83 research outputs found

    Interval valued intuitionistic fuzzy evaluations for analysis of a student's knowledge in university e-learning courses

    Full text link
    © The Korean Institute of Intelligent Systems. In the paper a method is proposed for evaluation of the students' knowledge obtained in the university e-learning courses and an evaluation of the whole student class. For the assessment of the student's solution of the respective assessment units the theory of intuitionistic fuzzy sets is used, while for the class evaluation, interval valued intuitionistic fuzzy sets is used. The obtained intuitionistic fuzzy estimations reflect the degree of each student's good or poor performances, for each assessment unit. The interval valued intuitionistic fuzzy evaluations are based on the separate student's evaluations. We also consider a degree of uncertainty that represents such cases wherein the student is currently unable to solve the problem. The method presented here provides the possibility for the algorithmization of the process of forming the student's evaluations

    Resistência a Septoria lycopersici em espécies de Solanum (Secção Lycopersicon) e em progênies de S. lycopersicum × S. peruvianum

    Get PDF
    Septoria leaf spot (Septoria lycopersici) is one of the major fungal diseases of tomatoes (Solanum lycopersicum) in tropical and subtropical regions with humid climates and/or in areas cultivated under sprinkler irrigation systems. Sources of resistance have been found in accessions of Solanum (section Lycopersicon) species. However, many of the described sources are not effective under Brazilian conditions. The objective of this work was to evaluate wild and cultivated Solanum (section Lycopersicon) germplasm to S. lycopersici isolates. A collection of 124 accessions was initially evaluated under greenhouse conditions. Ten accessions were highly resistance (HR), whereas 33 were classified as having a resistant (R) response to S. lycopersici isolates. Field evaluation was also conducted with a sub-set of accessions identified as either HR or R in the greenhouse experiment. This field evaluation confirmed greenhouse tests and indicated the presence of some potential sources of rate-reducing resistance. One highly resistant and eight resistant S. habrochaites accessions were identified as being resistant under both conditions, confirming that this wild species is one of the most promising sources of resistance to S. lycopersici. Five new sources with high levels of resistance were found in S. peruvianum accessions (PI-306811, CNPH-1036, LA-1910, LA-1984 and LA-2744). One accession derived from an interspecific cross between S. lycopersicum and S. peruvianum was also found to be highly resistant and might be useful to introgress resistance factors from this wild species into cultivated tomato germplasm. However, additional breeding efforts will be necessary to introgress into the cultivated tomato the resistance factors identified in other S. peruvianum accessions due to the presence of natural crossing barriers between the two species.A mancha-de-septória (Septoria lycopersici) é importante doença fúngica do tomateiro (Solanum lycopersicum) em áreas tropicais e subtropicais com alta umidade ou quando esta hortaliça é cultivada sob irrigação por aspersão. Fontes de resistência têm sido encontradas em germoplasma de Solanum (secção Lycopersicon). No entanto, muitas das fontes descritas não funcionam nas condições brasileiras. Avaliou-se uma coleção de germoplasma de tomate cultivado e selvagem (Solanum secção Lycopersicon) visando identificar novas fontes de elevada resistência. Uma coleção de 124 acessos foi inicialmente avaliada sob condições de casa de vegetação. Somente dez acessos foram classificados como altamente resistentes e 33 foram classificados como resistentes. Um ensaio de campo foi também conduzido com um subconjunto de acessos promissores identificados no primeiro experimento. Foi confirmada a resposta da maioria dos acessos avaliados em casa de vegetação e indicou a presença de fontes de resistência capazes de reduzir a taxa de progresso da doença. Um acesso de S. habrochaites com elevada resistência e oito acessos resistentes foram identificados, confirmando que esta espécie representa uma das mais promissoras fontes de genes de resistência a S. lycopersici. Cinco novas fontes com elevados níveis de resistência foram identificadas em acessos da espécie S. peruvianum (PI-306811, CNPH-1036, LA-1910, LA-1984 e LA-2744). Um acesso, derivado de cruzamento interespecífico entre S. lycopersicum e S. peruvianum também mostrou-se altamente resistente e poderá ser útil na introgressão deste(s) gene(s) em germoplasma de tomateiro cultivado. No entanto, esforços adicionais de melhoramento serão necessários para transferir para o tomateiro cultivado os fatores de resistência identificados em outros acessos de S. peruvianum, uma vez que existem barreiras naturais de cruzamentos entre estas duas espécies

    A User's Guide to the Encyclopedia of DNA Elements (ENCODE)

