A biomechanical model of feeding kinematics forDunkleosteus terrelli(Arthrodira, Placodermi)

Paleobiology ◽  
2009 ◽  
Vol 35 (2) ◽  
pp. 251-269 ◽  
Author(s):  
Philip S. L. Anderson ◽  
Mark W. Westneat
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Biomechanical Model ◽  
Bite Force ◽  
Rapid Expansion ◽  
Morphological Data ◽  
Large Individual ◽  
Linkage Mechanism ◽  
Cross Sectional ◽  
Biomechanical Models

Biomechanical models illustrate how the principles of physics and physiology determine function in organisms, allowing ecological inferences and functional predictions to be based on morphology. Dynamic lever and linkage models of the mechanisms of the jaw and skull during feeding in fishes predict function from morphology and have been used to compare the feeding biomechanics of diverse fish groups, including fossil taxa, and to test ideas in ecological morphology. Here we perform detailed computational modeling of the four-bar linkage mechanism in the skull and jaw systems ofDunkleosteus terrelli, using software that accepts landmark morphological data to simulate the movements and mechanics of the skull and jaws during prey capture. The linkage system is based on the quadrate and cranio-thoracic joints: Cranial elevation around the cranio-thoracic joint forces the quadrate joint forward, which, coupled with a jaw depressor muscle connecting the jaw to the thoracic shield, causes the jaw to rotate downward during skull expansion. Results show a high speed transmission for jaw opening, producing a rapid expansion phase similar to that in modern fishes that use suction during prey capture. During jaw closing, the model computes jaw and skull rotation and a series of mechanical metrics including effective mechanical advantage of the jaw lever and kinematic transmission of the skull linkage system. Estimates of muscle cross-sectional area based on the largest of five specimens analyzed allow the bite force and strike speed to be estimated. Jaw-closing muscles ofDunkleosteuspowered an extraordinarily strong bite, with an estimated maximal bite force of over 6000 N at the jaw tip and more than 7400 N at the rear dental plates, for a large individual (10 m total length). This bite force capability is among the most powerful bites in animals. The combination of rapid gape expansion and powerful bite meant thatDunkleosteus terrellicould both catch elusive prey and penetrate protective armor, allowing this apex predator to potentially eat anything in its ecosystem, including other placoderms.

scholarly journals Feeding mechanics and bite force modelling of the skull of Dunkleosteus terrelli , an ancient apex predator

2006 ◽  
Vol 3 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Philip S.L Anderson ◽  
Mark W Westneat
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Mouth Opening ◽  
Biomechanical Model ◽  
Bite Force ◽  
Rapid Expansion ◽  
Large Individual ◽  
Linkage Mechanism ◽  
Feeding Mechanics ◽  
Four Bar Linkage

Placoderms are a diverse group of armoured fishes that dominated the aquatic ecosystems of the Devonian Period, 415–360 million years ago. The bladed jaws of predators such as Dunkleosteus suggest that these animals were the first vertebrates to use rapid mouth opening and a powerful bite to capture and fragment evasive prey items prior to ingestion. Here, we develop a biomechanical model of force and motion during feeding in Dunkleosteus terrelli that reveals a highly kinetic skull driven by a unique four-bar linkage mechanism. The linkage system has a high-speed transmission for jaw opening, producing a rapid expansion phase similar to modern fishes that use suction during prey capture. Jaw closing muscles power an extraordinarily strong bite, with an estimated maximal bite force of over 4400 N at the jaw tip and more than 5300 N at the rear dental plates, for a large individual (6 m in total length). This bite force capability is the greatest of all living or fossil fishes and is among the most powerful bites in animals.

