A Model of Stress and Strain in the Interosseous Ligament of the Forearm Based on Fiber Network Theory

2006 ◽  
Vol 128 (5) ◽  
pp. 725-732 ◽  
Author(s):  
H. James Pfaeffle ◽  
Kenneth J. Fischer ◽  
Arun Srinivasa ◽  
Theodore Manson ◽  
Savio L-Y. Woo ◽  
...  
Keyword(s):  
Network Model ◽  
Network Theory ◽  
Three Dimensional ◽  
Experimental Result ◽  
Stress And Strain ◽  
Forearm Rotation ◽  
Fiber Network ◽  
Interosseous Ligament

Fiber network theory was developed to describe cloth, a thin material with strength in the fiber directions. The interosseous ligament (IOL) of the forearm is a broad, thin ligament with highly aligned fibers. The objectives of this study were to develop a model of the stress and strain distributions in the IOL, based on fiber network theory, to compare the strains from the model with the experimentally measured strains, and to evaluate the force distribution across the ligament fibers from the model. The geometries of the radius, ulna, and IOL were reconstructed from CT scans. Position and orientation of IOL insertion sites and force in the IOL were measured during a forearm compression experiment in pronation, neutral rotation, and supination. An optical image-based technique was used to directly measure strain in two regions of the IOL in neutral rotation. For the network model, the IOL was represented as a parametric ruled three-dimensional surface, with rulings along local fiber directions. Fiber strains were calculated from the deformation field, and fiber stresses were calculated from the strains using average IOL tensile properties from a previous study. The in situ strain in the IOL was assumed uniform and was calculated so that the net force predicted by the network model in neutral rotation matched the experimental result. The net force in the IOL was comparable to experimental results in supination and pronation. The model predicted higher stress and strain in fibers near the elbow in neutral rotation, and higher stresses in fibers near the wrist in supination. Strains in neutral forearm rotation followed the same trends as those measured experimentally. In this study, a model of stress and strain in the IOL utilizing fiber network theory was successfully implemented. The model illustrates variations in the stress and strain distribution in the IOL. This model can be used to show surgeons how different fibers are taut in different forearm rotation positions—this information is important for understanding the biomechanical role of the IOL and for planning an IOL reconstruction.

How Artefacts Do Leadership: A Ventriloquial Analysis

2021 ◽  
pp. 089331892199807
Author(s):  
Jonathan Clifton ◽  
Fernando Fachin ◽  
François Cooren
Keyword(s):  
Organizational Communication ◽  
Recent Work ◽  
Distributed Leadership ◽  
Network Theory ◽  
Actor Network Theory ◽  
Fine Grained ◽  
Naturally Occurring ◽  
Human Actors

To date there has been little work that uses fine-grained interactional analyses of the in situ doing of leadership to make visible the role of non-human as well as human actants in this process. Using transcripts of naturally-occurring interaction as data, this study seeks to show how leadership is co-achieved by artefacts as an in-situ accomplishment. To do this we situate this study within recent work on distributed leadership and argue that it is not only distributed across human actors, but also across networks that include both human and non-human actors. Taking a discursive approach to leadership, we draw on Actor Network Theory and adopt a ventriloquial approach to sociomateriality as inspired by the Montreal School of organizational communication. Findings indicate that artefacts “do” leadership when a hybrid presence is made relevant to the interaction and when this presence provides authoritative grounds for influencing others to achieve the group’s goals.

scholarly journals Transport and localization of exogenous myelin basic protein mRNA microinjected into oligodendrocytes.

1993 ◽  
Vol 123 (2) ◽  
pp. 431-441 ◽  
Author(s):  
K Ainger ◽  
D Avossa ◽  
F Morgan ◽  
S J Hill ◽  
C Barry ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Living Cells ◽  
Branch Points ◽  
Rna Granules ◽  
Intracellular Movement ◽  
Directional Movement ◽  
Ionic Detergent ◽  
Mrna Granules

We have studied transport and localization of MBP mRNA in oligodendrocytes in culture by microinjecting labeled mRNA into living cells and analyzing the intracellular distribution of the injected RNA by confocal microscopy. Injected mRNA initially appears dispersed in the perikaryon. Within minutes, the RNA forms granules which, in the case of MBP mRNA, are transported down the processes to the periphery of the cell where the distribution again becomes dispersed. In situ hybridization shows that endogenous MBP mRNA in oligodendrocytes also appears as granules in the perikaryon and processes and dispersed in the peripheral membranes. The granules are not released by extraction with non-ionic detergent, indicating that they are associated with the cytoskeletal matrix. Three dimensional visualization indicates that MBP mRNA granules are often aligned in tracks along microtubules traversing the cytoplasm and processes. Several distinct patterns of granule movement are observed. Granules in the processes undergo sustained directional movement with a velocity of approximately 0.2 micron/s. Granules at branch points undergo oscillatory motion with a mean displacement of 0.1 micron/s. Granules in the periphery of the cell circulate randomly with a mean displacement of approximately 1 micron/s. The results are discussed in terms of a multi-step pathway for transport and localization of MBP mRNA in oligodendrocytes. This work represents the first characterization of intracellular movement of mRNA in living cells, and the first description of the role of RNA granules in transport and localization of mRNA in cells.

