Redistribution Of Flow Research Articles

Skeletal and respiratory muscle blood flow redistribution during submaximal exercise in pulmonary hypertensive rats.

Pulmonary hypertension (PH) is a chronic, progressive disease characterized by pulmonary vascular remodelling, dyspnoea and exercise intolerance. Key facets of dyspnoea and exercise intolerance include skeletal and respiratory muscle contractile and metabolic disturbances; however, muscle perfusion during exercise has not been investigated. We hypothesized that diaphragm blood flow ( ) would be increased and locomotory muscle would be decreased during submaximal treadmill running in PH rats compared to healthy controls. Female Sprague-Dawley rats were injected (i.p.) with monocrotaline to induce PH (n=16), or a vehicle control (n=15). Disease progression was monitored via echocardiography. When moderate disease severity was confirmed, maximal oxygen uptake ( ) tests were performed. Rats were given >24h to recover, and then fluorescent microspheres were infused during treadmill running (20m/min, 10% grade; ∼40-50% maximal speed attained during the test) to determine tissue . In PH rats compared with healthy controls, was lower (84 (7) vs. 67 (11) ml/min/kg; P<0.001), exercising diaphragm was 35% higher and soleus was 28% lower. Diaphragm was negatively correlated with soleus and in PH rats. Furthermore, there was regional redistribution in the diaphragm in PH compared to healthy rats, which may represent or underlie diaphragmatic weakness in PH. These findings suggest the presence of a pathological respiratory muscle blood flow steal phenomenon in PH and that this may contribute to the exercise intolerance reported in patients. KEY POINTS: Pulmonary hypertension (PH) impairs exercise tolerance, which is associated with skeletal and respiratory muscle dysfunction. Increased work of breathing in PH may augment diaphragm blood flow and lower locomotory muscle blood flow during exercise, hindering exercise tolerance. Our findings demonstrate that respiratory muscle blood flow is increased while the locomotory muscle is decreased in PH compared to healthy rats during exercise, suggesting that blood flow is preferentially redistributed to sustain ventilatory demand. Furthermore, blood flow is regionally redistributed within the diaphragm in PH, which may underlie diaphragm dysfunction. Greater respiratory muscle work at a given workload in PH commands higher respiratory muscle blood flow, impairing locomotory muscle oxygen delivery and compromising exercise tolerance, which may be improved by therapeutics which target the diaphragm vasculature.

Effects of 1267 nm Illumination on Microcirculation Regulatory Mechanisms.

This study explored the effects of 1267 nm laser irradiation on changes in blood flow parameters and activation of the regulatory mechanisms of the microcirculatory bed (MCB). Using laser Doppler flowmetry (LDF) technique and time-frequency analysis of perfusion signals, changes in the MCB of 16 healthy volunteers, targeting the distal phalanx of the third finger with 1267 nm laser irradiation were evaluated. Results indicated no significant differences in perfusion between control and target measurements, likely due to blood flow redistribution caused by vessel dilation/constriction. However, differences in oscillation amplitudes in endothelial and myogenic ranges were observed, suggesting microcirculation self-regulation. Detailed analysis revealed characteristic peaks in the endothelial range during and after irradiation, indicating endothelial mediator release. It is assumed that the identified effects may be related to the singlet oxygen generated by 1267 nm laser irradiation, which directly affects the MCB, manifesting as endothelium-dependent vascular activity.

