Usos de la repetición como recurso plástico

ste trabajo se enmarca en una investigación sobre el uso de la repetición como recurso plástico en arte contemporáneo. Su objetivo es identificar formas de repetir como herramienta de creación artística para significar opuestos. La metodología consiste en un análisis comparativo de la obra de Andy Warhol, Richard Long y Allan McCollum. La repetición ha formado parte indispensable en la configuración de las estructuras básicas del arte actual y, por lo tanto, un acercamiento a sus formas de uso y significación ayuda a comprender esas bases y estructuras. Se concluye que el significado de la repetición en arte depende de la forma en que se use y contextualice y que puede llegar a dotar a la obra de significados paradójicos presentando una alta gama de posibilidades que van desde la aparición de estereotipos a temas relacionados con el valor, precio o unicidad en arte

Trend analysis of CO2 and CH4 recorded at a semi-natural site in the northern plateau of the Iberian Peninsula

CO2 and CH4 were recorded from October 2010 to February 2016 with a Picarro G1301 analyser at the centre of the upper plateau of the Iberian Peninsula. Large CO2 values were observed during the vegetation growing season, and were reinforced by the stable boundary layer during the night. Annual CH4 evolution may be explained by ecosystem activity and by the dispersion linked with the evolution of the boundary layer. Their trends were studied using an equation that considers one polynomial and one harmonic part. The polynomial part revealed an increasing trend from 0.8 to 2.3 ppm year 1 for CO2 and from 0.004 to 0.011 ppm year 1 for CH4. The harmonic part considered four harmonics whose amplitudes were noticeable for the first and second harmonics for CO2 and for the first harmonic for CH4. Long-term evolution was similar with alternative equations. Finally, seasonal study indicated summer minima for both gases, which may be explained by the lack of vegetation in this season. Harmonic analysis showed two maxima for CO2, one in spring linked with vegetation growth, which decreased with time, and another in autumn related with the onset of plant activity after the summer, which increased with time. CH4 presented only one maximum in winter and a short time with steady concentration in spring where the evolution of the boundary layer may play a noticeable role. The harmonic equation, which takes into account all the observations, revealed opposite behaviour between CO2, whose minima decreased, and CH4, whose maxima increased.Ministry of Economy and Competitiveness and ERDF funds (projects CGL2009-11979 and CGL2014-53948-P)

Features of the annual evolution of CO2 and CH4 in the atmosphere of a Mediterranean climate site studied using a nonparametric and a harmonic function

Concentrations of CO2 and CH4 measured over 3 years at a rural site in the Spanish northern plateau were investigated together with vegetation and meteorological variables. Two procedures were implemented to study the annual evolution. Kernel estimation provided a detailed time description, and the harmonic model may be fitted easily. The site was characterised by grass from autumn to spring. However, vigorous growth was observed during the latter season due to the biological cycle of plants under favourable meteorological conditions. A CO2 peak was observed a fortnight before the time of maximum NDVI, and was attributed to the prevalence of respiration over photosynthesis. A pronounced trough was apparent in summer and was explained by the death of vegetation and active dispersion in a highly developed boundary layer. CH4 evolution was characterised by a deficit period from May to October, indicating that meteorological evolution played a key role. The harmonic model showed that annual and half-annual cycles evidenced a similar contribution for CO2, whereas said weight for the half-annual cycle was considerably smaller for CH4.Ministry of Economy and Competitiveness and ERDF funds (grant numbers CGL2009-11979 and CGL2014-53948-P

