157082 research outputs found
Sort by
Mathematical models for the EP2 and EP4 signaling pathways and their crosstalk
No full textG protein-coupled receptors EP2 and EP4 are both activated by the lipid messenger Prostaglandin E2 (PGE2) and induce the intracellular production of cyclic AMP (cAMP), ultimately affecting gene expression. Changes in cellular responses to PGE2 can have important consequences on immunity and disease, yet a detailed understanding of the EP2-EP4 signaling network is lacking. EP2 and EP4 are often co-expressed in cells but their specific contribution to cAMP production is poorly understood. Experimental data have shown that cAMP levels differ depending on whether PGE2 triggers EP2 or EP4, or both. To better understand the underlying mechanisms and predict cellular responses to PGE2, we developed mathematical models for EP2 and EP4 cAMP signaling, including receptor crosstalk. The mathematical models qualitatively reproduce the experimentally observed cAMP levels and provide mechanistic insight into both the differences and commonalities in EP2/EP4 signaling. We found that ligand binding dynamics play a crucial role for both single-receptor signaling and inter-receptor crosstalk. Inhibition of PGE2 signaling via receptor antagonists is gaining increasing attention in tumor immunology. These mathematical models could therefore contribute to the design of more effective anti-tumor therapies targeting EP2 and EP4
Characteristics of Wind Field Observed by Synthetic Aperture Radar and Microwave Radiometer in Tropical Cyclone
No full textWind field structure of tropical cyclone (TC) can be resolved by remotely sensed sensors operated at microwave frequency, i.e. synthetic aperture radar (SAR) and microwave radiometer. The main purpose of this study is to investigate the characteristics of TC wind observed by Sentinel-1 (S-1) and soil moisture active passive (SMAP) during over 100 TCs from 2016 to 2023. The swath coverage of CyclObs winds inverted from S-1 images is about 500 km with a spatial resolution of about 500 m, while the SMAP wind products have a swath coverage of 1000 km with spatial resolution of 0.25° grids. Three TC parameters, geographic location of eye, maximum wind speed and radius of maximum wind speed, 34, 50, and 64 knot (kt) wind radii are estimated from CyclObs and SMAP winds. It is found that the distance between TC eyes derived from these two remote-sensed products and those from International Best Track Archive for Climate Stewardship (IBTrACS) reanalysis increases with central pressure increasing. Compared with IBTrACS data, the Root Mean Squared Error (RMSE) and Correlation Coefficient (COR) of maximum wind speed by CyclObs are 9.94 m s–1 and 0.63, whereas those by SMAP are 12.34 m s–1 and 0.51. In contrast, about 23 m RMSE of radius of maximum wind speed and about 0.7 COR is achieved from both CyclObs and SMAP winds. Here, the angle is defined as follows: 0°−135° clockwise relative with TC movement represents the right side, 135°−225° represents the back side, and 0°−135° counterclockwise represents the left side. The angle between the maximum wind velocity direction relative to TC translation direction (forward direction) is not correlated well with NHC maximum wind speed or NHC radius of maximum wind speed. Interestingly, as the radius of maximum wind speed increases, the angle in CyclObs wind increases at the back and left sides of TC centre, whereas the angle decreases at the right side. This behaviour is only observed at the left side in SMAP wind
Impact of Emissions Mitigation Technologies on the Costs of a CO<sub>2</sub> Capture Plant for a Generic Refinery Process Flue Gas
No full textCarbon capture is a necessary tool to support the energy transition and help companies and countries reach their climate targets. Amine-based absorption is the most mature technology for postcombustion carbon capture. Understanding solvent behavior in relation to degradation and emissions is crucial for the implementation of such a process. However, this task proved to be extremely difficult as the behavior is dependent on several factors, including the solvent formulation, the flue gas composition, the capture rate, and the reboiler temperature, to cite some. This work investigates the impacts of a few selected technologies to handle emissions on the costs of implementing a capture plant in a refinery. The cases were evaluated using two solvents, 30 wt % MEA and CESAR1, where simulations were conducted to assess the process performance and size of the main plant equipment. A cost methodology was used to compare the cases where it shows that the configuration with water wash, dry bed, and acid wash was the most technically and economically efficient. Using the proposed methodology shows that operating the capture plant with CESAR1 is more economical than with 30 wt % MEA mainly due to the difference in regeneration costs (i.e., steam costs)
From Haskell to a New Structured Combinator Processor
