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A unilateral transfemoral amputation (TFA) has a major impact on function. A leg-length discrepancy is the primary structural change, accompanied by the loss of lower-limb muscle volume and function. Prostheses can help individuals with a TFA to regain function, but such individuals still do not reach the functional level of unimpaired peers and exhibit gait deviations. This study gives insight into the causality between residual limb strength and gait deviations in individuals with a TFA. A convenient sample of 13 male individuals with a TFA (38.0 ± 12.6y; 179.7cm ± 6.5cm; 82.9kg ± 12.4kg) was recruited for this study. One participant with TFA was excluded, as he differed from the rest of the cohort, in residual limb length and the use of walking aids. A cohort of 18 unimpaired subjects served as a reference group (REF; nine females; 44y ± 13y; 174cm ± 9cm; 71kg ± 12kg). All participants underwent a conventional clinical gait analysis using a marker based 3D motion capture system and force platforms. Kinematics and kinetics were determined utilizing standard modelling methods. All subjects underwent a strength test, using a custom-made device to determine isometric moments of the hip joint in abduction, adduction, extension, and flexion. Peak values for maximum isometric moments for each movement direction and selected kinematic and kinetic values were derived from the results. Differences between subjects with TFA and unimpaired were compared using a Mann-Whitney U Test and associations between groups by Spearman's rank correlation. The participants with a TFA showed a significantly lower maximum isometric moment for hip abduction (0.85 vs. 1.41 Nm/kg p < .001), adduction (0.87 vs. 1.37 Nm/kg p = .001) and flexion (0.93 vs. 1.63 Nm/kg p = .010) compared to the reference group. Typically reported gait deviations in people with a TFA were identified, i.e. significant lower cadence and increased step width. We further identified altered coronal plane hip and trunk kinematics, with significantly higher ranges of motion during involved side stance-phase. Gait kinetics of individuals with a TFA showed significantly lower peak values during stance for hip abduction, adduction and extension moments in comparison to the reference group. We identified a moderate negative correlation between maximum isometric moment for hip abduction and trunk obliquity range of motion (ρ = -0.45) for participants with a TFA, which was not significant (p = 0.14). We showed that there are strength deficits in individuals with TFA and, that there are moderate correlations between gait deviations, i.e. lateral trunk lean during involved side stance and isometric hip abductor moment. The relation between maximum moments during gait and the corresponding maximum isometric moment may therefore be helpful to detect strength related compensation mechanisms. However, the moderate, non-significant correlation between lateral trunk lean and isometric hip abductor moment was the only one which corresponded directly to a gait deviation. Thus results must be interpreted with care. This study suggests that gait deviations in individuals with TFA are multifactorial and cannot be exclusively explained by their strength deficits. Future studies should explore the relationship between strength with kinematics and kinetics during gait in this population.

Purpose - This study aims to evaluate the presence of abnormal returns due to stock splits or reverse stock splits in the Brazilian capital market context. Design/methodology/approach The event study technique was used on data from 518 events that occurred in a 30-year period (1987-2016), comprising 167 stock splits and 351 reverse stock splits. Findings The results revealed the occurrence of abnormal returns around the time the shares began trading stock splits or reverse stock splits at a statistical significance level of 5%. The main conclusion is that stock split and reverse stock split operations represent opportunities for extraordinary gains and may serve as a reference for investment strategies in the Brazilian stock market. Originality/value This study innovates by including reverse stock splits, as the existing literature focuses on stock splits, and by testing two distinct \"zero\" dates that of the ordinary general meeting that approved the share alteration and the \"ex\" date of the alteration, when the shares were effectively traded, reverse split or split.

Objectives We evaluated the potential of prospectively ECG-triggered high-pitch spiral acquisition with low tube voltage and current in combination with iterative reconstruction to achieve coronary CT angiography with sufficient image quality at an effective dose below 0.1 mSv. Methods Contrast-enhanced coronary dual source CT angiography (2 × 128 × 0.6 mm, 80 kV, 50 mAs) in prospectively ECG-triggered high-pitch spiral acquisition mode was performed in 21 consecutive individuals (body weight <100 kg, heart rate ≤60/min). Images were reconstructed with raw data-based filtered back projection (FBP) and iterative reconstruction (IR). Image quality was assessed on a 4-point scale (1 = no artefacts, 4 = unevaluable). Results Mean effective dose was 0.06 ± 0.01 mSv. Image noise was significantly reduced in IR (128.9 ± 46.6 vs. 158.2 ± 44.7 HU). The mean image quality score was lower for IR (1.9 ± 1.1 vs. 2.2 ± 1.0, P  < 0.0001). Of 292 coronary segments, 55 in FBP and 40 in IR ( P  = 0.12) were graded “unevaluable”. In patients with a body weight ≤75 kg, both in FBP and in IR, the rates of fully evaluable segments were significantly higher in comparison to patients >75 kg. Conclusions Coronary CT angiography with an estimated effective dose <0.1 mSv may provide sufficient image quality in selected patients through the combination of high-pitch spiral acquisition and raw data-based iterative reconstruction. Key Points • Coronary CT angiography with an estimated effective dose <0.1 mSv is possible. • Combination of high-pitch spiral acquisition with iterative reconstruction achieves sufficient image quality. • Diagnostic accuracy remains to be assessed in future trials.