Evolution of hindlimb posture in nonmammalian therapsids: biomechanical tests of paleontological hypotheses

Paleobiology ◽  
2001 ◽  
Vol 27 (1) ◽  
pp. 14-38 ◽  
Author(s):  
Richard W. Blob
Keyword(s):  
Experimental Data ◽  
Biomechanical Model ◽  
Axial Rotation ◽  
Morphological Data ◽  
Upright Posture ◽  
Cross Sectional ◽  
Model Calculations ◽  
Limb Bones ◽  
Plausible Model ◽  
Bending Stresses

Analyses of limb joint morphology in nonmammalian therapsid “mammal-like reptiles” have suggested that among many lineages, individual animals were capable of shifting between sprawling and upright hindlimb postures, much like modern crocodilians. The ability to use multiple limb postures thus might have been ancestral to the generally more upright posture that evolved during the transition from “mammal-like reptiles” to mammals. Here I derive a biomechanical model to test this hypothesis through calculations of expected posture-related changes in femoral stress for therapsid taxa using different limb postures. The model incorporates morphological data from fossil specimens and experimental data from force platform experiments on iguanas and alligators.Experimental data suggest that the evolutionary transition from sprawling to nonsprawling posture was accompanied by a change in the predominant loading regime of the limb bones, from torsion to bending. Changes in the cross-sectional morphology of the hindlimb bones between sphenacodontid “pelycosaurs” and gorgonopsid therapsids are consistent with the hypothesis that bending loads increased in importance early in therapsid evolution; thus, bending stresses are an appropriate model for the maximal loads experienced by the limb bones of theriodont therapsids. Results from the model used to estimate stresses in these taxa do not refute the use of both sprawling and more upright stance among basal theriodont therapsids. Thus, the hypothesis that the use of multiple postures was ancestral to the more upright posture typical of most mammals is biomechanically plausible. Model calculations also indicate that the axial rotation of the femur typical in sprawling locomotion can reduce peak bending stresses. Therefore, as experimental data from alligators and iguanas suggest, the evolution of nonsprawling limb posture and kinematics in therapsids might have been accompanied by increased limb bone bending stress.

scholarly journals IMPROVING THE DESIGN OF THERMAL TOOLS FOR ROCK FRACTURING

2021 ◽  
Vol 117 (2) ◽  
pp. 13-20
Author(s):  
Vitaly Povetkin ◽  
Alfiya Nurmukhanova ◽  
Amina Bukayeva ◽  
Zhannur Begendikova
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Mining Industry ◽  
Fuel Mixture ◽  
Rapid Expansion ◽  
Critical Cross Section ◽  
Rock Fracturing ◽  
Cross Sectional ◽  
Rock Destruction ◽  
Cylindrical Nozzle

The article deals with the main parameters of the thermodynamic working device for rock destruction due to the implementation of a new method of fuel mixture combustion in shock waves initiated by a high-speed torch burner in gas-dynamic combustion intensifiers. A device for thermal destruction of rocks has been developed, which belongs to the mining industry and can be used for directed impact on rocks when they are destroyed by hot gas jets in mining, stone processing and construction industries. Also, installed coaxial to the nozzle, with increasing inside diameter, a cylindrical nozzle, with two cascades of ejection holes - the first cascade is made at a distance from the Laval nozzle, equal to the distance to complete expansion of the jet of the torch, then, the accelerating section of the nozzle and the new, formed by burning the unburned fuel, jet of the burner. It is found that the cross sectional area of the inner hole of the cylindrical nozzle, is made with an excess of the area of the critical cross section of the nozzle Laval burner 2.5-3 times, in which, because of the rapid expansion of the gas flow in the nozzle, there is turbulization, with the formation of a powerful zone of heating of the gas flow and the appearance of a standing detonation wave in it. The drilling angle of the ejection holes of the first stage is 45-50º to the axis of the nozzle, which serves for ejection of atmospheric air, the oxygen of which reacts with the surplus of combustible in the main jet of the burner and the formation of a more powerful jet.

scholarly journals Feeding Kinematics And Morphology Of The Alligator Gar (Atractosteus Spatula, Lacépède, 1803): Feeding Mechanics Of Atractosteus Spatula

2019 ◽  
Author(s):  
Justin B. Lemberg ◽  
Neil H. Shubin ◽  
Mark W. Westneat
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Sister Group ◽  
Rapid Expansion ◽  
Feeding System ◽  
Primary Input ◽  
Feeding Mechanism ◽  
Alligator Gar ◽  
Feeding Kinematics ◽  
Atractosteus Spatula

