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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Purification and Characterization of Blue and Green Chromoprotein Pigments from the Integument of Male Darters in the Genus Etheostoma

Boone, Katelyn 05 January 2012 (has links)
Unlike most other vertebrates, many species in the genus Etheostoma do not utilize structural refraction to display blue or green color. Instead, blue and green mating coloration exhibited by male rainbow darters (E. caeruleum) and male greenside darters (E. blennioides) results from the presence of true chromoprotein pigments. This study was conducted in order to extract, purify, characterize, and compare these novel pigments. Pigments were extracted in aqueous buffer and partially purified by ammonium sulfate fractionation and gel filtration chromatography. Final purification consisted of preparative non-denaturing polyacrylamide gel electrophoresis for E. caeruleum and hydroxyapatite chromatography for E. blennioides. Isolation of the chromophore was accomplished using acetone precipitation. The chromophore is the same in both species and is believed to be biliverdin. The protein component differs between the species and appears to have a greater number of subunits in E. blennioides. Binding of the protein to the chromophore amplifies the absorbance in the visible region and causes spectral tuning of the absorbance profile of the chromophore, with slight differences between species. In E. caeruleum, the chromoprotein pigment has a lambda max of 683 nm and transmits light at slightly shorter wavelengths, causing it to appear blue. In E. blennioides, the chromoprotein pigment has a lambda max of 696 nm and transmits light at slightly longer wavelengths, causing it to appear green. This work has shown that the protein component, not the chromophore, is responsible for the difference in hue between these two pigments. Future work will involve obtaining amino acid sequences for the protein component of the pigments and ultimately sequencing the gene coding for these proteins in darters. / Bayer School of Natural and Environmental Sciences; / Environmental Science and Management (ESM) / MS; / Thesis;
22

Verification formelle et optimisation de l'allocation de registres

Robillard, Benoit, Bruno 30 November 2010 (has links) (PDF)
La prise de conscience générale de l'importance de vérifier plus scrupuleusement les programmes a engendré une croissance considérable des efforts de vérification formelle de programme durant cette dernière décennie. Néanmoins, le code qu'exécute l'ordinateur, ou code exécutable, n'est pas le code écrit par le développeur, ou code source. La vérification formelle de compilateurs est donc un complément indispensable à la vérification de code source.L'une des tâches les plus complexes de compilation est l'allocation de registres. C'est lors de celle-ci que le compilateur décide de la façon dont les variables du programme sont stockées en mémoire durant son exécution. La mémoire comporte deux types de conteneurs : les registres, zones d'accès rapide, présents en nombre limité, et la pile, de capacité supposée suffisamment importante pour héberger toutes les variables d'un programme, mais à laquelle l'accès est bien plus lent. Le but de l'allocation de registres est de tirer au mieux parti de la rapidité des registres, car une allocation de registres de bonne qualité peut conduire à une amélioration significative du temps d'exécution du programme.Le modèle le plus connu de l'allocation de registres repose sur la coloration de graphe d'interférence-affinité. Dans cette thèse, l'objectif est double : d'une part vérifier formellement des algorithmes connus d'allocation de registres par coloration de graphe, et d'autre part définir de nouveaux algorithmes optimisants pour cette étape de compilation. Nous montrons tout d'abord que l'assistant à la preuve Coq est adéquat à la formalisation d'algorithmes d'allocation de registres par coloration de graphes. Nous procédons ainsi à la vérification formelle en Coq d'un des algorithmes les plus classiques d'allocation de registres par coloration de graphes, l'Iterated Register Coalescing (IRC), et d'une généralisation de celui-ci permettant à un utilisateur peu familier du système Coq d'implanter facilement sa propre variante de cet algorithme au seul prix d'une éventuelle perte d'efficacité algorithmique. Ces formalisations nécessitent des réflexions autour de la formalisation des graphes d'interférence-affinité, de la traduction sous forme purement fonctionnelle d'algorithmes impératifs et de l'efficacité algorithmique, la terminaison et la correction de cette version fonctionnelle. Notre implantation formellement vérifiée de l'IRC a été intégrée à un prototype du compilateur CompCert.Nous avons ensuite étudié deux représentations intermédiaires de programmes, dont la forme SSA, et exploité leurs propriétés pour proposer de nouvelles approches de résolution optimale de la fusion, l'une des optimisations opéréeslors de l'allocation de registres dont l'impact est le plus fort sur la qualité du code compilé. Ces approches montrent que des critères de fusion tenant compte de paramètres globaux du graphe d'interférence-affinité, tels que sa largeur d'arbre, ouvrent la voie vers de nouvelles méthodes de résolution potentiellement plus performantes.
23

