79 resultados para Visual selection
Resumo:
Human respiratory syncytial virus (HRSV) is an important respiratory pathogens among children between zero-five years old. Host immunity and viral genetic variability are important factors that can make vaccine production difficult. In this work, differences between biological clones of HRSV were detected in clinical samples in the absence and presence of serum collected from children in the convalescent phase of the illness and from their biological mothers. Viral clones were selected by plaque assay in the absence and presence of serum and nucleotide sequences of the G2 and F2 genes of HRSV biological clones were compared. One non-synonymous mutation was found in the F gene (Ile5Asn) in one clone of an HRSV-B sample and one non-synonymous mutation was found in the G gene (Ser291Pro) in four clones of the same HRSV-B sample. Only one of these clones was obtained after treatment with the child's serum. In addition, some synonymous mutations were determined in two clones of the HRSV-A samples. In conclusion, it is possible that minor sequences could be selected by host antibodies contributing to the HRSV evolutionary process, hampering the development of an effective vaccine, since we verify the same codon alteration in absence and presence of human sera in individual clones of BR-85 sample.
Resumo:
ABSTRACT We propose a model to explain how contract terms are selected in the presence of a form of economic power: contract power. The orange juice sector is used to illustrate an analysis that demonstrates the effects of contract power on the economic organization of the sector. We define contract power as the ability to exploit contractual gaps or failures of contractual provisions, which are strategically left incomplete. Empirical evidence from content analysis of antitrust documents supports the logic of contract power in the orange juice sector in three forms: avoiding changes to payment methods from weight to solid contents (quality); using information asymmetries to manipulate indexes that calculate the formula of orange prices; and deliberately harvesting oranges late in order to dehydrate the fruit, which consequently reduces weight and price. The paper contributes to understanding the selection of contract terms and the debate about how antitrust offices can deal with this issue.
Resumo:
Devido às transformações ocorridas na adolescência, as indefinições que a acompanham, somadas à deficiência visual, justifica-se um estudo sobre a vivência da sexualidade das adolescentes portadoras de deficiência visual inseridas na sociedade e na comunidade escolar. Foram entrevistadas cinco adolescentes em um Centro de Apoio Pedagógico, com questões que buscaram o conhecimento e a compreensão sobre as causa da sua deficiência visual, composição e orientações familiares, experiência afetivo-sexual e o nível de conhecimento acerca de assuntos relacionados à sexualidade, dentre eles métodos contraceptivos e doenças sexualmente transmissíveis. Os resultados mostram que estas adolescentes apresentam as mesmas características de desenvolvimento da sexualidade da sua faixa etária, embora possuam características individuais. Percebeu-se o desconhecimento sobre métodos contraceptivos e doenças sexualmente transmissíveis com informações superficiais. Torna-se imprescindível que o conhecimento se faça de forma acessível para esta população.
Resumo:
Two populations of the wasp Trypoxylon rogenhoferi Kohl, 1884 from São Carlos and Luís Antônio, State of São Paulo, Brazil, were observed and sampled from May 1999 to February 2001 using trap-nests. This mass-provisioning wasp was used to test some aspects of optimal sex allocation theory. Both populations fit all the predictions of the models of Green and Brockmann and Grafen. Maternal provisions determined the size of each offspring, and females allocated well-stocked brood cells to daughters, the sex that benefits most being large. This strategy resulted in a difference in size between the sexes. In São Carlos, female weight at emergence was 1.18 times that of males, in Luís Antônio this value was 1.13. The brood cell volume was correlated with both wing length and weight at emergence in both sexes, and the chance that a given brood cell contained a male offspring decreased with increased brood cell volume. In T. rogenhoferi female body size was related to fitness. Larger females were able to collect more mass of spiders per day, the spiders they captured were heavier, and they provisioned more brood cells per day. They also produced larger daughters. For males, no relationship between body size and fitness was found, but the data were scarce. Since the patterns of provisioning were variable among different females in both study sites, it is possible that the females not follow a unique strategy for sex allocation. The sex ratio and/or investment ratio in the São Carlos population was female-biased and in Luís Antônio, male-biased. In spite of the influence of trap-nests diameters on male production in Luís Antônio, there is some evidence that in São Carlos population the local availability of prey and/or lower rate of parasitism may be major forces in determining the observed sex ratio, but further studies are necessary to verify such hypothesis.
