77 research outputs found

    Arte y astrología en Salamanca a finales del siglo XV

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    Las Tabulae ad meridianum Salamantinum que se conservan en la Bodleian Library de Oxford (ms. Can. Misc. 27) constituyen una compilación de tablas astronómicas realizada hacia 1460 para uso de los estudiantes de la cátedra de astronomía de la Universidad de Salamanca. Sus ilustraciones son una versión gótica de la habitual iconografía islámica de los signos del zodiaco, distinta de la que representan las pinturas de Fernando Gallego para la Biblioteca de la Universidad de Salamanca (hoy en las Escuelas menores). La iconografía de esta bóveda astrológica, que conmemora la fundación de la biblioteca, auna dos tradiciones astrológicas occidentales: una iconografía planetaria cuyo origen se halla en ciertos grabados florentinos conocidos como "Planetas Finiguerra", y una iconografía de las constelaciones derivada en último término de las ilustraciones del Liber introductorius de Miguel Escoto. La conjunción de ambas tradiciones se realizó por primera vez en los grabados de la primera edición ilustrada del Poeticon astronomicon de Higino (Venecia: Erhardt Ratdolt, 1482). El profesor Santiago Sebastián postuló una edición de 1485 de la obra de Higino como fuente de las pinturas salmantinas, y ello no sin juiciosas reservas, a pesar de las cuales la historiografía posterior ha tomado este dato como elemer¡to de precisión cronológica. Varios incunables de la década de 1480 retoman las figuras de la edición de Ratdolt total o parcialmente, pero una comparación detallada (que se ofrece en apéndice) demuestra que ninguna de las ediciones citadas coincide plenamente con las figuras de Fernando Gallego. En la Baja Edad Media se trató de lograr un siempre inestable equilibrio entre astrología y cristianismo. La astrología natural (con fines básicamente médicos), tolerada por la Iglesia, se convirtió en parte del currículum académico. La bóveda astrológica de la biblioteca salmantina pretendía expresar en términos figurativos el sentido exegético conferido en la época al versículo del Salmo VIII inscrito en su banda inferior ("... videbo celos tuos... "): que la contemplación científica del cielo no debe hacer olvidar que las maravillas que en él se contemplan no proceden sino de Dios

    La cultura visual de la magia en la época de Alfonso X

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    Fundación Séneca de Murcia (Agencia Regional de Ciencia y Tecnología) 00680/PI/04MEC-FEDER HUM2005-0687

    Paleohydrological dynamics in the Western Mediterranean during the last glacial cycle

