Central-Peak-Soft-Mode, Coupling in Ferroelectric Gd\u3csub\u3e2\u3c/sub\u3e(MoO\u3csub\u3e4\u3c/sub\u3e)\u3csub\u3e3\u3c/sub\u3e

Transmission measurements on Gd2(MoO4)3 in the ( 5-50)-cm-1 region were performed with use of tunable backward-wave oscillator sources (5-30 cm\u3e-1) and a Fourier spectrometer (30-50 cm\u3e-1). The resulting dielectric spectra show an additional low-frequency dispersion which was fitted with a standard central-peak model. Its characteristic relaxation frequency is ~20 cm\u3e-1 and the coupling between the soft mode and central mode increases near the transition temperature. This model also accounts very well for the weak anomaly in the clamped permittivity Ec measured at 63 MHz. The same central mode was used to fit earlier Raman soft-mode spectra. All of these data were fitted with a three-coupled-mode model which revealed that the soft-mode spectrum consists of two strongly coupled bare modes: a higher-frequency mode which softens and carries the entire Raman strength and a lower-frequency mode which is hard (59 cm-1) and Raman inactive. Both of these modes are also coupled to the central mode and this coupling increases sharply near the transition. The relatively large width of the central mode indicates its intrinsic nature and suggests partial disorder near the transition

The landscape of gifted and talented education in England and Wales: How are teachers implementing policy?

This is an Author's Accepted Manuscript of an article published in Research Papers in Education, 27(2), 167-186, 2012, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/02671522.2010.509514.This paper explores the evidence relating to how primary schools are responding to the ‘gifted and talented’ initiative in England and Wales. A questionnaire survey which invited both closed and open-ended responses was carried out with a national sample of primary schools. The survey indicated an increasing proportion of coordinators, compared with a survey carried out in 1996, were identifying their gifted and talented children as well as having associated school policies. However, the survey also highlighted a number of issues which need addressing if the initiative is to achieve its objective of providing the best possible educational opportunities for children. For example, it was found that a significant number of practitioners were not aware of the existence of the National Quality Standards for gifted and talented education, provided by the UK government in 2007, and the subject-specific criteria provided by the UK’s Curriculum Authority for identification and provision have been largely ignored. The process of identifying children to be placed on the ‘gifted and talented’ register seems haphazard and based on pragmatic reasons. Analysis of teachers’ responses also revealed a range of views and theoretical positioning held by them, which have implications for classroom practice. As the ‘gifted and talented’ initiative in the UK is entering a second decade, and yet more significant changes in policy are introduced, pertinent questions need to be raised and given consideration

Adducins Regulate Remodeling of Apical Junctions in Human Epithelial Cells

This article identifies membrane skeleton proteins, adducins, as important regulators of epithelial cell–cell adhesions that promote assembly and antagonize stimulus-induced disassembly of adherens and tight junctions

Friction forces position the neural anlage

During embryonic development, mechanical forces are essential for cellular rearrangements driving tissue morphogenesis. Here, we show that in the early zebrafish embryo, friction forces are generated at the interface between anterior axial mesoderm (prechordal plate, ppl) progenitors migrating towards the animal pole and neurectoderm progenitors moving in the opposite direction towards the vegetal pole of the embryo. These friction forces lead to global rearrangement of cells within the neurectoderm and determine the position of the neural anlage. Using a combination of experiments and simulations, we show that this process depends on hydrodynamic coupling between neurectoderm and ppl as a result of E-cadherin-mediated adhesion between those tissues. Our data thus establish the emergence of friction forces at the interface between moving tissues as a critical force-generating process shaping the embryo

ATP citrate lyase: cloning, heterologous expression and possible implication in root organic acid metabolism and excretion

In order to cope with phosphate deficiency, white lupin produces bottle-brushed like roots, so-called cluster or proteoid roots which are specialized in malate and citrate excretion. Young, developing cluster roots mainly excrete malate whereas mature cluster roots mainly release citrate. Mature proteoid roots excrete four to six times more carboxylates compared with juvenile proteoid roots. Using a cDNA-amplified restriction fragment length polymorphism (AFLP) approach we identified a gene coding for a putative ATP-citrate lyase (ACL) up-regulated in young cluster roots. Cloning of the lupin ACL revealed that plant ACL is constituted by two polypeptides (ACLA and ACLB) encoded by two different genes. This contrasts with the animal ACL, constituted of one polypeptide which covers ACLA and ACLB. The ACL function of the two lupin gene products has been demonstrated by heterologous expression in yeast. Both subunits are required for ACL activity. In lupin cluster roots, our results suggest that ACL activity could be responsible for the switch between malate and citrate excretion in the different developmental stages of cluster roots. In primary roots of lupin and maize, ACL activity was positively correlated with malate exudation. These results show that ACL is implicated in root exudation of organic acids and hence plays a novel role in addition to lipid synthesis. Our results suggest that in addition to lipid biosynthesis, in plants, ACL is implicated in malate excretion