scholarly journals The influence of sagittal trunk lean on uneven running mechanics

2020 ◽  
Vol 224 (1) ◽  
pp. jeb228288
Author(s):  
Soran AminiAghdam ◽  
Reinhard Blickhan ◽  
Kiros Karamanidis
Keyword(s):  
Centre Of Mass ◽  
Leg Length ◽  
Mass Model ◽  
Ankle Stiffness ◽  
Trunk Posture ◽  
Step Down ◽  
Posterior Trunk ◽  
Running Mechanics ◽  
Mass Position

ABSTRACTThe role of trunk orientation during uneven running is not well understood. This study compared the running mechanics during the approach step to and the step down for a 10 cm expected drop, positioned halfway through a 15 m runway, with that of the level step in 12 participants at a speed of 3.5 m s−1 while maintaining self-selected (17.7±4.2 deg; mean±s.d.), posterior (1.8±7.4 deg) and anterior (26.6±5.6 deg) trunk leans from the vertical. Our findings reveal that the global (i.e. the spring-mass model dynamics and centre-of-mass height) and local (i.e. knee and ankle kinematics and kinetics) biomechanical adjustments during uneven running are specific to the step nature and trunk posture. Unlike the anterior-leaning posture, running with a posterior trunk lean is characterized by increases in leg angle, leg compression, knee flexion angle and moment, resulting in a stiffer knee and a more compliant spring-leg compared with the self-selected condition. In the approach step versus the level step, reductions in leg length and stiffness through the ankle stiffness yield lower leg force and centre-of-mass position. Contrariwise, significant increases in leg length, angle and force, and ankle moment, reflect in a higher centre-of-mass position during the step down. Plus, ankle stiffness significantly decreases, owing to a substantially increased leg compression. Overall, the step down appears to be dominated by centre-of-mass height changes, regardless of having a trunk lean. Observed adjustments during uneven running can be attributed to anticipation of changes to running posture and height. These findings highlight the role of trunk posture in human perturbed locomotion relevant for the design and development of exoskeleton or humanoid bipedal robots.

scholarly journals Dark matter candidates in a type-II radiative neutrino mass model

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Roberto A. Lineros ◽  
Mathias Pierre
Keyword(s):  
Dark Matter ◽  
Neutral Particle ◽  
Matter Density ◽  
Indirect Detection ◽  
Dark Matter Candidate ◽  
Neutrino Masses ◽  
Type Ii ◽  
Mass Model ◽  
Direct And Indirect Detection

Abstract We explore the connection between Dark Matter and neutrinos in a model inspired by radiative Type-II seessaw and scotogenic scenarios. In our model, we introduce new electroweakly charged states (scalars and a vector-like fermion) and impose a discrete ℤ2 symmetry. Neutrino masses are generated at the loop level and the lightest ℤ2-odd neutral particle is stable and it can play the role of a Dark Matter candidate. We perform a numerical analysis of the model showing that neutrino masses and flavour structure can be reproduced in addition to the correct dark matter density, with viable DM masses from 700 GeV to 30 TeV. We explore direct and indirect detection signatures and show interesting detection prospects by CTA, Darwin and KM3Net and highlight the complementarity between these observables.

The effects of differences on sagittal kinematics and muscle coordination during step up and step down in patients with spinal stenosis

2021 ◽  
pp. 1-7
Author(s):  
Sun-Shil Shin ◽  
Won-Gyu Yoo
Keyword(s):  
Spinal Stenosis ◽  
Vastus Lateralis ◽  
Center Of Mass ◽  
Gluteus Medius ◽  
Muscle Coordination ◽  
Limb Muscle ◽  
Compensatory Mechanisms ◽  
Contraction Ratio ◽  
Trunk Posture ◽  
Step Down

