scholarly journals Does aquatic foraging impact head shape evolution in snakes?

2016 ◽  
Vol 283 (1837) ◽  
pp. 20161645 ◽  
Author(s):  
Marion Segall ◽  
Raphaël Cornette ◽  
Anne-Claire Fabre ◽  
Ramiro Godoy-Diana ◽  
Anthony Herrel
Keyword(s):  
Aquatic Environment ◽  
Anterior Part ◽  
Three Dimensional ◽  
Shape Evolution ◽  
Head Shape ◽  
Evolutionary Trajectory ◽  
Biomechanical Models ◽  
Historical Factors ◽  
Evolutionary Trajectories ◽  
Do So

Evolutionary trajectories are often biased by developmental and historical factors. However, environmental factors can also impose constraints on the evolutionary trajectories of organisms leading to convergence of morphology in similar ecological contexts. The physical properties of water impose strong constraints on aquatic feeding animals by generating pressure waves that can alert prey and potentially push them away from the mouth. These hydrodynamic constraints have resulted in the independent evolution of suction feeding in most groups of secondarily aquatic tetrapods. Despite the fact that snakes cannot use suction, they have invaded the aquatic milieu many times independently. Here, we test whether the aquatic environment has constrained head shape evolution in snakes and whether shape converges on that predicted by biomechanical models. To do so, we used three-dimensional geometric morphometrics and comparative, phylogenetically informed analyses on a large sample of aquatic snake species. Our results show that aquatic snakes partially conform to our predictions and have a narrower anterior part of the head and dorsally positioned eyes and nostrils. This morphology is observed, irrespective of the phylogenetic relationships among species, suggesting that the aquatic environment does indeed drive the evolution of head shape in snakes, thus biasing the evolutionary trajectory of this group of animals.

scholarly journals Flowering plant embryos: How did we end up here?

2021 ◽  
Author(s):  
Stefan A. Rensing ◽  
Dolf Weijers
Keyword(s):  
Current Knowledge ◽  
General Structure ◽  
Three Dimensional ◽  
Flowering Plants ◽  
Flowering Plant ◽  
Adult Plant ◽  
Ancestral State ◽  
Evolutionary Trajectory ◽  
Current State ◽  
Plant Embryo

AbstractThe seeds of flowering plants are sexually produced propagules that ensure dispersal and resilience of the next generation. Seeds harbor embryos, three dimensional structures that are often miniatures of the adult plant in terms of general structure and primordial organs. In addition, embryos contain the meristems that give rise to post-embryonically generated structures. However common, flowering plant embryos are an evolutionary derived state. Flowering plants are part of a much larger group of embryo-bearing plants, aptly termed Embryophyta. A key question is what evolutionary trajectory led to the emergence of flowering plant embryos. In this opinion, we deconstruct the flowering plant embryo and describe the current state of knowledge of embryos in other plant lineages. While we are far yet from understanding the ancestral state of plant embryogenesis, we argue what current knowledge may suggest and how the knowledge gaps may be closed.

Biomechanical Models for Radial Distance Determination by the Rat Vibrissal System

2007 ◽  
Vol 98 (4) ◽  
pp. 2439-2455 ◽  
Author(s):  
J. Alexander Birdwell ◽  
Joseph H. Solomon ◽  
Montakan Thajchayapong ◽  
Michael A. Taylor ◽  
Matthew Cheely ◽  
...  
Keyword(s):  
Angular Position ◽  
Three Dimensional ◽  
Radial Distance ◽  
Rate Of Change ◽  
Dynamic State ◽  
Rhythmic Movements ◽  
Tactile Information ◽  
Biomechanical Models ◽  
Object Distance ◽  
Dimensional Object