Diversity of the sponge fauna associated with white coral banks from two Sardinian canyons (Mediterranean Sea)

2019 ◽  
Vol 99 (8) ◽  
pp. 1735-1751 ◽  
Author(s):  
M. Bertolino ◽  
S. Ricci ◽  
S. Canese ◽  
A. Cau ◽  
G. Bavestrello ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Cold Water ◽  
Three Dimensional ◽  
Western Mediterranean ◽  
Tyrrhenian Sea ◽  
Lophelia Pertusa ◽  
Wide Range ◽  
Santa Maria

AbstractThe three-dimensional coral scaffolds formed by the skeletons of the cold-water corals Madrepora oculata and Lophelia pertusa represent an important deep-sea hard substratum and create an optimal shelter for a rich associated fauna in which the contribution of Porifera has still not been fully considered. The taxonomic analysis of sponges collected from two Sardinian canyons (Nora and Coda Cavallo, 256–408 m) and associated with the dead coral matrix resulted in 28 species, including new records for the Mediterranean Sea, Italian fauna or Central Tyrrhenian Sea. In addition, for many species this is the first finding associated with the coral framework or the first documentation of the in situ morphology. The taxonomic comparison with sponge assemblages associated with coral frameworks from Santa Maria di Leuca, Strait of Sicily and Bari Canyon, gave the opportunity to evaluate the similarities among geographically separated banks. Overall, the percentage of exclusive species (recorded only in one site), is very high (81%) and only one species is shared by all four sites, suggesting a low connectivity among the sponge communities. The percentage of shared species is higher for the Maltese community, supporting the role of the Sicily Channel as a crossroads between the communities of the eastern and western Mediterranean basins. Here, 55% of the sponges associated to the coral framework are also reported in shallow-water coralligenous assemblages, indicating a high bathymetric connectivity as well as an ecological plasticity allowing these species to occupy a wide range of small, dark refuges.

Development of a biaxial stretching test machine and its applications

2018 ◽  
Vol 38 (6) ◽  
pp. 605-616 ◽  
Author(s):  
Kentaro Egoshi ◽  
Toshitaka Kanai ◽  
Kazuhiro Tamura
Keyword(s):  
Light Scattering ◽  
Evaluation Method ◽  
Three Dimensional ◽  
Crystalline Polymer ◽  
Stress And Strain ◽  
Test Machine ◽  
Biaxial Stretching ◽  
As Stress ◽  
Stretching Process

Abstract The evaluation method for a biaxially oriented film was developed using in-situ measurement during the stretching process. It can obtain basic data such as stress-strain curves, birefringence, light scattering, three dimensional refractive indexes and birefringence distribution. Stress and strain as functions of stretching speed and stretching temperature, as well as the deformation of spherulite of semi-crystalline polymer can be obtained by measuring the birefringence and light scattering during the biaxial stretching process with a small piece of polymer sample. The experimental results show the stress, retardation and three dimensional molecular orientations behavior during the simultaneous biaxial stretching and the sequential biaxial stretching process. Stretchability, thickness uniformity and spherulite size can be obtained simultaneously. In this paper, advantages and details of the newly developed system will be discussed with some experimental data.

Finite Element Analysis of Stress and Strain in Two-Wedge Cross Wedge Rolling Step-Shaft Part

2008 ◽  
Vol 575-578 ◽  
pp. 255-260 ◽  
Author(s):  
Xi Dong Xing ◽  
Xue Dao Shu
Keyword(s):  
Finite Element ◽  
Deformation Process ◽  
Three Dimensional ◽  
Experimental Result ◽  
Work Piece ◽  
Stress And Strain ◽  
Cross Wedge Rolling ◽  
Principal Stresses ◽  
Element Analysis ◽  
Design Guideline

Two-wedge Cross Wedge Rolling (TCWR) is a metal processing technology in which a heated cylindrical billet is plastically deformed into an axial part by the action of two wedges dies moving tangentially relative to the work piece. The metal deformation process is more complicated in TCWR than in single-wedge CWR. In this paper, a new and innovative numerical model of TCWR was developed, using advanced explicit dynamic finite element method (FEM). The whole TCWR process was simulated successfully, the three-dimensional nonlinear deformation process including stress and strain variation among the whole stages was analyzed at length, and 4 different principal stresses, including the first, second, third and von Mises equivalent stresses, at different billet centers are presented serving as a TCWR design guideline. Experimental result proves that the finite element simulation in TCWR process is true and this fundamental investigation provides a multi-wedge guideline in selecting CWR tool parameters and tool manufacturing.

