults, males ate less than females and life history allocations of males were insensitive to diet, due to lower energetic costs of reproduction for males compared to females in early adulthood. In females, the onset of adulthood was accompanied by a shift in dietary preferences to more protein-biased diets in short-winged crickets investing in large scale and rapid oogenesis, but not in long-winged crickets investing in flight. Unlike juveniles, adult females did not fully behaviorally compensate for variation in diet composition and incurred large caloric and protein deficits on a carbohydrate-biased diet. This in turn resulted in a constraint on reproductive investment by short-winged females; on carbohydrate-biased diets, short-winged females could no longer meet biosynthetic demands of oogenesis, resulting in small ovaries. This finding broadly suggests that when energetic and nutrient demands of life history allocations are large, behavioral adjustments in feeding may not be sufficient to buffer organisms from energetic constraints caused by resource limitations. Additionally, on a carbohydrate-biased diet, ovary size of short-winged and long-winged crickets was similar suggesting that without sufficient protein acquisition, the adaptive benefit of higher early life fecundity associated with the typical short-winged life history strategy is lost. Together these findings reveal that strong associations between resource acquisition and life history allocations dictate fitness consequences of reductions in environmental resource availabilities in a life stage, sex, and life history specific manner. In Chapter 2, I focused on the association between metabolic and life history evolution. In the sand field cricket, Gryllus firmus, I determined how high energetic demands of life history allocations to dispersal-capability drives the evolution of larger metabolic capacities through biochemical and molecular changes in tissues and organelles. I hypothesized that tissue-specific increases in either mitochondrial content or function result in larger metabolic capacities and improved locomotor performance in flight-capable long-winged compared to flightless short-winged crickets, due to the high aerobic demands of flight. I measured a suite of metabolic traits across levels of the biological hierarchy, from organismal metabolic rates and running performance in vivo, to metabolic function of tissues and organelles in vitro. When running on a treadmill, flight-capable long-winged crickets reach higher maximal metabolic rates and had an enhanced endurance compared to flightless short-winged crickets. Consistent with my hypothesis, long-winged crickets also exhibited increases in mitochondrial content of dorsoventral flight muscle and modifications to the electron transport system composition within mitochondria of the fat body, a tissue responsible for fuel storage and mobilization, which resulted in enhanced mitochondrial bioenergetic capacities. Therefore, metabolic pathways are remodeled in a tissue-specific manner to increase energy production capacities required for high levels of activity. Since this study was conducted in sand field crickets (Gryllus firmus) artificially selected for flight-capability or reproduction, I further concluded that differences in metabolic capacities arose in response to selection on a single life history trait, dispersal-capability. Overall, this work provides fresh insight into the links between life history and metabolism, suggesting that dispersal capability should be explicitly considered as a potential factor driving the evolution of metabolic capacities.In Chapter 3, I further investigated the interaction between metabolism and life history by determining if mitochondrial function and life history allocations change concurrently across early adulthood. I hypothesized that energetic requirements increase with biosynthetic demands of life history and elicit concurrent elevations in mitochondrial respiratory function. To test this hypothesis, I assessed life history allocations and mitochondrial function across the first week of adulthood, in both long- and short-winged variable field (Gryllus lineaticeps) and sand field (Gryllus firmus) crickets. In both species, mitochondrial function of morphs diverged through time, along with their allocations to either flight or reproduction. In long-winged crickets, mitochondrial bioenergetic capacity for energy production increases through early adulthood, peaks at the time of dispersal, but rapidly declines when a switch to reproduction is made post-dispersal. In short-winged crickets, mitochondrial bioenergetic capacity declines gradually as ovarian synthesis is completed. Despite different evolutionary histories (Gryullus firmus- artificially selected vs. Gryllus lineaticeps- genetically admixed backgrounds), patterns of mitochondrial plasticity were consistent between species, suggesting that mitochondrial plasticity is likely an important general adaptation shaped by life history evolution. Overall, these findings support the conclusion that adaptive plasticity in mitochondrial function enables shifts in life history allocations, advancing our understanding of the metabolic basis of life history.

