19 resultados para POSTURES

em Deakin Research Online - Australia


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The central proposition of motivational posturing theory is that regulatees place social distance between themselves and authority, communicating the nature of that distance through a narrative that protects the self from negative appraisal by the authority. One of the key components of posturing is the coping sensibility that individuals adopt to manage the threat of authority. At a baseline level, authorities make demands on citizens and as such threaten individual freedom. At the highest level, authorities threaten through punishment for non-compliance. Data collected from 3,253 randomly selected Australian taxpayers and a special group of 2,292 taxpayers in conflict with the tax authority are used to show that in both groups, three coping sensibilities contribute to posturing ("thinking morally,""feeling oppressed," and "taking control"), and that all three sensibilities are significantly heightened in the group experiencing conflict with the authority. The article argues that the most effective regulatory outcome is achieved when the regulatory process can dampen the "taking control" and "feeling oppressed" sensibilities, and strengthen the "thinking morally" sensibility. Responsive regulation is an approach that encourages tax authorities to read motivational postures, understand the sensibilities that shape them, and tailor a regulatory intervention accordingly.

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Introduction: Neck injuries are common in high performance combat pilots and have been attributed to high gravitational forces and the non-neutral head postures adopted during aerial combat maneuvers. There is still little known about the pathomechanics of these injuries.

Methods: Six Royal Australian Air Force Hawk pilots flew a sortie that included combinations of three +Gz levels (1, 3, and 5) and four head postures (Neutral, Turn, Extension, and Check-6). Surface electromyography from neck and shoulder muscles was recorded in flight. Three-dimensional measures of head postures adopted in flight were estimated postflight with respect to end-range of the cervical spine using an electromagnetic tracking device.

Results: Mean muscle activation increased significantly with both increasing +Gz and non-neutral head postures. Check-6 at +5 Gz (mean activation of all muscles = 51% MVIC) elicited significantly greater muscle activation in most muscles when compared with Neutral, Extension, and Turn head postures. High levels of muscle co-contraction were evident in high acceleration and non-neutral head postures. Head kinematics showed Check-6 was closest to end-range in any movement plane (86% ROM in rotation) and produced the greatest magnitude of rotation in other planes. Turn and Extension showed a large magnitude of rotation with reference to end-range in the primary plane of motion but displayed smaller rotations in other planes.

Discussion:
High levels of neck muscle activation and co-contraction due to high +Gz and head postures close to end range were evident in this study, suggesting the major influence of these factors on the pathomechanics of neck injuries in high performance combat pilots.

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This study examined the trunk postures and upper-body muscle activations during four physically demanding wildfire suppression tasks. Bilateral, wireless surface electromyography was recorded from the trapezius and erector spinae muscles of nine experienced, wildfire fighters. Synchronised video captured two retroreflective markers to allow for quantification of two-dimensional sagittal trunk flexion. In all tasks, significantly longer time was spent in the mild and severe trunk flexion (p ≤ 0.002) compared to the time spent in a neutral posture. Mean and peak muscle activation in all tasks exceeded previously established safe limits. These activation levels also significantly increased through the performance of each task (p < 0.001). The results suggest that the wildfire suppression tasks analysed impose significant musculoskeletal demand on firefighters. Fire agencies should consider developing interventions to reduce the exposure of their personnel to these potentially injurious musculoskeletal demands.

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 The research investigated the efficacy of instructional methods on lower limb landing postures. The findings provided insight into the role of instructional methods that manipulate the focus of attention and the retention of motor learning, in the context of an ACL injury prevention program in an applied community based setting.

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BACKGROUND: There have been some disagreements on the comparison of disc pressures in the standing and sitting postures in literature. Most research on in vivo pressure needle measurement found higher disc pressure in sitting than in standing. The disc pressure data can help to advocate better postures for clinical advice. OBJECTIVE: The aim of this paper is to develop a procedure to study the compressive load on intervertebral joint in the standing and sitting postures through the approach of motion capture and musculoskeletal modeling. METHODS: The marker data of six subjects performing various standing and sitting postures was obtained during the motion capture experiment and used to train the musculoskeletal model with an enhanced discretized spine developed for subject in the inverse and forward simulations. RESULTS: Compressive loads on L3-L4 and L4-L5 joints are found higher in upright sitting than in upright standing. Slumped sitting, cross-legged sitting and flexion sitting can introduce higher compressive loads on intervertebral joints compared with upright sitting. CONCLUSIONS: These findings indicate the effects of standing and sitting postures on the spinal joint loads. The results can provide doctors and therapists with more information on clinical advice on better postures for people with spinal problems.

