1,604 research outputs found

    Flood dynamics derived from video remote sensing

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    Flooding is by far the most pervasive natural hazard, with the human impacts of floods expected to worsen in the coming decades due to climate change. Hydraulic models are a key tool for understanding flood dynamics and play a pivotal role in unravelling the processes that occur during a flood event, including inundation flow patterns and velocities. In the realm of river basin dynamics, video remote sensing is emerging as a transformative tool that can offer insights into flow dynamics and thus, together with other remotely sensed data, has the potential to be deployed to estimate discharge. Moreover, the integration of video remote sensing data with hydraulic models offers a pivotal opportunity to enhance the predictive capacity of these models. Hydraulic models are traditionally built with accurate terrain, flow and bathymetric data and are often calibrated and validated using observed data to obtain meaningful and actionable model predictions. Data for accurately calibrating and validating hydraulic models are not always available, leaving the assessment of the predictive capabilities of some models deployed in flood risk management in question. Recent advances in remote sensing have heralded the availability of vast video datasets of high resolution. The parallel evolution of computing capabilities, coupled with advancements in artificial intelligence are enabling the processing of data at unprecedented scales and complexities, allowing us to glean meaningful insights into datasets that can be integrated with hydraulic models. The aims of the research presented in this thesis were twofold. The first aim was to evaluate and explore the potential applications of video from air- and space-borne platforms to comprehensively calibrate and validate two-dimensional hydraulic models. The second aim was to estimate river discharge using satellite video combined with high resolution topographic data. In the first of three empirical chapters, non-intrusive image velocimetry techniques were employed to estimate river surface velocities in a rural catchment. For the first time, a 2D hydraulicvmodel was fully calibrated and validated using velocities derived from Unpiloted Aerial Vehicle (UAV) image velocimetry approaches. This highlighted the value of these data in mitigating the limitations associated with traditional data sources used in parameterizing two-dimensional hydraulic models. This finding inspired the subsequent chapter where river surface velocities, derived using Large Scale Particle Image Velocimetry (LSPIV), and flood extents, derived using deep neural network-based segmentation, were extracted from satellite video and used to rigorously assess the skill of a two-dimensional hydraulic model. Harnessing the ability of deep neural networks to learn complex features and deliver accurate and contextually informed flood segmentation, the potential value of satellite video for validating two dimensional hydraulic model simulations is exhibited. In the final empirical chapter, the convergence of satellite video imagery and high-resolution topographical data bridges the gap between visual observations and quantitative measurements by enabling the direct extraction of velocities from video imagery, which is used to estimate river discharge. Overall, this thesis demonstrates the significant potential of emerging video-based remote sensing datasets and offers approaches for integrating these data into hydraulic modelling and discharge estimation practice. The incorporation of LSPIV techniques into flood modelling workflows signifies a methodological progression, especially in areas lacking robust data collection infrastructure. Satellite video remote sensing heralds a major step forward in our ability to observe river dynamics in real time, with potentially significant implications in the domain of flood modelling science

