Sedimentology and depositional architecture of tufas deposited in stepped fluvial systems of changing slope: Lessons from the quaternary añamaza valley (Iberian Range, Spain)

The Pleistocene and Holocene tufas of the Añamaza valley (stepped build-ups, up to 70 m thick, along the valley) consist of several depositional stages separated by erosional surfaces. Eight associations of tufa and related carbonate facies, plus minor polygenic detrital facies, represent the processes that occurred in different fluvial and related environments. The bedrock lithology and structure controlled the location of the knickpoints along the valley and allowed separation of two stepped stretches with distinct conceptual facies models. The moderate-slope model includes extensive standing-water areas dammed by barrage-cascades. In the lakes, bioclastic silts, sands and limestones along with phytoclastic and marly, at places peaty, sediments formed. Abundant stem phytoherms account for extensive palustrine areas. The high-slope model consists of smaller dammed areas between close-up cascades and barrage-cascades, which were composed primarily of moss phytoherms and phytoclastic tufas. An outstanding feature is the extensive steep reach with phytoclastic and polygenic detrital sediments, and stepped cascades consisting of stromatolitic and moss phytoherms. There, the steep slope limited the preservation of stem phytoherms and favoured erosion. The geometry and thickness of the sedimentary fill (wedge-shaped units composed of cascade and barrage-cascade deposits downstream, and dammed and gentle-sloped channel deposits upstream) are therefore different for each model. Multi-storey wedges are a distinctive feature of the high-slope model. The initial knickpoint geometry and the tufa aggradation/progradation ratio on such steep surfaces (for example, related to changes in discharge) controlled the growth style of the cascades or barrage-cascades and, hence, the extent, thickness and vertical evolution of the upstream deposits. The sedimentological attributes and stable-isotope composition of the carbonate facies suggest a higher and more variable precipitation/evaporation ratio during the Pleistocene than during the Holocene, consistent with an overall decrease in the river discharge. This evolution was coupled with warm conditions, which prevailed during the stages of tufa formation. These results may help to assess architectural patterns in interpreting other basins, and underscore the significance of tufas as records of past hydrology and climate

La ampliación de la Unión Europea: situación actual y perspectivas

El proceso de unificación del continente, que se inició con la unión de los seis Estados fundadores de la Comunidad Europea, que se convirtieron en nueve en 1973, en diez en 1981, en doce en 1986, en quince en 1995, y que seguramente llegarán a 25 conforme avance este Tercer Milenio no deja de evolucionar. Si bien los desafíos de la posguerra exigían un esfuerzo de reconciliación de los pueblos y de la reconstrucción de las economías del oeste europeo, los que se le presentan a Europa en este siglo XXI son de una magnitud equivalente.Las nuevas democracias surgidas de la desintegración del bloque comunista esperan de sus vecinos solidaridad y el logro de un nuevo destino común. La historia y la geografía del Viejo Continente van a reconciliarse finalmente

Intrinsic and extrinsic controls of spatial and temporal variations in modern fluvial tufa sedimentation: A thirteen-year record from a semi-arid environment

Sedimentological and hydrochemical parameters of the River Piedra (north-east Spain) were monitored every six months (from 1999 to 2012) at 24 sites, at which tablets were installed all along the river. The river water is of HCO3–SO4–Ca type and is notably influenced by inputs from upstream karstic springs. Tufa deposition was first detected 8 km downstream of these springs and greatly increased from there, primarily along the steeper stretch (i.e. within the Monasterio de Piedra Natural Park); then, deposition decreased through the most downstream stretch, with smaller ground water inputs. The spatial evolution of the tufa thickness, with parallel variations of PWP (Plummer, Wigley, Parkhurst) rates, was thus determined by the river water pCO2 which was controlled by ground water inputs and by the river bed slope. Five fluvial subenvironments and seven sedimentary facies were characterized. The water flow conditions are the primary factor responsible for the distinct deposition rates of facies, mainly through CO2-outgassing. Stromatolites and moss-tufa and alga-tufa had the highest rates, whereas loose tufa formed in slow-flowing water and tufa of spray areas had thinner deposition. A six-month pattern in the deposition rate was detected through thickness measurements. That pattern was parallel to the seasonal PWP rates. The increased deposition during warm periods (spring and summer; mean: 5·08 mm) compared with cool periods (autumn and winter; mean: 2·77 mm) is linked chiefly to temperature, which controlled the seasonal changes in the physico-chemical and biological processes; this finding is supported by a principal components analysis. Seasonal variations of insolation and day duration also contributed to such a deposition pattern. Large discharge events, which provoked erosion of tufa deposits and dilution of water, caused the reversal of the seasonal deposition rate pattern. Stromatolites are likely to preserve the most complete sedimentary record. Although tufas are a potentially sensitive record of climate-related parameters, erosion is an intrinsic process that may overwhelm the effects of such parameters. This issue should be considered in palaeoclimatic studies based on the tufa record, particularly in semi-arid conditions

Tufa sedimentation in changing hydrological conditions: the River Mesa (Spain)

