Pressure Amplification Research Articles

Blast mitigation using monolithic closed cell aluminium foam

Abstract Blast protection using cellular materials is being actively pursued at research and technology levels. The present work uniquely demonstrates the generation of stress waves, strain waves and mass velocities in monolithic closed cell aluminium foams of different densities and lengths subjected to simulated blast loads and their combined effect on blast attenuation. The foams were assumed to be resting against a rigid end wall. If the numerically calculated stress at the back face was less than the applied stress at the front face, the interaction was termed blast mitigation or attenuation. The results show that ‘pressure mitigation’ occurs for low-density foams whose plastic strength is less than the applied pressure, but pressure amplification for high-density foams whose plastic strength is higher than the applied pressure. The pressure amplification observed in shorter length high density foams transformed to pressure mitigation if the foams were sufficiently long. Based on these results and other stress, strain and velocity related diagnostics, the underlying mechanism behind blast wave amplification/mitigation and its relation with foam density and length is proposed.

E-selectin and asymmetric dimethylarginine plasma levels in adult cyanotic congenital heart disease patients: relation to biochemical parameters, vascular function, and clinical status.

Abstract Background and Aim Patients with cyanosis secondary to congenital heart disease (CHD) are characterized by erythrocytosis and increased blood viscosity, which contributes to endothelial dysfunction, increased arterial stiffness, and impaired vascular function, which may affect the final clinical presentation. Asymmetric dimethylarginine (ADMA) and e-selectin (e-sel) are valuable biomarkers for prognosis of endocardial dysfunction and vascular damage. Their concentration levels in blood serum have the potential to be a rapid and easily accessible tool that reflects the severity of the disease. We aimed to assess e-sel and ADMA levels, their relationship with clinical status, as well as endothelial and vascular function. Methods A cross-sectional study including 36 adult CHD cyanotic patients [(17 males)(42.3 +/- 16.3 years)] with arterial blood oxygen saturation less than 92% and 20 healthy controls [(10 males)( 38.2 +/- 8.5 years)] was performed. All patients underwent clinical examination, blood testing, and cardiopulmonary tests. Endothelial function was assessed using intima-media thickness and flow-mediated dilatation (FMD). Vascular function using applanation tonometry methods was completed while considering aortic systolic pressure, aortic pulse pressure (AoPP), augmentation pressure (AP), augmentation index (AI), pulse pressure amplification (PPampl), and pulse wave velocity (PWV). Results Concentrations of e-sel and ADMA were significantly higher in patients with CHD than in controls (56.3 ± 13.6 ng/mL vs. 15.5 +/- 8.6 ng/mL, p<0.001) and (1.48 ± 0.48 ng/mL vs. 0.46 ± 0.1 ng/mL, p<0.001) respectively. E-sel levels correlated with gender, blood oxygen saturation, red blood cell, hemoglobin concentration, hematocrit, augmentation pressure, forced expiratory one second volume, forced vital capacity, and oxygen uptake. ADMA levels were found to correlate with age only. Conclusions E-sel level, unlike ADMA concentration, reflects the degree of severity of erythrocytosis and hypoxia and, thus, the physical status of patients with cyanotic CHD. E-selectin predicts increased augmentation pressure.Figure 1.A) ROC analysis for e-selectin

Chronopharmacotherapy and correction of central pressure in the aorta, structural and functional state of the left ventricular in patients with arterial hypertension and ischemic stroke

