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

The Standard Model of particle physics is believed to be only the low energy limit of a more fundamental theory. In order to determine its range of validity, a major part of theoretical and experimental efforts in physics is dedicated to precision tests of the Standard Model. Lattice QCD is a non-perturbative, first-principles approach to Quantum Field Theory. It plays an important role in flavor physics by providing calculations of non-perturbative strong interaction contributions to weak processes involving quarks. Measurements of hadronic quantities can be used to constrain the Standard Model as well as theories Beyond the Standard Model. The first part of this thesis contains theoretical developments regarding non-perturbative renormalization. A new renormalization scheme, RI/mSMOM, for fermion bilinear operators in QCD at non-vanishing quark mass is presented. In order to investigate the properties of the mSMOM scheme, an explicit one-loop computation in perturbation theory using dimensional regularization is performed. Numerically, vertex functions are generated on the lattice, with an appropriate projector, based on the RI/SMOM scheme and the renormalization factors are extracted. Quantities measured include renormalization of the axial current ZA, required to renormalize the axial current entering the computation of the decay constant and the renormalization of the bag parameter. The second part of this report focuses on flavor physics phenomenology on the lattice. It presents results of the first run of the RBC/UKQCD charm project with (2+1)-flavor Domain Wall fermions. Observables and matrix elements are measured on lattices with Iwasaki gauge action. There are two ensembles at the physical point with inverse lattice spacings 1.73 and 2.36 GeV and a third finer ensemble at 2.76 GeV as well as four other auxiliary ensembles with smaller volumes and heavier pion masses which are used to perform the continuum extrapolations. The quantities measured in the region of the charm quark mass are meson masses, decay constants, the matrix element of the OV V +AA operator, the neutral D-meson mixing parameter B and the SU(3) breaking ratio ξ.

La problématique générale de notre travail s'inscrit dans le domaine scientifique de la recherche d'information (RI). Les modèles de RI classiques sont généralement basés sur une définition de la notion de pertinence qui est liée essentiellement à l'adéquation thématique entre le sujet de la requête et le sujet du document. Le concept de pertinence a été revisité selon différents niveaux intégrant ainsi différents facteurs liés à l'utilisateur et à son environnement dans une situation de RI. Dans ce travail, nous abordons spécifiquement le problème lié à la modélisation de la pertinence multidimensionnelle à travers la définition de nouveaux modèles d'agrégation des critères et leur évaluation dans des tâches de recherche de RI. Pour répondre à cette problématique, les travaux de l'état de l'art se basent principalement sur des combinaisons linéaires simples. Cependant, ces méthodes se reposent sur l'hypothèse non réaliste d'additivité ou d'indépendance des dimensions, ce qui rend le modèle non approprié dans plusieurs situations de recherche réelles dans lesquelles les critères étant corrélés ou présentant des interactions entre eux. D'autres techniques issues du domaine de l'apprentissage automatique ont été aussi proposées, permettant ainsi d'apprendre un modèle par l'exemple et de le généraliser dans l'ordonnancement et l'agrégation des critères. Toutefois, ces méthodes ont tendance à offrir un aperçu limité sur la façon de considérer l'importance et l'interaction entre les critères. En plus de la sensibilité des paramètres utilisés dans ces algorithmes, est très difficile de comprendre pourquoi un critère est préféré par rapport à un autre. Pour répondre à cette première direction de recherche, nous avons proposé un modèle de combinaison de pertinence multicritères basé sur un opérateur d'agrégation qui permet de surmonter le problème d'additivité des fonctions de combinaison classiques. Notre modèle se base sur une mesure qui permet de donner une idée plus claire sur les