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https://www.readbyqxmd.com/read/27896679/what-are-the-biomechanical-properties-of-the-taylor-spatial-frame%C3%A2
#1
Daniel J Henderson, Jeremy L Rushbrook, Paul J Harwood, Todd D Stewart
BACKGROUND: The Taylor Spatial Frame™ (TSF) is a versatile variant of the traditional Ilizarov circular fixator. Although in widespread use, little comparative data exist to quantify the biomechanical effect of substituting the tried-and-tested Ilizarov construct for the TSF hexapod system. QUESTIONS/PURPOSES: This study was designed to investigate the mechanical properties of the TSF system under physiologic loads, with and without the addition of a simulated bone model, with comparison to the standard Ilizarov frame...
November 28, 2016: Clinical Orthopaedics and related Research
https://www.readbyqxmd.com/read/27818969/surgical-treatment-of-neglected-clubfoot-using-external-fixator
#2
Rodrigo Mota Pacheco Fernandes, Maurilio Darcy Dos Santos Mendes, Renato Amorim, Marcus Aurélio Preti, Marcelo Back Sternick, Guilherme Pelosini Gaiarsa
The definition of neglected clubfoot (NC) includes a variable range of complex deformities of the foot that are refractory to conventional treatments or are treated inappropriately. Several etiologies may be related to this. The Ilizarov method has become established as a tool for treating these deformities. It minimizes soft-tissue damage through gradual correction of the deformity, with a high success rate in relation to achieving a plantigrade foot, with low incidence of recurrence. The indications for treatment include severe rigid deformities (Dimeglio III and IV), or adverse skin conditions...
September 2016: Revista Brasileira de Ortopedia
https://www.readbyqxmd.com/read/27802747/a-high-performance-wave-guide-cryogenic-thermal-break
#3
S J Melhuish, M A McCulloch, L Piccirillo, C Stott
We describe a high-performance wave guide cryogenic thermal break. This has been constructed both for Ka band, using WR28 wave guide, and Q band, using WR22 wave guide. The mechanical structure consists of a hexapod (Stewart platform) made from pultruded carbon fibre tubing. We present a tentative examination of the cryogenic Young's modulus of this material. The thermal conductivity is measured at temperatures above the range explored by Runyan and Jones, resulting in predicted conductive loads through our thermal breaks of 3...
October 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27755338/effectiveness-of-treatment-for-distal-tibial-nonunions-with-associated-complex-deformities-utilizing-a-hexapod-external-fixator
#4
John Arvesen, J Tracy Watson, Heidi Israel
OBJECTIVE: To determine the efficacy of a hexapod external fixator (TSF) and its ability to perform six-axis correction in restoring deformities associated with distal tibial nonunions. DESIGN: Consecutive retrospective case review. SETTING: St. Louis University Hospital. Level One Trauma Center. PATIENTS/PARTICIPANTS: 37 patients with distal tibial nonunion with greater than 5 degrees of deformity in any plane. Patients were excluded who were less than 18 years of age, had tibial deformities less than 5 degrees, had proximal or middle tibial deformities or had less than one year of follow up...
October 7, 2016: Journal of Orthopaedic Trauma
https://www.readbyqxmd.com/read/27714051/rational-design-of-pt-ni-co-ternary-alloy-nanoframe-crystals-as-highly-efficient-catalysts-toward-the-alkaline-hydrogen-evolution-reaction
#5
Aram Oh, Young Jin Sa, Hyeyoun Hwang, Hionsuck Baik, Jun Kim, Byeongyoon Kim, Sang Hoon Joo, Kwangyeol Lee
The rational design of highly efficient electrocatalysts for the hydrogen evolution reaction (HER) is of prime importance for establishing renewable and sustainable energy systems. The alkaline HER is particularly challenging as it involves a two-step reaction of water dissociation and hydrogen recombination, for which platinum-based binary catalysts have shown promising activity. In this work, we synthesized high performance platinum-nickel-cobalt alloy nanocatalysts for the alkaline HER through a simple synthetic route...
