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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.
41

Evolution of central complex development: Cellular and genetic mechanisms

Farnworth, Max Stephen 30 September 2019 (has links)
No description available.
42

Moderní jednotka pro energetické využití odpadů o střední kapacitě / Up-to-Date Medium Capacity Waste-to-Energy Unit

Krišpín, Jan January 2017 (has links)
The submitted Master Thesis deals with the technological/mechanical solution of an up-to-date medium capacity waste-to-energy plant. Operational requirements and basic parameters related to a concrete region are specified in the introduction of the Thesis. This is supplemented by a flow-sheet of the plant with the description of main process subsystems. To meet the goals of the Thesis basic balance information is summarized and related schemes included. These data represent principal inputs for the on-site plant as well as basic parameters for the design of key equipment. These pieces of equipment are schematically drawn including their basic parameters and a description of construction. All the available innovative solutions are taken into account. The Thesis provides also a technical-economic analysis for being able to evaluate the overall project.
43

Technicko-ekonomické modely spaloven komunálního odpadu s využitím energie / Technical-economic models of waste-to-energy plants

Čech, Martin January 2012 (has links)
Main principle of the thesis is to create technical-economic model of municipal waste-to-energy plant. This model is suitable for different technical parameters of various incinerators and there is not necessary to create new model for each new incinerator. The model also includes basic economic aspects of technology and service of the municipal waste incinerator. The importance of municipal waste incinerator construction, their current situation and planned future in Czech Republic are also mentioned in the thesis.
44

Molecular, Cellular and Mechanical basis of Epithelial Morphogenesis during Tribolium Embryogenesis

