Changes In Wave Velocity Research Articles

Influence of biocementation treatment extent on dynamic system performance: A centrifuge liquefaction study

Previous centrifuge experiments have shown Microbially Induced Calcite Precipitation (MICP) is a viable ground improvement technique to mitigate liquefaction. However, in these past experiments the entire sample in the model container was MICP treated. This study is an investigation of the effect of treatment extent on the system seismic performance by varying the depth of improvement, while maintaining the same cross-sectional area. Specifically, MICP treated zones (10 cm × 10 cm in model scale in plan view) were varied in depth to 100%, 75%, and 37% of the liquefiable sand layer depth. As a comparison, two additional models were constructed, an untreated and fully treated model. The treated models were initially prepared to a relative density of less than 40% and MICP treatment applied until a change of shear wave velocity (Vs) of 300 m/s was measured. All models were instrumented with accelerometers and pore pressure transducers to capture the dynamic responses during the same sequence of eight shaking events. Cone penetration resistance was measured to verify the uniformity of the untreated zones in the models and track the evolution of penetration resistances at three different times during the shaking sequence. Vs was measured after each shaking event to assess the cementation integrity of the MICP treated zones. Linear potentiometer and pre- and post-surface measurements were obtained to track seismic-induced settlements. Pore pressure generation and settlements were reduced in the MICP treated zones compared to untreated zones, showing the increased liquefaction resistance and system performance of MICP. Amplification of the strong ground motions in the models with treatment through the full liquefiable layer lead to significant degradation of the MICP. While a base isolation effect was observed in the models not treated to the full depth of the liquefiable layer, reducing seismic demands to the MICP treated zoned, and leading to minimal changes in cementation integrity. These findings suggest that there may be a benefit to not improving the entire liquefiable depth for maintaining cementation integrity of MICPtreated soils.

Analyzing possible seismic velocity changes in Mexico City using seismic noise interferometry

The seismic response of the Mexico City basin has received plenty of attention as one of the most relevant cases of ground motion amplification. A recent study showed possible velocity variations of the deposits in both the lake bed and firm ground. A clear drop in seismic velocity was observed during the 2017.09.19 earthquake (Mw 7.1) in addition to more subtle seismic velocity changes related to seasonal temperature and precipitation. We use continuous seismic noise data recorded in a 29 broadband seismograph network in and around Mexico City to investigate Rayleigh wave group velocity structure and velocity changes. We estimate Green's functions (GF) between station pairs using seismic noise cross-correlation. An average estimate is computed for each of three five-day periods of recording. GFs are dominated by a Rayleigh pulse at low frequencies (between 0.1 and 0.2 Hz). Velocity changes are investigated through the comparison between GF's for different five-day periods. No velocity variations are observed. Station pairs separated at a distance smaller than 20 km also show some Rayleigh wave energy at higher frequencies, between 0.3 and 1.2 Hz. We repeated the analysis in a higher frequency band (up to 5 Hz) and show that again no velocity variation can be observed. In addition, we used horizontal-to-vertical spectral ratios computed for both earthquake and seismic noise records to identify possible non-linear effects during the 2017 earthquake. The results showed that significant non-linear effects during that event are to be discarded. Finally, we present preliminary results of a tomography of Rayleigh wave group velocity at the center of the array. Lateral structure variations below the geotechnical zonation are significant. Our data will be useful to constrain the structure of the volcanic deposits of the Transmexican Volcanic Belt (TVB).

Effect of Incorporating 1 Avocado per Day Versus Habitual Diet on Vascular Function in Adults With Abdominal Obesity: An Ancillary Study of HAT, a Randomized Controlled Trial.