Seasonal change in defensive coloration in a shieldbug

Johansen, Aleksandra I. January 2011 (has links)
Protective coloration such as aposematism and crypsis occurs in many insects but only a few species alter their defensive strategy during the same instar. We hypothesize the adult shield bug Graphosoma lineatum with an alternating black and non-melanised longitudinal striation exhibit such a change in defensive coloration. In Sweden, the non-melanised stripes of the pre-hibernation G. lineatum are pale brown and cryptic but they change during hibernation to red and aposematic. We have tested the adaptive functions of coloration of the two G. lineatum forms against bird predators. In Paper I we used great tits as predators and measured detection time of the two forms against a background of dry grass and plants, simulating late-summer conditions. We found that the birds took longer time to find the pale than the red form. Thus, the pale form of G. lineatum is more cryptic in a dry environment than the red form. In Paper II and III we used naïve predators and measured attack rate/latency on red and pale adults and fifth-instar larvae (black and brown) to investigate avoidance and generalisation between the stages. In Paper II domestic chicks initially found the red form most intimidating, but both adult forms are more intimidating than the larva. Moreover, there was a broad generalisation among forms. In Paper III naïve great tits did not find the red form significantly more aversive than the pale adult. Neither the chicks nor the tits showed any difference in the speed of avoidance learning between the two adult colour forms. In Paper IV the shieldbugs themselves were the main focus as we compared activity levels in the different colour forms and found that G. lineatum alters behaviour in accordance to their protective strategy. Thus they were significantly less active during the cryptic phase. Taken together, these experiments suggest that the pale brown adult invests in a cryptic strategy at the cost of reduced protection from aposematism, whereas the red adult benefits from aposematism at the cost of reduced camouflage. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.
24

Pigmentation as a strategy for reducing solar damage in reef-building corals /

Kluter, Anke. January 2003 (has links) (PDF)
Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.
25

The Costs and Consequences of Iridescent Coloration in Anna's Hummingbirds (Calypte anna)

January 2012 (has links)
abstract: Colorful ornaments in animals often serve as sexually selected signals of quality. While pigment-based colors are well-studied in these regards, structural colors that result from the interaction of light with photonic nanostructures are comparatively understudied in terms of their consequences in social contexts, their costs of production, and even the best way to measure them. Iridescent colors are some of the most brilliant and conspicuous colors in nature, and I studied the measurement, condition-dependence, and signaling role of iridescence in Anna's hummingbirds (Calypte anna). While most animal colors are easily quantified using well-established spectrophotometric techniques, the unique characteristics of iridescent colors present challenges to measurement and opportunities to quantify novel color metrics. I designed and tested an apparatus for careful control and measurement of viewing geometry and highly repeatable measurements. These measurements could be used to accurately characterize individual variation in iridescent Anna's hummingbirds to examine their condition-dependence and signaling role. Next, I examined the literature published to date for evidence of condition-dependence of structural colors in birds. Using meta-analyses, I found that structural colors of all three types - white, ultra-violet/blue, and iridescence - are significantly condition-dependent, meaning that they can convey information about quality to conspecifics. I then investigated whether iridescent colors were condition-dependent in Anna's hummingbirds both in a field correlational study and in an experimental study. Throughout the year, I found that iridescent feathers in both male and female Anna's hummingbirds become less brilliant as they age. Color was not correlated with body condition in any age/sex group. However, iridescent coloration in male Anna's hummingbirds was significantly affected by experimental protein in the diet during feather growth, indicating that iridescent color may signal diet quality. Finally, I examined how iridescent colors were used to mediate social competitions in male and female Anna's hummingbirds. Surprisingly, males that were less colorful won significantly more contests than more colorful males, and colorful males received more aggression. Less colorful males may be attempting to drive away colorful neighbors that may be preferred mates. Female iridescent ornament size and color was highly variable, but did not influence contest outcomes or aggression. / Dissertation/Thesis / Ph.D. Biology 2012
26

Partitionnement, recouvrement et colorabilité dans les graphes / Partitionability, coverability and colorability in graphs

