9,782 research outputs found

    The Impact of Institutional Structures on Transport Infrastructure Performance. A Cross-National Comparison on Various Indicators

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    It is generally acknowledged that structures and styles of decision-making have an important impact on what transport networks under these regimes look like. However, this has not been a regular line of research up to now. This paper investigates this by distinguishing four types of institutional structures that reflect various politico-administrative systems and styles in Western Europe. It seeks to construe an argument on how these types of institutional structures have divergent impacts on 1) decision-making speed on infrastructure projects, 2) satisfaction of actors in the decision making process, 3) Benefit-Cost ratios for projects, 4) modal split, 5) size of transport networks, 6) congestion in the networks and 7) investment levels. It seeks to explain why every specific type of institutional structure has a specific predicted impact on the form, type and performance of the transport networks and also takes into account that institutional structure is not the only factor with an impact on final physical outcomes. The article gives a well-substantiated argument on the supposed connection and provides some empirical evidence, but does not claim statistical significance. It sets a first step toward a new line of research and suggests this may prove fruitful as a contribution to policy making

    The enigmatic pair of dwarf galaxies Leo IV and Leo V: coincidence or common origin?

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    We have obtained deep photometry in two 1x1 degree fields covering the close pair of dwarf spheroidal galaxies (dSph) Leo IV and Leo V and part of the area in between. We find that both systems are significantly larger than indicated by previous measurements based on shallower data and also significantly elongated. With half-light radii of r_h=4'.6 +- 0'.8 (206 +- 36 pc) and r_h=2'.6 +- 0'.6 (133 +- 31 pc), respectively, they are now well within the physical size bracket of typical Milky Way dSph satellites. Their ellipticities of epsilon ~0.5 are shared by many faint (M_V>-8) Milky Way dSphs. The large spatial extent of our survey allows us to search for extra-tidal features with unprecedented sensitivity. The spatial distribution of candidate red giant branch and horizontal branch stars is found to be non-uniform at the ~3 sigma level. This substructure is aligned along the direction connecting the two systems, indicative of a possible `bridge' of extra-tidal material. Fitting the stellar distribution with a linear Gaussian model yields a significance of 4 sigma for this overdensity, a most likely FWHM of ~16 arcmin and a central surface brightness of ~32 mag arcsec^{-2}. We investigate different scenarios to explain the close proximity of Leo IV and Leo V and the possible tidal bridge between them. Orbit calculations demonstrate that they are unlikely to be remnants of a single disrupted progenitor, while a comparison with cosmological simulations shows that a chance collision between unrelated subhalos is negligibly small. Leo IV and Leo V could, however, be a bound `tumbling pair' if their combined mass exceeds 8 +- 4 x 10^9 M_sun. The scenario of an internally interacting pair appears to be the most viable explanation for this close celestial companionship. (abridged)Comment: 9 pages, 8 figures, small number of minor textual changes, accepted for publication in Astrophysical Journa

    Scanning tunnelling miscroscopy/spectroscopy and X-ray absorption spectroscopy studies of Co adatoms and anoislands on highly oriented pyrolytic graphite

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    In this paper, the scanning tunneling microscopy, scanning tunneling spectroscopy and X-ray absorption spectroscopy of cobalt adatoms and nanoislands were studied on a highly oriented pyrolytic graphite. Local electronic structure were observed by STS.\ud \u

    Balancing SoNaR: IPR versus Processing Issues in a 500-Million-Word Written Dutch Reference Corpus

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    In The Low Countries, a major reference corpus for written Dutch is beingbuilt. We discuss the interplay between data acquisition and data processingduring the creation of the SoNaR Corpus. Based on developments in traditionalcorpus compiling and new web harvesting approaches, SoNaR is designed tocontain 500 million words, balanced over 36 text types including bothtraditional and new media texts. Beside its balanced design, every text sampleincluded in SoNaR will have its IPR issues settled to the largest extentpossible. This data collection task presents many challenges because everydecision taken on the level of text acquisition has ramifications for the levelof processing and the general usability of the corpus. As far as thetraditional text types are concerned, each text brings its own processingrequirements and issues. For new media texts - SMS, chat - the problem is evenmore complex, issues such as anonimity, recognizability and citation right, allpresent problems that have to be tackled. The solutions actually lead to thecreation of two corpora: a gigaword SoNaR, IPR-cleared for research purposes,and the smaller - of commissioned size - more privacy compliant SoNaR,IPR-cleared for commercial purposes as well

    Confronting dark matter with the diphoton excess from a parent resonance decay

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    A diphoton excess with an invariant mass of about 750 GeV has been recently reported by both ATLAS and CMS experiments at LHC. While the simplest interpretation requires the resonant production of a 750 GeV (pseudo)scalar, here we consider an alternative setup, with an additional heavy parent particle which decays into a pair of 750 GeV resonances. This configuration improves the agreement between the 8 TeV and 13 TeV data. Moreover, we include a dark matter candidate in the form of a Majorana fermion which interacts through the 750 GeV portal. The invisible decays of the light resonance help to suppress additional decay channels into Standard Model particles in association with the diphoton signal. We realise our hierarchical framework in the context of an effective theory, and we analyse the diphoton signal as well as the consistency with other LHC searches. We finally address the interplay of the LHC results with the dark matter phenomenology, namely the compatibility with the relic density abundance and the indirect detection bounds.Comment: 11 figures, 2 tables, 29 page

    Predicative aspects of order theory in univalent foundations

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    We investigate predicative aspects of order theory in constructive univalent foundations. By predicative and constructive, we respectively mean that we do not assume Voevodskyā€™s propositional resizing axioms or excluded middle. Our work complements existing work on predicative mathematics by exploring what cannot be done predicatively in univalent foundations. Our first main result is that nontrivial (directed or bounded) complete posets are necessarily large. That is, if such a nontrivial poset is small, then weak propositional resizing holds. It is possible to derive full propositional resizing if we strengthen nontriviality to positivity. The distinction between nontriviality and positivity is analogous to the distinction between nonemptiness and inhabitedness. We prove our results for a general class of posets, which includes directed complete posets, bounded complete posets and sup-lattices, using a technical notion of a Ī“_V-complete poset. We also show that nontrivial locally small Ī“_V-complete posets necessarily lack decidable equality. Specifically, we derive weak excluded middle from assuming a nontrivial locally small Ī“_V-complete poset with decidable equality. Moreover, if we assume positivity instead of nontriviality, then we can derive full excluded middle. Secondly, we show that each of Zornā€™s lemma, Tarskiā€™s greatest fixed point theorem and Pataraiaā€™s lemma implies propositional resizing. Hence, these principles are inherently impredicative and a predicative development of order theory must therefore do without them. Finally, we clarify, in our predicative setting, the relation between the traditional definition of sup-lattice that requires suprema for all subsets and our definition that asks for suprema of all small families
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