No full textThis paper presents KappaMutor, a new graph reduction processor, along with its Haskell compiler. KappaMutor is based on structured combinators, a recently proposed combinator encoding, which is more flexible and efficient than fine-grained SKI combinators. The processor exploits parallel memories to enable single-cycle reduction of structured combinators while maintaining good compactness, utilising less than 1% of the logical resources on a modern FPGA. Its Haskell compiler implements novel code generation strategies designed to minimise combinator usage and achieve full laziness --- the first such implementation for structured combinators, to the best of our knowledge. Based on our measurements, structured combinators can reduce runtimes by 9% to 58%, compared to running equivalent SKI combinator programs on KappaMutor
An effective combination of mechanisms for particle swarm optimization-based ensemble strategy
No full textA high-quality ensemble strategy can effectively integrate several coefficients, mechanisms, and algorithms into a single framework. The adaptability, timing of intervention, and complementarity are the key factors to consider for the selected coefficients, mechanisms, and algorithms. In this study, two complementary variants based on Particle Swarm Optimization (PSO), namely Modified PSO (MPSO) and Social Learning PSO (SLPSO), were selected, forming IMPSO and ISLPSO after improvements. IMPSO excels at exploration, while ISLPSO excels at exploitation. The Improved Novel Ratio Adaptation Scheme (INRAS) is employed as a selection strategy and provides the ability to abandon less-optimal particles. The Modified Nonlinear Population Size Reduction (MNLPSR) enables the extension of generations, allowing for more sufficient evolution in later stages. Due to the use of MNLPSR, an improved inertia weight and adaptive acceleration coefficients are introduced to ensure compatibility with the proposed algorithm. Additionally, an improved dynamic differential mutation strategy is designed not only to be compatible with the proposed algorithm but also to enhance particle diversity. Both the Improved Sine Cosine Algorithm (ISCA) and Sequential Quadratic Programming (SQP), which focus on searching near the global best particles, are incorporated into the proposed ensemble strategy. This PSO-based variant is named the Effective Combination of Mechanisms for a PSO-based Ensemble Strategy (ECM-PSOES). Ablation experiments demonstrated the effectiveness of the individual coefficients and mechanisms. The novel PSO-based variant was evaluated on the CEC2017 benchmarks and compared with 14 state-of-the-art PSO-based variants and 11 non-PSO algorithms. Additionally, to evaluate the flexible and robust capability of the proposed algorithm, three real-world applications for long-term Transmission Network Expansion Planning (TNEP), Planetary Gear Train Design (PGTD), and Robot Gripper Design (RGD) were tested. The experimental results illustrate that the proposed algorithm displays superior performance compared to recently proposed PSO-based variants and most non-PSO algorithms. However, the proposed algorithm falls short of outperforming Differential Evolution (DE)-based algorithms and still requires time to match the performance of top-tier metaheuristics. The source code of ECM-PSOES is provided at https://github.com/microhard1999/CODES
Green electrospinning synthesis of NiO/Ni nanofiber for efficient soap removal from crude biodiesel
No full textThis study explores the eco-friendly synthesis of NiO/Ni nanocomposites (NC) utilizing Pistacia lentiscus leaf extract as a natural reducing agent, aimed at enhancing biodiesel purification through efficient soap removal. The NiO/Ni NCs were synthesized as powders and as electrospun nanofibers (NiO/Ni@PVA), and were characterized using UV–visible spectroscopy, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and BET surface area analysis. The NiO/Ni@PVA nanofibers exhibited superior soap removal efficiency, reducing the soap content from 4671 ppm to 13.5 ppm, compared to 19.5 ppm for the powdered form. The BET analysis confirmed a mesoporous structure with a specific surface area of 4.36 m²/g and a pore diameter of ~16 nm, facilitating enhanced molecular diffusion and adsorption. The TGA results revealed that NiO/Ni NC exhibited minimal total mass loss of 8.14% up to 800 °C, confirming excellent thermal stability. In contrast, NiO/Ni@PVA nanofibers showed multi-step degradation with a total loss of ~96.7%, primarily due to PVA decomposition, leaving thermally stable NiO/Ni residues. The effectiveness of these NCs in soap removal was evaluated under varying contact times, adsorbent dosages, and stirring speeds. Adsorption isotherm analyses indicated a chemisorption-dominated mechanism with strong monolayer binding, supported by high qₘₐₓ values of 2007 mg/g for NiO/Ni and 2497 mg/g for NiO/Ni@PVA, and excellent correlation with the Langmuir adsorption isotherm. The nanofibers also demonstrated high reusability across multiple cycles. Additionally, computational simulations validated the strong interaction between the soap molecules and the nanocomposite surface. These findings underscore the potential of NiO/Ni@PVA nanofibers as thermally stable, efficient, reusable, and environmentally friendly adsorbents for sustainable biodiesel purification
Is Omni-Channel Retailing the Future of Luxury Fashion Brands?
