Productivity And Firm Heterogeneity In Chile

We analyze productivity growth in Chilean manufacturing 1979-2000 using the newly available panel of establishments drawn from the Census of Manufacturing. We examine the contribution to productivity growth of ?internal? restructuring (such as new technology and organizational change among survivors) and ?external? restructuring (exit, entry and market share change). We find that (a) ?external restructuring? accounts for 52% of industry labour productivity growth and 57% of industry TFP growth; (b) much of the external restructuring effect comes from the closing down of poorly-performing plants due to import penetration, and (c) import penetration is also an important determinant of internal restructuring in the long term.Productivity, TFP, Firm, Chile

Observation of surface states with algebraic localization

We introduce and experimentally demonstrate a class of surface bound states with algebraic decay in a one-dimensional tight-binding lattice. Such states have an energy embedded in the spectrum of scattered states and are structurally stable against perturbations of lattice parameters. Experimental demonstration of surface states with algebraic localization is presented in an array of evanescently-coupled optical waveguides with tailored coupling rates.Comment: revised version with Supplemental Material, to appear in Phys. Rev. Let

Terrain classification by cluster analisys

The digital terrain modelling can be obtained by different methods belonging to two principal categories: deterministic methods (e.g. polinomial and spline functions interpolation, Fourier spectra) and stochastic methods (e.g. least squares collocation and fractals, i.e. the concept of selfsimilarity in probability). To reach good resul ts, both the fi rst and the second methods need same initial suitable information which can be gained by a preprocessing of data named terrain classification. In fact, the deterministic methods require to know how is the roughness of the terrain, related to the density of the data (elevations, deformations, etc.) used for the i nterpo 1 at ion, and the stochast i c methods ask for the knowledge of the autocorrelation function of the data. Moreover, may be useful or very necessary to sp 1 it up the area under consideration in subareas homogeneous according to some parameters, because of different kinds of reasons (too much large initial set of data, so that they can't be processed togheter; very important discontinuities or singularities; etc.). Last but not least, may be remarkable to test the type of distribution (normal or non-normal) of the subsets obtained by the preceding selection, because the statistical properties of the normal distribution are very important (e.g., least squares linear estimations are the same of maximum likelihood and minimum variance ones)

Qualitative and quantitative analysis of mixtures of compounds containing both hydrogen and deuterium

Method allows qualitative and quantitative analysis of mixtures of partially deuterated compounds. Nuclear magnetic resonance spectroscopy determines location and amount of deuterium in organic compounds but not fully deuterated compounds. Mass spectroscopy can detect fully deuterated species but not the location

Polarization entangled state measurement on a chip

The emerging strategy to overcome the limitations of bulk quantum optics consists of taking advantage of the robustness and compactness achievable by the integrated waveguide technology. Here we report the realization of a directional coupler, fabricated by femtosecond laser waveguide writing, acting as an integrated beam splitter able to support polarization encoded qubits. This maskless and single step technique allows to realize circular transverse waveguide profiles able to support the propagation of Gaussian modes with any polarization state. Using this device, we demonstrate the quantum interference with polarization entangled states and singlet state projection.Comment: Revtex, 5+2 pages (with supplementary information), 4+1 figure

2D equivalent linear analysis for the seismic vulnerability evaluation of multi-propped retaining structures

