Stratification Parameter Research Articles

The role of [68Ga]Ga-PSMA PET/CT in primary staging of newly diagnosed prostate cancer: predictive value of PET-derived parameters for risk stratification through machine learning

The role of [68Ga]Ga-PSMA PET/CT in primary staging of newly diagnosed prostate cancer: predictive value of PET-derived parameters for risk stratification through machine learning

Assessment of right ventricular ejection fraction cut-point for predicting mortality and heart failure hospitalization in asian patients with heart failure and reduced ejection fraction (HFrEF)

Abstract Background Left ventricular ejection fraction (LVEF) has been well established as a predictor of morbidity and mortality in heart failure patients (HF). Meta-analyses have confirmed that right ventricular systolic dysfunction (RVSD) identified by cardiac MR predicts adverse outcomes in HF patients. However, the cut-point and predictive value of right ventricular ejection fraction (RVEF) in Asian patients remain unknown. Objectives To evaluate the RVEF cut-point for RVSD and demonstrate the association between RVSD by cardiac MR and a composite endpoint consisting of HF hospitalisation and/or all-cause mortality in HFrEF patients (LVEF ≤40%). Materials & Methods A retrospective chart review of 370 consecutive HFrEF patients who underwent cardiac MR between 01 June 2009 and 31 December 2013 was done. The primary outcome was defined as all-cause mortality and/or HF hospitalisation. Receiver Operating Characteristic (ROC) analysis was done to explore the most accurate RVEF as a cut-point for RVSD. Multivariate Cox regression analysis was calculated. Results Patients were followed for a total of 1,989 patient-years with an average of 5.4 ± 2.9 years. The primary outcome occurred in 112 patients (30.3%). ROC analysis demonstrated that RVEF <48% provided the most accurate prognostic value (specificity 52%, sensitivity 70%) with an area under the curve of 0.62 (95% CI 0.55 – 0.69). Multivariate Cox analysis showed that RVSD was a significant independent risk factor (hazard ratio 1.71; 95% CI 1.10 – 2.66; p=0.018) for the primary outcome, in addition to age (p<0.001), New York Heart Association functional class (p<0.001), and diabetes mellitus (p=0.014), regardless of LVEF. Conclusions In Asian HFrEF patients, RVSD defined by RVEF <48% by cardiac MR can predict adverse events and provide a prognostic parameter for risk stratification.

Biomarkers in early and late period after radiofrequency and pulsed field catheter ablation of atrial fibrillation

Abstract Introduction Biomarkers are routinely used parameters for disease diagnosis, treatment control and risk stratification. In connection with atrial fibrillation (AF), the importance of GDF-15 (growth differentiation factor 15), NT-proBNP (N-terminal fragment brain natriuretic factor) and hs-TnT (high sensitivity cardiac troponin T) is discussed. Catheter ablation is an established treatment method in selected population with AF. However, biomarker response to radiofrequency catheter ablation (RFCA) and pulsed field ablation (PFA) of AF has not been precisely described. Purpose Purpose of the study was to describe early and late dynamics of GDF-15, hs-TnT and NT-proBNP in different ablation technologies. Methods We prospectively enrolled 48 patients (median (IQR) age 62 (55; 70) years, 30 males) undergoing RFCA, which we compared with 30 patients (median (IQR) age 64 (56; 71) years, 18 males) undergoing PFA. All patients underwent 6 sequential blood takes: before ablation (baseline), right after ablation (0h), 24 and 48 hours after procedure (24h and 48h), 90 and 180 days after procedure. Levels of GDF-15, hs-TnT and NT-proBNP were analyzed. Results Out of all patients, 19 (40 %) and 20 (67 %) patients had paroxysmal AF in RFCA and PFA group, respectively. Additional ablation lesions over pulmonary vein isolation were done in 26 (54 %) patients in RFCA group and 11 (43 %) patients in PFA group. Median procedural time was significantly longer in RFCA than in PFA group (155 (130; 190) vs. 80 (70; 90) min; p < 0.01). Early dynamics of GDF-15 and cardiac hs-TnT are visualised in Figure 1 and 2. GDF-15 level peak was registered 48 hours after ablation with median (IQR) 1183 (824; 1988) ng/l. Compared to baseline, GDF-15 values sustained elevated up to 90 days after ablation in both groups and decreased to baseline levels after 180 days. No significant differences were found in GDF-15 levels between patients treated with RFCA and PFA. Maximal values of hs-TnT were significantly higher in PFA group than in RFCA group (1001±589 vs. 458±202 ng/l; p < 0.001). We have recognised decrease of NT-proBNP between baseline and 90 days after procedure in both groups: 338 (112; 613) vs. 209 (101; 545) ng/l; p < 0.05. Conclusion Eventhough GDF-15 is considered as a nonspecific biomarker reflecting general condition of patient, the levels are significantly affected by catheter ablation of AF for several months irrespective to ablation technology. PFA is associated with advanced elevation of hs-TnT.Dynamics of GDF-15 (median; IQR)Dynamics of hs-TnT (median; IQR)

