Mean Value Of Velocity Research Articles

Two-dimensional shear wave elastography can improve the diagnostic accuracy of ultrasonography in acute appendicitis.

We aimed to evaluate the effectiveness of combining 2-dimensional shear wave elastography (2D-SWE) with ultrasonography (US) in diagnosing acute appendicitis in patients with suspected acute appendicitis. Clinical and laboratory findings, gray-scale US and 2D-SWE imaging features, operation information, and pathology results of 48 patients diagnosed with acute appendicitis who presented with right lower quadrant pain were prospectively evaluated. We compared the findings to the US and SWE imaging features of 79 asymptomatic patients. Mean Alvarado score and appendix diameter were statistically significantly higher for acute appendicitis (p < 0.001). In patients with acute appendicitis, mesenteric lymphadenopathy and fat stranding were also more frequent (p < 0.001). The mean velocity and kPa values for appendix and mesenteric fat were statistically significantly higher in acute appendicitis (p < 0.001). In the diagnosis of acute appendicitis, 2D-SWE increases the diagnostic performance of gray-scale US in the differentiation of inflamed and normal appendixes.

Lifting Velocity as a Predictor of the Maximum Number of Repetitions That Can Be Performed to Failure During the Prone Bench Pull Exercise.

To explore (1)the goodness of fit of generalized and individualized relationships between the maximum number of repetitions performed to failure (RTF) and the fastest mean velocity and peak velocity of the sets (RTF-velocity relationships), (2) the between-sessions reliability of mean velocity and peak velocity values associated with different RTFs, and (3) whether the errors in the prediction of the RTF under fatigued and nonfatigued conditions differ between generalized and individualized RTF-velocity relationships. Twenty-three sport-science students performed 4 testing sessions with the prone bench pull exercise in a Smith machine: a 1-repetition-maximum [1RM] session, 2 identical sessions consisting of singles sets of RTF against 4 randomized loads (60%-70%-80%-90%1RM), and 1 session consisting of 4 sets of RTF against the 75%1RM. Individualized RTF-velocity relationships presented a higher goodness of fit (r2 = .96-.97 vs .67-.70) and accuracy (absolute errors = 2.1-2.9 repetitions vs 2.8-4.3 repetitions) in the prediction of the RTF than generalized RTF-velocity relationships. The reliability of the velocity values associated with different RTFs was generally high (average within-subject coefficient of variation = 4.01% for mean velocity and 3.98% for peak velocity). The error in the prediction of the RTF increased by ~1 repetition under fatigue (ie,set 1 vs sets 2-4). Individualized RTF-velocity relationships can be used with acceptable precision and reliability to prescribe the loads associated with a given RTF during the match a specific XRM during the prone bench pull exercise, but a lower accuracy is expected in a fatigued state.

Effects of Acute Yohimbine Hydrochloride Ingestion on Bench Press Performance in Resistance-Trained Males

Yohimbine hydrochloride (YHM) is an alpha-2-adrenergic receptor antagonist that possesses sympathomimetic properties, but few studies have investigated YHM in the context of exercise. The purpose of this study was to examine the effects of acute YHM ingestion on bench press exercise power, velocity, and strength-endurance levels. In a double-blinded crossover design, resistance-trained males (n = 16) participated in two separate bench press trials, each with a different single-dose treatment: placebo (PL; gluten-free corn starch) or yohimbine hydrochloride (YHM; 2.5 mg). In each trial, the participants consumed their respective treatment 20 min prior to exercise. Following a warm-up, the participants completed 1 set × 2 explosive repetitions while a linear position transducer monitored the barbell velocity. The participants then completed 3 sets × repetitions to failure (RTF) at 75% of 1-repetition maximum (1-RM) separated by 2 min of rest. The motivation to exercise and subjective measures of energy or fatigue were measured post-exercise. The total RTF, mean velocity, mean power, motivation, and subjective energy or fatigue values were compared and analyzed. The mean power (p = 0.472; d = 0.16) and mean velocity (p = 0.297; d = 0.25) values were unchanged by treatment. However, the RTF (p = 0.002; d = 0.82) value was higher with YHM treatment. The motivation to exercise (p = 0.011; d = 0.64) and energy levels (p &lt; 0.001; d = 1.27) were significantly higher with YHM ingestion versus PL. The subjective fatigue was significantly lower with YHM ingestion (p &lt; 0.001; d = 1.65). In conclusion, the current findings show that YHM consumption enhanced muscular strength-endurance while improving feelings of motivation, energy, and fatigue. YHM ingestion may, therefore, be useful for athletes or competitors seeking to improve their performance or combat subjective fatigue.