Objective. To evaluate the dynamics of central aortic pressure and the cardioprotective effect of antihypertensive chronopharmacotherapy in patients with arterial hypertension (AH) and ischemic stroke. Materials and methods. The study included 119 patients with AH who has suffered an ischemic stroke; patients were randomized in 2 groups depending on the chronopharmacotherapy option: group 1 (n = 60) – patients who received indapamide retard 1.5 mg and valsartan 160 mg in the morning; group 2 (n = 59) – indapamide retard 1.5 mg in the morning and valsartan 80 mg each in the morning and before bedtime. After 2 months of pharmacotherapy, the achievement of the target level of blood pressure was assessed. In group 1, blood pressure was recorded in 47 (78.3 %), in group 2 – in 56 (94.9 %) patients (p < 0.05). The rest of the respondents, who did not reach the blood pressure target, underwent correction of antihypertensive therapy and were excluded from further follow-up. Accordingly, further follow-up was carried out in 47 patients of group 1 (group 1a) and 56 patients of group 2 (group 2a). Initially and after 12 months of therapy, echocardiography parameters ("ALOKA SSD 2500", Japan), as well as daily blood pressure monitoring with determination of central aortic pressure (Peter Telegin LLC BPLabVasotens, Russia) were performed. The results of the study were processed using the Statistica 12.0 program (StatSoftInc, USA). Results. At the time of inclusion in the study, the main parameters of the central aortic pressure and echocardiography parameters in both groups of patients were equivalent. After 12 months a statistically more significant decrease in the main parameters of the central aortic pressure (average daily systolic and diastolic pressure in the aorta, pulse pressure in the aorta, augmentation index in the aorta, amplification of pulse pressure, duration of the expulsion period, subendocardial blood flow efficiency index), as well as echocardiography indicators was recorded in group 2a (end-systolic and end-diastolic dimensions, thickness of the interventricular septum, thickness of the posterior wall of the left ventricular myocardium, left ventricular myocardial mass, left ventricular myocardial mass index and ejection fraction) (p < 0.05). The left ventricular myocardial geometry normalized during therapy was recorded significantly more often in group 2a than in group 1a (p < 0.05). Conclusion. Two times a day intake of valsartan with thiazidelike diuretic in the morning facilitated more significant improvement of central aortic pressure, echocardiography parameters and as well as an improvement in the geometry of the left ventricular myocardium comparing to just morning intake.

Impact of arterial system alterations due to amputation on arterial stiffness and hemodynamics: a numerical study

Subjects with amputation of the lower limbs are at increased risk of cardiovascular mortality and morbidity. We hypothesize that amputation-induced alterations in the arterial tree negatively impact arterial biomechanics, blood pressure and flow behavior. These changes may interact with other biological factors, potentially increasing cardiovascular risk. To evaluate this hypothesis regarding the purely mechanical impact of amputation on the arterial tree, we used a simulation computer model including a detailed one-dimensional (1D) arterial network model (143 arterial segments) coupled with a zero-dimensional (0D) model of the left ventricle. Our simulations included five settings of the arterial network: (1) 4-limbs control, (2) unilateral amputee (right lower limb), (3) bilateral amputee (both lower limbs), (4) trilateral amputee (lower-limbs and right upper-limb), and (5) quadrilateral amputee (lower and upper limbs). Analysis of regional stiffness, as calculated by pulse wave velocity (PWV) for large-, medium- and small-sized arteries, showed that, while aortic stiffness did not change with increasing degree of amputation, stiffness of medium and smaller-sized arteries increased with greater amputation severity. Despite a staged decrease in cardiac output, the systolic and diastolic blood pressure values increased, resulting in an increase in both central and peripheral pulse pressures but with an attenuation of pulse pressure amplification. The most significant increase in peak systolic pressure and decrease in peak systolic blood flow was observed at the site of the abdominal aorta. Wave separation analysis indicated no changes in the shape of the forward and backward wave components. However, the results from wave intensity analysis showed that with extended amputation, there was an increase in peak forward wave intensity and a rise in the inverse peak of the backward wave intensity, suggesting potential alterations in cardiac hemodynamic load. In conclusion, this simulation study showed that biomechanical and hemodynamic changes in the arterial network geometry could interact with additional risk factors to increase the cardiovascular risk in patients with amputations.

Rapid Amplification of Cerebrospinal Fluid Pressure as a Possible Mechanism for Optic Nerve Sheath Bleeding in Infants With Nonaccidental Head Injury.

