Looking back to see the future: building nuclear power plants in Europe

The so-called ‘nuclear renaissance’ in Europe is promulgated by the execution of two large engineering projects involving the construction of two European Pressurized Reactors (EPRs) in Flamanville, France and Olkiluoto in Finland. As both projects have faced budget overruns and delays, this paper analyses their governance and history to derive lessons useful for the construction of future projects. Analysis indicates that the reasons for these poor outcomes are: overoptimistic estimations, first-of-a-kind (FOAK) issues and undervaluation of regulation requirements. These pitfalls have the potential to impact on many other engineering construction projects and highlight fruitful areas of further research into project performance

Complex Network Analysis of State Spaces for Random Boolean Networks

We apply complex network analysis to the state spaces of random Boolean networks (RBNs). An RBN contains $N$ Boolean elements each with $K$ inputs. A directed state space network (SSN) is constructed by linking each dynamical state, represented as a node, to its temporal successor. We study the heterogeneity of an SSN at both local and global scales, as well as sample-to-sample fluctuations within an ensemble of SSNs. We use in-degrees of nodes as a local topological measure, and the path diversity [Phys. Rev. Lett. 98, 198701 (2007)] of an SSN as a global topological measure. RBNs with $2 \leq K \leq 5$ exhibit non-trivial fluctuations at both local and global scales, while K=2 exhibits the largest sample-to-sample, possibly non-self-averaging, fluctuations. We interpret the observed ``multi scale'' fluctuations in the SSNs as indicative of the criticality and complexity of K=2 RBNs. ``Garden of Eden'' (GoE) states are nodes on an SSN that have in-degree zero. While in-degrees of non-GoE nodes for $K>1$ SSNs can assume any integer value between 0 and $2^N$, for K=1 all the non-GoE nodes in an SSN have the same in-degree which is always a power of two

On the properties of cycles of simple Boolean networks

We study two types of simple Boolean networks, namely two loops with a cross-link and one loop with an additional internal link. Such networks occur as relevant components of critical K=2 Kauffman networks. We determine mostly analytically the numbers and lengths of cycles of these networks and find many of the features that have been observed in Kauffman networks. In particular, the mean number and length of cycles can diverge faster than any power law.Comment: 10 pages, 8 figure

Reflections on phronetic social science: a dialogue between Stewart Clegg, Bent Flyvbjerg and Mark Haugaard

Clegg, Flyvbjerg and Haugaard debate the strengths and weaknesses of a Foucauldian-Nietzschean critique of power compared to a tradition exemplified by Lukes and Habermas. Flyvbjerg and Clegg argue that the pursuit of universal normative principles and of rationality without power may lead to oppressive utopian thinking. Drawing on the Aristotelian tradition of phronesis, they propose a contextualist form of critique that situates itself in analysis of local practices to render domination transparent and open to change. While Haugaard accepts there cannot be a universal view that transcends the particularities of context, he argues that the phronetic approach is crypto-normative because it implicitly presupposes unacknowledged liberal normative premises; moreover, any use of 'truth' as a criterion follows Enlightenment principles of verification. © 2014 Taylor & Francis

The phase diagram of random threshold networks

Threshold networks are used as models for neural or gene regulatory networks. They show a rich dynamical behaviour with a transition between a frozen and a chaotic phase. We investigate the phase diagram of randomly connected threshold networks with real-valued thresholds h and a fixed number of inputs per node. The nodes are updated according to the same rules as in a model of the cell-cycle network of Saccharomyces cereviseae [PNAS 101, 4781 (2004)]. Using the annealed approximation, we derive expressions for the time evolution of the proportion of nodes in the "on" and "off" state, and for the sensitivity $\lambda$. The results are compared with simulations of quenched networks. We find that for integer values of h the simulations show marked deviations from the annealed approximation even for large networks. This can be attributed to the particular choice of the updating rule.Comment: 8 pages, 6 figure

Dry and wet interfaces: Influence of solvent particles on molecular recognition

We present a coarse-grained lattice model to study the influence of water on the recognition process of two rigid proteins. The basic model is formulated in terms of the hydrophobic effect. We then investigate several modifications of our basic model showing that the selectivity of the recognition process can be enhanced by considering the explicit influence of single solvent particles. When the number of cavities at the interface of a protein-protein complex is fixed as an intrinsic geometric constraint, there typically exists a characteristic fraction that should be filled with water molecules such that the selectivity exhibits a maximum. In addition the optimum fraction depends on the hydrophobicity of the interface so that one has to distinguish between dry and wet interfaces.Comment: 11 pages, 7 figure

Random sampling vs. exact enumeration of attractors in random Boolean networks

We clarify the effect different sampling methods and weighting schemes have on the statistics of attractors in ensembles of random Boolean networks (RBNs). We directly measure cycle lengths of attractors and sizes of basins of attraction in RBNs using exact enumeration of the state space. In general, the distribution of attractor lengths differs markedly from that obtained by randomly choosing an initial state and following the dynamics to reach an attractor. Our results indicate that the former distribution decays as a power-law with exponent 1 for all connectivities $K>1$ in the infinite system size limit. In contrast, the latter distribution decays as a power law only for K=2. This is because the mean basin size grows linearly with the attractor cycle length for $K>2$, and is statistically independent of the cycle length for K=2. We also find that the histograms of basin sizes are strongly peaked at integer multiples of powers of two for $K<3$

Bent Flyvbjerg: power and project management – an appreciation

© 2008, © Emerald Group Publishing Limited. Purpose – The purpose of this paper is to provide a critique of Bent Flyybjerg's work that has high relevance to the project management (PM) literature. Design/methodology/approach – The paper takes the form of a narrative with argument and analysis. Findings – The paper challenges readers, PM academics and practitioners to view PM with a political perspective. This paper was delivered at the ICAN 2007 Conference (which is the focus of this issue), which was entitled “Mission Control: Power, Knowledge and Collaboration in Project Practice.” Originality/value – This paper triggers and sustains the debate about the influence of power and its unintended consequences that may affect projects. The review raises PM issues worthy of consideration that are often neglected

Topological Evolution of Dynamical Networks: Global Criticality from Local Dynamics

We evolve network topology of an asymmetrically connected threshold network by a simple local rewiring rule: quiet nodes grow links, active nodes lose links. This leads to convergence of the average connectivity of the network towards the critical value $K_c =2$ in the limit of large system size $N$. How this principle could generate self-organization in natural complex systems is discussed for two examples: neural networks and regulatory networks in the genome.Comment: 4 pages RevTeX, 4 figures PostScript, revised versio