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COMPUTATIONAL AND EXPERIMENTAL ASSESSMENT OF AORTIC AND ATRIAL FLOWS
No full textCardiovascular diseases and their treatments can significantly alter blood flow dynamics, impacting patient outcomes. Understanding these flow changes is critical for optimizing device design, refining treatment strategies, and improving clinical decision making. This dissertation is divided into a flow dynamics assessment of the aorta and left atrium (LA).
Aortic stenosis (AS) is the most common valvular heart disease worldwide, with aortic valve replacement (AVR) being the only effective treatment. Hypertension (HTN) is common in patients with AS, and blood pressure (BP) often remains high after AVR. While HTN is typically associated with negative outcomes, it is actually lower BP, not higher, that has been linked to worse outcomes after AVR. The studies presented in this dissertation suggest that higher BP after AVR may help maintain sufficient epicardial coronary flow to prevent myocardial ischemia. However, elevated BP may also contribute to the initiation and acceleration of calcific changes in bioprosthetic leaflets, potentially leading to valve degeneration.
Bioprosthetic valve performance is an important factor following AVR. Benchtop testing of AVs often excludes the aortic arch, yet findings show that the arch has a pressure recovery zone, which is relevant for catheter-based pressure measurements of bioprosthetic valve performance. Lastly, stroke remains a major concern after AVR, with no clear predictors identified for stroke risk following transcatheter aortic valve replacement (TAVR). Stroke risk assessments in TAVR candidates revealed that anatomical and geometric parameters may serve as potential correlates of stroke after TAVR.
Atrial fibrillation (AF) is the most common arrhythmia worldwide and is associated with an increased risk of stroke. While catheter ablation can restore the heart to sinus rhythm, its impact on left atrial flow dynamics remains unclear. Flow assessments of the left atrium (LA) before and after ablation revealed distinct changes in flow mixing, vortex patterns, velocity, and wall shear stress (WSS) distributions, suggesting that ablation techniques may induce flow alterations that could be thrombogenic over time. The left atrial appendage (LAA) is a common site of thrombosis in AF patients, and its occlusion can help reduce stroke risk. However, a small percentage of patients develop device related thrombosis (DRT) after left atrial appendage occlusion (LAAO). Findings from the LAAO study indicated that DRT positive patients exhibited worse flow parameters at the atrial surface of the LAAO device, with regions of low time averaged WSS (TAWSS) closely aligning with clinically identified thrombus locations.
This dissertation work aims to improve our understanding of aortic and atrial flow dynamics in the context of cardiovascular disease and its treatment, bridging the communication gap between engineers and clinicians to facilitate the translation of engineering research into clinical practice
ESTERASE-DEPENDENT RED-TO-BLUE FLUORESCENCE COLOR CHANGE IN COUMARINS: SMALL FLUOROPHORES FOR LIVE DEAD CELL SENSING
No full textCoumarins have been widely utilized in designing fluorescent reporters that possess target-specific outputs. However, the coumarin core as a supporter of color-changing properties without extensive derivatization has not yet been achieved. Here, we report a small library of coumarin esters capable of red-to-blue fluorescence upon hydrolysis by cellular esterase. By stabilizing the red-transition through C4 coumarin substitution and the blue-shifted transition through C7 coumarin substitution this generates a color-changing scaffold of ~150 nm difference between the two transitions.
Varying alkyl and aryl C4-carboxylate substitution allowed for tuning of fluorescence and hydrolytic efficiency. These probes display fast cellular uptake and esterase dependent color change in live cells allowing for detection under both the red and blue channel. However, in dead cells the probes are only detectable in the red channel. This identifies alkyl and aryl 7-hydroxy-4-carboxy coumarins as small color-changing tools for live-dead cell analysis and markers for cellular esterase activity
TEST STAND DEVELOPMENT: AN ANALYSIS OF EXCAVATION FORCES WITHIN A SIMULATED LUNAR ENVIRONMENT
Get PDFSpace exploration has rapidly developed in recent years as scientists look to the lunar surface for water ice in permanently shadowed regions. The excavation and decomposition of water outside of Earth’s atmosphere could provide in-situ resources for propellant manufacturing and sustaining life. However, without informed design parameters for lunar exploration and infrastructure development, time will be wasted on systems unfit for the harsh environment. Testing facilities that simulate the environmental conditions are required to better understand the forces these complex systems may face while extraterrestrial.
