scholarly journals A three-dimensional musculoskeletal model of the dog

2020 ◽  
Author(s):  
Heiko Stark ◽  
Martin S. Fischer ◽  
Alexander Hunt ◽  
Fletcher Young ◽  
Roger Quinn ◽  
...  
Keyword(s):  
Experimental Data ◽  
Body Size ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Musculoskeletal Model ◽  
Muscle Synergy ◽  
Locomotor System ◽  
Wide Range ◽  
Joint Load

AbstractDogs are an interesting object of investigation because of the wide range of body size, body mass, and physique. In the last several years, the number of clinical and biomechanical studies on dog locomotion has increased. However, the relationship between body structure and joint load during locomotion, as well as between joint load and degenerative diseases of the locomotor system (e.g. dysplasia), are not sufficiently understood. In vivo measurements/records of joint forces and loads or deep/small muscles are complex, invasive, and sometimes ethically questionable. The use of detailed musculoskeletal models may help in filling that knowledge gap. We describe here the methods we used to create a detailed musculoskeletal model with 84 degrees of freedom and 134 muscles. Our model has three key-features: Three-dimensionality, scalability, and modularity. We tested the validity of the model by identifying forelimb muscle synergies of a beagle at walk. We used inverse dynamics and static optimization to estimate muscle activations based on experimental data. We identified three muscle synergy groups by using hierarchical clustering. Predicted activation patterns exhibited good agreement with experimental data for most of the forelimb muscles. We expect that our model will speed up the analysis of how body size, physique, agility, and disease influence joint neuronal control and loading in dog locomotion.

scholarly journals A three-dimensional musculoskeletal model of the dog

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Heiko Stark ◽  
Martin S. Fischer ◽  
Alexander Hunt ◽  
Fletcher Young ◽  
Roger Quinn ◽  
...  
Keyword(s):  
Experimental Data ◽  
Body Size ◽  
Inverse Dynamics ◽  
Musculoskeletal Model ◽  
Muscle Synergy ◽  
Domestic Dog ◽  
Locomotor System ◽  
Wide Range ◽  
Joint Load

AbstractThe domestic dog is interesting to investigate because of the wide range of body size, body mass, and physique in the many breeds. In the last several years, the number of clinical and biomechanical studies on dog locomotion has increased. However, the relationship between body structure and joint load during locomotion, as well as between joint load and degenerative diseases of the locomotor system (e.g. dysplasia), are not sufficiently understood. Collecting this data through in vivo measurements/records of joint forces and loads on deep/small muscles is complex, invasive, and sometimes unethical. The use of detailed musculoskeletal models may help fill the knowledge gap. We describe here the methods we used to create a detailed musculoskeletal model with 84 degrees of freedom and 134 muscles. Our model has three key-features: three-dimensionality, scalability, and modularity. We tested the validity of the model by identifying forelimb muscle synergies of a walking Beagle. We used inverse dynamics and static optimization to estimate muscle activations based on experimental data. We identified three muscle synergy groups by using hierarchical clustering. The activation patterns predicted from the model exhibit good agreement with experimental data for most of the forelimb muscles. We expect that our model will speed up the analysis of how body size, physique, agility, and disease influence neuronal control and joint loading in dog locomotion.

Three-dimensional asymmetric maximum weight lifting prediction considering dynamic joint strength

2021 ◽  
pp. 095441192098703
Author(s):  
Rahid Zaman ◽  
Yujiang Xiang ◽  
Jazmin Cruz ◽  
James Yang
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Three Dimensional ◽  
Optimization Method ◽  
Weight Lifting ◽  
Joint Torque ◽  
Maximum Weight ◽  
Angular Velocities ◽  
Asymmetric Lifting