Rats use active, rhythmic movements of their whiskers to acquire tactile information about three-dimensional object features. There are no receptors along the length of the whisker; therefore all tactile information must be mechanically transduced back to receptors at the whisker base. This raises the question: how might the rat determine the radial contact position of an object along the whisker? We developed two complementary biomechanical models that show that the rat could determine radial object distance by monitoring the rate of change of moment (or equivalently, the rate of change of curvature) at the whisker base. The first model is used to explore the effects of taper and inherent whisker curvature on whisker deformation and used to predict the shapes of real rat whiskers during deflections at different radial distances. Predicted shapes closely matched experimental measurements. The second model describes the relationship between radial object distance and the rate of change of moment at the base of a tapered, inherently curved whisker. Together, these models can account for recent recordings showing that some trigeminal ganglion (Vg) neurons encode closer radial distances with increased firing rates. The models also suggest that four and only four physical variables at the whisker base—angular position, angular velocity, moment, and rate of change of moment—are needed to describe the dynamic state of a whisker. We interpret these results in the context of our evolving hypothesis that neural responses in Vg can be represented using a state-encoding scheme that includes combinations of these four variables.

scholarly journals Influence of different orientations and rates of bidirectional distraction osteogenesis of the mandibular corpus: a three-dimensional study.

2019 ◽  
Vol S (1) ◽  
pp. 11-14
Author(s):  
Lamiaa A. Hasan ◽  
◽  
Nada M. Al-Sayagh ◽  
Lara R. Al-Banaa ◽  
◽  
...  
Keyword(s):  
Distraction Osteogenesis ◽  
Anterior Part ◽  
Three Dimensional ◽  
Posterior Part ◽  
Von Mises Stress ◽  
Occlusal Plane ◽  
Three Dimensional Model ◽  
Direction Parallel ◽  
Inferior Border ◽  
Von Mises

Objective: The objective of this study was to evaluate the biomechanical effect of mandibular corpus distraction osteogenesis with different orientations and rates. Materials and Methods: A three-dimensional model of the mandible was created. The vertical surgical cut was made, the force was applied horizontally in a bidirectional manner within two orientations: parallel to the occlusal plane and parallel to the inferior border of the mandible with three rates (0.5mm, 1mm and 1.5mm). Results: The maximum values for von Mises stress when the force was applied parallel to the inferior border of the mandible with all three rates were smaller than those with force direction parallel to the occlusal plane. The displacement in all three directions x, y, and z were not parallel and prominent in the anterior part of the mandible, while the movement at the posterior part is negligible, x and z displacement were bigger when force was applied parallel to the inferior border of the mandible, z displacement was more prominent than x and y displacement, both directions produced upward rotation of the mandible, this rotation was more noticeable when the force was applied parallel to the inferior border of the mandible. Conclusions: A vertical cut can be used in the patient with a long anterior face. This site of distraction achieves more lengthening of mandible than expansion.

scholarly journals O lugar da cartografia no ensino de geografia: perspectivas a partir de um projeto de extensão

GeoTextos ◽  
2013 ◽  
Vol 9 (1) ◽  
Author(s):  
Erika Do Carmo Cerqueira ◽  
Dária Maria Cardoso Nascimento
Keyword(s):  
New Technologies ◽  
School Context ◽  
Three Dimensional ◽  
Pedagogical Practice ◽  
State School ◽  
Dimensional Representation ◽  
Three Dimensional Representation ◽  
Innovative Methodology ◽  
Do So

