Dispersion Relations for Thermally Excited Waves in Plasma Crystals

Thermally excited waves in a Plasma crystal were numerically simulated using a Box_Tree code. The code is a Barnes_Hut tree code proven effective in modeling systems composed of large numbers of particles. Interaction between individual particles was assumed to conform to a Yukawa potential. Particle charge, mass, density, Debye length and output data intervals are all adjustable parameters in the code. Employing a Fourier transform on the output data, dispersion relations for both longitudinal and transverse wave modes were determined. These were compared with the dispersion relations obtained from experiment as well as a theory based on a harmonic approximation to the potential. They were found to agree over a range of 0.9<k<5, where k is the shielding parameter, defined by the ratio between interparticle distance a and dust Debye length lD. This is an improvement over experimental data as current experiments can only verify the theory up to k = 1.5.Comment: 8 pages, Presented at COSPAR '0

Significance of low energy impact damage on modal parameters of composite beams by design of experiments

This paper presents an experimental study on the effects of multi-site damage on the vibration response of composite beams damaged by low energy impacts around the barely visible impact damage limit (BVID). The variation of the modal parameters with different levels of impact energy and density of damage is studied. Vibration tests have been carried out with both burst random and classical sine dwell excitations in order to compare that which of the methods among Polymax and Half Bandwidth Method is more suitable for damping estimation in the presence of damage. Design of experiments (DOE) performed on the experimental data show that natural frequency is a more sensitive parameter for damage detection than the damping ratio. It also highlighted energy of impact as the factor having a more significant effect on the modal parameters. Half Bandwidth Method is found to be unsuitable for damping estimation in the presence of damage

Driver behaviour with adaptive cruise control

This paper reports on the evaluation of adaptive cruise control (ACC) from a psychological perspective. It was anticipated that ACC would have an effect upon the psychology of driving, i.e. make the driver feel like they have less control, reduce the level of trust in the vehicle, make drivers less situationally aware, but workload might be reduced and driving might be less stressful. Drivers were asked to drive in a driving simulator under manual and ACC conditions. Analysis of variance techniques were used to determine the effects of workload (i.e. amount of traffic) and feedback (i.e. degree of information from the ACC system) on the psychological variables measured (i.e. locus of control, trust, workload, stress, mental models and situation awareness). The results showed that: locus of control and trust were unaffected by ACC, whereas situation awareness, workload and stress were reduced by ACC. Ways of improving situation awareness could include cues to help the driver predict vehicle trajectory and identify conflicts

The early Neolithic of Iraqi Kurdistan: current research at Bestansur, Shahrizor Plain

Human communities made the transition from hunter-foraging to more sedentary agriculture and herding at multiple locations across Southwest Asia through the Early Neolithic period (ca. 10,000-7000 cal. BC). Societies explored strategies involving increasing management and development of plants, animals, materials, technologies, and ideologies specific to each region whilst sharing some common attributes. Current research in the Eastern Fertile Crescent is contributing new insights into the Early Neolithic transition and the critical role that this region played. The Central Zagros Archaeological Project (CZAP) is investigating this transition in Iraqi Kurdistan, including at the earliest Neolithic settlement so far excavated in the region. In this article, we focus on results from ongoing excavations at the Early Neolithic site of Bestansur on the Shahrizor Plain, Sulaimaniyah province, in order to address key themes in the Neolithic transition

Translating research for policy: the importance of equivalence, function, and loyalty

The question of how to make academic research more useful to government, and frustration over its lack of obvious use, have long been the subject of policy makers’ and scholars’ attention. These have driven the global development of institutionalised links between the two communities, while also leading to a broad consensus as to why the goal is often not realised. In order to better explain the barriers, this paper takes the concept of “translation” very literally, and proposes an innovative approach, which analyses academic and policy practices using ideas from the humanities-based discipline of Translation Studies. This enables an exploration of what constitutes good translation, and in particular of the tension between keeping faith with the original material and users’ understandable emphasis on functionality. The conclusion is that while some aspect of original research content must be maintained, what this is cannot be prescribed: the appropriate equivalence between original and translation is always context-dependent. This throws the emphasis on the relational aspects of translatorial action for promoting “good translation”. The argument follows Christiane Nord in seeing the core issue as the moral one of a translator’s loyalty to original author and user, and so also of mutual trust between academics and civil servants. This raises important questions about how such trust can be cultivated, and so finally leads to an emphasis on the importance of an endeavour shared by researchers and policy makers, which recognises and respects their different environments and the work involved in creating useful meaning from scholarly research

