Performing Whole-Body Simulations of Gait with 3-D, Dynamic Musculoskeletal Models

Direct measurement of cartilage contact is not feasible, necessitating the use of musculoskeletal models to estimate the internal soft tissue loading associated with movement2. However, current computational models used to simulate movement often utilize simplified joint kinematic constraints which can only provide an estimate of the net joint reaction force1. Detailed finite element models of the knee have been created14 which can provide estimates of cartilage tissue stress, but are too computationally expensive to solve within the context of a whole body simulation of movement. Discrete element analysis (DEA) provides a viable alternative for rapidly computing contact stress patterns in movement15, However, even DEA models can be computationally expensive as high resolution polygonal meshes are needed to accurately represent complex cartilage geometries such as that seen on the femoral condyles and tibia plateau. In a DEA model, much of the computation time is spent querying for contact between triangles of two polygonal surfaces. The objective of this study was to investigate the potential for using graphic processor computation (GPU) to expedite contact detection5. To do this, we use a contact detection algorithm that pre-constructs hierarchical bounding-volumes (BVH) of the target body to increase the efficiency of contact detection. We then show that implementing a parallel computational version of this algorithm on the GPU greatly speed up performance and thus make it more viable to simulate cartilage contact within the context of human movement.

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Real-Time Vertical Ground Reaction Force Estimation in a Unified Simulation Framework Using Inertial Measurement Unit Sensors

Robotics ◽

10.3390/robotics9040088 ◽

2020 ◽

Vol 9 (4) ◽

pp. 88

Author(s):

Elliot Recinos ◽

John Abella ◽

Shayan Riyaz ◽

Emel Demircan

Keyword(s):

Real Time ◽

Inertial Measurement Unit ◽

Human Motion ◽

Whole Body ◽

Measurement Unit ◽

Ground Reaction Forces ◽

Inertial Measurement ◽

Musculoskeletal Models ◽

Reaction Forces ◽

Vertical Ground

Recent advances in computational technology have enabled the use of model-based simulation with real-time motion tracking to estimate ground reaction forces during gait. We show here that a biomechanical-based model including a foot-ground contact can reproduce measured ground reaction forces using inertial measurement unit data during single-leg support, single-support jump, side to side jump, jogging, and skipping. The framework is based on our previous work on integrating the OpenSim musculoskeletal models with the Unity environment. The validation was performed on a single subject performing several tasks that involve the lower extremity. The novelty of this paper includes the integration and real-time tracking of inertial measurement unit data in the current framework, as well as the estimation of contact forces using biologically based musculoskeletal models. The RMS errors of tracking the vertical ground reaction forces are 0.027 bodyweight, 0.174 bodyweight, 0.173 bodyweight, 0.095 bodyweight, and 0.10 bodyweight for single-leg support, single-support jump, side to side jump, jogging, and skipping, respectively. The average RMS error for all tasks and trials is 0.112 bodyweight. This paper provides a computational framework for further applications in whole-body human motion analysis.

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Neck Musculoskeletal Model Generation through Anthropometric Scaling

10.1101/695833 ◽

2019 ◽

Author(s):

Paulien E. Roos ◽

Anita Vasavada ◽

Liying Zheng ◽

Xianlian Zhou

Keyword(s):

Optimization Method ◽

Bilevel Optimization ◽

Musculoskeletal Model ◽

Whole Body ◽

Model Generation ◽

Neck Length ◽

Anthropometric Parameters ◽

Us Army ◽

Musculoskeletal Models ◽

Neck Strength

ABSTRACTA new methodology was developed to quickly generate whole body models with detailed neck musculoskeletal architecture that are properly scaled in terms of anthropometry and muscle strength. This method was implemented in an anthropometry model generation software that allows users to interactively generate any new male or female musculoskeletal models with adjustment of anthropometric parameters (such as height, weight, neck circumference, and neck length) without the need of subject-specific motion capture or medical images. 50th percentile male and female models were developed based on the 2012 US Army Anthropometric Survey (ANSUR II) database and optimized with a novel bilevel optimization method to have strengths comparable to experimentally measured values in the literature. Other percentile models (ranging from the 1st to 99th percentile) were generated based on anthropometric scaling of the 50th percentile models and compared. The resultant models are reasonably accurate in terms of both musculoskeletal geometry and neck strength, demonstrating the effectiveness of the developed methodology for interactive neck model generation with anthropometric scaling.

