Evaluación y optimización de parámetros PLLR en sistemas de reconocimiento de idioma fonotácticos

Este trabajo tiene como objetivo por un lado describir el estado de la cuestión relacionado con el reconocimiento de idioma (LID), haciendo especial énfasis en aquellos temas que están más relacionados con el desarrollo de este trabajo. Por otra parte se presentan los resultados y conclusiones obtenidos tras el estudio y análisis de diferentes técnicas basadas en los parámetros “Phone Log-Likelihood Ratios” (PLLR) para mejorar el rendimiento de un sistema de reconocimiento de idioma basado en iVectores. En concreto, se presentarán los estudios realizados sobre dos familias de reconocedores de idioma PLLR: los basados en las probabilidades de los fonemas y los basados en las probabilidades de los estados de cada fonema. Estos últimos serán objeto de un estudio más profundo

Influence of hydrogen peroxide in the tribocorrosion behaviour of a CoCrMo biomedical alloy

This paper studies the influence of hydrogen peroxide (H2O2) in simulated body fluids on the wear and corrosion behaviour of a CoCrMo biomedical alloy. CoCrMo are passive materials commonly used in prosthesis and implants because of its high corrosion resistance and mechanical properties. Hydrogen peroxide is produced by bacteria and leukocytes as a consequence of an inflammatory reaction which may modify the tribo-electrochemical response of metals implanted in the human body. Indeed, the oxidizing environment generated by the presence of the peroxide increases the metal dissolution rate. Electrochemical and tribocorrosion tests were carried out in a PBS solution with different addition of H2O2 (0.5, 2, 4 and 12%).The authors acknowledge Generalitat Valencia for the Gerónimo Forteza financial support and to the Electron Microscopy Service of the UPV for the SEM images

Cage Active Contours for image warping and morphing

Cage Active Contours (CACs) have shown to be a framework for segmenting connected objects using a new class of parametric region-based active contours. The CAC approach deforms the contour locally by moving cage's points through affine transformations. The method has shown good performance for image segmentation, but other applications have not been studied. In this paper, we extend the method with new energy functions based on Gaussian mixture models to capture multiple color components per region and extend their applicability to RGB color space. In addition, we provide an extended mathematical formalization of the CAC framework with the purpose of showing its good properties for segmentation, warping, and morphing. Thus, we propose a multiple-step combined method for segmenting images, warping the correspondences of the object cage points, and morphing the objects to create new images. For validation, both quantitative and qualitative tests are used on different datasets. The results show that the new energies produce improvements over the previously developed energies for the CAC. Moreover, we provide examples of the application of the CAC in image segmentation, warping, and morphing supported by our theoretical conclusions

Data-driven System to Predict Academic Grades and Dropout

Nowadays, the role of a tutor is more important than ever to prevent students dropout and improve their academic performance. This work proposes a data-driven system to extract relevant information hidden in the student academic data and, thus, help tutors to offer their pupils a more proactive personal guidance. In particular, our system, based on machine learning techniques, makes predictions of dropout intention and courses grades of students, as well as personalized course recommendations. Moreover, we present different visualizations which help in the interpretation of the results. In the experimental validation, we show that the system obtains promising results with data from the degree studies in Law, Computer Science and Mathematics of the Universitat de Barcelona

Degradation mechanisms in martensitic stainless steels: wear, corrosion and tribocorrosion appraisal

[EN] A deep understanding of degradation mechanisms of metals is crucial for developing new materials with high performance. Within the different families of stainless steels, martensitic stainless steels are widely used in a great variety of industrial applications where mechanical properties, such as strength, wear resistance and fatigue behavior, need to be high. In many of those applications, such as bearings or gears, martensitic stainless steels may be subject to tribological conditions leading to wear. Furthermore, when a contact operates in a corrosive environment its deterioration can be significantly affected by surface chemical phenomena, leading to a tribocorrosion degradation mechanism. Indeed, martensitic stainless steels degrade through a great variety of wear and corrosion mechanisms. This paper aims to review the published data from 2005 to present related to wear, corrosion and tribocorrosion of martensitic stainless steels. Individual studies of tribological and corrosion behavior of martensitic stainless steels have been widely published since 2005. From the wear point of view, ploughing or abrasive wear in dry contacts involving martensitic stainless steel has been reported, while pitting corrosion is the most common mechanism for those steels. However, only nine papers were found since 2005 related to tribocorrosion of martensitic stainless steels, although most authors concluded that this joint action is the most important material degradation in martensitic stainless steels.Dalmau-Borrás, A.; Richard, C.; Igual Muñoz, AN. (2018). Degradation mechanisms in martensitic stainless steels: wear, corrosion and tribocorrosion appraisal. Tribology International. 121:167-179. https://doi.org/10.1016/j.triboint.2018.01.036S16717912

