How pigeons couple three-dimensional elbow and wrist motion to morph their wings

Birds change the shape and area of their wings to an exceptional degree, surpassing insects, bats and aircraft in their ability to morph their wings for a variety of tasks. This morphing is governed by a musculoskeletal system, which couples elbow and wrist motion. Since the discovery of this effect in 1839, the planar ‘drawing parallels’ mechanism has been used to explain the coupling. Remarkably, this mechanism has never been corroborated from quantitative motion data. Therefore, we measured how the wing skeleton of a pigeon ( Columba livia ) moves during morphing. Despite earlier planar assumptions, we found that the skeletal motion paths are highly three-dimensional and do not lie in the anatomical plane, ruling out the ‘drawing parallels’ mechanism. Furthermore, micro-computed tomography scans in seven consecutive poses show how the two wrist bones contribute to morphing, particularly the sliding ulnare. From these data, we infer the joint types for all six bones that form the wing morphing mechanism and corroborate the most parsimonious mechanism based on least-squares error minimization. Remarkably, the algorithm shows that all optimal four-bar mechanisms either lock, are unable to track the highly three-dimensional bone motion paths, or require the radius and ulna to cross for accuracy, which is anatomically unrealistic. In contrast, the algorithm finds that a six-bar mechanism recreates the measured motion accurately with a parallel radius and ulna and a sliding ulnare. This revises our mechanistic understanding of how birds morph their wings, and offers quantitative inspiration for engineering morphing wings.

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Soft biohybrid morphing wings with feathers underactuated by wrist and finger motion

Science Robotics ◽

10.1126/scirobotics.aay1246 ◽

2020 ◽

Vol 5 (38) ◽

pp. eaay1246 ◽

Cited By ~ 13

Author(s):

Eric Chang ◽

Laura Y. Matloff ◽

Amanda K. Stowers ◽

David Lentink

Keyword(s):

Degrees Of Freedom ◽

Transfer Functions ◽

Columba Livia ◽

Flight Tests ◽

Morphing Wings ◽

Finger Motion ◽

Control Flight ◽

Wing Morphing ◽

Control Principle ◽

Flexion And Extension

Since the Wright Flyer, engineers have strived to develop flying machines with morphing wings that can control flight as deftly as birds. Birds morph their wing planform parameters simultaneously—including sweep, span, and area—in a way that has proven to be particularly challenging to embody robotically. Previous solutions have primarily centered around the classical aerospace paradigm of controlling every degree of freedom to ensure predictable performance, but underperform compared with birds. To understand how birds accomplish wing morphing, we measured the kinematics of wing flexion and extension in common pigeons, Columba livia. The skeletal and feather kinematics show that the 20 primary and 20 secondary feathers are coordinated via approximately linear transfer functions controlled by wrist and finger motion. To replicate this control principle in a robot, we developed a biohybrid morphing wing with real feathers to understand the underlying design principles. The outcome, PigeonBot, embodies 42 degrees of freedom that control the position of 40 elastically connected feathers via four servo-actuated wrist and finger joints. Our flight tests demonstrate that the soft feathered wings morph rapidly and robustly under aerodynamic loading. They not only enable wing morphing but also make robot interactions safer, the wing more robust to crashing, and the wing reparable via “preening.” In flight tests, we found that both asymmetric wrist and finger motion can initiate turn maneuvers—evidence that birds may use their fingers to steer in flight.

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Characterization of Darai Limestone Composition and Porosity Using Data-Constrained Modeling and Comparison with Xenon K-Edge Subtraction Imaging

Microscopy and Microanalysis ◽

10.1017/s1431927615000653 ◽

2015 ◽

Vol 21 (4) ◽

pp. 961-968 ◽

Cited By ~ 4

Author(s):

Sheridan C. Mayo ◽

Sam Y.S. Yang ◽

Marina Pervukhina ◽

Michael B. Clennell ◽

Lionel Esteban ◽

...

Keyword(s):

Three Dimensional ◽

Micro Computed Tomography ◽

Mineral Phases ◽

Limestone Sample ◽

Computed Tomography Scans ◽

Sample Characterization ◽

Dimensional Distribution ◽

Using Data ◽

Porosity Measurements

AbstractData-constrained modeling is a method that enables three-dimensional distribution of mineral phases and porosity in a sample to be modeled based on micro-computed tomography scans acquired at different X-ray energies. Here we describe an alternative method for measuring porosity, synchrotron K-edge subtraction using xenon gas as a contrast agent. Results from both methods applied to the same Darai limestone sample are compared. Reasonable agreement between the two methods and with other porosity measurements is obtained. The possibility of a combination of data-constrained modeling and K-edge subtraction methods for more accurate sample characterization is discussed.

