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Fourie, Gerda. "Evolutionary biology of Fusarium oxysporum f.sp. cubense." Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/29586.
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Fusarium oxysporum Schlecht. is a cosmopolitan species complex that consists of both pathogenic and non-pathogenic members. The pathogenic members are subdivided into formae speciales, based on virulence to specific host species. More than 150 formae speciales have been described, of which F. oxysporum f.sp. cubense (E.F.Smith) Snyder and Hansen (Foc), causal agent of Fusarium wilt of banana, is regarded as one of the economically most important and destructive. According to phenotypic and genotypic markers, Foc has been classified into three races and 24 vegetative compatibility groups, and can be divided into a number of clonal lineages that roughly correspond with VCG groupings. In this thesis, we investigated the evolutionary relationships among VCGs using multi-gene sequencing and MAT genotyping. A PCR-RFLP fingerprint discriminating the Foc lineages and a PCR primer that identified Foc ‘subtropical’ race 4 isolates, was developed. Nine microsatellite markers (SSRs) were applied to a global population of Foc in order to investigate diversity not always detectable using sequencing data. Phylogenetic analysis of isolates representing Foc, various other formae speciales of F. oxysporum and non-pathogenic F. oxysporum of the genes encoding the translation elongation factor-1á (TEF), the mitochondrial small subunit (MtSSU), ribosomal RNA (rRNA), the repeated region encoded on the mitochondrion (MtR) and the intergenic spacer (IGS) gene regions separated these isolates into four clades, two of which included Foc. Within these two clades, Foc separated into six lineages that broadly corresponded to VCGs, while the non-pathogenic isolates of F. oxysporum grouped together in only one of the two clades, with an unknown Foc VCG isolate. The mating type of all isolates was determined and crosses were attempted between isolates harbouring MAT-1 and MAT-2 genes, without success. Cultural, morphological and pathogenic variation among isolates of Foc was unable to identify lineages as species. The separation of Foc isolates into two clades suggested that the banana pathogen evolved during two unrelated events. Factors such as horizontal gene transfer, however, might also have played a part in the pathogen’s evolution, as was evident from the divergent placement of some VCGs and lineages within the phylogenetic trees constructed. The inclusion of other formae speciales of F. oxysporum and non-pathogenic F. oxysporum isolates illustrated the great diversity that exists within the F. oxysporum complex. The inclusion of the Foc isolate of an unknown VCG suggests that the genetic diversity of Foc might be far greater than what is known and what was revealed in this study. The opposite mating types found in the respective lineages indicate a sexual origin for the Fusarium wilt fungus that could account for its polyphyletic nature. Within South Africa, Foc ‘subtropical’ race 4 is regarded the most important constrain to banana production. Conventional control practices for Fusarium wilt of banana are ineffective, and disease management relies heavily on the use of clean planting material and the early detection and isolation of the pathogen, in order to restrict spread to unaffected areas. Identification of Foc typically involves vegetative compatibility assays and pathogenicity testing using a set of differential host cultivars. The development of a PCR-based method for the rapid and accurate identification of Foc ‘subtropical’ race 4 will, therefore, be of great importance. The lack of morphological variation between lineages of Foc, and between pathogenic and non-pathogenic members, as well as the unreliability in race identification in Foc, makes the use of molecular tools a viable alternative. Following DNA isolation, PCR and sequencing of the MtR, the DNA sequence data revealed an 8-bp insertion that was subsequently targeted for the design of a Foc ‘subtropical’ race 4-specific primer. Isolates were positively identified as Foc ‘subtropical’ race 4 with the amplification of an 800-pb fragment. The development of the Foc ‘subtropical’ race 4 primer will aid in rapid and accurate detection of the Fusarium wilt pathogen of banana. The population structure defined according to SSR data of a global population of 239 Foc isolates resembled the structure defined according to multi-gene phylogeny, with some exceptions. Measures of gene and genotypic diversity unequivocally supported the opinion that Asia is the centre of origin of Foc. The presence of unique genotypes in all geographically-defined Foc populations could potentially indicate their evolution outside the centre of origin, although this is highly unlikely. The absence of certain genotypes from the Asian population was either due to insufficient and selective sampling, or it demonstrated the effects of clonal selection in combination with adaptation to the forces of geographic isolation and environmental changes over time. The worldwide collection of Foc mostly consisted of six over represented genotypes, thereby providing support for a clonal genetic structure. It was, however, not possible to reject the hypothesis of a recombining population for the populations representing isolates of Lineage V. The implication of recombination within some Foc lineages may be due to unobserved sexual reproduction in nature or the historical association with a sexual ancestor. When one considers diversity within and among genotypes, a specific genotype was mostly associated with only one or two Foc VCGs, therefore indicating that vegetative compatibility determination, in combination with phylogenetic analyses, is a powerful tool for characterizing isolates causing Fusarium wilt of banana. Results from this study, in combination with the multi-gene phylogeny, clearly indicated the presence of unrelated lineages that most probably represent cryptic species. Copyright 2008, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Fourie, G 2008, Evolutionary biology of Fusarium oxysporum f.s.p. cubense, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-11192008-094622/> E1216/gmDissertation (MSc)--University of Pretoria, 2008.
Microbiology and Plant Pathology
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Groenewald, Susan. "Biology, pathogenicity and diversity of Fusarium oxysporum f.sp. cubense." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-02232007-175712.
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Cortes, Blanca R. "Parasexuality and heterokaryosis in fusarium oxysporum forma specialis cubense." FIU Digital Commons, 1996. http://digitalcommons.fiu.edu/etd/2717.
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Intra and Inter Vegetative Compatibility Group (VCG) heterokaryon formation was observed in Fusariurn oxysporum f.sp. cubense (Foc). Using the double-pick method to force heterokaryon formation via hyphal anastomosis, 104 pairwise combinations were done between 100 auxotrophic mutants of Foe representing races 1, 2 and 4 in five VCGs. Inter formae speciales heterokaryon formation was also observed on pairings between benomyl resistant Wild Type Testers (WTT) and wild type isolates in 15 VCGs and four different formae speciales. Microconidia analysis of heterokaryons identified both parental phenotypes as well as diploid phenotypes. Colonies with altered and hybrid genotypes were recovered from analysis of sectors from prototrophic hybrids as well as sectors with parental phenotype providing evidence of all stages of the parasexual cycle in this asexual, soilborne, phytopathogen.
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Heck, Daniel Winter [UNESP]. "Supressividade a Fusarium oxysporum f. sp. cubense por produtos orgânicos." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/132112.
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000851960.pdf: 1986629 bytes, checksum: fd2eda9f5c5da698a200b6313ee03909 (MD5)A indução de supressividade a Fusarium oxysporum f. sp. cubense (Foc) em bananeira por meio de produtos orgânicos foi avaliada pela incorporação ao solo, artificialmente infestado com o patógeno, de biocarvão de serragem de Eucalyptus (BC), casca de camarão (CC), composto de lodo de esgoto (LE), concha de marisco (CM), bio-óleo de casca de arroz (BA) e de serragem de Eucalyptus (BE), emulsão (EP) e hidrolisado de peixe (HP). Características químicas do solo; área abaixo da curva de progresso do índice da doença (AACPID); severidade final; descoloração interna do rizoma; respiração microbiana por meio da liberação de CO2; comunidade de F. oxysporum, fungos e bactérias totais; a inibição do crescimento micelial e da germinação de microconídios pelos extratos aquosos e pela liberação de compostos voláteis tóxicos foram os parâmetros avaliados. A CC e o LE reduziram a severidade externa (50 e 37%, respectivamente) e a descoloração interna do rizoma (56 e 36%, respectivamente). As CC e CM reduziram o desenvolvimento das plantas nas fases iniciais de cultivo, mostrando sintomas de fitotoxicidade. A elevação do pH, condutividade elétrica (CE), K, Mg, S, Na, Fe, Zn, CO2 e comunidade de bactérias foram as características que apresentaram maior influência na redução da severidade, enquanto que o aumento no pH, CE, CO2, P, Ca, S, Na e B também contribuíram para reduzir a população de F. oxysporum no solo. O BA, o BE e o HP reduziram em 94, 84 e 40% a AACPID, respectivamente. Os teores de Zn, a inibição do crescimento micelial e inibição da germinação dos microconídios pela ação de compostos voláteis e de extratos aquosos foram os mecanismos que mais explicaram o controle ...
The induction of suppressiveness to Fusarium wilt in banana by the incorporation of Eucalyptus sawdust biochar (BC), shrimp shells (CC), composted sewage sludge (LE), clamshell (CM), bio-oil of rice husk (BA) and bio-oil of Eucalyptus sawdust (BE), fish emulsion (EP) and fish hydrolyzate (HP) to soil was evaluated. Soil chemical characteristics; the area under the curve of progress of the disease index (AUPCDI), final severity and internal discoloration of the rhizome; microbial respiration through the release of CO2; the populations of F. oxysporum, fungi and total bacteria; and inhibition of mycelial growth and microconidia germination through the compounds volatile toxic and aqueous extracts were the parameters evaluated. The CC and LE reduced final severity (50 and 37%, respectively) and the internal discoloration of the rhizome (56 and 36%, respectively). The incorporation of CC and CM reduced plant development in the early stages of cultivation, showing symptoms of phytotoxicity. The increase in pH, electric ...
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Heck, Daniel Winter 1990. "Supressividade a Fusarium oxysporum f. sp. cubense por produtos orgânicos /." Botucatu, 2015. http://hdl.handle.net/11449/132112.
Full textAbstract:
Orientador: Wagner BettiolCoorientador: Carlos Gilberto Raetano
Banca: Antonio Carlos Maringoni
Banca: Miguel Angel Dita Rodriguez
Resumo: A indução de supressividade a Fusarium oxysporum f. sp. cubense (Foc) em bananeira por meio de produtos orgânicos foi avaliada pela incorporação ao solo, artificialmente infestado com o patógeno, de biocarvão de serragem de Eucalyptus (BC), casca de camarão (CC), composto de lodo de esgoto (LE), concha de marisco (CM), bio-óleo de casca de arroz (BA) e de serragem de Eucalyptus (BE), emulsão (EP) e hidrolisado de peixe (HP). Características químicas do solo; área abaixo da curva de progresso do índice da doença (AACPID); severidade final; descoloração interna do rizoma; respiração microbiana por meio da liberação de CO2; comunidade de F. oxysporum, fungos e bactérias totais; a inibição do crescimento micelial e da germinação de microconídios pelos extratos aquosos e pela liberação de compostos voláteis tóxicos foram os parâmetros avaliados. A CC e o LE reduziram a severidade externa (50 e 37%, respectivamente) e a descoloração interna do rizoma (56 e 36%, respectivamente). As CC e CM reduziram o desenvolvimento das plantas nas fases iniciais de cultivo, mostrando sintomas de fitotoxicidade. A elevação do pH, condutividade elétrica (CE), K, Mg, S, Na, Fe, Zn, CO2 e comunidade de bactérias foram as características que apresentaram maior influência na redução da severidade, enquanto que o aumento no pH, CE, CO2, P, Ca, S, Na e B também contribuíram para reduzir a população de F. oxysporum no solo. O BA, o BE e o HP reduziram em 94, 84 e 40% a AACPID, respectivamente. Os teores de Zn, a inibição do crescimento micelial e inibição da germinação dos microconídios pela ação de compostos voláteis e de extratos aquosos foram os mecanismos que mais explicaram o controle ...
Abstract: The induction of suppressiveness to Fusarium wilt in banana by the incorporation of Eucalyptus sawdust biochar (BC), shrimp shells (CC), composted sewage sludge (LE), clamshell (CM), bio-oil of rice husk (BA) and bio-oil of Eucalyptus sawdust (BE), fish emulsion (EP) and fish hydrolyzate (HP) to soil was evaluated. Soil chemical characteristics; the area under the curve of progress of the disease index (AUPCDI), final severity and internal discoloration of the rhizome; microbial respiration through the release of CO2; the populations of F. oxysporum, fungi and total bacteria; and inhibition of mycelial growth and microconidia germination through the compounds volatile toxic and aqueous extracts were the parameters evaluated. The CC and LE reduced final severity (50 and 37%, respectively) and the internal discoloration of the rhizome (56 and 36%, respectively). The incorporation of CC and CM reduced plant development in the early stages of cultivation, showing symptoms of phytotoxicity. The increase in pH, electric ...
