The interactions of chlorinated polymers

Imperial Users onl

The Ellipsoid Factor for quantification of rods, plates and intermediate forms in 3D geometries

The Ellipsoid Factor (EF) is a method for the local determination of the rod- or plate-like nature of porous or spongy continua. EF at a point within a 3D structure is defined as the difference in axis ratios of the greatest ellipsoid which fits inside the structure and which contains the point of interest, and ranges from -1 for strongly oblate (discus-shaped) ellipsoids, to +1 for strongly prolate (javelin-shaped) ellipsoids. For an ellipsoid with axes a ≤ b ≤ c, EF = a/b – b/c. Here, EF is demonstrated in a Java plugin, Ellipsoid Factor for ImageJ, distributed in the BoneJ plugin collection. Ellipsoid Factor utilises an ellipsoid optimisation algorithm which assumes that maximal ellipsoids are centred on the medial axis, then dilates, rotates and translates slightly each ellipsoid until it cannot increase in volume any further. Ellipsoid Factor successfully identifies rods, plates and intermediate structures within trabecular bone, and summarises the distribution of geometries with an overall EF mean and standard deviation, EF histogram and Flinn diagram displaying a/b versus b/c. Ellipsoid Factor is released to the community for testing, use, and improvement

'Hidden’

‘Hidden’ is a novel exploring ideas of secrecy, self-presentation and what it means to be an artist. The two main characters are Jemima, an art student at university, and Clement. They meet at a party when Clement walks in on Jemima cutting herself. Something about Jemima reminds Clement of his sister, Hannah, who died as a result of her anorexia. Jemima is intrigued by Clement’s reaction to her cutting and finds herself drawn to the only person who knows her secret. While she finds comfort in the fact he knows something she keeps hidden, and the space of intimacy this creates, she refuses to participate actively in that intimacy, keeping him, emotionally, at an arm‘s length. Clement and Jemima travel separately to Barcelona. Clement visits before the start of the novel and returns early when Hannah is readmitted to hospital. Clement remembers Barcelona in a twist of pleasure and pain. It is where he found his artistic voice and where he felt free as an artist for the first time. At the same time, however, he feels that he deserted Hannah for art, represented by Barcelona. Since his sister‘s death, Clement has become ‘anorexic’ about art. In an attempt to control something in this uncontrollable world, he avoids seeing or creating art. Jemima, perplexed by Clement’s feelings about Barcelona and knowing nothing of Hannah, thinks that by going there she‘ll be able to connect with him, without the risk of real intimacy. At the same time, travelling alone to Barcelona appeals to Jemima as a way to escape their burgeoning relationship. In Barcelona she discovers that she will always be herself no matter where she goes. She also finds her own way of thinking about art and what it means to be an artist – very different from Clement’s. ‘Looking in a Broken Mirror: Reflections on the Split Writer and the Visual Artist Character’ is the exegesis for ‘Hidden‘. The exegesis explores the idea of split or doubled artists, looking specifically at the relationship between writer-artist and fictional character-artist. It is argued that writing about a fictional artist can be a way of exploring the creative process and the relationship between artist (writer) and artwork (novel). Margaret Atwood‘s novel Cat’s Eye is discussed as exploring a possible relationship between the artist, her life and her art. Other novels about visual artists are also discussed in relation to ‘Hidden’. The creative process and the experience of research for this project are examined, specifically in relation to the split or doubled relationship between life and art and the split between rational and creative thinking. Gaudí’s architecture, in the city of Barcelona, is considered in these contexts as a significant influence in the development of the novel.Thesis (Ph.D.) -- University of Adelaide, School of Humanities, 201

