Detailed Structure of a CDW in a Quenched Random Field

Using high resolution x-ray scattering, we have measured the structure of the Q_1 CDW in Ta-doped NbSe_3. Detailed line shape analysis of the data demonstrates that two length scales are required to describe the phase-phase correlation function. Phase fluctuations with wavelengths less than a new length scale $a$ are suppressed and this $a$ is identified with the amplitude coherence length. We find that xi_a* = 34.4 \pm 10.3 angstroms. Implications for the physical mechanisms responsible for pinning are discussed.Comment: revtex 3.0, 3 postscript uuencoded figure

Defects, order, and hysteresis in driven charge-density waves

We model driven two-dimensional charge-density waves in random media via a modified Swift-Hohenberg equation, which includes both amplitude and phase fluctuations of the condensate. As the driving force is increased, we find that the defect density first increases and then decreases. Furthermore, we find switching phenomena, due to the formation of channels of dislocations. These results are in qualitative accord with recent dynamical x-ray scattering experiments by Ringlandet al. and transport experiments by Lemay et al.Comment: Accepted to Phys. Rev. Lett. Click here for "http://www-theory.mpip-mainz.mpg.de/~karttune/CDW/", movies of driven CDW

Envisioning sustainable tourism futures: An evaluation of the futures wheel method

Methods for researching the future have grown both in variety and rigour, offering new opportunities for understanding sustainable tourism. This paper discusses the value of futures research as a tool for envisioning and planning sustainable tourism futures but observes that there is greater potential for the use of futures methods in tourism. The aim of this paper is to evaluate the usefulness of a particular method known as the futures wheel as a sustainable planning tool for tourism decision makers and researchers. The futures wheel method is combined with a grounded theory approach to capture and distil the tacit knowledge of three 'expert' think tanks. The evaluation suggests that the futures wheel is a useful tool for researching sustainable tourism futures but that its potential may be enhanced if it can be combined with other futures research methods

Collaborative virtual environment to facilitate game design evaluation with children with ASC

Involvement of children with autism spectrum conditions (ASC) in the design of new educational technology is becoming more prevalent. Despite potential barriers due to communication and ideation difficulties for children with ASC, adapted participatory design methods can successfully facilitate their direct involvement. Nonetheless, methods requiring face-to-face communication can still be difficult for children with ASC and research suggests that technology mediation could facilitate their contribution. This study explores the use of collaborative virtual environments (CVEs) as a medium through which students evaluated existing computer games and offered suggestions for game development. CVEs in which the users were represented by (a) avatars and (b) video-pods were compared to a face-to-face condition. Twelve typically developing (aged 8-9 years), 12 higher ability ASC (12-14) and 4 lower ability ASC children (12-14) participated. All student groups preferred the video-pod CVE and students with ASC were generally better able to contribute effectively through this medium than face-to-face

Comparing political futures: the rise and use of scenarios in future-oriented area studies

The predictive ability of scholars of politics has long been a subject of theoretical debate and methodological development. In theoretical debate, prediction represents a central issue regarding the extent to which the study of politics is scientific. In methodological development, much effort and resource have been devoted to a diverse range of predictive approaches, with varying degrees of success. Expectations that scholars forecast accurately come as much from the policy and media worlds as from the academy. Since the end of the Cold War, scenario development has become prevalent in future-oriented research by area studies scholars. This approach is long due critical re-assessment. For all its strengths as a policy tool, scenario development tends towards a bounded methodology, driving the process of anticipating futures along predetermined paths into a standardised range of options, and paying insufficient attention to theoretical and contextual understandings available within the relevant scholarly disciplines

Understanding Organizational Evolution : Toward a Research Agenda using Generalized Darwinism

The terms ‘evolution’ and ‘coevolution’ are widely used in organization studies but rarely defined. Often it is unclear whether they refer to single entities or populations. When specific evolutionary processes are suggested, the labelling is often misleading. For example, in the debate over the roles of individual adaptation and competitive selection, the ‘selectionist’ position of Michael Hannan and John Freeman (1989), which emphasizes the role of selection and stress the limits of individual firm adaptability, is often described as ‘Darwinian’ whereas opposing views that emphasise adaptability are described as ‘Lamarckian’. But these labels are not strictly dichotomous. Scholars have shown that core Darwinian principles, resulting from abstract ontological communality rather than analogy, apply to social evolution. This opens up a research agenda using the principles of generalized Darwinism and the replicator-interactor framework to help understand the evolution of organizations. Some illustrations of the conceptual value of this approach are provided, including understanding the entwinement of selection and adaptation, the nature and role of organizational routines, the place of strategic choice and the growth of organizational complexity. The framework of generalized Darwinism also helps to bridge apparently divergent perspectives in the business strategy and organizational ecology literatures.Peer reviewedFinal Accepted Versio