scholarly journals Humans use minimum cost movements in a whole-body task

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lijia Liu ◽  
Dana Ballard
Keyword(s):  
Dynamic Model ◽  
Tool Use ◽  
Large Scale ◽  
Minimum Cost ◽  
Whole Body ◽  
Energetic Cost ◽  
Body Movements ◽  
Closed Curves ◽  
General Movements ◽  
Musculoskeletal Systems

AbstractHumans have elegant bodies that allow gymnastics, piano playing, and tool use, but understanding how they do this in detail is difficult because their musculoskeletal systems are extraordinarily complicated. Nonetheless, common movements like walking and reaching can be stereotypical, and a very large number of studies have shown their energetic cost to be a major factor. In contrast, one might think that general movements are very individuated and intractable, but our previous study has shown that in an arbitrary set of whole-body movements used to trace large-scale closed curves, near-identical posture sequences were chosen across different subjects, both in the average trajectories of the body’s limbs and in the variance within trajectories. The commonalities in that result motivate explanations for its generality. One explanation could be that humans also choose trajectories that are economical in cost. To test this hypothesis, we situate the tracing data within a forty eight degree of freedom human dynamic model that allows the computation of movement cost. Using the model to compare movement cost data from nominal tracings against various perturbed tracings shows that the latter are more energetically expensive, inferring that the original traces were chosen on the basis of minimum cost.

scholarly journals Humans use minimum cost movements in a whole-body task

2020 ◽  
Author(s):  
Lijia Liu ◽  
Dana Ballard
Keyword(s):  
Neural Control ◽  
Large Scale ◽  
Minimum Energy ◽  
Minimum Cost ◽  
Whole Body ◽  
Energetic Cost ◽  
Energy Principle ◽  
Closed Curves ◽  
Minimum Energy Principle ◽  
New Perspective

AbstractHumans have elegant bodies that allow gymnastics, piano playing, and tool use, but understanding how they do this in detail is difficult because their musculoskeletal systems are extraordinarily complicated. Nonetheless, although movements can be very individuated, some common movements like walking and reaching can be stereotypical, with the movement cost a major factor. A recent study has extended these observations by showing that in an arbitrary set of whole-body movements used to trace large-scale closed curves, near-identical posture changes were chosen across different subjects, both in the average trajectories of the body’s limbs and in variations within trajectories. The commonality of that result motivates explanations for this generality. One could be that humans also choose trajectories that are economical in energetic cost. To test this hypothesis, we situate the tracing data within a fifty degree of freedom dynamic model of the human skeleton that allows the computation of movement cost. Comparing the model movement cost data from nominal tracings against various perturbed tracings shows that the latter are more energetically expensive, inferring that the original traces were chosen on the basis of minimum cost. Moreover, the computational approach used to establish minimum cost principle suggests a refinement of what is known about cortical movement representations.Author SummaryAlthough motor cortical areas have been extensively studied, their basic response properties are still only partially understood, and it remains controversial whether neural activity relates to muscle commands or to abstract movement features. We provide a new perspective of how movements may be resented in the brain by showing that humans chose trajectories with minimum energy cost while accomplishing goal-directed tasks. Furthermore, most of the current neural control studies are experimental. Our computational methodology coupled with a minimum energy principle suggests a refinement of the brain’s storage of remembered movements.

scholarly journals Adaptation of Random Binomial Graphs for Testing Network Flow Problems Algorithms

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1716
Author(s):  
Adrian Marius Deaconu ◽  
Delia Spridon
Keyword(s):  
Network Flow ◽  
Large Scale ◽  
Random Network ◽  
Minimum Cost ◽  
Maximum Flow ◽  
Network Flow Problems ◽  
Commodity Flow ◽  
Vast Number ◽  
Flow Problems ◽  
Execution Speed

Algorithms for network flow problems, such as maximum flow, minimum cost flow, and multi-commodity flow problems, are continuously developed and improved, and so, random network generators become indispensable to simulate the functionality and to test the correctness and the execution speed of these algorithms. For this purpose, in this paper, the well-known Erdős–Rényi model is adapted to generate random flow (transportation) networks. The developed algorithm is fast and based on the natural property of the flow that can be decomposed into directed elementary s-t paths and cycles. So, the proposed algorithm can be used to quickly build a vast number of networks as well as large-scale networks especially designed for s-t flows.

Cyclic Breathing Simulations in Large Scale Models of the Lung Airway From the Oronasal Opening to the Terminal Bronchioles

2012 ◽  
Author(s):  
D. Keith Walters ◽  
Greg W. Burgreen ◽  
Robert L. Hester ◽  
David S. Thompson ◽  
David M. Lavallee ◽  
...  
Keyword(s):  
Steady State ◽  
Boundary Conditions ◽  
Large Scale ◽  
Whole Body ◽  
Patient Specific ◽  
Cfd Simulations ◽  
Reduced Order ◽  
Scale Models ◽  
Steady State Simulation ◽  
Conducting Zone

