Acceleration Slope Research Articles

Impaired Dynamic Response of Oxygen Saturation During the 6-min Walk Test Is Associated With Mortality in Chronic Fibrosing Interstitial Pneumonia.

The 6-min walk test (6MWT) is a common assessment of exercise-induced hypoxemia and exercise capacity used in patients with chronic fibrosing interstitial pneumonia (CFIP). However, whether the dynamic changes in SpO2 and heart rate during the 6MWT are associated with mortality in patients with CFIP has been undefined. This retrospective study enrolled 63 subjects with mild to severe CFIP who underwent the 6MWT. Subjects with CFIP were divided into 2 groups according to disease severity: mild, diffusing capacity of the lungs for carbon monoxide percentage predicted (%DLCO) > 55% and %FVC > 75%; and severe, %DLCO ≤ 55% and/or %FVC ≤ 75%. This study aimed to evaluate dynamic changes in the 6MWT including 6-min walk distance, change in SpO2 (ΔSpO2 ), SpO2 reduction time, SpO2 recovery time, change in heart rate (Δ heart rate), heart rate acceleration time, slope of heart rate acceleration, heart rate recovery at 1 min of rest after the 6MWT (HR-recovery), and dyspnea on exertion that are reflected by static pulmonary function and are related to exacerbation of CFIP and mortality. Compared with subjects with mild CFIP, subjects with severe CFIP had significantly larger ΔSpO2 and longer SpO 2 reduction time and recovery time. The slope of heart rate, heart rate immediately after the 6MWT, and HR-recovery were lower in subjects with severe CFIP than in those with mild CFIP. In multiple regression analysis, percent vital capacity was significantly associated with SpO2 reduction time, and %DLCO was significantly associated with ΔSpO2 and SpO2 recovery time. Subjects with ΔSpO2 of > 10% and SpO2 recovery time of > 79 s had a significantly higher risk for exacerbation and mortality. Dynamic changes in SpO2 and heart rate during the 6MWT were associated with risk for exacerbation and mortality in subjects with CFIP. Impaired dynamic response of SpO2 could reflect likelihood of exacerbation and increased mortality in CFIP.

A geometric approach to quantifying the neuromodulatory effects of persistent inward currents on individual motor unit discharge patterns

Objective. All motor commands flow through motoneurons, which entrain control of their innervated muscle fibers, forming a motor unit (MU). Owing to the high fidelity of action potentials within MUs, their discharge profiles detail the organization of ionotropic excitatory/inhibitory as well as metabotropic neuromodulatory commands to motoneurons. Neuromodulatory inputs (e.g. norepinephrine, serotonin) enhance motoneuron excitability and facilitate persistent inward currents (PICs). PICs introduce quantifiable properties in MU discharge profiles by augmenting depolarizing currents upon activation (i.e. PIC amplification) and facilitating discharge at lower levels of excitatory input than required for recruitment (i.e. PIC prolongation). Approach. Here, we introduce a novel geometric approach to estimate neuromodulatory and inhibitory contributions to MU discharge by exploiting discharge non-linearities introduced by PIC amplification during time-varying linear tasks. In specific, we quantify the deviation from linear discharge (‘brace height’) and the rate of change in discharge (i.e. acceleration slope, attenuation slope, angle). We further characterize these metrics on a simulated motoneuron pool with known excitatory, inhibitory, and neuromodulatory inputs and on human MUs (number of MUs; Tibialis Anterior: 1448, Medial Gastrocnemius: 2100, Soleus: 1062, First Dorsal Interosseus: 2296). Main results. In the simulated motor pool, we found brace height and attenuation slope to consistently indicate changes in neuromodulation and the pattern of inhibition (excitation–inhibition coupling), respectively, whereas the paired MU analysis (ΔF) was dependent on both neuromodulation and inhibition pattern. Furthermore, we provide estimates of these metrics in human MUs and show comparable variability in ΔF and brace height measures for MUs matched across multiple trials. Significance. Spanning both datasets, we found brace height quantification to provide an intuitive method for achieving graded estimates of neuromodulatory and inhibitory drive to individual MUs. This complements common techniques and provides an avenue for decoupling changes in the level of neuromodulatory and pattern of inhibitory motor commands.

