scholarly journals Binocular vision and the control of foot placement during walking in natural terrain

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kathryn Bonnen ◽  
Jonathan S. Matthis ◽  
Agostino Gibaldi ◽  
Martin S. Banks ◽  
Dennis M. Levi ◽  
...  
Keyword(s):  
Binocular Vision ◽  
Visual Function ◽  
Visual Information ◽  
Developmental Disorders ◽  
Control Process ◽  
Visuomotor Control ◽  
The Body ◽  
Foot Placement ◽  
Sensory Uncertainty ◽  
The Impact

AbstractCoordination between visual and motor processes is critical for the selection of stable footholds when walking in uneven terrains. While recent work (Matthis et al. in Curr Biol 8(28):1224–1233, 2018) demonstrates a tight link between gaze (visual) and gait (motor), it remains unclear which aspects of visual information play a role in this visuomotor control loop, and how the loss of this information affects that relationship. Here we examine the role of binocular information in the visuomotor control of walking over complex terrain. We recorded eye and body movements while normally-sighted participants walked over terrains of varying difficulty, with intact vision or with vision in one eye blurred to disrupt binocular vision. Gaze strategy was highly sensitive to the complexity of the terrain, with more fixations dedicated to foothold selection as the terrain became more difficult. The primary effect of increased sensory uncertainty due to disrupted binocular vision was a small bias in gaze towards closer footholds, indicating greater pressure on the visuomotor control process. Participants with binocular vision losses due to developmental disorders (i.e., amblyopia, strabismus), who have had the opportunity to develop alternative strategies, also biased their gaze towards closer footholds. Across all participants, we observed a relationship between an individual’s typical level of binocular visual function and the degree to which gaze is shifted toward the body. Thus the gaze–gait relationship is sensitive to the level of sensory uncertainty, and deficits in binocular visual function (whether transient or long-standing) have systematic effects on gaze strategy in complex terrains. We conclude that binocular vision provides useful information for locating footholds during locomotion. Furthermore, we have demonstrated that combined eye/body tracking in natural environments can be used to provide a more detailed understanding of the impact of a type of vision loss on the visuomotor control process of walking, a vital everyday task.

scholarly journals The critical phase for visual control of human walking over complex terrain

2017 ◽  
Vol 114 (32) ◽  
pp. E6720-E6729 ◽  
Author(s):  
Jonathan Samir Matthis ◽  
Sean L. Barton ◽  
Brett R. Fajen
Keyword(s):  
Complex Terrain ◽  
Visual Information ◽  
Center Of Mass ◽  
Ground Surface ◽  
The Body ◽  
Foot Placement ◽  
Preceding Step ◽  
Control Work ◽  
Base Of Support ◽  
Target Visibility

To walk efficiently over complex terrain, humans must use vision to tailor their gait to the upcoming ground surface without interfering with the exploitation of passive mechanical forces. We propose that walkers use visual information to initialize the mechanical state of the body before the beginning of each step so the resulting ballistic trajectory of the walker’s center-of-mass will facilitate stepping on target footholds. Using a precision stepping task and synchronizing target visibility to the gait cycle, we empirically validated two predictions derived from this strategy: (1) Walkers must have information about upcoming footholds during the second half of the preceding step, and (2) foot placement is guided by information about the position of the target foothold relative to the preceding base of support. We conclude that active and passive modes of control work synergistically to allow walkers to negotiate complex terrain with efficiency, stability, and precision.

scholarly journals The quality of visual information about the lower extremities influences visuomotor coordination during virtual obstacle negotiation

2018 ◽  
Vol 120 (2) ◽  
pp. 839-847 ◽  
Author(s):  
Aram Kim ◽  
Kari S. Kretch ◽  
Zixuan Zhou ◽  
James M. Finley
Keyword(s):  
Visual Information ◽  
Pitch Angle ◽  
Visual Representation ◽  
Lower Extremities ◽  
Online Control ◽  
The Body ◽  
Visuomotor Coordination ◽  
Foot Placement ◽  
Safety Margins ◽  
Virtual Obstacle