The optimality of a foraging strategy shifts in response to dynamic ecological conditions and the need to devote effort to other tasks. Nest defense and foraging effort in the honey bee may trade off as both tasks are performed by a shared workforce of physiologically-specialized individuals in exclusive roles. Honey robbing is a foraging strategy predicted to benefit from simultaneous increases in foraging and defensive effort, but may be constrained by workforce specialization. We developed a methodology to induce robbing behaviors with uninhabited bait hives. We used this methodology to evaluate foraging and defensive effort before and during robbing by measuring forager activity and guard defensive behavior. We then assessed three cues as potential indicators guards use to determine colony robbing status. We assessed changes in identifying odor through laboratory assays of comb exposure, robber behavior through a genomic analysis of aggression biomarker genes, and field studies of the correlation between forager activity and guard defensiveness. Our results indicate colonies can simultaneously increase defensive and foraging effort when participating in robbing. We determine guards likely respond to multiple cues, with strong evidence for robbing nestmate behavior and some evidence for forager activity as signals. These results show colonies are able to dynamically balance the trade-offs of worker specialization to facilitate optimal foraging through complex social cues.

Ecological restoration has become a large enterprise driven by regulatory policies and by public and private initiatives. Regulatory agencies and ecologists call for use of propagules that are adapted to project sites, compatible with other species, and genetically diverse. This project uses a native California grass, Stipa pulchra, to ask whether the cost-management practice of collecting seeds from dense stands of target species can have unintended selective effects on species used in restoration. Absolute cover, standing biomass, species composition, and S. pulchra density and culm count were recorded on plots in three central California sites. S. pulchra seeds from these plots were sown in pots allocated to two watering groups and three temporal blocks. Pot-study plants grown from seed collected from plots with greater absolute cover and S. pulchra density had significantly higher basal diameters, tiller counts, and root: shoot ratios. Plants derived from less-competitive plots reproduced earlier and gave rise to more culms. These results indicate that distribution of S. pulchra genoypes in the field may reflect a competition: colonization pattern, with more fecund S. pulchra plants inhabiting less-competitive patches than those occupied by their more-competitive conspecifics. Other aspects of pot-study plant growth appeared to reflect background vegetation of the field plots. Although plants grown from seeds collected at the three sites were significantly different, there was no evidence that ecological distance reflected geographic distance. Plants receiving more water had relatively greater aboveground growth and lower root: shoot ratios. Statistical interactions of blocking and watering treatments with site may reflect plant adaptation to climate and soil at the various sites. Implications of these results apply to environmental restoration and extend to ecological research, where nonrandomly collected propagules are often used to represent genetic characteristics of entire populations.

The operating room (OR) is accountable for most hospital admissions and is one of the most cost and work intensive areas in the hospital. From recent trends, we discover an unexpected parallel increase in expenditure and waiting time. Therefore, improving OR planning has become obligatory, particularly regarding utilization, and service level. Significant challenges in OR planning are the high variations in demand, processing times of surgical specialties, the trade-off between the objectives, and control of OR performance in long-term. Our model provides OR configurations at a strategical level of OR planning to minimize the tradeoff between the utilization and service level accounting for variation in both demand and processing times of surgical specialties. An adaptive control scheme is proposed to aid OR managers to maintain the OR performance within the prescribed controllable limits. Our model is validated using a simulation of demand and processing time data of surgical services at University of Kentucky Health Care.

