Comparative assessment of 4D CT-derived geometric and effective orifice areas in severe aortic stenosis.

Replication through cell division is one of the fundamental processes of life and a major driver of dynamics in systems ranging from bacterial colonies to embryogenesis, tissues and tumors. While regulation also shapes self-organization, many biologically relevant behaviors arise from a limited number of physical ingredients, and particle-based models have become a popular platform to investigate these emergent dynamics. However, incorporating division into such models often produces aberrant mechanical fluctuations that hinder meaningful analysis. Here, we introduce a minimal model ensuring mechanical consistency during cell division. Cells consist of two nodes, overlapping disks which separate during division, forming transient dumbbell shapes. Internal degrees of freedom, cell-cell interactions and equations of motion guarantee force continuity at all times, including during division, both for the dividing cell and its interaction partners, while allowing arbitrary anisotropic mobilities. As a benchmark, we also translate an established model of proliferating spherocylinders with similar dynamics into our theoretical framework. Numerical simulations demonstrate force continuity of the new disk cell model, quantify the improvements, and show agreement in terms of collective behaviors such as alignment and orientational order. We also demonstrate force extraction and a Voronoi-based interpretation in a confluent-tissue context-with a three-dimensional generalization in embryonic-like confinement. A reference implementation of the model in two and three dimensions is freely available as a Julia package based on InPartS.jl. Our model provides a framework for analyzing mechanical observables such as velocities and stresses, and can be readily extended with additional biological features.

ABSTRACT Detention ponds are a key component of urban flood control as they mitigate the additional runoff generated by land-cover changes and the associated reduction in time of concentration. Estimating the required reduction in peak discharge involves hydrological reservoir routing. This study proposes a novel simulation-driven routing methodology based on a modified Rosenbrock numerical scheme to solve the mass continuity equation coupled with the storage–outflow relationship. A key advantage of the proposed approach is its automatic time-step adjustment. Monte Carlo simulations are employed to generate multiple routing scenarios, which are subsequently used to train machine learning surrogate models. Among the evaluated ML algorithms, a Rational Quadratic Gaussian Process Regression model exhibited the best predictive performance. The methodology is demonstrated through a case study of a 17,340 m2 urban catchment. The proposed framework constitutes a practical decision-support tool for engineers and environmental agencies involved in the design and assessment of detention ponds.

Purpose This study investigates electrokinetically driven Bingham viscoplastic fluid flow and heat transfer over a rotating disk embedded in a porous medium under zeta-potential, electric-field and magnetic-field effects. The purpose of this paper is to clarify the coupled transport behavior and to establish the numerical reliability of the solution for this yield-stress flow problem. Design/methodology/approach The governing continuity, momentum, energy and electric-potential equations are reduced through similarity transformations to a coupled nonlinear system of ordinary differential equations. The resulting boundary-value problem is solved in MATLAB using the bvp4c collocation solver, and the numerical accuracy is assessed through residual, grid-refinement, convergence and validation analyses. Heat transfer and shear stress are also computed. A large data set is required for feed forward neural networks to learn Bingham fluid flow problem. The numerical solution obtained by bvp4c is considered to train the network as a ground truth data. A total of 495 data points are obtained as a numerical solution in the domain 0≤η≤10. To partition data set 396 samples are used as a training set (80%) and 99 samples as testing set (20%). Performance metric like MSE and values verify the accuracy and reliability of obtained solution. Findings The outcomes reveal that enhancing the zeta potential and electroosmotic parameter diminishes the radial velocity, while higher electric field parameter intensifies it. The Bingham response is more enhanced across the disk, whereas the skin friction is greater and yielded layer is observed preceding across the far field. An increase in the Eckert number raises the temperature field and reduces the heat-transfer rate (Nusselt number), while larger zeta potential lowers the skin-friction coefficient. The numerical solution exhibits second-order convergence with average errors of order 10−9 and good agreement with available benchmark results. Originality/value This study extends rotating-disk Bingham-flow analysis by incorporating electroosmotic forcing with zeta-potential and porous-medium effects within a convergence-validated framework. The results provide useful guidance for controlling viscoplastic flow, wall shear and thermal transport in electrochemical, biomedical and microfluidic systems.

Effects of propofol versus sevoflurane induction on echocardiographic parameters in patients with mitral stenosis: a randomized clinical trial.

