scholarly journals Biomechanics and the wheelchair

1991 ◽  
Vol 15 (1) ◽  
pp. 24-37 ◽  
Author(s):  
C. A. McLaurin ◽  
C. E. Brubaker
Keyword(s):  
Power Output ◽  
Rolling Resistance ◽  
Metabolic Cost ◽  
Power Input ◽  
User Preferences ◽  
User Characteristics ◽  
Wheelchair User ◽  
Wind Resistance ◽  
The Individual ◽  
Source Of Information

Wheelchair biomechanics involves the study of how a wheelchair user imparts power to the wheels to achieve mobility. Because a wheelchair can coast, power input need not be continuous, but each power strike can be followed by a period of recovery, with the stroking frequency depending on user preferences and the coasting characteristics of the wheelchair. The latter is described in terms of rolling resistance, wind resistance and the slope of the surface. From these three factors the power required to propel the wheelchair is determined, and must be matched by the power output of the user. The efficiency of propulsion is the ratio of this power output to the metabolic cost and is typically in the order of 5% in normal use. The features required in a wheelchair depend upon user characteristics and intended activities. The ideal wheelchair for an individual will have the features that closely match these characteristics and activities. Thus prescription is not just choosing a wheelchair, but choosing the components of the wheelchair that best serve the intended purpose. In this paper, each component is examined for available options and how these options effect the performance of the wheelchair for the individual. The components include wheels, tyres, castors, frames, bearings, materials, construction details, seats, backrests, armrests, foot and legrests, headrests, wheel locks, running brakes, handrims, levers, accessories, adjustments and detachable parts. Each component is considered in relation to performance characteristics including rolling resistance, versatility, weight, comfort, stability, maneouvrability, transfer, stowage, durability and maintenance. Where they exist, wheelchair standards are referred to as a source of information regarding these characteristics.

Formation of Standing Waves in Radial Tires

1984 ◽  
Vol 12 (1) ◽  
pp. 44-63 ◽  
Author(s):  
Y. D. Kwon ◽  
D. C. Prevorsek
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Unit Length ◽  
Standing Waves ◽  
Rolling Resistance ◽  
Damping Coefficient ◽  
Circular Membrane ◽  
Critical Speeds ◽  
Steel Cord ◽  
The Individual

Abstract Radial tires for automobiles were subjected to high speed rolling under load on a testing wheel to determine the critical speeds at which standing waves started to form. Tires of different makes had significantly different critical speeds. The damping coefficient and mass per unit length of the tire wall were measured and a correlation between these properties and the observed critical speed of standing wave formation was sought through use of a circular membrane model. As expected from the model, desirably high critical speed calls for a high damping coefficient and a low mass per unit length of the tire wall. The damping coefficient is particularly important. Surprisingly, those tire walls that were reinforced with steel cord had higher damping coefficients than did those reinforced with polymeric cord. Although the individual steel filaments are elastic, the interfilament friction is higher in the steel cords than in the polymeric cords. A steel-reinforced tire wall also has a higher density per unit length. The damping coefficient is directly related to the mechanical loss in cyclic deformation and, hence, to the rolling resistance of a tire. The study shows that, in principle, it is more difficult to design a tire that is both fuel-efficient and free from standing waves when steel cord is used than when polymeric cords are used.

The Role of Normative Information in Judgments of Others

2019 ◽  
Author(s):  
Katherine H. Rogers
Keyword(s):  
Social Desirability ◽  
Interpersonal Perception ◽  
Future Research ◽  
Average Person ◽  
The Individual ◽  
The Relationship ◽  
Source Of Information

When forming impressions of an other’s personality, people often rely on information not directly related to the individual at hand. One source of information that can influence people’s impressions of others is the personality of the average person (i.e., normative profile). This relationship between the normative profile and an impression is called normative accuracy or normativity. In this chapter, you will learn about the average personality, why it is important, the relationship to social desirability and what it means to have a normative impression, as well as correlates and moderators of normativity. More broadly, you will learn about current research and views regarding the normative profile and normative impressions as well as concrete steps for incorporating this approach into your future research on interpersonal perception.