corrélations et interactions entre les critères. Nous avons ainsi adapté ce modèle pour deux scénarios de combinaison de pertinence multicritères : (i) un cadre de recherche d'information multicritères dans un contexte de recherche de tweets et (ii) deux cadres de recherche d'information personnalisée. Le deuxième axe de recherche s'intéresse à l'intégration du facteur temporel dans le processus d'agrégation afin de tenir compte des changements occurrents sur les collection de documents au cours du temps. Pour ce faire, nous avons proposé donc un modèle d'agrégation sensible au temps pour combinant le facteur temporel avec le facteur de pertinence thématique. Dans cet objectif, nous avons effectué une analyse temporelle pour éliciter l'aspect temporel des requêtes, et nous avons proposé une évaluation de ce modèle dans une tâche de recherche sensible au temps. / The main research topic of this document revolve around the information retrieval (IR) field. Traditional IR models rank documents by computing single scores separately with respect to one single objective criterion. Recently, an increasing number of IR studies has triggered a resurgence of interest in redefining the algorithmic estimation of relevance, which implies a shift from topical to multidimensional relevance assessment. In our work, we specifically address the multidimensional relevance assessment and evaluation problems. To tackle this challenge, state-of-the-art approaches are often based on linear combination mechanisms. However, these methods rely on the unrealistic additivity hypothesis and independence of the relevance dimensions, which makes it unsuitable in many real situations where criteria are correlated. Other techniques from the machine learning area have also been proposed. The latter learn a model from example inputs and generalize it to combine the different criteria. Nonetheless, these methods tend to offer only limited insight on how to consider the importance and the interaction between the criteria. In addition to the parameters sensitivity used within these algorithms, it is quite difficult to understand why a criteria is more preferred over another one. To address this problem, we proposed a model based on a multi-criteria aggregation operator that is able to overcome the problem of additivity. Our model is based on a fuzzy measure that offer semantic interpretations of the correlations and interactions between the criteria. We have adapted this model to the multidimensional relevance estimation in two scenarii: (i) a tweet search task and (ii) two personalized IR settings. The second line of research focuses on the integration of the temporal factor in the aggregation process, in order to consider the changes of document collections over time. To do so, we have proposed a time-aware IR model for combining the temporal relavance criterion with the topical relevance one. Then, we performed a time series analysis to identify the temporal query nature, and we proposed an evaluation framework within a time-aware IR setting.

Made available in DSpace on 2014-12-17T14:27:06Z (GMT). No. of bitstreams: 1 AndreMLA.pdf: 943466 bytes, checksum: 1ea37e7af8ee803c9223422cfd499f9f (MD5) Previous issue date: 2007-05-11 / The present work has for object the Jury under the democratic optics, looking for to demonstrate its democratic validation. The purpose of this work was to revisit the institution, in order to bring its importance while instrument of popular participation. The work presents, first, a systematic and chronological approach of the institution of the Jury and its evolution inside of Brazilian constitutional history, objectifying, with this, to approach the narrow entailing of the Jury with the constitutional postulates. After that, the constitutional principles of the Jury had been examined, looking for to establish the popular identity of the institution and its approach with the human rights system of the Brazilian Federal Constitution. More ahead, had been examined the direct participation of the society in the Jury, going deep the questions related with the election of the jurors and the jury nullification on the American Jury. Finally, had been dedicated the study of the current