We present new observations of the field containing the z = 3.786 protocluster PC 217.96+ 32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1 degrees.2 x 0 degrees.6 area (approximate to 150 x 75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Ly alpha emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i. e., within a radius of 2.5 comoving Mpc) of 14 +/- 7 relative to the average LAE spatial density ((rho) over bar) in the imaged field. Further, (rho) over bar is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 +/- 0.010. The velocity dispersion of galaxies near the core is sigma = 350 +/- 40 km s(-1), a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of > 10(15)M(circle dot) and > 6 x 10(14)M(circle dot) The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Ly alpha) luminosity and environmental density: the Ly alpha luminosity is enhanced on average by 1.35x within the protocluster core. There is no evidence that the Ly alpha equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC. 217.96+ 32.3 is a Coma cluster analog, witnessed in the process of formation.

We report the observation and confirmation of the first group-and cluster-scale strong gravitational lensing systems found in Dark Energy Survey data. Through visual inspection of data from the Science Verification season, we identified 53 candidate systems. We then obtained spectroscopic follow-up of 21 candidates using the Gemini Multi-object Spectrograph at the Gemini South telescope and the Inamori-Magellan Areal Camera and Spectrograph at the Magellan/Baade telescope. With this follow-up, we confirmed six candidates as gravitational lenses: three of the systems are newly discovered, and the remaining three were previously known. Of the 21 observed candidates, the remaining 15 either were not detected in spectroscopic observations, were observed and did not exhibit continuum emission (or spectral features), or were ruled out as lensing systems. The confirmed sample consists of one group-scale and five galaxy-cluster-scale lenses. The lensed sources range in redshift z similar to 0.80-3.2 and in i-band surface brightness i(SB) similar to 23-25 mag arcsec(-2) (2 '' aperture). For each of the six systems, we estimate the Einstein radius theta(E) and the enclosed mass M-enc, which have ranges theta(E) similar to 5 ''-9 '' and M-enc similar to 8 x 10(12) to 6 x 10(13)M(circle dot), respectively.

On 2014 December 9.61, the All-sky Automated Survey for SuperNovae (ASAS-SN or "Assassin") discovered ASASSN-141p just similar to 2 days after first light using a global array of 14 cm diameter telescopes. ASASSN-141p went on to become a bright supernova (V = 11.94 mag), second only to SN 2014J for the year. We present prediscovery photometry (with a detection less than a day after first light) and ultraviolet through near-infrared photometric and spectroscopic data covering the rise and fall of ASASSN-141p for more than 100 days. We find that ASASSN-141p had a broad light curve (Delta m(15) (B) = 0.80 +/- 0.05), a B-band maximum at 2457015.82 +/- 0.03, a rise time of 16.941(-0.10)(+0.11) days, and moderate host-galaxy extinction (E (B - V)host = 0.33 +/- 0.06). Using ASASSN-141p, we derive a distance modulus for NGC 4666 of mu = 30.8 +/- 0.2, corresponding to a distance of 14.7 +/- 1.5 Mpc. However, adding ASASSN-141p to the calibrating sample of Type Ia supernovae still requires an independent distance to the host galaxy. Finally, using our early-time photometric and spectroscopic observations, we rule out red giant secondaries and, assuming a favorable viewing angle and explosion time, any nondegenerate companion larger than 0.34 RG(circle dot).

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Given the ubiquity of time series data, and the exponential growth of databases, there has recently been an explosion of interest in time series data mining. Finding similar trends and patterns among time series data is critical for many applications ranging from financial planning, weather forecasting, stock analysis to policy making. With time series being high-dimensional objects, detection of similar trends especially at the granularity of subsequences or among time series of different lengths and temporal misalignments incurs prohibitively high computation costs. Finding trends using non-metric correlation measures further compounds the complexity, as traditional pruning techniques cannot be directly applied. My dissertation addresses these challenges while meeting the need to achieve near real-time responsiveness. First, for retrieving exact similarity results using Lp-norm distances, we design a two-layered time series index for subsequence matching. Time series relationships are compactly organized in a directed acyclic graph embedded with similarity vectors capturing subsequence similarities. Powerful pruning strategies leveraging the graph structure greatly reduce the number of time series as well as subsequence comparisons, resulting in a several order of magnitude speed-up. Second, to support a rich diversity of correlation analytics operations, we compress time series into Euclidean-based clusters augmented by a compact overlay graph encoding correlation relationships. Such a framework supports a rich variety of operations including retrieving positive or negative correlations, self correlations and finding groups of correlated sequences. Third, to support flexible similarity specification using computationally expensive warped distance like Dynamic Time Warping we design data reduction strategies leveraging the inexpensive Euclidean distance with subsequent time warped matching on the reduced data. This facilitates the comparison of sequences of different lengths and with flexible alignment still within a few seconds of response time. Comprehensive experimental studies using real-world and synthetic datasets demonstrate the efficiency, effectiveness and quality of the results achieved by our proposed techniques as compared to the state-of-the-art methods.

