Limited Flow Research Articles

Polysomnographic features of hypoglossal nerve stimulation efficacy: Looking deeper than the apnea-hypopnea index.

Hypoglossal nerve stimulation (HGNS) is a promising surgical option for patients with obstructive sleep apnea (OSA) who are intolerant of continuous positive airway pressure therapy (CPAP). Efficacy studies for HGNS stimulation largely focus on the apnea-hypopnea index and/or oxygen desaturation index. This study's objective was to show the physiological effects of HGNS stimulation on upper airway patency, airflow, and treatment effect during polysomnography (PSG) testing. PSG tracings from patients implanted with an Inspire© HGNS device were reviewed for this study. Nasal pressure was utilized as a surrogate for respiratory flow and chin electromyography was used to detect HGNS stimulation, allowing for breath-to-breath analysis. Per our sleep laboratory protocol, the HGNS device was turned on and off at different periods of the night. Respiratory tracings during these periods were visually analyzed. Analysis of on-off periods of HGNS therapy during PSG allows for a concise assessment of HGNS efficacy. The presence of inspiratory flow limitation and subsequent apneas or hypopneas upon turning off HGNS stimulation with restoration of stable, unobstructed breathing upon resuming HGNS stimulation indicates a positive treatment effect related to HGNS therapy. Despite the respiratory-sensing capacity of the Inspire HGNS device, desynchrony of stimulation and inspiration is observed. Desynchrony yields partially captured inspiratory cycles, allowing for assessment of HGNS effect on an individual breath. Night-to-night and intranight variability in OSA severity makes assessing the effect of HGNS complex. Strategic testing protocols during postoperative PSG can provide critical insight into the effect of this therapy on upper airway obstruction during sleep. On-off periods of stimulation provide a concise assessment of the effect of HGNS on preventing upper airway collapse and help to account for night-to-night and intranight variability. Respiratory desynchrony associated with HGNS therapy exists. Observing partially-stimulated inspiratory cycles allow for assessment of HGNS's effect on a single breath. 4.

The effect of working capital management and capital structure on firm value through profitability as a mediating variable in manufacturing companies during the COVID-19 pandemic

During the COVID-19 pandemic, many companies experienced a decline in performance due to market uncertainty, cash flow limitations, and disruptions to supply chains. Therefore, effective capital management to support company performance became crucial. This study aims to analyze the impact of working capital management (CCC) and capital structure (DER) on firm value (Tobin’s Q) through profitability (ROA) among manufacturing companies listed on the Indonesia Stock Exchange during the Covid-19 pandemic from 2020 to 2022. The sample was selected using purposive sampling, resulting in a total of 118 companies. Data analysis includes descriptive statistics, normality tests, Robust Least Squares regression, coefficient of determination tests, partial tests, path analysis, and Sobel test. The results indicate that the independent variables CCC and DER do not have a direct significant effect on firm value during the Covid-19 pandemic. However, when profitability (ROA) is considered as a mediating variable, both CCC and DER show a negative impact on firm value. Furthermore, the study reveals a differing direct relationship between capital structure (DER) and firm value, where the relationship is positive.

Feasibility and Safety of Distal Radial Artery Access with Recanalization of a Chronic Radial Artery Occlusion for Subsequent Coronary Angiography and Intervention.

This study aims to verify the feasibility and safety of percutaneous coronary intervention (PCI) after a distal transradial approach (dTRA) with radial artery occlusion (RAO) recanalization. Between July 2018 and January 2022, 30 patients underwent PCI following attempted RAO recanalization via dTRA. Among these cases, the target radial arteries could not be recanalized in five patients, necessitating alternative vascular access. The remaining 25 patients with successful RAO recanalization were divided into a standard group (n = 19) and tough group (n = 6), the latter requiring more than 10 minutes and complex techniques and devices for recanalization. The procedural success rate was 96.7%, with vascular access-site complications occurring in 20% of the cases, including five perforations easily managed with prolonged balloon inflation and one pseudoaneurysm without flow limitation. In the tough group, no significant increase in procedural complications, access-site vascular complications, or total major adverse cardiac and cerebrovascular events was observed. However, Doppler ultrasound one month later for the recanalized radial artery revealed a significantly higher rate of severe stenosis and re-occlusion at 100% compared to 10% in the standard group, as supported by receiver operating characteristic curve analysis. The feasibility and safety of PCI following RAO recanalization via dTRA were acceptable. We propose a 10-minute threshold to differentiate between standard and tough groups during RAO recanalization. Given the uncertainty of long-term patency in recanalized RAs, the primary goal in tough cases is to ensure the guide catheter reaches the ascending aorta for subsequent PCI.

Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males.

To assess the impact of thoracic load carriage on the physiological response to exercise in hypoxia. Healthy males (n = 12) completed 3 trials consisting of 45 min walking in the following conditions: (1) unloaded normoxia (UN; FIO2:20.93%); (2) unloaded hypoxia (UH; FIO2:~13.0%); and (3) loaded hypoxia (LH; 29.5 kg; FIO2:~13.0%). Intensity was matched for absolute VO2 (2.0 ± 0.2 L·min-1) across conditions and relative VO2 (64.0 ± 2.6 %VO2max) across hypoxic conditions. With LH versus UH, there were increases in breathing frequency (5-11 breaths·min-1; p < 0.05) and decreases in tidal volume (10%-18%; p < 0.05) throughout exercise due to reductions in end inspiratory lung volumes (p < 0.05). Consequently, deadspace (11%-23%; p < 0.05) and minute ventilation (7%-11%; p < 0.05) were increased starting at 20 and 30 min, respectively. In addition, LH increased perceived exertion/dyspnea and induced inspiratory (~12%; p < 0.05 vs. UN) and expiratory (~10%; p < 0.05 vs. pre-exercise) respiratory muscle fatigue. Expiratory flow limitation was present in 50% of subjects during LH. Cardiac output and muscle oxygenation were maintained during LH despite reduced stroke volume (6%-8%; p < 0.05). Finally, cerebral oxygenated/total hemoglobin were elevated in the LH condition versus UH starting at 15 min (p < 0.05). Thoracic load carriage increases physiological strain and interferes with the compensatory response to hypoxic exposure.

Impact of Addition of a Newtonian Solvent to a Giesekus Fluid: Analytical Determination of Flow Rate in Plane Laminar Motion

In this study, the influence of the presence of a Newtonian solvent on the flow of a Giesekus fluid in a plane channel or fracture is investigated with a focus on the determination of the flow rate for an assigned external pressure gradient. The pressure field is nonlinear due to the presence of the normal transverse stress component. As expected, the flow rate per unit width Q′ is larger than for a Newtonian fluid and decreases as the solvent increases. It is strongly dependent on the viscosity ratio ε (0≤ε≤1), the dimensionless mobility parameter β (0≤β≤1) and the Deborah number De, the dimensionless driving pressure gradient. The degree of dependency is notably strong in the low range of ε. Furthermore, Q′ increases with De and tends to a constant asymptotic value for large De, subject to the limitation of laminar flow. When the mobility factor β is in the range 0.5÷1, there is a minimum value of ε to obtain an assigned value of De. The ratio UN/U between Newtonian and actual mean velocity depends only on the product βDe, as for other non-Newtonian fluids.

Experimental Analysis of Elastic Property Variations in Methane Hydrate-Bearing Sediments with Different Porosities

Natural gas hydrates, a promising clean energy resource, hold substantial potential. Porosity plays a crucial role in hydrate systems by influencing formation processes and physical properties. To clarify the effects of porosity on hydrate elasticity, we examined methane hydrate formation and its acoustic characteristics. Experiments were conducted on sediment samples with porosities of 23%, 32%, and 37%. P- and S-wave velocities were measured to assess acoustic responses. Results show that as hydrate saturation increases, sample acoustic velocity also rises. However, high-porosity samples consistently exhibit lower acoustic velocities compared to low-porosity samples and reach a lower maximum hydrate saturation. This behavior is attributed to rapid pore filling in high-porosity samples, which blocks flow pathways and limits further hydrate formation. In contrast, hydrate formation in low-porosity sediments progresses more gradually, maintaining clearer pore channels and resulting in relatively higher hydrate saturation. Higher porosity also accelerates the shift of hydrates from cementing to load-bearing morphologies. These findings underscore porosity’s significant influence on hydrate formation and provide insights into observed variations in hydrate saturation and acoustic velocity across different experimental conditions.

