Exponential Diffusion Research Articles

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.

Preparation, mechanical analysis and investigation of swelling behavior of boron nitride reinforced hydrogel polymer composite films

AbstractThis study presents the preparation, hydrogel kinetics, and mechanical analysis of Boron Nitride (BN) reinforced PVA/PVP/PEO‐BN hydrogel composite films using Polyvinyl alcohol (PVA), Polyvinyl pyrrolidone (PVP), and Polyethylene oxide (PEO) commercial polymers. Dynamic mechanical analysis tests reveal that PVA90PEO5PVP5‐BN composite films exhibit plastic‐viscoelastic behavior under a maximum force of 18 N. The Young's Modulus values for PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20 are 0.22, 0.32, and 0.44 MPa, respectively. The highest % Strain value is observed in PVA90PEO5PVP5‐BN%20, reaching 279.80%. In the hydrogel kinetics study, Schott's and Fickian models are utilized. The regression from the Fickian model is quite low, with exponential diffusion index, n, values lower than 0.5, indicating a classical Fickian water diffusion mechanism. Schott's model provides graphs with significantly higher regression compared to the Fickian model. The results indicate compatibility with the other model and confirm the presence of water‐based diffusion. Equilibrium swelling values (Se, g H2O/g gel) are 6.71, 7.03, and 7.91 for PVA90PEO5PVP5, PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20, respectively. Differential Scanning Calorimetry (DSC) analysis results show that the glass transition temperatures, Tg, are 52.37, 60.20, and 63.05°C for PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20, respectively.

Influences of thermal and mass stratification on unsteady magnetohydrodynamics parabolic flow along an infinite vertical plate with periodic temperature variation and exponential mass diffusion in porous medium

AbstractThis study explores the dynamics of unsteady magnetohydrodynamics (MHD) parabolic flow along an infinite vertical plate, emphasizing the effects of thermal and mass stratification in a porous medium subjected to periodic temperature variation and exponential mass diffusion. Utilizing the Laplace transform technique to obtain precise solutions, this study effectively integrates the impacts of both thermal and mass stratification without dependence on approximations. The main goal is to assess how thermal and mass stratification impact MHD flow dynamics, temperature, and concentration profiles under varying conditions. The study provides a thorough comparison of these findings with traditional nonstratified scenarios, presenting a comprehensive analysis of fluid behavior under diverse conditions. The conclusions reveal that thermal and mass stratifications considerably diminish velocity and stabilize temperature distributions, which suggests a damping influence on fluid movement and improved management of diffusion processes. Enhanced Grashof numbers improve heat and mass transfer efficiency, while magnetic and Darcy parameters significantly influence flow resistance and heat transfer characteristics. These conditions also result in higher Nusselt and Sherwood numbers, indicating increased efficiency in heat and mass transfer. In contrast, scenarios without stratification display higher velocities and more unstable temperature and concentration profiles. The findings highlight the critical role of stratification in improving fluid dynamics and increasing the efficiency of heat and mass transfer processes, offering valuable insights for engineering and environmental applications in similar conditions. The main novelty of the research is being the first to use the Laplace transform for exact solutions on combined thermal and mass stratification in MHD flows, enhancing prediction accuracy and process control.

Comparative study of ultra-high field diffusion-weighted MRI imaging between hepatocellular carcinoma and paracancerous, distant cancerous, and background liver tissues