ABSTRACTModern (lepisosteid) gars are a small clade of seven species and two genera that occupy an important position on the actinopterygian phylogenetic tree as members of the Holostei (Amia + gars), sister-group of the teleost radiation. Often referred to as “living fossils,” these taxa preserve many plesiomorphic characteristics used to interpret and reconstruct early osteichthyan feeding conditions. Less attention, however, has been paid to the functional implications of gar-specific morphology, thought to be related to an exclusively ram-based, lateral-snapping mode of prey capture. Previous studies of feeding kinematics in gars have focused solely on members of the narrow-snouted Lepisosteus genus, and here we expand that dataset to include a member of the broad-snouted sister-genus and largest species of gar, the alligator gar (Atractosteus spatula, Lacépède, 1803). High-speed videography reveals that the feeding system of alligator gars is capable of rapid expansion from anterior-to-posterior, precisely timed in a way that appears to counteract the effects of a bow-wave during ram-feeding and generate a unidirectional flow of water through the feeding system. Reconstructed cranial anatomy based on contrast-enhanced micro-CT data show that a lateral-sliding palatoquadrate, flexible intrasuspensorial joint, pivoting interhyal, and retractable pectoral girdle are all responsible for increasing the range of motion and expansive capabilities of the gar cranial linkage system. Muscular reconstructions and manipulation experiments show that, while the sternohyoideus is the primary input to the feeding system (similar to other “basal” actinopterygians), additional input from the hyoid constrictors and hypaxials play an important role in decoupling and modulating between the dual roles of the sternohyoideus: hyoid retraction (jaw opening) and hyoid rotation (pharyngeal expansion) respectively. The data presented here demonstrate an intricate feeding mechanism, capable of precise control with plesiomorphic muscles, that represents one of the many ways the ancestral osteichthyan feeding mechanism has been modified for prey capture.RESEARCH HIGHLIGHTSAlligator gars use a surprisingly expansive cranial linkage system for prey capture that relies on specialized joints for increased mobility and is capable of precise modulation from anterior to posterior using plesiomorphic osteichthyan musculature.

scholarly journals Extremely fast feeding strikes are powered by elastic recoil in a seahorse relative, the snipefish, Macroramphosus scolopax

2018 ◽  
Vol 285 (1882) ◽  
pp. 20181078 ◽  
Author(s):  
Sarah J. Longo ◽  
Tyler Goodearly ◽  
Peter C. Wainwright
Keyword(s):  
High Speed ◽  
High Performance ◽  
Muscle Power ◽  
Prey Capture ◽  
Head Rotation ◽  
Specific Power ◽  
Elastic Recoil ◽  
Linkage Mechanism ◽  
Power Requirement ◽  
Feeding Mechanism

Among over 30 000 species of ray-finned fishes, seahorses and pipefishes have a unique feeding mechanism whereby the elastic recoil of tendons allows them to rotate their long snouts extremely rapidly in order to capture small elusive prey. To understand the evolutionary origins of this feeding mechanism, its phylogenetic distribution among closely related lineages must be assessed. We present evidence for elastic recoil-powered feeding in snipefish ( Macroramphosus scolopax ) from kinematics, dynamics and morphology. High-speed videos of strikes show they achieve extremely fast head and hyoid rotational velocities, resulting in rapid prey capture in as short a duration as 2 ms. The maximum instantaneous muscle-mass-specific power requirement for head rotation in snipefish was above the known vertebrate maximum, which is evidence that strikes are not the result of direct muscle power. Finally, we show that the over-centre conformation of the four-bar linkage mechanism coupling head elevation to hyoid rotation in snipefish can function as a torque reversal latch, preventing the head from rotating and providing the opportunity for elastic energy storage. The presence of elastic recoil feeding in snipefish means that this high-performance mechanism is not restricted to the Syngnathidae (seahorses and pipefish) and may have evolved in parallel.

scholarly journals Observation and analysis of diving beetle movements while swimming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Debo Qi ◽  
Chengchun Zhang ◽  
Jingwei He ◽  
Yongli Yue ◽  
Jing Wang ◽  
...  
Keyword(s):  
Swimming Speed ◽  
High Speed ◽  
Kinematic Model ◽  
Movement Pattern ◽  
Unmanned Vehicles ◽  
Power Stroke ◽  
Cross Sectional ◽  
Motion Data ◽  
The Cross ◽  
Diving Beetle

