Peak Velocity Time Research Articles

Corticocortical and corticomuscular connectivity dynamics in standing posture: electroencephalography study.

Cortical mechanism is necessary for human standing control. Previous research has demonstrated that cortical oscillations and corticospinal excitability respond flexibly to postural demands. However, it is unclear how corticocortical and corticomuscular connectivity changes dynamically during standing with spontaneous postural sway and over time. This study investigated the dynamics of sway- and time-varying connectivity using electroencephalography and electromyography. Electroencephalography and electromyography were recorded in sitting position and 3 standing postures with varying base-of-support: normal standing, one-leg standing, and standing on a piece of wood. For sway-varying connectivity, corticomuscular connectivity was calculated based on the timing of peak velocity in anteroposterior sway. For time-varying connectivity, corticocortical connectivity was measured using the sliding-window approach. This study found that corticomuscular connectivity was strengthened at the peak velocity of postural sway in the γ- and β-frequency bands. For time-varying corticocortical connectivity, the θ-connectivity in all time-epoch was classified into 7 clusters including posture-relevant component. In one of the 7 clusters, strong connectivity pairs were concentrated in the mid-central region, and the proportion of epochs under narrow-base standing conditions was significantly higher, indicating a functional role for posture balance. These findings shed light on the connectivity dynamics and cortical oscillation that govern standing balance.

Contrast-Enhanced Ultrasonography Findings Within 3 Days Postoperatively Are Associated With 1-Month Graft Failure After Split Liver Transplantation

Purpose:To evaluate whether Doppler ultrasonography (DUS) and contrast-enhanced ultrasonography (CEUS) within 3 days postoperative can identify 1-month graft failure after split liver transplantation (SLT). Materials and methodsA total of 58 consecutive patients who underwent SLT between February 2022 and September 2023 were included. The DUS and CEUS images and parameters within 3 days postoperatively were analyzed and recorded. The DUS parameters included peak systolic velocity (PSV), resistive index, and systolic acceleration time for the hepatic artery, PSV for the portal vein and hepatic vein. The CEUS qualitative analysis variables included the liver parenchyma enhancement pattern and the posterior enhancement attenuation. Logistic regression and Cox proportional hazard regression were used to evaluate the relationship between DUS/CEUS findings and 1-month graft failure. ResultsSeven of the 58 liver grafts failed within one month. Poor CEUS enhancement (pattern Ⅱ/Ⅲ) was observed in 5 of 7 patients (71.4%) of graft failure, whereas good contrast enhancement (pattern Ⅰ) was found in 47 of the 51 patients (92.1%) in the successful group on postoperative day 3. Multivariate logistic regression analysis revealed that 1-month graft failure was independently predicted by operative time (OR=3.79, 95% CI: 1.27–11.29, p=.017) and CEUS enhancement pattern on postoperative day 3 (OR=90.88, 95% CI: 2.77–2979.56, p=.011). Cox proportional hazard regression showed that operative time ( HR=1.6, 95% CI: 1.15–2.22, p =.005) and CEUS enhancement pattern on postoperative day 3 (HR=11.947, 95% CI: 2.04–69.98, p =.006) were independent predictors for graft failure. ConclusionsPoor CEUS enhancement (pattern Ⅱ/Ⅲ) was associated with 1-month graft failure in SLT recipients. CEUS may serve as a noninvasive, valuable prognostic tool to predict clinical outcomes early after SLT.

