787 research outputs found
Identity dynamics as a barrier to organizational change
This article seeks to explore the construction of group and professional identities in situations of organizational change. It considers empirical material drawn from a health demonstration project funded by the Scottish Executive Health Department, and uses insights from this project to discuss issues that arise from identity construction(s) and organizational change. In the course of the project studied here, a new organizational form was developed which involved a network arrangement with a voluntary sector organization and the employment of “lay-workers” in what had traditionally been a professional setting. Our analysis of the way actors made sense of their identities reveals that characterizations of both self and other became barriers to the change process. These identity dynamics were significant in determining the way people interpreted and responded to change within this project and which may relate to other change-oriented situations
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Regional and seasonal radiative forcing by perturbations to aerosol and ozone precursor emissions
Predictions of temperature and precipitation responses to changes in the anthropogenic emissions of climate forcers require the quantification of the radiative forcing exerted by those changes. This task is particularly difficult for near-term climate forcers like aerosols, methane, and ozone precursors because their short atmospheric lifetimes cause regionally and temporally inhomogeneous radiative forcings. This study quantifies specific radiative forcing, defined as the radiative forcing per unit change in mass emitted, for eight near-term climate forcers as a function of their source regions and the season of emission by using dedicated simulations by four general circulation and chemistry-transport models. Although differences in the representation of atmospheric chemistry and radiative processes in different models impede the creation of a uniform dataset, four distinct findings can be highlighted. Firstly, specific radiative forcing for sulfur dioxide and organic carbon are stronger when aerosol–cloud interactions are taken into account. Secondly, there is a lack of agreement on the sign of the specific radiative forcing of volatile organic compound perturbations, suggesting they are better avoided in climate mitigation strategies. Thirdly, the strong seasonalities of the specific radiative forcing of most forcers allow strategies to minimise positive radiative forcing based on the timing of emissions. Finally, European and shipping emissions exert stronger aerosol specific radiative forcings compared to East Asia where the baseline is more polluted. This study can therefore form the basis for further refining climate mitigation options based on regional and seasonal controls on emissions. For example, reducing summertime emissions of black carbon and wintertime emissions of sulfur dioxide in the more polluted regions is a possible way to improve air quality without weakening the negative radiative forcing of aerosols
Interactions between a Trawl Fishery and Spatial Closures for Biodiversity Conservation in the Great Barrier Reef World Heritage Area, Australia
Background\ud
The Queensland East Coast Otter Trawl Fishery (ECOTF) for penaeid shrimp fishes within Australia's Great Barrier Reef World Heritage Area (GBRWHA). The past decade has seen the implementation of conservation and fisheries management strategies to reduce the impact of the ECOTF on the seabed and improve biodiversity conservation. New information from electronic vessel location monitoring systems (VMS) provides an opportunity to review the interactions between the ECOTF and spatial closures for biodiversity conservation.\ud
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Methodology and Results\ud
We used fishing metrics and spatial information on the distribution of closures and modelled VMS data in a geographical information system (GIS) to assess change in effort of the trawl fishery from 2001–2009 and to quantify the exposure of 70 reef, non-reef and deep water bioregions to trawl fishing. The number of trawlers and the number of days fished almost halved between 2001 and 2009 and new spatial closures introduced in 2004 reduced the area zoned available for trawl fishing by 33%. However, we found that there was only a relatively minor change in the spatial footprint of the fishery as a result of new spatial closures. Non-reef bioregions benefited the most from new spatial closures followed by deep and reef bioregions.\ud
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Conclusions/Significance\ud
Although the catch of non target species remains an issue of concern for fisheries management, the small spatial footprint of the ECOTF relative to the size of the GBRWHA means that the impact on benthic habitats is likely to be negligible. The decline in effort as a result of fishing industry structural adjustment, increasing variable costs and business decisions of fishers is likely to continue a trend to fish only in the most productive areas. This will provide protection for most benthic habitats without any further legislative or management intervention
Directly Imaging Rocky Planets from the Ground
Over the past three decades instruments on the ground and in space have
discovered thousands of planets outside the solar system. These observations
have given rise to an astonishingly detailed picture of the demographics of
short-period planets, but are incomplete at longer periods where both the
sensitivity of transit surveys and radial velocity signals plummet. Even more
glaring is that the spectra of planets discovered with these indirect methods
are either inaccessible (radial velocity detections) or only available for a
small subclass of transiting planets with thick, clear atmospheres. Direct
detection can be used to discover and characterize the atmospheres of planets
at intermediate and wide separations, including non-transiting exoplanets.
Today, a small number of exoplanets have been directly imaged, but they
represent only a rare class of young, self-luminous super-Jovian-mass objects
orbiting tens to hundreds of AU from their host stars. Atmospheric
characterization of planets in the <5 AU regime, where radial velocity (RV)
surveys have revealed an abundance of other worlds, is technically feasible
with 30-m class apertures in combination with an advanced AO system,
coronagraph, and suite of spectrometers and imagers. There is a vast range of
unexplored science accessible through astrometry, photometry, and spectroscopy
of rocky planets, ice giants, and gas giants. In this whitepaper we will focus
on one of the most ambitious science goals --- detecting for the first time
habitable-zone rocky (<1.6 R_Earth) exoplanets in reflected light around nearby
M-dwarfsComment: 8 pages, 1 figure, Astro2020 Science White Pape
Accreting Protoplanets in the LkCa 15 Transition Disk
Exoplanet detections have revolutionized astronomy, offering new insights
into solar system architecture and planet demographics. While nearly 1900
exoplanets have now been discovered and confirmed, none are still in the
process of formation. Transition discs, protoplanetary disks with inner
clearings best explained by the influence of accreting planets, are natural
laboratories for the study of planet formation. Some transition discs show
evidence for the presence of young planets in the form of disc asymmetries or
infrared sources detected within their clearings, as in the case of LkCa 15.
Attempts to observe directly signatures of accretion onto protoplanets have
hitherto proven unsuccessful. Here we report adaptive optics observations of
LkCa 15 that probe within the disc clearing. With accurate source positions
over multiple epochs spanning 2009 - 2015, we infer the presence of multiple
companions on Keplerian orbits. We directly detect H{\alpha} emission from the
innermost companion, LkCa 15 b, evincing hot (~10,000 K) gas falling deep into
the potential well of an accreting protoplanet.Comment: 35 pages, 3 figures, 1 table, 9 extended data item
Paving the Way to Future Missions: the Roman Space Telescope Coronagraph Technology Demonstration
This document summarizes how far the Nancy Grace Roman Space Telescope Coronagraph Instrument (Roman CGI) will go toward demonstrating high-contrast imaging and spectroscopic requirements for potential future exoplanet direct imaging missions, illustrated by the HabEx and LUVOIR concepts. The assessment is made for two levels of assumed CGI performance: (i) current best estimate (CBE) as of August 2020, based on laboratory results and realistic end-to-end simulations with JPL-standard Model Uncertainty Factors (MUFs); (ii) CGI design specifications inherited from Phase B requirements. We find that the predicted performance (CBE) of many CGI subsystems compares favorably with the needs of future missions, despite providing more modest point source detection limits than future missions. This is essentially due to the challenging pupil of the Roman Space Telescope; this pupil pushes the coronagraph masks sensitivities to misalignments to be commensurate with future missions. In particular, CGI will demonstrate active low-order wavefront control and photon counting capabilities at levels of performance either higher than, or comparable to, the needs of future missions
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