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Shah, Niyati Chetankumar. "Hybridization of Bast Natural and Synthetic Fibers in Thermoplastic Composites." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/29892.
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In recent years, the use of natural fiber-reinforced composites in more advanced applications has grown substantially. Applications of high strength require high mechanical properties. An effective method for increasing the field of application and mechanical properties is the hybridization of natural fibers with synthetic fibers. In this research, the effects of recycled carbon fiber hybridizing flax (Linum ussitatissimum L.) and hemp (Cannabis sativa L.) fibers were investigated to identify trends in mechanical properties resulting from varied weight fractions. A new high-performance composite was demonstrated for injection molding applications by hybridizing bast natural fibers and recycled carbon fibers in a polyolefin thermoplastic. After reinforcing recycled carbon fiber with flax and hemp fibers, this study showed a 10-15% increase in tensile strength. After reinforcing recycled carbon fiber with hemp fiber, a 30-35% increase in flexure strength was observed. Impact strength for hemp fiber also increased by 60% compared to recycled carbon fiber.Composites Innovation Centre (Manitoba)
Sunstrand LLC
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Maydan, Jason Stephen. "High-resolution mutation detection in Caenorhabditis elegans mutants and natural isolates using array comparative genomic hybridization." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/6683.
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An essential requirement of genetic research is the ability to identify mutations. Forward genetic screens begin by selecting for a phenotype and proceed to search for the causative mutation. Reverse genetics experiments first identify the mutation and then seek to derive the mutant phenotype, if any. Both approaches depend on efficient means of detecting mutations. This thesis describes the development of methods to facilitate the detection of mutations in the model organism, Caenorhabditis elegans, using array Comparative Genomic Hybridization (aCGH). Exon-centric oligonucleotide microarrays targeting specific chromosomes and the whole genome were designed and used to detect both large multi-gene and small single-gene deletions. Both homozygous and heterozygous deletions were identified using this technique. I showed that even single nucleotide transitions and transversions are detectable when using microarrays with sufficient probe densities, which are achievable with target regions of two Mbp or less. I also used aCGH to detect extensive natural gene content variation between the N2 Bristol strain and twelve wild C. elegans isolates. Most of the DNA copy number alterations in these strains are deletions relative to Bristol. Over 5% of the genes present in the Bristol strain are absent in at least one of the natural isolates that were examined. This represents a significant increase in the number of genes with known null alleles. These deletions were then used to infer relationships among the natural isolates, which proved to be complex. The methods described in this thesis will greatly assist in the identification of mutations in C. elegans and are also applicable to other organisms with sequenced reference genomes.
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羅毓瑩 and Yuk-ying Eugenia Lo. "Phylogenetic relationships and natural hybridization in the mangrove genus rhizophora from the Indo-West Pacific Region." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31227661.
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Conesa, Muñoz Miquel Àngel. "Hybridization patterns in Balearic endemic plants assessed by molecular and morphological markers." Doctoral thesis, Universitat de les Illes Balears, 2010. http://hdl.handle.net/10803/9373.
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La hibridació natural a plantes és un fenòmen àmplement conegut. És una important font de variabilitat que accelera l'evolució de les espècies. Es creu que és l'origen de moltes angiospermes, entre elles endemismes locals. Per altra banda, també pot tenir efectes negatius per la supervivència d'aquests endemismes, diluint els seus trets direfencials. En aquesta tesi s'estudia la possible hibridació natural que afecta a tres endemismes baleàrics (Viola jaubertiana, Lotus fulgurans i Helichrysum crassifolium), des del punt de vista dels marcadors moleculars basats en ADN i de la morfologia. S'avalua el paper de la hibridació natural la variabilitat, l'origen i la conservació d'aquestes espècies endèmiques.Natural hybridization is a widely known process in plants. It is an important source of variation promoting species evolution. It is likely to be the origin of many angiosperms, including local endemisms. Oppositely, it is also regarded as a potential threat for endemisms survivorship, diluting their differentail traits. This thesis deals with putative natural hybridization processes involving three Balearic endemics (Viola jaubertiana, Lotus fulgurans i Helichrysum crassifolium), from the points of view of the DNA molecular markers and the morphology. The role of natural hybridization in the variation, origin, and conservation of the above endemics is evaluated.
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Shimoyama, Ryohei. "Ethological and Ecological Factors Causing Natural Hybridization between Two Pond Frogs, Rana porosa brevipoda and Rana nigromaculata." 京都大学 (Kyoto University), 2000. http://hdl.handle.net/2433/181461.
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Parris, Matthew James. "Analysis of fitness determinants in an anuran hybrid zone (Rana blairi and Rana sphenocephala) : the evolutionary potential of natural hybridization /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9953888.
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Freitas, Hélder Marques de. "Natural hybridization between the Iberian hare (Lepus granatensis) and the brown hare (L. europaeus) in northern Iberian Peninsula." Dissertação, Porto : [s.n.], 2006. http://catalogo.up.pt/F?func=find-b&local_base=FCB01&find_code=SYS&request=000091225.
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Freitas, Hélder Marques de. "Natural hybridization between the Iberian hare (Lepus granatensis) and the brown hare (L. europaeus) in northern Iberian Peninsula." Master's thesis, Porto : [s.n.], 2006. http://hdl.handle.net/10216/64104.
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Zhang, Qiang. "Genetic and Expression Analyses of the 'Nkrp1-Clr' Gene Cluster." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23271.
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Natural killer (NK) cells, lymphocytes of the innate immune system, can recognize a wide array of cells via several receptors families such as Ly49 and NKR-P1. The Nkrp1 gene family encode for C-type lectin-like receptors which can recognize their ligands, Clr, on target cells. Nkrp1 and Clr genes are intertwined in the NK gene complex and are thus inherited together. The Nkrp1-Clr genes in 129S6 and BALB/c mouse strains show significant sequence polymorphism compared to those of C57BL/6 mice while the overall gene organization and gene number are conserved. RT-PCR was utilized to study the expression of individual Nkrp1-Clr genes. In situ hybridization was performed to validate expression results from RT-PCR, as well as to verify the cell types in which Nkrp1-Clr genes are expressed. Surprisingly, our expression studies reveal an interesting pattern of expression of Nkrp1 and Clr genes not only in lymphoid tissues but also in the epithelial cells of the intestine, kidney, eye and lung, the myocytes of the heart and skeletal muscle, and possibly some endothelial cells, indicating novel functions of NK cells in these tissues.
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Pinheiro, Fabio. "Estrutura genética de zonas de hibridação natural entre Epidendrum fulgens e E. puniceoluteum (Orchidaceae)." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41132/tde-11032010-154836/.
