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  • 11
    In: Journal of Anatomy, Wiley, Vol. 235, No. 2 ( 2019-08), p. 357-378
    Abstract: Computed‐tomography‐derived ( CT ‐derived) polymesh surfaces are widely used in geometric morphometric studies. This approach is inevitably associated with decisions on scanning parameters, resolution, and segmentation strategies. Although the underlying processing steps have been shown to potentially contribute artefactual variance to three‐dimensional landmark coordinates, their effects on measurement error have rarely been assessed systematically in CT ‐based geometric morphometric studies. The present study systematically assessed artefactual variance in landmark data introduced by the use of different voxel sizes, segmentation strategies, surface simplification degrees, and by inter‐ and intra‐observer differences, and compared their magnitude to true biological variation. Multiple CT ‐derived surface variants of the anuran (Amphibia: Anura) pectoral girdle were generated by systematic changes in the factors that potentially influence the surface geometries. Twenty‐four landmarks were repeatedly acquired by different observers. The contribution of all factors to the total variance in the landmark data was assessed using random‐factor nested permanova s. Selected sets of Euclidean distances between landmark sets served further to compare the variance among factor levels. Landmark precision was assessed by landmark standard deviation and compared among observers and days. Results showed that all factors, except for voxel size, significantly contributed to measurement error in at least some of the analyses performed. In total, 6.75% of the variance in landmark data that mimicked a realistic biological study was caused by measurement error. In this landmark dataset, intra‐observer error was the major source of artefactual variance followed by inter‐observer error; the factor segmentation contributed 〈 1% and slight surface simplification had no significant effect. Inter‐observer error clearly exceeded intra‐observer error in a different landmark dataset acquired by six partly inexperienced observers. The results suggest that intra‐observer error can potentially be reduced by including a training period prior to the actual landmark acquisition task and by acquiring landmarks in as few sessions as possible. Additionally, the application of moderate and careful surface simplification and, potentially, also the use of case‐specific optimal combinations of automatic local thresholding algorithms and parameters for segmentation can help reduce intra‐observer error. If landmark data are to be acquired by several observers, it is important to ensure that all observers are consistent in landmark identification. Despite the significant amount of artefactual variance, we have shown that landmark data acquired from microCT ‐derived surfaces are precise enough to study the shape of anuran pectoral girdles. Yet, a systematic assessment of measurement error is advisable for all geometric morphometric studies.
    Type of Medium: Online Resource
    ISSN: 0021-8782 , 1469-7580
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 1474856-3
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  • 12
    Online Resource
    Online Resource
    Wiley ; 2017
    In:  Journal of Anatomy Vol. 230, No. 4 ( 2017-04), p. 497-509
    In: Journal of Anatomy, Wiley, Vol. 230, No. 4 ( 2017-04), p. 497-509
    Abstract: Scorpions have elongated metasomas that bear a telson, which is used as a stinger for venom injection. There is a remarkable diversity in the use of the stinger among scorpions, comprising defensive behavior, prey subjugation and mating. This diversity could be reflected by the shape of the telson, as different stinging behaviors will result in very different functional demands. Here we explored the diversity of telson shapes in scorpions by providing morphological measurements, such as curvature and tip angle, as well as by testing stingers under load using finite element analysis ( FEA ). FEA models were loaded with forces scaled to the surface area of the models, to allow comparison of the relative strain energy based on shape alone. Load force angle was rotated to identify the optimal stinging angle based on the lowest strain energy. Aculeus length and mean aculeus height correlated with minimal strain energy. Optimal stinging angle correlated with tip angle, and differed from the tip angle by about 28.4 ± 6.22 °. We found that species that are more venomous have long aculei (stinger barbs) with a larger radius of curvature. FEA models of these longer aculei showed basal stress concentrations, indicating a potential greater risk of basal breakage due to shape alone. Telsons with shorter and thicker aculeus shapes showed stress concentrations at the tip only. Despite these marked differences in shape, we found no difference in the scaled strain energy between groups of species that are more venomous and less venomous groups of species. These results show that scorpion stingers may be biomechanically optimized, and this may indicate different usage of the stinger in different species.