conjuncture of the Brazilian Jury, its problems and the possible solutions, beyond the study of the limitation's mechanisms in the constitutional principle of the popular supremacy and the reform's projects suggested for legislators and jurists. In this way, had been looked elaborate a constitutional construction of the Jury, defending its permanence in the Brasil law system, for being a fundamental guarantee to protect the freedom, moreover for being essential to validate the Democratic State of Right, for to be the materialization of the democratic principle. For opportune, it's necessary to allege that this work had been directed to the constitutional analysis of the Jury, its legitimacy and its democratic vocation, using themselves as ideological north the American Jury System and as philosophical base the social contract theory, understanding the Jury as an instrument of protection of the society front to the state supremacy and its hierarchy structure of the power / O presente trabalho tem por objeto a an?lise do J?ri sob a ?tica democr?tica, procurando demonstrar a sua necessidade ? pr?pria valida??o do Estado Democr?tico de direito. A finalidade deste trabalho foi revisitar a institui??o, a fim de trazer ? tona a sua import?ncia enquanto instrumento de participa??o popular. O trabalho apresenta, primeiramente, uma abordagem sistem?tica e cronol?gica do J?ri e sua evolu??o dentro da hist?ria constitucional brasileira, objetivando, com isso, abordar a sua estreita vincula??o com os postulados constitucionais. Em seguida, foram examinados os princ?pios constitucionais do J?ri, estabelecendo-se a sua identidade com o sistema de prote??o dos direitos fundamentais da atual constitui??o. Mais adiante, foi analisada a participa??o direta da sociedade no J?ri, aprofundando as quest?es relacionadas com a sele??o dos jurados e poder de veto do J?ri no sistema americano. Por fim, foi dedicado o estudo da atual conjuntura do J?ri brasileiro, seus problemas e as poss?veis solu??es, abordando os principais mecanismos de limita??o da soberania dos veredictos, as cr?ticas e propostas de reforma do J?ri sugerida por legisladores e juristas. Desse modo, procurou-se elaborar uma constru??o constitucional do J?ri, defendendo a sua perman?ncia no sistema jur?dico brasileiro, por tratar-se de garantia fundamental ao direito de liberdade, e ainda pela sua essencialidade ? pr?pria validade do Estado Democr?tico de Direito, por representar a materializa??o do princ?pio democr?tico. Por oportuno, mister se faz aduzir que a presente se dirige ? an?lise constitucional do J?ri, sua legitimidade e sua voca??o democr?tica, utilizando-se como norte ideol?gico o modelo americano de J?ri e como base filos?fica a teoria do contrato social, compreendendo o J?ri como instrumento de prote??o da sociedade frente ? supremacia estatal e sua estrutura hierarquizante de poder

Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-02-03T18:45:40Z No. of bitstreams: 1 Dissertação - Vanessa da Costa Sena.pdf: 1290238 bytes, checksum: d6931cc5400a39ef7ad8f9ad3fd25d83 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-02-04T13:02:27Z (GMT) No. of bitstreams: 1 Dissertação - Vanessa da Costa Sena.pdf: 1290238 bytes, checksum: d6931cc5400a39ef7ad8f9ad3fd25d83 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-02-04T13:02:38Z (GMT) No. of bitstreams: 1 Dissertação - Vanessa da Costa Sena.pdf: 1290238 bytes, checksum: d6931cc5400a39ef7ad8f9ad3fd25d83 (MD5) / Made available in DSpace on 2016-02-04T13:02:38Z (GMT). No. of bitstreams: 1 Dissertação - Vanessa da Costa Sena.pdf: 1290238 bytes, checksum: d6931cc5400a39ef7ad8f9ad3fd25d83 (MD5) Previous issue date: 2014-12-19 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / Éste trabajo analiza el establecimiento de la comunicación de los ecosistemas bases de datos del grupo de investigación y recuperación de la información del Instituto de Computación de la Universidad Federal de Amazonas, a partir de una red de colaboración científica como objeto de estudio . A través de un enfoque cuantitativo , se identificarón los que participan en la colaboración , la frecuencia de esta relación y los principales medios de comunicación empleados por los miembros de la red a la