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  • Article
  • 01 natural sciences
  • European Commission
  • EU

  • Publication . Article . 2016
    Open Access English
    Wiebren J. Boonstra; Emma Björkvik; L. Jamila Haider; Vanessa A. Masterson;
    Publisher: Springer Japan
    Country: Sweden
    Project: EC | SES-LINK (283950)

    Social-ecological (SE) traps refer to persistent mismatches between the responses of people, or organisms, and their social and ecological conditions that are undesirable from a sustainability perspective. Until now, the occurrence of SE traps is primarily explained from a lack of adaptive capacity; not much attention is paid to other causal factors. In our article, we address this concern by theorizing the variety of human responses to SE traps and the effect of these responses on trap dynamics. Besides (adaptive) capacities, we theorize desires, abilities and opportunities as important additional drivers to explain the diversity of human responses to traps. Using these theoretical concepts, we construct a typology of human responses to SE traps, and illustrate its empirical relevance with three cases of SE traps: Swedish Baltic Sea fishery; amaXhosa rural livelihoods; and Pamir smallholder farming. We conclude with a discussion of how attention to the diversity in human response to SE traps may inform future academic research and planned interventions to prevent or dissolve SE traps.

  • Open Access English
    Douwe J.J. van Hinsbergen; Trond H. Torsvik; Stefan M. Schmid; Liviu Maţenco; Marco Maffione; Reinoud L.M. Vissers; Derya Gürer; Wim Spakman;
    Countries: Netherlands, Switzerland
    Project: EC | SINK (306810)

    The basins and orogens of the Mediterranean region ultimately result from the opening of oceans during the early break-up of Pangea since the Triassic, and their subsequent destruction by subduction accommodating convergence between the African and Eurasian Plates since the Jurassic. The region has been the cradle for the development of geodynamic concepts that link crustal evolution to continental break-up, oceanic and continental subduction, and mantle dynamics in general. The development of such concepts requires a first-order understanding of the kinematic evolution of the region for which a multitude of reconstructions have previously been proposed. In this paper, we use advances made in kinematic restoration software in the last decade with a systematic reconstruction protocol for developing a more quantitative restoration of the Mediterranean region for the last 240 million years. This restoration is constructed for the first time with the GPlates plate reconstruction software and uses a systematic reconstruction protocol that limits input data to marine magnetic anomaly reconstructions of ocean basins, structural geological constraints quantifying timing, direction, and magnitude of tectonic motion, and tests and iterations against paleomagnetic data. This approach leads to a reconstruction that is reproducible, and updatable with future constraints. We first review constraints on the opening history of the Atlantic (and Red Sea) oceans and the Bay of Biscay. We then provide a comprehensive overview of the architecture of the Mediterranean orogens, from the Pyrenees and Betic-Rif orogen in the west to the Caucasus in the east and identify structural geological constraints on tectonic motions. We subsequently analyze a newly constructed database of some 2300 published paleomagnetic sites from the Mediterranean region and test the reconstruction against these constraints. We provide the reconstruction in the form of 12 maps being snapshots from 240 to 0 Ma, outline the main features in each time-slice, and identify differences from previous reconstructions, which are discussed in the final section. Gondwana Research, 81 ISSN:1342-937X ISSN:1878-0571

  • Open Access
    Luca Deseri; G. Gentili; John M. Golden;
    Publisher: Technological University Dublin
    Country: Ireland
    Project: EC | HOTBRICKS (609758), NSF | Center for Nonlinear Anal... (0635983)

