Global Parameters Research Articles

SCARF: Scalable Continual Learning Framework for Memory‐efficient Multiple Neural Radiance Fields

AbstractThis paper introduces a novel continual learning framework for synthesising novel views of multiple scenes, learning multiple 3D scenes incrementally, and updating the network parameters only with the training data of the upcoming new scene. We build on Neural Radiance Fields (NeRF), which uses multi‐layer perceptron to model the density and radiance field of a scene as the implicit function. While NeRF and its extensions have shown a powerful capability of rendering photo‐realistic novel views in a single 3D scene, managing these growing 3D NeRF assets efficiently is a new scientific problem. Very few works focus on the efficient representation or continuous learning capability of multiple scenes, which is crucial for the practical applications of NeRF. To achieve these goals, our key idea is to represent multiple scenes as the linear combination of a cross‐scene weight matrix and a set of scene‐specific weight matrices generated from a global parameter generator. Furthermore, we propose an uncertain surface knowledge distillation strategy to transfer the radiance field knowledge of previous scenes to the new model. Representing multiple 3D scenes with such weight matrices significantly reduces memory requirements. At the same time, the uncertain surface distillation strategy greatly overcomes the catastrophic forgetting problem and maintains the photo‐realistic rendering quality of previous scenes. Experiments show that the proposed approach achieves state‐of‐the‐art rendering quality of continual learning NeRF on NeRF‐Synthetic, LLFF, and TanksAndTemples datasets while preserving extra low storage cost.

The Impact of Different Revascularization Strategies Implemented in Acute Myocardial Infarction on the Recovery of Left Ventricular Functional and Deformational Parameters

Background: Despite well-established therapeutic techniques, such as direct revascularization through percutaneous coronary intervention (PCI), acute myocardial infarction (AMI) remains a leading cause of mortality and morbidity. Objectives: To determine if two-dimensional speckle tracking echocardiography (STE) deformation parameters and the early recovery of left ventricular (LV) functions are affected by the timing of PCI in AMI. Methods: A total of 200 cases with newly-onset acute myocardial infarction (AMI) who had a baseline left ventricular ejection fraction (LVEF) higher than 40% and received effective therapy with percutaneous coronary intervention (PCI) were included in this investigation. cases were categorized as either ST-elevation myocardial infarction (STEMI) or non-ST-elevation myocardial infarction (NSTEMI). cases were grouped into four groups according to the time between presentation and PCI. Using standard echocardiography and two-dimensional (2D) ST-elevation STE, individuals were re-evaluated three months later to find out if remodeling had taken place or if the LV function had returned. Results: Of the 200 AMI patients, including 140 males (70%), improvement in global longitudinal strain (GLS) and harmed longitudinal strain (HLS) were better in STEMI and NSTEMI patients received urgent revascularization with PCI (groups I and III) versus patients with pharmacoinvasive strategy or routine invasive strategy (Groups II and IV) (P < 0.05) while there was an insignificant difference between group I and III (P = 0.79). Of the 200 patients, 47 patients (23.5%) presented signs of LV remodeling at 3 months follow up. Age, smoking history, hypertension, dyslipidemia, Killip class, peak creatine phosphokinase - MB level, baseline left ventricular end diastolic volume (LVEDV), HLS, and harmed longitudinal strain rate (HLSR) were all factors that were found to be significantly associated with left ventricular remodeling (P<0.05) in the univariate logistic regression analysis. The following factors were identified as independent predictors of left ventricular remodeling in multivariate logistic regression analysis: damaged left ventricular ejection fraction (EF) and end-systolic volume, peak troponin I, Killip class, culprit left anterior descending (LAD), 2 and 3-vessel coronary artery disease (CAD), and wall motion score index (WMSI). Conclusion: Earlier PCI in AMI helps earlier improvement in myocardial strain parameters. HLS and HLSR are excellent predictors for LV remodeling and may do better than global parameters.

