Usefulness of Bayesian networks in epidemiological studies

Introduction: Bayesian networks are a form of statistical modelling, which has been widely used in fields like clinical decision, systems biology, human immunodeficiency virus (HIV) and influenza research, analyses of complex disease systems, interactions between multiple diseases and, also, in diagnostic diseases. The present study aimed to show the usefulness of Bayesian networks (BNs) in epidemiological studies. Material and Methods: 3,993 subjects (men 1,758, women 2,235) belonging to the public productive sector from the Balearic Islands (Spain), which were active workers, constitute the data set. Results: A BN was built from a dataset composed of twelve relevant features in cardiovascular disease epidemiology. Furthermore, the structure and parameters were learnt with GeNIe 2.0 tool. Taking into account the main topological properties some features were optimized, obtaining a hypothesized scenario where the likelihoods of the different features were updated and the adequate conclusions were established. Conclusions: Bayesian networks allow us to obtain a hypothetical scenario where the probabilities of the different features are updated according to the evidence that is introduced. This fact makes Bayesian networks a very attractive tool.Introducción: Las redes Bayesianas son una forma de modelización estadística, las cuales han sido ampliamente utilizadas en campos como la decisión clínica, biología de sistemas, virus de inmunodeficiencia humana (VIH) e investigación en influenza, análisis de sistemas de enfermedades complejos, interacciones entre múltiples enfermedades y, también, en enfermedades de diagnóstico. Este estudio tiene como objetivo mostrar la utilidad de las redes Bayesianas en estudios epidemiológicos. Material y Métodos: 3,993 individuos (hombres 1,758, mujeres 2,235) pertenecientes al sector productivo público de las Islas Baleares (España), los cuales eran trabajadores activos, constituyen la base de datos. Resultados: Una red Bayesiana se ha obtenido a partir de una base de datos compuesta de doce características relevantes de la epidemiología de la enfermedad cardiovascular. Por otra parte, la estructura y los parámetros se han obtenido con la herramienta Genie 2.0. Teniendo en cuenta las principales propiedades topológicas algunas características fueron optimizadas. Conclusiones: Las redes Bayesianas permiten obtener un escenario hipotético donde las probabilidades de las diferentes características se van actualizando de acuerdo con la evidencia introducida. Este hecho hace de las redes Bayesianas una herramienta muy atractiva, además permite establecer diversas conclusiones

Perfluoroalkylated substances effects in Xenopus laevis A6 kidney epithelial cells determined by ATR-FTIR spectroscopy and chemometric analysis

The effects of four perfluoroalkylated substances (PFASs), namely, perfluorobutanesulfonate (PFBS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS) and perfluorononanoic acid (PFNA) were assessed in Xenopus laevis A6 kidney epithelial cells by attenuated total reflection Fouriertransform infrared (ATR-FTIR) spectroscopy and chemometric analysis. Principal component analysis-linear discriminant analysis (PCA-LDA) was used to visualize wavenumber-related alterations and ANOVA-simultaneous component analysis (ASCA) allowed data processing considering the underlying experimental design. Both analyses evidenced a higher impact of low-dose PFAS-treatments (10-9 M) on A6 cells forming monolayers, while there was a larger influence of high-dose PFAS-treatments (10-5 M) on A6 cells differentiated into dome structures. The observed dose-response PFAS-induced effects were to some extent related to their cytotoxicity: the EC50-values of most influent PFAS-treatments increased (PFOS<PFNA<PFOA<<PFBS), higherdoses of these chemicals induced a larger impact. Major spectral alterations were mainly attributed to DNA/RNA, secondary protein structure, lipids and fatty acids. Finally, PFOS and PFOA caused a decrease in A6 cell numbers compared to controls, whereas PFBS and PFNA did not significantly change cell population levels. Overall, this work highlights the ability of PFASs to alter A6 cells, whether forming monolayers or differentiated into dome structures, and the potential of PFOS and PFOA to induce cell death

Source apportionment of submicron organic aerosol at an urban background and a road site in Barcelona (Spain) during SAPUSS