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    This study was supported by the project B-RNM-144-UGR18 of the action "Proyectos I+D+i del Programa Operativo FEDER 2018 -Junta de Andalucia-UGR", the projects CGL2013-47038-R and CGL201785415-R, of the "Ministerio de Economia y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER", and the research group RNM-190 (Junta de Andalucia). A.G.-A. was also supported by a Marie Curie Intra-European Fellowship of the 7th Framework Programme for Research, Technological Development and Demonstration of the European Commission (NAOSIPUK. Grant Number: PIEF-GA-2012-623027) and by a Ram ' on y Cajal Fellowship RYC-2015-18966 of the Spanish Government (Ministerio de Economia y Competividad). J.C. acknowledges the postdoctoral funding provided by the Academy of Finland (project number 316702). J.L.T. hosted the NAOSIPUK project (PIEFGA-2012-623027) at the University of Glasgow. A.L.-A PhD is funded by BES-2018-084293 (Ministerio de Economia y Competividad). M.J.R.R. acknowledges the postdoctoral funding by the European Research Council (ERC-2017-ADG-788616). This study was supported by an ERC Consolidator Grant (STEEPclim) to D.S. (Grant Agreement No. 647035). E.S. is supported by the DFG Cluster of Excellence 2077 >The Ocean Floor -Earth's Uncharted Interface < at MARUM. We thank Ralph Kreutz for analytical support.The transitional regions between the low and high latitudes of the Northern Hemisphere are highly vulnerable to future climate change yet most of the current climate models usually diverge in their projections. To better understand the dynamics in these regions, the reconstruction of past hydrological fluctuations and precipitation patterns is of paramount importance to accurately constrain present and future climate scenarios. In this study, we investigated paleohydrological dynamics in the western Mediterranean region, a transitional zone between low-mid latitudes and Atlantic - Mediterranean realms. We reconstruct precipitation and moisture source changes during the last -35 ka in order to propose the potential mechanisms driving these oscillations. To do so, we use hydrogen isotopes from sedimentary leaf waxes, more specifically the C31 n-alkane homologue, and a precipitation proxy based on previously published pollen data from a sedimentary core (Padul-15-05) in southern Iberia (Padul wetland -37-N). With this combination we disentangle the coupled effect of precipitation amount and source on the hydrogen isotopic signature of the studied C31 n-alkane record. Our results show three main periods characterized by different precipitation patterns. Low precipitation, mainly linked to a significant contribution from an isotopically-enriched Mediterranean precipitation source, occurred from -30 to -15.5 ka BP and during the last -5 ka, whereas enhanced precipitation with a predominant isotopically-depleted Atlantic precipitation source prevailed from -15.5 to -5 ka BP. This latter stage is here defined as the Western Mediterranean Humid Period (WMHP). In addition, some occasional millennial-scale opposite precipitation patterns can be observed during these climatically distinct periods. These changes in the source of precipitation were likely coupled to a shift in the main rainy season from winter, when Atlantic precipitation prevailed, to late winter-early spring, when the contribution of Mediterranean moisture is higher. Comparison between the studied mid-latitude terrestrial Padul-15-05 core and a low-latitude marine record offshore of northwestern Africa shows clear long-term synchronous responses of both western Mediterranean precipitation and western African monsoon systems to northern Hemisphere atmospheric dynamics, ultimately controlled by orbital forcing and ice-sheets fluctuations.action "Proyectos I+D+i del Programa Operativo FEDER 2018 -Junta de Andalucia-UGR" B-RNM-144-UGR18Ministerio de Economia y Competitividad of Spain CGL2013-47038-R CGL201785415-RJunta de Andalucia RNM-190Marie Curie Intra-European Fellowship of the 7th Framework Programme for Research, Technological Development and Demonstration of the European Commission (NAOSIPUK) PIEF-GA-2012-623027Spanish Government (Ministerio de Economia y Competividad) RYC-2015-18966Academy of FinlandEuropean Commission 316702NAOSIPUK project at the University of Glasgow PIEFGA-2012-623027Ministerio de Economia y Competividad BES-2018-084293European Research Council (ERC)European Commission ERC-2017-ADG-788616ERC Consolidator Grant (STEEPclim) 647035DFG Cluster of Excellence 2077 >The Ocean Floor -Earth's Uncharted Interface < at MARUMEuropean Commissio

    Climatic control on the Holocene hydrology of a playa-lake system in the western Mediterranean

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    This study was supported by the action "Proyectos I + D + i del Programa Operativo FEDER 2018-Junta de Andalucia-UGR"& nbsp;[grant number B-RNM-144-UGR] , the Spanish Government (Ministerio de Economia y Competividad) and the European Regional Development Fund (ERDF-FEDER) [grant numbers CGL2013-47038-R and CGL2017- 85415-R] , and the Junta de Andalusia [grant numbers P18-RT-871 and Retos P20_00059, and research group RNM-190] . A.G.-A. was supported by a Ramon y Cajal Fellowship RYC of the Spanish Government (Ministerio de Economia y Competividad) [grant number 2015-18966] . A.L.-A PhD was funded by a fellowship of the Spanish Government (Ministerio de Economia y Competividad) [grant number BES-2018-084293] . F.G was financially supported by a Ramon y Cajal Fellowship (RYC2020-029811-I) of the Spanish Government (Ministerio de Economia y Competividad) . The Open Access Publication Charge was funded by the University of Granada/CBUA.Evaporitic lakes such as playa-lakes are characteristic of many arid regions and are unique environments with respect to fauna and flora, while being very vulnerable to climate and environmental fluctuations and threatened by the current global change scenario. Water balance oscillations in these systems can trigger the precipitation or dissolution of different evaporitic minerals, negatively impacting local biodiversity and economic activities. Here, we study the sedimentary record of a small saline pond from a playa-lake complex in southwestern Iberia in order to reconstruct the paleohydrological evolution of this area and assess potential anthropogenic disturbances. The different proxies studied in the ~11.9 ky old sedimentary record of the Laguna de la Ballestera suggest that the greatest lake extension and the highest water levels occurred during the Early Holocene, pointing to the wettest period of the record. Climate transitioned towards more arid conditions during the Middle Holocene, and even more dramatically during the Late Holocene. In this last stage the wetland surface and the water level largely diminished and gypsum precipitation gradually increased pointing towards a negative precipitation/ evapotranspiration balance and lowest water levels. Summer desiccation likely occurred under this scenario, especially after ~1.0–0.9 cal ky BP coeval with the Medieval Climate Anomaly, when gypsum content started to rise abruptly. However, this significant gypsum precipitation was only associated with a massive drop in the siliciclastic content and scarce carbonates (dolomite and calcite) during the last ~400 years. This evidence suggests a shift from a (semi) permanent to a temporal/seasonal hydrological regime. The environmental evolution of this wetland responded to the general climatic evolution of the western Mediterranean during the Holocene, being mostly controlled by changes in insolation. Our data also show that the environmental response of the studied wetland to natural climate variations was only significantly disturbed by human activities since the 20th century, especially in the second half of the century, deduced by abrupt fluctuations in the siliciclastic, gypsum and organic content in the sediments, as well as by the enhanced sedimentary accumulation rates, probably as a response to changes in the hydroperiod of the lake and in the catchment land use.Spanish Government B-RNM-144-UGRProyectos I + D + i del Programa Operativo FEDER 2018-Junta de Andalucia-UGR B-RNM-144-UGRSpanish Government RNM-190European Commission B-RNM-144-UGR BES-2018-084293Junta de Andalusia CGL2013-47038-R CGL2017- 85415-R P18-RT-871Ramon y Cajal Fellowship RYC of the Spanish Government (Ministerio de Economia y Competividad) Retos P20_00059 2015-18966University of Granada/CBUA RYC 2020-029811-

