Body Stability Research Articles

Investigating Biomechanical Postural Control Strategies in Healthy Aging Adults and Survivors of Stroke

As the aging populations, both nationwide and worldwide, rapidly increase, falls leading to unintentional injury and death subsequently increase. Thus, developing an understanding of biomechanical postural control strategies used to maintain balance in aging healthy adults, and those that have suffered stroke, are critical. Here, we were interested in how one’s body segments stabilize relative to one another, and in space, in order to maintain balance. To accomplish this goal, we studied 30 healthy individuals and 8 survivors of stroke between 60 and 85 years old, both before and after several weeks of sensory training. Motion capture data were acquired to assess participants’ body kinematics during walking: forward (easiest), forward-tandem, backward, and backward-tandem walking (most challenging). Deviations (via the observation of the absolute angle with deviations, or AADs) of the head, thorax, and lumbar areas relative to an earth vertical reference, as well as how one body segment stabilized in space or relative to the inferior body segment (via the observation of anchoring indices, or AIs), were explored. The results provide metrics (AADs and AIs) that can assess aging posture. Further, the results show an initial indication that, for aging individuals, training could lead to improved head and body stabilization in space.

Static and seismic stability investigation of a bamboo grid reinforced slope with different stepped reinforcing arrangements

Bamboo is primarily used as a soil reinforcement material to build roadways and stabilize slopes and river banks. The current study aims to examine how bamboo grid reinforcing slopes behave in the form of various stepped reinforcing arrangements. The static and seismic characteristics of a slope reinforced with a bamboo grid were examined through 3D numerical analyses employing the finite element program MIDAS GTS NX (340) 2023 v1.1. In this study, the Strength Reduction Method (SRM), a crucial technique in finite element analysis, is utilized to compute the factor of safety and displacement in static stability analysis. Seismic stability analysis is conducted using non-linear time history analysis, examining the changes in critical slope parameters in response to seismic excitation. Three distinct arrangements of bamboo grids were employed to enhance slope stability. Static stability analysis, considering the factor of safety and deformation, was conducted for various bamboo grid-reinforced slope arrangements. Additionally, a comprehensive seismic analysis was performed specifically for the type 2 bamboo grid reinforcement arrangement, using the seismic record from the 1971 San Fernando Down earthquake. The safety factor increases by 52.10%, 68.67%, and 62.65% for type 1, 2, and 3 arrangements, respectively, compared to the unreinforced slope. Consequently, the type 2 bamboo grid-reinforced slope arrangement exhibits superior stability in terms of the safety factor. The lateral displacement of the type 2 arrangement is minimal compared to other types. Furthermore, a bamboo grid-reinforced slope with a vertical spacing of 1.5 m demonstrates less deformation than slopes with different vertical spacings. The seismic stability of the slope body surpasses other sections of the bamboo grid-reinforced slope.

Analysis of the Research Progress on the Impact of Lumbosacral Transitional Vertebra on the Lumbopelvic-Hip Complex

The lumbosacral transitional vertebra is a common congenital variation. The presence of LSTV can result in smaller benefits for the population after total hip arthroplasty. Although extensive research has been conducted on the association between LSTV and lumbopelvic-hip complex syndrome in populations undergoing total hip arthroplasty, with convincing evidence suggesting that the presence of LSTV can have a negative impact on the outcomes of total hip arthroplasty, there is currently a lack of exploration into the association between LSTV and hip joint anatomical development, as well as its correlation with lumbopelvic-hip complex syndrome. The lumbopelvic-hip complex (LPHC) is a key structure for maintaining body stability and transmitting forces. Lumbosacral transitional vertebra (LSTV) is one of the most common congenital variations at the lumbosacral junction, which has a certain influence on the line of force transmission to the pelvis and hip joints and plays a role in the occurrence and development of hip and lumbar back pain.