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A preliminary study of three-dimensional reconstruction of the human osseous labyrinth from micro-computed tomography scans

Folia Morphologica ◽

10.5603/fm.2013.0003 ◽

2013 ◽

Vol 72 (1) ◽

pp. 17-21 ◽

Cited By ~ 2

Author(s):

J. Skrzat ◽

A. Wróbel ◽

J. Walocha

Keyword(s):

Computed Tomography ◽

Three Dimensional ◽

Three Dimensional Reconstruction ◽

Micro Computed Tomography ◽

Computed Tomography Scans ◽

Dimensional Reconstruction ◽

Preliminary Study

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Application of subject-specific adaptive mechanical loading for bone healing in a mouse tail vertebral defect

Scientific Reports ◽

10.1038/s41598-021-81132-8 ◽

2021 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Angad Malhotra ◽

Matthias Walle ◽

Graeme R. Paul ◽

Gisela A. Kuhn ◽

Ralph Müller

Keyword(s):

Mechanical Loading ◽

Bone Defect ◽

Bone Healing ◽

Three Dimensional ◽

Patient Specific ◽

Dependent Manner ◽

Micro Computed Tomography ◽

Computed Tomography Images ◽

Bone Defect Healing ◽

Subject Specific

AbstractMethods to repair bone defects arising from trauma, resection, or disease, continue to be sought after. Cyclic mechanical loading is well established to influence bone (re)modelling activity, in which bone formation and resorption are correlated to micro-scale strain. Based on this, the application of mechanical stimulation across a bone defect could improve healing. However, if ignoring the mechanical integrity of defected bone, loading regimes have a high potential to either cause damage or be ineffective. This study explores real-time finite element (rtFE) methods that use three-dimensional structural analyses from micro-computed tomography images to estimate effective peak cyclic loads in a subject-specific and time-dependent manner. It demonstrates the concept in a cyclically loaded mouse caudal vertebral bone defect model. Using rtFE analysis combined with adaptive mechanical loading, mouse bone healing was significantly improved over non-loaded controls, with no incidence of vertebral fractures. Such rtFE-driven adaptive loading regimes demonstrated here could be relevant to clinical bone defect healing scenarios, where mechanical loading can become patient-specific and more efficacious. This is achieved by accounting for initial bone defect conditions and spatio-temporal healing, both being factors that are always unique to the patient.

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Numerical study of geometric morphing wings of the 1303 UCAV

The Aeronautical Journal ◽

10.1017/aer.2021.15 ◽

2021 ◽

pp. 1-17

Author(s):

B. Nugroho ◽

J. Brett ◽

B.T. Bleckly ◽

R.C. Chin

Keyword(s):

Flight Control ◽

Numerical Study ◽

Aerodynamic Characteristics ◽

Morphing Wing ◽

Rolling Moment ◽

Wide Range ◽

Morphing Wings ◽

Wing Geometry ◽

Lift And Drag ◽

Wing Morphing

ABSTRACT Unmanned Combat Aerial Vehicles (UCAVs) are believed by many to be the future of aerial strike/reconnaissance capability. This belief led to the design of the UCAV 1303 by Boeing Phantom Works and the US Airforce Lab in the late 1990s. Because UCAV 1303 is expected to take on a wide range of mission roles that are risky for human pilots, it needs to be highly adaptable. Geometric morphing can provide such adaptability and allow the UCAV 1303 to optimise its physical feature mid-flight to increase the lift-to-drag ratio, manoeuvrability, cruise distance, flight control, etc. This capability is extremely beneficial since it will enable the UCAV to reconcile conflicting mission requirements (e.g. loiter and dash within the same mission). In this study, we conduct several modifications to the wing geometry of UCAV 1303 via Computational Fluid Dynamics (CFD) to analyse its aerodynamic characteristics produced by a range of different wing geometric morphs. Here we look into two specific geometric morphing wings: linear twists on one of the wings and linear twists at both wings (wash-in and washout). A baseline CFD of the UCAV 1303 without any wing morphing is validated against published wind tunnel data, before proceeding to simulate morphing wing configurations. The results show that geometric morphing wing influences the UCAV-1303 aerodynamic characteristics significantly, improving the coefficient of lift and drag, pitching moment and rolling moment.

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In-Vivo Degradation Behavior and Osseointegration of 3D Powder-Printed Calcium Magnesium Phosphate Cement Scaffolds

Materials ◽

10.3390/ma14040946 ◽

2021 ◽

Vol 14 (4) ◽

pp. 946

Author(s):

Katharina Kowalewicz ◽

Elke Vorndran ◽

Franziska Feichtner ◽

Anja-Christina Waselau ◽

Manuel Brueckner ◽

...

