scholarly journals Data-driven geometric system identification for shape-underactuated dissipative systems

2021 ◽  
Author(s):  
Brian Arthur Bittner ◽  
Ross L Hatton ◽  
Shai Revzen
Keyword(s):  
System Identification ◽  
Body Shape ◽  
The Body ◽  
System Model ◽  
Data Driven ◽  
Model Complexity ◽  
Dissipative Systems ◽  
Pneumatic Actuators ◽  
Series Elastic Actuators

Abstract Systems whose movement is highly dissipative provide an opportunity to both identify models easily and quickly optimize motions. Geometric mechanics provides means for reduction of the dynamics by environmental homogeneity, while the dissipative nature minimizes the role of second order (inertial) features in the dynamics. Here we extend the tools of geometric system identification to ``Shape-Underactuated Dissipative Systems (SUDS)'' -- systems whose motions are more dissipative than inertial, but whose actuation is restricted to a subset of the body shape coordinates. Many animal motions are SUDS, including micro-swimmers such as nematodes and flagellated bacteria, and granular locomotors such as snakes and lizards. Many soft robots are also SUDS, particularly those robots using highly damped series elastic actuators. Whether involved in locomotion or manipulation, these robots are often used to interface less rigidly with the environment. We motivate the use of SUDS models, and validate their ability to predict motion of a variety of simulated viscous swimming platforms. For a large class of SUDS, we show how the shape velocity actuation inputs can be directly converted into torque inputs suggesting that systems with soft pneumatic actuators or dielectric elastomers can be modeled with the tools presented. Based on fundamental assumptions in the physics, we show how our model complexity scales linearly with the number of passive shape coordinates. This offers a large reduction on the number of trials needed to identify the system model from experimental data, and may reduce overfitting. The sample efficiency of our method suggests its use in modeling, control, and optimization in robotics, and as a tool for the study of organismal motion in friction dominated regimes.

scholarly journals Men, appearance, and cosmetic surgery: The role of confidence, self-esteem, and comfort with the body

2008 ◽  
Vol 34 (1) ◽  
pp. 105-134 ◽  
Author(s):  
Rosemary Ricciardelli ◽  
Kimberley Ann Clow
Keyword(s):  
Cosmetic Surgery ◽  
Body Shape ◽  
Online Survey ◽  
Identity Theory ◽  
Self Esteem ◽  
The Body ◽  
Sociology Of The Body ◽  
Lower Confidence

Recent research has suggested that perceptions of the body are important to men’s sense of confidence and that men see the body as a vehicle for personal improvement. To build on this research, an online survey investigated Canadian men’s perspectives on their appearance and their attitudes toward cosmetic surgery. Low self-esteem, lack of confidence, and comfort with one’s body uniquely predicted different aspects of men’s experiences, including attitudes about body shape, perceptions of others, pressures to lose weight, and perspectives regarding cosmetic surgery. For example, participants who were more comfortable with their bodies and higher in self-esteem were happier with their current body shape and features, whereas participants who were less comfortable with their bodies and lower in confidence put more pressure on themselves to lose weight. In addition, lower confidence significantly predicted willingness to undergo cosmetic surgery. Men’s perspectives on cosmetic surgery were thematically analyzed. These findings are situated within identity theory and sociology of the body.

Oscillatory motion and wake instability of freely rising axisymmetric bodies

2007 ◽  
Vol 573 ◽  
pp. 479-502 ◽  
Author(s):  
PEDRO C. FERNANDES ◽  
FRÉDÉRIC RISSO ◽  
PATRICIA ERN ◽  
JACQUES MAGNAUDET
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Axial Velocity ◽  
Body Shape ◽  
Rigid Bodies ◽  
The Body ◽  
Body Motion ◽  
Wake Instability ◽  
Moving Bodies