This study investigates the contribution of potential sources to the submicron (PM₁) organic aerosol (OA) simultaneously detected at an urban background (UB) and a road site (RS) in Barcelona during the 30 days of the intensive field campaign of SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies, September–October 2010). A total of 103 filters at 12 h sampling time resolution were collected at both sites. Thirty-six neutral and polar organic compounds of known emission sources and photo-chemical transformation processes were analyzed by gas chromatography–mass spectrometry (GC-MS). The concentrations of the trace chemical compounds analyzed are herein presented and discussed. <br><br> Additionally, OA source apportionment was performed by multivariate curve resolution–alternating least squares (MCR-ALS) and six OA components were identified at both sites: two were of primary anthropogenic OA origin and three of secondary OA origin, while a sixth one was not clearly defined. Primary organics from emissions of local anthropogenic activities (urban primary organic aerosol, or POA Urban), mainly traffic emissions but also cigarette smoke, contributed 43% (1.5 μg OC m^&minus;3) and 18% (0.4 μg OC m^&minus;3) to OA at RS and UB, respectively. A secondary primary source – biomass burning (BBOA) – was found in all the samples (average values 7% RS; 12% UB; 0.3 μg OC m^&minus;3), but this component was substantially contributing to OA only when the sampling sites were under influence of regional air mass circulation (REG.). Three secondary organic aerosol (SOA) components (describing overall 60% of the variance) were observed in the urban ambient PM₁. Products of isoprene oxidation (SOA ISO) – i.e. 2-methylglyceric acid, C₅ alkene triols and 2-methyltetrols – showed the highest abundance at both sites when the city was under influence of inland air masses. The overall concentrations of SOA ISO were similar at both sites (0.4 and 0.3 μg m⁻³, or 16% and 7%, at UB and RS, respectively). By contrast, a SOA biogenic component attributed to &alpha;-pinene oxidation (SOA BIO PIN) presented average concentrations of 0.5 μg m⁻³ at UB (24% of OA) and 0.2 μg m^&minus;3 at RS (7%), respectively, suggesting that this SOA component did not impact the two monitoring sites at the same level. A clear anti-correlation was observed between SOA ISO and SOA PIN during nucleation days, surprisingly suggesting that some of the growth of urban freshly nucleating particles may be driven by biogenic α-pinene oxidation products but inhibited by isoprene organic compounds. A third SOA component was formed by a mixture of aged anthropogenic and biogenic secondary organic compounds (SOA Aged) that accumulated under stagnant atmospheric conditions, contributing for 12% to OA at RS (0.4 μg OC m^&minus;3) and for 18% at UB (0.4 μg OC m^&minus;3). <br><br> A sixth component, formed by C₇–C₉ dicarboxylic acids and detected especially during daytime, was called "urban oxygenated organic aerosol" (OOA Urban) due to its high abundance at urban RS (23%; 0.8 μg OCm^&minus;3) vs. UB (10%; 0.2 μg OCm^&minus;3), with a well-defined daytime maximum. This temporal trend and geographical differentiation suggests that local anthropogenic sources were determining this component. However, the changes of these organic molecules were also influenced by the air mass trajectories, indicating that atmospheric conditions have an influence on this component, although the specific origin on this component remains unclear. It points to a secondary organic component driven by primary urban sources including cooking and traffic (mainly gasoline) activities

Impacts of metals and nutrients released from melting multiyear Arctic sea ice

Nutrients (C, N, and P) and metals (iron, molybdenum, nickel, zinc, vanadium, copper, and cobalt) were determined in water and multiyear ice sampled along the Greenland current and Fram Strait in July 2007. Total metal and nutrient concentrations in ice varied fivefold to tenfold, for most elements, across the area sampled. Data show that some nutrients (i.e., NH4+) and metals (i.e., Fe, Zn, V, Cu, Ni, Mo, and Co) are enriched in Arctic ice relative to surface seawaters, suggesting that ice melting is a significant source of metals to the receiving seawaters, particularly Fe and Zn whose concentrations were significantly (t test, P < 0.05) more than 2 orders of magnitude higher in ice than in surface seawater.This research is part of the ATOS project, funded as part of the Spanish contribution to the International Polar Year (IPY) by the Spanish Ministry of Science and Innovation (POL2006-00550/CTM). This is a contribution to the GEOTRACES cluster of the IPY. We thank the ATOS participants, UTM and crew of R/V Hespérides for help with ice sampling and logistics. We thank R. Santiago, R. Martínez, and A. Massanet at IMEDEA and J. A. González (SCT, UIB) for help with chemical analyses. This manuscript was written in the field stations of Ses Salines Lighthouse.Peer reviewe

Tres generaciones de serpentina en el perfil laterítico niquelífero del Ne de Cuba)

Los yacimientos lateríticos de Ni-Co producen actualmente alrededor del 40% del Ni mundial. Sin embargo, el conocimiento sobre la distribución de Ni en las distintas fases minerales presentes en estos depósitos es sólo a un nivel muy genérico y de poco detalle composicional y estructural

Comparative study of Spanish norms used to quantify gypsum content in civil and building construction

The "Pliego de Prescripciones Técnicas Generales para Obras de Carreteras y Puentes (PG3)" is the Spanish's Government Technical Instruction that stablishes the properties that materials used in road and bridge construction must accomplish, and includes the corresponding standardized norms to test these properties

Garnierite Mineralization from Falcondo Ni-Laterite Deposit (Dominican Republic)

Mine geologists use the term "garnierite" for the green Ni-rich silicate minerals that occur in many Ni-laterite deposits. However, garnierite is not a mineral species recognized by the Commission on New Mineral and Mineral Names (CNMMN). Actually, garnierite is a general name for the NiMg hydrosilicates that usually occur as an intimate mixture that commonly includes two or more of the following minerals: serpentine, talc, sepiolite, smectite, and chlorite (e.g. Brindley and Hang, 1973; Springer, 1974; Brindley et al., 1979; Gleeson et al., 2004)

Local migration quantification method for scratch assays

The scratch assay is an in vitro technique used to assess the contribution of molecular and cellular mechanisms to cell migration. The assay can also be used to evaluate therapeutic compounds before clinical use. Current quantification methods of scratch assays deal poorly with irregular cell-free areas and crooked leading edges which are features typically present in the experimental data. We introduce a new migration quantification method, called 'monolayer edge velocimetry', that permits analysis of low-quality experimental data and better statistical classification of migration rates than standard quantification methods. The new method relies on quantifying the horizontal component of the cell monolayer velocity across the leading edge. By performing a classification test on in silico data, we show that the method exhibits significantly lower statistical errors than standard methods. When applied to in vitro data, our method outperforms standard methods by detecting differences in the migration rates between different cell groups that the other methods could not detect. Application of this new method will enable quantification of migration rates from in vitro scratch assay data that cannot be analysed using existing methods