150 research outputs found

    The effect of transient overloads on the stress-rupture of glass fibre reinforced polymers

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    SIGLEAvailable from British Library Document Supply Centre- DSC:DX93936 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    Etching effects during the chemical vapor deposition of (100) diamond

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    Current theories of CVD growth on (100) diamond are unable to account for the numerous experimental observations of slow-growing, locally smooth (100)(2×1)(100)(2×1) films. In this paper we use quantum mechanical calculations of diamond surface thermochemistry and atomic-scale kinetic Monte Carlo simulations of deposition to investigate the efficacy of preferential etching as a mechanism that can help to reconcile this discrepancy. This etching mechanism allows for the removal of undercoordinated carbon atoms from the diamond surface. In the absence of etching, simulated growth on the (100)(2×1)(100)(2×1) surface is faster than growth on the (110) and (111) surfaces, and the (100) surface is atomically rough. When etching is included in the simulations, the (100) growth rates decrease to values near those observed experimentally, while the rates of growth on the other surfaces remain largely unaffected and similar to those observed experimentally. In addition, the etching mechanism promotes the growth of smooth (100) surface regions in agreement with numerous scanning probe studies. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70606/2/JCPSA6-111-9-4291-1.pd

    Statutory Assessment of the class? Supporting the additional needs of the learning context

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    This paper considers issues of funding of support for students facing difficulties in learning, and the role of assessment and labelling within this process. It explores the tensions within this process using a Foucauldian framework, and from the key perspectives of social justice and rights. Drawing on a range of literature it identifies the focus upon the individual within assessment processes around the world, and then considers in detail the strengths and weaknesses of the current form of Statutory Assessment of Special Educational Needs within England. The paper proposes an alternative funding system that resolves shortcomings within the individual approach and the English system. It suggests that a Class Funding Approach could build on a notion of justice for all, reduce the opportunities for wide variations in provision, and minimise the negative impact of current dividing practices

    Concepts of Cardiac Development in Retrospect

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    Recent research, enabled by powerful molecular techniques, has revolutionized our concepts of cardiac development. It was firmly established that the early heart tube gives rise to the left ventricle only, and that the remainder of the myocardium is recruited from surrounding mesoderm during subsequent development. Also, the cardiac chambers were shown not to be derived from the entire looping heart tube, but only from the myocardium at its outer curvatures. Intriguingly, many years ago, classic experimental embryological studies reached very similar conclusions. However, with the current scientific emphasis on molecular mechanisms, old morphological insights became underexposed. Since cardiac development occurs in an architecturally complex and dynamic fashion, molecular insights can only fully be exploited when placed in a proper morphological context. In this communication we present excerpts of important embryological studies of the pioneers of experimental cardiac embryology of the previous century, to relate insights from the past to current observations
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