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Following its time-honoured 'great and powerful friends' foreign policy tradition, Australia has been cultivating close ties simultaneously with the United States and China. Yet, as a rivalry between the two powers apparently looms large, Australia faces an acute dilemma. While the rise of China and the question of Taiwan are often cited as main causes of US-China discord, this article argues that the American neoconservative policy on China, underpinned by a belief in both military strength and moral clarity, is integral to this growing competition and is, by extension, partly responsible for the emergence of Australia's predicament. To avoid such a difficult choice, the article suggests that Australia should strive to curb the policy influence of neoconservatism both in the United States and at home by pursuing a more independent foreign policy, making clear its strategic postures on US-China relations, and helping establish a trilateral strategic forum between Australia, the United States, and China.

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Computer display height and desk design to allow forearm support are two critical design features of workstations for information technology tasks. However there is currently no 3D description of head and neck posture with different computer display heights and no direct comparison to paper based information technology tasks. There is also inconsistent evidence on the effect of forearm support on posture and no evidence on whether these features interact. This study compared the 3D head, neck and upper limb postures of 18 male and 18 female young adults whilst working with different display and desk design conditions. There was no substantial interaction between display height and desk design. Lower display heights increased head and neck flexion with more spinal asymmetry when working with paper. The curved desk, designed to provide forearm support, increased scapula elevation/protraction and shoulder flexion/abduction.

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Procedural justice generally enhances an authority's legitimacy and encourages people to comply with an authority's decisions and rules. We argue, however, that previous research on procedural justice and legitimacy has examined legitimacy in a limited way by focusing solely on the perceived legitimacy of authorities and ignoring how people may perceive the legitimacy of the laws and rules they enforce. In addition, no research to date has examined how such perceptions of legitimacy may moderate the effect of procedural justice on compliance behavior. Using survey data collected across three different regulatory contexts – taxation (Study 1), social security (Study 2), and law enforcement (Study 3) – the findings suggest that one's perceptions of the legitimacy of the law moderates the effect of procedural justice on compliance behaviors; procedural justice is more important for shaping compliance behaviors when people question the legitimacy of the laws than when they accept them as legitimate. An explanation of these findings using a social distancing framework is offered, along with a discussion of the implications the findings have on enforcement.

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Objective
This study examines the influence of posture on the range of axial rotation of the thorax and the range and direction of the coupled lateral flexion.

Methods

The ranges of mid thoracic axial rotation and coupled lateral flexion were measured in 52 asymptomatic subjects (aged 18-43 years) using an optical motion analysis system. To examine the influence of posture on primary and coupled motion, we initiated axial rotation from a neutral sitting posture and from end-range thoracic flexion and extension.

Results
There was a significant decrease in the range of thoracic rotation in flexion compared with the neutral and extended postures (P < .001). The mean range of coupled lateral flexion was 8.9% of the axial rotation range in the neutral posture and increased to 14.3% and 23.2% in the extended and flexed postures, respectively. Patterns of coupled motion varied between subjects, but an ipsilateral pattern was more common in the flexed posture, whereas a contralateral pattern was more common in the neutral and extended postures.

Conclusions

The ranges and patterns of coupled motion of the thorax appear to be strongly influenced by the posture from which the movement is initiated. This has important implications in relation to the interpretation of clinical tests of thoracic motion and in consideration of mechanisms of development of thoracic pain disorders.

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This study compared the rate of fatigue and lower limb EMG activities during high-intensity constantload cycling in upright and supine postures. Eleven active males performed seven cycling exercise tests: one upright graded test, four fatigue tests (two upright, two supine) and two EMG tests (one upright, one supine). During the fatigue tests participants initially performed a 10 s all-out effort followed by a constant-load test with 10 s all-out bouts interspersed every minute. The load for the initial two fatigue tests was 80% of the peak power (PP) achieved during the graded test and these continued until failure. The remaining two fatigue tests were performed at 20% PP and were limited to the times achieved during the 80% PP tests. During the EMG tests subjects performed a 10 s all-out effort followed by a constant-load test to failure at 80% PP. Normalised EMG activities (% maximum, NEMG) were assessed in five lower limb muscles. Maximum power and maximum EMG activity prior to each fatigue and EMG test were unaffected by posture. The rate of fatigue at 80% PP was significantly higher during supine compared with upright posture (-68 ± 14 vs. -26 ± 6 W min-1, respectively, P\0.05) and the divergence of the fatigue responses occurred by the second minute of exercise. NEMG responses were significantly higher in the supine posture by 1–4 min of exercise. Results show that fatigue is significantly greater during supine compared with upright high-intensity cycling and this effect is accompanied by a reduced activation of musculature that is active during cycling.