Analytical Computation of Sandy Slope Stability under the Groundwater Seepage and Earthquake Conditions

Groundwater and earthquake are two of the factors behind the occurrence of slope instability. This paper focuses on the computation of the safety factor acting on a sandy slope when subjected to groundwater seepage and earthquake load. Based on the theory of limit equilibrium and a pseudodynamic method of analysis, a general solution for the dynamic factor of sandy slope containing two load conditions is proposed. In the solution, the effects of parameters such as water level, seismic acceleration coefficients, slope angle, and soil internal friction angle on the slope stability have been discussed. In order to evaluate the validity of the present formulation, the dynamic factors of safety computed by the present method are compared with those given by other cases. It is found that the results of the present method are in good agreement with those of the previous method. The results indicate that the dynamic of safety factor increases linearly with an increase in the soil internal friction angle but decreases with the slope angle and groundwater level and that the effects of direction and magnitude of the seismic inertia forces on the dynamic safety factor of sandy slope are different at different times.

Bilateral Symmetry Analysis Of Tibial Accelerations During Single Leg Hop For Distance In Healthy Collegiate Soccer Players

Bilateral comparative analysis has commonly been used to aid return-to-sport (RTS) decision making during functional testing. Different symmetry thresholds have been used as a criteria to determine RTS, however, knowledge of normative symmetries are prerequisite to establishing any criterion. Normative bilateral symmetry of tibial acceleration metrics during the single leg hop for distance (SLH) have never been reported. PURPOSE: To determine if bilateral differences exist in tibial acceleration metrics (PA: peak acceleration, TPA: time to peak acceleration, AS: acceleration slope) during the SLH and to report normative symmetry within a healthy group of collegiate soccer players. METHODS: Twenty-four collegiate soccer players (4F, 20 M; 19.5 ± 1.2 yrs) granted informed consent and performed three SLH trials with both legs (D = dominant, ND = non-dominant) while wearing inertial measurement units (IMU; 9.5 g, 1500 Hz) fixated with a silicon strap 3-cm proximal to both medial malleoli. A Matlab script processed triaxial acceleration data for the SLH of greatest distance with a 60-Hz, fourth-order, dual-pass Butterworth filter before resultant acceleration was computed. Bilateral PA, TPTA and AS were tested for significant differences between legs with a series of paired t-tests. Significance level was set apriori at 0.05. Symmetry angle % was then computed for hop distance and all tibial acceleration metrics. RESULTS: Hop distance (D: 53.8 ± 7.6 cm, ND: 54.4 ± 7.3 cm, p = 0.42), PTA (D: 35.5 ± 5.4 g, ND: 38.3 ± 10.1 g, p = 0.06), TPTA (D: 15.9 ± 5.2 ms, ND: 16.5 ± 6.1 ms) and AS (D: 3233.0 ± 1222.2 g/ms, ND: 2990.3 ± 1233.9 g/ms) did not significantly differ between legs. All average symmetry angle %s were < 10% (hop distance: 1.6 ± 1.5%; PTA: 4.0 ± 3.8%; TPTA: 8.0 ± 7.5%; AS 9.1 ± 5.9%). CONCLUSIONS: Within a group of healthy collegiate soccer players, no significant differences in either hop distance or tibial acceleration metrics existed when comparing dominant and non-dominant legs. Seven of the participants (29.2%) displayed bilateral differences in peak tibial acceleration greater than the MDC95 level indicating a meaningful difference. Clinicians are encouraged to perform baseline testing to establish player-specific symmetry angle %s for establishing RTS criteria in tibial acceleration metrics during the SLH.

Tibial Accelerations During the Single-Leg Hop Test: Influence of Fixation.

