304 research outputs found
Características geomorfológicas y evolución del medio litoral de la zona de Empuries (Girona)
[Resumen] Se aborda la reconstrucción y evolución del entorno físico de la zona próxima al conjunto arqueológico greco-romano de Empuries. La combinación de los datos arqueológicos y geomorfológicos aporta nuevas perspectivas en los dos campos. Al inicio de la colonización la cota se situaba más al interior y presentaba una morfología irregular con acantilados e islotes. Posteriormente se produce una progradación y una regularización de la costa, con un predominio de sedimentos arenosos. Este cambio se interpreta como consecuencia de un descenso del nivel del mar y un cambio del uso del suelo. Esta progradación hacia el E conlleva una movilización de arenas hacia el S, que a su vez puede relacionarse con los desplazamientos de los distintos núcleos de población de Empuries[Abstract] This paper envisages the reconstruction and evolution of the physical environment of the Empurias archeological site and adjoining area. The combination of archeological and geomorphological data provides new insights in both fields. In the early ages of colonization the coast was situated more inland and showed an irregular morphology with cliffs and small islands.The lowereing of the sea and a change of land use caused later coast progradation and regularization with a predominance of sandy sediments. Eastwards progradation is linked to southwards sandy-dune transporte The moving off of different archeological sites in Empuries can be related to the above mentioned sandy-dune transport
The INTERPRET Decision-Support System version 3.0 for evaluation of Magnetic Resonance Spectroscopy data from human brain tumours and other abnormal brain masses.
Background
Proton Magnetic Resonance (MR) Spectroscopy (MRS) is a widely available technique for those clinical centres equipped with MR scanners. Unlike the rest of MR-based techniques, MRS yields not images but spectra of metabolites in the tissues. In pathological situations, the MRS profile changes and this has been particularly described for brain tumours. However, radiologists are frequently not familiar to the interpretation of MRS data and for this reason, the usefulness of decision-support systems (DSS) in MRS data analysis has been explored.
Results
This work presents the INTERPRET DSS version 3.0, analysing the improvements made from its first release in 2002. Version 3.0 is aimed to be a program that 1st, can be easily used with any new case from any MR scanner manufacturer and 2nd, improves the initial analysis capabilities of the first version. The main improvements are an embedded database, user accounts, more diagnostic discrimination capabilities and the possibility to analyse data acquired under additional data acquisition conditions. Other improvements include a customisable graphical user interface (GUI). Most diagnostic problems included have been addressed through a pattern-recognition based approach, in which classifiers based on linear discriminant analysis (LDA) were trained and tested.
Conclusions
The INTERPRET DSS 3.0 allows radiologists, medical physicists, biochemists or, generally speaking, any person with a minimum knowledge of what an MR spectrum is, to enter their own SV raw data, acquired at 1.5 T, and to analyse them. The system is expected to help in the categorisation of MR Spectra from abnormal brain masses
Efficacy of AAV serotypes to target Schwann cells after intrathecal and intravenous delivery
Diseases of the nervous system; Myelin biology and repair; Peripheral nervous systemEnfermedades del sistema nervioso; Biología y reparación de la mielina; Sistema nervioso periféricoMalalties del sistema nerviós; Biologia i reparació de la mielina; Sistema nerviós perifèricTo optimize gene delivery to myelinating Schwann cells we compared clinically relevant AAV serotypes and injection routes. AAV9 and AAVrh10 vectors expressing either EGFP or the neuropathy-associated gene GJB1/Connexin32 (Cx32) under a myelin specific promoter were injected intrathecally or intravenously in wild type and Gjb1-null mice, respectively. Vector biodistribution in lumbar roots and sciatic nerves was higher in AAVrh10 injected mice while EGFP and Cx32 expression rates and levels were similar between the two serotypes. A gradient of biodistribution away from the injection site was seen with both intrathecal and intravenous delivery, while similar expression rates were achieved despite higher vector amounts injected intravenously. Quantified immune cells in relevant tissues were similar to non-injected littermates. Overall, AAV9 and AAVrh10 efficiently transduce Schwann cells throughout the peripheral nervous system with both clinically relevant routes of administration, although AAV9 and intrathecal injection may offer a more efficient approach for treating demyelinating neuropathies.Generalitat de Catalunya, 2019FI_B2 00061, 2019FI_B2 00061, Fundació la Marató de TV3, 201607.10, Muscular Dystrophy Association, 603003