    Type of Medium: Online Resource
    ISSN: 0021-8782 , 1469-7580
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 1474856-3
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  • 13
    In: Journal of Anatomy, Wiley, Vol. 241, No. 3 ( 2022-09), p. 716-728
    Abstract: Caecilians are elongate, limbless and annulated amphibians that, as far as is known, all have an at least partly fossorial lifestyle. It has been suggested that elongate limbless vertebrates show little morphological differentiation throughout the postcranial skeleton. However, relatively few studies have explored the axial skeleton in limbless tetrapods. In this study, we used μCT data and three‐dimensional geometric morphometrics to explore regional differences in vertebral shape across a broad range of caecilian species. Our results highlight substantial differences in vertebral shape along the axial skeleton, with anterior vertebrae being short and bulky, whereas posterior vertebrae are more elongated. This study shows that despite being limbless, elongate tetrapods such as caecilians still show regional heterogeneity in the shape of individual vertebrae along the vertebral column. Further studies are needed, however, to understand the possible causes and functional consequences of the observed variation in vertebral shape in caecilians.
    Type of Medium: Online Resource
    ISSN: 0021-8782 , 1469-7580
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 1474856-3
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  • 14
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2017
    In:  Artificial Life and Robotics Vol. 22, No. 4 ( 2017-12), p. 412-420
    In: Artificial Life and Robotics, Springer Science and Business Media LLC, Vol. 22, No. 4 ( 2017-12), p. 412-420
    Type of Medium: Online Resource
    ISSN: 1433-5298 , 1614-7456
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2017
    detail.hit.zdb_id: 1480655-1
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  • 15
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2014
    In:  Scientific Reports Vol. 4, No. 1 ( 2014-06-12)
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 4, No. 1 ( 2014-06-12)
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2014
    detail.hit.zdb_id: 2615211-3
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  • 16
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2017
    In:  Journal of Crustacean Biology Vol. 37, No. 2 ( 2017-03-01), p. 142-150
    In: Journal of Crustacean Biology, Oxford University Press (OUP), Vol. 37, No. 2 ( 2017-03-01), p. 142-150
    Type of Medium: Online Resource
    ISSN: 0278-0372 , 1937-240X
    RVK:
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2017
    detail.hit.zdb_id: 2173764-2
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  • 17
    Online Resource
    Online Resource
    The Royal Society ; 2014
    In:  Journal of The Royal Society Interface Vol. 11, No. 91 ( 2014-02-06), p. 20130816-
    In: Journal of The Royal Society Interface, The Royal Society, Vol. 11, No. 91 ( 2014-02-06), p. 20130816-
    Abstract: In this study, we investigate the morphology and mechanical features of Octopus vulgaris suckers, which may serve as a model for the creation of a new generation of attachment devices. Octopus suckers attach to a wide range of substrates in wet conditions, including rough surfaces. This amazing feature is made possible by the sucker's tissues, which are pliable to the substrate profile. Previous studies have described a peculiar internal structure that plays a fundamental role in the attachment and detachment processes of the sucker. In this work, we present a mechanical characterization of the tissues involved in the attachment process, which was performed using microindentation tests. We evaluated the elasticity modulus and viscoelastic parameters of the natural tissues ( E ∼ 10 kPa) and measured the mechanical properties of some artificial materials that have previously been used in soft robotics. Such a comparison of biological prototypes and artificial material that mimics octopus-sucker tissue is crucial for the design of innovative artificial suction cups for use in wet environments. We conclude that the properties of the common elastomers that are generally used in soft robotics are quite dissimilar to the properties of biological suckers.