Numerical exploration of micropolar fluid stratified flow over curved stretching sheet under buoyancy effect

AbstractThis article focuses on the effect of buoyancy on the bioconvective micropolar fluid flow over a curved stretching surface under the slip boundary condition. Mass and heat transfer analysis has been analysed using double stratification, linear heat source, chemical reaction and Joule dissipation. The calculation of entropy formation in a fluid flow is also illustrated. Using similarity transformations, the system of partial differential equations is transformed into a set of ordinary differential equations through reduction in the flow equations and then solved using the numerical methodology of the Runge‐Kutta‐Fehlberg 4th‐5th order method. The mathematical data obtained for velocity, temperature, concentration, and bio‐convection profiles with different parameters are presented on graphs. The velocity profile exhibits consistent behaviour near the buoyancy parameter, with a decrease at the boundary followed by an increase. Notably, the velocity profile experiences a decrease under first‐order slip conditions but grows when subjected to second‐order slip. Micro‐rotation intensifies as the material parameter increases. Conversely, temperature and concentration has declined as the stratification parameter rises. Additionally, the concentration of motile microorganisms reduces with increasing Lewis number and Peclet number. As the material parameter rises, entropy decreases while the Bejan number increases.

Unveiling Immunological and Hematological Markers in COVID-19: Insights from a Clinical Study.

The COVID-19 pandemic has affected the global health system and economies largely. Therefore, knowledge about the clinical and laboratory profiles of patients with COVID-19 would help in the management and prognosis of the disease. The immunological and hematological indices have emerged as critical determinants for the severity of the disease and the prognosis; however, association with COVID-19 is clouded. The present study is aimed to characterize the immunological and hematological profiles of patients with COVID-19 in correlation with the disease severity. The study included 1,019 polymerase chain reaction (PCR)-confirmed patients with COVID-19 who were classified into serious and nonserious groups, considering severity criteria. Clinical laboratory investigations included hematological, biochemical, and immunological parameters regarding leukocyte counts, hemoglobin levels, and inflammatory markers. Our analysis of immunological and hematological differences between serious and nonserious patients with COVID-19 indicates that serious cases reflected elevated levels of pro-inflammatory markers such as lactate dehydrogenase, C-reactive protein (CRP), D-dimer, and ferritin, representing immune system dysregulation and systemic inflammation. Furthermore, in serious cases, discrepancies had also been noticed for many hematological parameters than nonserious ones, which also contained leukocyte count and hemoglobin level. Additionally, the CRP, D-dimer, blood urea nitrogen, alanine transaminase, and albumin levels could be independent predictors of COVID-19 severity by multivariate logistic regression analysis. Cutoff values for these biomarkers were defined by receiver operating characteristic curve analysis defining optimal parameters for the risk stratification and prognostication. The current investigation provides a comprehensive understanding of immunological and hematological correlation with COVID-19 severity, refining clinical decision-making and therapeutic interventions to improve patient outcomes.

