2,341 research outputs found

    Applying consumer responsibility principle in evaluating environmental load of carbon emissions

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    There is a need for a proper indicator in order to assess the environmental impact of international trade, therefore using the carbon footprint as an indicator can be relevant and useful. The aim of this study is to show from a methodological perspective how the carbon footprint, combined with input- output models can be used for analysing the impacts of international trade on the sustainable use of national resources in a country. The use of the input-output approach has the essential advantage of being able to track the transformation of goods through the economy. The study examines the environmental impact of consumption related to international trade, using the consumer responsibility principle. In this study the use of the carbon footprint and input-output methodology is shown on the example of the Hungarian consumption and the impact of international trade. Moving from a production- based approach in climate policy to a consumption-perspective principle and allocation, would also help to increase the efficiency of emission reduction targets and the evaluation of the ecological impacts of international trade

    One More Awareness Gap? The Behaviour–Impact Gap Problem

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    Preceding research has made hardly any attempt to measure the ecological impacts of pro-environmental behaviour in an objective way. Those impacts were rather supposed or calculated. The research described herein scrutinized the ecological impact reductions achieved through pro-environmental behaviour and raised the question how much of a reduction in carbon footprint can be achieved through voluntary action without actually affecting the socio-economic determinants of life. A survey was carried out in order to measure the difference between the ecological footprint of “green” and “brown” consumers. No significant difference was found between the ecological footprints of the two groups—suggesting that individual pro-environmental attitudes and behaviour do not always reduce the environmental impacts of consumption. This finding resulted in the formulation of a new proposition called the BIG (behaviour–impact gap) problem, which is an interesting addition to research in the field of environmental awareness gaps

    Fully Sampled Maps of Ices and Silicates in Front of Cepheus A East with Spitzer

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    We report the first fully sampled maps of the distribution of interstellar CO2 ices, H2O ices and total hydrogen nuclei, as inferred from the 9.7 micron silicate feature, toward the star-forming region Cepheus A East with the IRS instrument onboard the Spitzer Space Telescope. We find that the column density distributions for these solid state features all peak at, and are distributed around, the location of HW2, the protostar believed to power one of the outflows observed in this star-forming region. A correlation between the column density distributions of CO2 and water ice with that of total hydrogen indicates that the solid state features we mapped mostly arise from the same molecular clumps along the probed sight lines. We therefore derive average CO2 ice and water ice abundances with respect to the total hydrogen column density of X(CO2)_ice~1.9x10^-5 and X(H2O)_ice~7.5x10^-5. Within errors, the abundances for both ices are relatively constant over the mapped region exhibiting both ice absorptions. The fraction of CO2 ice with respect to H2O ice is also relatively constant at a value of 22% over that mapped region. A clear triple-peaked structure is seen in the CO2 ice profiles. Fits to those profiles using current laboratory ice analogs suggest the presence of both a low-temperature polar ice mixture and a high-temperature methanol-rich ice mixture along the probed sightlines. Our results further indicate that thermal processing of these ices occurred throughout the sampled region.Comment: 26 pages, 8 figures, accepted for publication in Ap

    Gas-phase CO2 emission toward Cepheus A East: the result of shock activity?

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    We report the first detection of gas-phase CO2 emission in the star-forming region Cepheus A East, obtained by spectral line mapping of the v2 bending mode at 14.98 micron with the Infrared Spectrograph (IRS) instrument onboard the Spitzer Space Telescope. The gaseous CO2 emission covers a region about 35'' x 25'' in extent, and results from radiative pumping by 15 micron continuum photons emanating predominantly from the HW2 protostellar region. The gaseous CO2 exhibits a temperature distribution ranging from 50 K to 200 K. A correlation between the gas-phase CO2 distribution and that of H2 S(2), a tracer of shock activity, indicates that the CO2 molecules originate in a cool post-shock gas component associated with the outflow powered by HW2. The presence of CO2 ice absorption features at 15.20 micron toward this region and the lack of correlation between the IR continuum emission and the CO2 gas emission distribution further suggest that the gaseous CO2 molecules are mainly sputtered off grain mantles -- by the passage of slow non-dissociative shocks with velocities of 15-30 km/s -- rather than sublimated through grain heating.Comment: 11 pages, 6 figures, accepted for publication in ApJ

    Fast Distributed Approximation for Max-Cut

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    Finding a maximum cut is a fundamental task in many computational settings. Surprisingly, it has been insufficiently studied in the classic distributed settings, where vertices communicate by synchronously sending messages to their neighbors according to the underlying graph, known as the LOCAL\mathcal{LOCAL} or CONGEST\mathcal{CONGEST} models. We amend this by obtaining almost optimal algorithms for Max-Cut on a wide class of graphs in these models. In particular, for any ϵ>0\epsilon > 0, we develop randomized approximation algorithms achieving a ratio of (1ϵ)(1-\epsilon) to the optimum for Max-Cut on bipartite graphs in the CONGEST\mathcal{CONGEST} model, and on general graphs in the LOCAL\mathcal{LOCAL} model. We further present efficient deterministic algorithms, including a 1/31/3-approximation for Max-Dicut in our models, thus improving the best known (randomized) ratio of 1/41/4. Our algorithms make non-trivial use of the greedy approach of Buchbinder et al. (SIAM Journal on Computing, 2015) for maximizing an unconstrained (non-monotone) submodular function, which may be of independent interest