scholarly journals Silicon/polypyrrole nanocomposite wrapped with graphene for lithium ion anodes

MRS Advances ◽  
2017 ◽  
Vol 2 (54) ◽  
pp. 3323-3327 ◽  
Author(s):  
Changling Li ◽  
Chueh Liu ◽  
Zafer Mutlu ◽  
Yiran Yan ◽  
Kazi Ahmed ◽  
...  
Keyword(s):  
Silicon Nanoparticles ◽  
Sol Gel ◽  
Three Dimensional ◽  
Lithium Ion ◽  
Hydroxyl Groups ◽  
Transport Pathways ◽  
Fiber Network ◽  
Reduced Graphene ◽  
Sol Gel Process

ABSTRACTHerein, silicon nanoparticles (SiNPs) are coated with conducting hydrogel and wrapped with reduced graphene oxide (rGO) sheets via a facile and scalable solution-based sol-gel process. The in-situ polymerized polypyrrole (PPy) hydrogel forms an interconnected three-dimensional (3D) fiber matrix. Amine and hydroxyl groups from the hydrogel assist the encapsulation of the SiNPs through hydrogen bonding. The electro-conductive PPy fiber network and the wrapping of rGO offer efficient electron and ion transport pathways. The PPy/SiNPs/rGO electrodes can produce highly reversible capacities of 1312, 1285 and 1066 mAh g-1 at 100, 250 and 500 cycles at a current density of 2.1 A g-1, respectively.

Three-dimensional Gd-doped TiO2 fibrous photoelectrodes for efficient visible light-driven photocatalytic performance

RSC Advances ◽  
2014 ◽  
Vol 4 (23) ◽  
pp. 11750-11757 ◽  
Author(s):  
Junghyun Choi ◽  
P. Sudhagar ◽  
P. Lakshmipathiraj ◽  
Jung Woo Lee ◽  
Anitha Devadoss ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Photocatalytic Performance ◽  
Three Dimensional ◽  
Electrode Geometry ◽  
Doped Tio2 ◽  
Visible Light Driven

Demonstration of the role of electrode geometry on in situ Gd-doping and their effects in the photocatalytic activity.

Dynamics of the Growth of InAs Quantum Dots on GaAs(001) Substrates

1999 ◽  
Vol 571 ◽  
Author(s):  
D.I. Westwood ◽  
I.H. Brown ◽  
D.N.J. Linsell ◽  
C.C. Matthai
Keyword(s):  
Quantum Dots ◽  
Three Dimensional ◽  
Wetting Layer ◽  
Molecular Beam Epitaxial ◽  
Reflectance Anisotropy ◽  
Standard Rate ◽  
Conventional Models ◽  
Molecular Beam Epitaxial Growth

ABSTRACTStandard rate equation models of island formation in the InAs/GaAs(001) system have been reassessed in terms of new experimental evidence from real time in-situ reflectance anisotropy spectroscopy (RAS) measurements. These measurements have revealed the behaviour and role of the wetting layer in the modified Stranski-Krastanov growth mode during molecular beam epitaxial growth showing that it can continue to significantly increase in thickness following the onset of islanding. The presence of two dimensional (2D) islands, which act as precursors to three dimensional (3D) islands (the quantum dots) in conventional models, does in principle allow an extension of the “wetting layer”. However, it has been found necessary to extend the standard model to include extra terms that allow material to be incorporated into (and detach from) the wetting layer and which cannot convert to 3D islands. With this improved model, it is found possible to achieve agreement with the RAS measurements.

scholarly journals Inferring cell junction tension and pressure from cell geometry

Development ◽  
2021 ◽  
Vol 148 (18) ◽  
pp. dev192773
Author(s):  
Chloé Roffay ◽  
Chii J. Chan ◽  
Boris Guirao ◽  
Takashi Hiiragi ◽  
François Graner
Keyword(s):  
Three Dimensional ◽  
Cell Junction ◽  
Cell Geometry ◽  
Early Mouse Embryo ◽  
Validity Criteria ◽  
Early Mouse ◽  
Computational Analyses ◽  
Non Destructive

ABSTRACTRecognizing the crucial role of mechanical regulation and forces in tissue development and homeostasis has stirred a demand for in situ measurement of forces and stresses. Among emerging techniques, the use of cell geometry to infer cell junction tensions, cell pressures and tissue stress has gained popularity owing to the development of computational analyses. This approach is non-destructive and fast, and statistically validated based on comparisons with other techniques. However, its qualitative and quantitative limitations, in theory as well as in practice, should be examined with care. In this Primer, we summarize the underlying principles and assumptions behind stress inference, discuss its validity criteria and provide guidance to help beginners make the appropriate choice of its variants. We extend our discussion from two-dimensional stress inference to three dimensional, using the early mouse embryo as an example, and list a few possible extensions. We hope to make stress inference more accessible to the scientific community and trigger a broader interest in using this technique to study mechanics in development.

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