Equilibrium Analysis Research Articles

Effect of furosemide on comprehensive renin-angiotensin-aldosterone system activity of Thoroughbred horses.

Furosemide, a commonly used diuretic, activates the renin-angiotensin-aldosterone system (RAAS) in other species. Little is known about RAAS peptide activation in horses. To evaluate equilibrium analysis as a practical method for RAAS quantification in horses and describe the RAAS response to a single dose of furosemide. We hypothesize that furosemide would cause transient increase in RAAS peptides in horses. 14 healthy adult thoroughbreds from a university teaching herd. Horses received either furosemide (1 mg/kg IV) or saline IV in a crossover study design. Protease-inhibited samples were compared with equilibrium analysis samples with Deming regression analysis. Renin-angiotensin-aldosterone system hormones were evaluated at 0, 0.25, 0.5, 4, and 24 hours postadministration, via equilibrium analysis. Values were compared with a mixed effects model. Correlation between protease inhibition and equilibrium analysis was high for angiotensin I peptide (AngI) and angiotensin II peptide (AngII) (r = .92 and .95, respectively). Baseline RAAS peptide concentrations were below the limit of detection except AngII (median, 7.5 [range, 3.5-14.0] pmol/L). Furosemide administration resulted in an increase in AngI (8.0 [0.5-15.5] pmol/L, P = .03), AngII (33.7 [9.6-57.9] pmol/L, P = .0008), angiotensin III peptide (AngIII) (2.9 [0.9-4.9] pmol/L, P = .0005), angiotensin IV peptide (AngIV) (2.0 [0.6-3.4] pmol/L, P = .0005), and angiotensin 1-5 peptide (Ang1-5) (5.6 [1.2-5.9] pmol/L, P = .003) at 4 hours. Differences are reported as difference in the mean (95% confidence interval [CI]). Furosemide produced an increase in hormones associated with both the classical and alternative RAAS pathways. Serum equilibrium analysis is practical for RAAS analysis in horses.

5G Network Slicing as a Service Enabler for the Automotive Sector

ABSTRACTNetwork slicing, a key technology introduced in 5G standards, enables mobile networks to simultaneously support a wide range of heterogeneous use cases with diverse quality of service (QoS) requirements. This work discusses the potential benefits of network slicing for the automotive sector, encompassing manufacturing processes and vehicular communications. The review of the state of the art reveals a clear gap regarding the application of network slicing from the perspective of industrial verticals such as automotive use cases and their specific requirements. Departing from this observation, we first identify limitations of previous cellular technologies and open challenges for supporting the data services required. Then we describe network slicing as an enabler to face these challenges. We present an analysis of the cost equilibrium for network slicing to be effective for car manufacturers, and tests in real 5G networks that demonstrate the performance improvement in OTA updates coexisting with other services.

Mathematical Modeling of Dengue Disease Transmission Dynamics

Objectives: This study developed a compartmental ordinary differential equation model to investigate dengue transmission dynamics within a human population. The model stratified the population into susceptible, exposed, infected, and recovered classes, incorporating key epidemiological factors. Methods: Model equilibrium analysis was conducted to determine the stability of disease-free and endemic states. The basic reproduction number (R₀) was calculated to quantify the potential for disease spread. Additionally, sensitivity analysis was performed to assess the impact of key parameters on model outcomes. Findings: Results indicate that reducing mosquito biting rates and increasing human recovery rates are effective strategies for controlling dengue transmission. The model exhibits backward bifurcation, suggesting that even when R₀ is less than one, the disease can persist in the population under certain conditions. Novelty: This study presents a novel modeling framework that can inform the development of targeted prevention and management strategies for dengue. Keywords: Dengue, Mathematical Model, Ordinary differential equations, Basic reproduction number, Sensitivity analysis

Validating effectiveness of crown-of-thorns starfish control thresholds to limit coral loss throughout the Great Barrier Reef