Unsteady MHD flow past an oscillating vertical plate with periodic temperature variation and exponential mass diffusion embedded in a porous medium with thermal and mass stratification effects

AbstractThe present study investigates the impacts of both mass and thermal stratification on unsteady magnetohydrodynamic flow past a plate swinging vertically on its own axis while entangled in a porous medium with periodic temperature variation and exponential mass diffusion. The technique of Laplace transform for the unitary Prandtl and Schmidt numbers is employed to obtain the closed‐form solution for the nondimensional system of partial differential equations that govern the system for velocity, temperature, and concentration fields. For various physical factors, such as stratification parameters, phase angle, thermal Grashof number, Darcy number, mass Grashof number, and time on velocity, temperature, concentration, skin‐friction, plate heat flux, and mass flux, numerical computations have been performed, and illustrated in graphs. It has been observed that the steady state is attained more swiftly when stratification is applied to the flow. The desire to enhance the knowledge of fluid flow in many technological as well as environmental circumstances, where such conditions are widely used could be the driving force behind this research. Significant results from the thermal and mass stratification are contrasted with the environment where stratification is absent. Understanding flow mechanisms in both naturally occurring and artificially created environments can be enriched by this innovative method.

Significance of tri‐hybrid nanoparticles on the dynamics of Ellis rotating nanofluid with thermal stratification

AbstractThe fluids flow containing nano size particles is essential in industrial applications, especially in nuclear cooling system and nuclear reactor to increase the energy performance. In connection to this, a trihybrid Ellis rotating nanofluid flow through a stretching surface for increasing the heat transportation is presented. By suspending three different types of nano size particles the trihybrid nanofluid is formed with distinct chemical and physical connection into base liquid. In this article, the nano size particles , and are mixed in (water). This type of mixture helps in degradation of noxious substances, cleaning environmental and many other appliances that requires the cooling effect. In addition, the linear thermal radiation is also considered. The governing equations of the flow and fluid temperature are minimized to ordinary differential equations and these equations are solved by Runge Kutta order fourth (RK45) approach. The approximate results are analyzed via graphs and the results reveal that thermal conductivity of trihybrid nano type fluid is more valuable as compared to hybrid and single nanofluid. Higher values of magnetic and rotational parameter have aggrandized the fluid temperature and opposite trend has observed for Ellis and thermal stratification parameter. Moreover, the results are compared with previous literature and found an excellent agreement.

New Biomarkers to Define A Biological Borderline Situation for Pancreatic Adenocarcinoma - Results of An Ancillary Study of the PANACHE01-PRODIGE48 Trial.

To investigate in patients treated for a resectable pancreatic ductal adenocarcinoma (PA), the prognostic value of baseline CA19-9 and circulating tumour DNA (ctDNA) for overall survival (OS), to improve death risk stratification, based on a planned ancillary study from PANACHE01-PRODIGE 48 trial. Biological borderline situation that was first used by the MD Anderson, became a standard practice following the international consensus conference in 2016 to manage PA. Regarding the risk of systemic disease especially in the setting of "markedly elevated" CA19-9, neoadjuvant therapy is advised to avoid unnecessary surgery, with risk of early recurrence. To best define biological borderline situations, new biomarkers are needed. Characteristics at diagnosis and OS were compared between patients with or without ctDNA status available. OS was estimated with Kaplan Meier method and compared with log-rank test. Restricted cubic spline approach was used to identify optimal threshold for biological parameters for death risk stratification. Univariate and multivariate Cox proportional hazard models were estimated to assess the association of ctDNA status and other parameters with OS. Among the 132 patients from the primary population for analysis in the PANACHE01 -PRODIGE 48 trial, 92(71%) were available for ctDNA status at diagnosis. No selection bias was identified between patients with or without ctDNA status. 14 patients (15%) were ctDNA+ and exhibited a higher risk for death (P=0,0188; HR95% CI: 2.28 (1.12-4.63). In the 92 patients with ctDNA status available among the others parameter analysed only CA19-9 was statically associated with OS in univariate analysis. Patients with log of CA19-9 equal or superior to 4.4 that corresponds to a CA19-9 of 80 UI/mL were identified at higher risk for death (P=0,0143; HR95% CI: 2.2 (1.15-4.19). In multivariate analysis CA19-19 remained independently associated with OS (p-value=0.0323). When combining the two biomarkers, median OS was of 19.4 (IC 95% 3.8-Not reached) months, 30.2 (IC 95% 17.1-NR) months and not reached (IC 95% 39.3-NR) for "CA19-9 high and ctDNA+ group", "CA19-9 high or ctDNA+ group", and "CA19-9 low and ctDNA- group", respectively (logrank P=0,0069). Progress in the management of potentially operable PA remains limited, relying solely on strategies to optimize the sequence of complete treatment, based on modern multidrug chemotherapy (FOLFIRINOX, GemNabPaclitaxel) and surgical resection. The identification of risk criteria, such as the existence of systemic disease, is an important issue, currently referred to as "biologic borderline disease". Few data, particularly from prospective studies, allow us to identify biomarkers other than CA19-9. Combining ctDNA to CA19-9 could be of interest to best define biological borderline situations in PA.

