scholarly journals Shortcomings of human-in-the-loop optimization for an ankle-foot prosthesis: a case series

Author(s):  
Cara G. Welker ◽  
Alexandra S. Voloshina ◽  
Vincent L. Chiu ◽  
Steven H. Collins

ABSTRACTHuman-in-the-loop optimization allows for individualized device control based on measured human performance. This technique has been used to produce large reductions in energy expenditure during walking with exoskeletons but has not yet been applied to prosthetic devices. In this series of case studies, we applied human-in-the-loop optimization to the control of an active ankle-foot prosthesis used by participants with unilateral transtibial amputation. We optimized the parameters of five control architectures that captured aspects of successful exoskeletons and commercial prostheses, but none resulted in significantly lower metabolic rate than generic control. In one control architecture, we increased the exposure time per condition by a factor of five, but the optimized controller still resulted in higher metabolic rate. Finally, we optimized for self-reported comfort instead of metabolic rate, but the resulting controller was not preferred. There are several reasons why human-in-the-loop optimization may have failed for people with amputation. Control architecture is an unlikely cause given the variety of controllers tested. The lack of effect likely relates to adaptation protocol or differences in the learning mechanisms or objectives of people with amputation. Future work should investigate these causes to determine whether human-in-the-loop optimization for prostheses could be successful.

2021 ◽  
Author(s):  
Sanaz Mehranfar ◽  
Seyed Davar Siadat ◽  
Sara Ahmadi Badi ◽  
Sara Hajishizari ◽  
Mir Saeed Yekaninejad ◽  
...  

Abstract Purpose Low Resting Metabolic Rate (RMR), as a risk factor for obesity, can be affected by many factors. Indeed, genetic and environmental factors are variables taken into account when predicting RMR, and may contribute to a high inter-individual variance. Besides the well-known causes of obesity, researchers have demonstrated the contribution of gut microflora in obesity and energy expenditure. Therefore, the goal of the current study was to compare the Firmicutes/Bacteroidetes ratio and the relative abundance of, Prevotellaceae, Faecalibacterium prausnitzii, bifidobactrium spp, lactobacillus spp, Akkermansia muciniphila, Bacteroides fragilis, and Escherichia coli in two groups of people with normal and low RMR in overweigh/obese women in Iran. Results The abundance of F. prausnitzii (p>0.001), B. fragilis (P= 0.02), and Firmicutes phylum (P= 0.02) were significantly higher in the controls compared to the cases, and showed significant positive association with RMR, (β = 1.29 ×10−5, P=0.01), (β = 4.13 ×10−6, p= 0.04), and (β = 7.76 ×10−1, p= 0.01), respectively. Regarding Lactobacilus, the results showed a significant positive association with RMR (β = 1.73 ×10−4, p= 0.01). Conclusion Intestinal microbiota may be associated with host metabolism. Therefore, future work should investigate, using clinical trials, the impact of manipulating gut microflora to positively influence energy expenditure.


Animals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 215
Author(s):  
Dane W. Fausnacht ◽  
Kellie A. Kroscher ◽  
Ryan P. McMillan ◽  
Luciane S. Martello ◽  
Lance H. Baumgard ◽  
...  

Heat stress (HS) diminishes animal production, reducing muscle growth and increasing adiposity, especially in swine. Excess heat creates a metabolic phenotype with limited lipid oxidation that relies on aerobic and anaerobic glycolysis as a predominant means of energy production, potentially reducing metabolic rate. To evaluate the effects of HS on substrate utilization and energy expenditure, crossbred barrows (15.2 ± 2.4 kg) were acclimatized for 5 days (22 °C), then treated with 5 days of TN (thermal neutral, 22 °C, n = 8) or HS (35 °C, n = 8). Pigs were fed ad libitum and monitored for respiratory rate (RR) and rectal temperature. Daily energy expenditure (DEE) and respiratory exchange ratio (RER, CO2:O2) were evaluated fasted in an enclosed chamber through indirect calorimetry. Muscle biopsies were obtained from the longissimus dorsi pre/post. HS increased temperature (39.2 ± 0.1 vs. 39.6 ± 0.1 °C, p < 0.01) and RER (0.91 ± 0.02 vs. 1.02 ± 0.02 VCO2:VO2, p < 0.01), but decreased DEE/BW (68.8 ± 1.7 vs. 49.7 ± 4.8 kcal/day/kg, p < 0.01) relative to TN. Weight gain (p = 0.80) and feed intake (p = 0.84) did not differ between HS and TN groups. HS decreased muscle metabolic flexibility (~33%, p = 0.01), but increased leucine oxidation (~35%, p = 0.02) compared to baseline values. These data demonstrate that HS disrupts substrate regulation and energy expenditure in growing pigs.


Author(s):  
Ryan Mullins ◽  
Deirdre Kelliher ◽  
Ben Nargi ◽  
Mike Keeney ◽  
Nathan Schurr

Recently, cyber reasoning systems demonstrated near-human performance characteristics when they autonomously identified, proved, and mitigated vulnerabilities in software during a competitive event. New research seeks to augment human vulnerability research teams with cyber reasoning system teammates in collaborative work environments. However, the literature lacks a concrete understanding of vulnerability research workflows and practices, limiting designers’, engineers’, and researchers’ ability to successfully integrate these artificially intelligent entities into teams. This paper contributes a general workflow model of the vulnerability research process, and identifies specific collaboration challenges and opportunities anchored in this model. Contributions were derived from a qualitative field study of work habits, behaviors, and practices of human vulnerability research teams. These contributions will inform future work in the vulnerability research domain by establishing an empirically-driven workflow model that can be adapted to specific organizational and functional constraints placed on individual and teams.


