Flexible transition strategies towards future well-to-wheel chains: an evolutionary modelling approach

Well to wheel (WTW) analyses mainly focus on alternative road fuel/vehicle systems that are very different from the current crude oil based individual transport system. A large share of WTW chains evaluated require changes in the energy source, new fuel production facilities, different fuel distribution systems and also modifications of the vehicles. An immediate transition to such a new system would be an unprecedented technological discontinuity. Historical examples of successful technological changes are characterized by stepwise transitions of subsystems. In this paper, we present a model that identifies likely sequences of stepwise transitions in analogy to the fitness landscape model in evolutionary biology. Applying this methodology allows for a dynamic interpretation of otherwise static WTW information. We show that sequences of transitions are path dependent, so that current decisions predetermine the future WTW system. We, therefore, argue that flexible initial transition steps that allow for different transition paths later on are favorable. Results suggest that improvements of vehicle technologies are most flexible if decision makers focus on decreasing WTW energy requirements. A full transition to diesel, as a first step, is advisable if WTW greenhouse gases should be reduced.Alternative fuels, Hydrogen, Lock-in, Fitness-landscape

A complex systems methodology to transition management

There is a general sense of urgency that major technological transitions are required for sustainable development. Such transitions are best perceived as involving multiple transition steps along a transition path. Due to the path dependent and irreversible nature of innovation in complex technologies, an initial transition step along some preferred path may cut off paths that later may turn out to be more desirable. For these reasons, initial transition steps should allow for future flexibility, where we define flexibility as robustness regarding changing evidence and changing preferences. We propose a technology assessment methodology that identifies the flexibility of initial transition steps in complex technologies. We illustrate our methodology by an empirical application to 2646 possible future car systems.NK-model, complexity, flexibility, irreversibility, path dependence, transition path, transition management, sustainable development, car technology

Mixed methodology in human brain research: integrating MRI and histology

Postmortem magnetic resonance imaging (MRI) can provide a bridge between histological observations and the in vivo anatomy of the human brain. Approaches aimed at the co-registration of data derived from the two techniques are gaining interest. Optimal integration of the two research fields requires detailed knowledge of the tissue property requirements for individual research techniques, as well as a detailed understanding of the consequences of tissue fixation steps on the imaging quality outcomes for both MRI and histology. Here, we provide an overview of existing studies that bridge between state-of-the-art imaging modalities, and discuss the background knowledge incorporated into the design, execution and interpretation of postmortem studies. A subset of the discussed challenges transfer to animal studies as well. This insight can contribute to furthering our understanding of the normal and diseased human brain, and to facilitate discussions between researchers from the individual disciplines

Phenomenological approach to non-linear Langevin equations

In this paper we address the problem of consistently construct Langevin equations to describe fluctuations in non-linear systems. Detailed balance severely restricts the choice of the random force, but we prove that this property together with the macroscopic knowledge of the system is not enough to determine all the properties of the random force. If the cause of the fluctuations is weakly coupled to the fluctuating variable, then the statistical properties of the random force can be completely specified. For variables odd under time-reversal, microscopic reversibility and weak coupling impose symmetry relations on the variable-dependent Onsager coefficients. We then analyze the fluctuations in two cases: Brownian motion in position space and an asymmetric diode, for which the analysis based in the master equation approach is known. We find that, to the order of validity of the Langevin equation proposed here, the phenomenological theory is in agreement with the results predicted by more microscopic models.Comment: LaTex file, 2 figures available upon request, to appear in Phys.Rev.