4,629 research outputs found

    The Dawes Review 1: Kinematic studies of star-forming galaxies across cosmic time

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    The last seven years have seen an explosion in the number of Integral Field galaxy surveys, obtaining resolved 2D spectroscopy, especially at high-redshift. These have taken advantage of the mature capabilities of 8-10 m class telescopes and the development of associated technology such as AO. Surveys have leveraged both high spectroscopic resolution enabling internal velocity measurements and high spatial resolution from AO techniques and sites with excellent natural seeing. For the first time, we have been able to glimpse the kinematic state of matter in young, assembling star-forming galaxies and learn detailed astrophysical information about the physical processes and compare their kinematic scaling relations with those in the local Universe. Observers have measured disc galaxy rotation, merger signatures, and turbulence-enhanced velocity dispersions of gas-rich discs. Theorists have interpreted kinematic signatures of galaxies in a variety of ways (rotation, merging, outflows, and feedback) and attempted to discuss evolution vs. theoretical models and relate it to the evolution in galaxy morphology. A key point that has emerged from this activity is that substantial fractions of high-redshift galaxies have regular kinematic morphologies despite irregular photometric morphologies and this is likely due to the presence of a large number of highly gas-rich discs. There has not yet been a review of this burgeoning topic. In this first Dawes review, I will discuss the extensive kinematic surveys that have been done and the physical models that have arisen for young galaxies at high-redshift.Comment: 51 pages, 34,000 words, 16 figures. A few minor corrections have been made to the journal version. High-resolution PDF and iPad optimised ePUB versions available from http://astronomy.swin.edu.au/karl/dawe

    Review of: William Leiss & Christina Chociolko, Risk and Responsibility (1994)

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    Review of: William Leiss & Christina Chociolko, Risk and Responsibility (McGill- Queens University Press 1994). ISBN 0-7735-1177-6 (cloth) 0-7735-H1i194- 6.(paper). Abbreviations, acknowledgements, bibliography, figures, notes, preface, tables. [405 pp. Paper 55.00;cloth55.00; cloth 22.95. 3430 McTavish St., Montreal, Quebec, H3A 1X9 Canada.

    Future prospects in observational galaxy evolution: towards increased resolution

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    Future prospects in observational galaxy evolution are reviewed from a personal perspective. New insights will especially come from high-redshift integral field kinematic data and similar low-redshift observations in very large and definitive surveys. We will start to systematically probe the mass structures of galaxies and their haloes via lensing from new imaging surveys and upcoming near-IR spectroscopic surveys will finally obtain large numbers of rest frame optical spectra at high-redshift routinely. ALMA will be an important new ingredient, spatially resolving the molecular gas fuelling the high star-formation rates seen in the early Universe.Comment: 8 pages, 2 figures, Proceedings IAU Symposium No. 295, Beijing, 2013, eds. D. Thomas, A. Pasquali & I. Ferrera

    Papua New Guinea’s refugee track record and its obligations under the 2013 Regional Resettlement Arrangement with Australia