Investigations on mesh stiffness functions in three-dimensional spur and helical gear models. Definitions and numerical simulations

A definition of mesh stiffness as a scalar function connecting spur and helical three-dimensional pinions and gears is presented along with its conceptual limitations. Since it relies on global parameters namely, variations in torque and transmission errors, it can therefore be applied to the vast majority of the models found in the literature. In parallel, a multi-foundation (MF) model of mesh interface is introduced with the objective of being as accurate as three-dimensional finite element (FE) simulations for highly reduced computational costs. Numerous results on mesh stiffness and tooth contact conditions are presented for unmodified spur and helical gears. It is shown that the proposed mesh stiffness functions based on global parameters are sound and that the MF and FE results compare well, particularly when gear body deflections are limited. The contributions of off-line of action contacts, elastic couplings when several tooth pairs are loaded and axial deflections in helical gears are analysed. Finally, the notion of mesh stiffness function representative of the elasticity of a pinion-gear pair for static and dynamic conditions is examined.

Transition metal-modified armchair graphene network for high-performance hydrogen evolution reaction catalysts

This study explores the structural, electronic, and catalytic properties of armchair hexagonal graphene networks (AHGN) modified with single transition metal (TM) atoms from Period V. Substitutions of Ag, Mo, Nb, Pd, Rh, Ru, Tc, Y, and Zr were investigated, revealing significant changes in bond lengths, bond angles, and dihedral angles. The binding energies indicate that TM substitutions do not drastically destabilize AHGN, suggesting potential applications requiring modified electronic properties. Electronic investigations showed that TM substitutions influence the partial density of states (PDOS) and energy gaps (ΔE), with Tc significantly reducing ΔE, indicating a shift towards metallic behavior. Mulliken charge analysis highlighted the electron density redistribution around TM atoms and edge carbons, enhancing electronic conductivity and chemical reactivity. Based on the results, AHGN-Rh-H, AHGN-Pd-H, and AHGN-Mo-H demonstrate the most efficient catalytic performance for the hydrogen evolution reaction (HER), with ΔG values comparable to platinum, underscoring their potential for practical hydrogen production applications. Conversely, materials like AHGN-Nb-H and AHGN-Zr-H exhibit higher ΔG values, indicating lower efficiency for HER. Global reactivity parameters (GRPs) analysis revealed AHGN-Tc with the most negative chemical potential (−4.010 eV) and highest electronegativity (4.010 eV), indicating strong electron-accepting and electron-attracting abilities. These findings underscore the potential of TM-substituted AHGN for advanced electronic applications and efficient hydrogen production.

Design and optimization of a planar anti-buckling compliant rotational joint with a remote center of motion

Compliant mechanisms (CMs) exhibit some excellent mechanical properties and provide numerous innovative solutions for many existing mechanical applications. Among them, planar compliant rotational joints have made substantial contributions to precision engineering. To achieve high-precision positioning with a compliant rotational joint, it is essential to study characteristics such as anti-buckling and constant stiffness. The remote center of motion (RCM) mechanism, with its compact structure and ease of precise control, is expected to enhance overall rigidity and reduce parasitic displacements. Here, we propose a planar anti-buckling compliant rotational joint with a RCM. Static modeling and model validation are conducted for different geometric configurations, including single and combined structures. A distributed configuration with bidirectional anti-buckling properties is selected for optimization. Using a global parameter optimization model, single-objective optimization studies are conducted for three distinct characteristics. Subsequently, a multi-objective optimization model for constant stiffness and high precision is established. Based on the optimization results, a compliant rotational joint with bidirectional anti-buckling, constant rotational stiffness, and high precision is designed. Finally, the effectiveness of the optimization method is validated through physical experiments.