Performance on single-leg hopping (SLH) assessments is commonly included within return-to-sport criteria for rehabilitating athletes. Triaxial accelerometers have been used to quantify impact loading in a variety of movements, including hopping; however, they have never been attached to the tibia during SLH, and their method of fixation has not been investigated. The purpose of this study was to quantify triaxial accelerations and evaluate the influence of the fixation method of a lightweight inertial measurement unit (Blue Trident) mounted to the tibia during SLH performance. Single cohort, repeated-measures experimental design. Sixteen healthy participants (10 females and 6 males; 20 [0.9]y; 1.67 [0.08]m; 66.0 [8.5]kg) met the inclusion criteria, volunteered, and completed this study. Participants performed 2 sets of 3 SLH trials with an inertial measurement unit (1500Hz) fixated to the tibia, each set with 1 of 2 attachment methods (double-sided tape [DST] with athletic tape and silicon strap [SS] with Velcro adhesion). Hop distance, peak tibial acceleration (PTA), time to PTA, and the acceleration slope were assessed during each hop landing. Repeated-measures analysis of variance determined no significant effect of the attachment method on hop metrics (P = .252). Across 3 trials, both fixation methods (DST and SS) had excellent reliability values (intraclass correlation coefficient: .868-.941) for PTA and acceleration slope but not for time to PTA (intraclass correlation coefficient: .397-.768). The PTA for DST (27.22 [7.94] g) and SS (26.21 [10.48]g) was comparable and had a moderate, positive relationship (DST: r = .72, P < .01; SS: r = .77, P < .01) to SLH distance. Tibial inertial measurement units with triaxial accelerometers can reliably assess PTA during performance of the SLH, and SS is a viable alternative tibial attachment to DST.

Mechanomyography and acceleration show interlimb asymmetries in Parkinson patients without tremor compared to controls during a unilateral motor task

The mechanical muscular oscillations are rarely the objective of investigations regarding the identification of a biomarker for Parkinson’s disease (PD). Therefore, the aim of this study was to investigate whether or not this specific motor output differs between PD patients and controls. The novelty is that patients without tremor are investigated performing a unilateral isometric motor task. The force of armflexors and the forearm acceleration (ACC) were recorded as well as the mechanomyography of the biceps brachii (MMGbi), brachioradialis (MMGbra) and pectoralis major (MMGpect) muscles using a piezoelectric-sensor-based system during a unilateral motor task at 70% of the MVIC. The frequency, a power-frequency-ratio, the amplitude variation, the slope of amplitudes and their interlimb asymmetries were analysed. The results indicate that the oscillatory behavior of muscular output in PD without tremor deviates from controls in some parameters: Significant differences appeared for the power-frequency-ratio (p = 0.001, r = 0.43) and for the amplitude variation (p = 0.003, r = 0.34) of MMGpect. The interlimb asymmetries differed significantly concerning the power-frequency-ratio of MMGbi (p = 0.013, r = 0.42) and MMGbra (p = 0.048, r = 0.39) as well as regarding the mean frequency (p = 0.004, r = 0.48) and amplitude variation of MMGpect (p = 0.033, r = 0.37). The mean (M) and variation coefficient (CV) of slope of ACC differed significantly (M: p = 0.022, r = 0.33; CV: p = 0.004, r = 0.43). All other parameters showed no significant differences between PD and controls. It remains open, if this altered mechanical muscular output is reproducible and specific for PD.

