Dissertations / Theses on the topic 'Flower colour'

Phenotypic differences between species and populations can reveal much about how they have adapted and responded to a complex set of environmental cues. Studies have shown that genetic control of some traits is centralised to single genomic regions, while others are regulated at many unlinked loci dispersed throughout the genome. One trait that shows an enormous degree of variation between plant species is flower colour, and its tractability makes it an ideal trait for studying genetic differences underlying species differentiation. Antirrhinum majus has long been used as a model for studying floral traits, including colour. The 20-30 wild Antirrhinum species use diverse patterns on their flowers, formed by producing and accumulating magenta anthocyanins and yellow aurones in different tissues, to attract pollinators. In this project, I sought to genetically map flower colour phenotypes to the Antirrhinum genome. Several Antirrhinum species were crossed to A. majus to generate segregating populations. I used a combination of bulked segregant analysis, individual genotyping of segregating populations and analysis of genome sequences from wild accessions to test whether genes governing each colour trait were concentrated at particular loci or dispersed across many chromosomes. I found that variation in magenta not previously characterised maps to the known ROSEA-ELUTA (ROS-EL) locus where transcription factors regulating anthocyanin production are encoded. Yellow phenotypes from three species mapped to chromosome 2, where there is reduced recombination between A. majus and many wild species, and where an aurone biosynthetic enzyme is encoded. However, there appear to be some additional modifiers of flower colour in these species, not linked to the ROS-EL and chromosome 2 loci. These results fit neither the central- nor dispersed-control models of genetic control, but rather an intermediate hypothesis - that flower colour can be changed by selection acting on a modest number of loci spread throughout the genome.

Flowers’ colours are an essential element of their ability to attract visits from pollinators. However, the colours as they appear to human observers can differ substantially from their appearance to insect pollinators, and so it is essential to consider pollinator vision in any study of the ecology of flower colour. In this thesis I describe how I have overseen the development of an online database to provide accurate information on floral spectral reflectance measured without human observational bias. This resource allows a more accurate consideration of flower colours in future studies, and permits investigations of flower colours within and across habitats. Using the records in this database, I analysed flowers from two European habitats for spatial or temporal changes, modelling the colours according to insect visual perception. I discovered that the insect-colour composition of the plant communities does not change either along an altitudinal gradient or throughout the year. These novel and ecologically-relevant analyses contradict previous observational studies, but support the theory of a pollination “market” in which flowers compete for pollinator visitation. I then describe my experimental investigations into the visual capabilities of two pollinators and how this may relate to what colours of flowers they visit. Firstly I study the foraging behaviour of bees under spatially inconsistent illumination and how this impacts on their choice behaviour. I revealed patchy light can have measurable effects on bee foraging behaviour: they intentionally choose familiar over unfamiliar illumination, which may impact on the flowers they visit in complex natural environments. Secondly, I detail the new evidence for a red-sensitive photoreceptor in South African monkey beetles, a major pollinator in a habitat containing many longwavelength- reflecting flowers, which are not classically “attractive” to bees. Throughout this thesis, I explore how pollinator vision has shaped the evolution of flower colours in different contexts.

Pollinating insects are important for many plants and for the human population. To be able to monitor pollinators and assess improvements made for them, it is important to get information about pollinator population changes. Therefore, it is essential that the methods used to collect data are accurate (i.e. that they represent the pollinator fauna). One commonly used method is pan-traps, but this method is suggested to be affected by the abundance of surrounding flowers. The results in the present study showed that catches in pan-traps can be affected by flower cover and the colour of the flowers, depending on which colours are preferred by the insects. The effects differed when looking at a larger scale (2-6 ha) and a smaller scale (25 m2) around the pan-traps. When comparing cover of flowers with catches in pan-traps in the small scale there were some results that showed linear positive correlations (expected), but also, negative linear and quadratic correlations. In contrast, in the large scale there were no significant positive linear correlations. When comparing catches in hand-net and pan-traps, only in one out of six taxonomical groups there were a correlation. The results in this study show that catches in pan-traps can be misleading if catches are done to survey pollinator population fauna and the cover of flowers is not considered.

The perceived colour of an object depends on its spectral reflection and spectral composition of the illuminant. Upon illumination change, the light reflected from the object also varies. This results in a different colour sensation if no colour constancy mechanism is available to form consistent representations of colours across various illuminants. We explore various colour constancy mechanisms in an agent-based model of foraging bees selecting flower colour based on reward. The simulations are based on empirically determined spatial distributions of various flower species in different plant communities, their rewards and spectral reflectance properties. Simulated foraging bees memorise the colours of flowers experienced as being most rewarding, and their task is to discriminate against other flower colours with lower rewards, even in the face of changing illumination conditions. The experimental setup of the simulation of bees foraging under different photic environments reveals the performance of various colour constancy mechanisms as well as the selective pressures on flower colour as a result of changing light. We compared the performance of von Kries photoreceptor adaptation and various computational colour constancy models based on the retinex theory with (hypothetical) bees with perfect colour constancy, and with modelled bees with colour blindness. While each individual model generated moderate improvements over a colour-blind bee, the most powerful recovery of reflectance in the face of changing illumination was generated by computational mechanisms that increase perceptual distances between co-occurring colours in the scene. We verified the results of our model using various comparisons between modelled bees’ performance and that predicted by our models, as well as exploring the implications for flower colour distribution in a variety of representative habitats under realistic illumination conditions.

Unravelling the genetic nature of reproductive isolation is crucial to understanding the maintenance of diversity between populations. In hybrid zones, loci that establish a barrier to gene flow between populations remain divergent, whereas neutral unlinked loci become mixed. In those instances, fit allelic combinations across several loci can be maintained through selection, but this is antagonized by gene flow and recombination. Here, I show that particular allelic combinations in a linked cluster of loci responsible for a flower colour polymorphism between two A. majus subspecies are maintained despite recombination in a hybrid zone. I reveal that a known locus that controls the magenta flower colour of the subspecies, ROSEA (ROS), is highly divergent between them, compared with most of the genome. The divergence region extends downstream of ROS, likely due to selection on another linked, but unidentified, locus that also controls flower colour, ELUTA (EL). Fine-mapping experiments identified an interval containing EL and regions within ROS that control different components of the magenta phenotype. Transcriptome analysis from flower buds suggests that MYB-like transcription factors within the mapped intervals control this trait. ROS and EL interact epistatically, meaning that the phenotype of an individual depends on the particular allelic combination it has for these loci. In the hybrid zone, markers in ROS and EL are in high linkage disequilibrium, but ~5% of recombinant haplotypes were found in the population. Recombinant haplotypes modify the phenotype of the flowers in relation to the parental subspecies, and therefore may be selected against. The data suggest that allelic combinations in ROS-EL are maintained by selection, despite gene flow and recombination between the two subspecies. This work reveals the consequences of selection, gene flow and recombination in shaping the patterns of genomic divergence in linked clusters of loci that establish an isolating barrier between populations.

Impatiens walleriana Hook.f. is a popular bedding plant with a variety of flower colours excepting yellow. Transfer of this characteristic could be achieved through somatic hybridization, thus this study was an attempt to establish the basic parameters of tissue and protoplast culture. The condition of the stock plants and surface sterilisation techniques are important for this species. Most tissues responded to trials for callus induction with rhizogenesis. Evaluation of media and plant growth regulator combinations revealed that axillary shoot proliferation was most efficient on MS medium with 3.0 mg/L BAP and 0.1 mg/L IBA. Protoplast isolation was most effective in 0.5% w/v cellulase and 0.25% w/v pectinase with 0.25 M mannitol and 0.25 M glucose yielding 2.70 $ times$ 10$ sp5$ protoplasts per gram of leaf tissue. The presence of mucous, raphids and excessive debris inhibited successful culture of leaf mesophyll protoplasts. Cotyledon protoplasts show promise for such investigations.

