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Rodrigues Ribeiro R.S.,INESC Porto | Jorge P.A.S.,FCUP | Guerreiro A.,INESC Porto
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The intensity profile of a focused beam of light can exert small drift forces on particles with a few microns and even smaller, which can be used to confine or manipulate them. Optical trapping has several applications, in particular it has been adopted as a powerful tool in biology, allowing, for instance to manipulate in vivo single cells. A wide variety of optical setups have been implemented to optically trap microscopic bodies, however, the single beam trap using a tightly focused Gaussian beam continues to be the most used. Recent developments introduced an alternative to bulk optical trapping systems based on lensed optical fibers. This work presents simulations showing new designs of fiber optic and 2D waveguide tweezers based on studies of the forces acting on dielectric particles immersed in media with a distinct refractive index, which take into account the refractive index and structure of the particles. © 2013 SPIE. Source

Schroder B.,University of Aveiro | Coutinho J.A.P.,University of Aveiro | Santos L.M.N.B.F.,FCUP
Polycyclic Aromatic Compounds | Year: 2013

COSMO-RS, the Conductor-like Screening Model for Real Solvents, has been used to predict a set of basic partition coefficients of 22 (alkylated) naphthalenes. To validate the approach, methyl-, dimethyl-, and ethylnaphthalenes have been chosen, according to the availability of experimental data. Then, predictions have been extended to diisopropylnaphthalenes. Given the model's expected uncertainty intervals, COSMO-RS predictions of aqueous solubilities, (subcooled) vapor pressures, Henry's law constants, as well as octanol-water partition coefficients, are in agreement with available literature data. Simultaneous overestimation of aqueous solubilities and vapor pressures of comparable magnitude leads to partial error cancellation in the Henry's law constants. Based on physico-chemical property data obtained with COSMO-RS, the Mackay Level III fugacity model, a steady-state, non equilibrium, and regional-scale model, has been applied to exemplary evaluate the tendency of 2,6-diisopropylnaphthalene to migrate between media by modelling emissions to each individual medium and calculating the amount present at steady state. © 2013 Copyright Taylor and Francis Group, LLC. Source

Lemos J.M.,University of Lisbon | Gomes J.,University of Lisbon | Costa B.A.,University of Lisbon | Mendonca T.,FCUP | Coito A.,University of Lisbon
2011 19th Mediterranean Conference on Control and Automation, MED 2011 | Year: 2011

This work addresses the problem of identifying neuromuscular blockade models of patients undergoing general surgery. First, a sensitivity analysis is made, exploring the Wiener structure of the system. The outcomes of this analysis are twofold: First, it provides information about the time periods in which data is more informative for parameter estimation. Second, it is the basis of a local identifiability analysis that allows to decide which parameters are to be estimated from data and which are the ones whose values should be a priori selected based on previous insight. The time dependency of sensitivity is then used to adjust the weight of output errors in a Bayesian cost function whose minimization yields parameter estimates: Whenever the sensitivity is low, the weight is reduced. The contribution of the paper consists in the demonstration of this procedure using actual clinical data. © 2011 IEEE. Source

Ruela M.,University of Lisbon | Barata C.,University of Lisbon | Mendonca T.,FCUP | Marques J.S.,University of Lisbon
International Symposium on Image and Signal Processing and Analysis, ISPA | Year: 2013

This paper presents a study on the role of shape in the detection of melanomas in dermoscopy images. The contribution of shape-related features was assessed by developing a Computer-Aided Diagnosis (CAD) system whose classification is solely based on this type of features. Four shape descriptors were used, first separately and then simultaneously, to describe the images. Image segmentation was performed both manually, by an expert, and automatically, by using an Adaptive Thresholding algorithm. The best performances were SE = 92% and SP = 74%, obtained for manually segmented images, and SE = 92% and SP = 78%, obtained for automatically segmented images. These results were achieved by combining the shape descriptors and show that shape information plays an important role in melanoma detection. Furthermore, no degradation was observed when automatic segmentation methods are used, instead of manual ones. © 2013 University of Trieste and University of Zagreb. Source

Soderstrom L.,Norwegian University of Science and Technology | Hagborg A.,Science and Education | Von Konrat M.,Science and Education | Seneca A.,FCUP | Seneca A.,Norwegian University of Science and Technology
Polish Botanical Journal | Year: 2013

The first ever liverwort and hornwort checklist is provided for Paraguay. Despite the high level of biological diversity in Paraguay, there remain very few intensive collecting efforts for liverworts and homworts in the region since the late 1800's. We report 2 hornwort taxa and 71 liverwort taxa. The list is based on almost 100 literature references, including monographs, regional studies, and molecular investigations. Given the dramatic loss of habitats in Paraguay coupled with high species diversity in other organisms, further collecting of liverworts and hornworts is critical. There is also the potential to use historical records with contemporary collections to investigate the impact of habitat loss in the area. Source

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