Non INESC TEC publications

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    Spanish coal royal decree: An energy security measure
    ( 2013) Diaz,CA ; José Villar ; Campos,FA ; Gonzalez,P ; Webster,M
    National governments sometimes introduce policies that modify energy markets to achieve other social and political goals. These policies, created with the best of intentions, often have unintended consequences. Here we present a case study of one such policy, the Royal Decree in Spain that mandates the use of the Spanish-Indigenous Coal (IC). © 2013 IEEE.
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    High sensitivity LPG Mach-Zehnder sensor for real-time fuel conformity analysis
    ( 2013) Osorio,JH ; Mosquera,L ; Carlos Jesus Gouveia ; Biazoli,CR ; Hayashi,JG ; Pedro Jorge ; Cordeiro,CMB
    A high sensitivity refractive index sensor based on the combination of mechanically induced long period gratings (LPG) and fiber tapers was developed for real-time fuel quality analysis. The sensor was built in a Mach-Zehnder configuration by employing a pair of in-series gratings. In order to enhance sensor sensitivity, the region between both LPGs was tapered down from 125 to 10 mu m. The system was tested by measuring water concentration in ethanol and ethanol concentration in commercial gasoline. The tapered sensor has shown an average sensitivity of 930 nm/RIU, 18 times higher than the non-tapered version. The resolution limit of the system using spectral interrogation was estimated to be 0.06% of ethanol dissolved in gasoline. For the purpose of real-time monitoring, an interrogation system based on white light interferometry (WLI) and virtual instrumentation was employed to evaluate ethanol evaporation in water, avoiding the use of spectral analysis. The WLI system, using phase tracking techniques, enabled us to record the evolution of the ethanol concentration in water with a resolution of 0.005% (v/v).
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    Design lessons from deploying NFC mobile payments
    ( 2013) Jose,R ; Rodrigues,H ; Melro,A ; Coelho,A ; Marta Campos Ferreira
    The adoption of mobile payment systems is known to face multiple concerns regarding security, usability and value proposition. In this work, we start from the assumption that initial acceptance will always be weak because of the lack of an established usage frame. Instead, we focus on understanding how we can leverage upon the real contact with the technology to create a solid path for gradual acceptance through the development of new practices and the increasing perception of value. In this study, we report on our findings with a real-world prototype of a NFC-based payment system. We identify a set of design lessons that may help to improve the initial phases of NFC-based payment deployments and provide a path for the adoption that focuses on positive initial user experiences and early adoption scenarios. © Springer International Publishing 2013.
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    A new Branch and Bound method for a discrete truss topology design problem
    ( 2013) Adelaide Cerveira ; Agra,A ; Bastos,F ; Gromicho,J
    Our paper considers a classic problem in the field of Truss Topology Design, the goal of which is to determine the stiffest truss, under a given load, with a bound on the total volume and discrete requirements in the cross-sectional areas of the bars. To solve this problem we propose a new two-stage Branch and Bound algorithm. In the first stage we perform a Branch and Bound algorithm on the nodes of the structure. This is based on the following dichotomy study: either a node is in the final structure or not. In the second stage, a Branch and Bound on the bar areas is conducted. The existence or otherwise of a node in this structure is ensured by adding constraints on the cross-sectional areas of its incident bars. In practice, for reasons of stability, free bars linked at free nodes should be avoided. Therefore, if a node exists in the structure, then there must be at least two incident bars on it, unless it is a supported node. Thus, a new constraint is added, which lower bounds the sum of the cross-sectional areas of bars incident to the node. Otherwise, if a free node does not belong to the final structure, then all the bar area variables corresponding to bars incident to this node may be set to zero. These constraints are added during the first stage and lead to a tight model. We report the computational experiments conducted to test the effectiveness of this two-stage approach, enhanced by the rule to prevent free bars, as compared to a classical Branch and Bound algorithm, where branching is only performed on the bar areas.
