Combining confocal and BSE SEM imaging for bone block surfaces

The present report presents a method for the correlation of qualitative and quantitative BSE SEM imaging with confocal scanning light microscopy (CSLM) imaging modes applied to bone samples embedded in PMMA. The SEM has a proper digital scan generator: we leave the BSE image unchanged, and match the CSLM image to it, because the CSLM scan mechanism is not digital, though the signal is digitised. Our overlapping program uses a linear transformation matrix which projects one system to the other, calculated by finding three corresponding points in BSE and CSLM pictures. BSE images are empty where cells and osteoid are present. Fluorescence mode CSLM fills in these gaps. The combination images enhance our understanding of what is going on - and re-establish the need for good cellular preservation

Nanoindentation of bone: Comparison of specimens tested in liquid and embedded in polymethylmethacrylate

Elastic modulus of bone was investigated by nanoindentation using common methods of sample preparation, data collection, and analysis, and compared to dynamic mechanical analysis (DMA: three-point bending) for the same samples. Nanoindentation (Berkovich, 5 μm and 21 μm radii spherical indenters) and DMA were performed on eight wet and dehydrated (100% ethanol), machined equine cortical bone beams. Samples were embedded in polymethylmethacrylate (PMMA) and mechanical tests repeated. Indentation direction was transverse to the bone long axis while DMA tested longitudinally, giving approximately 12% greater modulus in DMA. For wet samples, nanoindentation with spherical indenters revealed a low modulus surface layer. Estimates of the volume of material contributing to elastic modulus measurement showed that the surface layer influences the measured modulus at low loads. Consistent results were obtained for embedded tissue regardless of indenter geometry, provided appropriate methods and analysis were used. Modulus increased for nanoindentation (21 μm radius indenter) from 11.7 GPa ± 1.7 to 15.0 GPa ± 2.2 to 19.4 GPa ± 2.1, for wet, dehydrated in ethanol, and embedded conditions, respectively. The large increases in elastic modulus caused by replacing water with ethanol and ethanol with PMMA demonstrate that the role of water in fine pore space and its interaction with collagen strongly influence the mechanical behavior of the tissue

Cover Page, Table of Contents, Contributor Biographies and Editorial – Dedication to Siobhan O’Sullivan (1974-2023)

Animal Studies Journal 2023 12(1): Cover Page, Table of Contents, Contributor Biographies and Editorial – Dedication to Siobhan O’Sullivan (1974-2023

The structure and development of mammalian enamel.

PhDEnamel development and structure have been studied in a number of placental and marsupial mammals, by light microscopy; electron-microscopy; and scanning electron microscopy. The relationship between the formative cells of the enamel and its structural organisation into "prisms" and interprismatic regions has been studied in particular. The crystallites in developing enamel tend to be oriented perpendicular to its mineralising front; but their orientation may be modified by either the translatory movement which may occur between certain surfaces of the TOMES' processes of the ameloblasts and the mineralising front, or the self directed growth of groups of groups of crystallites. The presence of a repetitive (prism) pattern of crystallite orientation in formed enamel is determined by changes of orientation of and within the mineralising front: these changes are 1) the result of the peculiar mode of secretion of the enamel precursor substances from and about projections from the ameloblasts; and 2) absent during the formation of the first and last layers of enamel (formed at the enamel-dentine junction and the true enamel surface respectively) by a given group of ameloblasts: hence there are no prisms in these regions. Abrupt changes in orientation of the mineralising front determine abrupt changes in crystallite orientation in the enamel (equivalent to the "prism-sheaths" of adult enamel). The secretory territories of individual ameloblasts are only equivalent to prisms in one particular pattern: one ameloblast may be related to more than one prism. Decussation of prisms is associated with the depressions in the mineralising front filling in from alternate sides in "zones". Zone formation begins as a spiral over cusp centres. Light scattering from enamel depends on 1) the size; and 2) the orientation of its ultrastructural elements and 3) the wavelength of the incident radiation; blue light being scattered preferentially; hence the visibility of: - 1) the incremental striae; and 2) the decussating zones of prisms; and 3) the brown colour of the incremental striae when viewed by transmitted light. The calcium content in developing enamel measured by the x-ray emission microanalytical method was found to increase steadily, from the surface of the developing enamel inwards

Bounding size of homotopy groups of spheres

Let $p$ be prime. We prove that, for $n$ odd, the $p$-torsion part of $\pi_q(S^{n})$ has cardinality at most $p^{2^{\frac{1}{p-1}(q-n+3-2p)}}$, and hence has rank at most $2^{\frac{1}{p-1}(q-n+3-2p)}$. For $p=2$ these results also hold for $n$ even. The best bounds proven in the existing literature are $p^{2^{q-n+1}}$ and $2^{q-n+1}$ respectively, both due to Hans-Werner Henn. The main point of our result is therefore that the bound grows more slowly for larger primes. As a corollary of work of Henn, we obtain a similar result for the homotopy groups of a broader class of spaces.Comment: 5 pages. Two corrections in v2: First, Lemma 3.1 in v1 was wrong, and has been replaced with a different lemma which makes the same point. The error was the sentence beginning 'We will not do so here, but one can show....'. Second, since submitting v1 I discovered the paper of Iriye, which gives a result similar to Theorem 1.1 without proof. The introduction has been updated to acknowledge thi

Animal Studies Journal 2018 7 (1): Cover Page, Table of Contents, Editorial and Notes on Contributors

Animal Studies Journal 2018 7 (1): Cover Page, Table of Contents, Editorial and Notes on Contributor

Idempotents and homology of diagram algebras

This paper provides a systematization of some recent results in homology of algebras. Our main theorem gives criteria under which the homology of a diagram algebra is isomorphic to the homology of the subalgebra on diagrams having the maximum number of left-to-right connections. From this theorem, we deduce the `invertible-parameter' cases of the Temperley-Lieb and Brauer results of Boyd-Hepworth and Boyd-Hepworth-Patzt. We are also able to give a new proof of Sroka's theorem that the homology of an odd-strand Temperley-Lieb algebra vanishes, as well as an analogous result for Brauer algebras and an interpretation of both results in the even-strand case. Our proofs are relatively elementary: in particular, no auxiliary chain complexes or spectral sequences are required. We briefly discuss the relationship to cellular algebras in the sense of Graham-Lehrer.Comment: 40 pages, comments welcome. Added comments (esp Rmks 1.5, 1.15) which relate this paper to cellular algebras in the sense of Graham-Lehre

Cover Page, Table of Contents, and Contributor Biographies

Animal Studies Journal 2022 11(2): Cover Page, Table of Contents, and Contributor Biographies