High Velocity Research Articles

Influence of Substitutions and Roles on Kinematic Variables in Professional Soccer Players.

In soccer, roles, and substitutions could make unclear how different physical capacities decrease over time and impact performance. This investigation aimed to analyze kinematic parameters and their changes over game time and provide information to effectively prescribe training programs. Data from four professional teams were analyzed, and all the teams competed in the Premier Division championship. Average metabolic power and high-intensity activities associated with critical moments in the match were considered in the comparisons. The video analysis system STATS SportVU collected the data during official matches. Players were assigned to a specific group according to their time played, categorized as follows: 0-15', 15-30', 30-45', 45-60', 60-75', 75-90', and > 90 min. Different roles, including forwards and wingers (FW), midfielders (MF), center-backs (CB), and side-backs (SB) were also considered. Significant differences (p<0.05) were found in different roles and within roles at different times played. The results highlighted how MF performance decreased over time, whereas CB was unaffected by time. SB spent more time at very high velocity than other roles, independently from the time played. These findings provide valuable information about the physical demands of official soccer games and could be used to review training prescriptions.

Modelling the Flow Conditions and Primary Atomization of an Air-Core-Liquid-Ring (ACLR) Atomizer Using a Coupled Eulerian–Lagrangian Approach

AbstractThe Air-Core-Liquid-Ring atomizer is a pioneering internal-mixing pneumatic atomization technique designed for energy-efficient spray drying of highly viscous liquid feeds with substantial solid contents. However, it can suffer internal flow instabilities, which may lead to spray droplets with a wide variation in diameter. Experimental investigation of how flow conditions mechanistically determine the resulting droplet sizes is hindered by high velocities near the nozzle outlet. Therefore, this study addressed the issue by implementing a numerical model, employing a coupled Eulerian-Lagrangian approach with adaptive mesh refinement, to simulate the breakup of the liquid into ligaments and droplets. Additionally, Large Eddy Simulation was incorporated to replicate turbulent flow conditions observed in experiments. The numerical model demonstrated significant improvement in predicting liquid film thickness, compared to previous work. Additionally, the simulated droplet size distributions mirrored experimental trends, shifting to smaller sizes as pressure increased. Unfortunately, while reduced, there is a persistent underestimation of the lamella thickness and the droplet sizes at 0.2 MPa. In spite of this, the fact that the error propagates between the two phenomena underscores the effective coupling between Eulerian and Lagrangian approaches.

Proton Therapy: A Ray of Hope for the Cancer Patients

Abstract: Cancer is a life-threatening disease, and there are very few options to treat it almost completely, with a high percentage of success rates. Proton therapy is a very unique and one of the latest techniques to treat cancer with a very promising percentage of success rate. In this therapy, a proton particle with high velocity is used, and it is superior to conventional photon or radiotherapy. In this review, we have discussed the theoretical aspects of this technique and the latest variant of this therapy called pencil beam proton therapy, which is a cutting-edge technique to treat cancer. We have also tried to discuss the applications of proton therapy for different types of cancers.

Enhancing Big Data Security through Comprehensive Data Protection Measures: A Focus on Securing Data at Rest and In-Transit

Purpose: This research paper aims to enhance Big Data security by implementing comprehensive data protection measures, focusing on securing data at rest and in transit. In the era of Big Data, organizations handle vast quantities of data characterized by high velocity, volume, and variety, which complicates management and increases security risks. Methodology: The study examines various data protection strategies, including encryption, access control, data masking, immutable storage, tokenization, and physical security for data at rest. For data in transit, it explores encryption protocols, secure transfer methods like SSH and TLS, VPNs, Zero Trust architecture, and secure APIs. These methods are crucial for safeguarding sensitive information and preventing unauthorized access. Findings: The findings highlight common security challenges in Big Data, such as data breaches, unauthorized access, and integrity issues. The study emphasizes the need for robust protection measures and offers a comprehensive view of the data security landscape. Implementing these strategies helps organizations safeguard sensitive information and ensure compliance with international data protection regulations, enhancing their overall security posture. Unique contribution to theory policy and practice: This paper contributes to theory, policy, and practice by advocating comprehensive data protection strategies. It stresses the importance of continuous monitoring and regulatory compliance, providing practical insights into best practices and technologies that protect Big Data. The research supports developing robust data protection policies and practices, advancing knowledge in Big Data security.