Keyword(s):

Three Dimensional ◽

Bone Substitutes ◽

Magnesium Phosphate ◽

Degradation Behavior ◽

Micro Computed Tomography ◽

Calcium Magnesium ◽

Interest In Research ◽

In Vivo Degradation ◽

Volume Decrease

Calcium magnesium phosphate cements (CMPCs) are promising bone substitutes and experience great interest in research. Therefore, in-vivo degradation behavior, osseointegration and biocompatibility of three-dimensional (3D) powder-printed CMPC scaffolds were investigated in the present study. The materials Mg225 (Ca0.75Mg2.25(PO4)2) and Mg225d (Mg225 treated with diammonium hydrogen phosphate (DAHP)) were implanted as cylindrical scaffolds (h = 5 mm, Ø = 3.8 mm) in both lateral femoral condyles in rabbits and compared with tricalcium phosphate (TCP). Treatment with DAHP results in the precipitation of struvite, thus reducing pore size and overall porosity and increasing pressure stability. Over 6 weeks, the scaffolds were evaluated clinically, radiologically, with Micro-Computed Tomography (µCT) and histological examinations. All scaffolds showed excellent biocompatibility. X-ray and in-vivo µCT examinations showed a volume decrease and increasing osseointegration over time. Structure loss and volume decrease were most evident in Mg225. Histologically, all scaffolds degraded centripetally and were completely traversed by new bone, in which the remaining scaffold material was embedded. While after 6 weeks, Mg225d and TCP were still visible as a network, only individual particles of Mg225 were present. Based on these results, Mg225 and Mg225d appear to be promising bone substitutes for various loading situations that should be investigated further.

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Correlation between tympanometry volume and three-dimensional computed tomography mastoid volumetry in tympanoplasty candidates

The Journal of Laryngology & Otology ◽

10.1017/s002221512100164x ◽

2021 ◽

pp. 1-5

Author(s):

L Epprecht ◽

L Qingsong ◽

N Stenz ◽

S Hashimi ◽

T Linder

Keyword(s):

Computed Tomography ◽

Tympanic Membrane ◽

Cell Volume ◽

Radiation Injury ◽

Three Dimensional ◽

Non Invasive ◽

Tympanic Membrane Perforations ◽

Computed Tomography Scans ◽

Air Cells ◽

Mastoid Air Cells

Abstract Objective Ventilation of the middle ear and mastoid air cells is believed to play an important role in the pathogenesis of chronic ear disease. Traditionally, ventilation is assessed by computed tomography. However, this exposes patients to cumulative radiation injury. In cases with a perforation in the tympanic membrane, tympanometry potentially presents a non-invasive alternative to measure the ventilated middle-ear and mastoid air cell volume. This study hypothesised that total tympanometry volume correlates with ventilated middle-ear and mastoid air cell volume. Method Total tympanometry volume was compared with ventilated middle-ear and mastoid air cell volume on computed tomography scans in 20 tympanic membrane perforations. Results There was a high correlation between tympanometry and computed tomography volumes (r = 0.78; p < 0.001). A tympanometry volume more than 2 ml predicted good ventilation on computed tomography. Conclusion These results may help reduce the need for pre-operative computed tomography in uncomplicated cases with tympanic membrane perforations.

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The orthopedic characterization of cfap298tm304 mutants validate zebrafish to faithfully model human AIS

Scientific Reports ◽

10.1038/s41598-021-86856-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marie-Hardy Laura ◽

Cantaut-Belarif Yasmine ◽

Pietton Raphaël ◽

Slimani Lotfi ◽

Pascal-Moussellard Hugues

Keyword(s):

Cerebrospinal Fluid ◽

Three Dimensional ◽

Fluid Circulation ◽

Micro Computed Tomography ◽

Csf Flow ◽

Cerebrospinal Fluid Circulation ◽

Clinical Criteria ◽

Brain And Spinal Cord ◽

The Brain

AbstractCerebrospinal fluid (CSF) circulation relies on the beating of motile cilia projecting in the lumen of the brain and spinal cord cavities Mutations in genes involved in cilia motility disturb cerebrospinal fluid circulation and result in scoliosis-like deformities of the spine in juvenile zebrafish. However, these defects in spine alignment have not been validated with clinical criteria used to diagnose adolescent idiopathic scoliosis (AIS). The aim of this study was to describe, using orthopaedic criteria the spinal deformities of a zebrafish mutant model of AIS targeting a gene involved in cilia polarity and motility, cfap298tm304. The zebrafish mutant line cfap298tm304, exhibiting alteration of CSF flow due to defective cilia motility, was raised to the juvenile stage. The analysis of mutant animals was based on micro-computed tomography (micro-CT), which was conducted in a QUANTUM FX CALIPER, with a 59 µm-30 mm protocol. 63% of the cfap298tm304 zebrafish analyzed presented a three-dimensional deformity of the spine, that was evolutive during the juvenile phase, more frequent in females, with a right convexity, a rotational component and involving at least one dislocation. We confirm here that cfap298tm304 scoliotic individuals display a typical AIS phenotype, with orthopedic criteria mirroring patient’s diagnosis.

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