Resumo:
Influence of male nutritional conditions on the performance and alimentary selection of wild females of Anastrepha obliqua (Macquart) (Diptera, Tephritidae). The behavior of A. obliqua females is regulated by endogenous and exogenous factors and among these the presence of males. Experiments were carried out to investigate whether the presence of males and their nutritional condition may affect the behavior of self-selection feeding and the performance of A. obliqua females. Females were sorted in groups containing yeast-deprived females and males, and non-yeast-deprived females and males. The females were maintained apart from the males by a transparent plastic screen. Several yeast and sucrose combinations were offered to the females in a single diet block or in separate blocks. Ingestion, egg production, longevity and diet efficiency were determined. The non-yeast-deprived males positively influenced the females performance when the latter were fed with yeast and sucrose in distinct diet blocks. Performance was better in the groups without males and with yeast-deprived males where the females could not select the nutrient proportions (yeast and sucrose in a single diet block).
Resumo:
Several factors influence the selection of oviposition substrates by insects. The aim of the present work was to find answers to the following questions related to the oviposition behavior of Anastrepha obliqua. Can carbohydrates (glucose or sucrose) present in the adult diet have influence on the female preference for an oviposition substrate with similar composition? Can the previous experience with a host containing one of mentioned carbohydrates interfere in further selection of oviposition substrates? The results showed that the kind of carbohydrate present in the adult diet did not affect the female preference for an artificial oviposition substrate, neither when it was presented by itself nor in combination with brewer's yeast. The effect of experience in the oviposition behavior was observed when there was a previous contact with artificial oviposition substrates containing yeast and sucrose. The data are discussed in terms of the behavioral plasticity presented by this species in relation to feeding and oviposition behaviors.
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The choice for suitable places for female mosquitoes to lay eggs is a key-factor for the survival of immature stages (eggs and larvae). This knowledge stands out in importance concerning the control of disease vectors. The selection of a place for oviposition requires a set of chemical, visual, olfactory and tactile cues that interact with the female before laying eggs, helping the localization of adequate sites for oviposition. The present paper presents a bibliographic revision on the main aspects of semiochemicals in regard to mosquitoes' oviposition, aiding the comprehension of their mechanisms and estimation of their potential as a tool for the monitoring and control of the Culicidae.
Resumo:
Egg laying site selection by a host plant specialist leaf miner moth at two intra-plant levels in the northern Chilean Atacama Desert. The spatial distribution of the immature stages of the leaf miner Angelabella tecomae Vargas & Parra, 2005 was determined at two intra-plant levels (shoot and leaflet) on the shrub Tecoma fulva fulva (Cav.) D. Don (Bignoniaceae) in the Azapa valley, northern Chilean Atacama Desert. An aggregated spatial pattern was detected for all the immature stages along the shoot, with an age dependent relative position: eggs and first instar larvae were clumped at apex; second, third and fourth instar larvae were mostly found at intermediate positions; meanwhile the spinning larva and pupa were clumped at basis. This pattern suggests that the females select new, actively growing leaflets for egg laying. At the leaflet level, the immature stages were found more frequently at underside. Furthermore, survivorship was higher for larvae from underside mines. All these results highlight the importance of an accurate selection of egg laying site in the life history of this highly specialized leaf miner. By contrast, eventual wrong choices in the egg laying site selection may be associated with diminished larval survivorship. The importance of the continuous availability of new plant tissue in this highly human modified arid environment is discussed in relation with the observed patterns.
Resumo:
Quase tudo do pouco que sabemos sobre o conhecimento produzido nos chega pelos meios de informação e comunicação. Estes, por sua vez, também constroem imagens do mundo. Imagens para deleitar, entreter, vender, sugerindo o que devemos vestir, comer, aparentar, pensar. Em nossa sociedade contemporânea discute-se a necessidade de uma alfabetização visual, que se expressa em várias designações, como leitura de imagens e compreensão crítica da cultura visual. Freqüentes mudanças de expressões e conceitos dificultam o entendimento dessas propostas para o currículo escolar, assim como a própria definição do professor ou professora que será responsável por esse conhecimento e seu referencial teórico. Este artigo apresenta os conceitos que fundamentam as propostas da leitura de imagens e cultura visual, sinalizando suas proximidades e distâncias. Contrasta alguns referenciais teóricos da antropologia, arte, educação, história, sociologia, e sugere linhas de trabalho em ambientes de aprendizagem para que se possa refletir a permanente formação docente.
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Este trabalho relata a atividade do acesso e do uso das tecnologias de informação e de comunicação (TICs), tendo como sujeito uma pessoa com necessidades educacionais especiais (PNEE) na produção de páginas para a Internet. A atividade permitiu a observação das barreiras e dificuldades enfrentadas e superadas, mediante o uso de ambiente de aprendizagem mediado por computador (AAMC). Foram utilizadas várias alternativas, formas de comunicação, tecnologias adequadas para a realização da atividade proposta, resultando em uma postura de compartilhamento no qual cada um tem muito para cooperar, para doar-se na busca de uma construção coletiva e na superação das limitações, sejam estas físicas e/ou tecnológicas. O artigo aponta que, com a educação e o uso das TICs, é possível promover a inclusão social e digital das PNEEs com limitação visual.