    Fluid-Rock Interactions from the Lithosphere to Earth’s Surface

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    Fluids can cycle and migrate through planetary bodies, transporting soluble ions and influencing physical properties of the surrounding rock or magma, such as fracture toughness, seismic wave velocity, melting point, viscosity, and more. Precipitated minerals, fluids trapped in inclusions, and free pore fluids can be used to constrain fluid provenance, mixing relationships, and paleoenvironmental information such as temperature, pressure, redox conditions, salinity, and pH. In my thesis, I discuss my research on topics pertaining to the geochemistry associated with fluid-rock interactions that occur from the depths of the lithospheric mantle to Earth’s surface. Broadly, these chapters address open questions pertaining to 1) the retention timescales and metasomatic overprinting of fluids sourced from the mantle in obducted peridotites, 2) the capacity for pedogenic Mg-carbonates to preserve palaeohydrological information with implications for Martian carbonates, and 3) the influences hydrous fluids have on lithospheric magmas and minerals. Helium isotopes are arguably the best tracer for fluid sources in Earth materials at the planetary scale. ³He/⁴He ratios of the Earth’s 1) continental crust, 2) atmosphere, 3) upper mantle, and 4) core or deep isolated mantle (mantle plume source) vary by over two orders of magnitude, offering considerable dynamic range compared to measurement precision. While helium isotope signatures in Earth’s mantle have been determined almost exclusively by the analysis of helium retained in mantle xenoliths, phenocrysts, erupted glasses, and vent gases, this selection introduces a sampling bias towards fluids that have been transported to Earth’s surface by eruptive processes. In contrast, residual mantle peridotites take much longer to arrive at Earth’s surface and are therefore more susceptible to metasomatic processes that can overprint primary helium isotopic signatures. In Chapter 1, I use concentrations and isotopes of helium and argon along with concentrations of U and Th to place constraints on the sources and siting of helium retained in exhumed mantle peridotites collected from Twin Sisters Mountain of the Northern Cascades in Washington State, USA. Helium isotope ratios of peridotites from the Twin Sisters Mountain span from 0.8 to 6 times the atmospheric ratio (1RA=1.4*10⁻⁶ ³He/⁴He). Fluid inclusions in these peridotites capture a two-component mixture that included a mantle-like endmember (~6 RA) and a serpentinizing endmember (1.0 ± 0.5 RA) that is consistent with a mixture of surface-derived groundwater, leached crustal radiogenic helium and reworked mantle helium. While these components are not effectively isolated by extraction using vacuum crushing and powder fusion, step-heating analysis reveals that the serpentinizing endmember is released at lower temperatures (&#60;1000°C) and the mantle-like endmember is released at higher temperatures. Results demonstrate that helium signatures can be retained in lithospheric peridotites against both diffusive loss and radiogenic ingrowth over at least 10⁸-year timescales but can be greatly modified by cryptic metasomatic processes during emplacement. Mg-carbonates have become increasingly relevant in the scientific community due to their orbital and in situ detection on the Martian surface. Like Ca-carbonate on Earth, Martian Mg-carbonates may preserve paleoenvironmental information associated with their formation on Mars billions of years ago, shedding light on habitability. Yet, unlike Ca-carbonates, the capacity for Mg-carbonates to preserve paleoenvironmental information through trace element signatures associated with their source fluids has not been well established for surficial magnesite samples on Earth. In Chapter 2, I 1) develop a digestion protocol to selectively digest Mg-carbonates (magnesite ± dolomite) while obviating influences of contaminant phases and ions adsorbed to mineral surfaces, 2) validate a method to analyze trace elements with Mg-matrix by solution ICP-MS, and 3) apply these procedures to determine trace element concentrations of pedogenic Mg-carbonates sampled along a depth profile in the Kunwarara open pit magnesite mine in Queensland, Australia. Results from this study confirm that the method we implemented selectively digests magnesite ± dolomite. A relationship between negative Ce anomaly in the carbonates and Fe/Mn-oxides/hydroxides in corresponding host sediment collected along the depth profile demonstrates that pedogenic magnesites can capture redox gradients in the soil column. This finding implies that Ce anomaly in carbonates can potentially be used to place constraints on the paleo-redox conditions associated with Mg-carbonate formation on ancient Mars. Numerous questions in Earth science depend on quantitative understanding of how elements fractionate during melting and crystallization. To name a few: assessment of how lithospheric fluids influence geodynamical processes, constraining mechanisms that led to the formation of the Earth’s continental crust, evaluation of elemental fluxes from the mantle to Earth's surface, calibration of a reliable crustal barometer, and gauging how magmatism and plate tectonics differed with the higher geothermal gradients of a younger Earth. MELTS thermodynamic software is a widely available free tool utilized by geoscientists to both test hypotheses and model the geochemistry of magmatic processes. However, minerals of the amphibole supergroup, although common in magmatic systems, rarely crystallize in MELTS simulations, even when well controlled experiments demonstrate that they should. The decrease in the Gibbs energy needed to stabilize amphibole in MELTS is often on the order of the configurational entropy contribution to the Gibbs energy associated with minor elements that are not present in any of the current amphibole solution models used in MELTS but are frequently incorporated in the amphibole crystal lattice. In Chapter 3, I outline a framework for a volume model for monoclinic amphiboles that can be used in an expanded amphibole solution model to be incorporated in MELTS software. A volume model is prerequisite to calibrating the other model terms because it accounts for differences in pressure among experimental constraints. The framework I develop extends the model to include minor components that are not present in existing versions of the MELTS amphibole models. I calibrate a preliminary model using a dataset composed of x-ray refinements that supply amphibole volume and site occupancy data. Results reveal regions in parameter space where data is limited and the sensitivity that model coefficients have to uncertainties in the data, suggesting that filtering the dataset to remove outliers may be necessary.</p

    30th European Congress on Obesity (ECO 2023)

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    This is the abstract book of 30th European Congress on Obesity (ECO 2023

