817 research outputs found

    Energy Transition Dynamics; Understanding Policy Resistance in the Dutch Energy System

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    Contains fulltext : 127511pre.pdf (preprint version ) (Open Access)Various countries seek to establish an energy transition, a structural change towards a more sustainable energy system. Countries implement a combination of energy policies aimed at establishing an energy transition, but these policies frequently result in unintended negative consequences. This study provides an attempt to unravel the complexity of the Dutch energy transition. We present a model of the Dutch energy transition, showing its various components and their interrelations. The model is based on eight group model building workshops in which a total of 96 stakeholders in the Dutch energy transition participated. In each workshop, a variety of stakeholders engaged in the collaborative construction of a model that explains the current progress of the energy transition. In this paper, we aggregate these eight models into one overarching model, which we lay out step by step. The model shows how technological, ecological, social, economic, and political aspects of the energy transition influence each other either directly or indirectly. We discuss several policy implications, with a focus on reducing unintended negative consequences.32nd International Conference of the System Dynamics Societ

    A BRST Analysis of WW-symmetries

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    We perform a classical BRST analysis of the symmetries corresponding to a generic wNw_N-algebra. An essential feature of our method is that we write the wNw_N-algebra in a special basis such that the algebra manifestly has a ``nested'' set of subalgebras vNN⊂vNN−1⊂⋯⊂vN2≡wNv_N^N \subset v_N^{N-1} \subset \dots \subset v_N^2 \equiv w_N where the subalgebra vNi (i=2,…,N)v_N^i\ (i=2, \dots ,N) consists of generators of spin s={i,i+1,…,N}s=\{i,i+1,\dots ,N\}, respectively. In the new basis the BRST charge can be written as a ``nested'' sum of N−1N-1 nilpotent BRST charges. In view of potential applications to (critical and/or non-critical) WW-string theories we discuss the quantum extension of our results. In particular, we present the quantum BRST-operator for the W4W_4-algebra in the new basis. For both critical and non-critical WW-strings we apply our results to discuss the relation with minimal models.Comment: 32 pages, UG-4/9

    The Importance of Cognitive Diversity for Sustaining the Commons

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    Cognitive abilities underpin the capacity of individuals to build models of their environment and make decisions about how to govern resources. Here, we test the functional intelligences proposition that functionally diverse cognitive abilities within a group are critical to govern common pool resources. We assess the effect of two cognitive abilities, social and general intelligence, on group performance on a resource harvesting and management game involving either a negative or a positive disturbance to the resource base. Our results indicate that under improving conditions (positive disturbance) groups with higher general intelligence perform better. However, when conditions deteriorate (negative disturbance) groups with high competency in both general and social intelligence are less likely to deplete resources and harvest more. Thus, we propose that a functional diversity of cognitive abilities improves how effectively social groups govern common pool resources, especially when conditions deteriorate and groups need to re-evaluate and change their behaviors

    Impact ionization in GaAs: a screened exchange density functional approach

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    Results are presented of a fully ab-initio calculation of impact ionization rates in GaAs within the density functional theory framework, using a screened-exchange formalism and the highly precise all-electron full-potential linearized augmented plane wave (FLAPW) method. The calculated impact ionization rates show a marked orientation dependence in {\bf k} space, indicating the strong restrictions imposed by the conservation of energy and momentum. This anisotropy diminishes as the impacting electron energy increases. A Keldysh type fit performed on the energy-dependent rate shows a rather soft edge and a threshold energy greater than the direct band gap. The consistency with available Monte Carlo and empirical pseudopotential calculations shows the reliability of our approach and paves the way to ab-initio calculations of pair production rates in new and more complex materials.Comment: 11 pages, 4 figures, Submitted to Phys. Rev.