Role of nucleic acid amplification assays in monitoring treatment response in chagas disease: Usefulness in clinical trials

Chagas disease has become a global health problem due to migration of infected people out of Latin America to non-endemic countries. For more than 40 years, only the nitroimidazole compounds Benznidazole and Nifurtimox, have been used for specific treatment of Trypanosoma cruzi infection with disappointing results, specially due to the long duration of treatment and adverse events in the chronic phase. In the last years, ergosterol inhibitors have been also proposed for specific treatment. Different randomized clinical trials were performed for evaluating their treatment efficacy and safety. One of the greatest concerns in clinical trials is to provide an early surrogate biomarker of response to trypanocidal chemotherapy. Serological response is slow and the classical parasitological tests have poor sensitivity and are time-consuming. Nowadays, PCR is the most helpful tool for assessing treatment response in a short period of time. Different protocols of PCR have been developed, being quantitative real time PCR based on amplification of repetitive satellite or minicircle DNA sequences plus an internal amplification standard, the mostly employed strategies in clinical trials. Standardized protocols and the use of an external quality assessment ensure adequate technical procedures and reliable data. Clinical trials have shown a significant reduction in parasite loads, reaching undetectable DNA levels in bloodstream after specific treatment, however events of treatment failure have also been reported. Treatment failure could be due to inadequate penetrance of the drugs into the affected tissues, to the presence of primary or secondary drug resistance of the infecting strains as well as to the existence of dormant parasite variants reluctant to drug action. The early diagnosis of drug resistance would improve clinical management of Chagas disease patients, allowing dictating alternative therapies with a combination of existing drugs or new anti-T. cruzi agents. The aim of this review was to describe the usefulness of detecting T.cruzi DNA by means of real time PCR assays, as surrogate biomarker in clinical trials for evaluating new drugs for CD or new regimens of available drugs and the possibility to detect treatment failure.Fil: Sulleiro Igual, Elena. Universidad Autónoma de Barcelona. Hospital Vall D' Hebron; EspañaFil: Muñoz Calderon, Arturo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentin

Influence of pH on the electrochemical behaviour of a duplex stainless steel in highly concentrated LiBr solutions

[EN] The objective is to study the influence of pH on the corrosion and passive behaviour of duplex stainless steels (DSS) using potentiodynamic measurements, potentiostatic tests and electrochemical impedance spectroscopy (EIS). DSS are spontaneously passive in heavy brine LiBr solutions. Under potentiostatic conditions at applied anodic potentials within the passive domain an equivalent circuit with two time constants is the most suitable model to describe the corrosion mechanism in the interface electrolyte/passive film/metal. pH modifies the electrochemical properties of the passivity of the alloy in a 992. g/L LiBr solution reducing its resistance with the applied potentialWe wish to express our gratitude to MCYT (CTQ2009-07518), to Feder and to Dr. M. Asunción Jaime for her translation assistanceGuiñón Pina, V.; Igual Muñoz, AN.; García Antón, J. (2011). Influence of pH on the electrochemical behaviour of a duplex stainless steel in highly concentrated LiBr solutions. Corrosion Science. 53(2):575-581. https://doi.org/10.1016/j.corsci.2010.09.066S57558153

Tribocorrosion Mechanisms of Ti6Al4V in Artificial Saliva by Zero-Resistance Ammetry (ZRA) Technique

