951 resultados para Steve Biko
Resumo:
Arsenic (As) accumulation in rice grains is a risk to human health. The mechanism of transfer of As from the shoot into the grain during grain filling is unknown at present. In this study As speciation in the shoot and grains at maturity were examined, and the relationships between phosphorus (P) and As, and silicon (Si) and As were established in a wide range of cultivars grown in As contaminated field trials in Bangladesh and China. No correlations were observed between shoot and grain speciation, with the inorganic form comprising 93.0-97.0% of As in the shoot and 63.0-83.7% in the grains. The percentage of dimethylarsinic acid (DMA) was between 1.4 and 6.6% in the shoot and 14.6 and 37.0% in the grains; however, the concentrations were comparable, ranging from 0.07 to 0.26 mg kg(-1) in the shoots and 0.03 to 0.25 mg kg(-1) in the grains. A positive correlation was observed between shoot As and shoot Si, however, no correlation was observed between shoot Si and grain As. A significant negative correlation was observed between shoot P and grain As concentrations. These results suggest that the translocation of As into the grain from the shoots is potentially using P rather than Si transport mechanisms. The findings also indicate that inorganic As and DMA translocation to the grain differ considerably.
Resumo:
The concentration of arsenic (As) in rice grains has been identified as a risk to human health. The high proportion of inorganic species of As (As(i)) is of particular concern as it is a nonthreshold, class 1 human carcinogen. To be able to breed rice with low grain As, an understanding of genetic variation and the effect of different environments on genetic variation is needed. In this study, 13 cultivars grown at two field sites each in Bangladesh, India, and China are evaluated for grain As. There was a significant site, genotype, and site by genotype interaction for total grain As. Correlations were observed only between sites in Bangladesh and India, not between countries or within the Chinese sites. For seven cultivars the As was speciated which revealed significant effects of site, genotype, and site by genotype interaction for percentage As(i). Breeding low grain As cultivars that will have consistently low grain As and low As(i), over multiple environments using traditional breeding approaches may be difficult, although CT9993-5-10-1-M, Lemont, Azucena, and Te-qing in general had low grain As across the field sites.
Resumo:
For the world's population, rice consumption is a major source of inorganic arsenic (As), a nonthreshold class 1 carcinogen. Reducing the amount of total and inorganic As within the rice grain would reduce the exposure risk. In this study, grain As was measured in 76 cultivars consisting of Bangladeshi landraces, improved Bangladesh Rice Research Institute (BRRI) cultivars, and parents of permanent mapping populations grown in two field sites in Bangladesh, Faridpur and Sonargaon, irrigated with As-contaminated tubewell water. Grain As ranged from 0.16 to 0.74 mg kg(-1) at Faridpur and from 0.07 to 0.28 mg kg(-1) at Sonargaon. Highly significant cultivar differences were detected and a significant correlation (r = 0.802) in the grain As between the two field sites was observed, indicating stable genetic differences in As accumulation. The cultivars with the highest concentration of grain As were the Bangladeshi landraces. Landraces with red bran had significantly more grain As than the cultivars with brown bran. The percent of inorganic As decreased linearly with increasing total As, but genetic variation within this trend was identified. A number of local cultivars with low grain As were identified. Some tropical japonica cultivars with low grain As have the potential to be used in breeding programs and genetic studies aiming to identify genes which decrease grain As.
Resumo:
The mechanisms of arsenic (As) hyperaccumulation in Pteris vittata, the first identified As hyperaccumulator, are unknown. We investigated the interactions of arsenate and phosphate on the uptake and distribution of As and phosphorus (P), and As speciation in P. vittata. In an 18-d hydroponic experiment with varying concentrations of arsenate and phosphate, P. vittata accumulated As in the fronds up to 27,000 mg As kg(-1) dry weight, and the frond As to root As concentration ratio varied between 1.3 and 6.7. Increasing phosphate supply decreased As uptake markedly, with the effect being greater on root As concentration than on shoot As concentration. Increasing arsenate supply decreased the P concentration in the roots, but not in the fronds. Presence of phosphate in the uptake solution decreased arsenate influx markedly, whereas P starvation for 8 d increased the maximum net influx by 2.5-fold. The rate of arsenite uptake was 10% of that for arsenate in the absence of phosphate. Neither P starvation nor the presence of phosphate affected arsenite uptake. Within 8 h, 50% to 78% of the As taken up was distributed to the fronds, with a higher translocation efficiency for arsenite than for arsenate. In fronds, 49% to 94% of the As was extracted with a phosphate buffer (pH 5.6). Speciation analysis using high-performance liquid chromatography-inductively coupled plasma mass spectroscopy showed that >85% of the extracted As was in the form of arsenite, and the remaining mostly as arsenate. We conclude that arsenate is taken up by P. vittata via the phosphate transporters, reduced to arsenite, and sequestered in the fronds primarily as As(III).