September 15, 2016: Nanoscale
https://www.readbyqxmd.com/read/27696666/wnt-repertoire-and-developmental-expression-patterns-in-the-crustacean-thamnocephalus-platyurus
#6
Savvas J Constantinou, Ryan M Pace, A J Stangl, Lisa M Nagy, Terri A Williams
Wnt genes are a family of conserved glycoprotein ligands that play a role in a wide variety of cell and developmental processes, from cell proliferation to axis elongation. There are 13 Wnt subfamilies found among metazoans. Eleven of these appear conserved in arthropods with a pattern of loss during evolution of as many as six subfamilies among hexapods. Here we report on Wnt genes in the branchiopod crustacean, Thamnocephalus platyurus, including the first documentation of the expression of the complete Wnt gene family in a crustacean...
December 2016: Evolution & Development
https://www.readbyqxmd.com/read/27663622/the-effect-of-six-degree-of-freedom-loading-sequence-on-the-in-vitro-compressive-properties-of-human-lumbar-spine-segments
#7
D B Amin, I M Lawless, D Sommerfeld, R M Stanley, B Ding, J J Costi
The complex, direction-dependent, poro-viscoelastic properties of the intervertebral disc (disc) suggest that investigations of the six degree of freedom (6DOF) behaviour may be susceptible to inter-test variation in mechanical response if the disc does not return to initial conditions between loading directions. No studies have quantified the effects of sequential multi-directional loading on the consistency of the compressive response of the disc throughout a 6DOF testing protocol. Therefore, the objective of this study was to determine the effect of 6DOF loading on the compressive properties (stiffness and phase angle) of human discs, as evaluated by a reference compression test performed after each single DOF test...
October 3, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/27589766/trajectory-correction-and-locomotion-analysis-of-a-hexapod-walking-robot-with-semi-round-rigid-feet
#8
Yaguang Zhu, Bo Jin, Yongsheng Wu, Tong Guo, Xiangmo Zhao
Aimed at solving the misplaced body trajectory problem caused by the rolling of semi-round rigid feet when a robot is walking, a legged kinematic trajectory correction methodology based on the Least Squares Support Vector Machine (LS-SVM) is proposed. The concept of ideal foothold is put forward for the three-dimensional kinematic model modification of a robot leg, and the deviation value between the ideal foothold and real foothold is analyzed. The forward/inverse kinematic solutions between the ideal foothold and joint angular vectors are formulated and the problem of direct/inverse kinematic nonlinear mapping is solved by using the LS-SVM...
2016: Sensors
https://www.readbyqxmd.com/read/27516737/design-of-spiking-central-pattern-generators-for-multiple-locomotion-gaits-in-hexapod-robots-by-christiansen-grammar-evolution
#9
Andres Espinal, Horacio Rostro-Gonzalez, Martin Carpio, Erick I Guerra-Hernandez, Manuel Ornelas-Rodriguez, Marco Sotelo-Figueroa
This paper presents a method to design Spiking Central Pattern Generators (SCPGs) to achieve locomotion at different frequencies on legged robots. It is validated through embedding its designs into a Field-Programmable Gate Array (FPGA) and implemented on a real hexapod robot. The SCPGs are automatically designed by means of a Christiansen Grammar Evolution (CGE)-based methodology. The CGE performs a solution for the configuration (synaptic weights and connections) for each neuron in the SCPG. This is carried out through the indirect representation of candidate solutions that evolve to replicate a specific spike train according to a locomotion pattern (gait) by measuring the similarity between the spike trains and the SPIKE distance to lead the search to a correct configuration...
2016: Frontiers in Neurorobotics
https://www.readbyqxmd.com/read/27444213/natural-vegetation-cover-in-the-landscape-and-edge-effects-differential-responses-of-insect-orders-in-a-fragmented-forest
#10
González Ezequiel, Adriana Salvo, Graciela Valladares
Human activities have led to global simplification of ecosystems, among which Neotropical dry forests are some of the most threatened. Habitat loss as well as edge effects may affect insect communities. Here, we analyzed insects sampled with pan traps in nine landscapes (at five scales, in 100-500m diameter circles) comprising cultivated fields and Chaco Serrano forests, at overall community and taxonomic order level. In total 7043 specimens and 456 species of hexapods were captured, with abundance and richness being directly related to forest cover at 500 m and higher at edges in comparison with forest interior...
