This thesis presents an investigation of ensemble Gaussianity, the effect of non- Gaussianity on covariance structures, storm-centered data assimilation techniques, and the relationship between commonly used data assimilation variables and the underlying dynamics for the case of Hurricane Humberto. Using an Ensemble Kalman Filter (EnKF), a comparison of data assimilation results in Storm-centered and Eulerian coordinate systems is made. In addition, the extent of the non-Gaussianity of the model ensemble is investigated and quantified. The effect of this non-Gaussianity on covariance structures, which play an integral role in the EnKF data assimilation scheme, is then explored. Finally, the correlation structures calculated from a Weather Research Forecast (WRF) ensemble forecast of several state variables are investigated in order to better understand the dynamics of this rapidly intensifying cyclone. Hurricane Humberto rapidly intensified in the northwestern Gulf of Mexico from a tropical disturbance to a strong category one hurricane with 90 mph winds in 24 hours. Numerical models did not capture the intensification of Humberto well. This could be due in large part to initial condition error, which can be addressed by data assimilation schemes. Because the EnKF scheme is a linear theory developed on the assumption of the normality of the ensemble distribution, non-Gaussianity in the ensemble distribution used could affect the EnKF update. It is shown that multiple state variables do indeed show significant non-Gaussianity through an inspection of statistical moments. In addition, storm-centered data assimilation schemes present an alternative to traditional Eulerian schemes by emphasizing the centrality of the cyclone to the assimilation window. This allows for an update that is most effective in the vicinity of the storm center, which is of most concern in mesoscale events such as Humberto. Finally, the effect of non-Gaussian distributions on covariance structures is examined through data transformations of normal distributions. Various standard transformations of two Gaussian distributions are made. Skewness, kurtosis, and correlation between the two distributions are taken before and after the transformations. It can be seen that there is a relationship between a change in skewness and kurtosis and the correlation between the distributions. These effects are then taken into consideration as the dynamics contributing to the rapid intensification of Humberto are explored through correlation structures.

 The integration of immigrants is a major source of social tension in multicultural cities. In Europe, the issue has become particularly contentious after the attacks of September 2001. Cities and societies are not immune to the challenges of social fragmentation and polarization caused by the forces of global migration. This thesis addresses the central question of why the course of integration remains largely problematic and difficult in cities that have become accustomed to diversity. It responds to the existing weaknesses of mainstream research paradigms by conducting a comparative and interdisciplinary analysis of the development of integration regimes in Berlin and Hong Kong that casts doubts on the ability of the ‘multicultural’ politics to mitigate the consequences of immigration and integration in cities. This thesis suggests that the course of integration is a global as well as a local challenge that is simultaneously affected by the forces of globalization and shaped by the distinctive socio-economic context and cultural-historical background of each receiving city. The comparative study demonstrates that the challenges in Berlin are embedded in the broader European anxiety over the two-fold threats of Islam and terrorism, the ethno-cultural German tradition, and the city’s strained socio-economic situation. The problems with integration in Hong Kong are closely related to the colonial legacy, the city’s difficult integration with mainland China, and the surging political sentiment in society. The study suggests that cities and local governments are not as accommodating to diversity as they claim to be, as racial discrimination and exclusion remain commonplace in both cities. It also rejects the presumed link between the celebration of diversity and the successful course of integration which is entangled with the limitations of the existing ‘multicultural paradigm’ that influences the policymaking. This thesis shows how the paradigm contributes to the growing gap between the active integration policy and the actual predicaments of integration. By offering a global comparative perspective, this cross-regional study is in a better position to capture the current trend of development and to explain concrete problems with integration in cities, thereby addressing some of the limitations of the mainstream nation-centered studies confined to the Western context. / published_or_final_version / Modern Languages and Cultures / Master / Master of Philosophy

Förutsättningar för inkorporation – upplevelsen av möjligheten är en studie, skriven av Hanna Öfors, som sätter fokus på invandrares upplevelse av sin möjlighet att bli en del av det svenska samhället. Detta har gjorts genom fyra djupintervjuer med invandrare som har kommit till Sverige i vuxen ålder och som kan betraktas som relativt sätt tillfredsställande fall, om deras egna upplevelser.  Studiens syfte är att teckna en bild av hur nysvenskar upplever sin inkorporationsprocess och möjlighet till delaktighet i det svenska samhället.  Dessutom är studiens strävan att identifiera vilka komponenter som är av betydelse för en upplevelse av delaktighet respektive utanförskap. Den teoretiska referensram som studien utgår ifrån innefattar dels kapitalteori med särskilt fokus på socialt kapital, och dels av teorier om delaktighet och utanförskap samt identitet, vilket har infogats som komplement till dig förstnämnda. Den tidigare forskning som presenteras lyfter fram äktenskap och samboskap som positivt för inkorporationen. Resultatet av undersökningen visar att det är viktigt att individen har ett högt socialt kapital inom minst ett fält för att hen ska kunna känna delaktighet och tillhörighet i det svenska samhället.  