Multi-Modal in Vitro Experiments Mimicking the Flow Through a Mitral Heart Valve Phantom.

Fluid-structure interaction (FSI) models are more commonly applied in medical research as computational power is increasing. However, understanding the accuracy of FSI models is crucial, especially in the context of heart valve disease in patient-specific models. Therefore, this study aimed to create a multi-modal benchmarking data set for cardiac-inspired FSI models, based on clinically important parameters, such as the pressure, velocity, and valve opening, with an in vitro phantom setup. An in vitro setup was developed with a 3D-printed phantom mimicking the left heart, including a deforming mitral valve. A range of pulsatile flows were created with a computer-controlled motor-and-pump setup. Catheter pressure measurements, magnetic resonance imaging (MRI), and echocardiography (Echo) imaging were used to measure pressure and velocity in the domain. Furthermore, the valve opening was quantified based on cine MRI and Echo images. The experimental setup, with 0.5% cycle-to-cycle variation, was successfully built and six different flow cases were investigated. Higher velocity through the mitral valve was observed for increased cardiac output. The pressure difference across the valve also followed this trend. The flow in the phantom was qualitatively assessed by the velocity profile in the ventricle and by streamlines obtained from 4D phase-contrast MRI. A multi-modal set of data for validation of FSI models has been created, based on parameters relevant for diagnosis of heart valve disease. All data is publicly available for future development of computational heart valve models.

High-strain rate deformation of aluminum during the Taylor test

The aim of the study is to develop a methodology for assessing changes in the microstructure of aluminum under dynamic deformation in a rather wide range of the strain rate and strain degree. The distribution of the microstructure and the strength properties in the cross-section of pure aluminum samples (A99) after dynamic deformation according to the Taylor test were studied. The tests were carried out at room temperature using a PG-20 light-gas cannon, at sample throwing speeds of 127 and 165 m/sec. An interference microscope (Leica IM DRM) and a scanning electron microscope (Jeol JSM-6490) were used to study the aluminum microstructure; the microhardness measurements were carried out on an HVS-1000 device to study the uniformity of the strain distribution in samples. It is shown that three characteristic areas can be distinguished in aluminum samples after Taylor test: the elastic deformation zone, the plastic deformation zone, and the zone of severe plastic deformation, which is located in the area of collision of the sample with a steel barrier. It is shown that dynamic deformation reduced the grain structure from 1 – 1.1 mm to 2.5 – 3 μm at high impact velocities. An elongated grain shape is observed in the collision zone. The proposed method provided determination of the critical strain degree necessary for the onset of grain fragmentation and allowed us to explain the formation of zones of weak and severe plastic deformation. It is shown that the critical strain degree corresponding to the beginning of grain fragmentation increases from 0.18 to 0.21 with an increase in the throwing speed of the sample from 127 to 165 m/sec. In the zone of weak deformation, plastic deformation proceeds by intragrain riveting and the initial stages of grain fragmentation. In the zone of severe plastic deformation, a fine-grained microstructure is formed, which leads to an increase in the microhardness of aluminum in accordance with the Hall – Petch equation.

Uterine Arteriovenous Malformation: Diagnostic and Therapeutic Challenges

Uterine arteriovenous malformations are a rare cause of puerperal haemorrhage, but their incidence is increasing due to both improved diagnosis and the more frequent use of uterine surgery in recent years. The use of ultrasound, both B-mode and Doppler, is recommended for diagnosis and follow-up, as it has been shown to be the simplest and most cost-effective method. Endometrial thickening associated with an anechoic and vascular intramiometrial structure is very useful for diagnosis and can help to exclude other causes of dysfunctional bleeding. Pulsed Doppler shows low-resistance vessels and high pulsatility indices with a high peak systolic velocity (PSV). In a healthy myometrium, the vessels have a peak systolic velocity of 9–40 cm/s and a resistance index between 0.6 and 0.8, whereas in the case of AVMs, the systolic and diastolic velocities are 4–6 times higher (PSV 25–110 cm/s with a mean of 60 cm/s and a resistance index of 0.27–0.75 with a mean of 0.41). For treatment, we must individualise each case, taking into account haemodynamic stability, the patient’s reproductive wishes, and the severity of the AVM as assessed by its size and PSV.