Mestre
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King'u, Jackson N. "Ecology, distribution and population structure of Fusarium oxysporum f.sp. cubense in Kenya." Thesis, University of Kent, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263733.
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D'Alessio, Naomi. "Mitochondrial inheritance during a parasexual cycle in fusarium oxysporum forma specialis cubense." FIU Digital Commons, 1997. http://digitalcommons.fiu.edu/etd/2705.
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Fusarium oxysporum is a diverse, asexual fungal species composed of both saprophytic and pathogenic members. The destructive phytopathogens are classified into formae speciales based on the host species and into vegetative compatibility groups (VCGs) based on the ability of two individuals to form heterokaryons. Parasexuality, a nonsexual mode of genetic exchange unique to some fungi has been demonstrated in the laboratory in Fusarium oxysporum f. sp. cubense (FOC). The goals of this dissertation were threefold: to ascertain whether mitochondrial (mt) markers can distinguish race differences in FOC; to determine genetic relatedness of VCGs in FOC based on a mt marker; and to discover the mode of mt inheritance during a parasexual cycle.
Band patterns produced by electrophoresis of Hae III digested genomic DNA indicated that VCG differences, not race, could be discerned by mtDNA analysis. Primers were designed to amplify a mt intergenic locus which served as a molecular marker to screen 55 strains of FOC in 16 VCGs using both single strand conformational polymorphism and DNA sequencing. Based on homogeneity of the locus, strains were assigned to seven mitotypes, a classification unit which I introduced and found informative for grouping related VCGs.
To determine the mode of mt inheritance during a parasexual cycle, strains in different mitotypes were paired. Mitochondrial inheritance in all hybrid progeny was found to be uniparental. I speculated that if a parasexual cycle occurs in nature there would be greater variation in the nuclear genome than the mt. This could produce multiple VCGs within a mitotype, a phenomenon observed in FOC. Based on these data, I concluded that parasexuality in nature may contribute to the diversity observed in Fusarium oxysporum.
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Meyer, Tania. "Agrobacterium tumefaciens-mediated transformation of Fusarium oxysporum f. sp. cubense for pathogenicity gene analysis." Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-06122009-132700/.
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Costa, Juliana Leles. "Estudos histológicos e moleculares da interação Musa spp. x Fusarium oxysporum f. sp. cubense." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-29052013-170512/.
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A doença da bananeira \'mal-do-Panamá\', causada pelo fungo Fusarium oxysporum f. sp. cubense (Foc) é uma das doenças mais destrutivas da bananeira e é considerada uma das seis doenças economicamente mais importante da história da humanidade. Algumas cultivares resistentes, como a \'BRS Platina\', foram lançadas pela Embrapa, porém para a sustentabilidade da resistência é necessário entender os mecanismos moleculares envolvidos na resposta de resistência e defesa. O objetivo deste estudo foi caracterizar o processo de infecção pelo Foc raça 1 em três cultivares contrastantes para a resistência e analisar o padrão transcricional no início da interação. A análise histopatológica indicou que o Foc raça 1 penetra pela raízes laterais e principal, colonizando os espaços inter e intracelular do córtex nas três cultivares. Foram visualizadas, hifas \'globosas\' na cultivar suscetível \'Maçã\' com a formação de estruturas de resistência, como clamidósporos. Na cultivar resistente \'BRS Platina\', foi observado por microscopia óptica no período inicial da interação (24 horas após inoculação) a indução de respostas de defesa da planta, como formação de zona de cicatrização, e aos 15 dias após inoculação, formação de tilose, presença de cristais de oxalato de cálcio e deposição de calose. Foi utilizada a tecnologia Illumina para sequenciamento massal de RNA e abordagens de bioinformática para identificar genes diferencialmente expressos (DE) relacionados com a resposta de defesa de bananeira em interações compatíveis e incompatíveis. O sequenciamento paired-end gerou um total de 113.632.486 fragmentos (reads) com alta qualidade. Do total de reads alinhados no genoma referência (\'DH-Pahang\'), 55.555.480 alinharam-se com genes conhecidos e anotados no genoma referência, sendo utilizados para a análise DE inoculado x não inoculado, permitindo detectar 2.307 genes para as três cultivares. Os genes anotados de cada cultivar foram comparados, sendo identificados quatro genes comuns para as três cultivares, dez compartilhados entre \'Maçã\' e \'Prata-anã\', 21 compartilhados entre \'BRS Platina\' e \'Maçã\', 114 compartilhados entre \'BRS Platina\' e \'Prata-anã\', além de 75 serem exclusivos de \'Maçã\', 599 de \'BRS Platina\' e 1484 de \'Prata-anã\'. O mecanismo de resistência/defesa ao Foc em \'BRS Platina\', ocorre em nível de percepção precoce na presença do patógeno desencadeando resposta de defesa inexistente em \'Maçã\', e com cinética distinta da cultivar com resposta intermediária (\'Prata-anã\'). Dessa forma, os resultados permitiram propor um modelo da resposta de defesa/resistência ao Foc raça 1 em bananeira, baseando-se no nível de indução de genes que codificam para proteínas de reconhecimento do patógeno (receptor like kinase), fatores de transcrição (WRKY e MYB); reforço e síntese de parede celular, degradação da parede celular do fungo (quitinase e glucanases), heat shocks, enzimas antioxidantes e na resposta visualizada pela histologia na cultivar \'BRS Platina\'. Sendo assim, este trabalho fornece novas perspectivas para estudos de análise funcional, identificação e anotação de novos genes relacionados a resposta de defesa e resistência ao Foc raça 1.The banana Panama disease, caused by fungus Fusarium oxysporum f. sp. cubense (Foc), is one of the most destructive disease of the industry, and it is considered one of the six most economically important of all times. A few cultivars, such as \'BRS Platina\', were released, but it is still necessary to understand molecular mechanisms involved in defense response and resistance. The objective of this study was to characterize the infection process by Foc in three banana cultivars contrasting for resistance to Foc and to analyze the transcriptional profile at the beginning of interaction. In this way, Foc race 1 penetrated the main and lateral roots, colonizing inter- and intracellular spaces of the root cortex in the three cultivars. Hyphae were globose in the susceptible cultivar \'Maçã\' with the formation of resilience structure, such as chlamydospores. In the resistant cultivar \'BRS Platina\', during the initial period of interaction (24 hours after inoculation), induced of plant defense responses, such as a healing zone, tylosis formation, presence of calcium oxalate and callose deposition. The Illumina technology were applied to sequence RNA, followed by bioinformatic tools to identify genes differentially expressed (DE) related to resistance and defense response in the compatible and incompatible interactions. Pair-end sequencing generated a total of 113,632,486 reads with high quality. From the total of aligned reads to the banana reference genome (\'DH-Pahang\'), 55,555,480 aligned with gene models annotated in the reference genome. The aligned contigs were analysed for DE, comparing inoculated x non-inoculated, enabling the detection of 2307 genes for the three cultivars. Each annotated gene from each cultivar was compared: four common genes to the three cultiars; 10 genes were shared between \'Maçã\' and \'Prata-anã\'; 21 shared between \'BRS Platina\' and \'Maçã\'; 114 shared between \'BRS Platina\' and \'Prata-anã\', plus 75 exclusive to \'Maçã\'; 599 exclusive to \'BRS Platina\' and 1,484 to \'Prata-anã\'. The mechanism of resistance/defense in \'BRS Platina\', level of perception occurs early in the presence of the pathogen defense response triggering nonexistent in \'Maçã\' and with kinetics distinct cultivar with intermediate response (\'Prata-anã\'). Thus, the results have provided a model of defense response/resistance to Foc race 1 in banana, based on the level of gene induction that encode recognition proteins (Receptor-like Kinase, RLK), transcription factors (WRKY and MYB), cell wall synthesis and reinforcement, degradation of fungal cell wall (chitinases and glucanases), heat shocks , proteins;anto-oxidative enzymes and visualized by histologcal in response cultivar \'BRS Platina\'. The present work offer new perspectives to functional analyses, identification and annotation of new genes related to resistance and defense response to Foc race 1.
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Meyer, Tanja. "Agrobacterium tumefaciens-mediated transformation of Fusarium oxysporum f. sp. cubense for pathogenicity gene analysis." Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/25473.
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Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most destructive plant diseases in recorded history. The disease was first discovered in Australia in 1874 but became renowned for the severe losses it caused to export banana plantations during the 1960s in Central America. The banana export industry was saved only by replacing Gros Michel bananas, the dessert banana grown for the export market, with highly resistant Cavendish banana cultivars. Despite this apparent solution, the fungus was found to attack Cavendish bananas in the sub-tropics, where plants were believed to be predisposed to the disease by the cool winter climate. Good management practices and conventional disease management strategies have not been sufficient to reduce losses and stop the disease from spreading, and today Fusarium wilt can be found in almost all banana-producing countries of the world. Since 1988, Foc has been responsible for significant losses of Cavendish bananas in tropical Asia. The only sustainable control measure, the use of resistant varieties, is not always popular as people prefer to eat locally adopted varieties that, unfortunately, are susceptible to Foc. Sustainable Fusarium wilt management in banana depends on the improvement of existing banana cultivars or the development of novel disease management strategies. Molecular biology and biotechnology provide opportunities to introduce foreign resistance genes into existing cultivars and to develop new, environmentally friendly products that can protect susceptible bananas from Foc. Better knowledge of the Fusarium wilt pathogen, its diversity, and its mechanisms of pathogenesis will contribute significantly to developing these novel approaches for control of the disease. Molecular information on the pathogenicity of Foc, however, is limited, whereas other formae speciales of F. oxysporum have been better studied. In this thesis, Agrobacterium tumefaciens-mediated transformation of (ATMT) was employed to investigate genes responsible for pathogenicity of Foc to banana. Chapter 1 provides an overview of pathogenicity in F. oxysporum. Pathogenic and non-pathogenic forms of the fungus are first introduced to the reader, and then the biology, epidemiology and etiology of pathogenic forms of F. oxysporum are discussed. The genetic make-up and ability of the Fusarium wilt fungus to cause disease in plants concludes the first part of the review. In recent years, there has been a noted increase in the number of techniques available to study hostpathogen interactions. The second part of the review concentrates on these techniques and their applications in studying pathogenicity of the Fusarium wilt pathogen. In Chapter 2, an ATMT and screening system for Foc was developed. Five A. tumefaciens strains were evaluated for their efficiency to transform Foc with a randomly integrating vector that confers hygromycin B resistance and expression of green fluorescent protein (GFP). A small insertion mutant library of Foc was created, and a subset of transformants was characterized by determining the number of T-DNA inserts present, the location and identity of predicted genes disrupted by T-DNA insertion, and whether transformants of Foc were altered in their virulence against susceptible banana plants. In Chapter 3, the role of a known pathogenicity gene, Frp1, of the tomato pathogen F. oxysporum f. sp. lycopersici (Fol) was investigated in Foc. The first objective was to isolate and characterize the Frp1 gene in Foc, and to compare it to the homologous gene in Fol. A vector containing a modified Fol Frp1 gene was then obtained and used for targeted disruption of the gene in Foc via ATMT. Mutants in which the Frp1 gene was disrupted were then analyzed for GFP expression, culture morphology, and alterations in pathogenicity to banana.Dissertation (MSc)--University of Pretoria, 2008.
Microbiology and Plant Pathology
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Sabogal, Ana. "Influencia del zinc en la resistencia del plátano al mal de Panamá (Fusarium oxysporum f.sp. cubense)." Revista de Química, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/99562.
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El presente articulo revisa la función del zinc en la planta de plátano. Partiendo de la premisa que una balanceada nutrición del plátano conzinc mejora la resistencia de la planta a la enfermedad denominada mal de Panamá causada por el hongo Fusarium oxysporum f. sp. cubense. Para ello se realiza el cultivo del plátano in vitro con tres dosis de zinc y se describe los síntomas visuales de deficiencia en plantas de laboratorio.La resistencia del plátano a la enfermedad parece estar influenciada por la formación de un tejido parenquimático en el xilema denominado tilosas y a la formación de geles, tejido producido a partir de la pared celular de las células exteriores del xilema. Estos dos tejidos bloquean el xilema impidiendo la difusión de la enfermedad. El zinc influye en laformación de estos tejidos al estar vinculado al metabolismo de la auxina. Las plantas resistentes a la enfermedad tienen una mayor velocidad de formación de tilosas.
