87191 research outputs found
Sort by
Can GW231123 have a stellar origin?
No full textThe gravitational wave event GW231123 detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) interferometers during their fourth observing run features two black holes (BHs) with source-frame masses of and – in the range of the pair-instability BH mass gap predicted by standard stellar evolution theory. Both BHs are also inferred to be rapidly spinning (, ). The primary object in GW231123 is the heaviest stellar mass BH detected to date, which, together with its extreme rotation, raises questions about its astrophysical origin. Accounting for the unusually large spin of with hierarchical mergers requires some degree of fine-tuning. We investigate whether such a massive, highly spinning object could plausibly form from the collapse of a single rotating massive star. We simulate stars with an initial core mass of – sufficient to produce BH masses at the upper edge of the 90 per cent credible interval for in GW231123 – across a range of rotation rates and reaction rates. We allow for differential rotation to explore the high-spin regime. In this limit of weak angular momentum transport, we find that (i) rotation shifts the pair-instability mass gap to higher masses, introducing an important correlation between masses and spins in gravitational wave predictions, and (ii) highly spinning BHs with masses can form above the mass gap. Our results suggest that the primary object of GW231123 may be the first directly observed BH that formed via direct core collapse following the photodisintegration instability
Lithium isotopic composition of fluid inclusions provides insights into fluid–rock interaction in subducted sediments and sources of mud volcano fluids
No full textLithium isotopes have been widely used to investigate fluid-mediated processes in subduction zones. However, direct analysis of pore fluids in metamorphic rocks remains challenging due to prohibitive depths at which these processes occur. To evaluate the potential of Li concentration and isotopic composition recorded in fluid inclusions, we employed a crush-leach technique to extract fluid inclusion leachates, complemented by analyses of host quartz and wall rocks of syn-subduction veins from three paleo-accretionary complexes–The Kodiak complex (Alaska), Shimanto Belt (Japan), and Western Alps (France–Italy)–formed in the temperature range of 250–400℃.Our results reveal that Li concentrations in fluid inclusion leachates range between 2 and 24 ppm. Compared to seawater and pore fluids of modern deep-sea sediments, the leachates show an enrichment of at least an order of magnitude. The mixing model suggests that such an increase in Li concentration in metasedimentary pore fluids requires the release of less than 1% Li from the surrounding rock in a closed system, unexpectedly low for metasediments experiencing temperatures up to 400°C. The δ7Li values of leachates span from −1.5‰ to +17.1‰, varying between localities, and are generally lower compared to paired quartz residues (+10.9‰ to +22.6‰). The Li-δ7Li mixing model between quartz and fluid inclusions suggests minimal to negligible impact of post-entrapment re-equilibration on Li concentrations and δ7Li composition of fluid inclusions, confirming the preservation of the initial pore fluid δ7Li values. The variation in δ7Li values of pore fluids between Kodiak (+8.1‰ to +17.1‰), the Western Alps (−1.5‰ to +9.5‰), and Shimanto (+2.5‰ to +10.4‰) is primarily governed by the presence of Li-bearing mineral phases during vein formation–particularly chlorite, white mica, and paragonite–and their capacity to retain lithium. In closed systems, δ7Li values of pore fluids can be explained by Rayleigh fractionation during the crystallization of chlorite, illite/phengite, and paragonite, which dominantly incorporate 6Li, leaving the fluids enriched in 7Li. Conversely, in open systems, continuous Li removal from the rocks results in decreasing δ7Li values of pore fluids, though their Li concentrations remain comparable to those in closed systems. Similarities in Li concentrations and δ7Li values between leachates and mud volcano fluids in modern examples of subduction zone forearcs further confirm that such fluids dominantly originate from subducted sediments. Collectively, this study demonstrates the capability of Li isotope systematics of fluid inclusions to effectively contribute to the understanding of fluid–rock interactions in subducted lithologies
Editorial preface to special issue: From rock to time: evolutionary lineages and the calibration of the Chronostratigraphic Scale
No full textThe International Chronostratigraphic Chart has been under consideration and construction for more than two hundred years. The integration of multidisciplinary, high-resolution studies, and the correlation of pervasive and recognizable markers, have helped develop and continuously update the chart providing a standardized and global language for stratigraphers. STRATI (International Congress on Stratigraphy) is the main scientific meeting of the International Commission on Stratigraphy (ICS) that takes place every four years and is dedicated to all topics associated with improving and updating chronostratigraphy and geochronology. We note that stratigraphical studies are undertaken by specialists who, primarily, focus on specific Phanerozoic systems, rarely venturing beyond the confines of their adopted time slice. Acknowledging this potential weakness, STRATI attempts to remove the intellectual and geological boundaries (disciplinary, taxonomic and temporal), and engage the wider community to define, discuss, combine and compare the potential and role of stratigraphy today in fine tuning the International Chronostratigraphic Chart, especially its correlation and geochronometry. In this Virtual