AbstractThe fast swimming speed, flexible cornering, and high propulsion efficiency of diving beetles are primarily achieved by their two powerful hind legs. Unlike other aquatic organisms, such as turtle, jellyfish, fish and frog et al., the diving beetle could complete retreating motion without turning around, and the turning radius is small for this kind of propulsion mode. However, most bionic vehicles have not contained these advantages, the study about this propulsion method is useful for the design of bionic robots. In this paper, the swimming videos of the diving beetle, including forwarding, turning and retreating, were captured by two synchronized high-speed cameras, and were analyzed via SIMI Motion. The analysis results revealed that the swimming speed initially increased quickly to a maximum at 60% of the power stroke, and then decreased. During the power stroke, the diving beetle stretched its tibias and tarsi, the bristles on both sides of which were shaped like paddles, to maximize the cross-sectional areas against the water to achieve the maximum thrust. During the recovery stroke, the diving beetle rotated its tarsi and folded the bristles to minimize the cross-sectional areas to reduce the drag force. For one turning motion (turn right about 90 degrees), it takes only one motion cycle for the diving beetle to complete it. During the retreating motion, the average acceleration was close to 9.8 m/s2 in the first 25 ms. Finally, based on the diving beetle's hind-leg movement pattern, a kinematic model was constructed, and according to this model and the motion data of the joint angles, the motion trajectories of the hind legs were obtained by using MATLAB. Since the advantages of this propulsion method, it may become a new bionic propulsion method, and the motion data and kinematic model of the hind legs will be helpful in the design of bionic underwater unmanned vehicles.

scholarly journals Energetic-Materials-Driven Synthesis of Graphene-Encapsulated Tin Oxide Nanoparticles for Sodium-Ion Batteries

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2550
Author(s):  
Yingchun Wang ◽  
Jinxu Liu ◽  
Min Yang ◽  
Lijuan Hou ◽  
Tingting Xu ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Energetic Materials ◽  
High Speed ◽  
Coulombic Efficiency ◽  
Sno2 Nanoparticles ◽  
Direct Synthesis ◽  
Exothermic Reaction ◽  
Rate Capability ◽  
Rapid Expansion ◽  
Core Shell

By evenly mixing polytetrafluoroethylene-silicon energetic materials (PTFE-Si EMs) with tin oxide (SnO2) particles, we demonstrate a direct synthesis of graphene-encapsulated SnO2 (Gr-SnO2) nanoparticles through the self-propagated exothermic reaction of the EMs. The highly exothermic reaction of the PTFE-Si EMs released a huge amount of heat that induced an instantaneous temperature rise at the reaction zone, and the rapid expansion of the gaseous SiF4 product provided a high-speed gas flow for dispersing the molten particles into finer nanoscale particles. Furthermore, the reaction of the PTFE-NPs with Si resulted in a simultaneous synthesis of graphene that encapsulated the SnO2 nanoparticles in order to form the core-shell nanostructure. As sodium storage material, the graphene-encapsulated SnO2 nanoparticles exhibit a good cycling performance, superior rate capability, and a high initial Coulombic efficiency of 85.3%. This proves the effectiveness of our approach for the scalable synthesis of core-shell-structured graphene-encapsulated nanomaterials.

scholarly journals Prey Capturing Dynamics and Nanomechanically Graded Cutting Apparatus of Dragonfly Nymph

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 559
Author(s):  
Lakshminath Kundanati ◽  
Prashant Das ◽  
Nicola M. Pugno
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Speed ◽  
Prey Capture ◽  
High Speed Photography ◽  
Sensory Organs ◽  
Dragonfly Nymph ◽  
Drag Forces ◽  
Predatory Insects ◽  
Dragonfly Nymphs

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey and it presents challenges in terms of movements due to drag forces. Dragonfly nymphs are known to be voracious predators with structures and movements that are yet to be fully understood. Thus, we examine two main mouthparts of the dragonfly nymph (Libellulidae: Insecta: Odonata) that are used in prey capturing and cutting the prey. To observe and analyze the preying mechanism under water, we used high-speed photography and, electron microscopy. The morphological details suggest that the prey-capturing labium is a complex grasping mechanism with additional sensory organs that serve some functionality. The time taken for the protraction and retraction of labium during prey capture was estimated to be 187 ± 54 ms, suggesting that these nymphs have a rapid prey mechanism. The Young’s modulus and hardness of the mandibles were estimated to be 9.1 ± 1.9 GPa and 0.85 ± 0.13 GPa, respectively. Such mechanical properties of the mandibles make them hard tools that can cut into the exoskeleton of the prey and also resistant to wear. Thus, studying such mechanisms with their sensory capabilities provides a unique opportunity to design and develop bioinspired underwater deployable mechanisms.