The evaluation of the seismic behaviour of underground structures represents one of the most actual seismic geotechnical and structural engineering research topics about the study of the complex phenomena of soil-structural interaction. In the last decades, different types of simplified and numerical approaches have been developed for the correct analysis of the seismic vulnerability of these important infrastructures and a series of laboratory tests for the seismic behaviour characterization of the soils (resonant column test, etc.) and of the coupled soil-structure system (centrifuge test, etc.) have been conducted, especially after the recent strong earthquakes where the underground structures have been subjected to significant damages. In the same way, in the last few years, the International Codes are beginning to pay attention to the concepts of the seismic design of these structures. Despite the significant development of knowledge, described above, still remain open several uncertainties of the correct reproduction of the underground structures behaviour under seismic load. In this paper, the evaluation of the seismic behaviour of a multi-propped retaining structure was conducted, considering the soil-structure interaction effects. The results of the 2D equivalent linear analysis are analysed in terms of bending moment acting on the concrete retaining walls.L‘évaluation du comportement sismique des structures souterraines représentent un des sujets de recherche les plus courants sismique, géotechnique et de construction, qui concerne l‘étude du phénomène complexe de l‘interaction sol-structure. Pendant les dernières décennies, différents types d‘approches simples et numeriques ont été développés pour une analyse exacte de la vulnérabilité sismique de ces infrastructures importantes et encore une série de tests de laboratoire pour la caractérisation du comportement sismique du sols (test de colonne résonnante etc.) et du système couplé du sol-structure (test de centrifugation etc.) ont été menées, après le fort tremblement de terre où les structures souterraines ont subi des dommages importants. De la même manière, pendant les dèrnieres années, les Codes Internationales ont commencé a prêter plus d‘attention aux concepts de désign sismique de ces structures. Malgré la considèrable connaissance, décrit ci-dessus, il y a quand même de l‘incertitude sur la correcte reproduction du comportement des structures sous charge sismique. Dans cet article, il a été mené l‘evaluation du comportement sismique des structures de soutenement multi-etayé, considérant que les effets de l‘interaction sol-structure. Les resultats de l‘analyse linéaire 2D equivalente sont analysées en termes de moment de flexion agissant sur les murs de soutènement en béton

High-rate GPS positioning for tracing anthropogenic seismic activity. The 29 January 2019 mining tremor in Legnica- Głogów Copper District, Poland

High-rate GNSS observations are usually studied in relation to earthquake analysis and structural monitoring. Most of the previous research on short-term dynamic deformations has been limited to natural earthquakes with magnitudes exceeding 5 and amplitudes equal to several dozen centimetres. High-frequency position monitoring via GNSS stations is particularly important in mining areas due to the need to monitor mining damages. On 29 January 2019 (12:53:44 UTC), an M3.7 event occurred in the area of Legnica-Głogów Copper District. This study presents GPS-derived displacement analysis in relation to seismological data. Station position time series were determined by double differencing and Precise Point Positioning. The peak ground displacement was 2–14 mm. The correlation coefficients between GPS and seismological displacement time series reached 0.92. A statistical evaluation of GPS displacement time series was carried out to detect an event using only GPS observations

Tuning Fermi-surface properties through quantum confinement in metallic meta-lattices: New metals from old atoms

We describe a new class of nanoscale structured metals wherein the effects of quantum confinement are combined with dispersive metallic electronic states to induce modifications to the fundamental low-energy microscopic properties of a three-dimensional metal: the density of states, the distribution of Fermi velocities, and the collective electronic response.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let

Doping effects on the electronic and structural properties of CoO2: An LSDA+U study

A systematic LSDA+U study of doping effects on the electronic and structural properties of single layer CoO2 is presented. Undoped CoO2 is a charge transfer insulator within LSDA+U and a metal with a high density of states (DOS) at the Fermi level within LSDA. (CoO2)$^{1.0-}$, on the other hand, is a band insulator with a gap of 2.2 eV. Systems with fractional doping are metals if no charge orderings are present. Due to the strong interaction between the doped electron and other correlated Co d electrons, the calculated electronic structure of (CoO2)$^{x-}$ depends sensitively on the doping level x. Zone center optical phonon energies are calculated under the frozen phonon approximation and are in good agreement with measured values. Softening of the $E_g$ phonon at doping x ~0.25 seems to indicate a strong electron-phonon coupling in this system. Possible intemediate spin states of Co ions, Na ordering, as well as magnetic and charge orderings in this system are also discussed.Comment: 11 pages, 12 figure