Subdural hemorrhage along the optic nerve (ON) is a histopathological indicator of abusive head trauma (AHT) in infants. We sought to determine if this bleeding could be caused by an abrupt increase in intracranial pressure transmitted to cerebrospinal fluid (CSF) at the optic foramen (OF). A theoretical model is developed to simulate the effect of a pressure perturbation of maximal amplitude P applied at the optic foramen for a short duration T on the CSF-filled ON subarachnoid space (ONSAS). The ONSAS is modelled as a fluid-filled channel with an elastic wall representing the flexible ONSAS-arachnoid/dura interface. A constitutive law describing the relationship between CSF pressure and ONSAS deformation is inferred from published measurements. CSF pressure profiles along the ONSAS are examined systematically over a broad range of P and T. The pressure perturbation initiated at the OF produces a pressure wave that stretches the ONSAS. This wave propagates rapidly along the ONSAS toward the scleral end of the ON, where it is reflected back toward the brain. For sufficiently small T a shock wave with amplification up to six times larger than P over a timescale of tens of milliseconds is observed at the scleral end of the ON. Comparatively smaller amplifications are observed for slower perturbations. A sudden increase in CSF pressure in the cranial cavity can cause a rapid expansion of the ONSAS, which may lead to rupture of the bridging blood vessels. Our study predicts a plausible mechanism for subdural hemorrhage that occurs in abusive head trauma in infants.

Haemodynamics of hyperthyroidism: increased cardiac work and findings related to vasodilatation.

Hyperthyroidism increases cardiovascular morbidity and mortality, but the underlying mechanisms are not fully understood. In this study we compared non-invasive haemodynamics between 20 hyperthyroid patients and 60 euthyroid subjects. The measurements were performed median 6 days after the initiation of antithyroid medication when the patients were still hyperthyroid. Three controls matched for age, sex, body mass index, and smoking status were selected for each patient. Recordings were performed during rest and passive head-up tilt using whole-body impedance cardiography, radial pulse wave analysis, and finger blood pressure measurements. Systolic and diastolic blood pressures in the aorta and radial artery were similar in hyperthyroid and euthyroid subjects, while finger blood pressure was 16/12 mmHg lower in hyperthyroidism (p<0.001). Pulse wave velocity and aortic pulse pressure were similar, but radial pulse pressure was ~5 mmHg higher in hyperthyroidism (p=0.040) due to augmented amplification (p=0.045). Systemic vascular resistance was reduced (-18%), whereas heart rate (+19 beats/min), cardiac index (+28%), and left cardiac work (+31%) were increased in hyperthyroidism (p<0.001). Subendocardial viability ratio, reflecting the balance between coronary perfusion and pressure load, was reduced by 19% in hyperthyroidism (p<0.001). Compared with euthyroid subjects, hyperthyroid patients presented with reductions in systolic and diastolic finger blood pressures (p<0.001), and higher increase in heart rate (p=0.014) during upright posture. Hyperthyroid patients exhibited hyperdynamic circulation, reduced vascular resistance, reduced peripheral but not central blood pressure, and higher pulse pressure amplification. Furthermore, left cardiac workload was increased in parallel with unfavourable changes in coronary perfusion conditions.

Comparison of arterial stiffness index predictors in perimenopausal and postmenopausal women

ABSTRACT The present cross-sectional study aimed to compare climacteric symptoms and arterial stiffness indices between perimenopausal and postmenopausal women. The study sample comprised 70 healthy female participants, including 27 perimenopausal (49.8 ± 3.8 years) and 43 postmenopausal (55.7 ± 4 years) individuals. Validated methods were used to assess physical activity level, quality of life, climacteric symptoms, and anthropometric data. Arterial stiffness parameters were measured using Mobil-O-Graph. Pulse wave velocity (PWV) had a higher mean in the postmenopausal group than in the perimenopause group [8.04 m/s (SD 0.79) vs 7.01 m/s (SD 0.78), p < .001). PWV was strongly correlated with peripheral (r = 0.619) and central (r = 0.632) Systolic Blood Pressure (SBP) in postmenopausal group and an even stronger correlation was observed in perimenopausal group (r = 0.779 pSBP and 0.782 cSBP). BMI was a risk predictor in the perimenopausal group contributing positively to increase Pulse Pressure Amplification (PPA) (0.458, p < .05). In postmenopausal women, heart rate (HR) was a stronger predictor for central SBP, cardiac output, and total vascular resistance, whereas perimenopausal women HR influenced central diastolic blood pressure and PPA. Vascular changes initiating during perimenopause may contribute to the development of cardiovascular pathologies in the postmenopausal period. Further research with larger, representative samples is warranted to corroborate these findings.

