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Made available in DSpace on 2014-12-17T14:06:48Z (GMT). No. of bitstreams: 1 HaroldoRAM.pdf: 1140599 bytes, checksum: 95a046b646a7cfa0d6cf0153f138783f (MD5) Previous issue date: 2008-08-20 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Titanium is a biomaterial widely employed in biomedical applications (implants, prostheses, valves, stents). Several heat treatments are usually used in order to obtain physical properties required to different applications. This work studied the influence of the heat treatment on microstructure of commercial pure titanium, and their consequences in growth and proliferation of MC3T3-E1 cells. Discs of titanium were treated in different temperatures, and characterized by optical microscopy, image analysis, wettabillity, roughness, hardness and X-ray diffraction. After the heat treatment, significant modifications in these properties were observed. Pattern images of titanium, before and after the cell culture, were compared by overlapping to analyze the influence of microstructure in microstructure and preferences guidance cells. However, in general, titanium discs that showed a higher residual strength also presented an increase of cells numbers on surface / O tit?nio como biomaterial ? amplamente utilizado em dispositivos biom?dicos (implantes, pr?teses, v?lvulas, stents entre outros). Diversos tratamentos t?rmicos s?o usualmente utilizados na obten??o das propriedades necess?rias para as diferentes aplica??es. Este trabalho estudou a influ?ncia desses tratamentos na microestrutura do tit?nio comercialmente puro e suas conseq??ncias no crescimento, forma e prolifera??o de c?lulas pr?-osteobl?stica. Para tanto foram utilizados discos de tit?nio submetidos a diferentes tratamentos e caracterizados por microscopia ?tica, an?lise de imagens, molhabilidade, rugosidade, dureza e difra??o de raios-X. Ap?s os tratamentos t?rmicos foram verificado modifica??es significantes nestas propriedades. Padr?es de imagens de superf?cies do tit?nio antes e ap?s a cultura de c?lula foram comparados atrav?s de sobreposi??o para analisar a influ?ncia da microestrutura na resposta biol?gica, n?o sendo verificadas correla??es entre a microestrutura e as prefer?ncias orientacionais das c?lulas. Entretanto de um modo geral verificou-se que os discos que presentaram maior estado de tens?o residual apresentaram tamb?m maior n?mero de c?lulas em sua superf?cie

This study investigates the cues used for predator recognition by wild-living untrained birds great tits (Parus major). The experimental approach is used to test the reaction to the variously modified dummies of sparrowhawk (Accipiter nisus) and pigeon (Columba livia f. domestica) under laboratory conditions. The role of key features (yellow eye, hooked beak and talons), colour and size is tested. The results imply that the presence of raptor-specific features is mostly necessary but not sufficient to recognize predator in the presented dummies. Following research revealed that the part of the variability in response of great tits can be taken on the account of personality.

Unlike infrastructure-based networks, mobile ad hoc networks consist of nodes independent of any infrastructure. Cooperation among these nodes is essential for the sustenance of multi hop communication. However, battery and bandwidth constraints may lead nodes in an ad hoc network to adopt energy- and bandwidth-conserving strategies. As routing and packet forwarding are end results of cooperation, network performance is affected when nodes in the network behave selfishly to conserve their resources. Our work involves characterizing selfish behavior by nodes in ad hoc networks and assessing the effectiveness of adopting tit for tat based strategies, which are meant to discourage selfish behavior in the network. We show that in an ad hoc network where other nodes act selfishly to conserve their resources, a node can benefit by adopting a generous tit for tat strategy. We also show that a node can gain benefit by avoiding selfish nodes in an ad hoc network, adopting a strategy that we call generous tit for tat with selfish avoidance (GTFT-SA) To analyze the effectiveness of cooperation strategies in selfish ad hoc networks we create an emulation environment based on virtualization. Such an emulation environment is more flexible to changes and is simpler to replicate than real life testbeds, while providing higher fidelity than simulations. / Master of Science

