8,348 research outputs found

    Nature, society and social change

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    Environmental destruction has become an everyday reality in the contemporary world. Major concerns are being put forward regarding the dangers to the environment in general and to human societies in particular, with strong focus currently being put on climate change. Sociology has an important role to play in the analysis of environmental problems. The interaction between nature and society can be analysed through the concept of overdetermination. At the same time, the social construction on environmental problems is imperative for environmental issues to reach the agenda. An active environmental sociology which is as much concerned with analysis as it is with social change, should clearly highlight that claimsmaking and political strategy is imperative in the tackling of environmental issues within the public sphere.peer-reviewe

    Nonlinear dynamics of Shear Alfv\'en fluctuations in Divertor Tokamak Test facility plasmas

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    Following the analysis on linear spectra of shear Alfv\'en fluctuations excited by energetic particles (EPs) in the Divertor Tokamak Test (DTT) facility plasmas [T. Wang et al., Phys. Plasmas 25, 062509 (2018)], in this work, nonlinear dynamics of the corresponding mode saturation and the fluctuation induced EP transport is studied by hybrid magnetohydrodynamic-gyrokinetic simulations. For the reversed shear Alfv\'en eigenmode driven by magnetically trapped EP precession resonance in the central core region of DTT plasmas, the saturation is mainly due to radial decoupling of resonant trapped EPs. Consistent with the wave-EP resonance structure, EP transport occurs in a similar scale to the mode width. On the other hand, passing EP transport is analyzed in detail for toroidal Alfv\'en eigenmode in the outer core region, with mode drive from both passing and trapped EPs. It is shown that passing EPs experience only weak redistributions in the weakly unstable case; and the transport extends to meso-scale diffusion in the strongly unstable case, due to orbit stochasticity induced by resonance overlap. Here, weakly/strongly unstable regime is determined by Chirikov condition for resonance overlap. This work then further illuminates rich and diverse nonlinear EP dynamics related to burning plasma studies, and the capability of DTT to address these key physics.Comment: 32 pages, 20 figure

    Lobbying in Malta : environmental NGOs and social capital

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    This paper explores the usage of social capital by Maltese Environmental Non-Governmental Organisations in their lobbying strategies and access to resources, particularly within the context of Malta as a new EU member state. The findings of the empirical research carried out in this regard show that as regards lobbying, Maltese ENGOs tend to prefer forming homogenous alliances with similar organisations. Besides, there is no direct link between access to resources and usage of social capital.peer-reviewe

    MagAO: Status and on-sky performance of the Magellan adaptive optics system

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    MagAO is the new adaptive optics system with visible-light and infrared science cameras, located on the 6.5-m Magellan "Clay" telescope at Las Campanas Observatory, Chile. The instrument locks on natural guide stars (NGS) from 0th^\mathrm{th} to 16th^\mathrm{th} RR-band magnitude, measures turbulence with a modulating pyramid wavefront sensor binnable from 28x28 to 7x7 subapertures, and uses a 585-actuator adaptive secondary mirror (ASM) to provide flat wavefronts to the two science cameras. MagAO is a mutated clone of the similar AO systems at the Large Binocular Telescope (LBT) at Mt. Graham, Arizona. The high-level AO loop controls up to 378 modes and operates at frame rates up to 1000 Hz. The instrument has two science cameras: VisAO operating from 0.5-1 μ\mum and Clio2 operating from 1-5 μ\mum. MagAO was installed in 2012 and successfully completed two commissioning runs in 2012-2013. In April 2014 we had our first science run that was open to the general Magellan community. Observers from Arizona, Carnegie, Australia, Harvard, MIT, Michigan, and Chile took observations in collaboration with the MagAO instrument team. Here we describe the MagAO instrument, describe our on-sky performance, and report our status as of summer 2014.Comment: 13 pages, 11 figures, to appear in Proc. SPIE 9148-

    The politics of Bluefin tuna in Malta

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    This paper analyzes the politics of bluefin tuna in Malta within the first years of EU accession (2004-9). The paper concludes that despite making certain impacts, ENGOs were unsuccessful in creating a hegemonic formation to stop the fishing of bluefin tuna until stocks recover.peer-reviewe

    Recovering pyramid WS gain in non-common path aberration correction mode via deformable lens

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    It is by now well known that pyramid based wavefront sensors, once in closed loop, have the capability to improve more and more the gain as the reference natural star image size is getting smaller on the pyramid pin. Especially in extreme adaptive optics applications, in order to correct the non-common path aberrations between the scientific and sensing channel, it is common use to inject a certain amount of offset wavefront deformation into the DM(s), departing at the same time the pyramid from the optimal working condition. In this paper we elaborate on the possibility to correct the low order non-common path aberrations at the pyramid wavefront sensor level by means of an adaptive refractive lens placed on the optical path before the pyramid itself, allowing the mitigation of the gain loss
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