Submitted by Adriana Alves Rodrigues (aalves@espm.br) on 2017-11-06T13:13:25Z No. of bitstreams: 1 Fabio Cássio de Souza.pdf: 1627330 bytes, checksum: 71873750a643ef670bbe26fb9724e15a (MD5) / Approved for entry into archive by Adriana Alves Rodrigues (aalves@espm.br) on 2017-11-06T13:14:58Z (GMT) No. of bitstreams: 1 Fabio Cássio de Souza.pdf: 1627330 bytes, checksum: 71873750a643ef670bbe26fb9724e15a (MD5) / Approved for entry into archive by Ana Cristina Ropero (ana@espm.br) on 2017-11-10T12:11:28Z (GMT) No. of bitstreams: 1 Fabio Cássio de Souza.pdf: 1627330 bytes, checksum: 71873750a643ef670bbe26fb9724e15a (MD5) / Made available in DSpace on 2017-11-10T12:13:32Z (GMT). No. of bitstreams: 1 Fabio Cássio de Souza.pdf: 1627330 bytes, checksum: 71873750a643ef670bbe26fb9724e15a (MD5) Previous issue date: 2016-02-26 / The survival of the subsidiary is an important indicator of the success of foreign investments. Several studies focus efforts on survival testing. The institutional approach emerges as an alternative research topic. However, they are generally restricted to few national institutional distances. This research is intended to contribute to the literature examining the impact of nine institutional distances (ID) on the survival of subsidiary in a different continent than the parent. In addition, it investigates the local experience and its reducing national institutional distances. The hypotheses were tested in 1,650 observations of subsidiaries in 36 countries, in a longitudinal study in the period of 2007-2014. The hazard ratio was implemented with the Cox Regression for the execution. The models indicated effectiveness with a high degree of significance. The results suggest that national DIs have a significant impact on survival. Between the nine DI examined, six evidence of survival risk related to administrative aspects, demographic, political, knowledge, global and cultural. Local experience also plays a relevant role for continuity, however, it is not able to moderate DI for the survival of the subsidiary. It is hoped that this evidence can provide important information for the strategic process and contribute to the success and survival of international operations. / A sobrevivência da subsidiária é importante indicador de sucesso de investimentos estrangeiros. Diversos estudos concentram esforços no exame da sobrevivência. A abordagem institucional surge como uma alternativa de investigação do tema. No entanto, são geralmente restritos a poucas distâncias institucionais nacionais. Esta investigação tem o intuito de contribuir para a literatura ao examinar o impacto de nove distâncias institucionais (DI) na sobrevivência da subsidiária em continente diferente da matriz. Além disto, investiga a experiência local e seu efeito moderador na redução das distâncias institucionais nacionais. As hipóteses foram testadas em 1.650 observações de subsidiárias em 36 países, em estudo longitudinal no período de 2007-2014. A Taxa de Risco (hazard ratio) foi implementada com a Regressão Cox para a execução. Os modelos indicaram efetividade com alto grau de significância. Os resultados sugerem que as DI nacionais impactam significativamente na sobrevivência. Entre as nove DI examinadas, seis evidenciam o risco à sobrevivência relacionados aos aspectos administrativos, demográficos, políticos, conhecimento, global e cultural. A experiência local também desempenha papel relevante para a continuidade, entretanto, não é capaz de moderar as DI para a sobrevivência da subsidiária. Espera-se que estas evidências possam fornecer importantes informações para o processo estratégico e contribuir para o sucesso e sobrevivência das operações internacionais.