    Explicit expressions for the minimum free energy of a linear viscoelastic material and Noll’s definition of state are used here to explore spatial energy decay estimates for viscoelastic bodies, in the full dynamical case and in the quasi-static approximation. In the inertial case, Chirita et al. obtained a certain spatial decay inequality for a space–time integral over a portion of the body and over a finite time interval of the total mechanical energy. This involves the work done on histories, which is not a function of state in general. Here it is shown that for free energies which are functions of state and obey a certain reasonable property, the spatial decay of the corresponding space–time integral is stronger than the one involving the work done on the past history. It turns out that the bound obtained is optimal for the minimal free energy. Two cases are discussed for the quasi-static approximation. The first case deals with general states, so that general histories belonging to the equivalence class of any given state can be considered. The continuity of the stress functional with respect to the norm based on the minimal free energy is proved, and the energy measure based on the minimal free energy turns out to obey the decay inequality derived Chirita et al. for the quasi-static case. The second case explores a crucial point for viscoelastic materials, namely that the response is influenced by the rate of application of loads. Quite surprisingly, the analysis of this phenomenon in the context of Saint-Venant principles has never been carried out explicitly before, even in the linear case. This effect is explored by considering states, the related histories of which are sinusoidal. The spatial decay parameter is shown to be frequency-dependent, i.e. it depends on the rate of load application, and it is proved that of those considered, the most conservative estimate of the frequency-dependent decay is associated with the minimal free energy. A comparison is made of the results for sinusoidal histories at low frequencies and general histories.

  • Closed Access
    Matthias Wurdack; Tinghe Yun; Eliezer Estrecho; Nitu Syed; Semonti Bhattacharyya; Maciej Pieczarka; Ali Zavabeti; Shao-Yu Chen; Benedikt Haas; Johannes Müller; +8 more
    Publisher: Wiley
    Project: ARC | ARC Centres of Excellence... (CE170100039), EC | unLiMIt-2D (679288), ARC | Discovery Early Career Re... (DE190100100), ARC | Linkage Infrastructure, E... (LE180100030)

    Atomically thin transition metal dichalcogenide crystals (TMDCs) have extraordinary optical properties that make them attractive for future optoelectronic applications. Integration of TMDCs into practical all-dielectric heterostructures hinges on the ability to passivate and protect them against necessary fabrication steps on large scales. Despite its limited scalability, encapsulation of TMDCs in hexagonal boron nitride (hBN) currently has no viable alternative for achieving high performance of the final device. Here, it is shown that the novel, ultrathin Ga2 O3 glass is an ideal centimeter-scale coating material that enhances optical performance of the monolayers and protects them against further material deposition. In particular, Ga2 O3 capping of monolayer WS2 outperforms commercial-grade hBN in both scalability and optical performance at room temperature. These properties make Ga2 O3 highly suitable for large-scale passivation and protection of monolayer TMDCs in functional heterostructures.

  • Closed Access
    Vincenzo Palma; Filomena Castaldo; Paolo Ciambelli; Gaetano Iaquaniello; Gian Carlo Capitani;
    Publisher: Elsevier BV
    Project: EC | COMETHY (279075)

    Abstract The performance of CeO 2 -supported Pt–Ni and Pt–Co catalysts in the low temperature-Ethanol Steam Reforming (ESR) reaction has been evaluated studying the effect of the preparation method (impregnation/coprecipitation) and parameters such as dilution ratio, temperature, water-to-ethanol feed ratio and Gas Hourly Space Velocity (GHSV). The results show that impregnated samples perform better. In particular, the Pt/Ni/CeO 2 catalyst starting from 350 °C leads to a products distribution very close to the equilibrium calculations, with a low CO content that is ideal for fuel cells devices. In addition, the Co-based catalysts appear attractive in terms of hydrogen yield and coking tendency. For the Pt/Ni sample at 370 °C, the analysis of products distributions vs contact time suggests a surface reaction path involving ethanol dissociative adsorption, dehydrogenation to acetaldehyde at short contact time (5–40 ms), followed by decomposition, reforming and CO-WGS reactions, to obtain H 2 , CH 4 , CO 2 and CO. The last step is the methanation reaction, occurring at contact times higher than 100 ms, which drives the system to the equilibrium.

  • Publication . Article . 2017
    Open Access
    Xinxin Yang; Andrei Vorobiev; Andrey Generalov; Michael Andersson; Jan Stake;
    Country: Finland
    Project: EC | GrapheneCore1 (696656)

    We present a flexible terahertz (THz) detector based on a graphene field-effect transistor fabricated on a plastic substrate. At room temperature, this detector reveals voltage responsivity above 2 V/W and estimated noise equivalent power (NEP) below 3 nW/ Hz at 487 GHz. We have investigated the effects of bending strain on DC characteristics, voltage responsivity, and NEP of the detector, and the results reveal its robust performance. Our findings have shown that graphene is a promising material for the development of THz flexible technology.