Ultrasound parameters of arteries and heart in normal fetuses

BackgroundCurrently, no normal ultrasound data of the fetuses during the 20–40 gestation have been obtained for references of fetal growth and development. If such ultrasound data existed for prenatal diagnosis of possible diseases and abnormalities, neonates would be able to get timely treatment immediately after birth. This study was thus performed to obtain ultrasound parameters of normal fetuses during the 20–40 week gestation and the distribution of ultrasound parameters with the gestational age for references of detecting potential fetal diseases and abnormalities.MethodsNormal fetuses without any abnormalities were enrolled, and the ultrasound parameters of the general biology, arteries, and aorta were measured and analyzed.Results417 normal fetuses were enrolled. A significant (P < 0.05) negative correlation with the gestational age was detected in the peak systolic velocity/peak diastolic velocity (S/D), pulsatility index (PI) and resistance index (RI) of the umbilical artery (UA). A relatively stable relationship with the gestational age was detected in the fetal weight%, S/D, PI and RI of the middle cerebral artery (MCA), peak systolic velocity (PSV) and velocity time integral (VTI) of the intra-abdominal UA, fetal heart to chest ratio, mitral valve (MV)- and tricuspid valve (TV)-E/A peak flow velocity, aortic isthmic Z-score and displacement, distance between the brachiocephalic artery-left common carotid artery (BA-LCCA) and LCCA-left subclavian artery (LSA), Z-score of aorta, ascending aorta (AAO), pulmonary artery (PA), main pulmonary artery (MPA), and descending aorta (DAO). A significant (P < 0.05) positive correlation with the gestational age was detected in the fetal biological data, MCA PSV and VTI, free-UA PSV and VTI and cardio-thoracic ratio, cardiac parameters, ductus arteriosus (DA) and isthmus diameter, aortic parameters, PA and MPA diameter, MPA PSV and VTI, isthmus flow volume and velocity and PA flow volume, DA and BA parameters, and LCCA and LSA parameters (flow volume, PSV, and VTI).ConclusionA certain correlation and distribution trend is detected in the ultrasound parameters of normal fetuses, and the ratios among different parameters remain relative stable. These findings can be used for determination of abnormal growth of the fetuses in prenatal ultrasound scan.Graphic

Experimental characterization of exhaled flow dynamics of human breathing and vocalization

During the onging pandemic of COVID-19, there are numerous asymptomatic patients who are infectious. The exhaled droplets from their daily respiratory activities like breathing or speaking can be the sources of airborne disease transmission of COVID-19. The understanding of the airflow dynamics of these respiratory activities may be helpful to develop effective measures to prevent and control the spread of the disease. In this study, the exhaled flows from human breathing and vocalization of specific syllables are characterized using particle image velocimetry (PIV) and smoke visualization. The exhaled flow generated by ten phonemes including vowels, fricatives, affricates, plosives and nasals as well as mouth breathing are studied. The dynamic developments of the airflow processes are described by a series of parameters, including peak velocity, peak velocity time, duration time, propagation velocity and distance. Results show that vocalization of affricates and plosives as well as mouth breathing tend to have higher peak velocities and propagation distances. The evolutions of exhaled flows generated from these respiratory processes are found to have different jet structures, which are related to the stroke ratio (L/D). The flow field of a small L/D only has a pair of dominant vortices. Whereas that of a large L/D presents both a pair of dominant vortex ring and a trailing jet. Certain phoneme (e.g., /t/) is found to display a two-stage jet similar to a cough with the starting jet and an interrupted jet. The characterization of human exhaled flow of this study may be helpful to provide basis of CFD simulations and a better understanding of the spread of airborne diseases from human breathing.

Impact of 14 Days of Bed Rest in Older Adults and an Exercise Countermeasure on Body Composition, Muscle Strength, and Cardiovascular Function: Canadian Space Agency Standard Measures