    Constraints on Extrasolar Planet Populations from VLT NACO/SDI and MMT SDI and Direct Adaptive Optics Imaging Surveys: Giant Planets are Rare at Large Separations

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    We examine the implications for the distribution of extrasolar planets based on the null results from two of the largest direct imaging surveys published to date. Combining the measured contrast curves from 22 of the stars observed with the VLT NACO adaptive optics system by Masciadri et al. (2005), and 48 of the stars observed with the VLT NACO SDI and MMT SDI devices by Biller et al. (2007) (for a total of 60 unique stars; the median star for our survey is a 30 Myr K2 star at 25 pc), we consider what distributions of planet masses and semi-major axes can be ruled out by these data, based on Monte Carlo simulations of planet populations. We can set this upper limit with 95% confidence: the fraction of stars with planets with semi-major axis from 20 to 100 AU, and mass >4 M_Jup, is 20% or less. Also, with a distribution of planet mass of dN/dM ~ M^-1.16 between 0.5-13 M_Jup, we can rule out a power-law distribution for semi-major axis (dN/da ~ a^alpha) with index 0 and upper cut-off of 18 AU, and index -0.5 with an upper cut-off of 48 AU. For the distribution suggested by Cumming et al. (2007), a power-law of index -0.61, we can place an upper limit of 75 AU on the semi-major axis distribution. At the 68% confidence level, these upper limits state that fewer than 8% of stars have a planet of mass >4 M_Jup between 20 and 100 AU, and a power-law distribution for semi-major axis with index 0, -0.5, and -0.61 cannot have giant planets beyond 12, 23, and 29 AU, respectively. In general, we find that even null results from direct imaging surveys are very powerful in constraining the distributions of giant planets (0.5-13 M_Jup) at large separations, but more work needs to be done to close the gap between planets that can be detected by direct imaging, and those to which the radial velocity method is sensitive.Comment: 46 pages, 17 figures, accepted to Ap

    Modelling Clock Synchronization in the Chess gMAC WSN Protocol

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    We present a detailled timed automata model of the clock synchronization algorithm that is currently being used in a wireless sensor network (WSN) that has been developed by the Dutch company Chess. Using the Uppaal model checker, we establish that in certain cases a static, fully synchronized network may eventually become unsynchronized if the current algorithm is used, even in a setting with infinitesimal clock drifts

    Logic in Early Modern Thought

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    Logical reflection in early modern philosophy (EMP) is marked by the instability of the period, although it is more lasting (the Port-Royal Logic was nevertheless used as a handbook in philosophy courses until the end of the nineteenth century). It started in the sixteenth century and ended in the nineteenth century, a period of 300 years during which there were deep transformations in the conceptions of authority and scientific method. For the history of twentieth-century philosophy, it was the period of “classical logic,” which lasted from the Renaissance to the linguistic turn conducted by Gottlob Frege. The period was used to be thought of as centuries of little or no original contribution to logic, in which conceptions of logic were tainted by rhetoric, epistemology, and psychologism in the worst sense (Kneale and Kneale 1962; Michael 1997). From the last decades of the twentieth century, however, scholars began to regard this period more accurately with respect to reflection and changes in logic and semantics. It has recently become a promising field for historical and conceptual research; today we can say that the legacy of early modern logical reformism has a philosophical, logical, and semantic value in itself

    Dissecting the Moth: Discovery of an off-centered ring in the HD 61005 debris disk with high-resolution imaging

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    The debris disk known as "The Moth" is named after its unusually asymmetric surface brightness distribution. It is located around the ~90 Myr old G8V star HD 61005 at 34.5 pc and has previously been imaged by the HST at 1.1 and 0.6 microns. Polarimetric observations suggested that the circumstellar material consists of two distinct components, a nearly edge-on disk or ring, and a swept-back feature, the result of interaction with the interstellar medium. We resolve both components at unprecedented resolution with VLT/NACO H-band imaging. Using optimized angular differential imaging techniques to remove the light of the star, we reveal the disk component as a distinct narrow ring at inclination i=84.3 \pm 1.0{\deg}. We determine a semi-major axis of a=61.25 \pm 0.85 AU and an eccentricity of e=0.045 \pm 0.015, assuming that periastron is located along the apparent disk major axis. Therefore, the ring center is offset from the star by at least 2.75 \pm 0.85 AU. The offset, together with a relatively steep inner rim, could indicate a planetary companion that perturbs the remnant planetesimal belt. From our imaging data we set upper mass limits for companions that exclude any object above the deuterium-burning limit for separations down to 0.3". The ring shows a strong brightness asymmetry along both the major and minor axis. A brighter front side could indicate forward-scattering grains, while the brightness difference between the NE and SW components can be only partly explained by the ring center offset, suggesting additional density enhancements on one side of the ring. The swept-back component appears as two streamers originating near the NE and SW edges of the debris ring.Comment: 6 pages, 6 figures. Accepted to Astronomy and Astrophysics letter
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