Successful negotiation of obstacles during walking relies on the integration of visual information about the environment with ongoing locomotor commands. When information about the body and the environment is removed through occlusion of the lower visual field, individuals increase downward head pitch angle, reduce foot placement precision, and increase safety margins during crossing. However, whether these effects are mediated by loss of visual information about the lower extremities, the obstacle, or both remains to be seen. Here we used a fully immersive, virtual obstacle negotiation task to investigate how visual information about the lower extremities is integrated with information about the environment to facilitate skillful obstacle negotiation. Participants stepped over virtual obstacles while walking on a treadmill with one of three types of visual feedback about the lower extremities: no feedback, end-point feedback, and a link-segment model. We found that absence of visual information about the lower extremities led to an increase in the variability of leading foot placement after crossing. The presence of a visual representation of the lower extremities promoted greater downward head pitch angle during the approach to and subsequent crossing of an obstacle. In addition, having greater downward head pitch was associated with closer placement of the trailing foot to the obstacle, further placement of the leading foot after the obstacle, and higher trailing foot clearance. These results demonstrate that the fidelity of visual information about the lower extremities influences both feedforward and feedback aspects of visuomotor coordination during obstacle negotiation. NEW & NOTEWORTHY Here we demonstrate that visual information about the lower extremities is utilized for precise foot placement and control of safety margins during obstacle negotiation. We also found that when a visual representation of the lower extremities is present, this information is used in the online control of foot trajectory. Together, our results highlight how visual information about the body and the environment is integrated with motor commands for planning and online control of obstacle negotiation.

scholarly journals When my avatar’s movements make me feel I am moving: From natural-like stimuli to fully artificial ones in virtual reality

2021 ◽  
Vol 130 ◽  
pp. 02001
Author(s):  
Marion Giroux ◽  
Julien Barra ◽  
Christian Graff ◽  
Michel Guerraz
Keyword(s):  
Virtual Reality ◽  
Visual Information ◽  
Visual Cues ◽  
Visual Motion ◽  
Body Representation ◽  
The Body ◽  
Morphological Similarity ◽  
Person Perspective ◽  
Visual Motion Cues ◽  
The Impact

In virtual reality, users do not receive any visual information coming from their own body. Thus, avatars are often used, and they can be embodied which alters the body representation. We suggested that the perception of one’s own movements (i.e., kinaesthesia) can be altered as well. We investigated whether visual cues coming from an avatar can be used for kinaesthesia and to what extent such cues can deviate from natural ones. We used a paradigm in which the participant’s left forearm was moved passively, correlated with the movement of both forearms of the avatar. Such visuo-proprioceptive combination induces kinaesthetic illusions in the participant’s right forearm. The impact of the morphological similarity (semantic congruency) and of the visual perspective of the avatar (spatial congruency) was investigated. Results have indicated that avatar’s movements are processed as one’s own movements. Morphological similarity and first-person perspective were not necessary, but they reinforced the illusions. Thus, visual motion cues can strongly deviate from natural ones in morphology and perspective and still contribute to kinaesthesia.

The Impact of Shariah Governance and Corporate Governance on the Risk Management Practices: Evidence from Local and Foreign Islamic Banks in Malaysia

2018 ◽  
Vol 15 (2) ◽  
pp. 1-20
Author(s):  
Sabri Embi ◽  
Zurina Shafii
Keyword(s):  
Risk Management ◽  
Corporate Governance ◽  
Management Practices ◽  
Principal Component ◽  
T Test ◽  
The Body ◽  
Primary Data ◽  
Islamic Banks ◽  
Shariah Governance ◽  
The Impact