Computational multiphysics modeling of radioactive aerosol deposition in diverse human respiratory tract geometries

The evaluation of aerosol exposure relies on generic mathematical models that assume uniform particle deposition profiles over the human respiratory tract and do not account for subject-specific characteristics. Here we introduce a hybrid-automated computational workflow that generates personalized particle deposition profiles in 3D reconstructed human airways from computed tomography scans using Computational Fluid and Particle Dynamics simulations. This is the first large-scale study to consider realistic airways variability, where 380 lower and 40 upper human respiratory tract 3D geometries are reconstructed and parameterized. The data is clustered into nine groups using random forest regression. Computational fluid and particle dynamics simulations are conducted on these representative geometries using a realistic heavy-breathing respiratory cycle and radioactive iodine-131 as a source term. Monte Carlo radiation transport simulations are performed to obtain detailed energy deposition maps. Our findings emphasize the importance of personalized studies, as minor respiratory tract variations notably influence deposition patterns rather than global parameters of the lower airways, observing more than 30% variance in the mass deposition fraction.

Valley switch effect in an α-T3 lattice-based superconducting interferometer

Abstract Dirac electrons possess a valley degree of freedom, which is currently under investigation as a potential information carrier. We propose an approach to generate and manipulate the valley-switching current (VSC) through Andreev reflection using an interferometer-based superconductor hybrid junction. The interferometer comprises a ring-shaped structure formed by topological kink states in the α-T3 lattice via carefully designed electrostatic potentials. Our results demonstrate the feasibility of achieving a fully polarized VSC in this device without contamination from cotunneling electrons sharing the same valley as the incident electron. Furthermore, we show that control over the fully polarized VSC can be achieved by applying a nonlocal gate voltage or modifying the global parameter α. The former alters the dynamic phase of electrons while the latter provides an α-dependent Berry phase, both directly influencing quantum interference and thereby affecting performance in terms of generating and manipulating VSC, crucial for advancements in valleytronics.

Spectroscopic, quantum chemical and molecular docking studies of N-((anthracen-9-yl) methylene-2-methyl benzenamine): a potent probe to lipid bilayer systems

ABSTRACT A new synthesized Schiff base, N-((anthracen-9-yl) methylene-2-methyl benzenamine) (AMMB), was prepared from o-toluidine and 9-anthracenecarboxaldehyde. The structure of the compound was confirmed by single crystal X-ray diffraction and characterized through various analytical tools such as high resolution mass, 1H and 13C NMR, infrared, UV-vis and elemental composition analysis. The molecular geometries of AMMB were optimized by means of DFT/B3LYP/6311-G++ (d,p) basis set. The optimized geometric parameters of the compound were concordant with the single crystal structure. The optimized structure was utilized in comparison of experimental FT-IR with calculated frequency calculation. TD-DFT analysis was performed to compute the electronic absorption of the compound. SCF-GIAO was employed to compute 1H and 13C NMR, which was consistent with the experimental results. Additionally, NLO, NBO, MEP and global reactivity parameters were also computed using the same level of theory. Hirshfield surface analysis, fingerprint plot and energy frameworks were presented to explore the intermolecular interactions within the crystal. Molecular docking study was carried out to predict the probable binding site of AMMB into lipid bilayers such as DMPC, DPPC, POPC, DLPE, DOPC and POPE. The molecular docking analysis of AMMB showed complex formation with binding affinity energy ranging from −9.3 to −3.4 kcal/mol.

Normal reference of myocardial work during exercise stress echocardiography and the doubt about wasted work