3C-SiC phononic waveguide for manipulating mechanical wave propagation

We present experimental demonstration and modeling of mechanical wave propagation in a quasi-one-dimensional (quasi-1D) phononic crystal (PnC) waveguide (WG) constructed from a periodic array of single-crystal cubic-silicon carbide (3C-SiC) coupled micromechanical resonators, with an exceptional dynamic range exceeding 92 dB. The PnC design comprises 50 periodic cells, enabling the propagation of flexural mechanical waves in high-frequency and very-high-frequency bands, featuring a broad PnC bandgap spanning approximately 24–27.5 MHz. Furthermore, the 3C-SiC PnC WG exhibits excellent characteristics, including a high group velocity of 350 m/s and a low transmission loss of 0.69 dB/mm, enabling efficient guidance and support for mechanical waves across extended distances before reaching the noise level of the device. These attributes of the PnC WG, as demonstrated in this study, may open possibilities for the development of device platforms with applications in on-chip signal processing, sensing, and quantum transducer technologies.

The influence of ionized gas kinematics on H ii galaxies The cases of Tol 1004-296 and Tol 0957-278

Abstract Blue Compact Galaxies (BCGs), also known as H ii galaxies, are dwarf, star-forming objects with relatively simple dynamics, which allows for the investigation of star formation mechanisms in a cleaner manner compared to late-type objects. In this study, we have examined various characteristics of the interstellar medium, in connection with the kinematics and dynamics of ionized gas, in Tol 1004-296 and Tol 0957-278. These two objects were observed using the SOAR Integral Field Spectrometer (SIFS) attached to the Southern Observatory for Astrophysical Research (SOAR). Both galaxies were observed with two gratings: one with medium resolution for monochromatic and abundance maps, and another with high resolution for kinematics and profile analysis. Additionally, we conducted an analysis on the velocity and velocity dispersion maps using intensity-velocity dispersion (I - σ) and velocity-velocity dispersion (Vr - σ) diagrams. Neither object exhibits a rotation pattern, and only Tol 1004-296 shows a velocity gradient between the two principal knots. However, the study reveals the significant role played by velocity dispersion in the star formation process. Specifically, we identified a relationship between monochromatic intensity, metallicity, and velocity dispersion, where high emission corresponds to low metallicity and low velocity dispersion. Tol 1004-296, in particular, exhibits a distinctive linear high velocity dispersion pattern between the two main knots, suggesting that both star formation sites are pushing the gas in opposite directions.

Lumbopelvic Stability during a Single Leg Step Down Predicts Elbow Varus Torque during Baseball Pitching.

During a baseball pitch, energy is transferred from the lower extremities through the lumbopelvic junction to the upper extremity. Reduced lumbopelvic stability has been associated with elbow injuries, but the mechanisms are unclear. Characterize the predictive ability of lumbopelvic stability on elbow varus torque during a baseball pitch. Cross-Sectional. Facilities at NCAA Division 1 universities. NCAA Division 1 baseball players (N=44; 19.6+1.3yrs). Pitchers completed a warm-up and then threw ten fastballs from a mound to a catcher. During the pitches, elbow varus torque was recorded using an inertial measurement unit and ball velocity was recorded with a radar gun. Participants also completed a single leg step down (SLSD) task with and without a cognitive Stroop, while triplanar pelvic and trunk kinematics were recorded by inertial measurement units. Statistical analysis consisted of a cluster analysis, principal component analysis (PCA), and a multivariate logistic regression model. Cluster analysis revealed 2 clusters: Low Torque-High Velocity and High-Torque-Low Velocity. The PCA analysis revealed 4 patterns of variability (principal components) during the SLSD: 1-sagittal plane, 2-transverse plane, 3-frontal plane trail limb, and 4-frontal plane lead limb. Logistic regression indicated increased transverse plane trunk and pelvis motion predicted higher odds of belonging to the High Torque-Low Velocity cluster; trunk [OR=2.9 (95%CI:1.1,8.0), p=0.036] and pelvis [OR=2.6 (95%CI:1.1,6.0), p=0.031]. Lumbopelvic movement assessed during the SLSD can identify deficits that relate to high elbow torque-low ball velocity during the baseball pitch. Specifically, higher pelvis and trunk transverse plane motion was associated with pitchers in the High Torque-Low Velocity cluster. Our assessment of trunk and pelvis motion during a SLSD provides a method for coaches and clinicians to identify a potential risk factor related to increased elbow varus torque and decreased ball velocity.