Computational fluid dynamics (CFD) simulations were performed for unsteady periodic breathing conditions, using large-scale models of the human lung airway. The computational domain included fully coupled representations of the orotracheal region and large conducting zone up to generation four (G4) obtained from patient-specific CT data, and the small conducting zone (to G16) obtained from a stochastically generated airway tree with statistically realistic geometrical characteristics. A reduced-order geometry was used, in which several airway branches in each generation were truncated, and only select flow paths were retained to G16. The inlet and outlet flow boundaries corresponded to the oronasal opening (superior), the inlet/outlet planes in terminal bronchioles (distal), and the unresolved airway boundaries arising from the truncation procedure (intermediate). The cyclic flow was specified according to the predicted ventilation patterns for a healthy adult male at three different activity levels, supplied by the whole-body modeling software HumMod. The CFD simulations were performed using Ansys FLUENT. The mass flow distribution at the distal boundaries was prescribed using a previously documented methodology, in which the percentage of the total flow for each boundary was first determined from a steady-state simulation with an applied flow rate equal to the average during the inhalation phase of the breathing cycle. The distal pressure boundary conditions for the steady-state simulation were set using a stochastic coupling procedure to ensure physiologically realistic flow conditions. The results show that: 1) physiologically realistic flow is obtained in the model, in terms of cyclic mass conservation and approximately uniform pressure distribution in the distal airways; 2) the predicted alveolar pressure is in good agreement with previously documented values; and 3) the use of reduced-order geometry modeling allows accurate and efficient simulation of large-scale breathing lung flow, provided care is taken to use a physiologically realistic geometry and to properly address the unsteady boundary conditions.

scholarly journals Blunted emotion judgments of body movements in Parkinson’s disease

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Emmanuelle Bellot ◽  
Antoine Garnier-Crussard ◽  
Elodie Pongan ◽  
Floriane Delphin-Combe ◽  
Marie-Hélène Coste ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Mirror Neuron System ◽  
Mirror Neuron ◽  
Emotional Valence ◽  
Whole Body ◽  
Emotional Expressions ◽  
Emotional Facial Expressions ◽  
Body Movements ◽  
Point Light

AbstractSome of the behavioral disorders observed in Parkinson’s disease (PD) may be related to an altered processing of social messages, including emotional expressions. Emotions conveyed by whole body movements may be difficult to generate and be detected by PD patients. The aim of the present study was to compare valence judgments of emotional whole body expressions in individuals with PD and in healthy controls matched for age, gender and education. Twenty-eight participants (13 PD patients and 15 healthy matched control participants) were asked to rate the emotional valence of short movies depicting emotional interactions between two human characters presented with the “Point Light Displays” technique. To ensure understanding of the perceived scene, participants were asked to briefly describe each of the evaluated movies. Patients’ emotional valence evaluations were less intense than those of controls for both positive (p < 0.001) and negative (p < 0.001) emotional expressions, even though patients were able to correctly describe the depicted scene. Our results extend the previously observed impaired processing of emotional facial expressions to impaired processing of emotions expressed by body language. This study may support the hypothesis that PD affects the embodied simulation of emotional expression and the potentially involved mirror neuron system.

Efficiency of uphill locomotion in nocturnal and diurnal lizards

1996 ◽  
Vol 199 (3) ◽  
pp. 587-592 ◽  
Author(s):  
C Farley ◽  
M Emshwiller
Keyword(s):  
Body Mass ◽  
Low Cost ◽  
Minimum Cost ◽  
Mechanical Work ◽  
Energetic Cost ◽  
Cost Of Transport ◽  
Unit Distance ◽  
Cost Of Locomotion ◽  
Average Body Mass ◽  
Average Body

Nocturnal geckos can walk on level ground more economically than diurnal lizards. One hypothesis for why nocturnal geckos have a low cost of locomotion is that they can perform mechanical work during locomotion more efficiently than other lizards. To test this hypothesis, we compared the efficiency of the nocturnal gecko Coleonyx variegatus (average body mass 4.2 g) and the diurnal skink Eumeces skiltonianus (average body mass 4.8 g) when they performed vertical work during uphill locomotion. We measured the rate of oxygen consumption when each species walked on the level and up a 50 slope over a range of speeds. For Coleonyx variegatus, the energetic cost of traveling a unit distance (the minimum cost of transport, Cmin) increased from 1.5 to 2.7 ml O2 kg-1 m-1 between level and uphill locomotion. For Eumeces skiltonianus, Cmin increased from 2.5 to 4.7 ml O2 kg-1 m-1 between level and uphill locomotion. By taking the difference between Cmin for level and uphill locomotion, we found that the efficiency of performing vertical work during locomotion was 37 % for Coleonyx variegatus and 19 % for Eumeces skiltonianus. The similarity between the 1.9-fold difference in vertical efficiency and the 1.7-fold difference in the cost of transport on level ground is consistent with the hypothesis that nocturnal geckos have a lower cost of locomotion than other lizards because they can perform mechanical work during locomotion more efficiently.

Standard English in Trinidad: Multinormativity, Translocality, and Implications for the Dynamic Model and the EIF Model

2020 ◽  
pp. 274-297
Author(s):  
Philipp Meer ◽  
Dagmar Deuber
Keyword(s):  
Dynamic Model ◽  
Large Scale ◽  
Theoretical Framework ◽  
Standard English ◽  
Alternative Development ◽  
Comprehensive Understanding ◽  
Developmental Processes ◽  
Educational Domain ◽  
Speech Communities

This article applies the Dynamic Model and the Extra- and Intra-territorial Forces (EIF) Model to Standard English in Trinidad based on the findings of a large-scale attitude study. The results suggest that, in the educational domain in Trinidad, a multidimensional norm orientation with coexisting standards that incorporates exo- and endonormative tendencies is prevalent. The Dynamic Model is not fully able to explain the findings, but the EIF Model can account for this norm complexity. However, the assumption underlying both models that postcolonial Englishes prototypically achieve (full) endonormativity unless their development is stalled at an earlier stage or even reversed is unlikely to fully capture the norm developmental processes in Trinidad and other complex postcolonial speech communities. We therefore propose an extension of the EIF Model that, depending on the constellation, directionality, and continuity of different sets of forces, allows for multinormative stabilization as an alternative development. We also introduce translocality as an alternative theoretical framework for the conceptualization of forces and argue for a more comprehensive understanding of intra-varietal heterogeneity. An extended and modified version of the EIF Model that takes these further complexities into account can help explain the norm developments in highly complex postcolonial speech communities.

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