Mergers in Asymmetric Stackelberg Markets

It is well known that the profitability of horizontal mergers with quantity competition is scarce. However, in an asymmetric Stackelberg market we obtain that some mergers are profitable. Our main result is that mergers among followers become profitable when the followers are inefficient enough. In this case, leaders reduce their output when followers merge and this reduction renders the merger profitable. This merger increases price and welfare is reduced.Mergers, Asymmetries, Stackelberg

Depth map compression via 3D region-based representation

In 3D video, view synthesis is used to create new virtual views between encoded camera views. Errors in the coding of the depth maps introduce geometry inconsistencies in synthesized views. In this paper, a new 3D plane representation of the scene is presented which improves the performance of current standard video codecs in the view synthesis domain. Two image segmentation algorithms are proposed for generating a color and depth segmentation. Using both partitions, depth maps are segmented into regions without sharp discontinuities without having to explicitly signal all depth edges. The resulting regions are represented using a planar model in the 3D world scene. This 3D representation allows an efficient encoding while preserving the 3D characteristics of the scene. The 3D planes open up the possibility to code multiview images with a unique representation.Postprint (author's final draft

Aplicació de les Normes ISO a l’ensenyament

Master, especialitat TecnologiaUn dels aspectes principals en els que està centrada l’actualitat del món educatiu és la problemàtica relacionada amb els baixos índexs de rendiment dels alumnes i la mala relació entre les famílies i els centres. Al llarg del temps, les Normes ISO han anat ocupant una posició cada vegada més important per tal que les empreses milloressin la qualitat dels seus serveis. En conseqüència, poden representar un nou mètode per a obtenir millores en el procés educatiu. La Norma ISO 9001 fa referència als requisits necessaris de tot sistema de gestió de qualitat, és a dir, les condicions de treball que ha de seguir el centre. És necessari entendre totes les activitats com un procés amb unes instruccions associades, unes persones encarregades, uns recursos a utilitzar, etc. Tota aquesta informació ha d’estar documentada i vigilada, i la millora en el sistema de la qualitat s’obtindrà a partir de l’anàlisi i la verificació de les disconformitats, assumint també els comentaris o queixes de les famílies. La difusió de les Normes ISO en l’àmbit educatiu no és, avui en dia, molt elevada. Els alts costos de la certificació i de les revisions periòdiques, així com la dificultat a l’hora d’interpretar el contingut de la normativa, frenen la seva expansió. No obstant, els centres educatius que en disposen les utilitzen en una doble vessant: d’una banda, milloren els seu funcionament intern (com ara els processos del centre, el rendiment dels alumnes o la satisfacció de les famílies), mentre que, de l’altra, projecten cap a l’exterior una imatge de qualitat, credibilitat, seriositat i compromís amb l’educació dels seus alumnes. Només des d’una millora interna del funcionament del centre pot millorar la qualitat global i, en aquest sentit, les Normes ISO hi donen resposta

Improving OpenStack Swift interaction with the I/O stack to enable software defined storage

This paper analyses how OpenStack Swift, a distributed object storage service for a globally used middleware, interacts with the I/O subsystem through the Operating System. This interaction, which seems organised and clean on the middleware side, becomes disordered on the device side when using mechanical disk drives, due to the way threads are used internally to request data. We will show that only modifying the Swift threading model we achieve an 18% mean improvement in performance with objects larger than 512 KiB and obtain a similar performance with smaller objects. Compared to the original scenario, the performance obtained on both scenarios is obtained in a fair way: the bandwidth is shared equally between concurrently accessed objects. Moreover, this threading model allows us to apply techniques for Software Defined Storage (SDS). We show an implementation of a Bandwidth Differentiation technique that can control each data stream and that guarantees a high utilization of the device.The research leading to these results has received funding from the European Community under the IOStack (H2020-ICT-2014-7-1) project, by the Spanish Ministry of Economy and Competitiveness under the TIN2015-65316-P grant and by the Catalan Government under the 2014-SGR-1051 grant. To learn more about the IOStack H2020 project, please visit http:nnwww.iostack.eu.Peer ReviewedPostprint (author's final draft