3D velocity-depth model from multichannel seismic in the Dinaric foredeep of the Gulf of Trieste (Adriatic Sea), at the NE edge of Adria plate

The Gulf of Trieste (GT), northeastern Adriatic, sits at the rigid edge of the Adria microplate representing the foreland of the adjoining Meso-Cenozoic External Dinarides and Southeastern Alps. The Adria-Eurasia plate boundary extends along the GT eastern coastline, depicted by the Karst Thrust, outer ramp of the SW-verging Dinarides. This separates the Cretaceous-Paleogene carbonates outcropping hundreds of meters on the Karst Plateau (hanging-wall) from their counterparts buried in the eastern gulf. Although the thrust has no evidence of historical and instrumental seismicity, a detailed seismic velocity field is needed to quantify reliable geometries in the foredeep, embedded in a tectonically active area where Adria is moving NNW-ward. Availability of a newly acquired marine multichannel seismic dataset, allowed us to provide the first well-constrained 3D P-wave velocity and depth model in the footwall of the Karst Thrust. Two iterative techniques, traveltime reflection tomography and depth seismic imaging, were applied on the data surveying the Dinaric foredeep. Our findings provide mean velocity values of 1700 m/s for the Quaternary sediments, 2900 m/s for the upper Eocene flysch turbidites, 4500 m/s for the lower flysch, 5000 m/s for the upper carbonates. The maximum flysch unit thickness results in about 1500 m and the top carbonates depth reaches about 1600 m below sea level, 1.7 km offshore Trieste, revealing the thrust is responsible for a minimum 1600–1800 m vertical throw. This study provides benefits for Adria geodynamic models and give new constraints for the geological and tectonic setting assessment, in a region settled over a currently active continental margin.

Effects of different inspiratory muscle warm-up loads on mechanical, physiological and muscle oxygenation responses during high-intensity running and recovery

Inspiratory muscle warm-up (IMW) has been used as a resource to enhance exercises and sports performance. However, there is a lack of studies in the literature addressing the effects of different IMW loads (especially in combination with a shorter and applicable protocol) on high-intensity running and recovery phase. Thus, this study aimed to investigate the effects of three different IMW loads using a shorter protocol on mechanical, physiological and muscle oxygenation responses during and after high-intensity running exercise. Sixteen physically active men, randomly performed four trials 30 s all-out run, preceded by the shorter IMW protocol (2 × 15 breaths with a 1-min rest interval between sets, accomplished 2 min before the 30 s all-out run). Here, three IMW load conditions were used: 15%, 40%, and 60% of maximal inspiratory pressure (MIP), plus a control session (CON) without the IMW. The force, velocity and running power were measured (1000 Hz). Two near-infrared spectroscopy (NIRS) devices measured (10 Hz) the muscle’s oxygenation responses in biceps brachii (BB) and vastus lateralis (VL). Additionally, heart rate (HR) and blood lactate ([Lac]) were also monitored. IMW loads applied with a shorter protocol promoted a significant increase in mean and minimum running power as well as in peak and minimum force compared to CON. In addition, specific IMW loads led to higher values of peak power, mean velocity (60% of MIP) and mean force (40 and 60% of MIP) in relation to CON. Physiological responses (HR and muscles oxygenation) were not modified by any IMW during exercise, as well as HR and [Lac] in the recovery phase. On the other hand, 40% of MIP presented a higher tissue saturation index (TSI) for BB during recovery phase. In conclusion, the use of different loads of IMW may improve the performance of a physically active individual in a 30 s all-out run, as verified by the increased peak, mean and minimum mechanical values, but not in performance assessed second by second. In addition, 40% of the MIP improves TSI of the BB during the recovery phase, which can indicate greater availability of O2 for lactate clearance.