Great tits (Aves: Passeriformes; Parus major) and blue tits (Parus caeruleus) nested in boxes in Wytham Woods near Oxford. The breeding densities of both species were limited by the availability of nest sites. The larger great tits were dominant in obtaining nest boxes. This was most important where breeding sites were scarce. The two species did not maintain interspecific territories or interfere with interspecific nest site spacing beyond the immediate vicinity of the nest. Blue and great tit numbers fluctuated in parallel where nest sites were not limiting resources. Annual changes in breeding numbers of great tits were negatively related to blue tit breeding density but great tit density did not seem to affect changes in the blue tit population. Overlap in the feeding sites of blue and great tits was greatest during the summer and interference competition was lowest at this time. The nestling diets of the two species were very similar. Despite an apparent abundance of food for nestlings, adults were pressed to feed large broods. Food for nestlings was probably a limiting and depletable resource. The date of clutch initiation of great tits, but not blue tits, was retarded at high densities of blue or great tits. The clutch sizes of both species were probably negatively affected by high breeding densities of congeners but the results were not clear cut. Heavy great tit fledglings are most likely to survive to breed. Great tit fledglings were heavier at low densities of blue tits. An experiment in which blue tit young were removed from a section of the Woods, showed that great tit nestlings were heavier and developed faster, and that female condition was better, than in a control section or section where blue tit broods were supplemented. In terms of resource competition, blue tits were the better scramble competitors and great tits the better interference competitors.

Explaining variation between individuals is a central concept in ecology. Phenotypic variation is the product of genes, environments and their interactions. In contrast to genotypes which are fixed within individuals, environments vary considerably in time and space and have measurable effects on phenotypic quality between and within individuals. The aim of the current work was to identify environmental sources of life-history variation in a wild population of the great tit. The size of Thiessen polygons formed around c. 8000 nestboxes occupied over a 41 year period was used to estimate breeding density at the level of the individual. Linear mixed modelling showed that birds breeding in large territories laid more eggs and produced heavier fledglings that were more likely to survive to breed, than those in smaller territories. Systematic capping of territory sizes revealed that birds breeding in territories more than 2ha in size were unconstrained by density. This method of measuring individual density identified important relationships between density and life-histories and allowed for the accurate separation of other environmental effects usually confounded by density. For example, the life-histories and breeding density of woodland passerines often both vary with distance from the woodland edge. Using the Thiessen polygons to control for density we were able to independently examine edge effects on life-histories. Results confirmed higher density at edges and independently showed that birds near the woodland edge tended to lay smaller clutches of larger eggs later in the season, than birds away from the edge, probably due differences in habitat quality. A further use of Thiessen polygons was to determine the scale at which to measure oak availability in the vicinity of each occupied nestbox. Birds breeding in oak rich polygons laid larger clutches, earlier in the season and had heavier nestlings than birds in oak poor polygons, independently of density and edge effects. What's more, including oaks in life-history models, reduced or eliminated the effect of the Thiessen polygons, suggesting that density dependent life-histories are to some extent explained by reduced oak availability at high density. Clutch size, fledgling mass and recruitment were also found to correlate with local soil calcium. Analyses performed at several spatial scales found the greatest effect of calcium at scales of c.500m. This figure may indicate the average distance females were travelling to obtain calcium rich food during periods of high demands. That breeding environments strongly affect life-histories has been demonstrated by the above work. However, no correlations were found between natal environment and the subsequent life-histories of recruited individuals, probably due to high mortality in great tits, which favours current condition over any character that conveys benefits later in life. This result shows that long-term effects of rearing environments cannot be assumed as it depends on the life-history conditions under which they are found. The results of this study suggest a pervasive role of fine-scale environment variation in determining the life-histories of individual great tits. Moreover, the study demonstrates the efficacy of GIS to model such variation and applying it to explaining life-history variation in long-term databases.