    Type of Medium: Online Resource
    ISSN: 1742-5689 , 1742-5662
    Language: English
    Publisher: The Royal Society
    Publication Date: 2014
    detail.hit.zdb_id: 2156283-0
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  • 18
    Online Resource
    Online Resource
    Wiley ; 2013
    In:  Journal of Morphology Vol. 274, No. 9 ( 2013-09), p. 1026-1043
    In: Journal of Morphology, Wiley, Vol. 274, No. 9 ( 2013-09), p. 1026-1043
    Abstract: Three lineages of cartilaginous fishes have independently evolved filter feeding (Lamniformes: Megachasma and Cetorhinus , Orectolobiformes: Rhincodon , and Mobulidae: Manta and Mobula ); and the structure of the branchial filters is different in each group. The filter in Rhincodon typus has been described; species within the Lamniformes have simple filamentous filters, but the anatomy and ultrastructure of the branchial filter in the mobulid rays varies and is of functional interest. In most fishes, branchial gill rakers are elongated structures located along the anterior ceratobranchial and/or epibranchial arches; however, mobulid gill rakers are highly modified, flattened, lobe‐like structures located on the anterior and posterior epibranchial elements as well as the ceratobranchials. The ultrastructure of the filter lobes can be smooth or covered by a layer of microcilia, and some are denticulated along the dorsal and ventral lobe surface. Flow through the mobulid oropharyngeal cavity differs from other filter‐feeding fishes in that water must rapidly deviate from the free stream direction. There is an abrupt 90° turn from the initial inflowing path to move through the laterally directed branchial filter pores, over the gill tissue, and out the ventrally located gill slits. The deviation in the flow must result in tangential shearing stress across the filter surface. This implies that mobulids can use cross‐flow filtration in which this shearing force serves as a mechanism to resuspend food particles initially caught by sieving or another capture mode. These particles will be transported by the cross filter flow toward the esophagus. We propose that species with cilia on the rakers augment the shear mediated movement of particles along the filter with ciliary transport. J. Morphol. 274:1026–1043, 2013. © 2013 Wiley Periodicals, Inc.
    Type of Medium: Online Resource
    ISSN: 0362-2525 , 1097-4687
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 1479991-1
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  • 19
    In: Acta Zoologica, Wiley, Vol. 93, No. 2 ( 2012-04), p. 208-221
    Type of Medium: Online Resource
    ISSN: 0001-7272
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2012
    detail.hit.zdb_id: 2019873-5
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  • 20
    Online Resource
    Online Resource
    Beilstein Institut ; 2016
    In:  Beilstein Journal of Nanotechnology Vol. 7 ( 2016-06-22), p. 893-903
    In: Beilstein Journal of Nanotechnology, Beilstein Institut, Vol. 7 ( 2016-06-22), p. 893-903
    Abstract: Frogs (Lissamphibia: Anura) use adhesive tongues to capture fast moving, elusive prey. For this, the tongues are moved quickly and adhere instantaneously to various prey surfaces. Recently, the functional morphology of frog tongues was discussed in context of their adhesive performance. It was suggested that the interaction between the tongue surface and the mucus coating is important for generating strong pull-off forces. However, despite the general notions about its importance for a successful contact with the prey, little is known about the surface structure of frog tongues. Previous studies focused almost exclusively on species within the Ranidae and Bufonidae, neglecting the wide diversity of frogs. Here we examined the tongue surface in nine different frog species, comprising eight different taxa, i.e., the Alytidae, Bombinatoridae, Megophryidae, Hylidae, Ceratophryidae, Ranidae, Bufonidae, and Dendrobatidae. In all species examined herein, we found fungiform and filiform papillae on the tongue surface. Further, we observed a high degree of variation among tongues in different frogs. These differences can be seen in the size and shape of the papillae, in the fine-structures on the papillae, as well as in the three-dimensional organization of subsurface tissues. Notably, the fine-structures on the filiform papillae in frogs comprise hair-like protrusions (Megophryidae and Ranidae), microridges (Bufonidae and Dendrobatidae), or can be irregularly shaped or absent as observed in the remaining taxa examined herein. Some of this variation might be related to different degrees of adhesive performance and may point to differences in the spectra of prey items between frog taxa.
    Type of Medium: Online Resource
    ISSN: 2190-4286
    Language: English
    Publisher: Beilstein Institut
    Publication Date: 2016
    detail.hit.zdb_id: 2583584-1
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