Costs of transport for the scyphomedusa Stomolophus meleagris L. Agassiz

1987 ◽  
Vol 65 (11) ◽  
pp. 2690-2695 ◽  
Author(s):  
R. J. Larson
Keyword(s):  
Output Power ◽  
Power Function ◽  
Power Output ◽  
Reynolds Numbers ◽  
Power Input ◽  
Cost Of Transport ◽  
Swimming Efficiency ◽  
Wet Weight ◽  
Planktonic Crustaceans ◽  
Stomolophus Meleagris

The rhizostome scyphomedusa Stomolophus meleagris swims continuously at speeds up to 15 cm∙s−1. Mean velocities increased as a power function of wet weight up to 70 g but were mostly constant thereafter. Bell pulsations ranged from 1.7 to 3.6 Hz. Reynolds numbers equalled 900 – 13 000. During activity, medusae consumed 0.05 mL O2∙h−1∙g WW−1 (1.2 mL O2∙h−1∙g DW−1), at 30 °C. Rates for inactive medusae were 50% less. The estimated cost of transport ranged from 2 J∙kg−1∙m−1 at 5 g to 1 J∙kg−1∙m−1 at 1 kg. These rates are comparable to those of fishes and about 1/50th that of planktonic crustaceans. These results were unexpected in light of the typical inefficiency (power output/power input) of jet swimming. However, S. meleagris has a very low respiration rate relative to crustaceans and fish, which probably compensated for low swimming efficiency.

Youtube as a source of information on "Manual Blood Pressure Measurement"

2021 ◽  
Author(s):  
Mehmet Fatih Yılmaz ◽  
Sedat Kalkan
Keyword(s):  
Blood Pressure ◽  
Pressure Measurement ◽  
Health Workers ◽  
Blood Pressure Measurement ◽  
Average Score ◽  
Educational Value ◽  
Manual Blood Pressure ◽  
The Individual ◽  
Source Of Information

Objectives: The aim of the study is to evaluate the quality and reliability of videos on manual blood pressure measurement on Youtube. Patients and Methods: In January 2021, the first 100 videos found as a result of a search with the keywords 'manual blood pressure measurement' on Youtube were watched and evaluated. According to exclusion criteria, 75 videos were included in the study. Duplicate videos, irrelevant videos, and videos in languages other than English were excluded from the study. Each video was scored according to the questions prepared based on the guidelines. The GQS score and the 'Reliability' score were used to assess the quality of the videos. Results: According to the checklist prepared according to the hypertension consensus report, the mean score of the videos was 8.33 ± 2.1. When the videos were evaluated according to their sources, the average score of the videos of the health sites was 9±2.5, the average score of the videos of the individual health workers was 8.66±1.8, the average score of the videos of the unidentified people was 7.54±2.1. Conclusion: Manual blood pressure measurement videos on Youtube have little educational value. Videos of health websites should be preferred for education.

scholarly journals Optimized hip-knee-ankle exoskeleton assistance reduces the metabolic cost of walking with worn loads

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Gwendolyn M. Bryan ◽  
Patrick W. Franks ◽  
Seungmoon Song ◽  
Ricardo Reyes ◽  
Meghan P. O’Donovan ◽  
...  
Keyword(s):  
Body Weight ◽  
Muscle Activity ◽  
Metabolic Cost ◽  
Load Carriage ◽  
Heavy Load ◽  
Human In The Loop ◽  
Light Load ◽  
Wide Range ◽  
Ankle Exoskeleton ◽  
The Individual