Part One is an investigation of the dawn chorus in the Great Tit. The major conclusions are as follows: Foraging and singing are partly incompatible because of the temporal and spatial separation of microhabitat conditions required for each activity. The dawn chorus occurs at a time of day when: a) foraging efficiency is limited by low light intensity and possibly by lack of mobility of the prey due to low temperature; b) acoustic communication is more efficient than visual displays because of poor visibility and an enhanced sound transmission; c) the rate of territorial intrusion is at its daily peak. Great Tit's readiness to sing and react agonistically towards a territorial intruder is enhanced by experimentally lowering profitability of feeding, but it does not appear to be affected by time of day. Restricting access to food early in the morning leads to higher body weight in the evenings as an anticipatory compensation. Part Two is a study of sampling strategies based on the statistical decision paradigm known as the Two-Armed Bandit problem. I studied transition behaviour in foraging experiments using concurrent variable ratio schedules. The birds' foraging behaviour approximated the predictions of a dynamic programming algorithm that calculates the optimal balance between exploring and exploiting for finite time horizons. The birds' response to patch diversity and time horizon was closer to molar maximization (total rewards over a certain period) than to molecular maximization (maximising the instantaneous probability of reward). When the environment is not totally stable these two possibilities conflict, and my results supported molar maximization. Part Three investigates the trade-off between maximising foraging efficiency and efficient territorial defence. Great Tits behaved close to the predictions of the Marginal Value model when there were no territorial intrusions, but modified their feeding behaviour in the predicted way when the probability of intrusion was higher.

This thesis explores the far-reaching impacts of sexual conflict over care on a suite of traits in the penduline tit family (Remizidae), further confirming the intricate relationships between parental care, mating systems and sexual selection. The results reveal the first genetic phylogeny of this family and suggest that uniparental care evolved once in this group. The transition to uniparental care is associated with rapid evolution of male plumage ornaments most likely driven by increased sexual selection. The results also suggest a relationship between male care and the likelihood of paternity on an evolutionary time-scale, as the biparental species exhibit much lower levels of promiscuity than the uniparental European penduline tit. Increased promiscuity was also found to impact sperm morphology in the penduline tits and allies with greater sperm length uniformity in more promiscuous species. This sperm trait was also discovered to co-vary with a sexually selected plumage trait in the European penduline tit suggesting potential interactions between female mate choice and male fertility. An investigation into genetic diversity within the Sylvioidea super-family finds large variation but does not suggest any link between promiscuity and genetic diversity as predicted if promiscuity maintains a higher effective population size in these passerines. The work highlights the interlinked relationships between parental care, mating systems and sexually selected traits, which are increasingly studied in concert. The consequences of sexual conflict over care appear to be far-reaching in the penduline tits, however the degree to which they feedback upon each other and the effect that it has on speciation remains to be seen. The penduline tits further prove their ability to provide valuable insight into the evolution of sexual conflict.