A Novel Semi-Supervised Methodology for Extracting Tumor Type-Specific MRS Sources in Human Brain Data
BackgroundThe clinical investigation of human brain tumors often starts with a non-invasive imaging study, providing information about the tumor extent and location, but little insight into the biochemistry of the analyzed tissue. Magnetic Resonance Spectroscopy can complement imaging by supplying a metabolic fingerprint of the tissue. This study analyzes single-voxel magnetic resonance spectra, which represent signal information in the frequency domain. Given that a single voxel may contain a heterogeneous mix of tissues, signal source identification is a relevant challenge for the problem of tumor type classification from the spectroscopic signal.Methodology/Principal FindingsNon-negative matrix factorization techniques have recently shown their potential for the identification of meaningful sources from brain tissue spectroscopy data. In this study, we use a convex variant of these methods that is capable of handling negatively-valued data and generating sources that can be interpreted as tumor class prototypes. A novel approach to convex non-negative matrix factorization is proposed, in which prior knowledge about class information is utilized in model optimization. Class-specific information is integrated into this semi-supervised process by setting the metric of a latent variable space where the matrix factorization is carried out. The reported experimental study comprises 196 cases from different tumor types drawn from two international, multi-center databases. The results indicate that the proposed approach outperforms a purely unsupervised process by achieving near perfect correlation of the extracted sources with the mean spectra of the tumor types. It also improves tissue type classification.Conclusions/SignificanceWe show that source extraction by unsupervised matrix factorization benefits from the integration of the available class information, so operating in a semi-supervised learning manner, for discriminative source identification and brain tumor labeling from single-voxel spectroscopy data. We are confident that the proposed methodology has wider applicability for biomedical signal processing
A machine learning pipeline for supporting differentiation of glioblastomas from single brain metastases
Machine learning has provided, over the last decades, tools for knowledge extraction in complex medical domains. Most of these tools, though, are ad hoc solutions and lack the systematic approach that would be required to become mainstream in medical practice. In this brief paper, we define a machine learning-based analysis pipeline for helping in a difficult problem in the field of neuro-oncology, namely the discrimination of brain glioblastomas from single brain metastases. This pipeline involves source extraction using k-Meansinitialized Convex Non-negative Matrix Factorization and a collection of classifiers, including Logistic Regression, Linear Discriminant Analysis, AdaBoost, and Random Forests
Characterization of clay minerals and Fe oxides through diffuse reflectance spectroscopy (VNIR-SWIR)
[ES] Se ha realizado el análisis mineralógico a través de las propiedades espectrales desarrolladas por muestras de suelos y sedimentos del borde noroccidental de la Cuenca del Duero. Las absorciones producidas por los óxidos y oxihidróxidos de hierro (hematites y goethita, principalmente) están localizadas en zonas del VNIR (400-1200 nm), mientras que las bandas de absorción presentes en los espectros del SWIR (1200-2500 nm) están relacionadas con la composición química de minerales arcillosos. Los espectros de reflectancia medidos en laboratorio han sido normalizados aplicando los métodos del Continuum Removal (CR) y la segunda derivada (SD). Este último puede resolver la superposición de bandas al cuantificar sutiles inflexiones de la curva. Esto ha permitido examinar las bandas de absorción por separado midiendo los parámetros geométricos desarrollados en ellas. La proporción