3,008 research outputs found

    Towards the technological maturity of membrane distillation: the MD module performance curve

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    Membrane distillation (MD) is constantly acknowledged in the research literature as a promising technology for the future of desalination, with an increasing number of studies reported year after year. However, real MD applications still lag behind with only a few pilot-plant tests worldwide. The lack of technology transfer from academia to industry is caused by important gaps between its fundamental basis and the process design. Herein, we explore critical disconnections by conducting coupled mass and heat transfer modeling and MD simulations; we use well-known MD mass and heat transfer equations to model and simulate flux over a typical MD membrane for different geometries, areas, and operational conditions in direct contact configuration. From the analysis of the results, we propose research guidelines and process development strategies, and construct an MD module performance curve. From this graph, permeate flow rate, thermal energy consumption and outlet temperatures can be determined for given feed inlet conditions (temperature and concentration). Comprehensive tools such as this MD module curve and good communication between membrane developers and process engineers are required to accelerate the process of bringing the MD technology from a still-emerging status to a maturity level

    Modelling soil water dynamics of full and deficit drip irrigated maize cultivated under a rain shelter

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    Research PaperThe model HYDRUS-1D was used to simulate soil water dynamics of full and deficit irrigated maize grown under a rainout shelter during two crop seasons. Four irrigation treatments were established based on the amount of water applied to fulfil crop water requirements. Treatment D1 was irrigated to fully satisfy crop water requirements, while treatments D2 (mild deficit), D3 (moderate deficit), and D4 (severe deficit) were for increased controlled water stress conditions. The computation and partitioning of evapotranspiration data into soil evaporation and crop transpiration was carried out with the SIMDualKc model, and then used with HYDRUS-1D. The soil hydraulic properties were determined from numerical inversion of field water content data. The compensated root water uptake mechanism was used to describe water removal by plants. TheHYDRUS-1D model successfully simulated the temporal variability of soil water dynamics in treatments irrigated with full and deficit irrigation, producing RMSE values that varied between 0.014 and 0.025 cm3 cm 3 when comparing model simulations with field measurements. Actual transpiration varied between 224 and 483 mm. Potential transpiration reductions varied from 0.4 to 48.8% due to water stress, but plants were able to compensate for the water deficits in the surface layers by removing more water from the deeper, less stressed layers. HYDRUS-1D water balance estimates were also comparable with the corresponding ones determined with the SIMDualKc water balance model. Both modelling approaches should contribute to improve the webbased IRRIGA system, used to support farm irrigation scheduling in Brazilinfo:eu-repo/semantics/publishedVersio

    Computational Prediction of Potential Inhibitors of the Main Protease of SARS-CoV-2

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    The rapidly developing pandemic, known as coronavirus disease 2019 (COVID-19) and caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has recently spread across 213 countries and territories. This pandemic is a dire public health threat-particularly for those suffering from hypertension, cardiovascular diseases, pulmonary diseases, or diabetes; without approved treatments, it is likely to persist or recur. To facilitate the rapid discovery of inhibitors with clinical potential, we have applied ligand- and structure-based computational approaches to develop a virtual screening methodology that allows us to predict potential inhibitors. In this work, virtual screening was performed against two natural products databases, Super Natural II and Traditional Chinese Medicine. Additionally, we have used an integrated drug repurposing approach to computationally identify potential inhibitors of the main protease of SARS-CoV-2 in databases of drugs (both approved and withdrawn). Roughly 360,000 compounds were screened using various molecular fingerprints and molecular docking methods; of these, 80 docked compounds were evaluated in detail, and the 12 best hits from four datasets were further inspected via molecular dynamics simulations. Finally, toxicity and cytochrome inhibition profiles were computationally analyzed for the selected candidate compounds

    The Dusty Tori of Nearby QSOs as Constrained by High-Resolution Mid-IR Observations