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SILVA, Denise de Santana. "Diversidade genética de isolados de Fusarium oxysporum f. sp. cubense em helicônia utilizando ARDRA e RAPD." Universidade Federal Rural de Pernambuco, 2009. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6462.
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Denise de Santana Silva.pdf: 550225 bytes, checksum: ad8bfba40464a81bb730c91685eba898 (MD5)Made available in DSpace on 2017-02-20T13:53:01Z (GMT). No. of bitstreams: 1 Denise de Santana Silva.pdf: 550225 bytes, checksum: ad8bfba40464a81bb730c91685eba898 (MD5) Previous issue date: 2009-01-23
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Heliconias are the most cultivated flowers in tropical floriculture of the Brazil northeast, due to its characteristics like beauty, exotic, exuberant colors and rusticity, but its yield has being affected by Fusarium wilt caused by Fusarium oxysporum f. sp. cubense. The present study had how objective to determine the genetic diversity existing between the isolates of F. oxysporum f. sp. cubense collected in heliconia and banana through the ITS region of rDNA using ARDRA (Amplified Ribossomal DNA Restriction Analysis), markers like RAPD (Random Amplified Polymorphic DNA). In the ARDRA analysis products amplified by ITS1 and ITS4 primers were digested by restriction enzymes Hae III, Xho I, Hind III and Eco IV by 37ºC. But only enzyme Hae III showed to be efficient a molecular marker, to analysis genetic diversity of F. oxysporum f. sp. cubense to RAPD marker was realized the Polymerase Chain Reaction (PCR) using tenoligonucleotides follow arbitrary up, only seven oligonucleotides generated a total 44 bands polymorphic with fragments varying from 100 pb to 700 pb. The two techniques used in the study genetic diversity showed high genetic variability of fungal, don’t related to with geographical region where were colleted the isolates.
As helicônias são as flores mais cultivadas dentro da floricultura tropical no Nordeste brasileiro, devido a características como beleza, exoticidade, cores exuberantes e rusticidade, porém a produção de várias espécies vem sendo afetada pela murcha de fusário, causada pelo fungo de Fusarium oxysporum f. sp. cubense. O presente trabalho teve como objetivo caracterizar a diversidade genética existente entre os isolados de F.oxysporum f. sp. cubense, coletados em helicônias e bananeiras através da análise da região ITS do rDNA utilizando ARDRA (Amplified Ribossomal DNA Restriction Analysis) e marcadores do tipo RAPD (Random Amplified Polymorphic DNA). Para a amplificação da região do rDNA, foram utilizados os primers ITS1 e ITS4 que foram digeridos pelas enzimas de restrição Hae III, Xho I, Hind III e Eco IV a 37ºC. Porém apenas a enzima Hae III, neste trabalho mostrou ser um marcador molecular eficiente,utilizada na técnica de ARDRA para estudos de diversidade genética dos isolados. Para o marcador RAPD realizou-se a Polymerase Chain Reaction (PCR) utilizando-se dez oligonucleotídeos de seqüência arbitrária, onde apenas sete oligonucleotídeos geraram um total de 44 bandas polimórficas com fragmentos que variaram de 100pb a 700pb. As duas técnicas utilizadas no estudo de diversidade genética evidenciaram alta variabilidade genética do fungo, não relacionada com as regiões geográficas onde foram coletados os isolados.
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Silva, Cristiane Maria da. "Análise da diversidade genética por marcadores RAPD e SSR em Fusarium oxysporum f. sp. cubense no Estado de Santa Catarina." reponame:Repositório Institucional da UFSC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/92283.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-graduação em Recursos Genéticos Vegetais, Florianópolis, 2009Made available in DSpace on 2012-10-24T07:27:40Z (GMT). No. of bitstreams: 1 274971.pdf: 2846578 bytes, checksum: f745a914e07ddeda6a34cc83417453f8 (MD5)
O Mal-do-Panamá causado por Fusarium oxysporum f. sp. cubense (FOC) é um dos principais problemas fitossanitários da bananicultura. Para esta doença, o uso da resistência genética é o método de controle recomendável. Porém, sua eficiência depende tanto de genes de resistência disponíveis como da presença de patótipos do patógeno. Assim este estudo teve como objetivo caracterizar a diversidade genética de isolados de FOC por meio de descritores morfológicos e marcadores moleculares (RAPD, SSR). Para tanto, foram avaliados 66 isolados coletados em regiões produtoras de Santa Catarina. Os resultados de patogenicidade revelaram que 100% dos isolados foram patogênicos à bananeira da cultivar Enxerto. Quanto às características morfológicas dos isolados não se observou diferenças significativas com relação à taxa de crescimento das colônias, que variaram de 4,4 a 6,6 mm.dia-1. A coloração das colônias sobre meio de cultura BDA variou de branco, salmão e roxo. Os resultados utilizando marcadores moleculares RAPD apresentaram uma variabilidade considerável entre os isolados de FOC, com estimativas de similaridade que variaram de 35 a 98%. Baseado nos 10 marcadores selecionados de RAPD, os 66 isolados foram agrupados em cinco grupos distintos, sendo que o número de indivíduos provenientes das regiões norte e sul do Estado foi igualmente distribuído no primeiro grupo, onde 58 indivíduos foram agrupados. Nos outros quatro grupos formados teve-se somente isolados provenientes do norte do Estado, os quais apresentaram uma maior distância genética quando comparados ao grupo um. A técnica de marcador molecular SSR separou os isolados em três grupos distintos. O primeiro grupo foi constituído de 59 indivíduos provenientes dos diversos municípios onde as coletas foram feitas. O segundo grupo, composto por dois isolados (CO16, JS23), caracterizou-se por apresentar alelo nulo para o marcador MB11. Já o terceiro grupo, formado por quatro isolados (JS26, SI53, SI54, SI55, SI56), apresentou um alelo extra no marcador MB02. No estudo de compatibilidade vegetativa não foi possível observar o pareamento entre os quatro isolados testados não havendo, portanto compatibilidade vegetativa entre os mesmos. Não houve associação dos agrupamentos RAPD e SSR com origens geográficas e características morfológicas da colônia de FOC, visto que os isolados foram distribuídos indistintamente nos grupos.
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Van, den Berg Noëlani. "Identification of genes associated with tolerance in the C Cavendish banana selection, GCTCV 218, against Fusarium oxysporum f.sp. cubense 'subtropical' race 4." Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-11082006-171800.
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Almeida, Nayane Oliveira. "Ocorrência de nematoides na cultura da banana no estado de Goiás e sua correlação com o mal-do-Panamá e com fatores edáficos." Universidade Federal de Goiás, 2016. http://repositorio.bc.ufg.br/tede/handle/tede/6704.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The problems caused by nematodes and by the Panama disease on banana plantations are responsible for production losses and limiting to its cultivation. In the state of Goiás there is few information about the nematode genus that affect this crop, and its relationship with the incidence of the fungus Fusarium oxysporum f. sp. cubense (Foc). This research aimed to survey the occurrence of plant parasitic nematodes, the incidence of Foc and soil attributes, and determine if there is a correlation among these factors. In January 2015, twelve banana producing regions in the state of Goiás were sampled: Anápolis, Caiapônia, Goiatuba, Itaguaru, Itumbiara (two areas), Jataí, Morrinhos, Ouro Verde, Palestina, Taquaral and Uruana. All sampled areas, except Morrinhos, revealed contamination with Foc, and all had different genus of nematodes. Meloidogyne sp., Helicotylenchus sp. and Rotylenchus sp. were the main genus of plant parasitic nematodes present in the banana plantations, with Meloidogyne sp. and Rotylenchus sp. the most dominant and abundant genus. We found that Pratylenchus sp. increases the population levels of F. oxysporum and that Helicotylenchus sp. has been affected by the concentration of P, Ca, Mn and the soil pH.
Os problemas fitossanitários causados por nematoides e pela doença mal-do-Panamá, na cultura da banana, são responsáveis por grandes perdas de produção ou são fatores limitantes de seu cultivo. Em Goiás, são escassas as informações sobre os gêneros de nematoides que afetam a bananicultura, bem como sua relação com a incidência do fungo Fusarium oxysporum f. sp. cubense (Foc), agente causal do mal-do-Panamá. Assim, esse trabalho teve por objetivo fazer levantamento da ocorrência de fitonematoides, da incidência de Foc e dos atributos dos solos, e determinar se há correlação entre estes fatores. Em janeiro de 2015, foram amostradas doze regiões produtoras de banana no estado de Goiás, distribuídas em onze municípios: Anápolis, Caiapônia, Goiatuba, Itaguaru, Itumbiara, Jataí, Morrinhos, Ouro Verde, Palestina, Taquaral e Uruana. Todas as áreas amostradas, exceto a do município de Morrinhos, apresentaram-se contaminadas com Foc, e todas apresentaram diversos gêneros de fitonematoides. Meloidogyne sp., Helicotylenchus sp. e Rotylenchus sp. foram os principais gêneros de fitonematoides presentes nos bananais no estado de Goiás, sendo Meloidogyne sp. e Rotylenchus sp. os gêneros mais dominantes e abundantes. Foi constatado que a presença de Pratylenchus sp. aumenta o nível populacional de F. oxysporum e que Helicotylenchus sp. é afetado pelos teores de P, Ca, Mn e pelo pH do solo.
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Cunha, Cristiane Maria da Silva da. "Caracterização genética de isolados de Fusarium oxysporum f. sp. cubense e desenvolvimento de um marcador SCAR para identificação de suscetibilidade ao mal-do-panamá da bananeira." reponame:Repositório Institucional da UFSC, 2014. https://repositorio.ufsc.br/xmlui/handle/123456789/128789.
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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Recursos Genéticos Vegetais, Florianópolis, 2014.Made available in DSpace on 2015-02-05T20:20:51Z (GMT). No. of bitstreams: 1 332314.pdf: 1573375 bytes, checksum: bff58997fb8a8d0eb5d2ed9710dc1790 (MD5) Previous issue date: 2014
O mal-do-panamá, causado por Fusarium oxysporum f. sp. cubense (Foc), é uma doença endêmica em todas as regiões produtoras de banana, sendo citado como uma das seis doenças mais importantes de plantas cultivadas e responsável por grandes perdas econômicas. O cultivo da bananeira em Santa Catarina sofre com essa doença e uma das estratégias usadas no seu controle é a substituição das cultivares do subgrupo Prata, consideradas suscetíveis ao fungo, pelas cultivares do subgrupo Cavendish, devido a sua maior resistência. Nos últimos anos, no entanto, essa estratégia vem sendo questionada em função da ocorrência de focos de Foc nos bananais de cultivares do subgrupo Cavendish. Tendo em vista a importância da bananicultura no Sul do Brasil, região subtropical, a constatação do avanço da doença e o aumento de focos do mal-do-panamá em bananais de cultivares do subgrupo Cavendish nessa região, este trabalho teve como objetivo caracterizar isolados de Fusarium oxysporum f. sp. cubense coletados de cultivares de bananeira dos subgrupos Prata e Cavendish e desenvolver um marcador SCAR associado à suscetibilidade ao mal-do-panamá. Avaliou-se uma população de 152 isolados de Foc coletados em 13 regiões produtoras de banana do Estado de Santa Catarina por meio de características morfológicas, níveis de agressividade, utilização de marcadores moleculares microssatélites e intermicrossatélites (SSR, ISSR) e também pelo sequenciamento do fator de alongação TEF 1a. A patogenicidade foi confirmada para todos os isolados, e os critérios morfológicos confirmaram a identidade do fungo. Em relação aos níveis de agressividade, foi possível classificar os isolados em três grupos distintos, considerados como pouco agressivo moderadamente agressivo e agressivo. Quando utilizamos as técnicas moleculares, observou-se que os resultados de ISSR, SSR e sequenciamento TEF 1a revelaram uma menor variação entre os isolados analisados, sendo que, a maioria apresentou 100% de similaridade interna. Entre esses marcadores, ISSR + SSR foi o mais polimórfico, sendo capaz de diferenciar mais indivíduos e com uma maior percentagem de dissimilaridade. Na segunda etapa desse trabalho, aplicando-se 78 iniciadores arbitrários em DNA genômico de genótipos resistentes e suscetíveis, uma banda de RAPD associada à susceptibilidade foi selecionada e usada para gerar o iniciador SCAR SuscPD-F/SuscPD-R. Este marcador foi validado em 28 cultivares de bananeira e os resultados indicaram um elevado grau de especificidade do marcador, o qual foi capaz de discriminar entre os dois grupos de contraste resistentes ou suscetíveis com um poder12discriminatório de 93%. Os resultados obtidos poderão apoiar os trabalhos de melhoramento genético da cultura, acelerando a seleção e o desenvolvimento de cultivares com maior nível intrínseco de resistência às infecções e melhorias nas técnicas de controle à doença. Esse trabalho representa uma contribuição na caracterização de Foc e no estudo de resistência da bananeira em áreas subtropicais, onde há até o momento uma carência de resultados e ferramentas nesta área.