Trichogramma carverae Oatman and Pinto is mass-released for biological control of the leafroller pest, light brown apple moth, Epiphyas postvittana (Walker) in Australian vineyards. Parasitoid performance can, however, be constrained by a lack of suitable adult food and no information is available on the effect of nectar on the parasitism and longevity of T. carverae. To address this, the effect of alyssum, Lobularia maritima (L.) flowers on E. postvittana parasitism was studied in a vineyard experiment with and without releases of T. carverae. Egg parasitoid activity was assessed with E. postvittana egg 'sentinel cards' and no parasitism was recorded in plots without T. carverae releases. Where T. carverae were released, there was no significant enhancement of parasitism by the presence of L. maritima flowers. Three hypotheses were subsequently tested to account for the lack of an effect: (i) T. carverae does not benefit from L. maritima nectar, (ii) T. carverae was feeding on nectar from other flowering plants (weeds) present in the vineyard, (iii) T. carverae was feeding on sugars from ripe grapes. A growth-cabinet experiment using potted L. maritima plants with and without flowers did not support hypothesis one. No parasitism was recorded after day two for T. carverae caged without flowers whilst parasitism occured until day eight in the presence of flowers. A laboratory experiment with common vineyard weeds (Trifolium repens, Hypochoeris radicata, Echium plantagineum) as well as L. maritima did not support hypothesis one but gave partial support to hypothesis two. Survival of T. carverae was enhanced to a small but statistically significant extent in vials with intact flowers of L. maritima, white clover (T. repens) and catsear (H. radicata) but not in vials with flowering shoots of these species from which flowers and flowering buds had been removed. Paterson's curse (E. plantagineum) flowers had no effect on T. carverae survival. In a laboratory study, punctured grapes significantly enhanced T. carverae survival compared with a treatment without grapes, supporting hypothesis three. Trichogramma carverae performance in the field experiment was probably also constrained by relatively cool and wet weather. Further work on the enhancement of T. carverae efficacy by L. maritima and other carbohydrate sources is warranted. Greenhouse and field experiments were conducted to investigate whether T. carverae benefit from different groundcover plant species. Ten T. carverae adults (<24h after eclosion) were caged with different groundcover species and a control with no plant materials. Epiphyas postvittana egg sentinel cards were used to measure parasitism and longevity was recorded visually. Survival and realised parasitism of T. carverae was significantly higher in L. maritima than in Brassica juncea, Coriandrum sativum, shoots of these species from which flowers had been removed and nil control treatments. A similar experiment with Fagopyrum esculentum (with- and without-flowers) and a control treatment showed that survival was significantly higher in intact F. esculentum than in without-flower and control treatments. There was no significant treatment effect on parasitism in the early stages of that experiment, though parasitism was recorded in the presence of F. esculentum flowers for 12 days, compared with 6 days in other treatments. Higher parasitism was observed in intact Borago officinalis than in the flowerless shoot, water only and no plant material control treatments in a third experiment. There was no significant treatment effect on parasitism. Fitted exponential curves for survival data differed significantly in curvature in the first, second and third experiments but the slope was a non-significant parameter in the second and third experiments. In a second series of laboratory experiments, one male and one female T. carverae were caged with groundcover species to investigate male and female longevity and daily fecundity. Both male and female longevity in F. esculentum and L. maritima treatments were significantly higher than on shoots of these species from which flowers had been removed, and than in the control treatments. Daily fecundity was significantly greater in the intact L. maritima treatment than in all other treatments. Fitted exponential curves for daily fecundity differed significantly in position and slope but not in curvature. There was no significant treatment effect on longevity or parasitism when a male and female were caged with intact B. juncea, B. officinalis or without-flower of these species, nor in the treatment with no plant materials. No parasitism was observed in a survey of naturally occurring egg parasitoids on two sites close to Orange and Canowindra in New South Wales, illustrating the importance of mass releases of T. carverae in biological control of E. postvittana. In an experiment on the Canowindra site, parasitism was significantly higher on day one and day two after T. carverae release when with-flower treatments were compared with without-flower treatments. Parasitism was significantly higher in the F. esculentum treatment than in C. sativum, L. maritima, vegetation without-flowers and control treatments on these dates. On day five, parasitism was higher in C. sativum than in all other treatments. There was no significant increase in parasitism in a second experiment conducted on the Orange site. Coriandrum sativum, F. esculentum and L. maritima appear to be suitable adult food sources for T. carverae and offer some scope for habitat manipulation in vineyards The adults of many parasitoid species require nectar for optimal fitness but very little is known about flower recognition. Flight cage experiments showed that the adults of T. carverae benefited from L. maritima bearing white flowers to a greater extent than was the case for light pink, dark pink or purple flowered cultivars, despite all cultivars producing nectar. Survival and realised parasitism on non-white flowers were no greater than when the parasitoids were caged on L. maritima shoots from which flowers had been removed. The possibility that differences between L. maritima cultivars were due to factors other than flower colour, such as nectar quality, was excluded by dyeing white L. maritima flowers by placing the roots of the plants in 5% food dye (blue or pink) solution. Survival of T. carverae was lower on dyed L. maritima flowers than on undyed white flowers. Mixing the same dyes with honey in a third experiment conducted in the dark showed that the low level of feeding on dyed flowers was unlikely to be the result of olfactory or gustatory cues. Flower colour appears, therefore, to be a critical factor in the choice of plants used to enhance biological control, and is likely to also be a factor in the role parasitoids play in structuring invertebrate communities. Provision of nectar producing plants to increase the effectiveness of biological control is one aspect of habitat manipulation, but care needs to be taken to avoid the use of plant species that may benefit pest species. Greenhouse experiments were conducted to investigate whether the adult E. postvittana and larvae benefit from nectar producing groundcover species. Newly emerged E. postvittana adults were caged with different groundcover species and a honey-based artificial adult diet. The longevity of male and female E. postvittana when caged with shoots of borage (B. officinalis) and buckwheat (F. esculentum) bearing flowers was as long as when fed a honey-based artificial diet. This effect was not evident when caged with shoots of these plants from which flowers had been removed. Longevity was significantly lower than in the artificial diet treatment when caged with coriander (C. sativum) or alyssum (L. maritima) irrespective of whether flowers were present or not. There was no significant treatment effect on the lifetime fecundity of E. postvittana. A second experiment with mustard (B. juncea) (with- and without-flowers), water only and honey-based artificial adult diet showed no significant treatment effects on the longevity of male and female E. postvittana or on the lifetime fecundity of E. postvittana. The anomalous lack of a difference between the water and honey-based diet treatments precludes making conclusions on the value of B. juncea for E. postvittana. Two greenhouse experiments were conducted to evaluate the effects of groundcover species on the larval development of E. postvittana. In the first experiment, larval mortality was significantly higher in C. sativum, and L. maritima than in B. juncea, B. officinalis and white clover (T. repens) a known host of E. postvittana. Coriandrum sativum and L. maritima extended the larval period. In B. juncea and B. officinalis, mortality did not differ from that in T. repens. In F. esculentum, larval mortality was significantly higher than in T. repens. A short larval period was observed on B. juncea, B. officinalis and F. esculentum. Fitted exponential curves for larval mortality differed significantly in curvature between plant treatments. Similarly, successful pupation was significantly lower in C. sativum, F. esculentum and L. maritima than in T. repens. The percentage of successful pupation in B. juncea and B. officinalis did not differ from F. esculentum and T. repens. Fitted exponential curves for pupation differed significantly in curvature. A similar trend was observed in a second experiment with potted plants. The overall results suggest that C. sativum and L. maritima denied benefit to E. postvittana adults and larvae, so could be planted as vineyard groundcover with minimal risk of exacerbating this pest. Overall results suggest that T. carverae require nutrients to reach their full reproductive potential and flowers provide such nutrients. Lobularia maritima and C. sativum may be considered 'selective food plants' for T. carverae whereas F. esculentum appears to be a 'non-selective food plant'; both T. carverae and E. postvittana benefited from it. Fruits such as grapes can be used as food resources in habitat manipulation and this merits further research. This result also suggests that within species flower colour is an important factor for flower selection in habitat manipulation.

