87191 research outputs found
Sort by
Futures
No full textHow might Cultural Geography relate to the future, in a critical moment in which ‘the future’ appears to be intensely in question? The chapter offers three answers to this question, each of which folds into different versions of the concept of culture, and opens different futures for Cultural Geography. Cultural Geography might perform a diagnostic mode that attempts to understand the formation of distinct imaginaries of ‘the future’, and how those relations are affectively (re)mediated. Here, Cultural Geography would become a way of multiplying the stories told about contemporary and historical relations with ‘the future’, as well as attending to their variability and specificity. Opening into a different version of culture as a way or form of life, and secondly, Cultural Geography might stay with how specific futures are part of, and (re/de)composed through, everyday lives. Finally, and more disruptively, Cultural Geography might practice a utopian mode of inquiry inspired by dissident traditions of immanent utopianism. Such a Cultural Geography to come might take as its task to illuminate and amplify traces of something better. Across these three answers, the chapter performs a simple affirmation – that all cultural geographies are geographies of the future
Task-parallelism in SWIFT for heterogeneous compute architectures
Get PDFThis paper highlights first steps towards enabling graphics processing unit (GPU) acceleration of the task-parallel smoothed particle hydrodynamics (SPH) solver SWIFT. Novel combinations of algorithms are presented, enabling SWIFT to function as a truly heterogeneous software leveraging task-parallelism on CPUs for memory-bound computations concurrently with GPUs for compute-bound computations while minimizing the effects of CPU–GPU communication latency. The proposed algorithms are validated in extensive testing. The GPU acceleration methodology is shown to deliver up to 3.5 and speedups for the offloaded computations when including and excluding the time required to prepare and post-process data transfers on the CPU side, respectively. The overall performance of the GPU-accelerated hydrodynamic solver for a full simulation on a single Grace Hopper superchip is 1.8 times faster compared to the superchip’s fully parallelized CPU capabilities. This constitutes an improvement from 8 million particle updates/s for the full CPU-only baseline (115 000 updates per CPU core) to 15 million updates/s for the GPU-accelerated SPH solver. Moreover, it displays near-perfect strong scaling on 4 Grace Hopper nodes. The GPU-acceleration is also demonstrated to give a 29 per cent improvement in energy efficiency in comparison to CPU-only baselines. Finally, inter-influential bottlenecks in the prototype solver presented in this work are identified: a significant amount of time (up to 80 per cent) of a GPU-offloading cycle is spent on preparing and post-processing particle data on the CPU for the transfer to and from the GPU, respectively. Approaches are suggested to minimize their effects and maximize the solver’s performance in our future work
Probing Dark Matter Substructures with Free-Form Modelling: A Case Study of the `Jackpot' Strong Lens
Get PDFCharacterizing the population and internal structure of sub-galactic haloes is critical for constraining the nature of dark matter. These haloes can be detected near galaxies that act as strong gravitational lenses with extended arcs, as they perturb the shapes of the arcs. However, this method is subject to false-positive detections and systematic uncertainties, particularly degeneracies between an individual halo and larger scale asymmetries in the distribution of lens mass. We present a new free-form lens modelling code, developed within the framework of the open-source software pyautolens, to address these challenges. Our method models mass perturbations that cannot be captured by parametric models as pixelized potential corrections and suppresses unphysical solutions via a Matérn regularization scheme that is inspired by Gaussian process regression. This approach enables the recovery of diverse mass perturbations, including subhaloes, line-of-sight haloes, external shear, and multipole components that represent the complex angular mass distribution of the lens galaxy, such as boxiness/disciness. Additionally, our fully Bayesian framework objectively infers hyperparameters associated with the regularization of pixelized sources and potential corrections, eliminating the need for manual fine-tuning. By applying our code to the well-known ‘Jackpot’ lens system, SLACS0946+1006, we robustly detect a highly concentrated subhalo that challenges the standard cold dark matter model. This study represents the first attempt to independently reveal the mass distribution of a subhalo using a fully free-form approach
Neo-Victorian Decadence: Media, Genres, Eras