Comparison of contrast-enhanced ultrasound imaging (CEUS) and super-resolution ultrasound (SRU) for the quantification of ischaemia flow redistribution: a theoretical study

The study of microcirculation can reveal important information related to pathology. Focusing on alterations that are represented by an obstruction of blood flow in microcirculatory regions may provide an insight into vascular biomarkers. The current in silico study assesses the capability of contrast enhanced ultrasound (CEUS) and super-resolution ultrasound imaging (SRU) flow-quantification to study occlusive actions in a microvascular bed, particularly the ability to characterise known and model induced flow behaviours. The aim is to investigate theoretical limits with the use of CEUS and SRU in order to propose realistic biomarker targets relevant for clinical diagnosis. Results from CEUS flow parameters display limitations congruent with prior investigations. Conventional resolution limits lead to signals dominated by large vessels, making discrimination of microvasculature specific signals difficult. Additionally, some occlusions lead to weakened parametric correlation against flow rate in the remainder of the network. Loss of correlation is dependent on the degree to which flow is redistributed, with comparatively minor redistribution correlating in accordance with ground truth measurements for change in mean transit time,dMTT(CEUS,R = 0.85; GT,R = 0.82) and change in peak intensity,dIp(CEUS,R = 0.87; GT,R = 0.96). Major redistributions, however, result in a loss of correlation, demonstrating that the effectiveness of time-intensity curve parameters is influenced by the site of occlusion. Conversely, results from SRU processing provides accurate depiction of the anatomy and dynamics present in the vascular bed, that extends to individual microvessels. Correspondence between model vessel structure displayed in SRU maps with the ground truth was>91%for cases of minor and major flow redistributions. In conclusion, SRU appears to be a highly promising technology in the quantification of subtle flow phenomena due ischaemia induced vascular flow redistribution.

Blood flow changes in the rabbit cranial and caudal venae cavae during postural loads after propranolol, bisoprolol and methyldopa pretreatment

To treat the hyperadrenergic form of postural orthostatic tachycardia syndrome, the β1,2-adrenergic receptor blocker propranolol, the β1-blocker bisoprolol and the central agonist of inhibitory presynaptic α2-adrenergic receptors, methyldopa, are used in clinical practice. There is no data in the literature concerning the effects of these drugs on venae cavae flows during postural tests. In acute experiments on anesthetized rabbits, we studied changes of cranial and caudal venae cavae flows during orthostatic (head up tilt by 25°) and antiorthostatic (head down tilt by −25°) tests for 20 s after preliminary pretreatment with propranolol, bisoprolol and methyldopa. Before administration of these drugs, in response to orthostasis at 4 and 20 s, a decrease of the cranial and caudal venae cavae flows was noted. During antiorthostasis, caudal venae cavae flow increased for 4 s, and by 20 s it decreased to the initial value; cranial venae cavae flow decreased by 4 s, and by 20 s it was greater than the initial one. After propranolol pretreatment, caudal venae cavae flow decreased to a greater extent compared with intravenous administration of bisoprolol and methyldopa. After methyldopa administration during orthostasis, by 20 s, the cranial venae cavae flow decreased more pronouncedly than in the caudal venae, while after propranolol and bisoprolol pretreatment under conditions of orthostasis, both cranial and caudal venae cavae flows decreased approximately to the same extent. During antiorthostasis by 20 s after pretreatment with propranolol caudal venae cavae flow increased more than cranial venae cavae flow. In case of pretreatment with bisoprolol and methyldopa, in response to antiorthostasis, cranial venae cavae flow increased not only to a greater extent than caudal venae cavae flow, but also more pronouncedly compared with its increase in rabbits initially. Thus, we concluded, that in case of postural loads after pretreatment with indicated above drugs, there are differences in the mechanisms of blood flows redistribution in the basins of the cranial and caudal venae cavae.