Objective: To investigate the differences in multi-b-value apparent diffusion coefficient (ADC) and exponential apparent diffusion coefficient (eADC) between hepatocellular carcinoma (HCC) and paracancerous liver tissue, distant cancerous liver tissue, and background liver tissues by ultra-high field 3.0T diffusion-weighted (DWI) MRI imaging. Methods: Sixty-eight consecutive HCC cases confirmed by surgical pathology from January 2018 to October 2021 were enrolled and divided into a cirrhosis (n=39) and a non-cirrhosis group (n=29) according to the presence or absence of cirrhosis.The average ADC and eADC of liver tissues of paracancerous (including proximal and distal), distant cancerous, and background were measured by DWI images with diffusion sensitivity factors (b) of 50, 100, 400, 600 s/mm2, and 1 000 s/mm2, respectively. The Kruskal-Wallis H test and Bonferroni method were used to test the differences between the measured values of the five tissues. The statistical differences were used to evaluate the diagnostic efficacy of the five tissues by parametric receiver operating characteristic (ROC) curve and area under the curve (AUC). Results: The comparison of average ADC and eADC among five types of tissues in the liver cirrhosis group showed that the average ADC and eADC measured at b values of 50, 100, 400, and 600 s/mm2 had statistically significant differences (adjusted P<0.005) between cancerous and proximal paracancerous, distal paracancerous, distant cancerous, and background liver tissue, as well as the average ADC measured at b=1 000 s/mm2 between cancerous and proximal paracancerous tissue. The average ADC and eADC in the non-cirrhosis group had statistically significant differences (adjusted P<0.005) between cancerous and proximal paracancerous, distant paracancerous, distant cancerous, and background liver tissue measured at b values of 50, 100, and 400 s/mm2, respectively. The average ADC and eADC measured at b=600 s/mm2 showed statistically significant differences (adjusted P<0.005) between cancerous and proximal paracancerous, distal paracancerous, and distant cancerous liver tissue, as well as the average ADC measured at b=1 000 s/mm2 between cancerous and distal paracancerous, and distant cancerous liver tissue. The average ADC and eADC in the cirrhosis group had no statistically significant difference between the proximal paracancerous and the distant cancerous, as well as the background liver tissue measured at b-values of 50, 100, 400, 600, and 1 000 s/mm2, respectively (adjusted P>0.005), while there were statistically significant differences (adjusted P<0.005) in the average ADC values in the non-cirrhosis group between the proximal paracancerous and the distant paracancerous and background liver tissues at b=50 s/mm2, as well as the average ADC and eADC values between the proximal paracancerous and the distant liver tissues at b=100 s/mm2. The average ADC and eADC values measured in the cirrhosis group and non-cirrhosis group had no statistically significant difference between the distant paracancerous, distant cancerous, and background liver tissue (adjusted P>0.005). The efficacy of average ADC and eADC in distinguishing five types of tissues (cancerous and proximal paracancerous, distant paracancerous, distant cancerous, and background liver tissue) showed that in the cirrhosis group, the diagnostic efficacy was best at b=50 s/mm2. The area under the ROC curve (AUC) of average ADC was 0.815, 0.828, 0.855, and 0.855, respectively, and the AUC of average eADC was 0.815, 0.830, 0.856, and 0.855, respectively. The diagnostic efficacy was best in the non cirrhosis group at b=100 s/mm2, with average ADC AUCs of 0.787, 0.823, 0.841, and 0.821, and average eADC AUCs of 0.836, 0.874, 0.893, and 0.873, respectively. The AUC of the average ADC in the non-cirrhosis group for distinguishing between proximal paracancerous and distant cancerous liver tissues, as well as proximal paracancerous and background liver tissues, with b=50 s/mm2, were 0.605 and 0.604, respectively. The average AUC of ADC and eADC for distinguishing between proximal paracancerous and distant liver tissues with b=100 s/mm2 were 0.619 and 0.620, respectively. Conclusion: The average ADC and eADC measured by multiple b-values are helpful in distinguishing HCC from proximal paracancerous, distal paracancerous, distant-cancerous, and background liver tissues in patients with cirrhosis and non-cirrhosis, while the average ADC and eADC at b=50 s/mm2 and 100 s/mm2 exhibit differences between the proximal paracancerous from the distant cancerous liver tissue and background liver tissue in patients with non-cirrhosis.

Influences of thermal stratification and chemical reaction on MHD free convective flow along an accelerated vertical plate with variable temperature and exponential mass diffusion in a porous medium

AbstractThis study examines the impacts of thermal stratification and chemical reaction on magnetohydrodynamic (MHD) free convective flow along an accelerated vertical plate with variable temperature and exponential mass diffusion, set within a porous medium. Analytical solutions, utilized, are obtained through the Laplace transform technique to accurately represent the flow's physical mechanism. The research employs advanced mathematical models to analyze the intricate interplay between MHD and convective processes under varying thermal and exponential mass diffusion conditions, offering insights into fluid dynamics that closely simulate real‐world conditions. The study draws a significant conclusion by contrasting the effects of thermal stratification with a nonstratified environment. It has been noted that when stratification is applied to the flow, the steady state is achieved more quickly. The study reveals that thermal stratification reduces fluid velocity and temperature but increases skin friction and the Nusselt number, diverging from nonstratified conditions. It also shows that parameters, like, , and significantly influence velocity, temperature, and concentration in fluid dynamics. This research could be driven by a need to enhance the understanding of fluid flow in various engineering and environmental contexts, where such conditions are prevalent, including geothermal energy extraction, thermal management, chemical processing industries, and environmental control technologies. This novel approach enhances understanding of flow processes in both natural and engineered porous environments.