Este trabalho visa discutir o lugar e/ou papel da cartografia no ensino da geografia. Para isso, traz resultados teóricos e práticos do projeto de pesquisa e extensão intitulado “Popularização da cartografia e suas novas tecnologias na escola pública”, realizado no Colégio Estadual Dona Mora Guimarães (Cajazeiras X, Salvador BA). Considera-se que a cartografia escolar, apesar dos avanços epistemológicos, vem passando por diversas dificuldades em sua implementação. Para analisar os entraves, potencialidades e exemplos de práxis pedagógicas, realizaram-se oficinas com foco nos conceitos da alfabetização cartográfica – visão vertical/horizontal, lateralidade, decodificação dos símbolos, proporcionalidade, representação bidimensional X tridimensional e uso de novas tecnologias. Defende-se que a alfabetização cartográfica pode ser utilizada como uma metodologia inovadora para a geografia escolar. Em paralelo, são discutidas as dificuldades encontradas em âmbito universitário e escolar. Por fim, dividem-se experiências exitosas, com mais de 400 alunos envolvidos diretamente, que utilizaram recursos técnico metodológicos a partir do espaço vivenciado e da abordagem construtivista, a saber: mapeamento do corpo humano, da sala de aula e construção de maquetes. Conclui-se que o tema possui muitos desafios, mas carece principalmente da ampliação deste debate para ultrapassar as barreiras dissociativas, colocando a cartografia como meio de comunicação da ciência geográfica. Abstract THE ROLE OF CARTOGRAPHY IN THE TEACHING OF GEOGRAPHY: PERSPECTIVES FROM AN EXTENSION PROJECT This paper aims to discuss the role of cartography in the teaching of geography. In order to do so it brings theoretical and practical results of the research project and extension called “Popularization of cartography and its new technologies in public school,” held in the State School Dona Mora Guimarães (Cazajeiras X, Salvador- BA). It is considered that the teaching of cartography, despite the epistemological advances, has experienced several difficulties in its implementation. To analyze the barriers, potentialities, and examples of pedagogical practice, workshops were held focusing on the concepts of cartographic literacy - vision vertical/horizontal, laterality, decoding of symbols, proportionality, two-dimensional X three-dimensional representation and use of new technologies. It is advocated that cartographic literacy can be used as an innovative methodology for the teaching of geography in schools. In parallel, the difficulties found in a university and school context are discussed. Finally, successful experiences are shared with more than 400 students involved directly, who used technical and methodological resources, from where they live and constructivist approach, namely: mapping of the human body, of the classroom and building of models. It is concluded that the theme has many challenges, but lacks mainly the expansion of this debate to overcome the dissociative barriers, putting the cartography as means of communication of the geographical science.

scholarly journals Characterisation of B.1.1.7 and Pangolin coronavirus spike provides insights on the evolutionary trajectory of SARS-CoV-2

2021 ◽  
Author(s):  
Samuel J Dicken ◽  
Matthew J Murray ◽  
Lucy G Thorne ◽  
Ann-Kathrin Reuschl ◽  
Calum Forrest ◽  
...  
Keyword(s):  
Protein Function ◽  
Virus Entry ◽  
Mitigation Measures ◽  
Evolutionary Trajectory ◽  
Immune Resistance ◽  
Recent Emergence ◽  
Model Cell ◽  
Evolutionary Trajectories ◽  
Evolutionary Tuning ◽  
The Uk

The recent emergence of SARS-CoV-2 variants with increased transmission, pathogenesis and immune resistance has jeopardised the global response to the COVID-19 pandemic. Determining the fundamental biology of viral variants and understanding their evolutionary trajectories will guide current mitigation measures, future genetic surveillance and vaccination strategies. Here we examine virus entry by the B.1.1.7 lineage, commonly referred to as the UK/Kent variant. Pseudovirus infection of model cell lines demonstrate that B.1.1.7 entry is enhanced relative to the Wuhan-Hu-1 reference strain, particularly under low expression of receptor ACE2. Moreover, the entry characteristics of B.1.1.7 were distinct from that of its predecessor strain containing the D614G mutation. These data suggest evolutionary tuning of spike protein function. Additionally, we found that amino acid deletions within the N-terminal domain (NTD) of spike were important for efficient entry by B.1.1.7. The NTD is a hotspot of diversity across sarbecoviruses, therefore, we further investigated this region by examining the entry of closely related CoVs. Surprisingly, Pangolin CoV spike entry was 50-100 fold enhanced relative to SARS-CoV-2; suggesting there may be evolutionary pathways by which SARS-CoV-2 may further optimise entry. Swapping the NTD between Pangolin CoV and SARS-CoV-2 demonstrates that changes in this region alone have the capacity to enhance virus entry. Thus, the NTD plays a hitherto unrecognised role in modulating spike activity, warranting further investigation and surveillance of NTD mutations.