An improved transfer coefficient method considering the combined effect of reservoir level variation and rainfall and its application in the stability evaluation of multistage sliding ancient landslides

Abstract In this paper, by considering the dynamic water pressure and particle migration effect caused by reservoir level variation, the weakening effect of slip zone soil influenced by rainfall infiltration, and the interaction force between multistage sliding bodies, an improved transfer coefficient method for multistage sliding ancient landslide is proposed under the combined action of reservoir level variation and rainfall. The results show that (1) the combined action of reservoir level variation and rainfall has a significant influence on the stability of multistage sliding ancient landslides. (2) The sliding force calculated by the improved transfer coefficient method is smaller than the calculation result by the traditional transfer coefficient method, and the residual sliding force is larger. The different sliding body stability coefficient is reduced by about 28.84, 18.13, 19.26, and 21.01%, respectively. (3) The stability results calculated by the traditional transfer coefficient are higher than the improved transfer coefficient method, which may lead to deviation in the multistage sliding ancient landslide stable state judgment. (4) This improved transfer coefficient method can provide a reference for the multistage sliding ancient landslides stability accurate evaluation in hydropower station reservoir area.

Classical PID Control of A Quadcopter UAV Under Variable Load Conditions

In recent years, the application of UAVs has become more and more extensive, resulting in a number of special operation UAVs. Quadrotor aerial robots have become one of the most popular vehicles at home and abroad because of their small size, light weight, simple structure, low cost, low requirements for takeoff and landing, and good maneuverability. UAVs are required to perform different tasks in the current complex environment, so variable loads are inevitable, and the stability of the UAV body is especially important when performing variable loads, and there are many ways to help and verify the attitude of the UAV during flight. In this paper, in order to more intuitively see the self-generated stability of the UAV under variable load conditions, the dynamics model of the UAV will be established first, and the simulation results show that the movement of the UAV has a very good stability. However, in the previous research, it is not possible to visualize the stability and flight state of the UAV when it is flying under variable load, this paper will make the UAV keep its own flight stability under two kinds of loads through the PID design model. At the same time, the function of the UAV's own mass change during flight is found, and the design function is used to show the stability curve of the UAV when it flies with its own changing mass. Through the final simulation and calculation, the experiment found that through the PID control, the flight state of the UAV when flying with variable load can be observed more intuitively, and the stability state of the UAV when flying can also be observed.

Study of the Critical Safe Height of Goaf in Underground Metal Mines

The empty-space subsequent filling mining method is the main mining scheme for underground metal mines to achieve large-scale mechanized mining. The stage height, one of the main parameters of this method, affects the various production process aspects of the mine and influences the stability of the goaf. In order to determine the stage height scientifically and rationally in the empty-space subsequent filling mining method, a formula for the stabilized critical safe height of a high goaf in an underground metal mine was derived based on Pu’s arch equilibrium theory, Bieniawski’s pillar strength limit theory, and the Kastner equation and combined with the results of an orthogonal analysis to rank the importance of the main factors in the formula. A copper mine in Jiangxi Province was used as a case study, with the reliability of the formula verified by numerical simulation and industrial testing. The factors in the formula influencing the critical stabilized safe height of the goaf were, in descending order, the compressive strength of the rock body, the width of the two-step mining pillar, the width of the one-step mining room, the mining height, and the depth of mining. Based on the calculation results, the recommended stage heights are 30 m (−378 m middle section) and 25 m (−478 m middle section) in the area of poor rock body stability and 50 m in the area of better rock body stability. The simulation results show that the goaf is significantly affected by the compressive stress under the condition of a certain rock body stability and that the compressive stress increases with increasing goaf height. The minimum recommended values of the sidewall safety coefficients in areas of poor and better rock stability are 1.04 and 1.06, respectively. The volume deviation coefficients of the three industrial test mines were all controlled within 3%, indicating that no obvious collapse and destabilization phenomenon occurred in the goaf. This paper provides some theoretical and applied guidance for the stage height design of similar underground metal mines using the empty-space subsequent filling mining method.

Effects of Positive and Negative Self-Talk on Balance and Postural Sway in College Students

Self-talk pertains to phrases individuals recite aloud or internally to increase motivation and focus and is a frequently used psychological skill that promotes enhanced sport performance. Several studies have examined how different these forms of self-talk can affect the execution of specific tasks in sport, but few have examined if self-talk can improve performance in basic activities of daily living, such as balance. The purpose of this study was to examine the effects of two different self-talk strategies on static balance and body stability during a single-leg balance task. Twenty-nine participants were divided into three groups (control group, positive self-talk group, negative self-talk group) and performed a single-leg balance task on the right and left leg while donning inertial measurement units and standing on a force platform and while reciting a positive, negative, or no self-talk strategy (i.e., control). No significant differences (p > 0.05) were detected in the anterior-posterior center of pressure displacement and velocity, and the anterior-posterior center of mass displacement and velocity of the right and left legs. The findings of this study do not suggest that positive or negative self-talk impacts performance during a single-leg balance task.