Abstract: The mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), has an obligatory dispersal phase before selection of a suitable host for brood production. Flight during the dispersal phase is affected by both beetle physiology and environmental factors. Mountain pine beetle utilizes energy obtained during larval development and adult feeding before emergence from the natal tree host to fuel flight. Energy expenditure on flight may have consequences for subsequent reproduction. Mountain pine beetles were flown on computer-linked flight mills to establish how beetles utilize energy during flight and to determine how environmental conditions affect flight capacity. Mountain pine beetles utilize both lipids and carbohydrates to fuel the flight. Neutral lipids are the major fuel for flight. Beetles held at lower temperatures were more likely to fly and flew for longer distances than beetles held at warmer temperatures. Beetles increase flight distance and duration with day length. Beetles fly against wind speeds of 0-2 m/s in a wind tunnel. The effect of flight on subsequent reproduction was tested by introducing beetles flown on flight mills and un-flown control beetles into bolts of either lodgepole, Pinus contorta Douglas. ex. Loud. var. latifolia), or jack, Pinus banksiana Dougl., pine to reproduce. There is a trade-off between flight and reproduction in the mountain pine beetle as control beetles that did not fly produced a significantly higher number of offspring than flown beetles. The pine host that offspring were reared in affected the number of offspring and their condition, as more offspring emerged from jack pine but higher quality offspring emerged from lodgepole pine. Offspring from flown parents have a slightly lower body condition compared to the offspring from control adults. The study reveals physiological and environmental factors that influence dispersal capacity of mountain pine beetle and a trade-off between flight and reproduction in mountain pine beetle.

During 2014 in West Africa, Ebola virus disease (EVD) was a serious public health concern and risk where the most deadly outbreak occurred since the initial epidemic in 1976 and where health care workers (HCWs) population suffered in a dramatic way. EVD transmission is possible through the movement of infected individuals where infection is classified as asymptomatic or severe. This could imply that as symptoms severity increase, individuals with severe infections may be unable to move as much and therefore contacts with other individuals will decrease. This involves a trade-off between contact and probability of transmission given contact in the general population (non-HCWs population). In contrast, HCWs population do not experience the same trade-off as the general population, because as symptom severity becomes greater, contacts with HCWs will increase. A mathematical model was developed in order to study this scenario and also to interpret the effect of the trade-off involving both populations by analyzing the basic reproductive number R0 as a function of the probability of transmission given contact. It was found that R0 in the model represents the contribution of the general population and the contribution of the HCWs population regarding the new cases of EVD. Moreover, sufficient conditions were determined in order to acquire an increasing monotone function of the probability of transmission given contact including intermediate ranges for relative transmissibility parameters. Finally, performing parameter estimation of the model it was possible to estimate the initial growth rate of an epidemic r using the cumulative incidence data from 2014 that corresponds to the outbreak. Additionally, R0 was estimated from r providing a match between the data, literature, and the deterministic model. This could help to interpret in a clean way how much the contribution in disease transmission from HCWs during the 2014 Ebola outbreak was, how fast the EVD outbreak grew, and how to be prepared for another catastrophic outbreak with the necessary intervention capacity and adequate measurements for control.

Temporally variable environments are the norm rather than the exception in nature. Yet, the ecological consequences of this variability and the evolutionary responses it invokes remain poorly understood. In this thesis, a previously proposed theory of competitive coexistence was further developed that yielded a nonconventional prediction: fluctuating environments can support stable coexistence of competitors even in the absence of negative frequency-dependent selection. It was confirmed by laboratory competition using bacteria. After generalization of the theory by simulation, an alternative to the genetic drift model emerges that explains the rich polymorphism observed in nature. Next, a dynamic theory of bet-hedging was developed and tested by experiments, which also proved stochastic phenotypic switching as a highly adaptive bet-hedging strategy. Besides, this new theory predicts that the standard theory of bet-hedging should fail under certain conditions of direct biological relevance. With the ecological and evolutionary models tested, a forward evolutionary experiment was carried out to study adaptation to fluctuating environments. Hypothesis free, this effort captured unexpected strategies to cope with cyclic environments, revealing the generative effect of trade-off in the presence of two-dimensional selection. Together, these three projects offer a multi-perspective picture of the complex process of adaptation in fluctuating environments, with an emphasis on mechanisms—ecological or physiological—that underlie the emergence of varied evolutionary responses.