Abstract Aims Myocardial work (MW) estimated based on pressure-strain loops is a noninvasive parameter for evaluating left ventricular function. The aims of this study were (1) to characterize the MW changes at rest and post-exercise in healthy adults and heart failure with preserved ejection fraction (HFpEF) patients, (2) to explore the related influencing factors for the increase of global wasted work (GWW) after exercise. Methods and results The study enrolled 167 healthy adults and 38 HFpEF patients. All subjects underwent comprehensive echocardiographic assessment at rest and immediately after a symptom-limited treadmill stress test. The MW changes and the impact of sex were analyzed. The related influencing factors for the increase of GWW after exercise were explored. Global work efficiency (GWE) was decreased and other global parameters were increased after exercise in normal adults. There was no significant difference of all global parameters between sexes at rest. GWE was higher in men after exercise (p<0.05).There was no significant difference in MW reserve parameters between sexes. Peak positive strain (PPS) significantly increased after exercise, while GWE reduced in normal adults and HFpEF patients (p<0.05). PPS was independently associated with GWW in normal adults and patients with HFpEF both at rest and after exercise (normal adults: r: 0.77, p<0.001 at rest, r: 0.72, p<0.001 after exercise; HFpEF patients: r: 0.74, p<0.001 at rest, r: 0.62, p<0.001 after exercise). Conclusion Global MW parameters were less affected by sex. PPS was independently associated with GWW in normal adults and patients with HFpEF and the work done due to myocardial elongation might not be calculated as wasted work during the isovolumic contraction phase.example of myocardial work and PPSThe relationship between PPS and GWW

Additive effect of metabolic dysfunction-associated fatty liver disease on left ventricular function and global strain in type 2 diabetes mellitus patients: a 3.0 T CMR feature tracking study

Abstract Purpose Type 2 diabetes mellitus (T2DM) represents the most prevalent form of diabetes, exerting a significant influence on cardiovascular health. Concurrently, metabolic dysfunction-associated fatty liver disease (MAFLD) is closely linked to heightened cardiac dysfunction risk. Our study aimed to explore the additive effect of MAFLD on left ventricular (LV) deformation among T2DM patients, utilizing cardiac magnetic resonance (CMR) feature tracking technology. Methods This study retrospectively included 270 patients with T2DM, comprising 110 individuals with MAFLD and 160 without, alongside 80 age- and sex-matched healthy controls, all of whom underwent CMR examination. Parameters derived from CMR encompass those related to LV function and global strain metrics. LV global strain parameters include global radial peak strain (GRPS), longitudinal peak strain (GLPS), and circumferential peak strain (GCPS), peak systolic strain rate (PSSR), and peak diastolic strain rate (PDSR), measured across radial, circumferential, and longitudinal directions. Intergroup analysis, employing the Mann-Whitney U test, was utilized to compare LV function and global strain parameters. Results The LV function parameters, including LV end-diastolic volume (LVEDV), LVEDV index, LV end-systolic volume (LVESV), LVESVI, LV mass, and LV mass index, displayed a progressive augmentation from controls through T2DM patients without MAFLD, to those with MAFLD. In parallel, LVEF showed a declining trajectory across these groups. In contrast, LVSV and LVSVI were comparable among the three groups. In a similar vein, when examining global strain parameters derived from CMR, a significant and progressive deterioration is observed across the groups. GRPS, GCPS and GLPS, along with PSSR and PDSR in radial, circumferential, and longitudinal directions, manifest a pronounced decline moving from control subjects to T2DM patients without MAFLD, and further deteriorating in those with T2DM and MAFLD (All p-values < 0.05). To assess the effect of MAFLD severity on global peak strain, patients with T2DM and MAFLD were stratified into two groups: a mild MAFLD group (N=77) and a moderate to severe MAFLD group (N=33). Although there was a noticeable decline in GRPS, GCPS and GLPS, as well as in PSSR and PDSR across the three groups—from those without MAFLD to those with mild and then moderate to severe MAFLD—the observed differences did not reach statistical significance. The absence of statistical significance is likely due to the small sample sizes of the groups categorized by severity of MAFLD. Conclusions This study revealed that MAFLD has additive worsening effects on LV function and LV global strains in T2DM patients evaluated by CMR. Besides, moderate to severe MAFLD, compared to mild MAFLD, exhibits worse global strain parameters. Early detection and intervention of MAFLD might improve the prognosis of T2DM patients.