Application of pressure small signals extraction and amplification technology in abandoned well pattern for geothermal energy extraction and H2 storage: Numerical modeling and economic analysis

Using abandoned reservoirs for geothermal energy development and H2 storage is economical. The impact of complex fractures from long-term oil and gas extraction on geothermal energy and H2 storage is not yet clearly understood. Here, a pressure small signals extraction and amplification (PSEA) technology is developed to improve reservoir monitoring accuracy. This technology is capable of coupling many pressure transient analysis models to invert parameters for multiple scenarios. This work establishes numerical models to simulate the effects of geothermal energy extraction and H2 storage over 5000 days. Results show that this technology improves the accuracy of inverted parameters by 4–14 times. This technology adjusts the production temperature differences in a single injection-production system from 1.4K to 6.5K and the net heat power from 0.25 MW to 1.1 MW, and it can also identify an early low-rate H2 storage phase. The Non-Sorting Genetic Algorithm II calculates that the PSEA technology brings economic benefits of $704,000 and $352,000 for geothermal energy extraction and H2 storage in a single injection-production system. In conclusion, the developed monitoring technology and models improve accuracy in assessing geothermal energy development and H2 storage, preventing failures in residential heating or H2 storage projects.

Progression in central blood pressure and hemodynamic parameters and relationship with cardiovascular risk factors in a Spanish population. EVA follow-up study.

The progression of Central Blood Pressure (CBP) values and central hemodynamic parameters and its relationship with cardiovascular risk factors is quite unknown. We sought to investigate this association in a Spanish adult population without cardiovascular diseases. Prospective observational research with a five-year follow-up. Randomly sampled 501 individuals (mean age 56±14 years, 50.3% women). After five years, 480 individuals had a follow-up. Measurements taken using the SphygmoCor® (AtCor Medical Pty Ltd., Head Office,West Ryde, Australia), following all the recommendations established in the "International task force"1, giving an estimate of central blood pressure relative to measured brachial blood pressure (type 1 device). Progressions during follow-up: central systolic blood pressure (cSBP): 4.16±13.71 mmHg; central diastolic blood pressure (cDBP): 2.45±11.37 mmHg; central pulse pressure (cPP): 1.72±12.43 mmHg; pulse pressure amplification (PPA): 2.85±12.20 mmHg; ejection duration (ED): 7.00±47.87ms; subendocardial viability ratio (SEVR): -8.04±36.24%. In multiple regression analysis: cSBP positively associated with: BMI (β=0.476); waist size (β=0.159); number of cigarettes per day (β=0.192). Inversely associated with peripheral systolic blood pressure (β=-0.282). cDBP increase positively associated with number of cigarettes per day (β=0.174). Inversely associated with peripheral diastolic blood pressure (β=-0.292). cPP increase positively associated with BMI (β=0.330). Inversely associated with peripheral pulse pressure (β=-0.262). PPA increase positively associated with: BMI (β=0.276); number of cigarettes per day (β=0.281). ED progress inversely associated with basal plasma glucose (β=-0.286). All measures increased except for SEVR. Progressions in CBP and PPA were positively associated with anthropometric parameters and number of cigarettes and CBP inversely associated with peripheral blood pressure, although this association was different according to sex.

E-Selectin and Asymmetric Dimethylarginine Levels in Adult Cyanotic Congenital Heart Disease: Their Relation to Biochemical Parameters, Vascular Function, and Clinical Status.

Background and Aim: Patients with cyanosis secondary to congenital heart disease (CHD) are characterized by erythrocytosis and increased blood viscosity, which contribute to endothelial dysfunction, increased arterial stiffness, and impaired vascular function, which may affect the final clinical presentation. Asymmetric dimethylarginine (ADMA) and e-selectin (e-sel) are valuable biomarkers for endothelial and vascular dysfunction. Their concentration levels in blood serum have the potential to be an accessible tool that reflects the severity of the disease. We aimed to assess e-sel and ADMA levels and their relationship with the clinical status and endothelial and vascular function. Methods: A cross-sectional study, including 36 adult CHD cyanotic patients [(17 males) (42.3 ± 16.3 years)] with an arterial blood oxygen saturation less than 92% and 20 healthy controls [(10 males) (38.2 ± 8.5 years)], was performed. All the patients underwent a clinical examination, blood testing, and cardiopulmonary tests. Their endothelial function was assessed using the intima media thickness and flow-mediated dilatation. Vascular function, using applanation tonometry methods, was determined using the aortic systolic pressure, aortic pulse pressure, augmentation pressure, augmentation index, pulse pressure amplification, and pulse wave velocity. Results: The concentrations of e-sel and ADMA were significantly higher in the patients with CHD. The E-sel levels correlated positively with red blood cells, hemoglobin concentration, hematocrit, and augmentation pressure; they correlated negatively with blood oxygen saturation, the forced expiratory one-second volume, forced vital capacity, and oxygen uptake. The ADMA levels were found to correlate only with age. Conclusions: The E-sel level, unlike ADMA concentration, reflects the severity of erythrocytosis and hypoxia and, thus, the physical status of patients with cyanotic CHD.

