Threshold of Preference for Collusion and Interconnection Fees in Different Market Structures : the Tunisian Mobile Market Case

We present a Cournot model that compares the critical threshold of collusion in Duopoly and Oligopoly Markets where the actors are private, mixed or public. We assume that the incentive critical threshold for collusion depends on the interconnection fees. The different threshold values calculated in each Market structure are then estimated, using the OLS method, with variables related to the Tunisian market structures and prices. The Econometric estimation of the different threshold values is consistent with our theoretical results. Our findings can be used by the decision makers to control collusion, by acting on the level of interconnection fees for each market structure and by implementing the suitable market liberalization policies in this sector

Market Power and Collusion on Interconnection Phone Market in Tunisia : What Lessons from International Experiences

We try in this paper to characterize the state of mobile phone market in Tunisia. Our study is based on a survey of foreign experience (Europe) in detecting collusive behavior and a comparison of the critical threshold of collusion between operators in developing countries like Tunisia. The market power is estimated based on the work of Parker Roller (1997) and the assumption of "Balanced Calling Pattern". We use then the model of Friedman (1971) to compare the critical threshold of collusion. We show that the "conduct parameter" measuring the intensity of competition is not null during the period 1993-2011. Results show also that collusion is easier on the Tunisian market that on the Algerian, Jordanian, or Moroccan one

Computing Optical Properties of Ultra-thin Crystals

An overview is given of recent advances in experimental and theoretical understanding of optical properties of ultra-thin crystal structures (graphene, phosphorene, silicene, MoS2, MoSe2 , WS2 , WSe2 , h-AlN, h-BN, fluorographene, graphane). Ultra-thin crystals are atomically-thick layered crystals that have unique properties which differ from their 3D counterpart. Because of the difficulties in the synthesis of few-atom-thick crystal structures, which are thought to be the main building blocks of future nanotechnology, reliable theoretical predictions of their electronic, vibrational and optical properties are of great importance. Recent studies revealed the reliable predictive power of existing theoretical approaches based on density functional theory (DFT)

Raman spectroscopy characterization of 10-cash productions from the late Chinese emperors to the Republic

This is the peer reviewed version of the following article: Montoya, Noemí, Montagna, Elena, Lee, Yu, Domenech Carbo, Mª Teresa, Doménech Carbó, Antonio. (2017). Raman spectroscopy characterization of 10-cash productions from the late Chinese emperors to the Republic.Journal of Raman Spectroscopy, 48, 10, 1337-1345. DOI: 10.1002/jrs.5218 , which has been published in final form at http://doi.org/10.1002/jrs.5218. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] The use of Raman spectroscopy for discriminating monetary emissions, a recurrent problem in much archaeological studies, is described. The method involves the record of Raman signatures of tenorite and crystalline and defective cuprite in the patina based on the idea that subtle, mint-characteristic variations in the composition and metallography of the base metal during the manufacturing process are reflected in the variation in depth of the composition and crystallinity of the corrosion patina. The technique was applied to a series of 10-cash copper coins produced around the transition between the Kuang Hsu and Hsuan Tung last Chinese emperors and the first Republic whose averaged composition was 95 +/- 1% wt Cu plus 5 +/- 1% wt Zn often accompanied by traces of Sn and Pb. Raman data, corroborated by focusing ion beam-field emission scanning electron microscopy and voltammetry of immobilized particles measurements, suggested the possibility of discerning between different provincial and regular unified currency productions.MINECO, Grant/Award Number: CTQ2014-53736-C3-1-P and CTQ2014-53736-C3-2-PMontoya, N.; Montagna, E.; Lee, Y.; Domenech Carbo, MT.; Domenech Carbo, A. (2017). Raman spectroscopy characterization of 10-cash productions from the late Chinese emperors to the Republic. Journal of Raman Spectroscopy. 48(10):1337-1345. https://doi.org/10.1002/jrs.5218S13371345481

Phonon-driven spin-Floquet magneto-valleytronics in MoS2

Two-dimensional materials equipped with strong spin-orbit coupling can display novel electronic, spintronic, and topological properties originating from the breaking of time or inversion symmetry. A lot of interest has focused on the valley degrees of freedom that can be used to encode binary information. By performing ab initio time-dependent density functional simulation on MoS2, here we show that the spin is not only locked to the valley momenta but strongly coupled to the optical E '' phonon that lifts the lattice mirror symmetry. Once the phonon is pumped so as to break time-reversal symmetry, the resulting Floquet spectra of the phonon-dressed spins carry a net out-of-plane magnetization (approximate to 0.024 mu(B) for single-phonon quantum) even though the original system is non-magnetic. This dichroic magnetic response of the valley states is general for all 2H semiconducting transition-metal dichalcogenides and can be probed and controlled by infrared coherent laser excitation

Liquid-Phase Exfoliated Indium–Selenide Flakes and Their Application in Hydrogen Evolution Reaction

Single- and few-layered InSe flakes are produced by the liquid-phase exfoliation of β-InSe single crystals in 2-propanol, obtaining stable dispersions with a concentration as high as 0.11 g L−1. Ultracentrifugation is used to tune the morphology, i.e., the lateral size and thickness of the as-produced InSe flakes. It is demonstrated that the obtained InSe flakes have maximum lateral sizes ranging from 30 nm to a few micrometers, and thicknesses ranging from 1 to 20 nm, with a maximum population centered at ≈5 nm, corresponding to 4 Se–In–In–Se quaternary layers. It is also shown that no formation of further InSe-based compounds (such as In2Se3) or oxides occurs during the exfoliation process. The potential of these exfoliated-InSe few-layer flakes as a catalyst for the hydrogen evolution reaction (HER) is tested in hybrid single-walled carbon nanotubes/InSe heterostructures. The dependence of the InSe flakes' morphologies, i.e., surface area and thickness, on the HER performances is highlighted, achieving the best efficiencies with small flakes offering predominant edge effects. The theoretical model unveils the origin of the catalytic efficiency of InSe flakes, and correlates the catalytic activity to the Se vacancies at the edge of the flakes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Collusion et structure des coûts dans un marché de duopole mixte vs privé de téléphonie mobile

Nous présentons dans ce papier une modélisation du seuil critique de préférence pour la collusion dans un duopole mixte/privé en fonction du tarif d'interconnexion et de son coût marginal, dans un régime de concurrence à la Cournot. L'objectif consiste à comparer la préférence pour la collusion à travers ce seuil dans les deux structures de marché étudiées et dans deux cas de figures : coûts d'interconnexion linéaires et coût d'interconnexion quadratiques. Les résultats montrent que le seuil dépend de deux variables : Le tarif d'interconnexion et un paramètre relatif à la technologie employée par l'opérateur. Les résultats de l'application au cas du marché Tunisien sont conformes aux résultats théoriques

Controlling the Stability and the Electronic Structure of Transition Metal Dichalcogenide Single Layer under Chemical Doping

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Tuning the Magnetic and Electronic Properties of Monolayer Chromium Tritelluride through Strain Engineering

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