Prevalence of stage B heart failure in healthy adults and people with type 2 diabetes

Abstract Introduction People with Type 2 Diabetes (T2D) are at increased risk of heart failure, and as such are classified as having Stage A Heart Failure (SAHF). Those with additional evidence of raised filling pressures, biochemical or structural cardiac changes, without heart failure symptoms, are deemed to have Stage B heart failure (SBHF). Identifying patients with SBHF may help determine those at highest risk of disease progression. Purpose The aim of this work was to assess the prevalence of SBHF in a cohort of asymptomatic healthy volunteers and people with T2D characterised according to current American Heart Association/American College Cardiology/Heart Failure Society of America. Methods A single-centre, prospectively recruited cohort of middle-aged asymptomatic adults with T2D and healthy volunteers, with no history or signs of cardiovascular disease, underwent comprehensive cardiac phenotyping with transthoracic echocardiography and circulating brain natriuretic peptide. Healthy volunteers with risk factors for heart failure, including hypertension and obesity, were excluded from analysis. Prevalence of SBHF was determined by comparing cardiovascular data to proposed standards, left ventricular ejection fraction and global longitudinal strain parameters were omitted from analysis due to data availability. Results We included 383 T2Ds (diabetes duration 9(5,15) years) and 65 healthy volunteers (Table 1); 91% of those with T2D and 65% of healthy volunteers met ≥1 criteria for SBHF (Table 2). Median number of SBHF criteria met in the T2D cohort was 3 (2,4); in particular, a large proportion of the cohort met defined cut offs for relative wall thickness (70.6%), lateral e’ (62.2%), septal e’ (54.1%) and LV wall thickness (47.4%). Of the 65 healthy volunteers, median number of SBHF criteria met was 1 (0,2.5). In healthy volunteers, SBHF was most commonly defined by lateral e’ (40.0%), septal e’ (38.3%), relative wall thickness (32.2%), left atrial volume indexed (22.4%) and serum brain natriuretic peptide (23.3%). Of note, brain natriuretic peptide levels met current SBHF parameters in 18.8% of healthy volunteers and 9.9% people with T2D, which may be attributable to the exclusion of obesity in the healthy volunteer group. Conclusion Using currently proposed standards, a high proportion of middle-aged asymptomatic people with T2D, and healthy volunteers without any risk factors for heart failure, would be categorised as having SBHF. These data strongly suggest that the majority of the proposed parameters for the definition of SBHF are not specific for a UK population and if applied will incorrectly classify many asymptomatic people at high risk of developing heart failure.

Design and damping characterization of sandwich composite made of particle-filled hollow spheres and steel sheets

Sandwich composites made of particle-filled hollow sphere structures (PHSS) and steel sheets offer excellent lightweight and damping properties, ideal for high-speed machine tool components under dynamic loads. Previous research has focused on single particle-filled hollow sphere (PHS) and small PHSS, leaving a gap understanding of PHSS/steel sandwich composites. In this study a test rig was developed, and Design of Experiments and Response Surface Analysis were used to investigate the effects of sheet and core thickness (design parameters), filling ratio, and particle size (particle parameters) on the damping performance of PHSS/steel sandwiches. The results indicate that the design parameters have a significant influence on damping performance. The interaction between design and particle parameters also substantially affects damping. Minimizing particle size, increasing filling ratio, thinning the face layer, and thickening the core layer significantly improve structural damping. To address manufacturing tolerances, a finite element (FE) model-based optimization was developed to accurately determine PHSS material parameters. These parameters were used in an FE model of the PHSS-steel composite, with identified contact parameters minimizing measurement and simulation differences. The homogenized material model and the linear model using global damping parameters accurately reproduce the dynamic properties of the PHSS-steel sandwich composite in low vibration modes.