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    We present mid-infrared (MIR; 7.5–13.5 μm) imaging and spectroscopy observations obtained with the CanariCam (CC) instrument on the 10.4-m Gran Telescopio CANARIAS for a sample of 20 nearby, MIR bright and X-ray luminous quasi-stellar objects (QSOs). We find that for the majority of QSOs the MIR emission is unresolved at angular scales ∼0.3 arcsec, corresponding to physical scales ≲ 600 pc. We find that the higher-spatial resolution CC spectra have similar shapes to those obtained with Spitzer/IRS, and hence we can assume that the spectra are not heavily contaminated by extended emission in the host galaxy. We thus take advantage of the higher signal-to-noise ratio Spitzer/IRS spectra, as a fair representation of the nuclear emission, to decompose it into a combination of active galactic nuclei (AGN), polycyclic aromatic hydrocarbon (PAH) and stellar components. In most cases, the AGN is the dominant component, with a median contribution of 85 per cent of the continuum light at MIR (5–15 μm) within the IRS slit. This IR AGN emission is well reproduced by clumpy torus models. We find evidence for significant differences in the parameters that describe the dusty tori of QSOs when compared with the same parameters of Seyfert 1 and 2 nuclei. In particular, we find a lower number of clouds (N0 ≲ 12), steeper radial distribution of clouds (q ∼ 1.5–3.0) and clouds that are less optically thick (τV ≲ 100) than in Seyfert 1, which could be attributed to dusty structures that have been partially evaporated and piled up by the higher radiation field in QSOs. We find that the combination of the angular width σtorus, viewing angle i, and number of clouds along the equatorial line, N0, produces large escape probabilities (Pesc \u3e 2 per cent) and low geometrical covering factors (f2 ≲ 0.6), as expected for AGN with broad lines in their optical spectra

    A deep look at the nuclear region of UGC 5101 through high angular resolution mid-IR data with GTC/CanariCam

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    We present an analysis of the nuclear infrared (IR, 1.6–18 μm) emission of the ultraluminous IR galaxy UGC 5101 to derive the properties of its active galactic nucleus (AGN) and its obscuring material. We use new mid-IR high angular resolution (0.3–0.5 arcsec) imaging using the Si-2 filter (λ_C = 8.7 μm) and 7.5–13 μm spectroscopy taken with CanariCam (CC) on the 10.4 m Gran Telescopio CANARIAS. We also use archival Hubble Space Telescope/NICMOS and Subaru/COMICS imaging and Spitzer/IRS spectroscopy. We estimate the near- and mid-IR unresolved nuclear emission by modelling the imaging data with GALFIT. We decompose the Spitzer/IRS and CC spectra using a power-law component, which represents the emission due to dust heated by the AGN, and a starburst component, both affected by foreground extinction. We model the resulting unresolved near- and mid-IR, and the starburst subtracted CC spectrum with the CLUMPY torus models of Nenkova et al. The derived geometrical properties of the torus, including the large covering factor and the high foreground extinction needed to reproduce the deep 9.7 μm silicate feature, are consistent with the lack of strong AGN signatures in the optical. We derive an AGN bolometric luminosity L_(bo)l ∼ 1.9 × 10^(45) erg s^(−1) that is in good agreement with other estimates in the literature

    A Deep Look at the Nuclear Region of UGC 5101 Through High Angular Resolution Mid-IR Data with GTC/CanariCam

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    We present an analysis of the nuclear infrared (IR, 1.6–18 μm) emission of the ultraluminous IR galaxy UGC 5101 to derive the properties of its active galactic nucleus (AGN) and its obscuring material. We use new mid-IR high angular resolution (0.3–0.5 arcsec) imaging using the Si-2 filter (λC = 8.7 μm) and 7.5–13 μm spectroscopy taken with CanariCam (CC) on the 10.4 m Gran Telescopio CANARIAS. We also use archival Hubble Space Telescope/NICMOS and Subaru/COMICS imaging and Spitzer/IRS spectroscopy. We estimate the near- and mid-IR unresolved nuclear emission by modelling the imaging data with GALFIT. We decompose the Spitzer/IRS and CC spectra using a power-law component, which represents the emission due to dust heated by the AGN, and a starburst component, both affected by foreground extinction. We model the resulting unresolved near- and mid-IR, and the starburst subtracted CC spectrum with the CLUMPY torus models of Nenkova et al. The derived geometrical properties of the torus, including the large covering factor and the high foreground extinction needed to reproduce the deep 9.7 μm silicate feature, are consistent with the lack of strong AGN signatures in the optical. We derive an AGN bolometric luminosity Lbol ~ 1.9 × 1045 erg s−1 that is in good agreement with other estimates in the literature