Abdominal obesity is associated with endothelial dysfunction and poorer vascular health. Avocado consumption improves postprandial endothelial function; however, the longer-term effects remain unclear. It was hypothesized that the daily addition of 1 avocado to a habitual diet for 6 months would improve flow-mediated dilation (FMD) and carotid-femoral pulse wave velocity in individuals with abdominal obesity (waist circumference ≥35 in for women, ≥40 in for men), compared with a habitual diet low in avocados. HAT (Habitual Diet and Avocado Trial) was a multicenter, randomized, controlled, parallel-arm study that investigated the health effects of adding 1 avocado per day to a habitual diet in individuals with abdominal obesity. At the Pennsylvania State University, University Park study center (n=134; age, 50 ± 13 years; women, 78%; body mass index, 32.6 ± 4.8 kg/m2), markers of vascular function were measured, including endothelial function, assessed via brachial artery flow-mediated dilation, and arterial stiffness, assessed via carotid-femoral pulse wave velocity. Between-group differences in 6-month change in flow-mediated dilation and carotid-femoral pulse wave velocity were assessed using independent t tests. Prespecified subgroup analyses were conducted using linear regression. No significant between-group differences in flow-mediated dilation (mean difference=-0.62% [95% CI, -1.70 to 0.46]) or carotid-femoral pulse wave velocity (0.25 m/s [95% CI, -0.13 to 0.63]) were observed. Results of the subgroup analyses were consistent with the primary analyses. Longer-term consumption of 1 avocado per day as part of a habitual diet did not improve measures of vascular function compared with a habitual diet low in avocados in individuals with abdominal obesity. URL: https://www.clinicaltrials.gov; Unique identifier: NCT03528031.

Untangling the environmental and tectonic drivers of the Noto earthquake swarm in Japan.

The underlying mechanism of the ongoing seismic swarm in the Noto Peninsula, Japan, which generates earthquakes at 10 times the average regional rate, remains elusive. We capture the evolution of the subsurface stress state by monitoring changes in seismic wave velocities over an 11-year period. A sustained long-term increase in seismic velocity that is seasonally modulated drops before the earthquake swarm. We use a three-dimensional hydromechanical model to quantify environmentally driven variations in excess pore pressure, revealing its crucial role in governing the seasonal modulation with a stress sensitivity of 6 × 10-9 per pascal. The decrease in seismic velocity aligns with vertical surface uplift, suggesting potential fluid migration from a high-pore pressure zone at depth. Stress changes induced by abnormally intense snow falls contribute to initiating the swarm through subsequent perturbations to crustal pore pressure.

CENTRAL BLOOD PRESSURE AND VASCULAR RESPONSES TO DIFFERENT PHYSICAL EXERCISE INTENSITIES IN NORMAL AND HIGH-NORMAL BLOOD PRESSURE AS A TOOL TO IDENTIFY EARLY VASCULAR DAMAGE

Objective: To evaluate acute changes in arterial distensibility and central pressure by high-intensity interval physical exercise (HIIPE) compared to moderate intensity continuous physical exercise (MICPE) sessions in subjects with normal and high-normal blood pressure (BP). Design and method: A randomized two-period crossover trial with 29 subjects (48±7years, 76%female, BMI=28.3±4.3kg/m2) divided into two groups according to Normal BP (120-129 and/or 80-84 mmHg) or HighNormal BP (130-139 and 85-89 mmHg) levels. They underwent either MICPE-HIIPE or HIIPE-MICPE sequences. Exercise intensity was defined according to the cardiopulmonary exercise test. The measures included aortic pulse wave velocity (PWV) and applanation tonometry (Sphygmocor®) changes at baseline, immediately, and 24 hours after each physical exercise session. Results: In HighNormal BP group, PWV was significantly lower 24h after MICPE compared to baseline (7.49 ±0.95 vs 8.20± 0.64 m/s; p=0.022). Aortic SBP was significantly lower immediately after HIIPE than baseline and 24h after MICPE (113 ± 8; 124±9 and 121±9; p < 0.05). Comparison between groups, aortic SBP was higher in HighNormal BP at baseline and immediately after MICPE compared to Normal BP (124 ±9 and 122 ±17 vs 114± 9 and 110 ±8; respectively p=0.012). Conclusions: In subjects with normal and high-normal BP, vascular distensibility response to exercise is more dependent on basal levels of stiffness and more sensitive to the stimulus of MICPE; however, changes in aortic BP are more dependent on basal BP levels and more sensitive to high-intensity stimuli.

Characterization of the Dynamic Behavior of Multinanobubble System under Shock Wave Influence.

