Influence of wear algorithm formulation on computational-experimental corroboration

Experimental wear testing is well-established as an important part of the TKR design process. Recently, in-silico models have proved their value to corroborate long-term in-vitro results on a much shorter timescale [1]. Both FE-based models & multi-body dynamics can be used to predict contact pressures, sliding distances and cross-shear (CS). The precise mechanisms of wear are not sufficiently understood to permit analytical calculations, and so empirical formulations are used to estimate wear depths & volumes.Most early simulations were based on a modified Archard/Lancaster formulation; more recently a number of alternative formulations for cross shear have been proposed; it is unclear which is the most robust or accurate for the widest range of activities. The aim of this study was to develop and corroborate a fast in-silico wear model, and use this to compare different wear formulations

Recreation of the terminal events in physiological integrin activation.

Increased affinity of integrins for the extracellular matrix (activation) regulates cell adhesion and migration, extracellular matrix assembly, and mechanotransduction. Major uncertainties concern the sufficiency of talin for activation, whether conformational change without clustering leads to activation, and whether mechanical force is required for molecular extension. Here, we reconstructed physiological integrin activation in vitro and used cellular, biochemical, biophysical, and ultrastructural analyses to show that talin binding is sufficient to activate integrin alphaIIbbeta3. Furthermore, we synthesized nanodiscs, each bearing a single lipid-embedded integrin, and used them to show that talin activates unclustered integrins leading to molecular extension in the absence of force or other membrane proteins. Thus, we provide the first proof that talin binding is sufficient to activate and extend membrane-embedded integrin alphaIIbbeta3, thereby resolving numerous controversies and enabling molecular analysis of reconstructed integrin signaling

Financial intermediation and the role of price discrimination in a two-tier market

Though unambiguously outperforming all other financial markets in terms of liquidity, foreign exchange trading is still performed in opaque and decentralized markets. In particular, the two-tier market structure consisting of a customer segment and an interdealer segment to which only market makers have access gives rise to the possibility of price discrimination. We provide a theoretical foreign exchange pricing model that accounts for market power considerations and analyze a database of the trades of a German market maker and his cross section of end-user customers. We find that the market maker generally exerts low bargaining power vis-á-vis his customers. The dealer earns lower average spreads on trades with financial customers than commercial customers, even though the former are perceived to convey exchange-rate-relevant information. From this perspective, it appears that market makers provide interdealer market liquidity to end-user customers with cross-sectionally differing spreads. --foreign exchange,market microstructure,pricing behavior

Edward W. Said: resistance, knowledge, criticism

The prodigious output of the controversial Palestinian-American public intellectual, academic, and political activist Edward W. Said (1935-2003), continues to polarize the academic, intellectual, and political worlds, not least because of the inflammatory nature of his relationship to the vexed issue of Israel/Palestine. It is a contention of this thesis that this polarization has resulted in what are often less than critical examinations of Said's work. In short, because Said and his work remain relevant and influential, a new method of reading is required, one which not only takes account of Said's secular, 'worldly' approach to the issue of knowledge and its production, but applies the same rigour and method to the Palestinian's work in all its literary-critical, political, and personal varieties. This thesis attempts to meet that aim by testing Said's oeuvre within the rubric of his stated ambition to create a critical location from which the production of 'non-coercive' knowledge was attainable. In the context of his opposition to political Zionism and wider Western imperialism, whether Said produced, or even intended to produce knowledge that was 'non-coercive' is an extremely important question, and one that will be answered in this thesis. Formed by an introduction and three main chapters, the scope of this thesis is broad. Following an exposition of the biographical 'facts' of Said's life, Chapter One engages his late work, Out of Place. Ostensibly a memoir, Out of Place is subjected to the discipline of Said's own critical concept of 'worldliness' and placed within the much broader context of the author's oeuvre. From this location it is possible to see the memoir as one of a number of narratives competing in the political sphere. Chapter Two deals with the issue of Said's relationship to some of the key thinkers and schools of thought that seemed to inform his work, questioning whether Said resisted inculcation in powerful concepts like humanism, structuralism, post-structuralism, and Marxism or, in fact, permitted these influences to disrupt his desired critical location of homelessness. The final part of the thesis engages with Said's secular, provisional approach to knowledge. First, weaving through the tautly balanced concepts of beginnings and origins in Beginnings: Intention and Method, much of the chapter addresses Said's attack on Western knowledge production in Orientalism, where perversely he produces his own counter-monument to Western colonialism. The chapter ends with a Saidian reading of Said's three principal modes of criticism: secular, contrapuntal, and democratic. The conclusion that emerges from a Saidian,'worldly' reading of Said is perhaps both surprising and, yet, exactly as one might expect. Said was a human being, and human beings are flawed. The first intellectual line out of Said creates a restless critical and philosophical framework with the potential to undermine the second intellectual line out of Said, the political pragmatist always ready to produce coercive knowledge

