Efficient indexing of necklaces and irreducible polynomials over finite fields

We study the problem of indexing irreducible polynomials over finite fields, and give the first efficient algorithm for this problem. Specifically, we show the existence of poly(n, log q)-size circuits that compute a bijection between {1, ... , |S|} and the set S of all irreducible, monic, univariate polynomials of degree n over a finite field F_q. This has applications in pseudorandomness, and answers an open question of Alon, Goldreich, H{\aa}stad and Peralta[AGHP]. Our approach uses a connection between irreducible polynomials and necklaces ( equivalence classes of strings under cyclic rotation). Along the way, we give the first efficient algorithm for indexing necklaces of a given length over a given alphabet, which may be of independent interest

Electron-acoustic plasma waves: oblique modulation and envelope solitons

Theoretical and numerical studies are presented of the amplitude modulation of electron-acoustic waves (EAWs) propagating in space plasmas whose constituents are inertial cold electrons, Boltzmann distributed hot electrons and stationary ions. Perturbations oblique to the carrier EAW propagation direction have been considered. The stability analysis, based on a nonlinear Schroedinger equation (NLSE), reveals that the EAW may become unstable; the stability criteria depend on the angle $\theta$ between the modulation and propagation directions. Different types of localized EA excitations are shown to exist.Comment: 10 pages, 5 figures; to appear in Phys. Rev.

The Properties of Large Amplitude Whistler Mode Waves in the Magnetosphere: Propagation and Relationship with Geomagnetic Activity

Wepresent resultsof a studyof the characteristicsof very large amplitude whistler mode waves inside the terrestrial magnetosphere at radial distances of less than 15 RE using waveform capture data from the Wind spacecraft. We observed 247 whistler mode waves with at least one electric field component (105/247 had !80 mV/m peak!to!peak amplitudes) and 66 whistler mode waves with at least one search coil magnetic field component (38/66 had !0.8 nT peak!to!peak amplitudes). Wave vectors determined from events with three magnetic field components indicate that 30/46 propagate within 20 of the ambient magnetic field, though some are more oblique (up to "50 ). No relationship was observed between wave normal angle and GSM latitude. 162/247 of the large amplitude whistler mode waves were observed during magnetically active periods (AE > 200 nT). 217 out of 247 total whistler mode waves examined were observed inside the radiation belts. We present a waveform capture with the largest whistler wave magnetic field amplitude (^8 nT peak!to!peak) ever reported in the radiation belts. The estimated Poynting flux magnitude associated with this wave is ^300 mW/m2, roughly four orders of magnitude above estimates from previous satellite measurements. Such large Poynting flux values are consistent with rapid energization of electrons

An inter-institutional postgraduate diploma for university teachers: exploring formative feedback data from the position of socially just pedagogies

In January 2014, after many years of preparation, the Postgraduate Diploma in Higher Education Teaching and Learning [PG Dip (HETL)] – a collaboration between the Cape Peninsula University of Technology, the University of Stellenbosch and the University of the Western Cape – was offered. The qualification is a two-year part-time course, and the first cohort of participants graduated in December 2015. The question that this paper seeks to address is whether a collaborative qualification, offered to academic staff across very different institutions, can make a contribution towards socially just teaching and learning in higher education. The study draws on Nancy Fraser's (2003) conceptualisation of social justice, with its three dimensions of redistribution, recognition and representation, as a framework for reflecting on the extent to which the programme contributed towards the development and understanding of socially just pedagogies in professional learning. This paper draws on data collected from participants' and facilitators' formative feedback on the postgraduate diploma over a two-year period (2014 – 2015). We conclude that offering a single PG Dip (HETL) collaboratively across three universities was socially just in that knowledge and resources were shared, differently placed institutions were brought together, with their different attributes being valued, and participants were given opportunities to interact with and learn from one another across differences. Applying the research findings to practice suggests that programmes in support of socially just professional learning should enhance alignment across the redistribution of facilitator and participant resources, recognise and address participants' concerns and build participants' academic voices – elements key to participatory parity.DHE

Workplace stress in the construction industry: An explanatory model

The construction industry is noted for high levels of occupational stress, particularly among professional workers. Using data from 676 architects, civil engineers, quantity surveyors, and project and construction managers responding to an on-line survey in South Africa, an integrated conceptual model of occupational stress is proposed. Structural equation modeling is used to test the model iteratively. The results of the final model indicate that: psychological, physiological and sociological strain effects are the terminal consequences of occupational stress; organizational climate is largely determined by gender and job demand, control and support; age, gender, control and organizational climate are predictors of discrimination; psychological distress is predicted by age, job demand and control factors, and organizational climate; sociological stress is determined by age, job demands, discrimination and psychological distress; and age, and sociological and psychological stress effects manifest themselves as predictors of physiological stress effects. Construction employers should regularly review workload allocations, empower employees, foster a supportive work environment, conduct stress appraisals, and hold stress management workshops

Social Roles and Baseline Proxemic Preferences for a Domestic Service Robot

© The Author(s) 2014. This article is published with open access at Springerlink.com. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. The work described in this paper was conducted within the EU Integrated Projects LIREC (LIving with Robots and intEractive Companions, funded by the European Commission under contract numbers FP7 215554, and partly funded by the ACCOMPANY project, a part of the European Union’s Seventh Framework Programme (FP7/2007–2013) under grant agreement n287624The goal of our research is to develop socially acceptable behavior for domestic robots in a setting where a user and the robot are sharing the same physical space and interact with each other in close proximity. Specifically, our research focuses on approach distances and directions in the context of a robot handing over an object to a userPeer reviewe

Performance Measurements of a Low Specific Speed TurboClaw (R) Compressor

Low specific speed compressors have been historically based on positive displacement machines. Attempts to bring advantages of turbomachinery such as oil free, low parts counts, low cost of manufacture, and reliability to low flow rate applications have not been sparse, but the principle difficulty has always been that the conventional turbomachine design operates at ultra-high speed to deliver low volume flow rates. This is synonymous with low efficiency due to higher losses (windage, surface finish, and tip clearances). The innovative TurboClaw® design is a low specific speed turbomachinery with forward swept impeller geometry. It owes its high efficiency and operational stability to careful design of its nearly tangential forward swept blading and diffuser geometry. The present contribution describes the design and development of a high speed test rig to accurately measure TurboClaw efficiency using shaft torque. The test rig employs a permanent magnet high speed motor designed and developed for this purpose. The motor shaft drives a single stage TurboClaw® compressor via a high speed torque sensor. The results are presented and compared to data obtained through an energy balance method well established for this geometry since its first innovative development at Imperial College in 2003. The accurate performance measurements have been used to design and test a two stage compressor to recover energy from waste steam. This is also briefly described