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Epidendrum L. é o maior gênero de Orchidaceae da região Neotropical com cerca de 1500 espécies, e os processos de diversificação no grupo são pouco conhecidos. Apesar de existirem muitos relatos sobre hibridação no gênero, não há trabalhos que tenham testado essa hipótese em populações naturais. Epidendrum fulgens Brongn. e E. puniceoluteum F. Pinheiro & F. Barros são espécies que ocorrem ao longo do litoral brasileiro, freqüentemente em simpatria. Para testar a eficiência de suas barreiras reprodutivas, foi examinada a distribuição da variação genética dentro e entre populações simpátricas e alopátricas dessas duas espécies. Nove loci de microsatélites nucleares, e cinco loci de microssatélites de cloroplasto foram utilizados para genotipar 463 indivíduos de oito populações, ao longo de toda distribuição geográfica das espécies. A utilização de métodos de atribuição Bayesianos (programas STRUCTURE e NEWHYBRIDS) detectou a existência de grande quantidade de híbridos nas populações simpátricas. As zonas de hibridação são constituídas por híbridos F1, F2 e retrocruzamentos. A introgressão foi assimétrica, ocorrendo preferencialmente de E. fulgens para E. puniceoluteum. Na população da Ilha do Cardoso, foi detectada a predominância de indivíduos F1 e F2, enquanto nas demais localidades a maior parte dos indivíduos híbridos foi identificada como sendo retrocruzamentos na direção de E. puniceoluteum. Em Florianópolis, não foi possível observar a existência de indivíduos puros de E. puniceoluteum, apenas indivíduos exibindo fortes sinais de introgressão, revelando que o processo de hibridação pode interferir na integridade genética das espécies, levando um dos parentais à extinção. O presente estudo sugere que hibridação e introgressão podem ter papel importante na diversificação em Epidendrum e mostra a importância de investigar zonas de hibridação para melhor entender as barreiras reprodutivas e os processos de especiação nas espécies neotropicais de orquídeas.Among members of the genus Epidendrum , the largest orchid genus of the Neotropics, E. fulgens and E. puniceoluteum occur along the seashore in Brazilian Atlantic Rainforest in sympatric populations. To test the strength of their reproductive barriers, we examined the distribution of genetic variation within and among sympatric and allopatric populations of these two species. Nine specifically developed nuclear microsatellite loci and five chloroplast microsatellite loci were used to genotype 463 individuals from eight populations across species geographical range. All six sympatric populations analyzed present hybrid zones, indicating that hybridization between E. fulgens and E. puniceoluteum is a common phenomenon. Bayesian assignment analysis detected the presence of F1 and F2 individuals, and signs of introgression as well, demonstrating a high potential for interspecific gene flow. The introgression patterns are assimetrical, with differences among populations. Introgression occurs preferentially from E. fulgens to E. puniceoluteum. In Florianópolis population the hybridization seems to lead a species erosion, where pure individuals of E. puniceoluteum where not found. This study suggests that hybridization and introgression could play an important role in the diversification of Epidendrum , and indicated the importance to investigate hybrid zones for better understanding reproductive barriers and speciation processes in Neotropical orchid species.
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Svedin, Nina. "Natural and Sexual Selection in a Natural Hybrid Zone of Ficedula Flycatchers." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7372.
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Buhlman, Lori Marie. "Heterologous Expression of Alpha 6*- Nicotinic Acetylcholine Receptors and the Natural Distribution of Alpha 6 Subunits." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195344.
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Nicotinic acetylcholine receptors (nAChR) are neurotransmitter-gated ion channels that exist as a family of subtypes defined by unique subunit compositions. nAChR containing α6 subunits (α6*-nAChR) have attracted interest because α6 subunits are thought to be localized in brain regions implicated in reward, mood and drug dependence. To provide new information necessary toward a more complete understanding of roles of α6*-nAChR in neuropsychiatric health and disease, three lines of investigation were pursued. A set of stably transfected, human, immortalized cell lines were generated that heterologously express nAChR α6 subunits in combination with other nAChR subunits found in reward brain regions (nAChR subunit combinations α6β2, α6β4, α6β2β3, α6β4β3, α6β2β3α5, α6β4β3α5, α6α4β2β3 and α6α4β4β3). The α6α4β2β3 combination may have a functional response to epibatidine that differs from that of the α4β2 nAChR. A unique binding site was identified in cells transfected with the α6β4β3α5 nAChR subunit combination. Messenger RNA fluorescence in situ hybridization (mRNA FISH) studies established regional and celluar distribution of nAChR α6 subunit mRNA in the mouse brain. The third line of study extended this work to examine potential co-expression of nAChR α6 subunits and glutamic acid decarboxylase (GAD) or tyrosine hydroxylase (TH) as labels of GABAergic and dopaminergic/catecholaminergic neurons respectively, using tandem mRNA FISH and fluorescence immunohistochemistry. nAChR α6 subunit signal in the substantia nigra (SN) and ventral tegmental area (VTA) was congruent with previous studies. Message was also detected in the amydala, dentate gyrus, striatum, zona incerta, and cingulate, entorhinal, perirhinal, piriform, and prelimbic cortices. nAChR α6 mRNA was coexpressed with GAD in the amygdala, dentate gyrus, striatum, SN, VTA and cingulate, entorhinal, prelimbic and prelimbic cortices. TH was exclusively co-localized with nAChR α6 mRNA in the SN and VTA. Findings suggest extended roles for α6*-nAChR in the brain, particularly in the control of GABAergic neuronal activity and/or GABA release. These studies provide new insights into the composition of α6*-nAChR, the localization and cellular origins of nAChR α6 subunit expression. Data collected suggest roles for α6*-nAChR in many brain regions, including those involved in higher order processes involved in drug dependence and reward, and in modulation of inhibitory neurotransmission.
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Campbell, Lesley Geills. "Rapid evolution in a crop-weed complex (Raphanus spp.)." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1166549627.
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Edwards, Taylor Artemus. "A Biogeographic Perspective of Speciation Among Desert Tortoises in the Genus Gopherus." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556486.
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One of the important contributions genetic studies have made to conservation is the ability to resolve taxonomy and define relationships among populations. However, this can be complicated when species exhibit hybridization. Hybridization can be an important part of the evolutionary process and a critical component in a species ability to adapt to a changing environment. Most hybrid zones are observed at ecotones between two distinct habitats and this may be important in defining the role of hybrid zones in the evolutionary process. I examined hybridization among the three distinct lineages of desert tortoises in the genus Gopherus. An important aspect of this study system is the presence of areas of overlap between divergent lineages of desert tortoise which allowed me to test hypotheses about which forces influence these taxonomic boundaries. Specifically, I tested hypotheses about the contribution of physical vs. ecological segregation and the relative importance of isolation and gene flow in the formation of these disparate desert tortoise lineages. I used mtDNA sequence data and 25 microsatellite loci to perform Bayesian clustering, clinal analyses and habitat suitability modeling to infer population structure and influence of landscape features at each contact zone. In both instances, I observed ecological niche partitioning and limited hybridization at ecotones. I then used mtDNA and four nDNA loci to perform a multi-locus phylogenetic analysis to estimate the species tree among desert tortoise lineages and tested for ancestral admixture with RNA-seq data using demographic inference employed in the software package ∂a∂i. My results validate taxonomic distinction among all three lineages without evidence of ancestral introgression. These data suggest that despite the presence of contemporary hybridization and incomplete reproductive isolation, divergence among these lineages is consistent with species-level differentiation. By clarifying the evolutionary processes that influence the distribution of desert tortoise lineages, this study will directly inform efforts to preserve the evolutionary potential of these threatened species. Ultimately, understanding the evolutionary history of desert tortoises not only clarifies the forces that have driven speciation in this group, but it also contributes to our knowledge of the biogeographic history of the southwestern deserts and how diversity is maintained within them.
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Atanasov, Kostadin Evgeniev. "Genetics of natural variation and environmental modulation of immune-related hybrid incompatibilities in Arabidopsis." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/667030.