AbstractPopulation irruptions of the Pacific crown-of-thorns starfish (CoTS, Acanthaster cf. solaris) are a key source of coral loss on Australia’s Great Barrier Reef (GBR). CoTS management currently involves their manual control (culling) to threshold densities below which net coral decline theoretically ceases based on analysis of a validated population dynamics model. Spatial variability in coral growth and community composition, and their predicted changes under continuing global warming, necessitate further consideration of current coral representation in CoTS models. Here, we consider the sensitivity of equilibrium coral-CoTS thresholds to coral growth rates and consider how the demographic composition of CoTS at a site may relate to culling thresholds. We found thresholds should be location-specific if the objective of CoTS control is coral recovery, but location-specific thresholds may not be needed if the objective is to limit coral cover loss based on coral growth and CoTS demography. The consequence of using a higher CPUE threshold than the analytical equilibrium coral-CoTS thresholds in terms of coral cover loss is suggested to be limited at coral cover < 40%, and varying control thresholds thereof may make little difference. Introducing a 0.06 CoTS.min−1 threshold for 40–60% coral cover may reduce coral loss at ~ 40% where it is likely greatest. With regional GBR coral cover averaging < 40%, this study validates the 0.04–0.08 CoTS.min−1 tiered threshold system for CoTS control and suggests methods developed from localised studies can be more broadly applicable and well-defined objectives (e.g. avoiding coral cover decline at a site) can help guide what thresholds are used and the sensitivity around these.

In Vivo Dynamics of HIV-1 Infection With Impaired Antibody Immunity and Three General Infection Mechanisms

In this paper we investigate two generalized human immunodeficiency virus type-1 (HIV-1) dynamics models with impaired antibody immunity. The models include both latently and actively infected cells. Three infection mechanisms are incorporated into the models, viral infection mechanism (VIM), latent cellular infection mechanism (CIM) and active CIM. The three infection rates are provided by generic nonlinear functions. The second model includes three types of distributed time delays. We find that our models are biologically feasible. The global stability analysis of equilibria are performed and found the basic reproduction ratio (R0) as a threshold parameter. Using Lyapunov method we show that, the virus-free equilibrium is globally asymptotically stable when R0≤1 and the virus-persistence equilibrium is globally asymptotically stable when R0>1. Sensitivity analysis on R0 is studied. To support our theoretical results we provide some numerical simulations. We have demonstrated that R0 is influenced by all three of the infection types, and that if one of them were ignored, R0 would be underestimated. This might lead to inadequate medication effectiveness that aims to remove HIV-1 from the body. The effects of time delay and impaired antibody immunity on HIV-1 progression are examined. According to our research, lowered immunity is a significant factor in the infection's growth. Furthermore, time delays might drastically reduce R0, which would prevent HIV-1 from replicating. The information provided by our research in this work can improve our comprehension of HIV-1 dynamics within-host and provide guidance for the creation of novel pharmacological treatments.

Imports and tourism expansion: A general equilibrium analysis

There is an ongoing debate within the literature about whether inbound tourism in developing countries contributes positively to national welfare. Most of the existing literature primarily relies on case studies and lacks theoretical frameworks essential for a comprehensive understanding of the role of imported intermediate inputs in tourism development. We aim to fill this gap by presenting a theoretical specific-factor general-equilibrium model of a tourism-exporting economy that incorporates both imported and non-traded intermediate goods. Our findings indicate that the extensive utilization of imported intermediate goods by the tourism industry, as well as other sectors, could potentially increase residents’ real income during a tourism boom. Additionally, our analysis reveals deviations from some standard results of the “beach disease” model. Lastly, we shed light on the complexity of the consequences of tourism expansion on income distribution, which prove to be more intricate than commonly believed. This underscores the need for a deeper understanding of the multifaceted dynamics involved in analyzing the connections between imports and tourism expansion.

Cytosine Methylation and Demethylation Model: Equilibrium Point and the Influence of Enzymes on Cytosine Forms Levels

Epigenetic changes, apart from changes in the DNA sequence, are one of the most important factors determining the fate of cells in living organisms. The main epigenetic change is cytosine methylation in relevant regions of DNA. Recently, we published an article in which we proposed a mathematical model of cytosine methylation and demethylation. In present work, we present an equilibrium analysis of this model. We present the conditions for its stability and aperiodic nature of the system’s free response. In particular, we focus on the influence of the levels of enzymes involved in cytosine methylation and demethylation on the equilibrium coordinates. The conclusions from this analysis are important in understanding the biological basis of the behavior of cells in living organisms.

