36,868 research outputs found
Solution to the Landau-Zener problem via Susskind-Glogower operators
We show that, by means of a right-unitary transformation, the fully quantized
Landau-Zener Hamiltonian in the weak-coupling regime may be solved by using
known solutions from the standard Landau-Zener problem. In the strong-coupling
regime, where the rotating wave approximation is not valid, we show that the
quantized Landau-Zener Hamiltonian may be diagonalized in the atomic basis by
means of a unitary transformation; hence allowing numerical solutions for the
few photons regime via truncation.Comment: 6 pages, 5 figure
The effect of international trade on mark-ups distribution
This paper presents empirical evidence about the relationship between market openness and markup distribution of manufacturing firms. The empirical analysis uses a panel data set of Spanish firms in the period 1990-2005, with a structural approach that lets us to identify individual mark-ups. The results point out that tougher competition associated to openness reduces the average of marginal costs and prices, while it increases the average firm size. However, the evidence about the effect on average markups and the dispersion of performance variables is weaker. These results partially support the theoretical predictions by the recent literature on efficiency heterogeneity and international trade and, in particular, Melitz and Ottaviano (2008).markups, marginal costs, size, openness
Markups, bargaining power and offshoring: an empirical assessment
This paper tests the pro-competitive effect of imports on product and labour markets for Spanish manufacturing firms in the period 1990-2005. In doing so, it takes into account the type of imported products: final vs intermediate. Markups are estimated following the procedure suggested by Roeger (1995) and including an efficient bargaining model. The observed heterogeneity among firms is parameterized to consider additional product standardization and market concentration. The results support the Imports as Market Discipline hypothesis for importers of final goods, while firms that offshore intermediate inputs show similar markups to non-importers. Additionally, the union bargaining power is smaller the more final-goods oriented imports are and the more homogeneous is the type of goods elaborated by firms.Markups, offshoring, bargaining power
Socioeconomic effects of protected areas in Spain across spatial scales and protection levels
Impacts of the legal designation of protected areas (PAs) may have contrasting implications for different stakeholders, and at different spatial scales. In this study, we analysed the organisational perception on the socioeconomic effects of PA designation from all sectors of activity in Spain, accounting for PAsâ legal stringency. A semi-structured questionnaire was administered to 68 organisations at national, regional (Andalusia) and local scales (two municipalities in the Almeria province, Andalusia) through an online survey. Local stakeholders and the primary, secondary and tertiary sectors were most concerned about the social and economic impacts of PAs designation on their organisations. By contrast, organisations at the national or regional scales together with public institutions, the quaternary sector and other miscellaneous stakeholders perceived predominantly positive effects. Only national organisations perceived an increase in local social and economic effects from the designation of legally stringent PAs with regard to multiple-use PAs
Self-similar transmission properties of aperiodic Cantor potentials in gapped graphene
We investigate the transmission properties of quasiperiodic or aperiodic
structures based on graphene arranged according to the Cantor sequence. In
particular, we have found self-similar behaviour in the transmission spectra,
and most importantly, we have calculated the scalability of the spectra. To do
this, we implement and propose scaling rules for each one of the fundamental
parameters: generation number, height of the barriers and length of the system.
With this in mind we have been able to reproduce the reference transmission
spectrum, applying the appropriate scaling rule, by means of the scaled
transmission spectrum. These scaling rules are valid for both normal and
oblique incidence, and as far as we can see the basic ingredients to obtain
self-similar characteristics are: relativistic Dirac electrons, a self-similar
structure and the non-conservation of the pseudo-spin. This constitutes a
reduction of the number of conditions needed to observe self-similarity in
graphene-based structures, see D\'iaz-Guerrero et al. [D. S. D\'iaz-Guerrero,
L. M. Gaggero-Sager, I. Rodr\'iguez-Vargas, and G. G. Naumis,
arXiv:1503.03412v1, 2015]
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