que se inserta la BD y RI . Se utilizó como fuente de recopilación de datos Plataforma Lattes, donde fue posible detectar las producciones publicadas en revistas y eventos científicos durante el período de tres años 2.010-21.012 y Capes colección consistió en el año 2013, durante el cual el PPGI / UFAM recibido Concepto 5 CAPES . El análisis de los datos permitió verificar que la red del Grupo consiste és um tipo de colaboración sin parar , y las relaciones no aleatorios influyen en la expansión de los contactos y la comunicación de los descubrimientos científicos. Es de destacar que , en este trabajo , debido a algunas limitaciones, no era posible ir más allá de la composición de la red de colaboración científica , porque para entender la constitución de un ecosistema comunicativo sería necesario identificar las interconexiones existentes entre factores físicos , ecológicos y bióticos / Este trabalho analisa a constituição do ecossistema comunicacional do grupo de pesquisa Banco de Dados e Recuperação da Informação do Instituto de Computação da Universidade Federal do Amazonas, a partir de sua rede de colaboração científica como objeto de estudo. Por meio de uma abordagem quantitativa, identificou-se os atores envolvidos na colaboração, a frequência desse relacionamento e os principais meios de comunicação empregados pelos membros da rede a qual o BD&RI está inserido. Utilizou-se como fonte de coleta de dados a Plataforma Lattes, onde foi possível detectar as produções publicadas em periódicos e eventos científicos durante o triênio 2010 – 21012 e que constaram no Coleta Capes do ano de 2013, período em que o PPGI/UFAM recebeu conceito 5 da CAPES. A análise dos dados possibilitou constatar que a rede de colaboração científica é um modelo sem escalas, sendo que as relações não aleatórias influenciam a ampliação dos contatos e a comunicação das descobertas científicas. Destaca-se que, neste trabalho, devido a algumas limitações, não foi possível ir além da composição da rede de colaboração científica, pois para compreender a constituição de um ecossistema comunicacional seria necessário identificar as interconexões existentes entre os fatores físico, ecológico e biótico.

Composite flow simulation tools for LCM processing can be expensive and time-consuming but necessary to design a mold system with proper placement of resin inlets and vacuum outlets. Composites manufacturing engineers would benefit from data regarding the impact of mold curvature radius on resin flow. This could help determine whether or not a particular part and mold would require expensive simulation software designed to handle complex flow paths through curved fabric architectures exhibiting variable permeability over the curvature, or if simple flow modeling would provide accurate enough simulations for sound tooling setup decision making. Four molds, with double curvature having equal radii, were fabricated with radii ranging from 3.2 to 25.4 mm to characterize the permeability of two different fiber reinforcements 1) a carbon biaxial NCF and 2) a fiberglass CSM over the mold curvatures. Three infusions of each material type were conducted on each of the 4 molds for a total of 24 test infusions. Flow front position vs. time data was captured during each experimental infusion. The permeability in the bend regions, KB, was first estimated by the integrated form of Darcy's Law to evaluate the permeability for average flow across the entire bend region. This was done for both the convex and concave regions using a geometric estimate for the increased compaction in the bend regions. The permeability increases as the tool radius increases, and the rate of increase diminishes as the tool radius increases and the permeability approaches the flat region permeability. An estimate of KB for VI was then made by applying a ratio calculated from the resulting permeability from the rigid- and VI-based models in the flat regions. Generic power law fits are reported that could be used in LCM process simulation, to give a model to estimate the permeability for any bend in the reinforcement part geometry. The results suggest that any curve with a radius higher than 25 mm requires no adjustment to the flat permeability.

