Spectroscopic measurements of Mira variable stars as a function of phase probe the stellar atmospheres and underlying pulsation mechanisms. For example, measuring variations in TiO, VO, and ZrO with phase can be used to help determine whether these molecular species are produced in an extended region above the layers where Balmer line emission occurs or below this shocked region. Using the same methods, the Balmer line increment, where the strongest Balmer line at phase zero is Hδ and not Hα, can be measured and explanations tested, along with another peculiarity, the absence of the H∈ line in the spectra of Mira variables when the other Balmer lines are strong. We present new spectra covering the spectral range from 6200 to 9000 Å of 20 Mira variables. A relationship between variations in the Ca II IR triplet and Hα as a function of phase support the hypothesis that H∈'s observational characteristics result from an interaction of H∈ photons with the Ca II H line. New periods and epochs of variability are also presented for each star.

For a complete 12 μn flux-limited sample of 207 IRAS sources (F 12 ≥ 150 Jy, |b| ≥ 5°), the majority of which are AGB stars (∼87%), we have extracted light curves in seven infrared bands between 1.25 and 60 μm using the database of the Diffuse Infrared Background Experiment (DIRBE) instrument on the Cosmic Background Explorer (COBE) satellite. Using previous infrared surveys, we filtered these light curves to remove data points affected by nearby companions and obtained time-averaged flux densities and infrared colors, as well as estimates of their variability at each wavelength. In the time-averaged DIRBE color-color plots, we find clear segregation of semiregulars, Mira variables, carbon stars, OH/IR stars, and red giants without circumstellar dust (i.e., V-[12] < 5) and with little or no visual variation (ΔV < 0.1 mag). The DIRBE 1.25-25 μm colors become progressively redder and the variability in the DIRBE database increases along the oxygen-rich sequence nondusty slightly varying red giants→SRb/Lb→SRa→Mira→OH/IR and the carbon-rich SRb/Lb→Mira sequence. This supports previous assertions that these are evolutionary sequences involving the continued production and ejection of dust. The carbon stars are redder than their oxygen-rich counterparts for the same variability type, except in the F12/F25 ratio, where they are bluer. Of the 28 sources in the sample not previous noted to be variable, 18 are clearly variable in the DIRBE data, with amplitudes of variation of ∼0.9 mag at 4.9 μm and ∼0.6 mag at 12 μm, consistent with them being very dusty Mira-like variables. We also present individual DIRBE light curves of a few selected stars. The DIRBE light curves of the semiregular variable L2 Pup are particularly remarkable. The maxima at 1.25, 2.2, and 3.5 μm occur 10-20 days before those at 4.9 and 12 μm, and, at 4.9 and 12 μm, another maximum is seen between the two near-infrared maxima.

We have used the COBE DIRBE database to derive near- and mid-infrared light curves for a well-defined sample of 38 infrared-bright Mira variable stars and compared with optical data from the AAVSO. In general the 3.5 and 4.9 μm DIRBE bandpasses provide the light curves with the best signal-to-noise ratio (S/N), with S/N decreasing with wavelength at longer wavelengths. At 25 μm good light curves are only available for ∼10% of our stars, and at wavelengths ≥60 μm extracting high quality light curves is not possible. The amplitude of variability is typically less in the near-infrared than in the optical and less in the mid-infrared than in the near-infrared, with decreasing amplitude with increasing wavelength. On average there are 0.20 ± 0.01 mag variation at 1.25 μm and 0.14 ± 0.01 mag variation at 4.9 μm for each magnitude variation in V. The observed amplitudes are consistent with results of recent theoretical models of circumstellar dust shells around Mira variables. For a few stars in our sample we find clear evidence of time lags between the optical and near-infrared maxima of phase ∼0.05-0.13, with no lags in the minima. For three stars mid-infrared maximum appears to occur slightly before that in the near-infrared, but after optical maximum. We find three examples of secondary maxima in the rising portions of the DIRBE light curves, all of which have optical counterparts in the AAVSO data, supporting the hypothesis that they are due to shocks rather than newly formed dust layers. We find no conclusive evidence for rapid (hours to days) variations in the infrared brightnesses of these stars.