    Spatio temporal and climatic analysis of the high Andean wetland of Chalhuanca (Peru) during the period 1986-2016

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    [ES] Los humedales altoandinos son considerados ecosistemas frágiles que proporcionan servicios ecosistémicos para el mantenimiento de la biodiversidad y economía andina, sin embargo, actualmente la amenaza global del cambio climático los pone en grave riesgo, es por ello que el objetivo de este estudio es determinar la variación espacio temporal y climática del humedal altoandino de Chalhuanca (Perú), durante el periodo 1986-2016. Se obtuvieron escenas Landsat de la temporada seca de los años 1986, 1991, 1996, 2001, 2006, 2011, 2016 y mediante técnicas de teledetección se calculó el área y el índice de vegetación (NDVI) de los humedales. Para la precipitación, temperatura máxima y temperatura mínima, se realizó un análisis de medias móviles, tendencias lineales y se aplicó la prueba estadística no paramétrica de Mann-Kendall, finalmente mediante correlación y regresión se evaluó la interacción entre las variables. Los resultados muestran que el área de humedal se ha incrementado en razón de 12 ha/año. En cuanto al NDVI, se ha detectado un incremento de los valores promedio para el periodo evaluado, siendo 0,26 el umbral (promedio de valores mínimos). El análisis de los datos climáticos muestra que la precipitación, temperatura máxima y mínima se han incrementado en 32  mm/dec, 0,3  °C/dec y 0,6  °C/dec respectivamente, siendo significativos (α<0,05) la temperatura máxima y mínima. Por último, los análisis de correlación y regresión muestran que la relación área de humedal-precipitación, NDVI-precipitación y área de humedal-NDVI son significativas para α<0,01, en cambio, la relación área de humedal-temperatura y NDVI-temperatura fueron significativos para α<0,05.[EN] The high Andean wetlands are considered fragile ecosystems that provide ecosystem services for the maintenance of Andean biodiversity and economy. However, currently the global threat of climate change puts them at serious risk, which is why the objective of this study is to determine the spatial-temporal and climatic variation of the high Andean wetlands of Chalhuanca (Peru), during the period 1986-2016. Landsat scenes were obtained during dry season in the years 1986, 1991, 1996, 2001, 2006, 2011, 2016, and using remote sensing techniques the area and vegetation index (NDVI) of the wetlands were calculated. For precipitation, maximum and minimum temperature, an analysis of moving averages, linear trends and the Mann-Kendall non-parametric statistical test was carried out, and finally the interaction between the variables was evaluated by using correlation and regression. The results show that the wetland area has increased by 12 ha/year. As for the NDVI, an increase of the average values for the evaluated period has been detected, being 0.26 the average of minimum values. Analysis of climate data shows that precipitation, maximum and minimum temperature have increased by 32 mm/dec, 0.3 °C/dec and 0.6 °C/dec respectively, with the maximum and minimum temperature being significant (α<0.05). Finally, correlation and regression analyses show that the wetland area-precipitation, NDVI-precipitation and wetland-NDVI relationships are significant for α<0.01, while the wetland-temperature and NDVI-temperature relationships were significant for α<0.05.Esta investigación fue financiada por la Universidad Nacional de San Agustín de Arequipa (UNSA) por contrato N° 047-2016-UNSA dentro del proyecto: “Servicios ecosistémicos de los humedales altoandinos y su contribución en la mitigación de los efectos del cambio climático: estudio de caso”, según contrato de subvención, también, se agradece al Tambo Chalhuanca (Programa Nacional PAIS – Midis), a los pobladores de la localidad de Chalhuanca y a la jefatura de la Reserva Nacional de Salinas y Aguada Blanca (Res. Jef. 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The influence of climate change on recent peat accumulation patterns of Distichia muscoides cushion bogs in the high-elevation tropical Andes of Colombia. Journal of Geophysical Research: Biogeosciences, 118(4), 1627-1635. https://doi.org/10.1002/2013JG002419Berlanga, C., García, R., López, J., Ruiz, A. 2010. Patrones de cambio de coberturas y usos del suelo en la región costa norte de Nayarit (1973-2000). Investigaciones Geográficas, 72, 7-22.Castino, F., Bookhagenl, B., Strecker, M. R. 2017. Rainfall variability and trends of the past six decades (1950-2014) in the subtropical NW Argentine Andes. Climate Dynamics, 48(3-4), 1049-1067. https://doi.org/10.1007/s00382-016-3127-2Congalton R.G. 1991. A review of assessing the accuracy of classifications of remotely sensed data. Remote Sensing of Environment, 37, 35-46. https://doi.org/10.1016/0034-4257(91)90048-BDangles, O., Rabatel, A., Kraemer, M., Zevallos, G., Soruco, A., Jacobsen, D., Anthelme, M. 2017. Ecosystem sentinels for climate change? Evidence of wetland cover changes over the last 30 years in the tropical Andes. Plos One, 12(5). e0175814. https://doi.org/10.1371/journal.pone.0175814Dong, Z., Wang, Z., Liu, D., Song, K., Li, L., Jia, M., Ding, Z. 2014. Mapping Wetland Areas Using Landsat-Derived NDVI and LSWI: A Case Study of West Songnen Plain, Northeast China. Journal of the Indian Society of Remote Sensing, 42(3), 569-576. https://doi.org/10.1007/s12524-013-0357-1ENVI - Environment for Visualizing Images v5.3. 