Orientador: Leonor Patricia Cerdeira Morellato
Resumo: A visão é o principal sentido utilizado pelos polinizadores para forragear, no qual a cor das flores é a primeira característica de atração. A percepção dos sinais de cores depende da coloração do segundo plano das flores, composto principalmente pelas folhas. Diferenças na composição das espécies e na estrutura da vegetação, e também na sazonalidade climática, podem interferir na cor do segundo plano de folhas em diferentes vegetações e estações, interferindo como os polinizadores percebem a flor. Portanto, a diversidade de cores das flores e os padrões de floração de uma comunidade podem estar relacionados com a composição de polinizadores e condições ambientais. Desta maneira, utilizando comunidades vegetais e considerando o sistema visual das abelhas, nós descrevemos e comparamos a diversidade de cores das flores e seus sinais, dando importância para a cor do segundo plano de folhas em duas vegetações sazonais tropicais e uma vegetação sazonal temperada. Em seguida, para vincular os sinais florais com a sazonalidade, nós analisamos a importância das síndromes de polinização levantadas, o padrão de floração, a influência da cor do segundo plano de folhas no padrão de cor das flores entre as estações. Nós encontramos diferenças na diversidade de cores das flores e confirmamos a influência da coloração do segundo plano de folhas, juntamente com a estrutura da vegetação e a intensidade da sazonalidade nos sinais florais exibidos em diferentes vegetações sazonais, de acordo co... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Vision is the main sense used to forage by pollinators being the flower colour the primary feature of attraction. Colour signals perception depend on the flower background colouration, mainly composed by leaves. Differences in species composition and vegetation structure, and also the seasonality, may change the leaf-background colouration of different vegetations and seasons, interfering how the pollinators perceive a flower. Therefore, flower colour diversity and flowering patterns of a community may be related to the pollinators’ composition and environmental conditions. Using a community level-approach and according to bee visual system, we described and compared the flower colour diversity and the signals of a temperate and two tropical seasonal vegetations, considering their leaf background colouration. Then, to link flower signals to seasonality and using the cerrado sensu stricto as a model of seasonal vegetation, we analysed the importance of the surveyed pollination syndromes, the community flowering pattern, flowering patterns according to the colour of flowers and the influence of seasonal changes in the background colouration in the flower colour signals between seasons. We found differences in flower colour diversity and confirmed the influence of the leaf- background colouration, along with the vegetation structure and seasonality intensity, in flower colour signals displayed in different seasonal vegetations according to the colour vision of bees. Higher value... (Complete abstract click electronic access below)
Mestre

Trichogramma carverae Oatman and Pinto is mass-released for biological control of the leafroller pest, light brown apple moth, Epiphyas postvittana (Walker) in Australian vineyards. Parasitoid performance can, however, be constrained by a lack of suitable adult food and no information is available on the effect of nectar on the parasitism and longevity of T. carverae. To address this, the effect of alyssum, Lobularia maritima (L.) flowers on E. postvittana parasitism was studied in a vineyard experiment with and without releases of T. carverae. Egg parasitoid activity was assessed with E. postvittana egg �sentinel cards� and no parasitism was recorded in plots without T. carverae releases. Where T. carverae were released, there was no significant enhancement of parasitism by the presence of L. maritima flowers. Three hypotheses were subsequently tested to account for the lack of an effect: (i) T. carverae does not benefit from L. maritima nectar, (ii) T. carverae was feeding on nectar from other flowering plants (weeds) present in the vineyard, (iii) T. carverae was feeding on sugars from ripe grapes. A growth-cabinet experiment using potted L. maritima plants with and without flowers did not support hypothesis one. No parasitism was recorded after day two for T. carverae caged without flowers whilst parasitism occured until day eight in the presence of flowers. A laboratory experiment with common vineyard weeds (Trifolium repens, Hypochoeris radicata, Echium plantagineum) as well as L. maritima did not support hypothesis one but gave partial support to hypothesis two. Survival of T. carverae was enhanced to a small but statistically significant extent in vials with intact flowers of L. maritima, white clover (T. repens) and catsear (H. radicata) but not in vials with flowering shoots of these species from which flowers and flowering buds had been removed. Paterson�s curse (E. plantagineum) flowers had no effect on T. carverae survival. In a laboratory study, punctured grapes significantly enhanced T. carverae survival compared with a treatment without grapes, supporting hypothesis three. Trichogramma carverae performance in the field experiment was probably also constrained by relatively cool and wet weather. Further work on the enhancement of T. carverae efficacy by L. maritima and other carbohydrate sources is warranted. Greenhouse and field experiments were conducted to investigate whether T. carverae benefit from different groundcover plant species. Ten T. carverae adults (<24h after eclosion) were caged with different groundcover species and a control with no plant materials. Epiphyas postvittana egg sentinel cards were used to measure parasitism and longevity was recorded visually. Survival and realised parasitism of T. carverae was significantly higher in L. maritima than in Brassica juncea, Coriandrum sativum, shoots of these species from which flowers had been removed and nil control treatments. A similar experiment with Fagopyrum esculentum (with- and without-flowers) and a control treatment showed that survival was significantly higher in intact F. esculentum than in without-flower and control treatments. There was no significant treatment effect on parasitism in the early stages of that experiment, though parasitism was recorded in the presence of F. esculentum flowers for 12 days, compared with 6 days in other treatments. Higher parasitism was observed in intact Borago officinalis than in the flowerless shoot, water only and no plant material control treatments in a third experiment. There was no significant treatment effect on parasitism. Fitted exponential curves for survival data differed significantly in curvature in the first, second and third experiments but the slope was a non-significant parameter in the second and third experiments. In a second series of laboratory experiments, one male and one female T. carverae were caged with groundcover species to investigate male and female longevity and daily fecundity. Both male and female longevity in F. esculentum and L. maritima treatments were significantly higher than on shoots of these species from which flowers had been removed, and than in the control treatments. Daily fecundity was significantly greater in the intact L. maritima treatment than in all other treatments. Fitted exponential curves for daily fecundity differed significantly in position and slope but not in curvature. There was no significant treatment effect on longevity or parasitism when a male and female were caged with intact B. juncea, B. officinalis or without-flower of these species, nor in the treatment with no plant materials. No parasitism was observed in a survey of naturally occurring egg parasitoids on two sites close to Orange and Canowindra in New South Wales, illustrating the importance of mass releases of T. carverae in biological control of E. postvittana. In an experiment on the Canowindra site, parasitism was significantly higher on day one and day two after T. carverae release when with-flower treatments were compared with without-flower treatments. Parasitism was significantly higher in the F. esculentum treatment than in C. sativum, L. maritima, vegetation without-flowers and control treatments on these dates. On day five, parasitism was higher in C. sativum than in all other treatments. There was no significant increase in parasitism in a second experiment conducted on the Orange site. Coriandrum sativum, F. esculentum and L. maritima appear to be suitable adult food sources for T. carverae and offer some scope for habitat manipulation in vineyards The adults of many parasitoid species require nectar for optimal fitness but very little is known about flower recognition. Flight cage experiments showed that the adults of T. carverae benefited from L. maritima bearing white flowers to a greater extent than was the case for light pink, dark pink or purple flowered cultivars, despite all cultivars producing nectar. Survival and realised parasitism on non-white flowers were no greater than when the parasitoids were caged on L. maritima shoots from which flowers had been removed. The possibility that differences between L. maritima cultivars were due to factors other than flower colour, such as nectar quality, was excluded by dyeing white L. maritima flowers by placing the roots of the plants in 5% food dye (blue or pink) solution. Survival of T. carverae was lower on dyed L. maritima flowers than on undyed white flowers. Mixing the same dyes with honey in a third experiment conducted in the dark showed that the low level of feeding on dyed flowers was unlikely to be the result of olfactory or gustatory cues. Flower colour appears, therefore, to be a critical factor in the choice of plants used to enhance biological control, and is likely to also be a factor in the role parasitoids play in structuring invertebrate communities. Provision of nectar producing plants to increase the effectiveness of biological control is one aspect of habitat manipulation, but care needs to be taken to avoid the use of plant species that may benefit pest species. Greenhouse experiments were conducted to investigate whether the adult E. postvittana and larvae benefit from nectar producing groundcover species. Newly emerged E. postvittana adults were caged with different groundcover species and a honey-based artificial adult diet. The longevity of male and female E. postvittana when caged with shoots of borage (B. officinalis) and buckwheat (F. esculentum) bearing flowers was as long as when fed a honey-based artificial diet. This effect was not evident when caged with shoots of these plants from which flowers had been removed. Longevity was significantly lower than in the artificial diet treatment when caged with coriander (C. sativum) or alyssum (L. maritima) irrespective of whether flowers were present or not. There was no significant treatment effect on the lifetime fecundity of E. postvittana. A second experiment with mustard (B. juncea) (with- and without-flowers), water only and honey-based artificial adult diet showed no significant treatment effects on the longevity of male and female E. postvittana or on the lifetime fecundity of E. postvittana. The anomalous lack of a difference between the water and honey-based diet treatments precludes making conclusions on the value of B. juncea for E. postvittana. Two greenhouse experiments were conducted to evaluate the effects of groundcover species on the larval development of E. postvittana. In the first experiment, larval mortality was significantly higher in C. sativum, and L. maritima than in B. juncea, B. officinalis and white clover (T. repens) a known host of E. postvittana. Coriandrum sativum and L. maritima extended the larval period. In B. juncea and B. officinalis, mortality did not differ from that in T. repens. In F. esculentum, larval mortality was significantly higher than in T. repens. A short larval period was observed on B. juncea, B. officinalis and F. esculentum. Fitted exponential curves for larval mortality differed significantly in curvature between plant treatments. Similarly, successful pupation was significantly lower in C. sativum, F. esculentum and L. maritima than in T. repens. The percentage of successful pupation in B. juncea and B. officinalis did not differ from F. esculentum and T. repens. Fitted exponential curves for pupation differed significantly in curvature. A similar trend was observed in a second experiment with potted plants. The overall results suggest that C. sativum and L. maritima denied benefit to E. postvittana adults and larvae, so could be planted as vineyard groundcover with minimal risk of exacerbating this pest. Overall results suggest that T. carverae require nutrients to reach their full reproductive potential and flowers provide such nutrients. Lobularia maritima and C. sativum may be considered �selective food plants� for T. carverae whereas F. esculentum appears to be a �non-selective food plant�; both T. carverae and E. postvittana benefited from it. Fruits such as grapes can be used as food resources in habitat manipulation and this merits further research. This result also suggests that within species flower colour is an important factor for flower selection in habitat manipulation.