Resting coronary blood flow velocity profile predicts coronary flow reserve in HFpEF

Abstract Background Coronary microvascular disease (CMD) is prevalent in patients with heart failure with preserved ejection fraction (HFpEF). CMD can be assessed by coronary flow reserve (CFR) using transthoracic echocardiography (TTE). We hypothesised that the coronary Doppler flow profile in LAD at rest could reveal information about the downstream resistance in the vessel, where increased resistance is a sign of CMD. Purpose We aimed to measure features of the acceleration and deceleration of the LAD Doppler flow profile to investigate association with coronary and cardiac function. Methods CFR was assessed in 202 patients by TTE in the PROMIS-HFpEF-study. Detailed flow profile measurements were possible in 169 patients (84%) who constituted the study population. The coronary Doppler flow profiles were analysed with respect to acceleration time (corAT) and slope (corAS) and deceleration pressure half time (corPHT) (figure 1). Results The average age was 75±9 years and 55% were female. Atrial fibrillation (AF) was present in 53% and 62% were current or previous smokers. There was no significant difference in gender, age, BMI, blood pressure or heart rate in the CMD vs non-CMD group, but AF as well as a history of smoking was more prevalent in the CMD group, p=0.022 and 0.003 respectively. Further, there were no significant differences in neither corAT nor corAS between the two groups. However, patients with CMD had shorter corPHT of 268±64 ms compared to 298±67 ms, p=0.01. A longer corPHT was associated with increased TAPSE (R=0.205, p=0.007) and higher CFR (R=0.231, p=0.002). In a multivariable analysis adjusted for age, sex, BMI, SBP, reactive hyperemia index, HR, AF, diabetes, CVD, smoking, LVM and study site*, corPHT independently predicted CFR (table 1, p=0.016). Conclusion Short pressure half time, indicating a steep deceleration of the coronary Doppler signal at rest, may provide useful information for prediction of CFR determined by transthoracic ultrasound by reflecting the increased resistance in the coronary microvasculature associated with CMD. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Sahlgrenska University Hospital, Sponsor AstraZeneca

Influence of Swing-Foot Strike Pattern on Balance Control Mechanisms during Gait Initiation over an Obstacle to Be Cleared

Gait initiation (GI) over an obstacle to be cleared is a functional task that is highly challenging for the balance control system. Two swing-foot strike patterns were identified during this task—the rearfoot strike (RFS), where the heel strikes the ground first, and the forefoot strike (FFS), where the toe strikes the ground first. This study investigated the effect of the swing-foot strike pattern on the postural organisation of GI over an obstacle to be cleared. Participants performed a series of obstacle clearance tasks with the instruction to strike the ground with either an FFS or RFS pattern. Results showed that anticipatory postural adjustments in the frontal plane were smaller in FFS than in RFS, while stability was increased in FFS. The vertical braking of the centre of mass (COM) during GI swing phase was attenuated in FFS compared to RFS, leading to greater downward centre of mass velocity at foot contact in FFS. In addition, the collision forces acting on the foot were smaller in FFS than in RFS, as were the slope of these forces and the slope of the C7 vertebra acceleration at foot contact. Overall, these results suggest an interdependent relationship between balance control mechanisms and foot strike pattern for optimal stability control.

A simulation study of the role of cohort forces in mortality patterns

ABSTRACTThis study uses the micro-simulation method to investigate the role of cohort forces in age-dependent mortality pattern. We test the micro mechanisms for cohort evolution and mortality selection, and how these two biological and demographic forces may interact with epidemiologic transition to shape the cohort age-dependence of mortality pattern in both early- and later-transition countries. We show that cohort evolution is due to the declining rate of mortality acceleration at the individual level, which is associated with lower initial mortality rates but not smaller variance of frailty distribution in later birth cohorts. The steeper slope of mortality acceleration at the population level among later birth cohorts is due to mortality selection mechanism associated with smaller variance of frailty distribution but not lower initial mortality rates. These two forces jointly shape the non-crossover cohort age-dependence of mortality pattern regardless of the differential mechanisms of epidemiologic transition in early- and later-transition countries.

Examination of Utricular Response Using oVEMP and Unilateral Centrifugation Rotation Testing.

