Bite performance surfaces of three ecologically divergent Iguanidae lizards: relationships with lower jaw bones

2019 ◽  
Vol 127 (4) ◽  
pp. 810-825
Author(s):  
Monique Nouailhetas Simon ◽  
Renata Brandt ◽  
Tiana Kohlsdorf ◽  
Stevan J Arnold
Keyword(s):  
Biomechanical Model ◽  
Disruptive Selection ◽  
Head Shape ◽  
Linear Combinations ◽  
Mechanical Advantage ◽  
Jaw Bones ◽  
Correlational Selection ◽  
Lower Jaw ◽  
Linear Selection ◽  
Non Linear

Abstract Traits that interact to perform an ecologically relevant function are expected to be under multivariate non-linear selection. Using the lower jaw morphology as a biomechanical model, we test the hypothesis that lower jaw bones of lizards are subjected to stabilizing and correlational selection, associated with mechanical advantage and maximum bite force. We used three closely related tropidurine species that differ in size, head shape and microhabitat: Eurolophosaurus nanuzae, Tropidurus hispidus and Tropidurus semitaeniatus. We predicted a common pattern of correlational selection on bones that are part of in-levers or part of the out-lever of the lower jaw. The predicted pattern was found in E. nanuzae and T. hispidus, but this could not be shown to be statistically significant. For T. semitaeniatus, we found significant disruptive selection on a contrast involving the surangular, and also significant directional selection on linear combinations of traits in all species. The results indicate that the non-linear selection on lower jaw bones does not reflect an optimum to enhance mechanical advantage in all species. Divergent functional demands and specific ecological contexts of species seem relevant in shaping patterns of selection on morphology.

Optimum linear selection indexes for multiple generation objectives with non-linear profit functions

1995 ◽  
Vol 61 (1) ◽  
pp. 165-175 ◽  
Author(s):  
J. C. M. Dekkers ◽  
P. V. Birke ◽  
J. P. Gibson
Keyword(s):  
Optimal Control ◽  
Net Present Value ◽  
Selection Index ◽  
Index Theory ◽  
Planning Horizon ◽  
Simultaneous Optimization ◽  
Linear Selection ◽  
Non Linear ◽  
Profit Functions ◽  
Selection Indexes

AbstractA method to obtain linear selection indexes that maximize objectives that involve average profit in one or more generations within a planning horizon based on non-linear profit functions, was derived through application of optimal control theory. The method involves simultaneous optimization of indexes for each generation in the planning horizon. Optimum linear indexes were found to be conform indexes derived from selection index theory, with economic values equal to a weighted sum of partial derivatives of the profit function at the trait means which result in each generation of the planning horizon. Numerical procedures to derive optimum indexes are presented. Methods and properties of alternative strategies for selection witli non-linear profit functions are illustrated for selection on egg weight and rate of lay in poultry. In the example, the additional benefit of selection indexes that maximize cumulative net present value of profit over a planning horizon of10 years was small relative to use of traditional selection procedures. Optimal indexes were also derived with a derivative-free non-linear programming optimizer, with identical results. The latter method also allows incorporation of additional constraints.Possible extensions of the optimal control methodology to address other problems related to optimization of selection over multiple generations are discussed.

scholarly journals Morphology of the suspensorial, jaw, and opercle musculature of Beloniformes and related species (Teleostei: Acanthopterygii), with a special reference to the m. adductor mandibulae complex

2014 ◽  
Author(s):  
Ingmar Werneburg
Keyword(s):  
Related Species ◽  
Phylogenetic Analyses ◽  
Phylogenetic Position ◽  
Closely Related Species ◽  
Jaw Bones ◽  
Morphological Findings ◽  
Lower Jaw ◽  
Flying Fishes ◽  
Reduced Mobility ◽  
Jaw Musculature

The taxon Beloniformes represents a heterogeneous group of teleost fishes that show an extraordinary diversity of jaw morphology. I present new anatomical descriptions of the jaw musculature in six selected beloniforms and four closely related species. A reduction of the external jaw adductor (A1) and a changed morphology of the intramandibular musculature were found in many Beloniformes. This might be correlated with the progressively reduced mobility of the upper and lower jaw bones. The needlefishes and sauries, which are characterised by extremely elongated and stiffened jaws, show several derived characters, which in combination enable the capture of fish at high velocity. The ricefishes are characterised by several derived and many plesiomorphic characters that make broad scale comparisons difficult. Soft tissue characters are highly diverse among hemiramphids and flying fishes reflecting the uncertainty about their phylogenetic position and interrelationship. The morphological findings presented herein may help to interpret future phylogenetic analyses using cranial musculature in Beloniformes.

scholarly journals Studies on the Upper and Lower Jaw-bones of the Japanese

1950 ◽  
Vol 17 (5) ◽  
pp. 290-302
Author(s):  
Yoshihiro Kaneko
Keyword(s):  
Jaw Bones ◽  
Lower Jaw

scholarly journals Mechanics of Screw Joints Solved as Beams Placed in a Tangential Elastic Foundation

2021 ◽  
Vol 11 (12) ◽  
pp. 5616
Author(s):  
Karel Frydrýšek ◽  
Šárka Michenková ◽  
Leopold Pleva ◽  
Jan Koutecký ◽  
Jiří Fries ◽  
...  
Keyword(s):  
Biomechanical Model ◽  
Human Cadaver ◽  
Joint Models ◽  
Limit Values ◽  
Pull Out ◽  
Spruce Wood ◽  
Screw Joint ◽  
Non Linear ◽  
Deformation Force ◽  
Stress States

