Grupo de Ingeniería Estadística Multivariante GIEM
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Innovation project to validate and select items for assessing transversal competencies in higher education
[EN] The educational improvement innovation project is focused on determining how to evaluate any competence and which are their main related items that should be used for that purpose. Currently, the selection of items is usually performed by groups of experts. However, two main problems related to this type of selection arise in this case: on the one hand, the selection resulting from different groups of experts may be not the same or similar enough, since it is based on the experience and knowledge of each member. On the other hand, the coefficients or weights a priori assigned to each item on any competence invalidate any a posteriori analysis on its statistical significance and the "real" weight on this competence. To mitigate the above drawbacks, this work presents a methodology able to select, from an objective point of view, the items related to a specific competence, from a set of potentially related ones; furthermore the weights associated to the items are determined. This is carried out by applying a multivariate statistical projection method such as Partial Least Squares (PLS), embedded in a cross-validation process. The paper presents how to preprocess the data, analyze it and obtain the items and their weights to be used for the evaluation of a specific competence.
Determination of phytoplankton composition using absorption spectra
Characterisation of phytoplankton communities in aquatic ecosystems is a costly task in terms of time, material and human resources. The general objective of this paper is not to replace microscopic counts but to complement them, by fine-tuning a technique using absorption spectra measurements that reduces the above-mentioned costs. Therefore, the objective proposed in this paper is to assess the possibility of achieving a qualitative determination of phytoplankton communities by classes, and also a quantitative estimation of the number of phytoplankton cells within each of these classes, using spectrophotometric determination. Samples were taken in three areas of the Spanish Mediterranean coast. These areas correspond to estuary systems that are influenced by both continental waters and Mediterranean Sea waters. 139 Samples were taken in 7–8 stations per area, at different depths in each station. In each sample, the absorption spectrum and the phytoplankton classes (Bacyllariophyceae (diatoms), Cryptophyceae, Clorophyceae, Chrysophyceae, Prasynophyceae, Prymnesophyceae, Euglenophyceae, Cyanophyceae, Dynophyceae and the Synechococcus sp.) were determined. Data were analysed by means of the Partial Least Squares (PLS) multivariate statistical technique. The absorbances obtained between 400 and 750 nm were used as the independent variable and the cell/l of each phytoplankton class was used as the dependent variable, thereby obtaining models which relate the absorbance of the sample extract to the phytoplankton present in it. Good results were obtained for diatoms (Bacillarophyceae), Chlorophyceae and Cryptophyceae. © 2009 Elsevier B.V. All rights reserved.
Mejora de la calidad y la productividad en la fabricación de resinas en la empresa Ppg Ibérica ( planta de Quart de Poblet ) mediante la estrategia Seis Sigma de mejora de procesos
Proyecto Confidencial
A statistical approach for a-posteriori deployment of microclimate sensors in museums: a case study
[EN] The deployment of sensors is the first issue encountered when microclimate monitoring is planned in spaces devoted to the conservation of artworks. Sometimes, the first decision regarding the position of sensors may not be suitable for characterising the microclimate close to climate sensitive artworks or should be revised in light of new circumstances. This paper fits into this context by proposing a rational approach for a posteriori deployment of microclimate sensors in museums where long-term temperature and relative humidity observations were available (here, the Rosenborg Castle, Copenhagen, Denmark). Different statistical tools such as box-and-whisker plots, principal component analysis (PCA) and cluster analysis (CA) were used to identify microclimate patterns, i.e., similarities of indoor air conditions among rooms. Box-and-whisker plots allowed us to clearly identify one microclimate pattern in two adjoining rooms located in the basement. Multivariate methods (PCA and CA) enabled us to identify further microclimate patterns by grouping not only adjoining rooms but also rooms located on different floors. Based on these outcomes, new configurations about the deployment of sensors were proposed aimed at avoiding redundant sensors and collecting microclimate observations in other sensitive locations of this museum.