Abstract Background Load carriage is common in a wide range of professions, but prolonged load carriage is associated with increased fatigue and overuse injuries. Exoskeletons could improve the quality of life of these professionals by reducing metabolic cost to combat fatigue and reducing muscle activity to prevent injuries. Current exoskeletons have reduced the metabolic cost of loaded walking by up to 22% relative to walking in the device with no assistance when assisting one or two joints. Greater metabolic reductions may be possible with optimized assistance of the entire leg. Methods We used human-in the-loop optimization to optimize hip-knee-ankle exoskeleton assistance with no additional load, a light load (15% of body weight), and a heavy load (30% of body weight) for three participants. All loads were applied through a weight vest with an attached waist belt. We measured metabolic cost, exoskeleton assistance, kinematics, and muscle activity. We performed Friedman’s tests to analyze trends across worn loads and paired t-tests to determine whether changes from the unassisted conditions to the assisted conditions were significant. Results Exoskeleton assistance reduced the metabolic cost of walking relative to walking in the device without assistance for all tested conditions. Exoskeleton assistance reduced the metabolic cost of walking by 48% with no load (p = 0.05), 41% with the light load (p = 0.01), and 43% with the heavy load (p = 0.04). The smaller metabolic reduction with the light load may be due to insufficient participant training or lack of optimizer convergence. The total applied positive power was similar for all tested conditions, and the positive knee power decreased slightly as load increased. Optimized torque timing parameters were consistent across participants and load conditions while optimized magnitude parameters varied. Conclusions Whole-leg exoskeleton assistance can reduce the metabolic cost of walking while carrying a range of loads. The consistent optimized timing parameters across participants and conditions suggest that metabolic cost reductions are sensitive to torque timing. The variable torque magnitude parameters could imply that torque magnitude should be customized to the individual, or that there is a range of useful torque magnitudes. Future work should test whether applying the load to the exoskeleton rather than the person’s torso results in larger benefits.

A COMPARISON OF POWER INPUT VS. POWER OUTPUT FOR FOUR CYCLE ERGOMETERS

1995 ◽  
Vol 27 (Supplement) ◽  
pp. S245
Author(s):  
S. M. Puhl ◽  
L. F. Fussner ◽  
J. L. Hodgson ◽  
K. G. Stoedefalke
Keyword(s):  
Power Output ◽  
Power Input ◽  
Cycle Ergometers

Photos, Videos, and Other Technology

2017 ◽  
Author(s):  
Ron Astor ◽  
Rami Benbenishty
Keyword(s):  
Social Media ◽  
Monitoring System ◽  
School Safety ◽  
The Public ◽  
Staff Members ◽  
Reliable Source ◽  
The Media ◽  
The Individual ◽  
Speak Up ◽  
Source Of Information

On their own, photos and videos are not a reliable source of information about what is taking place in a school. It’s easy to react emotionally or with outrage to a video of a fight, a child being picked on, or some other display of abuse or wrongdoing. But everyone knows from highly publicized incidents posted on YouTube, Twitter, or other social media sites that photos and videos can be taken out of context. They tell a story, but they don’t tell the whole story. Even so, they can be used by administrators to discern whether the action shown in the photo or video is an isolated incident or could be a symptom of a larger problem. If an alarming photo or video taken at a school is receiving attention from the media, it’s better to talk about it with the school community as soon as possible than to pretend it didn’t happen. Situations like these create an opportunity to examine and share other sources of data about school safety, violence, and victimization. Too often, one incident can cause the public to draw conclusions about a school that are not accurate. That’s why a monitoring system is necessary— to put such an incident in context. Administrators who can refer to other sources of data regarding violence, drug use, or weapons can respond with more confidence when faced with criticism over one incident. As part of a monitoring system, photos, videos and other technology can be used for positive purposes. They allow students who might skip questions on a survey or don’t want to speak up during a focus group to express themselves in a different way. There are many examples of projects in which students are given cameras and microphones and encouraged to express themselves and present their experiences in school through this media. In addition to the individual students benefitting from such experiences, school leaders, staff members, and parents get the opportunity to see the school from the students’ perspectives.

scholarly journals Validity of the Velocomp PowerPod Compared With the Verve Cycling InfoCrank Power Meter

2019 ◽  
Vol 14 (10) ◽  
pp. 1382-1387 ◽  
Author(s):  
Paul F.J. Merkes ◽  
Paolo Menaspà ◽  
Chris R. Abbiss
Keyword(s):  
Power Output ◽  
Average Power ◽  
Dynamic Environment ◽  
Rolling Resistance ◽  
Mean Power ◽  
Power Meter ◽  
Test Study ◽  
Environment Study ◽  
Road Cyclists ◽  
Mean Power Output