Gastineau, Nicolas 08 July 2014 (has links)
Nos recherches traitent de coloration de graphes avec des contraintes de distance (coloration de packing) ou des contraintes sur le voisinage (coloration de Grundy). Soit S={si| i in N*} une série croissante d’entiers. Une S -coloration de packing est une coloration propre de sommets telle que tout ensemble coloré i est un si-packing (un ensemble où tous les sommets sont à distance mutuelle supérieure à si). Un graphe G est (s1,... ,sk)-colorable si il existe une S -coloration de packing de G avec les couleurs 1, ...,,k. Une coloration de Grundy est une coloration propre de sommets telle que pour tout sommet u coloré i, u est adjacent à un sommet coloré j, pour chaque j<i.Dans cette exposé, nous présentons des résultats connus à propos de la S-coloration de packing. Nous apportons de nouveaux résultats à propos de la S-coloration de packing, pour des classes de graphes telles que les chemins, les cycles et les arbres. Nous étudions en détail la complexité du problème de complexité associé à la S-coloration de packing, noté S -COL. Pour certaines instances de S -COL, nous caractérisons des dichotomies entre problèmes NP-complets et problèmes résolubles en tempspolynomial. Nous nous intéressons aux différentes grilles infinies, les grilles hexagonale, carrée, triangulaire et du roi et nous déterminons des propriétés de subdivisions d’un i-packing en plusieurs j-packings, avec j>i. Ces résultats nous permettent de déterminer des S-colorations de packings de ces grilles pour plusieurs séries d’entiers. Nous examinons une classe de graphe jamais étudiée en ce qui concerne la S -coloration de packing: les graphes subcubiques. Nous déterminons que tous les graphes subcubiques sont (1,2,2,2,2,2,2)-colorables et (1,1,2,2,3)-colorables. Un certain nombre de résultats sont prouvés pour certaines sous-classes des graphes subcubiques. Pour finir, nous nous intéressons au nombre de Grundy des graphes réguliers. Nous déterminons une caractérisation des graphes cubiques avec un nombre de Grundy de 4. De plus, nous prouvons que tous les graphes r-réguliers sans carré induit ont pour nombre de Grundy de r+1, pour r<5. / Our research are about graph coloring with distance constraints (packing coloring) or neighborhood constraints (Grundy coloring). Let S={si| i in N*} be a non decreasing sequence of integers. An S-packing coloring is a proper coloring such that every set of color i is an si-packing (a set of vertices at pairwise distance greater than si). A graph G is (s1,... ,sk)-colorable if there exists a packing coloring of G with colors 1,... ,k. A Grundy coloring is a proper vertex coloring such that for every vertex of color i, u is adjacent to a vertex of color j, for each j<i.In this presentation, we present results about S-packing coloring. We prove new results about the S-coloring of graphs including paths, cycles and trees. We study the complexity problem associated to the S-packing coloring, this problem is denoted S-COL. For some instances of S-COL, we characterize dichotomy between NP-complete problems and problems solved by a polynomial time algorithm. We study also different lattices, the hexagonal, square, triangular and king lattices. We determine properties on the subdivision of an i-packing in several j-packings, for j>i. These results allow us to determine S-packing coloring of these lattices for several sequences of integers. We examine a class of graph that has never been studied for S-packing coloring: the subcubic graphs. We determine that every subcubic graph is (1,2,2,2,2,2,2)-colorable and (1,1,2,2,3)-colorable. Few results are proven about some subclasses. Finally, we study the Grundy number of regular graphs. We determine a characterization of the cubic graphs with Grundy number 4. Moreover, we prove that every r-regular graph without induced square has Grundy number r+1, for r<5.
27

Mimeze pestřenkovitých (Diptera: Syrphidae) v kontextu selekčních tlaků ze strany predátorů, termoregulace a pohlavního výběru / Mimicry of hoverflies (Diptera: Syrphidae) in the context of selection pressures from predators, thermoregulation and sexual selection

Daňková, Klára January 2019 (has links)
Thermoregulation plays an important role in organisms' lives during foraging, escaping from predators, sexual selection or overwintering. Moreover, pressure on efficient thermoregulation could affect species on an evolutionary level and was recently hypothesized to maintain imperfect mimicry in hoverflies (Diptera, Syrphidae). We set these two aims: 1) to study relationships between thermoregulation, mimicry accuracy and resembled model, 2) to closely study effect of developmental temperature in an intermediately accurate honeybee mimic, Eristalis tenax. In the first part of the project, we examined temperature excess of 566 specimens in 47 species of hoverflies in the field. We did not find significant effect of mimicry accuracy on temperature excess in our data. However, we found a strong sexual dimorphism. Females had lower temperature excess, which was very resilient to internal and external factors, whereas males had higher temperature excess, influenced by activity at time of capture (flying > sitting) and resembled model (bumblebee-mimics > honeybee- mimics > wasp-mimics > solitary bee-mimics). We suggest, that males are pushed to higher temperature excess by sexual selection within lekking. In the second part of the project, we reared E. tenax in three different temperatures in laboratory...
28

Understanding of correlation between size and coloration of Copper Gallium Oxide and its application in perovskite solar cell

Yu, Yongze, Yu January 2016 (has links)
No description available.
29

Rendimento e cor de selênio e seus compostos na coloração de vidros sodo-cálcicos. / Income and color of selenium and its compounds in the soda-lime-silica glasses coloration.

