On és la química? Com podem aprendre a descobrir-la?

A l'Escola Politècnica Superior d'Enginyeria de Manresa (Departament d'Enginyeria Minera i Recursos Naturals), fa sis anys, es va començar la iniciativa de l'exposició «On és la química?», amb l'objectiu de mostrar als estudiants de secundària que la química es troba en tot allò que ens envolta. L'experiència va ser molt ben rebuda i es va ampliar amb el taller «Què és l'enginyeria química?», en el qual els estudiants prenen una part més activa. Finalment, s'ha completat amb l'edició d'una taula periòdica digital.In the Escola Politècnica Superior d’Enginyeria de Manresa (Department Of Mining Engineering and Natural Resources), the iniciative of the exhibition «Where is chemistry?», began six years ago with the aim of showing secondary students that chemistry exists in everything around them. The exhibition was very successful and was expanded with the workshop «What is chemical engineering?», where students played a more active role. Finally, it has been completed with the addition of a digital periodic table

Hemodynamic on abdominal aortic aneurysm: Parametric study

El objetivo del presente estudio es determinar qué influencia tienen los parámetros geométricos con las tensiones hemodinámicas en aneurismas abdominales aórticos. Para ello los autores han creado varios modelos geométricos de aneurismas abdominales basándose en sus principales características geométricas (diámetro máximo, diámetro mínimo, longitud aneurisma y asimetría) y técnicas computacionales para calcular la presión y la tensión de corte en el saco aneurismático. Los resultados obtenidos constatan que la presión hemodinámica es la principal carga mecánica que actúa sobre la pared arterial y que la morfometría de los aneurismas podría ser utilizada como buen predictor del riesgo de rotura. Posteriormente, con el objetivo de determinar si los modelos geométricos se podrían usar como aproximación de modelos reales, se compararon varios modelos reales (patient-specific) con sus respectivos modelos geométricos obteniendo una buena aproximación.The aim of this study is to assess how the shape of the abdominal aortic aneurysms (AAA) affects the hemodynamic wall stresses. With this purpose, different AAAs are studied through simplified models based on geometrical parameters of the aneurism such as its maximum and minimum diameter, length and asymmetry. Then, a computational fluid dynamics analysis is performed on the simplified models in order to compute pressure and wall shear stresses on the aneurysm sac. The results obtained show that blood pressure is the main dynamic load acting on the artery wall, and that the morphology of the aneurysm could be a good indicator of risk of failure. Furthermore, the computational results are compared with patient-specific real models with the objective to assess the reliability of the proposed simplified approach.Peer Reviewe

Aportacions de l'índex de connectivitat ecològica a la planificació territorial i a l'avaluació ambiental estratègica, en el context de les recerques i les polítiques de connectivitat ecològica a Catalunya