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Echeverria, Santy Peraza. "Molecular cloning and characterisation of potential Fusarium resistance genes in banana (Musa acuminata ssp. Malaccensis)." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16573/.
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Banana is the most important fruit crop in the world but ironically one of the crops least studied. This fruit constitutes a major staple food for millions of people in developing countries and also it is considered the highest selling fruit in the world market making this crop a very important export commodity for the producing countries. At the present time, one of the most significant constraints of banana production that causes significant economical losses are fungal diseases. Among these, Panama disease, also known as Fusarium wilt has been the most catastrophic. Panama disease is caused by the soil-borne fungus Fusarium oxysporum formae specialis (f.sp) cubense (FOC), which infects susceptible bananas through the roots causing a lethal vascular wilt. To date, the race 4 of this pathogen represents the most serious threat to banana production worldwide since most of the commercial cultivars are highly susceptible to this pathogen. Introduction of FOC resistance into commercial cultivars by conventional breeding has been difficult because edible bananas are sterile polyploids without seeds. Genetic transformation of banana, which has already been established in various laboratories around the world has the potential to solve this problem by transferring a FOC race 4 resistance gene into susceptible banana cultivars (eg. Cavendish cultivars). However, a FOC resistant (R) gene has not been isolated. Genes that confer resistance to Fusarium oxysporum have been isolated from tomato and melon using a map-based positional cloning approach. The tomato I2 and melon Fom-2 genes belong to the non-Toll/interleukin like receptors (TIR) subclass of nucleotide-binding site and leucine-rich repeat (NBS-LRR) R genes. These genes confer resistance only to certain races of F. oxysporum in their corresponding plant families limiting their use in other plant families. The fact that these two Fusarium resistance genes share the same basic non-TIR-NBS-LRR structure suggests a similar Fusarium resistance mechanism is shared between the families Solanaceae and Cucurbitaceae. This observation opens the possibility to find similar Fusarium resistance genes in other plant families including the Musaceae. A remarkable discovery of a population of the wild banana Musa acuminata subspecies (ssp.) malaccensis segregating for FOC race 4 resistance was made by Dr. Ivan Buddenhagen (University of California, Davis) in Southeast Asia. Research carried out at Queensland Department of Primary Industries (Australia) using this plant material has demonstrated that a single dominant gene is involved in FOC race 4 resistance (Dr. Mike Smith, unpublished results). Tissue-culture plantlets of this FOC race 4 segregating population were kindly provided to the Plant Biotechnology Program (Queensland University of Technology) by Dr. Mike Smith to be used in our research. This population holds the potential to assist in the isolation of a FOC race 4 resistance gene and other potential Fusarium resistance genes. The overall aims of this research were to isolate and characterise resistance gene candidates of the NBS-type from M. acuminata ssp. malaccensis and to identify and characterise potential Fusarium resistance genes using a combination of bioinformatics and gene expression analysis.
Chapter 4 describes the isolation by degenerate PCR of five different classes of NBS sequences from banana (Musa acuminata ssp malaccensis) designated as resistance gene candidates (RGCs). Deduced amino acid sequences of the RGCs revealed the typical motifs present in the majority of known plant NBS-LRR resistance genes. Structural and phylogenetic analyses showed that the banana RGCs are related to non-TIR subclass of NBS sequences. The copy number of each class was estimated by Southern hybridisation and each RGC was found to be in low copy number. The expression of the RGCs was assessed by RT-PCR in leaf and root tissues of plants resistant or susceptible to Fusarium oxysporum f. sp. cubense (FOC) race 4. Four classes showed a constitutive expression profile whereas no expression was detected for one class in either tissue. Interestingly, a transcriptional polymorphism was found for RGC2 whose expression correlated with resistance to FOC race 4 suggesting a possible role of this gene in resistance to this devastating FOC race. Moreover, RGC2 along with RGC5 showed significant sequence similarity to the Fusarium resistance gene I2 from tomato and were chosen for further characterisation. The NBS sequences isolated in this study represent a valuable source of information that could be used to assist the cloning of functional R genes in banana.
Chapter 5 describes the isolation and characterisation of the full open reading frame (ORF) of RGC2 and RGC5 cDNAs. The ORFs of these two banana RGCs were predicted to encode proteins that showed the typical structure of non-TIR-NBS-LRR resistance proteins. Homology searches using the entire ORF of RGC2 and RGC5 revealed significant sequence similarity to the Fusarium resistance gene I2 from tomato. Interestingly, the phylogenetic analysis showed that RGC2 and RGC5 were grouped within the same phylogenetic clade, along with the Fusarium resistance genes l2 and Fom-2. These findings suggest that the banana RGC2 and RGC5 are potential resistance gene candidates that could be associated with Fusarium resistance. The case of RGC2 is more remarkable because its expression was correlated to FOC race 4 resistance (Chapter 4). As a first step to test whether RGC2 has a role in FOC race 4 resistance, different expression constructs were made with the ORF of this sequence. One of the constructs contains a RGC2 putative promoter region that was successfully cloned in this work. These constructs will be used to transform susceptible banana plants that can then be challenged with FOC race 4 to assess whether resistance has been acquired by genetic complementation.
The results of this thesis provide interesting insights about the structure, expression and phylogeny of two potential Fusarium resistance genes in banana, and provide a rational starting point for their functional characterisation. The information generated in this thesis may lead to the identification of a Fusarium resistance gene in banana in further studies and may also assist the cloning of Fusarium resistance genes in other plant species.
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Cooper, Jessica G. "Cucurbit Downy Mildew (Pseudoperonospora cubensis): Cucumber Resistance." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/49606.
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Pseudoperonospora cubensis (Bert. et Curt) Rost. is the causal agent of cucurbit downy mildew (CDM). It is the most damaging cucumber pathogen on the Eastern Shore of Virginia and eastern parts of the United States. Pseudoperonospora cubensis is an obligate oomycete pathogen, infecting crops within the Cucurbitaceae family. The disease is characterized by angular chlorotic lesions and a downy or felt-like appearance on the abaxial side of the leaf. Control of this pathogen includes use of resistant cucumber cultivars and costly fungicide programs. Continuous use has led to resistance to commonly used fungicides. This has become a major concern and in response, seed companies have developed cucumber cultivars which claim downy mildew resistance. This study evaluates different cucumber cultivars and assesses their level of resistance to CDM. The results indicate that an integrated management approach of reduced fungicide application and the use of resistant cultivars can suppress levels of CDM and yield a cucumber crop. Additionally, a molecular study was conducted, comparing the relative expression of genes encoding a basic PR-1 protein, a cytosolic ascorbate peroxidase protein and three resistance (R) gene proteins, in nineteen cultivars. All of the selected genes were analyzed using real-time PCR. The relative expression levels of the R-genes varied between cultivars. The basic PR-1 protein decreased expression in the majority of the cultivars, suggesting no involvement in the first twenty-four hours. Cytosolic ascorbate peroxidase relative expression levels suggest an increase in susceptible cultivars and a decrease in tolerant cultivars.Master of Science
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Coward, Daniel R. "Sums of two rational cubes." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320587.
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Volte, Emmanuel. "Miroirs, Cubes et Feistel Dissymétriques." Thesis, Cergy-Pontoise, 2014. http://www.theses.fr/2014CERG0701/document.
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La première partie est consacrée à l'étude d'attaques génériques sur des schémas de Feistel dissymétriques. Ces attaques sont en fait des distingueurs qui calculent sur une partie des clairs-chiffrés le nombre de paires vérifiant un système d'égalités et de non-égalités sur un groupe fini. La recherche de ce type d'attaques a été automatisée et améliorée, notamment en tenant compte de goulots d'étranglement. Plus généralement, des travaux sur ce type de systèmes, que l'on désigne par les termes << théorie du miroir >> sont exposés dans cette partie. En particulier, on décrit le problème de la somme de deux bijections sur un groupe fini.La deuxième partie décrit un des candidats à la compétition SHA-3 : la fonction de hachage CRUNCH. Cette fonction reprend un schéma de Feistel dissymétrique et utilise la somme de deux bijections. De plus, un nouveau mode d'enchaînement a été utilisé.Dans la dernière partie on traite de problème d'authentification à divulgation nulle de connaissance. D'abord avec les polynômes à plusieurs variables, puis avec un problème difficile lié aux groupes symétriques. Une illustration est donnée avec le groupe du Rubik's Cube.Enfin une méthode originale pour tenter de trouver une solution aux équations de Brent est donnée en annexeThe first part is dedicated to the study of generic attacks in unbalanced Feistel schemes. All these attacks are distinguishers that counts how many number of couples (plain text, cipher text) verify a system of equalities and non-equalities on a finite groupe. With the help of algorithms we have found all the possible attacks, and some attacks with a neck bottle have been rejected automatically. More generally, we describe some works about the "mirror theory" that deals about that kind of systems. We specially describe the problem of the sum of two bijections in a finite group.The second part describes one of the candidate of the SHA-3 competition : the hash function called CRUNCH. This function includes the sum of two bijections, and each bijection is an unbalanced Feistel Scheme. A new chaining process for long messages is given.In the last part we deal with zero-knowledge authentication problems. The first protocol is based on multivariate polynomials. The second is linked to a difficult problem in symmetric groups. We take the example of the Rubik's cube group.Finally, we reveal some works on Brent equations. We build an algorithm that may find one solution
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Bliss, Adam. "Covering Numbers of the Cubes." Scholarship @ Claremont, 2003. https://scholarship.claremont.edu/hmc_theses/141.
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How many triangles does it take to make a square? The answer is simple: two. This problem has a direct analogue in dimensions three and higher, but the answers are much harder to find. We provide new lower bounds in dimensions 4 through 13, an asymptotic lower bound which is inferior to the best known bound in high dimensions, and some new ideas which produce good upper bounds in both low and high dimensions.
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Barreto, Elisa da Silva. "Produção, purificação e caracterização de uma poligalacturonase do Chrysoporthe cubensis." reponame:Repositório Institucional da UFOP, 2016. http://www.repositorio.ufop.br/handle/123456789/6372.