Felisberto, Camila Benini 23 November 2006 (has links)
Vidros comerciais de base silicato do tipo sodo-cálcico, apresentam coloração pela presença de óxidos de metais de transição, tais como ferro e cobalto, ou pela presença de elementos não-metálicos, tais como o selênio. Geralmente, a presença de selênio metálico (Se°) num vidro silicato confere-lhe a cor rosa (depende de seu estado de oxidação). Desse modo, industrialmente, adiciona-se selênio à composição de vidros quando se deseja produzir vidros róseos ou, mais freqüentemente, quando se deseja mascarar a cor esverdeada conferida pela presença de ferro, o principal contaminante das matérias-primas naturais. Entretanto, o selênio é encontrado em pequenas quantidades na natureza, daí seu alto custo. Além disso, da quantidade inicial de selênio colocada na composição de vidros industriais sodo-cálcicos, quase 80% são vaporizados durante a etapa de fusão do vidro. Este trabalho é dedicado ao estudo do efeito da adição de diferentes compostos portadores de selênio como matéria-prima em substituição ao selênio metálico, visando a redução da volatilização de selênio durante a fusão. Além do selênio metálico, foram utilizados selenitos de sódio, de bário, de zinco e de ferro. Os vidros foram obtidos por fusões em escala de laboratório, em cadinhos de alta alumina, a 1500°C, em forno elétrico. A seguir determinou-se a composição química de cada vidro obtido, por fluorescência de raios X e sua cor, através da determinação de suas coordenadas cromáticas no sistema CIEL*a*b*. A análise dos resultados teve como principal conclusão que a concentração final de selênio no vidro é função apenas de sua quantidade no banho, independentemente do composto químico que lhe forneceu. / Commercial silicate glasses of the soda-lime system attain color by the presence of transition metal oxides, such as iron and cobalt, or by the presence of non-metallic elements, like selenium. Usually, the presence of metallic selenium (Se°) in a silicate glass results in a light pink coloration (depends on its oxidation state). Therefore, industrially, selenium is added to a glass composition when the objective is to obtain a pink color glass, or, more often, when the objective is to mask the greenish coloration resultant from the presence of iron, the most usual contaminant in the natural raw-materials. However, selenium occurs in the nature only in small quantities. Besides, from the initial selenium added to industrial soda-lime batch compositions, almost 80% volatilize during melting. This work is dedicated to the study of the effect of adding selenium from different raw-materials, substituting for the metallic selenium, with the principal objective of reducing the loss of this element during glass melting. Along with metallic selenium, sodium, barium, zinc, and iron selenites were employed. The glasses were obtained in laboratory scale meltings in alumina crucibles, at 1500°C, in an electrical furnace. After that, the chemical composition of each glass was obtained by X-ray fluorescence, and its color was measured according to the chromatic coordinates in the CIEL*a*b* method. The main conclusion that can be drawn from the analysis of the results is that the selenium concentration in the final glass is a function only of the quantity of selenium present in the melt, independently of the chemical compound which supplied such selenium.
30

Circular coloring and acyclic choosability of graphs / Coloration circulaire et coloration acyclique par listes de graphes

Roussel, Nicolas 14 December 2009 (has links)
Dans cette thèse, nous nous intéressons à la coloration circulaire des graphes planaires. Des bornes supérieures ont été données pour des graphes avec degré maximum borné, avec girth, la longueur de son plus petit cycle, bornée, avec des cycles manquants, etc. Ici nous donnerons de nouvelles bornes pour les graphes avec degré moyen maximum borné. Nous étudions également la coloration totale et la coloration (d,1)-totale de plusieurs familles infinies de graphes. Nous décrivons le nouveau concept de coloration (d,1)-totale circulaire. Enfin, nous discutons les conditions nécessaires pour qu'un graphe planaire admette une coloration acyclique par listes de taille 4. / In this thesis, we study the circular coloring of planar graphs. Upper bounds have been given for graphs with bounded maximum degree, with bounded girth, that is the length of its smallest cycle, with missing cycles, and so on. It has also been studied for graphs with bounded maximum average degree. Here we give new upper bounds for that latter case. We also study the total coloring and ($d,1$)-total labeling of a few infinite families of graphs and describe the new concept of circular ($d,1$)-total labeling of graphs. In the last part, we will discuss conditions for a planar graph to be acyclically $4$-choosable.

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