The simulation reproducibility crisis. Can reporting guidelines help?

Modern computational science is gripped by a reproducibility crisis. This means that the benefits of computational research are hard if not impossible to realise. The field of computer simulation is not immune to this crisis. The complexity of simulation models leads to difficulties in reporting the internal logic and data to an extent where it is often difficult to reproduce the model and its results. We describe the reproducibility crisis and introduce the Strengthening The Reporting of Empirical Simulation Studies (STRESS) guidelines; a standardised checklist approach to improve the reporting of discrete-event simulation, system dynamics and agent-based simulation models. We argue that STRESS provides a partial solution to the reproducibility crisis in computer simulation

Lessons learned from the Youngstown, Ohio induced earthquake sequence from January 2011 to January 2012

The Youngstown earthquake sequence of 2011 is one of the clearest examples of inadvertently induced seismicity for which detailed documentation is available. In this paper, we investigate (i) likely stress states in the vicinity of the injection well, (ii) a range of likely permeability scenarios, and (iii) relatively simple methods by which induced seismicity can be evaluated and mitigated. We use relocated hypocenters from the seismic sequence to construct a basement fault structure, which is then used to serve as a reference surface within the basement, and on which we calculate the effects of pore pressure changes induced by the injection activities of the Northstar #1 injection well. We also deduce an in situ (pre-injection) strike-slip stress regime, where σ2 ≈ σ3, and it is consistent with both recent earthquake data and published stress estimates for the region. If the reactivation characteristics of the basement are known or assumed, a critical or threshold slip tendency can be determined and the basement faults can be analyzed for the likelihood of reactivation in a perturbed pore pressure field. Comparison of well injection pressures and simulated pore pressure perturbations within the basement below the injection well indicates that permeability anisotropy is necessary to generate sufficient pore pressure perturbation to induce fault reactivation. Simulations of the well's injection history show that our estimate of in situ stress state, coupled with a highly anisotropic permeability structure, can generate sufficient pore pressure perturbation on the inferred basement structure to cause reactivation, potentially slipping an area of approximately 4 × 105 m2

New Basal Synapsid Supports Laurasian Origin for Therapsids

The distant evolutionary ancestry of mammals is documented by a rich therapsid fossil record. While sphenacodontid synapsids are considered the sister−group of therapsids, the place of origin of therapsids is an enigma, largely because of a long standing morphological and temporal gap (Olson’s Gap) in their fossil record. We describe a new large predatory synapsid, Raranimus dashankouensis gen. et sp. nov., from the Middle Permian of Dashankou in China which has a unique combination of therapsid and sphenacodontid features. This specimen is of great significance asit is a basal therapsid which is the sister taxon to all other therapsids. The fact that it was found in association with Early Permian tetrapods (Anakamacops and Belebey) suggests that it is the oldest therapsid and provides the first evidence of therapsid−bearing rocks which cover Olson’s Gap. It further supports that therapsids may have had a Laurasian rather than Gondwanan origin