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Programa de Pós-Graduação em Biotecnologia. Núcleo de Pesquisas em Ciências Biológicas, Pró-Reitoria de Pesquisa de Pós Graduação, Universidade Federal de Ouro Preto.Submitted by giuliana silveira (giulianagphoto@gmail.com) on 2016-04-12T18:33:25Z No. of bitstreams: 1 DISSERTAÇÃO_ProduçãoPurificaçãoCaracterização.pdf: 1800894 bytes, checksum: 81ba847b0ec8fcfae1907bb11bb2a53e (MD5)
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Os objetivos deste trabalho foram cultivar o fungo Chrysoporthe cubensis em diferentes fontes de carbono de baixo custo, para induzir a produção da poligalacturonase, purificar e caracterizar a enzima, para identificar propriedades funcionais interessantes para possíveis aplicações biotecnológicas. O fungo foi cultivado em meio semi sólido (67% de umidade), com farelo de trigo, casca de maracujá e casca de laranja, além disso os resíduos de frutas foram misturados ao farelo nas proporções 1:1, 3:1 e 9:1 (farelo: resíduo de fruta). O fungo apresentou maior produção da poligalacturonase em meio composto por farelo de trigo e casca de maracujá (3:1), com atividade de 41.49 U/g de substrato, sendo 1,32 vezes maior do que no cultivo em farelo de trigo puro. O extrato enzimático bruto foi purificado a partir da cromatografia de troca iônica DEAE-Sepharose, seguida por cromatografia em gel filtração em coluna Sephacryl S-200, exibindo atividade específica de 1117,45U/mg, com aumento de 28,34 vezes e rendimento final de 29,2 %. A massa molecular da poligalacturonase, obtida através de SDS-PAGE 12% foi de, aproximadamente, 40,74Kd. A enzima apresentou pH e temperatura ótimos de 3,5 e 50°C, repectivamente, e meia vida de 4,05 minutos a 50°C. A enzima se manteve estável na faixa de pH de 2,5 a 8,5, apresentando acima de 80% da atividade após 1h. O substrato preferencial da enzima foi o ácido poligalacturônico e o km e Vmax foi de 0,766 mg.mL-1 e 1,88U/mL, respectivamente. Os resultados obtidos neste trabalho indicam que a PG de C. cubensis é uma enzima importante dentro do complexo hidrolítico secretado pelo fungo quando cultivado em SSF, em meio contendo resíduos agroindustriais. __________________________________________________________________________________________________________________
ABSTRACT : The aims of this study were to cultivate the fungi Chrysoporthe cubensis on differents inexpensive carbon sources, to induce polygalacturonase production, purify and characterize the enzyme to identify interesting functional properties for potential biotechnological applications. The fungi was grown in semi solid (67% moisture) with wheat bran, passion fruit peel and orange peel, in addition, the waste fruits were mixed with the meal in the ratios 1: 1, 3: 1 and 9: 1 (bran: fruit residue). The fungus showed increased production of polygalacturonase in medium composed of wheat bran and passion fruit peel (3: 1), activity of 41.49 U / g substrate, being 1.32 times higher than that in pure culture in wheat bran. The crude extract enzyme was purified from the ion exchange chromatography DEAE-Sepharose, followed by gel filtration chromatography on Sephacryl S200 column exhibiting specific activity 1117,45U / mg, an increase of 28.34 fold and final yield of 29 ,2 %. The molecular weight of the polygalacturonase obtained by SDS-12% PAGE was approximately 40,74Kd. The enzyme showed pH 3.5 and temperature to 50 ° C, respectively, and a half life of 4.05 minutes at 50 ° C. The enzyme remained stable in the pH range of 2.5 to 8.5, with over 80% of activity after one hour of incubation. The preferred enzyme substrate was polygalacturonic acid and the Km and Vmax was 0.766 mg.mL-1and 1,88 U/mL, respectively. The results of this study indicate that C. cubensis PG is an important enzyme in the hydrolytic complex secreted by the fungus when grown in SSF, in medium containing organic residues.
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Bengtsson, Fredrik. "Efficient aggregate queries on data cubes." Licentiate thesis, Luleå, 2004. http://epubl.luth.se/1402-1757/2004/53.
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Negre, Elsa. "Exploration collaborative de cubes de données." Thesis, Tours, 2009. http://www.theses.fr/2009TOUR4023/document.
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Data warehouses store large volumes of consolidated and historized multidimensional data to be explored and analysed by various users. The data exploration is a process of searching relevant information in a dataset. In this thesis, the dataset to explore is a data cube which is an extract of the data warehouse that users query by launching sequences of OLAP (On-Line Analytical Processing) queries. However, this volume of information can be very large and diversified, it is thus necessary to help the user to face this problem by guiding him/her in his/her data cube exploration in order to find relevant information. The present work aims to propose recommendations, as OLAP queries, to a user querying a data cube. This proposal benefits from what the other users did during their previous explorations of the same data cube. We start by presenting an overview of the used framework and techniques in Information Retrieval, Web Usage Mining or e-commerce. Then, inspired by this framework, we present a state of the art on collaborative assistance for data exploration in (relationnal and multidimensional) databases. It enables us to release work axes in the context of multidimensional databases. Thereafter, we propose thus a generic framework to generate recommendations, generic in the sense that the three steps of the process are customizable. Thus, given a set of sequences of queries, corresponding to the previous explorations of various users, and given the sequence of queries of the current user, our framework proposes a set of queries as recommendations following his/her sequence. Then, various instantiations of our framework are proposed. Then, we present a Java prototype allowing a user to specify his/her current sequence of queries and it returns a set of recommendations. This prototype validates our approach and its effectiveness thanks to an experimentations collection. Finally, in order to improve this data cube exploration collaborative assistance and, in particular, to share, navigate or annotate the launched queries, we propose a framework to manage queries. Thus, an instantiation to manage recommendations is presentedLes entrepôts de données stockent de gros volumes de données multidimensionnelles, consolidées et historisées dans le but d'être explorées et analysées par différents utilisateurs. L'exploration de données est un processus de recherche d'informations pertinentes au sein d'un ensemble de données. Dans le cadre de nos travaux, l'ensemble de données à explorer est un cube de données qui est un extrait de l'entrepôt de données que les utilisateurs interrogent en lançant des séquences de requêtes OLAP (On-Line Analytical Processing). Cependant, cette masse d'informations à explorer peut être très importante et variée, il est donc nécessaire d'aider l'utilisateur à y faire face en le guidant dans son exploration du cube de données afin qu'il trouve des informations pertinentes. Le travail présenté dans cette thèse a pour objectif de proposer des recommandations, sous forme de requêtes OLAP, à un utilisateur interrogeant un cube de données. Cette proposition tire parti de ce qu'ont fait les autres utilisateurs lors de leurs précédentes explorations du même cube de données. Nous commençons par présenter un aperçu du cadre et des techniques utilisés en Recherche d'Informations, Exploration des Usages du Web ou e-commerce. Puis, en nous inspirant de ce cadre, nous présentons un état de l'art sur l'aide à l'exploration des bases de données (relationnelles et multidimensionnelles). Cela nous permet de dégager des axes de travail dans le contexte des bases de données multidimensionnelles. Par la suite, nous proposons donc un cadre générique de génération de recommandations, générique dans le sens où les trois étapes du processus sont paramétrables. Ainsi, à partir d'un ensemble de séquences de requêtes, correspondant aux explorations du cube de données faites précédemment par différents utilisateurs, et de la séquence de requêtes de l'utilisateur courant, notre cadre propose un ensemble de requêtes pouvant faire suite à la séquence de requêtes courante. Puis, diverses instanciations de ce cadre sont proposées. Nous présentons ensuite un prototype écrit en Java. Il permet à un utilisateur de spécifier sa séquence de requêtes courante et lui renvoie un ensemble de recommandations. Ce prototype nous permet de valider notre approche et d'en vérifier l'efficacité avec un série d'expérimentations. Finalement, afin d'améliorer cette aide collaborative à l'exploration de cubes de données et de permettre, notamment, le partage de requêtes, la navigation au sein des requêtes posées sur le cube de données, ou encore de les annoter, nous proposons un cadre d'organisation de requêtes. Ainsi, une instanciation adaptée à la gestion des recommandations est présentée
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Gregory, Ray N. "Cyclic cutwidth of three dimensional cubes." CSUSB ScholarWorks, 1998. https://scholarworks.lib.csusb.edu/etd-project/1400.
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Clarke, Dwayne William. "The cyclic cutwidth of mesh cubes." CSUSB ScholarWorks, 2002. https://scholarworks.lib.csusb.edu/etd-project/2329.
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This project's purpose was to understand the workings of a new theorem introduced in a professional paper on the cutwidth of meshes and then use this knowledge to apply it to the search for the cyclic cutwidth of the n-cube.
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Engström, Carl, and Nawrin Oxing Felix. "Marching Cubes med Deferred Rendering motor." Thesis, Blekinge Tekniska Högskola, Sektionen för planering och mediedesign, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5542.
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Spel idag kräver en enorm mängd arbetstimmar för att skapas, därför behövs alltid sätt att spara tid och automatisera processer. Algoritmer för polygoniseringen av skalärfält, som Marching Cubes, har under de senaste åren blivit ett allt vanligare tillvägagångssätt för att automatiskt generera terräng. Scenkomplexiteten och kraven för visuell kvalitet i dagens spel ökar ständigt. Därmed kommer också kravet för prestandaeffektiva renderingsmetoder. Deferred rendering är en renderingsmetod som kan hantera scener med stora mängder ljuskällor och hög scenkomplexitet samtidigt. För att undersöka integreringen mellan procedurellt skapad terräng och en deferred rendering pipeline, skapades en applikation i DirectX 11 för att undersöka implementeringen och potentiella optimeringar av denna integration.Detta projekt handlar om slumpmässig procedurell skapning av digital terräng för bruk inom datorspel, och hur man i denna kontext kan ta nytta av en grafikmotor som använder renderingstekniken deferred rendering.
Carl Engström can be reached at: Phone: 076-102 86 00 Mail: Lemmibl@gmail.com Felix Nawrin Oxing can be reached at: Mail: felix@nawrin-oxing.se
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Andersson, Patrik. "Voxelbaserad rendering med "Marching Cubes"-algoritmen." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-6096.
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Det finns flera olika metoder och tekniker för tredimensionell rendering, alla med olika för- och nackdelar som lämpar sig för olika applikationer. Voxelbaserad rendering har använts flitigt inom vetenskapliga områden, främst inom det medicinska för visualisering av volymetrisk data. Tekniken används nu inom flera olika områden för tredimensionell rendering, t.ex. i datorspel, i matematiska applikationer och vid geologisk rekonstruktion. I den här rapporten kommer voxelbaserad rendering med Marching Cubes-algoritmen undersökas för att se hur den lämpar sig för realtidsapplikationer. Området behandlas dels teoretiskt, men även praktiskt då en implementering av Marching Cubes gjordes för att genomföra några tester för att se hur prestandan påverkades. Av testerna framkom det tydligt att algoritmen lämpar sig väl för realtidsapplikationer och dagens grafikkort. Viss optimering krävs dock för att kunna utnyttjas på bästa sätt.There are lots of different methods and techniques for three-dimensional rendering, everyone with different advantages and disadvantages that suits different applications. Voxel-based rendering has been used frequently within the scientific area, mainly within medicin for visualization of volumetric data. The technique is now used within many different areas for three-dimensional rendering, e.g. in computer games, in mathematical applications and in geological reconstruction. In this report voxel-based rendering with Marching Cubes algorithm will be researched to see how it suits for real-time applications. The area will partly be dealt with theoretically, but also practically as an implementation of Marching Cubes was done to run some tests to see how the performance was affected. From the tests it appeared cleary that the algorithm is well suited for real-time applications and today's graphics card. Though some optimization is needed to fully take advantage of it.
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Criswell, Adam. "Screening Cucumber (Cucumis sativus) for Resistance to Downy Mildew (Pseudoperonospora cubensis)." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-06272008-145848/.
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Downy mildew, a foliar disease caused by the oomycete Pseudoperonospora cubensis (Berk. and Curt.) Rostow. is one of the most destructive pathogens of cucurbits. Resistant cultivars are available but nevertheless yield losses are high in North Carolina and Poland if fungicides are not used. The first objective of this experiment was to test all available plant introduction accessions from the U.S. National Plant Germplasm System of cucumber for downy mildew resistance under field conditions. The 1289 cultigens were tested at Clinton NC, USA, and Skierniewice, Poland during 2005-2007 under natural field epidemics of the disease. Averaged over locations, eighty-one cultigens were classified as highly resistant, 130 as moderately resistant, 406 as intermediate, 408 as moderately susceptible, and 271 as highly susceptible. The 40 most resistant and 10 most susceptible cultigens from these field trials, were further evaluated in replicated field and greenhouse experiments in North Carolina, along with 22 check cultivars. Results from the retest study in North Carolina confirmed the results of the initial screening study, although the range of downy mildew ratings in the North Carolina field retest were much narrower compared with the screening results obtained in the larger study. The most resistant and most susceptible lines in the screening study were also the most resistant and most susceptible lines in the field retest. The most resistant 10 cultigens averaged over both locations were Ames 2353, Ames 2354, PI 197085, PI 197088, PI 234517, PI 321008, PI 330628, PI 432878, PI 605996 and PI 618931. These cultigens originated from India, the United States, Pakistan, P.R. China and Taiwan. Despite the identification of resistant plant introduction accessions, they were not significantly better than the most resistant cultivars currently used in either North Carolina or Poland. The most positive aspect of the screening effort was that resistant plant introductions originated from diverse geographic regions. Because geographic diversity is often associated with genetic diversity in germplasm collections, the newly identified resistant typed may carry unique alleles as compared to commercial material. If so, then the potential exists to develop recombinant types from crosses of commercial by exotic materials which may be more resistant. The second objective of this study was to measure the correlation of four response traits. A low correlation among the four response traits on a diverse array of cucumber cultigens would suggest that the traits are controlled by different genes. Field studies were conducted to measure the response traits of plant stunting, leaf necrosis, chlorosis and sporulation caused by downy mildew infection. Each of the four traits were measured on 67 diverse cucumber cultigens in North Carolina and India. All cucumber cultigens were tested in four replications and two locations under natural field epidemics of the disease. A significant genotype by location interaction was found by analysis of variance and data from the two locations were analyzed separately. In North Carolina, necrosis and chlorosis were highly correlated (r=0.90) while sporulation was moderately correlated with necrosis and chlorosis(r=0.71 and r=0.70, respectively) and not significantly correlated with stunting. Stunting was moderately correlated with necrosis and chlorosis (r=0.43 and r=0.34, respectively). In India, chlorosis and sporulation were highly correlated (r=0.97) while necrosis was moderately correlated with chlorosis, sporulation and stunting (r=0.67 and r=0.0.65 and r=0.76, respectively). Stunting was moderately correlated with chlorosis and sporulation (r=0.55 and r=0.57, respectively). Sporulation or necrosis may be controlled by a different gene(s) but another year of testing is required. Stunting may also be controlled by a different gene(s) but difficulties in differentiating between stunting resulting from genotype and stunting resulting from disease must be resolved. Different degrees of correlation among chlorosis, necrosis and sporulation in North Carolina and India may be due to the presence of different races in the two locations. These differences may also be explained by the variable number and timing of ratings between the two locations. Availability of only one set of data for sporulation in North Carolina may have reduced the correlation between it and necrosis and chlorosis. Sporulation ratings need to be taken on a weekly basis rather than once during the last rating. Therefore, the possibility exists that chlorosis, necrosis and sporulation are response traits controlled by the same genes.