Introduction: Head-down bed rest (HDBR) has long been used as an analog to microgravity, and it also enables studying the changes occurring with aging. Exercise is the most effective countermeasure for the deleterious effects of inactivity. The aim of this study was to investigate the efficacy of an exercise countermeasure in healthy older participants on attenuating musculoskeletal deconditioning, cardiovascular fitness level, and muscle strength during 14 days of HDBR as part of the standard measures of the Canadian Space Agency. Methods: Twenty-three participants (12 males and 11 females), aged 55–65 years, were admitted for a 26-day inpatient stay at the McGill University Health Centre. After 5 days of baseline assessment tests, they underwent 14 days of continuous HDBR followed by 7 days of recovery with repeated tests. Participants were randomized to passive physiotherapy or an exercise countermeasure during the HDBR period consisting of 3 sessions per day of either high-intensity interval training (HIIT) or low-intensity cycling or strength exercises for the lower and upper body. Peak aerobic power (V̇O2peak) was determined using indirect calorimetry. Body composition was assessed by dual-energy X-ray absorptiometry, and several muscle group strengths were evaluated using an adjustable chair dynamometer. A vertical jump was used to assess whole-body power output, and a tilt test was used to measure cardiovascular and orthostatic challenges. Additionally, changes in various blood parameters were measured as well as the effects of exercise countermeasure on these measurements. Results: There were no differences at baseline in main characteristics between the control and exercise groups. The exercise group maintained V̇O2peak levels similar to baseline, whereas it decreased in the control group following 14 days of HDBR. Body weight significantly decreased in both groups. Total and leg lean masses decreased in both groups. However, total body fat mass decreased only in the exercise group. Isometric and isokinetic knee extension muscle strength were significantly reduced in both groups. Peak velocity, flight height, and flight time were significantly reduced in both groups with HDBR. Conclusion: In this first Canadian HDBR study in older adults, an exercise countermeasure helped maintain aerobic fitness and lean body mass without affecting the reduction of knee extension strength. However, it was ineffective in protecting against orthostatic intolerance. These results support HIIT as a promising approach to preserve astronaut health and functioning during space missions, and to prevent deconditioning as a result of hospitalization in older adults.

Comparison of Smoothness, Movement Speed and Trajectory during Reaching Movements in Real and Virtual Spaces Using a Head-Mounted Display.

Virtual reality is used in rehabilitation and training simulators. However, whether movements in real and virtual spaces are similar is yet to be elucidated. The study aimed to examine the smoothness, trajectory, and velocity of participants' movements during task performance in real and virtual space. Ten participants performed the same motor task in these two spaces, reaching for targets placed at six distinct positions. A head-mounted display (HMD) presented the virtual space, which simulated the real space environment. The smoothness of movements during the task was quantified and analysed using normalised jerk cost. Trajectories were analysed using the actual trajectory length normalised by the shortest distance to the target, and velocity was analysed using the time of peak velocity. The analysis results showed no significant differences in smoothness and peak velocity time between the two spaces. No significant differences were found in the placement of the six targets between the two spaces. Conversely, significant differences were observed in trajectory length ratio and peak velocity time, albeit with small effect sizes. This outcome can potentially be attributed to the fact that the virtual space was presented from a first-person perspective using an HMD capable of presenting stereoscopic images through binocular parallax. Participants were able to obtain physiological depth information and directly perceive the distance between the target and the effector, such as a hand or a controller, in virtual space, similar to real space. The results suggest that training in virtual space using HMDs with binocular disparity may be a useful tool, as it allows the simulation of a variety of different environments.

Effect of sneeze flow velocity profiles on the respiratory droplets dispersion in a confined space: An experimental and computational fluid dynamics study

In this study, the effects of sneeze velocity profiles, including peak velocity (PV), peak velocity time (PVT), and sneeze duration time (SDT), on the dispersion of respiratory droplets were studied experimentally and numerically. Spatial–temporal datasets of droplet velocity exhaled from several subjects' mouths with different physiological characteristics were obtained by particle image velocimetry. A direct relationship was found between the forced vital capacity and PV, while the subject's body mass index significantly affected the SDT. A transient computational fluid dynamics (CFD) approach using the renormalization group k–ε turbulence model in conjunction with the Lagrangian particle tracking was developed and used to simulate sneeze droplet motion characteristics. Both one-way and two-way (humidity) coupling models were used in these simulations. The CFD results showed that the two-way (humidity) coupling model provided better agreement with the data in the turbulent and expanded puff zones than the one-way coupling model. The one-way model led to reasonably accurate results in the fully dispersed and dilute-dispersed droplet phases. The effect of injection duration time and injection angle on PVT was larger than that on PV values, while the effect of initial injection velocity on PV was higher than that on PVT values. In addition, the initial injection velocity and angle significantly affected the maximum spreading distance of droplets dmax,sp. The numerical results obtained from the dilute-dispersed droplet phase were in good agreement with the trajectories of isolated droplets in the experimental data. The findings of this study provide novel insights into the effect of sneeze velocity profiles on dmax,sp, and the sneezer subject physiological effect on the threshold distance for the transmission of respiratory pathogens in a confined space.