2019. Harris Geospatial Solutions. Recuperado en setiembre de 2019, disponible en: https://www.harrisgeospatial.com/Estrada, F., Barba, E., Ramos, R. 2013. Cobertura Temporal de los Humedales en la Cuenca del Usumacinta, Balancán, Tabasco, México. Universidad y Ciencia, 29(2), 141-151.García, E., Lleellish, M. 2012. Cartografiado de bofedales usando imágenes de satélite Landsat en una cuenca altoandina del Perú. Revista de Teledetección, 38, 92-118. 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Estudio de bofedales en los Andes ecuatorianos a través de la comparación de imágenes Landsat-8 y Sentinel-2. Revista de teledetección, 53, 45-57. https://doi.org/10.4995/raet.2019.11715Jaramillo, U., Cortés, J., Flórez, C. 2015. Colombia Anfibia. Un país de humedales. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humbolt.Kendall, M.G. 1975. Kendall Rank Correlation Methods. London: Griffin.Larsen, T., Brehm, G., Navarrete, H., Franco, P., Gómez, H., Mena, J., Morales, V., Argollo, J., Blacutt, L., Canhos, V. 2011. Desplazamientos de los rangos de distribución y extinciones impulsados por el cambio climático en los Andes tropicales: síntesis y orientaciones. En Herzog, S., Martínez, R., Jorgensen, P. y Tiessen, H. (Eds.), Cambio climático y biodiversidad en los Andes tropicales (pp. 57-82). Inter-American Institute for Global Change Research (IAI) and Scientific Committee on Problems of the Environment (SCOPE).Mann, H.B. 1945. Non parametric test against trend. Econometrica, 13, 245-259. https://doi.org/10.2307/1907187Maldonado-Fonkén, M. 2014. An introduction to the bofedales of the peruvian high Andes. Mires and Peat, 15(4), 1-13.Marengo, J., Pabón, J., Díaz, A., Rosas, G., Avalos, G., Montealegre, E., Villacís M., Solman S. M., Rojas, M. 2011. Cambio climático: evidencias y futuros escenarios en la región andina. En Herzog, S., Martínez, R., Jorgensen, P. y Tiessen, H. (Eds.), Cambio climático y biodiversidad en los Andes tropicales (pp. 131-150). Inter-American Institute for Global Change Research (IAI) and Scientific Committee on Problems of the Environment (SCOPE).Martínez, A., Rodríguez, J., Cabrera, A. 2014. Los paisajes de humedales, marco conceptual y aspectos metodológicos para su estudio y ordenamiento. Mercator (Fortaleza), 13(2), 169- 161. https://doi.org/10.4215/RM2014.1302.0012Mazzarino, M., Finn, J. T. 2015. An NDVI analysis of vegetation trends in an Andean watershed. Wetlands Ecology and Management, 24, 623-640. https://doi.org/10.1007/s11273-016-9492-0Medina, G., Mejía, A. 2014. Análisis multitemporal y multifractal de la desglaciación de la cordillera Parón en los Andes de Perú. Ecología Aplicada, 13(1), 35-42. https://doi.org/10.21704/rea.v13i1-2.452Mitsch, W., Gosselink, J. 2015. Wetlands. New Jersey: John Wiley y Sons, Inc.Mwita, E., Menz, G., Misana, S., Becker, M., Kisanga, D., Boehme, B. 2013. Mapping small wetlands of Kenya and Tanzania using remote sensing techniques. International Journal of Applied Earth Observation and Geoinformation, 21, 173-183. https://doi.org/10.1016/j.jag.2012.08.010Oñate-Valdivieso, F., Bosque, J. 2011. Estudio de tendencias climáticas y generación de escenarios regionales de cambio climático en una cuenca hidrográfica binacional en América del Sur. Estudios Geográficos, 270(27), 147-172. https://doi.org/10.3989/estgeogr.201107Otto, M., Schreder, D., Richters, J. 2011. Hydrology differentiation and spatial distribution of high altitude wetlands in a semi-arid Andean region derived from satellite data. Hydrology Earth System Science, 15, 1713-1727. https://doi.org/10.5194/hess-15-1713-2011Ozesmi, S.L., Bauer, M.E. 2002. Satellite remote sensing of wetlands. Wetland Ecology and Management, 10(5), 381-402. https://doi.org/10.1023/A:1020908432489Parra, A. Hernández, T., Francisco, L. 2010. Identificación y delimitación de humedales lénticos en el valle alto del río cauca mediante el procesamiento digital de imágenes de satélite. Ingeniería de Recursos Naturales y del Ambiente, 9, 78-88.Pekel, J.F., Cottam, A., Gorelick, N., Belward, A.S. 2016. High-resolution mapping of global surface water and its long-term changes. Nature, 540, 418- 422. https://doi.org/10.1038/nature20584Pérez, M., Llorca, J., Sanz, J. 2007. Evolución de la temperatura superficial desde el siglo XVIII. 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Mean annual temperature trends and their vertical structure in the tropical Andes. Geophysical Research Letters, 27, 3885-3888. https://doi.org/10.1029/2000GL011871Vuille, M., Bradley, R., Werner, M., Keiming, F. 2003. 20th century climate change in the tropical Andes: observations and model results. Climatic Change, 59, 75-99. https://doi.org/10.1023/A:1024406427519Vuille, M., Keimig, F. 2004. Interannual variability of summertime convective cloudiness and precipitation in the central Andes derived from ISCCP-B3 data. Journal of Climatology, 17, 3334-3348. https://doi.org/10.1175/1520-0442(2004)0172.0.CO;2Vuille, M. 2013. Climate Change and Water Resources in the Tropical Andes. Banco Interamericano de Desarrollo Unidad de Salvaguardias Ambientales. Nota técnica: No. IDB-TN-515.Vuille, M., Franquist, E., Garreaud, R., Casimiro, W., Cáceres, B. 2015. Impact of the global warming hiatus on Andean temperature. 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    CD4 cell count and the risk of AIDS or death in HIV-Infected adults on combination antiretroviral therapy with a suppressed viral load: a longitudinal cohort study from COHERE.

