Reduction In Cross-sectional Area Research Articles

Nasal Patency Across Seated, Supine, and Recumbent Postures in Individuals With and Without Allergic Rhinitis.

Objectives: This study aimed to investigate the effects of seated, supine, and recumbent postures on nasal resistance in individuals with allergic rhinitis (AR) and healthy controls, which has not been investigated in the past. Methods: A visual analog scale (VAS) assessed subjective nasal obstruction, while acoustic rhinometry and video endoscopy provided objective measures. Sixty participants, comprising 30 AR patients and 30 healthy controls, were evaluated across 4 postures without decongestion: seated, supine, left recumbent, and right recumbent. Results: In patients with AR, we noted no significant changes in subjective nasal blockage under various postures (all P > .18). However, significant reductions of minimal cross-sectional area (mCSA) were found (seated vs supine, P = .014; seated vs left recumbent, P = .001; seated vs right recumbent, P < .001) and significant increases in the inferior turbinate hypertrophy were observed on the dependent side of the nose when in recumbent posture (right nose: seated vs right recumbent, P = .013; left nose: seated vs left recumbent, P = .003). On the contrary, healthy controls experienced increased subjective nasal obstruction (VAS scores: seated vs supine, P < .001; seated vs left recumbent, P = .003; seated vs right recumbent, P < .001), reductions in mCSA (seated vs supine, P = .002; seated vs right or left recumbent, both P = .001), and increased inferior turbinate hypertrophy on the dependent side of the nose (right nose: seated vs right recumbent, P = .003; left nose: seated vs left recumbent, P = .006). Conclusions: Healthy controls reported better nasal patency when shifting from supine or recumbent to more upright or less gravity-dependent seated postures, which was further supported by objective examinations. On the contrary, despite patients with AR not subjectively perceiving increased nasal patency while adopting more upright postures, objective evaluations demonstrated an improvement in their nasal airflow in these less gravity-dependent postures.Level of Evidence: 4.

Single Cell Profiling Reveals Unique Contributions of Senescent Macrophages across Musculoskeletal Tissues in Posttraumatic Osteoarthritis

Injury to the acute cruciate ligament (ACL) disrupts musculoskeletal tissue architecture and function, leading to atrophy and weakness associated with the development of posttraumatic osteoarthritis (PTOA). The objective of this study was to profile senescent cell burden across skeletal muscle and knee joint capsule compartments and to ascertain the effectiveness of senolytic treatment in mitigation of PTOA. Given the unique features of these tissues, we hypothesized that composition and physiological consequence of senescent cell burden would differ among muscle and joint capsule, and senolytic treatment would prevent cartilage degradation and improve muscle function. We employed a surgical ACL transection model (ACLT) and performed scRNAseq analysis on the quadriceps and joint capsule 14-days post-injury and discerned senescent status by SPiDER-βGal. We also examined the influence of senescent cells on neighboring populations in vitro. We investigated whether senolytic treatment (dasatinib and quercetin; D+Q) improves muscle and joint health 28-d post-injury. scRNAseq revealed that macrophages (MΦ) accounted for 83% of senescent cells in the quadriceps and 48% in the joint capsule. Senescent MΦ exhibited an alternatively activated phenotype (M2) . Gene ontology enrichment analysis in the quadriceps showed downregulation of positive regulation of muscle cell differentiation, and upregulation of secretory granule lumen; in the joint capsule, it revealed upregulation of glycosaminoglycan catabolic process and regulation of ossification. In vitro, we found that mesenchymal progenitors incubated with senescent MΦ conditioned media exhibited upregulation of senescence associated secretory phenotype (SASP) genes and extracellular matrix organization-related genes ( i.e.Col1a1 and Lox). We found upregulation of protein glycosylation and downregulation of chondroitin sulfate proteoglycan biosynthetic process pathways. PTOA mice exhibited significant reductions in quadriceps myofiber cross-sectional area, increased accumulation of M2-like Cd163+ MΦ, and increased fibrosis, which were blunted in D+Q-treated mice. D+Q-treated PTOA mice exhibited a trend of improved peak torque compared to vehicle-treated PTOA mice. Histochemical assessment of whole knee joints revealed compromised articular cartilage and moderate to severe PTOA in vehicle-treated mice, which was blunted in D+Q-treated mice. These findings reveal distinct transcriptional profiles of senescent macrophages isolated from unique musculoskeletal tissues, providing critical insight into the heterogeneity of senescent cell programming following traumatic injury. Further, we show that accumulation of senescent alternatively-activated MΦ likely contributes to musculoskeletal dysfunction and development of PTOA, and that senolytics may improve functional recovery. AR072061. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Daily use of veno-constrictive thigh cuffs during 30 days of strict 6° head-down tilt bedrest to reverse the headward fluid shift