Carotid artery corrected flow time and respiratory variation of blood flow peak velocity for prediction of hypotension after induction of general anesthesia in adult patients undergoing emergency laparotomy for peritonitis: A prospective, observational study.

Doppler waveform analysis of carotid artery has been found to predict fluid responsiveness in patients undergoing elective surgeries. We evaluated the role of carotid artery corrected flow time (FTc) and respiratory variation of blood flow peak velocity (ðVpeak) in predicting post induction hypotension in patients undergoing emergency laparotomy for peritonitis. Adult patients (n = 60) with perforation peritonitis undergoing emergency laparotomy under general anesthesia (GA) were recruited in this prospective, observational study. Carotid ultrasonography was performed pre-induction, to determine FTc and ðVpeak. Post-induction hemodynamic parameters were recorded for 5 minutes. Spearman's rank correlation coefficient was used to determine the relationship between hypotension and carotid artery measurements. Post-induction hypotension occurred in 48.3% of patients. The carotid artery FTc was significantly lower (P = 0.008) in patients who developed post-induction hypotension, but ðVpeak was statistically similar (P = 0.62) in both groups. Spearman's rank correlation coefficient revealed a statistically significant correlation between FTc and systolic blood pressure (SBP) change at one-minute post induction (r2 = -0.29, P = 0.03); however statistical significance were not achieved at 2 minutes and 3 minutes (P = 0.05 at both time points). Carotid artery FTc had an area under the receiver operating characteristic (AUROC) curve (95% CI) of 0.70 (0.57-0.84) to predict post-induction hypotension and best cutoff value of 344.8 ms with a sensitivity and specificity of 61% and 79%, respectively. Carotid artery ðVpeak had an AUROC curve (95% CI) of 0.54 (0.39-0.69) to predict post-induction hypotension and best cutoff value of 7.9% with a sensitivity and specificity of 62% and 55%, respectively. Carotid artery FTc and ðVpeak are not reasonable predictors of hypotension in patients undergoing emergency laparotomy for perforation peritonitis.

The Use of Contrast May Improve Aortic Valve Assessment During Transesophageal Echocardiography

The Doppler profile that quantifies the degree of aortic stenosis is essential, as an inaccurate measurement can alter the surgical plan. The authors aimed to examine the level of agreement between the contrast and noncontrast methods of aortic valve sizing during intraoperative transesophageal echocardiography (TEE). At a tertiary hospital. A total of 30 patients undergoing surgical aortic valve replacement for a stenotic valve. Perflutren lipid microsphere contrast injection. The authors reviewed Doppler studies of 30 consecutive patients undergoing aortic valve replacement in whom a contrast agent was given (perflutren lipid microsphere). They measured the peak and/or mean aortic valve gradients and velocity time integral readings through the left ventricular outflow tract (LVOT), and the aortic valve before and after administering the contrast agent. The aortic valve area was then calculated using both methods. Paired t tests and Bland-Altman analyses were used to examine the bias and the level of agreement between the 2 processes. By not using a contrast agent, the aortic valve area was overestimated by 0.26 cm2 compared to those measured by transthoracic echocardiography (TTE) (p < 0.001). Using a contrast agent, TEE measurements were comparable to those obtained by TTE. Moreover, the peak and mean aortic valve gradients were underestimated by 19 and 11 mmHg, respectively (p value <0.001). Adding contrast did not affect the pulse-wave Doppler readings of the V1 velocity of the LVOT. This discrepancy is significant and could affect the decision to replace the aortic valve. When evaluating the aortic valve with TEE, the authors recommend using a contrast agent to improve the Doppler profile and to obtain a more accurate measurement of the aortic valve area.

