The quantum compass chain in a transverse magnetic field

We study the magnetic behaviors of a spin-1/2 quantum compass chain (QCC) in a transverse magnetic field, by means of the analytical spinless fermion approach and numerical Lanczos method. In the absence of the magnetic field, the phase diagram is divided into four gapped regions. To determine what happens by applying a transverse magnetic field, using the spinless fermion approach, critical fields are obtained as a function of exchanges. Our analytical results show, the field-induced effects depend on in which one of the four regions the system is. In two regions of the phase diagram, the Ising-type phase transition happens in a finite field. In another region, we have identified two quantum phase transitions in the ground state magnetic phase diagram. These quantum phase transitions belong to the universality class of the commensurate-incommensurate phase transition. We also present a detailed numerical analysis of the low energy spectrum and the ground state magnetic phase diagram. In particular, we show that the intermediate state ($h_{c_{1}}<h<h_{c_{2}}$) is gapful, describing the spin-flop phase.Comment: 9 pages, 8 figures. arXiv admin note: substantial text overlap with arXiv:1008.211

Good reasons to use psychological questionnaires in enhancing teaching English as a foreign language / Hadi Farjami

This article argues for using general psychological questionnaires as part of teaching English as a foreign language. It is claimed that questionnaires, particularly psychological ones, enjoy many of the characteristics of effective instructional material, raise foundational learning- related awarenesses, can function as the ground for meaningful and authentic tasks, and help learners develop academic autonomy. Teachers can easily prepare questionnaire-based material and be sure that it is both engaging and conducive to language learning as well as to other learnings which may be highly relevant to personal and academic development. A survey which was conducted to empirically explore the perception of a group of English learners about the appropriateness and effect of using questionnaires as language learning material is very briefly reported as part of the argument for this teaching strategy. Some limitations of the proposed idea are also mentioned

Machine Learning Based Classifier for Service Function Chains

Using service function chains, Internet Service Providers can customize the use of service functions that process the network flows belonging to their customers. Each network flow is injected into a service chain according to the flow features. Since most of the malicious applications try not to get the proper analysis by imitating some valid and famous applications, classification based on simple flow features may waste processing power by using inappropriate service chains for evasive flows. In this paper, we have explored an application-aware classification approach using machine learning methods. Using CatBoost as a machine learning method, a model is created and used for traffic classification. We have provided some statistical reports on how this approach is compared with simple flow feature-based approaches in malicious environments and how feature selection can impact classification correctness. Choosing the most suitable number of features at the right time can beat traditional approaches in classification quality and provide better results in the service function chaining environment

Dyadic Deontic Logic in HOL : Faithful Embedding and Meta-Theoretical Experiments

A shallow semantical embedding of a dyadic deontic logic by Carmo and Jones in classical higher-order logic is presented. The embedding is proven sound and complete, that is, faithful. This result provides the theoretical foundation for the implementation and automation of dyadic deontic logic within off-the-shelf higher-order theorem provers and proof assistants. To demonstrate the practical relevance of our contribution, the embedding has been encoded in the Isabelle/HOL proof assistant. As a result a sound and complete (interactive and automated) theorem prover for the dyadic deontic logic of Carmo and Jones has been obtained. Experiments have been conducted which illustrate how the exploration and assessment of meta-theoretical properties of the embedded logic can be supported with automated reasoning tools integrated with Isabelle/HOL