No full textIn the contemporary digital era, the rapid development of new technology and technological innovation, especially in the fields of artificial intelligence, augmented reality, virtual reality, multifunctional social media and e-commerce have completely altered consumers’ lifestyles and their communication and consumption behaviour. Therefore, in order to achieve sustainable success and satisfy these consumers’ needs in terms of psychological and functional benefits, retailers, including luxury fashion brands, need to implement advanced technology in their branding strategies, marketing communication and distribution strategies (Passavanti et al., 2020; Pantano et al., 2022). That they are already doing so is evidenced by the increasing number of luxury fashion brands which have developed multiple channel distribution strategies and phygital consumer experiences (a term referring to overall experiences across online and offline experiences) to create interactive experiences through the combination of digital channels with brick-and-mortar stores (Hyun et al., 2022; Bartoli et al., 2023)
Investigating the voltaic efficiency of 3D-printed macro-patterned electrodes for hydrogen evolution reactions in water electrolysis
No full textConventional electrodes of water electrolysis face limitations in mass transport and bubble detachment, hindering sustainable hydrogen production. This study investigates the enhancement of hydrogen evolution reaction (HER) efficiency in water electrolysis using 3D-printed macro-patterned 17-4 PH-grade stainless steel electrodes. Leveraging additive manufacturing, stainless steel-based electrodes were fabricated via 3D printing, debinding and sintering, featuring three distinct macro-patterns namely small and large semi-spherical dimples, as well as pyramidal pits. Electrochemical testing using chronoamperometry and efficiency calculations, using KOH electrolyte in a H-cell setup, revealed that patterned electrodes significantly outperformed their flat counterparts. Results show up to a 6.5-percentage point higher voltaic efficiency, and visual observation revealed enhanced bubble detachment. Scanning Electron Micrography (SEM) imaging confirmed inherent microporosity from 3D printing, increasing active surface area. The pyramidal-pit electrode initiated HER at lower voltages, while dimpled designs achieved higher peak current densities. The experimentally measured current densities showed good agreement with the Butler–Volmer model with electrode surface bubble coverage considered. An empirical model developed, shows a strong correlation between the cell’s normalised voltaic efficiency, the non-dimensional current density and the non-dimensional surface area, highlighting the critical role of surface geometry in the efficiency of electrolysis cells. Gold coating reduced ohmic losses but did not consistently improve hydrogen yield. These results add to the growing experimental evidence that 3D-printed macro-patterns are beneficial, and in this case, enabled by an innovative metal additive manufacturing process. HER voltaic efficiency is boosted by at least 5 percentage points for a flat electrode of the same form factor through optimised bubble management and surface area. The study hence underlines the importance of patterned electrodes for industrial green hydrogen production with attendant tangible economic and sustainability benefits
Corporate governance characteristics, shareholder dissent and agency cost of debt
No full textWe examine how shareholder dissent both affects and is affected by agency cost of debt, using credit ratings as a proxy. Specifically, we explore (1) whether agency costs of debt trigger dissent differently across corporate governance regimes characterized by greater stakeholder collaboration versus those with stronger shareholder dominance, and (2) whether credit rating agencies' subsequent responses to dissent vary across these regimes. We find evidence that dissent is lower when ratings are higher, but there is limited evidence that shareholders in more collaborative regimes dissent more. Dissent tends to improve subsequent credit ratings when shareholders are highly dominant, but this effect diminishes in more coordinated governance systems. This evidence suggests that dissent shifts power toward shareholders, which is more costly to debtholders in governance systems that are based on collaboration among stakeholders
Multi-Modal Multi-Stage Multi-Task Learning for Occlusion-Aware Facial Landmark Localisation
No full textThermal facial imaging enables non-contact measurements of face heat patterns that are valuable for healthcare and affective computing, but common occluders (glasses, masks, scarves) and the single-channel, texture-poor nature of thermal frames make robust landmark localisation and visibility estimation challenging. We propose M3MSTL, a multi-modal, multi-stage, multi-task framework for occlusion-aware landmarking on thermal faces. M3MSTL pairs a ResNet-50 backbone with two lightweight heads: a compact fully connected landmark regressor and a Vision Transformer occlusion classifier that explicitly fuses per-landmark temperature cues. A three-stage curriculum (mask-based backbone pretraining, head specialisation with a frozen trunk, and final joint fine-tuning) stabilises optimisation and improves generalisation from limited thermal data. On the TFD68 dataset, M3MSTL substantially improves both visibility and localisation: the occlusion accuracy reaches 91.8% (baseline 89.7%), the mean NME reaches 0.246 (baseline 0.382), the ROC–AUC reaches 0.974, and the AP is 0.966. Paired statistical tests confirm that these gains are significant. Our approach aims to improve the reliability of temperature-based biometric and clinical measurements in the presence of realistic occluders
Access Repository Dashboard
Do you manage Heriot Watt Pure? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!