Atiya-Bott theory for orbifolds and Dedkind sums

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1994.Includes bibliographical references (leaf 17).by Ana M.L.G. Canas da Silva.M.S

Estudio de atenuación sísimica en la costa este de la Península Ibérica

El gradiente de decaimiento de la amplitud a lo largo de la coda se caracteriza por el parámetro coda-Q-1 (Qc-1) que es constante independientemente de la localización de la fuente sísmica y de la estación de registro en una región determinada, y que representa una estimación de la atenuación sísmica introducida por el medio. Otros parámetros que caracterizan la atenuación sísmica son: la absorción intrínseca ( Qi-1 ), la atenuación por dispersión ( Q8-1) y la atenuación total Qt –1= Qi-1 + Q8-1. En el presente estudio se han analizado 64 terremotos registrados por 11 estaciones de período corto distribuidas a lo largo de la costa este de la Península Ibérica, de cara a la estimación de la atenuación sísmica y su dependencia frecuencial. En este trabajo se describe el método numérico utilizado y se presentan los parámetros de atenuación estimados para la costa mediterránea española

Aplicación del cálculo paralelo al análisis de energía sísmica en la coda de terremotos regionales

Coda waves constitute a powerful tool for the estimation of the seismic wave attenuation in the Earth s lithosphere. Total attenuation includes two effects: intrinsic absorption and scatttering, that can be separated if we perform a multiple scattering modelling of the coda envelope. In this paper we will compare, in terms of the computational point of view, two techniques (a Montecarlo simulation and an analytical procedure) for obtaining the theoretical space and time distribution of the seismic energy in the coda, under the hypothesis of multiple isotropic scattering and uniform distribution of scatterers. We will study the characteristic of the algorithms and will use parallelization techniques in order to reduce the time required for obtaining the results

Aplicación del cálculo paralelo al análisis de energía sísmica en la coda de terremotos regionales

Las ondas de coda constituyen un instrumento muy útil de cara a la estimación de la atenuación de las ondas sísmicas durante su propagación a través de la litosfera terrestre. La atenuación total consta de dos efectos principales: la absorción intrínseca y la dispersión, que pueden ser separados si se efectúa una modelización de la envolvente de la coda sobre la base de la teoría de esparcimiento múltiple. En este trabajo compararemos, desde el punto de vista computacional, dos técnicas (una simulación por el método de Montecarlo y un procedimiento analítico) para obtener la distribución espacio-temporal teórica de la energía sísmica en la coda, bajo las hipótesis de dispersión isótropa múltiple y distribución uniforme de dispersores. Para ello estudiaremos las características de los algoritmos e introduciremos el cálculo paralelo, en un intento de reducir el tiempo de computación necesario para obtener los resultados.Coda waves constitute a powerful tool for the estimation of the seismic wave attenuation in the Earth's lithosphere. Total attenuation includes two effects: intrinsic absorption and scatttering, that can be separated if we perform a multiple scattering modelling of the coda envelope. In this paper we will compare, in terms of the computational point of view, two techniques (a Montecarlo simulation and an analytical procedure) for obtaining the theoretical space and time distribution of the seismic energy in the coda, under the hypothesis of multiple isotropic scattering and uniform distribution of scatterers. We will study the characteristic of the algorithms and will use parallelization techniques in order to reduce the time required for obtaining the results.Peer Reviewe

Alternative structures and bi-Hamiltonian systems on a Hilbert space

We discuss transformations generated by dynamical quantum systems which are bi-unitary, i.e. unitary with respect to a pair of Hermitian structures on an infinite-dimensional complex Hilbert space. We introduce the notion of Hermitian structures in generic relative position. We provide few necessary and sufficient conditions for two Hermitian structures to be in generic relative position to better illustrate the relevance of this notion. The group of bi-unitary transformations is considered in both the generic and non-generic case. Finally, we generalize the analysis to real Hilbert spaces and extend to infinite dimensions results already available in the framework of finite-dimensional linear bi-Hamiltonian systems.Comment: 11 page

Bioclimatology, structure, and conservation perspectives of Quercus pyrenaica, Acer opalus subsp. Granatensis, and Corylus avellana deciduous forests on Mediterranean bioclimate in the South-Central part of the Iberian Peninsula

The plant variability in the southern Iberian Peninsula consists of around 3500 different taxa due to its high bioclimatic, geographic, and geological diversity. The deciduous forests in the southern Iberian Peninsula are located in regions with topographies and specific bioclimatic conditions that allow for the survival of taxa that are typical of cooler and wetter bioclimatic regions and therefore represent the relict evidence of colder and more humid paleoclimatic conditions. The floristic composition of 421 samples of deciduous forests in the south-central part of the Iberian Peninsula were analyzed. The ecological importance index (IVI) was calculated, where the most important tree species were Quercuspyrenaica, Aceropalus subsp. Granatensis, and Corylusavellana. These species are uncommon in the south-central part of the Iberian Peninsula, forming forests of little extension. An analysis of the vertical distribution of the species (stratum) shows that the majority of the species of stratum 3 (hemicriptophics, camephytes, geophites, and nanophanerophytes) are characteristic of deciduous forests, and their presence is positively correlated with high values of bioclimatic variables related to humidity and presence of water in the soil (nemoral environments), while they are negatively correlated with high values of bioclimatic variables related to high temperatures, evapotranspiration, and aridity. This work demonstrates that several characteristic deciduous forest taxa are more vulnerable to disappearance due to the loss of their nemoral conditions caused by gaps in the tree or shrub canopy. These gaps lead to an increase in evapotranspiration, excess insolation, and a consequent loss of water and humidity in the microclimatic conditions.info:eu-repo/semantics/publishedVersio

Multiplicity formulas for orbifolds

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1996.Includes bibliographical references (p. 46-47).by Ana M.L.G. Canas da Silva.Ph.D

Development and validation of a robust automated analysis of plasma phospholipid fatty acids for metabolic phenotyping of large epidemiological studies.

A fully automated, high-throughput method was developed to profile the fatty acids of phospholipids from human plasma samples for application to a large epidemiological sample set (n > 25,000). We report here on the data obtained for the quality-control materials used with the first 860 batches, and the validation process used. The method consists of two robotic systems combined with gas chromatography, performing lipid extraction, phospholipid isolation, hydrolysis and derivatization to fatty-acid methyl esters, and on-line analysis. This is the first report showing that fatty-acid profiling is an achievable strategy for metabolic phenotyping in very large epidemiological and genetic studies.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are