Introduction: Chronic exposure to weightlessness induces a persistent headward fluid shift, which may contribute to the development of Spaceflight Associated Neuro-ocular Syndrome (SANS). Strict 6° head-down tilt bedrest (HDTBR) is a spaceflight analog that induces a headward fluid shift and development of SANS findings, enabling the evaluation of potential countermeasures. Lower body exercise can induce a sustained post-exercise hyperemia thereby shifting blood away from the central circulation. In addition, veno-constrictive thigh cuffs (VTC) can sequester blood volume in the legs. The purpose of this study was to determine whether 6 hours of daily VTC use following cycling exercise (Ex+VTC) could reverse the headward fluid shift during 30 days of strict 6° HDTBR. We hypothesized that Ex+VTC would sequester fluid in the legs leading to increased thigh circumference and reduced stroke volume (SV), cardiac output (CO), internal jugular vein (IJV) cross-sectional area (CSA) and pressure, and intraocular pressure (IOP). Methods: Participants were randomly assigned to a Control (n=12, 6 female) or Ex+VTC (n=12, 4 female) group and completed baseline data collection (BDC) in the seated and supine posture followed by 30 days of strict 6° HDTBR. The Ex+VTC group completed a maximal exercise test on a cycle ergometer in 6° HDT posture during BDC to establish work rates during HDTBR. The Ex+VTC group performed 10 minutes of light cycle exercise, cycled for 45 minutes at 45% of their max wattage, and then donned VTC to ~50 mmHg for 6 hours on 6 of 7 days per week during HDTBR. Data were collected before exercise and 30 minutes and 6 hours after exercise and donning VTCs on days 3, 17, and 29 of HDTBR. Controls were studied at similar time points. Days were nested within the models. Mixed models were used to determine differences between groups in the change in thigh circumference measured using a flexible tape measure, bilateral IOP measured using tonometry, CO measured using the inert gas rebreathe technique (Innocor), and ultrasound of bilateral IJV CSA and pressure from before to 30 min and 6 hours after use of the countermeasure. Left and right IJV and IOP data were nested within each participant. Results: The Ex+VTC group completed all exercise sessions followed by 6 hours of VTC use. Compared to Control, thigh circumference was greater after 30 minutes (+1.3 vs. -0.2 cm, p&lt;0.001) and 6 hours of VTC use (+2.5 cm vs. -0.1 cm in controls, p&lt;0.001). SV (-38 vs. 2 ml, p&lt;0.001) and CO (-1.5 vs. 0.3 L/min, p&lt;0.001) were reduced at 30 minutes and 6 hours of VTC use (SV: -30 vs. 5 ml, p&lt;0.001; CO: -1.1 vs. 0.6 L/min, p&lt;0.001) compared to Control. IJV CSA and pressure were reduced at 30 minutes (CSA, p&lt;0.001; pressure, p=0.001) and 6 hours of VTC use (CSA, p&lt;0.001; pressure, p=0.007). IOP was not different compared to Control. Conclusions:Use of VTC for 6 hours after 45 minutes of exercise successfully sequestered fluid in the legs, leading to a reduction in central blood volume, IJV CSA, and IJV pressure. Thus, an Ex+VTC countermeasure resulted in a partial fluid shift reversal. This research was supported by the NASA Human Research Program. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Temporal change in channel form and hydraulic behaviour of a tropical river due to natural forcing and anthropogenic interventions

ABSTRACT Assessing the degradation of river channels is crucial in the Anthropocene era, particularly in the deltaic areas worldwide. The present study aims to investigate the degradation of the Mathabhanga-Churni River giving emphasis on the temporal change of channel morphology and hydraulic behaviour and comparing the current situation with the historical past based on planform morphology and meander geometry of 118 meander loops, and width, depth, cross-sectional area, and hydraulic behaviour (velocity, discharge, stream power) at 47 cross-sections. The absence of lateral dynamicity, the static character of channel sinuosity during the last century (1913–2018), and the constant meander morphology reflects the static meander geometry and degradation of the river. The reduction of average channel width, depth, and cross-sectional area supports the falling trend of channel forms. Findings on hydraulic behaviour indicate declining discharge (~50% reduction during 1915–2018) that induces the present-day downscaled velocity and lowered stream power. Neotectonics (eastward tilting of the Bengal delta) and anthropogenic stressors such as stream crossings, agriculture on river beds, brickfields, and urbanisation have a severe impact on the hydromorphology of the channel, turning the active river into a stagnant and polluted channel.