Interaction between hydrodynamic and morphodynamic processes at the confluence of pipe and channel

Confluences between a pipeline and a channel are commonly found in urban drainage networks. The mechanisms of sediment transport and the coherent structure within the confluence zone remain ambiguous. The hydro-morpho-sedimentary processes at pipe and channel confluences, which are influenced by discharge ratios, are investigated using a laboratory-scale confluence. The pipe current compresses and diverts downstream upon entering the main channel, creating a scour hole that carries sediment downstream. Coarser sediment deposits first, forming the slope of the downstream boundary of the scour hole (D50 = 60.31 μm) and the inner bar (D50 = 62.67 μm). Finer sediments are then deposited in the outer bar (D50 = 53.12 μm), resulting in a bed morphology consisting of the scour hole, outer and inner bars, and corridor. The penetration of the pipe current causes redistribution of the main channel flow, creating two shear layers. The height of the bar is directly related to the intensity of turbulence. Within the range of discharge ratios from 0.06 to 0.09, the shear layers and bars are displaced toward the outer bank by a distance of approximately one pipe diameter (0.05 m). Turbulence in this area is not isotropic, with power-law relations for streamwise and lateral velocity having an exponent of approximately −5/3. Conversely, the separation zone deviates from this pattern. Overall, this study highlights the significant influence of the bed morphology in modifying the flow structure compared to channel confluences and jets into crossflow, which are important in drainage engineering designs and fluvial studies.

The levels of oxidative stress markers in maternal and umbilical cord blood of pregnant women with diabetes mellitus in terms of blood flow redistribution in the fetal venous system

The levels of oxidative stress markers in maternal and umbilical cord blood of pregnant women with diabetes mellitus in terms of blood flow redistribution in the fetal venous system

One-year results from the REDUCER-I multi-center real-world clinical trial of the treatment of refractory angina with the coronary sinus Reducer

Abstract Background/Introduction Patients with refractory angina have chronic symptoms due to reversible ischemia which are inadequately controlled with optimal medical therapy or interventional treatments. These patients suffer from a poor quality of life and place a significant strain on the health care system due to their frequent rehospitalizations. The coronary sinus (CS) Reducer is a stainless-steel hour-glass shaped mesh stent that creates a focal narrowing in the lumen of the CS resulting in improved microvascular resistance and redistribution of myocardial blood flow. Purpose The COSIRA randomized controlled trial showed the Reducer is a safe and effective treatment for refractory angina with patients having significant improvements in Canadian Cardiovascular Society (CCS) class and other measures of quality of life. The REDUCER-I post-market study evaluated the long-term outcomes with the Reducer in a large and challenging ‘real-world’ cohort. Methods REDUCER-I is a multicenter, non-randomized study conducted across 26 medical centers in Europe. At one year, device effectiveness was assessed by improvement in CCS grade as compared to baseline and device safety was assessed by Major Adverse Cardiac Events (MACE). Secondary endpoints included six-minute walk tests, EQ-5D-5L tests, and Seattle Angina Questionnaires (SAQ). Subjects were followed at 30 days, 6 months, and annually through five years. Results The as-treated population includes a total of 371 patients who received a Reducer implant (78.7% (292/371) male, 47.2% (175/371) diabetic, 73.9% (274/371) post-revascularization). The one-year Kaplan-Meier overall MACE rate post-implant was 7.1% (95% CI [4.9, 10.4]). There were nine deaths within the first 365 days, one death was due to unknown causes and eight deaths were adjudicated to as not being device- or procedure-related. At 12 months, 70.0% (205/293) of patients improved by ≥1 CCS class. At baseline, 72.2% (232/363) of patients were CCS class III/IV and this proportion decreased to 18.1% (54/298) at 12 months (P&amp;lt;0.0001). The patients’ baseline six-minute walk distance was 327.5±116.1m which improved by a mean of 30.8±81.8m at 12 months (p&amp;lt;.0001). In the year prior to Reducer implant, 33.3% (88/264) of the patients had at least one visit to the emergency department compared to 11.7% (31/264) in the year after Reducer implant (p&amp;lt;.0001). The significant improvements in CCS class and SAQ-QoL were sustained through 3 years (Figure). Conclusion In this 12-month analysis of the REDUCER-I study, patients with refractory angina treated with the CS Reducer had low MACE rates and showed significant and sustained improvements in angina, QoL, functional capacity, and need for rehospitalization.

