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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.
11

Análise ecológica da helmintofauna do sabiá-laranjeira Turdus rufiventris e do pardal Passer domesticus na Região Metropolitana de Porto Alegre, RS

Marques, Cláudia Calegaro January 2006 (has links)
O Brasil é um dos países com a maior riqueza de aves do mundo (1.677 espécies). A Ordem Passeriformes detém 56% desta riqueza, incluindo o sabiálaranjeira Turdus rufiventris e o pardal Passer domesticus (introduzido), espécies cuja composição, padrão e estrutura da comunidade de helmintos foram investigadas nesta pesquisa. As aves (N=160 de cada espécie) foram capturadas com o auxílio de alçapões e de redes de neblina em paisagens urbanas e rurais da Região Metropolitana de Porto Alegre, RS. Quinze espécies de helmintos foram encontradas no sabiá-laranjeira (sete nematóides, quatro digenéticos, três cestóides e um acantocéfalo), com riqueza média de 2,92 espécies/hospedeiro. No pardal, a riqueza média foi de 0,19 espécies/hospedeiro e cinco espécies de helmintos foram encontradas (dois digenéticos, dois nematóides e um cestóide). Nove espécies foram dominantes, cinco co-dominantes e uma subordinada na comunidade de helmintos do sabiá, enquanto para o pardal, quatro espécies foram dominantes e uma co-dominante. Machos e fêmeas adultos das duas espécies hospedeiras apresentaram comunidades de parasitos semelhantes. Os sabiás-laranjeira adultos, por sua vez, tiveram uma maior riqueza de parasitos do que os juvenis. A fauna parasitária encontrada nestas espécies hospedeiras reflete em grande parte a dieta das aves, considerando que muitas das espécies de helmintos são adquiridas através da ingestão de hospedeiros intermediários infectados. As variações na prevalência apresentada por algumas espécies de helmintos entre as diferentes estações do ano e na riqueza da helmintofauna entre as paisagens rural e urbana são compatíveis com possíveis diferenças na disponibilidade de invertebrados e/ou de outros itens alimentares (tais como frutos) nestas épocas e/ou paisagens dominadas por ambientes distintos.
12

Análise ecológica da helmintofauna do sabiá-laranjeira Turdus rufiventris e do pardal Passer domesticus na Região Metropolitana de Porto Alegre, RS

Marques, Cláudia Calegaro January 2006 (has links)
O Brasil é um dos países com a maior riqueza de aves do mundo (1.677 espécies). A Ordem Passeriformes detém 56% desta riqueza, incluindo o sabiálaranjeira Turdus rufiventris e o pardal Passer domesticus (introduzido), espécies cuja composição, padrão e estrutura da comunidade de helmintos foram investigadas nesta pesquisa. As aves (N=160 de cada espécie) foram capturadas com o auxílio de alçapões e de redes de neblina em paisagens urbanas e rurais da Região Metropolitana de Porto Alegre, RS. Quinze espécies de helmintos foram encontradas no sabiá-laranjeira (sete nematóides, quatro digenéticos, três cestóides e um acantocéfalo), com riqueza média de 2,92 espécies/hospedeiro. No pardal, a riqueza média foi de 0,19 espécies/hospedeiro e cinco espécies de helmintos foram encontradas (dois digenéticos, dois nematóides e um cestóide). Nove espécies foram dominantes, cinco co-dominantes e uma subordinada na comunidade de helmintos do sabiá, enquanto para o pardal, quatro espécies foram dominantes e uma co-dominante. Machos e fêmeas adultos das duas espécies hospedeiras apresentaram comunidades de parasitos semelhantes. Os sabiás-laranjeira adultos, por sua vez, tiveram uma maior riqueza de parasitos do que os juvenis. A fauna parasitária encontrada nestas espécies hospedeiras reflete em grande parte a dieta das aves, considerando que muitas das espécies de helmintos são adquiridas através da ingestão de hospedeiros intermediários infectados. As variações na prevalência apresentada por algumas espécies de helmintos entre as diferentes estações do ano e na riqueza da helmintofauna entre as paisagens rural e urbana são compatíveis com possíveis diferenças na disponibilidade de invertebrados e/ou de outros itens alimentares (tais como frutos) nestas épocas e/ou paisagens dominadas por ambientes distintos.
13