Significant advancements have been made toward the clinical assessment of utricular function through ocular vestibular-evoked myogenic potentials (oVEMP) and unilateral centrifugation (UCF) testing. To date, no study has examined intrasubject relationships between these measures. The study hypothesis was that intrasubject responses from oVEMP and UCF testing would be correlated inasmuch as both tests have been reported to assess utricular function. UCF rotations and oVEMP testing were performed on healthy volunteers, aged 18 to 62 years. A within-subject study design compared and correlated UCF outcome measures of ocular counterroll, subjective visual vertical, and ocular counterroll-gravitational inertial acceleration slope against peak to peak oVEMP N1-P1 amplitude. Correlational analyses failed to reveal any significant relationships between oVEMP amplitude and UCF responses suggesting that these tests may be inciting different response properties within the utricular system. Various anatomical and physiological differences within the utricle, in addition to the fundamental differences in stimulus properties between the oVEMP and UCF tests, could explain the lack of significant correlations between these measures and suggest that oVEMP and UCF testing may be complimentary in their evaluation of the utricular system. These data reinforce the complexities of the utricular system and provide further insight into the difficulties encountered in its clinical assessment.

A Fast Earthquake Early Warning Algorithm Based on the First 3 s of the P‐Wave Coda

Research Article| July 10, 2018 A Fast Earthquake Early Warning Algorithm Based on the First 3 s of the P‐Wave Coda Armando Cuéllar; Armando Cuéllar aCentro de Instrumentación y Registro Sísmico (CIRES), Anaxágoras 814, Colonia Narvarte, Mexico City 03020, Mexico Search for other works by this author on: GSW Google Scholar Gerardo Suárez; Gerardo Suárez bInstituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City 04510, Mexico, gerardo@geofisica.unam.mx Search for other works by this author on: GSW Google Scholar J. M. Espinosa‐Aranda J. M. Espinosa‐Aranda aCentro de Instrumentación y Registro Sísmico (CIRES), Anaxágoras 814, Colonia Narvarte, Mexico City 03020, Mexico Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2018) 108 (4): 2068–2079. https://doi.org/10.1785/0120180079 Article history first online: 10 Jul 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Armando Cuéllar, Gerardo Suárez, J. M. Espinosa‐Aranda; A Fast Earthquake Early Warning Algorithm Based on the First 3 s of the P‐Wave Coda. Bulletin of the Seismological Society of America 2018;; 108 (4): 2068–2079. doi: https://doi.org/10.1785/0120180079 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract A new seismic early warning algorithm is presented that estimates a magnitude threshold using the first 3 s of the P‐wave coda on the vertical component. The algorithm considerably reduces the processing time compared to previous algorithms used by the Mexican seismic early warning system (Seismic Alert System of Mexico [SASMEX]). It was designed to alert earthquakes within the subducted Cocos plate. The tP+3 algorithm was based on a training dataset of 76 accelerograms of 25 Mexican in‐slab earthquakes, with focal depths >40 km⁠. The algorithm uses two parameters based on the unfiltered vertical component of the P waves: the sum of the cumulative quadratic acceleration, av(T) and θP a parameter that represents the slope of the cumulative acceleration. The model is based on a learning machine that linearizes piecewise the empirical relation between these two parameters and magnitude Mw⁠. The resulting algorithm was tested on nine earthquakes that took place from 2014 to 2017, recorded in 37 strong‐motion records. In addition, the algorithm was evaluated in the context of the Mexican earthquake early warning, applying it to 24 in‐slab earthquakes occurring from 1995 to 2017 (⁠5.0<Mw<7.1⁠). The magnitude of 19 earthquakes was properly estimated; for four of them, it was overestimated and in one case the magnitude was underestimated. Three earthquakes Mw>6.5 that affected Mexico City were included in the dataset: the Mw 6.5 event on 11 December 2011 and the destructive in‐slab Tehuacán and Morelos earthquakes on 15 June 1999 (⁠Mw 7.0) and 19 September 2017 (⁠Mw 7.1). The retrospective application of the tP+3 algorithm shows that these three earthquakes are correctly identified as Mw>6 and would activate a seismic alert. The tP+3 algorithm would have given an advance warning of 34, 35, and 16 s respectively, before the arrival of strong motion in Mexico City. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Asymmetric dielectric breakdown behavior in MgO based magnetic tunnel junctions