[EN] Degradation mechanisms of biomedical alloys involve two different phenomena, corrosion and wear, which simultaneously act and may cause the failure of implants and prosthesis. In this work, tribocorrosion of Ti6Al4V biomedical alloy in artificial saliva is studied at open circuit potential (OCP) by a new electrochemical technique that allows measuring the galvanic potential and current between the wear track (anode) and the passive material (cathode) through zero-resistance ammetry. The experimental set-up was conceived for physically separating the depassivated area from the passive material, thus allowing to quantify the mechanically activated corrosion at OCP. Two different counterparts, SiC and Al2O3, were used against the Ti6Al4V alloy in order to analyse the influence of the initial contact pressure on the tribocorrosion mechanisms. A galvanic model based on the cathodic reaction kinetics can describe the current and the potential evolution with time during sliding. It has been observed that at the highest initial contact pressures, wear follows the Archard law, while at lower contact pressures, third body appeared and wear can not be described by the Archard law. Quantification of the evolution of the depassivated wear track with time was obtained and the deviation from the Archard predictions was analysed.The authors would like to thank the financial support from NTNU (Project Number 69450741) for performing the experiments of this work and Universitat Politècnica de Valencia VLC/Campus (PMIA-2013) for the mobility Grant.Licausi, M.; Igual Muñoz, AN.; Amigó, V.; Espallargas, N. (2015). Tribocorrosion Mechanisms of Ti6Al4V in Artificial Saliva by Zero-Resistance Ammetry (ZRA) Technique. Journal of Bio- and Tribo-Corrosion (Online). 1(8):1-11. https://doi.org/10.1007/s40735-015-0008-xS11118Martin É, Azzi M, Salishchev GA, Szpunar J (2010) Influence of microstructure and texture on the corrosion and tribocorrosion behaviour of Ti–6Al–4V. Tribol Int 43:918–924Nosonovsky M, Bhushan B (2010) Green tribology: principles, research areas and challenges. Philos Trans R Soc A 368:4677–4694Geetha M, Singh AK, Asokamani R, Gogia AK (2009) Ti based biomaterials, the ultimate choice for orthopaedic implants—a review. Prog Mater Sci 54:397–425Niinomi M, Kuroda D, Fukunaga K, Morinaga M, Kato Y, Yashiro T et al (1999) Corrosion wear fracture of new β type biomedical titanium alloys. Mater Sci Eng A 263:193–199Kuroda D, Niinomi M, Morinaga M, Kato Y, Yashiro T (1998) Design and mechanical properties of new β type titanium alloys for implant materials. Mater Sci Eng A 243:244–249Eisenbarth E, Velten D, Müller M, Thull R, Breme J (2004) Biocompatibility of β-stabilizing elements of titanium alloys. Biomaterials 25:5705–5713More NS, Diomidis N, Paul SN, Roy M, Mischler S (2011) Tribocorrosion behaviour of β titanium alloys in physiological solutions containing synovial components. Mater Sci Eng C 31:400–408Milošev I, Metikoš-Huković M, Strehblow H-H (2000) Passive film on orthopaedic TiAlV alloy formed in physiological solution investigated by X-ray photoelectron spectroscopy. Biomaterials 21:2103–2113Komotori J, Hisamori N, Ohmori Y (2007) The corrosion/wear mechanisms of Ti–6Al–4V alloy for different scratching rates. Wear 263:412–418Dimah MK, Devesa Albeza F, Amigó Borrás V, Igual Muñoz A (2012) Study of the biotribocorrosion behaviour of titanium biomedical alloys in simulated body fluids by electrochemical techniques. Wear 294–295:409–418Licausi MP, Igual Muñoz A, Amigó Borrás V (2013) Tribocorrosion mechanisms of Ti6Al4V biomedical alloys in artificial saliva with different pHs. J Phys D 46:404003Runa MJ, Mathew MT, Rocha LA (2013) Tribocorrosion response of the Ti6Al4V alloys commonly used in femoral stems. Tribol Int 68:85–93Munoz AI, Espallargas N (2011) Tribocorrosion mechanisms in sliding contacts. In: Landolt D, Mischler S (eds) Tribocorrosion of passive metals and coatings. Woodhead Publishing, LausanneMischler S (2008) Triboelectrochemical techniques and interpretation methods in tribocorrosion: a comparative evaluation. Tribol Int 41:573–583Espallargas N, Johnsen R, Torres C, Muñoz AI (2013) A new experimental technique for quantifying the galvanic coupling effects on stainless steel during tribocorrosion under equilibrium conditions. Wear 307:190–197Vieira AC, Rocha LA, Papageorgiou N, Mischler S (2012) Mechanical and electrochemical deterioration mechanisms in the tribocorrosion of Al alloys in NaCl and in NaNO3 solutions. Corros Sci 54:26–35Papageorgiou N, Mischler S (2012) Electrochemical simulation of the current and potential response in sliding tribocorrosion. Tribol Lett 48(3):271–283Papageorgiou N, von Bonin A, Espallargas N (2014) Tribocorrosion mechanisms of NiCrMo-625 alloy: an electrochemical modeling approach. Tribol Int 73:177–186Dearnley PA, Dahm KL, Çimenoglu H (2004) The corrosion-wear behaviour of thermally oxidised CP-Ti and Ti-6Al-4V. Wear 256:469–47