Apocrita - High Performance Computing Cluster For Queen Mary University Of London

King, Thomas; Butcher, Simon; Zalewski, Lukasz

doi:10.5281/zenodo.438045

Cited by 47 publications

(15 citation statements)

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“…This research was supported by STFC Consolidated grants awarded to the QMUL Astronomy Unit 2015-2018 ST/M001202/1 and 2017-2020 ST/P000592/1. This research utilized Queen Mary's Apocrita HPC facility, supported by QMUL Research-IT (King et al 2017); and the DiRAC Data Centric system at Durham University, operated by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment was funded by a BIS National E-infrastructure capital grant ST/K00042X/1, STFC capital grant ST/K00087X/1, DiRAC Operations grant ST/K003267/1 and Durham University.…”

Section: Acknowledgementsmentioning

confidence: 99%

Migrating super-Earths in low-viscosity discs: unveiling the roles of feedback, vortices, and laminar accretion flows

McNally

Nelson

Paardekooper

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present the highest resolution study to date of super-Earths migrating in inviscid and low-viscosity discs, motivated by the connection to laminar, wind-driven models of protoplanetary discs. Our models unveil the critical role of vortices in determining the migration behaviour for partial gap-opening planets. Vortices form in pressure maxima at gap edges, and prevent the disc-feedback stopping of migration for intermediate planets in low-viscosity and inviscid discs, contrary to the concept of the 'inertial limit' or 'disc feedback' halting predicted from analytical models. Vortices may also form in the corotation region, and can dramatically modify migration behaviour through direct gravitational interaction with the planet. These features become apparent at high resolution, and for all but the highest viscosities there exist significant difficulties in obtaining numerically converged results. The migration of partial gap-opening planets, however, clearly becomes chaotic for sufficiently low viscosities. At moderate viscosity, a smooth disc-feedback regime is found in which migration can slow substantially, and the migration time-scale observed corresponds to migration being driven by diffusive relaxation of the gap edges. At high viscosity classical Type I migration is recovered. For Jupiter-analogue planets in inviscid discs, a wide, deep gap is formed. Transient Type II migration occurs over radial length-scales corresponding to the gap width, beyond which migration can stall. Finally, we examine the particle trapping driven by structures left in inviscid discs by a migrating planet, and find that particle traps in the form of multiple rings and vortices can persist long after the planet has passed. In this case, the observation of particle traps by submillimetre interferometers such as ALMA cannot be used to infer the current presence of an adjacent planet.

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Section: Acknowledgementsmentioning

confidence: 99%

Migrating super-Earths in low-viscosity discs: unveiling the roles of feedback, vortices, and laminar accretion flows

McNally

Nelson

Paardekooper

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Because MSMC can only analyse biallelic sites, all multiallelic sites were also removed from the MSMC SNP set, leaving a total of 7,761,294 SNPs. Genome mapping and variant calls were conducted on the QMUL Apocrita High Performance Computing Cluster (King et al, 2017).…”

Section: Sampling and Data Processingmentioning

confidence: 99%

Systematic genome scans reveal common population-specific signals of balancing selection

Thorburn

Sagonas

Lenz

et al. 2022

Preprint

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Balancing selection describes evolutionary processes that maintain genetic diversity. To date, the number of impacted genes and underlying biological functions remain elusive. Using 60 three-spined stickleback genomes (Gasterosteus aculeatus) from five recently diverged lake-river population-pairs, we performed genome-wide scans across two levels of organization: population-pairs and populations. We overlapped Tajima’s D and Watterson’s estimator metrics and verified signals with additional summary statistics, and evaluated alternative explanations: neutral evolution, population structure, associative overdominance, or demographic change. Candidate windows exhibiting signals of balancing selection spanned 2.31% (population-pair) and 3.10% (population) of the autosomes. These candidate windows had extended linkage disequilibrium and were enriched in intergenic and non-synonymous SNPs. We identified 715 (population-pair) and 1,010 (population) candidate genes under balancing selection. Importantly, using conservative thresholds, we found a small proportion of candidate genes overlapped with highly differentiated loci or regions of potential associative overdominance. There was little evidence of confounding effects originating from demographic change. Overall, candidate genes under balancing selection were associated with functions related to interactions with the environment (olfaction and receptor signalling pathways). Our results demonstrate selection that maintains standing genetic variation is common and evolves in response to local environmental pressures, playing an important role in adaptation.

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“…We acknowledge that the results of this research have been achieved using the DECI resource Beskow based in Sweden at PDC with support from the PRACE aisbl. This research utilised Queen Mary's Apocrita HPC facility, supported by QMUL Research-IT (King et al 2017). SJP is supported by a Royal Society URF.…”

Section: Acknowledgementsmentioning

confidence: 99%

Polydisperse Streaming Instability III. Dust evolution encourages fast instability

McNally,

Lovascio,

Paardekooper

2021

Preprint

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Planet formation via core accretion requires the production of km-sized planetesimals from cosmic dust. This process must overcome barriers to simple collisional growth, for which the Streaming Instability (SI) is often invoked. Dust evolution is still required to create particles large enough to undergo vigorous instability. The SI has been studied primarily with single size dust, and the role of the full evolved dust distribution is largely unexplored. We survey the Polydispserse Streaming Instability (PSI) with physical parameters corresponding to plausible conditions in protoplanetary discs. We consider a full range of particle stopping times, generalized dust size distributions, and the effect of turbulence. We find that, while the PSI grows in many cases more slowly with a interstellar power-law dust distribution than with a single size, reasonable collisional dust evolution, producing an enhancement of the largest dust sizes, produces instability behaviour similar to the monodisperse case. Considering turbulent diffusion the trend is similar. We conclude that if fast linear growth of PSI is required for planet formation, then dust evolution producing a distribution with peak stopping times on the order of 0.1 orbits and an enhancement of the largest dust significantly above the single power-law distribution produced by a fragmentation cascade is sufficient, along with local enhancement of the dust to gas volume mass density ratio to order unity.

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Apocrita - High Performance Computing Cluster For Queen Mary University Of London

Cited by 47 publications

References 0 publications

Migrating super-Earths in low-viscosity discs: unveiling the roles of feedback, vortices, and laminar accretion flows

Migrating super-Earths in low-viscosity discs: unveiling the roles of feedback, vortices, and laminar accretion flows

Systematic genome scans reveal common population-specific signals of balancing selection

Polydisperse Streaming Instability III. Dust evolution encourages fast instability

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