Plenos municipales: datos abiertos, agenda 2030 y ontología
[ES] El pleno municipal es el máximo órgano de representación política de la ciudadanía en el ámbito municipal. Es un órgano colegiado en el que se ponen a debate los problemas que afectan a los municipios y, en consecuencia, se toman medidas para combatirlos. Con la finalidad de que la ciudadanía pueda acceder a la información de los plenos municipales, con el apoyo de la Càtedra de Govern Obert, adscrita a la Universitat Politècnica de València, se desarrolló una ontología para la publicación de datos de los plenos municipales. Ahora, se realizará una revisión normativa aplicable a los plenos municipales, trabajando desde el paradigma del Buen Gobierno y sus principios. Adicionalmente, se propone una adaptación de toda la información de la ontología a los estándares de Lectura Fácil. Otra vía importante para disponer de información relevante de los plenos municipales son los datos abiertos. Estos son un instrumento muy importante que favorece el empoderamiento de la ciudadanía, ya que disponer de datos es el primer paso para disponer de información relevante, avalada por los datos, y que permite tomar decisiones. Consecuentemente, favorecen la participación de la ciudadanía en el paradigma de gobierno abierto. Los datos abiertos son de fácil acceso desde los Portales de datos abiertos y permiten a la ciudadanía conocer y disponer de los datos que se genera en las administraciones. En este contexto, se propone diseñar un conjunto de datos en el que se puedan registrar distintas variables vinculadas a los plenos municipales. Se estudiará que variables formarán parte de este conjunto de datos y ser trabajará en su estandarización para que se pueda comparar este conjunto de datos abiertos en las distintas Entidades Locales. Será importante incluir diversas variables que contribuyan a la trazabilidad y seguimiento de las decisiones y acuerdos que se adoptan en los plenos hasta que se implementan, y si es posible, cuáles son sus consecuencias e impacto. Por otro lado, también resulta de interés relacionar las decisiones que se adoptan en los plenos municipales y su impacto con los Objetivos de Desarrollo Sostenible (ODS) y las metas de la Agenda 2030 de Naciones Unidas. Podrán utilizarse indicadores ya propuestos en la Agenda 2030 o nuevos indicadores que se para medir el impacto. En este sentido, se trabajará con la perspectiva de los OD4D (Datos Abiertos para el Desarrollo Sostenible). Todos estos nuevos aspectos de los plenos municipales generan datos e , información de calidad accesible para la ciudadanía, empoderándolas para una mayor participación y rendición de cuentas. En definitiva, favorecen la apertura de los datos y la transparencia.
Differential expression in RNA-seq: A matter of depth
Next-generation sequencing (NGS) technologies are revolutionizing genome research, and in particular, their application to transcriptomics (RNA-seq) is increasingly being used for gene expression profiling as a replacement for microarrays. However, the properties of RNA-seq data have not been yet fully established, and additional research is needed for understanding how these data respond to differential expression analysis. In this work, we set out to gain insights into the characteristics of RNA-seq data analysis by studying an important parameter of this technology: the sequencing depth. We have analyzed how sequencing depth affects the detection of transcripts and their identification as differentially expressed, looking at aspects such as transcript biotype, length, expression level, and fold-change. We have evaluated different algorithms available for the analysis of RNA-seq and proposed a novel approach-NOISeq-that differs from existing methods in that it is data-adaptive and nonparametric. Our results reveal that most existing methodologies suffer from a strong dependency on sequencing depth for their differential expression calls and that this results in a considerable number of false positives that increases as the number of reads grows. In contrast, our proposed method models the noise distribution from the actual data, can therefore better adapt to the size of the data set, and is more effective in controlling the rate of false discoveries. This work discusses the true potential of RNA-seq for studying regulation at low expression ranges, the noise within RNA-seq data, and the issue of replication. © 2011 by Cold Spring Harbor Laboratory Press.