Bioconvective three-dimensional flow of Sutterby nanoliquid due to moving plate with activation energy applications

Owing to enhanced features of nanomaterials, various applications of such materials have been suggested in the thermal systems, heat exchanges, electronic cooling systems, coolant processes, energy production etc. Following to such motivated applications, the objective of current analysis is to presents the bioconvective double stratification flow of Sutterby nanofluid due to bidirectional moving surface. The thermal interpretation of problem is subject to utilization of radiative effects, activation energy and heat source. The observations for heat, mass and microorganism's assessment are performed by using the convective boundary conditions. Shooting numerical simulations are performed for modeled problem. It is noticed that heat transfer enhances due to thermal stratification parameter. An increment in mass transfer is subject to larger values of mass stratification Biot number. The claimed results offer significance in controlling the heating and cooling processes, thermal devices, energy generation, manufacturing developments, solar systems etc.

Impacts of thermally stratified medium on transient convective heat transfer between co‐axial horizontal fixed pipes: Applications of the thermal stratification

AbstractThermal stratification improves coaxial pipe systems’ efficiency and stability. Thermal stratification enables accurate temperature maintenance, reduces thermal stress, optimizes heat transmission performance, and minimizes usage of energy to guarantee the system's long‐term performance. The main aim of the current study is to investigate the impacts of thermal stratification on buoyancy force flow and thermal transmission between coaxial fixed pipes. In the present research, the applications of thermally stratified medium on transient convective heat transfer between two coaxial fixed pipes are studied. A two‐dimensional mathematical formulation in terms of mutually nonlinear partial differential equations is used to analyze the unsteady flow and temperature field between the co‐axial pipes, when the internal pipe is uniformly heated and the outer wall of the external pipe is placed at infinity from the surface of the inner fixed pipe. Flow is assumed along the axial direction of the internal pipe and stationary boundary condition is assumed at the surface of the inner pipe. The coupled equations of the simulated model are solved numerically by applying the Implicit Finite Difference Technique. The computed outcomes in the form of geometrical interpretation are highlighted by using the technically advanced software TECHPLOT‐360. Comprehensive detail of the obtained results for the non‐dimensional parameters included in the flow formulation is predicted for steady state velocity, temperature distribution, time‐dependent surface shearness and time‐dependent energy shearness in results and discussion section of the manuscript. The emphasis is placed on the thermal stratification parameter in the above mentioned chief quantities. From the obtained results, it is predicted that the fluid flow pattern and thermal distribution are both reduced for rising values of the thermal stratification parameter S = 0.001, 0.03, 0.05, and 0.07. Minimum flow and thermal profile are observed at S = 0.07. Further, the amplitude of the time‐dependent surface shearness is uniformly distributed throughout the medium and the amplitude of the time‐dependent energy shearness is reduced effectively for S = 1.0, 5.0, and 10.0.