The processes controlling tufa deposition along the River Mesa (NE Spain) were studied from April 2003 to September 2009, based on six-monthly monitoring of physical and chemical parameters of the river water and sedimentological characteristics, including deposition rates on tablets. With a mean annual discharge around 1.5m3 /s, the sedimentation rate (mean 2mm/yr) recorded important spatial, seasonal and interannual variations. The river waters are of the calcium bicarbonate type. In this study, three distinct river stretches were distinguished based on the steady groundwater inputs, some of low-thermal nature. Groundwater discharges controlled the water chemical composition, and some sedimentation features too. At each stretch, an increase in pCO2 and conductivity was measured around the spring sites. Decreasing trends in conductivity or alkalinity with high enough saturation values with respect to calcite were only clearly observed in the intermediate stretch, which had higher tufa deposition rates than the other two. Tufa deposition rates were higher in cool (autumn+winter) than in warm (spring+summer) periods. In some low-rainfall warm periods, tufa deposition was inhibited or limited due to the low flow –mainly from groundwater inputs– and to the dryness of some river sites, which indeed favoured erosion during flooding. A decrease in yearly deposition rates from April 2006 onwards paralleled an important reduction in the river discharge. Groundwater inputs, drought periods and flood events should therefore be considered to understand fluvial tufa sedimentation in semi-arid conditions

Ethylene is involved in pistil fate by modulating the onset of ovule senescence and the GA-mediated fruit set in Arabidopsis

Background: Ovule lifespan is an important factor in determining the ability to set fruits and produce seeds. Once ovule senescence is established, fruit set capacity in response to gibberellins (GAs) is lost. We aimed to elucidate whether ethylene plays a role in controlling ovule senescence and the fruit set response in Arabidopsis. Results: Ethylene response inhibitors, silver thiosulphate (STS) and 1-methylcyclopropene (1-MCP), were able to delay the loss of pistil response to GA3 . In addition, ethylene insensitive mutants ein2-5 and ein3-1 showed delayed loss of pistil response, as in plants treated with STS and 1-MCP, while constitutive mutant ctr1-1 displayed premature loss of response. The analysis of the expression of ethylene biosynthesis genes suggests that ethylene is synthesised in ovules at the onset of ovule senescence, while a transcriptional meta-analysis also supports an activated ethylene-dependent senescence upon the establishment of ovule senescence. Finally, a SAG12:GUS reporter line proved useful to monitor ovule senescence and to directly demonstrate that ethylene specifically modulates ovule senescence. Conclusions: We have shown that ethylene is involved in both the control of the ovule lifespan and the determination of the pistil/fruit fate. Our data support a role of the ovule in modulating the GA response during fruit set in Arabidopsis. A possible mechanism that links the ethylene modulation of the ovule senescence and the GA3 -induced fruit set response is discussed.The authors wish to thank Drs. Alonso and Amasino for their gifts of seeds; Drs. Alonso, Alabadi, and Blazquez for critically reading the manuscript, and Ms. Argomaniz and Ms. Fuster for technical assistance in the lab. This work has been supported by grants BIO2005-07156-C02-01 and BIO2008-01039 from the Spanish Ministry of Science and Innovation, Plan Nacional de I+D. PCB received a PhD fellowship from the Spanish Ministry of Science and Innovation.Carbonell Bejerano, P.; Urbez Lagunas, C.; Granell Richart, A.; Carbonell Gisbert, J.; Perez Amador, MA. (2011). Ethylene is involved in pistil fate by modulating the onset of ovule senescence and the GA-mediated fruit set in Arabidopsis. BMC Plant Biology. 11:84-84. https://doi.org/10.1186/1471-2229-11-84S84841

Tufa sedimentation in changing hydrological conditions: the River Mesa (Spain)

The processes controlling tufa deposition along the River Mesa (NE Spain) were studied from April 2003 to September 2009, based on six-monthly monitoring of physical and chemical parameters of the river water and sedimentological characteristics, including deposition rates on tablets. With a mean annual discharge around 1.5m3/s, the sedimentation rate (mean 2mm/yr) recorded important spatial, seasonal and interannual variations. The river waters are of the calcium bicarbonate type. In this study, three distinct river stretches were distinguished based on the steady groundwater inputs, some of low-thermal nature. Groundwater discharges controlled the water chemical composition, and some sedimentation features too. At each stretch, an increase in pCO2 and conductivity was measured around the spring sites. Decreasing trends in conductivity or alkalinity with high enough saturation values with respect to calcite were only clearly observed in the intermediate stretch, which had higher tufa deposition rates than the other two. Tufa deposition rates were higher in cool (autumn+winter) than in warm (spring+summer) periods. In some low-rainfall warm periods, tufa deposition was inhibited or limited due to the low flow –mainly from groundwater inputs– and to the dryness of some river sites, which indeed favoured erosion during flooding. A decrease in yearly deposition rates from April 2006 onwards paralleled an important reduction in the river discharge. Groundwater inputs, drought periods and flood events should therefore be considered to understand fluvial tufa sedimentation in semi-arid conditions