The low efficiency of collection, storage and transportation in the switchgrass supply chain has hindered the commercialization of a switchgrass-based biofuel industry, even given its ecological and environmental advantages in carbon sequestrate, soil quality, water use, and pollution pressure. Thus, designing a switchgrass-based supply chain balancing both environmental and economic performance is important to expedite the development of the cellulosic biofuel industry to meet the national energy plan. The objectives of this study are to 1) determine economic cost and multiple environmental outcomes in feedstock supply chains and 2) identify the relation between the economic and environmental performances. The first paper considers three objectives: minimization of economic cost, greenhouse gas (GHG) emissions, and soil erosions. The second paper focuses on the relation between economic cost and abated greywater footprint for industrialized supply of cellulosic biofuel in west Tennessee. The improved augmented epsilon method and compromise solution method were applied to high-resolution spatial data to determine the optimal placement of the feedstock supply chains. Results in the first paper indicated that land change into switchgrass production is crucial to both plant-gate cost and environmental impact of feedstock supply. Converting croplands to switchgrass incurred higher opportunity cost from land use change but stored more soil carbon and generated less soil erosion. Tradeoffs in higher feedstock costs with lower GHG emissions and lower soil erosion on the frontier were captured. Soil erosion was found more cost effective criterion than GHG emission in general. The compromise solution location for the conversion facility generated at 63% increase in feedstock cost but improved the environmental impact in lowering 27 % GHG emission and decreasing soil erosion by 70 times lower in the feedstock supply chain compared with cost minimization location. Results in the second paper showed that tradeoff between feedstock costs and greywater footprint was mainly associated with the changes of land use, while ambient water quality condition was also influential to the selection of feedstock production area. The average imputed cost of lowering grey water footprint in the most preferred feedstock supply chain in west Tennessee was $0.94 m-3 [per cubic meter].

The abundance of proteins expressed in a particular environment are primary determinants of an organism's phenotypic and fitness properties. However, protein synthesis is costly and proteome size is limited; thus, the benefit of expressing proteins also comes with costs. In this thesis, I interrogate the evolutionary and regulatory trade-offs resulting from these proteome allocation constraints. Throughout the thesis I employ a genome-scale model of metabolism and protein synthesis for Escherichia coli, which can compute condition-specific proteome allocation requirements and limitations. First, I show that microbial growth rates are quantitatively determined by the expression of unused protein. Rather than supporting growth in the current environment, large fractions of the expressed proteome enable readiness for environmental change and stress. The expression of these different proteome segments is regulated by global transcription factors and results in fitness trade-offs. Second, I show that after selecting for growth through experimental evolution, several adaptive regulatory mutations increase fitness through proteome and energy resource re-allocation. These pleiotropic mutations in the RNA Polymerase systematically re-allocate the proteome towards growth and away from stress resistance, showing that fitness trade-offs are readily modulated by global regulators during evolution. Finally, I show that the diversity present in evolving populations is predictable and due to proteome allocation trade-offs. Rather than evolving to a unique optimum, a range of near-optimal proteomic and metabolic phenotypes is apparent when strains are independently evolved in the same environment. The diversity of alternative phenotypes reflects a rate-yield trade-off due to the varying protein cost of metabolic pathways in central carbon metabolism. Thus, proteome allocation constraints have a pervasive and predictable effect on bacterial ecology, regulation, and evolution.