Jain, Akanksha 11 September 2018 (has links)
Embryonic development entails a series of morphogenetic events which require a precise coordination of molecular mechanisms coupled with cellular dynamics. Phyla such as arthropods show morphological and gene expression similarities during middle embryogenesis (at the phylotypic germband stage), yet early embryogenesis adopts diverse developmental strategies. In an effort towards understanding patterns of conservation and divergence during development, investigations are required beyond the traditional model systems. Therefore, in the past three decades, several insect species representing various insect orders have been established as experimental model systems for comparative developmental studies. Among these, the red flour beetle Tribolium castaneum has emerged as the best studied holometabolous insect model after the fruit fly Drosophila melanogaster. Unlike Drosophila, Tribolium is a short-germ insect that retains many ancestral characters common to most insects. The early embryogenesis of Tribolium shows dynamic epithelial rearrangements with an epibolic expansion of the extraembryonic tissue serosa over the embryo, the folding of the embryo in between the serosa and the second extra embryonic tissue amnion and the folding of the amnion underneath the embryo. These extensive tissues are evolutionarily conserved epithelia that undergo different tissue movements and are present in varying proportions in different insects, providing exceptional material to compare and contrast morphogenesis during early embryogenesis. However, most of the previous work on insects including Tribolium have largely focused on the conservation and divergence of gene expression patterns and on gene regulatory interactions. Consequently, very little studies on dynamic cell behaviour have been done and we lack detailed information about the cellular and tissue dynamics during these early morphogenetic events. During my PhD, I first established a live imaging and data analysis pipeline for studying Tribolium embryogenesis in 4-D. I combined live confocal and lightsheet imaging of transgenic or transiently labelled embryos with mechanical or genetic perturbations using laser ablations and gene knockdowns. Using this pipeline quantifications of cell dynamics and tissue behaviours can be done to compare different regions of the embryo as the development proceeds. In the second and third part of my thesis, I describe the actomyosin dynamics and associated cell behaviours during the stages of serosa epibolic expansion, amniotic fold formation and serosa window closure. I cloned and characterised the cellular dynamics of the Tribolium spaghetti squash gene (Tc-squash) - the non-muscle Myosin II regulatory light chain, which is the main molecular force generator in epithelial cells. Interestingly, the analysis of Tc-squash dynamics indicates a conserved role of Myosin II in controlling similar cell behaviours across short germ and long germ embryos. In the last part of the thesis, I report the dynamics of an actomyosin cable that emerges at the interface of the serosa and amnion. This cable increases in tension during development, concomitant with serosa tissue expansion and increased tensions in the serosa. It behaves as a modified purse string as it’s circumference shrinks due to a decrease in the number of cable forming cells over time. This shrinkage is an individual contractile property of the cells forming the cable. This indicates that a supracellular and contractile actomyosin cable might be functional during serosa window closure in insects with distinct serosa and amnion tissues. Further, the tension in the cable might depend on the relative proportion of the serosa, amnion and embryonic regions. Using these integrated approaches, I have correlated global cellular dynamics during early embryogenesis with actomyosin behaviours, and then performed a high-resolution analysis and perturbations of selected events. The established imaging, image processing and perturbation tools can serve as an important basis for future investigations into the tissue mechanics underlying Tribolium embryogenesis and can also be adapted for comparisons of morphogenesis in other insect embryos. More broadly, correlating the existing genetic, mechanical and biochemical understanding of developmental processes from Drosophila with species such as Tribolium, could help identify deeply conserved design principles that lead to different morphologies through differences in underlying regulation.:Page List of Tables v List of Figures vii 1 Introduction 1 1.1 Evo-Devo of insects 3 1.2 Tribolium castaneum 5 1.3 Fluorescence live imaging and lightsheet microscopy 10 1.4 Morphogenesis 15 1.5 Thesis objective 29 2 4D lightsheet imaging and analysis pipeline of Tribolium embryos 33 2.1 Standardisation of an injection protocol for sample mounting and imaging with the Zeiss LZ1 SPIM 35 2.2 Double labelling of Tribolium embryos 37 2.3 Image processing with Fiji 37 2.4 Long term timelapse imaging of Tribolium embryogenesis with SPIM 44 2.5 2D cartographic projections of 3D data as a method to visualise and analyse SPIM data 47 2.6 Summary 59 3 Cellular dynamics of the non muscle Myosin II regulatory light chain - Tc-Squash 61 3.1 Tc-Squash dynamics during Tribolium embryogenesis 64 3.2 Myosin drives basal cell closure during blastoderm cellularisation 66 3.3 Myosin shows planar polarity in the embryonic tissue 69 3.4 Myosin accumulation and apical constriction of putative germ cells at the posterior pole 71 3.5 Myosin pulses during apical constriction of mesoderm cells 74 3.6 Myosin accumulates at the extraembryonic-embryonic boundary to form a contractile supracellular cable 77 3.7 Summary 77 4 A supracellular actomyosin cable operates during serosa epiboly 79 4.1 Actin and Myosin accumulate at the extraembryonic-embryonic boundary 81 4.2 The actomyosin assembly migrates ventrally till it forms the rim of the serosa window 82 4.3 The actomyosin cable shows dynamic shape changes during serosa window closure 87 4.4 Serosa cells increase in area till circular serosa window stage 89 4.5 Tension in the serosa tissue increases during epibolic expansion 89 4.6 Serosa cells decrease their apical areas after laser ablation 92 4.7 Tension in the actomyosin cable increases during serosa epiboly 93 4.8 Myosin dynamics at the cable changes between early and serosa window stage 96 4.9 Individual cell membrane shrinkage and cell rearrangements decrease the cable circumference 98 4.10 Myosin dynamics at the cable during serosa window closure 101 4.11 Tension in the cable is not relieved after multiple laser cuts 103 4.12 Analysis of the actomyosin cable in Tc-zen 1 knockdown 105 4.13 Summary 109 5 Discussion 111 5.1 Reconstruction of insect embryogenesis using lightsheet microscopy and tissue cartography 111 5.2 Conserved Myosin II behaviours and its implications on morphogenesis across insects 114 5.3 A contractile supracellular actomyosin cable functions serosa window closure in Tribolium 119 6 Materials and Methods 123 6.1 Tribolium stock maintenance 123 6.2 RNA extraction and cDNA synthesis 124 6.3 Cloning of templates for mRNA synthesis and transgenesis 124 6.4 dsRNA synthesis for RNAi experiments 126 6.5 Capped, single stranded RNA synthesis 126 6.6 Fluorescence image acquisition 27 A Appendix 131 Bibliography 143
45

