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The nucleation and growth of mixed H2O–CO2 bubbles in magmas
Get PDFVolcanic eruptions are driven by the nucleation and growth of gas bubbles that form when volatile species dissolved in magma become supersaturated. Previous models for bubble growth have focussed on H2O; however, CO2 also plays a fundamental role in the nucleation and growth of gas bubbles. Here, we develop a numerical model to explore the nucleation and growth of bubbles containing both H2O and CO2 in magma of arbitrary composition. Nucleation is modelled as a Poisson process using classical nucleation theory with composition-appropriate solubility models for the mixed H2O–CO2 fluid. We find that CO2 dramatically increases the depth of bubble nucleation compared with H2O-only systems; for a case-study rhyolite (Krafla, Iceland) CO2 increases nucleation depth from 130 m (H2O-only) to 760 m if CO2 is included (a factor of 6 increase in nucleation pressure); for a case-study basalt (Fagradalsfjall, Iceland), nucleation occurs at 13 km depth if CO2 is included, but does not occur at all if H2O is the only volatile species. Post-nucleation growth of the bubbles is investigated by extending a ‘shell model’ to include CO2 as well as H2O. The species are coupled via a mixed equation-of-state for the gas phase, introducing a co-dependence on their solubility that allows H2O to exsolve at greater depth when CO2 is present. As a result, exsolution of a small volume of CO2 can trigger the exsolution of a much larger volume of H2O, driving rapid, disequilibrium bubble growth. Our findings show that accounting for mixed H2O–CO2 volatile compositions is essential for accurate modelling of magma ascent and eruption dynamics
Assessment of soil nutrient status and spatial variability in the Sundarbans Mangrove Forest, Bangladesh
No full textCommercial reform and corporate investment efficiency: The roles of governmental administrative efficiency, information transparency, and regulatory oversight
Get PDFOver the past decade, the Chinese government has reformed its commercial system to streamline administration, decentralize authority, and enhance regulation, services and oversight of commercial activities, which aims at improving the business environment and promoting sustainable economic development. Digital technologies have been integrated into the regulatory reform. We examine whether this reform affects corporate investment efficiency. Using a stacked difference-in-differences research design, we find that the reform enhances corporate investment efficiency. This enhancement is driven by more efficient government administration, increased transparency of commercial information, and stronger regulatory monitoring of commercial activities. The positive impact on investment efficiency is more pronounced for non-state-owned enterprises, firms in regions with higher market segmentation, and those facing greater commercial uncertainty. Further analysis reveals that the reform curbs both corporate underinvestment and overinvestment. Overall, our findings highlight the pivotal role of commercial reform in enhancing corporate investment efficiency, and provide valuable insights for policymakers worldwide in designing more effective regulatory frameworks to support business investment
Exploring the Experiences of Women Academics in England: The Combined Effects of Societal, Structural and Life‐Stage Factors
No full textThis study explored the experiences of women who are academics working in UK higher education (HE), using a feminist approach and narrative methods and analysis. The purpose of the research was to explore the experiences of women, with a view to highlighting potential shared experiences, informing the policies of universities and adding to the body of knowledge on women in HE. Findings include narrative themes around gender roles, male-dominated academia and life-stage impact on career. Concluding recommendations include meaningful recognition of pastoral roles and promotion tracks which value these skills and support for women's life stages, including maternity, motherhood, menopause and sandwich caring
“What’s Gone is Gone”: Partition, Ownership, and Loss in Geetanjali Shree’s Tomb of Sand
No full textThis article focuses on the depiction of two objects, an ancient Buddha statue and the protagonist Chanda’s extensive sari collection, in Tomb of Sand (2021), the Booker prize-winning translation of Geetanjali Shree’s Hindi novel Ret Samadhi (2018), and on the ways in which these objects are bound up not only with the novel’s political but also with its philosophical underpinnings. Even though the novel is primarily set in twenty-first-century India, the 1947 Indian Partition and its continuing repercussions are some of the novel’s core thematic concerns. In examining Shree’s representation of the statue and of Chanda’s collection of traditional saris, my essay shows how the text complicates our understanding of the multilayered and intensely gendered politics of individual as well as collective ownership and loss—both familial and national—against the backdrop of divisive religio-nationalist rhetoric in twentieth- and twenty-first-century South Asia. The paper also demonstrates the ways in which the novel participates in debates about post-Partition museology and heritage, revealing the close and, at times, disturbing relationship between national and familial myths about possession and dispossession