Passermessung an Druckmaschinen mit konventioneller Videotechnik

Loh, Gerald 11 December 2006 (has links)
Zur genauen Justage und objektiven Qualitätsprüfung von Druckmaschinen ist ein hochgenaues Messgerät zur Passermessung sinnvoll. Ein solches Messsystem wurde unter Verwendung konventioneller Videotechnik basierend auf Bildanalysetechnologien entwickelt. Speziell für das Messsystem entworfene Messelemente werden zur Passermessung gedruckt, mit Videotechnik digitalisiert und mit Hilfe von Bildanalysetechnologien erkannt, bewertet und vermessen. Auf dem Entwicklungsweg zu diesem Messsystem wurden verschiedene Problemkreise analysiert und gelöst. Dazu zählen beispielsweise Methoden zur Signalerfassung und zur Korrektur von Fehlern in optischen Abbildungssystemen. Ausgehend von einer Bewertung bekannter Lösungen zur Passermessung werden Technologien und Strategien für ein Messverfahren zur Passermessung mit konventioneller Videotechnik am Beispiel der Übergabepassermessung aufgezeigt. Nachweismöglichkeiten zur Prüfung der Technologie und Schlussfolgerungen wie wünschenswerte Forderungen für die Zukunft, beispielsweise für Folge- und Weiterentwicklungen, werden formuliert. / A high-precision instrument for register measurement is useful for the exact adjustment and quality control of printing presses. Such a measuring system has been developed on the basis of image analysis methods and the application of conventional video technology. Measuring elements specially designed for the measuring system are printed for register measurement, digitalized with video technology and recognized, evaluated and measured with the help of image analysis methods. On the way to the development of this measuring system various complexes of problems were analysed and solved, among them, for instance, methods of signal recognition and correction of errors in optical imaging systems. Proceeding from the evaluation of known solutions for register measurement, methods and strategies are demonstrated for a method of register measurement with conventional video technology using transfer register measurement as an example. Possibilities to proof the verification of the method, conclusions and desirable demands for the future, such as follow-up and further developments have been formulated.
14

The role of social interactions on the development and honesty of a signal of status

Diep, Sanh K 01 January 2012 (has links)
Badges of status are supposed to have insignificant production costs, so use costs are thought to be most important in ensuring signal reliability. Use costs arise from the use of the status signal in social interactions. Social experiences that arise from the use of inappropriate signals in social interactions may drive mechanisms that result in reduced fitness for inappropriate signalers. The role of social control, probing and familiarity in producing use costs was explored. There was no evidence that social control by dominants produced a cost for cheaters and no evidence that social control by subordinates produced a cost for inappropriate signaling by Trojans. Probing produced a cost for cheating when resource value was high but not when resource value was low. Familiarity had some effect on the cost and benefit of cheating but in patterns that were not predicted. Familiarity both eliminated a benefit of cheating and reduced a cost of cheating; therefore it is uncertain how familiarity affects honest signaling. The status signal of the receiver had no effect on the cost or benefits of cheating, and there was no evidence of punishment. Social experiences have the potential to affect signal development to produce a correspondence between signal and status. The effects of social experience on signal production were examined and there was little evidence that social experience influenced bib development. Neither aggression expressed nor aggression received was not predictive of bib size. Additionally, tests on the different measures of winning experience produced conflicting conclusions regarding the relationship between winning experience and bib development.
15

