Binary and nonbinary description of hypointensity for search and retrieval of brain MR images

Diagnosis accuracy in the medical field, is mainly affected by either lack of sufficient understanding of some diseases or the inter/intra-observer variability of the diagnoses. We believe that mining of large medical databases can help improve the current status of disease understanding and decision making. In a previous study based on binary description of hypointensity in the brain, it was shown that brain iron accumulation shape provides additional information to the shape-insensitive features, such as the total brain iron load, that are commonly used in clinics. This paper proposes a novel, nonbinary description of hypointensity in the brain based on principal component analysis. We compare the complementary and redundant information provided by the two descriptions using Kendall's rank correlation coefficient in order to better understand the individual descriptions of iron accumulation in the brain and obtain a more robust and accurate search and retrieval system

Nonlinear sigma model in 1+1 dimensions coupled to supergravity

O modelo não linear supersimétrico em l+l dimensões é acoplado à supergravidade. Ao quantizarmos a teoria, os campos de matéria adquirem massa dinamicamente, o que ocasiona a quebra da invariança de Weyl. Este fato implica em que as funções de dois pontos do Gravitino e do Graviton, obtidas a partir da ação efetiva, não sejam triviais. Em particular a função de dois pontos do Gravitino apresenta um polo no infravermelho. Nós conjeturamos que este polo está ligado com o confinamento dos graus de liberdade supersimétricos da teoria. Isto porque, ao restringirmos o domínio de integração de x IND. 1 à uma medida finita L (quebrando as invarianças da teoria), aparece na função de dois pontos do Gravitino um termo de massa, que decresce exponencialmente em função de L. Neste contexto relacionamos este model o como da corda supersimetrica e definimos um critério de estabilidade para a mesma.The nonlinear o supersymmetric model in l+l dimensions is coupled to supergravity. When we quantize the theory, the matter fields acquire mass dynamically, which leads to the breaking of the Weyl invariance. This fact implies that the two point functions of the Gravitino and the Graviton, obtained from the effective action, become non trivial. Particularly, the two point function of the Gravitino presents a pole in the infrared region. We conjecture that this pole is related to the confinement of all supersymmetric degrees of freedom of the theory. If we restraind the integration domain of x1 to a finite lengh L (breaking all invariances of the theory), there appears a mass term in two point function of the Gravitino, which decreases exponentially with L. In this context we relate this model with that of the supersymmetric string and define a stability criteria for the latter

Nonlinear sigma model in 1+1 dimensions coupled to supergravity

O modelo não linear supersimétrico em l+l dimensões é acoplado à supergravidade. Ao quantizarmos a teoria, os campos de matéria adquirem massa dinamicamente, o que ocasiona a quebra da invariança de Weyl. Este fato implica em que as funções de dois pontos do Gravitino e do Graviton, obtidas a partir da ação efetiva, não sejam triviais. Em particular a função de dois pontos do Gravitino apresenta um polo no infravermelho. Nós conjeturamos que este polo está ligado com o confinamento dos graus de liberdade supersimétricos da teoria. Isto porque, ao restringirmos o domínio de integração de x IND. 1 à uma medida finita L (quebrando as invarianças da teoria), aparece na função de dois pontos do Gravitino um termo de massa, que decresce exponencialmente em função de L. Neste contexto relacionamos este model o como da corda supersimetrica e definimos um critério de estabilidade para a mesma.The nonlinear o supersymmetric model in l+l dimensions is coupled to supergravity. When we quantize the theory, the matter fields acquire mass dynamically, which leads to the breaking of the Weyl invariance. This fact implies that the two point functions of the Gravitino and the Graviton, obtained from the effective action, become non trivial. Particularly, the two point function of the Gravitino presents a pole in the infrared region. We conjecture that this pole is related to the confinement of all supersymmetric degrees of freedom of the theory. If we restraind the integration domain of x1 to a finite lengh L (breaking all invariances of the theory), there appears a mass term in two point function of the Gravitino, which decreases exponentially with L. In this context we relate this model with that of the supersymmetric string and define a stability criteria for the latter

Space-time filtering, sampling and motion uncertainty

Robotics Institut

A method for detecting interstructural atrophy correlation in MRI brain images

Distinguishing neurodegenerative diseased patients (e.g., suffering from Alzheimer¿s Disease (AD)) from healthy individuals with the aid of MRI images is one of the challenges that need to be addressed in the field of Computational Anatomy (CA). A crucial feature in the analysis is the rate of atrophy of brain structures like the hippocampus or the ventricles. Until recently, analysis of atrophy rate has been restricted mainly to „localized atrophy¿, i.e. atrophy within one brain structure. Distinguishing correlations of atrophy rates between different brain structures could possibly provide additional information about the disease process. Therefore, in this paper, we propose a method to measure and analyze correlations of atrophy rate between hippocampus and ventricles with the aid of some correlation parameters. We combine the parameters that we thus obtain with some local atrophy rate parameters into a multidimensional vector, and use various vector classification methods to analyze the atrophy process with the aid of MRI brain volumes from the ADNI database. We obtain a good agreement between our classification results and the ground truth data. The analysis is facilitated with the aid of a specially designed graphical user interface

Dialogue support for memory impaired people

People affected by the loss of short term memory and cognitive impairment have serious difficulties in communication. This may lead to social isolation and lack of community access, a fundamental key barrier to independence for people suffering from Alzheimer's Disease, the most common form of memory and cognitive impairment. We propose Automated Memory Support for Social Interaction (AMSSI), a system that helps memory impaired people with their social interaction. The system provides active support that may help reducing stress level of patients. AMSSI recognizes visitors, determines the purpose of the visit, monitors the dialogue, determines whether the patient needs support, and provides feedback. AMSSI is tailored to patient needs, it has fast computation, full automation, and can be handled by the patient without supervision. The proposed assistive system can be beneficial for improving the quality of life of patients with mild to moderate cognitive impairments. This paper describes the implementation of the first working prototype of the AMSSI system. Validation user tests are still to be conducted