N-Acetylcysteine Attenuates Sepsis-Induced Muscle Atrophy by Downregulating Endoplasmic Reticulum Stress.

(1) Background: Sepsis-induced muscle atrophy is characterized by a loss of muscle mass and function which leads to decreased quality of life and worsens the long-term prognosis of patients. N-acetylcysteine (NAC) has powerful antioxidant and anti-inflammatory properties, and it relieves muscle wasting caused by several diseases, whereas its effect on sepsis-induced muscle atrophy has not been reported. The present study investigated the effect of NAC on sepsis-induced muscle atrophy and its possible mechanisms. (2) Methods: The effect of NAC on sepsis-induced muscle atrophy was assessed in vivo and in vitro using cecal ligation and puncture-operated (CLP) C57BL/6 mice and LPS-treated C2C12 myotubes. We used immunofluorescence staining to analyze changes in the cross-sectional area (CSA) of myofibers in mice and the myotube diameter of C2C12. Protein expressions were analyzed by Western blotting. (3) Results: In the septic mice, the atrophic response manifested as a reduction in skeletal muscle weight and myofiber cross-sectional area, which is mediated by muscle-specific ubiquitin ligases-muscle atrophy F-box (MAFbx)/Atrogin-1 and muscle ring finger 1 (MuRF1). NAC alleviated sepsis-induced skeletal muscle wasting and LPS-induced C2C12 myotube atrophy. Meanwhile, NAC inhibited the sepsis-induced activation of the endoplasmic reticulum (ER) stress signaling pathway. Furthermore, using 4-Phenylbutyric acid (4-PBA) to inhibit ER stress in LPS-treated C2C12 myotubes could partly abrogate the anti-muscle-atrophy effect of NAC. Finally, NAC alleviated myotube atrophy induced by the ER stress agonist Thapsigargin (Thap). (4) Conclusions: NAC can attenuate sepsis-induced muscle atrophy, which may be related to downregulating ER stress.

Diaphragm-Induced Attenuation in Shock Tubes

This is a numerical and experimental study on shock attenuation in shock tubes. Tube geometry, boundary layer, and reduction in cross-sectional area induced by burst diaphragms are often considered the main causes of shock speed reduction (or shock attenuation) observed during the experiments. In order to distinguish how each single phenomenon contributes toward shock attenuation, the National Cheng Kung University shock tube is simulated for driver and test (driver–test) gas pairs involving air–air and He–air. For low pressure ratios, the diaphragm effect was found to be negligible. For a pressure ratio of 200 and helium as driver gas, the shock speed was found to decrease linearly with the size of the diaphragm orifice. In general, wall viscous effects caused a 2.5% decrease in shock speed, while an additional 7% reduction was caused by the presence of the diaphragm. The gradual opening of the diaphragm mainly contributed to a decrease in shock oscillations.

Transcriptome and Metabolome Profiling Provide New Insights into Disuse Muscle Atrophy in Chicken: The Potential Role of Fast-Twitch Muscle Fibers.

Disuse muscle atrophy is a disease caused by restricted activity, affecting human health and animal protein quality. While extensive research on its mechanism has been studied in mammals, comparatively little is known about this process in chickens, which are a significant source of protein for human consumption worldwide. Understanding the mechanisms underlying skeletal muscle atrophy in chickens is crucial for improving poultry health and productivity, as well as for developing strategies to mitigate muscle loss. In this study, two groups of chickens were subjected to limb immobilization for two and four weeks, respectively, in order to induce disuse muscle atrophy and uniformly sampled gastrocnemius muscle at the fourth week. A combined analysis of the transcriptome and metabolome was conducted to investigate the mechanisms of disuse-induced muscle atrophy. Through H&E staining and immunofluorescence, we found that, compared to slow-twitch muscle fibers, the fast-twitch muscle fibers showed a greater reduction in cross-sectional area in the immobilized leg, and were also the main driver of changes in cross-sectional area observed in the non-immobilized leg. Integrated analysis revealed that differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) were mainly enriched in pathways related to energy metabolism, such as fatty acid metabolism, oxidative phosphorylation (OXPHOS), and glycolysis. These results provide important insights for further research on disuse muscle atrophy.

State-Dependent Biomechanical Behavior of Oropharyngeal Structures in Apneics and Controls: A Proof-of-Concept Study.