Concerning the Parameterization of Geometric and Criticality Effects on Detonation Amplification

This study investigates the role of geometric effects and detonation criticality on the behavior of a detonation transition through an area expansion of finite length. Three reinitiation behaviors that result in an amplified pressure impulse were observed and are referred to as steady, spike, and endwall amplification. Steady amplification was characterized by an amplification event with a peak pressure impulse 2 times that of the inlet detonation, followed by a near-linear attenuation toward Chapman–Jouguet conditions. Spike amplification displayed a larger peak pressure amplification that was 3 to 5 times greater than the inlet detonation, followed by a rapid and nonlinear attenuation. Endwall behavior represents a Craven–Grieg deflagration to detonation transition scenario. These behaviors are shown to be factors of area expansion ratio and the degree to which the incoming detonation is subcrtical. A decoupling parameter, Ψd, was devised to combine these effects into a single correlation metric. The finite length of the expansion chamber also plays a role in the reinitiation behavior as observed by the endwall reinitiation behavior. A critical chamber length parameter was devised to explain this behavior and then theorized to have a relationship to Ψd with this being explored theoretically and with the limited data set available.

Shaking table test for near-valley underground station: Influence of diaphragm walls

Diaphragm walls are commonly employed as a permanent support for the building of metro stations near urban valley, and in conjunction with the interior sidewalls of the station structure to withstand the pressure from surrounding soils. Despite their prevalent use, the effect of underground diaphragm walls on the seismic response of stations is not yet fully understood. In this paper, a series of 1-g shaking table tests is designed to investigate the seismic response of a near-valley station with underground diaphragm walls within the elastic range. Modeling the stratum-structure-diaphragm walls system is accomplished by employing granular concrete reinforced with galvanized steel wires and synthetic model soils, and a station without diaphragm walls is included, serving as a benchmark for comparative analysis to understand the influence of diaphragm walls on the seismic behavior of the station. The experiment was designed for three depth-to-width ratios (DWRs), i.e. 1/3, 1/4, and 1/8, of arc-shaped valley topography, as well as the seismic excitations for the test include actual seismic records with the amplitude of 0.2 g, 0.4 g, and 0.8 g, respectively. Results show that the underground diaphragm walls enhance the lateral stiffness of the near-valley station compared to structures without diaphragm walls, and thus significantly reducing the racking deformation of structure during earthquakes. The presence of diaphragm wall would decrease the amplification of dynamic earth pressure caused by valley effect at the structural sidewalls, and significantly reduce the lateral vibration and shear effect of the station near a valley with a larger DWR. Notably, bending moment response at the connection between the diaphragm walls and structural sidewalls are dramatically amplified under strong seismic loading, and such adverse effects gradually increase with the DWR of the valley.

Does stress from incarceration of family and friends contribute to signs of early vascular ageing in African American women?

BackgroundEarly vascular ageing (EVA) contributes to elevated risk of cardiovascular disease (CVD), which disproportionately affects African American women. Incarceration, an event disproportionately impacting African Americans, may be a stressor contributing...

Numerical study of cavitation shock wave emission in the thin liquid layer by power ultrasonic vibratory machining