  • Open Access English
    Geraint H. Jones; Matthew M. Knight; Karl Battams; Daniel C. Boice; John C. Brown; Silvio Giordano; John C. Raymond; Colin Snodgrass; Jordan K. Steckloff; Paul R. Weissman; +9 more
    Publisher: Springer Netherlands
    Countries: United States, United Kingdom, Italy, Norway, Italy, Norway, United States
    Project: NSF | Modeling Composition and ... (0908529), EC | ISANDAL (268421), NSF | Modeling Composition and ... (0908529), EC | ISANDAL (268421)

    Source at This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics.

  • Publication . Article . Preprint . 2011 . Embargo End Date: 01 Jan 2011
    Open Access
    Michael J. Kastoryano; David Reeb; Michael M. Wolf;
    Publisher: arXiv
    Project: CHIST-ERA | CQC (CQC), EC | COQUIT (233747)

    We derive upper and lower bounds on the convergence behavior of certain classes of one-parameter quantum dynamical semigroups. The classes we consider consist of tensor product channels and of channels with commuting Liouvillians. We introduce the notion of Cutoff Phenomenon in the setting of quantum information theory, and show how it exemplifies the fact that the convergence of (quantum) stochastic processes is not solely governed by the spectral gap of the transition map. We apply the new methods to show that graph states can be prepared efficiently, albeit not in constant time, by dissipation, and give the exact scaling behavior of the time to stationarity. Comment: 14 pages, 2 figures

  • Open Access English
    Prashant Kocherlakota; Luciano Rezzolla;
    Project: EC | BLACKHOLECAM (610058)

    The Rezzolla-Zhidenko (RZ) framework provides an efficient approach to characterize spherically symmetric black-hole spacetimes in arbitrary metric theories of gravity using a small number of variables [L. Rezzolla and A. Zhidenko, Phys. Rev. D. 90, 084009 (2014)]. These variables can be obtained in principle from near-horizon measurements of various astrophysical processes, thus potentially enabling efficient tests of both black-hole properties and the theory of general relativity in the strong-field regime. Here, we extend this framework to allow for the parametrization of arbitrary asymptotically-flat, spherically symmetric metrics and introduce the notion of a 11-dimensional (11D) parametrization space $\Pi$, on which each solution can be visualised as a curve or surface. An $\mathscr{L}^2$ norm on this space is used to measure the deviation of a particular compact object solution from the Schwarzschild black-hole solution. We calculate various observables, related to particle and photon orbits, within this framework and demonstrate that the relative errors we obtain are low (about $10^{-6}$). In particular, we obtain the innermost stable circular orbit (ISCO) frequency, the unstable photon-orbit impact parameter (shadow radius), the entire orbital angular speed profile for circular Kepler observers and the entire lensing deflection angle curve for various types of compact objects, including non-singular and singular black holes, boson stars and naked singularities, from various theories of gravity. Finally, we provide in a tabular form the first 11 coefficients of the fourth-order RZ parameterization needed to describe a variety of commonly used black-hole spacetimes. When comparing with the first-order RZ parameterization of astrophysical observables such as the ISCO frequency, the coefficients provided here increase the accuracy of two orders of magnitude or more. Comment: 19 pages, 2 figures, 5 tables. Comments welcome

  • Publication . Article . Other literature type . 2020
    Open Access English
    Maria Gabriella Chiariello; Viacheslav Bolnykh; Emiliano Ippoliti; Simone Meloni; Jógvan Magnus Haugaard Olsen; Thomas L. Beck; Ursula Rothlisberger; Christoph Fahlke; Paolo Carloni;
    Countries: Switzerland, Germany
    Project: EC | BioExcel-2 (823830)

    CLC channels and transporters conduct or transport various kinds of anions, with the exception of fluoride, which acts as an effective inhibitor. Here, we performed sub-nanosecond DFT-based QM/MM simulations of the E. coli anion/proton exchanger ClC-ec1 and observed that fluoride binds incoming protons within the selectivity filter, with excess protons shared with the gating glutamate E148. Depending on E148 conformation, the competition for the proton can involve either a direct F–/E148 interaction or the modulation of water molecules bridging the two anions. The direct interaction locks E148 in a conformation that does not allow for proton transport, and thus inhibits protein function.

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