РОЛЬ МІЖНАРОДНИХ ТРАНСПОРТНИХ КОРИДОРОВ У ПРОЦЕСІ ІНТЕГРАЦІЇ АЗЕРБАЙДЖАНУ У СВІТОВУ ЕКОНОМІКУ

The article discusses the concept, purposes of creation and general characteristics of international transport corridors. The authors provide a brief description of the prerequisites for the formation and development of international transport corridors, and also consider the contribution of international transport corridors to the development of the national economy of the state-participants of the transport system from the point of view of micro- and macroeconomic indicators. The purpose of the article is to analyze the role of international transport corridors in the process of integration of Azerbaijan into the world economy. The object of the research is logistic principles of international transport corridors in the process of integration of Azerbaijan into the world economy. The methods used in the research. Here are used methods of categorical analysis and synthesis to study theoretical approaches to determining the essence and features of omnichannel loyalty programs. In addition, the description of the transformation of loyalty programs required the use of the observation method to display market trends and vectors of their influence on the specified process, as well as specification - to highlight and characterize relevant digital tools. Research hypothesis. The construction of new international transport corridors in the process of integration of Azerbaijan into the world economy will be a guarantee of the development of this region and its economic opportunities. Presenting main material. The conclusions contained in this article on the importance of international transport corridors for the economy of the state can be used in the future to assess the need to develop transport and logistics infrastructure within the framework of already functioning international transport corridors, to determine new strategic directions for the formation of new international transport corridors in the context of changing macroeconomic prerequisites and redistribution of traffic flows, including due to the introduction of sanctions, as well as to assess the prospects for the formation of new transport corridors. The originality and practical significance of the research. International transport corridors (ITC) in the context of global integration processes and the global division of labor are one of the most important factors in the development of the world economy. International transport corridors ensure the creation and functioning of stable transport links between various foreign participants in international economic relations. Conclusions and perspectives of further research. Of course, it is difficult to deny the importance of international transport corridors for the development of the global economy. At the same time, scientific interest arises in relation to what prerequisites lie behind the formation of international transport corridors and what contribution they make to the development of national economies of states through whose territory the national part of international transport corridors passes.

Organic-Inorganic Dual-Network Composite Separators for Lithium Metal Batteries.

The suboptimal ionic conductivity of commercial polyolefin separators exacerbates uncontrolled lithium dendrite formation, deteriorating lithium metal battery performance and posing safety hazards. To address this challenge, a novel organic-inorganic composite separator designed is prepared to enhance ion transport and effectively suppress dendrite growth. This separator features a thermally stable, highly porous poly(m-phenylene isophthalamide) (PMIA) electrospun membrane, coated with ultralong hydroxyapatite (HAP) nanowires that promote "ion flow redistribution." The synergistic effects of the nitrogen atoms in PMIA and the hydroxyl groups in HAP hinder anion transport while facilitating efficient Li+ conduction. Meanwhile, the optimized unilateral pore structure ensures uniform ion transport. These results show that the 19µm-thick HAP/PMIA composite separator achieves remarkable ionic conductivity (0.68mS cm-1) and a high lithium-ion transference number (0.51). Lithium symmetric cells using HAP/PMIA separators exhibit a lifespan exceeding 1000h with low polarization, significantly outperforming commercial polypropylene separators. Furthermore, this separator enables LiFePO4||Li cells to achieve an enhanced retention of 97.3% after 200 cycles at 1C and demonstrates impressive rate capability with a discharge capacity of 72.7mAh g-1 at 15C.

SPECIFICS OF THE EU DEVELOPMENT POLICY

The article deals with the current stage of EU development policy. The evolution of the EU aid system is retrospectively analyzed. Attention is also paid to the key EU documents wherein the principles of current development policy are set forth. The background the EU is delivering its aid against is outlined. It involves political and economic crises, competition with the «rising» donors, including China, discussions on strategic autonomy, rise of the far-right parties. The pivotal changes in EU development policy are investigated, which are a new financial instrument, geographical redistribution of ODA flows, introduction of the Team Europe and Global Gateway initiatives, substantive change to the EU normative power concept. EU development policy is revealed to be increasingly acquiring a tactical character, with the focus having shifted onto the neighborhood and EU mainstream issues. Aspiration to make the aid system more flexible to rapidly respond to crises is noted as well.