En el present article, s'hi descriu l'índex de connectivitat ecològica (ICE), una metodologia paramètrica per analitzar i avaluar la connectivitat dels ecosistemes terrestres, dins d'una sinopsi del desenvolupament dels estudis i les polítiques de connectivitat ecològica a Catalunya. L'ICE ha estat desenvolupat pels autors en tres versions successives al llarg dels darrers sis anys. Se n'hi exposa la motivació, les potencialitats, les aplicacions actuals i les previsibles, especialment quant a la planificació territorial i l'avaluació ambiental estratègica, i se n'hi examinen les potencialitats en el marc de les possibilitats que han obert les directrius de connectivitat ecològica de Catalunya de 2006.En el presente artículo, se describe el índice de conectividad ecológica (ICE), una metodología paramétrica para analizar la conectividad ecológica de los ecosistemas terrestres, en el contexto de una síntesis del desarrollo de los estudios y las políticas de conectividad ecológica en Cataluña, una comunidad autónoma española con plenas competencias en los ámbitos de la ordenación territorial, evaluación estratégica y conservación de la naturaleza. El ICE ha sido desarrollado por los autores, con tres versiones sucesivas, a lo largo de los últimos seis años. De él se exponen su razón de ser, sus potencialidades, así como sus aplicaciones actuales y previsibles, especial mente en cuanto a la planificación territorial y la evaluación ambiental estratégica, en el marco de las posibilidades que abren les directrices de conectividad ecológica de Cataluña de 2006.On décrit l'index de connectivité écologique (ICE), une méthodologie paramétrique pour analyser et évaluer la connectivité des écosystèmes terrestres, dans de contexte du développement des études et des politiques de connectivité écologique de la Catalogne espagnole, une communauté autonome qu'a pleines responsabilités dans le domaine de l'aménagement du territoire, l'évaluation environnementale et la conservation de la nature. L'ICE a été développé par les auteurs en trois versions consécutives pendant les six dernières années. On n'explique la motivation, les potentialités, leurs applications actuels i prévisibles, spécialement en ce qui concerne l'aménagement du territoire et l'évaluation environnementale stratégique. Finalement, on montre les potentialités que l'ICE offre de dans le cadre des possibilités que viennent d'ouvrir les Directrices pour la connectivité écologique de la Catalogne de 2006.This paper presents in short the index of ecological connectivity (IEC), a parametric methodology to analyze and evaluate the ecological connectivity of terrestrial ecosystems. This is done in the context of the development of researches and policies of ecological connectivity in Catalonia, a Spanish Autonomy with full powers in land planning, environmental evaluation and nature conservation. The IEC has been developed by the authors in three consecutive versions during the last six years. The discussion includes the motivation of the IEC, its potentialities, and its present and foreseeable applications, mainly in land planning and strategic environmental assessment. Finally there is a discussion about the potential uses of the IEC in the frame of the directives for ecological connectivity of Catalonia of 2006

The Overlooked Potential of Generalized Linear Models in Astronomy - I: Binomial Regression

Revealing hidden patterns in astronomical data is often the path to fundamental scientific breakthroughs; meanwhile the complexity of scientific inquiry increases as more subtle relationships are sought. Contemporary data analysis problems often elude the capabilities of classical statistical techniques, suggesting the use of cutting edge statistical methods. In this light, astronomers have overlooked a whole family of statistical techniques for exploratory data analysis and robust regression, the so-called Generalized Linear Models (GLMs). In this paper -- the first in a series aimed at illustrating the power of these methods in astronomical applications -- we elucidate the potential of a particular class of GLMs for handling binary/binomial data, the so-called logit and probit regression techniques, from both a maximum likelihood and a Bayesian perspective. As a case in point, we present the use of these GLMs to explore the conditions of star formation activity and metal enrichment in primordial minihaloes from cosmological hydro-simulations including detailed chemistry, gas physics, and stellar feedback. We predict that for a dark mini-halo with metallicity $\approx 1.3 \times 10^{-4} Z_{\bigodot}$, an increase of $1.2 \times 10^{-2}$ in the gas molecular fraction, increases the probability of star formation occurrence by a factor of 75%. Finally, we highlight the use of receiver operating characteristic curves as a diagnostic for binary classifiers, and ultimately we use these to demonstrate the competitive predictive performance of GLMs against the popular technique of artificial neural networks.Comment: 20 pages, 10 figures, 3 tables, accepted for publication in Astronomy and Computin

A probabilistic approach to emission-line galaxy classification

We invoke a Gaussian mixture model (GMM) to jointly analyse two traditional emission-line classification schemes of galaxy ionization sources: the Baldwin-Phillips-Terlevich (BPT) and $\rm W_{H\alpha}$ vs. [NII]/H$\alpha$ (WHAN) diagrams, using spectroscopic data from the Sloan Digital Sky Survey Data Release 7 and SEAGal/STARLIGHT datasets. We apply a GMM to empirically define classes of galaxies in a three-dimensional space spanned by the $\log$ [OIII]/H$\beta$, $\log$ [NII]/H$\alpha$, and $\log$ EW(H${\alpha}$), optical parameters. The best-fit GMM based on several statistical criteria suggests a solution around four Gaussian components (GCs), which are capable to explain up to 97 per cent of the data variance. Using elements of information theory, we compare each GC to their respective astronomical counterpart. GC1 and GC4 are associated with star-forming galaxies, suggesting the need to define a new starburst subgroup. GC2 is associated with BPT's Active Galaxy Nuclei (AGN) class and WHAN's weak AGN class. GC3 is associated with BPT's composite class and WHAN's strong AGN class. Conversely, there is no statistical evidence -- based on four GCs -- for the existence of a Seyfert/LINER dichotomy in our sample. Notwithstanding, the inclusion of an additional GC5 unravels it. The GC5 appears associated to the LINER and Passive galaxies on the BPT and WHAN diagrams respectively. Subtleties aside, we demonstrate the potential of our methodology to recover/unravel different objects inside the wilderness of astronomical datasets, without lacking the ability to convey physically interpretable results. The probabilistic classifications from the GMM analysis are publicly available within the COINtoolbox (https://cointoolbox.github.io/GMM\_Catalogue/).Comment: Accepted for publication in MNRA

