110 resultados para A. P. B.
Resumo:
Size-spectrum theory is used to show that (i) predation mortality is a decreasing function of individual size and proportional to the consumption rate of predators; (ii) adult natural mortality M is proportional to the von Bertalanffy growth constant K; and (iii) productivity rate P/B is proportional to the asymptotic weight W8 -1/3. The constants of proportionality are specified using individual level parameters related to physiology or prey encounter. The derivations demonstrate how traditional fisheries theory can be connected to community ecology. Implications for the use of models for ecosystem-based fisheries management are discussed.
Resumo:
We carried out a yeast two-hybrid screen using a BRCA1 bait composed of amino acids 1 to 1142 and identified BRD7 as a novel binding partner of BRCA1. This interaction was confirmed by coimmunoprecipitation of endogenous BRCA1 and BRD7 in T47D and HEK-293 cells. BRD7 is a bromodomain containing protein, which is a subunit of PBAF-specific Swi/Snf chromatin remodeling complexes. To determine the functional consequences of the BRCA1-BRD7 interaction, we investigated the role of BRD7 in BRCA1-dependent transcription using microarray-based expression profiling. We found that a variety of targets were coordinately regulated by BRCA1 and BRD7, such as estrogen receptor alpha (ERalpha). Depletion of BRD7 or BRCA1 in either T47D or MCF7 cells resulted in loss of expression of ERalpha at both the mRNA and protein level, and this loss of ERalpha was reflected in resistance to the antiestrogen drug fulvestrant. We show that BRD7 is present, along with BRCA1 and Oct-1, on the ESR1 promoter (the gene which encodes ERalpha). Depletion of BRD7 prevented the recruitment of BRCA1 and Oct-1 to the ESR1 promoter; however, it had no effect on the recruitment of the other Swi/Snf subunits BRG1, BAF155, and BAF57 or on RNA polymerase II recruitment. These results support a model whereby the regulation of ERalpha transcription by BRD7 is mediated by its recruitment of BRCA1 and Oct-1 to the ESR1 promoter.
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Beliefs about personhood are understood to be a defining feature of individualism-collectivism (I-C), but they have been insufficiently explored, given the emphasis of research on values and self-construals. We propose the construct of contextualism, referring to beliefs about the importance of context in understanding people, as a facet of cultural collectivism. A brief measure was developed and refined across 19 nations (Study 1: N = 5,241), showing good psychometric properties for cross-cultural use and correlating well at the nation level with other supposed facets and indicators of I-C. In Study 2 (N = 7,623), nation-level contextualism predicted ingroup favoritism, corruption and differential trust of ingroup and outgroup members, while controlling for other facets of I-C, across 34 nations. We conclude that contextualism is an important part of cultural collectivism. This highlights the importance of beliefs alongside values and self-representations, and contributes to a wider understanding of cultural processes.
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Concern with what can explain variation in generalized social trust has led to an abundance of theoretical models. Defining generalized social trust as a belief in human benevolence, we focus on the emancipation theory and social capital theory as well as the ethnic diversity and economic development models of trust. We then determine which dimensions of individuals’ behavior and attitudes as well as of their national context are the most important predictors. Using data from 20 countries that participated in round one of the European Social Survey, we test these models at their respective level of analysis, individual and/or national. Our analysis revealed that individuals’ own trust in the political system as a moral and competent institution was the most important predictor of generalized social trust at the individual level, while a country’s level of affluence was the most important contextual predictor, indicating that different dimensions are significant at the two levels of analysis. This analysis also raised further questions as to the meaning of social capital at the two levels of analysis and the conceptual equivalence of its civic engagement dimension across cultures.
Resumo:
College students (N = 3,435) in 26 cultures reported their perceptions of age-related changes in physical, cognitive, and socioemotional areas of functioning and rated societal views of aging within their culture. There was widespread cross-cultural consensus regarding the expected direction of aging trajectories with (a) perceived declines in societal views of aging, physical attractiveness, the ability to perform everyday tasks, and new learning; (b) perceived increases in wisdom, knowledge, and received respect; and (c) perceived stability in family authority and life satisfaction. Cross-cultural variations in aging perceptions were associated with culture-level indicators of population aging, education levels, values, and national character stereotypes. These associations were stronger for societal views on aging and perceptions of socioemotional changes than for perceptions of physical and cognitive changes. A consideration of culture-level variables also suggested that previously reported differences in aging perceptions between Asian and Western countries may be related to differences in population structure.
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We examined the relationship between Individualism/Collectivism and generalized social trust across 31 European nations participating in the European Social Survey. Using multi-level regression analyses, the current study provides the first empirical investigation of the effects of cultural norms of Individualism/Collectivism on generalized social trust while accounting for individuals' own cultural orientations within the same analysis. The results provide clear support for Yamagishi and Yamagishi (1994) emancipation theory of trust, showing a significant and positive relationship between Individualism/Collectivism and generalized social trust, over and above the effect of a country political history of communism and ethnic heterogeneity. Having controlled for individual effects of Individualism/Collectivism it is clear that the results of the current analysis cannot be reduced to an individual-level explanation, but must be interpreted within the context Of macrosocial processes. We conclude by discussing potential mechanisms that could explain why national individualism is more likely to foster trust among people than collectivism.
