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

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.

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

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.

Dimension in a Radiative Stellar Atmosphere

Dimensional scales are examined in an extended 3+1 Vaidya atmosphere surrounding a Schwarzschild source. At one scale, the Vaidya null fluid vanishes and the spacetime contains only a single spherical 2-surface. Both of these behaviors can be addressed by including higher dimensions in the spacetime metric.Comment: to appear in Gen. Rel. Gra

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

Assessment of Higher-Order RANS Closures in a Decelerated Planar Wall-Bounded Turbulent Flow

A reference DNS database is presented, which includes third- and fourth-order moment budgets for unstrained and strained planar channel flow. Existing RANS closure models for third- and fourth-order terms are surveyed, and new model ideas are introduced. The various models are then compared with the DNS data term by term using a priori testing of the higher-order budgets of turbulence transport, velocity-pressure-gradient, and dissipation for both the unstrained and strained databases. Generally, the models for the velocity-pressure-gradient terms are most in need of improvement

Foodborne Illness Acquired in the United States—Unspecified Agents

Each year, unspecified agents caused an estimated 38.4 million episodes of illness, resulting in 71,878 hospitalizations and 1,686 deaths

Search for muon-neutrino emission from GeV and TeV gamma-ray flaring blazars using five years of data of the ANTARES telescope

The ANTARES telescope is well-suited for detecting astrophysical transient neutrino sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. The background due to atmospheric particles can be drastically reduced, and the point-source sensitivity improved, by selecting a narrow time window around possible neutrino production periods. Blazars, being radio-loud active galactic nuclei with their jets pointing almost directly towards the observer, are particularly attractive potential neutrino point sources, since they are among the most likely sources of the very high-energy cosmic rays. Neutrinos and gamma rays may be produced in hadronic interactions with the surrounding medium. Moreover, blazars generally show high time variability in their light curves at different wavelengths and on various time scales. This paper presents a time-dependent analysis applied to a selection of flaring gamma-ray blazars observed by the FERMI/LAT experiment and by TeV Cherenkov telescopes using five years of ANTARES data taken from 2008 to 2012. The results are compatible with fluctuations of the background. Upper limits on the neutrino fluence have been produced and compared to the measured gamma-ray spectral energy distribution.Comment: 27 pages, 16 figure