Framing indigenous identity in Bolivia : A qualitative case study of the lowland indigenous peoples mobilization in the TIPNIS conflict

Rechlin, Elsa January 2021 (has links)
Evo Morales became Latin Americas first indigenous president in 2005. Morales praised the indigenous peoples, the indigenous movements and aimed at ending their political marginalization in Bolivia. However, this politicization and framing of indigenous identity and rights was later turned into his disadvantage. In 2011, Confederation of Indigenous Peoples of Eastern Bolivia (CIDOB) decided to mobilize against the government's decision to build a highway through Isiboro Secure National Park and Indigenous Territory (TIPNIS), where three of the indigenous groups represented by CIDOB lives. The decision was taken without consolidation with the population living in the area. In this study Robert D. Benford and David A. Snow's theoretical framework concerning framing processes and social movements are used to analyze CIDOBs collective action framing of their indigenous identity and rights in their mobilization in the TIPNIS conflict. In the result, it became evident that CIDOB used their indigenous identity and rights in different framing strategies including master frames, frame alignment processes, diagnostic, and prognostic framing.
46

The Regulation of Ontogenetic Diversity in Papaveraceae Compound Leaf Development

Plant, Alastair R. 25 September 2013 (has links)
No description available.
47

Experiências com desenvolvimento ágil / Experiences with agile development

Bassi Filho, Dairton Luiz 18 March 2008 (has links)
A crescente demanda por sistemas e a alta velocidade com que seus requisitos evoluem têm evidenciado que desenvolvimento de software exige flexibilidade, pois muitas decisões precisam ser tomadas durante o projeto. Além disso, as dificuldades para a produção de sistemas vão muito além das questões técnicas. Fatores estratégicos, comerciais e humanos são responsáveis por algumas das variáveis que contribuem para tornar o desenvolvimento de sistemas de software uma atividade altamente complexa. Modelos tradicionais de desenvolvimento de software propõem processos prescritivos que não consideram toda essa complexidade. Por outro lado, Métodos Ágeis de desenvolvimento de software sugerem uma abordagem mais humanística com foco na entrega rápida e constante de software com valor de negócios. Porém, para conseguir isto, é preciso escolher um conjunto de práticas de desenvolvimento adequado às características do projeto e da equipe. Desta forma, a natureza única de cada projeto e a necessidade de alta qualidade e produtividade tornam importante a busca por práticas de desenvolvimento. A partir de projetos que conduzimos usando métodos ágeis na academia e na indústria, identificamos e descrevemos 22 práticas para desenvolvimento de software que podem ser adotadas por equipes para aumentar o seu desempenho e/ou a qualidade do software. / The growing demand for systems and the high speed with which their requirements evolve has shown that software development requires flexibility because many decisions need to be taken during the project. Also, the difficulties for the production of software systems go far beyond the technical issues. Strategic, commercial and human factors are responsible for some variables that contribute to make the software development a highly complex activity. Traditional models of software development propose prescritive processes that do not consider all this complexity. On the other hand, Agile Methods of software development suggest an humanistic approach focused on fast and often business valuable software deliveries. But, in order to get it, one needs to choose an appropriated group of development practices accordingly to the project and team features. In this way, the individuality of each project and the need for better quality and productivity motivate the search for software development practices. Based on projects that we conducted by using agile methods in academic and industry environments we identified and described 22 software development practices that can be used by teams to increase their performance and/or the software quality.
48