The purpose of this study is to examine the impact of Shariah governance and corporate governance (CG) on the risk management practices (RMPs) of local Islamic banks and foreign Islamic banks operating in Malaysia. The Shariah governance comprises the Shariah review (SR) and Shariah audit (SA) variables. The study also evaluates the level of RMPs, CG, SR, and SA between these two type of banks. With the aid of SPSS version 20, the items for RMPs, CG, SR, and SA were subjected to principal component analysis (PCA). From the PCA, one component or factor was extracted each for the CG, SR, and RMPs while another two factors were extracted for the SA. Primary data was collected using a self-administered survey questionnaire. The questionnaire covers four aspects ; CG, SR, SA, and RMPs. The data received from the 300 usable questionnaires were subjected to correlation and regression analyses as well as an independent t-test. The result of correlation analysis shows that all the four variables have large positive correlations with each other indicating a strong and significant relationship between them. From the regression analysis undertaken, CG, SR, and SA together explained 52.3 percent of the RMPs and CG emerged as the most influential variable that impacts the RMPs. The independent t-test carried out shows that there were significant differences in the CG and SA between the local and foreign Islamic banks. However, there were no significant differences between the two types of the bank in relation to SR and RMPs. The study has contributed to the body of knowledge and is beneficial to academicians, industry players, regulators, and other stakeholders.

Influence of DAFS-25+polizon composition on blood and functional state of liver of steers at fattening

2020 ◽  
pp. 15-18
Author(s):  
Inna R. Kilmetova ◽  
◽  
Igor A. Rodin ◽  
Nazira I. Khayrullina ◽  
Nikolay G. Fenchenko ◽  
...  
Keyword(s):  
Functional State ◽  
White Blood Cells ◽  
Live Weight ◽  
The Body ◽  
Farm Animals ◽  
Control Group ◽  
Standard Diet ◽  
The Impact ◽  
Experimental Group ◽  
Stimulation Of

Summary. The disbalanced feeding and the uneven distribution of micro- and macroelements in the environment leads to a trace element, in particular hypomelanosis. To accelerate the growth and preservation of young farm animals include in the diet of various biological additives and drugs, which include selenium. For stimulation of weight gain in the livestock industry, as well as for the prevention and treatment of pathological processes in addition to micro - and macrouse amino acids, primarily methionine. The aim of this work was to study the influence of composition of DAFS-25+Polizon on morpho-biochemical parameters of blood and functional state of the liver in fattening bulls of black-motley breed in the conditions of the Republic of Bashkortostan. Experiments using were conducted on bull-calves of black-motley breed of the properties in the properties age from 6 to 15 months. The first experimental group during the experiment was additionally given the composition of DAFS-25+Polizon at a dose of 2 mg/kg, the animals of the control group received a standard diet. To assess the impact of the composition DAFS-25+Polizon on metabolism cattle studied morphological and biochemical indicators of blood and conducted histological examination of the liver. It is established that the use of the composition of DAFS-25+Polizon at a dose of 2 mg/kg increases the number of erythrocytes and hemoglobin in the experimental group and reduces the amount of white blood cells. The serum content of total protein, phosphorus and calcium increases in the group of experimental animals. Microscopic examination of the liver revealed no changes in the structure of the organ and hepatocytes in the experimental group, whereas in the control group hemodynamic disorders and dystrophic changes in liver cells were observed. Thus, the use of the composition DAFS-25+Polizon at a dose of 2 mg/kg of live weight in fattening bulls black-and-white breed contributes to the increase of redox processes in the body, stimulation of metabolism, prevent the development of liver disorders of cellular mechanisms of metabolism, optimizes the structure of the liver, which generally provides higher productivity.

Comparative assessment of morphological mechanisms of maintaining structural liver homeostasis in the dynamics of exposure to coal-rock dust and sodium fluoride on the body

2020 ◽  
pp. 189-194
Author(s):  
M. S. Bugaeva ◽  
O. I. Bondarev ◽  
N. N. Mikhailova ◽  
L. G. Gorokhova
Keyword(s):  
Sodium Fluoride ◽  
Morphological Changes ◽  
The Body ◽  
System Level ◽  
Production Factor ◽  
Coal Rock ◽  
The Impact ◽  
Structural Homeostasis ◽  
Rock Dust