Simulation of the Stackelberg–Hotelling Game

This work studies the Hotelling game with sequential choice of prices, that is, the Stackelberg–Hotelling (SHOT) game. The game is studied through numerical simulation, which provides the subgame perfect equilibrium solution not only in the unrestricted game but also in the game with reservation cost and with elastic demand. The simulation technique is tested first in the unconstrained game, where the analytical subgame perfect equilibrium solution was already known. Then, the numerical procedure is generalized to cope with the SHOT game with reservation cost and with elastic demand. These enriched formulations of the SHOT game have not been studied so far, so this article provides an exploratory study of them.

Sulfur fixation performance of calcium-bearing carbonates in iron ore roasting process: Thermodynamics, phase transition, microstructure evolution, and kinetics

Roasting technology is increasingly used in the beneficiation of refractory iron ores. During the roasting process, the presence of pyrite in some iron ores leads to the formation of SO2, requiring effective sulfur fixation techniques. This study proposed an innovative in-situ sulfur fixation method by pre-oxidation roasting, in which sulfur was fixed during the oxidation roasting process before reduction roasting. The effects of the main iron mineral (hematite), primary gangue mineral (quartz), and common calcium-containing carbonate minerals (calcite and dolomite) on sulfur migration during pyrite roasting were investigated, with particular emphasis on the sulfur fixation capabilities of calcite and dolomite. The study included thermodynamic equilibrium analysis, phase transitions and microstructural evolution in different reaction systems. The results showed that calcite and dolomite effectively reduced SO2 emissions by forming CaSO4 and MgSO4, with calcite exhibiting a stronger sulfur fixation capacity for the same mass. Kinetic analysis indicated that pyrite pyrolysis followed a two-step random nucleation and growth model. Furthermore, the addition of calcite increased the apparent activation energy of SO2 formation and altered the reaction pathway, providing insight into the sulfur fixation mechanism of calcite from a kinetic perspective.

Liquid Rocket Engine Performance Characterization Using Computational Modeling: Preliminary Analysis and Validation

The need to refuel future missions to Mars and the Moon via in situ resource utilization (ISRU) requires the development of LOX/LCH4 engines, which are complex and expensive to develop and improve. This paper discusses how the use of digital engineering—specifically physics-based modeling (PBM)—can aid in developing, testing, and validating a LOX/LCH4 engine. The model, which focuses on propulsion performance and heat transfer through the engine walls, was created using Siemens’ STAR-CCM+ CFD tool. Key features of the model include Eulerian multiphase physics (EMP), complex chemistry (CC) using the eddy dissipation concept (EDC), and segregated solid energy (SSE) for heat transfer. A comparison between the complete GRI 3.0 and Lu’s reduced combustion mechanisms was performed, with Lu’s mechanism being chosen for its cost-effectiveness and similar output to the GRI mechanism. The model’s geometry represents 1/8th of the engine’s volume, with a symmetric rotational boundary. The performance of this engine was investigated using NASA’s chemical equilibrium analysis (CEA) and STAR-CCM+ simulations, focusing on thrust levels of 125 lbf and 500 lbf. Discrepancies between theoretical predictions and simulations ranged from 1.4% to 28.5%, largely due to differences in modeling assumptions. While NASA CEA has a zero-dimensional, steady-state approach based on idealized conditions, STAR-CCM+ accounts for real-world factors such as multiphase flow, turbulence, and heat loss. For the 125 lbf case, a 9.2% deviation in combustion chamber temperature and a 15.0% difference in thrust were noted, with simulations yielding 113.48 lbf compared to the CEA’s 133.52 lbf. In the 500 lbf case, thrust reached 488 lbf, showing a 2.4% deviation from the design target and an 8.6% increase over CEA predictions. Temperature and pressure deviations were also observed, with the highest engine wall temperature at the nozzle throat. Monte Carlo simulations revealed that substituting LNG for LCH4 affects combustion dynamics. The findings emphasize the need for advanced modeling approaches to enhance the prediction accuracy of rocket engine performance, aiding in the development of digital twins for the CROME.