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    Lane Background Removal for the Classification of Thin-Layer Chromatography Images
    ( 2013) Moreira,BM ; Sousa,AV ; Ana Maria Mendonça ; Aurélio Campilho
    This paper describes a methodology to remove the background of the lanes in Thin Layer Chromatography (TLC) images, aiming at improving band detection and classification. The storage of the biological samples to be analyzed by TLC is usually done via plastic containers. Filter paper is an alternative that allows reduced costs and higher portability, but it increases the complexity of the image analysis stage due to lane background alteration. In order to overcome this problem, a negative control lane is included in every chromatographic plate. After image preprocessing and lane detection stages, a background profile is generated by processing the negative control lane using the Discrete Wavelet Transform (DWT). This profile is then subtracted to the profiles of all other sample lanes in order to overcome the data degradation introduced by filter paper usage. For assessing the proposed background removal process, 105 TLC lanes, with and without background, were used as input for three one-class classifiers. In all cases, the best results were achieved for the lanes after background removal.
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    Scaling Exponents in Heart Rate Variability
    ( 2013) Argentina Leite ; Silva,ME ; Rocha,AP
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    Synergistic Effect between Cisplatin and Sunitinib Malate on Human Urinary Bladder-Cancer Cell Lines
    ( 2013) Arantes Rodrigues,R ; Pinto Leite,R ; Lio Gonçalves ; Palmeira,C ; Santos,L ; Colaco,A ; Oliveira,P
    The aim of this paper is to analyse sunitinib malate in vitro ability to enhance cisplatin cytotoxicity in T24, 5637, and HT1376 human urinary bladder-cancer cell lines. Cells were treated with cisplatin (3, 6, 13, and 18 mu M) and sunitinib malate (1, 2, 4, 6, and 20 mu M), either in isolation or combined, over the course of 72 hours. 3-(4,5-Dimethylthiazol-2-yl)- 2,5-diphenyl tetrazolium bromide assay, acridine orange, and monodansylcadaverine staining and flow cytometry were performed. The combination index (CI) was calculated based on the Chou and Talalay method. In isolation, cisplatin and sunitinib malate statistically (p < 0.05) decrease cell viability in all cell lines in a dose-dependent manner, with the presence of autophagic vacuoles. A cell cycle arrest in early S-phase and in G(0)/G(1) -phase was also found after exposure to cisplatin and sunitinib malate, in isolation, respectively. Treatment of urinary bladder-cancer cells with a combination of cisplatin and sunitinib malate showed a synergistic effect (CI < 1). Autophagy and apoptosis studies showed a greater incidence when the combined treatment was put into use. This hints at the possibility of a new combined therapeutic approach. If confirmed in vivo, this conjugation may provide a means of new perspectives in muscle-invasive urinary bladder cancer treatment.
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    Automatic Classification of Retinal Vessels Using Structural and Intensity Information
    ( 2013) Dashtbozorg,B ; Ana Maria Mendonça ; Aurélio Campilho
    This paper presents an automatic approach for artery/vein (A/V) classification based on the analysis of a graph representing the structure of the retinal vasculature. The entire vascular tree is classified by deciding on the type of each intersection point (graph node) and assigning one of two classes to each vessel segment (graph link). The final label for each vessel segment is accomplished by a combination of structural information taken from the graph (link class) with intensity features measured in the original color image. An accuracy of 88.0% was achieved for the 40 images of the INSPIRE-AVR dataset, thus demonstrating that our method outperforms state-of-the-art approaches for A/V classification.
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    Hourly energy and reserve joint dispatch with a hydro-thermal technological based representation
    ( 2013) Gonzalez,P ; José Villar ; Diaz,CA ; Campos,FA
    Intermittent technologies are enhancing both the economic and technological value of ancillary services in the electric power system. Some of these services commonly denoted as reserves have been liberalized and are offered in the balancing markets in the European Union countries, or in the regulation markets in the USA. This paper presents a deterministic single-node centralized energy and secondary reserve dispatch that outputs hourly scheduled energies and reserves, and both commodities prices. In this model, units of each generation company are simplified into technologies and sub-technologies for faster performance, but still considering inter temporal constraints such as ramps and responding time for reserves, and unit commitment decisions such as start-up and shut-down costs. Detailed short-term hydro-thermal constraints (topology, efficiency, etc.) have been simplified by means of weekly constraints based on historical data (inflows, installed capacity, productions). The model has been validated by comparing its output prices and productions with the real ones occurred during 2010 in the Spanish market with satisfactory results. Furthermore, a study-case on high penetration of solar generation in the Spanish system reveals strong interactions between the energy and reserve markets and points out the importance of hydro technologies in the system. © 2013 IEEE.