    Photo-Oxidation of Glycerol Catalyzed by Cu/TiO2

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    In the present study, glycerol was oxidized by photocatalysis to glyceraldehyde, formaldehyde, and formic acid. Copper-doped TiO2 was synthesized by the evaporation-induced self-assembly approach and it was used as catalyst during the glycerol photo-oxidation reactions. The prepared mesoporous material exhibited high specific surface area (242 m2/g) and band gap energy reduction of 2.55 eV compared to pure titania (3.2 eV) by the synthesis method due to the presence of copper cations (Cu2+ identified by XPS). The catalyst showed only anatase crystalline phase with nanocrystals around 8 nm and irregular agglomerates below 100  m. The selectivity and formation rate of the products were favored towards formaldehyde and glyceraldehyde. The variables studied were catalyst amount, reaction temperature, and initial glycerol concentration. The response surface analysis was used to evaluate the effect of the variables on the product’s concentration. A higher selectivity towards formaldehyde was observed when visible light was used as the radiation source. This study is useful to evaluate the best reaction conditions towards value-added products during the oxidation of glycerol by photocatalysis using Cu/TiO2.COMECYT–Mexico (CAT2021-0032) UAEMex (6518/2022CIB

    Laguna Seca sediments reveal environmental and climate change during the latest Pleistocene and Holocene in Sierra Nevada, southern Iberian Peninsula