This paper reports on an experimental study of the motion of freely rising axisym- metric rigid bodies in a low-viscosity fluid. We consider flat cylinders with height h smaller than the diameter d and density ρb close to the density ρf of the fluid. We have investigated the role of the Reynolds number based on the mean rise velocity um in the range 80 ≤ Re = umd/ν ≤ 330 and that of the aspect ratio in the range 1.5 ≤ χ = d/h ≤ 20. Beyond a critical Reynolds number, Rec, which depends on the aspect ratio, both the body velocity and the orientation start to oscillate periodically. The body motion is observed to be essentially two-dimensional. Its description is particularly simple in the coordinate system rotating with the body and having its origin fixed in the laboratory; the axial velocity is then found to be constant whereas the rotation and the lateral velocity are described well by two harmonic functions of time having the same angular frequency, ω. In parallel, direct numerical simulations of the flow around fixed bodies were carried out. They allowed us to determine (i) the threshold, Recf1(χ), of the primary regular bifurcation that causes the breaking of the axial symmetry of the wake as well as (ii) the threshold, Recf2(χ), and frequency, ωf, of the secondary Hopf bifurcation leading to wake oscillations. As χ increases, i.e. the body becomes thinner, the critical Reynolds numbers, Recf1 and Recf2, decrease. Introducing a Reynolds number Re* based on the velocity in the recirculating wake makes it possible to obtain thresholds $\hbox{\it Re}^*_{cf1}$ and $\hbox{\it Re}^*_{cf2}$ that are independent of χ. Comparison with fixed bodies allowed us to clarify the role of the body shape. The oscillations of thick moving bodies (χ < 6) are essentially triggered by the wake instability observed for a fixed body: Rec(χ) is equal to Recf1(χ) and ω is close to ωf. However, in the range 6 ≤ χ ≤ 10 the flow corrections induced by the translation and rotation of freely moving bodies are found to be able to delay the onset of wake oscillations, causing Rec to increase strongly with χ. An analysis of the evolution of the parameters characterizing the motion in the rotating frame reveals that the constant axial velocity scales with the gravitational velocity based on the body thickness, $\sqrt{((\rho_f-\rho_b)/\rho_f)\,gh}$, while the relevant length and velocity scales for the oscillations are the body diameter d and the gravitational velocity based on d, $\sqrt{((\rho_f-\rho_b)/\rho_f)\,gd}$, respectively. Using this scaling, the dimensionless amplitudes and frequency of the body's oscillations are found to depend only on the modified Reynolds number, Re*; they no longer depend on the body shape.

The Nature of Emotional Disorders

2010 ◽  
pp. 13-16
Author(s):  
David H. Barlow ◽  
Todd J. Farchione ◽  
Christopher P. Fairholme ◽  
Kristen K. Ellard ◽  
Christina L. Boisseau ◽  
...  
Keyword(s):  
Emotion Regulation ◽  
Emotional Disorders ◽  
The Body ◽  
Data Driven

Chapter 2 discusses the nature of emotional disorders (empirical and data-driven conceptions of anxiety and major emotional disorders, emerging research, the body of evidence), etiology (including the triple vulnerabilities theory), and the role of emotion regulation.

Evidence of a heritable component to body shape in the northern redbelly dace (Phoxinus eos)

1997 ◽  
Vol 75 (8) ◽  
pp. 1247-1253 ◽  
Author(s):  
C. Anna Toline ◽  
Allan J. Baker
Keyword(s):  
Body Shape ◽  
Natural Populations ◽  
The Body ◽  
Foraging Ability ◽  
Environmental Induction ◽  
Foraging Tactics ◽  
Selection For ◽  
Shape Changes ◽  
Common Laboratory

Hypotheses about the role of selection on body-shape evolution assume a heritable component to this phenotypic character. To examine the influence of environmental induction on body shape, offspring form two morphologically differentiated populations of northern redbelly dace (Phoxinus eos) were reared in a common laboratory environment. Additionally, shape changes were monitored over 3 consecutive years in six populations. Offspring reared in a common environment retained the body shape of individuals from their natal pond, and shape changes among fish in different ponds were maintained in natural populations over years. These results strongly suggest a heritable component to body shape in P. eos. These results complement earlier work examining foraging tactics as a potential selection pressure on body shape and support the conclusion that body-shape differences among fish in different ponds are being maintained by selection for foraging ability.

