Airline Market Power and Intertemporal Price Dispersion

This paper analyzes the empirical relationship between market structure and price dispersion in the airline markets connecting the UK and the Republic of Ireland. Price dispersion is measured by a number of inequality indexes, calculated using fares posted on the Internet at specific days before takeoff. We find a negative correlation between market dominance and price dispersion; thus competition appears to hinder the airlines' ability to price discriminate to exploit consumers' heterogeneity in booking time preferences. Moreover, in the Christmas and Easter periods of high demand, fares are less dispersed, possibly because airlines target a less heterogenous set of consumers.Intertemporal pricing, competition, price dispersion.

Rifting and arc-related early Paleozoic volcanism along the North Gondwana margin: geochemical and geological evidence from Sardinia (Italy)

Three series of volcanic rocks accumulated during the Cambrian to Silurian in the metasediment-dominated Variscan basement of Sardinia. They provide a record of the changing geodynamic setting of the North Gondwana margin between Upper Cambrian and earliest Silurian. A continuous Upper Cambrian–Lower Ordovician succession of felsic submarine and subaerial rocks, dominantly transitional alkaline in character (ca. 492–480 Ma), is present throughout the Variscan nappes. Trace element data, together with Nd isotope data that point to a depleted mantle source, indicate an ensialic environment. A Middle Ordovician (ca. 465 Ma) calc-alkaline bimodal suite, restricted to the external Variscan nappes, overlies the Sardic Unconformity. Negative ϵNdi values (−3.03 to −5.75) indicate that the suite is a product of arc volcanism from a variably enriched mantle. A Late Ordovician–Early Silurian (ca. 440 Ma) volcano-sedimentary cycle consists of an alkalic mafic suite in a post-Caradocian transgressive sequence. Feeder dykes cut the pre-Sardic sequence. The alkali basalts are enriched in Nb-Ta and have Zr/Nb ratios in the range 4.20–30.90 (typical of a rift environment) and positive ϵNdi values that indicate a depleted mantle source. Trachyandesite lavas have trace element contents characteristic of within-plate basalt differentiates, with evidence of minor crustal contamination

Airline Pricing under Different Market Conditions: Evidence from European Low-Cost Carriers

Traditional theories of airline pricing maintain that fares monotonically increase as fewer seats remain available on a flight. A fortiori, this implies a monotonically increasing temporal profile of fares. In this paper, we exploit the presence of drops in offered fares over time as an indicator of an active yield management intervention by two main European Low-Cost Carriers observed daily during the period June 2002 - June 2003. Our results indicate that yield management is effective in raising a flight's load factor. Furthermore, yield management interventions are more intense, and generate a stronger impact, on more competitive routes: one possible interpretation is that a reduction in competitive pressure allows the carriers to adopt a more standardized approach to pricing. Similarly, we find that yield management interventions are more effective in raising the load factor on routes where the customer mix is more heterogenous (i.e., it includes passengers traveling for leisure, business and for family matters). On markets with homogeneous customer base, no robust yield management effect was observed.Easyjet, Intertemporal Pricing, Panel Data, Ryanair, Yield Management

Diffuse cosmic rays shining in the Galactic center: A novel interpretation of H.E.S.S. and Fermi-LAT gamma-ray data

We present a novel interpretation of the $\gamma$-ray diffuse emission measured by Fermi-LAT and H.E.S.S. in the Galactic center (GC) region and the Galactic ridge (GR). In the first part we perform a data-driven analysis based on PASS8 Fermi-LAT data: we extend down to few GeV the spectra measured by H.E.S.S. and infer the primary cosmic-ray (CR) radial distribution between 0.1 and 3 TeV. In the second part we adopt a CR transport model based on a position-dependent diffusion coefficient. Such behavior reproduces the radial dependence of the CR spectral index recently inferred from the Fermi-LAT observations. We find that the bulk of the GR emission can be naturally explained by the interaction of the diffuse steady-state Galactic CR sea with the gas present in the Central Molecular Zone. Although our results leave room for a residual radial-dependent emission associated with a central source, the relevance of the large-scale background prevents from a solid evidence of a GC Pevatron.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter

Hard Cosmic Ray Sea in the Galactic Center: a consistent interpretation of H.E.S.S. and Fermi-LAT γ\gamma-ray data