The self-assembly of isotropic and anisotropic colloidal particles into higher-ordered structures has been of great interest recently due to the promise of creating metamaterials with novel macroscopic properties. The physicochemical properties of these metamaterials can be tailored to achieve composites with tunable functionalities. The formation of these metamaterials can be used as a pathway to emulating advanced biological systems. In particular, synthetically mimicking the surface of a moth’s eye, which consists of arrays of ellipsoidal protuberances, can be used as a strategy for fabricating antireflective coatings. To enable this technology, it is necessary to design a synthesis scheme that produces micron-sized composite particles with tunable refractive index. In the future, the resulting composite microparticles can then undergo geometric and spatial modifications to form self-assemblies that have unique macroscopic material properties. This research work delineates a strategy of developing microparticles with a hybrid configuration that constitutes an inorganic and an organic part. The inorganic part comprises ~30 nm diameter titania (TiO2) nanoparticles, which are embedded within an organic polymer particle comprised of diethyl methylene malonate polymer [p(DEMM)]. Anionic polymerization is modified to controllably incorporate TiO2 nanoparticles into the polymer matrix. A design of experiments was identified and carried out to identify the major process variables that influence the final particle size. In particular, since DEMM polymerization may be initiated entirely by the presence of hydroxyl anions, pH was found to control the final overall particle diameter between 300 nm and 1 micrometer. The overall inorganic particle loading can be readily modified and is confirmed by thermogravimetric analysis, allowing for the desired macroscopic refractive index to be controlled. Light scattering, scanning electron microscopy and zeta potential analysis reveals that the colloidal stability of the hybrid microparticles is dependent on the ligand coating the inorganic constituent. In addition, this synthetic scheme is applied to different inorganic constituents that have interesting functionalities, such as fluorescent CdTe quantum dots, in order to show the methods versatility method to produce composite particles for a wide spectrum of applications. These initial investigations provide a the synthetic groundwork to evaluating the coating properties of the microparticles and their self-assembly into novel materials in the future.

No description available.

O glioblastoma (GBM) é um tumor extremamente agressivo e resistente aos tratamentos convencionais. Os agentes utilizados na quimio- e radioterapia são indutores de danos no DNA, por induzirem quebras de fita simples (SSBs) e quebras de fita dupla (DSBs), as quais são letais para as células, mas quando eficientemente reparadas pelas células tumorais tornam estas resistentes. As principais vias de reparo de DSBs são: a via por recombinação homológa (Homologous Recombination HR) e por recombinação não- homóloga (Non-homologous end joining NHEJ). As proteínas de reparo participantes dessas vias têm sido estudadas como potenciais alvos moleculares na terapia contra o câncer. A estratégia empregada no presente trabalho foi a de inibir a via de reparo HR em células já comprometidas para a via NHEJ. Para isso foi utilizado o inibidor de RAD51 (uma das principais proteínas da via HR), 3-chloro-1-(3,4-dichlorophenyl)-4- morpholinylo-1H-pyrrole-2,5-dione, conhecido como RI-1(Calbiochem), testado em células de glioma M059J e M059K (deficientes e proficientes para DNA-PK, respectivamente), irradiadas com raios-X. Diferentes ensaios foram realizados para o teste com o inibidor RI-1 em células irradiadas ou não e comparados ao controle sem tratamento. Os resultados dos ensaios de sobrevivência clonogênica mostraram que a concentração de 40 M do inibidor RI-1 exerceu um maior efeito inibitório sobre a capacidade de as células se dividirem e formarem colônias. O RI-1 induziu alterações significativas na cinética do ciclo celular predominantemente na linhagem selvagem M059K, nos tempos de 24 e 72 h. Apesar de a linhagem M059J não mostrar alterações significativas na cinética do ciclo celular, esta demonstrou sensibilidade à irradiação, conforme demonstrado pela cinética de reparo das DSBs, sendo mais lenta