К влиянию растягивающих напряжений на интенсивность язвенной коррозии низкоуглеродистых трубных сталей

A significant part of accidents on trunk lines are ensured by metal corrosion. The most dangerous form of corrosion of trunk lines is location-action (pitting) corrosion of the inner wall of the pipe. An important factor in the corrosion process of the inner wall of a trunk line is the stress-strain state of the pipe metal, which impact on the intensity of pitting corrosion has been underexplored. This article presents the results of a study of the effect of tensile stresses on the intensity of pitting corrosion of low-carbon tube steels St3 and 08sk grades. As part of the study, corrosion tests of steel samples in stressed and non-stressed states were carried out, followed by determination of the depth of formed corrosion pits using a photometric technique. It is shown that for steel samples in a stressed state at a stress level of 0,7 with flow limit σT of the analyzed steels, the rate of pit depths increased 2,3 times for steel St3 and 1,2 times for steel 08sk compared with non-stressed samples, which significantly exceeds the value of a similar factor for the rate of general corrosion.At the same time, the obtained values of the mechanochemical coefficients also turned out to be higher than in case of a general corrosion – 0,0059 and 0,0014 MPa-1 compared to 0,0011. The authors explain the more intense effect of the stress state on the rate of pitting corrosion by the occurrence of stresses in the metal of the bottom part of the corrosion pits, which are significantly greater than the stresses occurring in the rest of the metal of the subsurface layer of the sample subjected to general corrosion.

Night to night variability in obstructive sleep apnea severity, the physiological endotypes and the frequency of flow limitation.

There is substantial night-to-night variability (NtNV) in obstructive sleep apnea (OSA) severity in some individuals, however predictors for this remain incompletely understood. This study aims to quantify the degree of NtNV in the apnea-hypopnea index (AHI), hypoxic burden, airflow limitation, and OSA endotypes; to determine if a relationship exists between the degree of NtNV in AHI and in endotype expression; to assess whether the degree of flow limited breathing is predictive of the degree of NtNV of the AHI. 71 patients with OSA underwent two polysomnograms (PSGs). OSA endotypes, hypoxic burden and flow limitation frequency were extracted from PSG data. Intra-individual agreement was assessed and associations with the NtNV of the AHI were calculated. Patients were grouped into High Variability vs Low Variability based on the degree of difference in AHI between each night. Despite wide limits of agreement, at the group level most PSG and endotype variables were not statistically different between first and second night. Flow limitation frequency was 7.7% (2.1 to 13, P<0.01) higher on the second night compared to baseline. There were weak linear associations between NtNV of endotypes and NtNV of the AHI. In sub-group analysis, there was greater difference between nights for Vactive (5%eupnea, P=0.01), Vpassive (3.1%eupnea, P=0.03), Vcomp (3.2%eupnea, P=0.01) and arousal threshold (4.1%eupnea, P=0.04) in the High Variability compared to the Low Variability group. There is high NtNV in AHI, OSA endotypes and flow limitation in some individuals, however no strong linear relationship exists between these changes.

Stability and related zero viscosity limit of steady plane Poiseuille-Couette flows with no-slip boundary condition

We study the existence and stability of smooth solutions to the steady Navier-Stokes equations near plane Poiseuille-Couette flow in the absence of any external force in two-dimensional domain Ω=(0,L)×(0,2). Under the assumption 0<L≪1, we prove that there exist smooth solutions to the steady Navier-Stokes equations which are stable under infinitesimal perturbations of plane Poiseuille-Couette flow. In particular, if the basic flow is the Couette flow, then through a formal asymptotic expansion including the Euler correctors and weak boundary layer correctors with different scales near the rigid walls y=0 and y=2, we can prove that for any finite disturbance o(1) of the Couette flow in horizontal direction, there still exist stable smooth solutions to the steady Navier-Stokes equations. Finally, based on the same linear estimates, we establish the zero viscosity limit of the solutions obtained above to the solutions of the steady Euler equations.