Acoustic measurement methods and spatiotemporal distribution patterns of microbubble spectra in water under artificial aeration conditions.

Bile movement obstruction is a common severe disease in people. This study aims to find the effects of stenosis on the peristaltic transport of bile fluid within an inclined duct of permeable nature. This is a bile transport application through an inclined channel (duct) with calculus and stenosis. Bile flow is examined from a wave frame of reference that travels with the wave speed. In this investigation, equations for continuity and motion are developed for theoretical analysis, and the equations so formed are solved under the assumption of a less Reynolds number value, long wavelength, along with a non-dimensionalization process. The study examines the velocity profile, pressure gradient, and pressure rise, with a specific emphasis on the permeability parameter, amplitude ratio, gravity parameter, angle of inclination, and height of stenosis. The findings indicate that the velocity component of bile in the axial direction diminishes for the increasing permeability parameter and the height of the stenosis, with respect to axial distance.

Abstract We present a numerical implementation of the Friedmann equations to describe the expansion of the Universe within spatially flat, homogeneous and isotropic Friedmann–Lemaître–Robertson–Walker (FLRW) models. We adopt up-to-date cosmological parameters from the Planck 2018 mission for the concordance ΛCDM model, including the present-day density fractions of radiation, matter and dark energy, as well as the value of the Hubble constant. Starting from the Friedmann acceleration equation together with the continuity equation for a perfect fluid with barotropic equation of state p = wρ, we integrate the evolution of the scale factor a(t) using a symplectic Euler scheme (semi-implicit Störmer–Verlet method) implemented in Python. The code allows one to explore different constant values of the equation-of-state parameter w associated with distinct energy components (radiation, non-relativistic matter, a cosmological constant and more exotic fluids), and to analyse how these values modify the history and fate of cosmic expansion. We present graphical results for the baseline ΛCDM scenario and for a family of models with w ≠ −1, discussing their qualitative behaviour and their consistency with the standard cosmological paradigm. Finally, we highlight the potential of this implementation as a teaching tool in undergraduate and graduate cosmology courses, as well as its straightforward extension to more general models.

This study investigates the influence of key operating parameters of fill factor, rotor speed, and rotor wear on the power consumption of an isothermal intermeshing internal mixer. A three-dimensional computational fluid dynamics (CFD) model incorporating dynamic remeshing was developed using the finite volume method to solve the continuity and momentum equations for non-Newtonian rubber flow. The dynamic remeshing approach enabled accurate tracking of the moving rotor geometry and maintained mesh quality under varying operating conditions. The model integrates the actual mixer geometry and rheological properties of the rubber, and was validated against plant-scale power consumption data, showing good agreement. Simulations were performed across a range of operating conditions to quantify the effects of each parameter. Results indicate that increasing the fill factor from 50% to 82% raises normalized power from 14–19 kW/% to 17–22 kW/%, with higher levels producing extensive shear stress coverage to the rotor barrels but at the cost of potential clogging and reduced energy efficiency. Increasing rotor speed from 35 to 60 rpm increases normalized power from 20–22 kW/rpm to 22–23 kW/rpm, as higher rotor speeds intensify the local shear stress and strain rate fields near the rotor tips, thereby increasing power consumption. Rotor wear was found to significantly influence power consumption, with increasing wear leading to a progressive reduction in energy demand. The results indicate that worn rotor conditions reduce mechanical energy transfer due to diminished rotor–material interaction and increased clearances, resulting in lower shear stress generation within the mixing chamber. These findings identify operational windows that minimize energy costs while maintaining effective wall shear stress, offering practical guidance for optimizing mixer performance.

A recent discussion that highlighted the differences between the reported effective orifice area and corresponding incidence of prosthesis-patient mismatch within the 1- and 7-year results of the PERIcardial SurGical AOrtic Valve ReplacemeNt (PERIGON) Trial of the Avalus valve has once again emphasized the instability of such measurements. The effective orifice area, calculated using the continuity equation through measurements of the left ventricular outflow tract diameter, is highly susceptible to measurement variability, as previously demonstrated in literature through both intra- and interobserver variability. To illustrate this problem, a simulation was performed in which the left ventricular outflow tract diameter was systematically altered by -2 mm, -1 mm, 0 mm, +1 mm, and +2 mm. Subsequently, the proportion of severe prosthesis-patient mismatch was recalculated and varied between 13.3%, 6.2%, 3.1% (original), 1.2%, and 0.3%, respectively. These findings demonstrate that small but clinically realistic variability in left ventricular outflow tract measurements can significantly affect the presence of prosthesis-patient mismatch. A measurement variability of 1 mm can nearly double or halve the prevalence of severe prosthesis-patient mismatch. This illustrates that prosthesis-patient mismatch, in its current form, is highly unstable and that indexed effective orifice area-based prosthesis-patient mismatch should not be used in isolation.