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    This study was supported by the I + D + i projects CGL2013-47038- R, CGL2017-85415-R, PID2019-1049449GB-I00, and PID2021- 125619OB-C21/C22 funded by Ministerio Ciencia e Innovación/Agencia Estatal de Investigación/ 10.13039/501100011033/ and Fondo Europeo de Desarrollo Regional “Una manera de hacer Europa”, I + D + i projects A-RNM-336-UGR20 and P20_00059 of the action “Proyectos I + D + i del Programa Operativo FEDER - Junta de Andalucía - UGR” and the research group RNM-190. This research is part of the project “Thematic Center on Mountain Ecosystem & Remote sensing, Deep learning- AI e-Services University of Granada-Sierra Nevada” (LifeWatch-2019- 10-UGR-01), which has been co-funded by the Ministry of Science and Innovation through the FEDER funds from the Spanish Pluriregional Operational Program 2014-2020 (POPE), LifeWatch-ERIC action line. José Carrión was supported by the I + D + I project PID2019-1049449 GB-I00 funded by MCIN/AEI/ 10.13039/501100011033/ and FEDER “Una manera de hacer Europa” and the fellowship 20788/PI/18 of Fundación Séneca. We thank Javier Jaimez for his help with the core drilling in Laguna Seca and Alejandro Navarro and Aurora Baquera for the sediment sampling. ALA acknowledges the predoctoral fellowship BES- 2018-084293 provide by the MCIN/ AEI/ 10.13039/5011000110 33/. CLB acknowledges the European Union for her Marie Sklodowska-Curie grant agreement number 892487 under Horizon 2020 funds. JC acknowledges the Ministerio de Ciencia e Innovación of the Spanish Government for the grant number FJC2020-044215-I of the Juan de la Cierva Formación postdoctoral program.Sedimentation in most glacial lakes and wetlands in the Sierra Nevada (southern Iberian Peninsula) began after the last deglaciation and since the Younger Dryas (YD)-Early Holocene (EH) transition. Therefore, until now, studies on older sedimentary records were lacking in this alpine area, which limits the paleoenvironmental and paleoclimatic information to the Holocene. In this study, we studied palynomorphs from the alpine record from Laguna Seca (LS), the longest and oldest (∼18,000 cal yr BP = 18 kyr) sedimentary record in the Sierra Nevada to investigate the response of forests and lake environments in the western Mediterranean area to climate changes and human impact during the latest Pleistocene and Holocene. The deepest lake conditions occurred during the last deglaciation, indicated by the occurrence of Pediastrum algae, which showed highest abundances during the Heinrich Stadial 1 (HS1) and Bølling-Allerød (B-A) transition. Xerophyte herbs such as Artemisia, Ephedra, and Amaranthaceae were highest during the late B-A and YD indicating regional aridity. Poaceae (grasses) were maxima in the B-A and EH, probably indicating expansion in the barren areas after deglaciation. Maximum in temperature and humidity during the EH and cooling and aridification in the Middle (MH) and Late Holocene (LH) are indicated by the changes in the abundance of deciduous Quercus and Pinus forest species. Botryococcus algae increased during the Early Holocene, while the rest of the algae almost vanished, which could indicate that the lake became very productive but shallower until 8.2 kyr. The lake level lowered and became seasonal in the Middle-Late Holocene transition, coinciding with the regional climate aridification. Microcharcoal analysis done on the palynological preparations agrees with the vegetation changes, showing maxima in the EH and MH, related with the maximum in regional forest occurrence, and a decrease in the LH when the Mediterranean vegetation, and thus fuel availability, diminished. This record shows evidence of anthropogenic impact in the last centuries by cultivation, reforestation, cattle grazing, enhanced erosion and eutrophication.I + D + i projects CGL2013-47038- R, CGL2017-85415-R, PID2019-1049449GB-I00, and PID2021- 125619OB-C21/C22 funded by Ministerio Ciencia e Innovación/Agencia Estatal de Investigación/ 10.13039/501100011033/ and Fondo Europeo de Desarrollo Regional “Una manera de hacer Europa”I + D + i projects A-RNM-336-UGR20 and P20_00059 of the action “Proyectos I + D + i del Programa Operativo FEDER - Junta de Andalucía - UGR” and the research group RNM-190Ministry of Science and Innovation through the FEDER funds from the Spanish Pluriregional Operational Program 2014-2020 (POPE), LifeWatch-ERIC action lineI + D + I project PID2019-1049449 GB-I00 funded by MCIN/AEI/ 10.13039/501100011033/ and FEDER “Una manera de hacer Europa” and the fellowship 20788/PI/18 of Fundación SénecaPredoctoral fellowship BES- 2018-084293 provide by the MCIN/ AEI/ 10.13039/5011000110 33/European Union for her Marie Sklodowska-Curie grant agreement number 892487 under Horizon 2020 fundsMinisterio de Ciencia e Innovación of the Spanish Government for the grant number FJC2020-044215-I of the Juan de la Cierva Formación postdoctoral progra

    Evidences of the Blake and Iceland Basin magnetic excursions in southeastern Iberia and chronological implications for the Padul sedimentary record