Shockwave-induced changes in nanobubbles cause cavitation erosion and membrane damage but can also be applied to biocarrier transport. Currently, research focuses on single nanobubbles; however, in reality, nanobubbles usually appear as a multibubble system. Therefore, this study proposes a method based on cutting and replicating to construct a multibubble model. This method can be widely applied to molecular dynamics (MD) models and enhance the customization capabilities of MD models. The dynamic behavior of a multinanobubble system with different numbers and arrangements of nanobubbles is investigated with the MD method under the influence of shock waves in a liquid argon system. The study also explores the range of influence between nanobubbles. The results show that in the case of two nanobubbles, when the distance between the bubbles is constant, the smaller the angle between the direction of the shock wave and the line connecting the bubbles, the greater is the influence between nanobubbles, and the moment of collapse of the nanobubbles farther away from the shock wave is slower. When three nanobubbles are arranged with a right offset, after the first bubble collapses, the effect on the other two bubbles is similar to the changes in bubbles when the angle of arrangement is 30° or 60°. Under a different arrangement, the change of shock wave velocity on the nanobubble size only affects its collapse time and contraction collapse rate. When the shock wave with a radian of about 2.87 or greater than 2.87 touches the bubbles, the collapse of the second nanobubble will not be affected.

Investigation of physical and metallographic properties of nickel matrix composite by ultrasonic method

Ultrasonic testing (UT) is one of the most widely used non-destructive testing techniques for the characterization and evaluation of materials. In this study, the material properties of AstCrM-BN-Cr-Ti-Ni composites produced by mechanical mixing and electroless nickel plating technique were evaluated using UT. Changes in ultrasonic wave velocity, Young's modulus, density, porosity and hardness are observed in the heat-treated material at different temperatures. Samples analyzed by Scanning Electron Microscopy (SEM) and X-Ray Diffractometry (XRD) exhibited changes in grain structure at different sintering temperatures. It has been observed that the change in grain size also affects mechanical and physical properties according to ultrasonic properties. In conclusion, the experimental results showed a linear relationship between the mean grain size and the UT parameters (ultrasonic longitudinal and transverse velocity, Young's modulus), physical (sintering temperature and density) and mechanical properties (hardness and porosity) of the material. Grain growth occurs with increasing sintering temperature, porosity content decreases, hardness, Young's modulus and ultrasonic wave velocity values also increase.

Abstract MP60: A Randomized Placebo-Controlled Trial of Pitavastatin Calcium to Treat Combined Dyslipidemia of Obesity in Adolescents - The Pediatric Heart Network Dyslipidemia of Obesity Intervention in Teens (Do It!) Trial

Background: Combined dyslipidemia of obesity (CDO) is prevalent in ~20% of youth and characterized by high numbers of atherogenic small LDL (sLDL) particles associated with stiffer arteries. The safety and impact of statin therapy is not known. Methods: A 2-year masked trial of pitavastatin calcium 4 mg/day versus placebo for participants ages 10-19 years with body mass index (BMI) ≥85 th %ile and CDO defined as non-HDL-C ≥120 mg/dL and either low HDL-C or high triglyceride (TG):HDL-C ratio. The primary outcome was change in carotid-femoral pulse wave velocity (PWV) and carotid measures assessed at baseline, 6, 12, 18, and 24 months. Secondary outcomes included safety and lipid measures. Results: Across 18 sites, 59 participants were randomized to pitavastatin and 60 to placebo. Demographic (mean age 13.5±1.2 yrs; 55% males), anthropomorphic (BMI %ile 98±3; waist/height ratio 0.66±0.08), lipid (non-HDL-C 167±29 mg/dL, LDL-C 127±25 mg/dL, HDL-C 37±7 mg/dL, TG/HDL ratio 6.4±4.7, sLDL number 866±419 nmol/L), vascular (PWV 5.0±0.7 m/sec) and safety measures were similar at baseline between groups. There were 28 early terminations (11 pitavastatin, 17 placebo). Significant reductions with pitavastatin versus placebo were noted in non-HDL-C (median -25% vs +3% at 6 months, p<0.001), LDL-C (-29% vs +7%, p<0.001), and apolipoprotein B (-26% vs 0%, p<0.001). An early reduction relative to placebo in sLDL particle number was not sustained (FIGURE A), and there were no significant changes or trends for PWV (FIGURE B) or carotid measures in either group. There was one serious adverse event (placebo), and no significant differences in liver enzymes, muscle toxicity, glucose homeostasis, or somatic growth, including adiposity. Conclusions: Over 2 years, treatment of CDO in adolescents with pitavastatin calcium resulted in significant improvement in dyslipidemia with no safety concerns. No change in PWV in either group may be due to lower-than-expected baseline PWV, insufficient magnitude of impact on CDO, or lack of change in adiposity.