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Souza, Helenize Gabriela de [UNESP]. "Resistência do eucalipto ao cancro de chrysoporthe cubensis e botryosphaeria sp." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/97156.
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O termo cancro é utilizado para designar lesões localizadas na casca do caule de plantas lenhosas que podem resultar no anelamento do caule e no secamento da parte superior da copa e a morte da planta. A melhor opção para o controle da doença é a resistência genética dos indivíduos quanto ao patógeno utilizado. Com o objetivo de estudar o comportamento de resistência e mecanismos moleculares de clones dos parentais e das progênies de eucalipto quanto ao cancro causado por Chrysoporthe cubensis e Botryosphaeria sp. foram executados ensaios em casa de vegetação e em campo. Os isolados utilizados foram Chrysoporthe cubensis e Botryosphaeria sp. sendo produzidos em meio BDA e inoculados nos indivíduos pelo método do disco. A avaliação foi realizada 60 dias após a inoculação, medindo a área da lesão de cada material. Para o patógeno C. cubensis inoculados nos parentais foi encontrado uma média de 3,20 e 6,14 cm2 de área de lesão do tronco causado pelos isolados provenientes de Piracicaba e Bofete, respectivamente, enquanto que para Botryosphaeria sp. a média variou de 7,29 cm ² a 9,72cm ² da área da lesão. Dos indivíduos testados, com C. cubensis, foram encontrados 46,66% de plantas classificadas como resistentes; 6,67% plantas moderadamente resistente, 13,33% planta moderadamente suscetíveis e 33,34% plantas suscetíveis. Já para o teste de clones com Botryosphaeria sp. verificou-se 91,67% resistentes, 5% moderadamente resistentes, 1,67% moderadamente suscetível e 1,67% suscetíveis. As variâncias fenotípicas encontradas foram de 41,32 a 0,23 inoculados com C. cubensis e 0,285 a 156,88, quando inoculados com Bothyosphaeria sp. Os coeficientes de variação foram de 125% a 15,05% para C. cubensis e 29,86% a 101,13% para Bothyosphaeria sp. Os resultados indicam que os materiais genéticos testados possuem boa fonte de resistência para os dois fitopatógenos...
The term canker is used to assign to injuries located in the bark of stems of woody plants that can result in the anelamento of stems and drying of the superior part of the crown and the death of the plant. The best option for the control of the illness is the resistance genetic of the individuals concerning to the used patógeno. The objective of this study the molecular behavior of resistance and mechanisms of clonals of parental and the lineages the eucalyptus concerning the canker caused for Chrysoporthe cubensis and Dothiorella sp. The essays executed in the greenhouse and field. The isolated ones used concerning Chrysoporthe cubensis and Dothiorella sp. being produced in inoculated medium BDA and in the individuals for the method of the disk. The evaluation was concluded 60 days after the inoculation, measuring the area of the injury of each material. For pathogeno C. cubensis inoculated in the parental ones a 6,14 was found average of 3,20 and cm² of area of isolated injury of the trunk caused for the proceeding ones from Piracicaba and Bofete, respectively. The average of the area of the injury for the studied lineages varied of 7,29 cm ² 9,72cm ² for Dothiorella sp. The clonals inoculated C. cubensis were grouped into the categories HS (highly susceptible – 33,34%), MS (moderately susceptible -13,3%), MR (moderately resistant- 6,67%), and HR (highly resistant -46,66%). The clonal tested, with Botryosphaeria sp., verified resistant 91.67%, 5% moderately resistant, 1.67% moderately susceptible and 5,26% susceptible. The phenotypic variation found was from 41,32 to 0,23, inoculated with C. cubensis while Botryosphaeria sp from 0,285 to156,88. The coefficient of variation from 125% to 15,95% for C. cubensis and 29,86% to 101,13% for Botryosphaeria sp. The results indicate that the tested genetic materials possess good source of resistance for the two fitopatógenos tested... (Complete abstract click electronic access below)
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Souza, Helenize Gabriela de 1980. "Resistência do eucalipto ao cancro de chrysoporthe cubensis e botryosphaeria sp /." Botucatu : [s.d.], 2008. http://hdl.handle.net/11449/97156.
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Orientador: Edson Luis FurtadoBanca: Marli Teixiera de Almeida Minhoni
Banca: Celso Garcia Auer
Resumo: O termo cancro é utilizado para designar lesões localizadas na casca do caule de plantas lenhosas que podem resultar no anelamento do caule e no secamento da parte superior da copa e a morte da planta. A melhor opção para o controle da doença é a resistência genética dos indivíduos quanto ao patógeno utilizado. Com o objetivo de estudar o comportamento de resistência e mecanismos moleculares de clones dos parentais e das progênies de eucalipto quanto ao cancro causado por Chrysoporthe cubensis e Botryosphaeria sp. foram executados ensaios em casa de vegetação e em campo. Os isolados utilizados foram Chrysoporthe cubensis e Botryosphaeria sp. sendo produzidos em meio BDA e inoculados nos indivíduos pelo método do disco. A avaliação foi realizada 60 dias após a inoculação, medindo a área da lesão de cada material. Para o patógeno C. cubensis inoculados nos parentais foi encontrado uma média de 3,20 e 6,14 cm2 de área de lesão do tronco causado pelos isolados provenientes de Piracicaba e Bofete, respectivamente, enquanto que para Botryosphaeria sp. a média variou de 7,29 cm ² a 9,72cm ² da área da lesão. Dos indivíduos testados, com C. cubensis, foram encontrados 46,66% de plantas classificadas como resistentes; 6,67% plantas moderadamente resistente, 13,33% planta moderadamente suscetíveis e 33,34% plantas suscetíveis. Já para o teste de clones com Botryosphaeria sp. verificou-se 91,67% resistentes, 5% moderadamente resistentes, 1,67% moderadamente suscetível e 1,67% suscetíveis. As variâncias fenotípicas encontradas foram de 41,32 a 0,23 inoculados com C. cubensis e 0,285 a 156,88, quando inoculados com Bothyosphaeria sp. Os coeficientes de variação foram de 125% a 15,05% para C. cubensis e 29,86% a 101,13% para Bothyosphaeria sp. Os resultados indicam que os materiais genéticos testados possuem boa fonte de resistência para os dois fitopatógenos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The term canker is used to assign to injuries located in the bark of stems of woody plants that can result in the anelamento of stems and drying of the superior part of the crown and the death of the plant. The best option for the control of the illness is the resistance genetic of the individuals concerning to the used patógeno. The objective of this study the molecular behavior of resistance and mechanisms of clonals of parental and the lineages the eucalyptus concerning the canker caused for Chrysoporthe cubensis and Dothiorella sp. The essays executed in the greenhouse and field. The isolated ones used concerning Chrysoporthe cubensis and Dothiorella sp. being produced in inoculated medium BDA and in the individuals for the method of the disk. The evaluation was concluded 60 days after the inoculation, measuring the area of the injury of each material. For pathogeno C. cubensis inoculated in the parental ones a 6,14 was found average of 3,20 and cm² of area of isolated injury of the trunk caused for the proceeding ones from Piracicaba and Bofete, respectively. The average of the area of the injury for the studied lineages varied of 7,29 cm ² 9,72cm ² for Dothiorella sp. The clonals inoculated C. cubensis were grouped into the categories HS (highly susceptible - 33,34%), MS (moderately susceptible -13,3%), MR (moderately resistant- 6,67%), and HR (highly resistant -46,66%). The clonal tested, with Botryosphaeria sp., verified resistant 91.67%, 5% moderately resistant, 1.67% moderately susceptible and 5,26% susceptible. The phenotypic variation found was from 41,32 to 0,23, inoculated with C. cubensis while Botryosphaeria sp from 0,285 to156,88. The coefficient of variation from 125% to 15,95% for C. cubensis and 29,86% to 101,13% for Botryosphaeria sp. The results indicate that the tested genetic materials possess good source of resistance for the two fitopatógenos tested... (Complete abstract click electronic access below)
Mestre
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Damasceno, Andrey Azedo, and 92-99233-2173. "Purificação e caracterização da lacase do fungo Trametes cubensis (Mont.) Sacc. 1891." Universidade Federal do Amazonas, 2016. http://tede.ufam.edu.br/handle/tede/5747.
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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
The following interest in fungal enzymes comes about their potential for industrial use, as well as biotechnological research. In this context, the enzyme laccase (EC 1.10.3.2) stand out by its potential use in several industrial applications. Thus, the main goal of this research was to characterize the laccase enzyme produced by the Amazonian fungus Trametes cubensis. The T. cubensis strain was collected in Tefé National Forest (FLONA) and the enzymatic activity was determined from the submerged and semi-solid fermentation. As substrate, sawdust of the wood of Simarouba amara and sugarcane bagasse was tested. As inductors, copper sulfate, “ABTS” and mineral medium were used. The laccase was purified by means of ion exchange chromotography and characterized by mass (SDS-PAGE and zymogram) and determined kinetic parameters Km and Vmax. The most expressive laccase activity occurred in the medium with substrate of Simarouba amara (marupá) with 184 U / mL. The yield was 40% and purification factor of 1.5, with Vmax and Km of 33.33 μmol.L-1 6.66 mM, respectively. The becoming laccase from Trametes cubensis has an apparent molecular mass of approximately 40 kDa. In this way, from the cultivation of Trametes cubensis, it is possible to obtain laccases, however, the study is still necessary in reference the use of different inductors, looking for a potentialization of this activity.
O crescente interesse pelas enzimas fúngicas vem em função da sua potencialidade para uso industrial, bem como na pesquisa biotecnológica. Neste contexto, a enzima lacase (EC 1.10.3.2) destaca-se pelo seu potencial uso em diversas aplicabilidades industriais. Assim, o objetivo dessa pesquisa foi caracterizar a enzima lacase produzida pelo fungo amazônico Trametes cubensis. A cepa de T. cubensis foi coletada na Floresta Nacional de Tefé (FLONA) e determinada a atividade enzimática a partir da fermentação submersa e semi-sólida. Como substrato testou-se serragem da madeira de Simarouba amara e bagaço-de-cana de açúcar. Como indutores utilizou-se sulfato de cobre, ABTS e meio mineral. A lacase foi purificada por meio de cromotografia de troca iônica e caracterizada quanto à massa (SDS-PAGE e zimograma) e determinados os parâmetros cinéticos Km e Vmax. A atividade de lacase mais expressiva ocorreu no meio com substrato de Simarouba amara (marupá) com 184 U/mL. O rendimento foi de 40% e fator de purificação de 1,5, com Vmax e Km de 33,33 μmol.L-1 6,66 mM, respectivamente. A lacase proveniente de Trametes cubensis apresenta massa molecular aparente de, aproximadamente, 40 kDa. Nesse sentido, a partir do cultivo de Trametes cubensis é possível obter lacases, contudo, estudos ainda são necessários no que se refere ao uso de diferentes indutores, visando uma potencialização dessa atividade.
