Power and politics in requirements engineering: embracing the dark side?

This vision paper considers the role of power and politics in requirements engineering (RE). It offers a working definition of both terms and reviews the existing literature both in RE and related disciplines. It argues that, given the increased complexity, uncertainty and organisational embeddedness faced by RE in practice, power and politics have become increasingly relevant factors that have not been adequately considered. Building upon recent relevant research, a research agenda is proposed that presents a methodological framework which examines power and politics through the structure of power relations and the process of decision-making. This framework will require validation through empirical research as a first step to developing models of power and politics that could be of practical use for RE. Although the potential problems faced by the study of power and politics in an RE context are acknowledged, it is argued that the potential benefits could be significant

Requirements Engineering as Creative Problem Solving: A Research Agenda for Idea Finding

This vision paper frames requirements engineering as a creative problem solving process. Its purpose is to enable requirements researchers and practitioners to recruit relevant theories, models, techniques and tools from creative problem solving to understand and support requirements processes more effectively. It uses 4 drivers to motivate the case for requirements engineering as a creative problem solving process. It then maps established requirements activities onto one of the longest-established creative problem solving processes, and uses these mappings to locate opportunities for the application of creative problem solving in requirements engineering. The second half of the paper describes selected creativity theories, techniques, software tools and training that can be adopted to improve requirements engineering research and practice. The focus is on support for problem and idea finding - two creative problem solving processes that our investigation revealed are poorly supported in requirements engineering. The paper ends with a research agenda to incorporate creative processes, techniques, training and tools in requirements projects

The structure of intercalated water in superconducting Na0.35_{0.35}CoO2⋅_{2}\cdot1.37D2_{2}O: Implications for the superconducting phase diagram

We have used electron and neutron powder diffraction to elucidate the structural properties of superconducting \NaD. Our measurements show that our superconducting sample exhbits a number of supercells ranging from ${1/3}a^{*}$ to ${1/15}a^{*}$, but the most predominant one, observed also in the neutron data, is a double hexagonal cell with dimensions \dhx. Rietveld analysis reveals that \deut\space is inserted between CoO$_{2}$ sheets as to form a layered network of NaO$_{6}$ triangular prisms. Our model removes the need to invoke a 5K superconducting point compound and suggests that a solid solution of Na is possible within a constant amount of water $y$.Comment: 4 pages, 3 figure

The Distance to the Vela Supernova Remnant

We have obtained high resolution Ca II and Na I absorption line spectra toward 68 OB stars in the direction of the Vela Supernova Remnant. The stars lie at distances of 190 -- 2800 pc as determined by Hipparcos and spectroscopic parallax estimations. The presence of high velocity absorption attributable to the remnant along some of the sight lines constrains the remnant distance to 250+/-30 pc. This distance is consistent with several recent investigations that suggest that the canonical remnant distance of 500 pc is too large.Comment: To be published in The Astrophysical Journal Letters Figure 1 y-axis labels correcte

Transition from a phase-segregated state to single-phase incommensurate sodium ordering in Na_xCoO_2 with x \approx 0.53

Synchrotron X-ray diffraction investigations of two single crystals of Na_xCoO_2 from different batches with composition x = 0.525-0.530 reveal homogeneous incommensurate sodium ordering with propagation vector (0.53 0.53 0) at room-temperature. The incommensurate (qq0) superstructure exists between 220 K and 430 K. The value of q varies between q = 0.514 and 0.529, showing a broad plateau at the latter value between 260 K and 360 K. On cooling, unusual reversible phase segregation into two volume fractions is observed. Below 220 K, one volume fraction shows the well-known commensurate orthorhombic x = 0.50 superstructure, while a second volume fraction with x = 0.55 exhibits another commensurate superstructure, presumably with a 6a x 6a x c hexagonal supercell. We argue that the commensurate-to-incommensurate transition is an intrinsic feature of samples with Na concentrations x = 0.5 + d with d ~ 0.03.Comment: Corrected/improved versio

Summation and transformation formulas for elliptic hypergeometric series

Using matrix inversion and determinant evaluation techniques we prove several summation and transformation formulas for terminating, balanced, very-well-poised, elliptic hypergeometric series.Comment: 21 pages, AMS-LaTe

Coexisting ordinary elasticity and superfluidity in a model of defect-free supersolid

We present the mechanics of a model of supersolid in the frame of the Gross-Pitaevskii equation at $T=0K$ that do not require defects nor vacancies. A set of coupled nonlinear partial differential equations plus boundary conditions is derived. The mechanical equilibrium is studied under external constrains as steady rotation or external stress. Our model displays a paradoxical behavior: the existence of a non classical rotational inertia fraction in the limit of small rotation speed and no superflow under small (but finite) stress nor external force. The only matter flow for finite stress is due to plasticity.Comment: 6 pages, 2 figure

Formal groups arising from formal punctured ribbons

We investigate Picard functor of a formal punctured ribbon. We prove that under some conditions this functor is representable by a formal group scheme. Formal punctured ribbons were introduced in arXiv:0708.0985.Comment: 42 pages, minor change

Surgical cure of the Wolff-Parkinson-White syndrome a comparison of two techniques

Curative arrhythmia surgery for patients with symptomatic Wolff-Parkinson-White syndrome (WPW) was first performed in South Africa in November 1987. Pre-operatively all patients were symptomatic despite medical therapy, and 32% were assessed as being at risk for sudden death. The first 9 patients (November 1987 to December 1989) underwent either epicardial or localised endocardial surgical dissections, and a cure was obtained in 66%. Aberrant atrioventricular conduction recurred in 2 patients, 30 atrioventricular heart block occurred in 2 patients, and there was 1 postoperative death in a patient who had undergone simultaneous coronary artery bypass grafting. In contrast, a standardised endocardial technique was used in the subsequent 10 patients. Surgical cure was obtained in all 10 patients (P < 0,01). However, 1 patient required reoperation 24 hours after the first procedure because of early postoperative recurrence due to initial incorrect pathway localisation. This was successful. There were no deaths, and no patient developed atrioventricular heart block. In view of the excellent surgical results, arrhythmia surgery should be considered in select WPW patients who either have refractory symptoms or are at risk for sudden death. Furthermore, this reliable surgical technique provides an essential back-up should alternative interventionalprocedures such as percutaneous radiofrequency ablation fail

A Bilinear Approach to Discrete Miura Transformations

We present a systematic approach to the construction of Miura transformations for discrete Painlev\'e equations. Our method is based on the bilinear formalism and we start with the expression of the nonlinear discrete equation in terms of $\tau$-functions. Elimination of $\tau$-functions from the resulting system leads to another nonlinear equation, which is a ``modified'' version of the original equation. The procedure therefore yields Miura transformations. In this letter, we illustrate this approach by reproducing previously known Miura transformations and constructing new ones.Comment: 7 pages in TeX, to appear in Phys. Letts.