Modelling of opposed flame spread over thin electric wires: estimation of flame spread rates and limiting oxygen concentrations

A model of opposed flame spread along thin electric wires is developed to estimate the variation of flame spread rate ( V f ) with oxygen concentrations and oxidiser flow velocity. The length of pyrolysis zone ( L py ) and V f are treated as eigenvalues of the problem, and one-dimensional energy balance equations for the wire core and insulation are formulated to derive their solutions. To obtain a set of steady solutions for L py and V f , the macroscopic energy balance equation for the entire system is calculated from the one-dimensional energy balance equations with appropriate boundary conditions. Since the equations are nonlinear function of L py and V f , multiple solutions appear. The physical meaning of each solution is evaluated based on the deviation of energy from the equilibrium. Comparison of the temperature distribution along the wire with experimental data confirms that the model reproduces well the actual flame spread process. The variation of V f with oxygen concentration shows a C-shaped curve. The upper branch is the stable solution, and the lower branch is the unstable solution and the merging point of two branches correspond to the limit condition for flame spread. Therefore, the model can be used to estimate the limiting oxygen concentration based on the existence of a solution for V f . Furthermore, the variation of V f with oxidiser flow velocity shows O-shaped curve, and it is confirmed that radiative extinction under low flow velocity and blow-off under high flow velocity can also be estimated with the model. Mapping of variations of radiative extinction and blow-off extinction with oxygen concentration reveals the U-shaped flammability diagram. The predicted flame spread limits are in good agreement with the limiting oxygen concentrations measured in both microgravity and normal gravity, demonstrating the validity of using this model to predict flammability characteristics of electric wires under various oxidiser flow velocity.

The initial sticking of high velocity water onto graphite under non-equilibrium supersonic flow conditions.

In this paper, we present a combined experimental and theoretical study that explored the initial sticking of water on cooled surfaces. Specifically, these ultra-high vacuum gas-surface scattering experiments utilized supersonic molecular beam techniques in conjunction with a cryogenically cooled highly oriented pyrolytic graphite crystal, giving control over incident kinematic conditions. The D2O translational energy spanning 300-750meV, the relative D2O flux, and the incident angle could all be varied independently. Three different experimental measurements were made. One involved measuring the total amount of D2O scattering as a function of surface temperature to determine the onset of sticking under non-equilibrium gas-surface collision conditions. Another measurement used He specular scattering to assess structural and coverage information for the interface during D2O adsorption. Finally, we used time-of-flight (TOF) measurements of the scattered D2O to determine how energy is exchanged with the graphite surface at surface temperatures above and near the conditions needed for gaseous condensation. For comparison and elaboration of the roles that internal degrees of freedom play in this process, we also did similar TOF measurements using another mass 20 incident particle, atomic neon. Enriching this study are precise molecular dynamics simulations that elaborate on gas-surface energy transfer and the roles of molecular degrees of freedom in gas-surface collisional energy exchange processes. This study furthers our fundamental understanding of energy exchange and the onset of sticking and ultimately gaseous condensation for gas-surface encounters occurring under high-velocity flows.

Varying primordial state fractions in exo- and endothermic SIDM simulations of Milky Way-mass haloes

Abstract Self-interacting dark matter (SIDM) is increasingly studied as a potential solution to small-scale discrepancies between simulations of cold dark matter (CDM) and observations. We examine a physically motivated two-state SIDM model with both elastic and inelastic scatterings. In particular, endothermic, exothermic, and elastic scattering have equal transfer cross sections at high relative velocities (vrel ≳ 400 km s−1). In a suite of cosmological zoom-in simulation of Milky Way-size haloes, we vary the primordial state fractions to understand the impact of inelastic dark matter self-interactions on halo structure and evolution. In particular, we test how the initial conditions impact the present-day properties of dark matter haloes. Depending on the primordial state fraction, scattering reactions will be dominated by either exothermic or endothermic effects for high and low initial excited state fractions respectively. We find that increasing the initial excited fraction reduces the mass of the main halo, as well as the number of subhaloes on all mass scales. The main haloes are cored, with lower inner densities and higher outer densities compared with CDM. Additionally, we find that the shape of the main halo becomes more spherical the higher the initial excited state fraction is. Finally, we show that the number of satellites steadily decreases with initial excited state fraction across all satellite masses.