Trade and distribution in Guinea-Bissau: A computable general equilibrium analysis

Trade and distribution in Guinea-Bissau: A computable general equilibrium analysis

On the refined boundary condition at the edge of a thin elastic strip supported by a Winkler-type foundation under antiplane shear deformation

The derivation of the boundary conditions is the most challenging part of the asymptotic techniques underlying low-dimensional models for thin elastic structures. At the moment, these techniques do not take into consideration the effect of the environment, e.g., a Winkler foundation, when tackling boundary conditions, and have to be amended. In this paper as an example we consider an antiplane problem for a thin elastic strip contacting with a relatively compliant Winkler foundation. Refined boundary conditions at an edge loaded by prescribed stresses are established using a properly adjusted Saint-Venant’s principle. They appear to be useful for advanced structure modelling including analysis of the static equilibrium under self-equilibrated loading.

Extraction of mandelic acid with tri-octyl-phosphine oxide (TOPO) in different solvents: Equilibrium and neural network analysis

Mandelic acid is an important carboxylic acid used in pharmaceutical industries. It is also important to use it as a purified form. In this study, selective extraction of mandelic acid was done by tri-octyl-phosphine oxide (TOPO) diluted in different solvents such as methyl isobutyl ketone, 1-octanol, octyl acetate, dimethyl phthalate, 2-octanone, cyclohexane and toluene. The high selectivity of mandelic acid from aqueous solution was supported by thermodynamic parameters (loading factor, distribution coefficient, and extraction efficiency). The obtained values for each solvent were applied to the Neural Network Analysis to predict phase equilibrium behaviour in ternary systems. The results showed the highest mandelic acid extraction efficiency (93.65 %) and distribution coefficient (14.74) were attained with the organic phase mixture prepared with MIBK and TOPO. Also, it was found that extraction efficiencies increased with increasing TOPO amount in the medium for all studied solvents.

Design and stability performance optimization of a novel hybrid inspection robot walking device for smart grid applications

Inspecting in high-altitude windy environments requires maintaining a stable attitude to avoid significant oscillations, which is a crucial factor in advancing the use of hybrid power transmission line inspection robots (PTLIRs) in real-world scenarios for the electrical power and energy industry. We developed and optimized a novel walking device to improve the safety of hybrid PTLIRs operating in strong wind conditions. First, we investigate the operational conditions of transmission line inspection and design a walking device capable of transporting a flight device to be suspended under the line for inspection purposes. Second, a force equilibrium analysis is performed to explore the relationship between the key structural parameters of the walking device and the wind-induced deflection of the robot. A multiobjective optimization model is formulated to minimize the maximum deflection angle of the robot along three axes under wind loads. Finally, an optimization algorithm, using an improved non-dominated sorting particle swarm optimization (NSPSO) approach, is proposed to solve the model with good global search ability and fast convergence speed. A test platform is constructed to collect the wind deflection angle of a self-developed hybrid PTLIR under the transmission line. The test results demonstrate that the walking device can carry 30 kg to move along the transmission line. The average deflection angle of the robot around the Z axis is the highest under the influence of wind force level 7 (wind speed of 15.5 m/s) perpendicular to the windward surface of the robot. After optimization, the maximum deflection angle is limited to 10.38°, aligning within safety thresholds. The optimization algorithm effectively reduces the maximum deflection angles around the X, Z, and Y axes by 33.19 %, 39.21 %, and 13.23 %, with minimal average errors of 2.40 %, 3.87 %, and 2.13 %, respectively. The research in this paper can solve the bottleneck problem of robot practicality, which has important theoretical significance and practical application value for the safety, stability, and intelligent operation and maintenance management of power transmission lines.

