EEG-based brain-computer interfaces using motor-imagery: techniques and challenges.

Electroencephalography (EEG)-based brain-computer interfaces (BCIs), particularly those using motor-imagery (MI) data, have the potential to become groundbreaking technologies in both clinical and entertainment settings. MI data is generated when a subject imagines the movement of a limb. This paper reviews state-of-the-art signal processing techniques for MI EEG-based BCIs, with a particular focus on the feature extraction, feature selection and classification techniques used. It also summarizes the main applications of EEG-based BCIs, particularly those based on MI data, and finally presents a detailed discussion of the most prevalent challenges impeding the development and commercialization of EEG-based BCIs

Síntesis de Sistemas de Conmutación Mediante Permutación de Tablas de Código Gray (Método PGC)

Finding the shortest function on switching systems is a necessity for the development of efficient automatic systems. Currently, several methodologies aim to solve this need with different techniques. This article proposes a new methodology to find a propositional formula that describes a switching system problem using several truth tables which are based on an original one; these tables are generated using Gray Code principles and permutations. As it will be shown, the used code has a direct relation to the Hamiltonian paths, where each permutation is a different connection in a hypervolume, and each node is represented as a bit combination. An algorithm was developed using MATLAB and compared with the solutions from the software Boole-Deusto to verify and validate the applicability and implementation of the method. Finally, examples of execution, computational cost comparison and future work proposals are presented.Encontrar la función más corta en los sistemas de conmutación es una necesidad para el desarrollo de sistemas automáticos eficientes. Actualmente, existen varias metodologías que tienen como objetivo solucionar esta necesidad con diferentes técnicas. Este artículo propone una nueva metodología para encontrar una fórmula proposicional que describa un problema de un sistema de conmutación utilizando varias tablas de verdad que se basan en una original, estas tablas se generan utilizando los principios y permutaciones del Código Gray. Como se mostrará, el código utilizado tiene una relación directa con los caminos hamiltonianos, donde cada permutación es una conexión diferente en un hipervolumen y cada nodo se representa como una combinación de bits. Para verificar y validar el método, se desarrolló un algoritmo utilizando el MATLAB y se comparó con las soluciones del software Boole-Deusto. Finalmente, se presentan ejemplos de ejecución, comparación de costos computacionales y propuestas de trabajos futuros

Spatial variability of hydraulic conductivity and solute transport parameters and their spatial correlations to soil properties

[EN] Spatial variation of the correlation among variables related to water flow and solute transport are important in the characterization of the spatial variability when performing uncertainty analysis and making uncertainty qualified solute transport predictions. However, the spatial variation of the correlation between solute transport parameters and soil properties are rarely studied. In this study, the spatial correlation among laboratory-measured transport parameters dispersivity and coefficient of distribution of a reactive and a nonreactive solute and soil properties were studied at the scale of a few meters using a dense sampling design. In an area of 84 m(2) and a depth of 2 m, 55 undisturbed soil samples were taken to determine the soil properties. Column experiments were performed, and the transport parameters were obtained by fitting the experimental data to the analytical solution of the advection-dispersion equation using the computer program CFITM. Stepwise multiple linear regression (MLR) was performed in order to identify the statistically significant variables. The spatial correlation of the variables and between variables were determined using the Stanford Geostatistical Modeling Software. Soil properties presented a moderate coefficient of variation, while hydraulic conductivity and transport parameters were widely dispersed. The difference between its minimum and maximum value was quite large for most of the studied variables evidencing their high variability. Both dispersivity and retardation factor were higher than the expected and this result can be related to the preferential pathways and to the non-connected micropores. None of the physical soil property was strongly correlated to the transport parameters. Coefficient of distribution was strongly correlated to the cation exchange capacity and significantly correlated to mesoporosity and microporosity. Hydraulic conductivity presented significant positive correlation to the effective porosity and macroporosity. Stepwise multiple linear regression analysis indicated that further studies should be performed aiming to include other variables relevant for lateritic soils such as pH, electrical conductivity, the content of Al and Fe, CaCO3 and soil structure and microstructure. The study of the spatial correlation among transport parameters and soil properties showed that the codispersion among the variables is not constant in space and can be important in dictate the behavior of the combined variables. Our results also showed that some variables that were identified as explanatory in the MLR were not significant in the spatial analysis of the correlation, showing the importance of this kind of analyses for a better decision about the most relevant variables and their relations. The present study was a first attempt to evaluate the spatial variation in the correlation coefficient of transport parameters of a reactive and a nonreactive solute, indicating the more relevant variables and the ones that should be included in future studies.The authors thank the financial support by the Brazilian National Council for Scientific and Technological Development (CNPq) (Project 401441/2014-8). The doctoral fellowship awarded to the first author by the Coordination of Improvement of Higher Level Personnel (CAPES) is gratefully acknowledged. The first author also thanks to the international mobility grant awarded by CNPq, through the Science Without Borders program (grant number: 200597/2015-9), and the international mobility grant awarded by Santander Mobility in cooperation with the University of Sao Paulo.Almeida De-Godoy, V.; Zuquette, LV.; Gómez-Hernández, JJ. (2019). Spatial variability of hydraulic conductivity and solute transport parameters and their spatial correlations to soil properties. Geoderma. 339:59-69. https://doi.org/10.1016/j.geoderma.2018.12.015S596933