Ultrasonic monitoring of softening in solid foods during in-vitro gastric digestion

This study aims to evaluate the feasibility of using non-destructive ultrasound to monitor textural softening in potato and cheese during in vitro gastric digestion. Textural measurements were taken after different digestion times (5, 10, 15, 20, 25, 30, 60, 90, and 120 min) at 37 °C, while in vitro digestion was non-destructively monitored using ultrasound in through-transmission mode.The textural softening resulted in a substantially greater variation in hardness, ranging from 0.418 to 1.241 N for potato and from 0.200 to 0.534 N for cheese. Meanwhile, the ultrasonic velocity increased during gastric digestion from 745 ± 106.6 m/s to 1342.9 ± 131.5 m/s in potato and from 1377.4 ± 3.8 m/s to 1502.8 ± 4.6 m/s in cheese. Both the softening and velocity increase were attributable to the compositional variation occurring within the food structure due to gastric fluid diffusion into the food matrix. The Weibull model kinetic parameter “k” indicated that potato exhibited a higher softening rate than cheese, due to a faster gastric fluid migration. This was also evidenced by the effective diffusivity of gastric fluid (Deff) obtained by modeling the evolution of the ultrasonic velocity during digestion (Deff, potatõ2.5 Deff, cheese). A noticeable relationship was found between the softening of both food matrices and the change in the ultrasonic wave velocity. Additionally, it should be highlighted that the measurement of the ultrasonic velocity by ultrasound presented a lower degree of variability than instrumental texture assessment. Therefore, ultrasound proves to be an accurate technique for the on-line monitoring of textural changes in foods during in vitro digestion. This non-destructive approach provides a powerful instrumental tool in the design of new products with enhanced nutritional properties by better monitoring how in vitro digestion affects their mechanical properties.

Stress‐induced anisotropy in Gulf of Mexico sandstones and the prediction of in situ stress

AbstractThe strong sensitivity of velocity to stress observed in many sandstones originates from the response of stress‐sensitive discontinuities such as grain contacts and microcracks to a change in effective stress. If the change in stress is anisotropic, then the change in elastic wave velocities will also be anisotropic. Characterization of stress‐induced elastic anisotropy in sandstones may enable estimation of the in situ three dimensional stress tensor with important application in solving problems occurring during drilling, such as borehole instability, and during production, such as sanding and reservoir compaction. Other applications include designing hydraulic fracture stimulations and quantifying production‐induced stresses which may lead to rock failure. Current methods for estimating stress anisotropy from acoustic anisotropy rely on third‐order elasticity, which ignores rock microstructure and gives elastic moduli that vary linearly with strain. Elastic stiffnesses in sandstones vary non‐linearly with stress. Using P‐ and S‐wave velocities measured on Gulf of Mexico sandstones, this non‐linearity is found to be consistent with a micromechanical model in which the discontinuities are represented by stress‐dependent normal and shear compliances. Stress‐induced anisotropy increases with increasing stress anisotropy at small stress but then decreases at larger stresses as the discontinuities close and their compliance decreases. When the ratio of normal‐to‐shear compliance of the discontinuities is unity, the stress‐induced anisotropy is elliptical, but for values different from unity, the stress‐induced anisotropy becomes anelliptic. Although vertical stress can be obtained by integrating the formation's bulk density from the surface to the depth of interest, and minimum horizontal stress can be estimated using leak‐off tests or hydraulic fracture data, maximum horizontal stress is more difficult to estimate. Maximum horizontal stress is overpredicted based on third‐order elasticity using measured shear moduli, with estimates of pore pressure, vertical stress and minimum horizontal stress as input. The non‐linear response of grain contacts and microcracks to stress must be considered to improve such estimates.