In this study, the three-dimensional (3D) asymmetric maximum weight lifting is predicted using an inverse-dynamics-based optimization method considering dynamic joint torque limits. The dynamic joint torque limits are functions of joint angles and angular velocities, and imposed on the hip, knee, ankle, wrist, elbow, shoulder, and lumbar spine joints. The 3D model has 40 degrees of freedom (DOFs) including 34 physical revolute joints and 6 global joints. A multi-objective optimization (MOO) problem is solved by simultaneously maximizing box weight and minimizing the sum of joint torque squares. A total of 12 male subjects were recruited to conduct maximum weight box lifting using squat-lifting strategy. Finally, the predicted lifting motion, ground reaction forces, and maximum lifting weight are validated with the experimental data. The prediction results agree well with the experimental data and the model’s predictive capability is demonstrated. This is the first study that uses MOO to predict maximum lifting weight and 3D asymmetric lifting motion while considering dynamic joint torque limits. The proposed method has the potential to prevent individuals’ risk of injury for lifting.

scholarly journals Electro-osmotic flow enhancement in carbon nanotube membranes

2016 ◽  
Vol 374 (2060) ◽  
pp. 20150268 ◽  
Author(s):  
Davide Mattia ◽  
Hannah Leese ◽  
Francesco Calabrò
Keyword(s):  
Experimental Data ◽  
Carbon Nanotube ◽  
Osmotic Flow ◽  
Nanotube Membranes ◽  
Wide Range ◽  
Simplifying Assumptions ◽  
Carbon Nanotube Membranes ◽  
Simplified Solution ◽  
Electro Osmotic Flow

In this work, experimental evidence of the presence of electro-osmotic flow (EOF) in carbon nanotube membranes with diameters close to or in the region of electrical double layer overlap is presented for two different electrolytes for the first time. No EOF in this region should be present according to the simplified theoretical framework commonly used for EOF in micrometre-sized channels. The simplifying assumptions concern primarily the electrolyte charge density structure, based on the Poisson–Boltzmann (P-B) equation. Here, a numerical analysis of the solutions for the simplified case and for the nonlinear and the linearized P-B equations is compared with experimental data. Results show that the simplified solution produces a significant deviation from experimental data, whereas the linearized solution of the P-B equation can be adopted with little error compared with the full P-B case. This work opens the way to using electro-osmotic pumping in a wide range of applications, from membrane-based ultrafiltration and nanofiltration (as a more efficient alternative to mechanical pumping at the nanoscale) to further miniaturization of lab-on-a-chip devices at the nanoscale for in vivo implantation.

A Four-DOF Laparo-Endoscopic Single Site Platform for Rapidly-Developing Next-Generation Surgical Robotics

2016 ◽  
Vol 01 (04) ◽  
pp. 1650006 ◽  
Author(s):  
Lou Cubrich ◽  
Mark A. Reichenbach ◽  
Jay D. Carlson ◽  
Andrew Pracht ◽  
Benjamin Terry ◽  
...  
Keyword(s):  
Surgical Procedures ◽  
Degrees Of Freedom ◽  
Haptic Feedback ◽  
Gynecologic Oncology ◽  
Single Site ◽  
Fundamental Limitations ◽  
Surgical Tool ◽  
Wide Range ◽  
Proven Efficacy

Minimally-invasive laparoscopic procedures have proven efficacy for a wide range of surgical procedures, but have notable shortcomings, including limited instrument motion and reduced dexterity. Endoscopic robots, like the intuitive surgical da Vinci system, have become an effective tool for many types of surgeries; however, these tools still have fundamental limitations with manipulator access, which reduces their effectiveness for many surgical procedures, like colectomy, cholecystectomy, and gynecologic oncology. Laparo-endoscopic single-site (LESS) robots operate in vivo, and overcome many of these limitations. Here, a four-degrees of freedom (DOF) surgical robot is presented as a tool to enable refinement of the LESS platform as a surgical tool, while also looking forward to applications in telesurgery and haptic feedback.

scholarly journals Implicit water model within the Zimm-Bragg approach to analyze experimental data for heat and cold denaturation of proteins

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Artem Badasyan ◽  
Shushanik Tonoyan ◽  
Matjaz Valant ◽  
Joze Grdadolnik
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Hamiltonian Formulation ◽  
Theoretical Models ◽  
Water Model ◽  
Explicit Model ◽  
Significant Progress ◽  
Cold Denaturation ◽  
Denaturation Of Proteins