AI-based automated detection and stability analysis of traumatic vertebral body fractures on computed tomography

PurposeWe developed and tested a neural network for automated detection and stability analysis of vertebral body fractures on computed tomography (CT). Materials and Methods257 patients who underwent CT were included in this Institutional Review Board (IRB) approved study. 463 fractured and 1883 non-fractured vertebral bodies were included, with 190 fractures unstable. Two readers identified vertebral body fractures and assessed their stability. A combination of a Hierarchical Convolutional Neural Network (hNet) and a fracture Classification Network (fNet) was used to build a neural network for the automated detection and stability analysis of vertebral body fractures on CT. Two final test settings were chosen: one with vertebral body levels C1/2 included and one where they were excluded. ResultsThe mean age of the patients was 68 ± 14 years. 140 patients were female. The network showed a slightly higher diagnostic performance when excluding C1/2. Accordingly, the network was able to distinguish fractured and non-fractured vertebral bodies with a sensitivity of 75.8 % and a specificity of 80.3 %. Additionally, the network determined the stability of the vertebral bodies with a sensitivity of 88.4 % and a specificity of 80.3 %. The AUC was 87 % and 91 % for fracture detection and stability analysis, respectively. The sensitivity of our network in indicating the presence of at least one fracture / one unstable fracture within the whole spine achieved values of 78.7 % and 97.2 %, respectively, when excluding C1/2. ConclusionThe developed neural network can automatically detect vertebral body fractures and evaluate their stability concurrently with a high diagnostic performance.

Conventional weight loss therapy in morbid obesity during COVID-19 pandemic: degree of burdens at baseline and treatment efficacy.

COVID-19 affected global physical and psychological health. The purpose of this study was to explore the pandemics impact on health-related quality of life (HRQoL), mental health (anxiety, depression, and perceived stress) and eating behavior in people with severe obesity participating in a multimodal conservative behavioral weight loss (BWL) program conducted via videoconferencing. Additionally, the efficacy of the six-month BWL program in a virtual video-based setting during the pandemic was examined. 297 participants of a face-to-face multimodal behavioral weight loss program prior to the pandemic (PrePAN, May 2014-September 2019) and 146 participants of the in terms of content same intervention in a videoconference-based setting during the pandemic (PAN, July 2020-April 2022) were questioned and compared using standardized questionnaires for HRQoL, symptoms of depressive and anxiety disorders, perceived stress, and eating behavior at baseline and at the end of treatment. Symptoms for anxiety, depression and perceived stress were similar between PrePAN and PAN at baseline. In addition, PAN tended to show lower disinhibition of eating behavior and feelings of hunger than PrePAN. During the pandemic, the BWL intervention resulted in body weight loss (67%) or stabilization (16%) in most of the participants. It also contributed by improving physical HRQoL, lower worries, and improved eating behaviors compared to baseline. During the COVID-19 pandemic, baseline mental health of people with morbid obesity was not worse than before the pandemic. Additionally, the BWL intervention in the virtual video-based setting stabilized and improved physical and mental health during the COVID-19 pandemic.

Ancestral photoreceptor diversity as the basis of visual behaviour.

Animal colour vision is based on comparing signals from different photoreceptors. It is generally assumed that processing different spectral types of photoreceptor mainly serves colour vision. Here I propose instead that photoreceptors are parallel feature channels that differentially support visual-motor programmes like motion vision behaviours, prey capture and predator evasion. Colour vision may have emerged as a secondary benefit of these circuits, which originally helped aquatic vertebrates to visually navigate and segment their underwater world. Specifically, I suggest that ancestral vertebrate vision was built around three main systems, including a high-resolution general purpose greyscale system based on ancestral red cones and rods to mediate visual body stabilization and navigation, a high-sensitivity specialized foreground system based on ancestral ultraviolet cones to mediate threat detection and prey capture, and a net-suppressive system based on ancestral green and blue cones for regulating red/rod and ultraviolet circuits. This ancestral strategy probably still underpins vision today, and different vertebrate lineages have since adapted their original photoreceptor circuits to suit their diverse visual ecologies.