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    This paper examines Papua New Guinea\u27s track record in assessing and resettling asylum seekers, its current obligations under the 2013 Regional Resettlement Arrangement, and the sustainability of this arrangement. Introduction In the lead-up to the Australian Federal Election in September 2013, public attention focused dramatically on Papua New Guinea (PNG) in terms of the joint PNG–Australia Regional Resettlement Arrangement, the subject of a memorandum of understanding (MOU) signed on 6 August 2013. In short, Australia would transfer asylum seekers who arrived in Australia by boat after 19 July 2013 to PNG where their claim for refugee status would be assessed, under PNG law, and those found to be refugees would be resettled in PNG ‘and in any other participating regional, including Pacific Island, states’. (Nauru is the only other current participating regional state, with Cambodia considering resettlement of asylum seekers at the time of publication.) While the Migration Legislation Amendment (Regional Processing and Other Measures) Act 2012 provided for assessment of asylum seekers by PNG, it was the August 2013 Regional Resettlement Arrangement (mentioned as the 2013 Arrangement) that provided for resettlement in PNG, of asylum seekers determined to be refugees. In accordance with the 2013 Arrangement, the full cost of implementing the arrangement in PNG, that is, transfer, assessment, and resettlement, would be met by Australia. PNG has a track record related to the assessment and resettlement of asylum seekers. The discussion paper begins with a brief outline of PNG policy responses to West Papuan asylum seekers from neighbouring Indonesian Papua. It focuses on the permissive residence system (part of a PNG ‘Limited Integration’ policy) offered to West Papuan refugees living at the former United Nations High Commissioner for Refugees (UNHCR) resettlement site at East Awin in Western Province since 1997. Limitations of the permissive residence permit, particularly issues related to eligibility and permit renewal, illustrate challenges faced by the PNG government and bureaucracy to design and administer a visa system. PNG’s track record of assessing and resettling West Papuan asylum seekers since 1984 is looked at against the terms of the 2013 Arrangement, which requires PNG to determine the refugee status of asylum seekers transferred by Australia to the offshore processing centre on Manus Island, review negative determinations, and resettle in PNG those determined to be refugees. The second section considers PNG’s obligations under the terms of the 2013 Arrangement. In relation to status determination, an efficient and procedurally fair determination process requires legislation i.e., domestic refugee law, and an effective immigration bureaucracy. It can be argued that neither of these elements were present at the time of the 2013 Arrangement. However, at the time of publication of this paper in mid-2014, some status determinations and a review process had been announced. In relation to resettlement, ongoing disagreement by the PNG government over the terms of resettlement (which refugees are to be resettled, how many refugees will be resettled) threatens to undermine the terms of the 2013 Arrangement. Australia has underwritten the costs of implementing resettlement under the Arrangement, although the details are not explicit. Nor are details available about any social planning being undertaken for the resettlement of refugees. The author takes up UNHCR’s charge of a ‘xenophobic phenomenon’ in relation to the reception of non-Melanesian refugees in PNG, and offers some context. It is argued that social planning that works towards minimising inter-community tension is critical to resettlement. The 2013 Arrangement is subject to annual review by the Australian–PNG Ministerial Forum. The sustainability of the Arrangement in terms of legal challenges and security issues is the subject of the third section. Responding to the announcement of the first status determination decisions at the time of publication of this paper, the conclusion summarises some of the major issues related to PNG’s responsibilities under the Arrangement: procedurally fair assessment and review processes, and resettlement planning

    Conformational Dynamics and Thermal Cones of C-terminal Tubulin Tails in Neuronal Microtubules

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    In this paper we present a model for estimation of the C-terminal tubulin tail (CTT) dynamics in cytoskeletal microtubules of nerve cells. We show that the screened Coulomb interaction between a target CTT and the negatively charged microtubule surface as well as its immediate CTT neighbours results in confinement of the CTT motion\ud within a restricted volume referred to as a thermal cone. Within the thermal cone the CTT motion is driven by the thermal fluctuations, while outside the thermal cone the CTT interaction energy with its environment is above the thermal energy solely due to repulsion from the negatively charged microtubule surface. Computations were performed for different CTT geometries and we have found that the CTT conformation with lowest energy is perpendicular to the microtubule surface. Since the coupling between a target CTT with its neighbour CTTs is 8 orders of magnitude below the thermal energy and considering the extremely short cytosolic Debye length of 0.79 nm, our results rule out generation\ud and propagation of CTT conformational waves along the protofilament as a result of local CTT perturbations. The results as presented support a model in which the cytosolic electric fields and ionic currents generated by the neuronal excitations are "projected" onto the CTTs of underlying microtubules thus affecting their regulatory function\ud upon kinesin motion and MAP attachment/detachment

    Here where it lives … bioscleave

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    This essay introduces the work of Arakaw and Gins to interdisciplinary specialists and scholars and practitioners who are concerned with issues of art-science convergence. The co-authors discuss several points of view to the work of these artist-turned-architects and address the difficulties and challenges that their work represents in terms of the convergence and complexity of multiple dicourse and the practical challenges to embodied experience, technlogy-based approaches ot knowledge acquisition and perceptually-based learning environments
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