Internal Tides at the Coast: Energy Flux of Baroclinic Tides Propagating into the Deep Ocean in the Presence of Supercritical Shelf Topography

Abstract The generation of internal tides at coastal margins is an important mechanism for the loss of energy from the barotropic tide. Although some previous studies attempted to quantify energy loss from the barotropic tides into the deep ocean, global estimates are complicated by the coastal geometry and spatially and temporally variable stratification. Here, we explore the effects of supercritical, finite amplitude bottom topography, which is difficult to solve analytically. We conduct a suite of 2D linear numerical simulations of the barotropic tide interacting with a uniform alongshore coastal shelf, representing the tidal forcing by a body force derived from the vertical displacement of the isopycnals by the gravest coastal trapped wave (of which a Kelvin wave is a close approximation). We explore the effects of latitude, topographic parameters, and nonuniform stratification on the baroclinic tidal energy flux propagating into the deep ocean away from the shelf. By varying the pycnocline depth and thickness, we extend previous studies of shallow and infinitesimally thin pycnoclines to include deep permanent pycnoclines. We find that scaling laws previously derived in terms of continental shelf width and depth for shallow and thin pycnoclines generally hold for the deeper and thicker pycnoclines considered in this study. We also find that baroclinic tidal energy flux is more sensitive to topographic than stratification parameters. Interestingly, we find that the slope of the shelf itself is an important parameter but not the width of the continental slope in the case of these steep topographies. Significance Statement The objective of this study is to better understand how vertical density stratification, which can vary seasonally in the ocean, affects the interaction of tides with steep coastal topography and the generation of waves that travel away from the coast in the ocean interior. These waves in the interior can travel over long distances, carrying energy offshore into the deep ocean. Our results suggest that the amount of energy in these internal waves is more sensitive to changes in topography and latitude than to the vertical density profile. The scaling laws found in this study suggest which parameters are important for calculating global estimates of the energy lost from the tide to the ocean interior at the coastal margins.

Numerical heat transfer analysis of bio convective flow of non-Newtonian nanofluid with Darcy-Forchheimer effect over a curved stretching surface

The main aim of this study is to investigate the behavior of bio-convective flow of 2nd grade micropolar nanofluid with Darcy-Forchheimer law over a curved porous stretching surface. The fluid flow analysis includes novel aspects such as the nonuniform heat source/sink, Joule heating, magnetic field, chemical reaction, and thermal radiation. Furthermore, the boundary of the stretching surface is acquired the stratification conditions. A suitable conversion method is employed to transform the flow model into a collection of ordinary differential equations, characterized by their nonlinearity. The bvp4c technique on the MATLAB is utilized to acquire numerical solutions for this set of nonlinear equations. The characteristics of various influential parameters on the velocity, temperature, concentration, and microorganism density profiles are observed and discussed. In the present problem, it is observed that by the growth of micropolar parameter enhances the angular fluid velocity. Moreover, larger values of the magnetic parameter, Darcy number, and porosity parameter result in a decrease in the fluid’s linear velocity. The temperature profile exhibits a decreasing pattern with the elevation thermal stratification parameter, while the opposite trend shows by the increment of the radiation parameter and Eckert number. Additionally, the concentration of nanoparticles decreases as the Schmidt number and Brownian motion parameter increases.

Assessment of prognostic factors in pediatric adrenocortical tumors: the modified pediatric S-GRAS score in an international multicenter cohort-a work from the ENSAT-PACT working group.