Testes Parenchymal Shear Wave Elastography Findings in Varicocele.

To investigate the testicular parenchymal changes in patients with varicocele using shear wave elastography (SWE). Cross-sectional study. Department of Radiology, Hatay Mustafa Kemal, School of Medicine, Hatay, Turkey, between June and August 2021. The study was conducted on 124 testes of 62 patients who had undergone scrotal ultrasonography. Using the SWE technique, the mean velocity and stiffness values of each testis were measured and recorded, and varicocele volume was calculated by measuring testis volume and the Pampiniform plexus (pp) vein diameter on Doppler examination. After the exclusion criteria, 55 (44.3%) testes with varicocele and 69 (55.6%) testes without varicocele were examined. The relationship between the SWE values of testis volume and the presence and volume of varicocele was evaluated statistically. The mean velocity value was 0.76 ± 0.08 m/s in the varicocele group and 0.85 ± 0.13 m/s in the without varicocele group; the mean stiffness value was 1.76 ± 0.37 KPa in the varicocele group and 2.25 ± 0.54 KPa in the without varicocele group. The SWE values were found to be significantly lower in testes with varicocele than in those without (p<0.001). The mean testis volume was 13.5 ± 4.6 in the varicocele group and 13.8 ± 4.4 in the without varicocele group. No statistically significant relationship was determined between the presence of varicocele and testis volume (p=0.670). A significant negative correlation was found between plexus pampiniform diameter and velocity (rs=-0.405, p=0.002) and stiffness (rs =-0.399, p=0.003) values. SWE findings can provide information about testicular damage associated with varicocele. Furthermore comprehensive studies may be of importance in varicocele treatment. Shearwave elastography (SWE), Testis, Varicocele, Parenchymal stiffness.

Accelerated dual-venc 4D flow MRI with variable high-venc spatial resolution for neurovascular applications.

PurposeDual‐velocity encoded (dual‐venc or DV) 4D flow MRI achieves wide velocity dynamic range and velocity‐to‐noise ratio (VNR), enabling accurate neurovascular flow characterization. To reduce scan time, we present interleaved dual‐venc 4D Flow with independently prescribed, prospectively undersampled spatial resolution of the high‐venc (HV) acquisition: Variable Spatial Resolution Dual Venc (VSRDV).MethodsA prototype VSRDV sequence was developed based on a Cartesian acquisition with eight‐point phase encoding, combining PEAK‐GRAPPA acceleration with zero‐filling in phase and partition directions for HV. The VSRDV approach was optimized by varying z, the zero‐filling fraction of HV relative to low‐venc, between 0%–80% in vitro (realistic neurovascular model with pulsatile flow) and in vivo (n = 10 volunteers). Antialiasing precision, mean and peak velocity quantification accuracy, and test–retest reproducibility were assessed relative to reference images with equal‐resolution HV and low venc (z = 0%).ResultsIn vitro results for all z demonstrated an antialiasing true positive rate at least 95% for RPEAK−GRAPPA = 2 and 5, with no linear relationship to z (p = 0.62 and 0.13, respectively). Bland–Altman analysis for z = 20%, 40%, 60%, or 80% versus z = 0% in vitro and in vivo demonstrated no bias >1% of venc in mean or peak velocity values at any RZF. In vitro mean and peak velocity, and in vivo peak velocity, had limits of agreement within 15%.ConclusionVSRDV allows up to 34.8% scan time reduction compared to PEAK‐GRAPPA accelerated DV 4D Flow MRI, enabling large spatial coverage and dynamic range while maintaining VNR and velocity measurement accuracy.