SGnn : A Web Server for the Prediction of Prion-Like Domains Recruitment to Stress Granules Upon Heat Stress

Proteins bearing prion-like domains (PrLDs) are essential players in stress granules (SG) assembly. Analysis of data on heat stress-induced recruitment of yeast PrLDs to SG suggests that this propensity might be connected with three defined protein biophysical features: aggregation propensity, net charge, and the presence of free cysteines. These three properties can be read directly in the PrLDs sequences, and their combination allows to predict protein recruitment to SG under heat stress. On this basis, we implemented SGnn, an online predictor of SG recruitment that exploits a feed-forward neural network for high accuracy classification of the assembly behavior of PrLDs. The simplicity and precision of our strategy should allow its implementation to identify heat stress-induced SG-forming proteins in complete proteomes

Computational prediction of protein aggregation : advances in proteomics, conformation-specific algorithms and biotechnological applications

Protein aggregation is a widespread phenomenon that stems from the establishment of non-native intermolecular contacts resulting in protein precipitation. Despite its deleterious impact on fitness, protein aggregation is a generic property of polypeptide chains, indissociable from protein structure and function. Protein aggregation is behind the onset of neurodegenerative disorders and one of the serious obstacles in the production of protein-based therapeutics. The development of computational tools opened a new avenue to rationalize this phenomenon, enabling prediction of the aggregation propensity of individual proteins as well as proteome-wide analysis. These studies spotted aggregation as a major force driving protein evolution. Actual algorithms work on both protein sequences and structures, some of them accounting also for conformational fluctuations around the native state and the protein microenvironment. This toolbox allows to delineate conformation-specific routines to assist in the identification of aggregation-prone regions and to guide the optimization of more soluble and stable biotherapeutics. Here we review how the advent of predictive tools has change the way we think and address protein aggregation

Measuring coupled oscillations using an automated video analysis technique based on image recognition

[EN] The applications of the digital video image to the investigation of physical phenomena have increased enormously in recent years. The advances in computer technology and image recognition techniques allow the analysis of more complex problems. In this work, we study the movement of a damped coupled oscillation system. The motion is considered as a linear combination of two normal modes, i.e. the symmetric and antisymmetric modes. The image of the experiment is recorded with a video camera and analysed by means of software developed in our laboratory. The results show a very good agreement with the theory.This work has received financial support by the Universidad Polit¿ecnica de Valencia (PII20020632), Spain. We would like to thank the R+D+I Linguistic Assistance Office at the Universidad Politècnica de Valencia for their help in revising this paper.Monsoriu Serra, JA.; Gimenez Valentin, MH.; Riera Guasp, J.; Vidaurre, A. (2005). Measuring coupled oscillations using an automated video analysis technique based on image recognition. European Journal of Physics. 26(6):1149-1155. https://doi.org/10.1088/0143-0807/26/6/023S1149115526