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Silicon-on-sapphire (SOS) substrates have been proven to offer significant advantages in the integration of passive and active devices in RF circuits. Germanium on insulator technology is a candidate for future higher performance circuits. Thus the advantages of employing a low loss dielectric substrate other than a silicon-dioxide layer on silicon will be even greater. This paper covers the production of germanium on sapphire (GeOS) substrates by wafer bonding. The quality of the germanium back interface is studied and a tungsten self-aligned gate process MOST process has been developed. High low field mobilities of 450-500 cm2/V-s have been achieved for p-channel MOSTs produced on GeOS substrates. Thick germanium on alumina (GOAL) substrates have also been produced.
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The effect of 3 slaughter weights (85.95 or 105 kg) on performance and carcass traits of 481 pigs in single-gender groups of 13 (18 groups of gilts and 19 groups of intact males) was evaluated. Pigs (39.5 +/- 3.3 kg) were fed a liquid diet 3 times daily in a long trough. The behaviour of pigs slaughtered at 105 kg was recorded at 50, 60 and 70 days after the start of the experiment (5 groups of gilts and 4 groups of intact males). Behaviour (active, inactive, feeding) and posture (standing, lying, dog-sitting) of all pigs was recorded at 5-min intervals for 30 min prior to and 1 h after each feeding event. Slaughtering pigs at 95 kg and 105 kg delayed production by 7 and 16 days, respectively, compared to slaughtering at 85 kg (P0.05). Muscle depth increased with increasing slaughter weight (P
Resumo:
We examined the role of common genetic variation in schizophrenia in a genome-wide association study of substantial size: a stage 1 discovery sample of 21,856 individuals of European ancestry and a stage 2 replication sample of 29,839 independent subjects. The combined stage 1 and 2 analysis yielded genome-wide significant associations with schizophrenia for seven loci, five of which are new (1p21.3, 2q32.3, 8p23.2, 8q21.3 and 10q24.32-q24.33) and two of which have been previously implicated (6p21.32-p22.1 and 18q21.2). The strongest new finding (P = 1.6 x 10(-11)) was with rs1625579 within an intron of a putative primary transcript for MIR137 (microRNA 137), a known regulator of neuronal development. Four other schizophrenia loci achieving genome-wide significance contain predicted targets of MIR137, suggesting MIR137-mediated dysregulation as a previously unknown etiologic mechanism in schizophrenia. In a joint analysis with a bipolar disorder sample (16,374 affected individuals and 14,044 controls), three loci reached genome-wide significance: CACNA1C (rs4765905, P = 7.0 x 10(-9)), ANK3 (rs10994359, P = 2.5 x 10(-8)) and the ITIH3-ITIH4 region (rs2239547, P = 7.8 x 10(-9)).
Resumo:
Background Ten to twenty per cent of breast tumours exhibit a basallike genetic profile and these tumours carry a poor prognosis. Breast tumours which contain germline mutations for BRCA1 commonly exhibit a molecular profile similar to basal breast tumours. BRCA1 is a tumour suppressor gene which is mutated in up to 5–10% of breast cancer cases and is involved in multiple cellular processes including DNA damage control, cell cycle checkpoint control, apoptosis, ubiquitination and transcriptional regulation.<br/><br/>Methods Microarray-based profiling was carried out using the HCC1937EV and HCC1937BR breast cancer cell lines. Basal gene and protein expression levels were analysed by qRT-PCR and western blotting. ChIP analyses were performed and demonstrated that BRCA1 regulates basal gene expression through a transcriptional mechanism involving c-myc.<br/><br/>Results We have previously carried out microarray-based expression profiling to examine differences in gene expression when BRCA1 is reconstituted in BRCA1 mutated HCC1937 breast cancer cells. We observed that p-cadherin and the cytokeratin 5 and cytokeratin 17 genes, which are strongly correlated with the basal phenotype, are differentially expressed when BRCA1 is reconstituted. In addition, qRT-PCR and ChIP analysis of BRCA1 reconstituted cells show that BRCA1 represses the expression of these basal genes by a transcriptional mechanism. Furthermore, abrogation of endogenous BRCA1 protein in the T47D cell line using siRNA results in reexpression of these basal genes, suggesting that BRCA1 expression levels may be important in basal gene expression. We have also demonstrated that BRCA1 is physically associated with the promoter regions of basal genes through an association with c-myc. Consequently, we have confirmed that siRNA inhibition of c-myc in T47D cells results in re-expression of these genes.<br/><br/>Conclusions Our results suggest that BRCA1 is involved in the transcriptional regulation of genes associated with the basal phenotype and that BRCA1 controls basal gene expression through a transcriptional mechanism involving c-myc. Further work is now concentrating on defining the relationship between BRCA1 and basal gene expression and how this may affect clinical responses to breast cancer chemotherapy.
Resumo:
Enantiopure arene cis-tetrahydrodiols of bromobenzene and iodobenzene have been obtained in good yields, from chemoselective hydrogenation (rhodium-graphite) of the corresponding cis-dihydrodiol metabolites. Palladium-catalysed substitution of the halogen, by hydrogen, boron, nitrogen and phosphorus nucleophiles, in the acetonide derivatives, has yielded highly functionalised products for application in synthesis with potential as scaffolds for chiral ligands.