1,433 research outputs found

    The sustainable transformation of business events: Sociodemographic variables as determinants of attitudes toward sustainable academic conferences

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    Purpose – This study aimed to assess whether sociodemographic variables explain significant differences in attitudes towards transforming academic conferences into more sustainable events. Design/methodology/approach – An analytical model of participants' attitudes towards sustainable conferences based on literature review as well as the theories of reasoned action and planned behavior was developed and applied to a sample of 532 surveyed individuals from 68 countries who regularly attended academic conferences in the last five years prior to 2020. The results were refined using statistical and computational techniques to achieve more empirically robust conclusions. Findings – Results reveal that sociodemographic variables such as attendees' gender and age explain differences in attitudes. Women and older adults have stronger pro-environmental attitudes regarding event sustainability. On the other hand, attitudes towards more sustainable academic conferences are quite strong and positive overall. More sustainable events' venues, catering, conference materials, and accommodations strongly influence attendees' attitudes towards more sustainable conferences. The strength of attitudes was weaker towards transportation. Originality/value – To our best knowledge, this research is the first to assess whether sociodemographic variables explain significant differences in attitudes towards the sustainable transformation of academic conferences.info:eu-repo/semantics/publishedVersio

    Downward pumping of magnetic flux as the cause of filamentary structures in sunspot penumbrae

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    The structure of a sunspot is determined by the local interaction between magnetic fields and convection near the Sun's surface. The dark central umbra is surrounded by a filamentary penumbra, whose complicated fine structure has only recently been revealed by high-resolution observations. The penumbral magnetic field has an intricate and unexpected interlocking-comb structure and some field lines, with associated outflows of gas, dive back down below the solar surface at the outer edge of the spot. These field lines might be expected to float quickly back to the surface because of magnetic buoyancy, but they remain submerged. Here we show that the field lines are kept submerged outside the spot by turbulent, compressible convection, which is dominated by strong, coherent, descending plumes. Moreover, this downward pumping of magnetic flux explains the origin of the interlocking-comb structure of the penumbral magnetic field, and the behaviour of other magnetic features near the sunspot

    Resolving the Azimuthal Ambiguity in Vector Magnetogram Data with the Divergence-Free Condition: Application to Discrete Data

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    We investigate how the divergence-free property of magnetic fields can be exploited to resolve the azimuthal ambiguity present in solar vector magnetogram data, by using line-of-sight and horizontal heliographic derivative information as approximated from discrete measurements. Using synthetic data we test several methods that each make different assumptions about how the divergence-free property can be used to resolve the ambiguity. We find that the most robust algorithm involves the minimisation of the absolute value of the divergence summed over the entire field of view. Away from disk centre this method requires the sign and magnitude of the line-of-sight derivatives of all three components of the magnetic field vector.Comment: Solar Physics, in press, 20 pages, 11 figure

    Spectral stability of noncharacteristic isentropic Navier-Stokes boundary layers

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    Building on work of Barker, Humpherys, Lafitte, Rudd, and Zumbrun in the shock wave case, we study stability of compressive, or "shock-like", boundary layers of the isentropic compressible Navier-Stokes equations with gamma-law pressure by a combination of asymptotic ODE estimates and numerical Evans function computations. Our results indicate stability for gamma in the interval [1, 3] for all compressive boundary-layers, independent of amplitude, save for inflow layers in the characteristic limit (not treated). Expansive inflow boundary-layers have been shown to be stable for all amplitudes by Matsumura and Nishihara using energy estimates. Besides the parameter of amplitude appearing in the shock case, the boundary-layer case features an additional parameter measuring displacement of the background profile, which greatly complicates the resulting case structure. Moreover, inflow boundary layers turn out to have quite delicate stability in both large-displacement and large-amplitude limits, necessitating the additional use of a mod-two stability index studied earlier by Serre and Zumbrun in order to decide stability