Rationale: Apneics have reduced airway caliber during sleep. The biomechanical changes in upper airway anatomy contributing to this airway narrowing are largely unknown. Objectives: To investigate the state-dependent (wake vs. sleep) biomechanical behavior of the upper airway soft-tissue and craniofacial structures. Methods: Upper airway magnetic resonance imaging was performed in 15 sleep-deprived controls (AHI<5; 0.3±0.5 events/hour) and 12 sleep-deprived apneics (AHI≥5; 35.2±18.1 events/hour) during wake and sleep and analyzed for airway measures and soft-tissue/mandibular movement. Results: In the retropalatal region, controls showed sleep-dependent reductions (p≤0.037) in average cross-sectional airway area (CSA), minimum CSA, anteroposterior, and lateral dimensions. Apneics showed sleep-dependent reductions (p≤0.002) in average CSA, minimum CSA, anteroposterior and lateral dimensions. In the retroglossal region, controls had no sleep-dependent airway reductions. However, apneics had sleep-dependent reductions in minimal CSA (p=0.001) and lateral dimensions (p=0.014). Controls only showed sleep-dependent posterior movement of the anterior-inferior tongue octant (p=0.039), while apneics showed posterior movement of the soft palate (p=0.006) and all tongue octants (p≤0.012). Sleep-dependent medial movement of the lateral walls was seen at the retropalatal minimum level (p=0.013) in controls and the retropalatal and retroglossal minimum levels (p≤0.017) in apneics. There was posterior movement of the mandible in apneics (p≤0.017). Conclusion: During sleep, controls and apneics showed reductions in retropalatal airway caliber; only apneics showed retroglossal airway narrowing. Reductions in anteroposterior and lateral airway dimensions were primarily due to posterior soft palate, tongue and mandibular movement and medial lateral walls movement. These data provide important initial insights into obstructive sleep apnea pathogenesis.

Insight into the shear failure mechanism of Wound FRP reinforced concrete beams through numerical simulations considering interface damage and material anisotropy

Utilizing the inherent flexibility of high-strength fibres, Fibre-Reinforced Polymers (FRP) can be engineered as optimized reinforcing cages for concrete structures through the application of advanced digital fabrication techniques. However, existing codified design methods and numerical investigations found in the literature fall short in providing an accurate characterization of the actual performance of FRP reinforcement in concrete structures. This work presents a novel Finite Element (FE) modelling approach for concrete beams reinforced with FRP in non-traditional arrangements, accounting for reinforcement-concrete interface behaviour and FRP material anisotropy. Validation against experimental tests of flexible Wound-FRP (W-FRP) reinforced beams demonstrates accurate predictions of load-displacement curves, crack propagation, and load-strain curves. The study delves into shear failure mechanisms, emphasizing FRP reinforcement behaviour and damage evolution at reinforcement-concrete interfaces. Further parametric analysis explores the impact of W-FRP inclination angle and spacing, revealing their significant influence on beam stiffness and ultimate capacity. Specifically, the horizontal tensile force component in inclined links and increased modulus of links with reduced spacing enhance stiffness. Altered crack propagation due to W-FRP patterns, coupled with resulting damage development at concrete-stirrup interfaces and stress evolution in W-FRP stirrups, are key contributors to varied ultimate capacity. Moreover, higher performance of W-FRP stirrups with smaller spacing and reduced cross-section area further bolsters ultimate capacity. This research advances the modelling of FRP-reinforced concrete, offering potential solutions for optimizing FRP material utilization in concrete structures.

P240: Sarcopenia of the lower limb on Magnetic Resonance Imaging in patients with Diabetes Mellitus – a systematic review

Abstract Introduction Sarcopenia is defined by low measures of muscle quantity and quality and physical performance. Accelerated sarcopenic changes in diabetic patients leads to biomechanical changes in the foot and limb loss. Aim To systematically review the literature on Magnetic Resonance Imaging (MRI) and sarcopenia in the lower limb in patients with diabetes. Methods A literature review was conducted in accordance with PRISMA guidelines. Embase and Medline databases were searched with Ovid interface, as well as Pubmed and Cochrane. The grey literature was also reviewed on ClinicalTrials.gov, WHO international clinical trials registry platform, Cochrane library and the NIHR journals library and ProQuest. The MeSH terms “sarcopenia” AND “diabetes mellitus” AND “magnetic resonance imaging” were employed in the primary search string. The articles were reviewed by two independent reviewers. Results 874 studies were screened. 20 articles were included in the final review. Methods of measurement included cross sectional area measurements, stereological muscle measurements, muscle volume estimation, adipose infiltration, signal intensity cut-off, Goutallier grading, semiquantitative 5-point scale. Reduction in cross-sectional area and volumes and greater intramuscular fat infiltration was noted in patients with diabetes Sarcopenia ++ in Diabetic polyneuropathy (DPN) compared to non-diabetic and diabetic but non-DPN counterparts. MRI findings correlate with neuropathy disability scores and physical tests. Single study using a semi-automated process to measure sarcopenia. Conclusion MRI has its merit in providing accurate and detailed information on skeletal muscle volume and assessment of fat infiltration in muscle. This is relevant to reducing complications associated with changes in the biomechanics of the foot.

