9,331 research outputs found
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
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
The Greek Crisis: Causes and Consequences
Greece has reached a point where, under any plausible macroeconomic scenario, public debt will continue growing faster than GDP. Fiscal consolidation alone cannot close the solvency gap. A substantial reduction in the stock of debt is needed. Even post-debt restructuring, there is no guarantee that the government will succeed in its dual goal of restoring fiscal solvency and closing the competitiveness gap. Yet we think Greece stands a better chance of accomplishing these goals from inside the EMU rather than outside it. This chapter takes stock of the factors that led to the explosion of public debt, the loss of competitiveness, and the failure of the first EU-IMF programme. We also present our views on the likely debt restructuring (and post-restructuring) scenarios.
Market Structure, Technology Spillovers, and Persistence in Productivity Differentials
Using data from 11 main manufacturing industries in 17 OECD countries, this paper empirically investigates the determinants of cross-country differences in the persistence of productivity differentials Specifically, we focus on the effects of product market structure and technology diffusion. It is found that the manufacturing industries display a wide range of convergence rates. Consistent with theories, the persistence of productivity differentials is found to be positively correlated with the price-cost margin and the intra-industry trade index - the proxies for market monopolistic behavior. The proxies for tecnology diffusion, however, do not exhibit consistently significant effect. Among the conditioning macro variables, productivity convergence appears to be enhanced by human capital but deterred by government spending.Total factor productivity, convergence, market structure, technology diffusion
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 -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
Testing for Output Convergence: A Re-Examination
This paper investigates output convergence for the G7 countries using multivariate time series techniques. We consider both the null hypotheses of no convergence and convergence. It is shown that inferences on output convergence depend on which one of the two null hypotheses is considered. Further, the no convergence results reported in previous studies using the time series definition may be attributed to the low power of the test procedures being used. Our results also highlight some potential problems on interpreting results from some typical multivariate unit root and stationarity tests.Output convergence, multivariate test, unit root test, stationarity test
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