A novel concept for performance enhancement of immersion-cooled data center servers

Efficient thermal management of highly densified data centers is important for carbon-neutral strategies. To this end, this work experimentally explored the most promising single-phase immersion cooling (SPIC) systems. Moreover, it proposed an active performance enhancement technology for SPIC systems. The results indicate that increasing the coolant immersion height helps to improve the SPIC performance, and the resulting increase in flow resistance is negligible. Increasing the volume flow rate improves heat transfer performance while also increasing flow resistance. Moreover, there exists a critical volume flow rate (i.e., 8 L/min) beyond which fails to significantly enhance the SPIC performance. The cooling water temperature is positively correlated with the device temperature but negatively correlated with flow resistance. The micropump-based flow turbulence enhancement and the fan-based flow redistribution techniques reduce the maximum CPU surface temperature by 6.1 % and 5.0 %, respectively. Compared to the micropump method, the fan-based technique degrades the thermal uniformity of coolants but does not significantly increase flow resistance. The economic benefit of the micropump-based strategy is greater for upstream CPUs than downstream CPUs, while the fan-based method is more economically advantageous for downstream CPUs. Moreover, the micropump-based strategy outperforms the fan-based method and demonstrates a 21.39 % increase in energy-economic performance.

Measuring mobility resilience with network-based simulations of flow dynamics under extreme events

Extreme events disrupt routine mobility patterns and affect citizens’ daily lives. Current disaster resilience measurements often rely on static proxies or topological analyses, failing to capture the dynamic interactions between functional organization and transportation systems, as well as critical regime shifts within the resilience process. Using big data sourced from mobile-devices, this study delineates the evolving nature of various response flows during disasters with different intensities, depicts curves illustrating shifts in maintained traffic flow proportion, maps mobility resilience heterogeneity, and examines the spatial ramifications of flow redistribution. Our findings revealed that even minor incidents prompt city-wide flow reorganization. Clusters of low resilience with gradients are caused by mobility structures rather than distance from the disaster. Arterial roads uphold connectivity for long-distance journeys, whereas branch roads facilitate shorter trips but remain vulnerable to traffic surges. Based on these findings, strategies for preparedness and emergency planning under road failure conditions are evidence-based.

Assessment of a body force modeling approach to examine the aerodynamics of high bypass ratio fan stages

The primary focus of modern civil jet engine intake design is to enhance propulsive efficiency through an increase in the bypass ratio of the turbofan engine, which requires an enlargement in fan diameter. However, this enlargement results in increased weight and drag due to the need for a larger nacelle to surround the fan. To mitigate these issues, efforts are being made to shorten the axial length of the aircraft engine intakes. Nonetheless, this reduction leads to more vulnerable fan aerodynamics since the diffusion within the intake must occur over a shorter distance, causing a higher possibility of flow separation. Common intake design methods employ throughflow nacelle models that do not consider the aerodynamic effects of the fan, including blockage, mass flow redistribution, and suction. The utilization of a full annulus domain numerical setup, which is necessary to capture inlet distortions, demands excessive computational resources particularly during the design phase. As a result, reduced order models, such as the body force model, can be utilized to simulate fan intake aerodynamics. This paper will assess the body force model and its abilities by comparing conventional bladed single passage simulations with the body force approach.