Carotid artery corrected flow time and respiratory variations of peak blood flow velocity for prediction of hypotension after induction of general anesthesia in elderly patients

BackgroundPostinduction hypotension is closely related to postoperative complications. Elderly patients with compromised cardiovascular compensatory reserve are more susceptible to hypotension after induction of general anesthesia. This study investigated whether the carotid artery corrected flow time (FTc) and respiratory variation of peak blood flow velocity in the common carotid artery (ΔVpeak) could predict postinduction hypotension in elderly patients.MethodsThis prospective observational study included elderly patients aged 65 to 75 who were scheduled for elective surgery under general anesthesia with ASA physical status class of I-II, without cardiovascular disease, hypertension, diabetes, or obesity. Anesthesia was induced by midazolam, sufentanil, and etomidate and was maintained by sevoflurane. The carotid artery FTc and ΔVpeak were measured by ultrasound before induction of anesthesia. Hemodynamic data were recorded before induction and then during the first 10 min after induction.ResultsNinety-nine patients were included in the final analysis, of whom 63 developed postinduction hypotension. The area under the receiver operating characteristic curves was 0.87 (0.78 to 0.93) for carotid artery FTc and 0.67 (0.56 to 0.76) for ΔVpeak, respectively. The optimal cutoff value for predicting postinduction hypotension was 379.1 ms for carotid artery FTc, with sensitivity and specificity of 72.2 and 93.7%, respectively. The best cutoff value was 7.5% for ΔVpeak, with sensitivity and specificity of 55.6 and 75.0%, respectively.ConclusionsThe carotid artery FTc is a reliable predictor of postinduction hypotension in elderly patients with ASA status of I or II, without cardiovascular disease, hypertension, diabetes, or obesity. Elderly patients with a carotid artery FTc less than 379.1 ms before anesthesia have a higher risk of postinduction hypotension.Trial registrationClinical Trial Registry on August 2nd, 2020 (www.chictr.org.cn; ChiCTR2000035190).

Influence of cough airflow characteristics on respiratory mucus clearance

A cough is a respiratory reflex for respiratory mucus clearance. The cough airflow dynamics can be characterized by three parameters, which are cough peak flow rate (CPFR), peak velocity time (PVT), and cough expired volume (CEV). In this study, the three-dimensional human respiratory airways from generation 0 to 5 are reconstructed from computerized tomography images. The non-Newtonian property of respiratory mucus is considered. The airflow–mucus interaction phenomenon has been analyzed in time and space based on the Eulerian wall film model. The maximum air velocity and wall shear stress could reach 38 m/s and 14 Pa, respectively, when the CPFR is 6 L/s. In addition, the influence of CPFR, PVT, and CEV on mucus clearance has been studied. The cough efficiency is used to quantify the mucus clearance. The results showed that increasing the cough peak flow rate has no noticeable effect on mucus clearance under normal and low mucus viscosity. Increasing the cough peak flow rate can effectively improve mucus clearance when the mucus viscosity becomes high. Specifically, the CEV has an apparent positive effect on clearing mucus regardless of the viscosity and thickness. This study provides a new research direction to improve mucus clearance by improving the CEV rather than the CPFR for patients with chronic obstructive pulmonary disease, neuromuscular disease, or other pulmonary diseases.

Modulation of Gamma Spectral Amplitude and Connectivity During Reaching Predicts Peak Velocity and Movement Duration

