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Fernandes M.J.,University of Porto | Lazaro C.,FCUP | Nunes A.L.,Polytechnic Institute of Porto | Pires N.,FCUP | And 2 more authors.
IEEE Geoscience and Remote Sensing Letters | Year: 2010

This letter presents an innovative method for computing the wet tropospheric correction for altimetry measurements in the coastal regions, where the measurements from the microwave radiometers (MWRs) onboard altimetric missions become invalid. The method, called Global Navigation Satellite System (GNSS)-derived Path Delay, gives an estimation of the correction, along with the associated mapping error, from the combination of independent zenith wet delay (ZWD) values obtained from the tropospheric delays derived at a network of coastal GNSS stations, from the MWR measurements acquired before land degradation, and from the European Centre for Medium-Range Weather Forecasts Deterministic Atmospheric Model. The wet tropospheric correction is estimated at each altimeter point with an invalid MWR value using a linear spacetime objective analysis technique that takes into account the spatial and temporal variability of the ZWD field and the accuracy of each data set used. The method was applied in the South West European region for the whole Envisat data series, and the results are presented here. The uncertainty of the wet-delay estimates is below 1 cm, provided they are obtained for points at distances shorter than ∼50 km from a GNSS station, and/or valid MWR measurements are available for the estimation. The method can be implemented globally and foster the use of satellite altimetry in coastal studies. © 2010 IEEE.


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.


Lemos J.M.,University of Lisbon | Lemos J.M.,Dynamic Systems and Research | Caiado D.V.,Dynamic Systems and Research | Costa B.A.,Dynamic Systems and Research | And 5 more authors.
IEEE Control Systems | Year: 2014

In biomedical systems, feedback control can be applied whenever adequate sensors, actuators, and sufficiently accurate mathematical models are available. The key issue is the capacity of the control algorithm to tackle the large levels of uncertainty, both structured and unstructured, associated with patient dynamics. In the particular case of intravenous anesthesia considered here, manipulated variables are drug infusion rates, administered by syringe pumps, and the measured signal outputs are the levels of hypnosis or depth of anesthesia (DoA) and of neuromuscular blockade (NMB). Figure 1 provides an example of a loop closed for the control of NMB. ©2014IEEE.


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.


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.


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.


Rodrigues M.,IFIMUP IN | Marques M.B.,FCUP | Marques M.B.,INESC Porto | Simeao Carvalho P.,FCUP
Physics Education | Year: 2016

Optics is probably one on the most exciting topics in physics. However, it also contains some of the less understood phenomena by students - the light spectra obtained from the diffraction of light. The experimental study of light spectra for studying radiating bodies, usually requests sophisticated and expensive equipment that is not normaly affordable for schools, and only a few teachers know how to measure the wavelength of light in a spectrum. In this work we present a simple and inexpensive setup, with enough accuracy for measuring light spectra to be used both in physics and chemistry classes. We show how freeware software Tracker, commonly used for teaching mechanics, can serve to measure wavelengths with about 2 nm of resolution. Several approaches to the calibration of different setups are also provided, depending on the degree of accuracy demanded. © 2016 IOP Publishing Ltd.


Rodrigues Ribeiro R.S.,Masdar Institute of Science and Technology | Soppera O.,INESC Porto | Viegas J.,FCUP | Guerreiro A.,CNRS Mulhouse Institute of Materials Science | Jorge P.A.S.,Masdar Institute of Science and Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

In this work, the trapping efficiency of new fiber optical tweezers structures fabricated using photo polymerization and focused ion beam milling techniques is evaluated. The first fabrication methods may present limited capabilities on the tailoring of the structures, and therefore limited operation features. On the other hand, with focused ion beam milling a vast myriad of structures may be accurately fabricated, and contrarily to conventional fabrication methods, more specialized manipulation tools can be developed. In this regard, the performance of FOT for the trapping of yeast cells using spherical lenses (photo polymerization) and spiral phase lenses (FIB) will be presented. In addition, finite difference time domain (FDTD) simulations of the full vectorial optical propagation through the designed structures and the corresponding calculation of the optical forces are presented and different designs are evaluated. © 2015 SPIE.


Gouveia C.,INESC Porto | Gouveia C.,University of Madeira | Zibaii M.,Shahid Beheshti University | Latifi H.,Shahid Beheshti University | And 4 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

In this work a fiber optic interferometric system for differential refractive index measurement is described. The system is based on a white light Mach-Zehnder configuration, with serrodyne phase modulation, used to interrogate two similar non-adiabatic tapered optical fiber sensors in a differential scheme. In this situation the system is able to measure the refractive index independent of temperature. Signal processing with low cost digital instrumentation developed in Labview environment allows a detectable change in refractive index of Δn ≈ 1.46 × 10-6, which is, from the best of our knowledge the highest resolution achieved using a bare fiber taper device for a range of refractive index close to the water index. The results demonstrate the potential of the proposed scheme to operate as a self-referenced chemical and biological sensing platform. © 2013 Elsevier B.V.


PubMed | FCUP
Type: Journal Article | Journal: Mini reviews in medicinal chemistry | Year: 2012

The adjustment of multiple criteria in hit-to-lead identification and lead optimization is a major advance in drug discovery. Thus, the development of approaches able to handle additional criteria for the early simultaneous treatment of the most important properties determining the pharmaceutical profile of a drug candidate is an emergent issue in this area. In this paper, we review a desirability-based multi-objective QSAR method allowing the joint handling of multiple properties of interest in drug discovery: the MOOP-DESIRE methodology. This methodology adapts desirability theory concepts allowing the holistic modeling of the many and conflicting biological properties determining the therapeutic utility of a drug candidate. Here we survey their suitability for key tasks involving the use of chemoinformatics methods in medicinal chemistry and drug discovery.

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