AIRBench: A DEA-based model for the benchmarking of airports revenues

The socio-economic development of countries is a key factor for the growth of people mobility, bringing an increase of inter and extra continental air passengers flows. On the other side, the leading model business of low cost companies is decreasing the revenues of airports coming from the avio operations. The two effects are increasing the awareness of airports management, historically focused on the avio operations, towards the mix of avio and commercial revenues. AIRBench is a DEA-based benchmark model developed by the ORO Group of Poltecnico di Torino and BDS, a consulting company specialized in the sector of airports management. Differently from other works in the literature, AIRBench uses data that can be obtained by publicly available documents and databases (consolidated balance sheets, web sites, and ENAC data) in order to link both avio and commercial revenues to the airports performances. The DEA-based method is applied to a panel of 21 airports (both Italian and European airports) in order to build a comparison of airports performances and to obtain a panel of reference management practices to evaluate additional airports. Moreover, given the airports considered efficient by the DEA models, a detailed analysis of causes, opportunities and threads for non-efficient airports is presented

Evidence for a Peierls phase-transition in a three-dimensional multiple charge-density waves solid

The effect of dimensionality on materials properties has become strikingly evident with the recent discovery of graphene. Charge ordering phenomena can be induced in one dimension by periodic distortions of a material's crystal structure, termed Peierls ordering transition. Charge-density waves can also be induced in solids by strong Coulomb repulsion between carriers, and at the extreme limit, Wigner predicted that crystallization itself can be induced in an electrons gas in free space close to the absolute zero of temperature. Similar phenomena are observed also in higher dimensions, but the microscopic description of the corresponding phase transition is often controversial, and remains an open field of research for fundamental physics. Here, we photoinduce the melting of the charge ordering in a complex three-dimensional solid and monitor the consequent charge redistribution by probing the optical response over a broad spectral range with ultrashort laser pulses. Although the photoinduced electronic temperature far exceeds the critical value, the charge-density wave is preserved until the lattice is sufficiently distorted to induce the phase transition. Combining this result with it ab initio} electronic structure calculations, we identified the Peierls origin of multiple charge-density waves in a three-dimensional system for the first time.Comment: Accepted for publication in Proc. Natl. Acad. Sci. US

Significant reduction of electronic correlations upon isovalent Ru substitution of BaFe2As2

We present a detailed investigation of Ba(Fe0.65Ru0.35)2As2 by transport measurements and Angle Resolved photoemission spectroscopy. We observe that Fe and Ru orbitals hybridize to form a coherent electronic structure and that Ru does not induce doping. The number of holes and electrons, deduced from the area of the Fermi Surface pockets, are both about twice larger than in BaFe2As2. The contribution of both carriers to the transport is evidenced by a change of sign of the Hall coefficient with decreasing temperature. Fermi velocities increase significantly with respect to BaFe2As2, suggesting a significant reduction of correlation effects. This may be a key to understand the appearance of superconductivity at the expense of magnetism in undoped iron pnictides

Ultrafast filling of an electronic pseudogap in an incommensurate crystal

We investigate the quasiperiodic crystal (LaS)1.196(VS2) by angle and time resolved photoemission spectroscopy. The dispersion of electronic states is in qualitative agreement with band structure calculated for the VS2 slab without the incommensurate distortion. Nonetheless, the spectra display a temperature dependent pseudogap instead of quasiparticles crossing. The sudden photoexcitation at 50 K induces a partial filling of the electronic pseudogap within less than 80 fs. The electronic energy flows into the lattice modes on a comparable timescale. We attribute this surprisingly short timescale to a very strong electron-phonon coupling to the incommensurate distortion. This result sheds light on the electronic localization arising in aperiodic structures and quasicrystals

Theoretical description of high-order harmonic generation in solids

We consider several aspects of high-order harmonic generation in solids: the effects of elastic and inelastic scattering; varying pulse characteristics; and inclusion of material-specific parameters through a realistic band structure. We reproduce many observed characteristics of high harmonic generation experiments in solids including the formation of only odd harmonics in inversion-symmetric materials, and the nonlinear formation of high harmonics with increasing field. We find that the harmonic spectra are fairly robust against elastic and inelastic scattering. Furthermore, we find that the pulse characteristics play an important role in determining the harmonic spectra.Comment: Accepted for publication in the New Journal of Physic

new morphologic variants of the hand motor cortex as seen with mr imaging in a large study population

BACKGROUND AND PURPOSE: The hand motor cortex (HMC) has been classically described as having an omega or epsilon shape in axial-plane images obtained with CT and MR imaging. The aim of this study was to use MR imaging and Talairach normalization in a large sample population that was homogeneous for age and handedness to evaluate in a sex model a new classification with 5 morphologic variants of the HMC in the axial plane (omega, medially asymmetric epsilon, epsilon, laterally asymmetric epsilon, and null). MATERIALS AND METHODS: Structural brain MR images were obtained from 257 right-handed healthy subjects (143 men and 114 women; mean age, 23.1 ± 1.1 years) via a Talairach space transformed 3D magnetization-prepared rapid acquisition of gradient echo sequence. The frequencies of the different HMC variants were reported for hemisphere and sex. RESULTS: The new variants of the HMC (medially asymmetric epsilon, laterally asymmetric epsilon, and null) were observed in 2.9%, 7.0%, and 1.8% of the hemispheres, respectively. Statistically significant sex differences were observed: The epsilon variant was twice as frequent in men, and an interhemispheric concordance for morphologic variants was observed only for women. CONCLUSION: The large study population permitted the description of a new morphologic classification that included 3 new variants of the HMC. This new morphologic classification should facilitate the identification of the precentral gyrus in subsequent studies and in everyday practice