Topological edge states in reconfigurable multi-stable mechanical metamaterials

Multi-stable mechanical structures find cutting-edge applications across various domains due to their reconfigurability, which offers innovative possibilities for engineering and technology advancements. This study explores the emergence of topological states in a one-dimensional chain-like multi-stable mechanical metamaterial composed of bistable units through a combination of mechanical and optical experiments. Drawing inspiration from the SSH (Su-Schrieffer-Heeger) model in condensed matter physics, we leverage the unique mechanical properties of the reconfigurable ligament-oscillator metamaterial to engineer a system with coexisting topological phases. Based on the one-dimensional periodic bistable chain, there is an exponential decay diffusion of elastic energy from both end boundaries towards the interior of the body. Experimental characterizations demonstrate the existence of stable topological phases within the reconfigurable multi-stable mechanical metamaterial. The findings underscore the potential of reconfigurable mechanical metamaterials as versatile platforms for flexibly exploring and manipulating topological phenomena, with applications ranging from impact resistance to energy harvesting and information processing.

Risk Assessment for Workers with Wearable Medical Devices Exposed to Electromagnetic Fields.

The exponential diffusion of wearable medical devices (WMD) in recent years has involved people of all ages, including workers. Workers who use WMDs should be considered at a particular risk from electromagnetic fields, and in accordance with EU Directive 2013/35/EU, they require an individual risk assessment. Currently, there is no international standard that provides specific guidance on how to perform such a risk assessment. This paper focuses on the effects of electromagnetic fields on WMDs and does not consider the direct effects on human body tissues. It aims to offer practical recommendations to employers and/or health physicists for the risk assessment of workers with WMDs. Focusing on EU countries, we first describe the requirements outlined by the technical standard for the electromagnetic compatibility (EMC) of medical electrical equipment EN 60601-1-2. Then, some general guidelines on how to perform the risk assessment are provided. The assessment can be conducted by comparing the field values measured in the workplace with the immunity test levels specified in the technical standards of medical electrical equipment. If the measured values are lower than the immunity test levels indicated in the standard and the distance from the electromagnetic source is greater than the distance used by the manufacturer during the EMC (electromagnetic compatibility) tests (typically 30 cm), the risk for the worker may be considered acceptable. However, if the measured values exceed the immunity test levels or the distance criteria, a specific evaluation based on a case-by-case analysis is required.

Ultrafast Diffusion Modeling via the Riemann–Liouville Nonlocal Structural Derivative and Its Application in Porous Media

Ultrafast diffusion disperses faster than super-diffusion, and this has been proven by several theoretical and experimental investigations. The mean square displacement of ultrafast diffusion grows exponentially, which provides a significant challenge for modeling. Due to the inhomogeneity, nonlinear interactions, and high porosity of cement materials, the motion of particles on their surfaces satisfies the conditions for ultrafast diffusion. The investigation of the diffusion behavior in cementitious materials is crucial for predicting the mechanical properties of cement. In this study, we first attempted to investigate the dynamic of ultrafast diffusion in cementitious materials underlying the Riemann–Liouville nonlocal structural derivative. We constructed a Riemann–Liouville nonlocal structural derivative ultrafast diffusion model with an exponential function and then extended the modeling strategy using the Mittag–Leffler function. The mean square displacement is analogous to the integral of the corresponding structural derivative, providing a reference standard for the selection of structural functions in practical applications. Based on experimental data on cement mortar, the accuracy of the Riemann–Liouville nonlocal structural derivative ultrafast diffusion model was verified. Compared to the power law diffusion and the exponential law diffusion, the mean square displacement with respect to the Mittag–Leffler law is closely tied to the actual data. The modeling approach based on the Riemann–Liouville nonlocal structural derivative provides an efficient tool for depicting ultrafast diffusion in porous media.