Att ha ett arbete lyfts av flera informanter fram som extra viktigt för denna möjlighet.  Vidare visar resultatet också, vilket understöds av tidigare forskning, att en relation, såsom äktenskapet, innebär ett ökat socialt kapital och därmed ökad möjlighet till delaktighet och tillhörighet i det svenska samhället. Genom att ta reda på vad som förutsätts för att en inkorporationsprocess skall upplevas som tillfredsställande skulle det kunna bli möjligt att påverka diskursen kring invandring och inkorporation i en positiv och mer gynnsam riktning för de individer som framgent kommer till Sverige. / Conditions for incorporation – experience of possibility is a study written by Hanna Öfors. It focuses on immigrants and their experience of the possibility to be included as a part of the Swedish society. This is done, by interviewing four people who moved too Sweden as grownups and whom, relatively speaking, could be looked at as cases of satisfying incorporation,   about their experiences of incorporation. The purpose of this study is to investigate and understand how immigrants look at their incorporation process and the degree to which it is possible for them to be a part of the Swedish society. Moreover, it is meant to identify the components that are important for them to feel included in or excluded from the Swedish society.  The frame of reference that this study is based on is built on three components, capital theory, concentrated on social capital, and theories about participation, alienation and identity. The three latest terms has added as a complement to capital theory. Recent research says that partnership and marriage has a positive effect on incorporation.    The results show that an individual ought to have a large amount of social capital, in at least one field, for them to feel a part of the Swedish society.  Employment is pointed out to be an extra important factor for this possibility. It is also shown that a relationship, such as marriage, leads to an increase in social capital. The same results are also proved in earlier studies.  By finding what is needed, for an incorporation process to be satisfying, it could be possible to influence the discourse around immigration and incorporation in a positive way. Hopefully this could lead to more favorable conditions for immigrants in the future.

Filtering problems in high dimensional geophysical applications often require spatially continuous models to interpolate spatially and temporally sparse data. Many applications in numerical weather and ocean state prediction are concerned with tracking and assessing the uncertainty in the position of large scale vorticity features, such as storm fronts, jets streams, and hurricanes. Quantifying the amplitude variance in these features is complicated by the fact that both height and lateral perturbations in the feature geometry are represented in the same covariance estimate. However, when there are sufficient observations to detect feature information like spatial gradients, the positions of these features can be used to further constrain the filter, as long as the statistical model (cost function) has provisions for both height perturbations and lateral displacements. Several authors since the 1990s have proposed various formalisms for the simultaneous modeling of position and amplitude errors, and the typical approaches to computing the generalized solutions in these applications are variational or direct optimization. The ensemble Kalman filter is often employed in large scale nonlinear filtering problems, but its predication on Gaussian statistics causes its estimators suffer from analysis deflation or collapse, as well as the usual curse of dimensionality in high dimensional Monte Carlo simulations. Moreover, there is no theoretical guarantee of the performance of the ensemble Kalman filter with nonlinear models. Particle filters which employ importance sampling to focus attention on the important regions of the likelihood have shown promise in recent studies on the control of particle size. Consider an ensemble forecast of a system with prominent feature information. The correction of displacements in these features, by pushing them into better agreement with observations, is an application of importance sampling, and Monte Carlo methods, including particle filters, and possibly the ensemble Kalman filter as well, are well suited to applications of feature displacement correction. In the present work, we show that the ensemble Kalman filter performs well in problems where large features are displaced both in amplitude and position, as long as it is used on a statistical model which includes both function height and local position displacement in the model state. In a toy model, we characterize the performance-degrading effect that untracked displacements have on filters when large features are present. We then employ tools from classical physics and fluid dynamics to statistically model displacements by area-preserving coordinate transformations. These maps preserve the area of contours in the displaced function, and using strain measures from continuum mechanics, we regularize the statistics on these maps to ensure they model smooth, feature-preserving displacements. The position correction techniques are incorporated into the statistical model, and this modified ensemble Kalman filter is tested on a system of vortices driven by a stochastically forced barotropic vorticity equation. We find that when the position correction term is included in the statistical model, the modified filter provides estimates which exhibit substantial reduction in analysis error variance, using a much smaller ensemble than what is required when the position correction term is removed from the model.

