Statistical switching kinetics in ferroelectrics

By assuming a more realistic nucleation and polarization reversal scenario we build a new statistical switching model for ferroelectrics, which is different from either the Kolmogorov-Avrami-Ishibashi (KAI) model or the Nucleation-Limited-Switching (NLS) model. After incorporating a time-dependent depolarization field this model gives a good description about the retardation behavior in polycrystalline thin films at medium or low fields, which can not be described by the traditional KAI model. This model predicts correctly n=1 for polycrystalline thin films at high Eappl or ceramic bulks in the ideal case

Global structures in a composite system of two scale-free discs with a coplanar magnetic field

We investigate a theoretical MHD disc problem involving a composite disc system of gravitationally coupled stellar and gaseous discs with a coplanar magnetic field in the presence of an axisymmetric dark matter halo. The two discs are expediently approximated as razor-thin, a ring-like magnetic field, and a power-law rotation curve in radius . By imposing the scale-free condition, we construct analytically stationary global MHD perturbation configurations for both aligned and logarithmic spiral patterns. MHD perturbation configurations in a composite system of partial discs in the presence of an axisymmetric dark matter halo are also considered. We derive analytically the stationary MHD dispersion relations for both aligned and unaligned perturbation structures and analyze the corresponding phase relationships between surface mass densities and the magnetic field. Compared with earlier results, we obtain three solution branches corresponding to super fast MHD density waves, fast MHD density waves and slow MHD density waves, respectively. By evaluating the unaligned $m=0$ case, we determine the marginal stability curves where the two unstable regimes corresponding to Jeans collapse instability and ring fragmentation instability are identified. We find that the aligned $m=0$ case is simply the limit of the unaligned $m=0$ case with the radial wavenumber $\xi\to0$. We further show that a composite system of partial discs behaves much differently from a composite system of full discs in certain aspects. Our formalism provides a useful theoretical framework in the study of stationary global perturbation configurations for MHD disc galaxies with bars, spirals and barred spirals.Comment: 35 pages, 24 figures, Accepted for publication in MNRA

Fast magnetoacoustic waves in a randomly structured solar corona

The propagation of fast magnetoacoustic waves in a randomly structured solar corona is considered in the linear and cold plasma limits. The random field is assumed to be static and associated with plasma density inhomogeneities only. A transcendental dispersion relation for the fast magnetoacoustic waves which propagate perpendicularly to the magnetic field is derived in the weak random field approximation. It is shown analytically that the fast magnetosonic waves experience acceleration, attenuation, and dispersion in comparison to the homogeneous case. These analytical findings are essentially confirmed by numerical simulations for a wide-spectrum pulse, except that the waves were found decelerated. It is concluded that the coronal Moreton waves can be applied to MHD seismology of the solar corona

Are we really that different from each other? The difficulties of focusing on similarities in cross-cultural research.

In this article we argue that there are 2 dominant underlying themes in discussions of strategies for dealing with diversity—similarity and difference. When we are dealing with social groups, a number of basic psychological processes, as well as popular media and research-based narratives, make it easier to highlight difference rather than similarity. This difference-based approach in research is inherently divisive, but the training that we receive as researchers in the field of psychology has taken us down this path. As a first step, we propose that researchers working in the area of cultural diversity should start making explicit attempts to highlight similarities between groups, even if such similarities are only based on the absence of observed statistical differences. Moreover, if we are going to be serious about demonstrating similarity between groups and certain types of universals in behavior, we should start embracing new approaches to data analyses and consider using statistical procedures that test for equivalence. We illustrate these new techniques using our own data. Finally, we argue that shifting our primary focus from difference to similarity is a worthwhile direction to pursue for successfully managing diversity in multicultural societies.Social Sciences and Humanities Research Council (SSHRC

A Study on the Effectiveness of Crossword Puzzle as Compared to Conventional Method in Teaching Vocabulary

This study is entitled “The Effectiveness of Crossword Puzzle as Compared TheConventional Method in Teaching Vocabulary.”The research was administered to answer the question “Is crossword puzzle ascompared to other methods effective in improving student vocabulary achievement?” The datawere collected through pretest and posttest, administered to 35 student and the data wasanalyzed by using T-test.The participants of this study were the grade five elementary pupils of kartika elementaryschool. in section 5A there were 34 pupils who were taught using conventional method andsection 5B there were 35 pupils who were taught using crossword puzzle method. The age ofthe participants were between 11-15 years old.From the computation of the pretest and posttest, the result mean of pretest controlgroup=51.17, the result mean of pretest experimental group=55.14. and the mean posttestcontrol group= 56.61,the mean posttest experiment group= 63.42. The result shows that t counted=2.106>t table = 1,684. There is significant different crossword puzzle method effective toimprove vocabulary skills.The researcher hopes that the finding of present crossword puzzle method could give somecontribution to the improvement vocabulary especially for the students of Kartika X-3,Parompong, Bandung

Arthroscopic Removal of Suprapatellar Fibroma of Tendon Sheath

Fibroma of tendon sheath (FTS) is a rare dense fibrous benign tumor that majorities are found over the tendons or tendon sheaths of limbs, with predilection in order starting with fingers, hands, wrists, and other parts.1 Almost 80% of tendon sheath fibromas are found over hands and wrists.2 The typical morphological feature is a solid nodule that is painless and slow growing in nature. Fibromas of tendon sheath rarely arise from knee joints. To our best knowledge, less than 20 such cases have been reported, and none of them was a Chinese patient. We present a case of intra-articular fibroma of tendon sheath of the knee that was excised arthroscopically.published_or_final_versio

Entanglement Spectra of the 2D AKLT Model: VBS/CFT Correspondence

We investigate the entanglement properties of the valence-bond-solid (VBS) state defined on two-dimensional lattices, which is the exact ground state of the Affleck-Kennedy-Lieb-Tasaki model. It is shown that the entanglement entropy obeys an area law and the non-universal prefactor of the leading term is strictly less than $\ln 2$. The analysis of entanglement spectra for various lattices reveals that the reduced density matrix associated with the VBS state is closely related to a thermal density matrix of a {\it holographic} spin chain, whose spectrum is reminiscent of that of the spin-1/2 Heisenberg chain. This correspondence is further supported by comparing the entanglement entropy in the holographic spin chain with conformal field theory predictions.Comment: 10 pages, 9 figures, published versio