Pressure-dependent characteristics of the diffusion coefficient during the gas desorption process in coal cuttings: Numerical modelling and analysis

Determining the diffusion coefficient is crucial in coalbed methane development. Existing models have limitations, as they often apply only to spherical systems, cannot describe nonlinear adsorption, and do not quantify the impact of gas pressure on diffusion coefficients. Additionally, traditional trial methods struggle to accurately compute diffusion coefficients in numerical solutions. To address these challenges, our study builds two unipore diffusion models (EPDDM and PPDDM) by introducing exponential and power pressure-dependent diffusion coefficients, considering three-dimensional coordinates and Langmuir adsorption. And then proposes a diffusion coefficient determination method using a particle swarm optimization algorithm. Through desorption experiments, numerical modelling, and model comparisons, we analyze the evolution law of diffusion coefficient, gas pressure, and desorption volume during the desorption process. Our results show that the proposed models quantitatively depict the positive correlation between diffusion coefficient and gas pressure. Furthermore, they accurately reflect changes in desorption volume. During early-stage desorption, the diffusion coefficient of EPDDM is 1.63–1.85 times greater than that of PPDDM, while their desorption volumes are similar. This observation motivates the proposal of a more versatile Logistic pressure-dependent diffusivity model, aiming to unify the above two models. These achievements are anticipated to serve as a foundational framework for exploring the mechanisms governing gas diffusion.

Thermal and Mass Stratification Effects on Unsteady Flow Past an Accelerated Infinite Vertical Plate with Variable Temperature and Exponential Mass Diffusion in Porous Medium

This study looks at how thermal and mass stratification affect the unsteady flow past an infinitely fast-moving vertical plate when the temperature is changing and there is exponential mass diffusion in a porous medium. By applying the Laplace transformation method, we determine the solutions to the equations that govern the system for the case of unitary Prandtl and Schmidt numbers. Graphical representations of the concentration, temperature, and velocity profiles, as well as the Nusselt Number, Sherwood number, and the Skin friction are provided to facilitate discussion of the cause of the different variables. To see the effects of thermal and mass stratification on the fluid flow, we compare the classical solution (Fluid with out stratification) with the primary solution (Fluid with the stratification) by using graph. The combined effects of the two stratification lead to a quicker approach to steady states. The outcomes can be helpful for heat exchange design and other engineering applications.

A Comprehensive Survey on Methods for Image Integrity

The outbreak of digital devices on the Internet, the exponential diffusion of data (images, video, audio, and text), along with their manipulation/generation also by Artificial Intelligence (AI) models, e.g., Generative Adversarial Networks (GANs), have created a great deal of concern in the field of forensics. A malicious use can affect relevant application domains, which often include counterfeiting biomedical images, and deceiving biometric authentication systems, as well as their use in scientific publications, in the political world, and even in school activities. It has been demonstrated that manipulated pictures most likely represent indications of malicious behavior, such as photos of minors to promote child prostitution or false political statements. Following this widespread behavior, various forensic techniques have been proposed in the scientific literature over time both to defeat these spoofing attacks as well as to guarantee the integrity of the information. Focusing on Image Forensics, which is currently a very hot topic area in Multimedia Forensics, this paper will discuss the whole scenario in which a target image could be modified. The aim of this comprehensive survey will be 1) to provide an overview of the types of attacks and contrasting techniques and 2) to evaluate to what extent the former can deceive prevention methods and the latter can identify counterfeit images. The results of this study highlight how forgery detection techniques, sometimes limited to a single type of real scenario, are not able to provide exhaustive countermeasures and could/should therefore be combined. Currently, the use of neural networks, such as CNNs, is already heading, synergistically, in this direction.