    Investigating signalling pathways that influence stem cell self-renewal and differentiation

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    Adult tissue homeostasis relies on stem cells dividing to provide cells that differentiate and replenish lost cells. To prevent depletion of the stem cell pool, some of the daughter cells resulting from stem cell divisions retain stem cell identity and continue to proliferate, or self-renew. How stem cell self-renewal and differentiation are balanced is poorly understood. The niche, in which stem cells reside, provides spatially restricted signals that promote self-renewal. Daughter cells displaced away from the niche are thought to differentiate upon losing access to such signals. The sequence of events that occurs leading up to and following stem cell division is not well-understood. The Drosophila testis is a well-characterised model to study these behaviours. Here, cyst stem cells (CySCs) give rise to cyst cells that support germline development. Previous work in fixed tissues has shown that dysregulating CySC signalling can bias CySC fate outcomes. It remains to be demonstrated that, under normal physiological conditions, endogenous differences in signalling pathway activity are responsible for stem cell fate. In this thesis, I present evidence that differentiation in the Drosophila testis is not a default state upon losing access to niche-derived signals but is actively induced by signalling, and that the germline also plays a role in CySC differentiation. To visualise signalling dynamics in vivo, we have adapted a kinase activity biosensor from mammalian cell culture. I demonstrate that this biosensor faithfully reports kinase activity in both larval and adult tissues, and that it can be implemented with live imaging to study real-time signalling dynamics in individual cells. Finally, I characterise CySC behaviours under normal physiological circumstances using time-lapse live imaging of adult Drosophila testis explants. Based on these data, I discuss the role that signalling pathways play in maintaining the balance between self-renewal and differentiation of stem cells during normal homeostasis

    New perspectives in surgical treatment of aortic diseases

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    Biomaterials for Bone Tissue Engineering 2020

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    This book presents recent advances in the field of bone tissue engineering, including molecular insights, innovative biomaterials with regenerative properties (e.g., osteoinduction and osteoconduction), and physical stimuli to enhance bone regeneration

    The Brazilian Flute Topic

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    Title from PDF of title page, viewed May 17, 2023Dissertation advisor: Noel Torres-RiveraVitaIncludes bibliographical references (pages 208-235)Dissertation (D.M.A.)--Conservatory of Music and Dance. University of Missouri--Kansas City, 2023This dissertation studies the connection between the flute, in its materiality and function, and ideas on Brazilianness. A question permeates the narrative I propose: why has the flute become an instrument so representative of Brazilian culture? By presenting a general overview of discourses on Brazilian musical nationalism in relation to social, political, and racial configurations, I analyze how the always-shifting concept of Brazilianness was transformed throughout history, and how the flute can be understood as one of its most distinctive symbols. To this end, I offer several perspectives from modernist authors such as Mário de Andrade to contemporary scholars such as Maria Eugênia Boaventura. Drawing on ideas proposed by music scholars such as Melanie Plesch, Raymond Monelle, and Michael Klein with regard to topic theory, I analyze how the flute and its sonority appear represented and/or used in Brazilian iconography, literature, and musical practices from colonial times up to the 1940s, also paying attention to issues of class, race, and politics. Through this broad cultural analysis, I build a network of signs, a code for what I call the Brazilian Flute Topic. Although the study of the Brazilian Flute as a cultural unit is an end in itself, I also develop analyses of three twentieth-century works for flute solo by composers deemed as nationalist: Melopéias n.3 (1950) by César Guerra-Peixe (1914-1993); Fantasia Sul América (1983) by Claudio Santoro (1919-1989); and Improviso (1974) by Osvaldo Lacerda (1927-2011). My goal is to explore the ways in which we can interpret such works through the cultural code I develop, suggesting new perspectives for their study, and with it, illustrating the potential of topic theory and semiotics in the study of Brazilian art music.Introduction -- Brazilian nationalism in perspective -- On the cultural unit of the Brazilian flute -- On the cultural unit of the Brazilian flute: Music -- Analysis of three Brazilian music for solo flut

    Outdoor Insulation and Gas Insulated Switchgears

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    This book focuses on theoretical and practical developments in the performance of high-voltage transmission line against atmospheric pollution and icing. Modifications using suitable fillers are also pinpointed to improve silicone rubber insulation materials. Very fast transient overvoltage (VFTO) mitigation techniques, along with some suggestions for reliable partial discharge measurements under DC voltage stresses inside gas-insulated switchgears, are addressed. The application of an inductor-based filter for the protective performance of surge arresters against indirect lightning strikes is also discussed
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