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Arabidopsis thaliana is a small ruderal weed with prominent north-hemisphere distribution. It has an autogamous style of reproduction, whereas about 3% of the natural population can exhibit outcrosses. Some of these outcrosses produce incompatible hybrids exhibiting temperature-dependent autoimmunity. The hybridization between accessions Ler (from North-Europe) and Kas-2 (from Central Asia) produces an incompatible hybrid. The genetics underlying the incompatibility is caused by the deleterious epistasic interactions between a unique Ler haplotype of RPP1-like genes and the SRF3 Kas-2 receptor-like kinase. The incompatibility exhibits recessive mendelian inheritance pattern and hybrids display strong dwarfism, spontaneous cell death, and sterility at 14 ◦C – 16 ◦C. By using EMS mutagenesis and CRISPR/Cas-9 gene editing on Ler/Kas-2 NIL plants, 15 RPP1-like intragenic loss-of-function mutations were identified. Furthermore, the impact of suppression of incompatibility was investigated in terms of disease resistance against hemibiotrophic or biotrophic pathogens. Moreover, changes on the global transcriptome and metabolite profiling were studied. The contribution of individual RPP1-like genes for the recognition of a local Hpa isolate (Gw) was carried out by cloning ATR1 effector and performing transient expression assays in tobacco plants. The environmental modulation of autoimmunity was studied with a focus on the nitrogen-based mineral nutrition. We found that increasing ammonium was sufficient to suppress the incompatibility and the mechanism behind implies signaling through nitric oxide and the contribution of the systemic acquired response master gene, NPR1. Furthermore, we suggest that ammonium enriched media has an impact on resistance to Pst turning the enhanced resistance on incompatible hybrids down to the parental lines. Finally, we investigated the natural variation to the plant herbicide, guazatine, on a set of 107 accessions. We found an association for the chlorophyllase 1 gene which was selected for functional validation together with the paralog chlorophyllase 2 gene. Chlorophyllase individual mutants and double mutants exhibit increased tolerance to guazatine. No geographical pattern between the tolerant genotype and gene phylogeny was found, whereas high proportion of tolerant accessions was detected in populations for Germany.Arabidopsis thaliana és una planta ruderal petita amb una distribució prominent a l'hemisferi nord. Té una reproducció del tipus autogàmic. No obstant, en la natura, es poden donar creuaments amb una freqüència pel voltant del 3%. Alguns d’aquests creuaments, poden originar híbrids incompatibles amb resposta autoimmunitària que és dependent de la temperatura ambiental. La hibridació entre els accessions Ler (Europa del Nord) i Kas-2 (Àsia Central) produeix un híbrid incompatible. La genètica subjacent a la incompatibilitat és causada per les interaccions epistàsiques deletèries donades per la presència de l’haplotip Ler RPP1-like i el receptor quinasa de Kas-2, SRF3. Aquesta incompatibilitat té un patró d'herència recessiva i els híbrids són nans, mostren mort cel·lular espontània i esterilitat a 14ºC – 16ºC. Mitjançant la mutagènesi per EMS i edició gènica per CRISPR/Cas-9 en Ler / Kas-2 NIL, s’han identificat 15 mutacions intragèniques en l’haplotip RPP1-like. Es va investigar l'impacte de la supressió de la incompatibilitat en termes de resistència a patògens hemibiotròfics o biotròfics. Tanmateix, es va fer un estudi del metaboloma i transcriptoma global per tal de veure l’impacte de la autoimmunitat en el metabolisme. La contribució de gens RPP1-like pel reconeixement del patogen local Hpa (Gw) s’ha investigat mitjançant la clonació d’efector ATR1 i assajos de coinfiltració en sistema heteròleg. També es va estudiar la modulació ambiental sobre l’autoimmunitat en aspectes nutricionals. S’ha trobat que un augment d’amoni era suficient per suprimir la incompatibilitat híbrida i hem suggerit la contribució moduladora per NO i el gen NPR1. Finalment, hem investigat la variació natural per fungicida i herbicida, guazatina, en 107 accessions. Hem trobat una associació pel gen de la clorofilasa 1 que va ser seleccionada per a la seva validació funcional, juntament amb el gen paràleg de la clorofilasa 2. Els mutants individuals de clorofilasa i els dobles mutants, van mostra una major tolerància a la guazatina tan a nivell de contingut de clorofil·les com creixement de l’arrel. No s’ha trobat cap patró geogràfic entre els genotips tolerants i la filogènia dels gens. No obstant, una gran proporció d’accessions tolerants es va detectar en les poblacions d'Alemanya.
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Durland, Evan R. "An evaluation of natural and artificial dietary lipid sources on egg quality and fry production in channel catfish ([female]) x blue catfish ([male]) hybridization." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Theses/DURLAND_EVAN_22.pdf.
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Thesis (M.S.)--Auburn University, 2007.The words "female" and "male" in the title are represented by the corresponding international symbols rather than by words. Abstract. Vita. Includes bibliographic references (ℓ. 38-42)
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Francisco, Patrícia Mara 1984. "Caracterização de populações naturais de Rhizophora spp. (Rhizophoraceae) de manguezais do litoral brasileiro e análise de zona de hibridação utilizando marcadores microssatélites = Characterization of natural populations of Rhizophora spp. (Rhizophoraceae) from mangroves forests along the Brazilian coast and analysis of a hybridization zone using microsatellite markers." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316467.
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Orientador: Anete Pereira de SouzaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-27T05:05:38Z (GMT). No. of bitstreams: 1 Francisco_PatriciaMara_D.pdf: 7911618 bytes, checksum: f90010b3ff20ba6416b899bcfb99b443 (MD5) Previous issue date: 2015
Resumo: Manguezais são ecossistemas com uma variedade incomum de animais e plantas adaptados às condições de alta salinidade, inundações frequentes e solo lodoso e anaeróbico. Ocorrem em locais onde há o encontro de águas de rios com a do mar. Diversos fatores bióticos e abióticos influenciam os padrões de diversidade de espécies de manguezais, como oceanografia, clima, topografia e condições do solo. A diversidade de plantas de mangue é muito reduzida, quando comparada com outros ecossistemas tropicais. O Brasil possui uma das maiores areas de manguezal do mundo e apresenta três gêneros de angiospermas de mangue. Um deles é Rhizophora, composto pelas espécies Rhizophora mangle, Rhizophora racemosa e, um possível híbrido, Rhizophora harrisonii. O objetivo da presente tese foi isolar e caracterizar locos microssatélites para essas espécies e estimar parâmetros populacionais como fluxo gênico, estruturação populacional, diversidade gênica e tamanho efetivo de população, além de estudar outros aspectos da biologia de Rhizophora, como uma possível zona de hibridação na região norte do país, taxa de cruzamento e o sistema reprodutivo. Com este propósito, foram coletados 318 indivíduos de R. mangle de 11 localidades ao longo da costa brasileira, e 33 indivíduos de R. racemosa e 37 indivíduos de R. harrisonii ambas coletadas de duas localidades no litoral brasileiro. Para identificar e caracterizar locos de microssatélites foram desenvolvidas bibliotecas enriquecidas em microssatélites para as três espécies. Utilizando os marcadores desenvolvidos na presente tese, bem como outros que já publicados, observou-se uma diferença significativa entre as populações no padrão de variação genética. A riqueza de alelos, heterozigosidades esperada e observada foram maiores na região norte. Os resultados sugerem que as espécies de Rhizophora não compõe apenas uma população panmítica ao longo do litoral brasileiro, devido à diferenciação existente entre as regiões norte e sul da costa. A análise do sistema reprodutivo de R. mangle de uma população do estado do Pará, encontramos valores que indicariam um sistema de reprodução misto. Em relação à hibridação contínua, não foram encontradas evidências de hibridação introgressiva entre as espécies de Rhizophora. Concluímos que com os resultados obtidos na presente tese foi possível contribuir para o maior conhecimento genético das espécies de Rhizophora spp. do litoral brasileiro
Abstract: Mangrove are ecosystems with an unusual variety of animals and plants adapted to conditions of high salinity and frequent floods and muddy anaerobic soil. Several abiotic factors influence the patterns of mangrove species diversity, such as oceanography, climate, topographic and soil conditions. The number of mangrove plant species is much reduced compared with other tropical ecosystems. Brazil has the second largest mangrove area in the world and has three genera of mangrove angiosperms. One genera is Rhizophora, composed of Rhizophora mangle, Rhizophora racemosa and a possible hybrid, Rhizophora harrisonii. The aim of this thesis was to isolate and characterize microsatellite loci for these species and estimate population parameters such as gene flow, population structure, genetic diversity and effective population size, and study other aspects of Rhizophora biology, as a possible hybrid zone in the north region of the Brazilian coast, crossing rate and the reproductive system. For this purpose, 318 individuals of R. mangle of 11 locations along the Brazilian coast, 33 individuals of R. racemosa and 37 individuals of R. harrisonii from two locations were collected. To identify and characterize the microsatellite loci, enriched microsatellite libraries for the three species were developed. Using the developed markers, and some others already published, we observed a significant difference between the populations in the pattern of genetic variation. Alleles richness, expected and observed heterozygosity were higher in the north. The results suggest that the species of R. mangle is not only composed of a single panmitic population due to differentiation found among the population from locales north and south of the Brazilian Coast. The reproductive system was evaluated studing a population of R. mangle from the state of Pará and we find values that would indicate a mixed mating system. Regarding the ongoing hybridization, we found no evidence of introgressive hybridization among the species leading to a hybrid species. We concluded that with this results it was possible to contribute to further genetic knowledge of Rhizophora spp. from the Brazilian coast
Doutorado
Genetica Vegetal e Melhoramento
Doutora em Genética e Biologia Molecular
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Campbell, Lesley G. "Rapid evolution in a crop-weed complex (Raphanus spp.)." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1166549627.