July 22, 2016: Insect Science
https://www.readbyqxmd.com/read/27436997/quadrupedal-robot-locomotion-a-biologically-inspired-approach-and-its-hardware-implementation
#11
A Espinal, H Rostro-Gonzalez, M Carpio, E I Guerra-Hernandez, M Ornelas-Rodriguez, H J Puga-Soberanes, M A Sotelo-Figueroa, P Melin
A bioinspired locomotion system for a quadruped robot is presented. Locomotion is achieved by a spiking neural network (SNN) that acts as a Central Pattern Generator (CPG) producing different locomotion patterns represented by their raster plots. To generate these patterns, the SNN is configured with specific parameters (synaptic weights and topologies), which were estimated by a metaheuristic method based on Christiansen Grammar Evolution (CGE). The system has been implemented and validated on two robot platforms; firstly, we tested our system on a quadruped robot and, secondly, on a hexapod one...
2016: Computational Intelligence and Neuroscience
https://www.readbyqxmd.com/read/27422100/divergence-of-structural-strategies-for-homophilic-e-cadherin-binding-among-bilaterians
#12
Shigetaka Nishiguchi, Akira Yagi, Nobuaki Sakai, Hiroki Oda
Homophilic binding of E-cadherins through their ectodomains is fundamental to epithelial cell-cell adhesion. Despite this, E-cadherin ectodomains have evolved differently in the vertebrate and insect lineages. Of the five rod-like, tandemly aligned extracellular cadherin domains of vertebrate E-cadherin, the tip extracellular cadherin domain plays a pivotal role in binding interactions. Comparatively, the six consecutive N-terminal extracellular cadherin domains of Drosophila E-cadherin, DE-cadherin (also known as Shotgun), can mediate adhesion; however, the underlying mechanism is unknown...
September 1, 2016: Journal of Cell Science
https://www.readbyqxmd.com/read/27419002/analysis-of-the-non-reciprocating-legged-gait-for-a-hexapod-robot-based-on-the-epaddle-egm
#13
Jinglei Zhao, Huayan Pu, Jun Zou, Yi Sun, Shugen Ma
A novel eccentric paddle mechanism based on the epicyclic gear mechanism (ePaddle-EGM) has been proposed to enhance the mobility of amphibious robot for multi-terrain tasks with diverse locomotion gaits. This paper presents a brief description for this mechanism. Based on the feature of ePaddle-EGM, a unique non-reciprocating legged gait planning method is proposed. This method could minimize the negative effect of backlash between gear mesh in the epicyclic gear mechanism. Furthermore, the stable tripod gait for the ePaddle-EGM-based hexapod robot is designed...
2016: Robotics and Biomimetics
https://www.readbyqxmd.com/read/27353342/facile-synthesis-of-complex-shaped-pt-cu-alloy-architectures
#14
Farhat Nosheen, Bing Ni, Xiaobin Xu, Haozhou Yang, Zhicheng Zhang, Xun Wang
Several intricate Pt-Cu alloy architectures have been synthesized including hexapod backbones with stretchers and caved octahedron like hexapods, as well as some other intermediates with complex structures. The mechanistic study indicates that the shape is realized via a competitive effect between etching and growth induced by different chemicals.
July 21, 2016: Nanoscale
https://www.readbyqxmd.com/read/27291789/effect-of-degeneration-on-the-six-degree-of-freedom-mechanical-properties-of-human-lumbar-spine-segments
#15
Dhara B Amin, Dana Sommerfeld, Isaac M Lawless, Richard M Stanley, Boyin Ding, John J Costi
While the effects of disc degeneration on compression and rotation motions have been studied, there is no data for shear loading. Clinical research has shown that those with low back pain (a potential consequence of degeneration) experience a 75% greater lateral shear force than those without it. Therefore, the aim was to compare the effect of degeneration on spine segment stiffness and phase angle in each of six degree of freedom (6DOF) loading directions. Fourteen intact functional spinal units (FSU) were dissected from human lumbar spines (mean (SD) age 76...