A Hybrid Parametrization Method for B‐Spline Curve Interpolation via Supervised Learning

AbstractB‐spline curve interpolation is a fundamental algorithm in computer‐aided geometric design. Determining suitable parameters based on data points distribution has always been an important issue for high‐quality interpolation curves generation. Various parameterization methods have been proposed. However, there is no universally satisfactory method that is applicable to data points with diverse distributions. In this work, a hybrid parametrization method is proposed to overcome the problem. For a given set of data points, a classifier via supervised learning identifies an optimal local parameterization method based on the local geometric distribution of four adjacent data points, and the optimal local parameters are computed using the selected optimal local parameterization method for the four adjacent data points. Then a merging method is employed to calculate global parameters which align closely with the local parameters. Experiments demonstrate that the proposed hybrid parameterization method well adapts the different distributions of data points statistically. The proposed method has a flexible and scalable framework, which can includes current and potential new parameterization methods as its components.

Controlled generation of cylindrical vector vortex beams using an optically active material.

An efficient method for the generation of tunable cylindrical vector vortex beams is proposed and demonstrated experimentally using an optically active (OA) material. The uniqueness of the proposed methodology lies in the control over the tunability of the cylindrical vector vortex beams using different concentrations of the optically active material. The efficiency of the generated beams is enhanced by using a single low oblique incidence angle of the input beam on a spatial light modulator with a single-phase profile. Two global parameters are measured experimentally to show the quantitative tunability and efficiency of the generated beams. The proposed method can find applications in the fabrication of various kinds of spiral nanostructures.

Quasi-continuous exhaust operational space

Abstract The IPED predictive pedestal code has been used to determine the critical gradients for the onset of 1) separatrix ballooning modes and 2) global peeling-ballooning modes as a function of plasma shaping. This results in a scaling of the onset threshold of separatrix ballooning modes as a function of elongation and triangularity αedge,crit = 0.64κ2.2(1+δ)0.9, while the critical gradient for global peeling-balloonig modes increases as αedge,crit 1.5. This implies that operational space for a ballooning unstable separatrix and stable peeling-ballooning modes exists at sufficiently high shaping. Applying a collisional broadnening based scaling of the separatrix gradients allows the critical separatrix density, required to drive the separatrix ballooning mode, to be derived from global plasma parameters for any operational scenario on any device. Evaluations for ASDEX Upgrade, JET, and the ITER 15 MA baseline plasma predict critical separatrix densities of 0.3-0.4 nGW for QCE access, making the QCE an attractive operational scenario for fusion devices.

Selective Chromogenic Chemosensors for Arsenite Anion: A Facile Approach to Analyzing Arsenite in Honey, Milk, and Water Samples.

In this study, two chemosensors, N5R1 and N5R2, based on 5-(4-nitrophenyl)-2-furaldehyde, with varying electron-withdrawing groups, were synthesized and effectively employed for the colorimetric selective detection of arsenite anions in a DMSO/H2O solvent mixture (8 : 2, v/v). Chemosensors N5R1 and N5R2 exhibited a distinct color change upon binding with arsenite, accompanied by a spectral shift toward the near-infrared region (Δλmax exceeding 200 nm). These chemosensors established stability between a pH range 6-12. Among them, N5R2 displayed the lowest detection limit of 17.63 ppb with a high binding constant of 2.6163×105 M-1 for arsenite. The binding mechanism involved initial hydrogen bonding between the NH binding site and the arsenite anion, followed by deprotonation and an intramolecular charge transfer (ICT) mechanism. The mechanism was confirmed through UV and 1H NMR titrations, cyclic voltammetric studies, and theoretical calculations. The interactions between the sensor and arsenite anions were further analyzed using global reactivity parameters (GRPs). Practical applications were demonstrated through the utilization of test strips and molecular logic gates. Real water samples, honey, and milk samples were successfully analyzed by both chemosensors for the sensing of arsenite.

The Implications of Sacralized Transitional Vertebra on Spinal Alignment.

