A Phillips curve to the Dominican Republic

This paper has provided an empirical evidence to support the existence of the Phillips curve in the case of the Dominican Republic. The Phillips curve is estimated using data over the last forty years and includes a role for supply factors. The most striking feature of the model is the strong relationship between inflation and excess demand.Phillips curve, output gap, unemployment gap

The magnetic SW Sextantis star RX J1643.7+3402

We present time-resolved spectroscopy and circular spectropolarimetry of the SW Sex star RX J1643.7+3402. We find significant polarisation levels exhibiting a variability at a period of 19.38 +- 0.39 min. In addition, emission-line flaring is found predominantly at twice the polarimetric period. These two findings are strong evidences in favour of the presence of a magnetic white dwarf in the system. We interpret the measured periodicities in the context of our magnetic accretion model for SW Sex stars. In contrast with LS Pegasi -the first SW Sex star discovered to have modulated circular polarisation- the polarisation in RX J1643.7+3402 is suggested to vary at 2(omega - Omega), while the emission lines flare at (omega - Omega). However, a 2omega/omega interpretation cannot be ruled out. Together with LS Peg and V795 Her, RX J1643.7+3402 is the third SW Sex star known to exhibit modulated circular polarisation.Comment: 7 pages, 4 figures, accepted for publication in MNRA

Sparse inversion of Stokes profiles. I. Two-dimensional Milne-Eddington inversions

Inversion codes are numerical tools used for the inference of physical properties from the observations. Despite their success, the quality of current spectropolarimetric observations and those expected in the near future presents a challenge to current inversion codes. The pixel-by-pixel strategy of inverting spectropolarimetric data that we currently utilize needs to be surpassed and improved. The inverted physical parameters have to take into account the spatial correlation that is present in the data and that contains valuable physical information. We utilize the concept of sparsity or compressibility to develop an new generation of inversion codes for the Stokes parameters. The inversion code uses numerical optimization techniques based on the idea of proximal algorithms to impose sparsity. In so doing, we allow for the first time to exploit the presence of spatial correlation on the maps of physical parameters. Sparsity also regularizes the solution by reducing the number of unknowns. We compare the results of the new inversion code with pixel-by-pixel inversions, demonstrating the increase in robustness of the solution. We also show how the method can easily compensate for the effect of the telescope point spread function, producing solutions with an enhanced contrast.Comment: 13 pages, 8 figures, accepted for publication in A&

Factores de infraestructura determinantes en el acceso a Internet en México en el período 2000-2008

56 páginas. Maestría en Economía.Un aspecto relevante en el desarrollo social y económico ha sido el acceso a la información y a las tecnologías de la comunicación (TIC), dando énfasis en la disminución de la pobreza. Organismos internacionales como el Banco Mundial centran uno de sus objetivos en la reducción de la pobreza, y es por ello que la incorporación de las TIC ha sido promovida como un mecanismo para: la integración de comunidades rurales que todavía viven aisladas; fomentar el desarrollo entre países y regiones e incrementar el crecimiento de los países dentro de una economía global. Debido a que la penetración de Internet es aún relativamente baja en México a pesar de las varias iniciativas oficiales para abatir la brecha digital, en esta investigación se plantea analizar los efectos de algunos de los principales factores en infraestructura en el acceso a Internet que siguen incidiendo en la persistencia de la brecha digital en el país, como son las inversiones en infraestructura de telecomunicaciones, el precio de acceso a Internet y el efecto del ingreso per-cápita de la población. Estos factores se analizarán en el período 2000 a 2008

An empirical assessment of exchange arrangements and inflation performance

Abstract. This article provides empirical support for the hypothesis that different exchange rate regimes have an impact on inflation in advanced, emerging and developing countries. The effects of different exchange rate regimes on inflation performance are examined through least squares dummy variables regressions using panel data on 125 countries for the post-Bretton Woods (1974-1999) period. Also, this article addresses the issue of measurement errors in the classification of exchange rate regimes by using four different classification schemes. Three de facto and one de jure classifications are used. Consequently, the sensitivity of these results to alternative exchange rate classifications is also tested. The empirical findings indicate that countries with fixed regimes tend to have a lower inflation rate compared to floating and intermediate exchange rate regimes, particularly in emerging and developing countries.Keywords. Exchange rate regimes, Inflation.JEL. E31, F31, F33

Short dynamic fibrils in sunspot chromospheres

Sunspot chromospheres display vigorous oscillatory signature when observed in chromospheric diagnostics like the strong Ca II lines and H-alpha. New high-resolution sunspot observations from the Swedish 1-m Solar Telescope show the ubiquitous presence of small-scale periodic jet-like features that move up and down. This phenomenon has not been described before. Their typical width is about 0.3 arcsec and they display clear parabolic trajectories in space-time diagrams. The maximum extension of the top of the jets is lowest in the umbra, a few 100 km, and progressively longer further away from the umbra in the penumbra, with the longest more than 1000 km. These jets resemble dynamic fibrils found in plage regions but at smaller extensions. LTE inversion of spectro-polarimetric Ca II 8542 observations enabled for a comparison of the magnetic field inclination and the properties of these short jets. We find that the most extended of these jets also have longer periods and tend to be located in regions with more horizontal magnetic fields. This is a direct observational confirmation of the mechanism of long-period waves propagating along inclined magnetic fields into the solar chromosphere. This mechanism was identified earlier as the driver of dynamic fibrils in plage, part of the mottles in quiet Sun, and type I spicules at the limb. The sunspot dynamic fibrils that we report here represent a new class of manifestation of this mechanism. They are not the same as the transient penumbral and umbral micro-jets reported earlier.Comment: animations of figures can be found at http://folk.uio.no/rouppe/dfsunspot

El uso de Twitter por parte de actores armados: explicando la Renuencia de Hezbollah

En la tesis de Grado se analiza la naturaleza de la ideología de Hezbollah y como está determina la utilización de Twitter por parte de este grupo terrorista.The aim of the thesis is to analyse the influence of the ideology of a terrorist organization (i.e. Hezbollah) in the usage of a social network e.g. Twitte