Software-Managed Read and Write Wear-Leveling for Non-Volatile Main Memory

In-memory wear-leveling has become an important research field for emerging non-volatile main memories over the past years. Many approaches in the literature perform wear-leveling by making use of special hardware. Since most non-volatile memories only wear out from write accesses, the proposed approaches in the literature also usually try to spread write accesses widely over the entire memory space. Some non-volatile memories, however, also wear out from read accesses, because every read causes a consecutive write access. Software-based solutions only operate from the application or kernel level, where read and write accesses are realized with different instructions and semantics. Therefore different mechanisms are required to handle reads and writes on the software level. First, we design a method to approximate read and write accesses to the memory to allow aging aware coarse-grained wear-leveling in the absence of special hardware, providing the age information. Second, we provide specific solutions to resolve access hot-spots within the compiled program code (text segment) and on the application stack. In our evaluation, we estimate the cell age by counting the total amount of accesses per cell. The results show that employing all our methods improves the memory lifetime by up to a factor of 955×

Potentially inappropriate prescribing in multimorbid and polymedicated older adults with AF:A Systematic Review and Meta-Analysis

Aim: Polypharmacy in multimorbid older patients with atrial fibrillation (AF) is a risk factor for potentially inappropriate prescribing (PIP). We aimed to systematically assess the evidence on the prevalence of PIP and its impact on adverse health outcomes in this patient group. Methods: A systematic search of the published peer-reviewed literature describing the prevalence of PIP and/or its association with adverse health outcomes in multimorbid (AF plus one comorbidity) and polymedicated (≥ 2 drugs) adults ≥ 65 years was done up to March 2023. A meta-analysis of the prevalence of PIP of (direct) oral anticoagulants ((D)OACs) was conducted using a random-effects model. Leave-one-out analysis was performed with R (version 4.2.2) and RStudio (version 2022.12.0+353).Results: Of the 12 studies included, only one reported on the prevalence of overall PIP (65%). The meta-analysis of 10 studies assessing PIP of (D)OACs produced a pooled prevalence [95% confidence interval (CI)] of 35% [30–40%], with significant heterogeneity between the included studies (I2 95%). No statistically significant association was reported in three studies between PIP of (D)OACs, cardiovascular (CV) and all-cause mortality, hospital readmission, CV hospitalisation and stroke. Reported associations between PIP and major bleeding differed, with one study demonstrating a significant association (odds ratio 2.17; 95% CI 1.14–4.12) and the other study not showing such association. Conclusion: This systematic review highlights the scarce evidence regarding the prevalence of PIP and its association with adverse health outcomes in multimorbid older adults with AF. Large, prospective and better-designed studies are needed.</p

Geomechanical modelling and consequences for fluid-flow in complex rifted settings: A case study in the Otway Basin, Australia

Poster presented at the EGU General Assembly 2019Geomechanical modelling of dilation tendency has been completed on more than 900 faults from nine three dimensional seismic surveys within the Otway Basin, Australia. As the in-situ stress regime within the basin is currently debated, scenarios of normal, strike-slip and reverse regimes of in-situ stress have been modelled. Additionally, the stability of natural fractures from seven wellbore image logs has been modelled under the same scenarios, with the consequences for each explored. NW-SE striking faults that define the basin’s major structural fabric are at critical risk of dilation irrespective of the regime of in-situ stress, while similarly striking fractures require very low (<5MPa under a strike-slip scenario) increases in pore pressure in order to be reactivated. N-S striking and W-E striking faults show lower risks for reactivation although their propensity to dilate is still significant. Our results in part explain why fault seal within the Otway Basin has been historically so poor, and suggest that while natural fracture networks may be optimally oriented for reactivation in order to increase secondary permeability – promising for unconventional prospectively - there is a high associated risk with respect to up-dip contamination along regional faults. This case study also provides insight into possible fluid flow pathways within other more frontier passive margin settings.Hugo Burgin, Khalid Amrouch, David Kulikowski, Simon Holford, and Philippe Robio