BACKGROUND AND OBJECTIVE: Lumbar spinal stenosis (LSS) is a common spinal disorder that causes patients to assume a forward-trunk posture. Spinal alignment affects swing limb angles and stance limb muscle activities. Therefore, we investigated the effects of differences in step up (SU) and step down (SD) tasks on the kinematics of the trunk and swing limb as well as stance limb muscle coordination in patients with LSS. METHODS: Nine elderly female patients diagnosed with LSS were recruited for this study. The sagittal kinematics of the trunk and swing limb and isolated contraction ratio of the gluteus medius (GMed) and vastus lateralis (VL) during SU and SD tasks were measured using a motion analysis system and surface electromyography system. RESULTS: Thoracic (17.71∘± 7.77∘) and spine angles (13.64∘± 11.34∘) as well as swing hip (48.48 ± 12.76) and pelvic angles (7.52 ± 10.33) were significantly greater during SU than SD (10.14 ± 8.41, 10.03 ± 11.03, 29.42 ± 10.57, 3.21 ± 10.11, all P< 0.05, respectively). The isolated contraction ratio of the GMed of the stance limb (34.12% ± 13.28%) was significantly higher during SU than during SD (26.65% ± 10.02%), whereas that of the VL of the stance limb (65.88% ± 13.28%) was significantly lower during SU than during SD (73.35% ± 10.02%, P= 0.011 for both comparisons). CONCLUSIONS: Patients with LSS demonstrated trunk compensatory mechanisms to address swing hip and knee angles. Trunk position affected pelvic limb muscle coordination in the standing support limb. These findings demonstrate that SD are more challenging than SU for patients with LSS, possibly due to reduced ability to generate adequate leg extensor muscular output to safely control the motion of the body’s center of mass. Therefore, trunk positions must be considered when patients with LSS undergo rehabilitation programs, particularly those involving SD or descending stairs, so that healthcare professionals can better assist patients with LSS. In addition, this study provides a background for further studies.

scholarly journals A Three-Dimensional Skeletal Reconstruction of the Stem Amniote Orobates pabsti (Diadectidae): Analyses of Body Mass, Centre of Mass Position, and Joint Mobility

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0137284 ◽  
Author(s):  
John A. Nyakatura ◽  
Vivian R. Allen ◽  
Jonas Lauströer ◽  
Amir Andikfar ◽  
Marek Danczak ◽  
...  
Keyword(s):  
Body Mass ◽  
Three Dimensional ◽  
Joint Mobility ◽  
Centre Of Mass ◽  
Mass Centre ◽  
Mass Position ◽  
Skeletal Reconstruction

scholarly journals The Role of Alteration of Glutamic Acid and Gaba in Learning and Memory Impairment of Rats Induced by Aluminum

2005 ◽  
Vol 3 (2) ◽  
pp. 97-101
Author(s):  
Q. Niu ◽  
P. Niu ◽  
Q. Zhang ◽  
L. Wang ◽  
S. He ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cerebral Cortex ◽  
Glutamic Acid ◽  
Learning And Memory ◽  
Memory Impairment ◽  
High Performance ◽  
Gamma Aminobutyric Acid ◽  
Aluminum Exposure ◽  
Step Down

Aluminum exposure has been reported to be related to learning and memory impairment. This study examines the role of aluminum in alterating amino acids of the cerebral cortex of rats. The Step-down type tests were performed to investigate the alteration of learning and memory of rats induced by aluminum. The amino acids in the cerebral cortex were detected by high performance liquid chromatography (HLPC). Results show that the amounts of aluminum in the cerebral cortex increased by 5.0mgAl3+/(Kg·BW) group and 10.0mg Al3+/(Kg·BW) group. In the Step-down type test, the EN1 increased significantly in the Al3+ 10.0mg/(Kg·BW) group. The latency shortened obviously and the EN2 increased significantly in the 10.0mg Al3+/(Kg·BW) group. The content of Glu (Glutamic acid) increased but the content of GABA (gamma-aminobutyric acid) decreased significantly in the 10.0mg Al3+/(Kg·BW) group. This present study shows evidence that the disorder of amino acid neurotransmitters system plays an important role in the impairment of learning and memory of rats induced by aluminum.