Introduction. The impact on the body of such factors of the production environment as coal-rock dust and fluorine compounds leads to certain shift s in strict indicators of homeostasis at the system level. Maintaining the relative constancy of the internal environment of the body is provided by the functional consistency of all organs and systems, the leading of which is the liver. Organ repair plays a crucial role in restoring the structure of genetic material and maintaining normal cell viability. When this mechanism is damaged, the compensatory capabilities of the organ are disrupted, homeostasis is disrupted at the cellular and organizational levels, and the development of the main pathological processes is noted.The aim of the study is to compare the morphological mechanisms of maintaining structural homeostasis of the liver in the dynamics of the impact on the body of coal-rock dust and sodium fluoride.Materials and methods. Experimental studies were conducted on adult white male laboratory rats. Features of morphological mechanisms for maintaining structural homeostasis of the liver in the dynamics of exposure to coal-rock dust and sodium fluoride were studied on experimental models of pneumoconiosis and fluoride intoxication. For histological examination in experimental animals, liver sampling was performed after 1, 3, 6, 9, 12 weeks of the experiment.Results. The specificity of morphological changes in the liver depending on the harmful production factor was revealed. It is shown that chronic exposure to coal-rock dust and sodium fluoride is characterized by the development of similar morphological changes in the liver and its vessels from the predominance of the initial compensatory-adaptive to pronounced violations of the stromal and parenchymal components. Long-term inhalation of coal-rock dust at 1–3 weeks of seeding triggers adaptive mechanisms in the liver in the form of increased functional activity of cells, formation of double-core hepatocytes, activation of immunocompetent cells and endotheliocytes, ensuring the preservation of the parenchyma and the general morphostructure of the organ until the 12th week of the experiment. Exposure to sodium fluoride leads to early disruption of liver compensatory mechanisms and the development of dystrophic changes in the parenchyma with the formation of necrosis foci as early as the 6th week of the experiment.Conclusions. The study of mechanisms for compensating the liver structure in conditions of long-term exposure to coal-rock dust and sodium fluoride, as well as processes that indicate their failure, and the timing of their occurrence, is of theoretical and practical importance for developing recommendations for the timely prevention and correction of pathological conditions developing in employees of the aluminum and coal industry.The authors declare no conflict of interests.

Experience in the use of double broncholytic therapy in occupational practice

2019 ◽  
pp. 303-307
Author(s):  
Elena A. Beigel ◽  
Natalya G. Kuptsova ◽  
Elena V. Katamanova ◽  
Oksana V. Ushakova ◽  
Oleg L. Lakhman
Keyword(s):  
Quality Of Life ◽  
Personal Data ◽  
The Body ◽  
Step Test ◽  
Aluminum Production ◽  
Chronic Obstructive ◽  
Body Plethysmography ◽  
Occupational Copd ◽  
The Impact

Introduction. Occupational chronic obstructive pulmonary disease (COPD) is one of the leading nosological forms of occupational respiratory disease. Numerous studies have shown high effectiveness of the combination of indacaterol/glycopyrronium (Ultibro®breezhaler®) on the impact on clinical and functional indicators in the treatment of COPD in General practice.The aim of the investigation the case of occupational COPD with the analysis of the dynamics of functional indicators, tolerance to physical load and evaluation of the quality of life of workers engaged in aluminum production by using combination of indacaterol/glycopyrronium.Materials and methods. The random sampling method included 20 men, workers of aluminum production, with the established diagnosis of professional COPD at the age of 40 to 60 years. The survey was conducted (Borg scale, medical Research Council scale (mMRC) and COPD Assessment Test (CAT). Functional methods of studies were conducted: spirometry, body plethysmography, electrocardiography (ECG) and the six-minute stepper test (6-MST).Results. Against the background of 8 weeks of therapy, the volume of forced exhalation for 1 minute (FEV1) increased by 14.7% and amounted to 67.90% of the due values, the forced vital capacity of the lungs (FVC) increased by 11.3% and amounted to 76.95% of the due. According to the body plethysmography (BPG) is set to decrease in residual lung volume on average by 13.4% and static hyperinflation, confirmed by the decrease in functional residual volume (FRV) of 18.8%. During the study period increased physical activity of patients. The average difference between the distance traveled in the six-minute step test before and after treatment was 58.8 m. The analysis of personal data showed that the quality of life of patients improved, the total score in the questionnaire CAT at the beginning of the study was 16.9 points, and after 8 weeks decreased by 63% and amounted to 10.7 points.Conclusions: The Results indicate a positive effect of combination therapy with indacaterol/glycopyrronium on the course and progression of occupational COPD.