Effect of Catalyst Inlet Flow Field Distribution Characteristics on Outlet NO Concentration Distribution in SCR Denitration Reactor Based on Monte Carlo Method

Selective catalytic reduction (SCR) technology plays a crucial role in flue gas denitration. The nonuniform distribution of catalyst inlet parameters causes the nonuniform distribution of NO concentration at the outlet, thus affecting accuracy of ammonia injection. Regarding this issue, this paper describes the impacts of nonuniform velocity and temperature on both the confidence of NO concentration measured at a single measuring point at the outlet and the denitration efficiency, which can provide a basis for structural optimization of SCR denitration reactor and decrease in ammonia slip. The random distribution form of velocity and temperature above the catalyst layer are derived from the actual gas volume and the actual SCR reactor model, and then the catalyst inlet boundary conditions were generated with different relative standard deviation of velocity and temperature accordingly. The confidence of outlet NO concentration measurement results can be counted by means of Monte Carlo simulation. Finally, the relation model can be obtained to calculate the confidence of outlet NO concentration measurement results at different working conditions. The results show that within the gas volume range of this work, in order to ensure the confidence of the NO concentration measurement results, the relative standard deviation of temperature before the catalyst inlet must be within 0.005 and the relative standard deviation of velocity before the catalyst inlet must be within 0.1. With the increase in relative standard difference in temperature, there is a slight decrease in the efficiency of denitration. With the different mean value of temperature, the variation range of denitration efficiency is similar to that of temperature-relative standard difference. With the different mean value of velocity, the deviation range of corresponding efficiency is similar to that of the temperature-relative standard difference. When the relative standard difference in velocity increases, the denitration efficiency decreases slightly. The greater velocity value, the decreasing range of denitration efficiency is larger than the variation range of relative standard difference in velocity.

Conduction velocity mapping in Bachmann Bundle using Omnipolar Technology

Abstract Funding Acknowledgements Type of funding sources: None. Background Bachmann’s bundle is emerging as a critical component of atrial fibrillation (AF) catheter ablation (CA). The introduction of Omnipolar Technology (OT) in the new Ensite X Cardiac Mapping system, provides three-dimensional information on conduction velocity, activation direction and voltage of endocardial potentials, independently of catheter orientation. OT can create a wave speed map: a color map type coded by numeric value of conduction velocity. Objective To assess the feasibility and reliability of left atrium wave speed maps in Bachmann’s bundle identification and conduction velocity characterization. Methods We included 10 patients, (60% male, 40% female, mean age 56±8.7 years) undergoing CA for paroxysmal AF at our institution with new Ensite X Cardiac Mapping System; the left atrium (LA) was mapped with the Advisor HD Grid catheter. A sinus rhythm voltage map and wave speed map were obtained and analyzed to identify high conduction velocity areas throughout the Bachmann’s bundle location (septum, roof and left atrium appendage (LAA)). Results Wave speed mapping allowed the identification, at the septum, roof and LAA, of a myocardial bundle with greater speed values (2.5±0.3 m/s) with respect to mean atrial value (1±0.1). Pulmonary vein antra conduction velocity mean value was 1.2±0.4 m/s. Standard voltage map (low-voltage areas defined as any LA region with voltage values &amp;lt; 0.5 mV) was compared with wave speed map. Standard voltage map (Figure 1) did not discriminate Bachmann’s bundle, while wave speed map did (Figure 2). Conclusion Wave speed mapping introduced by OT is a promising new map type, allowing characterization and identification of Bachmann’s bundle. Further studies are needed to assess the impact of this new technology on procedural workflow and clinical outcome.

