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951.
The development of ovarian follicular cells is controlled by multiple circulating and local hormones and factors, including
follicle-stimulating hormone (FSH) and epidermal growth factor (EGF). In this study, the stage-specific effect of EGF on FSH-induced
proliferation of granulosa cells was evaluated in the ovarian follicles of egg-laying chickens. Results showed that EGF and its receptor (EGFR) mRNAs displayed a high expression in granulosa cells from the prehierarchical follicles, including the large white follicle
(LWF) and small yellow follicle (SYF), and thereafter the expression decreased markedly to the stage of the largest preovulatory
follicle. SYF represents a turning point of EGF/EGFR mRNA expression during follicle selection. Subsequently the granulosa cells from SYF were cultured to reveal the mediation
of EGF in FSH action. Cell proliferation was remarkably increased by treatment with either EGF or FSH (0.1–100 ng/ml). This
result was confirmed by elevated proliferating cell nuclear antigen (PCNA) expression and decreased cell apoptosis. Furthermore,
EGF-induced cell proliferation was accompanied by increased mRNA expressions of EGFR, FSH receptor, and the cell cycle-regulating
genes (cyclins D1 and E1, cyclin-dependent kinases 2 and 6) as well as decreased expression of luteinizing hormone receptor
mRNA. However, the EGF or FSH-elicited effect was reversed by simultaneous treatment with an EGFR inhibitor AG1478. In conclusion,
EGF and EGFR expressions manifested stage-specific changes during follicular development and EGF mediated FSH-induced cell
proliferation and retarded cell differentiation in the prehierarchical follicles. These expressions thus stimulated follicular
growth before selection in the egg-laying chicken. 相似文献
952.
Gas-liquid coupling oscillation is a novel approach to reducing the resonant frequency and to elevating the pressure amplitude
of a thermoacoustic engine. If a thermoacoustic engine is used to drive low-frequency pulse tube refrigerators, the frequency
matching between the thermoacoustic engine and the refrigerator plays an important role. Based on an acoustic-electric analogy,
a lumped parameter model is proposed to estimate the resonant frequency of a standing-wave thermoacoustic engine with gas-liquid
coupling oscillation. Furthermore, a simplified lumped parameter model is also developed to reduce the computation complexity.
The resonant frequency dependence on the mean pressure, the gas space volume, and the water column length is computed and
analyzed. The impact of different working gases on the resonant frequency is also discussed. The effectiveness of the models
is validated by comparing the computed results with the experimental data of the gas-liquid coupling oscillation system. An
increase in the mean working pressure can lead to a rise in the resonant frequency, and a lower resonant frequency can be
achieved by elongating the liquid column. In comparison with nitrogen and argon, carbon dioxide can realize a lower frequency
due to a smaller specific heat ratio. 相似文献
953.
There are movements internationally towards curricula that incorporate values and citizenship education. In Australia, this movement has been illustrated with the adoption of a national curriculum in values education. This has arisen from the perceived need for citizens to hold values around the rights and responsibilities of functioning within a democracy. The Making News Today programme has been designed to develop a range of literacies enabling learners, for example, to read the media beyond the interests of the elite. The programme incorporates a journalistic process for television news production for middle school students using laptop and handheld video technologies, with embedded ethics and values education. The article reports on an analysis of the implementation of this programme with middle school students in Australia with reference to student adoption of ethical stances in the journalistic process and the implications for the use of this project in developing ethics, values and citizenship as part of the curriculum process. 相似文献
954.
如果说正义是人类道德交往的基本法则或者维度,那么这也似乎适用于一些教育问题。简而言之,我们需要教育孩子和年轻人正义和公平。然而,这并不是可以仅通过教授正义的理论就能够实现的。因为,正如这篇文章所揭示的那样,这些理论通常涉及到维护正义的准则,即在有些情况下,公民个体不能总是做到如其所期待的那样正义与公平。所以,正义教育更多的是培养正义的美德。从这点出发,本文致力于探究如何借助富有想象力的文学作品来培养正义的美德。 相似文献
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957.
Individual Differences in Childhood Behavior Disorders Associated With Epigenetic Modulation of the Cortisol Receptor Gene
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Mark R. Dadds Caroline Moul David J. Hawes Antonio Mendoza Diaz John Brennan 《Child development》2015,86(5):1311-1320
Behavioral/emotional difficulties in children are the first sign of mental health problems. These problems are however, heterogeneous. A domain that may identify homogenous subgroups is hypothalamic–pituitary–adrenal function. This study tested whether epigenetic regulation of glucocorticoid receptor gene could explain the co‐occurrence of anxiety problems in children with behavior problems. Four‐ to 16‐year‐old clinically referred children (N = 241) were measured for psychiatric symptoms, methylation of target CpG sites in blood or saliva, and morning cortisol levels in those who gave blood. Increased methylation of promoter 1F CpG sites was associated with higher vulnerability to co‐occurring internalizing symptoms and morning cortisol. The results support increasing optimism that epigenetic regulation of key neuroendocrine systems might help explain hitherto unfathomable individual differences in susceptibility to psychiatric symptom profiles. 相似文献
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959.
960.
Dewey and Video Games: From Education through Occupations to Education through Simulations
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David I. Waddington 《Educational theory》2015,65(1):1-20
Critics like Leonard Waks argue that video games are, at best, a dubious substitute for the rich classroom experiences that John Dewey wished to create and that, at worst, they are profoundly miseducative. Using the example of Fate of the World, a climate change simulation game, David Waddington addresses these concerns through a careful demonstration of how video games can recapture some of the lost potential of Dewey's original program of education through occupations. Not only do simulation games realize most of the original goals of education through occupations, but they also solve some of the serious practical problems that Dewey's curriculum generated. Waddington concludes the essay with an analysis of Waks's critiques and some cautionary notes about why it is important to be temperate in our endorsement of educational video gaming. 相似文献