Host-Parasite Interactions in an Invasive Songbird

Coon, Courtney A.c. 10 April 2014 (has links)
Introduced species are the greatest threat to biodiversity after habitat loss. Understanding the processes that permit organisms to become successful invaders may provide opportunities to prevent or limit their dispersal and establishment and thereby alleviate some of their harmful effects. The goal of my dissertation research has been to investigate whether invasive species have distinctive interactions with parasites, and some of the mechanisms that may underlie that variation. I used one of the world's most successful vertebrate invaders as a case study: the house sparrow (Passer domesticus; Introduction). Previous research in the house sparrow suggested that loss of parasite diversity may contribute to invasion success. However, my work demonstrates that infection with common avian malaria parasites is primarily a function of environmental heterogeneity and is not a predictor of time since introduction for house sparrows that are currently expanding their range in Kenya (Chapter 1). Interestingly, in spite of a large proportion of the population being infected with avian malaria, a state that should reduce competitive ability of house sparrow populations, this species is still able to establish themselves among native competitors. Though there are a number of potential mechanisms that could explain this pattern, one of the most convincing explanations is that house sparrows, and perhaps other introduced species, have adaptive differences in immunity. As such, the findings of Chapter 1 inspired two studies in which my collaborators and I showed that house sparrows from two non-native populations seem capable of maintaining normal health, performance and behavior during immune challenge, a response often referred to as parasite tolerance. Specifically, in Chapter 2, we found that when Floridian house sparrows, established since ~1870, were challenged with synthetic pathogens that mimicked infection with a fungi, an RNA virus or Gram-negative bacteria, only individuals challenged by the synthetic bacteria showed measurable sickness behaviors and secretion of an inflammatory protein. In Chapter 3, we compared parasite tolerance in Kenyan house sparrows (introduced in ~2000) and a native congener, the grey-headed sparrow (P. griseus) to a common intestinal parasite of songbirds. We found that both species were tolerant in that they were able to maintain fat reserves, protein reserves and vertical flight ability during infection. However, house sparrows maintained burdens that were, on average, more than 10x those of grey-headed sparrows. Moreover, when examining nutrient allocation in the two species, house sparrows appeared to assimilate nutrients more efficiently than grey-headed sparrows and did not change how nutrients were allocated among immune and reproductive organs during experimental infection. Grey-headed sparrows, however, did shift nutrient allocation among immune and reproductive organs during experimental infection. Together, the larger nutrient pool and maintenance of nutrient allocation patterns in challenged house sparrows suggests that no physiological trade-offs occurred and that house sparrows experienced a lower cost of parasite exposure. In the fourth Chapter, I explored why house sparrows had such high coccidia burdens in comparison to their congeners. We suspected burden was a function of the frequency of exposure to coccidia. Consequently, we explored heterogeneity in foraging preferences and other behaviors in Floridian house sparrows and their role in coccidia burden. As expected, we found that house sparrows did not avoid contaminated food. In fact, they ate contaminated and uncontaminated foods indiscriminately. What was surprising was a lack of correlation between burden and consumption of contaminated foods and all of the behaviors we monitored (i.e., aggression, activity, feeding rates and defecation frequency). Overall, these data suggest that house sparrows do not benefit from typical parasite-avoidance behaviors. In sum, this dissertation research implies that house sparrows respond to parasite infection differently than many other known vertebrates, most likely in an effort to maximize efficient use of resources and, in so doing, augment competitive ability and invasion success.
16

Embryonic Mortality and Sex Ratios in the Tree Sparrow

Svensson, Magnus January 2006 (has links)
<p>Tree sparrows (Passer montanus) have been studied in two areas in Sweden since 1997. At both sites, tree sparrow eggs had remarkably low hatching success. On average only 60% of the eggs hatched. Analyses have shown that this was caused by embryonic mortality, which was highly sex biased. About 70 % of the dead embryos were males, while about 65 % of all fledged nestlings were females. Impaired hatching success here related to two factors. Hatching success was lower for pairs with a male in poor body condition, and it was lower in areas with a high local population density. </p><p>A sex bias in the mortality early in life has been demonstrated in several species. Since the competitive ability of males is determined by conditions early in life, parents with poor provisioning capacity should prefer to produce female offspring in broods reared under poor conditions. The body condition of a tree sparrow during the nestling stage was well correlated to the condition as an adult, and pairs in which the male parent was in poor condition produced chicks in poor condition. Since the breeding success of a pair depended more on the condition of the male, females appear less affected by conditions early in life. Parents with poor provisioning capacity appear to bias offspring survival towards females, and a difference in the early susceptibility may be adaptive. </p><p>Changes in birth sex ratios have in some cases been suspected to result from exposure to estrogenic environmental pollutants. This was examined by exposing great- and blue tit embryos to a synthetic estrogen. Although there was a difference in the mortality rate, the difference was present also in the control groups, why this could not be attributed to estrogen exposure.</p>
17