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    Acknowledgments This study was supported by the project B-RNM-144-UGR18 and ARNM- 336-UGR20 of the action “Proyectos I + D + i del Programa Operativo FEDER 2018 - Junta de Andalucía-UGR”, the projects CGL2013-47038-R and CGL2017-85415-R, of the “Ministerio de Economía y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER”, and the research group RNM-190 (Junta de Andalucía), and the projects P18-RT-871 and Retos P20_00059 of Junta de Andalucia. A.G.-A. was also supported by a Ram´on y Cajal Fellowship RYC-2015-18966 of the Spanish Government (Ministerio de Economía y Competividad). A.L.-A PhD is funded by BES-2018-084293 (Ministerio de Economía y Competividad). We thank the Paleomagnetic Laboratory CCiTUB-Geo3Bcn CSIC for the support on paleomagnetic analysis. LV and EB thank the Geomodels Research Institute (UB). We are very grateful to two anonymous reviewers and to the editor Christian Zeeden.The Padul-15-05 sediment core provides an exceptional perspective of the paleoenvironmental and climate change in the Western Mediterranean region for the last ca. 200 kyr. However, even though a robust chronology mainly relying on radiometric dating is available for the last 50 ka, the chronology for the older sediments is not yet fully resolved. Ages for the bottom part of the core (>21 m) were previously inferred from amino-acid racemization dating and sediment accumulation rates. In this work, we provide a more accurate chronology for the older part (>100 kyr) of the Padul-15-05 sediment core record based on the recognition of past Earth's magnetic excursions. We identify an interval prone of reversed polarity samples close to MIS-5e/5 d transition that we correlate to the Blake geomagnetic excursion (116.5 kyr–112 kyr). In addition, we identify an interval of low inclinations and two reversed samples that we interpret as the Iceland Basin geomagnetic excursion (192.7 kyr–187.7 kyr: wide scenario of VGP <40°). Our new results, which include IRM acquisition curves that contribute to understand the magnetic mineralogy, enhances the robustness of the age model for the Padul-15-05 sedimentary sequence by adding an independent age dataset with new accurate tie-points. Our refined age control together with the available paleoenvironmental and paleoclimate multiproxy data provide insightful information to unveil the response of the western Mediterranean environments to regional environmental and climate change.Project B-RNM-144-UGR18 and ARNM- 336-UGR20 of the action “Proyectos I + D + i del Programa Operativo FEDER 2018 - Junta de Andalucía-UGR”Projects CGL2013-47038-R and CGL2017-85415-R, of the “Ministerio de Economía y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER”Research group RNM-190 (Junta de Andalucía)Projects P18-RT-871 and Retos P20_00059 of Junta de AndaluciaRamón y Cajal Fellowship RYC-2015-18966 of the Spanish Government (Ministerio de Economía y Competividad)Funded by BES-2018-084293 (Ministerio de Economía y Competividad

    The orientation as a sign of cultural identity: the historic churches of Lanzarote

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    La orientación de las iglesias cristianas es un elemento distintivo de su arquitectura que repite patrones desde época paleocristiana. Se ha medido la orientación de un total de 30 iglesias antiguas de la isla de Lanzarote edificadas con anterioridad a 1810, así como algunos ejemplos más de época posterior. La muestra indica que se siguió un patrón de orientación determinante en la isla, pero, al contrario que la norma encontrada hasta ahora en el resto del orbe cristiano, este prototipo es doble. Por un lado, aparece la representativa orientación a levante (o poniente), pero la muestra tiene además un patrón marcado de orientaciones hacia el norte-noreste exclusivo, por ahora, de Lanzarote. Se analiza el porqué de esta extraña regla, considerándose varias posibilidades desechadas en su mayoría. Encontramos que la explicación puede ser muy prosaica, de forma que, a veces, las necesidades terrenales resultan más relevantes y decisorias que las necesidades del culto.The orientation of Christian churches is a well-known distinctive feature of their architecture. We have measured the orientation of a total of 30 old churches of the island of Lanzarote built prior to 1810, as well as a few buildings of later times, nearly a complete sample of all the island Christian sanctuaries. The analysis of this sample indicates that a definite orientation pattern was followed on the island but, unlike the standard one often found in most of the Christian world, this prototype is twofold. On the one hand, the representative orientation to the east (or west) is present. However, the sample has also a marked orientation towards the north-northeast, which is as far as we know a pattern exclusive of Lanzarote. We analyze the reasons for this rule and suggest that one posible explanation could be a rather prosaic one, namely, that sometimes earthly needs are more relevant than religious beliefs

    Análisis, selección e implementación de la turbina de un turbocompresor para su acoplamiento en el prototipo de planta OTEC-CC-MX-1kWe

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    It is proposed to implement a turbocharger turbine to the OTEC plant prototype to generate 1 kWe. The radius was defined as a physical parameter for the turbocharger selection, the type of coupling was selected, tests were carried out on the turbine using an air compressor, obtaining a maximum of 3400 rpm, generating 1255,2 We, according to data from supplier, proving that coupling the turbine of a turbocharger is technically feasible.Se propone implementar la turbina de un turbocompresor al prototipo de planta OTEC para generar 1 kWe. Se definió el radio como parámetro físico para la selección del turbocompresor, se seleccionó el tipo de acoplamiento y se realizaron pruebas en la turbina mediante un compresor de aire. Se obtuvo un máximo de 3400 rpm, generando 1255,2 We, según datos del proveedor. Así se comprueba que acoplar la turbina de un turbocompresor es técnicamente viable
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