Purpose: To determine the validity of the Velocomp PowerPod power meter in comparison with the Verve Cycling InfoCrank power meter. Methods: This research involved 2 separate studies. In study 1, 12 recreational male road cyclists completed 7 maximal cycling efforts of a known duration (2 times 5 s and 15, 30, 60, 240, and 600 s). In study 2, 4 elite male road cyclists completed 13 outdoor cycling sessions. In both studies, power output of cyclists was continuously measured using both the PowerPod and InfoCrank power meters. Maximal mean power output was calculated for durations of 1, 5, 15, 30, 60, 240, and 600 seconds plus the average power output in study 2. Results: Power output determined by the PowerPod was almost perfectly correlated with the InfoCrank (r > .996; P < .001) in both studies. Using a rolling resistance previously reported, power output was similar between power meters in study 1 (P = .989), but not in study 2 (P = .045). Rolling resistance estimated by the PowerPod was higher than what has been previously reported; this might have occurred because of errors in the subjective device setup. This overestimation of rolling resistance increased the power output readings. Conclusion: Accuracy of rolling resistance seems to be very important in determining power output using the PowerPod. When using a rolling resistance based on previous literature, the PowerPod showed high validity when compared with the InfoCrank in a controlled field test (study 1) but less so in a dynamic environment (study 2).

I ♥ FB

2017 ◽  
Vol 9 (2) ◽  
pp. 46-61 ◽  
Author(s):  
Tom Robinson ◽  
Clark Callahan ◽  
Kristoffer Boyle ◽  
Erica Rivera ◽  
Janice K Cho
Keyword(s):  
Social Networks ◽  
Social Network ◽  
Q Methodology ◽  
Uses And Gratifications ◽  
Online Social Network ◽  
Fourth Quarter ◽  
User Characteristics ◽  
The Individual ◽  
Network Studies

Virtually seductive qualities of identity sharing, content gratification, and ample social atmosphere have made Facebook the most popular social network, boasting 890 million daily users (“Facebook Reports Fourth Quarter,” 2015; Joinson, 2008; Orchard et al., 2014, Reinecke et al., 2014). Online social network studies largely overlook the individual, limiting the understanding of what exactly drives people to use, abuse, even become dependent on sites like Facebook. Based on the theory of uses and gratifications, Q methodology subjectively observes what draws users to Facebook, focusing specifically on Facebook user characteristics. Past studies neglect the existence of three of the four factor groups discovered in this study, making these effectually new discoveries for academia (Alloway, Runac, Quershi, & Kemp, 2014; Cheung, Chieu & Lee, 2011; Sheldon, 2008, Tosun, 2012; Yang & Brown, 2013). These findings increase understanding of online usage, even addiction, and will help cater future social networks to specific users.

scholarly journals Bioenergetics and Biomechanics of Handcycling at Submaximal Speeds in Athletes with a Spinal Cord Injury

Sports ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 16 ◽  
Author(s):  
Gabriela Fischer ◽  
Pedro Figueiredo ◽  
Luca Paolo Ardigò
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Rolling Resistance ◽  
Metabolic Cost ◽  
Mechanical Efficiency ◽  
Metabolic Power ◽  
Ecological Conditions ◽  
Air Resistance ◽  
Cord Injury ◽  
Biomechanical Parameters

Background: This study aimed at comparing bioenergetics and biomechanical parameters between athletes with tetraplegia and paraplegia riding race handbikes at submaximal speeds in ecological conditions. Methods: Five athletes with tetraplegia (C6-T1, 43 ± 6 yrs, 63 ± 14 kg) and 12 athletes with paraplegia (T4-S5, 44 ± 7 yrs, 72 ± 12 kg) rode their handbikes at submaximal speeds under metabolic measurements. A deceleration method (coasting down) was applied to calculate the rolling resistance and frontal picture of each participant was taken to calculate air resistance. The net overall Mechanical Efficiency (Eff) was calculated by dividing external mechanical work to the corresponding Metabolic Power. Results: Athletes with tetraplegia reached a lower aerobic speed (4.7 ± 0.6 m s−1 vs. 7.1 ± 0.9 m s−1, P = 0.001) and Mechanical Power (54 ± 15 W vs. 111 ± 25 W, P = 0.001) compared with athletes with paraplegia. The metabolic cost was around 1 J kg−1 m−1 for both groups. The Eff values (17 ± 2% vs. 19 ± 3%, P = 0.262) suggested that the handbike is an efficient assisted locomotion device. Conclusion: Handbikers with tetraplegia showed lower aerobic performances but a similar metabolic cost compared with handbikers with paraplegia at submaximal speeds in ecological conditions.

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