Structure model index does not measure rods and plates in trabecular bone

Structure model index (SMI) is widely used to measure rods and plates in trabecular bone. It exploits the change in surface curvature that occurs as a structure varies from spherical (SMI = 4), to cylindrical (SMI = 3) to planar (SMI = 0). The most important assumption underlying SMI is that the entire bone surface is convex and that the curvature differential is positive at all points on the surface. The intricate connections within the trabecular continuum suggest that a high proportion of the surface could be concave, violating the assumption of convexity and producing regions of negative differential. We implemented SMI in the BoneJ plugin and included the ability to measure the amounts of surface that increased or decreased in area after surface mesh dilation, and the ability to visualize concave and convex regions. We measured SMI and its positive (SMI+) and negative (SMI-) components, bone volume fraction (BV/TV), the fraction of the surface that is concave (CF), and mean ellipsoid factor (EF) in trabecular bone using 38 X-ray microtomography (XMT) images from a rat ovariectomy model of sex steroid rescue of bone loss, and 169 XMT images from a broad selection of 87 species' femora (mammals, birds, and a crocodile). We simulated bone resorption by eroding an image of elephant trabeculae and recording SMI and BV/TV at each erosion step. Up to 70%, and rarely less than 20%, of the trabecular surface is concave (CF 0.155 – 0.700). SMI is unavoidably influenced by aberrations from SMI-, which is strongly correlated with BV/TV and CF. The plate-to-rod transition in bone loss is an erroneous observation resulting from SMI's close and artefactual relationship with BV/TV. SMI cannot discern between the distinctive trabecular geometries typical of mammalian and avian bone, whereas EF clearly detects birds' more plate-like trabeculae. EF is free from confounding relationships with BV/TV and CF. SMI results reported in the literature should be treated with suspicion. We propose that EF should be used instead of SMI for measurements of rods and plates in trabecular bone

Error introduced by common reorientation algorithms in the assessment of rodent trabecular morphometry using micro‐computed tomography

Quantitative analyses of bone using micro‐computed tomography (μCT) are routinely employed in preclinical research, and virtual image reorientation to a consistent reference frame is a common processing step. The purpose of this study was to quantify error introduced by common reorientation algorithms in μCT‐based characterization of bone. Mouse and rat tibial metaphyses underwent μCT scanning at a range of resolutions (6–30 μm). A trabecular volume‐of‐interest (VOI) was manually selected. Image stacks were analyzed without rotation, following 45° In‐Plane axial rotation, and following 45° Triplanar rotation. Interpolation was performed using Nearest‐Neighbor, Linear, and Cubic interpolations. Densitometric (bone volume fraction, tissue mineral density, bone mineral density) and morphometric variables (trabecular thickness, trabecular spacing, trabecular number, structural model index) were computed for each combination of voxel size, rotation, and interpolation. Significant reorientation error was measured in all parameters, and was exacerbated at higher voxel sizes, with relatively low error at 6 and 12 μm (max. reorientation error in BV/TV was 2.9% at 6 μm, 7.7% at 12 μm and 36.5% at 30 μm). Considering densitometric parameters, Linear and Cubic interpolations introduced significant error while Nearest‐Neighbor interpolation caused minimal error, and In‐Plane rotation caused greater error than Triplanar. Morphometric error was strongly and intricately dependent on the combination of rotation and interpolation employed. Reorientation error can be eliminated by avoiding reorientation altogether or by “de‐rotating” VOIs from reoriented images back to the original reference frame prior to analysis. When these are infeasible, reorientation error can be minimized through sufficiently high resolution scanning, careful selection of interpolation type, and consistent processing of all images. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2762–2770, 2018.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146417/1/jor24039_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146417/2/jor24039.pd

Calcified tissue structure in the distal condyle of the third metacarpal bonein young Thoroughbred horses