Dendrobium is the most important cut flower orchid in the world. Understanding the chemical, histological and molecular aspects of flower color is crucial for the development of breeding strategies for novel colors. The objectives of this research were to examine the histology of flower color, cloning and characterization of flavonoid biosynthetic genes, and metabolic engineering of Dendrobium flavonoid pathway to obtain new colors. In Dendrobium, anthocyanins can be confined to a single layer of cells (epidermal or suepidermal) in pale flowers. More intensely colored flowers had anthocyanin in several cell layers. Striped patterns on the perianth were due to the restriction of pigment to cells surrounding the vascular bundles. Color perception is markedly influenced by the presence or absence of carotenoids. Four types of epidermal cells were found in Dendrobium: flat, dome, elongated dome, and papillate. Epidermal cell shape and cell packing in the mesophyll affected the visual texture. Perianth parts with flat cells and a tightly packed mesophyll had a glossy texture, whereas dome cells and loosely packed mesophyll contributed a velvety texture. The labella in the majority of flowers examined had a complex epidermis with more than one epidermal cell shape, predominantly papillate epidermal cells. We were able to isolate a full clone of Dendrobium dihydroflavonol 4-reductase (dfr), and partial clones of chalcone synthase (chs), flavonoid 3'-hydroxylase (f3'h) and flavonoid 3', 5'-hydroxylase (f3'5'h), from Dendrobium Jaquelyn Thomas 'Uniwai Prince' (UH503). Expression data indicated that dfr and chs were expressed to the greatest degree in unopened buds. Amount of f3'h and f3'5'h mRNA was too small to detect. Southern analysis has shown that f3'h and f3'5'h is represented by 2 copies each in UH503. These clones will be extremely useful in future for flower color manipulation. Two different color genes, dfr and f3'5'h from two non-orchid plants, under the constitutive promoter ubiquitin3, were inserted into Dendrobium Icy Pink 'Sakura' with the intention of creating orange-red and blue shades, which are absent in commercial Dendrobium. Presence of the transgene in two sets of transformants was confirmed by PCR. Expression of the transgene from a few plants was indicated by RT-PCR and northern analyses.
Thesis (Ph. D.)--University of Hawaii at Manoa, 2003.
Includes bibliographical references (leaves 148-153).
Mode of access: World Wide Web.
Also available by subscription via World Wide Web
xix, 153 leaves, bound ill. 29 cm

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第13884号
農博第1699号
新制||農||954(附属図書館)
学位論文||H20||N4351(農学部図書室)
UT51-2008-C800
京都大学大学院農学研究科農学専攻
(主査)教授 矢澤 進, 教授 米森 敬三, 教授 縄田 栄治
学位規則第4条第1項該当

Kyoto University (京都大学)
0048
新制・論文博士
博士(農学)
乙第13017号
論農博第2827号
新制||農||1042(附属図書館)
学位論文||H28||N4964(農学部図書室)
32945
京都大学大学院農学研究科農学専攻
(主査)教授 土井 元章, 教授 裏出 令子, 教授 奥本 裕
学位規則第4条第2項該当

¿Quién no cae subyugado ante la belleza de la naturaleza, especialmente al ver un jardín de flores, donde sus hermosos colores nos muestran algunas de sus maravillas?Podemos jugar con estos colores haciendo que cambien debido a algunas reacciones químicas que se producen al usar algunos ácidos o bases que van a reaccionar con algunos de los colorantes que contienen algunos pétalos.En este experimento veremos como cambiar el color de los pétalos usando algunas soluciones y anilina de diversos colores.

Allopolyploids are formed by interspecific hybridization and whole genome duplication, with the resulting organism contains multiple distinct subgenomes in one nucleus. Subgenomic interactions result in massive genetic and epigenetic reconstruction, contributing to variable phenotypic traits noted in newly formed allopolyploids. To better understand these mechanisms in the context of molecular biology, evolution, and plant breeding, plant biologists study the model organism Brassica napus (farmed as canola or oilseed rape). With white-flowering and yellow-flowering progenitors, flower color phenotype of B. napus presents an opportunity to examine subgenomic interactions. CAROTENOID CLEAVAGE DIOXYGENASE 4 (CCD4) is known to play a major role in determining flower color phenotype of carotenoid-synthesizing angiosperms. Here, we investigate the genetic and epigenetic role of CCD4 orthologs and their role in flower color phenotype of B. napus.

Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第21875号
人博第904号
新制||人||215(附属図書館)
2018||人博||904(吉田南総合図書館)
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授 瀬戸口 浩彰, 教授 加藤 眞, 教授 市岡 孝朗, 准教授 西川 完途
学位規則第4条第1項該当

The yellowness of flour colour ranges is an important quality trait in wheat for end-use products and is determined by the accumulation of carotenoids in the endosperm. The aims of this study were to develop EST-based molecular markers for genes encoding enzymes of the carotenoid biosynthetic pathway leading to xanthophyll accumulation and identify quantitative trait loci for flour colour (b*) and xanthophyll content in Western Australian adapted germplasm. A novel bioinformatic strategy was developed to identify rice genes encoding key enzymes of the carotenoid biosynthetic pathway and to predict wheat orthologues on the short arm of chromosome 3 or long arm of chromosome 7. The bioinformatic strategy involved the identification of rice carotenoid genes on BAC/PAC contigs aligned to wheat mapped ESTs. Rice genes predicted to have wheat orthologues were selected based on ESTs mapping to regions on wheat homoeologous chromosomes 3 and 7 known to be involved in flour colour. The rice genes predicted to have wheat orthologues were Geranylgeranyltransferase I ƒÒ¡Vsubunit (GGT-Ibeta) and Rab geranylgeranyltransferase component A (RGGT-A) on the short arm of chromosome 3, Lycopene ƒÒ¡Vcylcase (LBC) on the long arm of chromosome 3 and Lycopene £`¡Vcylcase (LEC) on the long arm of chromosome 7. The prediction of these wheat orthologues provided the basis for development of EST-based molecular markers for detecting variation in xanthophyll content. Wheat ESTs with unknown chromosomal locations and having the highest similarity to GGT-Ibeta, RGGT-A and LBC were selected for the development of molecular markers. No EST homologues were identified for LEC and therefore this gene was not further considered. Orthology was confirmed by sequencing and deletion lines were used to confirm chromosomal locations. Two partial orthologues of GGT-Ibeta were identified on the short arms of chromosomes 3B and 3D. A partial orthologue of RGGT-A was mapped to the proximal regions of the short and long arms of chromosome 3B. At least two or more orthologues of LBC were identified from nullisomic-tetrasomic lines. An EST-based molecular marker for GGT-Ibeta was found to be involved in minor variation of xanthophyll content in a Westonia*2/Janz doubled haploid population. QTL analysis from three doubled haploid populations indicated variation in WA-adapted germplasm may be due to different alleles controlling flour colour. QTLs for b* and xanthophyll content were found to coincide on the short arms of chromosomes 3A, 4D, and 7B and the long arm of chromosomes 7A and 7B in WA-adapted germplasm. Homoeologous expression of regions controlling variation in b* and xanthophyll content on the long arm of chromosomes 7A and 7B suggests the shut-down of genes in the same region on chromosome 7D. The main outcome of this study is flour colour and identification of gene orthologues in wheat controlling variation in xanthophyll content is complex most likely because of the interaction of the carotenoid biosynthetic pathway with other pathways.

Pollinator-driven selection is thought to drive much of the extraordinary diversity of flowering plants. Plants that produce floral traits preferred by particular pollinators are more likely to receive conspecific pollen and to evolve further adaptations to those pollinators that enhance pollination and ultimately generate floral diversity. Two mechanisms in particular, sensory bias and learning, are thought to explain how pollinator preference can contribute to divergence and speciation in flowering plants. While the preferences of pollinators, such as bees, flies, and birds, are frequently implicated in patterns of floral trait evolution, the role of learning in generating reproductive isolation and trait divergence for different floral types within plant populations is not well understood. Floral color polymorphism in particular provides an excellent opportunity to examine how pollinator behavior and learning might maintain the different floral morphs. In this study we asked if bumble bees showed innate preferences for different color morphs of the pollen-only plant Solanum tridynamum, whether bees formed preferences for the morphs with which they had experience collecting pollen from, and the strength of those learned preferences. Using an absolute conditioning protocol, we gave bees experience collecting pollen from a color polymorphic plant species that offered only pollen rewards. Despite initially-naïve bees showing no apparent innate bias toward human-white versus human-purple flower morphs, we did find evidence of a bias in learning. Specifically, bees learned strong preferences for purple corollas, but learned only weak preferences for hypochromic (human-white) corollas. We discuss how our results might explain patterns of floral display evolution, particularly as they relate to color polymorphisms. Additionally, we propose that the ease with which floral visual traits are learned—i.e., biases in learning—can influence the evolution of floral color as a signal to pollinators.

Investigations of potato (Solanum tuberosum) have been hampered by its complicated genetics and high genetic load. This dissertation applies genome reduction techniques to investigate a broad swath of genomic and physiological phenomena. It begins with the presentation and evaluation of a protocol to characterize endoreduplication within potato tubers, demonstrating substantial variation between tissue types and among wild species which may facilitate research into the genesis and growth of these starchy underground stems. Next, we transitioned to explore the distribution and consequences of a specific class of transposable element, Miniature Inverted Transposable Elements (MITEs), showing that they comprise approximately 5% of the potato genome, occur more frequently in genes with stress-related functions, and may be associated with changes, especially decreases, in gene expression. We then combined homology and sparsity based approaches to predict recent MITE activity, identifying five families as especially active. Finally, we expose the gene underlying the potato flower color locus, a homolog of AN2, while showing the effects it exerts on the flavonoid biosynthesis and fruit ripening pathways. This region was shown to be particularly dynamic, replete with MITEs and structural variants which we hypothesize to be the ultimate cause of differences in AN2 expression within the germplasm we examined. While the separate topics of this dissertation are quite disparate, each addresses an important topic in potato genetics, the in-depth study of which is only possible through the utilization of genomic reduction approaches to acquire homozygous genotypes for study and currently available genomic resources.
Ph. D.

In the Summer of 2015, the Large Hadron Collider resumed operation after a two-year shutdown, providing proton-proton collisions at a record energy of 13 TeV. This thesis presents two measurements of data recorded by the ATLAS detector in proton-proton collisions at the LHC. The first is a measurement of the top-quark pair production cross-section. A dataset of 85 inverse picobarn recorded during an early operating period at the new centre-of-mass energy is used. The cross-section is measured in the single-lepton final state using a high-momentum electron or muon. Measured cross-section values from the two sub-channels and the combination are all consistent within their uncertainties with predictions from theoretical calculations. The second analysis using ATLAS data is a measurement of colour flow in top-quark pair events based on a dataset of 36.1 inverse femtobarn. This measurement also uses the single-lepton final state. Observables are constructed from the jet-pull vector, a momentum-weighted angular moment of a jet, which are sensitive to the colour flow in the signal event topology. Two scenarios are considered: the two jets originating from the hadronically decaying W boson and the two b-tagged jets from the top-quark decays. Observables derived from the former are sensitive to colour flow of a colour singlet while those derived from the latter probe the overall top-quark pair colour-flow. The measured observables are corrected for detector effects by unfolding them to particle level. Normalised unfolded distributions are compared to theoretical predictions taken from simulation and the agreement is quantified. Good agreement between the measured data and the predictions is observed for some combinations of observables and predictions. However, none of the predictions describes data well across all measured observables. A model with exotic colour flow is also constructed. The data favours the predictions from simulation according to the Standard Model over the model with exotic colour flow.