Carotid Intima-Media Thickness in Children with Chronic Kidney Disease as an Early Predictor of Cardiovascular Diseases

Aim: Cardiovascular problems are very common in children with chronic kidney disease (CKD). To examine early cardiovascular risk factors, notably carotid intima-media thickness (CIMT) and pulse wave velocity (PWV). Material and Method: Case-control study was conducted in the Department of Pediatric Nephrology Sindh Institute of Urology and Transplantation Karachi from 1stFebruary 2023 to 31st July 2023. Forty two children were enrolled. CIMT and PWV were measured using ultrasonography and pulse wave analysis respectively. The following clinical parameters were also assessed: blood pressure, age, gender, etiology, duration of chronic kidney disease (CKD), estimated glomerular filtration rate (eGFR), serum albumin, calcium-phosphate product, and intact parathyroid hormone (PTH), and vitamin D levels. Results: The average age was 10.2±3.6 years, with a higher proportion of boys in the cases group (69% versus 47.6%, p-value 0.04). Most patients had normal blood pressure (78.6%), and congenital anomalies were the most common CKD etiology (57.1%). Median eGFR was 30.5 ml/min/1.73 m2, with stages 3 and 4 CKD most prevalent. Serum albumin was normal (mean 4.45±0.68), but some cases had a high calcium-phosphate product (7%) and low vitamin D levels (52%). CIMT and PWV did not differ significantly between cases and controls. Echocardiography revealed mild cardiac abnormalities in some cases. Practical implication: Some patients showed minor left ventricular expansion, while others had mildly depressed GLS and decreased LVEF. Further research should focus on longitudinal studies and explore new biomarkers for early cardiovascular risk detection. Conclusion: The various clinical characteristics such as blood pressure, mineral and bone diseases, and cardiac abnormalities are common in children with chronic kidney diseases. There were no significant changes in carotid intima-media thickness and pulse wave velocity between the cases and controls. Keywords: Chronic kidney disease, Carotid intima-media thickness, Cardiovascular disease, Pulse wave velocity

Structure and elasticity of CaC2O5 suggests carbonate contribution to the seismic anomalies of Earth’s mantle

Knowledge of carbonate compounds under high pressure inside Earth is key to understanding the internal structure of the Earth, the deep carbon cycle and major geological events. Here we use first-principles simulations to calculate the structure and elasticity of CaC2O5-minerals with different symmetries under high pressure. Our calculations show that CaC2O5-minerals represent a group of low-density low-seismic-wave velocity mantle minerals. Changes in seismic wave velocity caused by the phase transformation of CaC2O5-Cc to CaC2O5-I4¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{4}$$\\end{document}2d (CaC2O5-C2-l) agree with wave velocity discontinuity at a depth of 660 km in the mantle transition zone. Moreover, when CaC2O5-Fdd2 transforms into CaC2O5-C2 under 70 GPa, its shear wave velocity decreases by 7.4%, and its density increases by 5.8%, which is consistent with the characteristics of large low-shear-velocity provinces (LLSVPs). Furthermore, the shear wave velocity of CaC2O5-I4¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{4}$$\\end{document}2d is very similar to that of cubic Ca-perovskite, which is one of the main constituents of the previously detected LLSVPs. Therefore, we propose that CaC2O5 and its high-pressure polymorphs may be a main component of LLSVPs.

The effects of internal erosion on granular soils used in transport embankments

The flooding of embankments used for rail and other infrastructure has the potential to cause lasting weakening of slopes via the movement of fine particles induced by seepage. In laboratory experiments, internal erosion was induced in granular soil samples, with properties consistent with those used to construct transportation embankments, to assess how particle migration through, and out of, samples caused shear wave velocity, strength, stiffness and permeability changes. Shear wave velocity changes, measured using horizontal bender elements, of up to 19 % were observed following fine particle removal of up to 1 % of initial sample mass. Shear wave velocity change was found to be an indicator for identifying the development of permeability change during seepage-induced particle migration. Median measured permeability changes were +5 % and −34 % for samples containing 15 % and 30 % fines, respectively. The largest directly observed permeability and shear wave velocity changes occurred during the initial stages of seepage. Negative correlation was observed between mass of material removed from samples and peak friction angle. Following seepage, soils displayed a dual stiffness behaviour. Stiffness and strength changes were attributed to redistribution of fine particles and opening of pore spaces. Our results have implications for the monitoring of earthworks affected by flooding and seepage as the associated redistribution of fine particles may lead to large changes in slope properties.