This study investigates the inference of heat release fields from time-averaged and time-resolved particle image velocimetry data using physics-informed neural networks. The method assimilates density fields using a continuity equation, from which heat release fields are calculated a posteriori using an enthalpy equation. The methodology is applied to data of a laminar, premixed methane V-flame of 1.53 kW thermal power and an equivalence ratio of 0.73 that is forced acoustically in the unsteady cases. Validation for the steady case is provided by comparing the assimilated density fields to fields obtained from the particle image velocimetry seeding concentration and by comparing the inferred heat release distribution to Abel de-convoluted OH* chemiluminescence images. The identified unsteady heat release rate fields are validated against global heat release readings from an OH*-filtered photomultiplier tube. This validation data is also transferred into a flame transfer function. The results indicate that dynamics of laminar, premixed flames can be identified solely from velocity data and detailed insights can be gained without any measurement of the heat release rate.

On the well-posedness of (nonlinear) rough continuity equations

Reconstruction of the baryon acoustic oscillation (BAO) signal has been a standard procedure in BAO analyses over the past decade and has helped to improve the BAO parameter precision by a factor of ∼2 on average. The Dark Energy Spectroscopic Instrument (DESI) BAO analysis for the first year (DR1) data uses the “standard” reconstruction framework, in which the displacement field is estimated from the observed density field by solving the linearized continuity equation in redshift space, and galaxy and random positions are shifted in order to partially remove non-linearities.There are several approaches tosolving for the displacement field in real survey data,including the multigrid (MG), iterative Fast Fourier Transform (iFFT), and iterative Fast Fourier Transform particle (iFFTP) algorithms. In this work, we analyze these algorithms and compare them with various metrics including two-point statistics and the displacement itself using realistic DESI mocks. We focus on three representative DESI samples, the emission line galaxies (ELG), quasars (QSO), and the bright galaxy sample (BGS), which cover the extreme redshifts and number densities, and potential wide-angle effects. We conclude that the MG and iFFT algorithms agree within 0.4% in post-reconstruction power spectrum on BAO scales with the RecSym convention, which does not remove large-scale redshift space distortions (RSDs), in all three tracers. The RecSym convention appears to be less sensitive to displacement errors than the RecIso convention, which attempts to remove large-scale RSDs.However, iFFTP deviates from the first two; thus, we recommend against using iFFTP without further development. In addition, we provide the optimal settings for reconstruction for five years of DESI observation.The analyses presented in this work pave the way for DESI DR1 analysis as well as future BAO analyses.

Counter-current flow in channels separated by a membrane has been studied by several scientists and researchers. The current study aims to analytically simulate and describe the distribution of pressure, volumetric flow rate, and velocity in square channels separated by a membrane. Consequently, the study was conducted using one-dimensional (1D) analytical solutions to achieve several objectives: avoiding the execution of experimental tests, reducing the effort required for expensive and time-consuming module design, and enabling easy observation of variations in pressure, volumetric flow rate, and velocity. The 1D analytical solution directly simulates flow in square channels separated by a membrane by solving the continuity equation and Darcy’s law, through which pressure, volumetric flow rate, and velocity are calculated. Experimental results were used to validate the 1D analytical solutions. The results of the current study indicate that pressure decreases from the inlet to the outlet of the channel, while the horizontal velocity decreases from the inlet to the midpoint of the channel length and then increases toward the outlet. The 1D analytical solutions show acceptable accuracy when compared with experimental results. Consequently, these solutions can be used to explore and illustrate the distributions of pressure, volumetric flow rate, and velocity in square channels separated by a membrane, enabling the evaluation of hemodialysis prototype module performance and efficiency prior to fabrication.

