Geomorphological signature of topographically controlled ice flow-switching at a glacier margin: Breiðamerkurjökull (Iceland) as a modern analogue for palaeo-ice sheets

Ice low-switching, which can involve changes in ice flow velocity and direction, is crucial to a full understanding of ice masses and their response to climate change. A topographically controlled ice flow switch near a glacier margin was recently documented at Breiðamerkurjökull, southeast Iceland, where the central flow unit migrated eastward in response to variations in subglacial topography and the influence of Jökulsárlón glacial lagoon. This site provides an opportunity to study the geomorphic response to ice-margin reconfiguration. Investigating contemporary processes can offer valuable insights into analogous landforms created during the deglaciation of palaeo-ice sheets. The landform assemblage and topographic setting of our Icelandic study site is compared to a palaeo-example from Alberta, Canada, which was once covered by the Laurentide ice sheet. Uncrewed aerial vehicle-(UAV) derived data was used to assess the geomorphic response to this switching and related processes across a 1.5 km2 area of the central flow unit which deglaciated between 2010 and 2023. From 2010 to 2017, the landscape featured streamlined subglacial material, a stable subglacial esker system and proglacial lakes (Landsystem A), shifting to a spillway-dominated system between 2018 and 2023 (Landsystem B). Since 2018 this section of Breiðamerkurjökull has been retreating across a reverse slope bed, resulting in the formation of quasi-annual ice-marginal spillways. Meltwater impoundment at the ice margin, formed ice-contact lakes which eventually initiated ice-margin parallel spillways draining proglacial meltwater along the local land-surface gradient, towards Jökulsárlón. As the ice retreats, an ice-contact lake forms again at the new margin and initiates the erosion of the next ice-marginal spillway. The geomorphological signature demonstrates how subglacial topography and ice-flow switching can significantly influence ice and meltwater dynamics. Since the glacier flow-switch, part of the central unit is now lake-terminating with areas of the margin evolving into a stagnant system, as it is now cut off from the accumulation centre. Therefore, Landsystem B could be analogous to regions of ice stream shut down and where ice masses retreated across reverse slope beds. For example, the Pakowki Lake region of Southeastern Alberta displays a similar landform assemblage and is presented as a palaeo-example in this work. Such insights are important for assessing the efficacy of numerical models in reconstructing the finer scale dynamics of past ice sheets during retreat

Genome-wide association and Mendelian randomisation analysis provide insights into the pathogenesis of heart failure

Heart failure (HF) is a leading cause of morbidity and mortality worldwide. A small proportion of HF cases are attributable to monogenic cardiomyopathies and existing genome-wide association studies (GWAS) have yielded only limited insights, leaving the observed heritability of HF largely unexplained. We report results from a GWAS meta-analysis of HF comprising 47,309 cases and 930,014 controls. Twelve independent variants at 11 genomic loci are associated with HF, all of which demonstrate one or more associations with coronary artery disease (CAD), atrial fibrillation, or reduced left ventricular function, suggesting shared genetic aetiology. Functional analysis of non-CAD-associated loci implicate genes involved in cardiac development (MYOZ1, SYNPO2L), protein homoeostasis (BAG3), and cellular senescence (CDKN1A). Mendelian randomisation analysis supports causal roles for several HF risk factors, and demonstrates CAD-independent effects for atrial fibrillation, body mass index, and hypertension. These findings extend our knowledge of the pathways underlying HF and may inform new therapeutic strategies

Middle to late Pleistocene palaeoceanography inferred from ridge-furrow structures on the continental slope offshore Angola

3D seismic reflection data have been used to map 784 enigmatic ridge-furrow structures in water depths of 0.8–1.7 km offshore Angola. The structures are characterised by asymmetric ridges with intervening furrows, typically <0.5–5.5 km long, with a sinuous to bifurcating planform. The furrows are well-imaged on seismic profiles, and range from 60 to 80 m in width, up to 10 m in amplitude, and 0.1–1 km in wavelength. The furrow sets aggrade in a downslope direction and occur in arrays that have an internally consistent direction that is either parallel, or slightly diverging or converging. Two alternative origins are considered: (1) furrows that are dominantly erosional scours formed from seafloor-incising currents flowing parallel to the furrows, with the ridges a by-product of the erosion, or (2) the ridge-furrows are bottom-current generated dune-type sediment waves. The latter interpretation allows us to reconstruct a key component of the deepwater bottom-currents regime along this continental margin from the Middle Pleistocene to the present-day. The most likely transport agent responsible for the interpreted sediment waves is a palaeo-bottom-current regime with a flow direction toward the west-southwest/south-southwest, the same direction of the sediment wave migration. The palaeo-bottom currents would then be expected to have a very specific flow regime with 1 < Frmax < 2 and may originate from longshore currents cascading off the shelf, Congo Canyon distal overflows, breaking internal waves or a combination of these processes