Exploring the spectroscopic diversity of type Ia supernovae with DRACULA: a machine learning approach

The existence of multiple subclasses of type Ia supernovae (SNeIa) has been the subject of great debate in the last decade. One major challenge inevitably met when trying to infer the existence of one or more subclasses is the time consuming, and subjective, process of subclass definition. In this work, we show how machine learning tools facilitate identification of subtypes of SNeIa through the establishment of a hierarchical group structure in the continuous space of spectral diversity formed by these objects. Using Deep Learning, we were capable of performing such identification in a 4 dimensional feature space (+1 for time evolution), while the standard Principal Component Analysis barely achieves similar results using 15 principal components. This is evidence that the progenitor system and the explosion mechanism can be described by a small number of initial physical parameters. As a proof of concept, we show that our results are in close agreement with a previously suggested classification scheme and that our proposed method can grasp the main spectral features behind the definition of such subtypes. This allows the confirmation of the velocity of lines as a first order effect in the determination of SNIa subtypes, followed by 91bg-like events. Given the expected data deluge in the forthcoming years, our proposed approach is essential to allow a quick and statistically coherent identification of SNeIa subtypes (and outliers). All tools used in this work were made publicly available in the Python package Dimensionality Reduction And Clustering for Unsupervised Learning in Astronomy (DRACULA) and can be found within COINtoolbox (https://github.com/COINtoolbox/DRACULA).Comment: 16 pages, 12 figures, accepted for publication in MNRA

Actualización en síndrome hemolítico urémico atípico: diagnóstico y tratamiento. Documento de consenso

Trobareu una actualització (2015) d'aquest document a: http://hdl.handle.net/2445/99427Haemolytic uraemic syndrome (HUS) is a clinical entity defined as the triad of nonimmune haemolytic anaemia, thrombocytopenia, and acute renal failure, in which the underlying lesions are mediated by systemic thrombotic microangiopathy (TMA). Atypical HUS (aHUS) is a sub-type of HUS in which the TMA phenomena are the consequence of decreased regulation of the alternative complement pathway on cell surfaces due to a genetic cause. aHUS is an extremely rare disease that, despite the administration of standard treatment with plasma therapy, often progresses to terminal chronic renal failure with a high associated rate of mortality. In recent years, research has established the key role that the complement system plays in the induction of endothelial damage in patients with aHUS, through the characterisation of multiple mutations and polymorphisms in the genes that code for certain complement factors. Eculizumab is a monoclonal antibody that inhibits the terminal fraction of the complement protein, blocking the formation of a cell membrane attack complex. In prospective studies in patients with aHUS, administering eculizumab produces a rapid and sustained interruption in the TMA process, with significant improvements in long-term renal function and an important decrease in the need for dialysis or plasma therapy. In this document, we review and bring up to date the important aspects of this disease, with special emphasis on how recent advancements in diagnostic and therapeutic processes can modify the treatment of patients with aHUS

Estudio de los métodos para la evaluación de los proveedores para una empresa de fabricación de maquinaria agrícola

El objeto de este proyecto es el estudio de los métodos para la evaluación de los proveedores para una empresa de fabricación de maquinaria agrícola y la implantación de la misma. Concretamente maquinaria agrícola pesada destinada al transporte de productos agrícolas. Dicha fábrica estará situada en la provincia de Lérida