Le 29 février 1704, une force de 250 alliés franco-amérindiens attaque le petit village frontalier de Deerfield au Massachusetts et enlève 112 habitants. De ce nombre, 89 parviennent vivants en Nouvelle-France. À la fin de la guerre de Succession d’Espagne, 25 d’entre eux finissent par s’installer parmi les Français ou les Amérindiens. Pendant longtemps, ils auront le statut de captifs, d’Anglais ou simplement, d’étrangers. Ce travail vise à reconstituer le parcours de vie et d’intégration des anciens captifs de Deerfield dans la colonie française. Nous identifierons pour commencer les participants de l’attaque de Deerfield. Passant ensuite aux captifs, nous étudierons le processus d’intégration à la colonie et d’assimilation par la religion. Nous aborderons les modalités de l’adoption des captifs par les Français et les Amérindiens. Nous verrons quelle a été l’influence du mariage quant à l’insertion des captifs dans les réseaux sociaux. Finalement, nous analyserons le statut socioprofessionnel et la reproduction sociale de la descendance immédiate de certains de ces captifs. / On February 29th, 1704, a force of 250 French and Amerindian allies attacked the small border village of Deerfield, Massachusetts and kidnapped 112 inhabitants, 89 of whom made it alive to New France. At the end of the War of the Spanish Succession, 25 of these captives stayed among the French or the Amerindians. For a long time, they had the status of captives, English or simply, foreigners. This work aims to reconstitute the course of life and integration of the former Deerfield captives in the French colony. We shall first identify the participants in the attack on Deerfield. Turning our attention to the captives, we shall study the process of their integration into the colony and their assimilation by religion. We shall examine the modalities of adoption of the captives by the colonists and the Amerindians. We shall also see what was the influence of marriage on the insertion of captives into Canadian social networks. Finally, we shall analyze the social and occupational status and the social reproduction of the immediate descendants of some of these captives.

Syftet med denna uppsats var att undersöka integrationsprocessen för de syriska immigranter, som har kommit till Sverige för minst två år sedan. Vi ville få reda på hur de hade upplevt första tiden i Sverige, hur de uppfattar att stödet från det svenska samhället har varit och vilka faktorer som har haft betydelse för deras välmående. I denna uppsats har vi använt oss av en kvalitativ metod. Data har samlats in genom intervjuer som har behandlat integrationsprocessen utifrån syriska emigranters perspektiv. Till våra intervjuer har vi använt oss av en intervjuguide och vi valde ut tre kvinnor och två män där deras ålder varierade från 20 till 45 årsåldern. De teoretiska utgångspunkterna utgick ifrån Bourdieus habitus, Olkiewiczs (2008) assimilatoriska och nostalgiska grupper samt Franzens (1997) konstruktiva och destruktiva mönster. Vårt resultat visade att första tiden i Sverige ansågs som en väldigt svår period för våra informanter. Detta berodde dels på att man var rädd att inte bli erbjuden ett svenskt uppehållstillstånd och dels att man i vissa fall upplevde osäkerhet på förläggningen. De berättade att ekonomin inte har varit ett större problem, men däremot var de missnöjda med att man inte tog hänsyn till deras psykiska ohälsa efter de hemska upplevelserna i deras hemland. Våra informanter menade även att det svenska språket, kulturen och arbetet är alla viktiga bakgrunder för att de ska kunna känna sig delaktiga i samhället. Genom vårt resultat kan vi dra slutsatser om att samhälleliga och politiska åtgärder måste tas när det gäller integrationsprocessen. Det första som borde göras är att förbättra emigranternas tillgång till psykiatrisk hjälp, med tanken på att deras psykiska ohälsa har haft största inverkan på deras integration. Detta menar informanterna när de berättar att de önskade stöd ifrån samhället för att kunna underlätta de förhållanden som de anser förbättrar deras välmående. En lyckad integration bör byggas på samspel mellan samhället och emigranten för att de ska kunna anpassa sig i samhället och detta är självklart en förutsättning för att befrämja emigranternas roller i samhället. / In recent times there has been a lot of debate on Syrian refugees who have immigrated to Sweden. The armed conflict in Syria is now in its fourth year. At least 120 000 people have died. The conflict has forced 9 million Syrians to flee and out of them 6.5 million are IDPs. The purpose of this study was to investigate the integration process of the Syrian immigrants, who have lived in Sweden for at least two years. We wanted to find out how they had experienced their first time in Sweden, how they perceive the support from the Swedish society and the factors that have had an impact on their wellbeing. In this essay we have used a