7. Shape and Motion Integration in People Perception Depends on the Action of the Performer

2018 ◽  
Author(s):  
Claire Honda
Keyword(s):  
Visual Information ◽  
Body Shape ◽  
Object Perception ◽  
Human Action ◽  
The Body ◽  
Motion Information ◽  
Centre Of Mass ◽  
Indirect Object ◽  
Throw Distance

Perception of human action depends on both the body shape and motion of a performer. We can indirectly perceive the properties of an object being acted upon even when visual information is limited and the object itself is not visible; we accomplish this using internal models of a body’s dynamics and an action’s kinematics (Runeson & Frykholm, 1981). We are also sensitive to correlations between a performer’s shape and motion, known as internal consistency (Runeson & Frykholm, 1983). To investigate how decorrelating shape and motion affects indirect object perception, we ran an experiment where participants watched realistic avatars of performers manipulating invisible objects. Unbeknownst to participants, half of the stimuli were internally inconsistent: the shape of one performer was combined with the motion of a performer with a dissimilar body shape. Participants saw sled pushes, beanbag throws, and box lifts, and estimated the sled weight, throw distance, or box weight. For sled pushes, there was a shape-motion interaction such that heavy bodies were perceived as pushing heavier weights when animated with motion from light performers, and light bodies were perceived as pushing lighter weights when animated with motion from heavy performers. In contrast, participants estimated beanbag throw distance primarily from performer motion. Interpretation of the box lift data is more complex. In conclusion, the way in which our visual system combines shape and motion information depends on the role of body shape and centre of mass on the outcome of an action.

scholarly journals Vestibular compensation in lampreys: impairment and recovery of equilibrium control during locomotion

1997 ◽  
Vol 200 (10) ◽  
pp. 1459-1471 ◽  
Author(s):  
T Deliagina
Keyword(s):  
Control System ◽  
Body Shape ◽  
The Body ◽  
Vestibular Compensation ◽  
Motor Deficit ◽  
Loss Of Function ◽  
Roll Control ◽  
Locomotor Pattern ◽  
Equilibrium Control

Removal of a vestibular organ (unilateral labyrinthectomy, UL) in the lamprey (Lampetra fluviatilis) results in a loss of equilibrium, so that the animal rolls (rotates around its longitudinal axis) almost continuously when swimming. This paper describes (i) UL-evoked disturbances of the pattern of locomotory movements responsible for rolling, (ii) recovery of equilibrium control after UL (vestibular compensation), and (iii) the role of vision in the recovery of equilibrium control. It was found that rolling is caused by an asymmetry in the undulatory locomotory movements, with larger deviations of the head towards the side with an intact labyrinth. The rolling appeared to be synchronized with the undulatory locomotory rhythm: during one complete roll turn (360 &deg;), two cycles of locomotion were performed. A characteristic feature of the UL-induced motor deficit in the lamprey is the alternation of episodes of impaired swimming (with a distortion of the body shape and of the locomotor pattern and with a loss of equilibrium) with episodes of normal swimming (without any marked distortion of the locomotor pattern or loss of equilibrium). In the course of recovery after UL, the duration and frequency of the appearance of episodes of normal swimming increased, whereas episodes of impaired swimming became less frequent and shorter. The recovery of equilibrium control and the role of vision in recovery were investigated in lampreys with different combinations of lesions to the vestibular and visual sensory organs. In group 1 (UL only) animals, the time required for 80 % recovery was, on average, 33 days. In group 2 (UL and removal of both eyes) and in group 3 (UL and removal of the contralateral eye) animals, vestibular compensation was considerably retarded, and normal functioning of the roll control system was not regained even 3 months after UL. In contrast, in group 4 (UL and removal of the ipsilateral eye) animals, no impairment of the equilibrium control was observed, and the animals swam without rolling immediately after surgery. These findings indicate (i) that the visual system is important for the process of vestibular compensation, and (ii) that the deficiency in equilibrium control caused by UL can be abolished by means of unilateral (contralateral to UL) visual input. The hypothesis is advanced that the main UL-evoked motor deficit in the lamprey (loss of equilibrium) is primarily caused not by a persistent static distortion of the body shape, but by a loss of function of the roll control system responsible for stabilization of the dorsal-side-up orientation during swimming. A conceptual model of the roll control system of the lamprey, formulated in our previous studies, is used here to present arguments in favour of this hypothesis.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