The nature of the flour constituents, other than the xanthophylls, responsible for the yellow colour of Asian alkaline noodles was investigated. Compounds which were colourless at neutral or acid pH but which turn yellow at alkaline pH were partially extracted with water whilst much larger quantities were extracted with 0.1M hydroxylamine at pH 7.2. A preliminary screening method for measuring the genetic variation of these compounds in wheat cultivars has been developed. The absorbance of hydroxylamine extracts at 440 nm, following adjustment of pH with NaOH, was used to estimate the quantity of these compounds in flour and whole meal. Of the 113 cultivars screened, Kamilaroi (T. durum cultivar) and Bodallin had the lowest levels whilst Avocet and Sunstar had the highest, the latter containing approximately 2.3 times the level in Bodallin. Wheat flour retained on average one third of the colour components present in the wheat grain, which can be extracted with aqueous solvents. The levels of these compounds in whole meal were not correlated with the levels in milled flour. This indicated that these compounds were concentrated in non-endosperm components of the grain and that their concentration in flour was highly dependent on the milling process and the degree of contamination of flour with non-endosperm tissue. Total yellow pigment content (xanthophyll content plus hydroxylamine soluble compounds) of flour was positively correlated (r=0.802, p<0.001) with the yellow colour, CIE b*, of alkaline noodle sheets. This result supports and extends the conclusion by Mares (1992), that the yellow colour of noodle sheets results from a combination of xanthophylls and water-soluble flavonoids. A high performance liquid chromatographic protocol for the analysis of naturally occurring flavonoids and related phenolic compounds in wheat flour has been developed. The separation system consisted of a C18 reversed-phase column and a gradient system of 1% formic acid (A) and methanol with 4% acetonitrile, 1% formic acid (B). Over 20 peaks were eluted from the column with a gradient system composed of seven steps starting at 10% (v/v) B in A and completing at 95% (v/v) B in A. The preliminary quantification of these compounds was achieved by diode array photometric detection at 340 nm with naringin as an external standard. A post column derivatization technique was employed to identify the compounds which turned yellow following addition of alkali. More than ten colour components were detected using this technique. Two flavonoid apigenin glycosides were isolated and tentatively identified by LC-UV and ES-MS. These two glycosides were found to be the major components responsible for the alkaline—induced change in noodle colour. Comparison of the HPLC profiles of water-soluble fractions with those of hydroxylaminesoluble fractions revealed that the level of colour components in hydroxylamine extract was much higher than in the water-soluble fraction. This was due not only to the increase in the concentration of major aqueous-soluble colour components but also to the presence of extra compounds which were absent in water-soluble fractions. Flour or whole meal extracted with basic water released a large amount of ferulic acid presumably from cell walls, and additional components which were more methanol soluble. The total content of colour components, other than xanthophylls present in flours of six Australian cultivars, grown in 1995, ranged from 45 to 82 mg/ 100 g naringin equivalent whereas whole meal contained 378-441 mg/ 100g. The distribution of ferulic acid in wheat was also investigated. Whole meal of the six tested Australian cultivars contained 48—52 mg/ 100g ferulic acid. The concentration in flour was 8.6 mg/ 100g and was about six times lower than that in whole meal. Investigation of the location of aqueous-soluble colour components in wheat showed that the level of the pigments in the grain, from which the germ has been removed, was significantly lower (20 times) than those in the germ tissues. The components present in flour milled from non—germ grain were around 6 mg/ 100g, which was 13.5 times lower than flour milled from grains with the germ intact. These results suggest that the presence of these colour components in flour is mainly due to germ and bran contamination during the milling process.

[Abstract]Quantitative Trait Loci (QTLs) for polyphenol oxidase and xanthophyll have a significant impact on variation in wheat flour for noodle colour and colour stability. QTLs from two Australian wheat cultivars, Sunco and Tasman, have been backcrossed into two Chinese wheat varieties, Chuanmai 22 and Mianyang 11, to assess marker predictability for these important traits in significantly different genetic backgrounds. The concept of Marker-Assisted-Selection (MAS) is being trialled in this study as a proposed method for wheat improvement. In this approach molecular markers are used in conjunction with backcross breeding methods to introgress specific characters into elite breeding materials, with the goal of improving the quality attributes of wheat for the Asian noodle market. After three single seed descent generations, the backcross populations generated allow four QTLs to be investigated. These include two for polyphenol oxidase (chromosome 2A and 2D) and two for xanthophyll (chromosome 3B and 7A). This research was successful in identifying microsatellite markers that are capable of predicting PPO activity levels and Xanthophyll content within the backcross populations. These microsatellites were validated as useful markers for these quality traits, as they have also found to be important in the Sunco x Tasman doubled haploid population. The combination of marker assisted selection and backcrossing has generated three lines that contain different combinations of the PPO activity and Xanthophyll content QTLs. These lines have been found to produce low levels of PPO activity and have a low Xanthophyll content. This improvement in flour colour and colour stability highlights the potential of marker assisted selection as a useful tool in wheat breeding.

How specialist bees distinguish their host plants from co-blooming non-hosts is not well understood, but it is thought that they may be physiologically limited in their ability to recognize the majority of visual and olfactory cues presented by flowering plants. Species in the genus Diadasia collect pollen from just one of five plant families: Cactaceae, Malvaceae, Onagraceae, Asteraceae, and Convolvulaceae. Assuming a common ancestor for all Diadasia specialized on just one plant, this indicates host-switches in the past, and an ability to recognize more than one flowering plant. I hypothesized that host plants of Diadasia share the same visual and olfactory cues, thus enabling past host-switching to novel plant families, and that co-blooming non-hosts are highly dissimilar in terms of scent and visual appearance. I determined the compounds associated with the scent of Malvaceae and Cactaceae host flowers of North American Diadasia. I also evaluated visual cues for these flowers by measuring their full spectrum of reflected wavelengths, as well as select morphometric characters. I determined whether host flowers, regardless of taxa, were more similar to each other than non-hosts that were co-blooming and attractive to other bee species. Finally, I performed electroantennographic and behavioral experiments to assess the relative importance of these cues (visual and olfactory) in natural settings. Diadasia host plants share some chemical and visual characteristics that may in part explain the radiation of this group onto these particular hosts. First, host plants share a suite of scent compounds that are among the least variable across species. Many of these elicited antennal responses and did not decrease visitation when applied to host flowers. In contrast, some compounds produced by non-host flowers are detectable to Diadasia, but Diadasia are repelled by them when they are applied to host flowers. Diadasia host flowers do not share a color profile in common, but there is more reflectance in the bee-uv range as compared to other regions of the light spectrum. Also, Diadasia host flowers have a more contrasting central area that is relatively larger than in non-hosts.

The majority of colours in the natural world are produced via the wavelength selective absorption of light by pigmentation. Some species of both flora and fauna, however, are particularly eye-catching and visually remarkable as a result of the sub-micron, light-manipulating architecture of their outer-integument material. This thesis describes detailed investigations of a range of previously unstudied photonic structures that underpin the creation of the interesting visual appearances of several such species of flora and fauna. These structures were examined using a variety of methods, including optical microscopy, scanning and transmission electron microscopy, focused ion-beam milling and atomic force microscopy. This enabled detailed characterisation of the species’ photonic systems. The degree of order discerned in the species’ photonic structures ranged from: ‘ordered’ systems, where multiple layers of two materials produces metallic and often mirror-like reflections; to ‘quasi-ordered’ systems, where an average periodicity of the structure in all directions gives rise to diffuse, coloured scatter; to disordered systems, where no discernible order is observed, which results in a diffuse, broad-band, white appearance. In addition to this, the range of systems also encompassed: periodicities in one-dimension in the form of multilayering; ‘quasi-two-dimensional’ structures in the form of aligned fibres; and three-dimensional structures formed from arrangements of spherical particles. Alongside this experimental characterisation, an in-depth series of supporting theoretical analyses were undertaken. For the one-dimensional systems studied here, the models’ theoretical reflectance was calculated using analytical methods. For other systems, with more complex structural-geometries, theoretical simulations of their electromagnetic response to incident radiation were carried out using finite-difference-time-domain and finite-element-method numerical modelling approaches. Theoretical modelling results were compared to experimental measurements of each sample's optical properties. These were primarily reflectance measurements, which were taken using a range of techniques appropriate for each specific investigation. In addition to this, a synthetic sample, mimicking the white-appearance and remarkable polarisation-dependant reflectance of one insect’s photonic structure, was created using polymer electrospinning. Using these experimental measurements and theoretical simulation predictions, the structural colour production mechanisms adopted by several species of flora and fauna were elucidated.