Modulation of gamma oscillations recorded from the human motor cortex and basal ganglia appears to play a key role in movement execution. However, there are still major questions to be answered about the specific role of cortical gamma activity in both the planning and execution of movement features such as the scaling of peak velocity and movement time. In this study, we characterized movement-related gamma oscillatory dynamics and its relationship with kinematic parameters based on 256-channels EEG recordings in 64 healthy subjects while performing fast and uncorrected reaching movements to targets located at three distances. In keeping with previous studies, we found that movement-related gamma synchronization occurred during movement execution. As a new finding, we showed that gamma synchronization occurred also before movement onset, with planning and execution phases involving different gamma peak frequencies and topographies. Importantly, the amplitude of gamma synchronization in both planning and execution increased with target distance and predicted peak velocity and movement time. Additional analysis of phase coherence revealed a gamma-coordinated long-range network involving occipital, frontal and central regions during movement execution that was positively related to kinematic features. This is the first evidence in humans supporting the notion that gamma synchronization amplitude and phase coherence pattern can reliably predict peak velocity amplitude and movement time. Therefore, these findings suggest that cortical gamma oscillations have a crucial role for the selection, implementation and control of the appropriate kinematic parameters of goal-directed reaching movements.

Is Functional Overreaching or Acute Fatigue the Key to the Effects of Concentrated Block Training in Running?

Borszcz, FK, Vieira, MT, Tramontin, AF, Visentainer, LH, and Costa, VP. Is functional overreaching or acute fatigue the key to the effects of concentrated block training in running? J Strength Cond Res 36(12): 3485-3496, 2022-This study examined the effects of 5 consecutive days of high- and moderate-intensity training on performance and physiological measures in moderately trained individuals. The relationship of the training organization with the state of overreaching and acute fatigue was investigated. Twenty-four male soldiers (age, 19.3 ± 0.4 years; V̇o2peak, 58.7 ± 3.8 ml·kg-1·min-1) were assigned to 2 training groups for 5 consecutive days of either high- or moderate-intensity training. The subjects underwent incremental and 12-minute time trial tests before, immediately after, 1 and 2 weeks after training. The high- and moderate-intensity sessions were 30 minutes in duration and performed at fixed velocities of 13.3 and 10 km·h-1 (near second and first ventilatory thresholds), respectively. Acute fatigue and overreaching criteria were set as concomitant nonimpairment and impairment, respectively, in the incremental peak velocity and 12-minute time trial performances at posttest immediately after the training block. Data analyses were completed using hierarchical Bayesian's models. In subjects who wer trained at moderate intensity, no performance impairment occurred (i.e., acute fatigue); for the high-intensity training, 5 subjects showed impairment in performance and were classified as overreached. Only in subjects who were acutely fatigued, clear beneficial effects were observed in incremental test peak velocity and 12-minute time trial performances. In moderately trained runners, a block of 5 consecutive days of moderate-intensity training was demonstrated to be a useful strategy for the improvement of performance. However, high-intensity training does not seem to be a safe strategy because of the observations of overreaching and inferior probabilities of performance improvements.

Abstract 11516: Quantification of Regurgitation Through Dual Orifices: Pulsatile in Vitro Analysis with Echocardiography and MRI Assessment

Introduction: Proximal Isovelocity Surface Area (PISA) measurement is widely accepted to quantify mitral regurgitant volume (RVol), but flow convergence (FC) zones are complicated with dual orifices, seen with mitral clipping. This study seeks to investigate how flow through one orifice affects PISA measurement across the other to better quantify RVol in dual orifice conditions. Methods: 3D-printed dual circular orifice models with varying relative areas were integrated into a pulsatile flow phantom simulating left heart flow. One orifice (A) was standardized at 19.6 mm 2 while the other (B) was 1X, 2X, and 3X the area of A in three models. Inter-orifice distance was 5 mm to emulate mitral clipping. Continuous wave doppler echocardiography measured peak velocity and velocity time integral. PISA was performed at four aliasing velocities normalized to peak velocity (V a /V peak ) (10%, 8%, 4%, 2%) to compute RVol with 2D phase contrast MRI as reference. In each model, PISA RVol and percent error was calculated to see how varying the area of B impacts PISA accuracy of A. 4D flow MRI FC data was also collected to visualize the 3D formation of FC zones. Results: Using a high V a /V peak to create distinct FC zones provides a better RVol estimation with PISA, as low V a /V peak will merge the FC zones, overestimating flow across individual orifices. Single factor analysis of variance (ANOVA) of percent error of A across the three models showed no significant difference at high V a /V peak (8%: p=0.80, 10%: p=0.23), but significant difference at low V a /V peak (2%: p=0.010, 4%: p=0.005). High V a /V peak FC zones of orifices are independent from each other; PISA can be measured with standard practices and added together for an accurate total RVol. At low V a /V peak , FC orifice zones overlap with overestimation error increasing with larger B area. This finding suggests that resolving two separate FC zones to minimize flow interference is important for accurate RVol estimate in a dual orifice setting.

