Inertial units offer a promising alternative to optoelectronic systems for joint lower limbs kinematic analysis. However, only one study 1 has made a proposal for sensor-to-segment calibration (S2S ...calibration) dedicated to patients even though this S2S calibration is a crucial step in the procedure 2.This study proposes to investigate whether it is possible to define a customizable protocol that could take the functional capacities of the analyzed patient into account.
Passive joint moments (PM) have been estimated in-vivo in several studies by measuring the applied forces and moments while manipulating the joint 1,2. Nevertheless, in most of the studies, ...simplified approaches are used to calculate these PM. The most common simplification is to considerthat the axes of the dynamometerare aligned with those of the manipulated segment 1,2. This way, no dynamometer's kinematics measurements is required.
In <xref ref-type="bibr" rid="ref1">1 , the centripetal accelerations, ac, in Figures 2, 4, 5, 6, 7, and 8 are presented in units of g , not m/s 2 (1 g = 9.80665 m/s 2 ).
Age determination in echinoderms Sun, Jiamin; Hamel, Jean-François; Gianasi, Bruno L. ...
Proceedings of the Royal Society. B, Biological sciences,
07/2019, Letnik:
286, Številka:
1906
Journal Article
Recenzirano
While age is fundamental in animal biology, forming the basis of critical concepts such as life-history strategies, longevity and population structures, measuring this variable in some taxa remains ...problematic. Such is the case of holothuroid echinoderms, which play key roles in marine benthic communities from the shore to the abyss, and which are extensively fished in many regions across the globe. Here, we present and validate a promising ageing technique using the cold-water species Psolus fabricii. The method involves the extraction of the oldest dermal plates (largest dorsal ossicles) to preserve their original pigments and structure. While plates initially appear to have a uniform texture, polishing and dying them reveals layered ring patterns. A study of laboratory-reared juveniles, from settlement to 40 months of age, confirmed that one layer is added annually, making plates both larger and thicker, and generating successive light and dark rings, the latter representing the transition (overlap) between two layers. Therefore, each pair of rings represents an annual growth band. Size-at-age data obtained using this method revealed that growth of P. fabricii is slow and that wild individuals collected at diving depths had reached an age of several decades.
Force enhancement (FE) is a phenomenon that is present in skeletal muscle. It is characterized by progressive forces upon active stretching—distinguished by a linear rise in force—and enhanced ...isometric force following stretching (residual FE (RFE)). In skeletal muscle, non-cross-bridge (XB) structures may account for this behaviour. So far, it is unknown whether differences between non-XB structures within the heart and skeletal muscle result in deviating contractile behaviour during and after eccentric contractions. Thus, we investigated the force response of intact cardiac trabeculae during and after isokinetic eccentric muscle contractions (10% of maximum shortening velocity) with extensive magnitudes of stretch (25% of optimum muscle length). The different contributions of XB and non-XB structures to the total muscle force were revealed by using an actomyosin inhibitor. For cardiac trabeculae, we found that the force–length dynamics during long stretch were similar to the total isometric force–length relation. This indicates that no (R)FE is present in cardiac muscle while stretching the muscle from 0.75 to 1.0 optimum muscle length. This finding is in contrast with the results obtained for skeletal muscle, in which (R)FE is present. Our data support the hypothesis that titin stiffness does not increase with activation in cardiac muscle.
The influence of pelvic incidence (PI) on spinopelvic and hip alignment and mobility has not been well investigated. The aim of this study was to evaluate the influence of PI on spinopelvic and hip ...alignment and mobility, including the pelvic-femoral angle (PFA) and motion (ΔPFA), in functional positions in a cohort of asymptomatic volunteers.
This was a single-center, prospective, cross-sectional study. We included 136 healthy volunteers (69% female; mean age, 38 ± 11 years; mean body mass index, 22 ± 3 kg/m2) divided into 3 subgroups on the basis of their PI: PI < 45° (low PI), 45° ≤ PI ≤ 60° (medium PI), and PI > 60° (high PI). We made full-body lateral radiographs in free-standing, standing with extension, relaxed-seated, and flexed-seated positions. We measured the sacral slope (SS), lumbar lordosis (LL), and PFA. We calculated lumbar (∆LL), pelvic (∆SS), and hip (∆PFA) mobilities as the change between the standing (i.e., standing with or without extension) and sitting (i.e., relaxed-seated or flexed-seated) positions.
There were significant differences between some of the 3 subgroups with respect to the LL, SS, and PFA in each of the 4 positions. There were no significant differences in ΔLL, ΔSS, or ΔPFA between the 3 groups when moving from a standing to a sitting position. PI had an inverse linear correlation with PFAextension (R = -0.48; p < 0.0001), PFAstanding (R = -0.53; p < 0.0001), PFArelaxed-seated (R = -0.37; p < 0.0001), and PFAflexed-seated (R = -0.47; p < 0.0001). However, PI was not correlated with ΔPFAstanding/relaxed-seated (R = -0.062; p = 0.48) or ΔPFAextension/flexed-seated (R = -0.12; p = 0.18). Similarly, PI was not significantly correlated with ΔLL or ΔSS in either pair of positions.
This study confirmed that spinopelvic and hip parameters in functional positions were affected by PI, whereas lumbar, pelvic, and hip mobilities did not depend on PI. These findings suggest that hip surgeons should consider the PI of the patient to determine the patient's specific functional safe zones before and after total hip arthroplasty.
Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.
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