de los minerales influye en la respuesta espectral y, por tanto, en los valores de los parámetros. Se han realizado correlaciones lineales entre estos valores y la proporción de las diferentes fases minerales obtenidas por difracción de rayos X. De los parámetros estudiados, la correlación entre la posición del centro de banda (BC) en la máxima absorción alrededor de longitudes de onda de 890-960 nm y la profundidad del rasgo de absorción a 470 nm (D470) ha permitido realizar una estimación relativa de la proporción de hematites/goethita. En cuanto a la distribución de los diferentes minerales de arcilla, se ha podido establecer una correlación entre la proporción de caolinita y la profundidad de las bandas de absorción a 1415 y 2210 nm, y en los rasgos de absorción cercanos a 1390 y 2160 nm, analizados en SD.[EN] The mineralogical analysis was carried out through the spectral properties developed by samples of soils and sediments from the northwestern edge of the Duero Basin. The absorptions produced by the oxides and Feoxyhydroxides (mainly hematite and goethite) are located in VNIR zones (400-1200 nm), while the absorption bands that are present in the SWIR spectra (1200-2500 nm) are related to the chemical composition of clay minerals. The reflectance spectra measured in the laboratory have been normalized by using the methods of Continuum Removal (CR) and the second derivative (SD). This last method can solve the band overlapping because it quantifies subtle drops in the curve. This has allowed the absorption bands to be examined separately by measurement of their geometrical parameters. The proportion of the minerals affects the spectral response and, accordingly, the values of the parameters. Linear correlations were conducted between these values and the proportion of the different mineral phases obtained by X-ray diffraction. In the studied parameters, the correlation between the band center (BC) position in the maximum absorption around the wavelengths at 890-960 nm and the absorption feature depth at 470 nm (D470) has enabled a relative estimation of the proportion of hematite/goethite. As for the distribution of the different clay minerals, a correlation has been established between the proportion of kaolinite and the absorption bands depth at 1415 and 2210 nm, and in the absorption features near 1390 and 2160 nm, analyzed in SD.Trabajo financiado por los Proyectos CGL2016-77005-R y ESP2017-89045-R del Ministerio de
Ciencia, Innovación y Universidades, y el ProyectoLE169G18 de la Junta de Castilla y León.Báscones, A.; Suárez, M.; Ferrer-Julià, M.; García-Meléndez, E.; Colmenero-Hidalgo, E.; Quirós, A. (2020). Caracterización de minerales de arcilla y óxidos de hierro mediante espectroscopía de reflectancia difusa (VNIR–SWIR). Revista de Teledetección. 0(55):49-57. https://doi.org/10.4995/raet.2020.13331OJS4957055Ben-Dor, E., Banin, A. 1995. Near-infrared analysis as a rapid method to simultaneously evaluate several soil properties. Soil Science Society of America Journal, 59(2), 364-37. https://doi.org/10.2136/ sssaj1995.03615995005900020014xBen-Dor, E. 2002. Quantitative remote sensing of soil properties. Advances in Agronomy, 75, 173-243. https://doi.org/10.1016/S0065-2113(02)75005-0Bishop, J.L., Lane, M.D., Dyar, M.D., Brown, A.J. 2008. Reflectance and emission spectroscopy study of four groups of phyllosilicates: smectites, kaolinite-serpentines, chlorites and micas. 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Relación entre la respuesta espectral (visible-infrarrojo cercano) y la composición mineralógica de materiales sedimentarios del borde occidental de la Cuenca del Duero. Rev. Soc. Geol. España, 17(1-2), 39-47.García-Rivas, J., Suárez, M., García-Romero, E., García-Meléndez, E. 2018. Identification and classification of mineralogical associations by VNIR-SWIR spectroscopy in the Tajo basin (Spain). International Journal of Applied Earth Observations and Geoinformation, 72, 57-65. https://doi.org/10.1016/j.jag.2018.05.028González Menéndez, L., Heredia, N., Marcos, A. 2008. Mapa Geológico Digital continuo E. 1:50000, Zona Asturoccidental-Leonesa (Zona-1100). En: GEODE. Mapa Geológico Digital continuo de España, Cartografía del IGME.Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L. y Klein, A.J. 2017. USGS Spectral Library Version 7. U.S. Geological Survey Data Series 1035, 61pp. https://doi.org/10.3133/ds1035Martín Pozas, J.M. 1975. Análisis cuantitativo de fases cristalinas por DRX. En: Difracción de muestras policristalinas. Método de Debye-Scherrer, J.A. Saja, ed., I.C.E. Universidad de Valladolid.Moore, D.M., Reynolds, R.C. 1997. X-ray diffraction and identification and analysis of clay minerals. 