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Papadaki, Anastasia A. "Pseudoperonospora cubensis development under differentiated nitrogen and potassium fertilization of Cucumis sativus." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/4460.
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Cucumber (Cucumis sativus) is one of the most economically important vegetable crops worldwide and downy mildew caused by Pseudoperonospora cubensis is considered among the most destructive diseases that attack this plant. Although the effect of mineral nutrition on plant diseases for various crops has been studied, there is practically none on cucumbers. The overall objective of this study were (a) to investigate the effect of increasing inoculum concentrations of P. cubensis on downy mildew emergence on different aged cucumber leaves (b) to examine the effect of various N and K concentrations in the fertilization solution on the disease development and the leaf surface (c) to study the potential interaction of these two essential nutrients in relation with the application of a fungicide used for downy mildew control (d) to determine the disease progress with time (e) to investigate the nutritional status of cucumber tissues and substrate. A range of greenhouse experiments were conducted. Cucumbers were grown under six K (200, 300, 400, 500, 600, 700 ppm) and six N (100, 200, 300, 400, 500 and 600 ppm) fertilization regimes, in two randomized block experiments respectively. Two factorial designs, one with three levels of spore concentrations and two leaf ages and the other with two N and three K levels plus fungicide treatments were also established. Cucumber plants (Cucumis sativus L. cv. Knossou) susceptible to downy mildew were artificially inoculated with P. cubensis. Disease was digitally assessed. Statistical analysis of the obtained data indicated that the pathogen attacked leaves regardless of age. The lesion area was significantly increased with increasing spore content at low disease pressure. N concentration of 300 ppm had a positive effect on the leaf area when compared with the lower N rates. A concentration of 400 ppm K resulted in a marked increase in leaf area in relation to the other treatments although the differences were not statistically significant (P=0.05). There were indications that downy mildew was significantly decreased on the plants grown in 300 ppm N, 300 and 400 ppm K. However, N and K interaction was observed for leaf and lesion area. Thus, inhibition of infection was recorded with increasing K levels only at low N rates. The best combination for disease limitation was 200 ppm N and 400ppm K, which was found to be comparable with the fungicide used. The disease progress for downy mildew followed a cubic curve in all cases (N and K fertilization treatments, fungicide application). The importance of leaf and soil nutrient status on infection and leaf area index was also noted.
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Duff, Christopher. "Codage d'automates et théorie des cubes intersectants." Phd thesis, Grenoble INPG, 1991. http://tel.archives-ouvertes.fr/tel-00339918.
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Cette thèse propose une methode de codage optimise d'automate synchrone dans un environnement du type compilateur de silicium. Dans une première partie, on recherche sur le graphe d'état des situations prédictives de minimisation des équations des variables internes et des sorties. Ceci définit des contraintes sur le codage en terme d'une liste de groupes d'adjacence d'états a immerger sur des faces ou cubes de l'hypercube. Dans une deuxième partie le codage est réalisé en satisfaisant au mieux ces affectations de faces et leurs intersections. Les principes de base de cette approche sont les suivants: (i) pour la première phase, la recherche de situations prédictives de minimisation est fondée sur la théorie des paires de partition de Hartmannis. Les situations sont recherchées entrée par entrée; cette approche locale permettra de faire face aux grandes complexités; remarquons que le codage des entrées n'est pas aborde. La priorité est donnée aux fusions potentielles de monômes dans les équations. On ne recherchera pas de façon indifférenciée comme dans d'autres approches (mustang) toutes les minimisations possibles incluant les factorisations. En effet, il est raisonnablement estime que seule la fusion de monômes assure un gain de surface et en connectique; (ii) pour la deuxième phase, les techniques d'immersion dans l'hypercube seront très sophistiquées. Elles reprendront une représentation de l'hypercube par le treillis de l'ensemble des parties de n éléments. Pour résoudre les problèmes des contraintes intersectantes, c'est-a-dire des contraintes impliquant des sous-ensembles d'états en commun, une théorie dite théorie des cubes intersectant sera proposée. Les résultats de cette thèse ont donne lieu a un logiciel intégré dans le système asyl. Les résultats obtenus en gain de surface sur silicium, de chemin critique et de facteurs de routage sont les meilleurs actuellement connus
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Faucon, Timothée. "Segmentation morphologique et topologique de cubes sismiques." Phd thesis, École Nationale Supérieure des Mines de Paris, 2007. http://pastel.archives-ouvertes.fr/pastel-00003029.
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Dans un contexte d'exploration et d'exploitation pétrolières, le traitement des données acquises par sismique réflexion requiert une analyse structurale à des fins de modélisation. Cette analyse passe par une phase d'extraction des structures horizontales représentant les empilements géologiques. Les techniques actuelles nécessitent beaucoup de temps et l'attention quasi permanente d'un spécialiste pour réaliser et valider cette opération effectuée structure par structure. De plus, la quantité de données sismiques augmentant rapidement avec l'évolution des techniques d'acquisition, leur traitement représente une charge de travail de plus en plus importante. Dans cette thèse, nous nous proposons d'alléger la phase d'extraction des structures horizontales en réalisant une segmentation presque automatique de ces dernières à l'aide d'outils basés sur des techniques morphologiques et topologiques. Nous présentons également quelques applications s'appuyant sur les structures que nous avons extraites. Ces applications facilitent l'analyse des données 3D en proposant de nouvelles méthodes de calcul d'attributs sismiques à partir des données d'amplitude.
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Duff, Christopher Saucier Gabrièle Mossière Jacques. "Codage d'automates et théorie des cubes intersectants." S.l. : Université Grenoble 1, 2008. http://tel.archives-ouvertes.fr/tel-00339918.
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Vestli, Snorre Nilssen. "Computation of prime cubes of a complex boolean function based on BDDs - continuation on probability of time unfolded prime cubes." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22712.
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With decreasing feature size and increasing complexity of integrated circuits, effective tools for verification and testing are in high demand. When testing large and complex state machines, effective tools for calculating probabilities of future states are often needed.The PState program calculates these with an adapted form of Binary Desicion Diagrams. This project is part of an effort to extend this to search for functions to reach these states by extracting prime cube covers of these BDDs.This report documents my work with the PState program, the adaptation of the cube extraction algorithm, and attempting to unfold the computation over several cycles of a state machine, the problems encountered, and outlines possible ways to solve these challenges.
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Van, Heerden Schalk Willem. "Studies on Cryphonectria cubensis in South Africa with special reference to mycovirus infection." Thesis, Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-08132008-115331.
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Tlatlik, Max Lukas. "Volume rendering with Marching cubes and async compute." Thesis, Blekinge Tekniska Högskola, Institutionen för datavetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-18315.
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With the addition of the compute shader stage for GPGPU hardware it has becomepossible to run CPU like programs on modern GPU hardware. The greatest benefit can be seen for algorithms that are of highly parallel nature and in the case of volume rendering the Marching cubes algorithm makes for a great candidate due to its simplicity and parallel nature. For this thesis the Marching cubes algorithm was implemented on a compute shader and used in a DirectX 12 framework to determine if GPU frametime performance can be improved by executing the compute command queue parallell to the graphics command queue. Results from performance benchmarks show that a gain is present for each benchmarked configuration and the largest gains are seen for smaller workloads with up to 52%. This information could therefore prove useful for game developers who want to improve framerates or decrease development time but also in other fields such as volume rendering for medical images.
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RODRIGUES, LIVIA COUTO RUBACK. "LDC MEDIATOR: A MEDIATOR FOR LINKED DATA CUBES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24859@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Um banco de dados estatístico consiste de um conjunto de observações feitas em pontos de um espaço lógico, e, muitas vezes, são organizados como cubos de dados. A definição adequada de cubos de dados, em especial de suas dimensões, ajuda a processar as suas observações e, mais importante, ajuda a combinar observações de cubos de dados diferentes. Neste contexto, os princípios de dados interligados podem ser proveitosamente aplicados à definição de cubos de dados, oferecendo uma estratégia para fornecer a semântica das dimensões, incluindo seus valores. Este trabalho introduz uma arquitetura de mediação para auxiliar no consumo de cubos de dados, expostos como triplas RDF e armazenados em bancos de dados relacionais. Os cubos de dados são descritos em um catálogo usando vocabulários padronizados e são acessados por métodos HTTP usando os princípios de REST. Portanto, este trabalho busca tirar proveito tanto dos princípios de dados interligados quanto dos princípios de REST para descrever e consumir os cubos de dados interligados de forma simples e eficiente.
A statistical data set comprises a collection of observations made at some points across a logical space and is often organized as what is called a data cube. The proper definition of the data cubes, especially of their dimensions, helps to process the observations and, more importantly, helps to combine observations from different data cubes. In this context, the Linked Data Principles can be profitably applied to the definition of data cubes, in the sense that the principles offer a strategy to provide the missing semantics of the dimensions, including their values. This work introduces a mediation architecture to help consume linked data cubes, exposed as RDF triples, but stored in relational databases. The data cubes are described in a catalogue using standardized vocabularies and are accessed by HTTP methods using REST principles. Therefore, this work aims at taking advantage of both Linked Data and REST principles in order to describe and consume linked data cubes in a simple but efficient way.
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Andersson, Patrik, and Sakarias Johansson. "Rendering with Marching Cubes, looking at Hybrid Solutions." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-4955.
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Marching Cubes is a rendering technique that has many advantages for a lot of areas. It is a technique for representing scalar fields as a three-dimensional mesh. It is used for geographical applications as well as scientific ones, mainly in the medical industry to visually render medical data of the human body. But it's also an interesting technique to explore for the usage in computer games or other real-time applications since it can create some really interesting rendering. The main focus in this paper is to present a novel hybrid solution using marching cubes and heightmaps to render terrain; moreover, to find if it’s suitable for real-time applications. The paper will follow a theoretical approach as well as an implementational one on the hybrid solution. The results across several tests for different scenarios show that the hybrid solution works well for today's real-time applications using a modern graphics card and CPU (Central Processing Unit).
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Khoshtaghaza, Mohammad Hadi. "Hydrothermal characteristics and quality of alfalfa cubes during transport." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq23947.pdf.
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Lu, Xuebin. "Fast computation of sparse data cubes in its applications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0009/MQ61455.pdf.
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McHugh, Rosemarie. "Intégration de la structure matricielle dans les cubes spatiaux." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25758/25758.pdf.
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Dans le monde de la géomatique, la fin des années 1990 a été marquée par l’arrivée de nouvelles solutions décisionnelles, nommées SOLAP. Les outils SOLAP fournissent des moyens efficaces pour facilement explorer et analyser des données spatiales. Les capacités spatiales actuelles de ces outils permettent de représenter cartographiquement les phénomènes et de naviguer dans les différents niveaux de détails. Ces fonctionnalités permettent de mieux comprendre les phénomènes, leur distribution et/ou leurs interrelations, ce qui améliore le processus de découverte de connaissances. Toutefois, leurs capacités en termes d’analyses spatiales interactives sont actuellement limitées. Cette limite est principalement due à l’unique utilisation de la structure de données géométrique vectorielle. Dans les systèmes d’information géographique (SIG), la structure de données matricielle offre une alternative très intéressante au vectoriel pour effectuer certaines analyses spatiales. Nous pensons qu’elle pourrait offrir une alternative intéressante également pour les outils SOLAP. Toutefois, il n’existe aucune approche permettant son exploitation dans de tels outils. Ce projet de maîtrise vise ainsi à définir un cadre théorique permettant l’intégration de données matricielles dans les SOLAP. Nous définissons les concepts fondamentaux permettant l’intégration du matriciel dans les cubes de données spatiaux. Nous présentons ensuite quelques expérimentations qui ont permis de les tester et finalement nous initions le potentiel du matriciel pour l’analyse spatiale dans les outils SOLAP.
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Pitarch, Yoann. "Résumé de Flots de Données : motifs, Cubes et Hiérarchies." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20051/document.
