230 research outputs found
Comparing Petri Net and Activity Diagram Variants for Workflow Modelling:A Quest for Reactive Petri Nets
Petri net variants are widely used as a workflow modelling technique. Recently, UMLa ctivity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri nets and on the surface, one may think that they are variants of each other. To substantiate or deny this claim, we need to formalise the intended semantics of activity diagrams and then compare this with various Petri net semantics. In previous papers we have defined two formal semantics for UMLact ivity diagrams that are intended for workflow modelling. In this paper, we discuss the design choices that underlie these two semantics and investigate whether these design choices can be met in low-level and high-level Petri net semantics. We argue that the main difference between the Petri net semantics and our semantics of UML act ivity diagrams is that the Petri net semantics models resource usage of closed, active systems that are non-reactive, whereas our semantics of UMLact ivity diagrams models open, reactive systems. Since workflow systems are open, reactive systems, we conclude that Petri nets cannot model workflows accurately, unless they are extended with a syntax and semantics for reactivity
Branding the City: The Democratic Legitimacy of a New Mode of Governance
__Abstract__
Place branding has been used to influence ideas concerning communities and districts, especially in regeneration programmes. This article approaches branding as a new governance strategy for managing perceptions. Considering the popular criticism that branding is a form of spin that prevents the public from gaining a proper understanding of their government's policies, this article focuses on the democratic legitimacy of branding in urban governance. The branding of two urban communities in the Netherlands is examined empirically in terms of input legitimacy, throughput legitimacy and output legitimacy. The research shows how the democratic legitimacy of branding varies in the two cases. In one case, branding largely excluded citizens, whereas in the other case there was limited citizen participation. The article indicates that, although branding can potentially be a participatory process in which the feelings and emotions of citizens are included, this potential is not always fully realised in practice
Persistent anthrax as a major driver of wildlife mortality in a tropical rainforest
Anthrax is a globally important animal disease and zoonosis. Despite this, our current knowledge of anthrax ecology is largely limited to arid ecosystems, where outbreaks are most commonly reported. Here we show that the dynamics of an anthrax-causing agent, Bacillus cereus biovar anthracis, in a tropical rainforest have severe consequences for local wildlife communities. Using data and samples collected over three decades, we show that rainforest anthrax is a persistent and widespread cause of death for a broad range of mammalian hosts. We predict that this pathogen will accelerate the decline and possibly result in the extirpation of local chimpanzee (Pan troglodytes verus) populations. We present the epidemiology of a cryptic pathogen and show that its presence has important implications for conservation
The Effects of Media and their Logic on Legitimacy Sources within Local Governance Networks: A Three-Case Comparative Study
__Abstract__
Although theoretical and empirical work on the democratic legitimacy of
governance networks is growing, little attention has been paid to the impact of mediatisation
on democracies. Media have their own logic of news-making led by the media’s rules,
aims, production routines and constraints, which affect political decision-making processes.
In this article, we specifically study how media and their logic affect three
democratic legitimacy sources of political decision-making within governance networks:
voice, due deliberation and accountability. We conducted a comparative case study of
three local governance networks using a mixed method design, combining extensive
qualitative case studies, interviews and a quantitative content analysis of media reports.
In all three cases, media logic increased voice possibilities for citizen groups.
Furthermore, it broadened the deliberation process, although this did not improve the
quality of this process per se, because the media focus on drama and negativity. Finally,
media logic often pushed political authorities into a reactive communication style as they
had to fight against negative images in the media. Proactive communication about
projects, such as public relation (PR) strategies and branding, is difficult in such a
media landscape
Resonant two-site tunnelling dynamics of bosons in a tilted optical superlattice
We study the non-equilibrium dynamics of a 1D Bose-Hubbard model in a
gradient potential and a superlattice, beginning from a deep Mott insulator
regime with an average filling of one particle per site. Studying a quench that
is near resonance to tunnelling of the particles over two lattice sites, we
show how a spin model emerges consisting of two coupled Ising chains that are
coupled by interaction terms in a staggered geometry. We compare and contrast
the behavior in this case with that in a previously studied case where the
resonant tunnelling was over a single site. Using optimized tensor network
techniques to calculate finite temperature behavior of the model, as well as
finite size scaling for the ground state, we conclude that the universality
class of the phase transition for the coupled chains is that of a tricritical
Ising point. We also investigate the out-of-equilibrium dynamics after the
quench in the vicinity of the resonance and compare dynamics with recent
experiments realized without the superlattice geometry. This model is directly
realizable in current experiments, and reflects a new general way to realize
spin models with ultracold atoms in optical lattices.Comment: 12 pages, 6 figure
Farmer-Scientist Knowledge Exchange
The last 25 years has seen a paradigm shift in the understanding of the nature of knowledge and how it is
exchanged in the agricultural context. A changing backdrop, with the move towards multi-functional land
management, persistent environmental problems and the search for sustainable agricultural approaches, has
brought new challenges. At the same time the research agenda on knowledge has changed as an era of
positivism, during which science and scientific experts were given unrivalled authority, was challenged by
social studies of science that began to question the superiority of scientific knowledge, and value alternative
forms of knowledge such as those held by farmers. Theory and practice of knowledge exchange in agriculture
has evolved in line with this, shifting from a linear model of knowledge transfer to a perspective that
integrates knowledge from multiple actors through facilitation and participation and emphasises learning in a
social context
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