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"Pressure data"
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Characteristics of an atypical large-meander path of the Kuroshio current south of Japan formed in September 2017
by
Ariyoshi, Keisuke
,
Hasegawa, Takuya
,
Yamashita, Yusuke
in
Baroclinic instability
,
Bottom pressure
,
Instability
2019
Since September 2017, the Kuroshio has taken a large-meander (LM) path in the region south of Japan. We examined characteristics of the 2017–present LM path in comparison with previous LM paths, using tide gauge, altimetric sea surface height, and bottom pressure data. The 2017–present LM path was formed from a path passing through a channel south of Hachijo-jima Island, while a typical LM path originated from a path through a channel north of Miyake-jima Island. The meander trough of this atypical path was found to be shifted far to the east and to vary on a timescale of months. These characteristics are different from those of a typical LM path but they are similar to those of the 1981–1984 LM path. Therefore, we identified two types of LM path; a stable and unstable LM paths. The 2017–present unstable type large meander has a zonal scale greater than that of the 2004–2005 stable type large meander and protrudes from the eastern boundary of the Shikoku Basin, i.e., Izu-Ogasawara Ridge. No significant bottom pressure depression was observed, associated with the formation of the 2017–present LM path, indicating that baroclinic instability was not important in the formation of this LM path. Due to no significant bottom steering, even during the 2017–present LM period, a mesoscale current path disturbance occurred southeast of Kyushu, propagated eastward, and amplified the offshore displacement of the Kuroshio.
Journal Article
Health Outcomes of Continuous Positive Airway Pressure versus Oral Appliance Treatment for Obstructive Sleep Apnea: A Randomized Controlled Trial
by
MIHAILIDOU, Anastasia S
,
MARKS, Guy B
,
YEE, Brendon J
in
Adult
,
Aged
,
Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy
2013
Continuous positive airway pressure (CPAP) and mandibular advancement device (MAD) therapy are commonly used to treat obstructive sleep apnea (OSA). Differences in efficacy and compliance of these treatments are likely to influence improvements in health outcomes.
To compare health effects after 1 month of optimal CPAP and MAD therapy in OSA.
In this randomized crossover trial, we compared the effects of 1 month each of CPAP and MAD treatment on cardiovascular and neurobehavioral outcomes.
Cardiovascular (24-h blood pressure, arterial stiffness), neurobehavioral (subjective sleepiness, driving simulator performance), and quality of life (Functional Outcomes of Sleep Questionnaire, Short Form-36) were compared between treatments. Our primary outcome was 24-hour mean arterial pressure. A total of 126 patients with moderate-severe OSA (apnea hypopnea index [AHI], 25.6 [SD 12.3]) were randomly assigned to a treatment order and 108 completed the trial with both devices. CPAP was more efficacious than MAD in reducing AHI (CPAP AHI, 4.5 ± 6.6/h; MAD AHI, 11.1 ± 12.1/h; P < 0.01) but reported compliance was higher on MAD (MAD, 6.50 ± 1.3 h per night vs. CPAP, 5.20 ± 2 h per night; P < 0.00001). The 24-hour mean arterial pressure was not inferior on treatment with MAD compared with CPAP (CPAP-MAD difference, 0.2 mm Hg [95% confidence interval, -0.7 to 1.1]); however, overall, neither treatment improved blood pressure. In contrast, sleepiness, driving simulator performance, and disease-specific quality of life improved on both treatments by similar amounts, although MAD was superior to CPAP for improving four general quality-of-life domains.
Important health outcomes were similar after 1 month of optimal MAD and CPAP treatment in patients with moderate-severe OSA. The results may be explained by greater efficacy of CPAP being offset by inferior compliance relative to MAD, resulting in similar effectiveness. Clinical trial registered with https://www.anzctr.org.au (ACTRN 12607000289415).