Comparison of Manipulative Indicators of Students and Therapists Using a Robotic Arm: A Feasibility Study

In this study, the motion therapy elements necessary for student education were clarified through comparison of the therapeutic motion techniques of therapists and students using an educational arm robot (Samothrace: SAMO). Eight therapists and 25 fourth-year students participated. The therapeutic motion therapy task was a reciprocating exercise in which the elbow joint of SAMO was flexed from an extended position and then re-extended. This was performed for three types of muscle tone intensities (mild, moderate, and severe), and the peak velocity, angle ratio, velocity time, and movement time were recorded using SAMO. These data were then compared using analysis of covariance. It was found that the SAMO elbow joint kinematic data generated by therapists differed significantly from those of students for different muscle tones. Multiple comparisons showed that the therapeutic motion techniques of students were associated with a higher peak velocity, smaller peak angle ratio, and shorter peak velocity time and movement time than those of the therapists. Thus, when students learn therapeutic motion techniques, they should be taught to (1) deal with multiple muscle tone intensities and (2) reduce the joint movement speed applied to the patient to extend the exercise time and ensure maximum joint movement range.

Perturbation of cortical activity elicits regional and age-dependent effects on unconstrained reaching behavior: a pilot study.

Contributions from premotor and supplementary motor areas to reaching behavior in aging humans are not well understood. The objective of these experiments was to examine effects of perturbations to specific cortical areas on the control of unconstrained reaches against gravity by younger and older adults. Double-pulse transcranial magnetic stimulation (TMS) was applied to scalp locations targeting primary motor cortex (M1), dorsal premotor area (PMA), supplementary motor area (SMA), or dorsolateral prefrontal cortex (DLPFC). Stimulation was intended to perturb ongoing activity inthe targeted cortical region before or after a visual cue to initiate moderately paced reaches to one of three vertical target locations. Regional effects were observed in movement amplitude both early and late in the reach. Perturbation of PMA increased reach distance before the time of peak velocity to a greater extent than all other regions. Reaches showed greater deviation from a straight-line path around the time of peak velocity and greater overall curvature with perturbation of PMA and M1 relative to SMA and DLPFC. The perturbationincreased positional variability of the reach path at the time of peak velocityand the time elapsing after peak velocity. Although perturbations had stronger effects on reaches by younger subjects, this group exhibited less reach path variability at the time of peak velocity and required less time to adjust the movement trajectory thereafter. These findings support the role of PMA in visually guided reaching and suggest an age-related change in sensorimotor processing, possibly due to a loss of cortical inhibitory control.

Comparison of Kinematic Sequences During Curveball and Fastball Baseball Pitches.