Simulation of Blood Flow in Arteries for Functional Assessment of Coronary Disease: Implementation of Numerical Code

Cardiovascular diseases are a major cause of mortality and morbidity in developed countries. Coronary atherosclerotic disease (CAD) is a degenerative process that is characterized by the development of atheromatous plaques on the wall of coronary arteries. Clinical manifestations of CAD range from stable angina, resulting from progressive plaque growth with partial obstruction of the arterial lumen (stenosis) and consequent limitation of coronary blood flow. In clinical practice, a diagnostic strategy is widely used to assess the functional relevance of CAD: the invasive assessment of myocardial fractional flow reserve (FFR).Coronary Computed Tomography Angiography (CTA) is an established non-invasive diagnostic tool for evaluating CAD. However, CTA can overestimate anatomic stenosis and is limited in that it does not provide information on the hemodynamic relevance of coronary stenosis. Thus, the implementation and numerical simulation of blood flow in arteries in the most real physiological conditions has been one of the main areas of interest of the authors [1]. The main purpose of this work is to develop and validate a computational tool for calculating the FFR and hemodynamic descriptors.In this way, to obtain the most accurate non-invasive FFR, the hemodynamic numerical tool was hardly improved to establish real conditions, specific to each patient case with CAD. Therefore, to achieve accurate pressures, Windkessel models, mainly based on the resistance of blood flow [2], were implemented considering hyperemia conditions (maximal dilation of the coronary tree), since the patient must be subjected to this condition during the catheterization to obtain the invasive FFR (reference value for validation). Moreover, the 3D patient-specific geometry of the artery was modified to simulate blood flow in hyperemic conditions. The numerical code development was performed in ANSYS® software.After validation, the authors aim to create a software for local use, allowing a comprehensive assessment of CAD in an accessible, fast, reliable, and non-invasive way. [1] Pinto, S.I.S. et al. (2020). The impact of non-linear viscoelastic property of blood in right coronary arteries hemodynamics – a numerical implementation. International Journal of Non-Linear Mechanics 123, 103477.[2] Boileau, E. et al. (2018) Estimating the accuracy of a reduced-order model for calculation of fractional flow reverse (FFR). Int J Numer Meth Biomed Engng 34, e2908.

Airfoil Design and Flow Analysis of a Multi-Blade Centrifugal Fan: An Experimental and Simulation Study

To overcome the technical challenges of the multi-blade centrifugal fan, such as low efficiency and insufficient total pressure, the blades of the fan were optimally designed in this study. The flow field of the multi-blade centrifugal fan with a single-arc blade and an airfoil blade was simulated and compared using Computational Fluid Dynamics (CFDs). Under steady-state conditions, the total pressure, velocity field distribution, and aerodynamic performance of a multi-blade centrifugal fan were analyzed. The numerical results showed that there were vortices, secondary flows, and boundary layer separation phenomena in the flow passage of the single-arc multi-blade centrifugal fan. Based on the lift-to-drag ratio theory of airfoil in aerodynamics, four different airfoil blades were designed for the multi-blade centrifugal fan. The study found that the lift-to-drag ratio of the airfoil blades was positively correlated with the fan efficiency; among them, the A-type airfoil exhibited the highest lift-to-drag ratio within the 0–10 degree angle of attack range. The three-dimensional simulation results indicated that, except for the initial operating point B, the A-type airfoil showed higher fan efficiency under other operating conditions, and its total pressure curve was the most stable. In addition, the use of airfoil blades effectively suppressed the aforementioned adverse flow phenomena and improved the flow within the blade passage. Experimental verification further confirmed the effect of airfoil blades on improving fan performance: compared to single-arc blades, the efficiency of the multi-blade centrifugal fan increased by 3–7% after using airfoil blades, and the upper limit of high-efficiency flow increased from 450 m3/h to 650 m3/h. Meanwhile, the total pressure and power of the airfoil fan were also significantly improved. The results of this work are significant for guiding the optimal design of the fan.

Conservative Management and Postoperative Return to Sport in Endurance Athletes with Flow Limitations in the Iliac Arteries: A Scoping Review.