It all started with a thought of one single colour; the colour red. The idea of building a collection from one colour was frighten- ing and intriguing at the same time. It was frightening because I didn’t know if it was enough to build a whole collection on only one colour, but the possibility to find other expressions arouse my curiosity. But why red? I find that this colour, of all colours, has the deepest range of shades. With red ink and my fingers as tools I created an ab- stract sketch to refer to. When the differ- ent shades come together it creates a great vivid expression of the whole picture. I am not interested in one shade alone, it is the interaction between two or more which are interesting.
Program: Modedesignutbildningen

Mestrado em Arquitectura Paisagista - Instituto Superior de Agronomia
Flowering bulbs are the dream of any landscape or gardener, for the great variety of bloom color, flowering time, plant height and shapes. In fact there are countless uses for this type of plants, and it is usual to find it in many ways in the garden, such as: under deciduous shrubs and trees, giving color when there are no leaves; in containers, outside or inside, portable or fixed; in Rock Gardens; in lawns or meadows, bounding different areas or appearing naturally or in small groups; as ground cover, associated with other species as Ajuga or Vinca. Although the variety of uses, the fact is that is our country is easier to find more of these species in interior containers than in public gardens. Therefore, the present work intended to explore the existence of endemic and autochthone bulbs and break the stigma that this kind of plants do not naturally adapt to Portuguese clime, or that are followed by numerous maintenance costs, by making a landscape project whose central element are the bubs itself, under different typologies

This thesis discusses our research conducted in the area of hand gesture recognition. The research objectives were to develop techniques that lead to accurate and robust gesture recognition under everyday settings. And work with consistent accuracy in both single and multiuser scenarios. In this research, we propose techniques that rely on the combination of skin colour and optical flow. A background subtraction stage involves identifying skin regions in an image frame. We use skin colour thresholds in chromaticity space. In our work, we have simplified the process by identifying a reliable set of thresholds without camera calibration and a specialized imaging setup. In order to tackle the issue of false positives we combine skin colour with optical flow magnitude i.e. joint thresholding. We propose a novel skin colour-optical flow metric to track an arbitrarily changing number of skin regions. The proposed technique has been successfully applied to Bayesian and non-Bayesian tracking. We use a novel feature descriptor to represent a gesture making hand i.e. the Radon transform of its contour. The tracking mechanism and gesture classification is tested for single and simultaneous multi-gesture classification. We also propose a novel technique for grouping skin regions belonging to a particular person. In our work, we first try to establish the potential usefulness of using standard HCI techniques by evaluating our real time application. Based on the results, we propose a usability evaluation framework. We formalize usability evaluation for interactive vision systems by incorporating the standard practice of prototyping and user feedback. This framework can be helpful in conducting a well rounded evaluation.

La segmentation d'image couleur consiste à partager l'image en différentes régions ayant des caractéristiques homogènes selon certains critères. La base de représentation couleur utilisée est la base RGB afin de ne pas perdre l'information couleur de l'image. Tenant compte de la corrélation des données des trois plans de l'image dans cette base, une segmentation grossière hybride suivie d'une segmentation fine sont développées. La segmentation grossière est une classification itérative. Elle utilise des mesures floues telles que l'index ou l'entropie floue afin de minimiser de manière optimale et auto-adaptative les zones ambiguës des histogrammes R, G, B de l'image, permettant l'extraction d'une classe 3D, et la formation grossière d'une région formée par un ensemble de pixels classés et de pixels masqués. La segmentation fine utilise le nombre de classes, leur centre de gravité et la fonction d'appartenance de l'algorithme des fuzzy C-means afin de classer globalement les pixels masqués. Etant donné qu'il existe quelques pixels mal classés, une approche markovienne est développée pour éliminer ces pixels et rendre les régions homogènes avec des frontières lisses. Pour finir une version modifiée de la segmentation est intégrée dans une structure pyramidale afin de diminuer les temps de calculs.

 la fin du Moyen Âge les fleurs sont fréquemment représentées dans les tapisseries, les manuscrits enluminés et les tableaux. L’objectif de l’étude est d’établir qu’il ne s’agit pas d’un simple procédé décoratif. Les fleurs, support naturel de la couleur, constituent un système symbolique par analogie dont la fonction est de guider le spectateur dans sa lecture de l’image. La construction des images en réseaux signifiants avec la flore symbolique accompagne un comportement nouveau, la Devotio Moderna, sous l’influence des ordres Mendiants, notamment les Dominicains. L’objectif est de guider le fidèle lors de ses prières. Les imagiers utilisent également ce système pour représenter les rois français Valois qui souhaitent proclamer leur lien privilégié avec Dieu. L’étude de ce système symbolique, contenu et structure, nous permet de mieux comprendre la mentalité médiévale avec sa façon particulière de penser le monde
At the end of the Middle Ages flowers are frequent in tapestries, manuscripts and paintings. The aim of this study is to prove they are not just decorative items but that they have their own function in images. These flowers, especially by means of their colours, make up a symbolical system aiming at guiding the reader to understand the inner sense of symbolical images. This special way of composing images is concomitant with a new way of praying God, the Devotio Moderna, under the supervision of preachers, especially the Dominicans. The image-makers also use these new patterns to picture the French Valois kings in order to assert their alleged special relationship with God. The study of this symbolical system, contents and structure, enable us to understand better the particular medieval way of thinking the world

Dans le domaine de l’optique, les savants ont réfléchi, depuis l’Antiquité, aux couleurs. Dans les beaux-arts, par sa nature accidentelle, la couleur a été traitée comme un élément inférieur au dessin. L’enseignement scolaire a suivi cette tendance. Cependant, au milieu du XIXe siècle, apparaissent divers ouvrages de vulgarisation traitant des couleurs. Leur point de vue est alors le savoir-vivre, l’éducation, l’ésotérisme, l’optique, l’art ou la technologie. Notre thèse a pour objectif de comprendre en quoi le traitement des couleurs est original dans les poèmes en vers de Rimbaud, en relation avec l’épistémè du XIXe siècle. Dans les poèmes de Rimbaud, les couleurs parlent du poète ; de son éducation, ses préoccupations, sa pensée politique ou religieuse et même l’enjeu poétique de son œuvre. Nous nous sommes concentré sur le symbole des couleurs, négligé jusqu’à présent, et sur les effets physiologiques et les impressions visuelles dont Goethe ou Chevreul ont traité. Rimbaud n’invente ni les couleurs spectrales, ni les correspondances entre sons et couleurs, ni le symbolisme des couleurs. Il s’inspire d’idées existantes, et les combine pour inventer une nouvelle langue poétique. Il superpose les couleurs symboliques provoquant des associations d’idées, aux couleurs spectrales. Dans « Voyelles », le poète implique sa méthode dans la description de l’arc-en-ciel, dans l’évocation sonore des lettres de l’alphabet grec et dans le symbolisme de cinq couleurs. L’originalité de sa démarche tient à la convergence de ses différents moyens d’expression. C’est cet emploi des couleurs qui contribue à la création d’une nouvelle langue poétique
In the field of optics, scientists have studied colors since ancient times. In Arts, because of its accidental nature, color is treated as a element lower than drawing. School education has followed this tendency to neglect the color. However, during the mid-nineteenth century appeared various books about colors, in the fields of etiquette, education, esotericism, optics, art and technology. Our objective is to find what makes the use of colors unique in the verse poems of Rimbaud, in consideration of the nineteenth century episteme. In his poems, colors speak of the poet; his education, his concerns, his political or religious thought and his poetics. We focused on the symbols of colors, which was neglected so far, and on the physiological effects and visual impressions treated by Goethe and Chevreul. Rimbaud do not invent neither the spectral colors, nor the correspondences between sounds and colors, nor color symbolism. He draws inspiration from existing ideas, and combines them to invent a new poetic language. He superimposes symbolic colors creating associations of ideas, on spectral colors, which maintain order in optics. In "Voyelles", he introduces his poetics through the description of a rainbow, the sonorous evocation of letter of the Greek alphabet, and the symbols of five colors. The originality of his approach lies in the convergence of its different means of expression. His use of color thus leads to the creation of a new poetic language.episteme. In his poems, colors speak of the poet; his education, his concerns, his political or religious thought and his poetics. We focused on the symbols of colors, which was neglected so far, and on the physiological effects and visual impressions treated by Goetheand Chevreul. Rimbaud do not invent neither the spectral colors, nor the correspondences between sounds and colors, nor color symbolism. He draws inspiration from existing ideas, and combines them to invent a new poeticlanguage. He superimposes symbolic colors creating associations of ideas, on spectral colors, which maintain order in optics. In "Voyelles", he introduces his poetics through the description of a rainbow, the sonorous evocation of letter of the Greek alphabet, and the symbols of five colors. The originality of his approach lies in the convergence of its different means of expression. His use of color thus leads to the creation of a new poetic language