    Guiding cities under increased droughts: The limits to sustainable urban futures

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    Climate change is likely to increase droughts. The vulnerability of cities to droughts is increasing worldwide. Policy responses from cities to droughts lack consideration of long-term climatic and socio-economic scenarios, and focus on short-term emergency actions that disregard sustainability in the connected regional and river basin systems. We aim to explore the dynamics of the water-energy-land nexus in urban systems suffering increased climate change-related droughts, and their implications for sustainability. We complement a case study with a literature review providing cross-regional insights, and detail pervasive knowledge, policy and ambition gaps in the interaction between cities and droughts. We show that water availability with low emissions, without compromising ecosystems and with low costs to society, poses a local-scale limit to sustainable urban growth, a new concept delineating the limits to growth in cities. We conclude that urban and river basin planners need to institutionalize transparency and cross-sectoral integration in multi-sector partnerships, to consider long-term land use planning together with water and energy, and to apply integrated climate services to cities. Our study reveals the importance of including land, water and energy in long-term urban planning, and to connect them with the county, region, river basin and global scales. © 2021 The Author(s)The authors would like to express their gratitude for limited contributions, comments and discussions that helped to improve the manuscript to Muhamad Bahri, Jörg Cortekar, Mirabela Marin, Serban Octavian Davidescu, Iñaki Torres Cobián, and to two anonymous reviewers that helped to substantially improve the manuscript. Valuable feedback obtained in two conference sessions co‑lead by some of the authors (at Adaptation Futures 2018 in Cape Town, and at the 4th European Climate Change Adaptation conference, in Lisbon in 2019) is acknowledged. The authors acknowledge financial support from the project CLISWELN funded by ERA4CS. ERA4CS is an ERA-NET initiated by JPI Climate, and CLISWELN is funded by BMBF (DE), UEFISCDI (RO), BMBWF and FFG (AT), and MINECO (ES), with co-funding from the European Union (Grant 690462 ). This paper and the content included in it do not represent the opinion of the European Union, and the European Union is not responsible for any use that might be made of its content. Marta OlazabalThe authors would like to express their gratitude for limited contributions, comments and discussions that helped to improve the manuscript to Muhamad Bahri, Jörg Cortekar, Mirabela Marin, Serban Octavian Davidescu, Iñaki Torres Cobián, and to two anonymous reviewers that helped to substantially improve the manuscript. Valuable feedback obtained in two conference sessions co‑lead by some of the authors (at Adaptation Futures 2018 in Cape Town, and at the 4th European Climate Change Adaptation conference, in Lisbon in 2019) is acknowledged. The authors acknowledge financial support from the project CLISWELN funded by ERA4CS. ERA4CS is an ERA-NET initiated by JPI Climate, and CLISWELN is funded by BMBF (DE), UEFISCDI (RO), BMBWF and FFG (AT), and MINECO (ES), with co-funding from the European Union (Grant 690462 ). This paper and the content included in it do not represent the opinion of the European Union, and the European Union is not responsible for any use that might be made of its content. Marta Olazaba

    On the influence of spatial information for hyper-spectral satellite imaging characterization

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    Land-use classification for hyper-spectral satellite images requires a previous step of pixel characterization. In the easiest case, each pixel is characterized by its spectral curve. The improvementof the spectral and spatial resolution in hyper-spectral sensors has led to very large data sets. Some researches have focused on better classifiers that can handle big amounts of data. Others have faced the problem of band selection to reduce the dimensionality of the feature space. However, thanks to the improvement in the spatial resolution of the sensors, spatial information may also provide new featuresfor hyper-spectral satellite data. Here, an study on the influence of spectral-spatial features combined with an unsupervised band selection method is presented. The results show that it is possible to reduce very significantly the number of spectral bands required while having an adequate description of the spectral-spatial characteristics of the image for pixel classification tasksThis work has been partly supported by grant FPI PREDOC/2007/20 from Fundació Caixa Castelló-Bancaixa and projects CSD2007-00018 (Consolider Ingenio 2010) and AYA2008-05965-C04-04 from the Spanish Ministry of Science and Innovatio

    VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager

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    In this paper we describe in detail the implementation and main properties of a new inversion code for the polarized radiative transfer equation (VFISV: Very Fast inversion of the Stokes vector). VFISV will routinely analyze pipeline data from the Helioseismic and Magnetic Imager (HMI) on-board of the Solar Dynamics Observatory (SDO). It will provide full-disk maps (4096×\times4096 pixels) of the magnetic field vector on the Solar Photosphere every 10 minutes. For this reason VFISV is optimized to achieve an inversion speed that will allow it to invert 16 million pixels every 10 minutes with a modest number (approx. 50) of CPUs. Here we focus on describing a number of important details, simplifications and tweaks that have allowed us to significantly speed up the inversion process. We also give details on tests performed with data from the spectropolarimeter on-board of the Hinode spacecraft.Comment: 23 pages, 9 figures (2 color). Submitted for publication to Solar Physic

    A systems perspective on the interactions between urban green infrastructure and the built environment

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    This research addresses the intricate dynamics between urban green infrastructure (UGI) and the built environment, focusing on the effects of urban heat islands, building energy demand, and human health. Following the idea of the Socio-Ecological-Technological Systems framework, we investigate key indicators related to green and grey infrastructure and their interactions at the urban scale. We construct a comprehensive causal-loop diagram through an iterative approach involving literature analysis and expert consultation. The outcomes highlight the significance of urban form and green infrastructure in connecting indoor and outdoor spaces. This research enhances the understanding of systemic behavior in the urban fabric and offers insights into the complex interactions between UGI and the built environment. The approach underscores the value of iterative modeling, fostering collaborative efforts and providing a foundation for further system modeling. Future research should focus on quantitative validation of the identified connections. Additionally, connection strengths and spatial elements would be valuable extensions of the presented system model
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