1,721,028 research outputs found
sj-docx-1-tej-10.1177_20417314221113746 – Supplemental material for Comparison of bone formation mediated by bone morphogenetic protein delivered by nanoclay gels with clinical techniques (autograft and InductOs®) in an ovine bone model
No full textSupplemental material, sj-docx-1-tej-10.1177_20417314221113746 for Comparison of bone formation mediated by bone morphogenetic protein delivered by nanoclay gels with clinical techniques (autograft and InductOs®) in an ovine bone model by Cameron Black, David Gibbs, Josephine McEwan, Janos Kanczler, Marta Peña Fernández, Gianluca Tozzi, Jonathan Dawson and Richard Oreffo in Journal of Tissue Engineering</p
The use of digital image correlation in the biomechanical area: a review
Get PDFThis paper offers an overview of the potentialities and limitations of digital image correlation (DIC) as a technique for measuring displacements and strain in biomechanical applications. This review is mainly intended for biomechanists who are not yet familiar with DIC. This review includes over 150 papers and covers different dimensional scales, from the microscopic level (tissue level) up to macroscopic one (organ level). As DIC involves a high degree of computation, and of operator- dependent decisions, reliability of displacement and strain measurements by means of DIC cannot be taken for granted. Methodological problems and existing solutions are summarized and compared, whilst open issues are addressed. Topics addressed include: preparation methods for the speckle pattern on different tissues; software settings; systematic and random error associated with DIC measurement. Applications to hard and soft tissues at different dimensional scales are described and analyzed in terms of strengths and limitations. The potentialities and limitations of DIC are highlighted, also in comparison with other experimental techniques (strain gauges, other optical techniques, digital volume correlation) and numerical methods (finite element analysis), where synergies and complementarities are discussed. In order to provide an overview accessible to different scientists working in the field of biomechanics, this paper intentionally does not report details of the algorithms and codes used in the different studies
Data-driven image mechanics (D2IM): a deep learning approach to predict displacement and strain fields from undeformed X-ray tomography images – Evaluation of bone mechanics
Get PDFThe recent advent of deep learning (DL) has enabled data-driven models to pave the way for the full exploitation of rich image datasets from which physics can be learnt. Here we propose a novel data-driven image mechanics (D2IM) approach that learns from digital volume correlation (DVC) displacement fields of vertebrae, predicting displacement and strain fields from undeformed X-ray computed tomography (XCT) images. D2IM successfully predicted the displacements in all directions, particularly in the cranio-caudal direction of the vertebra, where high correlation (R2=0.94) and generally minimal errors were obtained compared to the measured displacements. The predicted axial strain field in the cranio-caudal direction of the vertebra was also consistent in distribution with the measured one, displaying generally reduced errors in the regions within the vertebral body. The application of D2IM to lower resolution imaging in initial testing provides promising results indicating the future viability of integrating this technology into a clinical setting. This is the first study using experimental full-field measurements on bone structures from DVC to inform DL-based models such as D2IM, which represents a major contribution in the prediction of displacement and strain fields based only on the greyscale content of undeformed XCT images. In future, D2IM will incorporate a range of biological structures and loading scenarios for accurate prediction of physical fields, aiming at clinical translation for improved diagnostics
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A MicroCT in situ protocol to reveal the structure-function relation in electrospun hierarchical scaffolds for tendon/ligament regeneration
No full textElectrospun PLLA/collagen bundles (SB) and hierarchical structures (EHS) are under research as bioinspired tendon-ligament scaffolds [1]. Understanding how the hierarchical structure evolves with increasing strain is of the utmost importance to relate scaffold design and function. With this aim, a microCT in situ uniaxial loading protocol was developed. Firstly, to define reference mechanical characteristics, 4 SB and 4 EHS were tested with a monotonic ramp to failure at 0.33 %/s of strain rate. Then, 3 SB and 3 EHS underwent the microCT in situ test. Samples were submerged in PBS for two minutes before clamping for tensioning in the microCT apparatus (Skyscan 1172, Bruker, Belgium). After microCT scan at the minimum strain allowed by the load cell sensitivity (0.45 Newton, corresponding to 2% strain for SB and 0% strain for EHS), progressive strains were imposed (SB: 3-45-7-9%; EHS: 1.5-3-5-7%). Each strain was followed by 15 minutes stress-relaxation, to exhaust viscous phenomena, before each microCT acquisition. SB were scanned at a voxel size of 13 μm, with no filter and an x-ray tube voltage of 40 kV. Scanning protocol for EHS was the same, except for a higher spatial resolution (9 μm) to discriminate between different internal hierarchical levels. The region of interest (ROI) selection and morphometric analysis were performed using SkyScan CT-Analyser software. ROI extended for 6 mm in length, 2 mm below the superior fixed clamp, to avoid metal artefacts. The microCT in-situ test reported strain-load curves consistent with reference mechanical characterizations, confirming that the procedure did not alter the scaffold original mechanics, allowing the study of the evolution of their internal structure. Bundle tortuosity decreased and alignment along the mechanical axis increased with strain for EHS, while not for SB, probably because SB extensively overpassed the yielding point during the in-situ test. Contraption with increasing strain was common for both kinds of samples, as expected, but corresponded to a decrease in porosity only for SB (intra-bundle), while the presence of voids increased for EHS (inter-bundle). The microCT in situ mechanical test successfully allowed investigation, for the first time, of the relation between microstructure and mechanics of electrospun scaffolds. This protocol will be fundamental for future Digital Volume Correlation studies, for obtaining unpreceded information to design the future generations of scaffolds for tissue engineering
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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