Studying Abroad in Nepal: Assessing Impact

2003 ◽  
Vol 9 (1) ◽  
pp. 175-188 ◽  
Author(s):  
Patricia Farrell ◽  
Murari Suvedi
Keyword(s):  
Personal Development ◽  
Intellectual Development ◽  
Longitudinal Research ◽  
Adult Learning Theory ◽  
Academic Program ◽  
The Body ◽  
Study Abroad Programs ◽  
Studying Abroad ◽  
Perceived Impact ◽  
The Impact

The purpose of this study is to analyze the reported or perceived impact of studying in Nepal on student’s academic program, personal development and intellectual development. The study draws upon adult learning theory to analyze survey instrument data, interviews, and case studies to discern the impact of the program on college students and to contribute to the body of longitudinal research on U.S. study abroad programs.

Adrenergic and Cholinergic Uterine Innervation and the Impact on Reproduction in Aged Women

2020 ◽  
Vol 26 (3) ◽  
pp. 358-362 ◽  
Author(s):  
Ioannis P. Kosmas ◽  
Antonio Malvasi ◽  
Daniele Vergara ◽  
Ospan A. Mynbaev ◽  
Radmila Sparic ◽  
...  
Keyword(s):  
Negative Impact ◽  
Smooth Muscles ◽  
Nerve Fibers ◽  
The Body ◽  
Autonomous Nervous System ◽  
Childbearing Age ◽  
Assisted Reproductive Technique ◽  
Aged Patients ◽  
Post Menopause ◽  
The Impact

: In recent years, the development of Assisted Reproductive Technique, the egg and embryo donation changed substantially the role of the uterus in recent years. It provided a higher chance for a pregnancy even in women over 45 years or post-menopause. In fact, the number of aged patients and in peri/post-menopause in pregnancy is nowadays increasing, but it increases obstetrical and neonatal related problems. The human uterus is richly innervated and modified especially during pregnancy and labor, and it is endowed with different sensory, parasympathetic, sympathetic and peptidergic neurofibers. They are differently distributed in uterine fundus, body and cervix, and they are mainly observed in the stroma and around arterial vessel walls in the myometrial and endometrial layers. Many neurotransmitters playing important roles in reproductive physiology are released after stimulation by adrenergic or cholinergic nerve fibers (the so called sympathetic/parasympathetic co-transmission). Immunohistochemical study demonstrated the localization and quantitative distribution of neurofibers in the fundus, the body and cervix of young women of childbearing age. : Adrenergic and cholinergic effects of the autonomous nervous system are the most implicated in the uterine functionality. In such aged women, the Adrenergic and AChE neurofibers distribution in the fundus, body and cervix is progressively reduced by increasing age. Adrenergic and AChE neurotransmitters were closely associated with the uterine arteries and myometrial smooth muscles, and they reduced markedly by ageing. The Adrenergic and AChE neurofibers decreasing has a dramatical and negative impact on uterine physiology, as the reduction of pregnancy chance and uterine growth, and the increase of abortion risk and prematurity.

scholarly journals Dynamic Modeling and Simulation of a Body Weight Support System

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Zhendong Song ◽  
Wei Chen ◽  
Wenbing Wang ◽  
Guoqing Zhang
Keyword(s):  
Body Weight ◽  
Control Process ◽  
Vertical Motion ◽  
The Body ◽  
Body Weight Support ◽  
Gait Rehabilitation ◽  
Series Elastic Actuator ◽  
Weight Support ◽  
Support Force ◽  
Body Weight Support System

This paper proposes a body weight support (BWS) system with a series elastic actuator (SEA) to facilitate walking assistance and motor relearning during gait rehabilitation. This system comprises the following: a mobile platform that ensures movement of the system on the ground, a BWS mechanism with an SEA that is capable of providing the desired unloading force, and a pelvic brace to smooth the pelvis motions. The control of the body weight support is realized by an active weight-offload method, and a dynamic model of the BWS system with offload mass of a human is conducted to simulate the control process and optimize the parameters. Preliminary results demonstrate that the BWS system can provide the desired support force and vertical motion of the pelvis.

Sign in / Sign up

Export Citation Format

Share Document