Flow limitations in the iliac arteries (FLIA) is a sport-related vascular condition increasingly recognised as an occupational risk for professional cyclists and other endurance athletes. Surgical reconstruction is the definitive treatment for athletes wishing to continue competition. However, less information has been published regarding conservative management options and return-to-sport (RTS) guidelines. Our aim was to review the existing literature on conservative treatment of FLIA, identify knowledge gaps and propose an RTS framework for athletes returning to competition. A comprehensive literature review was performed using the Ovid-MEDLINE, PubMed, Embase and PEDro databases for publications relevant to conservative management of FLIA. A scoping review was conducted following PRISMA-ScR guidelines. Original, peer-reviewed publications in English describing conservative or postoperative management for athletes with FLIA were included. Additional grey literature and clinical expertise were consulted to inform RTS guidelines. Overall, 62 studies were included in this review. In total, 11 categories of conservative modalities were extracted and presented qualitatively in terms of the information source (discussion or results statements) and perspective of the authors (positive, negative or mixed). We have proposed RTS guidelines covering pre-operative preparation and postoperative rehabilitation based on the available literature, clinical experience, and drawing from other areas of sports medicine research. There is insufficient literature evaluating the effectiveness of conservative management options for FLIA to establish best practices. Considering the importance of RTS for competitive athletes, we proposed practical guidelines to help with clinician and patient decision making. Future consensus should be sought for RTS best practices.

Numerical simulation of battery thermal management based on ring microchannel cold plate

Efficient heat dissipation methods have been the focus of battery thermal management research. Due to the limitations of flow and heat transfer in traditional straight channel cold plates (SCCP), this paper introduces a ring channel cold plate (RCCP) and utilizes the j/f factor to evaluate the comprehensive thermal performance of the cold plates. Through comparison and analysis, it is found that the RCCP has a lower pressure drop and better comprehensive thermal performance. As the mass flow rate increases, the j/f improvement effect of the RCCP becomes more pronounced. Additionally, when the branch channel width is 6 mm, the RCCP exhibits higher comprehensive thermal performance. However, in the RCCP of equal width, the innermost channels have the shortest flow path and the largest flow rate. To further enhance heat transfer, the influence of non-uniform structure on the performance of RCCP is investigated. The result shows that the narrow inside and wide outside channel arrangement can enhance the heat transfer performance of the RCCP but at the cost of increasing pressure drop. Among them, the outermost, middle, and innermost channel widths of 6.66 mm, 6 mm, and 4 mm, the cold plate has better comprehensive thermal performance, more suitable for battery thermal management. The RCCP with a narrow inside and wide outside provides a new option for more efficient battery thermal management.

O040 Investigating the effects of airflow signal filtering on non-invasively quantified estimates of flow limitation

Abstract Introduction We previously reported a method to estimate flow limitation (FL, range 0-~1) from the airflow signal recorded within a polysomnogram. This method utilised high quality nasal pressure signals, without high-pass (HP) filtering. However, many clinical recording systems implement HP filtering on airflow signals. We hypothesised that FL estimates would be adversely affected when airflow signals have HP filtering present. Methods Within our existing framework for estimating FL, we manipulated the airflow signal by applying digital HP filtering (Butterworth, 4th order) at commonly used cutoff frequencies (0.005, 0.01, 0.03, 0.1Hz). At each HP filter cutoff, performance was assessed at the breath-level (pooled, all patients) and patient-level (median, sleep only) using coefficient of determination (R²) and root mean squared error (RMSE) comparing FL estimates with HP filtering against reference data without HP filtering. Results In N=96 individuals, R² decreased while RMSE increased as HP filter cutoff increased. For HP filter cutoffs at 0.005, 0.01, 0.03 and 0.1Hz, breath-level R² was 0.923, 0.879, 0.740, and 0.483; while RMSE was 0.062, 0.079, 0.129, and 0.219, respectively. Similarly, patient-level R² was 0.994, 0.977, 0.843, and 0.738; while RMSE was 0.015, 0.030, 0.100, and 0.170. Discussion Increasing HP cutoff frequency resulted in a reduction of consistency of FL estimates when compared to those made using an unfiltered airflow signal. Further work including reference to ‘gold standard’ is required, however, in line with current AASM recommendation (“Direct current (DC) or ≤0.03Hz”), this study suggests HP filter cutoff frequency for nasal pressure should be minimised, preferably avoided.