An integrated FEA-CFD simulation of offshore wind turbines with vibration control systems

The vibration mitigation of a monopile Offshore Wind Turbine (OWT) under wind and sea wave excitation is investigated, incorporating dynamic Vibration Control systems (VCS). The application of VCS to the OWTs has the potential to significantly improve the damping of the structure and its overall dynamic responses. A novel passive vibration absorption configuration is proposed, namely the Extended KDamper (EKD). Contrary to the conventional tuned mass dampers, EKD can increase its vibration absorption capability by introducing negative stiffness elements, instead of increasing the additional mass at the top of the towers. Therefore, EKD provides better isolation properties. The EKD optimum design and its realization are based on engineering criteria and realistic manufacturing limitations. The turbulence wind load time histories are determined stochastically while the mean velocity value is produced using the Blade Element Momentum theory. The influence of the sea wave excitation is studied using an integrated Computational Fluid Dynamics (CFD) approach. For the sea wave simulation, both fluids (water and air) are discretized using a non-uniform grid on which the Navier–Stokes equations are solved using the Double Control Volume Finite Element Method (DCVFEM). In order to render the large-scale physical problem computationally feasible, the Dynamic Adaptive Mesh Optimisation (DMO) and High Performance Computing (HPC) schemes are incorporated. The OWT tower is modelled using variable cross section beam elements accounting for geometrical nonlinearity (second order phenomena). The monopile soil–structure interaction (SSI) is modelled using a prismatic beam on elastic foundation together with the corresponding springs and dashpots along the pile’s length. An extensive case study is carried out on a monopile OWT providing insight to the structural dynamics and illustrating the viability of the VCS on the offshore wind industry. It is shown that vibration control can extend the lifetime of the structure, increasing the OWTs’ reliability and sustainability.

Effect of Hydraulic Flow on Phytoplankton Population Structure in Tajan River

The aim of present study was to investigate the relationship between hydraulic and ecological variables of the studied span and to investigate changes in living conditions of phytoplankton (Amphora ovsalis and Navicula placentula). According to the measurements and analysis of habitat fit curves, it can be concluded that the highest frequency of Amphora ovsalis and Navicula placentula occurred and specified at flow rate of 15.82 and 14.942 m3/s, respectively. As can be seen, the lowest frequency of Amphora ovsalis and Navicula placentula in this measurement occurred at flow rate of 15.355 and 5.289 m3/s, respectively. The best habitat conditions for Amphora ovsalis and Navicula placentula are in the range of 0.18 -0.31 and 0.18 - 0.265 of Froude number range respectively. The highest density and abundance of Amphora ovsalis and Navicula placentula was observed in the range of 0.017 - 0.055 and 0.017 -0.039 mg/l of phosphate demonstrating that the best growth and living conditions are predisposed in this range for these species had suitable habitat conditions for life in this range. The highest frequency of Amphora ovsalis and Navicula placentula is in the range of 0.019 - 0.071 and 0.047-0.071 mg/l nitrite, respectively. Amphora ovsalis and Navicula placentula had the highest frequency when nitrate ranges 4.48 – 5.16 and 4.48- 5.37 mg/l. The best habitat conditions for Amphora ovsalis and Navicula placentula were between the mean velocity values in the range of 1 -1.2 m/s.

Pulmonary Arteriovenous Pressure Gradient and Time-Averaged Mean Velocity of Small Pulmonary Arteries Can Serve as Sensitive Biomarkers in the Diagnosis of Pulmonary Arterial Hypertension: A Preclinical Study by 4D-Flow MRI.

(1) Background: Pulmonary arterial hypertension (PAH) is a serious condition that is associated with many cardiopulmonary diseases. Invasive right heart catheterization (RHC) is currently the only method for the definitive diagnosis and follow-up of PAH. In this study, we sought a non-invasive hemodynamic biomarker for the diagnosis of PAH. (2) Methods: We applied prospectively respiratory and cardiac gated 4D-flow MRI at a 9.4T preclinical scanner on three different groups of Sprague Dawley rats: baseline (n = 11), moderate PAH (n = 8), and severe PAH (n = 8). The pressure gradients as well as the velocity values were analyzed from 4D-flow data and correlated with lung histology. (3) Results: The pressure gradient between the pulmonary artery and vein on the unilateral side as well as the time-averaged mean velocity values of the small pulmonary arteries were capable of distinguishing not only between baseline and severe PAH, but also between the moderate and severe stages of the disease. (4) Conclusions: The current preclinical study suggests the pulmonary arteriovenous pressure gradient and the time-averaged mean velocity as potential biomarkers to diagnose PAH.