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This study investigated cycling performance and oxygen uptake (VO2) kinetics between upright and two commonly used recumbent (R) postures, 65ºR and 30ºR. On three occasions, ten young active males performed three bouts of high-intensity constant-load (85% peak workload achieved during a graded test) cycling in one of the three randomly assigned postures (upright, 65ºR or 30ºR). The first bout was performed to fatigue and second and third bouts were limited to 7 min. A subset of seven subjects performed a final constant-load test to failure in the supine posture. Exercise time to failure was not altered when the body inclination was lowered from the upright (13.1 ± 4.5 min) to 65ºR (10.5 ± 2.7 min) and 30ºR (11.5 ± 4.6 min) postures; but it was significantly shorter in the supine posture (5.8 ± 2.1 min) when compared with the three inclined postures. Resulting kinetic parameters from a tri-exponential analysis of breath-by-breath VO2 data during the first 7 min of exercise were also not different between the three inclined postures. However, inert gas rebreathing analysis of cardiac output revealed a greater cardiac output and stroke volume in both recumbent postures compared with the upright posture at 30 s into the exercise. These data suggest that increased cardiac function may counteract the reduction of hydrostatic pressure from upright ~25 mmHg; to 65ºR ~22 mmHg; and 30ºR ~18 mmHg such that perfusion of active muscle presumably remains largely unchanged, and also therefore, VO2 kinetics and performance during high-intensity cycling.

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This paper proposes a vision‐based autonomous move‐to‐grasp approach for a compact mobile manipulator under some low and small environments. The visual information of specified object with a radial symbol and an overhead colour block is extracted from two CMOS cameras in an embedded way. Furthermore, the mobile platform and the postures of the manipulator are adjusted continuously by vision‐based control, which drives the mobile manipulator approaching the object. When the mobile manipulator is sufficiently close to the object, only the manipulator moves to grasp the object based on the incremental movement with its head end centre of the end‐effector conforming to a Bezier curve. The effectiveness of the proposed approach is verified by experiments.

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 In this research, a novel method for generating training data of human postures with attached objects is proposed. The results has shown a significant increase in body-part classification accuracy for subjects with props from 60% to 94% using the generated image set

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OBJECTIVE: To determine the validity of a triaxial body-worn accelerometer for detection of gait and postures in people aged >80 years. DESIGN: Participants performed a range of activities (sitting, lying, walking, standing) in both a controlled and a home setting while wearing the accelerometer. Activities in the controlled setting were performed in a scripted sequence. Activities in the home setting were performed in an unscripted manner. Analyzed accelerometer data were compared against video observation as the reference measure. SETTING: Independent-living and long-term-care retirement village. PARTICIPANTS: Older people (N=22; mean age ± SD, 88.1±5y) residing in long-term-care and independent-living retirement facilities. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The level of agreement between video observation and the accelerometer for the total duration of each activity, and second-by-second correspondence between video observation and the accelerometer for each activity. RESULTS: The median absolute percentage errors between video observation and the accelerometer were <1% for locomotion and lying. The absolute percentage errors were higher for sitting (median, -22.3%; interquartile range [IQR], -62.8% to 10.7%) and standing (median, 24.7%; IQR, -7.3% to 39.6%). A second-by-second analysis between video observation and the accelerometer found an overall agreement of ≥85% for all activities except standing (median, 56.1%; IQR, 34.8%-81.2%). CONCLUSIONS: This single-device accelerometer provides a valid measure of lying and locomotion in people aged >80 years. There is an error of approximately 25% when discriminating sitting from standing postures, which needs to be taken into account when monitoring longer-term habitual activity in this age group.

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Recently, a renewed attention has been drawn into the dart-thrower's motion as the radiocarpal joint is unique to humans and this is believed to have played a pivotal role in human evolution. Considering the importance of the motion and the complexity of the wrist joint, there have been many articles discussing the kinematics behind this movement. CT scan techniques have been used in a number of these research activities. Due to limitations in the speed of the image acquisition, the positions of the wrist were recorded in static postures. To our knowledge, a data acquisition for the motion with realtime capturing has not been reported. This paper presents the use of a 3D vision-based motion capture device. Leap Motion Controller (LMC), for measuring the radiocarpal joint angles during the dart-thrower's motion in a real-time analysis. The practical capability of the LMC in measuring dart-thrower's motion was examined in a trial involving four subjects and the angles were compared to the angles acquired from an inertial measurement unit (IMU). The results confirmed the LMC can successfully be used in the application of measuring radiocarpal kinematics" of dart-thrower's motion.