Dans cette thèse, j'analyse des observations spectropolarimétriques d'étoiles froides évoluées dans tous les paramètres de Stokes ($I$, $Q$, $U$ et $V$).L'étude des spectres polarisés circulairement de trois étoiles supergéantes rouges (RSG) m'a permis de détecter un faible champ magnétique (de l'ordre de 1 Gauss) à leur surface ainsi que de mettre en évidence l'influence de la forte polarisation linéaire de ces étoiles sur la mesure du champ magnétique.Cette forte polarisation linéaire est d'origine non magnétique et est reliée à la polarisation du continu dont l'observabilité résulte de la présence de structures brisants la symétrie cylindrique du disque stellaire.Après une analyse en profondeur de la polarisation du continu des étoiles RSG, j'utilise un modèle analytique spectropolarimétrique permettant de remonter à la position sur le disque de ces structures, en bon accord avec des observations interférométriques.Les étoiles variables pulsantes montrent elles aussi des signaux polarisés linéairement intenses dont l'origine est la polarisation intrinsèque (où de résonance) associée à certaines raies spectrales.Pour ces étoiles, les gradients de vitesses, introduits par les ondes de chocs se propageants dans leur atmosphère, amplifient la polarisation intrinsèque des raies, un mécanisme d'éclaircissement Doppler, bien connu dans le cas du Soleil, qui offre de nouvelles perspectives dans l'étude de ces objets. / In this thesis work, full Stokes ($I$, $Q$, $U$ et $V$) spectropolarimetric observations of cool evolved stars have been analysed.I have measured a weak magnetic field at the surface of three well known red supergiant stars. Furthermore, I have shown that the strong level of linear polarisation, measured for these stars, can lead to some ambiguity in the measurement of magnetic fields.This strong, unmagnetic, linear polarisation originate from depolarisation of the continuum which, in turn, is only detectable because of symmetry-breaking effects on the stellar disk.I study in some details the continuum polarisation of RSG stars and I present a way of mapping symmetry-breaking strucutres through the mean of a spectropolarimetric model. Good agreement with interferometric observations is reached.From their side, pulsating variable stars also show strong linearly polarised features in their spectra. These features are indeed due to resonant scattering polarisation associated to metallic lines, a phenomenon reminiscent of the second solar spectrum.For these stars, the velocity gradients, pertaining to the shock waves propagating through their atmosphere, enhance the intrinsic polarisation of the lines. This Doppler brightening effect, well known in the solar case, offer a new innovative method for the analysis of these stars.

SMOS (Soil Moisture and Ocean Salinity) is ESA's Earth Explorer series satellite carrying the novel MIRAS (Microwave Imaging Radiometer with Aperture Synthesis) interferometric synthetic aperture radar. Its objective is monitoring and studying the planet's water cycle by following the changes in soil moisture levels and ocean surface salt concentrations on a global scale. The success of the mission calls for nearly uninterrupted operation of the science payload. However, the instrument experiences sporadically problems with its hardware, which cause losses of scientific data and may require intervention from ground to resolve. The geographical areas in which most of these anomalies occur, polar regions and the South-Atlantic anomaly, give cause to assume these problems are caused by charged particles in the planet's ionosphere. In this thesis, methods of predicting occurrence of hardware anomalies from indicators of Earth radiation environment are investigated.

Dans une démarche d’éco-innovation, les entreprises cherchent à inventer et mettre en oeuvre de nouvelles activités plus durables parfois en rupture avec leurs pratiques existantes, et qui entraînent des changements plus ou moins importants au sein de leurs offres, de leur business model, et parfois sur l’ensemble de leurs écosystèmes. Confrontée à de tels enjeux et des dynamiques associées souvent complexes de par leur nature parfois techniques, économiques, sociales, juridiques, politiques…, l’entreprise et les parties prenantes du projet en émergence semblent ne pas toujours réussir à suffisamment s’écarter consciemment des cadres cognitifs existants pour explorer des alternatives en adéquation avec les ambitions initiales d’un projet d’éco-innovation. Ainsi, les trajectoires empruntées par ces projets sont susceptibles d’entrainer par exemple une dilution des valeurs environnementales et sociales ou de provoquer l’abandon de projets par un manque de considération des dimensions techniques ou économiques.Les travaux présentés ici portent sur la phase de maturation des concepts éco-innovants et cherchent à développer des modalités d’accompagnement pour éviter ou surpasser de telles situations dites de « fixation collective ».L’approche méthodologique repose sur une recherche-action effectuée au sein de l’organisme d’accompagnement Apesa structurée en deux étapes :- L’analyse de trois cas de projets d’éco-innovation nous a d’abord permis de caractériser la problématique des pratiques d’accompagnement et plus précisément les fixations collectives présentes lors de la maturation des concepts.- Cette première étude a alimenté la démarche de conception mise en oeuvre pour élaborer la méthode MIRAS, l’apport principal de notre recherche.La méthode MIRAS propose un panel d’outils d’animation destinés aux acteurs de l’accompagnement pour aider les groupes projets lors des phases de maturation de leur concept et de leur potentiel de soutenabilité en visant un certain équilibre du triptyque économique – environnemental – social). Dans cette optique, MIRAS vise à adopter une pensée systémique, qui ne soit pas centrée seulement sur l’entreprise mais qui reconsidère l’ensemble des dimensions du « réseau élargi des parties prenantes ». / During the development of eco-innovations, companies are looking to implement a new activity that can create ruptures with its existing practices and cause many changes in their business model. In such complex situations, the stakeholders of emerging projects have some difficulties to consciously deviate from existing cognitive frameworks to explore alternatives in line with the initial goals of the project. Thus, they take trajectories that may lead to a dilution of the environmental and social values or cause the abandonment of projects. The work presented here focuses on the maturation of eco-innovative concepts and seeks to develop tools and methods to avoid and overcome such situations called collective fixations.The methodological approach is based on an action research conducted in the organization Apesa and structured in two steps:- The analysis of three case-studies of eco-innovative projects allowed us to characterize supporting practices and deepen our knowledge on the collective fixation present during the maturation of concepts.- This first study has fueled the design process of the MIRAS method, the main contribution of our research.The MIRAS method offers a toolkit designed for eco-innovation intermediaries in order to help them to structure their intervention during the stage of concept maturation. Specifically the tools help to improve the sustainability potential of concepts, to analyze project group behaviors during sessions and to revisit stakeholder networks so as to anticipate future mutations and news ways of incubation.

