1,098 research outputs found

    A Semantics for the Essence of React

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    Motivations of volunteers in Danish grazing organisations

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    Global biodiversity is under pressure from human activities, and despite the expansion of protected areas, investment in nature conservation and restoration, and allocation of economic resources for managing existing conservation is insufficient. Therefore, volunteers can play an important role as a resource in nature conservation projects if their recreational activities interact with the objectives of nature management. In recent years, the number of volunteers in conservation work has increased in Denmark, with more people volunteering to contribute to nature conservation projects. Ensuring that volunteers remain motivated and engaged is crucial to the success of such conservation projects. In this study, we evaluate the motivation among members of grazing organisations, an activity which represent the most prominent voluntary nature conservation initiatives in Denmark. We apply exploratory factor analysis (EFA) and ordinal regression to analyse survey data from 25 Danish grazing organisations. We find that five motivational factors are determining the engagement of the volunteers, namely social, nature value, instrumental, identification, and personal benefit. Whereas the social, nature value and personal benefit are factors also identified in the existing literature, the instrumental and identification factors add new perspectives to the motivation of environmental volunteers. We find that place attachment is an important driver, and that the chairpersons/coordinators of the grazing organisations especially emphasized the sharing of values and knowledge with their members as a driver. Last, volunteers were reluctant to support the idea of forming a more formal setup in terms of a “Grazing organisation union”

    Advances in the theory of III-V Nanowire Growth Dynamics

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    Nanowire (NW) crystal growth via the vapour_liquid_solid mechanism is a complex dynamic process involving interactions between many atoms of various thermodynamic states. With increasing speed over the last few decades many works have reported on various aspects of the growth mechanisms, both experimentally and theoretically. We will here propose a general continuum formalism for growth kinetics based on thermodynamic parameters and transition state kinetics. We use the formalism together with key elements of recent research to present a more overall treatment of III_V NW growth, which can serve as a basis to model and understand the dynamical mechanisms in terms of the basic control parameters, temperature and pressures/beam fluxes. Self-catalysed GaAs NW growth on Si substrates by molecular beam epitaxy is used as a model system.Comment: 63 pages, 25 figures and 4 tables. Some details are explained more carefully in this version aswell as a new figure is added illustrating various facets of a WZ crysta

    On the estimation of normal copula discrete regression models using the continuous extension and simulated likelihood

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    The continuous extension of a discrete random variable is amongst the computational methods used for estimation of multivariate normal copula-based models with discrete margins. Its advantage is that the likelihood can be derived conveniently under the theory for copula models with continuous margins, but there has not been a clear analysis of the adequacy of this method. We investigate the asymptotic and small-sample efficiency of two variants of the method for estimating the multivariate normal copula with univariate binary, Poisson, and negative binomial regressions, and show that they lead to biased estimates for the latent correlations, and the univariate marginal parameters that are not regression coefficients. We implement a maximum simulated likelihood method, which is based on evaluating the multidimensional integrals of the likelihood with randomized quasi Monte Carlo methods. Asymptotic and small-sample efficiency calculations show that our method is nearly as efficient as maximum likelihood for fully specified multivariate normal copula-based models. An illustrative example is given to show the use of our simulated likelihood method

    Parallelisation of the PC Algorithm

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    Creating Landscapes of Practice through Sequential Learning - A New Vision for PBL

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    In the current conceptualisations of Problem Based Learning and how we practice it, the students are expected to possess the necessary academic competencies in order to study through PBL. However, a desk research reveals that students in many cases don't have the necessary understanding or conceptual comprehension of disciplines such as problem formulation, analysis, exploration, literature review etc., which prevents them from unfolding an explorative approach to their professional practice. This article thus discusses Dewey's concepts of sequential inquiry processes to create new forms of learning designs to bolden further students ability to work problem-based. The article discusses through the development of iterative learning design how structured sequences of activities can provide a descriptive language to qualify a methodology for PBL. The study is based on Educational Design Research (EDR) as the overarching framework where the methods of Design thinking inform the design activities through iterative processes. Through a period of two years a total of 400 students at the education of ATCM, at University College of Northern Denmark has participated. The data collection included results from observation, reflective portfolios and sound recordings from the students' group work in combination with sketches, drawing and artefacts from the iterative design process.

    Peer-Assisted Content Distribution with Random Linear Network Coding

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    Parallelization of the PC Algorithm

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    This paper describes a parallel version of the PC algorithm for learning the structure of a Bayesian network from data. The PC algorithm is a constraint-based algorithm consisting of fi ve steps where the first step is to perform a set of (conditional) independence tests while the remaining four steps relate to identifying the structure of the Bayesian network using the results of the (conditional) independence tests. In this paper, we describe a new approach to parallelization of the (conditional) independence testing as experiments illustrate that this is by far the most time consuming step. The proposed parallel PC algorithm is evaluated on data sets generated at random from five different real- world Bayesian networks. The results demonstrate that signi cant time performance improvements are possible using the proposed algorithm
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