The first chapter of the dissertation analyzes how characteristics of a firm's brand affect financial decisions by using a proprietary database of consumer brand evaluation. It demonstrates that positive consumer attitude alleviates financial frictions by providing more net debt capacity, as measured by higher leverage and lower cash holdings. Brand perception reduces the overall riskiness of a firm, as strong consumer evaluations translate into lower future cash flow volatility, higher Z-scores, and better performance during recession. Creditors favor strong brands by demanding lower yields on corporate public bonds. The results are more pronounced among small firms and non-investment grade bonds, contradicting a number of reverse causality and omitted variables explanations. The second chapter develops a framework that shows how exactly market timing and trade-off forces coexist. The idea is that market timing benefits dominate trade-off costs when firms are close to their target leverage, but become offset by the rebalancing considerations when firms are farther away. Two sets of empirical results support the validity of the framework. First, the sensitivity of equity issuances to past stock performance is the highest among firms close to the target leverage. Second, the long-run performance of equity issuers is also a function of their deviation from target leverage. The lower the leverage of issuing firms is relative to the target, the worse their after-issuance returns are, consistent with higher market timing incentives compared to other issuers. The third chapter studies whether investors value dividend smoothing stocks differently by exploring the implications of dividend smoothing for firms' expected returns and their investor clientele. First, it demonstrates that dividend smoothing is associated with lower average stock returns in both univariate and multivariate settings. Some of this return differential can be attributed to lower risk, captured by return comovement among high (low) smoothing firms. Second, the chapter shows that institutional investors, and specifically, mutual funds, are more likely to hold dividend smoothing stocks. Last, firms that smooth their dividends issue equity more frequently. Together, these results are consistent with the role of dividend smoothing in mitigating the impact of agency conflicts on the cost of capital.

Locomotion is an integrative trait, critical for aspects of Darwinian fitness in many organisms. Selection resulting from locomotor demands can greatly influence morphology, physiology, and behavior. Locomotion can be energetically costly, and locomotor performance involves the function of many underlying physiological systems. When organisms are faced with multiple energetic demands, it is reasonable to expect trade-offs related to energy allocation. My dissertation research investigated the effects of environmental stressors on exercise. Using four unique High Runner (HR) lines of mice (Mus domesticus) bred for voluntary wheel running, my first chapter investigated a hindlimb `mini-muscle' phenotype that increased in frequency in response to selection in two of four selected lines. As compared with normal HR mice, mini-muscle individuals ran as much on wheels, but had reduced sprint speed, suggesting a trade-off with stamina, and, unexpectedly, a higher cost of transport. My second chapter investigated the response to a mammalian endoparasite (Trichinella spiralis) in HR and non-selected control mice, particularly possible trade-offs between wheel running and immune function. Contrary to our expectations, HR mice apparently did not have an important reduction in immune function. Moreover, our results suggest a similar response to infection in both HR and control mice.My third dissertation chapter examined the physiological, morphological and behavioral correlates of circulating corticosterone (a steroid "stress" hormone) levels in captive-bred California mice (Peromyscus californicus), a species that has unusually high corticosterone levels. Contrary to expectations based on the role of corticosteroids in energy metabolism, we found surprisingly few statistically significant relationships at the level of individual variation, suggesting that corticosterone is not always a critical contributor to voluntary exercise behavior or exercise performance. However, we did find differences in correlations between the sexes.My final chapter analyzed the upper limit to aerobic metabolism (V. O2max) during maximal locomotor exercise for 77 species of mammals. V. O2max is a physiologically and ecologically relevant trait for many animals, and it is generally considered to be the single best indicator of cardiopulmonary function and capacity for sustained intense exercise. Using conventional and phylogenetic statistics, we estimated allometric scaling exponents and demonstrated phylogenetic signal in mass-adjusted V. O2max.Together, these results point to the importance of understanding the complex, integrative physiological mechanisms contributing to exercise physiology and the limits to performance. Moreover, they drive home the importance of both evolutionary history and adaptation in response to natural selection as contributors to behavior and whole-organism performance.