Implication of electromagnetohydrodynamic and heat transfer analysis in nanomaterial flow over a stretched surface: Applications in solar energy

The limited availability of non-renewable energy resources, the need to protect ecosystems, and financial considerations create a powerful driving force for studying renewable energy and improving thermal energy systems. The utilization of solar radiation and nanofluids containing polyvinyl alcohol–water-based fluids with copper nanoparticles offers an opportunity to improve the efficiency of sustainable solar heating systems. Owing to its usage, this research examines the electromagnetohydrodynamic and thermal transfer of Jeffrey nanofluid flow over a stretchable surface by employing the influence of gyrotactic microorganisms on this flow. Additionally, the current research focused on creating an advanced numerical model that accurately exemplifies the flow and thermal properties of a parabolic trough solar collector (PTSC) installed on a solar plate to generate a continuous energy source. The unique aspect of our research lies in the integrated approach, combining EMHD, nanofluid flow, and stretchable surface technology to investigate the thermal performance of the coating. This innovative combination opens up new possibilities for efficient thermal management in solar energy applications. The effectiveness of thermal transport in PTSC is evaluated by investigating several factors such as the electric field parameter, solar radiation, exponential heat source, bioconvection Rayleigh, and diffusion parameter. This research utilizes invariant transformations to simplify partial differential equations into ordinary differential equations. These equations are then solved using the wavelets and the Chebyshev wavelets scheme (CWS) with the help of MATHEMATICA 11.3 software. The research outcomes revealed that an increase in the solar thermal radiation, and electric field parameters leads to a higher temperature distribution in concentrated solar power. Therefore, this research aims to improve industrial performance by increasing the efficiency of thermal power generation systems.

Proper Generalized Decomposition using Taylor expansion for non-linear diffusion equations

For a physical problem described by a parameterized mathematical model, different configurations of the problem require computing the solution over a range of parameters in order to study the phenomenon when parameters change. In other words, it is a process of looking for a continuum of solutions of the equation, relative to these parameters, in order to find the ones that fit the experimental data. However, solving a direct problem for each parametric configuration will generate a cascade of direct problems, which will cost a huge amount of time, especially when we deal with non-linear equations. Therefore, the parametric solution is a suitable alternative strategy to compute the solution of the equation. In this paper, we will use the Proper Generalized Decomposition (PGD) method to solve non-linear diffusion equations and produce parametric solutions. To treat the non-linear functions, we will not use the Discrete Empirical Interpolation Methods (DEIM), which has proven their utility, but the non-linear terms will be replaced by their Taylor series expansion up to an order m. This will produce a new model, which we call here the ”developed equation” and therefore the PGD is applied on. Polynomial equations appear for each tensor element computation. While space and time tensor elements’ equations are to be solved using Finite Elements Methods (FEM) and Borel–Padé–Laplace (BPL) integrator respectively, Newton solver is used for tensors relative to the parameters’ equations. Here, rational polynomial functions arise for parametric tensor elements, which are known to extrapolate solutions. Numerical simulations are done for a non-linear diffusion equation with exponential diffusion coefficient as first trial, and with a magnetic diffusion coefficient as a second one.

Real-Time Correction of Gas Concentration in Nondispersive Infrared Sensor

Non-dispersive infrared (NDIR) sensors have been widely used in measuring gas concentration in process industry. However, the inhomogeneous gas diffusion in the gas chamber of NDIR sensor increases the response time and causes measurement error. In this case, the fast-and-accurate measurement of gas concentration is of great importance in avoiding accidents. This article focuses on constructing a novel gas diffusion model among normalization concentration (N-concentration), inlet flow velocity, and diffusion time. Firstly, the structure model of gas chamber is constructed based on Fluent 15.0 and the turbulence intensity is calculated based on dynamic viscosity, inlet flow velocity, concentration, temperature and pressure. The simulation model is constructed based on the assumption of simultaneous reaction and mass transfer. The initial result shows that the N-concentration along the optical path is mainly influenced by inlet flow velocity and diffusion time, while the temperature, pressure and inlet concentration have less influence on gas diffusion. According to the velocity distribution map, the critical zone of inlet flow velocity is defined to divide the gas diffusion state into different zones. Then, a novel Multi-interval exponential diffusion model is proposed to calculate the N-concentration and the real-time measurement of gas concentration can be achieved based on inlet flow velocity, diffusion time and the pre-defined critical zone of inlet flow velocity. The proposed model is suitable for the gas concentration correction of different gases. Finally, the validation indexes include the coefficient of determination (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), Mean Squared Error (MSE) and standard uncertainty shows the accuracy of the proposed model can be obviously increased.

