1,532 research outputs found

    Multimetric Supergravities

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    Making use of integral forms and superfield techniques we propose supersymmetric extensions of the multimetric gravity Lagrangians in dimensions one, two, three and four. The supersymmetric interaction potential covariantly deforms the bosonic one, producing in particular suitable super-symmetric polynomials generated by the Berezinian. As an additional application of our formalism we construct supersymmetric multi-Maxwell theories in dimensions three and four.Comment: 37 pages, Latex2e, no figure

    ICT Spatial Concentration and Growth Among European Regions

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    Since the mid of the 80’s more prosperous European regions have growing faster than less prosperous ones, determining a widening of the gap between them. A possible explanation for the increasing gap relates to the effects of producing and/or using the information and communication technologies. In this case the increasing gap can be related to both the lower concentration of ICT industries and the lower use of ICT goods in less prosperous regions. For example, as both economies of scope as well as externalities due to geographical proximity characterise ICT industries, agglomeration economies could determine a cumulative process of concentration of ICT sectors in wealthier areas. In this paper we describe the distribution of ICT among European regions and we investigate empirically some effects of the use of ICT on European regional growth. We have found a positive correlation between ICT concentration and human capital as well as between regional growth and an index of the use of ICT in Europe

    Anticorruption campaigns and the determinants of corruption in Europe

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    Several studies shows that corruption is a persistent phenomenon and that many anticorruption campaigns failed in the past. After a review of the literature of the determinants of the dynamic of corruption, our paper investigates the persisting of corruption phenomenon in Italy and in other countries. Econometric estimates, using statistics on crimes against the public administration at a provincial level, show that corruption campaign ‘Clean Hands’ started in Italy in 1990 has been effective to fight corruption. The main conclusion of our work is that anticorruption campaigns have permanent effects if they intervene at the same time on economic, political and cultural factors

    THE DETERMINANTS OF CORRUPTION IN ITALY: REGIONAL PANEL DATA ANALYSIS

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    Several measures indicate the presence of substantial corruption in Italian society. This paper investigates the determinants of corruption in Italy in the period 1963–2001 using statistics on crimes against the public administration at a regional level. Our estimates show that economic variables (government consumption, level of development) and political and cultural influences (party concentration, presence of voluntary organisations, absenteeism at national elections) significantly affect corruption in Italy

    Developments of the pinned photodiode terahertz rectifier

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    This paper presents we presents a development of the structure of the pinned photodiode terahertz rectifier, in which the metal whisker of the antenna is separated from the semiconductor by a silane oxide layer, in order to reduce the surface defectiveness. The rectifies is the basic component of an image detection system based on the structure of actual CMOS image detectors. The structure combines a nano-antenna, fabricated on the top of a standard image sensor, the rectifier, and the readout electronics. The rectifier device proposed has vertical extension of some tenths of nanometers, can be created at the foot of the nano-whisker at the end of the terahertz antenna, above the storage well

    Circular quiver gauge theories, isomonodromic deformations and WN fermions on the torus

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    We study the relation between class S theories on punctured tori and isomonodromic deformations of flat SL(N) connections on the two-dimensional torus with punctures. Turning on the self-dual Ω -background corresponds to a deautonomization of the Seiberg–Witten integrable system which implies a specific time dependence in its Hamiltonians. We show that the corresponding τ-function is proportional to the dual gauge theory partition function, the proportionality factor being a nontrivial function of the solution of the deautonomized Seiberg–Witten integrable system. This is obtained by mapping the isomonodromic deformation problem to WN free fermion correlators on the torus

    The effect of the displacement damage on the Charge Collection Efficiency in Silicon Drift Detectors for the LOFT satellite

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    The technology of Silicon Drift Detectors (SDDs) has been selected for the two instruments aboard the Large Observatory For X-ray Timing (LOFT) space mission. LOFT underwent a three year long assessment phase as candidate for the M3 launch opportunity within the "Cosmic Vision 2015 -- 2025" long-term science plan of the European Space Agency. During the LOFT assessment phase, we studied the displacement damage produced in the SDDs by the protons trapped in the Earth's magnetosphere. In a previous paper we discussed the effects of the Non Ionising Energy Losses from protons on the SDD leakage current. In this paper we report the measurement of the variation of Charge Collection Efficiency produced by displacement damage caused by protons and the comparison with the expected damage in orbit.Comment: 17 pages, 7 figures. Accepted for publication by Journal of Instrumentatio

    Anthropogenic modifications to the drainage network of Rome (Italy). The case study of the Aqua Mariana

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    Rome is characterized by millennia of urbanization. Long lasting geomorphological investigations have allowed the geomorphological description of the city centre and the valorisation of its geomorphological heritage. In this paper the spatial change of the hydrographic network in historical times is illustrated, with some examples showing how deep has been, and still it is, the link between the historical-cultural development and the natural geomorphological and hydrological characteristics of the Roman territory. In particular, the most relevant human interventions on the drainage network, in the southern area of the city centre, have been investigated. Before the land-use modifications of Roman-age, this area was drained by the most important left tributary of the Tiber River within the city walls, the Nodicus River, more recently known as Aqua Mariana. This stream has undergone many anthropogenic modifications and diversions during the centuries, and its original path is known only downstream of the San Giovanni Basilica. According to geomorphological, archaeological and geological evidences, it is possible to hypothesize that the dimension of the pre-urbanization drainage basin, as known and reconstructed in the available literature, should have been until now underestimated

    Hyper-velocity impact test and simulation of a double-wall shield concept for the Wide Field Monitor aboard LOFT

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    The space mission LOFT (Large Observatory For X-ray Timing) was selected in 2011 by ESA as one of the candidates for the M3 launch opportunity. LOFT is equipped with two instruments, the Large Area Detector (LAD) and the Wide Field Monitor (WFM), based on Silicon Drift Detectors (SDDs). In orbit, they would be exposed to hyper-velocity impacts by environmental dust particles, which might alter the surface properties of the SDDs. In order to assess the risk posed by these events, we performed simulations in ESABASE2 and laboratory tests. Tests on SDD prototypes aimed at verifying to what extent the structural damages produced by impacts affect the SDD functionality have been performed at the Van de Graaff dust accelerator at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. For the WFM, where we expect a rate of risky impacts notably higher than for the LAD, we designed, simulated and successfully tested at the plasma accelerator at the Technical University in Munich (TUM) a double-wall shielding configuration based on thin foils of Kapton and Polypropylene. In this paper we summarize all the assessment, focussing on the experimental test campaign at TUM.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 91446

    Measurement of the effect of Non Ionising Energy Losses on the leakage current of Silicon Drift Detector prototypes for the LOFT satellite

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    The silicon drift detectors are at the basis of the instrumentation aboard the Large Observatory For x-ray Timing (LOFT) satellite mission, which underwent a three year assessment phase within the "Cosmic Vision 2015 - 2025" long-term science plan of the European Space Agency. Silicon detectors are especially sensitive to the displacement damage, produced by the non ionising energy losses of charged and neutral particles, leading to an increase of the device leakage current and thus worsening the spectral resolution. During the LOFT assessment phase, we irradiated two silicon drift detectors with a proton beam at the Proton Irradiation Facility in the accelerator of the Paul Scherrer Institute and we measured the increase in leakage current. In this paper we report the results of the irradiation and we discuss the impact of the radiation damage on the LOFT scientific performance.Comment: 21 pages, 7 figures, 2 tables. Accepted for publication by Journal of Instrumentation (JINST
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