The Measured Flow at the Inlet of a Francis Turbine Runner Operating in Speed No-Load Condition

Abstract For Francis turbines, speed-no-load (SNL) represents one of the most detrimental operating conditions, marked by significant pressure and strain fluctuations on the runner. Mitigating these fluctuations necessitates a comprehensive understanding and characterization of the flow phenomena responsible for their generation. This paper presents an experimental investigation of the flow at the inlet of a Francis turbine runner model operating in speed-no-load condition using high-speed stereoscopic and endoscopic particle image velocimetry (PIV). The measurements are made in a radial-azimuthal plane that covers the vaneless space and a large region in the interblade channel. This study marks the first-time measurement of critical flow phenomena at this operating point, performed in the runner. Instantaneous and average velocity fields are analyzed, along with other statistical data. The results not only confirm the stochastic nature of the flow at speed-no-load but also highlight the general structure of the flow observed in other studies. The high velocity fluctuations on the suction side are associated with a backflow extending into the vaneless space and a circulation zone occasionally generated by this backflow. Both phenomena are frequently present, but fluctuate stochastically. Additionally, two other circulation zones intermittently form on the pressure side of the blades. The presence of vortices, smaller than the circulation zones, near the blade's leading edge correlates with the backflow intensity.

Forecasting Convective Storms Trajectory and Intensity by Neural Networks

Convective storms represent a dangerous atmospheric phenomenon, particularly for the heavy and concentrated precipitation they can trigger. Given their high velocity and variability, their prediction is challenging, though it is crucial to issue reliable alarms. The paper presents a neural network approach to forecast the convective cell trajectory and intensity, using, as an example, a region in northern Italy that is frequently hit by convective storms in spring and summer. The predictor input is constituted by radar-derived information about the center of gravity of the cell, its reflectivity (a proxy for the intensity of the precipitation), and the area affected by the storm. The essential characteristic of the proposed approach is that the neural network directly forecasts the evolution of the convective cell position and of the other features for the following hour at a 5-min temporal resolution without a relevant loss of accuracy in comparison to predictors trained for each specific variable at a particular time step. Besides its accuracy (R2 of the position is about 0.80 one hour in advance), this machine learning approach has clear advantages over the classical numerical weather predictors since it runs at orders of magnitude more rapidly, thus allowing for the implementation of a real-time early-warning system.

Feasibility of High-resolution Transmission Spectroscopy for Low-velocity Exoplanets

In recent years, high-resolution transmission spectroscopy in the near-infrared has led to detections of prominent molecules in several giant exoplanets on close-in orbits. This approach has traditionally relied on the large Doppler shifts of the planetary spectral lines induced by the high velocities of close-in planets, which were considered necessary for separating them from the quasi-static stellar and telluric lines. In this work, we demonstrate the feasibility of high-resolution transmission spectroscopy for chemical detections in atmospheres of temperate low-mass exoplanets around M dwarfs with low radial velocity variation during transit. We pursue this goal using model injection and recovery tests with H- and K-band high-resolution spectroscopy of the temperate sub-Neptune TOI-732 c, observed using the IGRINS spectrograph on Gemini South. We show that planetary signals in transit may be recovered when the change in the planet’s radial velocity is very small, down to subpixel velocities. This is possible due to the presence of the planetary signal in only a subset of the observed spectra. A sufficient number of out-of-transit spectra can create enough contrast between the planet signal and telluric/stellar contaminants that the planet signal does not constitute a principal component of the time-series spectra and can therefore be isolated using principal-component-analysis-based detrending without relying on a significant Doppler shift. We additionally explore novel metrics for finding such signals, and investigate trends in their detectability. Our work extends the scope of high-resolution transmission spectroscopy and creates a pathway toward the characterization of habitable sub-Neptune worlds with ground-based facilities.

Pulsed Propulsion of Unmanned Aerial Vehicles by Centrifugal Force Modulation—First-Order Theory and Practicability

A novel technique suitable for the propulsion of small unmanned aerial vehicles (UAV) is discussed in this paper. This approach utilizes the rotational energy of airborne gyro rotors and converts it into translational propulsion for the vehicle. The energy conversion is achieved by generating precisely directed centrifugal force pulses through short-duration rotor unbalances. The accurate control of the timing and magnitude of these unbalances is crucial for successful propulsion generation. Our first-order theory of controlled unbalance propulsion (CUP) predicts the potential for achieving high translational accelerations and vehicle velocities up to orbital levels. Power-saving levitation of UAVs can be attained. In this paper, we provide traceable evidence that pulsed centrifugal propulsion is based on well-established laws of physics and can be realized using state-of-the-art technologies.