Aggregative feeding is widespread in Lepidopteran larvae suggesting that this behavior serves on adaptive function. Many studies of the potential benefits of aggregative feeding in Lepidopteran larvae have been conducted. However, no studies have directly examined the benefits of cryptic larvae being both chemically defended and gregarious. Group feeding occurs disproportionately more in chemically defended larvae than in larvae that have no chemical defense. Most of these larvae are cryptic when they are most highly aggregated and most vulnerable to predation. In this study, the benefits of group feeding in terms of decreased predation were explored in first instar larvae of pipevine swallowtail larvae, Battus philenor, a species that exhibits chemical sequestration. Contrary to our expectation, we found that groups of larvae fed a diet with high levels of the toxin aristolochic acid, which they sequester naturally and use as a defense against natural enemies, had significantly lower survivorship due to predation in both the field and in the laboratory experiments compared to groups of larvae fed a diet with low aristolochic acid content. We also found that aristolochic acid does not deter the generalist predator Hippodamia convergens, the ladybird beetle, suggesting that this compound is not a universal predator deterrent as previously assumed. Thus, instead of finding a benefit to group feeding and chemical defense in cryptic larvae, we have found a negative impact of group feeding in this population of B. philenor. Based on this evidence, we speculate that other benefits of group feeding might be outweighing the negative consequences of increased predation during the first instar. Future research on chemical defense, aposematism, and aggregative feeding should take into consideration that chemical defenses might not be universally effective against all natural enemies.

Abstract: A ubiquitous problem for all foragers is the trade-off between acquiring food energy while simultaneously avoiding the risk of predation. In central montane Alberta I modelled how ungulate forage changes with succession within cutblocks and the implications for forage availability to ungulates under current harvest regimes. Because cutblocks are discrete patches in space, I developed a dynamic state variable model for an ungulate to explore under what conditions an individual forager could (1) behaviourally avoid predation within a patch through inactivity, (2) overcome patch isolation when confronted with predation during transit between patches, and (3) alter patch use across a home range to optimize fitness. The model includes the requirement to process forage into energy through rumination behaviour that constrains foraging, and compares outcomes under a time-minimizing (sigmoid) and energy maximizing (linear) fitness functions. When an ungulate is in high energetic state, inactivity provides an effective behavioural refuge, or animals prioritize safety over energy gain, individuals avoid predation within patches reducing the need to move between patches. When energy acquisition is prioritized, individuals are at a low energetic state, or within patch anti-predator behaviours are ineffective, individuals move among patches to avoid predators in space, and configuration of the patches influences fitness. When model results were qualitatively compared to activity patterns and cutblock use of female, GPS-collared elk appear to follow a time minimizing strategy in their patch use across the home range and with their activity within riskier patches. I discuss the implications of these findings for the management of elk and cutblocks in west central Alberta.

Current research suggests that viewing complex scenes composed of a background and a negative, centralized image results in an emotion-induced memory trade-off. This trade-off is often characterized by high rates of memory accuracy for negative central images at the expense of a neutral background. In the present study, I explored whether the same trade-off effect is present for positive emotional stimuli. Therefore, when viewing complex scenes composed of a background and a positive central image, do people tend to remember the positive image more than they do the background? I examined two related research questions: (1) will positive scene components elicit an emotional memory trade-off effect? and (2) how does the passage of time, with and without sleep, influence positive scene components in comparison to negative scene components? Participants were separated into a sleep group and a wake group. The experiment consisted of two parts: the first was a viewing of 90 compound scenes and the second included a memory recognition test. Although the trade-off effect was present for negative valence items as well as positive objects, no main group effect was found. In other words, the emotional memory trade-off effect was not enhanced with sleep.