Depletion of atmospheric nitrate and chloride as a consequence of the Toba Volcanic Eruption

Continuous measurements of SO42− and electrical conductivity (ECM) along the GISP2 ice core record the Toba mega‐eruption at a depth 2590.95 to 2091.25 m (71,000±5000 years ago). Major chemical species were analyzed at a resolution of 1 cm per sample for this section. An ∼6‐year long period with extremely high volcanic SO42− coincident with a 94% depletion of nitrate and 63% depletion of chloride is observed at the depth of the Toba horizon. Such a reduction of chloride in a volcanic layer preserved in an ice core has not been observed in any previous studies. The nearly complete depletion of nitrate (to 5 ppb) encountered at the Toba level is the lowest value in the entire ∼250,000 years of the GISP2 ice core record. We propose possible mechanisms to explain the depletion of nitrate and chloride resulting from this mega‐eruption

Work in progress: a novel method of creating an academic content repository

This paper outlines a project aimed at addressing the issue of the scalability of online academic support. This project is being run during the Autumn semester at the University of Southern Queensland (USQ) Toowoomba Australia, in conjunction with the Australian Digital Futures Institute. The study attached to the project will use Design-Based Research to evaluate the effectiveness of a simple, but innovative academic content and metadata creation tool referred to as Academic Assist. Academic Assist has been recently developed at USQ as a plug-in block for the moodle-based Learning Management System employed at USQ for its several hundred online subjects. The pilot project and associated study now extends over nine subjects, including three consecutive subjects in computer engineering; and covers faculties of Engineering, Education, Business, Science and Arts. Some preliminary results are presented here. Complete results of the study including acceptance surveys, expert reviews and usage statistics will be presented at FIE 2009

Suppression of allergic airway inflammation by helminth-induced regulatory T cells

Allergic diseases mediated by T helper type (Th) 2 cell immune responses are rising dramatically in most developed countries. Exaggerated Th2 cell reactivity could result, for example, from diminished exposure to Th1 cell–inducing microbial infections. Epidemiological studies, however, indicate that Th2 cell–stimulating helminth parasites may also counteract allergies, possibly by generating regulatory T cells which suppress both Th1 and Th2 arms of immunity. We therefore tested the ability of the Th2 cell–inducing gastrointestinal nematode Heligmosomoides polygyrus to influence experimentally induced airway allergy to ovalbumin and the house dust mite allergen Der p 1. Inflammatory cell infiltrates in the lung were suppressed in infected mice compared with uninfected controls. Suppression was reversed in mice treated with antibodies to CD25. Most notably, suppression was transferable with mesenteric lymph node cells (MLNC) from infected animals to uninfected sensitized mice, demonstrating that the effector phase was targeted. MLNC from infected animals contained elevated numbers of CD4(+)CD25(+)Foxp3(+) T cells, higher TGF-β expression, and produced strong interleukin (IL)-10 responses to parasite antigen. However, MLNC from IL-10–deficient animals transferred suppression to sensitized hosts, indicating that IL-10 is not the primary modulator of the allergic response. Suppression was associated with CD4(+) T cells from MLNC, with the CD4(+)CD25(+) marker defining the most active population. These data support the contention that helminth infections elicit a regulatory T cell population able to down-regulate allergen induced lung pathology in vivo