Pediatric adrenocortical carcinoma (pACC) is rare, and prognostic stratification remains challenging. We aimed to confirm the prognostic value of the previously published pediatric scoring system (pS-GRAS) in an international multicenter cohort. Analysis of pS-GRAS items of pACC from 6 countries in collaboration of ENSAT-PACT, GPOH-MET, and IC-PACT. We received patient data of the pS-GRAS items including survival information from 9 centers. PS-GRAS score was calculated as a sum of tumor stage (1 = 0; 2-3 = 1; 4 = 2 points), grade (Ki67 index: 0%-9% = 0; 10%-19% = 1; ≥20% = 2 points), resection status (R0 = 0; RX/R1/R2 = 1 point), age (<4 years = 0; ≥4 years = 1 point), and hormone production (androgen production = 0; glucocorticoid-/mixed-/no-hormone production = 1 point) generating 8 scores and 4 groups (1: 0-2, 2: 3-4, 3: 5, 4: 6-7). Primary endpoint was overall survival (OS). We included 268 patients with median age of 4 years. The analysis of the pS-GRAS score showed a significantly favorable prognosis in patients with a lower scoring compared to higher scoring groups (5-year OS: Group 1 98%; group 2 87% [hazard ratio {HR} of death 3.6, 95% CI of HR 1.6-8.2]; group 3 43% [HR of death 2.8, 95% CI 1.9-4.4]; group 4: OS 18% [HR of death 2.1, 95% CI 1.7-2.7]). In the multivariable analysis, age (HR of death 3.5, 95% CI 1.8-7.0), resection status (HR of death 5.5, 95% CI 2.7-11.1), tumor stage (HR of death 1.9, 95% CI of HR 1.2-3.0), and Ki67 index (HR of death 1.7, 95% CI 1.2-2.4) remained strong independent outcome predictors. Especially infants < 4 years showed more often low-risk constellations with a better OS for all tumor stages. In an international multicenter study, we confirmed that the pS-GRAS score is strongly associated with overall survival among patients with pACC. Age, resection status, stage, and Ki67 index are important parameters for risk stratification.

Stratification characteristics of hydrogen-blended natural gas for gas risers inside residential users

ABSTRACT In this paper, a CFD model is developed to examine the stratification characteristics of hydrogen-blended natural gas in residential gas risers. Meanwhile, the accuracy of the CFD model is validated by field experiments. The effects of relevant parameters on stratification are analyzed, including hydrogen blending ratio, riser internal diameter, riser height, media temperature, and media pressure. The relative importance of relevant parameters for stratification is identified using the orthogonal experiment design and improved grey relational analysis. Furthermore, a device is designed to mitigate the impact of blended gas stratification. The results show that the stratification of hydrogen-blended natural gas inside residential gas risers is significant in the direction of gravity. The maximum stratification height in standing for 8 h can reach up to 17.4 cm. The stratification height presents a negative correlation with riser internal diameter, riser height, and media temperature, while that represents a positive correlation with hydrogen blending ratio and media pressure. Furthermore, the effects of these parameters on stratification height could be ranked as follows: media pressure > hydrogen blending ratio > riser internal diameter > riser height > media temperature. These achievements provide effective guidance for residential users on safely using hydrogen-blended natural gas.

Stratified numerical heat and mass transport mechanism in MHD Maxwell fluid flow with nonuniform heat source/sink