Triple inhaled therapy in asthma: Beliefs, behaviours and doubts

Long-acting muscarinic antagonists (LAMA) in association with inhaled corticosteroids (ICS) plus long-acting beta-2 agonists (LABA) are recommended by the GINA report as further option in step 4 and first choice in step 5 treatment. Despite consistent evidence of its efficacy and safety, inhaled triple therapy (ITT) is still not largely used in patients with asthma.With the aim to explore belief and behaviours of asthma specialists, an ad hoc survey has been developed by a panel of Interasma Scientific Network (INESnet) experts and subsequently defined by two Delphi rounds among an international group of physicians. The questionnaire has been distributed through Interasma social media between June and September 2023.Besides a descriptive analysis, to assess the responses gathered from the questionnaire, Spearman's non-parametric statistical method was employed.Totally, three hundred fourteen questionnaires were completed. Clinicians' attitudes and behaviours toward timing and methodologies adopted in prescribing ITT, were analysed. 35.7 % specialists consider ITT as a relevant therapeutic option, 61.8 % that is second option after reaching high dose of ICS-LABA and 89.2 % agreed that optimization of inhaled therapy should be attempted before the use of biological drugs. Persistent flow limitation and high reversibility are considered predictive factors of response.Specialists consider ITT a resource in asthma management. Although its efficacy in decreasing exacerbation rate and improving lung function were well known, the survey revealed persistent uncertainties among clinicians in positioning it highlighting the need for further measures to effectively integrate research findings into day-to-day clinical practice.

Ricci limit flows and weak solutions

In this paper we reconcile several different approaches to Ricci flow through singularities that have been proposed over the last few years by Kleiner–Lott, Haslhofer–Naber and Bamler. Specifically, we prove that every noncollapsed limit of Ricci flows, as provided by Bamler’s precompactness theorem, as well as every singular Ricci flow of Kleiner–Lott, is a weak solution in the sense of Haslhofer–Naber. We also generalize all path-space estimates of Haslhofer–Naber to the setting of noncollapsed Ricci limit flows. The key step to establish these results is a new hitting estimate for Brownian motion. A fundamental difficulty, in stark contrast to all prior hitting estimates in the literature, is the lack of lower heat kernel bounds under Ricci flow. To overcome this, we introduce a novel approach to hitting estimates that compensates for the lack of lower heat kernel bounds by making use of the heat kernel geometry of space-time.

Ventilatory Burden Predicts Change in Sleepiness Following Positive Airway Pressure in Sleep Apnea.

Excessive daytime sleepiness, an important symptom of obstructive sleep apnea (OSA), is commonly quantified using the Epworth Sleepiness Scale score (ESS). Baseline OSA severity measures (ventilatory burden, flow limitation, and hypoxemia) provide insights into OSA pathophysiology and could predict changes in sleepiness (i.e. change-in-ESS) following continuous positive airway pressure (CPAP) treatment. We hypothesized that change-in-ESS following CPAP treatment can be predicted from baseline polysomnography. Associations between OSA severity measures and ESS were evaluated in 2332 participants, adjusting for age, sex, BMI, and total sleep time. Change-in-ESS prediction was evaluated using 213 CPAP treatment studies (HomePAP, BestAIR, and ABC) in three steps: severity measures were compared (adjusted regression, n =64), a prediction model was developed using baseline ventilatory burden and baseline ESS ( n =139), and then evaluated in holdout participants ( n =74). In cross-sectional analysis, ESS was associated with ventilatory burden (0.45 points/SD; 95% CI 0.23-0.67), hypoxic burden (0.39; 0.17-0.62), the apnea-hypopnea index (AHI) (0.36; 0.14-0.59), and flow limitation severity (0.22; 0.01-0.43). Comparison analysis revealed that change-in-ESS was most strongly associated with baseline ventilatory burden (-1.08 points/SD; -2.13 to -0.05) and baseline ESS (-2.75; -3.83 to -1.69); the AHI association was weaker (-0.97; -2.01-0.05). Predicted change-in-ESS and actual change-in-ESS were correlated in holdout participants (adjusted R² =0.313); median [IQR] actual change-in-ESS of predicted responders (≥2-point ESS improvement, n =54, 73.0%) was -5.0 [-10.0 to -2.0] and non-responders was 0.0 [-1.0-1.0] ( P <0.001). Baseline ventilatory burden and baseline ESS were independently associated with change-in-ESS and could be used together to inform clinicians whether CPAP treatment will likely improve a patient's sleepiness.