qualitative method. Data was collected through interviews which dealt with the integration process based on Syrian immigrants´ perspective. To our interviews, we used an interview guide and we picked out three women and two men between the age 20 to 45 years. The theoretical basis was based on Bourdieu's habitus, Olkiewiczs (2008) assimilatory and nostalgic groups and Franzens (1997) constructive and destructive patterns. Our results showed that the first time in Sweden was considered as a very difficult period for our informants. This was partly because of the fear of not being offered a Swedish residence permit, in turn this caused feelings of uncertainty in the refugee camps. They told us that the economy has not been a major problem, however, they were unhappy with that lack of consideration about their mental illness after the terrible experiences in their past. Some important aspects of feeling part of the community participant in the community were language skills, knowledge of Swedish culture and access to employment. Through our results, we can draw the conclusions that social and political measures must be taken with regard to the integration process. The first thing you should do is to improve immigrants´ access to psychological treatment, since mental illness has had the biggest impact on their integration. At the same time we concluded that our informants need support from the community, in order to facilitate the conditions that they believe will improve their well-being. Successful integration should be built on the interaction between society and the immigrant, in order to be able to adapt to the society, and this is a fundamental condition for promoting the immigrants´ roles in society.

Thesis (M.A.)--Miami University, Dept. of Psychology, 2009. / Title from first page of PDF document. Includes bibliographical references (p. 44-50).

Les variations du champ magnétique terrestre sont documentées par les observatoires au sol et les satellites en orbite basse, pour des échelles de temps de l'année au siècle.Sur ces périodes, la dynamique du noyau externe -- là où est principalement généré le champ magnétique -- est fortement influencée par la rotation terrestre, qui tend à imposer une invariance dans la direction parallèle à l'axe de rotation.Dans cette thèse, j'étudie un modèle s'appuyant sur cette hypothèse de bidimensionnalité du champ de vitesse, le modèle quasi-géostrophique.Je présente une nouvelle dérivation de ce modèle par une approche variationnelle, plus adaptée aux fortes pentes des frontières du domaine sphérique.Je présente une étude modale des ondes hydro-magnétiques, qui pour la première fois prend en compte l'impact d'un champ magnétique imposé non-zonal.Deux groupes d'ondes magnéto-hydrodynamiques apparaissent alors : les ondes magnéto-Coriolis (centennales) et les ondes d'Alfvéen de torsion (interannuelle).Je décris l'évolution des ondes à mesure que l'on intensifie l'effet de la rotation, jusqu'à atteindre des paramètres géophysiques.Je discute également dans quel mesure une version du modèle quasi-géostrophique où la force de Lorentz est représentée par des produits quadratiques du champ magnétique est adapté pour l'interprétation de calculs numériques tridimensionnels de la dynamo. J'observe que pour les paramètres aujourd'hui accessibles à ces calculs, les forces magnétiques sont faibles. À long terme, nous espérons utiliser le modèle quasi-géostrophique dans le contexte de l'assimilation de données satellitaires. / Variations of the Earth's magnetic field are documented by ground observatories and low-orbiting satellites, for time scales from year to century.On such periods, dynamics of the outer core -- where the creation of the magnetic field takes place -- is strongly influenced by the Earth rotation, which tends to impose invariance of the flow in the direction parallel to the rotation axis.In this thesis report, I study a model based on this bi-dimensional velocity field hypothesis, the quasi-geostrophic model.I present a new mathematical formulation of this model through a variational approach, better suited to steep slopes on the boundaries of the spherical domain.I present a modal study of hydromagnetic waves, taking into account for the first time the impact of a non-zonal imposed magnetic field.Two groups of hydromagnetic waves are present : centennial magneto-Coriolis waves and interannual torsional Alfvén waves.I describe evolution of those waves as the effect of rotation is intensified until Earth-like parameters are reached.I also discuss in what measure an other version of the quasi-geostrophic model, where Lorentz force is represented by quadratic products of the magnetic field, can be adapted to understand tridimensional dynamo numerical simulations.I observe that for parameters available today, magnetic forces are weak.In the future, we hope to use the Quasi-geostrophic model in the context of satellite data assimilation.

