1,795 research outputs found

    Critical systems heuristics

    Get PDF
    Critical systems heuristics (CSH) is a framework for reflective professional practice organised around the central tool of boundary critique. This paper, written jointly by the original developer, Werner Ulrich, and Martin Reynolds, an experienced practitioner of CSH, offers a systematic introduction to the idea and use of boundary critique. Its core concepts are explained in detail and their use is illustrated by means of two case studies from the domain of environmental planning and management. A particular focus is on working constructively with tensions between opposing perspectives as they arise in many situations of professional intervention. These include tensions such as ā€˜situationā€™ versus ā€˜systemā€™, ā€˜isā€™ versus ā€˜oughtā€™ judgements, concerns of ā€˜those involvedā€™ versus ā€˜those affected but not involvedā€™, stakeholdersā€™ ā€˜stakesā€™ versus ā€˜stakeholding issuesā€™, and others. Accordingly, boundary critique is presented as a participatory process of unfolding and questioning boundary judgements rather than as an expert-driven process of boundary setting. The paper concludes with a discussion of some essential skills and considerations regarding the practice of boundary critique. Parts of the account of the NRUA-Botswana study in Section 6.2 of the present paper are reproduced from an earlier publication by one of the authors (Reynolds 2007); we are grateful to the publishers of Edge Press, Point Reyes, CA, for granting us permission to reproduce this material. We do not need the systems concept at all if we are not interested in handling systems boundaries critically

    Exploring Swarm-Based Visual Effects

    Get PDF
    In this paper, we explore the visual effects of animated 2D line strokes and 3D cubes. A given 2D image is segmented into either 2D line strokes or 3D cubes. Each segmented object (i.e., line stroke or each cube) is initialised with the position and the colour of the corresponding pixel in the image. The program animates these objects using the boid framework. This simulates a flocking behavior of line strokes in a 2D space and cubes in a 3D space. In this implementation the animation runs in a cycle from the disintegration of the original image to a swarm of line strokes or 3D cubes, then the swarm moves about and then integrates back into the original image (an example clip has been uploaded to YouTube and can be viewed at https://www.youtube.com/watch?v=aV6h0VzTZ8)

    Ch. 6. Critical Systems Heuristics: The Idea and Practice of Boundary Critique

    Get PDF
    Critical systems heuristics (CSH) is a framework for reflective professional practice organised around the central tool of boundary critique. This chapter, written jointly by the original developer, Werner Ulrich, and Martin Reynolds, an experienced practitioner of CSH, offers a systematic introduction to the idea and use of boundary critique. Its core concepts are explained in detail and their use is illustrated by means of two case studies from the domain of environmental planning and management. A particular focus is on working constructively with tensions between opposing perspectives as they arise in many situations of professional intervention. These include tensions such as ā€˜situationā€™ versus ā€˜systemā€™, ā€˜isā€™ versus ā€˜oughtā€™ judgements, concerns of ā€˜those involvedā€™ versus ā€˜those affected but not involvedā€™, stakeholdersā€™ ā€˜stakesā€™ versus ā€˜stakeholding issuesā€™, and others. Accordingly, boundary critique is presented as a participatory process of unfolding and questioning boundary judgements rather than as an expert-driven process of boundary setting. The paper concludes with a discussion of some essential skills and considerations regarding the practice of boundary critique

    Chapter 1: Introducing systems approaches

    Get PDF
    The five approaches covered in Systems Approaches to Making Change ā€“ System Dynamics (SD) Viable Systems Model (VSM), Strategic Options Development and Analysis (SODA: with cognitive mapping), Soft Systems Methodology (SSM), and Critical Systems Heuristics (CSH) ā€“ are introduced. The rationale for their inclusion is described based on their (i) common historic emergence in dealing with complex situations of change and uncertainty, (ii) shared potential and actual constructivist use of the systems idea, and (iii) pedigree of adaptability and versatility of tools in working with other approaches to making change

    Dynamical modeling of collective behavior from pigeon flight data: flock cohesion and dispersion

    Get PDF
    Several models of flocking have been promoted based on simulations with qualitatively naturalistic behavior. In this paper we provide the first direct application of computational modeling methods to infer flocking behavior from experimental field data. We show that this approach is able to infer general rules for interaction, or lack of interaction, among members of a flock or, more generally, any community. Using experimental field measurements of homing pigeons in flight we demonstrate the existence of a basic distance dependent attraction/repulsion relationship and show that this rule is sufficient to explain collective behavior observed in nature. Positional data of individuals over time are used as input data to a computational algorithm capable of building complex nonlinear functions that can represent the system behavior. Topological nearest neighbor interactions are considered to characterize the components within this model. The efficacy of this method is demonstrated with simulated noisy data generated from the classical (two dimensional) Vicsek model. When applied to experimental data from homing pigeon flights we show that the more complex three dimensional models are capable of predicting and simulating trajectories, as well as exhibiting realistic collective dynamics. The simulations of the reconstructed models are used to extract properties of the collective behavior in pigeons, and how it is affected by changing the initial conditions of the system. Our results demonstrate that this approach may be applied to construct models capable of simulating trajectories and collective dynamics using experimental field measurements of herd movement. From these models, the behavior of the individual agents (animals) may be inferred