High Spatial Resolution Imaging of NGC 1068 in the Mid Infrared

Mid-infrared observations of the central source of NGC 1068 have been obtained with a spatial resolution in the deconvolved image of 0.1" (~ 7pc). The central source is extended by ~1" in the north-south direction but appears unresolved in the east-west direction over most of its length. About two-thirds of its flux can be ascribed to a core structure which is itself elongated north-south and does not show a distinct unresolved compact source. The source is strongly asymmetric, extending significantly further to the north than to the south. The morphology of the mid-infrared emission appears similar to that of the radio jet, and has features which correlate with the images in [O III]. Its 12.5-24.5 micron color temperature ranges from 215 to 260 K and does not decrease smoothly with distance from the core. Silicate absorption is strongest in the core and to the south and is small in the north. The core, apparently containing two-thirds of the bolometric luminosity of the inner 4" diameter area, may be explained by a thick, dusty torus near the central AGN viewed at an angle of ~65 deg to its plane. There are, however, detailed difficulties with existing models, especially the narrow east-west width of the thin extended mid-infrared "tongue" to the north of the core. We interpret the tongue as re-processed visual and ultraviolet radiation that is strongly beamed and that originates in the AGN.Comment: 42 pages, 2 tables, 9 figures; Accepted for publication in A

Everyday stories of impact: interpreting knowledge exchange in the contemporary university

Research into the barriers of getting evidence produced by academics into policymaking processes has often highlighted the lack of research on academics and what they do, as compared to what policymakers do. This was most recently highlighted in a systematic review of the literature (Oliver et al, 2014). This paper reports on research carried out with academics who were tasked with producing evidence reviews for the UK Department for Communities and Local Government based on research funded by the UK Arts and Humanities Research Council. Using a novel co-produced methodology the academics were interviewed by an academic and a UK civil servant, with the analysis carried out by both. Using an interpretive approach, the findings identify specific meaning-making stories or practices that were enablers or barriers to producing evidence suitable for policymakers. The paper identifies three areas that affect academic behaviour at the nexus with policymaking: career biographies; disciplinary background; and the contradictory institutional pressures on academics. We conclude by arguing for a more collaborative approach between academics and policymakers. The co-produced approach also allowed us to identify the need for policymakers and civil servants to learn more about the different drivers of academics and the ways in which they work

MOST detects variability on tau Bootis possibly induced by its planetary companion

(abridged) There is considerable interest in the possible interaction between parent stars and giant planetary companions in 51 Peg-type systems. We demonstrate from MOST satellite photometry and Ca II K line emission that there has been a persistent, variable region on the surface of tau Boo A which tracked its giant planetary companion for some 440 planetary revolutions and lies ~68deg (phi=0.8) in advance of the sub-planetary point. The light curves are folded on a range of periods centered on the planetary orbital period and phase dependent variability is quantified by Fourier methods and by the mean absolute deviation (MAD) of the folded data for both the photometry and the Ca II K line reversals. The region varies in brightness on the time scale of a rotation by ~1 mmag. In 2004 it resembled a dark spot of variable depth, while in 2005 it varied between bright and dark. Over the 123 planetary orbits spanned by the photometry the variable region detected in 2004 and in 2005 are synchronised to the planetary orbital period within 0.0015 d. The Ca II K line in 2001, 2002 and 2003 also shows enhanced K-line variability centered on phi=0.8, extending coverage to some 440 planetary revolutions. The apparently constant rotation period of the variable region and its rapid variation make an explanation in terms of conventional star spots unlikely. The lack of complementary variability at phi=0.3 and the detection of the variable region so far in advance of the sub-planetary point excludes tidal excitation, but the combined photometric and Ca II K line reversal results make a good case for an active region induced magnetically on the surface of tau Boo A by its planetary companion.Comment: 7 pages, 7 figures; accepted for publication in A&