Role of Shear Wave Elastography of Synovium to Differentiate Rheumatoid and Tubercular Arthritis.

Background:Synovitis is the underlying pathology in various arthritis, and sometimes, it is difficult to differentiate various arthritis clinically or even by imaging. The purpose of our study was to use shear wave elastography (SWE) to evaluate rheumatoid arthritis (RA) and tubercular (TB) arthritis and to differentiate them using synovial stiffness.Methods:The prospective study was performed on Supersonic Imagine Aixplorer Ultrasound (USG) machine using a linear array probe SL10-2 (2–10 MHz). A total of 29 participants, 15 of RA (ACR/EULAR criteria) and 14 of proven TB arthritis were included. Region of interest of 1 mm was applied on the hypertrophied synovium and quantitative SWE data in form of elasticity (kPa) and velocity (m/s) were measured. Discrete categorical data were presented as n (%). Mean values were recorded along with standard deviation and the range of values. To find a maximal cutoff value of elasticity and velocity - receiver operating characteristic curve were plotted.Results:The mean elasticity and velocity values were 54.81 ± 10.6 kPa and 4.2 m/s ± 0.42 for RA and 37 ± 10 kPa and 3.4 ± 0.47 m/s for TB group. Significant difference (P < 0.001) was seen in elastic modulus values between rheumatoid and TB group with cutoff of 43.6 kPa to differentiate the two groups (sensitivity – 86.7% and specificity – 80%). Similar significant (P < 0.001) results were seen with velocity values, with cutoff of 3.76 m/s (sensitivity – 86.7% and specificity – 80%).Conclusion:SWE shows the potential to be a useful adjunct to gray scale and color Doppler USG in differentiating various arthritis on the basis of elastic properties of the synovium. Elastic modulus and velocity are useful SWE quantitative parameters for synovial evaluation and can differentiate RA and TB arthritis.

Theoretical and experimental investigations on swirling steam-water mixture flow in a circular channel with modified surface walls

The influence of surface roughness as well as protrusion geometry laid over the inner wall of the horizontal channel, on mean velocity and turbulent quantities along with thermal quantities of the swirling steam-water flow are determined experimentally. These were compared with the measurements for those obtained for smooth inner surface of the channel. The test facility has comprised of a Perspex pipe having inner diameter of 15 cm and length 30 cm. It contains three sections; one has smooth inner surface, second has rough inner surface with mild sand blasting and the third has square circular protruded collars along with mild treatment with the sand blasting. Mean velocity profile within the region close to the vicinity of the surface roughness has been lower than the values of the mean velocity profile in case of smooth inner surface of the pipe. And mean velocity values with protruded collar along with roughened surface are even lower than those in case of inner rough surface. However, the mean velocity values at distance away from the rough surface match among the three cases. Similar profiles representative of the three surfaces are obtained in case of velocity deficit. Whereas different turbulent characteristics are observed among smooth, rough, and protruded surfaces. Significant influences on the normal and Reynolds stresses occur over the whole of the layer due to the rough and protruded surfaces than those of the stresses generated in case of smooth surface. Although velocity spectra exhibit differences between the three surfaces, the mean energy dissipation rate does not appear to be significantly affected by the roughness and protruded surface. Nusselt number with passage of time following initiation of steam into the pipe, drops to an equilibrium value after passage of about 50–70 s. And the heat transfer characterized by normalized Stanton number ratio of rough surface to smooth surface, increases with increase in size of the sand grain for all the three surfaces. The increase in Stanton number ratio representing the rough surfaces is higher than the values of ratio in case of smooth surface. However, the major outcome of this study has been owed to the vorticities shed through the roughness, which is comparable to the roughness scale, k and this was found substantial than the turbulence scale of the outer layer.