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Bertin, Aline. "Mudanças genéticas e fenotípicas associadas à criação de Trichogramma galloi Zucchi, 1988 (Hymenoptera: Trichogrammatidae) nos hospedeiros natural e alternativo e os efeitos da hibridização intraespecífica no seu fitness." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11146/tde-19042016-120039/.
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A criação de inimigos naturais em laboratório pode resultar em mudanças genéticas e fenotípicas drásticas devido às alterações ocasionadas principalmente pela deriva genética, endogamia e seleção natural. Estas alterações podem afetar o fitness das populações e reduzir a capacidade adaptativa às condições naturais. Além disto, a criação de inimigos naturais em hospedeiros alternativos pode comprometer a eficiência em campo. Poucos estudos tiveram como objetivo estudar estratégias para minimizar estes efeitos em condições de laboratório. Quantificar a variação genética em características biológicas pode auxiliar a estimar a resposta adaptativa às condições de criação, além de fornecer informações importantes para o melhoramento de agentes de controle biológico. A hibridização intraespecífica, ou seja, o cruzamento entre populações divergentes também pode ser um método relevante e eficaz para aumentar a aptidão biológica de agentes de controle, uma vez que permite a introdução de variação genética externa capaz de recuperar o fitness de populações mantidas em laboratório por muito tempo. Desta forma, este trabalho teve como objetivo estudar as mudanças genéticas e fenotípicas associadas à criação de Trichogramma galloi nos hospedeiros natural e alternativo, bem como investigar a herdabilidade de caracteres fundamentais para o desempenho do parasitoide e identificar os efeitos da hibridização intraespecífica em populações já estabelecidas em laboratório. Os resultados mostraram que a longevidade, a porcentagem de emergência e o número de parasitoides por ovo do hospedeiro apresentaram um aumento entre gerações para a população mantida no hospedeiro natural, indicando haver sinais de adaptação às condições de criação. No entanto, para a população mantida no hospedeiro alternativo foi observada uma redução na fecundidade e porcentagem de emergência quando oferecido o hospedeiro natural para o parasitismo, indicando haver um custo adaptativo associado à utilização de um novo hospedeiro. Foi possível verificar a existência de variação genética significativa na fecundidade. Em média, 46% da variância fenotípica observada foi determinada pela variância genética aditiva, sendo os demais 54% devido à variância ambiental e componentes genéticos dominantes. Nos cruzamentos intraespecíficos não foram observados casos de heterose, no entanto, foi observada a recuperação do fitness em híbridos obtidos a partir da população que apresentava desempenho inferior. Como conclusões deste trabalho, (i) foi possível detectar sinais de adaptação às condições de laboratório na população mantida no hospedeiro natural e uma menor eficiência sobre a praga alvo ao longo das gerações na população mantida no hospedeiro alternativo; (ii) verificou-se variação genética significativa na fecundidade da população estudada e; (iii) a hibridização intraespecífica se mostrou eficaz para amenizar os efeitos da depressão por endogamia em uma das populações de T. galloi estudada.The rearing of natural enemies in laboratory conditions can result in drastic genetic and phenotypic changes due to natural selection, inbreeding, and genetic drift. These changes may affect population fitness and reduce the adaptive potential in natural conditions. Moreover, rearing on alternative hosts may compromise field efficiency. Few studies have focused in strategies to minimize these effects in laboratory conditions. Quantify the genetic variation in biological traits can help estimate the adaptive response to rearing conditions in addition to provide important information for the improvement of biological control agents. Intraspecific hybridization, that is, the crossing between different populations may also be an important and effective method to increase fitness, since it introduces genetic variation able to recover the fitness of populations under laboratory for a long time. Thus, the aims of this work were to: study the genetic and phenotypic changes in laboratory populations of Trichogramma galloi on the natural and alternative host, investigate the heritability of fundamental traits to parasitoid success and identify the effects of intraspecific hybridization in populations already established in the laboratory. The results showed that longevity, emergence rate and the number of parasitoids per host egg increased between generations for the population maintained on the natural host, which corresponds to adaptation signs to the rearing conditions. However, the population reared on the alternative host had a reduction in fecundity and emergence rate when exposed to the natural host, indicating that there is a fitness cost associated with the utilization of a new host. It was possible to verify the existence of significant genetic variance in fecundity. On average, 46% of the observed phenotypic variance was determined by the additive genetic variance, with the remaining 54% due to environmental variance and dominant genetic components. In the intraspecific crosses there were no cases of heterosis, however, the recovery of fitness was observed in hybrids obtained from the population with lower performance. In summary, (i) it was possible to detect signs of adaptation to the rearing conditions in the population maintained on the natural host and a reduction in the efficiency on the target pest over the generations in the population reared on the alternative host; (ii) there was significant genetic variation in fecundity of the population studied and (iii) intraspecific hybridization proved to be effective to mitigate the effects of inbreeding depression in one of the populations of T. galloi studied.
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Medford, Elizabeth. "Using Cleaved Amplified Polymorphic Sequence (CAPS) Genetic Markers to Determine the Extent of Hybridization between Castilleja affinis and Castilleja mollis as a Mechanism for Adapting to Climate Change on Santa Rosa Island." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/scripps_theses/820.
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Hybridization, the process of interbreeding between individuals of different species, is one method by which plants and animals adapt to a changing environment. One example of such adaptation through hybridization may be occurring on the California Channel Islands with two species of Castilleja. While United State Geological Survey (USGS) researchers have been studying the populations of Castilleja affinis and Castilleja mollis to determine if hybridization is occurring on Santa Rosa Island since the early 1990s, up until this point primarily overt phenotypic characteristics have been used to differentiate between the two species. Genetic methods of differentiation were adopted to confirm that hybridization is in fact occurring on the island, possibly in response to climate change. Hybrids may be expanding into areas once occupied by pure C. mollis, because they might carry some of C. affinis’ traits like an ability to survive warmer, drier climates as parts of the island are starting to become warmer and drier. In this study, I have developed a cleaved amplified polymorphic sequences (CAPS) marker based on internal transcribed spacer (ITS) regions to differentiate between the two species and hybrids and have applied these CAPS markers to genotype DNA samples isolated from 132 individuals. This protocol was used to determine the extent of hybridization on Santa Rosa Island in conjunction with ongoing surveys conducted by the USGS. Work focused on genotyping previously collected samples from two main sites on the island, which allowed confirmation that patterns observed based on phenotype in the field are supported by genetic data. In the future, findings will link genetic type with survivorship and growth data, to test whether hybrids perform differently than pure C. mollis. Broadly, this will determine if the two species are in fact hybridizing as a method for adapting to climate change, the most severe threat to Channel Island biodiversity.