Retrospective study of a multicentric prospective database. This study aimed to determine, in a cohort of healthy volunteers, the impact of sacralized lumbo-sacral transitional vertebra (LSTV) on spinal alignment according to its grade, particularly regarding lumbar lordosis magnitude and distribution, and the implications for spinopelvic parameters measurement. There is little data regarding spinopelvic alignment assessment in LSTV patients. This study included healthy volunteers with full-body stereoradiographs in free-standing position aged over 18. Castellvi grade, pelvic parameters (measured on S1 and L5), L1-S1 lumbar lordosis (LL) and segmental lordosis for each disc and vertebral body, thoracic kyphosis, cervical lordosis, lower limb, and global alignment parameters were assessed. Castellvi I and II were considered as Low-grade and Castellvi III and IV as High-grade LSTV. Alignment parameters between No-LSTV, Low- and High-grade LSTV were compared. Propensity score matching was used to match PI in No-LSTV and Low-grades. Spinopelvic parameters measured on S1 in No-LSTV group and on L5 in High-grade were compared. 713 subjects were included, of whom 23 Low-grades and 27 High-grades. Mean pelvic incidence was 51.0±11.0° and mean age was 37.5±16.2 years. LL distribution was different between groups, with an apex and inflexion point significantly higher in High-grade (P<0.001). Kyphosis in the LSTV segment was compensated for by a steeper increase of LL above L5 in the High-grades. Low-grades and PI-matched No-LSTV presented similar alignment parameters. There were minor differences in parameters measured on S1 in No-LSTV and no L5 in High-grades. Subjects with low-grade LSTV present similar alignment as PI-matched No-LSTV subjects, and S1 should be taken as reference to measure spinopelvic parameters. High-grade LSTV subjects have kyphotic L5-S1 segment with more cranial lumbar apex and thoracolumbar inflexion point. In these subjects, spinopelvic parameters should be measured on L5.

Isothermal Flow Field Characterization of a Full-Scale Sector Combustor at Elevated Pressures

Abstract An experimental investigation in a sector (20 deg) of full-scale annular gas turbine combustor is performed. The sector combustor is optically accessible for the flow and flame visualization of the primary and exit zones of the combustor. The distinctive feature of the experimental setup is that it preserves the geometrical details of an annular combustor that includes the casing, dome and combustor liner. The combustor design features a series of primary and secondary dilution holes with multiple film cooling strips on the outer and inner liner. In the present study, the combustor is operated at inlet Mach numbers of 0.02–0.3 at operating absolute pressures of 1–5 bar. Static pressure measurements are performed at multiple locations in the rig to characterize the pressure drop across the combustor. Two-dimensional particle image velocimetry (PIV) is performed to measure the velocity fields of the primary and exit zones of the combustor simultaneously. The results show the presence of a central recirculation zone (CRZ), high-velocity annular jets, and a pair of dilution jets in the primary zone of the combustor. The steady-state flow structures are invariant of inlet Mach number and pressures. The relationship between the relative pressure drop across the combustor and the combustor inlet condition is obtained. Mass flowrate and momentum flux are calculated for the flow through the swirler, central recirculation zone, the primary dilution jets, and the exit zone. The paper shows how the flow structures in a realistic combustor change with variations in global combustor parameters.

Assessment of fetal cardiac function in pregnant women with anemia: prospective case-control study.