Performance of a sequential proximal-to-distal transfer of segmental angular velocity (or Kinematic Sequence) is reported to reduce stress on musculoskeletal structures and thus the probability of injury while also maximizing ball velocity. However, there is limited investigation regarding the Kinematic Sequence of the five body segments (Pelvis, Trunk, Arm, Forearm, and Hand) among baseball pitchers. Some biomechanical and epidemiology studies have reported an association of the curveball with increased risk for elbow injury among youth pitchers. Kinematic Sequences with altered distal upper extremity (forearm and hand) sequences have been associated with greater elbow valgus and shoulder external rotation torques compared to other Kinematic Sequences. Identifying Kinematic Sequence patterns during curveball pitches may lead to improved understanding of injury susceptibility. This study investigated the Kinematic Sequence patterns (and their variability) during curveball pitching and compared them to the sequences identified during fastball pitches. Using 3D motion analyses, 14 baseball pitchers (four high school, eight college, and two professional) performed 5–6 curveball pitches and 12 pitchers also threw fastball pitches in a simulated bullpen session. Eleven different curveball Kinematic Sequences were identified and 8 fastball Kinematic Sequences. There was no significant variability in the number of Kinematic Sequences performed between the two pitch types, (Z = −0.431, p = 0.67). The median number of KSs performed by each group was 2.5. The most frequently used Kinematic Sequences for both pitch types were due to alteration in the sequence of the distal segments. The total percentage of Kinematic Sequences with altered distal segment sequencing for the curveball pitches was 49% and 43% for fastball pitches. Identifying the frequency of Kinematic Sequences with altered timing of hand and forearm peak velocities across pitch types may lead to a better understanding of the stresses that individual pitchers incur.

Experimental measurements of airflow features and velocity distribution exhaled from sneeze and speech using particle image velocimetry

Airflow exhaled from sneeze and speech is an important source of viruses and droplets in daily life and may cause imperceptible virus propagation. The velocities of sneeze and speech airflow exhaled from 10 healthy young participants repeatedly using high-frequency (2986 Hz) particle image velocimetry are measured. The parameters for describing the dynamic process of sneeze airflow, such as sneeze duration time (SDT), peak velocity time (PVT), maximum velocities, and sneeze spread angle, are analyzed. The sneeze airflow lasts 430 ms (SDT) and reaches the peak velocity in the first 20 ms (PVT). The maximum sneeze airflow velocity is approximately 15.9 m/s. The temporal variation of the sneeze velocity exhibits the gamma distribution. For speech airflow, the maximum instantaneous velocity and maximum time-averaged velocity are reported. The maximum instantaneous velocity is approximately 6.25 m/s, whereas the time-averaged value is only 0.208 m/s owing to the extremely small airflow velocity among syllables. The vertical/horizontal spread angles of the airflow are 15.1°/15.4° for sneeze and 52.9°/42.9° for speech. The difference in airflow features based on gender is generally slight for both sneeze and speech. Subsequently, an ensemble-average operation is conducted to obtain the general and representative velocity distributions. We report each component of the temporal and spatial velocity distributions of the sneeze airflow and the time-averaged velocity distribution of the speech airflow. These detailed distribution data can provide a comprehensive understanding of sneeze and speech airflow movement mechanisms as well as a detailed database for future sneeze and speech computational fluid dynamics simulations.

Changes in Orientation Behavior due to Extended High-Frequency (5 to 10 kHz) Spatial Cues.

Objectives:Current hearing aids have a limited bandwidth, which limits the intelligibility and quality of their output, and inhibits their uptake. Recent advances in signal processing, as well as novel methods of transduction, allow for a greater useable frequency range. Previous studies have shown a benefit for this extended bandwidth in consonant recognition, talker-sex identification, and separating sound sources. To explore whether there would be any direct spatial benefits to extending bandwidth, we used a dynamic localization method in a realistic situation.Design:Twenty-eight adult participants with minimal hearing loss reoriented themselves as quickly and accurately as comfortable to a new, off-axis near-field talker continuing a story in a background of far-field talkers of the same overall level in a simulated large room with common building materials. All stimuli were low-pass filtered at either 5 or 10 kHz on each trial. To further simulate current hearing aids, participants wore microphones above the pinnae and insert earphones adjusted to provide a linear, zero-gain response.Results:Each individual trajectory was recorded with infra-red motion-tracking and analyzed for accuracy, duration, start time, peak velocity, peak velocity time, complexity, reversals, and misorientations. Results across listeners showed a significant increase in peak velocity and significant decrease in start and peak velocity time with greater (10 kHz) bandwidth.Conclusions:These earlier, swifter orientations demonstrate spatial benefits beyond static localization accuracy in plausible conditions; extended bandwidth without pinna cues provided more salient cues in a realistic mixture of talkers.

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.