The global spread of fouling invasive species continues despite the use of antifouling biocides on vessel hulls. Furthermore, previous evidence suggests that non-indigenous species (NIS) introduced via hull fouling may have been selected for metal tolerance. Consequently, this process of selection may have then enhanced their introduction and establishment success in metal-polluted environments. This thesis examines the basis of copper tolerance in the non-indigenous bryozoan Watersipora subtorquata, and whether this successful NIS has evolved to benefit from a common contaminant in the marine environment. Using a series of laboratory-based experiments I found that tolerance to copper in W. subtorquata is a heritable genetic trait that varies on an individual basis. While there was no difference in tolerance between sites within an estuary for larval W. subtorquata, there was a significant interaction between parental colony and copper, with large variation in the response of colony offspring within sites. Larval size differed significantly both between sites and between colonies and was positively correlated with tolerance. In adult W. subtorquata colonies there was individual variation in tolerance to a gradient of copper concentrations and in the ability to recover from exposure to copper. Growth during and after exposure appear to be separate traits, while a trade-off between growth in control and copper environments during exposure suggests a cost to tolerance. The genetic variation present within this species indicates that further evolutionary change is possible under strong directional selection. The relationship between W. subtorquata and copper was further examined in field-based experiments. Copper appears to act as a settlement cue for W. subtorquata larvae by significantly increasing recruitment, although short term fitness costs were associated. Exposure to copper during initial settlement decreased recruit size and resulted in greater post-settlement mortality. In contrast, long term exposure to copper post-settlement significantly increased growth and reproductive fitness. The negative consequences of initial exposure during recruitment appear to be outweighed by the benefits of long term exposure which significantly increased overall fitness. In summary I have found that tolerance to copper is a heritable trait in W. subtorquata. Moreover, in an entirely novel finding, it appears that W. subtorquata has evolved to benefit directly from copper pollution, as well as indirectly through reduced competition from less tolerant species.

Abstract: Sheet and film forming processes refer to a set of processes that have a 2-dimensional sheet or film as their output. They are typically characterized by a scanning sensor which moves between the edges of the sheet in a periodic manner. This work is concerned with control and monitoring of such processes. There are three main contributions in this study. The first and foremost contribution is the reformulation of the Linear Quadratic Gaussian (LQG) objective function to give one the ability to trade-off between control over either dimension of the sheet. The second contribution is a method to derive the LQG trade-off surface between output variability in either dimension and input variance. The third contribution is a set of data driven techniques for performance assessment of these processes. Simulation results using the model used by Bergh and MacGregor (1987) are provided to support the proposed methods.

We often make decisions repeatedly. In these repeated-decision situations, consumers' prior knowledge and experiences based on consumption have been assumed to influence their current choice processes and outcomes. However, the research literature is currently silent as to how the influence of prior decision processes or outcomes operates in making subsequent decisions. To fill this gap, this dissertation investigates the impact of previous decisions on subsequent ones. We propose that the decision structure of an initial decision can differentially affect a subsequent one. Specifically, we compare the impact of trade-off- (i.e., the decision when no option is superior to the other option among all attributes) versus dominance-related initial decisions (i.e., the decision when one option is superior to and at least not inferior to the other option among all attributes). Based on the different research streams, we suggest competing predictions regarding the role of previous decision structure on subsequent choices. One stream of research from resource- or effort-based explanations (e.g., effort-as-information and resource availability) suggests that the tendency to keep a previous choice will be stronger in the trade-off versus the dominance condition. On the other hand, the other research stream from non-resource- or non-effort-based explanations (e.g., justification and regret/negative emotional research) suggests the opposite prediction (i.e., the tendency to keep a previous choice will be stronger in the dominance versus the trade-off condition). In six studies, we found empirical evidence for the impact of previous decisions on subsequent ones. We mainly found that people who made an initial trade-off decision (vs. those who made a dominance decision) were more likely to stick to their previously chosen alternative. In addition, the empirical studies supported the notion that the underlying mechanism of this pattern was due to the "resource availability" mechanism rather than the "effort-as-information: previous effort spending as a source of information for judgment" mechanism.