Delayed Detached-Eddy Simulations of Rough-Wall Turbulent Reactive Flows in a Supersonic Combustor

Reactive delayed detached-eddy simulations (DDESs) of hydrogen injection into a confined transverse supersonic flow of vitiated air are conducted. The corresponding conditions were studied in the LAPCAT-II combustor, which—due to thermal coating—exhibits non-negligible wall roughness. Its effects are taken into account with the equivalent sand-grain roughness model, and, to the best of the authors’ knowledge, it is the first time that this modeling framework is considered within the DDES framework to simulate turbulent reactive flows. Two operating conditions are considered, which differ in the value of the momentum ratio between the hydrogen and vitiated air inlet streams, thus leading to two distinct values of the operating equivalence ratio (ER). For its smallest value, smooth combustion is subject to a preliminary thermal runaway period, while for its largest value, combustion is more strongly intertwined with shock wave dynamics and boundary-layer separation. Since it features large subsonic regions, which are characteristic of situations close to thermal choking, the latter is referred to as the sudden or partially choked combustion mode. Computational results are assessed through comparisons with available experimental data for both operating conditions. The main mechanism through which wall roughness alters the combustion development lies in the reduction of the effective cross-sectional area that is induced by boundary-layer thickening. For the largest ER value, DDES conducted with the sand-grain roughness model does recover the partially choked combustion mode, while smooth wall (i.e., standard) DDES does not.

Evidence of MRI image features and inflammatory biomarkers association with low back pain in patients with lumbar disc herniation

BACKGROUND CONTEXTWhile MRI image features and inflammatory biomarkers are frequently used for guiding treatment decisions in patients with lumbar disc herniation (LDH) and low back pain (LBP), our understanding of the connections between these features and LBP remains incomplete. There is a growing interest in the potential significance of MRI image features and inflammatory biomarkers, both for quantification and as emerging therapeutic tools for LBP. PURPOSETo investigate the evidence supporting MRI image features and inflammatory biomarkers as predictors of LBP and to determine their relationship with pain intensity. STUDY DESIGNProspective cohort study. PATIENT SAMPLEAll consecutive patients with LDH who underwent discectomy surgery at our institution from February 2020 to June 2023 at the author's institution were included. OUTCOME MEASURESMRI image features in discogenic, osseous, facetogenic, and paraspinal muscles, as well as inflammatory biomarkers in serum (including CRP (C-reactive protein), ESR (erythrocyte sedimentation rate), PCT (procalcitonin), TNF (tumor necrosis factor), interleukin-1 beta (IL-1β), and IL-6), and paraspinal muscles (including TNF, IL-1β, IL-6, IL-10, and transforming growth factor beta 1 (TGF-β1)). METHODSA series of continuous patients diagnosed with LDH were categorized into acute LBP (<12 weeks), chronic LBP (≥12 weeks), and non-LBP groups. MRI image features and inflammatory biomarkers relation to pain intensity was assessed using the independent t-test, Chi-squared tests, Spearman rank correlation coefficient, and logistic regression test. RESULTSCompared to the non-LBP group, the chronic LBP group exhibited a higher incidence of intervertebral disc (IVD) degeneration (≥ grade 3) and high-fat infiltration in paraspinal muscles, alongside a significant reduction in the cross-sectional area (CSA) and fatty degeneration of the multifidus muscle. Furthermore, there was a greater expression of IL-6 in serum and TNF in paraspinal muscles in the chronic LBP group and a greater expression of CRP and IL-6 in serum and TNF in paraspinal muscles in the acute LBP group. CSA and fatty degeneration of multifidus muscle were moderately negatively correlated with chronic LBP scores. The expression of TNF and IL-6 in serum and the expression of TNF in the multifidus muscle were moderately correlated with preoperative LBP. IVD degeneration and high-fat infiltration were identified as risk factors for chronic LBP. CONCLUSIONThe results provide evidence that IVD degeneration, high-fat infiltration, and the reduction of CSA in paraspinal muscles were associated with the development of chronic LBP in patients with LDH, and these associations are linked to inflammatory regulation. This deepens our understanding of the etiology and pathophysiology of LBP, potentially leading to improved patient stratification and more targeted interventions.