Evaluation of corrective measures implemented for the preventive conservation of fresco paintings in Ariadne s house (Pompeii, Italy)
BACKGROUND: A microclimate monitoring study was conducted in 2008 aimed at assessing the conservation risks affecting the valuable wall paintings decorating Ariadne s House (Pompeii, Italy). It was found that thermohygrometric conditions were very unfavorable for the conservation of frescoes. As a result, it was decided to implement corrective measures, and the transparent polycarbonate sheets covering three rooms (one of them delimited by four walls and the others composed of three walls) were replaced by opaque roofs. In order to examine the effectiveness of this measure, the same monitoring system comprised by 26 thermohygrometric probes was installed again in summer 2010. Data recorded in 2008 and 2010 were compared. RESULTS: Microclimate conditions were also monitored in a control room with the same roof in both years. The average temperature in this room was lower in 2010, and it was decided to consider a time frame of 18 summer days with the same mean temperature in both years. In the rooms with three walls, the statistical analysis revealed that the diurnal maximum temperature decreased about 3.5 ºC due to the roof change, and the minimum temperature increased 0.5 ºC. As a result, the daily thermohygrometric variations resulted less pronounced in 2010, with a reduction of approximately 4 ºC, which is favorable for the preservation of mural paintings. In the room with four walls, the daily fluctuations also decreased about 4 ºC. Based on the results, other alternative actions are discussed aimed at improving the conservation conditions of wall paintings. CONCLUSIONS: The roof change has reduced the most unfavorable thermohygrometric conditions affecting the mural paintings, but additional actions should be adopted for a long term preservation of Pompeian frescoes.
Role of chromatin modifying enzymes and histone acetylation in the regulation of the yeast metabolic cycle
[EN] The yeast metabolic cycle (YMC) is a phenomenon that occurs in the baking yeast Saccharomyces cerevisiae. The YMC is produced at low glucose levels with a continuous feeding of the culture, and it is characterized by a cyclic expression of genes, together with cycles of oxygen consumption that repeat every 4–5 hours. These cycles feature three clearly differentiated phases, with sets of genes with characteristic functionalities expressing in each one of them. The first one is the oxidative phase, in which genes related to ribosome and amino acid synthesis are upregulated. The reductive/building phase is characterized by peaks in genes related to mitochondria and cell cycle. The oxygen consumption diminishes in this phase. In the reductive/charging phase, there is an increase in functionalities related to non-respiratory metabolism, fatty acids consumption and storage of carbohydrates. The characterization of the YMC has been performed by metabolic state studies, chromatin state studies and studies of gene expression, among others. For this study, public data of ChIPSeq of three chromatin modifying enzymes, Esa1, Gcn5 and Set1 (two acetyltransferases and one methyltransferase, respectively), were used. Data of histone modifications have also been integrated, focusing on the modifications H3K18ac and H3K9ac, because of their relevance in the regulation of gene expression. With this study, it was intended to understand the relationship between the chromatin modifying enzymes and the histone modifications H3K18ac and H3K9ac, and to study their impact on the gene expression and their importance in the YMC. To do this, ChIP-Seq data of Esa1, Gcn5 and Set were processed, and a study of the regions to which their attachment changed with time was performed, and also a multi-omics integration with histone acetylation data. These results can help to infer the possible regulation networks in which the chromatin plays an important role in the regulation of the gene expression during the YMC.
Statistical Process Control based on Multivariate Image Analysis: A new proposal for monitoring and defect detection
The monitoring, fault detection and visualization of defects are a strategic issue for product quality. This paper presents a novel methodology based on the integration of textural Multivariate image analysis (MIA) and multivariate statistical process control (MSPC) for process monitoring. The proposed approach combines MIA and p-control charts, as well as T2 and RSS images for defect location and visualization. Simulated images of steel plates are used to illustrate the monitoring performance of it. Both approaches are also applied on real clover images.
Multi-synchro: a novel approach for batch synchronization in scenarios of multiple asynchronisms
Batch synchronization has been widely misunderstood as being only needed when variable trajectories have uneven length. Batch data are actually considered not synchronized when the key process events do not occur at the same point of process evolution, irrespective of whether the batch duration is the same for all batches or not. Additionally, a single synchronization procedure is usually applied to all batches without taking into account the nature of asynchronism of each batch, and the presence of abnormalities. This strategy may distort the original trajectories and decrease the signal-to-noise ratio, affecting the subsequent multivariate analyses. The approach proposed in this paper, named multisynchro, overcomes these pitfalls in scenarios of multiple asynchronisms. The different types of asynchronisms are effectively detected by using the warping information derived from synchronization. Each set of batch trajectories is synchronized by appropriate synchronization procedures, which are automatically selected based on the nature of asynchronisms present in data. The novel approach also includes a procedure that performs abnormality detection and batch synchronization in an iterative manner. Data from realistic simulations of a fermentation process of the Saccharomyces cerevisiae cultivation are used to illustrate the performance of the proposed approach in a context of multiple asynchronisms.