AbstractStudies of biopolymer conformations essentially rely on theoretical models that are routinely used to process and analyze experimental data. While modern experiments allow study of single molecules in vivo, corresponding theories date back to the early 1950s and require an essential update to include the recent significant progress in the description of water. The Hamiltonian formulation of the Zimm-Bragg model we propose includes a simplified, yet explicit model of water-polypeptide interactions that transforms into the equivalent implicit description after performing the summation of solvent degrees of freedom in the partition function. Here we show that our model fits very well to the circular dichroism experimental data for both heat and cold denaturation and provides the energies of inter- and intra-molecular H-bonds, unavailable with other processing methods. The revealed delicate balance between these energies determines the conditions for the existence of cold denaturation and thus clarifies its absence in some proteins.

An Electromyographically Driven Cervical Spine Model in OpenSim

2021 ◽  
pp. 1-13
Author(s):  
Jeff M. Barrett ◽  
Colin D. McKinnon ◽  
Clark R. Dickerson ◽  
Jack P. Callaghan
Keyword(s):  
Cervical Spine ◽  
Potential Energy ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Published Data ◽  
Upper Cervical Spine ◽  
Biomechanical Models ◽  
Upper Cervical ◽  
Spine Model

Relatively few biomechanical models exist aimed at quantifying the mechanical risk factors associated with neck pain. In addition, there is a need to validate spinal-rhythm techniques for inverse dynamics spine models. Therefore, the present investigation was 3-fold: (1) the development of a cervical spine model in OpenSim, (2) a test of a novel spinal-rhythm technique based on minimizing the potential energy in the passive tissues, and (3) comparison of an electromyographically driven approach to estimating compression and shear to other cervical spine models. The authors developed ligament force–deflection and intervertebral joint moment–angle curves from published data. The 218 Hill-type muscle elements, representing 58 muscles, were included and their passive forces validated against in vivo data. Our novel spinal-rhythm technique, based on minimizing the potential energy in the passive tissues, disproportionately assigned motion to the upper cervical spine that was not physiological. Finally, using kinematics and electromyography collected from 8 healthy male volunteers, the authors calculated the compression at C7–T1 as a function of the head–trunk Euler angles. Differences from other models varied from 25.5 to 368.1 N. These differences in forces may result in differences in model geometry, passive components, number of degrees of freedom, or objective functions.

scholarly journals Muscle short-range stiffness can be used to estimate the endpoint stiffness of the human arm

2011 ◽  
Vol 105 (4) ◽  
pp. 1633-1641 ◽  
Author(s):  
Xiao Hu ◽  
Wendy M. Murray ◽  
Eric J. Perreault
Keyword(s):  
Experimental Data ◽  
Short Range ◽  
Muscle Activation ◽  
Three Dimensional ◽  
Musculoskeletal Model ◽  
Muscle Stiffness ◽  
Muscle Properties ◽  
Human Arm ◽  
Wide Range ◽  
Endpoint Stiffness

The mechanical properties of the human arm are regulated to maintain stability across many tasks. The static mechanics of the arm can be characterized by estimates of endpoint stiffness, considered especially relevant for the maintenance of posture. At a fixed posture, endpoint stiffness can be regulated by changes in muscle activation, but which activation-dependent muscle properties contribute to this global measure of limb mechanics remains unclear. We evaluated the role of muscle properties in the regulation of endpoint stiffness by incorporating scalable models of muscle stiffness into a three-dimensional musculoskeletal model of the human arm. Two classes of muscle models were tested: one characterizing short-range stiffness and two estimating stiffness from the slope of the force-length curve. All models were compared with previously collected experimental data describing how endpoint stiffness varies with changes in voluntary force. Importantly, muscle properties were not fit to the experimental data but scaled only by the geometry of individual muscles in the model. We found that force-dependent variations in endpoint stiffness were accurately described by the short-range stiffness of active arm muscles. Over the wide range of evaluated arm postures and voluntary forces, the musculoskeletal model incorporating short-range stiffness accounted for 98 ± 2, 91 ± 4, and 82 ± 12% of the variance in stiffness orientation, shape, and area, respectively, across all simulated subjects. In contrast, estimates based on muscle force-length curves were less accurate in all measures, especially stiffness area. These results suggest that muscle short-range stiffness is a major contributor to endpoint stiffness of the human arm. Furthermore, the developed model provides an important tool for assessing how the nervous system may regulate endpoint stiffness via changes in muscle activation.