Impact of Lean-Burn Combustor Flow on Nozzle Guide Vane Performance

Abstract In this paper we investigate the impact of lean-burn-representative swirl and temperature distortion on the aerothermal performance of fully-cooled high-pressure nozzle guide vanes (NGVs) from a modern aero-engine. Experiments were carried out in the Engine Component AeroThermal (ECAT) facility at the University of Oxford. This is a fully-annular warm-flow engine parts facility, designed to operate at engine-representative conditions of Reynolds and Mach number. Inlet profiles of swirl, turbulence, and non-dimensional total temperature were generated using a non-reacting combustor simulator. The NGV outlet flow was experimentally characterized at three downstream planes in experiments with and without lean-burn-representative inlet conditions. Area-survey measurements included distributions of whirl angle, kinetic energy (KE) loss, and non-dimensional total temperature. Experimental data is compared to computational fluid dynamics (CFD) simulations. Fully-featured NGV geometry (including film cooling holes and internal passages) was used, to account for internal cooling flow redistribution resulting from altered external loading. We show that lean-burn inlet conditions result in significant surface flow redistribution, relatively high levels of residual swirl in the downstream flow, and a small increase of integrated KE loss.

Flow in fracture Intersections: Deflection flow assumption reexamined

Deflection flow, which represents the process of flow redistribution at fracture intersections, is essential for accurately predicting fluid infiltration and contaminant transport in fracture networks. However, previous studies focused on the outcome of flow redistribution but neglected the process, leading to poor knowledge of deflection flow at intersections. In this study, numerical investigations of the deflection flow in cross fractures were carried out based on Navier-Stokes equations and the results were compared with previous experiments. Geometrical characteristics such as angle(φ), aperture ratio(k), and hydraulic characteristics like inlet flow ratio(n) were considered to explore the mechanism of deflection flow. The deflection flow intensity(Xφ) was introduced to characterize the magnitude and direction of the deflection flow. The results showed that the deflection flow is caused by unequal local head loss. The effect of φ on Xφ is limited by n and k. Increasing n or k enhances the deflection flow but the directions of the induced deflection flow are reversed. The obtained relationship was further supported by theoretical results derived from the cubic law. Subsequently, sensitivity analysis of impact factors to the deflection flow was carried out by the Morris method, the sensitivity in descending order was k, n, φ. Finally, based on the analysis of Xφ, the conditions to limit the occurrence of deflection flow was obtained as a linear positive correlation between the critical inlet flow ratio(nc) and aperture ratio(k). The results from this study may provide insights and physical constraints on construction of flow models based on discrete fracture networks.

Physiological effects and safety of bed verticalization in patients with acute respiratory distress syndrome

BackgroundTrunk inclination in patients with Acute Respiratory Distress Syndrome (ARDS) in the supine position has gained scientific interest due to its effects on respiratory physiology, including mechanics, oxygenation, ventilation distribution, and efficiency. Changing from flat supine to semi-recumbent increases driving pressure due to decreased respiratory system compliance. Positional adjustments also deteriorate ventilatory efficiency for CO2 removal, particularly in COVID-19-associated ARDS (C-ARDS), indicating likely lung parenchyma overdistension. Tilting the trunk reduces chest wall compliance and, to a lesser extent, lung compliance and transpulmonary driving pressure, with significant hemodynamic and gas exchange implications.MethodsA prospective, pilot physiological study was conducted on early ARDS patients in two ICUs at CHU Clermont-Ferrand, France. The protocol involved 30-min step gradual verticalization from a 30° semi-seated position (baseline) to different levels of inclination (0°, 30°, 60°, and 90°), before returning to the baseline position. Measurements included tidal volume, positive end-expiratory pressure (PEEP), esophageal pressures, and pulmonary artery catheter data. The primary endpoint was the variation in transpulmonary driving pressure through the verticalization procedure.ResultsFrom May 2020 through January 2021, 30 patients were included. Transpulmonary driving pressure increased slightly from baseline (median and interquartile range [IQR], 9 [5–11] cmH2O) to the 90° position (10 [7–14] cmH2O; P < 10–2 for the overall effect of position in mixed model). End-expiratory lung volume increased with verticalization, in parallel to decreases in alveolar strain and increased arterial oxygenation. Verticalization was associated with decreased cardiac output and stroke volume, and increased norepinephrine doses and serum lactate levels, prompting interruption of the procedure in two patients. There were no other adverse events such as falls or equipment accidental removals.ConclusionsVerticalization to 90° is feasible in ARDS patients, improving EELV and oxygenation up to 30°, likely due to alveolar recruitment and blood flow redistribution. However, there is a risk of overdistension and hemodynamic instability beyond 30°, necessitating individualized bed angles based on clinical situations.Trial registration ClinicalTrials.gov registration number NCT04371016, April 24, 2020.