In the field of power ultrasonic vibration processing, the thin liquid layer nestled between the tool head and the material serves as a hotbed for cavitation shock wave emissions that significantly affect the material's surface. The precise manipulation of these emissions presents a formidable challenge, stemming from a historical deficit in the quantitative analysis of both the ultrasonic enhancement effect and the shock wave intensity within this niche environment. Our study addresses this gap by innovatively modifying the Gilmore-Akulichev equation, laying the groundwork for a sophisticated bubble dynamics model and a pioneering shock wave propagation model tailored to the thin liquid layer domain. Firstly, our study investigated the ultrasound enhancement effect under various parameters of thin liquid layers, revealing an amplification of ultrasound pressure in the thin liquid layer area by up to 7.47 times. The mathematical model was solved using the sixth-order Runge–Kutta method to examine shock wave velocity and pressure under different conditions. our study identified that geometric parameters of the tool head, thin liquid layer thickness, ultrasonic frequency, and initial bubble radius all significantly influenced shock wave emission. At an ultrasonic frequency of 60 kHz, the shock wave pressure at the measurement point exhibited a brief decrease from 182.6 to 179.5 MPa during an increase. Furthermore, rapid attenuation of the shock wave was found within the range of R0-3R0 from the bubble wall. This research model aims to enhance power ultrasonic vibration processing technology, and provide theoretical support for applications in related fields.

An outcome-driven threshold for pulse pressure amplification

Pulse pressure amplification (PPA) is the brachial-to-aortic pulse pressure ratio and decreases with age and cardiovascular risk factors. This individual-participant meta-analysis of population studies aimed to define an outcome-driven threshold for PPA. Incidence rates and standardized multivariable-adjusted hazard ratios (HRs) of cardiovascular and coronary endpoints associated with PPA, as assessed by the SphygmoCor software, were evaluated in the International Database of Central Arterial Properties for Risk Stratification (n = 5608). Model refinement was assessed by the integrated discrimination (IDI) and net reclassification (NRI) improvement. Age ranged from 30 to 96 years (median 53.6). Over 4.1 years (median), 255 and 109 participants experienced a cardiovascular or coronary endpoint. In a randomly defined discovery subset of 3945 individuals, the rounded risk-carrying PPA thresholds converged at 1.3. The HRs for cardiovascular and coronary endpoints contrasting PPA < 1.3 vs ≥1.3 were 1.54 (95% confidence interval [CI]: 1.00–2.36) and 2.45 (CI: 1.20–5.01), respectively. Models were well calibrated, findings were replicated in the remaining 1663 individuals analyzed as test dataset, and NRI was significant for both endpoints. The HRs associating cardiovascular and coronary endpoints per PPA threshold in individuals <60 vs ≥60 years were 3.86 vs 1.19 and 6.21 vs 1.77, respectively. The proportion of high-risk women (PPA < 1.3) was higher at younger age (<60 vs ≥60 years: 67.7% vs 61.5%; P < 0.001). In conclusion, over and beyond common risk factors, a brachial-to-central PP ratio of <1.3 is a forerunner of cardiovascular coronary complications and is an underestimated risk factor in women aged 30–60 years. Our study supports pulse wave analysis for risk stratification.

Effects of steady-state fluid-structure interactions on air-supported membrane structures subjected to wind actions

With the perspective of static aeroelasticity, steady-state influences of fluid-structure interaction (FSI) on wind loads and responses of rectangular-planed air-supported membrane structure (ASMS) are investigated in this study. Steady-state FSI simulations are performed by coupling Reynolds-averaged computational fluid dynamics solving wind loads and static finite element analysis solving structural deformations. The feasibility of these simulations is validated with wind tunnel tests concerning time-averaged results. In contrast to analysis without static aeroelasticity, significant variations in wind pressure distributions and amplifications on structural wind responses due to steady-state FSI effects are observed. Subsequently, influencing factors and mechanisms of steady-state FSI effects are analyzed. These time-averaged effects are more significant with the increasing magnitude of structural wind actions, lower internal pressures and less membrane tensile stiffness. Though unlikely to induce irreversible effects as shell structures, the buckling of ASMS can make steady-state FSI more pronounced because of the coupling between stronger flow separation and larger membrane deformations. Accompanied with steady-state FSI, such buckling effect usually contributes to varying locations of the structural maximum responses and noticeable increases in response amplification factors, which deserves attentions in practice. Practically, it is realizable to evaluate these steady-state FSI effects above with simulations because of the much lower computational cost and reliable accuracy.