Experiências com desenvolvimento ágil / Experiences with agile development

Dairton Luiz Bassi Filho 18 March 2008 (has links)
A crescente demanda por sistemas e a alta velocidade com que seus requisitos evoluem têm evidenciado que desenvolvimento de software exige flexibilidade, pois muitas decisões precisam ser tomadas durante o projeto. Além disso, as dificuldades para a produção de sistemas vão muito além das questões técnicas. Fatores estratégicos, comerciais e humanos são responsáveis por algumas das variáveis que contribuem para tornar o desenvolvimento de sistemas de software uma atividade altamente complexa. Modelos tradicionais de desenvolvimento de software propõem processos prescritivos que não consideram toda essa complexidade. Por outro lado, Métodos Ágeis de desenvolvimento de software sugerem uma abordagem mais humanística com foco na entrega rápida e constante de software com valor de negócios. Porém, para conseguir isto, é preciso escolher um conjunto de práticas de desenvolvimento adequado às características do projeto e da equipe. Desta forma, a natureza única de cada projeto e a necessidade de alta qualidade e produtividade tornam importante a busca por práticas de desenvolvimento. A partir de projetos que conduzimos usando métodos ágeis na academia e na indústria, identificamos e descrevemos 22 práticas para desenvolvimento de software que podem ser adotadas por equipes para aumentar o seu desempenho e/ou a qualidade do software. / The growing demand for systems and the high speed with which their requirements evolve has shown that software development requires flexibility because many decisions need to be taken during the project. Also, the difficulties for the production of software systems go far beyond the technical issues. Strategic, commercial and human factors are responsible for some variables that contribute to make the software development a highly complex activity. Traditional models of software development propose prescritive processes that do not consider all this complexity. On the other hand, Agile Methods of software development suggest an humanistic approach focused on fast and often business valuable software deliveries. But, in order to get it, one needs to choose an appropriated group of development practices accordingly to the project and team features. In this way, the individuality of each project and the need for better quality and productivity motivate the search for software development practices. Based on projects that we conducted by using agile methods in academic and industry environments we identified and described 22 software development practices that can be used by teams to increase their performance and/or the software quality.
49