The role of umbilical-portal venous hemodynamics in fetal macrosomia pathogenesis in pregnancy complicated by diabetes mellitus

BACKGROUND: During pregnancy complicated by diabetes mellitus, the risks of developing fetal macrosomia and other perinatal complications increase. Redistribution of blood flow in the fetal umbilical-portal venous system may be an important but poorly understood compensatory mechanism that affects macrosomic fetal growth. AIM: The aim of this study was to determine the features of the fetal umbilical-portal venous hemodynamics in pregnant women with various types of diabetes mellitus and the absence of carbohydrate metabolism disorders, taking into account the gestational age and the macrosomic fetal growth. MATERIALS AND METHODS: In this prospective cohort study, 86 pregnant women with pregestational diabetes mellitus, 44 pregnant women with gestational diabetes mellitus and 58 patients without carbohydrate metabolism disorders underwent ultrasound examinations from 30+0 to 41+3 weeks of gestation. During ultrasound, we performed Doppler assessment of venous hemodynamic parameters in the vessels of the umbilical-portal venous system, with volumetric blood flow calculated for each vessel. Additionally, the total liver volumetric blood flow and ductus venosus shunt fraction were calculated. RESULTS: The presence of fetal macrosomia in patients from the pregestational diabetes mellitus group is associated with an increase in the volumetric blood flow of the umbilical vein by 89.5 ml/min (p = 0.003) and the left portal vein by 33.3 ml/min (p = 0.008), as well as the total volumetric blood flow of the fetal liver by 95.7 ml/min (p = 0.001) compared with normal-weight fetuses. At the same time, the ductus venosus shunt fraction decreased in macrosomic fetuses by 3.83% (p = 0.001). In the gestational diabetes mellitus and control groups, despite the tendency for these parameters to increase in fetuses with macrosomia, the differences did not reach statistical significance. With a left portal vein volume flow threshold of 94.51 ml/min, the sensitivity and specificity for predicting large births were 84.46 and 72.09%, respectively. CONCLUSIONS: Pregestational diabetes mellitus in the mother is associated with a priority redistribution of blood flow to the fetal liver and is accompanied by a decrease in the ductus venosus shunt fraction. The severity of these hemodynamic changes increases in the presence of fetal macrosomia, which confirms the role of liver perfusion in the regulation of fetal growth in uncomplicated pregnancy and maternal diabetes mellitus.

Study on the smoke mass flow in T-shaped tunnel fire

Smoke mass flow rate (SMFR) is an important factor for smoke control in tunnel fire. The presence of bifurcation structure can lead to the flow redistribution and distinctive characteristics. In the current study, a relational expression for the SMFR in branched tunnel was theoretically derived. A series of numerical simulations with Fire Dynamics Simulator(FDS) were conducted to investigate the effects of multiple factors on the smoke mass flow and validate the predictions. The results indicated that for a T-shaped tunnel, the amount of smoke flowing into the branch is mainly depends on the thickness and temperature of the incoming smoke flow from mainline, affecting by heat release rate(HRR) and tunnel section size, while the influence of the bifurcation angle and longitudinal position of fire source is unremarkable. Fairly good agreement was achieved between the predictions and simulation results. This research can be instrumental in estimating the SMFR in T-shaped tunnel fire scenarios and offer valuable insights for smoke management strategies.