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Sá, Fábio Perin de. "Evolução em Cycloramphidae : diversidade e especiação na Mata Atlântica brasileira /." Rio Claro, 2019. http://hdl.handle.net/11449/191273.
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Orientador: Célio Fernando Baptista HaddadResumo: As forças de seleção natural e sexual atuam sobre os indivíduos e podem os levar ao isolamento reprodutivo. O acúmulo de modificações evolutivas pode levar ao surgimento de novas entidades. Espécie é unidade basal em biologia; assim, com sua exuberante biodiversidade, a Mata Atlântica é uma floresta neotropical fundamental para estudos de processos evolutivos em anfíbios anuros. Reunindo os gêneros Cycloramphus, Thoropa e Zachaenus, a família Cycloramphidae agrupa espécies de anuros saxícolas e terrestres, todas endêmicas da Mata Atlântica brasileira. Pelos seus hábitos especializados de vida e reprodução, os cicloramfídeos formam um grupo atrativo para estudos evolutivos. Na presente tese são apresentados quatro capítulos que abordam três escalas distintas da evolução: a diversificação entre espécies, populações e indivíduos. São abordados: (1) a filogenia molecular multilocus de Cycloramphus-Zachaenus, demonstrando que a evolução da terrestrialidade no clado se correlaciona com o dimorfismo sexual em tamanho; (2) a diversificação fenotípica associada a diversificações genéticas em populações de C. boraceiensis e C. dubius, demonstrando que estas duas espécies-irmãs saxícolas apresentam zona de contato e hibridação; (3) o sistema de acasalamento promíscuo e as relações sociais em C. boraceiensis, demonstrando que tamanho das fêmeas e dos machos e parentesco genético influenciam a formação dos casais; e (4) o sistema de acasalamento poligínico com fidelidade na espécie saxíco... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Natural and sexual selection forces act on individuals and may lead to reproductive isolation. The increase in evolutionary modifications may lead to the emergence of new entities. Species is the basal unity in biology; thus, with its exuberant biodiversity, the Atlantic rainforest is a fundamental Neotropical forest for studies of evolutionary processes in anuran amphibians. Comprising the genera Cycloramphus, Thoropa, and Zachaenus, the family Cycloramphidae gathers saxicolous and terrestrial anuran species, all endemic to the Brazilian Atlantic rainforest. Because of their specialized life and reproductive habits, cycloramphids are an attractive group for evolutionary studies. In the present thesis we show four chapters that address three distinct scales of evolution: the diversification among species, populations, and individuals. We goaled: (1) the multilocus molecular phylogeny of Cycloramphus-Zachaenus, demonstrating that the evolution of terrestriality in the clade is correlated with the sexual size dimorphism; (2) the phenotypic diversification associated with the genetic diversifications in populations of C. boraceiensis and C. dubius, demonstrating that these two saxicolous sister species show a contact zone and hybridization; (3) the promiscuous mating system and the social relations in C. boraceiensis, demonstrating that female and male sizes, and mate relatedness influence pair formation; and (4) the polygynic mating system with fidelity in the saxicolous specie... (Complete abstract click electronic access below)
Doutor
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Fehri, Meriem. "Comportements mécanique et hydrique des composites renforcés par des fibres naturelles et/ou conventionnelles." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC215/document.
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Ce travail vise à étudier le comportement mécanique des composites renforcées par des fibres de lin ainsi que le comportement mécanique et hydrique des composites hybrides. Un taux de porosité élevée observée chez ces matériaux conduit à une dégradation des propriétés mécaniques. Des essais de traction et de flambement avec suivi par émission acoustique ont permis d’identifier les mécanismes d’endommagements qui règnent dans ces matériaux et à mettre en évidence leur chronologie d’apparition. Des observations microscopiques des faciès de rupture ont permis de valider ces résultats. Une optimisation des propriétés mécaniques et notamment en termes de réduire le taux de porosité a été testée et ceci en insérant des fibres de carbone dans la structure. Les résultats ont montré que la position des fibres de carbone est primordiale dans l’amélioration des propriété hydrique et mécaniquesThis work aims to study the mechanical behavior of composites reinforced by flax fibers as well as the mechanical and water behavior of hybrid composites. A high porosity rate observed in these materials leads to a degradation of the mechanical properties. Tensile and buckling tests with acoustic emission monitoring have identified the mechanisms of damage that reign in these materials and highlight their chronology appearance. Microscopic observations of fracture facies validated these results. An optimization of the mechanical properties particularly in terms of reducing the porosity rate has been tested by inserting carbon fibers in the structure. The results showed that the position of carbon fibers is essential in the improvement of water and mechanical properties
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Lin, Wuying. "Comparative Reproductive Biology of a Rare Endemic Orchid and its Sympatric Congeners in Southwestern China." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/570.
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Comparative studies on endangered species and their more common congeners can shed light on the mechanism of species rarity, and enable conservationists to formulate effective management strategies. I compared the breeding and pollination systems of the endangered Geodorum eulophioides and its two more common sympatric congeners in subtropical China. Geodorum eulophioides and G. recurvum were self-compatible, both depending on Ceratina cognata for fruit production, while G. densiflorum can autonomously self. Although the floral visitation frequency of G. eulophioides was the highest among the three, its natural fruit set was similar to that of G. recurvum, but both lower than that of G. densiflorum. These results partially explain the difference in species abundance. Coupled with severe habitat loss and degradation, the extremely low pollinator visitation and natural fruit set of G. eulophioides calls for rapid establishment of ex-situ collection, in conjunction with improving in-situ habitat. Natural hybridization tendencies were also studied among species.
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Mori, Gustavo Maruyama 1986. "Caracterização de populações naturais de Avicennia germinans e de A.schaueriana (Acanthaceae) de manguezais do litoral brasileiro e análise de zona de hibridação = filogeografia, genética de populações e de comunidades = Characterization of natural populations of Avicennia germinans and A.schaueriana (Acanthaceae) from mangrove forests along the Brazilian coast and analysis of a hybridization zone : phylogeography, population and community genetics." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316502.
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Orientadores: Anete Pereira de Souza, Maria Imaculada ZucchiTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Abstract: The complete abstract is available with the full electronic document
Doutorado
Genetica Vegetal e Melhoramento
Doutor em Genetica e Biologia Molecular
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Venard, Asongayi. "The Impact of World Bank’s Conditionality-Ownership Hybrid on Forest Management in Cameroon: Policy Hybridity in International Dependence Development." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2349.
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Many developing countries depend on the World Bank for development assistance, which the Bank often provides with policy reform conditions. Resistance to World Bank’s conditionality caused the Bank to posit “ownership” as a country’s real assent to its development policies. The combination of ownership and conditionality invalidates the neocolonial, false-paradigm and dualism theses in explaining the international dependence development model. This study explains this model by investigating how the relationship between conditionality and ownership in the context of this model impacts forest management in Cameroon.
Integrating theoretical and methodological insights mainly from political science, economics, geosciences, and sociology, the study finds that in this model, conditionality and ownership have a hybrid relationship that fosters and hinders effective forest management in Cameroon. This finding positions policy hybridity within this model. It proposes a nouvelle way to understand international development policies’ interactions, and the effects of the interactions on natural resource management.