The present boundary layer flow of Maxwell fluid over a stretching sheet has good number of practical applications in metallurgy, drawing of plastics, polymer sheet extrusion including hot rolling extrusion, glass blowing, spinning of fibers, rubber and plastic sheets, crystal growing and many more. Due to these extensive applications of Maxwell fluid in engineering, medicine and manufacturing industries including the above-mentioned applications, authors have motived, inspired and investigated the present problem. However, in this research paper, the influences of Soret and Dufour effects on the steady-state Maxwell fluid flow past a stretching sheet with nonuniform heat source/sink are considered numerically. The thermal and concentration stratifications impacts are also incorporated. The viscous dissipation and magnetic field effects are also included in the respective governing equations. The main novelty and uniqueness of this numerical research is to generalize the earlier studies and describe the salient features of magneto-thermo visco-elastic dissipative Maxwell fluid motion about a stretching sheet with cross-diffusion effects under the influence of double stratification phenomena. To differentiate the non-Newtonian fluids from those of Newtonian fluids, a well-known Maxwell fluid flow model is used in the present study. The investigated physical problem results the highly nonlinear coupled partial differential equations (PDEs) and which are not amenable to any of the direct methods. Suitable similarity transformations are deployed to reduce the highly complex PDEs into the system of ordinary differential equations (ODEs). A robust BVP4C Matlab function is employed to solve the rendered dimensionless system of ODEs. The numerically generated computed data is plotted in terms of velocity, temperature and concentration profiles including engineering quantities of interest such as skin-friction, Nusselt and Sherwood numbers in the flow region. It is evident from the current analysis that, the amplified magnetic field decreases the velocity field and increases the thermal and concentration distribution fields. Accelerating Maxwell’s number diminished the flow velocity and increased the temperature field. Increasing Soret and Dufour numbers enhances the concentration and temperature fields, respectively. Amplifying Maxwell’s number raises the skin-friction coefficient and enlarging the thermal stratification parameter magnifies the thermal transport rate. The mass transport rate amplified with a raise in concentration stratification number in the flow region. Finally, it is provided that, the current results are excellently matching with earlier published results in the literature and it confirms the accuracy of the used numerical method and the produced similarity solutions.

Computational analysis magnetohydrodynamics natural convection flow round vertical thermally stratified jet: Finite difference method in conjunction with primitive variable formulation

The problem of magnetohydrodynamic free convective heat transfer mechanism across a laminar, round, vertical, and thermally stratified jet is examined. The boundary layer equations are non-dimensionalized, and then, using the primitive variable formulation, the finite difference method is used to find the numerical solution of the problem. The impact of Prandtl number, magnetic parameter, and stratification parameter on velocity distribution, temperature profile, and heat transfer rate is explained graphically and in tabular form. It is found that for increasing values of thermal stratification parameter S, the velocity profile increases while temperature distribution and rate of heat transfer decrease. Similarly, with an increase in the values of Prandtl number, velocity, and temperature distribution decrease, but the rate of heat transfer increases.

Artificial neural computing and statistical analysis of heat and mass transport of nanofluid flow with melting heat and thermal stratification

The melting heat phenomenon in viscous nanofluid MHD flow over a stretching sheet with variable porosity and permeability was utilized. The behavior of magneto-viscous nanofluid flow was scrutinized using the concepts of machine learning and statistics. Thermal stratification, heat source, and activation energy in the solution of tween-20 nanoparticles and an ethyl-acetate base-type fluid are examined. Brownian and thermophoretic phenomena are included. Non-linear partial differential equations (PDEs) are converted into non-linear ordinary differential equations (ODEs) via von Karman similarity variables. Dataset is generated by the 4th-order Runge-Kutta numerical method for the artificial neural network. The ratio parameter and melting parameter enhance the velocity outline, while the melting parameter and thermal stratification parameter reduce the temperature outline. An increase in the concentration outline is seen with the activation energy parameter and Brownian motion parameter both increase the concentration outline. The system's performance using metrics like regression analysis, mean squared error, and error histograms is evaluated. The impact of these factors on significant results, such as the drag coefficient and heat transfer rate, is statistically investigated using multiple linear regressions. The integration of statistical and machine learning methods is deemed crucial for enhancing understanding of complex fluid dynamics in magnetic nanofluid flows.

Effect of Double Stratification on MHD Williamson Boundary Layer Flow and Heat Transfer across a Shrinking/Stretching Sheet Immersed in a Porous Medium