A new exponential model for predicting soil gas diffusivity with varying degree of saturation

AbstractSoil gas diffusivity (Dp/Do, gas diffusion coefficients in soil and in free air, respectively) and its relation to soil moisture is of great importance for describing and quantifying essential provisional and regulatory functions associated with terrestrial ecosystems such as soil aeration and greenhouse gas (GHG) emissions. Because gas migration in terrestrial soil systems is predominantly diffusion controlled, soil gas diffusivity becomes a fundamental prerequisite to quantify diffusive gas fluxes. Descriptive–predictive models are often used to estimate Dp/Do from easily measurable soil physical properties. Most of the available models take the form of power‐law functions and often tend to mischaracterize soil moisture effects at high moisture regimes. Based on a wide range Dp/Do data available in literature representing both intact and repacked soils, this study developed a novel air‐saturation‐dependent exponential (ASEX) gas diffusivity model to model Dp/Do in relation to soil air saturation. The model variable α, which represents the diffusivity at half air saturation normalized by the same in complete soil air saturation, could potentially differentiate moisture effects on different soil structural states. For specific applications in intact soils, we propose corresponding α values for upper‐limit (α = .6) and lower‐limit (α = .05) estimates of diffusivity, while an average value (α = .3) for general applications in both intact and repacked soils. As expected, our model based on a few a priori measured supportive data showed a better performance over the classical predictive models that do not use such measurements. The new model was further used to derive useful implications to showcase soil density effects on Dp/Do.

Glioma segmentation with DWI weighted images, conventional anatomical images, and post-contrast enhancement magnetic resonance imaging images by U-Net.

Glioma segmentation is believed to be one of the most important stages of treatment management. Recent developments in magnetic resonance imaging (MRI) protocols have led to a renewed interest in using automatic glioma segmentation with different MRI image weights. U-Net is a major area of interest within the field of automatic glioma segmentation. This paper examines the impact of different input MRI image-weight on the U-Net output performance for glioma segmentation. One hundred forty-nine glioma patients were scanned with a 1.5T MRI scanner. The main MRI image-weights acquired are diffusion-weighted imaging (DWI) weighted images (b50, b500, b1000, Apparent diffusion coefficient (ADC) map, Exponential apparent diffusion coefficient (eADC) map), anatomical image-weights (T2, T1, T2-FLAIR), and post enhancement image-weights (T1Gd). The U-Net and data augmentation are used to segment the glioma tumors. Having the Dice coefficient and accuracy enabled us to compare our results with the previous study. The first set of analyses examined the impact of epoch number on the accuracy of U-Net, and n_epoch = 20 was selected for U-Net training. The mean Dice coefficient for b50, b500, b1000, ADC map, eADC map, T2, T1, T2-FLAIR, and T1Gd image weights for glioma segmentation with U-Net were calculated 0.892, 0.872, 0.752, 0.931, 0.944, 0.762, 0.721, 0.896, 0.694 respectively. This study has found that, DWI image-weights have a higher diagnostic value for glioma segmentation with U-Net in comparison with anatomical image-weights and post enhancement image-weights. The results of this investigation show that ADC and eADC maps have higher performance for glioma segmentation with U-Net.

Sequential multiblock partial least squares discriminant analysis for assessing prostate cancer aggressiveness with multiparametric magnetic resonance imaging

In current radiology practice, multi-parametric magnetic resonance imaging (mpMRI) has recently become a key tool in diagnostic and therapeutic decisions. Although it is based on the subjective assessment of T2-weighted images, as well as perfusion-weighted and diffusion-weighted sequences, further quantitative parameters can also be derived from them for improving lesion phenotyping. Despite these parameters are usually exploited in a univariate way, ignoring the benefits of a real multivariate approach, still it is the gold standard imaging technique to assess prostate cancer location and probability of malignancy. In this paper, pharmacokinetic (perfusion) and exponential (diffusion) clinical models, as well as latent variable-based multivariate statistical models like multivariate curve resolution-alternating least squares (MCR-ALS), have been calculated and analyzed with sequential multi block-partial least squares discriminant analysis (SMB-PLS-DA) including technique-block differentiation, in order to better assess for cancer aggressiveness based on Gleason scales. The best prediction result was achieved by the ordered combination of diffusion blocks (MCR-ALS and exponential models) and normalized T2 values. The perfusion blocks did not improve the results obtained by diffusion and T2-weighted based parameters alone, so they can be removed from the SMB-PLS-DA model.