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Almeida, Susana Cerveira Campar. "Hybridization signals in Fucus diversification." Dissertação, 2016. https://repositorio-aberto.up.pt/handle/10216/91009.
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Almeida, Susana Cerveira Campar. "Hybridization signals in Fucus diversification." Master's thesis, 2016. https://repositorio-aberto.up.pt/handle/10216/91009.
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He, Song. "Marine Fish Hybridization." Diss., 2017. http://hdl.handle.net/10754/623477.
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Natural hybridization is reproduction (without artificial influence) between two or more species/populations which are distinguishable from each other by heritable characters. Natural hybridizations among marine fishes were highly underappreciated due to limited research effort; it seems that this phenomenon occurs more often than is commonly recognized. As hybridization plays an important role in biodiversity processes in the marine environment, detecting hybridization events and investigating hybridization is important to understand and protect biodiversity.
The first chapter sets the framework for this disseration study. The Cohesion Species Concept was selected as the working definition of a species for this study as it can handle marine fish hybridization events. The concept does not require restrictive species boundaries. A general history and background of natural hybridization in marine fishes is reviewed during in chapter as well.
Four marine fish hybridization cases were examed and documented in Chapters 2 to 5. In each case study, at least one diagnostic nuclear marker, screened from among ~14 candidate markers, was found to discriminate the putative hybridizing parent species. To
further investigate genetic evidence to support the hybrid status for each hybrid offspring in each case, haploweb analysis on diagnostic markers (nuclear and/or mitochondrial) and the DAPC/PCA analysis on microsatellite data were used. By combining the genetic evidences, morphological traits, and ecological observations together, the potential reasons that triggered each hybridization events and the potential genetic/ecology effects could be discussed.
In the last chapter, sequences from 82 pairs of hybridizing parents species (for which COI barcoding sequences were available either on GenBank or in our lab) were collected. By comparing the COI fragment p-distance between each hybridizing parent
species, some general questions about marine fish hybridization were discussed: Is there any correlation between genetic similarity and the potential for hybridization in marine fishes? In some particular geographic locations that have the existence of several different hybridization reports, are the species involved in hybridization among those reports all closely related or distantly related? Can any associations between parent species’ similarities and hybrid spots be found?
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Schwarz, Dietmar. "Natural hybridization and speciation in Rhagoletis (Diptera :Tephritidae)." 2004. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-714/index.html.
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Lopes, Sara Cristina Pinto. "Phylogenetics and Hybridization Assessment of Acanthodactylus scutellatus species group in North Africa." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/82300.
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Yen, Chia-yang, and 顏家揚. "A Study of Natural Hybridization in Taiwan Trema spp." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/24602943250870978914.
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碩士國立中山大學
生物科學系研究所
93
The morphological characters, pollen viability, and molecular markers are used in this study to assess the inter-species differentiation in Taiwan Trema( T. orientalis, T. tomentosa, T. cannabina, and the hybrid ). The hybrid was proposed to have been originated from T. tomentosa and T. cannabina natural hybridization with morphological, pollen viability and molecular marker evidences. The four taxa are variable in the following morphological characters: growth form, terminal bud color, leaf size, leaf apex, leaf base, leaf vestiture, leaf texture, leaf nerves, petiole, stipule size, inflorescence sex, male and female inflorescence length, flower number, mature fruit color, perianth vestiture, male flower perianth size, pistillode size, pistillode shape, filament length, and female flower size. The author also found differences in leaf shape, leaf size, leaf base, and leaf vestiture between adult and juvenile individuals of T. orientalis are ontogenetical variations. The hybrid is morphological intermediate between T. tomentosa and T. cannabina, possessing species-specific morphological characters of either species. Leaf trichome morphology was observed under scanning electronic microscope, and a unicellular trichome type with bulbous base, smooth surface, and creeping looking, is specific to T. orientalis leaf abaxial surface. In pollen viability tests, the hybrid had the lowest average pollen stainbility among tour taxa, but varied widely from 48.5 % to 81.6 %. In additivity test of molecular markers, for all 8 species-specific molecular markers of T. tomentosa, 6 were detected in hybrid; for all 14 species-specific molecular markers of T. cannabina, 11 were detected in hybrid; and none of 14 species-specific molecular markers of T. orientalis were detected in hybrid. Additionally, there were some recessive homozygote alleles detected in hybrid molecular marker, and even missing in T. tomentosa molecular markers. According to this evidence, there was a possible introgression between the hybrid and parental species-T. cannabina. In similarity dendrogram derived from molecular markers, all samples were clustered into four taxa-corresponded groups, the hybrid was placed between T. tomentosa and T. cannabina, and closely related to T. cannabina.
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Costa, Diana Isabel Barbosa da. "Insights into the extent of hybridization between flat periwinkles in the Iberian Peninsula." Dissertação, 2016. https://repositorio-aberto.up.pt/handle/10216/91004.
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Lopes, Sara Cristina Pinto. "Phylogenetics and Hybridization Assessment of Acanthodactylus scutellatus species group in North Africa." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/82300.
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Costa, Diana Isabel Barbosa da. "Insights into the extent of hybridization between flat periwinkles in the Iberian Peninsula." Master's thesis, 2016. https://repositorio-aberto.up.pt/handle/10216/91004.
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Ribeiro, Mariana Jorge Meneses Correia. "A landscape genetics perspective on the spatial dynamics of hybridization between two species of wall lizards." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/81330.
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Fontenot, Brian E. "Natural hybridization and speciation in toads of the Anaxyrus americanus group." 2009. http://hdl.handle.net/10106/1779.
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Ramos, Luana Isabel Ferreira da Silva Costa. "Assessing hybridization between wildcat and domestic cat : the particular case of Iberian Peninsula and some insights into North Africa." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/77447.
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Ribeiro, Mariana Jorge Meneses Correia. "A landscape genetics perspective on the spatial dynamics of hybridization between two species of wall lizards." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/81330.
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Freitas, Maria Carolina Pacheco de. "Assessing the spatial extent of wolf-dog hybridization in real-time and at population level using non-invasive DNA sampling." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/87537.
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Ramos, Luana Isabel Ferreira da Silva Costa. "Assessing hybridization between wildcat and domestic cat : the particular case of Iberian Peninsula and some insights into North Africa." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/77447.
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Black, Robert Shewan. "Structure and optical properties of natural low dimensional, semiconducting, organic inorganic hybrids." Thesis, 2013. http://hdl.handle.net/10539/12398.
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The aim of investigating the 2D PbX6 inorganic organic hybrids was to study octahedral distortions, short interlayer spacing’s, and the effect of functionalized aliphatic’s terminal halogen on idealizing or destabilizing the octahedral arrangements and their effect on the band gap of the single layer 2D hybrid systems. It was found that the PbX6 metal centred distortions do display some impact on the band gap, the greater the distortion experienced in the Ieq-Pb-Ieq cis bond angles, the wider the band gap, as we suspect a decrease in I 5p antibonding character which lowers the top of the valence band. The terminal halogen interaction specifically in (BrC2)PbI4, clearly displayed some Br 4p/s character at the bottom of the conduction band, which may further explain the reduction of the band gap of this compound. This in conjunction with the shorter interlayer spacing serve to stabilize more idealized bridging angles, as seen in both the lead iodide and bromide analogues. In the short interlayer spacing compounds large idealizations of the Pb-X-Pb bridging angles are observed however display a large metal centred octahedral distortions in order accommodate the spatial occupation of the lone pair on lead.
It was generally observed that the lead bromide hybrids appear to have a greater sensitivity to exciton lattice interactions, which give rise to red shifted emissions and absorptions with decreasing temperature. Structurally this behaviour is counterintuitive; because the structures increase in inorganic distortions with decreasing temperature and therefore a blue shift in the exciton absorption is expected. It should be noted that compounds displaying this phenomenon most, (C4, C6, C7)PbBr4 do display a large amount of structural disorder in their lower temperature phases.