Abstract 4135534: Total and Regional Lung Volumes And Pulmonary Blood Flow In Repaired Tetralogy Of Fallot - Smaller Lungs And A Maldistribution of Flow

Introduction: Many pts with repaired tetralogy of Fallot (rTOF) are left with residual pulmonary regurgitation (PR) and poor exercise performance. Small studies in young children suggest that the total lung volume of rTOF pts are smaller than normal and may contribute to these sequelae. As exercise and cardiac performance are intimately related to lung function, it’s surprising that few rTOF studies have investigated cardiopulmonary interactions. Aims: To determine if regional and total lung volumes in rTOF pts are the same size as normals and if the larger amount of forward blood flow courses to the bigger lung. We hypothesized that this may not be the case. Methods: rTOF patients undergoing clinically indicated cardiac magnetic resonance (CMR) were evaluated for lung volumes using dark blood imaging (figure) and blood flow to the branch pulmonary arteries (bPA) using velocity mapping. Significance &lt; P=0.05. Results: Eleven rTOF patients and 25 normal controls were studied. Total control lung volume was significantly larger than those of rTOF. Regional rTOF right and left lung volumes were smaller than their respective control lung volumes, barely missed statistical significance (table). In 6 rTOF pts with CMR prior to and after pulmonary valve replacement (PVR), lung volumes did not differ between the 2 timepoints (1034 vs 998 cc/m 2 respectively). Only 3/11 (27%) rTOF pts had the higher bPA flow coursing to the higher regional lung. The ratio of right bPA forward flow/right lung volume to left bPA forward flow/left lung volume ranged from 0.72-1.51 (ideal balanced flow to each lung would be 1), implying a maldistribution of flow. Conclusion: rTOF patients have smaller total lung volumes than controls with no change after PVR in our study. In addition, only a small proportion of rTOF patients have the larger amount of flow coursing to the larger lung. The ratio of individual bPA flow to individual lung volume implies a maldistribution of pulmonary flow relative to the respective lung volume. Our findings may have implications for timing of PVR, partially explaining PR and poor exercise performance. Flow limiters placed by cath or surgery may be able to redistribute the appropriate flow to regional lung fields.

The Influence of Fibers from Domestic Laundry Wastewater on the Clogging Process of a Filter

This study presents the impact of the size and shape of particles in laundry wastewater on the clogging process of a porous material. Clogging can be defined as a mechanical limitation of flow through porous media. The process of mechanical clogging was investigated in this study. The research was conducted in laboratory conditions in a filter column filled with glass beads whose diameter corresponded to coarse sand. The results reveal the influence of graywater quality on filter hydraulic conductivity and bed clogging, showing the impact of fiber particles in wastewater (sewage from home laundry) on the clogging process in soil. The results confirm that fiber particles significantly reduce filter permeability, particularly due to the formation of a filter cake. As analyzed in this paper, the distribution of quantitative data on particles of different sizes found in laundry wastewater indicates that they mainly accumulate in the upper layer, where particles with fiber lengths ranging from 0 to 1600 µm can be found. The average length of the fibers decreased with increasing depth. At a depth of approximately 10 cm, fibers with dimensions in the range of 0 to 100 μm were predominantly observed.

A study of asset and liability management applied to Brazilian pension funds

Asset and Liability Management (ALM) is a critical framework for pension funds, ensuring they have sufficient assets to meet future liabilities (pension payments) while managing investment risks effectively. This paper utilizes Brazilian data to develop an ALM model specifically for pension funds in the country. The model employs an optimization strategy that minimizes expected contributions made by individuals throughout their working lives. This optimization adheres to cash flow limitations and regulatory restrictions. The objective function leverages a min–max robust optimization approach based on a three-scenario planning scheme inspired by Brazil’s Interbank Rate. We incorporate a machine learning approach based on CMARS to predict confidence intervals for the key stochastic model parameters, particularly those related to the real returns of Brazilian investment classes. The findings empower pension fund managers to formulate well-informed investment strategies. We highlight allocation strategies that can reduce contribution rates without jeopardizing fund solvency, even for managers with a more aggressive risk profile favoring higher stock market allocations. Additionally, the study is enriched by an empirical analysis using data from a Brazilian pension fund, demonstrating the model’s practical application. In short, this model offers valuable insights that can benefit a wide range of pension funds in the Brazilian market, and it could also be applied to similar situations globally.