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L'explosion du volume de données disponibles due au développement des technologies de l'information et de la communication a démocratisé les flots qui peuvent être définis comme des séquences non bornées de données très précises et circulant à grande vitesse. Les stocker intégralement est par définition impossible. Il est alors essentiel de proposer des techniques de résumé permettant une analyse a posteriori de cet historique. En outre, un grand nombre de flots de données présentent un caractère multidimensionnel et multiniveaux que très peu d'approches existantes exploitent. Ainsi, l'objectif de ces travaux est de proposer des méthodes de résumé exploitant ces spécificités multidimensionnelles et applicables dans un contexte dynamique. Nous nous intéressons à l'adaptation des techniques OLAP (On Line Analytical Processing ) et plus particulièrement, à l'exploitation des hiérarchies de données pour réaliser cette tâche. Pour aborder cette problématique, nous avons mis en place trois angles d'attaque. Tout d'abord, après avoir discuté et mis en évidence le manque de solutions satisfaisantes, nous proposons deux approches permettant de construire un cube de données alimenté par un flot. Le deuxième angle d'attaque concerne le couplage des approches d'extractions de motifs fréquents (itemsets et séquences) et l'utilisation des hiérarchies pour produire un résumé conservant les tendances d'un flot. Enfin, les catégories de hiérarchies existantes ne permettent pas d'exploiter les connaissances expertes dans le processus de généralisation. Nous pallions ce manque en définissant une nouvelle catégorie de hiérarchies, dites contextuelles, et en proposant une modélisation conceptuelle, graphique et logique d'un entrepôt de données intégrant ces hiérarchies contextuelles. Cette thèse s'inscrivant dans un projet ANR (MIDAS), une plateforme de démonstration intégrant les principales approches de résumé a été mise au point. En outre, la présence de partenaires industriels tels que Orange Labs ou EDF RD dans le projet a permis de confronter nos approches à des jeux de données réellesDue to the rapid increase of information and communication technologies, the amount of generated and available data exploded and a new kind of data, the stream data, appeared. One possible and common definition of data stream is an unbounded sequence of very precise data incoming at an high rate. Thus, it is impossible to store such a stream to perform a posteriori analysis. Moreover, more and more data streams concern multidimensional and multilevel data and very few approaches tackle these specificities. Thus, in this work, we proposed some practical and efficient solutions to deal with such particular data in a dynamic context. More specifically, we were interested in adapting OLAP (On Line Analytical Processing ) and hierarchy techniques to build relevant summaries of the data. First, after describing and discussing existent similar approaches, we have proposed two solutions to build more efficiently data cube on stream data. Second, we were interested in combining frequent patterns and the use of hierarchies to build a summary based on the main trends of the stream. Third, even if it exists a lot of types of hierarchies in the literature, none of them integrates the expert knowledge during the generalization phase. However, such an integration could be very relevant to build semantically richer summaries. We tackled this issue and have proposed a new type of hierarchies, namely the contextual hierarchies. We provide with this new type of hierarchies a new conceptual, graphical and logical data warehouse model, namely the contextual data warehouse. Finally, since this work was founded by the ANR through the MIDAS project and thus, we had evaluated our approaches on real datasets provided by the industrial partners of this project (e.g., Orange Labs or EDF R&D)
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Harvey, John Andrew 1975. "Blinking cubes : a method for polygon-based scene reconstruction." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/49661.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 50-51).
by John Andrew Harvey.
S.B.and M.Eng.
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Tanner, Michael. "BOR2G : Building Optimal Regularised Reconstructions with GPUs (in cubes)." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:1928c996-d913-4d7e-8ca5-cf247f90aa0f.
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Robots require high-quality maps - internal representations of their operating workspace - to localise, path plan, and perceive their environment. Until recently, these maps were restricted to sparse, 2D representations due to computational, memory, and sensor limitations. With the widespread adoption of high-quality sensors and graphics processors for parallel processing, these restrictions no longer apply: dense 3D maps are feasible to compute in real time (i.e., at the input sensor's frame rate). This thesis presents the theory and system to create large-scale dense 3D maps (i.e., reconstruct continuous surface models) using only sensors found on modern autonomous automobiles: 2D laser, 3D laser, and cameras. In contrast to active RGB-D cameras, passive cameras produce noisy surface observations and must be regularised in both 2D and 3D to create accurate reconstructions. Unfortunately, straight-forward application of 3D regularisation causes undesired surface interpolation and extrapolation in regions unexplored by the robot. We propose a method to overcome this challenge by informing the regulariser of the specific subsets of 3D surfaces upon which to operate. When combined with a compressed voxel grid data structure, we demonstrate our system fusing data from both laser and camera sensors to reconstruct 7.3 km of urban environments. We evaluate the quantitative performance of our proposed method through the use of synthetic and real-world datasets - including datasets from Stanford's Burghers of Calais, University of Oxford's RobotCar, University of Oxford's Dense Reconstruction, and Karlsruhe Institute of Technology's KITTI - compared to ground-truth laser data. With only stereo camera inputs, our regulariser reduces the 3D reconstruction metric error between 27% to 36% with a final median accuracy ranging between 4 cm to 8 cm. Furthermore, by augmenting our system with object detection, we remove ephemeral objects (e.g., automobiles, bicycles, and pedestrians) from the input sensor data and target our regulariser to interpolate the occluded urban surfaces. Augmented with Kernel Conditional Density Estimation, our regulariser creates reconstructions with median errors between 5.64 cm and 9.24 cm. Finally, we present a machine-learning pipeline that learns, in an automatic fashion, to recognise the errors in dense reconstructions. Our system trains on image and laser data from a 3.8 km urban sequence. Using a separate 2.2 km urban sequence, our pipeline consistently identifies error-prone regions in the image-based dense reconstruction.
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LI, XIU-ZHU, and 李秀珠. "Variation of fusarium oxysporum f. sp. cubense." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/86573843248442459285.
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Liu, En-Tzu, and 劉恩慈. "Analysis of Fusarium oxysporum f. sp. cubense Using Random." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/09340140445237594035.
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碩士國立中興大學
植物病理學系
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英 文 摘 要 ABSTRACT Fusarium wilt of banana, the so- called Panama disease, caused by Fusarium oxysporum Schlechtend.:Fr. f. sp. cubense (E.F. Smith) W.C. Snyder & H.N. Hansen (Foc). In 1890, the outbreak of this disease in Panama almost completely destroyed the export trade of banana. Foc is distribute worldwide and is difficult to control in agricultural practice except planting wilt-resistant banana hybrids. Panama disease is a serious threat to banana production in the whole world. In 1967, the suspected Fusarium-wilted of banana was discovered in Pingtung, Taiwam, and this disease seriously destroyed the banana export industry there after in Taiwan. Since banana is propagated by asexual plantlets, in order to control the soilborne Panama disease, it is necessary to use health banana plantlets for production. Hence, the development of a fast detect Foc in banana plantlet is essential for rapid screening of health banana plantlets. In this study, random amplified polymorphic DNA (RAPD) analysis was first used to develop a rapid detection method for Foc. Next, specific primers for polymerase chain reaction (PCR) was designed for quick and accurate detection of Foc pathogen. The individually purified DNA from mycelia of fifteen isolates of Foc, fifteen F. oxysporum (Fo) isolates from ten species of different hosts and one other Fusarium sp. was used for RAPD and PCR analyses. The DNA sample from healthy banana tissue and three kinds of non-Fusarium pathogens pathogens were also used as control. Forty-four 8 to 15 nt of short random primers were used for analysis of the aboved DNA samples. A specific 400-bp fragment was amplified from DNA of 14 Foc and another Fo (Fo-L1) isolated from anoectochilus using OPA-02 (5’-TGCCGAGCTG-3’) primer. This 400-bp fragment (OPA02400) obtained from Foc samples was cloned and used as probe for Southern blot analysis. The OPA02400 probe could identify the specific 400-bp fragment amplified from the DNA samples of forteen Foc and Fo-L1. The sequence of OPA02400 showed no similarity to any sequence deposited in GenBank. The OPA02400 sequence was used to design two forward and reverse specific primers: OPA02400A1 (5’-CAGGGGATGTATGAGGAGGCT-3’)、OPA02400A2 (5’-CGGTACTTGCTGTGCGGGGA-3’)、OPA02400S1 (5’-CAGCTATGACAAGAACACCAGA-3’) and OPA02400S2 (5’-GTGACAGCGTCGTCTAGTTCC -3’). The results suggested that the OPA02400A1/OPA02400S2 and OPA02400A2/OPA02400S2 primer pairs could amplify specific fragments only in the 15 Foc and Fo-L1 DNA samples under proper PCR conditions, and the specificity was further confirmed by Southern blot analysis.
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Pan, Manjing. "The inhibition of Fusarium oxysporum f.sp. cubense race 4 by Burkholderia cepacia." Thesis, 1997. http://hdl.handle.net/10413/10296.
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Inhibition of Fusarium oxysporum f. sp. cubense race 4 by Burkholderia cepacia was evident when grown on various media (TSA, PDA, PSA, YM, KMB, PPM, NYGA, LA) with different carbon sources and under various pH and temperature
conditions. In addition, B. cepacia was able to inhibit several fungal pathogens in vitro.
Antagonism of B. cepacia against F. oxysporum f. sp. cubense occured at high levels of Fe³+, which may suggest that antagonism by B. cepacia did not involve siderophore production. Thin layer chromatogram (TLC) examination showed
that B. cepacia produced several substances, one of which had similar R[f] value
to that described for pyrrolnitrin. Cell-free supernatant of a 4-day culture of 6. cepacia was applied to an Amberlite XAD-2 column and inhibitory activity co-eluted
with the 95% methanol (pH 9.5) fraction. The concentrated activated
fractions showed inhibitory activity against F. oxysporum f. sp. cubense.
A GC-MS chromatogram indicated numerous components in the antifungal
extracts. The only compound identified in the Wiley 138 library, was 1,2-
Benzenedicarboxylic acid, bis (2-Ethylhexyl) ester.
Observations by light microscopy indicated that B. cepacia inhibited spore
germination in F. oxysporum f. sp. cubense race 4 and retarded the mycelial
growth. The interaction between the endophytic bacterium, B. cepacia and F.
oxysporum f. sp. cubense race 4 was investigated with aid of scanning and
transmission electron microscopy. This demonstrated that the bacterium was
able to colonize the surface of hypha and macrospore of F. oxysporum f. sp.
cubense. Mycelial deformation, terminal and/or intercalary swelling were evident.
At later stages, hyphae of F. oxysporum f.sp. cubense, colonized by B. cepacia, were found to have collapsed. Further studies in vivo confirmed that B. cepacia
colonized the hypha of F. oxysporum f. sp. cubense which had invaded banana
roots. TEM observation showed that in the banana plant B. cepacia was closely
associated with the healthy banana roots and a matrix was frequently found to
be present between the bacterium and the plant surface. In addition, B. cepacia exists mainly in the intercellular space of the banana roots.
UV irradiation treatment of B. cepacia resulted in a mutant that had lost
inhibitory activity against F. oxysporum f. sp. cubense on TSA agar.
Transposon mutagenesis of B. cepacia was performed by Tn5 insertion. Six
mutants which had lost or had reduced inhibitory activity against F. oxysporum
f. sp. cubense were generated. These mutants showed no inhibitory zones on
TSA medium in the presence of the fungus. It was observed that one mutants.
cepacia :: Tn5-188 appeared to lose the ability to colonize the fungal hypha,
whilst a different mutant B. cepacia ::Tn5 - 217 was still able to colonize the
fungal hyphae. TLC analyses showed that there was a decrease in antibiotic
production in mutants B. cepacia :: Tn5 - 217 and B. cepacia - UV - 34,
compared with the wild type. GC- MS analyses showed that there was no
evidence of the peaks at 14.62 minutes, 20.0 minutes and 20.46 minutes in
both chromatograms of mutants B. cepacia :: Tn5 -217 and 8. cepacia -UV -
34, compared with the wild type B. cepacia.
No PCR products were detected using primers that were developed from
sequences within the biosynthetic loci for Phi of P.fluorescens Q2-87(GenBank accession no. U41818) and PCA of P. fluorescens 2-79 (GeneBank no. L48616). Colony hybridization suggested that genomic DNA from B. cepacia
could contain both Phi- and PCA probes. It was found that hybridization of
genomic DNA digested with Cla-I of B. cepaca with Phl2a probe only occurred
at low stringency. A hybridization signal was detected from a Cla-l fragment of approximately 2800bp.Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.