Horizontal Smooth Pursuit Adaptation in Macaques After Muscimol Inactivation of the Dorsolateral Pontine Nucleus (DLPN)

2007 ◽  
Vol 98 (5) ◽  
pp. 2918-2932 ◽  
Author(s):  
Seiji Ono ◽  
Michael J. Mustari
Keyword(s):  
Smooth Pursuit ◽  
Visual Motion ◽  
T Test ◽  
Motion Information ◽  
Unit Recording ◽  
Pontine Nucleus ◽  
Dorsolateral Pontine Nucleus ◽  
Step Down ◽  
Ventral Paraflocculus

The smooth pursuit (SP) system can adapt its response to developmental changes, injury, and behavioral context. Previous lesion and single-unit recording studies show that the macaque cerebellum plays a role in SP initiation, maintenance, and adaptation. The aim of this study was to determine the potential role of the DLPN in SP adaptation. The DLPN receives inputs from the cortical SP system and delivers eye and visual motion information to the dorsal/ventral paraflocculus and vermis of the cerebellum. We studied SP adaptation in two juvenile rhesus monkeys ( Macaca mulatta), using double steps of target speed that step- up (10–30°/s) or step-down (25–5°/s). We used microinjection of muscimol (≤2%; 0.15 μl) to reversibly inactivate the DLPN, unilaterally. After DLPN inactivation, initial ipsilesional SP acceleration (first 100 ms) was significantly reduced by 47–74% ( P < 0.01; unpaired t-test) of control values in the single-speed step-ramp paradigm. Similarly, ipsilesional steady-state SP velocity was also reduced by 59–78% ( P < 0.01; unpaired t-test) of control values. Contralesional SP was not impaired after DLPN inactivation. Control testing showed significant adaptive changes of initial SP eye acceleration after 100 trials in either step-up or step-down paradigms. After inactivation, during ipsilesional SP, adaptation was impaired in the step-up but not in the step-down paradigm. In contrast, during contralesional tracking, adaptive capability remained in the step-down but not in the step-up paradigm. Therefore SP adaptation could depend, in part, on direction sensitive eye/visual motion information provided by DLPN neurons to cerebellum.

scholarly journals Simulations of dense-snow avalanches on deflecting dams

1998 ◽  
Vol 26 ◽  
pp. 265-271 ◽  
Author(s):  
Fridtjov Irgens ◽  
Bonsak Schieldrop ◽  
Carl B. Harbitz ◽  
Ulrik Domaas ◽  
Runar Opsahl
Keyword(s):  
Three Dimensional ◽  
Angle Of Incidence ◽  
Snow Avalanches ◽  
Centre Of Mass ◽  
Lumped Mass ◽  
Mass Model ◽  
One Dimensional ◽  
Lumped Mass Model ◽  
Flowing Material ◽  
Run Up

Two models simulating snow avalanches impacting retaining dams at oblique angles of incidence are presented.First, a lumped-mass model applying the Voellmy-Perla equation is used to calculate the path of the centre-of-mass along the side of a retaining dam.Secondly, a one-dimensional continuum model, applying depth-integrated equations of balance of mass and linear momentum, is expanded to take into account that real avalanche flows are three-dimensional. The centre-line of the avalanche path is determined by the flowing material as it progresses down the channelized avalanche path. The nonlinear constitutive equations comprise viscosity, visco-elasticity and plasticity.Both models are calibrated by simulations of a registered avalanche following a strongly curved channel. The path and the run-up height of the avalanche on the natural deflecting dam with oblique angle of incidence as calculated by the two models, are compared with the observations made.

Role of the hip flexors in trunk posture during walking

Physiotherapy ◽  
2015 ◽  
Vol 101 ◽  
pp. e684 ◽  
Author(s):  
T. Jiroumaru ◽  
R. Fujitani ◽  
N. Kanazawa
Keyword(s):  
Trunk Posture

4 The step-down principle in gonadotrophin treatment and the role of GnRH analogues

1993 ◽  
Vol 7 (2) ◽  
pp. 309-330 ◽  
Author(s):  
Bart C.J.M. Fauser ◽  
Peter Donderwinkel ◽  
Dick C. Schoot
Keyword(s):  
Gnrh Analogues ◽  
Step Down
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