In the 1D systems investigated further structure to property correlations were made. Optically it was found that unlike the corner-shared perovskite type 1D wires of [NH2C(I)=NH2]3PbI5 and [CH3SC(=NH2)NH2]3PbI5 the first exciton absorption of the octahedral face sharing wires of (A)PbI3 appear to be largely insensitive to the inorganic structural distortions experienced as a result of the low temperature phase transitions. In one instance however a low temperature phase transition did result in a polaron emission which was directly related to a discontinuity in the inorganic wires. More generally experimental links between the STE luminescence emissions and the inter-wire spacing, organic dielectric constant, and the density of the crystal, were shown to influence the STE lattice interactions to a greater degree. This effect is increased through a decrease in crystal density and organic dielectric constant, with an associated increase in the inter-wire spacing. Therefore as the exciton lattice interactions increase, a red shift in the STE emissions is observed.
In another series of systems strong 1- and interactions were present in particularly two 1D charge transfer compounds. It was noted that the inorganic wires promote interactions between the organic templates as has also been established in literature. Structurally it was also observed that the CT transitions of these compounds begin to largely coincide with the STE emission arising from the inorganic wire. Even though the CT compounds structurally have strong interactions the current experiments do not ascertain to what degree this interaction assists in electron transport. It was also established that as intermolecular interactions are absent in previously published MV and Et compounds with the dominant CT interaction was the I…N interaction which functions over a large range (4.9A). This long distance is substantiated from the strong covalent character of the I…N interaction observed in IR experiments completed on (MV)Pb2I6. It was also observed in our compounds that the position of the LUMO of the organic cation relative to the valence band of the inorganic wires appears to be largely dependent on the N…I distance and largely independent of the electron accepting templates HOMO-LUMO gap.
The increased wire thickness observed in these compounds does appear to display a pronounced effect on the PL emissions as seen in three chain wide wires produced. The thicker chains begin to allow higher energy emission’s to occur i.e. the desired first exciton emission begins to become favored due to the relaxing of the wires spatial confinement on the electron-hole’s orbit. Further investigations are needed into even thicker chain wires, in order to ascertain the ideal size of the wire to obtain the desired high energy first exciton emission. To date the wire thickness that does give rise to the first exciton emission appears to still need at least six coordinated PbI6 octahedral units.
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Freitas, Maria Carolina Pacheco de. "Assessing the spatial extent of wolf-dog hybridization in real-time and at population level using non-invasive DNA sampling." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/87537.
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Marques, Isabel. "Evolutionary outcomes of natural hybridization in Narcissus (Amaryllidaceae):the case of N. xperezlarae s.l." Doctoral thesis, 2010. http://hdl.handle.net/10451/1836.
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Tese de doutoramento, Biologia (Biologia Evolutiva), 2010, Universidade de Lisboa, Faculdade de CiênciasDisponível no documento
Este trabalho é resultado da cooperação efectiva entre o Jardim Botânico da Universidade de Lisboa (MNHN) e o Real Jardín Botánico, Madrid (CSIC)
Fundação para a Ciência e a Tecnología através da bolsa de doutoramento SFRH/BD/19053/2004. Outros projectos contribuiram para determinadas experiências: CSIC-Comunidad de Madrid, Spain, (CCG07-CSIC/AMB-1978), Ministerio de Ciencia e Tecnología de Espanha (CGL2007-66516) e Acção Integrada Luso-Espanhola (E-13/06 and HP2005-0140)
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Yang, Chieh-An, and 楊絜安. "Comparison of the histopathological changes and tissue distributions of CPV-2 variants natural infection by In Situ hybridization." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/jnm55w.
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碩士國立屏東科技大學
獸醫學系所
106
Canine parvovirus type 2 (CPV-2) is one of the most important alimentary and immune system diseases in dogs. It induces severe hemorrhagic enteritis and necrosis of peripheral lymphoid tissue of gastrointestinal tract, and was also been reported showing myocarditis in puppies. CPV-2 was first reported in 1978, and had become a world-wide infectious disease throughout these years, the long period of interaction with the different hosts leads to the variation of the virus. In the 1980s, new antigenic type CPV-2a and 2b had been discovered, and CPV-2c was been reported in the year 2000. The prototype CPV-2 is now totally been replaced by these variants. Previous research shows that CPV-2 variant has no significant difference in tissue distribution, but may have some differences in pathogenicity. While during CPV-2 diagnosis, In Situ hybridization has been reported showing high sensitivity, and could directly observe viral infection circumstances within the cells. However, no previous research compared the differences of micro lesions and ISH signal distribution caused by all three types of CPV-2 variants. Thus, the present study collects positive CPV-2 samples from Taiwan, using genetic sequencing technique to classify CPV-2 variants into three groups (2a, 2b and 2c). Synthesis the CPV-2 ISH probe, using the plastid DNA which contain the CPV-2 partial gene with in the competent cell to test the ISH probe, after establish the protocol, ISH staining technique is then used to compare the differences of histopathological changes and the tissue distributions between CPV-2 variants. Twenty four CPV-2 necropsy cases had been collected (8 CPV-2a, 2 CPV-2b, 14CPV-2c) , all of these cases are shows the variant severity of CPV-2 infectious lesion, and the histopathology also shows necrosis of crypts epithelium and crypts dilation. The ISH positive signal are mainly found in the necrotic crypt epithelium, and lymphocytes and macrophages in lymphoid tissues of gastrointestinal tract. But no significant differences were found in histopathology and tissue distribution between the variants, shows that there are no obvious differences of intestinal damage and virus distribution between three variants. The result suggested that there may be no obvious difference of pathogenicity and mechanisms between three variants.
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(11208897), Shubham Pradeep Agnihotri. "EFFICIENCY IMPROVEMENT ANALYSIS FOR COMMERCIAL VEHICLES BY (I) POWERTRAIN HYBRIDIZATION AND (II) CYLINDER DEACTIVATION FOR NATURAL GAS ENGINES." Thesis, 2021.
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The commercial vehicle sector is an important enabler of the economy and is heavily dependent on fossil fuels. In the fight against climate change, reduction of emissions by improving fuel economy is a key step for the commercial vehicle sector. Improving fuel economy deals with reducing energy losses from fuel to the wheels. This study aims to analyze efficiency improvements for two systems that are important in reducing CO2 emissions - hybrid powertrains and natural gas engines. At first, a prototype series hybrid powertrain was analyzed based on on-highway data collected from its powertrain components. Work done per mile by the electrical components of the powertrain showed inefficient battery operation. The net energy delivery of the battery was close to zero at the end of the runs. This indicated battery was majorly used as an energy storage device. Roughly 15% of losses were observed in the power electronics to supply power from battery and generator to the motor. Ability of the hybrid system to capture regenerative energy and utilize it to propel the vehicle is a primary cause for fuel savings. The ability of this system to capture the regenerative energy was studied by modeling the system. The vehicle model demonstrated that the system was capturing most of the theoretically available regenerative energy. The thesis also demonstrates the possibility of reduction of vehicular level losses for the prototype truck. Drag and rolling resistance coefficients were estimated based on two coast down tests conducted. The ratio of captured regenerative to the drive energy energy for estimated drag and rolling resistant coefficients showed that the current system utilizes 4%-9% of its drive energy from the captured regenerative energy. Whereas a low mileage Peterbilt 579 truck could increase the energy capture ratio to 8%-18% for the same drive profile and route. Decrease in the truck’s aerodynamic drag and rolling resistance can potentially improve the fuel benefits.