The force test stand is a unique mechanism that collects tensile and compressive force data within temperatures ranging from -40 to 20℃. At these temperatures, MTU-LHT-1A Lunar Highland Simulant [1] with varying water ice weight percentages can be dry-mixed [2] and excavated to accurately simulate lunar conditions. Eight S-type load cells are placed throughout the frame to collect force readings from the resulting interactions between the mounted system and regolith simulant. These results can further inform design revisions for weight and power reduction before the system is sent offworld
ThermalTrack Dataset - Training Labels - sequence 1-11
Get PDFWe present a wheel track detection system that leverages RGB-Thermal (RGB-T) imaging, where thermal channels reveal critical temperature differentials between compacted tracks and loose snow - tracks exhibit higher thermal inertia and lower reflectivity, emitting stronger radiation signatures even in visually homogeneous conditions. By fusing these distinctive thermal patterns with RGB spatial information, our method reliably identifies navigable tracks, enabling robust path-following in complete white-out conditions where snow textures and terrain features become indistinguishable
Bridging social and ecological science to create spatially explicit models of human-caused mortality of carnivores
Get PDFResearch indicates that human-caused mortality (HCM) is a key factor limiting numerous large carnivore populations. However, efforts to represent HCM in spatially explicit models have generally been limited in scope-often relying on proxies, such as road or human density. Yet such efforts fail to distinguish different sources of HCM, which can arise from different antecedent processes. We offer a systems-based conceptual framework for understanding the antecedents of HCMs that is grounded in theory from the social and behavioral sciences. Specifically, we first explain how HCMs are usefully distinguished into four types (e.g., accidental, harvest, illicit, control actions), then discuss how these different types tend to be driven by different sets of psychological and sociopolitical processes. We contend that improvements in understanding the spatial variation in HCMs would rise from more explicit attention to the various antecedent processes that precede each mortality type
Bio-Inspired Highest Lift-to-Drag-Ratio Fin Shape and Angle for Maximum Surfboard Stability: Flow Around Fish Fins
Get PDFWave surfing is a multi-billion dollar industry involving both maneuverability and speed, yet little research has been performed regarding the highest lift-to-drag-ratio fin shape for these competing qualities. Numerical modeling and laboratory experiments were performed here to identify a bio-inspired fin shape that maximized lateral stability and minimized drag forces, in order to increase surfing maneuverability. Nine fins based on dorsal fins of real fish were tested. Both the CFD and laboratory experiments confirmed that the fin of the same shape as that of the Short-Finned Pilot Whale at an angle of attack of 10° had the greatest lift-to-drag ratios. Flow patterns around fins at a low angle of attack were smooth with negligible flow separation, while at any angle of attack greater than 25°, flow-separation-induced drag forces became excessive
A novel surfactant S-[(2-hydroxyamino)-2-oxoethyl]-N,N-dibutyldithiocarbamate with flotation performance and hydrophobicity to cassiterite
No full textGrowing attention has been drawn to exploring effective collectors in the mining industry to make full use of the important cassiterite resource. Dithiocarbamate ester surfactant is deemed a promising collector group. In this work, researchers utilize S-[(2-hydroxyamino)-2-oxoethyl]-N, N-dibutyl-dithiocarbamate (HABTC) and octylhydroxamic acid (OHA) to conduct flotation tests of cassiterite. It was found that HABTC achieved a better flotation performance and realized a successful flotation enrichment of cassiterite particles, which was consistent with the hydrophobicity determination by ClogP, and the excellent performance of its bifunctional molecular structure. Moreover, researchers systematically investigated the adsorption mechanism of HABTC towards cassiterite surfaces. Results of Zeta potential and Ultraviolet/visible(UV/vis) measurements proved the occurrence of a chemisorption interaction between Sn4+ ions and HABTC. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that HABTC likely reacted with the Sn(IV) atoms on the cassiterite surface. It was hypothesized that the reaction occurred through the group between S atom of the N-C(=S) and O atom of −C(=O)N-OH in HABTC, producing complexes and the group might act as a hydrophilic group for calcite flotation, however as a chelating group for cassiterite flotation, leading to HABTC\u27s lower flotation recovery of calcite and its excellent collecting properties towards cassiterite. The universal mechanism revealed in this work shows strong potentials for broader applications of HABTC in cassiterite flotation