    Coordination and chemical effects on the structural, electronic and magnetic properties in Mn pnictides

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    Simple structures of MnX binary compounds, namely hexagonal NiAs and zincblende, are studied as a function of the anion (X = Sb, As, P) by means of the all-electron FLAPW method within local spin density and generalized gradient approximations. An accurate analysis of the structural, electronic and magnetic properties reveals that the cubic structure greatly favours the magnetic alignment in these compounds leading to high magnetic moments and nearly half-metallic behaviour for MnSb and MnAs. The effect of the anion chemical species is related to both its size and the possible hybridization with the Mn dd states; both contributions are seen to hinder the magnitude of the magnetic moment for small and light anions. Our results are in very good agreement with experiment - where available - and show that the generalized gradient approximation is essential to correctly recover both the equilibrium volume and magnetic moment.Comment: 18 pages and 4 figures, Latex-file, submitted to Phys.Rev.

    Investigating the topology of interacting networks - Theory and application to coupled climate subnetworks

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    Network theory provides various tools for investigating the structural or functional topology of many complex systems found in nature, technology and society. Nevertheless, it has recently been realised that a considerable number of systems of interest should be treated, more appropriately, as interacting networks or networks of networks. Here we introduce a novel graph-theoretical framework for studying the interaction structure between subnetworks embedded within a complex network of networks. This framework allows us to quantify the structural role of single vertices or whole subnetworks with respect to the interaction of a pair of subnetworks on local, mesoscopic and global topological scales. Climate networks have recently been shown to be a powerful tool for the analysis of climatological data. Applying the general framework for studying interacting networks, we introduce coupled climate subnetworks to represent and investigate the topology of statistical relationships between the fields of distinct climatological variables. Using coupled climate subnetworks to investigate the terrestrial atmosphere's three-dimensional geopotential height field uncovers known as well as interesting novel features of the atmosphere's vertical stratification and general circulation. Specifically, the new measure "cross-betweenness" identifies regions which are particularly important for mediating vertical wind field interactions. The promising results obtained by following the coupled climate subnetwork approach present a first step towards an improved understanding of the Earth system and its complex interacting components from a network perspective

    Enacting corporate governance of health care safety and quality: a dramaturgy of hospital boards in England

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    The governance of patient safety is a challenging concern for all health systems. Yet, while the role of executive Boards receives increased scrutiny, the area remains theoretically and methodologically underdeveloped. Specifically, we lack a detailed understanding of the performative aspects at play: what Board members say and do to discharge their accountabilities for patient safety. This article draws on qualitative data from overt non-participant observation of four NHS hospital Foundation Trust Boards in England. Applying a dramaturgical framework to explore scripting, setting, staging and performance, we found important differences between case study sites in the performative dimensions of processing and interpretation of infection control data. We detail the practices associated with these differences - the legitimation of current performance, the querying of data classification, and the naming and shaming of executives – to consider their implications

    Hall Effect and Resistivity in High-Tc Superconductors: The Conserving Approximation

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    The Hall coefficient (R_H) of high-Tc cuprates in the normal state shows the striking non-Fermi liquid behavior: R_H follows a Curie-Weiss type temperature dependence, and |R_H|>>1/|ne| at low temperatures in the under-doped compounds. Moreover, R_H is positive for hole-doped compounds and is negative for electron-doped ones, although each of them has a similar hole-like Fermi surface. In this paper, we give the explanation of this long-standing problem from the standpoint of the nearly antiferromagnetic (AF) Fermi liquid. We consider seriously the vertex corrections for the current which are indispensable to satisfy the conservation laws, which are violated within the conventional Boltzmann transport approximation. The obtained total current J_k takes an enhanced value and is no more perpendicular to the Fermi surface due to the strong AF fluctuations. By virtue of this mechanism, the anomalous behavior of R_H in high-Tc cuprates is neutrally explained. We find that both the temperature and the (electron, or hole) doping dependences of R_H in high-T_c cuprates are reproduced well by numerical calculations based on the fluctuation-exchange (FLEX) approximation, applied to the single-band Hubbard model. We also discuss the temperature dependence of R_H in other nearly AF metals, e.g., V_2O_3, kappa-BEDT-TTF organic superconductors, and heavy fermion systems close to the AF phase boundary.Comment: 19 pages, to appear in Phys. Rev. B, No.59, Vol.22, 199
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