A-043 A Fast, Novel and Analytically Sensitive Clinical Research Method for the Analysis of Free Testosterone using UPLC-MS/MS

Abstract Background The aim of this work was to develop an analytically sensitive, rapid clinical research method for the analysis of free testosterone in serum using a small sample volume. Laboratories have found this difficult, partly due to the inherent low concentrations (less than 3% of total testosterone is free), technical challenges and variability in results have been noted with equilibrium dialysis, which is considered the gold standard. Methods Testosterone certified reference material (Merck, UK) was used to create calibrators in 52.75 mM HEPES buffer adjusted to pH 7.4 to mimic the ionic environment of serum. Precision was evaluated using in-house QC materials prepared in serum (Golden West Biologicals, USA and BioIVT, UK). 200 µL serum was incubated at 37°C with 400 µL pH-adjusted 52.75 mM HEPES buffer for 2 hours, mixing at 800 r.p.m. with Rapid Equilibrium Analysis (RED) inserts and plates (Thermo Scientific™, UK). Testosterone-13C3 (Merck, UK) was spiked into resultant diasylate, then liquid-liquid extraction (LLE) was used to concentrate and clean the sample. The ACQUITY™ UPLC™ I-Class System with the Waters™ ACQUITY UPLC BEH C18, 1.7µm, 2.1 x 100 mm Column using a water/methanol/ammonium fluoride gradient and the Waters Xevo™ TQ Absolute Mass Spectrometer were used for quantification. An accelerated protocol for equilibrium dialysis, using a 2-hour incubation and fast mixing step was used (4 hours or longer is more typical historically) though it is essential to control the pH of the dialysis buffer and, particularly, the temperature of the chamber. Results No significant carryover or matrix effects were demonstrated with linearity from 0.5-650 pg/mL. Addition of high concentrations of endogenous substances (albumin, bilirubin, creatinine, cholesterol, triglycerides and uric acid) did not affect quantification. Analytical sensitivity investigations indicated the analytical sensitivity would allow precise quantification (≤20%CV and ≤15% bias) at 0.50 pg/mL. Coefficients of variation (CV) for total precision and repeatability on 5 analytical runs for low, mid and high QCs at approximately 2.79, 8.80 and 134 pg/mL respectively were all ≤ 8.4% (n=25). Accuracy was assessed by analyzing 45 male external quality assurance samples (NEQAS, UK) ranging in concentration from 50.1-268.6 pg/mL and the Bland-Altman agreement showed a small negative bias of -7.6% compared with the all-laboratory trimmed mean (ALTM), though excellent agreement overall. When LC-MS/MS determined concentrations were processed against Vermeulen equation determined concentrations (total testosterone and SHBG concentrations were provided by the scheme, a concentration of 45 g/L albumin was assumed), again good agreement was shown by the Bland-Altman bias of -7.7%. Conclusions A novel clinical research method using a fast equilibrium dialysis procedure with LLE and LC-MS/MS analysis with only 200 µL of serum has been demonstrated for clinical research use. Sub pg/mL analytical sensitivity, excellent linearity and precision, with minimal matrix effects and a strong agreement with an EQA scheme were established.

A Yebes W-band Line Survey towards an Unshocked Molecular Cloud of Supernova Remnant 3C 391: Evidence of Cosmic-Ray-Induced Chemistry

Cosmic rays (CRs) have strong influences on the chemistry of dense molecular clouds (MCs). To study the detailed chemistry induced by CRs, we conducted a Yebes W-band line survey towards an unshocked MC (which we named 3C391:NML) associated with supernova remnant 3C 391. We detected emission lines of 18 molecular species in total and estimated their column densities with local thermodynamic equilibrium (LTE) and non-LTE analysis. Using the abundance ratio N(HCO+)/N(CO) and an upper limit of N(DCO+)/N(HCO+), we estimated that the CR ionization rate of 3C391:NML is ζ ≳ 2.7 × 10−14 s−1 with an analytic method. However, we caution against adopting this value because chemical equilibrium, which is a prerequisite of using the equations, is not necessarily reached in 3C391:NML. We observed lower N(HCO+)/N(HOC+), higher N(HCS+)/N(CS), and higher X(l-C3H+) by an order of magnitude in 3C391:NML than the typical values in quiescent dense MCs. We found that an enhanced CR ionization rate (of order ∼10−15 or ∼10−14 s−1) is needed to reproduce the observation with a chemical model. This is higher than the values found in typical MCs by 2–3 orders of magnitude.

