Resilience trinity: Safeguarding ecosystem functioning and services across three different time horizons and decision contexts

Ensuring ecosystem resilience is an intuitive approach to safeguard the functioning of ecosystems and hence the future provisioning of ecosystem services (ES). However, resilience is a multi‐faceted concept that is difficult to operationalize. Focusing on resilience mechanisms, such as diversity, network architectures or adaptive capacity, has recently been suggested as means to operationalize resilience. Still, the focus on mechanisms is not specific enough. We suggest a conceptual framework, resilience trinity, to facilitate management based on resilience mechanisms in three distinctive decision contexts and time‐horizons: 1) reactive, when there is an imminent threat to ES resilience and a high pressure to act, 2) adjustive, when the threat is known in general but there is still time to adapt management and 3) provident, when time horizons are very long and the nature of the threats is uncertain, leading to a low willingness to act. Resilience has different interpretations and implications at these different time horizons, which also prevail in different disciplines. Social ecology, ecology and engineering are often implicitly focussing on provident, adjustive or reactive resilience, respectively, but these different notions of resilience and their corresponding social, ecological and economic tradeoffs need to be reconciled. Otherwise, we keep risking unintended consequences of reactive actions, or shying away from provident action because of uncertainties that cannot be reduced. The suggested trinity of time horizons and their decision contexts could help ensuring that longer‐term management actions are not missed while urgent threats to ES are given priority

The emission of X-rays by fission fragments

Approximately 5% of the γ-ray transitions in fission fragments are internally converted, giving rise to X-rays. X-ray energies are characteristic of Z, but yields depend strongly and not smoothly on Z and A of the fragments and on time. If these biases can be accepted, X-rays can be used to identify the atomic number of fission fragments. More generally, internal conversion and X-ray emission must be interpreted in the context of detailed knowledge of γ-ray transitions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43110/1/10967_2005_Article_BF02039468.pd

Gas cooled fast reactor benchmark critical assembly

The GCFR Phase I assembly is the initial Gas-Cooled Fast Reactor Benchmark assembly on the ZPR-9 reactor at Argonne National Laboratory. It represents the first full scale mockup of a GCFR ever assembled. It is a clean, simple geometry benchmark reference for the 300 MW(e) GCFR Demonstration Plant designed by General Atomic Company. A description and the evaluated specifications (zero-excess reactivity critical mass and dimensions) of the benchmark assembly are presented. (auth

S.: Guaranteed termination in the verification of LTL properties of non-linear robust discrete time hybrid systems

Abstract. We present a novel approach to the automatic verification of LTL requirements of non-linear discrete-time hybrid systems. The verification tool uses an interval-based constraint solver for non-linear robust constraints to compute incrementally refined abstractions. Although the problem is undecidable, we prove termination of abstraction refinement based verification of such properties for the class of robust non-linear hybrid systems, thus significantly extending previous semi-decidability results. We argue, that safety critical control applications are robust hybrid systems. We give first results on the application of this approach to a variant of an aircraft collision avoidance protocol.

Between a rock and a hard place: Environmental and engineering considerations when designing coastal defence structures

Coastal defence structures are proliferating as a result of rising sea levels and stormier seas.With the realisation that most coastal infrastructure cannot be lost or removed, research is required into ways that coastal defence structures can be built to meet engineering requirements, whilst also providing relevant ecosystem services\u2014 so-called ecological engineering. This approach requires an understanding of the types of assemblages and their functional roles that are desirable and feasible in these novel ecosystems. We review the major impacts coastal defence structures have on surrounding environments and recent experiments informing building coastal defences in a more ecologically sustainable manner. We summarise research carried out during the THESEUS project (2009\u20132014) which optimised the design of coastal defence structures with the aim to conserve or restore native species diversity. Native biodiversity could be manipulated on defence structures through various interventions: we created artificial rock pools, pits and crevices on breakwaters; we deployed a precast habitat enhancement unit in a coastal defence scheme; we tested the use of a mixture of stone sizes in gabion baskets; and we gardened native habitat-forming species, such as threatened canopy-forming algae on coastal defence structures. Finally, we outline guidelines and recommendations to provide multiple ecosystem services while maintaining engineering efficacy. This work demonstrated that simple enhancement methods can be costeffective measures to manage local biodiversity. Care is required, however, in the wholesale implementation of these recommendations without full consideration of the desired effects and overall management goals