Physical mechanism of the variation of longitudinal wave velocity with porosity in seafloor sediments

In order to reveal the response mechanism of longitudinal wave velocity and related parameters, through the statistical analysis of the measurement data of seafloor sediments, it is found that there is a minimum value of the change of longitudinal wave velocity with porosity of seafloor sediments. The minimum values of the empirical formula for the change of longitudinal wave velocity with porosity of sediments in different sea areas and their critical porosity values are uniformly analyzed. The calculation shows that the minimum variation range of longitudinal wave velocity with porosity of sediments in different sea areas is between 1468.59 and 1520.22 m/s, and the corresponding critical porosity value changes between 0.69 and 0.88. The analysis shows that the empirical formulas of different scholars belong to the unified mathematical expression derived from acoustic theory. The study shows that the essential reason for the formation of the minimum of longitudinal wave velocity in seafloor sediment is that the coupling of sediment grains affects the propagation of longitudinal wave. It is further revealed that the physical mechanism of the change of longitudinal wave velocity is that the change of contact or suspension state of seafloor sediment grains in seawater affects the elastic stress-strain relations of sediments.

Surface Acoustic Waves (SAW) Sensors: Tone-Burst Sensing for Lab-on-a-Chip Devices.

The article presents the design concept of a surface acoustic wave (SAW)-based lab-on-a-chip sensor with multifrequency and multidirectional sensitivity. The conventional SAW sensors use delay lines that suffer from multiple signal losses such as insertion, reflection, transmission losses, etc. Most delay lines are designed to transmit and receive continuous signal at a fixed frequency. Thus, the delay lines are limited to only a few features, like frequency shift and change in wave velocity, during the signal analysis. These facts lead to limited sensitivity and a lack of opportunity to utilize the multi-directional variability of the sensing platform at different frequencies. Motivated by these facts, a guided wave sensing platform that utilizes simultaneous tone burst-based excitation in multiple directions is proposed in this article. The design incorporates a five-count tone burst signal for the omnidirectional actuation. This helps the acquisition of sensitive long part of the coda wave (CW) signals from multiple directions, which is hypothesized to enhance sensitivity through improved signal analysis. In this article, the design methodology and implementation of unique tone burst interdigitated electrodes (TB-IDT) are presented. Sensing using TB-IDT enables accessing multiple frequencies simultaneously. This results in a wider frequency spectrum and allows better scope for the detection of different target analytes. The novel design process utilized guided wave analysis of the substrate, and selective directional focused interdigitated electrodes (F-IDT) were implemented. The article demonstrates computational simulation along with experimental results with validation of multifrequency and multidirectional sensing capability.

Longitudinal assessment of liver stiffness using ARFI technique does not support increased risk of fibrosis in rheumatoid arthritis patients on methotrexate.

To assess the liver stiffness in patients with rheumatoid arthritis treated with methotrexate monotherapy using non-invasive, ultrasound-based elastography (acoustic radiation force impulse (ARFI) imaging) in a longitudinal approach. In total, 23 MTX-naive patients were longitudinally assessed using acoustic radiation force impulse (ARFI) imaging. Baseline assessments were carried out between July 2018 and April 2019, and the follow-up evaluations took place after an average of 2.6years. The main outcome variable was the mean shear wave velocity as measured by the ARFI method. It was calculated from 10 valid ARFI measurements for each patient. Inferential statistical analyses (within-group comparisons) were performed using t-tests for dependent samples or suitable nonparametric procedures. The main finding was that observed ARFI shear wave velocities did not increase during the observation period. In fact, this parameter decreased over time from 1.07m/s (SD = 0.23) at baseline without MTX exposure to 0.97m/s (SD = 0.16) at follow-up after a mean of 2.6years (P = 0.013). Moreover, the magnitude of the change in shear wave velocity could not be predicted by indicators of inflammation or disease activity, BMI, age, sex or NSAR intake (corresponding regression analysis: corrected R2 = 0.344; P = 0.296). No increased risk of liver fibrosis was found in RA patients treated with MTX monotherapy during observation period.

The Impact of Finerenone on Changes in Pulse Wave Velocity, Arterial Pressure and Heart Related Deaths in Hemodialysis Patients—Study Perspective

The Impact of Finerenone on Changes in Pulse Wave Velocity, Arterial Pressure and Heart Related Deaths in Hemodialysis Patients—Study Perspective

Effects of low-pressure Valsalva maneuver on changes in cerebral arterial stiffness and pulse wave velocity.