There is ample evidence that climate change is impacting on phenology and it has been suggested that this may generate trophic mismatches. A key system for investigating phenology and trophic mismatch occurs in spring in temperate deciduous woodlands, where folivorous caterpillars and their predators, insectivorous passerines, are reliant upon ephemeral resources for reproductive success and survival. However, studies are primarily conducted within single-site, oak- (Quercus sp) dominated woodland and focus on a single caterpillar species, winter moth (Operophtera brumata), despite these passerines being habitat generalists with large geographic ranges. It remains to be seen whether insights gained from these studies can be generalised on the landscape scale across different habitats. In this thesis, I explore the extent to which geographic and habitat variation operates in this system and attempt to expand the system beyond a linear single-species food chain into a more biologically realistic multi-species food web. I also identify the most important environmental factors predicting the phenology of the passerines to allow better predictions of how their phenology could alter under future climate change scenarios. To address these questions, I established a novel 220km transect of Scotland incorporating 40 field sites that vary in elevation and the type of deciduous woodland habitat, monitoring six blue tit (Cyanistes caeruleus) nestboxes, tree and invertebrate phenology and abundance, at each site throughout the springs of 2014-16. Firstly, I assess how blue tit occupancy and productivity are affected by the variation in fine-scale woodland habitat, latitude, elevation and prey availability that exists along the transect (Chapter 2). I find that habitat variables strongly affect fledging success but not occupancy or clutch size, whilst occupancy exhibits biogeographic trends, revealing that the relationship between breeding decisions and outcomes differs among habitats and implies that it may be difficult to generalise results from one habitat to others. Next, I aim to identify the environmental aspects which play a role in regulating blue tit reproductive phenology by examining the ability of temperature, tree phenology, invertebrate prey abundance and photoperiod to predict nest initiation and laying dates (Chapter 3). I find that night-time temperature in early spring is the most important predictor of both nest initiation and lay date (slopes ~ -3days/°C) and I suggest that this supports the hypothesis that temperature acts as a constraint on timing rather than a cue. Invertebrate abundance is also a positive correlate of lay date, possibly allowing fine-tuning of timing. This knowledge provides clearer foundations from which to predict future phenological change and possible trophic mismatch in this system. There is the potential that the apparent effect of temperature on blue tit reproductive phenology is indirect and mediated by diet, which is largely undescribed in the period prior to breeding. Therefore, in Chapter 4 I examine how blue tit diet varies across habitat, geography and time, and whether there is a dietary cue utilised to initiate breeding phenology, using data from metabarcoding faeces collected from nestbox-roosting adults in early spring. Geographic variation in diet is substantial, with high site-to-site dietary turnover (β-diversity), as well as high turnover along the elevational and latitudinal gradients studied. Dietary α-diversity (richness) is unaffected by geographical variables, but increases over time, with significant pre-breeding dietary increases in Lepidoptera and Hemiptera signifying a possible cue. In addition, these data provide the most comprehensive next-generation insights into the diet of a wild bird to date and identify 432 prey taxa. Finally, I analyse how biogeographic and habitat variables affect the phenology, abundance and diversity of caterpillars (Chapter 5). Host tree species’ varied significantly in their likelihood of hosting a caterpillar, with oak and willow (Salix sp.) the most likely. Biogeography had less effect on the likelihood of caterpillar occurrence, but elevation delayed peak date by 3.7 days/100m increase. There was also support for the spring caterpillar peak being dominated by a few key species, with over half of all caterpillars identified being of just three of the 62 total species, including winter moth. These findings contribute to understanding how the temporal distribution of caterpillars varies across habitats on the landscape scale. Taken together, the findings of this thesis reveal considerable geographic and habitat variation throughout this system, in both the composition of the food web and the impacts on blue tit productivity, demonstrating why caution must be exercised when extrapolating findings from one location or habitat to others.

Changes in climate shape biological populations. They can alter spatial distributions, the timing of life history events, and even the species themselves. We are now experiencing a period of rapid directional climate change, alongside seasonal fluctuations. This thesis investigates temporal changes in life history events, phenology, as a climate response. I explore the causes and population level consequences of change in breeding phenology of two wild bird populations from Wytham Woods, UK. I test how great tits (Parus major) and blue tits (Cyanistes caeruleus) achieve temporal synchrony between the peak demands of their breeding and the peak abundance of their prey species (winter moth caterpillars - Operophtera brumata) in an inter-annually variable environment. I demonstrate great tit (Parus major) incubation behaviour fine-tunes the timing of hatching in response to ambient temperatures right up until hatching (Chapter two). Temperatures within the nest box, however, appear to play little role in the breeding phenology of blue tits (Cyanistes caeruleus) (Chapter two). I discuss the merits and limitations of statistical approaches for cue identification (Chapter six), finding the method and time period of data used both affect the cue identified and predictive accuracy. The second part of this thesis explores the influence of a directionally changing environment on great tit phenology. I use an integral projection model (IPM) to predict population dynamics over the 21^st century, showing that if the cues used by both interacting species change sufficiently closely, temporal synchrony can be maintained through both phenotypic plasticity and micro-evolution (Chapter 5). However, if the cues diverge mismatch will arise (Chapter 5) causing population declines when certain thresholds are passed (Chapter 4). This work contributes to understanding how phenological synchrony is achieved, how it might change in the future, and its population impacts. In Wytham Woods it appears that great tits have a great deal of flexibility in multiple components of their breeding cycle, allowing them to retain synchrony with their caterpillar prey in a fluctuating environment. These birds are relatively resilient to negative phenological impacts from climate change. Only if the cues used by the predator and prey completely diverge do we predict consistent declines in population size during this century.