August 2016: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
https://www.readbyqxmd.com/read/27240138/3d-sers-imaging-using-chemically-synthesized-highly-symmetric-nanoporous-silver-microparticles
#16
Sanpon Vantasin, Wei Ji, Yoshito Tanaka, Yasutaka Kitahama, Mengfan Wang, Kanet Wongravee, Harnchana Gatemala, Sanong Ekgasit, Yukihiro Ozaki
3D surface-enhanced Raman scattering (SERS) imaging with highly symmetric 3D silver microparticles as a SERS substrate was developed. Although the synthesis method is purely chemical and does not involve lithography, the synthesized nanoporous silver microparticles possess a regular hexapod shape and octahedral symmetry. By using p-aminothiophenol (PATP) as a probe molecule, the 3D enhancement patterns of the particles were shown to be very regular and predictable, resembling the particle shape and exhibiting symmetry...
July 11, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27234444/femoral-locking-plate-failure-salvaged-with-hexapod-circular-external-fixation-a-report-of-two-cases
#17
N Ferreira, L C Marais
Femoral non-unions are difficult to treat even for the experienced orthopaedic trauma surgeon. If the non-union follows failure of modern stable internal fixation, the complexity of the management is further increased. We report two cases of stiff hypertrophic femoral non-unions after failed locking plate fixation that were successfully treated with a new hexapod circular external fixator. In addition to providing the necessary stability for functional rehabilitation and union, the hexapod circular fixator software allows gradual correction of deformities in order to restore the normal mechanical alignment of the limb...
August 2016: Strategies in Trauma and Limb Reconstruction
https://www.readbyqxmd.com/read/27224904/forces-and-moments-delivered-by-novel-thinner-pet-g-aligners-during-labiopalatal-bodily-movement-of-a-maxillary-central-incisor-an-in-vitro-study
#18
Fayez Elkholy, Falko Schmidt, Rudolf Jäger, Bernd G Lapatki
OBJECTIVE: To evaluate whether overloading of teeth can be avoided by utilizing aligners with reduced thicknesses of 0.4 mm or 0.3 mm. MATERIALS AND METHODS: The experimental setup included an acrylic maxillary jaw model with tooth 11 separated and fixed via a 3-D force-moment transducer to a hexapod for experimental movement. Aligners tested were fabricated on duplicate stone models using commercially available polyethylene terephthalate glycol (PET-G) foils with thicknesses between 0...
May 25, 2016: Angle Orthodontist
https://www.readbyqxmd.com/read/27206256/computer-hexapod-assisted-orthopaedic-surgery-for-the-correction-of-tibial-deformities
#19
Andrew Hughes, Michael Parry, Nima Heidari, Mark Jackson, Roger Atkins, Fergal Monsell
We describe the intraoperative use of the Taylor Spatial Frame to correct complex multiplanar deformities of the tibia before definitive internal stabilization using minimally invasive techniques. Thirteen consecutive procedures were performed in 12 patients. All deformities of the tibia were assessed with standardized radiographs allowing estimation of the center of rotation of angulation (CORA) or multiple CORA for multiplanar deformities. The cause of the deformity included both posttraumatic and metabolic conditions...
July 2016: Journal of Orthopaedic Trauma
https://www.readbyqxmd.com/read/27078228/hexapod-external-fixation-of-tibia-fractures-in-children
#20
Christopher A Iobst
Most tibia fractures in children can be treated nonoperatively. For fractures that do require surgery, however, the most common methods of management include plating or flexible nail insertion. Some fracture patterns, such as periphyseal fractures, fractures with bone and/or soft tissue loss, or fractures with delayed presentation, are not easily amenable to these techniques. Hexapod external fixators are especially helpful in these difficult cases. The purpose of this review is to discuss the principles of performing hexapod circular external fixation applied to pediatric tibia fractures...
June 2016: Journal of Pediatric Orthopedics
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