The time-dependent dielectric breakdown phenomenon (TDDB) has been investigated in a series of nominally identical MgO based magnetic tunnel junctions (MTJs) by pulsed voltage endurance test. Results from the pulsed endurance test reveal that the breakdown voltage is dependent on the polarity of the applied voltage. MTJs with “UP” current stress (Iup) (flowing from reference layer (RL) to free layer (FL)) show higher endurance than that of MTJs with “DOWN” current stress (Idown). We also found that bipolar stressing could result in reduced cumulative stress time before failure as compared to unipolar stressing. This could be explained by increased charge trapping/detrapping effects during bipolar stressing. The asymmetric breakdown behavior for different polarity was further supported by the different field acceleration slopes observed in the mean time to failure (MTTF) – voltage bias trend line. Symmetric pulse scheme breakdown measurements were also carried out at different temperatures ranging from 25–85°C. The time-dependent clustering model is applied here to best describe the breakdown statistics in view of the non-uniformity in percolation breakdown due to thickness variations (interface roughness) and other process-induced damages to the ultra-thin MgO barrier layer.

Age-specific acceleration in malignant melanoma.

Background: The overall incidence of melanoma has increased steadily for several years. The relative change in incidence at different ages has not been fully described. Objective: To describe how incidence at different ages has changed over time and to consider what aspects of tumour biology may explain the observed pattern of change in incidence. Methods: The slope of incidence vs age measures the acceleration of cancer incidence with age. We described the pattern of change over time in the overall incidence of melanoma, as well as in acceleration. We used data for males and females from 3 different countries in the 17 sequential 5-year birth-cohort categories from 1895-99 to 1975-79, from which we derived the incidence patterns. Results: Over time, there has been a tendency for the overall incidence of melanoma to increase and for the acceleration (slope) of the age-incidence curves to decline. The changing patterns of melanoma incidence and acceleration differ between males and females and between the countries analysed. Conclusions: The observed pattern in melanoma of rising incidence and declining acceleration occurs in other cancers in response to genetic knockouts of mechanisms that protect against cancer. Perhaps some protective mechanism with respect to melanoma may be less effective now than in the past, possibly because of more intense environmental challenges.

Effects of shoes on kinetics and kinematics of the squash forward lunge in male players

Squash is associated with a high incidence of chronic injuries. Currently there is a trend in many sports for players to select minimalist footwear. The aim of the current investigation was to examine the effects of squashspecific, running shoes and minimalist footwear on the kinetics and 3-D kinematics of the lunge movement in squash players. Twelve male squash players performed lunge movements whilst wearing minimalist, running shoe and squash-specific footwear. 3-D kinematics of the lower extremities were measured using an eightcamera motion analysis system alongside kinetic and tibial acceleration information which were obtained using a force platform and an accelerometer. Differences between footwear were examined using one-way repeated measures ANOVA. The results show firstly that loading rate parameters were significantly greater in the minimalist (average = 85.36B.W/s and instantaneous = 179.09B.W/s) footwear in relation to the squashspecific (average = 38.66 B.W/s and instantaneous = 50.73B.W/s) and running footwear (average = 37.62B.W/s and instantaneous = 48.14B.W/s). In addition, tibial acceleration parameters were also significantly greater in the minimalist (peak tibial acceleration = 8.45 g and tibial acceleration slope = 422.28g/s) footwear in relation to the squash-specific (peak tibial acceleration = 4.33 g and tibial acceleration slope = 182.57g/s) and running footwear (peak tibial acceleration = 4.81 g and tibial acceleration slope = 226.72g/s). The significant increase in impact loading in the minimalist footwear therefore suggests this type of shoe may place squash players at an increased risk of developing impact-related chronic injuries.