We show some preliminary 10-37 micron high-resolution spectra taken with the Spitzer Space Telescope in 2008-9 of Mira variables distributed across the M, S and C chemical subclasses. Our entire Spitzer sample of 25 galactic Miras was observed from two to several times during this observing campaign and all have simultaneously measured near-infrared interferometric diameters acquired using the Palomar Testbed Interferometer. Because our sources are very bright for Spitzer IRS (typically 5-100 Janskys), we have excellent signal to noise and for many sources see marked changes in overall flux levels as a function of phase. Further, we are able to identify many strong emission lines and emission features due to silicate and carbon dusts and molecular constituents. We introduce the sample and the design of our experiment, discuss the data reduction required for such bright sources using Spitzer, show several examples of spectra with phase and discuss some preliminary findings. Finally, we discuss future steps for Paper II, to be presented later in the year.

La missió SMOS de l'Agència Europea de l'Espai (ESA) té com a objectiu mesurar la humitat del sòl i la salinitat dels oceans, paràmetres fonamentals per tal d'entendre el canvi climàtic global.MIRAS (Radiòmetre de microones generador d'imatges pel mètode de síntesi d'obertura) és un tipus d'instrument nou per a l'observació de la terra i és l'únic instrument de la missió SMOS. Consisteix en un agrupació aprimada (thinned array) en forma d'i grega amb 21 elements per braç. Amb aquesta tècnica s'aconsegueixen grans obertures sintètiques amb una massa relativament reduida.Aquesta nova tecnologia ha estat triada per a la missió SMOS, per tal d'acomplir els criteris de resolució espacial (30-50km) i de temps de revisita (3 dies). En el camp de la radioastronomia ja es fan servir instruments similars a MIRAS, però en aquest cas les fontsobservades tenen una mida angular reduïda (estrelles i galàxies). En el cas de MIRAS, la terra és una font extensa que cobreix pràcticament tot el camp de visió de MIRAS, de tal manera que les tècniques de calibració desenvolupades per a radioastronomia no sónvàlides per a la missió SMOS.Aquesta tesi es concentra principalment en comprovar experimentalment diferents tècniques de calibració i demostrar la capacitat de MIRAS per a generar imatges. La segona part està dedicada al mode polarimètric de MIRAS i a la capacitat d'aquest a millorar el rendiment de MIRAS. Aquest tesi es va iniciar l'any 2000 gràcies a una beca de dos anys (de l'estiu de 2000 a l'estiu de 2002) al centre ESTEC de l'Agència Europea de l'Espai als Països Baixos. Durant aquesta estada es van realitzar les primeres campanyes de mesura per tal de comprovar els mètodes de calibració i les capacitats de generar imatge de MIRAS. En aquests tests de validació d'imatge es va utilitzar un primer prototipus de MIRAS. La realització, planificació, preparació, execució i processament de les dades són part d'aquesta tesi. Aquelles campanyes van demostrar la capacitat dels mètodes de calibració indicant, a més en quina direcció calia continuar treballant per tal de refinar-los. També van demostrar la capacitat de MIRAS per a generar imatges,mitjançant la mesura de la seva resposta impulsional. En aquesta tesi se'n presenten els resultats més importants. Durant l'estada a ESTEC també es va realitzar treball teòric i simulacions sobre interferometria polarimètrica, contribuint d'aquesta manera a la formulació de la funció de visibilitat polarimètrica i a la definició del mode de funcionament polarimetric de MIRAS.La tesi es va continuar al Laboratori de Tecnologia Espacial (LST) de la Universitat Tecnològica de Hèlsinki (HUT) durant tres mesos (agost 2002 a octubre 2002) com a investigador convidat. Els coneixements adquirits prèviament van servir per a contribuir al desenvolupament de HUT-2D, el radiòmetre interferomètric aerotransportat de LST pensatcom a demostrador de la tecnologia emprada a MIRAS, confirmant els resultats obtinguts a les campanyes prèvies a ESTEC.El febrer de 2003 es va continuar la tesi a l'Institut d'Estudis Espacials de Catalunya (IEEC) amb un contracte de recerca del ministeri d'Educació i Ciència. Es va estudiar l'efecte dela rotació de Faraday a MIRAS. El resultat és una proposta de solució per a compensar-la fent servir el mode polarimètric de MIRAS. En el tram final de la tesi s'ha fet l'electrònica de control (EGSE) d'un demostrador aerotransportat de MIRAS (SAM), per a l'ESA. Aquest instrument permet fer ús del mètode de calibració per injecció de soroll a dues temperatures, que és un refinament dels anteriors mètodes de calibració dels prototipus de MIRAS. La tesi presenta resultats experimentals preliminars d'aquest mètode de calibració. / The SMOS mission of the European Space Agency (scheduled 2007) is devoted to measure Soil Moisture and Ocean