L’humidité du sol à été déclarée Essential Climate Variable (ECV) en 2010 par l’European Space Agency (ESA) en support du travail du Groupe d'experts Intergouvernemental sur l'Évolution du Climat (GIEC). Dans des zones vulnérables comme l’Afrique de l’Ouest (agriculture faiblement irriguée et de subsistance, températures extrêmes et forte variabilité des précipitations), la valeur ajoutée d’informations concernant l’humidité du sol est importante, surtout dans un contexte de changement climatique. La première partie de ces travaux de thèse concerne la représentation de l'humidité en profondeur à grande échelle en utilisant le triptyque mesures in-situ/télédétection/modélisation. Ces 3 méthodes présentent chacune des limites: (i) la faible densité des réseaux in-situ (3 sites de mesures sur toute l'Afrique de l'Ouest), (ii) les estimations de SMOS uniquement en surface (0-5 cm) et (iii) les incertitudes des forçages de précipitation temps-réel utilisés dans les modèles de surface. Afin de réduire ces limitations, une méthode d'assimilation (filtre particulaire) des données SMOS à été implémentée dans un modèle de surface empirique (API) et comparées aux mesures in-situ AMMA-CATCH. Les résultats montrent une amélioration des humidités modélisée après assimilation. La seconde partie concerne l'impact des variations d'humidité du sol sur les rendements de mil. Une relation statistique a tout d'abord été déterminée à partir de données de rendements mesurés sur 10 villages autour de Niamey. Les résultats montrent que les anomalies d'humidité du sol sur 20 jours début Juillet et fin Août - mi Septembre (période reproductive et période de remplissage du grain), à une profondeur d'environ 30 cm, expliquent les variations de rendement mesuré à R2=0.77 sur l'ensemble de 9 villages. Cette relation à ensuite été appliquée à l'échelle du Niger à partir de données de rendement issues de la FAO et de cartes d'humidité en profondeur développées dans la première partie de la thèse. Les résultats montrent une corrélation à R2=0.62 sur les années 1998-2014. Puis la méthode a été appliquée à 3 autres pays du Sahel, montrant une corrélation de 0.77. La dernière partie de ces travaux concerne l'exploitation des résidus du schéma d'assimilation afin de réduire les incertitudes sur les précipitations. Les produits de précipitations satellites CMORPH, TRMM et PERSIANN, dans leur version temps-réel ont été comparées à des pluviomètres avant et après assimilation. Le résultat de cette étude montre une nette amélioration des intensités estimées. La méthode a ensuite été appliquée à un produit de précipitation utilisé au centre régional AGRHYMET pour le suivi agricole, le produit TAMSAT.Ces travaux de thèse ont permis d'approfondir les recherches concernant le potentiel des données d'humidité par satellite pour des applications agronomiques. Les perspectives de ces travaux portent principalement sur : (i) l'utilisation d'autres capteurs (SMAP, ASCAT, AMSR) pour augmenter la fréquence des observations d'humidité dans l'assimilation, (ii) sur des méthodes de désagrégation des coefficients pour la correction des précipitations à plus haute résolution spatiale et (iii) sur l'utilisation de données multispectrales (indices de végétation, température du sol, ...) pour un meilleur suivi des rendements. / Soil moisture was declared Essential Climate Variable (ECV) in 2010 by the European Space Agency (ESA) in support of the work of the Intergovernmental Panel on Climate Change (IPCC). In vulnerable areas such as West Africa (poorly irrigated and subsistence agriculture, extreme temperatures and high variability of rainfall), the added value of informations on soil moisture is important, especially in a changing climate. The first part of this thesis concerns the representation of root-zone soil moisture on a large scale using the triptych in-situ measurements / remote sensing / modeling. These 3 methods each have limitations: (i) the low density of in-situ networks (3 measurement sites throughout West Africa), (ii) SMOS estimates only at the surface (0-5 cm) and (iii) the uncertainties of the real-time precipitation forcing used in surface models. In order to reduce these limitations, an assimilation method (particle filter) of SMOS data has been implemented in an empirical surface model (API) and compared to AMMA-CATCH in-situ measurements. The results show an improvement of the humidities modeled after assimilation. The second part concerns the impact of soil moisture variations on millet yields. A statistical relationship was first determined from yield data measured in 10 villages around Niamey. The results show that the 20-day soil moisture anomalies at the beginning of July and the end of August - mid September (reproductive period and