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    Telenursing in colorectal cancer patient follow-up and treatment assessment: a mixed methods evaluation study
    ( 2013) Dias,MJ ; Fragoso,M ; Lara Santos,L ; Pedro Pereira Rodrigues
    The incidence of colorectal cancer cases in the Portuguese Institute of Oncology of Porto created the need of a telenursing program in the Gastro-Intestinal Cancer Unit. After staging, treatment may involve surgery radio and chemotherapy (either oral or IV). Patients with no treatment after surgery are scheduled for medical exams every 3 months in the first 2 years. Patients on chemotherapy need to be compliant and to have a close monitoring of adverse events. The GI Cancer Unit uses a telenursing information system to help assess colorectal cancer patients' follow-up after surgery, medical treatment compliance and adverse events. A mixed-methods evaluation was done to a) describe the target population, b) detect problems in the telenursing information system, and c) suggest changes to meet users' requirements. From 181 outbound phone calls, representing 67 patients (49 in treatment and 18 in follow-up), patients' main characteristics were extracted and system's problems were identified by the intervening nurses. Recommendations will be useful for a further development of the system.
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    Interrogation Sensing Scheme Based on a Figure-of-Eight Fiber Loop Mirror
    ( 2013) Silva,RM ; Layeghi,A ; Zibaii,MI ; Latifi,H ; José Luís Santos ; Lobo Ribeiro,ABL ; Orlando Frazão
    A fiber optic interrogation sensor scheme based on a "figure-of-eight" configuration created from a single directional 3 x 3 fiber optic coupler is proposed. Two loops are formed in each arm and one of them contains the sensing head and the other is used as reference signal. A theoretical study based on Jones matrix analysis of this fiber loop mirror combination is reported. The optical configuration is tested as an interrogation scheme for a fiber strain sensor where the spectral response arises from the combination of the reference signal modulated by the sensor signal. The strain sensor configuration shows a phase sensitivity of 6.7 +/- 4.38 x 10(-2) mrad/mu strain by linear regression.
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    Fiber laser sensor based on a phase-shifted chirped grating for acoustic sensing of partial discharges
    ( 2013) Lima,SEU ; Farias,RG ; Araujo,FM ; Ferreira,LA ; José Luís Santos ; Vladimiro Miranda ; Orlando Frazão
    Acoustic emission monitoring is often used in the diagnosis of electrical and mechanical incipient faults in the high voltage apparatus. Partial discharges are a major source of insulation failure in electric power transformers, and the differentiation from other sources of acoustic emission is of the utmost importance. This paper reports the development of a new sensor concept - a fiber laser sensor based on a phase-shifted chirped fiber grating - for the acoustic emission detection of incipient faults in oil-filled power transformers. These sensors can be placed in the inner surface of the transformer tank wall, not affecting the insulation integrity of the structure and improving fault detection and location. The performance of the sensing head is characterized and compared for different surrounding media: air, water, and oil. The results obtained indicate the feasibility of this sensing approach for the industrial development of practical solutions. © 2012 The Author(s).
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    Enhancing traffic sampling scope and efficiency
    ( 2013) João Marco ; Carvalho,P ; Lima,SR
    Traffic Sampling is a crucial step towards scalable network measurements, enclosing manifold challenges. The wide variety of foreseeable sampling scenarios demands for a modular view of sampling components and features, grounded on a consistent architecture. Articulating the measurement scope, the required information model and the adequate sampling strategy is a major design issue for achieving an encompassing and efficient sampling solution. This is the main focus of the present work, where a layered architecture, a taxonomy of existing sampling techniques distinguishing their inner characteristics and a flexible framework able to combine these characteristics are introduced. In addition, a new multiadaptive technique proposal, based on linear prediction, allows to reduce the measurement overhead significantly, while assuring that traffic samples reflect the statistical behavior of the global traffic under analysis. © 2013 IEEE.
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    Robotics in Smart Manufacturing
    ( 2013) Neto,P ; António Paulo Moreira
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    New design for temperature-strain discrimination using fiber Bragg gratings embedded in laminated composites
    ( 2013) Rodriguez Cobo,L ; Marques,AT ; Lopez Higuera,JM ; José Luís Santos ; Orlando Frazão
    A new smart structure based on fiber Bragg gratings (FBGs) embedded into composite laminates for temperature and strain simultaneous measurement has been designed and experimentally tested. Two holes have been drilled at preset locations in the composite plate to create different strain sensitivities at different locations. The proposed design has been compared to three reference sensing heads also based on embedding FBGs into composite materials. Experimental results agree remarkably well with mechanical simulations and validate all the tested designs for the temperature-strain discrimination. Based on the same principle, another sensing head with a long single FBG embedded has also been designed and experimentally tested, obtaining temperature independent strain measurement.