The second study aimed to reduce the engine level pumping losses for a natural gas spark ignition engine by cylinder deactivation (CDA). Spark ignited stoichiometric engines with an intake throttle valve encounter pumping/throttling losses at low speed, low loads due to the restriction of intake air by the throttle body. A simulation study for CDA on a six cylinder natural gas engine model was performed in GT- Power. The simulations were ran for steady state operating points with a torque range 25-560 ftlbs and 1600 rpm. Two , three and four cylinders were deactivated in the simulation study. CDA showed significant fuel benefits with increase in brake thermal efficiency and reduction in brake specific fuel consumption depending on the number of deactivated cylinders. The fuel benefits tend to decrease with increase in torque. Engine cycle efficiencies were analyzed to investigate the efficiency improvements. The open cycle efficiency is the main contributor to the overall increase in the brake thermal efficiency. The work done by the engine to overcome the gas exchange during the intake and exhaust stroke is referred to the pumping losses. The reduction in pumping losses cause an improvement in the open cycle efficiency. By deactivating cylinders, the engine meets its low torque requirements by increase in the intake manifold pressure. Increased intake manifold pressure also resulted in reduction of the pumping loop indicating reduced pumping losses. A major limitation of the CDA strategy was ability to meet EGR fraction requirements. The increase in intake manifold pressure also caused a reduction in the delta pressure across the EGR valve. At higher torques with high EGR requirements CDA strategy was unable to meet the required EGR fraction targets. This limited the benefits of CDA to a specific torque range based on the number of deactivated cylinders. Some variable valve actuation strategies were suggested to overcome this challenge and extend the benefits of CDA for a greater torque range.
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Xu, Shiqin. "Genetic diversity and hybridization in natural stands of shortleaf pine (Pinus echinata mill.) and loblolly pine (Pinus taeda L.)." 2006. http://digital.library.okstate.edu/etd/umi-okstate-2071.pdf.
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Ballard, Harvey E. "Phylogenetic relationships and infrageneric groups in Viola (Violaceae) based on morphology, chromosome numbers, natural hybridization and internal transcribed spacer (ITS) sequences." 1996. http://catalog.hathitrust.org/api/volumes/oclc/36205086.html.
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Parreira, Ricardo Almiro. "Relatório de Estágio e Monografia intitulada "Novos agentes antimaláricos com estrutura esteróide"." Master's thesis, 2019. http://hdl.handle.net/10316/88395.
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Relatório de Estágio do Mestrado Integrado em Ciências Farmacêuticas apresentado à Faculdade de FarmáciaA malária ou paludismo é uma doença causada pelo parasita do género Plasmodium, que se transmite pelas picadas de mosquitos fêmeas Anopheles também designados de vetores da malária. Apesar da grande evolução ocorrida na ciência nos últimos anos, a malária continua a causar milhões de casos e milhares de mortes todos os anos, transformando-se num grande problema de saúde, principalmente nas zonas tropicais e subtropicais. A maioria dos casos de malária deve-se principalmente ao Plasmodium falciparum, o parasita mais virulento para o ser humano dentro do género Plasmodium. Embora exista um conjunto de fármacos e diversas combinações dos mesmos disponíveis para combater o paludismo, o P. falciparum tem vindo a desenvolver resistência à maioria deles nos últimos anos. Desta forma a descoberta de novos agentes antimaláricos é cada vez mais uma necessidade para combater esta ameaça futura. Os esteróides têm ganho um grande interesse no âmbito da medicina, devido às suas propriedades farmacológicas diversificadas e têm sido identificadas e sintetizadas novas moléculas com uma ação antimalárica possuindo esta estrutura química. Este trabalho tem como objetivo realizar uma análise sobre agentes com uma estrutura esteróide na qual recentemente foi identificada uma ação contra as diversas estirpes do Plasmodium falciparum. Os agentes abordados nesta apresentação são: - alcalóides da Horrhena pubescens, - esteróis da Xestospongia sp, - esteróides 17-arilmetilamino, - derivados do ácido fusídico e híbridos de artesunato.
Malaria or paludism is a disease caused by the parasite from the Plasmodium genre, the transmission mechanism revolves around the female mosquito Anopheles bite and due to this fact, this genre of mosquito received the designation of malaria vectors. Despite the staggering scientific progress made in recent years, malaria still infects millions of individuals and is responsible for the deaths of thousands due to infection related complications, mainly in tropical and subtropical regions. Most cases of malaria are due to infections by Plasmodium falciparum, the most virulent strain, for humans, of the Plasmodium genre. Despite the existence of a wide range of drugs and combinations to treat paludism, P. falciparum has been gaining resistance to the majority of these in recent years. As such, the effort to research new antimalarial agents must be viewed as priority in order to keep an effective response to this threat in the future. The interest in steroids on the medical field has surged over the last decades, mainly due to the diversified range of pharmacological properties, in addition, new molecules have been identified and synthetized with a steroidal structure to act as antimalarial agent. The present paper has, as its main goal to conduct a straightforward analysis of agents with a steroid structure which have been identified as effective against the diversified range of Plasmodium falciparum strains. The agents covered in this presentation are: - alkaloids found in Horrhena pubescens, - sterols from Xestospongia,- 17-arylmethylamino steroids - fusidic acid derivatives and artesunate hybrids.
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Johnson, James Bradley. "The Architecture of Phenotypes in a Naturally Hybridizing Complex of Xiphophorus Fishes." Thesis, 2013. http://hdl.handle.net/1969.1/149426.
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The origin and maintenance of phenotypic variation has generated considerable interest among students of functional morphology, sexual selection and behavioral ecology. In particular, hybridization has been suggested as a phenomenon which may generate novel phenotypic variation. In this dissertation I focus on the Xiphophorus birchmanni - X. malinche hybrid system to assess the role of hybridization in altering behavioral, morphological, sexual and non-sexual traits. I determine the relationship between the sword sexual ornament and body condition to support previous work which suggests that the sword is an inexpensive means to increase apparent size. My findings support the prediction that, while body size is condition-dependent, the sword is not. I show a trend toward hybrid populations displaying increased phenotypic variance and reduced phenotypic integration in sexual ornaments and body size. These findings provide evidence for a potential answer to a central question in the study of sexual selection, that of reduced genetic and phenotypic variance in sexual ornaments as the result of persistent direction selection generated by female choice. I take advantage of reduced phenotypic integration in hybrids allowing the evaluation of locomotor performance across a broad range of multivariate trait values. Sexual ornaments did not impair swimming performance per se. Rather, the sword negatively affected performance only when paired with a sub-optimal body shape. I evaluated how natural hybridization changes the relationship between boldness and anti-predator response. In poeciliid fishes, bold individuals have increased survival in the presence of predators. This non-intuitive observation may result from bold individuals being more likely to engage in anti-predator behaviors. Counter to my prediction, bold individuals were less likely to perform a fast-start response to a predator threat. This correlation was consistent among populations and species but was only significant in hybrids. My findings suggest that hybridization could influence correlations between behavioral traits in a manner similar to that documented for morphological traits.
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KOŠNAR, Jan. "Biosystematic studies in the family Cyperaceae." Doctoral thesis, 2013. http://www.nusl.cz/ntk/nusl-166158.
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The thesis was focused on the microevolutionary mechanisms that contribute to morphological diversity in selected members of the sedge family (Cyperaceae). Natural hybridization, evidenced from both morphological characters and molecular markers, was revealed to be a potentially important source of diversification in the tropical spikerushes of Eleocharis subgenus Limnochloa. High levels of phenotypic plasticity of clonal growth but rare genetic (ecotypic) differentiation among contrasting morphotypes were found in the polymorphic species Carex nigra, which implied that taxonomic splitting of the species was unreasonable.