The present study aims to provide a mathematical model of the Williamson fluid flow via a permeable stretching/shrinking sheet in the MHD boundary layer in the presence of a heat source, chemical reaction, and suction. This study is novel because it investigates the physical effects of thermal and solutal stratification on convective heat and mass transport using thermal radiation. The flow’s PDEs are numerically solved using the BVP4c approach and the pertinent similarity variables until a stable solution is found. Through visual analysis, the effects of dimensionless factors on temperature, velocity, and concentration profiles are examined. This encompasses the mass transfer rate, the heat transfer rate, and the coefficient of friction. The results of the present analysis are found to be consistent with those of previously published studies. The findings demonstrate that enhanced temperature and concentration profiles cause the Williamson, magnetic, and permeability parameters to rise in conjunction with a drop in the dimensionless velocity. In relation to temperature, the thermal stratification parameter exhibits the opposite tendency. Regarding the solutal stratification parameter, concentration profiles are seen to show the opposite trend. Lastly, the current work will have important implications for the removal of dust and viruses from viscoelastic fluid in bioengineering, the medical sciences, and medical equipment.

Density gradient effect on circulation patterns and mixing processes: Observations at the convergence front of a salt wedge, microtidal estuary

The convergence front in estuaries is a crucial area influenced by dynamic mixing processes which vary from one tidal cycle to another, with density gradients playing a key role in shaping circulation patterns. This significance is particularly pronounced in salt wedge estuaries, where discharge holds greater influence than tides. Despite this, there is a limited amount of research based on high-resolution in-situ data to analyze circulation and mixing processes affected by density gradients in the convergence front of a salt wedge estuary. In this study, continuous measurements of current velocities and CTD profiles were conducted over three tidal cycles to analyze the intratidal variability of circulation patterns (u, v, w) and mixing parameters in the convergence front. Stratification parameter (ηs) and Richardson numbers (RL and Ri) were calculated to analyze the mixing/stratification variability within a tidal cycle. The observations revealed a persistent Subsurface Velocity Maximum (SVM) in the longitudinal component, coinciding with density gradient increases > 4 kg m−3 along the water column. Similarly, lateral circulation patterns were influenced by those increases in density gradient, resulting in eastward-directed currents and the formation of two circulations cells. As expected in a salt wedge estuary, stratification occurs during flood and High Water (HW), when the density gradient increases due to intrusion of the salt wedge. Notably, in the Magdalena River estuary, when the discharge is below 3800 m3 s−1, the salt wedge remains consistently present irrespective of the tidal phase, resulting in a permanently stratified water column with ηs values between 1.60 – 1.95. It is expected that the steady presence of stratified conditions during periods of low discharge leads to an increased accumulation of sediments. These findings provide valuable quantitative insights into the complex interplay of density gradients, circulation patterns, and stratification dynamics in salt wedge estuaries.

Asymmetric drift in MaNGA: mass and radially dependent stratification rates in galaxy discs

ABSTRACT We measure the age–velocity relationship from the lag between ionized gas and stellar tangential speeds in ∼500 nearby disc galaxies from MaNGA in Sloan Digital Sky Survey IV (SDSS-IV). Selected galaxies are kinematically axisymmetric. Velocity lags are asymmetric drift, seen in the Milky Way’s (MW) solar neighbourhood and other Local Group galaxies; their amplitude correlates with stellar population age. The trend is qualitatively consistent in rate ($\dot{\sigma }$) with a simple power-law model where σ ∝ tb that explains the dynamical phase-space stratification in the solar neighbourhood. The model is generalized based on disc dynamical times to other radii and other galaxies. We find in-plane radial stratification parameters σ0,r (dispersion of the youngest populations) in the range of 10–40 km s−1 and 0.2 &amp;lt; br &amp;lt; 0.5 for MaNGA galaxies. Overall, brincreases with galaxy mass, decreases with radius for galaxies above 10.4 dex (M⊙) in stellar mass, but is ∼constant with radius at lower mass. The measurement scatter indicates the stratification model is too simple to capture the complexity seen in the data, unsurprising given the many possible astrophysical processes that may lead to stellar population dynamical stratification. None the less, the data show dynamical stratification is broadly present in the galaxy population, with systematic trends in mass and density. The amplitude of the asymmetric drift signal is larger for the MaNGA sample than the MW, and better represented in the mean by what is observed in the discs of M31 and M33. Either typical discs have higher surface-density or, more likely, are dynamically hotter (hence thicker) than the MW.