We present a novel interpretation of the gamma-ray diffuse emission measured by H.E.S.S. in the Galactic Center (GC) region and the Galactic ridge. Our starting base is an updated analysis of PASS8 Fermi-LAT data, which allows to extend down to few GeV the spectra measured by H.E.S.S. and to infer the primary CR radial distribution above 100 GeV. We compare those results with a CR transport model assuming a harder scaling of the diffusion coefficient with rigidity in the inner Galaxy. Such a behavior reproduces the radial dependence of the CR spectral index recently inferred from Fermi-LAT measurements in the inner GP. We find that, in this scenario, the bulk of the Galactic ridge emission can be naturally explained by the interaction of the diffuse, steady-state Galactic CR sea interacting with the gas present in the Central molecular zone. The evidence of a GC PeVatron is significantly weaker than that inferred adopting a conventional (softer) CR sea.Comment: Oral contribution to the International Cosmic Ray Conference (ICRC 2017), 12-20 July 2017, Bexco, Busan, Kore

A common solution to the cosmic ray anisotropy and gradient problems

Multichannel Cosmic Ray (CR) spectra and the large scale CR anisotropy can hardly be made compatible in the framework of conventional isotropic and homogeneous propagation models. These models also have problems explaining the longitude distribution and the radial emissivity gradient of the $\gamma$-ray galactic interstellar emission. We argue here that accounting for a well physically motivated correlation between the CR escape time and the spatially dependent magnetic turbulence power can naturally solve both problems. Indeed, by exploiting this correlation we find propagation models that fit a wide set of CR primary and secondary spectra, and consistently reproduce the CR anisotropy in the energy range 10^2 - 10^4 \GeV and the $\gamma$-ray longitude distribution recently measured by Fermi-LAT.Comment: 4 pages, 3 figures. v2: Accepted in Phys. Rev. Let

Physics and application of photon number resolving detectors based on superconducting parallel nanowires

The Parallel Nanowire Detector (PND) is a photon number resolving (PNR) detector which uses spatial multiplexing on a subwavelength scale to provide a single electrical output proportional to the photon number. The basic structure of the PND is the parallel connection of several NbN superconducting nanowires (100 nm-wide, few nm-thick), folded in a meander pattern. PNDs were fabricated on 3-4 nm thick NbN films grown on MgO (TS=400C) substrates by reactive magnetron sputtering in an Ar/N2 gas mixture. The device performance was characterized in terms of speed and sensitivity. PNDs showed a counting rate of 80 MHz and a pulse duration as low as 660ps full width at half maximum (FWHM). Building the histograms of the photoresponse peak, no multiplication noise buildup is observable. Electrical and optical equivalent models of the device were developed in order to study its working principle, define design guidelines, and develop an algorithm to estimate the photon number statistics of an unknown light. In particular, the modeling provides novel insight of the physical limit to the detection efficiency and to the reset time of these detectors. The PND significantly outperforms existing PNR detectors in terms of simplicity, sensitivity, speed, and multiplication noise

High performance NbN nanowire superconducting single photon detectors fabricated on MgO substrates

We demonstrate high-performance nanowire superconducting single photon detectors (SSPDs) on ultrathin NbN films grown at a temperature compatible with monolithic integration. NbN films ranging from 150nm to 3nm in thickness were deposited by dc magnetron sputtering on MgO substrates at 400C. The superconducting properties of NbN films were optimized studying the effects of deposition parameters on film properties. SSPDs were fabricated on high quality NbN films of different thickness (7 to 3nm) deposited under optimal conditions. Electrical and optical characterizations were performed on the SSPDs. The highest QE value measured at 4.2K is 20% at 1300nm

Hadronic interactions of primary cosmic rays with the FLUKA code

The measured fluxes of secondary particles produced by the interactions of cosmic rays with the astronomical environment represent a powerful tool to infer some properties of primary cosmic rays. In this work we investigate the production of secondary particles in inelastic hadronic interactions between several cosmic rays species of projectiles and different target nuclei of the interstellar medium. The yields of secondary particles have been calculated with the FLUKA simulation package, that provides with very good accuracy the energy distributions of secondary products in a large energy range. An application to the propagation and production of secondaries in the Galaxy is presented.Comment: 8 pages, 4 figures; Contribution to the 34th International Cosmic Ray Conference, July 30 to August 6, The Hague, Netherlands; fixing a typo in the y-axis label of Fig.

The hidden sides of ‘dynamic pricing’ for airline tickets

Unlike its planes, easyJet prices go up but don't come down: The longer you wait, the more you pay, write Marco Alderighi, Alberto A. Gaggero and Claudio A. Pig