Papers by Leonardo Alvarez
We have recently developed a true broadband Fourier transform microwave (FTMW) spectrometer that ... more We have recently developed a true broadband Fourier transform microwave (FTMW) spectrometer that obtains the rotational spectrum in the 7.5 -- 18.5 GHz range with 50 kHz resolution for each individual valve pulse in a molecular beam spectrometer. The ability to observe an 11 GHz broad rotational spectrum for each valve pulse is particularly useful for experiments where the molecular beam source conditions require optimization and in cases where the biological sample decomposes over a time scale of a few minutes. The high resolution of the measurement makes it possible to unravel the conformational complexity of gas phase biomolecules. Conformational assignments of the pure rotational spectrum of p-methoxyphenethylamine (MPEA) will be presented to illustrate the capabilities of the spectrometer. The spectrometer can also be employed in laser-FTMW double-resonance experiments where the conformational assignments in the pure rotational spectrum are used to automatically assign absorption features in either vibrational or electronic spectra.
Landscape and Urban Planning, 1995
A regional greenway network is proposed to reconnect ecologically the fragmented landscapes of so... more A regional greenway network is proposed to reconnect ecologically the fragmented landscapes of south Florida. The natural landscapes of the region have been progressively fragmented on account of agricultural and urban development. It is proposed that the regional system of drainage canals and reservoir levees, which was originally developed to facilitate agriculture and urbanization, be ecologically reclaimed and managed to become a network of environmental restoration and cultural opportunity for south Florida. The existing regional system of drainage canals and reservoir levees is restrictively underutilized. In general, the value of utility and transportation corridors as natural and cultural resources has not been fully appreciated in south Florida. Their value as resources lies in the ample opportunity they offer for landscape revegetation, wetland reclamation, habitat restoration, and community education and recreation. In particular, the existing regional system of drainage canals and reservoir levees represents an extensive resource that can naturally and culturally link the fragmented landscapes of south Florida while maintaining flood control and water conservation.
Pure and Applied Geophysics, 2007
An overview of the crust and upper mantle structure of Central America and the Caribbean region i... more An overview of the crust and upper mantle structure of Central America and the Caribbean region is presented as a result of the processing of more than 200 seismograms recorded by digital broadband stations from SSSN and GSN seismic networks. Group velocity dispersion curves are obtained in the period range from 10s to 40s by FTAN analysis of the fundamental mode of the Rayleigh waves; the error of these measurements varies from 0.06 and 0.09 km/s. From the dispersion curve, seven tomographic maps at different periods and with average spatial resolution of 500 km are obtained. Using the logical combinatorial classification techniques, eight main groups of dispersion curves are determined from the tomographic maps and eleven main regions, each one characterized by one kind of dispersion curves, are identified. The average dispersion curves obtained for each region are extended to 150s by adding data from a larger-scale tomographic study (Vdovin et al., 1999) and inverted using a nonlinear procedure. A set of models of the S-wave velocity vs. depth in the crust and upper mantle is found as a result of the inversion process. In six regions we identify a typically oceanic crust and upper mantle structure, while in the other two the models are consistent with the presence of a continental structure. Two regions, located over the major geological zones of the accretionary crust of the Caribbean region, are characterized by a peculiar crust and upper mantle structure, indicating the presence of lithospheric roots reaching, at least, about 200 km of depth.
Soil Dynamics and Earthquake Engineering, 2005
Synthetic seismograms (P -SV and SH waves) have been calculated along 6 profiles in Santiago de C... more Synthetic seismograms (P -SV and SH waves) have been calculated along 6 profiles in Santiago de Cuba basin, with a cutoff frequency of 5 Hz, by using the hybrid approach (modal summation for a regional (1D) structure plus finite differences for a local (2D) structure embedded in the first). They correspond to a scenario earthquake of M S = 7 that may occur in Oriente fault zone, directly south of the city. As initial data for a seismic microzoning, the characterisation of earthquake effects has been made considering several relative (2D / 1D) quantities (PGDR, PGVR, PGAR, DGAR, I A R , etc.) and functions representative of the ground motion behaviour in soil (2D) with respect to bedrock (1D). The functions are the response spectra ratio RSR(f), already routinely used in this kind of work, and the elastic energy input ratio E I R(f), defined, for the first time, in this paper.
Pure and Applied Geophysics, 2004
— The expected ground motion in Santiago de Cuba basin from earthquakes which occurred in the Ori... more — The expected ground motion in Santiago de Cuba basin from earthquakes which occurred in the Oriente fault zone is studied. Synthetic SH-waves seismograms have been calculated along four profiles in the basin by the hybrid approach (modal summation for the path source-profile and finite differences for the profile) for a maximum frequency of 1 Hz. The response spectra ratio (RSR) has been determined in 49 sites, distributed along all considered profiles with a spacing of 900 m. The corresponding RSR versus frequency curves have been classified using a logical-combinatorial algorithm. The results of the classification, in combination with the uppermost geological setting (geotechnical information and geological geometry of the subsoil) are used for the seismic zoning of the city. Three different main zones are identified, and a small sector characterized by major resonance effects, due to the particular structural conditions. Each zone is characterized in terms of its expected ground motion parameters for the most probable strong earthquake (M S =7), and for the maximum possible (M S =8).
Pure and Applied Geophysics, 1999
—A deterministic seismic zoning of Cuba is performed by modelling, with modal summation, the comp... more —A deterministic seismic zoning of Cuba is performed by modelling, with modal summation, the complete P-SV and SH waves fields generated by point-source earthquakes buried in flat-layered anelastic media. The results of the computation, performed for periods greater than 1 second, are presented in two sets of maps of maximum displacement (d max), maximum velocity (v max) and design ground acceleration (DGA), obtained by using two different criteria in the definition of the input magnitude: (1) values reported in the earthquake catalogue (M obs) and (2) values determined from seismotectonic considerations (M max). A comparison with the results of a previous probabilistic seismic zoning is made to test the possibility of making intensity — ground motion conversion with the aid of log-linear regressions.
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Papers by Leonardo Alvarez