scholarly journals Reduced biomechanical models for precision-cut lung-slice stretching experiments

2021 ◽  
Vol 82 (5) ◽  
Author(s):  
Hannah J. Pybus ◽  
Amanda L. Tatler ◽  
Lowell T. Edgar ◽  
Reuben D. O’Dea ◽  
Bindi S. Brook
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Ex Vivo ◽  
Finite Thickness ◽  
Biomechanical Model ◽  
Local Stress ◽  
Smooth Muscle Contraction ◽  
Biomechanical Models ◽  
Cytokine Activation ◽  
Asymptotic Reduction

AbstractPrecision-cut lung-slices (PCLS), in which viable airways embedded within lung parenchyma are stretched or induced to contract, are a widely used ex vivo assay to investigate bronchoconstriction and, more recently, mechanical activation of pro-remodelling cytokines in asthmatic airways. We develop a nonlinear fibre-reinforced biomechanical model accounting for smooth muscle contraction and extracellular matrix strain-stiffening. Through numerical simulation, we describe the stresses and contractile responses of an airway within a PCLS of finite thickness, exposing the importance of smooth muscle contraction on the local stress state within the airway. We then consider two simplifying limits of the model (a membrane representation and an asymptotic reduction in the thin-PCLS-limit), that permit analytical progress. Comparison against numerical solution of the full problem shows that the asymptotic reduction successfully captures the key elements of the full model behaviour. The more tractable reduced model that we develop is suitable to be employed in investigations to elucidate the time-dependent feedback mechanisms linking airway mechanics and cytokine activation in asthma.

scholarly journals Changing Sources of Stigma against Patients with HIV/AIDS in the Rapid Expansion of Antiretroviral Treatment Services in Vietnam

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Bach Xuan Tran ◽  
Phung Quoc Tat Than ◽  
Tung Thanh Tran ◽  
Cuong Tat Nguyen ◽  
Carl A. Latkin
Keyword(s):  
Healthcare Setting ◽  
Health Care Facilities ◽  
Rapid Expansion ◽  
People Living With Hiv ◽  
Health Administration ◽  
Continuous Training ◽  
Cross Sectional ◽  
Healthcare Facilities ◽  
Culturally Tailored ◽  
Hiv Aids

Stigmatization against HIV/AIDS greatly hinders efforts to increase the accessibility and utilization of HIV/AIDS services to meet the 90-90-90 goal. This study assessed the stigmatization and discrimination experienced by people living with HIV (PLWH) across multiple social settings such as family, community, and healthcare facilities in Vietnam. A total of 1,016 patients (63.8% males, mean age = 35.4) participated in a cross-sectional study using a culturally tailored HIV stigma measure in three HIV-epidemic-concentrated cities in Vietnam. Zero-inflated Poisson models were used to examine factors associated with the number of types of stigma that patients experienced. 86.2% PLWH reported experiencing stigma against HIV/AIDS, more frequently from their community (62.8%) and family (30.2%) than from health care facilities (8%). The level of stigma from community reported by PLWH is associated with socioeconomic status (e.g., income, occupation). The poor and middle economic classes and unemployed patients reported more stigmatization and discrimination from the community. Across all settings, PLWH experienced fewer stigmatization over the course of ART indicating the benefits of rapidly expanded ART programs. PLWH reported more stigmatization and discrimination at the provincial level of the health administration. Those with the history of drug injection reported significantly less stigmatization from healthcare setting. More culturally tailored interventions to reduce stigmatization overall to improve the quality of life and health outcomes of PLWH should be warranted to achieve the 90-90-90 goal. Improving HIV-related knowledge of the general population and providing opportunities for PLWH to be reintegrated into should be considered. Using mass media with positive messages and images would also foster positive attitudes towards HIV/AIDS among the population and could potentially change social values. Continuous training of health staffs’ attitude could minimize the occurrence of stigmatization and discrimination at healthcare facilities.

Sign in / Sign up

Export Citation Format

Share Document