Resumo:
Este artigo ressalta a importância da capacitação de bibliotecários, profissionais da informação, por meio da educação aberta e a distância (EAD) mediada por computador, sendo estes videntes ou pessoas com necessidades educacionais especiais (PNEEs) com limitação visual. Apresenta o curso Bibliotec II, realizado pelo DCI/Fabico/UFRGS, ministrado para bibliotecários e com a participação de dois profissionais PNEEs com limitação visual. Aborda temas relacionados à biblioteca escolar, à educação, à acessibilidade e à inclusão social, digital e profissional das PNEEs, e o bibliotecário como educador, sendo um mediador, junto com os professores e os alunos, no uso das TICs, nos processos de interação, colaboração, cooperação em ambientes virtuais de aprendizagem (AVAs).
Resumo:
The objective of this work was to evaluate the processes of selection in a citrus hybrid population using segregation analysis of RAPD markers. The segregation of 123 RAPD markers between 'Cravo' mandarin (Citrus reticulata Blanco) and 'Pêra' sweet orange (C. sinensis (L.) Osbeck) was analysed in a F1 progeny of 94 hybrids. Genetic composition, diversity, heterozygosity, differences in chromosomal structure and the presence of deleterious recessive genes are discussed based on the segregation ratios obtained. A high percentage of markers had a skeweness of the 1:1 expected segregation ratio in the F1 population. Many markers showed a 3:1 segregation ratio in both varieties and 1:3 in 'Pêra' sweet orange, probably due to directional selection processes. The distribution analysis of the frequencies of the segregant markers in a hybrid population is a simple method which allows a better understanding of the genetics of citrus group.
Resumo:
The objectives of this work were to estimate the genetic and phenotypic parameters and to predict the genetic and genotypic values of the selection candidates obtained from intraspecific crosses in Panicum maximum as well as the performance of the hybrid progeny of the existing and projected crosses. Seventy-nine intraspecific hybrids obtained from artificial crosses among five apomictic and three sexual autotetraploid individuals were evaluated in a clonal test with two replications and ten plants per plot. Green matter yield, total and leaf dry matter yields and leaf percentage were evaluated in five cuts per year during three years. Genetic parameters were estimated and breeding and genotypic values were predicted using the restricted maximum likelihood/best linear unbiased prediction procedure (REML/BLUP). The dominant genetic variance was estimated by adjusting the effect of full-sib families. Low magnitude individual narrow sense heritabilities (0.02-0.05), individual broad sense heritabilities (0.14-0.20) and repeatability measured on an individual basis (0.15-0.21) were obtained. Dominance effects for all evaluated characteristics indicated that breeding strategies that explore heterosis must be adopted. Less than 5% increase in the parameter repeatability was obtained for a three-year evaluation period and may be the criterion to determine the maximum number of years of evaluation to be adopted, without compromising gain per cycle of selection. The identification of hybrid candidates for future cultivars and of those that can be incorporated into the breeding program was based on the genotypic and breeding values, respectively. The prediction of the performance of the hybrid progeny, based on the breeding values of the progenitors, permitted the identification of the best crosses and indicated the best parents to use in crosses.
Resumo:
The objective of this study was to evaluate the efficiency of spatial statistical analysis in the selection of genotypes in a plant breeding program and, particularly, to demonstrate the benefits of the approach when experimental observations are not spatially independent. The basic material of this study was a yield trial of soybean lines, with five check varieties (of fixed effect) and 110 test lines (of random effects), in an augmented block design. The spatial analysis used a random field linear model (RFML), with a covariance function estimated from the residuals of the analysis considering independent errors. Results showed a residual autocorrelation of significant magnitude and extension (range), which allowed a better discrimination among genotypes (increase of the power of statistical tests, reduction in the standard errors of estimates and predictors, and a greater amplitude of predictor values) when the spatial analysis was applied. Furthermore, the spatial analysis led to a different ranking of the genetic materials, in comparison with the non-spatial analysis, and a selection less influenced by local variation effects was obtained.
Resumo:
The objective of this work was to propose a new selection strategy for the initial stages of sugarcane improvement, based on the methodology 'simulated individual BLUP (BLUPIS)', which promotes a dynamic allocation of individuals selected in each full-sib family, using BLUP as a base for both the genotypic effects of the referred families and plot effects. The method proposed applies to single full-sib families or those obtained from unbalanced or balanced diallel crosses, half-sib families and self-pollinated families. BLUPIS indicates the number of individuals to be selected within each family, the total number of clones to be advanced, and the number of families to contribute with selected individuals. Correlation between BLUPIS and true BLUP was 0.96, by method validation. Additionally, BLUPIS allows the identification of which replication contains the best individuals of each family.