Embryonic Mortality and Sex Ratios in the Tree Sparrow

Svensson, Magnus January 2006 (has links)
Tree sparrows (Passer montanus) have been studied in two areas in Sweden since 1997. At both sites, tree sparrow eggs had remarkably low hatching success. On average only 60% of the eggs hatched. Analyses have shown that this was caused by embryonic mortality, which was highly sex biased. About 70 % of the dead embryos were males, while about 65 % of all fledged nestlings were females. Impaired hatching success here related to two factors. Hatching success was lower for pairs with a male in poor body condition, and it was lower in areas with a high local population density. A sex bias in the mortality early in life has been demonstrated in several species. Since the competitive ability of males is determined by conditions early in life, parents with poor provisioning capacity should prefer to produce female offspring in broods reared under poor conditions. The body condition of a tree sparrow during the nestling stage was well correlated to the condition as an adult, and pairs in which the male parent was in poor condition produced chicks in poor condition. Since the breeding success of a pair depended more on the condition of the male, females appear less affected by conditions early in life. Parents with poor provisioning capacity appear to bias offspring survival towards females, and a difference in the early susceptibility may be adaptive. Changes in birth sex ratios have in some cases been suspected to result from exposure to estrogenic environmental pollutants. This was examined by exposing great- and blue tit embryos to a synthetic estrogen. Although there was a difference in the mortality rate, the difference was present also in the control groups, why this could not be attributed to estrogen exposure.
18

Does a high fundamental corticosterone concentration negatively affect the ornaments and visible sexual traits of male house sparrows (Passer domesticus)?

Nord, Iza January 2013 (has links)
The male house sparrows has two assumed visible sexual traits which are 1) the colouration (or brightness) of the beak and 2) the size of the black badge on the bird’s throat and chest. Earlier research has shown that the testosterone concentration play an important part in determine the beak colour, with a higher testosterone concentration giving the bird a darker beak and as such making the male more attractive to females.     Even though stress has been counted for as a changing factor of phenotypes and behaviour it is not certain how vast effect stress has on different animals. This study is focusing on how and if the individuals fundamental stress level (fundamental corticosterone concentration) is affecting the morphological appearance, in this case the visible sexual traits (beak colour and badge size) and mask (an indicator of age), within the house sparrows in the Lundy Island population. In this study there was no relationship between beak colour and corticosterone concentrations, stating that beak brightness is not determined by fundamental stress. Likewise there was no relationship between the corticosterone concentrations and the size of the badge. Mask measurements in relationship to corticosterone showed no significant effect. These results indicate that there is no relationship between the corticosterone concentration in the blood and the mask size or the beak colour and badge size as visible sexual traits. / Många forskare är ense om att gråsparvshannen använder sig av två synliga karaktärsdrag för att attrahera honor. Den första är mörkhetsgraden på näbben och den andra är storleken på hannens svarta bröstlapp, placerad på hals och bröst. Tidigare forskning har visat att näbbfärgen påverkas kraftigt av hannens testosteron nivå och att en högre testosteron nivå leder till en mörkare näbb, vilket är mer attraktivt för honorna.    Även om stress har visat sig påverka både fenotyp och beteende hos många olika djurgrupper är det fortfarande oklart hur stor effekt stress har på olika djur. Denna studie fokuserar på hur och om den individuella fundamentala stressnivån (den fundamentala kortikosteron nivån) påverkar de synliga attraherande karaktärsdragen (näbbfärg och bröstlappsstorlek) hos gråsparvshannarna. I denna rapport analyseras även hannarnas masker, vilka fungerar som åldersindikatorer, i relation till de individuella kortikosteron koncentrationerna. Inget samband kunde hittas mellan näbbfärg och kortikosteron nivå hos de analyserade individerna. Likaså kunde inget samband hittas mellan kortikosteron nivån och storleken på hannens bröstlapp. Inte heller maskstorleken visade samband med kortokosteron nivån. Resultatet indikerar således att stress inte påverkar hannens sexuellt attraktiva karaktärsdrag eller mask.
19