Neuromuscular dysfunction precedes muscle atrophy in C26 tumor-bearing mice

Background: Cancer patients frequently develop skeletal muscle wasting and weakness, which are hallmarks of cachexia, a wasting disease which worsens quality of life and is directly responsible for up to 30% of all cancer-related deaths. While advancements in detection and treatment have increased the population of cancer survivors, skeletal muscle dysfunction can persist for years following cancer remission. We previously demonstrated that late-stage cachexia is associated with impaired skeletal muscle innervation, linking loss of motor unit (MU) connectivity to cancer-induced wasting and weakness. In the present study, we investigated the onset of neuromuscular dysfunction in a preclinical model of cancer cachexia.&#x0D; Methods: CD2F1 male mice (8-week-old) were subcutaneously injected with C26 colorectal cancer cells (1.0x106) or saline and randomized into one the following timepoint groups: day 6, day 8, or day 10 (n=8-10). Animals were assessed for indices of MU connectivity and muscle function at each timepoint. Following functional assessment, skeletal muscles were harvested, weighed, and processed for molecular analyses.&#x0D; Results: 6 days post tumor injection, C26 hosts displayed reductions in neuromuscular junction (NMJ) transmission and motor unit connectivity, while muscle torque and mass were preserved. Specific torque was reduced in C26 hosts at day 8, while reductions in muscle mass or cross-sectional area did not occur until day 10. Molecular analysis revealed alterations of NMJ components as early as day 6 in C26 hosts, further suggesting that neuromuscular dysfunction precedes muscle atrophy.&#x0D; Conclusions: Altogether our data demonstrate that cancer-induced neuromuscular dysfunction precedes cancer-induced muscle atrophy, identifying impaired innervation as an early prognosticator of cachexia progression. Our work supports strategies to counteract impaired neuromuscular function in the treatment of cancer cachexia, in hopes of sustaining quality of life in cancer patients and the growing population of cancer survivors.

Population trends in human rib cross-sectional shapes.

Rib fractures remain the most frequent thoracic injury in motor vehicle crashes. Computational human body models (HBMs) can be used to simulate these injuries and design mitigation strategies, but they require adequately detailed geometry to replicate such fractures. Due to a lack of rib cross-sectional shape data availability, most commercial HBMs use highly simplified rib sections extracted from a single individual during original HBM development. This study provides human rib shape data collected from chest CT scans of 240 females and males across the full adult age range. A cortical bone mapping algorithm extracted cross-sectional geometry from scans in terms of local periosteal position with respect to the central rib axis and local cortex thickness. Principal component analysis was used to reduce the dimensionality of these cross-sectional shape data. Linear regression found significant associations between principal component scores and subject demographics (sex, age, height, and weight) at all rib levels, and predicted scores were used to explore the expected rib cross-sectional shapes across a wide range of subject demographics. The resulting detailed rib cross-sectional shapes were quantified in terms of their total cross-sectional area and their cortical bone cross-sectional area. Average-sized female ribs were smaller in total cross-sectional area than average-sized male ribs by between 20% and 36% across the rib cage, with the greatest differences seen in the central portions of rib 6. This trend persisted although to smaller differences of 14%-29% when comparing females and males of equal intermediate weight and stature. Cortical bone cross-sectional areas were up to 18% smaller in females than males of equivalent height and weight but also reached parity in certain regions of the rib cage. Increased age from 25 to 80 years was associated with reductions in cortical bone cross-sectional area (up to 37% in females and 26% in males at mid-rib levels). Total cross-sectional area was also seen to reduce with age in females but to a lesser degree (of up to 17% in mid-rib regions). Similar regions saw marginal increases in total cross-sectional area for male ribs, indicating age affects rib cortex thickness moreso than overall rib cross-sectional size. Increased subject height was associated with increased rib total and cortical bone cross-sectional areas by approximately 25% and 15% increases, respectively, in mid-rib sections for a given 30 cm increase in height, although the magnitudes of these associations varied by sex and rib location. Increased weight was associated with approximately equal changes in both cortical bone and total cross-sectional areas in males. These effects were most prominent (around 25% increases for an addition of 50 kg) toward lower ribs in the rib cage and had only modest effects (less than 12% change) in ribs 2-4. Females saw greater increases with weight in total rib area compared to cortical bone area, of up to 21% at the eighth rib level. Results from this study show the expected shapes of rib cross-sections across the adult rib cage and across a broad range of demographics. This detailed geometry can be used to produce accurate rib models representing widely varying populations.

