Fractal descriptors based on the probability dimension: a texture analysis and classification approach

In this work, we propose a novel technique for obtaining descriptors of gray-level texture images. The descriptors are provided by applying a multiscale transform to the fractal dimension of the image estimated through the probability (Voss) method. The effectiveness of the descriptors is verified in a classification task using benchmark over texture datasets. The results obtained demonstrate the efficiency of the proposed method as a tool for the description and discrimination of texture images.Comment: 7 pages, 6 figures. arXiv admin note: text overlap with arXiv:1205.282

Texture analysis by multi-resolution fractal descriptors

This work proposes a texture descriptor based on fractal theory. The method is based on the Bouligand-Minkowski descriptors. We decompose the original image recursively into 4 equal parts. In each recursion step, we estimate the average and the deviation of the Bouligand-Minkowski descriptors computed over each part. Thus, we extract entropy features from both average and deviation. The proposed descriptors are provided by the concatenation of such measures. The method is tested in a classification experiment under well known datasets, that is, Brodatz and Vistex. The results demonstrate that the proposed technique achieves better results than classical and state-of-the-art texture descriptors, such as Gabor-wavelets and co-occurrence matrix.Comment: 8 pages, 6 figure

Development of alternative micro and nanoparticulate polymeric systems for mucosal delivery of Streptococcus equi antigens

Tese de doutoramento em Farmácia (Tecnologia Farmacêutica), apresentada à Universidade de Lisboa através da Faculdade de Farmácia, 2008S. equi is considered the causative agent of strangles, a very contagious disease of the upper respiratory tract of the Equidae. Although S. equi is sensitive to some antibiotics, most of the current treatments are ineffective. During the recovery period, horses develop a protective immune response mostly against the antiphagocytic cell wall-associated M-like protein SeM, which encourages the development of efficient vaccines. The main purpose of this thesis was to develop and characterise stable polymeric particles and study their potential as mucosal S. equi antigens adjuvant. Non-aggregated and easily dispersible micro and nanospheres based on poly-e-caprolactone (PCL) and poly(lactic acid) (PLA) polymers were formulated by the double emulsion (w/o/w) solvent evaporation method and fully characterised. BALB/c monocyte macrophages (cell line J774.1A) were used in toxicity tests and cellular uptake studies. The influence of mucoadhesive polymers (chitosan (CS), glycolchitosan (GCS) and alginate (ALG)) and absorption enhancers (spermine (SP) and oleic acid (OA)) in particle physicochemical characteristics and consequently in the humoral, mucosal and cellular immune responses was as well evaluated. The non-toxic cholera toxin B subunit (CTB) is a potent mucosal adjuvant, and the oligodeoxynuleotide with repeating C and G motives (CpG) can also be used to up-regulate mucosal and cellular immune responses, increasing preferentially the T helper type 1 (Th1) cell activity. Therefore, those adjuvants were co-administrated with soluble antigen and non-modified PLA and PCL particles, in order to assess their eventual synergic effect. Inspite of administration route (i.n. and i.m.), S. equi-loaded polymeric systems were able to significantly increase systemic and cellular immune responses, when compared with free antigens, isolated or co-admixed with CTB or CpG. PLA-loaded particles generally induced higher mucosal antibody levels when compared with the correspondent PCL. Similar results were attained when the immune responses induced by S. equi antigens-adsorbed particles were compared with those elicited by the correspondent entrapped ones. As per PCL nanospheres, those formulated with ALG and GCS, seem to induce a more balance Th1/Th2 immune response. This study also confirmed the potential adjuvant of S. equi antigen-loaded PLA nanospheres, and again the mucopolysaccharide GCS induced the most prominent immune response. SeM recombinant proteins were entrapped in PLA nanospheres and their adjuvant potential after i.m. administration in a mouse model was compared with that achieved with S. equi extract. In fact, it was possible to observe that PLA-GCS and PLA-OA nanospheres are alternative cost-effective preparations, able to induce a balanced IgG2a/IgG1 immune response. These studies bring new insights into the strangles prevention field as the particulate carriers developed during this PhD thesis, mainly those containing GCS, are promising adjuvants for a safe vaccine against strangles, with no toxicity issues associated to their utilisation, in contrast to other adjuvants that have been associated to S. equi antigens. Therefore, the main goal of this thesis was accomplished but challenge studies must be done in order to support their future utilisation.Fundação para a Ciência e Tecnologia (FCT) e FEDER (SFRH/BD/14370/2003, POCI/BIO/59147/2004 e PPCDT/BIO/59147/2004

A sustainable path towards water purification an insight based on hydrophobic Deep Eutectic Solvents

"One of the main concerns of modern society is to provide clean water for everyone. The occurrence of a wide diversity of micropollutants in aquatic ecosystems leads to serious public health and environmental problems. Thus, the development of sustainable and cost-effective alternatives for water purification technologies is nowadays an important challenge. Deep eutectic solvents (DESs) have been proposed as new alternatives to conventional solvents and even ionic liquids. The choice of low cost, naturally occurring compounds and the straightforward preparation are among the key features of these solvents.(...)

Core-mantle boundary deformations and J2 variations resulting from the 2004 Sumatra earthquake

The deformation at the core-mantle boundary produced by the 2004 Sumatra earthquake is investigated by means of a semi-analytic theoretical model of global coseismic and postseismic deformation, predicting a millimetric coseismic perturbation over a large portion of the core-mantle boundary. Spectral features of such deformations are analysed and discussed. The time-dependent postseismic evolution of the elliptical part of the gravity field (J2) is also computed for different asthenosphere viscosity models. Our results show that, for asthenospheric viscosities smaller than 10^18 Pa s, the postseismic J2 variation in the next years is expected to leave a detectable signal in geodetic observations.Comment: 14 pages, 8 figures, 1 table. It will appear in Geophysical Journal Internationa

The role of the thymus in growth and development

Thesis (M.A.)--Boston University This item was digitized by the Internet Archive