1978 ◽  
Vol 35 (6) ◽  
pp. 816-821 ◽  
Author(s):  
J. R. Brett ◽  
J. M. Blackburn

The metabolic rate of spiny dogfish, Squalus acanthias, was determined in both a tunnel respirometer and a large, covered, circular tank (mass respirometer). Swimming performance was very poor in the respirometer, so that a power–performance curve could not be established. Instead, resting metabolic rates were determined, with higher rates induced by causing heavy thrashing (active metabolism). Routine metabolic rates were measured for the spontaneous activity characterizing behavior in the circular tank. For fish of 2 kg mean weight, the metabolic rates at 10 °C were 32.4 ± 2.6 SE (resting), 49.2 ± 5.0 SE (routine), and 88.4 ± 4.6 SE (active) mg O2∙kg−1∙h−1. Assuming that the routine rate represents a general energy expenditure in nature, this is equivalent to metabolizing about 3.8 kcal∙kg−1∙d−1 (15.9 × 103 J∙kg−1∙d−1). Key words: dogfish, metabolic rates, energetics, respiration


1997 ◽  
Vol 36 (4) ◽  
pp. 310-312 ◽  
Author(s):  
F. Thielecke ◽  
J. Möseneder ◽  
A. Kroke ◽  
K. Klipstein-Grobusch ◽  
H. Boeing ◽  
...  

2021 ◽  
Author(s):  
Patrick Mullie ◽  
Pieter Maes ◽  
Laurens van Veelen ◽  
Damien Van Tiggelen ◽  
Peter Clarys

ABSTRACT Introduction Adequate energy supply is a prerequisite for optimal performances and recovery. The aims of the present study were to estimate energy balance and energy availability during a selection course for Belgian paratroopers. Methods Energy expenditure by physical activity was measured with accelerometer (ActiGraph GT3X+, ActiGraph LLC, Pensacola, FL, USA) and rest metabolic rate in Cal.d−1 with Tinsley et al.’s equation based on fat-free mass = 25.9 × fat-free mass in kg + 284. Participants had only access to the French individual combat rations of 3,600 Cal.d−1, and body fat mass was measured with quadripolar impedance (Omron BF508, Omron, Osaka, Japan). Energy availability was calculated by the formula: ([energy intake in foods and beverages] − [energy expenditure physical activity])/kg FFM−1.d−1, with FFM = fat-free mass. Results Mean (SD) age of the 35 participants was 25.1 (4.18) years, and mean (SD) percentage fat mass was 12.0% (3.82). Mean (SD) total energy expenditure, i.e., the sum of rest metabolic rate, dietary-induced thermogenesis, and physical activity, was 5,262 Cal.d−1 (621.2), with percentile 25 at 4,791 Cal.d−1 and percentile 75 at 5,647 Cal.d−1, a difference of 856 Cal.d−1. Mean daily energy intake was 3,600 Cal.d−1, giving a negative energy balance of 1,662 (621.2) Cal.d−1. Mean energy availability was 9.3 Cal.kg FFM−1.d−1. Eleven of the 35 participants performed with a negative energy balance of 2,000 Cal.d−1, and only five participants out of 35 participants performed at a less than 1,000 Cal.d−1 negative energy balance level. Conclusions Energy intake is not optimal as indicated by the negative energy balance and the low energy availability, which means that the participants to this selection course had to perform in suboptimal conditions.


Author(s):  
Jingjing Xue ◽  
Shuo Li ◽  
Rou Wen ◽  
Ping Hong

Background: The purpose of this study was to investigate the accuracy of the published prediction equations for determining level overground walking energy cost in young adults. Methods: In total, 148 healthy young adults volunteered to participate in this study. Resting metabolic rate and energy expenditure variables at speeds of 4, 5, and 6 km/h were measured by indirect calorimetry, walking energy expenditure was estimated by 3 published equations. Results: The gross and net metabolic rate per mile of level overground walking increased with increased speed (all P < .01). Females were less economical than males. The present findings revealed that the American College of Sports Medicine and Pandolf et al equations significantly underestimated the energy cost of overground walking at all speeds (all P < .01) in young adults. The percentage mean bias for American College of Sports Medicine, Pandolf et al, and Weyand et al was 12.4%, 16.8%, 1.4% (4 km/h); 21.6%, 15.8%, 7.1% (5 km/h); and 27.6%, 12%, 6.6% (6 km/h). Bland–Altman plots and prediction error analysis showed that the Weyand et al was the most accurate in 3 existing equations. Conclusions: The Weyand et al equation appears to be the most suitable for the prediction of overground walking energy expenditure in young adults.


PEDIATRICS ◽  
1993 ◽  
Vol 91 (2) ◽  
pp. 281-286
Author(s):  
Robert C. Klesges ◽  
Mary L. Shelton ◽  
Lisa M. Klesges

The effects of television viewing on resting energy expenditure (metabolic rate) in obese and normal-weight children were studied in a laboratory setting. Subjects were 15 obese children and 16 normal-weight children whose ages ranged from 8 to 12 years. All subjects had two measures of resting energy expenditure obtained while at rest and one measurement of energy expenditure taken while viewing television. Results indicated that metabolic rate during television viewing was significantly lower (mean decrease of 211 kcal extrapolated to a day) than during rest. Obese children tended to have a larger decrease, although this difference was not statistically significant (262 kcal/d vs 167 kcal/d, respectively). It was concluded that television viewing has a fairly profound lowering effect of metabolic rate and may be a mechanism for the relationship between obesity and amount of television viewing.


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