Ethos d’une transfuge intellectuelle : présentation de soi dans L’écriture comme un couteau et Les années d’Annie Ernaux

Lefebvre-Côté, Béatrice 08 1900 (has links)
Comment se dire « intellectuelle » lorsque, comme Annie Ernaux, on porte la double illégitimité du transfuge de classe et du sujet féminin, pratiquement absent des figures d’intellectuels en France ? Pourtant, la conception d’Annie Ernaux de l’écriture comme un acte politique et ses prises de position fréquentes dans les médias français la rapprochent de la figure de l’intellectuel. Ce mémoire se propose ainsi de formuler dans un premier temps une définition de l’intellectuelle, à partir de laquelle il sera possible de penser l’engagement de l’auteure et sa présentation de soi dans l’espace public. Par l’étude de l’entretien L’écriture comme un couteau (2003), puis de l’autobiographie impersonnelle Les années (2008), il s’agira dans un second temps de montrer comment Annie Ernaux présente un ethos d’intellectuelle et de voir comment elle dépasse le modèle de l’intellectuelle « qui se mêle de ce qui ne le regarde pas » (Sartre, 1972), grâce à la variété de voix qu’elle adopte dans ses écrits : celles de l’autobiographe, de l’ethnologue, de l’auteure « impliquée », de la transfuge, de la « cheftaine » de famille, de la femme vieillissante. Si elle en dépasse le modèle, n’est-ce pas également parce qu’elle s’identifie d’abord à sa situation de transfuge de classe ? Traversée par les sentiments de culpabilité et de responsabilité propres au transfuge, l’auteure fait de sa position de l’entre-deux classes un moteur d’écriture, pour donner une voix aux dominés au sein de son œuvre auto-socio-biographique. L’analyse de L’écriture comme un couteau esquissera ainsi les bases conceptuelles de son ethos de transfuge intellectuelle, alors que dans Les années, l’étude des voix narratives au « on », au « nous » et au « elle » explorera l’entrelacement de l’intime au social, de l’expérience singulière à la mémoire collective. En somme, par l’attention accordée à l’ethos dans ces deux œuvres, ce mémoire se propose d’étudier comment Annie Ernaux se constitue comme une figure légitime de transfuge et d’intellectuelle au sein de l’espace public de son époque. / How can an author call himself an « intellectual », especially when one, such as Annie Ernaux, cumulates both the illegitimacy of a class-passer and a feminine subject? Yet, her vision of writing as a political activity and her positions in the media do assimilate her to the figure of the intellectual. This dissertation thereby aims to provide a definition of the intellectual woman, to which Annie Ernaux’s example contributes significantly. Studying the author interview L’écriture comme un couteau (2003) and her impersonal autobiography Les années (2008), I intend to show how Annie Ernaux displays the ethos of an intellectual and even moves beyond the model, while she embodies the figures of the autobiographer, the ethnologist, the "involved" writer, the class-passer, the head of family, and the aging woman. If she surpasses that model, isn’t it also because she primarily identifies herself as a class-passer? Driven by the class-passer’s sense of guilt and responsibility, Annie Ernaux uses the sensation of being in-between social classes to enable her writing. Therefore, her auto-socio-biographical works become a literary commitment to the dominated. The study of L’écriture comme un couteau will define the conceptual basis of Annie Ernaux’s ethos as an class-passer intellectual, while in Les années, the analysis of the narrative voices « on », « nous » and « elle » will explore how the intimate intricates itself to the social, the subjective experience to the collective memory. In other words, while studying the ethos in Annie Ernaux’s works, this dissertation examines how the author has shaped an image of herself as a legitimate class-passer intellectual within the public sphere of her time.

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