Faddeev-Skyrme Model and Rational Maps

The Faddeev-Skyrme model, a modified O(3) nonlinear sigma model in three space dimensions, is known to admit topological solitons that are stabilized by the Hopf charge. The Faddeev-Skyrme model is also related to the low-energy limits of SU(2) Yang-Mills theory. Here, the model is reformulated into its gauge-equivalent expression, which turns out to be Skyrme-like. The solitonic solutions of this Skyrme-like model are analyzed by the rational map ansatz. The energy function and the Bogomolny-type lower bound of the energy are established. The generalized Faddeev-Skyrme model that originates from the infrared limits of SU(N) Yang-Mills theory is presented.Comment: 12 pages, LaTex, minor typo correcte

SWiM: A Simple Window Mover

As computers become more ubiquitous, traditional two-dimensional interfaces must be replaced with interfaces based on a three-dimensional metaphor. However, these interfaces must still be as simple and functional as their two-dimensional predecessors. This paper introduces SWiM, a new interface for moving application windows between various screens, such as wall displays, laptop monitors, and desktop displays, in a three-dimensional physical environment. SWiM was designed based on the results of initial "paper and pencil" user tests of three possible interfaces. The results of these tests led to a map-like interface where users select the destination display for their application from various icons. If the destination is a mobile display it is not displayed on the map. Instead users can select the screen's name from a list of all possible destination displays. User testing of SWiM was conducted to discover whether it is easy to learn and use. Users that were asked to use SWiM without any instructions found the interface as intuitive to use as users who were given a demonstration. The results show that SWiM combines simplicity and functionality to create an interface that is easy to learn and easy to use.Comment: 7 pages, 4 figure

A Workload-Specific Memory Capacity Configuration Approach for In-Memory Data Analytic Platforms

We propose WSMC, a workload-specific memory capacity configuration approach for the Spark workloads, which guides users on the memory capacity configuration with the accurate prediction of the workload's memory requirement under various input data size and parameter settings.First, WSMC classifies the in-memory computing workloads into four categories according to the workloads' Data Expansion Ratio. Second, WSMC establishes a memory requirement prediction model with the consideration of the input data size, the shuffle data size, the parallelism of the workloads and the data block size. Finally, for each workload category, WSMC calculates the shuffle data size in the prediction model in a workload-specific way. For the ad-hoc workload, WSMC can profile its Data Expansion Ratio with small-sized input data and decide the category that the workload falls into. Users can then determine the accurate configuration in accordance with the corresponding memory requirement prediction.Through the comprehensive evaluations with SparkBench workloads, we found that, contrasting with the default configuration, configuration with the guide of WSMC can save over 40% memory capacity with the workload performance slight degradation (only 5%), and compared to the proper configuration found out manually, the configuration with the guide of WSMC leads to only 7% increase in the memory waste with the workload's performance slight improvement (about 1%

Are Real Exchange Rates Nonlinear with a Unit Root? Evidence on Purchasing Power Parity for China: A Note

This article applies the threshold autoregressive model proposed by Caner and Hansen (2001) to examine both linearity and stationarity of China's real exchange rate vis-à-vis her 9 trading partner countries over the period of January 1986 to October 2009. Two main conclusions are drawn. Firstly, the empirical results indicate that China's real exchange is a nonlinear process. Secondly, a unit root in real exchange rate was found for most of the cases under study. This result provides no support for purchasing power parity for China relative to their major trading partner countries.Threshold Autoregressive Model; Linearity and Stationarity, Purchasing Power Parity; Threshold Unit Root Test

Grammatical errors in spoken english of University students in oral communication course

The present study examines the grammatical errors in spoken English of university students who are less proficient in English. The specific objectives of the study are to determine the types of errors and the changes in grammatical accuracy during the duration of the English for Social Purposes course focussing on oral communication. The language data were obtained from the simulated oral interactions of 42 students participating in five role play situations during the 14-week semester. Error analysis of 126 oral interactions showed that the five common grammar errors made by the learners are preposition, question, article, plural form of nouns, subject-verb agreement and tense. Based on Dulay, Burt and Krashen’s (1982) surface structure taxonomy, the main ways by which students modify the target forms are misinformation and omission, with addition of elements or misordering being less frequent. The results also showed an increase in grammatical accuracy in the students’ spoken English towards the end of the course