The Valsalva maneuver (VM), commonly used to assess cardiovascular and autonomic nervous system functions, can induce changes in hemodynamic function that may affect cerebral vascular functionality, such as arterial elasticity. This study aimed to investigate the effects of low-pressure VM on cerebral arterial stiffness and cerebral vascular dynamics. Thirty-one healthy young participants (average age 21.58±1.72 years) were recruited for this study. These participants were instructed to maintain an expiratory pressure of 30-35 mmHg for 15 seconds. We measured the vasoconstriction and vasodilation diameters (VCD and VDD) of the common carotid artery (CCA), as well as systolic and diastolic blood pressures (SBP and DBP), before and after VM (PRE_VM and POST_VM). Additionally, we assessed mean arterial pressure (MAP), pulse pressure (PP), pulse wave velocity (PWV), and arterial stiffness. Our findings revealed significant increases in both the VCD and VDD of the CCA (2.15%, p = 0.039 and 4.55%, p<0.001, respectively), MAP (1.67%, p = 0.049), and DBP (1.10%, p = 0.029) following low-pressure VM. SBP showed an increasing trend, but this was not statistically significant (p = 0.108). Interestingly, we observed significant decreases in arterial stiffness and PWV in POST_VM when comparing with PRE_VM (p<0.001 and p<0.001, respectively). In conclusion, our study demonstrated the effectiveness of low-pressure VM in reducing the PWV and stiffness of the CCA. This suggests that low-pressure VM can be a simple and cost-effective method to reduce cerebrovascular stiffness in a brief interval, without the need for specific environmental conditions.

Evaluation of the coefficient of lateral stress at rest of granular materials under repetitive loading conditions

Although the internal stress state of soils can be affected by repetitive loading, there are few studies evaluating the lateral stress (or K0) of soils under repetitive loading. This study investigates the changes in K0 and directional shear wave velocity (Vs) in samples of two granular materials with different particle shapes during repetitive loading. A modified oedometer cell equipped with bender elements and a diaphragm transducer was developed to measure the variations in the lateral stress and the shear wave velocity, under repetitive loading on the loading and unloading paths. The study produced the following results: (1) Repetitive loading on the loading path resulted in an increase in the K0 of test samples as a function of cyclic loading number (i), and (2) Repetitive loading on the unloading path resulted in a decrease in K0 according to i. The shear wave velocity ratio (i.e. Vs(HH)/Vs(VH), where the first and second letters in parentheses corresponds to the directions of wave propagation and particle motion, respectively, and V and H corresponds to the vertical and horizontal directions, respectively) according to i supports the experimental observations of this study. However, when the tested material was in lightly over-consolidated state, there was an increase in K0 during repetitive loading, indicating that it was the initial K0, rather than the loading path, which is responsible for the change in K0. The power model can capture the variation in the K0 of samples according to i. Notably, the K0 = 1 line acts as the boundary between the increase and decrease in K0 under repetitive loading.

Comparing the stretching technique and the wavelet cross-spectrum technique for measuring stress-induced wave-velocity changes in concrete

Coda wave interferometry (CWI) holds promise as a technique for concrete stress monitoring. This is because the coda, which consists of multiply scattered arrivals, is the result of propagation through the medium over large distances. As such, it is sensitive to both minute structural changes and small velocity changes in that medium. Previous studies focusing on concrete have predominantly utilized the time-domain-based stretching technique to measure travel-time changes. There is, however, a lack of consensus on how to quantify these changes effectively. In this study, we conduct a systematic comparison between two techniques, namely the stretching technique and the wavelet cross-spectrum (WCS) technique, for measuring stress-induced velocity changes in a cylindrical concrete sample. Our comparison focuses on two key aspects: (i) stability against cycle skipping and (ii) consistency in retrieving velocity changes. Experimental results reveal that both the WCS technique and the stretching technique yield consistent velocity changes. In terms of stability, it is challenging to determine which technique performs better, due to differences in the mechanisms triggering cycle skipping. However, when considering waves with frequencies ranging from 50 kHz to 80 kHz, both techniques exhibit comparable performance. Based on our findings, we offer the following recommendations for utilizing these CWI techniques in concrete stress monitoring:For the stretching technique, selecting the time window length based on the wave frequency and the expected magnitude of velocity change.For the WCS technique, operating it in the frequency band where spectral decomposition shows sufficiently high energy in the signal and can accommodate the expected magnitude of velocity change.