The radio to TeV orbital variability of the microquasar LSI+61303

Context: .The microquasar LS I +61 303 has recently been detected at TeV energies by the Cherenkov telescope MAGIC, presenting variability on timescales similar to its orbital period. This system has been intensively observed at different wavelengths during the last three decades, showing a very complex behavior along the orbit.Aims: .We aim to explain, using a leptonic model in the accretion scenario, the observed orbital variability and spectrum from radio to TeV energies of LS I +61 303.Methods: .We apply a leptonic model based on accretion of matter from the slow inhomogeneous equatorial wind of the primary star, assuming particle injection proportional to the accretion rate. The relativistic electron energy distribution within the binary system is computed taking into account convective/adiabatic and radiative losses. The spectral energy distribution (SED) has been calculated accounting for synchrotron and (Thomson/Klein Nishina -KN-) inverse Compton (IC) processes and the photon-photon absorption in the ambient photon fields. The angle dependence of the photon-photon and IC cross sections has been considered in the calculations.Results: .We reproduce the main features of the observed light curves from LS I +61 303 at radio, X-rays, high-energy (HE), and very high-energy (VHE) gamma-rays, and the whole spectral energy distribution.Conclusions: .Our model is able to explain the radio to TeV orbital variability taking into account that radiation along the orbit is strongly affected by the variable accretion rate, the magnetic field strength, and by the ambient photon field via dominant IC losses and photon-photon absorption at periastron.Fil: Bosch Ramon, Valentí. Universidad de Barcelona; EspañaFil: Paredes, Josep Maria. Universidad de Barcelona; EspañaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Ribó, Marc. Universidad de Barcelona; Españ

Labour productivity developments in the euro area

This paper provides a description and a discussion of some important aspects relating to recent productivity developments in the euro area. Following decades of stronger gains in the euro area than in the US, labour productivity growth has fallen behind that in the US in recent years. This reflects a decline in average labour productivity growth observed in the euro area since the mid-1990s, which stands in sharp contrast with opposite developments in the US. The decline in labour productivity growth experienced in the euro area since the mid-1990s resulted from both lower capital deepening and lower total factor productivity growth. From a sectoral perspective, industries not producing or using intensively information and communication technology (ICT) would appear mostly responsible for the decline in average labour productivity growth since the mid-1990s. These developments were broadly experienced by most euro area countries. A comparison with developments in the US suggests that the euro area economy seems to have benefited much less from increased production and use of ICT technologies, in particular in the services sector. Diverging trends in labour productivity growth between the euro area and the US in recent years mainly reflect developments in a number of specific ICT-using services such as retail, wholesale and some financial services where strong gains were registered in the US. The evidence presented in this paper suggests that, in order to support economic growth in the euro area, emphasis should be given to both policy measures that directly address the determinants of productivity and, given the interactions among the various factors of growth, to policies that raise labour utilisation.

A stabilized finite element method for the mixed wave equation in an ALE framework with application to diphthong production

The archived file is not the final published version of the article. © (2016) S. Hirzel Verlag/European Acoustics Association The definitive publisher-authenticated version is available online at http://www.ingentaconnect.com/contentone/dav/aaua/2016/00000102/00000001/art00012 Readers must contact the publisher for reprint or permission to use the material in any form.Working with the wave equation in mixed rather than irreducible form allows one to directly account for both, the acoustic pressure field and the acoustic particle velocity field. Indeed, this becomes the natural option in many problems, such as those involving waves propagating in moving domains, because the equations can easily be set in an arbitrary Lagrangian-Eulerian (ALE) frame of reference. Yet, when attempting a standard Galerkin finite element solution (FEM) for them, it turns out that an inf-sup compatibility constraint has to be satisfied, which prevents from using equal interpolations for the approximated acoustic pressure and velocity fields. In this work it is proposed to resort to a subgrid scale stabilization strategy to circumvent this condition and thus facilitate code implementation. As a possible application, we address the generation of diphthongs in voice production.Peer ReviewedPostprint (author's final draft

The grape phylloxera plague as a natural experiment: the upkeep of vineyards in Catalonia (Spain), 1858-1935

We present a comparative analysis of the impact and outcome in Catalonia of the wine rush and crash unleashed by the spread of the Grape Phylloxera plague in Europe (1865-1890). In order to explain why many rural districts in the provinces of Barcelona and Tarragona were able to resume winegrowing after the plague, while most in the provinces of Girona and Lleida were not, a statistical model is used to check the economic resilience of the Catalan districts to the external ecological and economic shock. The model combines the population densities as a proxy of the opportunity cost in labour allocation, the demand pull of commercial growth measured by the time-distances to the city of Barcelona, and the agroclimatic land's suitability for growing vines, as measured by the Hugling and Winkler indices or the mean slopes of land. After comparing the vineyard allocation in every district in 1860, 1889 and 1920, these variables are used to explain the differing capacities to endure the Phylloxera plague in Catalonia

Explaining vineyard specialization in the province of Barcelona (Spain) in the mid-19th century

We present a statistical model of agrarian vineyard specialization in the province of Barcelona towards 1860, that combines the Boserupian push of population increase, the demand pull of a Smithian-type of growth (measured by the time-distances to the nearest seaport), and the agrological lands suitability for sowing grain or growing vines (as measured by water stress, slopes and frost risk). The overall outcome of the adjusted R2 levels, which range from 0.608 to 0.826, can be considered very successful. The inequality in land ownership is another factor that we believe to have played an important role, but has had to be omitted for the moment due to the lack of statistical data. Further research is also needed to deal with a possible endogeneity problem that working with socio-demographic variables entails.wine international market integration, regional land-use patterns, vineyard specialization, population pressure, agrological suitability