Arterial stiffness is associated with prehypertension in both non-hypertensives and treated hypertensives–A matched case control study

BackgroundPrehypertension (PHT) is a cardiovascular health risk defined by blood pressure (BP). Arterial stiffness (AS) provides beyond brachial BP inference on vascular ageing and pulse wave analysis (PWA) can measure it non-invasively.We compared association between AS and PHT using age and gender matched case-controls. MethodsThis is a sub analysis of previous PWA studies of hypertensives and non-hypertensives. Using oscillometric PWA by Mobil-o-Graph (IEM, Stolberg, Germany), parameters of AS (augmentation pressure and index, reflection magnitude, aortic pulse wave velocity, pulse pressure amplification), brachial hemodynamics (BH), and central hemodynamics (CH; aortic BP, cardiac output related parameters, stroke work) were derived. Age and gender matched case controls were compared as: 1) Nonhypertensives with BP at prehypertensive level (PHT) versus normotensives (NT) (n = 217 each), 2) Under treatment hypertensives with BP at prehypertensive level (PHT-T) versus untreated, nonhypertensives with BP at prehypertensive level (PHT-UT) (n = 74 each). ResultsPHTs had higher AS, BH and CH than NTs, with statistical significance for all but few parameters. PHT-T had comparable BH but higher AS, CH than PHT-UT with significance for few parameters. ConclusionPulse wave analysis derived arterial stiffness is associated with prehypertension compared to normal, after age and gender matching. In hypertensives, arterial stiffness is significantly higher despite being treated to prehypertension level as compared to control. It hints arterial stiffness to be better parameter than brachial BP to study prehypertension.

Pulse pressure amplification as a predictor of cardiovascular risk in shift workers: an analysis based on PARTAGE

Pulse pressure amplification as a predictor of cardiovascular risk in shift workers: an analysis based on PARTAGE

Acoustic Pressure Amplification through In-Duct Sonic Black Holes

Acoustic detection of machinery defaults from in-duct measurements is of practical importance in many areas, such as the health assessment of turbines in ventilation systems or engine testing in the surface and air transport sectors. This approach is, however, impeded by the low signal-to-noise ratio (SNR) observed in such environments. In this study, it is proposed to exploit the slow sound effect of Sonic Black Hole (SBH) ducted silencers to enhance the sensing of incident pulse acoustic signals with low SNR. It is found from transfer matrix and finite element modelling that fully opened SBH silencers with perforated skin interfaces are able to substantially enhance an incident pulse amplitude while channeling an air flow. We demonstrate that the graded depths of the SBH cavities provide rainbow spectral decomposition and amplification of the incident pulse frequency components, provided that impedance matching, slow sound, and critically coupled conditions are met. In-duct experiments showed the ability of a 3D printed SBH silencer to simultaneously enhance acoustic sensing and fully trap the pulse spectral components in the SBH cavities in the presence of a low-speed flow. This study opens up new avenues for the development of dual-purpose silencers designed for acoustic monitoring and noise control in duct systems without obstructing the air flow.

In silico modelling of stroke volume, cardiac output and systemic vascular resistance in cardiovascular safety pharmacology studies by telemetry

The principle of proportionality of the systolic area of the central aortic pressure to stroke volume (SV) has been long known. The aim of the present work was to evaluate an in silico solution derived from this principle for modelling SV (iSV model) in cardiovascular safety pharmacology studies by telemetry. Blood pressure was measured in the abdominal aorta in accordance with standard practice. Central aortic pressure was modelled from the abdominal aortic pressure waveform using the N-point moving average (NPMA) method for beat-to-beat estimation of SV. First, the iSV was compared to the SV measured by ultrasonic flowmetry in the ascending aorta (uSV) after various pharmacological challenges in beagle dogs anaesthetised with etomidate/fentanyl. The iSV showed minimal bias (0.2 mL i.e. 2%) and excellent agreement with uSV. Then, previous telemetry studies including reference vasoactive and inotropic compounds were retrospectively reanalysed to model drug effects on stroke volume (iSV), cardiac output (iCO) and systemic vascular resistance (iSVR). Among them, the examples of nicardipine and isoprenaline highlight risks of erroneous or biased estimation of drug effects from the abdominal aortic pressure due to pulse pressure amplification. Furthermore, the examples of verapamil, quinidine and moxifloxacin show that iSV, iCO and iSVR are earlier biomarkers than blood pressure itself for predicting drug effect on blood pressure. This in silico modelling approach included in vivo telemetry safety pharmacology studies can be considered as a New Approach Methodology (NAM) that provides valuable additional information and contribute to improving non-clinical translational research to the clinic.