Journal Article
Pressure Dependence of Permeability in Cracked Rocks: Experimental Evidence of Non‐Linear Pore‐Pressure Gradients From Local Measurements
2024
Understanding the coupling between rock permeability, pore pressure, and fluid flow is crucial, as fluids play an important role in the Earth's crustal dynamics. We measured the distribution of fluid pressure during fluid‐flow experiments on two typical crustal lithologies, granite and basalt. Our results demonstrate that the pore‐pressure distribution transitions from a linear to a non‐linear profile as the imposed pore‐pressure gradient is increased (from 2.5 to 60 MPa) across the specimen. This non‐linearity results from the effective pressure dependence of permeability, for which two analytical formulations were considered: an empirical exponential and a new micromechanics‐based model. In both cases, the non‐linearity of pore pressure distribution is predicted. Using a compilation of permeability versus Terzaghi's effective pressure data for granites and basalts, we show that our micromechanics‐based model has the potential to predict the pore pressure distribution over the range of effective pressures expected within the brittle crust. Plain Language Summary Fluids distributions and fluid migrations play an important role in the Earth's crustal dynamics and how fluids migrate through a rock will depend primarily on permeability. However, the permeability of crustal rocks may exhibit important pressure dependence, because cracks and fractures will increasingly close with increasing tectonic pressure. In this experimental study, we show that the couplings between increasing pressure, crack closure, and permeability reduction may result in non‐linear pore pressure distributions on a rock specimen at the laboratory scale, which confirms for the first time pioneering theoretical and experimental works. Two simple analytical expressions of the pressure dependence of permeability predict this non‐linearity. One empirical expression, most commonly used in the literature, takes the form of an exponential. The second one, a new model, based on crack micromechanics, was developed within this work and shown to outperform the exponential formulation at low Terzaghi's effective pressure. Key Points Pore pressure was measured locally in rocks exhibiting pressure‐dependent permeability We observed a transition from linear to nonlinear pore pressure distribution with increasing fluid pressure gradients A new, micromechanics‐based, analytical model was developed for the pressure dependence of permeability in microcracked rocks
Journal Article
Analysis of centre of pressure trajectories and plantar pressure distribution to map development of foot-ground interactions from new to confident walking infants
by
Price, Carina
,
Montagnani, Eleonora
,
Morrison, Stewart C.
in
Analysis
,
Babies
,
Biology and Life Sciences
2025
Independent walking is a crucial milestone, allowing infants to explore their environment efficiently. This phase introduces complex foot-ground interactions. However, previous studies have focused on either center of pressure (CoP) or plantar pressure distribution alone, often losing critical information. The impact of variables like body weight, height, and foot size on pressure distribution in infants remains also underexplored. Our study uses continuous statistical approaches to comprehensively analyze anterior-posterior (AP) and medio-lateral (ML) trajectories of CoP and plantar pressure distribution in infancy, mapping foot-ground interactions from new to confident walking stages. Thirty-nine infants walked across an EMED xl platform as new and then confident walkers. Frames of pressure steps were exported and processed in Matlab 2019b. Upon data normality assessment, AP and ML trajectories of new and confident walking steps were compared with parametric two-sample paired SPM1d t-test. Plantar pressure distribution between new and confident walking were compared using the nonparametric two-sample paired SPM1d t-test. Nonparametric linear regression analysis at pixel-level considered variables like body weight, height, foot dimensions, and walking experience, ensuring only non-correlated items were included. Our analyses revealed significant changes in CoP and plantar pressure distribution from new to confident walkers. New walkers initially contact the ground with the central part of their foot, while confident walkers show a more posterior initial contact. Confident walkers also exhibit more medial heel contact and a progression of CoP trajectories closer to the foot’s longitudinal axis. Regression analysis indicated that increasing walking experience significantly predicts higher pressure in the lateral and central forefoot. These findings underscore the importance of combining multi-segment joint analysis with plantar pressure data to fully understand foot development during infancy. This project highlighted key aspects of the unique biomechanics of infants’ foot development, emphasizing the need for further research to enhance understanding and inform clinical practices.
Journal Article
Optimizing footwear for the diabetic foot: Data-driven custom-made footwear concepts and their effect on pressure relief to prevent diabetic foot ulceration
by
Paardekooper, Irma
,
Zwaferink, Jennefer B. J.
,
Berendsen, Heleen A.
in
Athletic shoes
,
Biology and Life Sciences
,
CAD-CAM systems
2020
To assess the effect of data-driven custom-made footwear concepts on plantar pressure relief to prevent diabetic foot ulceration.
Twenty-four neuropathic diabetic patients at high risk of foot ulceration were measured for in-shoe plantar pressures during walking in four data-driven custom-made footwear conditions, an athletic shoe and an off-the-shelf non-therapeutic shoe. Two evidence-based footwear conditions (Shoe-A; Insole-A) follow a scientific-based design protocol, are handmade, and use in-shoe plantar pressure guided optimization. One evidence-based insole condition (Insole-B) uses a barefoot plantar pressure and 3D foot shape-based computer-assisted design and manufacturing (CADCAM) routine. And one insole condition (Insole-C) uses a barefoot and in-shoe plantar pressure and 3D foot shape-based CADCAM design and optimization routine. Patient satisfaction was scored on walking comfort, shoe fit, weight and appearance.
