Teacher and child talk in active learning and whole-class contexts : some implications for children from economically less advantaged home backgrounds

This paper reports the experiences of 150 children and six primary teachers when active learning pedagogies were introduced into the first year of primary schools. Although active learning increased the amount of talk between children, those from socio-economically advantaged homes talked more than those from less advantaged homes. Also, individual children experienced very little time engaged in high-quality talk with the teacher, despite the teachers spending over one-third of their time responding to children's needs and interests. Contextual differences, such as the different staffing ratios in schools and pre-schools,may affect how well the benefits of active learning transfer from preschool contexts into primary schools. Policy-makers and teachers should pay particular attention to the implications of this for the education of children from economically less advantaged home backgrounds

π−N\pi-N from an Extended Effective Field Theory

Third order chiral perturbation theory accounts for the $\pi-N$ scattering phase shift data out to energies slightly below the position of the $\Delta$ resonance. The low energy constants are not accurately determined. Explicit inclusion of the $\Delta$ field is favored.Comment: 2 pages latex, working group talk, Chiral Dynamics 2000, Jefferson Lab., VA, July 2000, World Scientific, to be pu

Flavor Singlet Axial Coupling of the Proton - An Updated Analysis

We present a combined analysis of SESAM and TxL data for the flavor singlet axial coupling G_A^1 of the proton, which is very helpful to stabilize the disconnected signals at small quark masses. From connected and disconnected contributions we use the tadpole improved renormalization constant Z_A and obtain G_A^1=0.21(12).Comment: 3 pages, contribution to LATTICE99 (matrix elements

A mechanism for precise linear and angular adjustment utilizing flexures

The design and development of a mechanism for precise linear and angular adjustment is described. This work was in support of the development of a mechanical extensometer for biaxial strain measurement. A compact mechanism was required which would allow angular adjustments about perpendicular axes with better than 0.001 degree resolution. The approach adopted was first to develop a means of precise linear adjustment. To this end, a mechanism based on the toggle principle was built with inexpensive and easily manufactured parts. A detailed evaluation showed that the resolution of the mechanism was better than 1 micron and that adjustments made by using the device were repeatable. In the second stage of this work, the linear adjustment mechanisms were used in conjunction with a simple arrangement of flexural pivots and attachment blocks to provide the required angular adjustments. Attempts to use the mechanism in conjunction with the biaxial extensometer under development proved unsuccessful. Any form of in stitu adjustment was found to cause erratic changes in instrument output. These changes were due to problems with the suspension system. However, the subject mechanism performed well in its own right and appeared to have potential for use in other applications

Biaxial experiments supporting the development of constitutive theories for advanced high-temperature materials

Complex states of stress and strain are introduced into components during service in engineering applications. It follows that analysis of such components requires material descriptions, or constitutive theories, which reflect the tensorial nature of stress and strain. For applications involving stress levels above yield, the situation is more complex in that material response is both nonlinear and history dependent. This has led to the development of viscoplastic constitutive theories which introduce time by expressing the flow and evolutionary equation in the form of time derivatives. Models were developed here which can be used to analyze high temperature components manufactured from advanced composite materials. In parallel with these studies, effort was directed at developing multiaxial testing techniques to verify the various theories. Recent progress in the development of constitutive theories from both the theoretical and experimental viewpoints are outlined. One important aspect is that material descriptions for advanced composite materials which can be implemented in general purpose finite element codes and used for practical design are verified

Phenomenological tests of the Two-Higgs-Doublet Model with MFV and flavour-blind phases

In the context of a Two-Higgs-Doublet Model in which Minimal Flavour Violation (MFV) is imposed, one can allow the presence of flavour-blind CP-violating phases without obtaining electric dipole moments that overcome the experimental bounds. This choice permits to accommodate the hinted large phase in the $B_s$ mixing and, at the same time, to soften the observed anomaly in the relation between $\epsilon_K$ and $S_{\psi K_S}$.Comment: 8 pages, 2 figures, Proceedings of "DISCRETE 2010" - December 6-11, 2010 - Rome (Italy

A Liouville String Approach to Microscopic Time and Cosmology

In the non-critical string framework that we have proposed recently, the time $t$ is identified with a dynamical local renormalization group scale, the Liouville mode, and behaves as a statistical evolution parameter, flowing irreversibly from an infrared fixed point - which we conjecture to be a topological string phase - to an ultraviolet one - which corresponds to a static critical string vacuum. When applied to a toy two-dimensional model of space-time singularities, this formalism yields an apparent renormalization of the velocity of light, and a $t$-dependent form of the uncertainty relation for position and momentum of a test string. We speculate within this framework on a stringy alternative to conventional field-theoretical inflation, and the decay towards zero of the cosmological constant in a maximally-symmetric space.Comment: Latex 23 pages, no figures, CERN-TH.7000/93, CTP-TAMU-66/9