Between endings and beginnings: ‘Detachment’ and (non)relations in contemporary human geography
No full textThis paper offers a theory of detachment as a distinctive social-spatial (non)relation as a contribution to recent debates about relations and relationality in contemporary human geography. It argues that ‘detachment’ has thus far served as other to and problem for the literatures concerned with (non)relational geographies. As part of an approach to relationality that advocates for an orientation to multiple, different kinds of (non)relation, the paper proposes three complementary understandings of detachment: detachment as the absence of a promise; detachment as the imminent loosening of a promise; detachment as the ending of a promise
XMM-Newton multi-year campaign on NGC 55 ULX-1: Resolving the wind and its variability with RGS
No full textContext. Winds are an important ingredient in the evolution of X-ray binary (XRB) systems, particularly those at high accretion rates such as ultra-luminous X-ray sources (ULXs), because they may regulate the accretion of matter onto the compact object.Aims. Our aim is to understand the properties of ULX winds and their link with the source spectral and temporal behaviour.Methods. We performed high-resolution X-ray spectroscopy of the variable source NGC 55 ULX-1 to resolve emission and absorption lines as observed with XMM-Newton at different epochs. Optically thin plasma models were used to characterise the wind.Results. We confirmed and thoroughly strengthened previous evidence of outflows in NGC 55 ULX-1. The presence of radiative recombination signatures and the ratios of the fluxes of the emission lines favours photoionisation balance and low to moderate densities, which confirm that the lines originate from classical XRB disc winds. An in-depth parameter space exploration shows line emission from a slowly moving, cool, and variable plasma perhaps associated with a thermal wind. Mildly relativistic Doppler shifts (about −0.15c) associated with the absorption lines confirm, at higher confidence, the presence of powerful radiatively driven winds.Conclusions. The comparison between the results obtained at different epochs revealed that the wind responds to the variability of the underlying continuum. These variations may be used to understand the actual accretion regime and the nature of the source
Leveraging China's SCIAP Initiative: How Digital Transformation Policies Reshape Supply Chain Performance Dynamics
No full textIn the ever-evolving realm of global supply chain management, optimizing corporate supply chain performance is paramount for sustaining competitiveness. Based on data of Chinese A-share listed companies from 2009 to 2022, we harness the Supply Chain Innovation and Application Pilots (SCIAP) policy in China as a quasi-natural experiment to empirically scrutinize the impact of supply chain digitalization on corporate supply chain performance. Our findings suggest that SCIAP policy significantly improves enterprises’ supply chain performance by facilitating corporate digital transformation, promoting the vertical integration of supply chains and alleviating corporate financing constraints. There is significant heterogeneity in the effectiveness of digital transformation policy: compared to large-scale companies, the supply chain performance of small-scale enterprises has significantly improved as a result of digital transformation; the SCIAP policy exerts more pronounced effects on enterprises with high supply chain risks, which indicates that vulnerable groups benefit more from digital transformation. Furthermore, companies located in regions with high municipal government digital attention experience more favourable impacts from pilot policies. These insights contribute to the theoretical and practical understanding of supply chain digitalization, offering a foundation for developing high-quality, modern supply chain systems
Islamic Economic Systems and Sustainable Development: Islamic Capitalism versus Insanism (Islamic Humanism)
No full textThis article examines different economic systems and assesses their implications for promoting sustainable development. In a capitalist system, capital is managed by homo economicus who focuses on maximising profits and capital accumulation without ethical considerations. This has led to the continuous exploitation of natural resources, resulting in destructive impacts on the environment. Recognising that capital has the power to affect production and value creation, this article asserts that ethics is needed to tame capital and its production processes to achieve sustainable development. The configuration of an Islamic economic system will depend on the meanings of Sharīʿah and how it is interpreted. A narrow legalistic perspective would focus on legal compliance and would produce an Islamic capitalist system that would have similar adverse impacts on the environment as its capitalist counterpart. Alternatively, expanding the meaning of Sharīʿah to include legal-ethical principles and values would frame the economic system as insanism (Islamic humanism) that embeds human welfare-related ethics of maqāṣid al-Sharīʿah and legal maxims. In this system, moral homo Islamicus (homo islami-ethicus) imbued with the ethical characteristics of khalīfah, will act as a steward to guide capital and production processes, preserve the environment and contribute to sustainable development
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