Dual template-derived 3D porous Co6Mo6C2/Mo2C@NC framework for electromagnetic wave response and multifunctional applications

The swift advancement of electronics technology has led to a burgeoning interest in multifunctionalizing electromagnetic wave (EMW) absorption materials as a prospective avenue for future development. However, the effective integration of diverse functions within a single material continues to present challenges. This work successfully fabricated a three-dimensional (3D) porous Co6Mo6C2/Mo2C@NC framework with carbon microspheres through uncomplicated freeze-drying and high-temperature pyrolysis techniques. The resultant magnetic bimetallic carbide (Co6Mo6C2 and Mo2C) nanoparticles are uniformly and densely embedded within the carbon layer, facilitated jointly by a rigid template (molybdenum salt) and a flexible template (glucose), thus realizing an exceptional dual loss mechanism involving dielectric and magnetic components. The establishment of the 3D porous conductive network enhances EMW absorption through multiple reflections and scattering mechanisms. Impressively, the Co6Mo6C2/Mo2C@NC framework attains remarkable EMW absorption characteristics with ultralightweight (0.1567 g cm–3), ultrathin matching thickness (1.7 mm), and robust absorption (reflection loss RL value of –65.89 dB). Furthermore, it achieves a noteworthy effective absorption bandwidth (EAB, RL ≤ –10 dB) spanning 6.4 GHz, ensuring complete absorption of 100 % within the X band (8–12 GHz) at a matching thickness of 2 mm. In addition, the Co6Mo6C2/Mo2C@NC framework exhibits pronounced hydrophobicity and magnetic responsiveness, bestowing upon it appealing attributes including self-cleaning, flame retardancy, and thermal insulation, on par with those observed in commercial products. The radar cross-sectional area (RSC) reduction value of the Co6Mo6C2/Mo2C@NC framework can reach 35.2 dB m2 by RSC simulation, which can effectively lower the likelihood of detection by radar detectors for the target. This study presents a viable strategy for the advancement of novel lightweight and multifunctional materials that demonstrate exceptional performance in absorbing electromagnetic waves.

Effects of empagliflozin on right ventricular adaptation to pressure overload.

Right ventricular (RV) failure is the prime cause of death in patients with pulmonary arterial hypertension. Novel treatment strategies that protect the RV are needed. Empagliflozin, a sodium-glucose co-transporter-2 inhibitor, shows cardioprotective effects on the left ventricle in clinical and preclinical studies, but its direct effects on RV remain elusive. We investigated the effects of empagliflozin on RV dysfunction induced by pulmonary trunk banding (PTB). Male Wistar rats (116 ± 10 g) were randomized to PTB or sham surgery. One week after surgery, PTB animals received empagliflozin mixed into the chow (300 mg empagliflozin/kg chow; PTB-empa, n = 10) or standard chow (PTB-control, n = 10). Sham rats (Sham, n = 6) received standard chow. After five weeks, RV function was evaluated by echocardiography, cardiac MRI, and invasive pressure-volume measurements. PTB caused RV failure evident by decreased cardiac output compared with sham. PTB-empa rats had a 49% increase in water intake compared with PTB-control yet no differences in hematocrit or blood glucose. Treatment with empagliflozin decreased RV end-systolic pressures without any changes in RV cardiac output or ventricular-arterial coupling (Ees/Ea). The decrease in RV end-systolic pressure was complemented by a slight reduction in RV cross sectional area as a sign of reduced hypertrophy. Load-independent measures of RV systolic and diastolic function were not affected in PTB-empa rats compared with PTB-control. Empagliflozin treatment reduced RV end-systolic pressure in RV failure induced by pressure overload. Further studies are needed to elucidate whether this simply relates to a diuretic effect and/or additional independent beneficial RV effects.

Evaluations of low-temperature mechanical properties and full-range constitutive models of AA 5083-H112/6061-T6

The low-temperature mechanical properties of aluminium alloys (AAs) are important for the analysis and design of infrastructures in cold regions and LNG storage tanks made of AAs. This paper investigated the stress-strain behaviours of AA 5083-H112/6061-T6 materials through conducting tensile tests on 32 AA coupons at 20 ℃ ∼ −165 ℃. All the tested AA coupons exhibited ductile failure modes. Their results showed that the stress-strain curves of AA 5083-H112 exhibited the Portevin-Le Chatelier effects that gradually weakened with the decreasing temperature. Reducing the temperature from 20 ℃ to −165 ℃ increased the elastic modulus, yield and ultimate strengths of AA 5083-H112 (or 6061-T6) by 5.1% (6.5%), 8.7% (12.0%) and 7.8% (13.1%), but reduced the fracture strain by 16.4% (12.4%). The fracture surfaces of all AA 5083-H112 and 6061-T6 coupons displayed localised cross-sectional area reductions and substantial plastic deformation. Meanwhile, precipitation-hardened AA 6061-T6 exhibits a more pronounced enhancement compared to strain-hardened AA 5083-H112. Furthermore, regression analyses were performed to establish prediction equations for the low-temperature mechanical indexes of AAs. Subsequently, a full-range constitutive model was proposed to estimate the stress-strain behaviours of AA 5083-H112 and 6061-T6. Validations against reported experimental observations demonstrated that the developed model reasonably described the stress-strain responses of AA 5083-H112 and 6061-T6 from 20 ℃ to −165 ℃.