Resumo:
OBJECTIVES: The objective of this study was to investigate the relationship between BRCA1 protein expression, as determined by immunohistochemistry, and clinical outcome in uterine serous carcinoma (USC). METHODS: A tissue microarray containing duplicate cores of 73 cases of USC was immunohistochemically stained with mouse anti-BRCA1 (Ab-1) mouse monoclonal (MS110) antibody. The cores were scored in a semiquantitative manner evaluating both the distribution and intensity of nuclear staining. BRCA1 protein expression was correlated with progression-free survival. RESULTS: Seventy-two of 73 cases were assessable, and there was a statistically significant decreased progression-free survival for those cases exhibiting tumor cell nuclei staining of 76% or greater (P = 0.0023). CONCLUSIONS: Our study illustrates that a low level of BRCA1 protein expression is a favorable prognostic indicator in USC, similar to what is observed in high-grade serous ovarian carcinoma. Further studies should focus on the BRCA1 status of USCs at a molecular level and also investigate whether BRCA1 protein expression is associated with response to chemotherapy in USC.
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We examine experiences of collective self-objectification (CSO) (or its failure) among participants in a ‘multicultural’ St Patrick's Day parade. A two-stage interview study was carried out in which 10 parade participants (five each from ethnic majority and minority groups) were interviewed before and after the event. In pre-event interviews, all participants understood the parade as an opportunity to enact social identities, but differed in the category definitions and relations they saw as relevant. Members of the white Irish majority saw the event as being primarily about representing Ireland in a positive, progressive, light, whereas members of minority groups saw it as an opportunity to have their groups' identities and belonging in Ireland recognized by others. Post-event interviews revealed that, for the former group, the event succeeded in giving expression to their relevant category definitions. The latter group, on the other hand, cited features of the event such as inauthentic costume design and a segregated structure as reasons for why the event did not provide the group recognition they sought. The accounts revealed a variety of empowering and disempowering experiences corresponding to the extent of enactment. We consider the implications in terms of CSO, the performative nature of dual identities, as well as the notion of multicultural recognition.
Resumo:
We develop and test a dual pathway model of effervescence - the intensely positive experience of being in a crowd. The model proposes that positive feelings arise when those attending a mass event see each other as sharing a common social identity. This sense of shared identity predicts (a) crowd participants’ ability to enact their valued collective identity, and (b) the intimacy of social relations between crowd members. In turn, both of these are theorized to predict crowd members’ positivity of experience. These ideas are tested using survey data from pilgrims (n = 416) attending the Magh Mela - a month-long Hindu pilgrimage festival in north India. The findings provide clear support for the model.
Resumo:
How does participation in collective activity affect our social identifications and behavior? We investigate this question in a longitudinal questionnaire study conducted at one of the world’s largest collective events – the Magh Mela (a month-long Hindu religious festival in north India). Data gathered from pilgrims and comparable others who did not attend the event show that one month after this mass gathering was over, those who had participated (but not controls) exhibited a heightened social identification as Hindu and increased levels of religious activity (e.g., performing prayer rituals). Additional data gathered from the pilgrim respondents during the festival show that the pilgrims’ perceptions of sharing a common identity with other pilgrims, and of being able to enact their social identity in this event, predicted these outcomes.
Resumo:
Full length critical peer review article about House at Bogwest, which was the winner of the 2012 RIAI Best House award, by architect Emmett Scanlon. Photographs by Alice Clancy. Photographs and plans describing House at Bogwest.
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Interview with Steve Larkin examining the architecture of House at Bogwest. Specifically in relation to use of zenithal light. Article text by Rafael Suriani. Includes photographs by Alice Clancy
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House at Bogwest to be included in a guide to contemporary Irish architecture since 1990 published by Gandon Editions and prepared by Sean Antoin O Muiri.
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Feature on House at Bogwest. Includes text by Steve Larkin and Emmet Scanlon. Includes photographs by Alice Clancy and drawings by Steve Larkin.
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All houses selected for exhibition in "Houses of the World 2013" exposition in Ljubljana, Kongresni Trg to be published in the "Houses of the world 2013" by Hise Magazine. House at Bogwest selected for publication and exhibition.