This article deals with a new original analytical solution of deformation, force and stress states in wood screw joints up to the limit values of pulling out/breaking the screw. The screws are under tension. The wood-to-screw interaction is effectively simplified by introducing several physical model variants using a tangential elastic non-linear foundation. The experimental verification of the proposed models using pull-out tests (i.e., pulling out screws from dry spruce wood in laboratory conditions) confirms the correctness of the proposed models of the elastic linear/non-linear foundation. The validity of the model is also analytically and experimentally verified in the biomechanical model of pulling out screws from the femur of a bovine/human cadaver, which confirms and expands the validity of newly designed screw joint models outside the timber structure area.

scholarly journals Changes in jaw dimensions and bone density in patients with osteoporosis

2009 ◽  
Vol 56 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Srdjan Postic
Keyword(s):  
Bone Density ◽  
Treatment Method ◽  
Radiographic Analysis ◽  
Panoramic Radiographs ◽  
Jaw Bones ◽  
Restorative Treatment ◽  
Lower Jaw

Introduction Osteopenia and osteoporosis reduce the density and mass of jaw bones. Aim The aim of this study was to present the methods of radiographic analysis in patients with osteoporosis prior to restorative treatment. Method 127 panoramic radiographs (Kodak, USA) and 39 retroalveolar radiographs (KD 58-R 30?40 mm, USA) were used for the analysis of density (DT II 05 densitometer, England) and dimensions of jaw bones with respect to segments corresponding to bone layers. Results The results of this study indicated statistically significant differences in bone density (p<0.05 and p<0.01) in patients with osteopenia. Bone density was significantly reduced (p<0.01 and p<0.001) in osteoporotic patients, when compared to controls. Significant reductions of edentulous ridges in osteoporotic patients women X=23.05 mm (kV=30.72%) and X=22.85 mm (kV=28.81%), and men X=28.83 (kV=8.55%) as well as X=25.36 (kV=11.43%), were observed. Conclusion Bone density of the upper and lower jaw is reduced in osteoporotic patients. At the very beginning of restorative prosthodontic therapy of osteoporotic patients, retroalveolar radiographs and panoramic radiographs should be obtained. Reference lines should be assigned, contours of the alveolar and edentulous ridges on radiographs should be analysed and bone density assessed.

scholarly journals Morphology of the jaw, suspensorial, and opercle musculature of Beloniformes and related species (Teleostei: Acanthopterygii), with a special reference to the m. adductor mandibulae complex

2015 ◽  
Author(s):  
Ingmar Werneburg
Keyword(s):  
Related Species ◽  
Phylogenetic Analyses ◽  
Phylogenetic Position ◽  
Closely Related Species ◽  
Jaw Bones ◽  
Morphological Findings ◽  
Lower Jaw ◽  
Flying Fishes ◽  
Reduced Mobility ◽  
Jaw Musculature

The taxon Beloniformes represents a heterogeneous group of teleost fishes that show an extraordinary diversity of jaw morphology. I present new anatomical descriptions of the jaw musculature in six selected beloniforms and four closely related species. A reduction of the external jaw adductor (A1) and a changed morphology of the intramandibular musculature were found in many Beloniformes. This might be correlated with the progressively reduced mobility of the upper and lower jaw bones. The needlefishes and sauries, which are characterised by extremely elongated and stiffened jaws, show several derived characters, which in combination enable the capture of fish at high velocity. The ricefishes are characterised by several derived and many plesiomorphic characters that make broad scale comparisons difficult. Soft tissue characters are highly diverse among hemiramphids and flying fishes reflecting the uncertainty about their phylogenetic position and interrelationship. The morphological findings presented herein may help to interpret future phylogenetic analyses using cranial musculature in Beloniformes.

scholarly journals STUDY OF STRESS-STRAIN STATE OF MATHEMATICAL MODEL OF JAWS USING THE FINITE-ELEMENTS METHOD

2019 ◽  
Vol 19 (1-2) ◽  
pp. 131-139
Author(s):  
D. A Trunin ◽  
A. V Revyakin ◽  
M. A Postnikov ◽  
I. N Kolganov ◽  
I. A Zakharova ◽  
...  
Keyword(s):  
Finite Elements ◽  
Strain State ◽  
Soft Tissues ◽  
Finite Elements Method ◽  
Stress Strain ◽  
Jaw Bones ◽  
Stress Strain State ◽  
Lower Jaw ◽  
Characteristic Features ◽  
Bone Structures

This work is devoted to the study of the stress-strain state (SSS) model by using the finite-elements method (FEM) of jaw-bones (the system of lower jaw (LJ) - upper jaw (UJ)) and is the next step in understanding the mechanism of mastication as one of the main functions of the maxillofacial system (MFS). At the same time, reliable information about SSS of the LJ and UJ bones with account of the peculiarities of their anatomical and topographical structure will, firstly, reveal the main regularities of the jaw bone deformations. It will make possible to choose prosthetic appliances that will provide the minimum level of intensity of atrophic processes in supporting tissues and the most favorable biomechanical interaction of bone structures, soft tissues and elements of the prosthetic appliance. The results of mathematical calculations allowed to identify the characteristic features of the deformation and interaction of the LJ and UJ bones, which will ensure a scientifically based choice of those prosthetic appliances contributing to the most prolonged and normal functioning of the maxillofacial system in general.

Sign in / Sign up

Export Citation Format

Share Document