The lifetime of the battery significantly influences the acceptance of electric vehicles. Calendar aging contributes to the limited operating lifetime of lithium-ion batteries. Therefore, its consideration in addition to cyclical aging is essential to understand battery degradation. This study consequently examines the same graphite/NCA pouch cell that was the subject of previously published cyclic aging tests. The cells were aged at different temperatures and states of charge. The self-discharge was continuously monitored, and after each storage period, the remaining capacity and the impedance were measured. The focus of this publication is on the correlation of the measurements. An aging correlation is obtained that is valid for a wide range of temperatures and states of charge. The results show an accelerated capacity fade and impedance rise with increasing temperature, following the law of Arrhenius. However, the obtained data do also indicate that there is no path dependency, i.e., earlier periods at different temperature levels do not affect the present degradation rate. A large impact of the storage state of charge at 100% is evident, whereas the influence is small below 80%. Instead of the commonly applied square root of the time function, our results are in excellent agreement with an exponential function.

Alongside electrical loads, it is known that temperature has a strong influence on battery behavior and lifetime. Investigations have mainly been performed at homogeneous temperatures and non-homogeneous conditions in single cells have at best been simulated. This publication presents the development of a methodology and experimental setup to investigate the influence of thermal boundary conditions during the operation of lithium-ion cells. In particular, spatially inhomogeneous and transient thermal boundary conditions and periodical electrical cycles were superimposed in different combinations. This required a thorough design of the thermal boundary conditions applied to the cells. Unlike in other contributions that rely on placing cells in a climatic chamber to control ambient air temperature, here the cell surfaces and tabs were directly connected to individual cooling and heating plates. This improves the control of the cells’ internal temperature, even with high currents accompanied by strong internal heat dissipation. The aging process over a large number of electrical cycles is presented by means of discharge capacity and impedance spectra determined in repeated intermediate characterizations. The influence of spatial temperature gradients and temporal temperature changes on the cyclic degradation is revealed. It appears that the overall temperature level is indeed a decisive parameter for capacity fade during cyclic aging, while the intensity of a temperature gradient is not as essential. Furthermore, temperature changes can have a substantial impact and potentially lead to stronger degradation than spatial inhomogeneities.

Objective We evaluated radiation exposure and image quality of a new coronary CT angiography protocol, high-pitch spiral acquisition, using dual source CT (DSCT). Material and methods Coronary CTA was performed in 25 consecutive patients with a stable heart rate of 60 bpm or less after premedication, using 2 × 128 0.6-mm sections, 38.4-mm collimation width and 0.28-s rotation time. Tube settings were 100 kV/320 mAs and 120 kV/400 mAs for patients below and above 100-kg weight, respectively. Data acquisition was prospectively ECG-triggered at 60% of the R–R interval using a pitch of 3.2 (3.4 for the last 10 patients). Images were reconstructed with 75-ms temporal resolution, 0.6-mm slice thickness and 0.3-mm increment. Image quality was evaluated using a four-point scale (1 = excellent, 4 = unevaluable). Results Mean range of data acquisition was 113 ± 22 mm, mean duration was 268 ± 23 ms. Of 363 coronary artery segments, 327 had an image quality score of 1, and only 2 segments were rated as “unevaluable”. Mean dose–length product (DLP) was 71 ± 23 mGy cm, mean effective dose was 1.0 ± 0.3 mSv (range 0.78–2.1 mSv). For 21 patients with a body weight below 100 kg, mean DLP was 63 ± 5 mGy cm (0.88 ± 0.07 mSv; range 0.78–0.97 mSv). Conclusion Prospectively ECG-triggered high-pitch spiral CT acquisition provides high and stable image quality at very low radiation dose.