    Creativity and Autonomy in Swarm Intelligence Systems

    Get PDF
    This work introduces two swarm intelligence algorithms -- one mimicking the behaviour of one species of ants (\emph{Leptothorax acervorum}) foraging (a `Stochastic Diffusion Search', SDS) and the other algorithm mimicking the behaviour of birds flocking (a `Particle Swarm Optimiser', PSO) -- and outlines a novel integration strategy exploiting the local search properties of the PSO with global SDS behaviour. The resulting hybrid algorithm is used to sketch novel drawings of an input image, exploliting an artistic tension between the local behaviour of the `birds flocking' - as they seek to follow the input sketch - and the global behaviour of the `ants foraging' - as they seek to encourage the flock to explore novel regions of the canvas. The paper concludes by exploring the putative `creativity' of this hybrid swarm system in the philosophical light of the `rhizome' and Deleuze's well known `Orchid and Wasp' metaphor

    Introducing systems approaches

    Get PDF
    Systems Approaches to Managing Change brings together five systems approaches to managing complex issues, each having a proven track record of over 25 years. The five approaches are: System Dynamics (SD) developed originally in the late 1950s by Jay Forrester Viable Systems Model (VSM) developed originally in the late 1960s by Stafford Beer Strategic Options Development and Analysis (SODA: with cognitive mapping) developed originally in the 1970s by Colin Eden Soft Systems Methodology (SSM) developed originally in the 1970s by Peter Checkland Critical Systems Heuristics (CSH) developed originally in the late 1970s by Werner Ulrich

    The magnetic nature of disk accretion onto black holes

    Get PDF
    Although disk accretion onto compact objects - white dwarfs, neutron stars, and black holes - is central to much of high energy astrophysics, the mechanisms which enable this process have remained observationally elusive. Accretion disks must transfer angular momentum for matter to travel radially inward onto the compact object. Internal viscosity from magnetic processes and disk winds can in principle both transfer angular momentum, but hitherto we lacked evidence that either occurs. Here we report that an X-ray-absorbing wind discovered in an observation of the stellar-mass black hole binary GRO J1655-40 must be powered by a magnetic process that can also drive accretion through the disk. Detailed spectral analysis and modeling of the wind shows that it can only be powered by pressure generated by magnetic viscosity internal to the disk or magnetocentrifugal forces. This result demonstrates that disk accretion onto black holes is a fundamentally magnetic process.Comment: 15 pages, 2 color figures, accepted for publication in Nature. Supplemental materials may be obtained by clicking http://www.astro.lsa.umich.edu/~jonmm/nature1655.p

    Association between the c.*229C>T polymorphism of the topoisomerase IIb binding protein 1 (TopBP1) gene and breast cancer

    Get PDF
    Topoisomerase IIb binding protein 1 (TopBP1) is involved in cell survival, DNA replication, DNA damage repair and cell cycle checkpoint control. The biological function of TopBP1 and its close relation with BRCA1 prompted us to investigate whether alterations in the TopBP1 gene can influence the risk of breast cancer. The aim of this study was to examine the association between five polymorphisms (rs185903567, rs116645643, rs115160714, rs116195487, and rs112843513) located in the 30UTR region of the TopBP1 gene and breast cancer risk as well as allele-specific gene expression. Five hundred thirty-four breast cancer patients and 556 population controls were genotyped for these SNPs. Allele-specific Top- BP1 mRNA and protein expressions were determined by using real time PCR and western blotting methods, respectively. Only one SNP (rs115160714) showed an association with breast cancer. Compared to homozygous common allele carriers, heterozygous and homozygous for the T variant had significantly increased risk of breast cancer (adjusted odds ratio = 3.81, 95 % confidence interval: 1.63ā€“8.34, p = 0.001). Mean TopBP1 mRNA and protein expression were higher in the individuals with the CT or TT genotype. There was a significant association between the rs115160714 and tumor grade and stage. Most carriers of minor allele had a high grade (G3) tumors classified as T2-T4N1M0. Our study raises a possibility that a genetic variation of TopBP1 may be implicated in the etiology of breast cancer

    Thinking differently about sustainability: experiences from the UK Open University

    Get PDF
    Systems thinking is often invoked as a panacea for dealing with issues of sustainable development. Imperatives towards being more holistic - getting the bigger picture ā€“ are often coupled with a need for greater interdisciplinarity - joined-up-thinking ā€“ particularly amongst triple bottom line disciplines of economics, social studies and natural sciences. So why are systems thinking courses not more prevalent? And how might the teaching of systems thinking enhance the value of thinking differently about sustainable development? The Open University, UK, is a recognised international leader in the provision of Systems education for over 40 years. More recent experiences with the launch of a postgraduate Systems Thinking in Practice suite of qualifications at Certificate, Diploma, and Masters level, suggest an appetite for systems thinking amongst mature-age part-time students from a variety of professional backgrounds with an interest in learning for sustainability. This paper outlines three key features of the two core modules of the programme - epistemic understanding, active pedagogy, and design praxis. Significantly, these attributes have helped to complement rather than replace existing skill-sets amongst professionals from different sectors working in the field of sustainable development
    • ā€¦
    corecore