Rethinking Cognition, Representations, and Processes in 3D Online Social Learning Environments

2008 ◽  
pp. 176-205 ◽  
Author(s):  
James G. Jones ◽  
Stephen C. Bronack
Keyword(s):  
Social Learning ◽  
Learning Environments ◽  
Virtual Worlds ◽  
Three Dimensional ◽  
Social Environments ◽  
3D Virtual Worlds ◽  
Movement Artifacts ◽  
University Level ◽  
The University ◽  
Do So

Three-dimensional (3D) online social environments have emerged as viable alternatives to traditional methods of creating spaces for teachers and learners to teach to and to learn from one another. Robust environments with a bias toward peer-based, network-driven learning allow learners in formal environments to make meaning in ways more similar to those used in informal and in-person settings. These new created environments do so by accounting for presence, immediacy, movement, artifacts, and multi-modal communications in ways that help learners create their own paths of knowing using peer-supported methods. In this chapter, we will review the basics of the technologies and the theoretical underpinnings that support the development of such environments, provide a framework for creating, sustaining, and considering the effectiveness of such environments, and will conclude by describing two examples of 3D virtual worlds used to support course instruction at the university level.

scholarly journals Biological Significance of Tumor Heterogeneity in Esophageal Squamous Cell Carcinoma

Cancers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1156 ◽  
Author(s):  
Lehang Lin ◽  
De-Chen Lin
Keyword(s):  
Squamous Cell Carcinoma ◽  
Esophageal Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Tumor Heterogeneity ◽  
Three Dimensional ◽  
Biological Significance ◽  
Molecular Characteristics ◽  
Tumor Evolution ◽  
Evolutionary Trajectories

Esophageal squamous cell carcinoma (ESCC) is a common and aggressive malignancy, with hitherto dismal clinical outcome. Genomic analyses of patient samples reveal a complex heterogeneous landscape for ESCC, which presents in both intertumor and intratumor forms, manifests at both genomic and epigenomic levels, and contributes significantly to tumor evolution, drug resistance, and metastasis. Here, we review the important molecular characteristics underlying ESCC heterogeneity, with an emphasis on genomic aberrations and their functional contribution to cancer evolutionary trajectories. We further discuss how novel experimental tools, including single-cell sequencing and three-dimensional organoids, may advance our understanding of tumor heterogeneity. Lastly, we suggest that deciphering the mechanisms governing tumor heterogeneity holds the potential to developing precision therapeutics for ESCC patients.

scholarly journals The Biomechanics of Erections: Modeling the Penis as a One-Comparment Pressurized Vessel vs. Modeling it as a Two-Compartments Pressurized Vessel

2009 ◽  
Vol 3 (2) ◽  
Author(s):  
A. Mohamed ◽  
A. Erdman ◽  
G. Timm
Keyword(s):  
Structural Integrity ◽  
Tunica Albuginea ◽  
Three Dimensional ◽  
The Body ◽  
Physical Models ◽  
Von Mises Stress ◽  
Two Dimensional ◽  
Biomechanical Models ◽  
Significant Difference ◽  
The One

Previous biomechanical models of the penis that have attempted to simulate penile erections have either been limited to two-dimensional geometry, simplified three-dimensional geometry or made inaccurate assumptions altogether. Most models designed the shaft of the penis as a one-compartment pressurized vessel fixed at one end, when in reality it is a two-compartments pressurized vessel, in which the compartments diverge as they enter the body and are fixed at two separate points. This study began by designing simplified two-dimensional and three-dimensional models of the erect penis using Finite Element Analysis (FEA) methods with varying anatomical considerations for analyzing structural stresses, axial buckling and lateral deformation. The study then validated the results by building physical models replicating the computer models. Finally a more complex and anatomically accurate model of the penis was designed and analyzed. There was a significant difference in the peak von-Mises stress distribution between the one-compartment pressurized vessel and the more anatomically correct two-compartments pressurized vessel. Furthermore, the two-compartments diverging pressurized vessel was found to have more structural integrity when subject to external lateral forces than the one-compartment pressurized vessel. This study suggests that Mother Nature has favored an anatomy of two corporal cavernosal bodies separated by a perforated septum as opposed to one corporal body, due to better structural integrity of the tunica albuginea when subject to external forces.