Estimation and Investigation of Mean and Most Probable Velocities of Tropospheric Gases over Ilorin, Nigeria

In this study, the monthly average minimum and maximum temperature meteorological data obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) during the period of thirty eight years (1979 – 2016) were used to estimate the mean velocity and most probable velocity of atomic Oxygen and Hydrogen for Ilorin. The values of the mean velocity and most probable velocity for these atoms were compared to the value of escape velocity. The results revealed that the highest values of mean velocity and most probable velocity for atomic Oxygen were found to be in the month of March with and respectively and the highest values of mean velocity and most probable velocity for atomic Hydrogen were found to be in the month of March with and respectively. Based on the values of the mean velocity and most probable velocity for atomic Oxygen and Hydrogen obtained during the studied period suggests that these atoms cannot escape the gravitational field as their values are less than the escape velocity .

Validation of a novel method to assess maximal neuromuscular capacities through the load-velocity relationship

This study was designed to elucidate whether the assessment of the load-velocity relationship during the bench press throw exercise can be used as an indicator of the maximal capacity of upper-body muscles to produce force at low and high velocities as well as doing work at a maximal rate. Twenty-four resistance-trained men (bench press one-repetition maximum [1RM] relative to body mass = 1.14 ± 0.17) performed two incremental loading tests from 14 kg until the 1RM during the bench press throw exercise 7 days apart. Individual load-velocity relationships were modelled from the mean velocity values collected under all loading conditions and three variables were calculated from the individual load-velocity relationships: load-axis intercept (L0), velocity-axis intercept (v0), and area under the line (Aline = L0·v0/2). The bench press 1RM strength, peak velocity achieved against 14 kg (PV14kg), and the maximum power determined as the apex of the power-velocity relationship (Pmax) were also determined as traditional measures of maximal neuromuscular capacities. The three load-velocity relationship variables showed a very high reliability (CV ≤ 2.36%; ICC ≥ 0.86). Regarding the concurrent validity of the load-velocity relationship variables, nearly perfect correlations were observed between L0 and 1RM strength (r = 0.98) and between Aline and Pmax (r = 0.96), while lower correlations were observed between v0 and PV14kg (r = 0.59). These results highlight that the three maximal mechanical capacities of upper-body muscles can be quickly estimated through the assessment of the load-velocity relationship during the bench press throw exercise.

Preservation of left ventricle peak and mean pulse flow blood velocity despite progressive deterioration of cardiac function in a chronic heart failure murine model.

The goal of this study was to assess the alterations in left ventricle (LV) blood flow velocity patterns in relation to progressive impairment of cardiac function in the course of heart failure (HF) in a unique murine model of chronic HF in Tgαq*44 mice. Doppler- and MRI-based assessments of blood velocity and cardiac performance, respectively, were performed in Tgαq*44 mice at the age of 1, 2, 4, 6, 8 and 12 months as compared with age-matched FVB control mice. One-month-old Tgαq*44 mice displayed elongated early diastolic phase with fully preserved cardiac function that, however, progressively deteriorated in older Tgαq*44 mice. As early as in 2-month-old Tgαq*44 mice, the filling rate (FR), max. radial strain and end-systolic volume increased; in 4-month-old Tgαq*44 mice, the ejection fraction, max. circ. strain and ventriculo-arterial coupling decreased, and the ejection time was prolonged; in 6 - 8-month-old Tgαq*44 mice, the stroke volume, max. (both) strains decreased, end-systolic volume, FR and end-diastolic volume increased, and finally, in 12-month-old Tgαq*44 mice, the ejection fraction, cardiac output and stroke volume were all severely impaired. In the early phase of HF development, no differences were observed in Tgαq*44 mice versus FVB mice regarding systolic LV flow pattern, but indices of mitral diastolic flow were considerably increased in 1-month-old Tgαq*44 mice versus FVB mice. In the late phase of HF, despite progressive deterioration of cardiac function, LV pulse flow blood velocity was not altered in Tgαq*44 mice up to the age of 8 months. Systolic peak velocity and mean acceleration time deteriorated only in 12-month-old Tgαq*44 mice, with peak acceleration and mean velocity values still preserved. We demonstrated that the cardiac mitral diastolic flow pattern displayed adaptive changes in the very early phase of HF development in Tgαq*44 mice and that these changes preceded early alterations in LV haemodynamics. Then, despite the progressive deterioration of cardiac haemodynamics, peak and mean in- and out-flow velocities remained unchanged for a relatively long time and deteriorated only at the end-stage HF. Altogether, we revealed that in addition to cardiac performance, adaptive vascular performance represents an important factor determining LV mitral inflow and ejection flow phenotype during the progression of chronic HF in Tgαq*44 mice.