Antes de se fazer uma estimativa ou uma simulação geoestatística, os domínios geológicos devem ser modelados de forma que cada domínio utilize apenas dados que pertencem a ele. Na industria mineral a incerteza oriunda dos teores geralmente é levada em consideração, entretanto a incerteza gerada pelo modelo nem sempre é analisada. Sabendo que a maior fonte de incerteza está na transição de uma litologia para outra, essa dissertação visa avaliar a incerteza do modelo geológico através de simulações de funções distâncias assinaladas em zonas de maior incerteza, gerando vários modelos com diferentes proporções de cada litologias. Um estudo de caso em um banco de dados real com alta complexidade geológica é utilizado para avaliar o uso da metodologia. O método se mostrou eficaz para avaliar o impacto da diferença de volume que cada litologia pode alcançar, demonstrando a importância de medir a incerteza na construção de modelos geológicos. / Before making an estimation or a geostatistical simulation, geological domains must be modeled so that each domain uses only data that belongs to it. In the mineral industry the uncertainty derived from the grades is generally taken into account, however the uncertainty generated by the model is not always analyzed. Knowing that the greatest source of uncertainty is in the transition from one lithology to another, this dissertation aims to evaluate the uncertainty of the geological model through signed distances function simulation in uncertainty zones, generating several models with different proportions of each lithology. A case study in a real dataset with high geological complexity is used to evaluate the use of the methodology. The method proved effective in assessing the impact of the volume difference that each lithology can reach, demonstrating the importance of measuring uncertainty in the construction of geological models.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO. / Includes bibliographical references. / Ph.D.

La méthode de la parallaxe de pulsation, appliquée à des observations VINCI du VLTI, a permis la détermination de distance de sept Céphéides Galactiques. Pour l Car, la plus résolue d'entre elles, la précision obtenue est de 5%. Le point-zéro de la relation P-L a également été déterminée avec une précision de 0.08 magnitude. Les mesures interférométriques fournissent la variation du diamètre angulaire de l'étoile sur tout le cycle de pulsation, tandis que la variation du diamètre linéaire est déterminée par une intégration temporelle de la vitesse pulsante photosphérique Vpuls de l'étoile. Or la détermination de cette dernière, à partir du décalage Doppler de la raie spectrale Vrad est extrêmement délicate. Le facteur de projection, défini par p=Vpuls/Vrad est en effet très sensible aux paramètres physiques et à la dynamique atmosphérique de l'étoile. En particulier, les gradients de vitesse dans l'atmosphère des Céphéides, pose la question de la définition de la vitesse pulsante. Premièrement, un modèle hydrodynamique a permis d'étudier les gradients de vitesse dans l'atmosphère de d Cep. La différence de vitesse obtenue entre la vitesse photosphérique et la vitesse associée à la zone de formation de la raie, affecte le facteur de projection et donc la distance à un niveau de 6%. Deuxièmement, en comparant le modèle géométrique simple à des observations à haute résolution spectrale HARPS de neuf Céphéides, l'impact de la dynamique atmosphérique des étoiles sur l'asymétrie des raies spectrales a été mis en évidence. Troisièmement, le modèle hydrodynamique a permis de faire le lien entre les gradients de vitesse dans l'étoile, le facteur de projection, et les observables spectro-interférométriques. Ceci pourrait constituer un moyen supplémentaire pour contraindre observationnellement le facteur de projection. La connaissance du facteur de projection dans le cadre du futur survey AMBER est crucial. Nous envisageons de déterminer la distance d'une trentaine de Céphéides à mieux que 5%, afin de calibrer le point zéro de la relation P-L avec une précision de 0.01 magnitude.

Les Etats dits « sahéliens » sont souvent identifiés comme enclavés. Dans une forme de stéréotype de l'espace marginalisé, une position continentale est un élément supplémentaire des difficultés économiques. La continentalité, anciennement centrale en Afrique de l'ouest, devient une situation périphérique, c'est à dire une fermeture ou une distance au Monde. Le choix d'étude d'une circulation terrestre permettant l'ouverture littorale propose un regard sur cet enclavement. Dans un espace ouest africain international, les pouvoirs politiques ont produit les instruments d'une circulation établissant la relation entre les espaces continentaux devenus territoires d'Etat et les interfaces littorales. Mais cette réponse est dysfonctionnante. Un ensemble de contraintes techniques, politiques, économiques, produit un processus de discontinuités. L'enclavement est un système de distances qui éloigne les opérateurs continentaux de certaines ouvertures. Mais ces espaces enclavés ne sont pas enfermés. Les actions contemporaines des bailleurs de fonds et des opérateurs privés tendent à sélectionner et moderniser des axes validant une stratégie d'inscription d'espaces d'activités dans les réseaux mondiaux. Il se développe une recomposition des territoires intérieurs réduisant la fracture entre les positions étatiques littorale et continentale. Et cette fracture est souvent dépassée et même utilisée dans les circulations s'inscrivant dans l'espace ouest africain. L'enclavement continental n'est pas une position spatiale de fermeture figée. Il est une situation relative qui tient dans les permanences de certaines discontinuités qui ne sont pas annulées par les différents pouvoirs politiques.