Seepage stability analysis of geogrid reinforced tailings dam

To investigate the influence of a geogrid-reinforced tailings dam on the seepage stability of the dam body, this paper was based on the field test of a reinforced tailings accumulation dam. The study utilized the finite element strength reduction method to simulate the stability of the main dam of the Fengshuigou tailings reservoir under different seepage conditions using ABAQUS software. Additionally, the paper discussed the impact of conventional heightening, dry beach length, and geogrid reinforcement on the position and safety factor of the saturation line of the dam body. The results showed that when the dam body was raised, the saturation line rose by 2.8–5.3 m, resulting in a decrease in the safety factor. The geogrid effectively reduced the height of the saturation line in the tailings dam. In comparison to the unreinforced condition (dam heightening), the saturation line of the tailings dam decreased by 0.9–2.8 m under the local reinforcement condition and by 3.2–12.5 m under the overall reinforcement condition. The geogrid significantly improved the stability of the tailings dam. Furthermore, under the local reinforcement condition, the safety factor of the dam increased by 3.8–5.5%, and under the overall reinforcement condition, it increased by 35.9–42.9%, when compared to the unreinforced condition. Increasing the dry beach length improved the stability of the tailings dam, and under normal working conditions, the safety of the tailings dam was much higher than under the minimum dry beach condition. These results served as a reference for the design of the dam and the new tailings reservoir, laying a foundation for the sustainable development and environmental protection of the tailings pond.

Application of Fuzzy Logic for Robotic Arm Joint Control of an Explosive Ordnance Disposal Unit

Precise luffing of payload in mobile cranes is a crucial part of material handling and safety in industrial operations. Explosive ordnance disposal uses a bomb disposal robot to safely disable explosive devices at a safe distance. This robot is a mobile jib crane type with a gripper as an end effector instead of the typical suspension cable with a hook. The common challenge of this crane type is the arm/jib movement sensitivity with respect to tip-over stability of the crane body. This is directly influenced by the payload and constrained by the degree of freedom. This paper presents a control strategy of the joint for luffing such that the back wheels remain in contact with the surface ground and avoid bucking at any given instance of weight change in the payload. Fuzzy logic was applied to control the motor torque and luffing angle of the arm in response to the load and gripper opening size to maintain the tip-over stability margin at the highest value possible. The response curves at different configurations of the two input signals were also analyzed based on the rules set to determine its precision with respect to the expected response curve.

Gait smoothness during high-demand motor walking tasks in older adults with mild cognitive impairment.

Early signs of Mild Cognitive Impairment (MCI)-related gait deficits may be detected through the performance of complex walking tasks that require high gait control. Gait smoothness is a robust metric of overall body stability during walking. This study aimed to explore gait smoothness during complex walking tasks in older adults with and without MCI. Participants were 18 older adults with MCI (mean age = 67.89 ± 4.64 years) and 18 cognitively intact controls (mean age = 67.72 ± 4.63 years). Gait assessment was conducted under four complex walking tasks: walking a narrow path, walking around an obstacle, horizontal head turns while walking, and vertical head turns while walking. The index of harmonicity (IH), representing gait smoothness associated with overall body stability, was measured in anteroposterior, mediolateral, and vertical directions. A multivariate analysis was employed to compare the differences in IH between groups for each complex walking task. The MCI group demonstrated a reduction of IH in the mediolateral direction during the horizontal head turns than the control group (MCI group = 0.64 ± 0.16, Control group = 0.74 ± 0.12, p = 0.04). No significant differences between groups were found for the IH in other directions or walking conditions. These preliminary findings indicate that older adults with MCI have a decline in step regularity in the mediolateral direction during walking with horizontal head turns. Assessment of the smoothness of walking during head turns may be a useful approach to identifying subtle gait alterations in older adults with MCI, which may facilitate timely gait intervention.