Using infrared/X-ray flare statistics to probe the emission regions near the event horizon of Sgr A*

The supermassive black hole at the centre of the Galaxy flares at least daily in the infrared (IR) and X-ray bands, yet the process driving these flares is still unknown. So far detailed analysis has only been performed on a few bright flares. In particular, the broadband spectral modelling suffers from a strong lack of simultaneous data. However, new monitoring campaigns now provide data on thousands of flaring events, allowing a statistical analysis of the flare properties. In this paper, we investigate the X-ray and IR flux distributions of the flare events. Using a self-consistent calculation of the particle distribution, we model the statistical properties of the flares. Based on a previous work on single flares, we consider two families of models: pure synchrotron models and synchrotron self-Compton (SSC) models. We investigate the effect of fluctuations in some relevant parameters (e.g. acceleration properties, density, magnetic field) on the flux distributions. The distribution of these parameters is readily derived from the flux distributions observed at different wavelengths. In both scenarios, we find that fluctuations of the power injected in accelerated particles plays a major role. This must be distributed as a power-law (with different indices in each model). In the synchrotron dominated scenario, we derive the most extreme values of the acceleration power required to reproduce the brightest flares. In that model, the distribution of the acceleration slope fluctuations is constrained and in the SSC scenario we constrain the distributions of the correlated magnetic field and flow density variations.

立位乗車式買い物用電動車の開発

We are proposing a small electric vehicle which uses a low powered battery (7.2 V, approximately 2 Ah) to be used for shopping by the elderly. For this study, we have developed a standing position ride-type electric vehicle with an easy operation system in terms of easy shopping. Furthermore, steady running tests and repeated start-stop tests were conducted simulating actual vehicle use. Then, power consumption on various acceleration time are investigated to determine suitable acceleration slope. And, voltage history while getting on-off the vehicle were investigated using electromyograph. This paper will present the design with respect to easy shopping and running performance and present the experimental results.

The effects of shoe temperature on the kinetics and kinematics of running

The aim of the current investigation was to examine the effects of cooled footwear on the kinetics and kinematics of running in comparison to footwear at normal temperature. Twelve participants ran at 4.0 m/s ± 5% in both cooled and normal temperature footwear conditions over a force platform. Two identical footwear were worn, one of which was cooled for 30 min. Lower extremity kinematics were obtained using a motion capture system and tibial accelerations were measured using a triaxial accelerometer. Differences between cooled and normal footwear temperatures were contrasted using paired samples t-tests. The results showed that midsole temperature (cooled = 4.21 °C and normal = 23.25 °C) and maximal midsole deformation during stance (cooled = 12.85 mm and normal = 14.52 mm) were significantly reduced in the cooled footwear. In addition, instantaneous loading rate (cooled = 186.21 B.W/s and normal = 167.08 B W/s), peak tibial acceleration (cooled = 12.75 g and normal = 10.70 g) and tibial acceleration slope (cooled = 478.69 g/s and normal = 327.48 g/s) were significantly greater in the cooled footwear. Finally, peak eversion (cooled = −10.57 ° and normal = −7.83°) and tibial internal rotation (cooled = 10.67 ° and normal = 7.77°) were also shown to be significantly larger in the cooled footwear condition. This study indicates that running in cooled footwear may place runners at increased risk from the biomechanical parameters linked to the aetiology of injuries.

Accuracy of Doppler-Derived Indices in Predicting Pulmonary Vascular Resistance in Children With Pulmonary Hypertension Secondary to Congenital Heart Disease With Left-to-Right Shunting