Recharge dynamic and flow-path geometry controls of solute transport in karst aquifer

Solute transport is complex in karst aquifer due to its heterogeneous structure and polytropic hydrodynamic condition. Hydrological monitoring and artificial tracer test were conducted in two flow paths under different recharge conditions, and the Advection–Dispersion Equation and Dual Region Advection–Dispersion models were successfully calibrated to simulate the breakthrough curves. Intermittent concentrated recharge at sinkholes and quick hydrological response at spring outlet often occur after rainstorms. Single symmetrical shape and bimodal shape with long tail were characterized in the breakthrough curves. Stronger recharge hydrodynamic condition drives a larger transport velocity with higher solute transport efficiency. The tracer injection time during a concentrated recharge event is found to significantly affect the solute transport process. Constantly pushed by the follow-up recharge water, the piston transport process of solute in conduit enables higher recovery rate for the tracer injected at the initial recharge process. Solute transient storage in fissures occurs while tracer is injected at the peak flow. A negative correlation between dispersivity and flow velocity is found in karst conduits. The reduction in cross-section area of karst conduits causes high dispersivity and obvious tailing in breakthrough curves due to the blocking function of solute by the uneven bottom surface in karst conduits. The solute transport process is significantly controlled by the changes in hydrodynamic and flow cross-section due to concentrated recharge events, which deepen our understanding of solute transport in karst groundwater.

Genetic diversity modulates the physical and transcriptomic response of skeletal muscle to simulated microgravity in male mice

Developments in long-term space exploration necessitate advancements in countermeasures against microgravity-induced skeletal muscle loss. Astronaut data shows considerable variation in muscle loss in response to microgravity. Previous experiments suggest that genetic background influences the skeletal muscle response to unloading, but no in-depth analysis of genetic expression has been performed. Here, we placed eight, male, inbred founder strains of the diversity outbred mice (129S1/SvImJ, A/J, C57BL/6J, CAST/EiJ, NOD/ShiLtJ, NZO/HILtJ, PWK/PhJ, and WSB/EiJ) in simulated microgravity (SM) via hindlimb unloading for three weeks. Body weight, muscle morphology, muscle strength, protein synthesis marker expression, and RNA expression were collected. A/J and CAST/EiJ mice were most susceptible to SM-induced muscle loss, whereas NOD/ShiLtJ mice were the most protected. In response to SM, A/J and CAST/EiJ mice experienced reductions in body weight, muscle mass, muscle volume, and muscle cross-sectional area. A/J mice had the highest number of differentially expressed genes (68) and associated gene ontologies (328). Downregulation of immunological gene ontologies and genes encoding anabolic immune factors suggest that immune dysregulation contributes to the response of A/J mice to SM. Several muscle properties showed significant interactions between SM and mouse strain and a high degree of heritability. These data imply that genetic background plays a role in the degree of muscle loss in SM and that more individualized programs should be developed for astronauts to protect their skeletal muscles against microgravity on long-term missions.

A low-frequency sound insulation metastructure with relatively high ventilation

Noise pollution is growing nowadays and there is always a conflict between ventilation and noise insulation. The advances in acoustic metamaterials provide an effective solution for this conflict. In this paper, we propose a metastructure with protruded necks based on Helmholtz resonance. Sound transmission loss (STL) of 13 dB at low-frequency of 488[Formula: see text]Hz is obtained in experiment with the ventilation of 20%, which is in good agreement with the simulation. It is revealed that introduction of protruded neck can reduce the resonant frequency. Sound absorption is the main mechanism for noise insulation at low frequency. Next, the effects of geometric parameters on sound insulation are discussed. A reduction in cross-sectional area of neck, an increase in neck length, and an increase in ventilation all lead to a decrease in both resonant frequencies and STL amplitudes. Finally, a two-layer structure is constructed by the proposed metastructure with different neck length in each unit. Both the amplitude and frequency range of STL are enlarged. These results exhibit a practical application for ventilated metastructure in sound insulation at low frequency.