The critical Ising lines of the d=2 Ashkin-Teller model

The universal critical point ratio $Q$ is exploited to determine positions of the critical Ising transition lines on the phase diagram of the Ashkin-Teller (AT) model on the square lattice. A leading-order expansion of the ratio $Q$ in the presence of a non-vanishing thermal field is found from finite-size scaling and the corresponding expression is fitted to the accurate perturbative transfer-matrix data calculations for the $L\times L$ square clusters with $L\leq 9$.Comment: RevTex, 4 pages, two figure

Fractal Scales in a Schwarzschild Atmosphere

Recently, Glass and Krisch have extended the Vaidya radiating metric to include both a radiation fluid and a string fluid [1999 Class. Quantum Grav. vol 16, 1175]. Mass diffusion in the extended Schwarzschild atmosphere was studied. The continuous solutions of classical diffusive transport are believed to describe the envelope of underlying fractal behavior. In this work we examine the classical picture at scales on which fractal behavior might be evident.Comment: to appear in Class. Quantum Gra

Generation of maximum spin entanglement induced by cavity field in quantum-dot systems

Equivalent-neighbor interactions of the conduction-band electron spins of quantum dots in the model of Imamoglu et al. [Phys. Rev. Lett. 83, 4204 (1999)] are analyzed. Analytical solution and its Schmidt decomposition are found and applied to evaluate how much the initially excited dots can be entangled to the remaining dots if all of them are initially disentangled. It is demonstrated that the perfect maximally entangled states (MES) can only be generated in the systems of up to 6 dots with a single dot initially excited. It is also shown that highly entangled states, approximating the MES with a good accuracy, can still be generated in systems of odd number of dots with almost half of them being excited. A sudden decrease of entanglement is observed by increasing the total number of dots in a system with a fixed number of excitations.Comment: 6 pages, 7 figures, to appear in Phys. Rev.

Bridging the Gap: Cognitive and social approaches to research in second language learning and teaching.

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139862/1/SSLA2014.pd

Aircraft computations using multigrid and an unstructured parallel library

This paper examines the application of unstructured multigrid, using a sequence of independent tetrahedral grids. The test cases examined are for inviscid flow over an aircraft and an M6 wing. The sensitivity of the method to grid sequence and cycling strategy are investigated. \ud \ud All of the calculations were performed on a parallel computer. This was achieved by using the OPlus library which, by the straightforward insertion of subroutine calls, facilitates parallelisation of the resulting code. A single source OPlus application code can be compiled to executed on either a parallel or sequential machine. This greatly increases the usability of the parallel machine, and the maintainability of the code

Investigating distribution of practice effects for the learning of foreign language verb morphology in the young learner classroom

Within limited-input language classrooms, understanding the effect of distribution of practice (spacing between practice) on learning is critical, yet evidence is conflicting and of limited relevance for young learners. For second language (L2) grammar learning, some studies reveal advantages for spacing of 7 days or more (Bird, 2010; Rogers, 2015), but others for shorter spacing (Suzuki, 2017). Further, little is known about the role of cognitive individual differences (e.g., language analytic ability) in mediating practice distribution effects for L2 grammatical knowledge development and retention (Suzuki & DeKeyser, 2017). To address this gap, this classroom-based study investigated whether distribution of practice and language analytic ability moderated the effectiveness of explicit, input-based grammar instruction for young first language (L1) English learners of French (aged 8 to 11). The study revealed minimal differences between longer (7-day) versus shorter (3.5-day) spacing of practice for learning an L2 French verb inflection subsystem, at either post- or delayed post-test. Minimal group-level gains and substantial within-group variation in performance at post-tests was observed. Accuracy of practice during training and language analytic ability were significantly associated with post-test performance under both practice schedules. These findings indicated that within an ecologically valid classroom context, differences in distribution of practice had limited impact on learner performance on our tests; rather, individual learner differences were more critical in moderating learning. This highlights the importance of considering individual learner differences in the development of resources and the potential of digital tools for dynamically adapting instruction to suit individuals

A database of whole-body action videos for the study of action, emotion, and untrustworthiness

We present a database of high-definition (HD) videos for the study of traits inferred from whole-body actions. Twenty-nine actors (19 female) were filmed performing different actions—walking, picking up a box, putting down a box, jumping, sitting down, and standing and acting—while conveying different traits, including four emotions (anger, fear, happiness, sadness), untrustworthiness, and neutral, where no specific trait was conveyed. For the actions conveying the four emotions and untrustworthiness, the actions were filmed multiple times, with the actor conveying the traits with different levels of intensity. In total, we made 2,783 action videos (in both two-dimensional and three-dimensional format), each lasting 7 s with a frame rate of 50 fps. All videos were filmed in a green-screen studio in order to isolate the action information from all contextual detail and to provide a flexible stimulus set for future use. In order to validate the traits conveyed by each action, we asked participants to rate each of the actions corresponding to the trait that the actor portrayed in the two-dimensional videos. To provide a useful database of stimuli of multiple actions conveying multiple traits, each video name contains information on the gender of the actor, the action executed, the trait conveyed, and the rating of its perceived intensity. All videos can be downloaded free at the following address: http://www-users.york.ac.uk/~neb506/databases.html. We discuss potential uses for the database in the analysis of the perception of whole-body actions

Finite time and asymptotic behaviour of the maximal excursion of a random walk

We evaluate the limit distribution of the maximal excursion of a random walk in any dimension for homogeneous environments and for self-similar supports under the assumption of spherical symmetry. This distribution is obtained in closed form and is an approximation of the exact distribution comparable to that obtained by real space renormalization methods. Then we focus on the early time behaviour of this quantity. The instantaneous diffusion exponent $\nu_n$ exhibits a systematic overshooting of the long time exponent. Exact results are obtained in one dimension up to third order in $n^{-1/2}$. In two dimensions, on a regular lattice and on the Sierpi\'nski gasket we find numerically that the analytic scaling $\nu_n \simeq \nu+A n^{-\nu}$ holds.Comment: 9 pages, 4 figures, accepted J. Phys.