To compare fetal cardiac function in pregnant women with iron deficiency anemia (IDA) vs healthy pregnant controls. This was a single-center, prospective, case-control study conducted in a tertiary hospital between November 2022 and September 2023. Women diagnosed with IDA who attended as outpatients at the pregnancy follow-up clinic at 30-34 weeks' gestation or who were hospitalized for intravenous iron treatment owing to profound anemia were included. The control group consisted of randomly selected gestational-age-matched pregnant women with no obstetric complications or comorbidities and who did not have anemia. Patients underwent two-dimensional imaging, followed by pulsed-wave Doppler and M-mode and tissue Doppler imaging (TDI) to evaluate fetal cardiac function. A fetal cardiac score was calculated using systolic, diastolic and global hemodynamic function parameters, and was compared between patients with IDA and those without. The fetal cardiac score was also assessed according to the severity of anemia in the IDA group. A total of 150 patients, comprising 50 patients with IDA and 100 healthy pregnant women at 30-34 weeks' gestation, were included in the study. Of the patients with IDA, 20 had mild, 18 had moderate and 12 had severe anemia. The fetal myocardial performance index and isovolumetric relaxation time were significantly higher in the IDA group compared with the control group (P < 0.0001 for both), while isovolumetric contraction time was similar. Among the fetal tricuspid and mitral valve diastolic parameters, the E, A and E/A values were significantly lower in the IDA group (P < 0.05 for all). Mitral (MAPSE) and tricuspid (TAPSE) annular plane systolic excursions were significantly lower in the IDA group (P < 0.05 for both). The IDA group also had significantly lower values for the TDI parameters mitral and tricuspid E', A', S' and E'/A' ratio and a significantly higher E/E' ratio (P < 0.05 for all). Among the IDA subgroups, a significant decrease was observed in the tricuspid and mitral A, E and E/A ratio in fetuses whose mothers had severe anemia (P = 0.001). M-mode Doppler analysis revealed significantly lower fetal TAPSE and MAPSE in the patient group with severe maternal anemia (P = 0.001 for both). According to the subgroup comparison of TDI findings, the fetuses of mothers with severe anemia had significantly lower tricuspid and mitral E', A', S' and E'/A' ratio values and a significantly higher E/E' ratio (P < 0.05 for all). The fetal cardiac score was significantly higher in the maternal IDA group compared with the control group (P < 0.001). A significant negative correlation was found between maternal hemoglobin level and fetal cardiac score (P < 0.001). We observed differences in fetal systolic and diastolic cardiac function in pregnancies with maternal IDA. Fetal cardiac function was affected more among patients with severe anemia. This study found an increased E/E' ratio in the fetuses of pregnant women with IDA, suggesting decreased fetal heart maturation. Prenatal fetal cardiac evaluation, especially in women with severe anemia, can facilitate a more seamless transition to the postnatal period for these newborns. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Network efficiency of functional brain connectomes altered in type 2 diabetes patients with and without mild cognitive impairment

AimTo explore the topological organization alterations of functional connectomes in type 2 diabetes (T2DM) patients with and without mild cognitive impairment (MCI), and compare these with structural connectomes changes.MethodsTwenty-six T2DM patients with MCI (DM-MCI), 26 without cognitive impairment (DM-NC), and 28 healthy controls were included. Diffusion tensor imaging (DTI) and resting-state functional MRI images were acquired. Networks were constructed and graph-theory based network measurements were calculated. The global network parameters and nodal efficiencies were compared across the three groups using one-way ANOVA and a false-discovery rate correction was applied for multiple comparisons. Partial correlation analyses were performed to investigate relationships between network parameters, cognitive performance and clinical variables.ResultsIn the structural connectome, the DM-MCI group exhibited significantly decreased global efficiency (Eglob) and local efficiency (Eloc) compared to the DM-NC and control groups. In the functional connectome, the DM-MCI group exhibited increased Eloc and clustering coefficient (Cp) compared to the controls. No significant differences were found in Eglob, Eloc, or Cp between the DM-NC and the control group, both in structural and functional connectomes. Nodal efficiencies decreased in some brain regions of structural and functional networks in the DM-MCI and DM-NC groups, but increased in five regions in functional network, some of which were involved in the default-mode network.ConclusionUnlike the consistently decreased global properties and nodal efficiencies in the structural connectome of T2DM patients, increases in Eloc, Cp, and nodal efficiencies in the functional connectome may be viewed as a compensatory mechanism due to functional plasticity and reorganization. Altered nodal efficiency can hint at cognitive decrements at an early stage in T2DM patients.