Simulating Instrumented Knee Implant Forces With a Simplified Computational Model

2013 ◽  
Author(s):  
Jacobus H. Müller
Keyword(s):  
Computational Model ◽  
Inverse Analysis ◽  
Inverse Dynamics ◽  
Musculoskeletal Model ◽  
Grand Challenge ◽  
Dynamics Analysis ◽  
Muscle Dynamics ◽  
Target Values ◽  
Inverse Dynamics Analysis

A simplified computational model is presented with which axial knee implant forces can be estimated. The dataset provided in the IV Grand Challenge to Predict in-vivo Knee Loads [1] is used to assemble a musculoskeletal model, and perform an inverse dynamics analysis. The joint and muscle dynamics recorded during the inverse analysis is then used as target values during a forward dynamics analysis to compute the axial tibiofemoral load.

Respiratory pigments: interactions between oxygen and carbon dioxide transport

1989 ◽  
Vol 67 (12) ◽  
pp. 2971-2985 ◽  
Author(s):  
C. R. Bridges ◽  
S. Morris
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Venous Blood ◽  
Oxygen Affinity ◽  
Specific Effect ◽  
Carbon Dioxide Transport ◽  
Wide Range ◽  
Lower Vertebrates ◽  
Haldane Effect

Oxygen and carbon dioxide are transported in vertebrates and invertebrates by a wide range of respiratory pigments. These respiratory gases are not transported independently of one another, and this review considers the influence of carbon dioxide on oxygen transport and vice versa. A specific effect of carbon dioxide or bicarbonate, decreasing oxygen affinity, is found in many haemoglobins, but the effect is often reduced in the presence of organic phosphates. Clear experimental data are available for mammalian haemoglobins but in birds and lower vertebrates more data are required to verify the presence and magnitude of the CO2 effect. In erythrocruorins and haemocyanins CO2 increases O2 affinity, whereas in haemerythrins, as in haemoglobin, CO2 again decreases oxygen affinity. Much of our knowledge of invertebrate respiratory pigments is based, however, on data from one or two species. A specific effect of CO2 on O2 affinity has also often been found only at high CO2 partial pressures, which may be outside the physiological range for these species. More in vivo experimental data on CO2 values are required for these species, and further studies on other species may help to explain this discrepancy. The interaction of O2 and CO2 transport is mainly through the Haldane effect, i.e., deoxygenated blood having a greater capacity for CO2 than oxygenated blood. This is due directly to the formation of carbamino groups (carbamate) and also to the fact that deoxygenated blood binds relatively more protons than oxygenated blood. This forms the basis for the linkage between the Bohr and Haldane effects. In some species in which the Bohr coefficient is below −1.0, an akalosis in the tissues may be induced. Large Haldane effects may be particularly effective in promoting CO2 unloading when the partial pressure difference of CO2 between arterial and venous blood is small. Carbamate formation may account for 10–20% of the CO2 transported in mammals, but its role in lower vertebrates and invertebrates has only recently been considered. Carbon dioxide transport is modulated by those factors that influence O2 affinity as these in turn influence the Haldane effect.

Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

1991 ◽  
Vol 30 (01) ◽  
pp. 35-39 ◽  
Author(s):  
H. S. Durak ◽  
M. Kitapgi ◽  
B. E. Caner ◽  
R. Senekowitsch ◽  
M. T. Ercan
Keyword(s):  
Soft Tissue ◽  
Room Temperature ◽  
Normal Subjects ◽  
Left Testis ◽  
Wide Range ◽  
Activity Ratios ◽  
The Right ◽  
Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

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