A VERY COMPLEX CASE OF DORV TYPE FALLOT: A CASE REPORT

Abstract Double outlet right ventricle (DORV) is a rare CHD characterized by ventriculoarterial connection in which both great arteries arise entirely or predominantly from the right ventricle. Its prevalence is 0.9% of all CHDs. Several chromosomal abnormalities have been associated with DORV, including trisomy 13, trisomy 18, and chromosome 22q11 deletion. Hearts with DORV are an extremely heterogeneous group showing various morphological features, connections, and relationships at each level of the cardiac segments and intersegmental junctions. As a consequence, the clinical manifestations and required surgical procedures for patients with DORV are variable. The anatomical spectrum is higly variable: it can be associated with ventricular septal defect, transposition of the great arteries (TGA) and functional single ventricle. We report the case of an infant with prenatal diagnosis of CHD and finding partial duplication of the short arm of the X chromosome. Pregnant woman at 22 weeks comes to the outpatient clinic to perform follow–up ultrasound. At that site finding of CHD which was later confirmed at birth and therefore prostaglandin therapy was started. Echocardiogram showed a wide DIV from malalignment with antero–cephalic deviation of the conal septum with significant aortic destroposition configuring picture of double outlet right ventricle. It also presents a complex right efflux obstruction already at subvalvular pulmonary departure. The pulmonary valve presented dysplastic, with en dome motion, hypoplastic. Pulmonary perfusion appears to be provided predominantly by the Botallo‘s duct originating from the isthmic region of the aorta and leading with a long and tortuous course to the pulmonary confluence near the left pulmnary artery with high velocity flow. The remaining findings are normal. Therefore, in view of the clinical picture, he was subjected to palliative surgery of right systemic–pulmonary shunt between the brachiocephalic trunk and right pulmonary artery (modified Blalock–Taussing surgery) in 3.5mm PTFE and ligation of Botallo‘s duct. At subsequent follow–up, the systemic–pulmonary shunt appeared pervious with regular flow. Wide DIV from anterior malalignment with aorta cavalier to DIV. Severe stenosis at complex pulmonary outflow with max gradient up to 124mmHg with dynamic and valvular component. For the subsequent course of treatment, the patient will be discussed collegially.

Free-Living Sit-to-Stand Characteristics as Predictors of Lower Extremity Functional Decline Among Older Adults.

Habitual strength and power-demanding activities of daily life may support the maintenance of adequate lower-extremity functioning with ageing, but this has been sparingly explored. Hence, we examined whether the characteristics of free-living sit-to-stand (STS) transitions predict a decline in lower-extremity functioning over a 4-year follow-up. 340 community-dwelling older adults (60% women, age 75, 80 or 85 years) participated in this prospective cohort study. At baseline, a thigh-worn accelerometer was used continuously (3-7 days) to monitor the number and intensity of free-living STS transitions. A decline in lower-extremity functioning was defined as a drop of ≥2 points in the Short Physical Performance Battery (SPPB) from baseline to follow-up. Maximal isometric knee-extension strength was measured in the laboratory. 85 participants (75% women) declined in SPPB over 4 years. After adjusting for age, sex, and baseline SPPB points, higher free-living peak STS angular velocity (odds ratio [OR] = 0.70; 95% confidence interval [CI] = 0.52-0.92, per 20 deg/s increase) protected against a future decline. When adjusting the model for maximal isometric knee-extension strength, the statistical significance was attenuated (OR = 0.72; 95% CI = 0.54-0.96, per 20 deg/s increase). Performing STS transitions at higher velocities in the free-living environment can prevent a future decline in lower-extremity function. This indicates that changes in daily STS behavior may be useful in the early identification of functional loss. Free-living peak STS angular velocity may be a factor underlying the longitudinal association of lower-extremity strength and performance.

Effect of High velocity Nasal Cannula compared with Noninvasive Positive Pressure Ventilation in Patients with COPD Exacerbation

Effect of High velocity Nasal Cannula compared with Noninvasive Positive Pressure Ventilation in Patients with COPD Exacerbation