Inhomogeneous Magnetoelectric Effect on Defect in Multiferroic Material: Symmetry Prediction

Inhomogeneous magnetoelectric effect in magnetization distribution heterogeneities (0-degree domain walls) appeared on crystal lattice defect of the multiferroic material has been investigated. Magnetic symmetry based predictions of kind of electrical polarization distribution in their volumes were used. It was found that magnetization distribution heterogeneity with any symmetry produces electrical polarization. Results were systemized in scope of micromagnetic structure chirality. It was shown that all 0-degree domain walls with time-noninvariant chirality have identical type of spatial distribution of the magnetization and polarization.Comment: submitted to IOP Conference Series: Materials Science and Engineerin

Anisotropic thermal expansion of Fe1.06Te and FeTe0.5Se0.5 single crystals

Heat capacity and anisotropic thermal expansion was measured for Fe1.06Te and FeTe0.5Se0.5 single crystals. Previously reported phase transitions are clearly seen in both measurements. In both cases the thermal expansion is anisotropic. The uniaxial pressure derivatives of the superconducting transition temperature in FeTe0.5Se0.5 inferred from the Ehrenfest relation have opposite signs for in-plane and c-axis pressures. Whereas the Gruneisen parameters for both materials are similar and only weakly temperature-dependent above ~ 80 K, at low temperatures (in the magnetically ordered phase) the magnetic contribution to the Gruneisen parameter in Fe1.06Te is significantly larger than electron and phonon contributions combined

The redundancy of universal compression for finite-length memoryless sources

In this paper, we investigate the redundancy in the universal compression of finitelength smooth parametric sources. Rissanen demonstrated that for a smooth parametric source with d unknown parameters, the expected redundancy for regular codes is asymptotically given by d 2 log n + o(log n) for almost all sources We derive a lower bound on the probability that the source is compressed with redundancy greater than any redundancy level R 0 , i.e., we find a lower bound on P[R n (l 2p , θ) > R 0 ], where R n (l 2p , θ) is the redundancy in the compression of a parametric sequence of length n using a two-part length function l 2p for the source parameter θ. In other words, we derive a lower bound on the probability measure of the sources that are not compressible with a redundancy smaller than a certain fraction of d 2 log n: Theorem 1 Let ϵ be a real number such that 0 < ϵ < 1. Then, the probability that log n is lower bounded as where C d is the volume of d-dimensional unit ball, I(θ) is the fisher information matrix. Further, we precisely characterize the minimax redundancy of universal coding for parametric sources when a two-part length function is considered. Let g(d) denote the extra redundancy incurred by the two-part assumption. Then, , where Γ is the gamma function. This extra redundancy is negligible compared to the main term ( d 2 log n ) when the number of source parameters is large. REFERENCES [1] J. Rissanen, "Complexity of strings in the class of Markov sources,&quot

MDL Convergence Speed for Bernoulli Sequences

The Minimum Description Length principle for online sequence estimation/prediction in a proper learning setup is studied. If the underlying model class is discrete, then the total expected square loss is a particularly interesting performance measure: (a) this quantity is finitely bounded, implying convergence with probability one, and (b) it additionally specifies the convergence speed. For MDL, in general one can only have loss bounds which are finite but exponentially larger than those for Bayes mixtures. We show that this is even the case if the model class contains only Bernoulli distributions. We derive a new upper bound on the prediction error for countable Bernoulli classes. This implies a small bound (comparable to the one for Bayes mixtures) for certain important model classes. We discuss the application to Machine Learning tasks such as classification and hypothesis testing, and generalization to countable classes of i.i.d. models.Comment: 28 page

Ab initio parametrised model of strain-dependent solubility of H in alpha-iron

The calculated effects of interstitial hydrogen on the elastic properties of alpha-iron from our earlier work are used to describe the H interactions with homogeneous strain fields using ab initio methods. In particular we calculate the H solublility in Fe subject to hydrostatic, uniaxial, and shear strain. For comparison, these interactions are parametrised successfully using a simple model with parameters entirely derived from ab initio methods. The results are used to predict the solubility of H in spatially-varying elastic strain fields, representative of realistic dislocations outside their core. We find a strong directional dependence of the H-dislocation interaction, leading to strong attraction of H by the axial strain components of edge dislocations and by screw dislocations oriented along the critical slip direction. We further find a H concentration enhancement around dislocation cores, consistent with experimental observations.Comment: part 2/2 from splitting of 1009.3784 (first part was 1102.0187), minor changes from previous version

Overview of the 1st international competition on plagiarism detection

The 1st International Competition on Plagiarism Detection, held in conjunction with the 3rd PAN workshop on Uncovering Plagiarism, Authorship, and Social Software Misuse, brought together researchers from many disciplines around the exciting retrieval task of automatic plagiarism detection. The competition was divided into the subtasks external plagiarism detection and intrinsic plagiarism detection, which were tackled by 13 participating groups. An important by-product of the competition is an evaluation framework for plagiarism detection, which consists of a large-scale plagiarism corpus and detection quality measures. The framework may serve as a unified test environment to compare future plagiarism detection research. In this paper we describe the corpus design and the quality measures, survey the detection approaches developed by the participants, and compile the achieved performance results of the competitors

Overview of the 2nd international competition on plagiarism detection

This paper overviews 18 plagiarism detectors that have been developed and evaluated within PAN'10. We start with a unified retrieval process that summarizes the best practices employed this year. Then, the detectors' performances are evaluated in detail, highlighting several important aspects of plagiarism detection, such as obfuscation, intrinsic vs. external plagiarism, and plagiarism case length. Finally, all results are compared to those of last year's competition

Overview of the 3rd international competition on plagiarism detection

This paper overviews eleven plagiarism detectors that have been developed and evaluated within PAN'11. We survey the detection approaches developed for the two sub-tasks "external plagiarism detection" and "intrinsic plagiarism detection," and we report on their detailed evaluation based on the third revised edition of the PAN plagiarism corpus PAN-PC-11

On Convergence Properties of Shannon Entropy

Convergence properties of Shannon Entropy are studied. In the differential setting, it is shown that weak convergence of probability measures, or convergence in distribution, is not enough for convergence of the associated differential entropies. A general result for the desired differential entropy convergence is provided, taking into account both compactly and uncompactly supported densities. Convergence of differential entropy is also characterized in terms of the Kullback-Liebler discriminant for densities with fairly general supports, and it is shown that convergence in variation of probability measures guarantees such convergence under an appropriate boundedness condition on the densities involved. Results for the discrete setting are also provided, allowing for infinitely supported probability measures, by taking advantage of the equivalence between weak convergence and convergence in variation in this setting.Comment: Submitted to IEEE Transactions on Information Theor

The effects of room design on computer-supported collaborative learning in a multi-touch classroom.

While research indicates that technology can be useful for supporting learning and collaboration, there is still relatively little uptake or widespread implementation of these technologies in classrooms. In this paper, we explore one aspect of the development of a multi-touch classroom, looking at two different designs of the classroom environment to explore how classroom layout may influence group interaction and learning. Three classes of students working in groups of four were taught in the traditional forward-facing room condition, while three classes worked in a centered room condition. Our results indicate that while the outcomes on tasks were similar across conditions, groups engaged in more talk (but not more off-task talk) in a centered room layout, than in a traditional forward-facing room. These results suggest that the use of technology in the classroom may be influenced by the location of the technology, both in terms of the learning outcomes and the interaction behaviors of students. The findings highlight the importance of considering the learning environment when designing technology to support learning, and ensuring that integration of technology into formal learning environments is done with attention to how the technology may disrupt, or contribute to, the classroom interaction practices