Productivity Differences in OECD Countries

This paper investigates cross-country productivity convergence at a sectoral level using multivariate unit-root tests. Our empirical analysis counts with three distinctive features. First, it allows all the coefficients in the panel specification to vary across countries. Second, it accounts for the presence of significant cross-country correlations found in the data. Third, when the null hypothesis of non convergence is rejected, a second test determines the number of converging countries. Based on a sample of thirteen OECD countries our results show evidence of convergence in three out of six sectors, namely, agriculture, construction, and transportation and communication services.Convergence, panel data, productivity

A fast version of the k-means classification algorithm for astronomical applications

Context. K-means is a clustering algorithm that has been used to classify large datasets in astronomical databases. It is an unsupervised method, able to cope very different types of problems. Aims. We check whether a variant of the algorithm called single-pass k-means can be used as a fast alternative to the traditional k-means. Methods. The execution time of the two algorithms are compared when classifying subsets drawn from the SDSS-DR7 catalog of galaxy spectra. Results. Single-pass k-means turn out to be between 20 % and 40 % faster than k-means and provide statistically equivalent classifications. This conclusion can be scaled up to other larger databases because the execution time of both algorithms increases linearly with the number of objects. Conclusions. Single-pass k-means can be safely used as a fast alternative to k-means

Single magnetic adsorbates on s-wave superconductors

In superconductors, magnetic impurities induce a pair-breaking potential for Cooper pairs, which locally affects the Bogoliubov quasiparticles and gives rise to Yu-Shiba-Rusinov (YSR or Shiba, in short) bound states in the density of states (DoS). These states carry information on the magnetic coupling strength of the impurity with the superconductor, which determines the many-body ground state properties of the system. Recently, the interest in Shiba physics was boosted by the prediction of topological superconductivity and Majorana modes in magnetically coupled chains and arrays of Shiba impurities. Here, we review the physical insights obtained by scanning tunneling microscopy into single magnetic adsorbates on the $s$-wave superconductor lead (Pb). We explore the tunneling processes into Shiba states, show how magnetic anisotropy affects many-body excitations, and determine the crossing of the many-body groundstate through a quantum phase transition. Finally, we discuss the coupling of impurities into dimers and chains and their relation to Majorana physics.Comment: 18 pages, 17 figures, revie

Treatment with antisense oligonucleotides in Duchenne’s disease

Se revisa el estado actual de los tratamientos de modificación del ARN de distrofina, que persiguen convertir la forma grave de la distrofia muscular de Duchenne a una forma leve (Becker), especialmente con la omisión del exón 51 mediante oligonucleótidos en antisentido y la terapia de restauración de la lectura de la distrofina, suprimiendo un codón de terminación prematura mediante PTC124. Constituyen un avance notable en el tratamiento. Consiguen una producción significativa de distrofina en el músculo esquelético, aunque, por el momento, los resultados clínicos son menos notables. Es de esperar que modificaciones químicas en la liberación y distribución corporal, así como en la captación celular de estos oligonucleótidos, aumenten su eficacia y seguridad, permitiendo el tratamiento crónico de la distrofia muscular de DuchenneIn this paper I review the results of the treatments directed to modify the mRNA of dystrophin with the goal of converting the severe Duchenne type to the milder Becker muscular dystrophy. Antisense oligomers potential to modify Duchenne muscular dystrophy (DMD) gene expression and therapeutic strategies to induce ribosomal read-through of nonsense mutations (PTC124) are described. They are an important advance in the treatment of DMD, so far unspecific. Significant expression of new dystrophin is observed in biopsies of peripheral muscle, although the functional improvement is not so encouraging. New modification of chemistries are expected to improve the liberation, broad distribution in muscles, as well as their efficacy and safety enough to allow a positive chronic treatment of DM

Some first steps into glottogenetics in Catalonia: the vivential approach

Es pot aprendre un idioma? Tots sabem que I'idioma matero no s'apren, sinó que s'adquireix. La glotodidàctica pretén que l'alumne aprengui un idioma. No serà aquesta, tal vegada, la causa del freqüent i a vegades massiu abandonament de l'estudi d'un idioma per part d'un elevat percentatge d'alumnes? No estarem forçant la ment humana a aprendre un altre idioma amb unes tècniques diferents a les de la intel·ligència, tal i com està configurada per dur-ho a terme? Després de 23 anys de dedicació exclusiva a l'ensenyament de l'angles com a idioma estranjer, a l'autor, li sembla d'haver arribat a un punt en el qual creu s'hauria d'intentar trobar el mètode anti-mètode. Potser el psicolingüista nord-americà L. A. Jakobovits ja anava per aquest camí en afirmar que "la tecnica d'ensenyar conversa radica en l'art de no ensenyar l'idioma". En aquest sentit, contrasta la Metodologia Vivencial amb la que generalment s'empra avui amb la frase: "Molts aprenen un idioma per parlar-lo. Nosaltres parlem l'idioma per aprendre'l"