em relação à M059K, demonstrando o comprometimento do reparo NHEJ na linhagem mutante para DNA-PK. A expressão das proteínas LIG3, XRCC1 e PARP-1 foram analisadas no tempo de 15 minutos e 24 h após a irradiação. Na presença do inibidor RI-1, a expressão da LIG3 foi aumentada em células M059K (15 min e 24 h) comparadas ao grupo controle. Já a linhagem M059J apresentou uma elevada expressão das proteínas XRCC1 e PARP-1 apenas em 15 min em relação ao controle; esses dados indicaram que um possível reparo de DSBs envolvendo essas proteínas pode ter sido ativado logo nos primeiros minutos após a indução de danos nessas células. O conjunto dos resultados deste trabalho sugere um papel atuante do inibidor RI-1 em células comprometidas para o reparo NHEJ, isto é, a linhagem M059J, levando à sugestão de que vias alternativas de reparo podem possivelmente estar envolvidas na resistência das células tumorais aos tratamentos convencionais. / Glioblastoma (GBM) is an extremely aggressive and resistant tumor to conventional treatments. The agents used in chemotherapy and radiotherapy are inducers of DNA damage, since they induce single strand breaks (SSBs) and doublestrand breaks (DSBs), which are lethal to cells, but when efficiently repaired by tumor cells make them resistant to antitumoral agents. The main repair pathways for DSBs are the homologous recombination (HR) and non-homologous end joining (NHEJ) pathways. Proteins participating in these processes have been studied as potential molecular targets in cancer therapy. Thus, the strategy employed in this work involved the inhibition of HR repair pathway in cells already committed to the NHEJ pathway, aiming to sensitize irradiated GBM cells. An inhibitor of RAD51 (one of the major HR proteins) was used: 3-chloro-1-(3,4-dichlorophenyl) -4 morpholinylo-1Hpyrrole- 2,5-dione, known as RI-1 (Calbiochem); this compound was tested in GBM cells, M059K and M059J (proficient and deficient for the DNA-PK, respectively) irradiated with X-rays. Various assays were performed to test the inhibitory property of RI-1 in irradiated cells and the combination of the inhibitor with X-irradiation, compared with the untreated control. The results of clonogenic survival showed that 40 M of RI-1 inhibitor exerted a higher inhibitory effect on the ability of cells to divide and form colonies. The RI-1 induced changes in cell cycle kinetics predominantly in the wild-type M059K, at 24 and 72 h. Although M059J did not show significant changes in cell cycle kinetics, these cells showed sensitivity to X-irradiation, as shown by the kinetics of DSB repair (gamma-H2AX foci), which was slower compared to M059K, demonstrating the commitment of the NHEJ repair in M059J (mutant for DNA-PK). The expression of LIG3, PARP-1 and XRCC1 proteins were analyzed at 15 min. and 24 h after irradiation. In the presence of the inhibitor RI-1, LIG 3 expression was increased in M059K cells (15 min. and 24 h) compared to the control group. M059J cells showed a high expression of XRCC1 and PARP-1 only at 15 min., compared to the control. These data indicated that a possible repair of DSBs involving these proteins may have been activated in the first minutes after DNA damage induction. The overall results of this study suggest that RI-1 inhibitor was efficient to influence cellular responses in cells committed to the NHEJ repair, i.e. M059J cell line, leading to the hypothesis that alternative repair pathways may be possibly involved in the resistance of tumor cells.

O glioblastoma (GBM) é um tumor extremamente agressivo e resistente aos tratamentos convencionais. Os agentes utilizados na quimio- e radioterapia são indutores de danos no DNA, por induzirem quebras de fita simples (SSBs) e quebras de fita dupla (DSBs), as quais são letais para as células, mas quando eficientemente reparadas pelas células tumorais tornam estas resistentes. As principais vias de reparo de DSBs são: a via por recombinação homológa (Homologous Recombination HR) e por recombinação não- homóloga (Non-homologous end joining NHEJ). As proteínas de reparo participantes dessas vias têm sido estudadas como potenciais alvos moleculares na terapia contra o câncer. A estratégia empregada no presente trabalho foi a de inibir a via de reparo HR em células já comprometidas para a via NHEJ. Para isso foi utilizado o inibidor de RAD51 (uma das principais proteínas da via HR), 