PhDAims: To determine improvements in third metacarpal (Mc3) condylar microanatomy attributable to preconditioning exercise. To investigate developmental causes of Mc3 condylar fracture. Methods: Twelve Thoroughbred horses were raised at pasture; six received preconditioning exercise from 10 days. Calcein labels were administered 19 and 11 days prior to euthanasia at 18 months. Six horses also received 2 seasons of race-training and were euthanised at 3 years. Slices were taken from the distal Mc3 condyle in the frontal and dorsal- and palmar-oblique frontal planes, scanned with DXA and macerated (frontal slices) or embedded in PMMA (oblique slices). Articular calcified cartilage (ACC) and subchondral bone (SCB) in oblique slices were imaged using confocal scanning light microscopy and quantitative backscattered electron scanning electron microscopy. ACC and SCB in the palmar slice lateral parasagittal grooves were imaged using μCT and nanoindentation tested. Results: Characteristic spatial variations in ACC and SCB histomorphometric parameters were present, none of which was significantly related to preconditioning exercise. Thickened, aberrantly mineralised ACC was found in 13/24 parasagittal grooves in the palmar slices and on the sagittal ridge of 4/12 dorsal slices of 18-month-old horses. Deep to thickened ACC, SCB had an open marrow structure, having not adopted the buttress morphology of the normal SCB plate. SCB in 3-year-old horses had incorporated early ACC defects as notches in parasagittal grooves and a hyaline cartilage island in a sagittal ridge. ACC was less stiff and SCB more stiff in affected than unaffected parasagittal grooves. Chondroclastic resorption in the parasagittal groove may be retarded as early as 3-6 months, possibly due to localised inhibition of ACC mineralisation. Linear defects in the Mc3 parasagittal groove may develop prior to entry to race training and are not significantly affected by preconditioning exercise. Early identification of affected individuals should aid in reducing condylar fracture riskHorserace Betting Levy Board Veterinary Research Training Scholarship Overseas Research Students Awards Schem

Limb bone scaling in hopping diprotodonts and quadrupedal artiodactyls

Bone adaptation is modulated by the timing, direction, rate, and magnitude of mechanical loads. To investigate whether frequent slow, or infrequent fast, gaits could dominate bone adaptation to load, we compared scaling of the limb bones from two mammalian herbivore clades that use radically different high-speed gaits, bipedal hopping and quadrupedal galloping. Forelimb and hindlimb bones were collected from 20 artiodactyl and 15 diprotodont species (body mass M 1.05 - 1536 kg) and scanned in clinical computed tomography or X-ray microtomography. Second moment of area (Imax) and bone length (l) were measured. Scaling relations (y = axb) were calculated for l vs M for each bone and for Imax vs M and Imax vs l for every 5% of length. Imax vs M scaling relationships were broadly similar between clades despite the diprotodont forelimb being nearly unloaded, and the hindlimb highly loaded, during bipedal hopping. Imax vs l and l vs M scaling were related to locomotor and behavioural specialisations. Low-intensity loads may be sufficient to maintain bone mass across a wide range of species. Occasional high-intensity gaits might not break through the load sensitivity saturation engendered by frequent low-intensity gaits

Ethyl 2-methyl-4-phenyl­quinoline-3-carboxyl­ate

In the mol­ecule of the title compound, C19H17NO2, the quinoline ring system is planar [maximum deviation 0.021 (3) Å] and oriented with respect to the phenyl ring at a dihedral angle of 80.44 (4)°. Intra­molecular C—H⋯O inter­actions result in the formation of five- and six-membered rings having planar and envelope conformations, respectively. In the crystal structure, inter­molecular C—H⋯O inter­actions link the mol­ecules into centrosymmetric dimers forming R 2 2(12) ring motifs. π–π contacts between the rings of the quinoline system [centroid-to-centroid distance = 3.812 (1) Å] may further stabilize the structure. Two weak C—H⋯π inter­actions are also found

Factors influencing the adoption and use of web-supported teaching by academic staff at the University of Adelaide: Executive summary

Extent: 9p.Report prepared for the Deputy Vice Chancellor (Education) & Provost, supported by a University of Adelaide Learning and Teaching Development Grant, June 2003.Susan Shannon, Loene Doub

Factors influencing the adoption and use of web-supported teaching by academic staff at the University of Adelaide

Report prepared for the Deputy Vice Chancellor (Education) & Provost, supported by a University of Adelaide Learning and Teaching Development Grant. Extent: 157p.Susan Shannon, Loene Doub