Advanced monitoring of water quality in order to perform a real-time hazard analysis prior to Water Treatment Works (WTW) is more of a necessity nowadays, both to give warning of any contamination and also to avoid downtime of the WTW. Downtimes could be a major contributor to risk. Any serious accident will cause a significant loss in customer and investor confidence. This has challenged the industry to become more efficient, integrated and attractive, with benefits for its workforce and society as a whole. The reality is that water companies are not yet prepared to invest heavily in trials, before another company announces its success in implementing a new monitoring strategy. This has slowed down the development of the water industry. This research has taken the theoretical idea that the use of advanced online monitoring technique in the water industry would be beneficial and a step further; demonstrating by means of a state-of-the-art assessment, usability trials, case studies and demonstration that the barriers to mainstream adoption can be overcome. The findings of this work have been presented in four peer-reviewed papers. The research undertaken has shown that Turbidity levels in rivers can be measured from the rivers' mean flow rate, using either Doppler Ultrasound device for real-time readings or based on past performance history. In both cases, the Turbidity level can also help estimate both the Colour and Conductivity levels of the subject river. Recalibration of the equations used is a prerequisite as each individual river has its own unique "finger print".

We investigate some problems commonly found when dealing with stereo images. Working within the context of visual effects for films, we explore software solutions to issues arising with stereo images captured on-set. These images originate from a wide variety of hardware which may or may not provide additional data support for post-production needs. Generic software solutions are thus greatly to be preferred. This dissertation documents contributions in the following three areas. Each project was undertaken at Double Negative and investigated with the aim of improving the post-production pipeline for 3D films. Colour matching is the process whereby the colours of one view from a stereo pair are matched with those of the other view. This process is necessary due to the fact that slight differences in hardware and viewing angle can result in some surprisingly large colour discrepancies. Chapter 3 presents a novel approach to colour matching between stereo pairs of images, with a new tool for visual effects artists given in section 6.2.Vertical alignment of stereo images is key to providing a comfortable experience for the viewer, yet we are rarely presented with perfectly aligned footage from the outset. In chapter 4 we discuss the importance of correcting misalignments for both the final audience and the artists working on these images. We provide a tool for correcting misalignments in section 6.3.Disparity maps are used in many areas of post-production, and so in chapter 5 we investigate ways in which disparity map generation can be improved for the benefit of many existing tools at Double Negative. In addition, we povide an extensive exploration of the requirements of 3D films in order to make them presentable in the cinema. Through these projects, we have provided improvements to the stereo workflow and shown that academic research is a necessary component of developing tools for the visual effects pipeline. We have provided new algorithms to improve the 3D experience for moviegoers, as well as artists, and conclude by discussing the future work that will provide further gains in the field.

In this thesis, the search for the production of the Higgs boson in associationwith two top quarks is presented. The main focus of this work is on the analysis optimised for the decay of the Higgs boson to a b-quark pair. The analysis is performed using 36.1 fb−1 of ppcollision data at a centre of mass energy sqrt(s)=13 TeV collected by the ATLAS detector at the Large Hadron Collider during 2015 and 2016. The signal strength of ttH in relation to the Standard Model prediction for a Higgs boson with a mass of 125 GeV is measured to be mu(ttH) = 0.87 +0.64−0.61, with signal strengths greater than 2.0 excluded at the 95% confidence level. The combination of this analysis with searches targeting additional Higgs boson decay modes is subsequently presented. The measured signal strength in relation to the Standard Model prediction is mu(ttH) = 1.2 +/-0.3. This correspondsto an observed (expected) significance for ttH of 4.2sigma (3.8sigma), constituting evidence for the ttH production mode. Finally, a study into the ability to observe and model the colour connection of b-quarks in ttH(bb) and ttbar+jets events is presented. The jet pull angle observable is used to investigate the effect of colour connection on jet substructure. Such an observable is found to be sensitive to the underlying colour structure in events, showing differences between b-quarks which decay from a colour singlet in comparison to a colour octet. However, the effect is found to be small and a larger dataset is required to measure the effect in ttH events.

The organization of complex societies requires constant information to flow between individuals. Because of their elaborated social structures and principally because of the division of labor, social insects depend on the efficacy of their information web in order to adapt the colony activity to its needs. Although many studies focused on understanding the regulation of the foraging activity, little is known about the intranidal food distribution and stock management regulation. The aim of this thesis is to quantify and describe the dynamics of the food flow and its regulation in an ant colony. A medical imagery technique, scintigraphy, was adapted to follow the propagation of radio-labeled nutrients inside the nest. This technique allowed spatiotemporal dynamics quantification of the food flow and led to the enunciation of simple yet robust regulation rules that are at work during the colony feeding process.

The dynamics of the harvest is regulated by the coupling of a positive and negative feedbacks. The harvest acts as both: negative and positive feedbacks. Entering food-loads trigger foragers to exploit the newly discovered food source through the well-known recruitment process. At the same time, the harvest proportionally reduces the entering food flow until the complete stop of the foraging activity when the colony reaches satiety. Surprisingly, the positive feedback (that is the recruitment) is not responsible for a faster entering food flow and is not influenced by the colony needs while the exploring activity is. The spatial dynamics of the food exchange network revealed stable patterns and fine tuning regulation of the feeding process. Spatial analysis of the food distribution showed that sucrose is heterogeneously stored among individuals and also heterogeneously consumed. We observed a regular spatial structure leading to centralization of the stocks: heavy loaded individuals being at the center of the cluster and weakly loaded individuals at its periphery.

The spatiotemporal quantification of the food flow allowed describing and understanding the flexibility of the colony to adapt its working force according to its nutritional requirements.

Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Dans cette thèse, une nouvelle représentation des images couleur basée sur une généralisation du signal analytique est introduite. En utilisant l'analogie entre les conditions de Cauchy-Riemann, qui définissent le caractère holomorphe d'une fonction, et l'équation de Dirac dans l'algèbre de Clifford R_{5,0}, un système d'équations dont la solution est le signal monogène couleur est obtenu. Ce signal est notamment basé sur des noyaux de Riesz ainsi que de Poisson 2D, et une représentation polaire, basée sur un produit géométrique, peut lui être associée. Les applications envisagées reposent majoritairement sur cette représentation polaire et sur les informations de couleur et de structures locales s'y rattachant. Des problématiques liées au flot optique couleur, à la segmentation couleur multi-échelle, au suivi d'objets couleur et à la détection de points d'intérêt sont abordées. En ce qui concerne le flot optique, nous nous intéressons à l'extraction du mouvement d'objets d'une certaine couleur en remplaçant la contrainte de conservation de l'intensité par une contrainte de conservation d'angles. Pour la segmentation, une méthode de détection de contours basée sur de la géométrie différentielle et plus particulièrement sur la première forme fondamentale d'une surface, est proposée afin de déterminer les contours d'objets d'une couleur choisie. Pour le suivi d'objets, nous définissons un nouveau critère de similarité utilisant le produit géométrique que nous insérons dans un filtrage particulaire. Enfin, nous resituons la définition du détecteur de Harris dans le cadre de la géométrie différentielle en faisant le lien entre ce dernier et une version "relaxée" du discriminant du polynôme caractéristique de la première forme fondamentale. Ensuite nous proposons une nouvelle version multi-échelle de ce détecteur en traitant le paramètre d'échelle comme une variable d'une variété de dimension 3.