All data-driven footwear conditions significantly reduced metatarsal head peak pressure compared with the non-therapeutic shoe (17-53% relief). Shoe-A and Insole-A showed the lowest metatarsal head peak pressures (mean 112-155 kPa, 90-98% of cases <200 kPa), significantly lower than for Insole-B and Insole-C (mean 119-199 kPa, 52-100% <200 kPa). Patient satisfaction was not significantly different between footwear concepts.
This study proves the offloading efficacy of a scientific-based, handmade, and in-shoe plantar pressure data-driven approach to custom-made footwear design, and advocates its implementation to optimize diabetic footwear for plantar foot ulcer prevention.
Journal Article
Mapping Pressure Surge Source in Urban Water Networks: Integrating Low‐ and High‐Frequency Pressure Data With an Illustrative Real Case Study
2024
This paper introduces a novel methodology that integrates low‐ and high‐frequency pressure monitoring in the parts of the urban water distribution network characterized by the largest number of repairing operations. This integrated approach aims to pinpoint the source and characterize potentially dangerous pressure variations. The actual behavior of a real operational water distribution network is considered as an example to verify the effectiveness of the proposed methodology. The analysis of the acquired pressure signals allows for mapping frequent pressure surges and identifying their source in the functioning conditions of a big user. Notwithstanding these pressure variations are not overly large, according to the literature, their near‐continuous nature poses a risk of inducing pipe breaks, and then leakage, due to fatigue. The proposed method integrating routine low‐frequency measurements with targeted high‐frequency surveys provides a cost‐effective, proactive management strategy. Key Points A method is proposed for detecting transient source in Urban Water Distribution Networks Low‐frequency pressure monitoring initially identifies the most pressure‐stressed section in a high‐maintenance area High‐frequency pressure monitoring allows localizing the transient source
Journal Article
Cost-effectiveness of high flow nasal cannula therapy versus continuous positive airway pressure for non-invasive respiratory support in paediatric critical care
by
Grieve, Richard
,
Sadique, Zia
,
Darnell, Robert
in
Cannula - economics
,
Cannula - standards
,
Cannula - statistics & numerical data
2024
Background
High flow nasal cannula therapy (HFNC) and continuous positive airway pressure (CPAP) are two widely used modes of non-invasive respiratory support in paediatric critical care units. The FIRST-ABC randomised controlled trials (RCTs) evaluated the clinical and cost-effectiveness of HFNC compared with CPAP in two distinct critical care populations: acutely ill children (‘step-up’ RCT) and extubated children (‘step-down’ RCT). Clinical effectiveness findings (time to liberation from all forms of respiratory support) showed that HFNC was non-inferior to CPAP in the step-up RCT, but failed to meet non-inferiority criteria in the step-down RCT. This study evaluates the cost-effectiveness of HFNC versus CPAP.
Methods
All-cause mortality, health-related Quality of Life (HrQoL), and costs up to six months were reported using FIRST-ABC RCTs data. HrQoL was measured with the age-appropriate Paediatric Quality of Life Generic Core Scales questionnaire and mapped onto the Child Health Utility 9D index score at six months. Quality-Adjusted Life Years (QALYs) were estimated by combining HrQoL with mortality. Costs at six months were calculated by measuring and valuing healthcare resources used in paediatric critical care units, general medical wards and wider health service. The cost-effectiveness analysis used regression methods to report the cost-effectiveness of HFNC versus CPAP at six months and summarised the uncertainties around the incremental cost-effectiveness results.
Results
In both RCTs, the incremental QALYs at six months were similar between the randomised groups. The estimated incremental cost at six months was − £4565 (95% CI − £11,499 to £2368) and − £5702 (95% CI − £11,328 to − £75) for step-down and step-up RCT, respectively. The incremental net benefits of HFNC versus CPAP in step-down RCT and step-up RCT were £4388 (95% CI − £2551 to £11,327) and £5628 (95% CI − £8 to £11,264) respectively. The cost-effectiveness results were surrounded by considerable uncertainties. The results were similar across most pre-specified subgroups, and the base case results were robust to alternative assumptions.
Conclusions
HFNC compared to CPAP as non-invasive respiratory support for critically-ill children in paediatric critical care units reduces mean costs and is relatively cost-effective overall and for key subgroups, although there is considerable statistical uncertainty surrounding this result.
Journal Article
High flow nasal cannula (HFNC) versus nasal continuous positive airway pressure (nCPAP) for the initial respiratory management of acute viral bronchiolitis in young infants: a multicenter randomized controlled trial (TRAMONTANE study)
by
Afanetti, Mickael
,
Douillard, Aymeric
,
Essouri, Sandrine
in
Acute Disease
,
Anesthesiology
,
Babies
2017
Purpose
Nasal continuous positive airway pressure (nCPAP) is currently the gold standard for respiratory support for moderate to severe acute viral bronchiolitis (AVB). Although oxygen delivery via high flow nasal cannula (HFNC) is increasingly used, evidence of its efficacy and safety is lacking in infants.