Although recent studies showed the prognostic value of cardiac magnetic resonance (CMR) parameters especially microvascular obstruction (MO) after reperfused ST-elevation myocardial infarction (STEMI), a study assessing their prognostic significance for long-term follow-up is missing so far. The objective of this study was to determine the prognostic impact of MO on long-term prognosis after reperfused first STEMI in a setting allocating CMR-assessed parameters to hard clinical events only. In 249 patients, CMR was performed after reperfused STEMI, and hereby, left ventricular ejection fraction (LVEF), infarct size (IS), and the amount of MO were quantified. Follow-up (median 6.0 years) was obtained regarding occurrence of major adverse cardiac events (MACE). MACE occurred more often in patients showing presence of MO (MO vs no MO: n = 61 [54%] vs n = 12 [9%], p <0.0001). By multivariate analysis, the extent of MO remained the strongest predictor (p <0.001) for occurrence of MACE and provided incremental prognostic value over clinical variables and LVEF (p = 0.028, c-index increase from 0.723 to 0.817). In conclusion, CMR-assessed MO proves predictive for assessment of 6-year prognosis in patients after reperfused first STEMI and provides incremental prognostic information over clinical variables and LVEF in a setting based on hard end points.

The teeth of all vertebrates predominantly comprise the same materials, but their lifespans vary widely: in stark contrast to mammals, shark teeth are functional only for weeks, rather than decades, making lifelong durability largely irrelevant. However, their diets are diverse and often mechanically demanding, and as such, their teeth should maintain a functional morphology, even in the face of extremely high and potentially damaging contact stresses. Here, we reconcile the dilemma between the need for an operative tooth geometry and the unavoidable damage inherent to feeding on hard foods, demonstrating that the tooth cusps of Port Jackson sharks, hard-shelled prey specialists, possess unusual microarchitecture that controls tooth erosion in a way that maintains functional cusp shape. The graded architecture in the enameloid provokes a location-specific damage response, combining chipping of outer enameloid and smooth wear of inner enameloid to preserve an efficient shape for grasping hard prey. Our discovery provides experimental support for the dominant theory that multi-layered tooth enameloid facilitated evolutionary diversification of shark ecologies. Shark teeth have short lifespans yet can be subject to significant mechanical damage. Here, the authors report on a site-specific damage mechanism in shark teeth enameloid, which maintains tooth functional shape, providing experimental evidence that tooth architecture may have influenced the diversification of shark ecologies over evolution.

Temperature has a significant influence on the behavior of batteries and their lifetime. There are several studies in literature that investigate the aging behavior under electrical load, but are limited to homogeneous, constant temperatures. This article presents an approach to quantifying cyclic aging of lithium-ion cells that takes into account complex thermal boundary conditions. It not only considers different temperature levels but also spatial and transient temperature gradients that can occur despite-or even due to-the use of thermal management systems. Capacity fade and impedance rise are used as measured quantities for degradation and correlated with the temperature boundary conditions during the aging process. The concept and definition of an equivalent aging temperature (EAT) is introduced to relate the degradation caused by spatial and temporal temperature inhomogeneities to similar degradation caused by a homogeneous steady temperature during electrical cycling. The results show an increased degradation at both lower and higher temperatures, which can be very well described by two superimposed exponential functions. These correlations also apply to cells that are cycled under the influence of spatial temperature gradients, both steady and transient. Only cells that are exposed to transient, but spatially homogeneous temperature conditions show a significantly different aging behavior. The concluding result is a correlation between temperature and aging rate, which is expressed as degradation per equivalent full cycle (EFC). This enables both temperature-dependent modeling of the aging behavior and its prediction.

Improvements in image quality in cardiac computed tomography may be achieved through iterative image reconstruction techniques. We evaluated the ability of “Iterative Reconstruction in Image Space” (IRIS) reconstruction to reduce image noise and improve subjective image quality. 55 consecutive patients undergoing coronary CT angiography to rule out coronary artery stenosis were included. A dual source CT system and standard protocols were used. Images were reconstructed using standard filtered back projection and IRIS. Image noise, attenuation within the coronary arteries, contrast, signal to noise and contrast to noise parameters as well as subjective classification of image quality (using a scale with four categories) were evaluated and compared between the two image reconstruction protocols. Subjective image quality (2.8 ± 0.4 in filtered back projection and 2.8 ± 0.4 in iterative reconstruction) and the number of “evaluable” segments per patient 14.0 ± 1.2 in filtered back projection and 14.1 ± 1.1 in iterative reconstruction) were not significant different between the two methods. However iterative reconstruction had a lower image noise (22.6 ± 4.5 HU vs. 28.6 ± 5.1 HU) and higher signal to noise and image to noise ratios in the proximal coronary arteries. IRIS reduces image noise and contrast-to-noise ratio in coronary CT angiography, thus providing potential for reducing radiation exposure.