Core overshoot constrained by the absence of a solar convective core and some solar-like stars

ABSTRACT Convective-core overshoot mixing is a significant uncertainty in stellar evolution. Because numerical simulations and turbulent convection models predict exponentially decreasing radial rms turbulent velocity, a popular treatment for overshoot mixing is to apply a diffusion process with an exponentially decreasing diffusion coefficient. It is important to investigate the parameters of the diffusion coefficient because they determine the efficiency of the mixing in the overshoot region. In this paper, we have investigated the effects of the core overshoot mixing on the properties of the core in solar models. We have constrained the parameters of the overshoot model by using helioseismic inferences and the observation of the solar 8B neutrino flux. For solar-mass stars, the core overshoot mixing helps to prolong the lifetime of the convective core developed at the zero-age main sequence. If the strength of the mixing is sufficiently high, then the convective core in a solar model could survive until the present solar age, leading to large deviations of the sound speed and density profiles compared with the helioseismic inferences. The 8B neutrino flux also favours a radiative solar core. These observations provide a constraint on the parameters of the exponential diffusion model of the convective overshoot mixing. A limited asteroseismic investigation of 13 Kepler low-mass stars with 1.0 &amp;lt; M/M⊙ &amp;lt; 1.5 shows a mass-dependent range of the overshoot parameter. The overshoot mixing processes for different elements are analysed in detail. It is found that the exponential diffusion overshoot model leads to different effective overshoot mixing lengths for elements with different nuclear equilibrium time-scales.

First 100 minimally invasive liver resections in a new tertiary referral centre for liver surgery.

Background:In the last decades, there has been an exponential diffusion of minimally invasive liver surgery (MILS) worldwide. The aim of this study was to evaluate our initial experience of 100 patients undergoing MILS resection comparing their outcomes with the standard open procedures.Materials and Methods:One hundred consecutive MILS from 2016 to 2019 were included. Clinicopathological data were reviewed to evaluate outcomes. Standard open resections were used as the control group and compared exploiting propensity score matching.Results:In total, 290 patients were included. The rate of MILS has been constantly increasing throughout years, representing the 48% in 2019. Of 100 (34.5%) MILS patients, 85 could be matched. After matching, the MILS conversion rate was 5.8% (n = 5). The post-operative complication rates were higher in the open group (45.9% vs. 31.8%, P = 0.004). Post-operative blood transfusions were less common in the MILS group (4.7% vs. 16.5%, P = 0.021). Biliary leak occurred in 2 (2.4) MILS versus 13 (15.3) open. The median comprehensive complication index was higher in the open group (8.7 [0–28.6] vs. 0 [0–10.4], P = 0.0009). The post-operative length of hospital stay was shorter after MILS (median 6 [5–8] vs 8 [7–13] days, P < 0.0001).Conclusions:The rate of MILS has been significantly increasing throughout the years. The benefits of MILS over the traditional open approach were confirmed. The main advantages include lower rates of post-operative complications, blood transfusions, bile leaks and a significantly decreased hospital stay.

The correlation between magnetic resonance diffusion parameters and Ki-67 and PCNA in hepatic fibrosis and cirrhosis rats.

The aim of this study was to assess the value of different 1.5 T MRI apparent diffusion coefficient (ADC) and exponential apparent diffusion coefficient (EADC) values in diagnosing the stages of liver cirrhosis. Sprague-Dawley (SD) rats were randomly divided into the experimental group and the control group. The experimental group was injected with thioacetamide intraperitoneally 3 times per week. After routine MR scanning, diffusion-weighted imaging (DWI) was processed by spin echo-echo planar imaging (SE-EPI) to generate the ADC value and EADC image. The liver ADC and EADC values of rats were measured in the control and experimental groups, followed by Masson staining and hematoxylin and eosin staining. Furthermore, immunohistochemistry was performed to detect Ki-67 and PCNA expression in liver tissues. In the control group, the differences in ADC and EADC values between the liver fibrosis and cirrhosis group were different. The ADC values of the liver fibrosis stage I-II, III-IV, and cirrhosis rats in the experimental group were lower than the control group, while the EADC values were higher than the control group. The ADC values of the liver fibrosis stage III-IV group and cirrhosis nodules group were lower than the control group. There were significant differences in EADC values between the cirrhotic nodule groups and the control group. DWI-ADC values showed a negative correlation between SD rat liver fibrosis and cirrhosis pathology classification.