Motor protein Kif6 regulates cilia motility and polarity in brain ependymal cells.

Motile cilia on ependymal cells that line brain ventricular walls beat in concert to generate a flow of laminar cerebrospinal fluid (CSF). Dyneins and kinesins are ATPase microtubule motor proteins that promote the rhythmic beating of cilia axonemes. Despite common consensus about the importance of axonemal dynein motor proteins, little is known about how kinesin motors contribute to cilia motility. Here, we show that Kif6 is a slow processive motor (12.2±2.0 nm/s) on microtubules in vitro and localizes to both the apical cytoplasm and the axoneme in ependymal cells, although it does not display processive movement in vivo. Using a mouse mutant that models a human Kif6 mutation in a proband displaying macrocephaly, hypotonia and seizures, we found that loss of Kif6 function causes decreased ependymal cilia motility and, subsequently, decreases fluid flow on the surface of brain ventricular walls. Disruption of Kif6 also disrupts orientation of cilia, formation of robust apical actin networks and stabilization of basal bodies at the apical surface. This suggests a role for the Kif6 motor protein in the maintenance of ciliary homeostasis within ependymal cells.

The effect of complex cognitive context on the dynamic stability during gait initiation in older women.

Changes in cognitive control are considered potential factors affecting voluntary motor movements during gait initiation (GI). Simulating environments with higher cognitive resource demands have an effect on the stability of GI task performance, which is of significant importance for assessing fall risk in the older adults and devising fall risk management measures in multiple environments. This study aims to reveal the influence of complex cognitive competitive environment with increased cognitive demands on the dynamic stability during GI in the older women. Twenty-three older females and twenty-three younger females performed walking tests under three conditions: voluntary initiation (SI), visual light reaction time task (LRT), and cognitive interference + visual light reaction time task (C + LRT). Eight cameras (Qualisys, Sweden, model: Oqus 600) and three force plates (Kistler, Switzerland, model: 9287C) are used to obtain kinematic and kinetic data. To recorde the trajectory of center of pressure (CoP) and the position of the foot placement, and compute the anterior-posterior (A-P) and medio-lateral (M-L) dynamic stability at the onset and end moments of the single-leg support by means of center of mass (CoM) and gait spatiotemporal parameters. Older women responded to the effect of complex environments involving cognitive competition on body stability by prolonging the lateral displacement time of the CoP during the anticipatory postural adjustments (APAs) phase, reducing step length and velocity, and increasing step width and foot inclination angle. Complex initiation environments lead to competition for cognitive resources in the brain, resulting in decreased stability of GI motor control in older adults. The higher the complexity of the cognitive resource demands environment, the lower the stability of GI in older adults, and the greater the effect on their M-L stability at the onset of stepping.

Analysis of the effectiveness of landslide stabilization in a near-dam reservoir area

The geological conditions of the landslide area in a near-dam reservoir area of a water conservancy hub project are complicated, and the stability problem of the landslide body is prominent, which is not only directly related to the safety of the adjacent office building and highway, but also poses a threat to the normal operation of the water conservancy hub. According to the latest geological data of the landslide area, the results of the stability calculation of the landslide body are analyzed, and the reinforcement design scheme of circular chair type anti-slide piles & prestressed anchor cables is proposed for the landslide body to solve the problem of anti-slide stability of the landslide body. Numerical analysis results show that: the safety factor under each working condition after reinforcement is within the permissible range and meets the relevant normative requirements, the landslide body has good control effect on deformation after reinforcement, and the reinforcement measures can provide certain reference value for the design and construction of similar projects.