PH-dependent aggregation in intrinsically disordered proteins is determined by charge and lipophilicity

Protein aggregation is associated with an increasing number of human disorders and premature aging. Moreover, it is a central concern in the manufacturing of recombinant proteins for biotechnological and therapeutic applications. Nevertheless, the unique architecture of protein aggregates is also exploited by nature for functional purposes, from bacteria to humans. The relevance of this process in health and disease has boosted the interest in understanding and controlling aggregation, with the concomitant development of a myriad of algorithms aimed to predict aggregation propensities. However, most of these programs are blind to the protein environment and, in particular, to the influence of the pH. Here, we developed an empirical equation to model the pH-dependent aggregation of intrinsically disordered proteins (IDPs) based on the assumption that both the global protein charge and lipophilicity depend on the solution pH. Upon its parametrization with a model IDP, this simple phenomenological approach showed unprecedented accuracy in predicting the dependence of the aggregation of both pathogenic and functional amyloidogenic IDPs on the pH. The algorithm might be useful for diverse applications, from large-scale analysis of IDPs aggregation properties to the design of novel reversible nanofibrillar materials

Exploring cryptic amyloidogenic regions in prion-like proteins from plants

Prion-like domains (PrLDs) are intrinsically disordered regions (IDRs) of low sequence complexity with a similar composition to yeast prion domains. PrLDs-containing proteins have been involved in different organisms' regulatory processes. Regions of moderate amyloid propensity within IDRs have been shown to assemble autonomously into amyloid fibrils. These sequences tend to be rich in polar amino acids and often escape from the detection of classical bioinformatics screenings that look for highly aggregation-prone hydrophobic sequence stretches. We defined them as cryptic amyloidogenic regions (CARs) and recently developed an integrated database that collects thousands of predicted CARs in IDRs. CARs seem to be evolutionary conserved among disordered regions because of their potential to stablish functional contacts with other biomolecules. Here we have focused on identifying and characterizing CARs in prion-like proteins (pCARs) from plants, a lineage that has been poorly studied in comparison with other prionomes. We confirmed the intrinsic amyloid potential for a selected pCAR from Arabidopsis thaliana and explored functional enrichments and compositional bias of pCARs in plant prion-like proteins

Valorización de Volcan Compañía Minera S.A.A. y subsidiarias (2016)

El objetivo de este trabajo es presentar los resultados de la valorización económica que se ha realizado a Volcan Compañía Minera S.A.A. y subsidiarias, en adelante “Volcan” o la “Compañía” al cierre del ejercicio 2016, empresa dedicada a la extracción, producción y comercialización de minerales como plata y concentrados de zinc y plomo con operaciones mineras en la sierra central del Perú. Dentro de la presente valorización se efectuaron tres metodologías: i) Flujo de caja descontado (FCD), ii) Múltiplos comparables y iii) Valor contable de la empresa. Volcan, en el año 2016 se encontró dentro del ranking mundial como la quinta empresa productora de zinc, octava de plata y novena de plomo. Para efectuar la valorización se tomó información histórica de los estados financieros trimestrales consolidados y anuales auditados al cierre de los ejercicios 2013 al 2016, memorias anuales y reportes de sostenibilidad. Se consultaron también diversas fuentes de información, tales como documentos emitidos por la Compañía a través de su página web, bases de datos financieras como Bloomberg y Reuters e información pública disponible en la Superintendencia de Mercados y Valores (SMV) y la Bolsa de Valores de Lima (BVL)