Special Issue (VSI), we present some of the findings of STRATI2023 held in Lille, France (July 11st-13rd 2023) and attended by 285 participants from over 40 countries. Our intention is to collect the most significant contributions arising from this meeting, complemented by specific research articles in order to guarantee a full coverage of the fields of stratigraphy. We demonstrate that refined applied stratigraphy is now approached through a multiproxy perspective, as highlighted in most studies captured here. The VSI goes further by reexamining fundamental concepts in stratigraphy together with the definition of marine bioevents and the role of vertebrates in biostratigraphy. More broadly, the VSI addresses a range of current topics within stratigraphy to highlight the essential role of modern stratigraphical practice as a prerequisite for all future research in palaeogeography, palaeoclimatology and palaeoecology
Escape to express: Tourist identity and self-disclosure
Get PDFCounter to the common intuition that consumers tend to be more cautious and less self-expressive when traveling to or reviewing an unfamiliar place, this research uncovers a counterintuitive effect: making a tourist identity salient increases consumer self-disclosure. A field study (n = 224) establishes the main effect. Then, Study 2 (n = 283) tests the mediating role of psychological anonymity while ruling out several alternatives. Studies 3 (n = 396) and 4 (n = 381) examine the moderating roles of social anxiety and brand type. Finally, a large-scale secondary data analysis (n = 39,574) further corroborates our findings. The results extend identity theory in tourism by showing that tourist identity influences behavior beyond immediate travel contexts and provide practical insights
Balancing selection maintains intraspecific diversity in a deep-sea fish.
Get PDFSegregating alleles in natural populations can be driven to fixation or loss by genetic drift or directional selection, or may be maintained in a polymorphic state by balancing selection. Balancing selection in a panmictic population is theoretically well established, but not widely understood at the molecular level. In this study, we focus on the evolutionary processes affecting non-synonymous variants at eight functionally relevant loci (based on candidate SNP genotyping) in a deep-sea fish species (Coryphaenoides rupestris) that lives across habitat zones ranging from ~200 m to ~2000 m depth. At each of these loci, one allele is predominant in the deeper water. Across a shallower depth range, we find that minor allele frequencies show a highly significant increase or decline progressively across five defined age categories. At single depths below a threshold depth, the deep-water allele declines in frequency with age. Together, these data indicate segregation to different depths, either shallow or deep, and balancing selection to retain variants needed for each depth range. This is supported by signals for long-term balancing selection at these loci (based on published genomic data). We discuss alternative interpretations and conclude that balancing selection maintaining ecotype diversity is the best supported mechanism
The impact of bars on the properties of H ii regions in the TIMER survey
Get PDFIn this study, we perform a comparative analysis of the properties of the H ii regions located in different areas of barred galaxies, with the aim of investigating the impact of bars on the physical properties of the ionized gas. Based on integral field spectroscopy data for 17 barred galaxies covering approximately the central kpc, we detect a total of 2200 regions, of which 331 are located within the nuclear disc (also known as circumnuclear regions), 661 in the bar region, and 1208 in the disc. Among the physical properties of the regions, we explore the O/H and N/O abundances, H luminosity, dust extinction, electron density, and H equivalent width. We find clear differences in the properties of the regions between the nuclear disc, the bar, and the disc, that could be explained by an enhancement in the molecular gas concentration in the central parts driven by bar-induced gas flows. As this gas is channelled towards the galaxy centre, the most extreme values in the analysed properties are found for the circumnuclear regions. Unlike the bar strength, galaxy mass does seem to affect the properties of the regions, with massive galaxies presenting higher values in most of the properties, possibly due to the increased amount of gas in these systems. This study provides evidence that the bar-driven redistribution of material within the galaxy inner parts causes significant differences in the region properties depending on their location within the galaxies
The Routledge Handbook of Spirituality, Religion, and the Medical Humanities
No full textCurrently, religion is absent or severely underemphasized within the medical humanities, and The Routledge Handbook of Spirituality, Religion, and the Medical Humanities forges direct engagements between the fields of medical and health humanities, on the one hand, and religious studies and theological studies on the other. This volume consists of 35 chapters from an international and interdisciplinary range of contributors, organized into 6 parts:Religious Studies and Theology in the Medical Humanities: Tensions and TransformationsThe Socio-Spiritual SelfCulture and the Culturally MediatedSpace, Place, and BodiesBeliefs, Brains, and BehavioursSpirituality and Religion in Healthcare: Application and ImpactBy directly connecting major questions and themes from each of these domains, this volume firmly establishes a needed bridge and valuable resource for stakeholders with an interest in how mental and physical health relates to the human drive for meaning
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! 👇