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    BACKGROUND: Most adults infected with HIV achieve viral suppression within a year of starting combination antiretroviral therapy (cART). It is important to understand the risk of AIDS events or death for patients with a suppressed viral load. METHODS AND FINDINGS: Using data from the Collaboration of Observational HIV Epidemiological Research Europe (2010 merger), we assessed the risk of a new AIDS-defining event or death in successfully treated patients. We accumulated episodes of viral suppression for each patient while on cART, each episode beginning with the second of two consecutive plasma viral load measurements 500 copies/µl, the first of two consecutive measurements between 50-500 copies/µl, cART interruption or administrative censoring. We used stratified multivariate Cox models to estimate the association between time updated CD4 cell count and a new AIDS event or death or death alone. 75,336 patients contributed 104,265 suppression episodes and were suppressed while on cART for a median 2.7 years. The mortality rate was 4.8 per 1,000 years of viral suppression. A higher CD4 cell count was always associated with a reduced risk of a new AIDS event or death; with a hazard ratio per 100 cells/µl (95% CI) of: 0.35 (0.30-0.40) for counts <200 cells/µl, 0.81 (0.71-0.92) for counts 200 to <350 cells/µl, 0.74 (0.66-0.83) for counts 350 to <500 cells/µl, and 0.96 (0.92-0.99) for counts ≥500 cells/µl. A higher CD4 cell count became even more beneficial over time for patients with CD4 cell counts <200 cells/µl. CONCLUSIONS: Despite the low mortality rate, the risk of a new AIDS event or death follows a CD4 cell count gradient in patients with viral suppression. A higher CD4 cell count was associated with the greatest benefit for patients with a CD4 cell count <200 cells/µl but still some slight benefit for those with a CD4 cell count ≥500 cells/µl