Global to local: a novel encoder-decoder framework for urban real-time rainfall-runoff forecasting
No full textUrban real-time rainfall-runoff forecasting (URRF) offers an economical and efficient approach to assessing flood risks in urban areas. However, the hydrological processes of urban rainfall are characterized by high nonlinearity and long-term dependencies due to strong uncertainties and significant human influences, making URRF a challenging task in hydrological simulation. Existing methods often fall short in meeting the requirements for real-time response and accuracy. To address these limitations, this paper proposes a novel global-encoder and local-decoder (GL-ED) model. The global encoder extracts global temporal features, while the local decoder focuses on forecasting. A temporal fully connected (TFC) module is introduced within the global encoder to capture the global features of runoff sequences, overcoming the limitation of convolutional operations that primarily focus on local information. Additionally, to tackle the uneven distribution of urban rainfall-runoff data, a novel RD loss function is proposed, combining dynamic time warping (DTW) with RMSE to better guide the training of complex features. The GL-ED model was evaluated using observed urban rainfall events from January 2018 to December 2019 in a 3.52 km2 complex terrain area in Chongqing, China. Experimental results demonstrate that the GL-ED model outperforms conventional deep learning models, including convolutional neural networks (CNNs), recurrent neural networks (RNNs), and long short-term memory (LSTM) networks, in terms of NSE, MAE, and RMSE. In ablation experiments, the GL-ED model trained with the RD loss function achieved an average improvement of 2.51% in NSE and 5.62% in KGE, while reducing RMSE, MAE, and Pbias by 6.08%, 11.31%, and 93%, respectively. These findings highlight the model’s capability to provide reliable and accurate real-time rainfall-runoff forecasting, offering significant potential for enhancing urban flood risk management and decision-making processes
A review of direct ink writing of polymer derived ceramics
Get PDFWith the growing demand for materials capable of withstanding extreme temperatures and pressures, ceramic components with exceptional corrosion resistance and reliable mechanical properties have experienced a significant surge in demand. However, traditional ceramic forming methods involve high-temperatures and energy-intensive processes that often struggle to produce complex parts or composites efficiently. Polymer-Derived Ceramics (PDCs) offer a transformative solution by using polymeric precursors that can be converted into a wide variety of silicon-based and non-silicon-based ceramics through heat treatment. The polymeric nature of PDC precursors enables the fabrication of geometrically intricate components using conventional polymer-forming techniques at significantly lower processing temperatures. Furthermore, PDCs are well-suited for additive manufacturing (AM), allowing the production of complex structural and functional components through cost-effective, low-temperature processes. By leveraging the diverse properties of PDC materials–each with unique advantages and limitations–manufacturers can optimise performance for specific applications. This review provides an overview of the types of PDCs developed to date and their broad range of applications. Specifically, it delves into the Direct Ink Writing (DIW) process, exploring its rheological requirements and the critical role of fillers in tailoring the rheological properties of polymeric precursors to meet the specific demands of DIW
3rd Workshop on Maritime Computer Vision (MaCVi) 2025: Challenge Results
No full textThe 3rd Workshop on Maritime Computer Vision (MaCVi) 2025 addresses maritime computer vision for Unmanned Surface Vehicles (USV) and underwater. This report offers a comprehensive overview of the findings from the challenges. We provide both statistical and qualitative analyses, evaluating trends from over 700 submissions. All datasets, evaluation code, and the leaderboard are available to the public at https://macvi.org/workshop/macvi25