The Role of Computer Modeling in Electrocardiography

1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom
Keyword(s):  
Electrical Activity ◽  
Computer Modeling ◽  
Body Surface ◽  
Electrical Current ◽  
The Body ◽  
Volume Conductor ◽  
Current Generator ◽  
Cardiac Electrical Activity ◽  
Source Models

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.

Questions on the role of biofilms for the adaptation of microorganisms to unfavorable environmental factors by the example of P. aeruginosa

2020 ◽  
Vol 99 (4) ◽  
pp. 379-383
Author(s):  
Vasily N. Afonyushkin ◽  
N. A. Donchenko ◽  
Ju. N. Kozlova ◽  
N. A. Davidova ◽  
V. Yu. Koptev ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Environmental Factors ◽  
Barrier Function ◽  
Infectious Agent ◽  
Antagonistic Activity ◽  
The Body ◽  
Main Function ◽  
Pathogenic Potential ◽  
The Face

Pseudomonas aeruginosa is a widely represented species of bacteria possessing of a pathogenic potential. This infectious agent is causing wound infections, fibrotic cystitis, fibrosing pneumonia, bacterial sepsis, etc. The microorganism is highly resistant to antiseptics, disinfectants, immune system responses of the body. The responses of a quorum sense of this kind of bacteria ensure the inclusion of many pathogenicity factors. The analysis of the scientific literature made it possible to formulate four questions concerning the role of biofilms for the adaptation of P. aeruginosa to adverse environmental factors: Is another person appears to be predominantly of a source an etiological agent or the source of P. aeruginosa infection in the environment? Does the formation of biofilms influence on the antibiotic resistance? How the antagonistic activity of microorganisms is realized in biofilm form? What is the main function of biofilms in the functioning of bacteria? A hypothesis has been put forward the effect of biofilms on the increase of antibiotic resistance of bacteria and, in particular, P. aeruginosa to be secondary in charcter. It is more likely a biofilmboth to fulfill the function of storing nutrients and provide topical competition in the face of food scarcity. In connection with the incompatibility of the molecular radii of most antibiotics and pores in biofilm, biofilm is doubtful to be capable of performing a barrier function for protecting against antibiotics. However, with respect to antibodies and immunocompetent cells, the barrier function is beyond doubt. The biofilm is more likely to fulfill the function of storing nutrients and providing topical competition in conditions of scarcity of food resources.

Receptions of the Past: Commemoration, Racism, Desire

Somatechnics ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 288-303
Author(s):  
Michael Connors Jackman
Keyword(s):  
Critical Point ◽  
Social Relations ◽  
White Privilege ◽  
Body Politic ◽  
The Body ◽  
Race And Racism ◽  
Lesbian And Gay ◽  
The Past ◽  
History Of

This article investigates the ways in which the work of The Body Politic (TBP), the first major lesbian and gay newspaper in Canada, comes to be commemorated in queer publics and how it figures in the memories of those who were involved in producing the paper. In revisiting a critical point in the history of TBP from 1985 when controversy erupted over race and racism within the editorial collective, this discussion considers the role of memory in the reproduction of whiteness and in the rupture of standard narratives about the past. As the controversy continues to haunt contemporary queer activism in Canada, the productive work of memory must be considered an essential aspect of how, when and for what reasons the work of TBP comes to be commemorated. By revisiting the events of 1985 and by sifting through interviews with individuals who contributed to the work of TBP, this article complicates the narrative of TBP as a bluntly racist endeavour whilst questioning the white privilege and racially-charged demands that undergird its commemoration. The work of producing and preserving queer history is a vital means of challenging the intentional and strategic erasure of queer existence, but those who engage in such efforts must remain attentive to the unequal terrain of social relations within which remembering forms its objects.

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