    Cretaceous intraplate contraction in Southern Patagonia: A far-field response to changing subduction dynamics?

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    The origin, extent, and timing of intraplate contraction in Patagonia are among the least understood geological processes of southern South America. Particularly, the intraplate Deseado fold-thrust belt (FTB), located in the Patagonian broken foreland (47°–48°300 S), is one of the most enigmatic areas. In this belt, time constraints on tectonic events are limited and synorogenic deposits have not been documented so far. Furthermore, the driving mechanism for intraplate contraction remains unknown. In this study, we carried out a structural and sedimentological analysis. We report the first syntectonic deposits in this area in the Baqueró (Aptian) and Chubut (Cenomanian/Campanian) groups and a newly found unit referred to as the Albian beds (109.9 ± 1.5 Ma). Thus, several contractional stages in late Aptian, Albian, and Cenomanian-Campanian are then inferred. We suggest that the Deseado FTB constituted the southernmost expression of the early Patagonian broken foreland in Cretaceous times. Additionally, we analyzed the spatiotemporal magmatic arc behavior as a proxy of dynamic changes in the Andean subduction during determined stages of intraplate contraction. We observe a significant arc broadening from ~121 to 82 Myr and magmatic quiescence after ~67 Ma. This is interpreted as a slab shallowing to flattening process. Far-field tectonic forces would have been produced by increased plate coupling linked to the slab flattening as indirectly indicated by the correlation between Cretaceous arc expansion and intraplate contraction. Finally, the tectonic evolution of the Deseado FTB favors studies supporting inception of Andean shortening since Cretaceous times.Fil: Gianni, Guido Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; ArgentinaFil: Navarrete Granzotto, César Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Liendo, Ingrid Florencia. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Díaz, Marianela Ximena Yasmin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geología; ArgentinaFil: Gimenez, Mario Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; ArgentinaFil: Encinas, Alfonso. Universidad de Concepción; ChileFil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentin
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