Territory-Related Functional Connectivity Changes Associated with Verbal Memory Decline in Patients with Unilateral Asymptomatic Internal Carotid Stenosis.

Verbal memory decline is a common complaint of patients with severe asymptomatic stenosis of the internal carotid artery (aICS). Previous publications explored the associations between verbal memory decline and altered functional connectivity (FC) after aICS. Patients with severe aICS may show reduced perfusion in the ipsilateral territory and redistribution of cerebral blood flow to compensate for the deficient regions, including expansion of the posterior and contralateral ICA territories via the circle of Willis. However, aICS-related FC changes in anterior and posterior territories and the impact of the sides of stenosis were less explored. This study aims to investigate the altered FC in anterior and posterior circulation territories of patients with left or right unilateral aICS and its association with verbal memory decline. We enrolled 15 healthy controls (HCs), 22 patients with left aICS (aICSL), and 33 patients with right aICS (aICSR) to receive fMRI, Mini-Mental State Examination (MMSE), the Digit Span Test (DST), and the 12-item Chinese version of Verbal Learning Tests. We selected brain regions associated with verbal memory within anterior and posterior circulation territories. Territory-related FC alterations and verbal memory decline were identified by comparing the aICSL and aICSR groups with HC groups (P < .05, corrected for multiple comparisons), respectively. Furthermore, the association between altered FC and verbal memory decline was tested with the Pearson correlation analysis. Compared with HCs, patients with aICSL or aICSR had significant impairment in delayed recall of verbal memory. Decline in delayed recall of verbal memory was significantly associated with altered FC between the right cerebellum and right middle temporal pole in the posterior circulation territory (r = 0.40, P = .03) in the aICSR group and was significantly associated with altered FC between the right superior medial frontal gyrus and left lingual gyrus in the anterior circulation territory (r = 0.56, P = .01) in the aICSL group. Patients with aICSL and aICSR showed different patterns of FC alterations in both anterior and posterior circulation territories, which suggests that the side of aICS influences the compensatory mechanism for decline in delayed recall of verbal memory.

UPDATED MATHEMATICAL MODEL OF THE TRUNK PIPELINE SECTION WITH LOOPING IN CASE OF LEAKAGE

Pipeline transport is the main method of moving volumes of oil and oil products, as it has several advantages, for example, quality safety and high throughput. At the same time, it also has some disadvantages, which can include the difficulty of increasing throughput without high capital investments and possible leaks and unauthorized tie-ins into pipelines, which are sometimes difficult to identify. Looping is one of the main ways to increase the throughput of the existing pipeline system, when the need to increase the volume of oil and oil products supplies requires the construction of several parallel pipelines — looping. At the same time, the basic mathematical model for calculating the section of the trunk oil pipeline with looping does not fully cover all the physical processes associated with the distribution of flows in the parallel section, which arise due to turbulences in the connection nodes, as well as head loss along the length of the jumpers. Taking into account the resulting flow redistributions, it becomes difficult to detect a potential leak, since any of the detection methods can not solve the problem with high accuracy with determining the leak coordinate with an unknown distribution of fluid flow rates in a parallel section. As part of the study, an updated mathematical model of the oil export pipeline section with looping was developed, which took into account the presence of a potential leak in the parallel section. Mathematical modeling was carried out on the basis of the assumption of a known coordinate, the effect of leakage on the redistribution of flows in a parallel section was estimated. To assess the impact of the leak, various coordinates and volumetric flow rates were set, based on the calculation results, graphs of the flow rate in looping versus its length and internal diameter were plotted. The study is the initial phase of developing a hydraulic location leak detection system for the oil export pipeline section with looping. The need to refine the mathematical model for determining the flow rate in the parallel section is an urgent and necessary task, the solution of which will allow identifying potential leaks with reliable accuracy.