Warning signals promote morphological diversification in fossorial uropeltid snakes (Squamata: Uropeltidae)

2020 ◽  
Author(s):  
Vivek Philip Cyriac ◽  
Ullasa Kodandaramaiah
Keyword(s):  
Body Size ◽  
Free Space ◽  
Morphological Evolution ◽  
Environmental Constraints ◽  
Shape Evolution ◽  
Head Shape ◽  
Warning Signals ◽  
Morphological Diversification ◽  
Niche Expansion ◽  
Antipredator Defences

Abstract Many species possess warning colourations that signal unprofitability to predators. Warning colourations are also thought to provide prey with a ‘predator-free space’ and promote niche expansion. However, how such strategies release a species from environmental constraints and facilitate niche expansion is not clearly understood. Fossoriality in reptiles imposes several morphological limits on head and body size to facilitate burrowing underground, but many fossorial snakes live close to the surface and occasionally move above ground, exposing them to predators. In such cases, evolving antipredator defences that reduce predation on the surface could potentially relax the morphological constraints associated with fossoriality and promote morphological diversification. Fossorial uropeltid snakes possess varying degrees of conspicuous warning colourations that reduce avian predation when active above ground. We predicted that species with more conspicuous colourations will exhibit more robust body forms and show faster rates of morphological evolution because constraints imposed by fossoriality are relaxed. Using a comparative phylogenetic approach on the genus Uropeltis, we show that more conspicuous species tend to have more robust morphologies and have faster rates of head-shape evolution. Overall, we find that the evolution of warning colourations in Uropeltis can facilitate niche expansion by influencing rates of morphological diversification.

scholarly journals An automated computational biomechanics workflow for improving breast cancer diagnosis and treatment

2019 ◽  
Vol 9 (4) ◽  
pp. 20190034 ◽  
Author(s):  
Thiranja Prasad Babarenda Gamage ◽  
Duane T. K. Malcolm ◽  
Gonzalo Maso Talou ◽  
Anna Mîra ◽  
Anthony Doyle ◽  
...  
Keyword(s):  
Breast Cancer ◽  
State Of The Art ◽  
Three Dimensional ◽  
Breast Cancer Diagnosis ◽  
Automated System ◽  
Machine Learning Techniques ◽  
Breast Cancers ◽  
Computational Biomechanics ◽  
Biomechanical Models ◽  
Treatment Procedures

Clinicians face many challenges when diagnosing and treating breast cancer. These challenges include interpreting and co-locating information between different medical imaging modalities that are used to identify tumours and predicting where these tumours move to during different treatment procedures. We have developed a novel automated breast image analysis workflow that integrates state-of-the-art image processing and machine learning techniques, personalized three-dimensional biomechanical modelling and population-based statistical analysis to assist clinicians during breast cancer detection and treatment procedures. This paper summarizes our recent research to address the various technical and implementation challenges associated with creating a fully automated system. The workflow is applied to predict the repositioning of tumours from the prone position, where diagnostic magnetic resonance imaging is performed, to the supine position where treatment procedures are performed. We discuss our recent advances towards addressing challenges in identifying the mechanical properties of the breast and evaluating the accuracy of the biomechanical models. We also describe our progress in implementing a prototype of this workflow in clinical practice. Clinical adoption of these state-of-the-art modelling techniques has significant potential for reducing the number of misdiagnosed breast cancers, while also helping to improve the treatment of patients.

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