87191 research outputs found
Sort by
Understanding the ocean as energy: The ITLOS Advisory Opinion on Climate Change as an earth systems provocation
No full textEvaluation of bootstrap methods for coverage estimation and prediction accuracy with small samples
No full textSmall sample sizes are common in biomedical research, often making it difficult, or even impossible, to determine the underlying distribution of the data. Traditional frequentist methods typically rely on assumptions of normality, which may not hold in such settings. Bootstrap methods offer a flexible alternative when normality cannot be reasonably assumed, though their use is typically associated with larger sample sizes. This article investigates the performance of four bootstrap methods—nonparametric predictive inference bootstrap (NPI-B), Banks bootstrap (Banks-B), Hutson bootstrap (Hutson-B), and Efron bootstrap (Efron-B)—for estimating population characteristics and making predictive inferences with small sample sizes. A simulation study is conducted using data generated from normal, lognormal, exponential, and mixed-normal distributions. Results indicate that the nonparametric predictive inference bootstrap method performs best for predictive inference with small samples. Additionally, the study highlights promising results for the smooth bootstrap methods, Banks-B and Hutson-B, particularly in the context of estimation
Lessons learned from matching 3D DEM and experiments at macro, meso and fabric scales for triaxial compression tests on lentils
No full textA series of discrete element method (DEM) triaxial compression simulations on specimens of an anisometric granular material starting from distinct initial fabric anisotropy states are conducted and compared with physical experiments on lentils at different scales, assisted by operando X-ray tomography measurements. A quantitative reproduction of the group of experimental results is achieved by appropriate idealization and determination of particle shape, boundary conditions, contact parameters, and initial state. The reliability of DEM in quantitative representation of macro scale stress–strain response, meso scale strain localization, and micro scale fabric anisotropy evolution is thus comprehensively validated against measurements from physical experiments, which is a step forward from comparisons only at the macro or particle kinematics level. Several key factors that govern realistic DEM simulations are also identified. The friction coefficient between particles during specimen generation, particle shape, and specimen preparation method can significantly affect the initial state of DEM specimens. Differences in initial state at macro and micro scales and boundary conditions can strongly influence the stress–strain response. However, the evolution of fabric anisotropy appears to be insensitive to changes in initial state and boundary conditions
Ethical Dilemmas in Educational Research: BERA Case Studies for Researchers by Researchers
No full textDrawing on the real voices and experiences of researchers, this book illustrates how the British Educational Research Association (BERA) Ethical Guidelines for Educational Research can be used to appraise research studies ethically. Researchers have choices when they design, conduct and report their research. These choices have consequences for others – funders, sponsors, those who facilitate access to research settings, those in the research settings, participants and the researchers. Sometimes the consequences can be anticipated and positive consequences can be maximised in the research design and negative consequences minimised. Sometimes the consequences only become apparent as the research unfolds.This book presents a series of case studies following researchers in their decision-making through studies in a range of settings to consider different ways to deal with ethical dilemmas raised. The authors draw on their experiences to explain researcher thinking and how this relates to enacting values, pointing to relevant advice in the BERA ethical guidelines. They also explore choices not taken, considering the possible implications from such decisions, and how other researchers might have made different decisions based on different positionality. The book confronts rather than avoids the application of Global North derived guidance for research in settings other than the UK. As well as thought provoking case studies, the book puts forward questions for readers to relate to their own research contexts and recommended reading for further thinking about the issues raised.Published in partnership with the British Educational Research Association
The Impact of Biochar Addition on the Water Quality of a Lowland Peat Ecosystem
Get PDFThe addition of biochar has been proposed as a mechanism for enhancing carbon storage in soils, but the consequences of this approach for water quality have not been assessed for peat soils. In this study we considered the impact of biochar treatment on the soil water of a raised bog in northern England. Biochar application rate was up to 64 t/ha equivalent to 2 cm depth of peat. Over the 2 years of the study we found that biochar addition brought about a statistically significant increase in soil water pH, electrical conductivity, dissolved organic carbon concentration, absorbance, inorganic nitrate and sulphate concentrations; although in most cases changes were small in magnitude and hence expected to have little ecological impact. Biochar addition made no significant difference to iron and phosphate concentrations. The lack of increase in phosphate concentration may mean that increase in inorganic N could not be utilised by biota. The study found no evidence of detrimental impact of biochar addition on water quality in and from these peat soils. Therefore, changing water quality would not be an impediment to using biochar as a nature‐based solution to anthropogenic climate change