Discerning the interactions between environmental parameters reflected in d13C and d18O of recent fluvial tufas: Lessons from a Mediterranean climate region

d13C and d18O of recent, continuous tufa records, obtained during a monitoring period spanning 3 to 13 years, are compared with the corresponding, known environmental conditions. Three rivers in NE Iberia (located along a 200-km N–S transect) are used for this comparison. The isotopic variations through space and time are discussed in terms of the environmental and geological parameters that operate on different scales, focusing on discerning the interactions between these parameters and providing examples of possible misinterpretation of climatic conditions, which is important to past climate studies based on isotopic data. The calculation of the actual isotopic fractionation coefficients, and the comparison with the literature-derived coefficients, demonstrates that the studied tufa formation was close to isotopic equilibrium to reflect the water temperature. The difference between mean measured water temperature (Tw) and mean calculated Tw (based on d18Ocalcite and measured d18Owater) is less than 2.7 °C. Tendencies of these calculated Tw are similar to the regional air temperature (Tair) tendencies through time, in particular in the case of the 13-year record, although certain deviations exist over shorter time spans. The best agreement between measured and calculated Tw and between d18Ocalcite-based Tw tendencies and Tair tendencies corresponds to the tufa stromatolite facies. Differences between the d18Ocalcite records of the three rivers cannot be attributed to temperature changes, but to the varying influences of groundwater inputs and isotopic rainfall composition in each river.Without considering these parameters, d18Ocalcite-based Tw calculations yield inaccurate results when comparing the study sites. d13Ccalcite values do not exhibit distinct patterns over time, and d13Ccalcite variations are likely caused by local processes that do not reflect general environmental changes. These findings underscore the significance of accounting for both groundwater behaviour and rainfall stable isotope composition when interpreting climate parameters in carbonate systems, particularly when differences between the isotopic signatures of deposits exist in the same region

The vanishing axis as a resource in the architectonic backgrounds in the full-length films of animation in USA (1980-2005)

Pese a la abundancia de material fílmico producido por la industria de animación norteamericana en el período que abarca los últimos veinte años del siglo xx y los inicios del xxi, son escasos los estudios sobre la perspectiva en el trabajo de fondos de estas películas. Si bien parece que los fondos sean una parte secundaria, éstos juegan, no obstante, un papel esencial en la expresión de los personajes y en el sentido de realidad o de fantasía en el que se les busca ubicar. Vamos a analizar la aplicación del eje de fugas como recurso perspectivo que incide en la representación figurativa, ayudando a salvar unas veces pequeñas limitaciones perspectivas, mientras que en otras ocasiones simplemente son empleados como parte del juego perspectivo. En este contexto analizaremos también la estructura espacial, para lo cual efectuaremos restituciones de las obras y veremos lo que éstas nos descubren, intentando averiguar la intención del artista y el papel que ejerce este tipo de soluciones sobre la acción de los personajes en el espacio representado y sus consecuencias en el referente visual. Por razones temáticas, el ámbito de estudio de los fondos se centra en elementos arquitectónicos exteriores y en espacios interiores, dentro de un período temporal que hemos considerado como el más creativo e influyente.Despite the abundance of footage produced by the North American animation industry in the period covering the last twenty years of the 20th century and early 21st, there are few studies on perspective in the backgrounds of these films. Although it seems that the backgrounds are a secondary part in animation, they play, however, an essential role in the expression of the characters and in the atmosphere of reality or fantasy in which they are located. We are going to analyze the application of the vanishing axis as a resource for the firgurative representation, sometimes helping to save small perspective limitations, while in other occasions they are simply used as part of perspective game. In this context we will also analyze the spatial structure, for which we will make restitution of the works to see what they discover us. We try to find out the purpose of the artist, and the role played by such solutions on the action of the characters in those backgrounds and its consequences for visual reference. For thematic reasons the field of our study on backgrounds focuses on exterior architectural elements and interior spaces within a time period that we consider as the most creative and influential

Propuesta didáctica sobre el Parkour para la mejora de la competencia motriz, valores y actitudes de esta disciplina física en el alumnado de Educación Primaria

La recién llegada del Parkour al ámbito educativo ha significado una oportunidad para desarrollar las capacidades motrices básicas del alumnado de una forma original e innovadora. El conocimiento de su historia, filosofía y terminología por parte de los maestros y maestras de Educación Física, es necesario para abordar su didáctica desde una perspectiva actualizada que permita aprovechar el potencial que ofrece esta disciplina urbana. Al mismo tiempo, el desarrollo de aprendizajes transversales al área de Educación Física y las conexiones interdisciplinares con otras asignaturas, dotarán de mayor valor a la experiencia del alumnado. El desarrollo de los aprendizajes de Parkour por lo tanto, servirá al profesorado para trabajar las posibilidades motrices y capacidades físicas básicas, desde la interacción con otros compañeros, la superación personal, el respeto y la adquisición de hábitos y rutinas saludables.<br /