Methods
A randomized controlled trial was performed in five pediatric intensive care units (PICUs) to compare 7 cmH
2
O nCPAP with 2 L/kg/min oxygen therapy administered with HFNC in infants up to 6 months old with moderate to severe AVB. The primary endpoint was the percentage of failure within 24 h of randomization using prespecified criteria. To satisfy noninferiority, the failure rate of HFNC had to lie within 15% of the failure rate of nCPAP. Secondary outcomes included success rate after crossover, intubation rate, length of stay, and serious adverse events.
Results
From November 2014 to March 2015, 142 infants were included and equally distributed into groups. The risk difference of −19% (95% CI −35 to −3%) did not allow the conclusion of HFNC noninferiority (
p
= 0.707). Superiority analysis suggested a relative risk of success 1.63 (95% CI 1.02–2.63) higher with nCPAP. The success rate with the alternative respiratory support, intubation rate, durations of noninvasive and invasive ventilation, skin lesions, and length of PICU stay were comparable between groups. No patient had air leak syndrome or died.
Conclusion
In young infants with moderate to severe AVB, initial management with HFNC did not have a failure rate similar to that of nCPAP. This clinical trial was recorded in the National Library of Medicine registry (NCT 02457013).
Journal Article
Spatiotemporal localization of sex difference in plantar pressure distribution during self paced walking in healthy Japanese adults
2026
There is notable sex difference in the manner of locomotion, but researchers are yet to obtain the comprehensive information about the biomechanical difference in gait pattern between males and females. The present study aimed to investigate sex differences in plantar pressure distribution during self-paced walking using a cluster-based permutation approach.
Plantar pressure data were collected from 24 healthy males and 68 healthy females using a pressure-sensor footplate. Group comparisons were conducted for basic gait parameters as well as pressure-related metrics, including maximum force, peak pressure, and contact area size. Additionally, time-series characteristics of total force were compared between sexes. A cluster-based permutation test was used to identify spatial and temporal regions with significant sex differences in plantar pressure distribution at high resolution.
Analyses revealed that females exhibited shorter step durations and higher cadence compared to males, attributable in part to differences in the duration of the late stance phase. Females also demonstrated higher weight-normalized plantar pressures across most of the stance phase. Sex-specific differences in plantar pressure distribution were localized to the calcaneal and second metatarsal regions.
Spatially localized pattern of sex difference in the plantar pressure indicates that biomechanical factors may contribute to the sex difference in the incidence rates of clinical conditions such as stress fracture. There was also a hitherto unreported pattern of sex difference in the time-series of total force, that may be related to sex-specific strategy to keep a self-preferred walking speed.
Journal Article
Pore‐Scale Fluid Dynamics Resolved in Pressure Fluctuations at the Darcy Scale
by
Krevor, Samuel
,
Tchelepi, Hamdi
,
Roberts, Gareth G.
in
Carbon dioxide
,
Fluctuations
,
Fluid dynamics
2023
Complex pore‐scale dynamics have been observed during multiphase flow through porous rocks. These dynamics are not incorporated in large scale models for the migration and trapping of subsurface fluids such as CO2 or hydrogen. We show that fluctuations in pressure measured at the core‐scale (centimeters) can reflect fluid displacements at the pore‐scale (millimeters). The spectral characteristics of pressure data are shown to depend on the flow dynamics, the size of the rock sample, and the heterogeneity of the pore space. These results show that pressure data, transformed into the time‐frequency domain using wavelets, provides information about flow dynamics, across scales, that are otherwise challenging to acquire. Plain Language Summary Understanding the flow of fluid in porous rocks is crucial for the safe, long‐term, storage of CO2 and hydrogen. Complex fluid flow has been observed in small pores. However, imaging limitations prevent direct observation of such dynamics in larger samples. As such, small‐scale flow remains a considerable source of uncertainty for predicting the underground storage or movement of fluid. In the absence of suitable imaging techniques, we demonstrate how flow dynamics at smaller scales can be explored by analyzing pressure data and its fluctuations using mathematical techniques. We apply this approach to larger samples and discover that pressure fluctuations contain useful information about flow dynamics, sample size, and rock composition that are often otherwise unavailable. Key Points Pore‐scale dynamics can be linked to pressure fluctuations measured across the core The spectral signature of the pressure fluctuations can be used to classify the dominant flow regime By exploring the spectral signature of pressure fluctuations at the larger scale, we are able to infer the underlying pore‐scale dynamics
Journal Article