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Occurrence and biogeographic significance of Heliaster (Echinodermata: Asteroidea) from the Pliocene of southwest Florida

Journal of Paleontology ◽

10.1017/s0022336000058960 ◽

1988 ◽

Vol 62 (01) ◽

pp. 126-132 ◽

Cited By ~ 8

Author(s):

Douglas S. Jones ◽

Roger W. Portell

Keyword(s):

Central American ◽

Eastern Pacific ◽

Whole Body ◽

Marine Fauna ◽

Western Atlantic ◽

Southwest Florida ◽

Extant Species ◽

Geologic Record ◽

Central American Isthmus

Whole body asteroid fossils are rare in the geologic record and previously unreported from the Cenozoic of Florida. However, specimens of the extant species,Heliaster microbrachiusXantus, were recently discovered in upper Pliocene deposits. This marks the first reported fossil occurrence of the monogeneric Heliasteridae, a group today confined to the eastern Pacific. This discovery provides further non-molluscan evidence of the close similarities between the Neogene marine fauna of Florida and the modern fauna of the eastern Pacific. The extinction of the heliasters in the western Atlantic is consistent with the pattern of many other marine groups in the region which suffered impoverishment following uplift of the Central American isthmus.

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Cerebral Tissue Response in Chronic Electrode Implantation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080547 ◽

1977 ◽

Vol 35 ◽

pp. 624-625

Author(s):

R.F. Dodson ◽

L.W-F Chu ◽

N. Ishihara

Keyword(s):

Tissue Response ◽

Whole Body ◽

Platinum Electrodes ◽

Fixed Tissue ◽

Electrode Implantation ◽

Surface Areas ◽

Tissue Changes ◽

Micron Diameter ◽

Extent Of Damage ◽

Electrode Sheath

The extent of damage surrounding an implanted electrode in the cerebral cortex is a question of significant importance with regard to attaining consistency and validity of physiological recordings. In order to determine the extent of such tissue changes, 150 micron diameter platinum electrodes were implanted in the cortex of four adult baboons, and after eight days the animals were sacrificed by whole body perfusion with a 3% glutaraldehyde in 0.1M phosphate fixative.The calvarium was carefully removed and the electrode tracts were readily discernible in the firm, glutaraldehyde fixed tissue.Careful dissection of the zone of the electrode tract resulted in a small block which was further sectioned into tip, mid-tract and surface areas. Ultrastructurally, damage extended from the electrode sheath to the greatest extent of from 0.2 to 3.5 mm.

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Neutrophil Myeloperoxidase Destruction by Ultraviolet Irradiation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102778 ◽

1988 ◽

Vol 46 ◽

pp. 138-139

Author(s):

J. Hanker ◽

B. Giammara ◽

G. Strauss

Keyword(s):

Uv Radiation ◽

Myeloid Leukemia ◽

Stratospheric Ozone ◽

Psoriasis Patient ◽

Whole Body ◽

Human Neutrophils ◽

Cupric Nitrate ◽

The Earth ◽

Routine Handling ◽

Uvb Phototherapy

Only a fraction of the UV radiation emitted by the sun reaches the earth; most of the UVB (290-320nm) is eliminated by stratospheric ozone. There is increasing concern, however, that man-made chemicals are damaging this ozone layer. Although the effects of UV on DNA or as a carcinogen are widely known, preleukemia and acute myeloid leukemia (AML) have only rarely been reported in psoriasis patients treated with 8-methoxypsoralen and UV (PUVA). It was therefore of interest to study the effects of UV on the myeloperoxidase (MP) activity of human neutrophils. The peroxidase activity of enriched leukocyte preparations on coverslips was shown cytochemically with a diaminobenzidine medium and cupric nitrate intensification.Control samples (Figs. 1,4,5) of human bloods that were not specifically exposed to UV radiation or light except during routine handling were compared with samples which had been exposed in one of several different ways. One preparation (Fig. 2) was from a psoriasis patient who had received whole-body UVB phototherapy repeatedly.