The focus of this dissertation is on improving decision-maker trade-offs and the development of a new constrained methodology for multiple response surface optimization. There are three key components of the research: development of the necessary conditions and assumptions associated with constrained multiple response surface optimization methodologies; development of a new constrained multiple response surface methodology; and demonstration of the new method. The necessary conditions for and assumptions associated with constrained multiple response surface optimization methods were identified and found to be less restrictive than requirements previously described in the literature. The conditions and assumptions required for a constrained method to find the most preferred non-dominated solution are to generate non-dominated solutions and to generate solutions consistent with decision-maker preferences among the response objectives. Additionally, if a Lagrangian constrained method is used, the preservation of convexity is required in order to be able to generate all non-dominated solutions. The conditions required for constrained methods are significantly fewer than those required for combined methods. Most of the existing constrained methodologies do not incorporate any provision for a decision-maker to explicitly determine the relative importance of the multiple objectives. Research into the larger area of multi-criteria decision-making identified the interactive surrogate worth trade-off algorithm as a potential methodology that would provide that capability in multiple response surface optimization problems. The ISWT algorithm uses an ε-constraint formulation to guarantee a non-dominated solution, and then interacts with the decision-maker after each iteration to determine the preference of the decision-maker in trading-off the value of the primary response for an increase in value of a secondary response. The current research modified the ISWT algorithm to develop a new constrained multiple response surface methodology that explicitly accounts for decision-maker preferences. The new Modified ISWT (MISWT) method maintains the essence of the original method while taking advantage of the specific properties of multiple response surface problems to simplify the application of the method. The MISWT is an accessible computer-based implementation of the ISWT. Five test problems from the multiple response surface optimization literature were used to demonstrate the new methodology. It was shown that this methodology can handle a variety of types and numbers of responses and independent variables. Furthermore, it was demonstrated that the methodology can be successful using a priori information from the decision-maker about bounds or targets or can use the extreme values obtained from the region of operability. In all cases, the methodology explicitly considered decision-maker preferences and provided non-dominated solutions. The contribution of this method is the removal of implicit assumptions and includes the decision-maker in explicit trade-offs among multiple objectives or responses.

Over the past decade, modern technologies such as Direct Injection (DI), Exhaust Gas Recirculation (EGR), Variable Geometry Turbocharging (VGT), and most recently, High Pressure Common Rail (HPCR) fuel injection have narrowed the gap between Diesel engines and Spark-Ignition (SI) engines in terms of environmental impact. These improvements in Diesel engine technology are accompanied by several challenges. The modern diesel engine is a complex nonlinear system that must be controlled optimally to ensure that it meets the environmental regulations while maintaining its performance. One-loop-at-a-time tuning is no longer effective due to the complexity of the system. Currently, a significant part of time is spent in the optimization of engine performance, a luxury industry cannot afford in the increasingly competitive scenario. For this reason, the automotive industry is realizing the significance of model based and multivariate control. Fuel path control has mostly been of a feedforward nature due to lack of appropriate sensors. With sensors for emissions such as NOX beginning to become commercially viable, a need has arisen to formulate control paradigms that incorporate the emission optimization problem into the feedback control framework. Methodologies for modeling and feedback control of the NOX-BSFC trade-off are explored. Two different types of subsystems of a common high-speed Diesel engine are modeled based on the chosen input parameters. Linear models for the open-loop torque and NOX dynamics are proposed for each subsystem based on models published in the literature. These models are identified and demonstrated to be capable of reproducing essential system properties. A generic control paradigm is proposed that enables the explicit incorporation of the trade-offs between different output variables directly within the control framework. Two different instances of a constrained NOX-BSFC trade-off are demonstrated to exist in a Diesel engine. The first example relates to the existence of a NOX-BSFC trade-off in the context of torque control in the fuel path. The second example demonstrates the existence of a similar trade-off in the context of air flow control. The above control paradigm is applied to each example for the feedback control of the NOX-BSFC trade-off.

Seed mass is thought to be a critical plant trait, which determines patterns of species abundance. This is based on a presumed trade-off between seed size and seed number, and a hypothesised relationship between recruitment and seed size. The relationship between seed mass and abundance was examined in a long-term study of 71 tussock grassland species of south-eastern New Zealand. This study was unique in that the colonisation and extinction rates were also known for the species. A significant relationship was found between colonisation ability and seed mass. Species with intermediate sized seeds were better colonists. This result indicates that colonising ability is related to both dispersal and recruitment. Colonisation success is expected to be important factor determining abundance patterns in communities. However, small-seeded Hieracium species were found to be the most abundant species. These results indicate that, in south-eastern New Zealand tussock grassland communities seed mass is an not a important factor influencing community abundance and structure. More likely a complex interaction of a number of key plant traits influence species abundance.