3-chloro-1-(3,4-dichlorophenyl)-4- morpholinylo-1H-pyrrole-2,5-dione, conhecido como RI-1(Calbiochem), testado em células de glioma M059J e M059K (deficientes e proficientes para DNA-PK, respectivamente), irradiadas com raios-X. Diferentes ensaios foram realizados para o teste com o inibidor RI-1 em células irradiadas ou não e comparados ao controle sem tratamento. Os resultados dos ensaios de sobrevivência clonogênica mostraram que a concentração de 40 M do inibidor RI-1 exerceu um maior efeito inibitório sobre a capacidade de as células se dividirem e formarem colônias. O RI-1 induziu alterações significativas na cinética do ciclo celular predominantemente na linhagem selvagem M059K, nos tempos de 24 e 72 h. Apesar de a linhagem M059J não mostrar alterações significativas na cinética do ciclo celular, esta demonstrou sensibilidade à irradiação, conforme demonstrado pela cinética de reparo das DSBs, sendo mais lenta em relação à M059K, demonstrando o comprometimento do reparo NHEJ na linhagem mutante para DNA-PK. A expressão das proteínas LIG3, XRCC1 e PARP-1 foram analisadas no tempo de 15 minutos e 24 h após a irradiação. Na presença do inibidor RI-1, a expressão da LIG3 foi aumentada em células M059K (15 min e 24 h) comparadas ao grupo controle. Já a linhagem M059J apresentou uma elevada expressão das proteínas XRCC1 e PARP-1 apenas em 15 min em relação ao controle; esses dados indicaram que um possível reparo de DSBs envolvendo essas proteínas pode ter sido ativado logo nos primeiros minutos após a indução de danos nessas células. O conjunto dos resultados deste trabalho sugere um papel atuante do inibidor RI-1 em células comprometidas para o reparo NHEJ, isto é, a linhagem M059J, levando à sugestão de que vias alternativas de reparo podem possivelmente estar envolvidas na resistência das células tumorais aos tratamentos convencionais. / Glioblastoma (GBM) is an extremely aggressive and resistant tumor to conventional treatments. The agents used in chemotherapy and radiotherapy are inducers of DNA damage, since they induce single strand breaks (SSBs) and doublestrand breaks (DSBs), which are lethal to cells, but when efficiently repaired by tumor cells make them resistant to antitumoral agents. The main repair pathways for DSBs are the homologous recombination (HR) and non-homologous end joining (NHEJ) pathways. Proteins participating in these processes have been studied as potential molecular targets in cancer therapy. Thus, the strategy employed in this work involved the inhibition of HR repair pathway in cells already committed to the NHEJ pathway, aiming to sensitize irradiated GBM cells. An inhibitor of RAD51 (one of the major HR proteins) was used: 3-chloro-1-(3,4-dichlorophenyl) -4 morpholinylo-1Hpyrrole- 2,5-dione, known as RI-1 (Calbiochem); this compound was tested in GBM cells, M059K and M059J (proficient and deficient for the DNA-PK, respectively) irradiated with X-rays. Various assays were performed to test the inhibitory property of RI-1 in irradiated cells and the combination of the inhibitor with X-irradiation, compared with the untreated control. The results of clonogenic survival showed that 40 M of RI-1 inhibitor exerted a higher inhibitory effect on the ability of cells to divide and form colonies. The RI-1 induced changes in cell cycle kinetics predominantly in the wild-type M059K, at 24 and 72 h. Although M059J did not show significant changes in cell cycle kinetics, these cells showed sensitivity to X-irradiation, as shown by the kinetics of DSB repair (gamma-H2AX foci), which was slower compared to M059K, demonstrating the commitment of the NHEJ repair in M059J (mutant for DNA-PK). The expression of LIG3, PARP-1 and XRCC1 proteins were analyzed at 15 min. and 24 h after irradiation. In the presence of the inhibitor RI-1, LIG 3 expression was increased in M059K cells (15 min. and 24 h) compared to the control group. M059J cells showed a high expression of XRCC1 and PARP-1 only at 15 min., compared to the control. These data indicated that a possible repair of DSBs involving these proteins may have been activated in the first minutes after DNA damage induction. The overall results of this study suggest that RI-1 inhibitor was efficient to influence cellular responses in cells committed to the NHEJ repair, i.e. M059J cell line, leading to the hypothesis that alternative repair pathways may be possibly involved in the resistance of tumor cells.