A Data-Driven Method for Vehicle Speed Estimation

This paper presents a method based on Artificial Neural Networks for estimation of the vehicle speed. The technique exploits the combination of two tasks: a) speed estimation by means of regression neural networks dedicated to different road conditions (dry, wet and icy); b) identification of the road condition with a pattern recognition neural network. The training of the networks is conducted with experimental datasets recorded during the driving sessions performed with a vehicle on different tracks. The effectiveness of the proposed approach is validated experimentally on the same car by deploying the algorithm on a dSPACE computing platform. The estimation accuracy is evaluated by comparing the obtained results to the measurement of an optical sensor installed on the vehicle and to the output of another estimation method, based on the mean value of velocity of the four wheels.

Large eddy simulation of fully-developed flow in a helical segmented-fin tube bundle

The Large Eddy Simulation approach was used to perform a numerical simulation of a flow around a circular tube bundle. The model is based on numerical tools, such as the immersed boundary technique and the extrapolation of pressure in the solid region of the tube, to represent a helical segmented-fin tube geometry. The simulation was conducted in an area away from the boundaries of the tube bundle, where the flow is fully-developed, and the use of periodic boundary conditions was possible. The mean velocity and turbulence values of the results and experimental data were compared and showed good general agreement. From the instantaneous results, it was possible to observe and study different turbulent structures presented in the flow. Two counter-rotating horseshoe vortices were identified in the space between the fins, which can improve heat transfer. Furthermore, a relevant transfer of momentum in the inter-segment space and contiguous zones was observed.

Multifrequency magnetic resonance elastography for elasticity quantitation and optimal tissue discrimination: A two-platform liver fibrosis mimicking phantom study.

In the framework of algebraic inversion, magnetic resonance elastography (MRE) repeatability, reproducibility and robustness were evaluated on extracted shear velocities (or elastic moduli). The same excitation system was implemented at two sites equipped with clinical MR scanners of 1.5 and 3 T. A set of four elastic, isotropic, homogeneous calibrated phantoms of distinct elasticity representing the spectrum of liver fibrosis severity was mechanically characterized. The repeatability of the measurements and the reproducibility between the two platforms were found to be excellent with mean coefficients of variations of 1.62% for the shear velocity mean values and 1.95% for the associated standard deviations. MRE velocities were robust to the amplitude and pattern variations of the displacement field with virtually no difference between outcomes from both magnets at identical excitation frequencies, even when the displacement field amplitude was six times smaller. However, MRE outcomes were very sensitive to the number of voxels per wavelength, s, of the recorded displacement field, with relative biases reaching 62% and precision loss by a factor of up to 23.5. For both magnetic field strengths, MRE accuracy and precision were largely degraded outside of established conditions of validity (6 ≲ s ≲ 9), resulting in estimated shear velocity values not significantly different between phantoms of increasing elasticity. When fulfilling the spatial sampling conditions, either prospectively in the acquisition or retrospectively before the reconstruction, MRE produced quantitative measurements that allowed to unambiguously discriminate, with infinitesimal p values, between the phantoms mimicking increasing severity of liver fibrosis.