An integrated approach to determining 4D stress development at Castle Cove

Models for basin evolution and natural fracture development often contain many uncertainties. Multiscale approaches to structural analysis assist in reducing these by providing checkpoints for structural evolution to better constrain the development of paleostress phases through time. In this study, we integrate the analysis of calcite twins, magnetic fabrics, stylolites and natural fractures at Castle Cove in the eastern Otway Basin, producing a five-phase model for stress evolution consisting of: phase 1 ~NW–SE Mid-Cretaceous strike-slip or compression; phases 2 and 3 Late Cretaceous extension, coinciding with the development of ~NW–SE and ~NE–SW striking extensional fracture sets; phase 4 ~NE–SW strike-slip and compression, representing an enigmatic period of stress evolution with respect to the current understanding of the Otway Basin; and phase 5, present day ~NW–SE strike-slip stress. The results contribute to a 4D structural history construction for the eastern Otway Basin and suggest that the evolution of the region may require reassessing in order to determine the timing and nature of the detected ~NE–SW oriented compressional event. This study also demonstrates how the use of a calcite stress inversion technique can assist in providing mechanical checkpoints for the evolution of complex natural fracture networks, which can easily be expanded within the sub-surface.Hugo B. Burgin, Khalid Amrouch, Philippe Robion and David Kulikowsk

The intracontinental High Atlas belt: geological overview and pending questions

Published online: 03June 2021The High Atlas intracontinental belt is an inverted rift formed along the Northwest African Craton, between the Central Atlantic Ocean and the Africa-Eurasia plates’ boundaries. Due to its particular location at this triple junction, the Moroccan High Atlas is a good example to investigate the tectonic and geodynamic complexity within continental interiors. The present paper aims to give an overview of the actual understanding of the post-Variscan tectonic and structural history of the High Atlas belt and to shed light on some of the most actively debatable questions relating to the geodynamic context of its uplifts. The High Atlas basin Alpine history started with a period of passive rifting during the Middle-Late Triassic-Early Liassic resulting in a complex rift system actuated by the reactivation of Variscan NNE to ENE-trending structures in the framework of a global NW-SE extension. The Late Triassic rift basins were filled by thick salt-bearing red-beds whose post-rift extensive halokinetics has a considerable impact on the structural architecture of the Western and Central High Atlas. Extensional deformation was renewed in the Central High Atlas at the Late Liassic-Early Bajocian associated with the drowning of Liassic carbonate platform coevally with salt mobilization which led to the initiation of NE to ENE-elongated narrow diapiric ridges. By the Middle Jurassic, a major part of the High Atlas basin was submitted to a widespread post-rift epeiorogenic upward motion that lasted up until the Lower Cretaceous, and to which is associated the occurrence of transitional to moderately alkaline magmatism that was emplaced within the established ridges across basement faults. The driving geodynamic mechanisms and the tectonic setting of this uplift are poorly known but the large extent of the exhumed lands in both margins of the Central Atlantic and the synchronicity between the upward movements and the drastic increase of the Central Atlantic Ocean spreading rate suggests a possible causal link between the Central Atlantic dynamics and the Middle Jurassic-Lower Cretaceous post-rift exhumation. The Late Cretaceous signals the onset of the convergence between Africa and Eurasia and the consequent Alpine orogeny. The effective inversion of the Atlas paleo-rift begun during the Eocene and accentuated during the Neogene in an intra-continental environment. The western segment of range witness a basement-involved thick-skinned faulting and folding style, whereas thin-skinned deformation detached mostly on Upper Triassic-Early Liassic evaporitic layers is focused in external forelands. In the Central High Atlas, the salt-involved Cenozoic deformation triggered the evaporites squeezing and extrusion and the inversion of the pre-structured magmatic cored ridges into compressional anticlines. During the Alpine orogeny, the High Atlas orogen underwent weak crustal shortening with the development of a moderate crustal root that resides over a highly elevated Lithosphere-Asthenosphere Boundary. The most prevailing view predicts the occurrence of a hot mantle anomaly, superimposed to the collisional deformation, beneath the Atlas range that maintains the high topography featuring the High Atlas orography. Although advanced studies have been performed, several questions regarding the kinematic history, the origin of the vertical movements, the role played by the week salt layers during both extensional and compressional deformation stages, and the factors controlling the selective inversion of the paleo-rift normal faults and the deep geometry of the range’s major faults, are still not well resolved and deserve to be deeply re-investigated.Hamza Skikra, Khalid Amrouch, Abderrahmane Soulaimani, Rémi Leprêtre, Muhammad Ouabid, Jean-Louis Bodinie