No full textThis pioneering collection of essays connects scholars of Decadence studies and neo-Victorian studies to investigate the fascinating intersections between these two fields. Showcasing the revivalistic nature of aestheticist and decadent texts, it considers neo-Victorianism as inherently decadent in how it subverts and reframes Victorian standards. Within this framework, Neo-Victorian Decadence breathes new life into the paradoxical tensions between art and life, nostalgia and the zeitgeist, consumerism and connoisseurship. It interrogates periodisation for the first time, pushing the limits of what might qualify as neo-Victorian to the Interwar period. The volume stands out for its interdisciplinarity and genre-blending, extending beyond the novel to include non-fiction, film, painting, performance art, and digital communities
Limit theorems for Andrews’ restricted overpartitions
Get PDFThe study of overpartitions in recent years has been used to great effect in various fields, including hypergeometric series, q-series identities, and mathematical physics. We investigate the limiting distributions of the number of parts in a family of overpartitions of n, introduced by Andrews, where parts are counted with two different weights. Using Andrews’ identities and the saddle-point method, we establish two central limit theorems (CLTs) for the number of parts as n→∞, corresponding to these weightings. We also derive explicit formulas for the mean and variance in each case
p-Hacking in the Formal Inference Approach
Get PDFp-hacking occurs when researchers conduct multiple significance tests (e.g., p1;H0,1 and p2;H0,2) and then selectively report tests that yield desirable (usually significant) results (e.g., p2 ≤ 0.05;H0,2) without correcting for multiple testing (e.g., 0.05/2 = 0.025). In the present article, I consider p-hacking in the context of two philosophies of significance testing — the error statistical approach and the formal inference approach. I argue that although p-hacking inflates Type I error rates in the error statistical approach, it does not inflate them in the formal inference approach. Specifically, in the error statistical approach, the “actual” familywise error rate (e.g., 1 − [1 − 0.05]2 = 0.098 for two tests) is relevant because it covers both the selectively reported and unreported tests in the “actual” test procedure (i.e., p1;H0,1 and p2;H0,2). In this approach, Type I error rate inflation occurs because the “actual” error rate (0.098) is higher than the nominal error rate (0.05). In contrast, in the formal inference approach, the “actual” familywise error rate is irrelevant because (a) the researcher does not report a statistical inference about the corresponding intersection null hypothesis (i.e., H0,1 ∩ H0,2), and (b) the “actual” familywise error rate does not license inferences about the reported individual hypotheses (i.e., H0,2). Instead, in the formal inference approach, only the nominal error rate is relevant, and a comparison with the “actual” error rate is inappropriate. Implications for conceptualizing, demonstrating, and reducing p-hacking are discussed
Functional composition and structural diversity enhance mangrove forest resilience in the Sundarbans
Get PDFMangrove forests offer nature-based solutions for climate change mitigation by storing atmospheric CO2, while also supporting biodiversity, livelihoods, and coastal protection. Yet, they face increasing threats from deforestation, salinity, and extreme weather events. Here, we assessed and explored the resilience of Sundarbans mangrove forests and associated drivers using satellite-derived vegetation indices, biodiversity, and environmental data, within a structural equation modeling framework. We found 1–8 major perturbations at 250-meter spatial resolution, with the lowest resilience to disturbance or stress in the central and southeastern zones of the Sundarbans. Approximately 610 to 990 km² (~10-15% of the total Sundarbans area) of mangrove forests exhibited declining resilience. The functional composition of maximum canopy height (MCH) was the strongest driver of mangrove forest resilience (β= 0.61), followed by specific leaf area (SLA; β= 0.56) and precipitation (β= 0.44). Structural diversity (β= 0.22), though weakly associated, mediated the positive association of species richness with resilience. Perturbation frequency had a significant negative direct (β= −0.29) and total (β= −0.33) association on resilience, whereas temperature exhibited only a total negative association (β= −0.20). Based on these findings, we hold that for enhancing mangrove forest resilience against disturbances and stressors, (re-)establishment and conservation efforts should focus on maintaining site-specific dominant species with tall canopy height and specific leaf area —supplemented by a few complementary species— to increase structural diversity and facilitate recovery rates
Data sources:
Access Repository Dashboard
Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