Revised time-of-flight calculations for high-latitude geomagnetic pulsations using a realistic magnetospheric magnetic field model

We present a simple time-of-flight analysis of Alfvén pulsations standing on closed terrestrial magnetic field lines. The technique employed in this study in order to calculate the characteristic period of such oscillations builds upon earlier time-of-flight estimates via the implementation of a more recent magnetospheric magnetic field model. In this case the model employed is the Tsyganenko (1996) field model, which includes realistic magnetospheric currents and the consequences of the partial penetration of the interplanetary magnetic field into the dayside magnetopause. By employing a simple description of magnetospheric plasma density, we are therefore able to estimate the period of standing Alfvén waves on geomagnetic field lines over a significantly wider range of latitudes and magnetic local times than in previous studies. Furthermore, we investigate the influence of changing season and upstream interplanetary conditions upon the period of such pulsations. Finally, the eigenfrequencies of magnetic field lines computed by the time-of-flight technique are compared with corresponding numerical solutions to the wave equation and experimentally observed pulsations on geomagnetic field lines

Expanding the vision: a study of trainee teachers’ beliefs about using technology in the English language classroom

This study investigates the beliefs of a group of English language teacher trainees from Malaysia with regard to the use of technology for teaching and learning English. The Malaysian school system, like many schools systems, is strongly committed to the implementation and integration of technology across the curriculum in order to equip its next generation of citizens to compete globally in the technological age. Teacher trainees today, who have often grown up with technology and might be considered as digital natives (Prensky, 2001) or second generation users of technology, appear ideally placed to expedite this aim. In this study, three instruments are used for investigating teacher trainees’ beliefs: questionnaires, discussion boards and reflective writing. Findings suggest that whilst some traditional concerns relating to technology use remain, a number of additional concerns have arisen, such as the perceived need for a wide knowledge of technological tools and a feeling of pressure to keep up to date. The study also highlights several negative influences on participants’ perceptions of technology and its use in the classroom, such as the effect of their own classroom experiences as learners or ‘apprentice of observation’ (Lortie, 1975). Based on the findings, a framework for incorporating a more appropriate technology component into language teacher education programmes emerges which might help second generation users in developing appropriate skills for an ever-changing digital environment

On implicational bases of closure systems with unique critical sets

We show that every optimum basis of a finite closure system, in D.Maier's sense, is also right-side optimum, which is a parameter of a minimum CNF representation of a Horn Boolean function. New parameters for the size of the binary part are also established. We introduce a K-basis of a general closure system, which is a refinement of the canonical basis of Duquenne and Guigues, and discuss a polynomial algorithm to obtain it. We study closure systems with the unique criticals and some of its subclasses, where the K-basis is unique. A further refinement in the form of the E-basis is possible for closure systems without D-cycles. There is a polynomial algorithm to recognize the D-relation from a K-basis. Thus, closure systems without D-cycles can be effectively recognized. While E-basis achieves an optimum in one of its parts, the optimization of the others is an NP-complete problem.Comment: Presented on International Symposium of Artificial Intelligence and Mathematics (ISAIM-2012), Ft. Lauderdale, FL, USA Results are included into plenary talk on conference Universal Algebra and Lattice Theory, June 2012, Szeged, Hungary 29 pages and 2 figure

Remote manipulator dynamic simulation

A simulator to generate the real time visual scenes required to perform man in the loop investigations of remote manipulator application and design concepts for the space shuttle is described. The simulated remote manipulator consists of a computed display system that uses a digital computer, the electronic scene generator, an operator's station, and associated interface hardware. A description of the capabilities of the implemented simulation is presented. The mathematical models and programs developed for the simulation are included

On a generalized quantum SWAP gate

The SWAP gate plays a central role in network designs for qubit quantum computation. However, there has been a view to generalize qubit quantum computing to higher dimensional quantum systems. In this paper we construct a generalized SWAP gate using only instances of the generalized controlled-NOT gate to cyclically permute the states of d qudits for d prime

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Dietary aflatoxin exposure and impaired growth in young children from Benin and Togo: cross sectional study

Fetal and early childhood environment, including the nutritional status of the pregnant mother and the infant, are considered critical for growth and risk of disease in later life. Many people in developing coun­ tries are not only malnourished but also chronically exposed to high levels of toxic fungal metabolites (mycotoxins). One family of mycotoxins, the aflatoxins, are carcinogenic and immunotoxic and cause growth retardation in animals. Aflatoxins contaminate staple foods in West Africa, particularly maize and ground­ nuts, as a result of hot, humid storage conditions that promote fungal growth. High exposure to aflatoxins occurs throughout childhood in the region, suggest­ ing that growth and development could be critically affected.We assessed exposure to aflatoxins in relation to anthropometric measures in children in Benin and Togo

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