Plutonic Xenoliths Reveal the Influence of Cryptic Melt-Mush Reaction Processes in the Plumbing System Beneath St Vincent, Lesser Antilles Arc
Get PDFIn subduction zones, it is widely established that magmas are stored as crystal dominated mush within sub-volcanic plumbing systems. In these mush-dominated systems, it is likely that melt-mush reactions between migrating melts and the pre-existing mush influence the chemical evolution of magmas. However, melt-mush reactions and their effect on the chemical evolution of arc magmas can be elusive and cannot be constrained when studying erupted lavas in isolation. In this study, we focus on the island of St. Vincent in the Lesser Antilles volcanic arc because (1) the composition of erupted lavas has been interpreted to reflect simple fractional crystallisation (FC), with minimal influence of other magmatic processes, and (2) an abundance of plutonic xenoliths (erupted fragments of crystal mush) can be found within the eruptive products. Thus, we are able to compare interpretations gleaned from the chemistry of erupted lavas with new observations of the crystal mush in the same magmatic system. To this end, textural analyses were undertaken on seventeen representative plutonic xenoliths from St Vincent, and four of these samples (two olivine [OL] gabbros, two hornblende-olivine gabbros) were studied in detail via element mapping, mineral trace element analyses and geochemical modelling. The chemical, textural and mineralogical characteristics of the olivine gabbros were best explained via FC in the mid-upper crust (~6–18 km depth). However, the hornblende-olivine gabbros (two of seventeen samples studied) contained clear textural evidence for melt-mush reaction in the mid-upper crust. The trace element compositions of minerals such as clinopyroxene in these two samples were best reproduced via assimilation-FC (AFC) modelling, simulating melt-mush reactions, supporting the textural evidence. Our plutonic xenoliths reveal that in addition to FC, cryptic (i.e. not directly recorded in lavas) melt-mush reaction processes also contribute to magma chemical evolution, particularly influencing trace elements, within the sub-volcanic plumbing system. Textural evidence for melt-mush reaction is increasingly reported in plutonic xenoliths from other active arcs and exhumed arc crustal sections, suggesting that this process is ubiquitous in mush-dominated arc plumbing systems. Melt-mush reaction therefore represents an important process contributing to arc magma and arc crust trace element chemical diversity
Leadership Identity at a Crossroads: New Ways of Theorizing, Measuring, and Modeling Dynamic States
No full textThis chapter captures the emerging theory and research of leadership identity dynamics with a focus on short-term and nonlinear changes. It first reviews the state of the science on identity dynamics in the context of leadership and followership, including phenomena such as claiming and granting of leadership, within-person change of leadership identities, and identity liminality. The authors discuss the key assumptions of relevant theories and synthesize results in relation to influence factors and the outcomes of these dynamics. Based on the review, leader-follower identity liminality is developed as a conceptual extension of dynamic leadership identity states with the potential to inform research in the future. The authors also provide the items of the Leader-Follower Identity Liminality Scale. Finally, the chapter translates the conceptual ideas into principles of dynamic modeling of leadership and followership identities. It concludes by encouraging readers to expand the current understanding of identity dynamics by linking new theoretical, measurement, and modeling approaches in future research
Ecosystem extent mapping in a global monitoring context
Get PDFThe vital role of ecosystems in maintaining biosphere stability is now recognized globally. Updates in policy frameworks on biodiversity and environmental decline include information on ecosystem extent (EE) as a core assessment indicator, e.g., the Global Biodiversity Framework indicator A2 ‘Extent of natural ecosystems’. The recently proposed System of Environmental-Economic Accounting – Ecosystem Accounting requires EE as the first pillar for assessing ecosystem condition and, ultimately, ecosystem services. Detailed and up-to-date information on ecosystem characteristics is increasingly achievable due to the unprecedented availability of Earth observation data, combined with advances in geospatial data analysis and high-performance computing, building on a long-established tradition of surface monitoring. However, consistent mapping and delineation of EE remains a challenge. This research aims to identify the role of EE mapping data in nature protection, environmental degradation, and climate agendas, and define components of the usability of geospatial data products as operational solutions. For that, we analyzed global and regional policy frameworks and corporate reporting standards to determine EE-related data needs, alongside bottlenecks shaped by domain-specific challenges, such as thematic complexity of ecosystem definitions, high costs of in-situ monitoring, and demands of data processing workflows to capture dynamic and complex entities. Finally, we translated these findings into a checklist to design policy- and reporting-ready products, covering relevance, thematic coherence, reliability of mapping outputs defined by validation and uncertainty quantification, and transparency of data and methods contributing to the achievement of shared policy targets
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! 👇