Employer-provided parking: Departure time choice, investment decision, and welfare effects

Employer-provided parking (EP) has become a prevalent way to reduce employees’ parking delays and late arrivals through offering them free or low-price parking spaces at the workplace. This paper explores the EP effects on employees’ trip scheduling, employer’s EP investment decision, and commercial parking operator’s pricing decision. An analytical trip scheduling equilibrium model is first presented to model the interaction between EP provision and employees’ departure time choices during morning commute. A profit maximization model incorporating the employee productivity is then developed to determine the employer’s optimal EP investment decision. A competitive game between employer’s investment decision and commercial parking operator’s parking pricing decision is analytically investigated, together with the effects of EP investment on social welfare. The results show that the EP investment can lead to a win-win situation with decreased employee commuting cost and increased firm production output; and the employer would like to provide only part of the employees with EP services. The competitive game solutions depend very much on the marginal costs of EP and commercial parking spaces. The EP investment with an excessively high commercial parking fee may hurt the society due to decreased social welfare.

Exact Second-Order Stiffness Matrix of Axial-Loaded Beam–Columns on Winkler Foundation

This paper establishes the exact second-order stiffness matrix of axial-loaded beam–columns on Winkler foundation. This Winkler foundation model has been widely used in engineering applications. The equilibrium analysis of an axial-loaded beam–column on Winkler foundation is conducted, and the element flexural deformations and forces are solved exactly from the governing differential equation. Two dimensionless factors for the axial force and foundation spring stiffness are defined, respectively. The exact second-order element stiffness matrix of the axial-loaded beam–column on Winkler foundation is then formulated, showing the relationship between the element-end deformations (translation and rotation angle) and the corresponding forces (shear force and bending moment). Such an exact second-order stiffness matrix may be used for the buckling and second-order solutions with allowance for the use of one element per member for the exact solution. The classical buckling problem of axial-loaded beam–columns on Winkler foundation with typical element-end boundary conditions is then analyzed by the developed matrix stiffness method. By comparing with classical buckling criterion expressions of axial-loaded beam–columns on Winkler foundation with various boundary conditions, it is demonstrated that the derived exact second-order stiffness matrix can be used to obtain the exact buckling solutions systematically.

Ethanol removal by stripping with CO2 reduced-size bubbles: Mechanical and thermodynamic entrainments

The efficiency of stripping processes for volatile compounds is governed by mechanical and thermodynamic entrainments, which play crucial roles in ethanol removal during the extractive fermentation process. These mechanisms depend on variables such as bubble diameter, ethanol concentration, liquid volume, pressure, and temperature. However, the quantification of each of them separately and their dependence on bubble diameter have never been addressed. The present study proposes a new methodology to evaluate both mechanical and thermodynamic entrainments, based on experimental data and thermodynamic equilibrium analysis of the bubbles in reactors with working volumes of 10.0 and 50 L, aiming to clarify the role that bubble diameter (microbubbles, fine and coarse bubbles) plays in these mechanisms. The results indicated that thermodynamic equilibrium was reached for any size of bubbles up to 5 mm in diameter, under a wide range of experimental conditions with specific gas flow rates from 0.22 to 10 vvm. Equally important, mechanical entrainment was found to enrich the gas phase in ethanol by a factor of 15, representing a higher concentration factor than for thermodynamic entrainment, which was inconceivable initially. This introduces a new and promising approach to intensify the stripping process of volatile compounds by means of mechanical entrainment.

An analysis of optimal equilibrium in the carbon trading market - From a tripartite evolutionary game perspective

As the climate crisis intensifies, achieving the global consensus of carbon peaking and carbon neutrality has become imperative. Carbon trading is an important financial measure to address the environmental crisis, and the realization of the dual‑carbon goals requires the cooperation and joint efforts of all parties involved in the carbon emissions trading market. This study constructs a dynamic evolutionary game model involving enterprises, government, and financial institutions while considering consumers' influence. By solving for equilibrium points and conducting numerical simulations, we explore optimal strategy choices for each stakeholder. Our findings reveal that the success of enterprise low-carbon transition is contingent upon market dynamics and requires active cooperation from government, financial institutions, and the public. Furthermore, factors such as financial market efficiency and internal governance capacity significantly impact enterprises' transformation decisions by influencing low-carbon transition costs. Public feedback indirectly affects enterprise decisions through its influence on financial institutions' provision of green services. Additionally, gradual reduction of carbon quotas by government entities facilitates progress toward low-carbon transformation objectives.