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    Automatic Estimation of the Arteriolar-to-Venular Ratio in Retinal Images Using a Graph-Based Approach for Artery/Vein Classification
    ( 2013) Dashtbozorg,B ; Ana Maria Mendonça ; Aurélio Campilho
    The Arteriolar-to-Venular Ratio (AVR) is a well known index for the diagnosis of diseases such as diabetes, hypertension or cardiovascular pathologies. This paper presents a fully automatic AVR estimation method which uses a graph-based artery/vein classification approach to classify the retinal vessels by a combination of structural information taken from the vasculature graph with intensity features from the original color image. This method was evaluated on the images of the INSPIRE-AVR dataset. The mean error and the correlation coefficient of obtained results with respect to the reference AVR values were identical to the ones obtained by the second observer using a semi-automated system, which demonstrate the potential of the herein proposed solution for clinical application.
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    Computational models for new fiber optic tweezers
    ( 2013) Ana Rita Ribeiro ; Pedro Jorge ; Ariel Guerreiro
    This paper discusses the calculation of the trapping forces in optical tweezers using a combination of the finite differences time domain (FDTD) method and the Lorentz force on electric dipoles. The results of 2D simulations of the trapping of a circular particle by a waveguide with a circular tip are presented and discussed. © 2012 The Author(s).
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    E-cadherin and adherens-junctions stability in gastric carcinoma: Functional implications of glycosyltransferases involving N-glycan branching biosynthesis, N-acetylglucosaminyltransferases III and V
    ( 2013) Pinho,SS ; Figueiredo,J ; Cabral,J ; Carvalho,S ; Dourado,J ; Magalhaes,A ; Gaertner,F ; Ana Maria Mendonça ; Isaji,T ; Cu,JG ; Carneiro,F ; Seruca,R ; Taniguchi,N ; Reis,CA
    Background: E-cadherin is a cell-cell adhesion molecule and the dysfunction of which is a common feature of more than 70% of all invasive carcinomas, including gastric cancer. Mechanisms behind the loss of E-cadherin function in gastric carcinomas include mutations and silencing at either the DNA or RNA level. Nevertheless, in a high percentage of gastric carcinoma cases displaying E-cadherin dysfunction, the mechanism responsible for E-cadherin dysregulation is unknown. We have previously demonstrated the existence of a bi-directional cross-talk between E-cadherin and two major N-glycan processing enzymes, N-acetylglucosaminyltransferase-III or -V (GnT-III or GnT-V). Methods: In the present study, we have characterized the functional implications of the N-glycans catalyzed by GnT-III and GnT-V on the regulation of E-cadherin biological functions and in the molecular assembly and stability of adherens-junctions in a gastric cancer model. The results were validated in human gastric carcinoma samples. Results: We demonstrated that GnT-III induced a stabilizing effect on E-cadherin at the cell membrane by inducing a delay in the turnover rate of the protein, contributing for the formation of stable and functional adherens-junctions, and further preventing clathrin-dependent E-cadherin endocytosis. Conversely, GnT-V promotes the destabilization of E-cadherin, leading to its mislocalization and unstable adherens-junctions with impairment of cell-cell adhesion. Conclusions: This supports the role of GnT-III on E-cadherin-mediated tumor suppression, and GnT-V on E-cadherin-mediated tumor invasion. General significance: These results contribute to fill the gap of knowledge of those human carcinoma cases harboring E-cadherin dysfunction, opening new insights into the molecular mechanisms underlying E-cadherin regulation in gastric cancer with potential translational clinical applications.
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    Next generation of Fabry-Perot sensors for high-temperature
    ( 2013) Marta Sofia Ferreira ; Paulo Roriz Oliveira ; Susana Oliveira Silva ; José Luís Santos ; Orlando Frazão
    This paper presents an overview of optical fiber sensors based on Fabry-Perot interferometers with a focus on high temperature applications. The next generation of these fiber types interferometers are based in photonic crystal fibers, microfabrication as well as by chemical etching of special structures. High temperature measurements with linear behavior are observed namely in un-doped fibers, i.e., with a pure silica composition. Three new configurations are presented as possible solutions to be considered in extreme conditions.