Salinity, which are key parameters on the understanding of global climate change. The single instrument of this mission is the MIRAS (Microwave Imaging Radiometer using Aperture Synthesis), a new kind of instrument devoted to Earth observation. It is a thinned Y-shaped array with 21 elements per arm. With this technique a large synthetic aperture antenna with relative low weight can be obtained. This novel technique has been selected for the SMOS mission in order to fulfil both criteria ground resolution (35-50km) and revisit time (3 days). Similar instruments to MIRAS have already been used for radio astronomy but in that case only sources with a narrow angular size (stars and galaxies) were observed. In the case of MIRAS, the Earth is an extended source of thermal radiation, which almost fills up the complete field of view of MIRAS. The consequence of it is that the calibration techniques developed for radio astronomy may not be used in the SMOS mission. This thesis is mainly focused to experimentally test several calibration techniques and to prove the imaging properties of MIRAS. A second part is devoted to the polarimetric mode of MIRAS and its capability to improve its performance. This thesis was started thanks to a two year grant (from summer 2000 to summer 2002) at the ESTEC centre of the European Space Agency in the Netherlands. During this time the first experimental campaigns aimed to test calibration methods and imaging capabilities of MIRAS were done. In these so called image validation tests a first MIRAS prototype was used. The planning, preparation, execution and data processing for different tests was done. The capability of the calibration methods was demonstrated, showing also in which direction further research should be undertaken in order to refine them. The imaging properties of MIRAS were also demonstrated with the measurement of its impulsional response. The most important results are presented here. At the ESTEC centre theoretical work and simulations on polarimetric interferometry have also been done. This research contributed to the formulation of the polarimetric visibility function and the definition of the polarimetric operation mode of MIRAS. After the two years stage at ESTEC, the thesis was continued at the Laboratory of Space Technology (LST) of the Helsinki University of Technology (HUT) for three months (August 2002 to October 2002), as an invited researcher. There the HUT-2D interferometric radiometer, an airborne demonstrator instrument for MIRAS, was being constructed. The experience gained in the previous campaigns was shared with the HUT-2D team and the calibration methods were tested in a different instrument, confirming the previous results. In February 2003 this thesis was continued at the Institut d'Estudis Espacials de Catalunya (IEEC) under a research contract of the Spanish ministry of research. There the effect of Faraday rotation on MIRAS was studied. A solution for compensating it was proposed, making use of the polarimteric operation mode of MIRAS. The thesis was continued at IEEC, designing and manufacturing the Electrical Ground Support Equipment (EGSE) of an airborne demonstrator of MIRAS, known as SAM (Small Airborne MIRAS). This work was done for ESA. This instrument implements the complete calibration scheme with two-level noise injection, which is arefinement of the calibration schemes used in previous MIRAS prototypes. Preliminary experimental results of this novel calibration technique are also presented in this thesis.

In this thesis, it is aimed to make a study on Primary Schools of Rum Minority in Istanbul, and in light of this study, to define general principles for conservation studies on these schools. Rum Minority had an important part in social and cultural life in Istanbul and in late 19th Century, their impact in the city increased with their financial power, especially in Beyoglu. Increase in number of schools they built also occurred in the same timeline. Schools built in and after this term by Rum Minority were built as important public buildings of a minority group and possess strong authenticity, technical-artistic, socio-cultural and economical values. In order to decide which values, problems and potentials these buildings bear, a site survey study is done for this thesis. Primary Schools of Rum Minority in Istanbul are among strongest solid evidences of cultural diversity in Istanbul, and Turkey. While conserving these cultural assets, considering all their values, problems, and potentialities is vital. In addition to conservation studies, interpretation and presentation are also necessary steps for reintegration of these buildings to the city. This thesis performs as an effort made to document features and current state of these schools, decide their value, problems, and potentials / and defining general conservation principles for them.