This study aimed to evaluate the accuracy of Doppler echocardiography-derived indices in children with pulmonary hypertension secondary to congenital heart disease with left-to-right shunting. Doppler-derived indices including the acceleration time corrected (AcTc), deceleration time corrected, deceleration index, peak velocity, heart-rate-corrected inflection time (InTc), and a new index (the acceleration slope [Acc = peak flow velocity/AcTc]) were measured from the pulmonary artery (PA) systolic flow curve before and after 100 % oxygen administration in the main, left, and right PAs of 33 children. The acquired data were compared between low and high pulmonary vascular resistance (PVR) groups and between responders and nonresponders to the vasoreactivity test. The AcTc values differed significantly between the low and high PVR groups before and after oxygen administration in the main (P = 0.032 and <0.001, respectively), right (P = 0.011 and <0.001, respectively), and left (P < 0.001 and <0.001, respectively) PAs. The AcTc cutoff point in the main PA was 3.44 before oxygen administration (81% sensitivity and 91% specificity). The InTc in the main PA and its changes differed significantly between the low and high PVR groups before and after oxygen administration and between the responders and nonresponders (P = 0.016, 0.046, and 0.021, respectively). The velocity changes of the PA in the main PA differed significantly between the responders and nonresponders to oxygen administration (P < 0.001). The Acc and its changes differed significantly between the low and high PVR groups after oxygen administration and between the responders and nonresponders to oxygen administration (P = 0.044 and 0.006, respectively). Doppler echocardiographic examination using PA systolic flow indices in addition to PA reactivity testing is a promising technique for assessing PVR in children with congenital heart disease.

Leg Tissue Mass Composition Affects Tibial Acceleration Response Following Impact

To date, there has not been a direct examination of the effect that tissue composition (lean mass/muscle, fat mass, bone mineral content) differences between males and females has on how the tibia responds to impacts similar to those seen during running. To evaluate this, controlled heel impacts were imparted to 36 participants (6 M and 6 F in each of low, medium and high percent body fat [BF] groups) using a human pendulum. A skin-mounted accelerometer medial to the tibial tuberosity was used to determine the tibial response parameters (peak acceleration, acceleration slope and time to peak acceleration). There were no consistent effects of BF or specific tissue masses on the un-normalized tibial response parameters. However, females experienced 25% greater peak acceleration than males. When normalized to lean mass, wobbling mass, and bone mineral content, females experienced 50%, 62% and 70% greater peak acceleration, respectively, per gram of tissue than males. Higher magnitudes of lean mass and bone mass significantly contributed to decreased acceleration responses in general.

The mitral late diastolic flow acceleration slope after the restoration of sinus rhythm in acute atrial fibrillation: relationship to atrial function and change over time

This study was prospectively designed to evaluate the relationship between the mitral A wave acceleration slope (AWA-slope) and the left atrial ejection fraction (LA-EF) after the restoration of sinus rhythm in patients with atrial fibrillation (AF), and also to evaluate the change in the AWA-slope between the sequent second day and first month. Twenty-nine patients (16 female, mean age 56 ± 13 years) with unknown cause of AF (except for age) converted to sinus rhythm within the first 48 hours were included into the study. A transthoracic echocardiography was performed in all patients on the second day and the first month after restoration of the sinus rhythm. The paired Student's t test was used in comparisons of the continuous variables. The simple and multiple correlations of the LA-EF were evaluated by the simple and multiple linear regression analyses, respectively. Left atrial ejection fraction (42 ± 17 vs 51 ± 19%, p=0.03) and AWA-slope (950 ± 337 vs 1087 ± 351 cm/sec2, p=0.021) obtained after the first month were greater than on the second day. A significant correlation between LA-EF and AWA-slope was observed both on the second day (r=0.76, p=0.001) and at the end of the first month (r=0.71, p=0.001). In addition, there were the correlations between LA-EF and mitral A wave peak velocity (r=0.42, p=0.025) or mitral E/A ratio (r=-0.39, p=0.040) at the end of the first month. On multiple linear regression analysis, only AWA-slope was found to be related to LA-EF (y=9.35+0.04 (AWA-slope), the overall R2=0.51, beta =0.71; 95% CI 0.02-0.05; p=0.001). Mitral A wave acceleration slope is a simple, reliable and non-invasive method that can be used to evaluate left atrial contractile function. It can also be used in monitoring of atrial stunning period in patients with sinus rhythm converted from AF.