grain filling period), at a depth of about 30 cm, explain the variations in yield measured at R2=0.77. This relationship was then applied to the Nigerien scale from FAO yield data and in-depth moisture maps developed in the first part of the thesis. The results show a correlation at R2=0.62 over the years 1998-2015. Then, the method was apply to 3 other sahelian countries, showing a agreement of 0.77. The last part of this work concerns the exploitation of the residuals of the assimilation scheme in order to reduce the uncertainties on the precipitations. The satellite precipitation products CMORPH, TRMM and PERSIANN, in their real-time version, were compared to rain gauges before and after assimilation. The result of this study shows a marked improvement in the estimated precipitations intensities. The method was then applied to a precipitation product used at the AGRHYMET regional center for agricultural monitoring, the TAMSAT product.This thesis work has led to further research into the potential of satellite moisture data for agronomic applications. The perspectives of this work mainly concern: (i) the use of other sensors (SMAP, ASCAT, AMSR) to increase the frequency of the observations of humidity in the assimilation, (ii) on methods of disaggregation of the coefficients for the correction of precipitation at higher spatial resolution and (iii) the use of multispectral data (vegetation indices, soil temperature, ...) for a better monitoring of yields.

Cette thèse présente des travaux en lien avec l’utilisation de données cliniques dans la construction de modèles appliqués à l’oncologie. Les modèles actuels visant à intégrer plusieurs mécanismes biologiques liés à la croissance tumorale comportent trop de paramètres et ne sont pas calibrables sur des cas cliniques. A l’inverse, les modèles plus simples ne parviennent pas à prédire précisément l’évolution tumorale pour chaque patient. La multitude et la variété des données acquises par les médecins sont de nouvelles sources d’information qui peuvent permettre de rendre les estimations des modèles plus précises. A travers deux projets différents, nous avons intégré des données dans le processus de modélisation afin d’en tirer le maximum d’information. Dans la première partie, des données d’imagerie et de génétique de patients atteints de gliomes sont combinées à l’aide de méthodes d’apprentissage automatique. L’objectif est de différencier les patients qui rechutent rapidement au traitement de ceux qui ont une rechute plus lente. Les résultats montrent que la stratification obtenue est plus efficace que celles utilisées actuellement par les cliniciens. Cela permettrait donc d’adapter le traitement de manière plus spécifique pour chaque patient. Dans la seconde partie, l’utilisation des données est cette fois destinée à corriger un modèle simple de croissance tumorale. Même si ce modèle est efficace pour prédire le volume d’une tumeur, sa simplicité ne permet pas de rendre compte de l’évolution de forme. Or pouvoir anticiper la future forme d’une tumeur peut permettre au clinicien de mieux planifier une éventuelle chirurgie. Les techniques d’assimilation de données permettent d’adapter le modèle et de reconstruire l’environnement de la tumeur qui engendre ces changements de forme. La prédiction sur des cas de métastases cérébrales est alors plus précise. / This thesis deals with the use of clinical data in the construction of models applied to oncology. Existing models which take into account many biological mechanisms of tumor growth have too many parameters and cannot be calibrated on clinical cases. On the contrary, too simple models are not able to precisely predict tumor evolution for each patient. The diversity of data acquired by clinicians is a source of information that can make model estimations more precise. Through two different projets, we integrated data in the modeling process in order to extract more information from it. In the first part, clinical imaging and biopsy data are combined with machine learning methods. Our aim is to distinguish fast recurrent patients from slow ones. Results show that the obtained stratification is more efficient than the stratification used by cliniciens. It could help physicians to adapt treatment in a patient-specific way. In the second part, data is used to correct a simple tumor growth model. Even though this model is efficient to predict the volume of a tumor, its simplicity prevents it from accounting for shape evolution. Yet, an estimation of the tumor shape enables clinician to better plan surgery. Data assimilation methods aim at adapting the model and rebuilding the tumor environment which is responsible for these shape changes. The prediction of the growth of brain metastases is then more accurate.