O exercício de agachamento recruta músculos do tronco tanto quanto exercícios localizados

Abstract Introduction In the context of resistance training, which encompasses both strengthening and rehabilitation, the incorporation of global range exercises demands intense activation of the trunk muscle groups, which play a primary role in body stabilization. The squat, notorious for its complexity and effectiveness in activating stabilizers during execution, raises a central question: whether this exercise recruits the muscles more significantly compared to localized exercises, such as push-ups and trunk exten-sions. Objective To identify the degree of activation of the trunk muscles during squats and compare it with localized exercises for the trunk muscles: lumbar and abdominal. Methods Using surface electromyography, the activation of the iliocostalis, multifidus, internal oblique, external oblique and rectus abdominis muscles was evaluated. The sample included 16 physically active volunteers of both sexes. A repeated measures t-test (α < 0.05) was used as an analysis method. Results The iliocostalis, multifidus and internal oblique muscles showed similar levels of activation both in the squat and in their respective isolated exercises, while the rectus abdominis and external oblique muscles showed greater activity during trunk flexion. Conclusion It is possible to infer that squats are an effective exercise for training the iliocostalis, multifidus and internal oblique muscles, while localized exercises are more suitable for strengthening the external oblique and rectus abdominis muscles. Such conclusion can contribute to optimizing the planning of exercise sessions by replacing isolated trunk exercises with squats.

Effects of Pretreatment on Stability of Peanut Oil Bodies and Functional Characteristics of Proteins Extracted by Aqueous Enzymatic Method.

Effects of dry and wet grind on peanut oil and protein yield, oil bodies (OBs) stability, fatty acid composition, protein composition and functional characteristics were systematically analyzed. Results showed that peanut oil and protein yields reached highest at dry grind 90 s (92.56% and 83.05%, respectively), while peanut oil and protein yields were 94.58% and 85.36%, respectively, at wet grind 120 s. Peanut oil and protein yields by wet grind was 2.18% and 2.78% higher than that of dry grind, respectively. Surface protein concentration (Г) and absolute value of zeta potential of OBs extracted by wet grind (WOBs) were 11.53 mg/m 2 and 18.51 mV, respectively, which were higher than OBs extracted by dry grind (DOBs), indicating stability of WOBs was higher than DOBs. Relative contents of oleic acid and linoleic acid in peanut oil, essential and hydrophobic amino acids in protein extracted by wet grind were higher than dry grind. There was little difference in protein composition between wet and dry grind, but thermal denaturation degree of protein obtained by wet grind was lower than dry grind. Solubility, oil retention, emulsion stability, foaming and foam stability of protein obtained by wet grind were better than dry grind. Results from this study provided theoretical basis for grind pretreatment selection of aqueous enzymatic method.

Numerical calculation of seepage field and stability analysis of dam body of closed tailings pond

Abstract In this study, taking a certain iron ore tailings pond as the research object, a closed pond engineering design was conducted to ensure its sustained and stable operation. Firstly, installation of a flood drainage system (spillway) and closure of the existing overflow tower and drainage pipe are suggested. Secondly, numerical analysis is conducted on the seepage field of the dam body to determine the position of the saturation line of the dam body under normal water storage level and design flood level. Subsequently, the stability of the dam body under various working conditions is assessed using the limit equilibrium method.

Effect of juggling expertise on pointing performance in peripheral vision.

Juggling is a very complex activity requiring motor, visual and coordination skills. Expert jugglers experience a "third eye" monitoring leftward and rightward ball zenith positions alternately, in the upper visual fields, while maintaining their gaze straight-ahead. This "third eye" reduces their motor noise (improved body stability and decrease in hand movement variability) as it avoids the numerous head and eye movements that add noise into the system and make trajectories more uncertain. Neuroimaging studies have shown that learning to juggle induces white and grey matter hypertrophy at the posterior intraparietal sulcus. Damage to this brain region leads to optic ataxia, a clinical condition characterised by peripheral pointing bias toward gaze position. We predicted that expert jugglers would, conversely, present better accuracy in a peripheral pointing task. The mean pointing accuracy of expert jugglers was better for peripheral pointing within the upper visual field, compatible with their subjective experience of the "third eye". Further analyses showed that experts exhibited much less between-subject variability than beginners, reinforcing the interpretation of a vertically asymmetrical calibration of peripheral space, characteristic of juggling and homogenous in the expert group. On the contrary, individual pointing variability did not differ between groups neither globally nor in any sector of space, showing that the reduced motor noise of experts in juggling did not transfer to pointing. It is concluded that the plasticity of the posterior intraparietal sulcus related to juggling expertise does not consist of globally improved visual-to-motor ability. It rather consists of peripheral space calibration by practicing horizontal covert shifts of the attentional spotlight within the upper visual field, between left and right ball zenith positions.