    Get PDF
    The mission of the Encyclopedia of DNA Elements (ENCODE) Project is to enable the scientific and medical communities to interpret the human genome sequence and apply it to understand human biology and improve health. The ENCODE Consortium is integrating multiple technologies and approaches in a collective effort to discover and define the functional elements encoded in the human genome, including genes, transcripts, and transcriptional regulatory regions, together with their attendant chromatin states and DNA methylation patterns. In the process, standards to ensure high-quality data have been implemented, and novel algorithms have been developed to facilitate analysis. Data and derived results are made available through a freely accessible database. Here we provide an overview of the project and the resources it is generating and illustrate the application of ENCODE data to interpret the human genome.National Human Genome Research Institute (U.S.)National Institutes of Health (U.S.

    Quorum sensing:Implications on rhamnolipid biosurfactant production

    Get PDF

    Potential therapeutic applications of microbial surface-activecompounds

    Get PDF
    Numerous investigations of microbial surface-active compounds or biosurfactants over the past two decades have led to the discovery of many interesting physicochemical and biological properties including antimicrobial, anti-biofilm and therapeutic among many other pharmaceutical and medical applications. Microbial control and inhibition strategies involving the use of antibiotics are becoming continually challenged due to the emergence of resistant strains mostly embedded within biofilm formations that are difficult to eradicate. Different aspects of antimicrobial and anti-biofilm control are becoming issues of increasing importance in clinical, hygiene, therapeutic and other applications. Biosurfactants research has resulted in increasing interest into their ability to inhibit microbial activity and disperse microbial biofilms in addition to being mostly nontoxic and stable at extremes conditions. Some biosurfactants are now in use in clinical, food and environmental fields, whilst others remain under investigation and development. The dispersal properties of biosurfactants have been shown to rival that of conventional inhibitory agents against bacterial, fungal and yeast biofilms as well as viral membrane structures. This presents them as potential candidates for future uses in new generations of antimicrobial agents or as adjuvants to other antibiotics and use as preservatives for microbial suppression and eradication strategies

    Rhamnolipids: diversity of structures, microbial origins and roles

    Get PDF
    Rhamnolipids are glycolipidic biosurfactants produced by various bacterial species. They were initially found as exoproducts of the opportunistic pathogen Pseudomonas aeruginosa and described as a mixture of four congeners: α-L-rhamnopyranosyl-α-L-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate (Rha-Rha-C10-C10), α-L-rhamnopyranosyl-α-L-rhamnopyranosyl-β-hydroxydecanoate (Rha-Rha-C10), as well as their mono-rhamnolipid congeners Rha-C10-C10 and Rha-C10. The development of more sensitive analytical techniques has lead to the further discovery of a wide diversity of rhamnolipid congeners and homologues (about 60) that are produced at different concentrations by various Pseudomonas species and by bacteria belonging to other families, classes, or even phyla. For example, various Burkholderia species have been shown to produce rhamnolipids that have longer alkyl chains than those produced by P. aeruginosa. In P. aeruginosa, three genes, carried on two distinct operons, code for the enzymes responsible for the final steps of rhamnolipid synthesis: one operon carries the rhlAB genes and the other rhlC. Genes highly similar to rhlA, rhlB, and rhlC have also been found in various Burkholderia species but grouped within one putative operon, and they have been shown to be required for rhamnolipid production as well. The exact physiological function of these secondary metabolites is still unclear. Most identified activities are derived from the surface activity, wetting ability, detergency, and other amphipathic-related properties of these molecules. Indeed, rhamnolipids promote the uptake and biodegradation of poorly soluble substrates, act as immune modulators and virulence factors, have antimicrobial activities, and are involved in surface motility and in bacterial biofilm development

    A user's guide to the Encyclopedia of DNA elements (ENCODE)

    Get PDF
    The mission of the Encyclopedia of DNA Elements (ENCODE) Project is to enable the scientific and medical communities to interpret the human genome sequence and apply it to understand human biology and improve health. The ENCODE Consortium is integrating multiple technologies and approaches in a collective effort to discover and define the functional elements encoded in the human genome, including genes, transcripts, and transcriptional regulatory regions, together with their attendant chromatin states and DNA methylation patterns. In the process, standards to ensure high-quality data have been implemented, and novel algorithms have been developed to facilitate analysis. Data and derived results are made available through a freely accessible database. Here we provide an overview of the project and the resources it is generating and illustrate the application of ENCODE data to interpret the human genome
    corecore