Molecular Evolution of Mammalian Sex Differentiation

Chung, Wai Yee 07 June 2024 (has links)
Die embryonale Gonade ist bei Säugetieren das einzige bipotente Organ, das sich während der Geschlechtsbestimmung in Hoden oder Eierstock differenziert. Nach der Spezifikation produziert sie geschlechtsspezifische Hormone, die wichtige morphologische, physiologische und Verhaltensänderungen auslösen und schließlich zu reifen Fortpflanzungsorganen führen, die für die Fortpflanzung der Art unerlässlich sind. Trotz der evolutionären Bedeutung der Gonadenfunktion gibt es erhebliche Entwicklungsunterschiede zwischen den Arten, deren molekulare Mechanismen weitgehend unerforscht sind. Zur Untersuchung dieser Mechanismen wurden Einzelzell-Omics-Techniken (scRNA- und scATAC-seq) an sich entwickelnden Gonaden eingesetzt, um molekulare Faktoren für interspezifische Unterschiede während der Geschlechtsdifferenzierung zu analysieren. Bekannte Zelltypen wurden in Hoden und Eierstöcken von Schweinen (mit medullären Strängen), Mäusen (ohne medulläre Stränge), Kaninchen (mit verzögerter Meiose der Keimzellen) und Maulwürfen (mit Ovotestes) zu geschlechtsdimorphen Zeitpunkten charakterisiert. Interartspezifische Vergleiche zeigten sowohl konservierte als auch artspezifische Ereignisse auf den Ebenen der dynamischen Genexpression, Co-Expressionsnetzwerke und zellulären Kommunikation. Expressionsdaten wurden mit epigenomischen Daten integriert, um genregulatorische Netzwerke (GRNs) abzuleiten und die regulatorischen Mechanismen zu klären. Analysen zeigten die Einbeziehung artenspezifischer Transkriptionsfaktoren in konservierte GRNs und identifizierten mutmaßliche cis-regulatorische Elemente, die mit artspezifisch exprimierten Genen verknüpft sind. Die Studie legt nahe, dass unterschiedliche Kontrollmechanismen die Meiose in ovariellen Keimzellen über Arten hinweg initiieren und dass der Metabolismus steroidogener Enzyme zu einzigartigen Entwicklungsmerkmalen bei Kaninchen beitragen könnte. / In mammals, the embryonic gonad is the only bipotential organ, differentiating into either testis or ovary during sex determination. Once specified, it produces sex-specific hormones that induce key morphological, physiological, and behavioral changes, leading to mature reproductive organs essential for species perpetuation. Despite the evolutionary importance of gonadal function, significant developmental plasticity exists across species, with underlying molecular mechanisms largely unexplored. To address this, single-cell omics techniques (scRNA- and scATAC-seq) were employed on developing gonads to investigate molecular contributors to interspecies differences during sex differentiation. Known cell types were characterized in testes and ovaries of pigs (exhibiting medullary cords), mice (lacking medullary cords), rabbits (displaying delayed meiosis of germ cells), and moles (forming ovotestes) at sexually dimorphic time points. Interspecies comparative analyses revealed both conserved and species-specific events at the levels of dynamic gene expression, co-expression networks, and cellular communication. Expression data were integrated with epigenomic data to infer gene regulatory networks (GRNs), clarifying regulatory mechanisms governing these events. Analyses revealed species-specific transcription factors in conserved GRNs and identified putative cis-regulatory elements linked with species-specific expressed genes. The study suggests diverse controls initiate meiosis in ovarian germ cells across species and that steroidogenic enzyme metabolism may contribute to unique developmental features in rabbits. Overall, this study advances the understanding of mammalian gonad differentiation and highlights how gene expression program evolution has contributed to mammalian phenotype diversity.
50

Regeneration and calcification in the Spirobranchus lamarcki operculum : development and comparative genetics of a novel appendage

Szabó, Réka January 2015 (has links)
Regeneration, the replacement of lost or damaged body parts, and biomineralisation, the biologically controlled formation of minerals, are important and widespread abilities in the animal kingdom. Both phenomena have a complex evolutionary history; thus their study benefits from investigations in diverse animals. Spirobranchus (formerly Pomatoceros) lamarcki is a small tube-dwelling polychaete worm of the serpulid family. Serpulids have evolved a novel head appendage, the operculum, which functions as a defensive tube plug and regenerates readily when lost. In S. lamarcki, the end of the operculum is reinforced by a calcareous plate; thus, the operculum is a good system in which to study both regeneration and biomineralisation. This thesis explores several aspects of these important processes in the adult operculum. First, a time course of normal regeneration is established. Next, cell proliferation patterns are described, suggesting a combination of proliferation-dependent and proliferation-independent elements in opercular regeneration. The formation of the calcareous opercular plate is examined using both microscopic observations of whole opercular plates and X-ray diffraction analysis of isolated plate mineral, revealing a large shift in mineralogy over the course of regeneration. Histochemical study of alkaline phosphatase enzyme activity indicates the importance of these enzymes in the operculum, although their precise functions are as yet unclear. Finally, a preliminary survey of three opercular transcriptomic datasets is presented, with a broad sampling of gene families with regeneration- or biomineralisation-related roles in other animals. The opercular transcriptome constitutes the first biomineralisation transcriptome from any annelid, and one of the first transcriptomic datasets related to annelid regeneration. Many of the candidate genes examined here display interesting behaviour and suggest targets for further investigation. The work presented here establishes the S. lamarcki operculum as a promising model system in the field of evolutionary developmental biology.

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