In this work, the numerical investigation of mixed convection heat transfer and flow structures around four trapezoid obstacle geometries in a duct was carried out using TiO 2 -pure water nanofluid and pure water. Geometries have a constant heat flux, and they were placed opposed each other on the parallel plates forming the duct, two on the left side and two on the right side. The numerical investigation was performed by solving the continuity, momentum, and energy equations in a steady, laminar, and two-dimensional flow using the academic Ansys-Fluent software. To direct the flow to the warmed trapezoid obstacle elements, flow director fins were placed on the upper inlet surfaces of the duct at angles of 30 o and 60 o . Except for the obstacle elements, all surfaces of the duct and the fins are adiabatic. The results of the work were compared with those from experimental and numerical studies in the literature. It was found that in the case of using TiO 2 -pure water nanofluid in the 60 o fin angle duct at Ri* = 200 and Re = 200, the Nu m number of the object on the upper left side is 8.22% higher than the one on the lower left side. In addition, it was found that the performance evaluation criterion number value achieved in the 60 o fin angle for Re = 200 and Ri* = 50 was 9.98% and 6.55% higher than that in the Re = 200 and Ri* = 200 when nanofluid and pure water were used, respectively.

This study presents a unified mechanics-based framework for evaluating bonded composite patch repairs. Discrete fracture, fatigue, and adhesive responses are transformed into continuous master equations over the design space. Low-order polynomial surfaces model stress intensity and concentration responses, enabling continuous prediction of repair performance without repeated finite-element analyses. A fracture-based repair efficiency index is derived from the analytical master surface. This index quantifies the average reduction in crack-driving force across the domain. Combined with adhesive stiffness and strength, it defines an adhesive-based repair efficiency index (A-REI), providing a direct link between structural response and material properties. The results show that repair effectiveness is strongly influenced by both geometric severity and adhesive properties. Fatigue performance decreases significantly with increasing notch ratio in single-sided repairs. Double-sided configurations maintain consistently higher efficiency. Symmetric reinforcement more effectively reduces stress concentration, with improvements exceeding 40% at intermediate notch ratios. Adhesive selection is governed by stiffness and strength. Structural adhesives achieve significantly higher A-REI values, whereas compliant adhesives contribute negligibly. Overall, repair symmetry controls the magnitude of improvement, while adhesive properties determine performance ranking. This framework provides a clear, practical basis for design and material selection.

U-bend geometries are commonly used flow restrictions in nuclear reactor systems. Two-phase flows through U-bends are quite different from those in straight pipes, yet systematic modeling of inverted U-bend effects is lacking. A separate-effects air-water two-phase flow test facility has been used to study the two-phase flow transport from vertical upward to vertical downward across a vertical U-bend (25.4-mm inner diameter; curvature-to-diameter ratio = 9). Detailed data, including void fraction, gas velocity, bubble diameter, and pressure loss, were obtained. Using the obtained experimental data, models and correlations were developed to characterize the U-bend effects, which include models and correlations for variance of void fraction σ 2, U-bend dissipation length, bubble velocity, and pressure loss. The U-bend strength can be represented by the variance of the void fraction, which dissipates exponentially in the U-bend dissipation region. The dissipation lengths of U-bend effects under different test conditions are determined by the dissipation rate β . The bubble velocity correlations are related to the development of σ 2. The Lockhart-Martinelli’two-phase flow frictional loss correlation can be used to predict the experimental two-phase pressure drop across the U-bend with some modifications. Experimental data also suggest a strong correlation between σ 2 and bubble interaction covariance terms (covariance of random collision, CO V RC ) in the U-bend and U-bend dissipation region. A modified Froude number, F r m , derived from the two-fluid model momentum equation is used as a fundamental parameter in developing the correlations for σ 2, β , U-bend dissipation length, bubble velocity, and CO V RC . To model the void fractions in the interfacial area transport equation across the U-bend, a continuity equation was used, while conventional drift-flux models were used in the straight pipe sections. Model coefficients of different bubble interaction terms were determined by evaluating each region (i.e. vertical upward, U-bend, U-bend dissipation, vertical downward) using experimental data individually. The one-group interfacial area transport from vertical upward to vertical downward two-phase flow across a vertical U-bend is then evaluated using all the above developed models and correlations. The evaluation shows that the models predict a i development effectively, with deviations generally within ±15%.

Three-dimensional evaluation of operating conditions and channel design in a wall-coated microreactor for dry reforming of methane

A longitudinal analysis of bidirectional relationships between executive functioning and peripheral inflammation in schizophrenia.

Solution space characterisation of perturbed linear discrete and continuous stochastic Volterra convolution equations: the ℓ and L cases