2nd Edition, Oxford University Press, New York.Pérez García, L.C. 1977. Los Sedimentos Auríferos del NO de la Cuenca del Duero (Provincia de León, España) y su Prospección. Tesis Doctoral, Universidad de Oviedo.Petit, S., Madejová, J., Decarreau, A., Martin, F. 1999. Characterization of octahedral substitutions in kaolinites using near Infrared spectroscopy. Clays and Clay Minerals, 47, 103-108. https://doi.org/10.1346/CCMN.1999.0470111Petit, S., Decarreau, A., Martin, F., Buchetet, R. 2004. Refined relationship between the position of the fundamental OH stretching and the first overtones for clays. Phys. Chem. 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Removal of 4-hydroxyphenylacetic acid from aqueous medium by electrochemical oxidation with a BDD anode: mineralization, kinetics and oxidation products
The degradation of 100 mL of solutions containing 4-hydroxyphenylacetic acid in 0.050 M Na2SO4 at pH 3.0 has been performed by anodic oxidation with electrogenerated H2O2 (AO-H2O2) using a stirred tank reactor equipped with a boron-doped diamond (BDD) anode and an air-diffusion cathode. An almost total mineralization with 95.5% total organic carbon (TOC) removal was achieved for a 1.03 mM substrate solution at 100 mA cm-2. The effect of current density between 16.7 and 100 mA cm-2 and 4-hydroxyphenylacetic acid content between 0.21 and 2.06 mM was examined. Greater current efficiency with lower specific energy consumption and smaller mineralization was found at low current density and high substrate concentration. The TOC abatement as well as the 4-hydroxyphenylacetic acid concentration decay obeyed a pseudo-first-order kinetics. The oxidation role of hydroxyl radical formed from water discharge at the BDD anode is explained on the basis of its electrogeneration rate and competitive wasting reactions. 4-Hydroxybenzenemethanol and its derivative 4-hydroxybenzenealdehyde were identified as primary aromatic by-products by gas chromatography-mass spectrometry. Ion-exclusion HPLC allowed the detection of low amounts of the persistent oxalic acid during the AO-H2O2 process. The remaining TOC in final electrolyzed solutions is related to the presence of a large proportion of unidentified by-products that are even more recalcitrant than common short-linear aliphatic carboxylic acids
EXPERIMENTAL EVIDENCE OF PHYSIOLOGICAL AND BEHAVIORAL EFFECTS OF MICROPLASTICS INGESTION IN SPARUS AURATA
Increasing global research has identified microplastics (MPs) to be impacting marine organisms. The present work aimed at investigating the physiological and behavioral effects of thirty-six juvenile Sparus aurata exposed to control, virgin and weathered MPs enriched diets during a 21-day period under controlled conditions. Physiological effects were assessed in liver and brain using the following biomarkers: activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd), the detoxifying enzyme glutathione S-transferase (GST) and malondialdehyde (MDA) as indicative of lipid peroxidation. Individuals were recorded for behavior analysis (i.e. social interactions and feeding behavior). Results revealed an increase in cellular stress from control to weathered fish groups, with the virgin group showing intermediate levels in all quantified biomarkers. Significant differences were found in the liver for all biomarkers except for MDA, suggesting that exposure time to MPs in this experiment is long enough to trigger the activation of antioxidant enzymes but not to produce cell damage by lipid peroxidation. In brain tissue samples, fish from the weathered group presented significantly higher values for CAT and SOD, highlighting its function as primary antioxidants. Regarding behavioral effects, results showed that the two MPs enriched groups were significantly bolder during social interactions and, although no significantly, tended to be more active during feeding. In conclusion, MPs which have been weathered in marine environmental conditions produces a higher physiological response than virgin MPs but also, a physiological response is variable depending on the tissue analyzed. In addition, a short period to MP exposure seems to affect overall social and feeding behavior but, further research is needed to assess long-term effects of MP ingestion and its potential consequences on fish populations
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