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Adipokines as key players in β cell function and failure

Clinical Science ◽

10.1042/cs20190523 ◽

2019 ◽

Vol 133 (22) ◽

pp. 2317-2327 ◽

Cited By ~ 3

Author(s):

Nicolás Gómez-Banoy ◽

James C. Lo

Keyword(s):

Metabolic Diseases ◽

Cell Function ◽

Whole Body ◽

Pancreatic Β Cell ◽

Β Cell ◽

Cell Axis ◽

Β Cell Function ◽

Prevalence Of Obesity ◽

Specific Factors ◽

Whole Body Metabolism

Abstract The growing prevalence of obesity and its related metabolic diseases, mainly Type 2 diabetes (T2D), has increased the interest in adipose tissue (AT) and its role as a principal metabolic orchestrator. Two decades of research have now shown that ATs act as an endocrine organ, secreting soluble factors termed adipocytokines or adipokines. These adipokines play crucial roles in whole-body metabolism with different mechanisms of action largely dependent on the tissue or cell type they are acting on. The pancreatic β cell, a key regulator of glucose metabolism due to its ability to produce and secrete insulin, has been identified as a target for several adipokines. This review will focus on how adipokines affect pancreatic β cell function and their impact on pancreatic β cell survival in disease contexts such as diabetes. Initially, the “classic” adipokines will be discussed, followed by novel secreted adipocyte-specific factors that show therapeutic promise in regulating the adipose–pancreatic β cell axis.

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Quantifying Vocal Power: Correlation of Whole-Body Anaerobic Power to Vocal Function Measures

Journal of Speech Language and Hearing Research ◽

10.1044/2020_jslhr-20-00110 ◽

2020 ◽

Vol 63 (8) ◽

pp. 2597-2608

Author(s):

Emily N. Snell ◽

Laura W. Plexico ◽

Aurora J. Weaver ◽

Mary J. Sandage

Keyword(s):

Fundamental Frequency ◽

Forced Vital Capacity ◽

Vital Capacity ◽

Anaerobic Power ◽

Performance Outcomes ◽

Sound Level ◽

Whole Body ◽

Vocal Function ◽

Laryngeal Diadochokinesis ◽

High Sound

Purpose The purpose of this preliminary study was to identify a vocal task that could be used as a clinical indicator of the vocal aptitude or vocal fitness required for vocally demanding occupations in a manner similar to that of the anaerobic power tests commonly used in exercise science. Performance outcomes for vocal tasks that require rapid acceleration and high force production may be useful as an indirect indicator of muscle fiber complement and bioenergetic fitness of the larynx, an organ that is difficult to study directly. Method Sixteen women (age range: 19–24 years, M age = 22 years) were consented for participation and completed the following performance measures: forced vital capacity, three adapted vocal function tasks, and the horizontal sprint test. Results Using a within-participant correlational analyses, results indicated a positive relationship between the rate of the last second of a laryngeal diadochokinesis task that was produced at a high fundamental frequency/high sound level and anaerobic power. Forced vital capacity was not correlated with any of the vocal function tasks. Conclusions These preliminary results indicate that aspects of the laryngeal diadochokinesis task produced at a high fundamental frequency and high sound level may be useful as an ecologically valid measure of vocal power ability. Quantification of vocal power ability may be useful as a vocal fitness assessment or as an outcome measure for voice rehabilitation and habilitation for patients with vocally demanding jobs.

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Clinical Update: Functional Capacity Evaluations and Disability

Guides Newsletter ◽

10.1001/amaguidesnewsletters.1998.marapr02 ◽

1998 ◽

Vol 3 (2) ◽

pp. 4-5

Author(s):

Glenn Pransky

Keyword(s):

Direct Observation ◽

Functional Capacity ◽

Work Capacity ◽

Functional Capacity Evaluation ◽

Whole Body ◽

Validity Of Results ◽

Job Tasks ◽

Capacity Evaluation ◽

Physical Abilities ◽

The Relationship

Abstract According to the AMA Guides to the Evaluation of Permanent Impairment, a functional capacity evaluation (FCE) measures an individual's physical abilities via a set of activities in a structured setting and provides objective data about the relationship between an impairment and maximal ability to perform work activities. A key distinction between FCEs and self-reported activities of daily living is that the former involve direct observation by professional evaluators. Numerous devices can quantify the physical function of a specific part of the musculoskeletal system but do not address the performance of whole body tasks in the workplace, and these devices have not been shown to predict accurately the ability to perform all but the simplest job tasks. Information about reliability has been proposed as a way to identify magnification and malingering, but variability due to pain and poor comprehension of instructions may cause variations in assessments. Structured work capacity evaluations involve a set of activities but likely underestimate the individual's ability to do jobs that involve complex or varying activities. Job simulations involve direct observation of an individual performing actual job tasks, require a skilled and experienced evaluator, and raise questions about expense, time, objectivity and validity of results, and interpretation of results in terms of the ability to perform specific jobs. To understand the barriers to return to work, examiners must supplement FCEs with information regarding workplace environment, accommodations, and demotivators.

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