Modeling the erythemal surface diffuse irradiance fraction for Badajoz, Spain

A pesar de su importante papel en la salud humana y en numerosos procesos biológicos, el componente difuso de la irradiación ultravioleta eritemática (UVER) apenas se mide en las estaciones radiométricas estándar y, por lo tanto, debe estimarse. Este estudio propone y compara 10 modelos empíricos para estimar la fracción difusa de UVER. Estos modelos están inspirados en expresiones matemáticas originalmente utilizadas para estimar la fracción difusa total, pero, en este estudio, se aplican al caso UVER y se comparan con mediciones experimentales. Además de adaptarse a la gama UVER de las diversas variables independientes involucradas en estos modelos, se agregó la columna de ozono total para tener en cuenta su fuerte impacto en la atenuación de la radiación ultravioleta. Los modelos propuestos se ajustan a mediciones experimentales y se validan contra un subconjunto independiente. El modelo de mejor desempeño (RAU3) se basa en un modelo propuesto por Ruiz-Arias et al. (2010) y muestra valores de r2 iguales a 0.91 y error relativo de la media cuadrática (rRMSE) igual a 6.1%. El rendimiento alcanzado por este modelo completamente empírico es mejor que el obtenido por los enfoques semi-empíricos anteriores y, por lo tanto, no necesita información adicional de otros modelos basados ​​físicamente. Este estudio expande la investigación previa a la gama ultravioleta y proporciona modelos empíricos confiables para estimar con precisión la fracción difusa UVER.Despite its important role on the human health and numerous biological processes, the diffuse component of the erythemal ultraviolet irradiance (UVER) is scarcely measured at standard radiometric stations and therefore needs to be estimated. This study proposes and compares 10 empirical models to estimate the UVER diffuse fraction. These models are inspired from mathematical expressions originally used to estimate total diffuse fraction, but, in this study, they are applied to the UVER case and tested against experimental measurements. In addition to adapting to the UVER range the various independent variables involved in these models, the total ozone column has been added in order to account for its strong impact on the attenuation of ultraviolet radiation. The proposed models are fitted to experimental measurements and validated against an independent subset. The best-performing model (RAU3) is based on a model proposed by Ruiz-Arias et al. (2010) and shows values of r2 equal to 0.91 and relative root-mean-square error (rRMSE) equal to 6.1%. The performance achieved by this entirely empirical model is better than those obtained by previous semi-empirical approaches and therefore needs no additional information from other physically based models. This study expands on previous research to the ultraviolet range and provides reliable empirical models to accurately estimate the UVER diffuse fraction.Trabajo financiado por: Ministerio de Economía y Competitividad. Proyecto CGL2014-56255-C2-1-R (I+D+i) Junta de Extremadura y Fondos FEDER. Ayuda a grupos GR15137 Ministerio de Economía y Competitividad. Beca predoctoral FPI BES-2012-054975, para Guadalupe Sánchez HernándezpeerReviewe

Influence of wind speed on CO2 and CH4 concentrations at a rural site

Producción CientíficaMeteorological variables have a noticeable impact on pollutant concentrations. Among these variables, wind speed is typically measured, although research into how pollutants respond to it can be improved. This study considers nine years of hourly CO2 and CH4 measurements at a rural site, where wind speed values were calculated by the METEX model. Nine wind speed intervals are proposed where concentrations, distribution functions, and daily as well as annual cycles are calculated. Contrasts between local and transported concentrations are around 5 and 0.03 ppm for CO2 and CH4, respectively. Seven skewed distributions are applied, and five efficiency criteria are considered to test the goodness of fit, with the modified Nash–Sutcliffe efficiency proving to be the most sensitive statistic. The Gumbel distribution is seen to be the most suitable for CO2, whereas the Weibull distribution is chosen for CH4, with the exponential function being the worst. Finally, daily and annual cycles are analysed, where a gradual decrease in amplitude is observed, particularly for the daily cycle. Parametric and nonparametric procedures are used to fit both cycles. The latter gave the best fits, with the agreement being higher for the daily cycle, where evolution is smoother than for the annual cycle.Ministerio de Economía, Industria y Competitividad y Fondo Europeo de Desarrollo Regional (FEDER) - (Projects CGL-2009-11979 and CGL2014-53948-P)Junta de Castilla y León - (Project VA027G19

Trend analysis and outlier distribution of CO2 and CH4: A case study at a rural site in northern Spain

Producción CientíficaCO2 and CH4 outliers may have a noticeable impact on the trend of both gases. Nine years of measurements since 2010 recorded at a rural site in northern Spain were used to investigate these outliers. Their influence on the trend was presented and two limits were established. No more than 23.5% of outliers should be excluded from the measurement series in order to obtain representative trends, which were 2.349 ± 0.012 ppm year−1 for CO2 and 0.00879 ± 0.00004 ppm year−1 for CH4. Two types of outliers were distinguished. Those above the trend line and the rest below the trend line. Outliers were described by skewed distributions where the Weibull distribution figures prominently in most cases. A qualitative procedure was presented to exclude the worst fits, although five statistics were considered to select the best fit. In this case, the modified Nash-Sutcliffe efficiency is prominent. Finally, three symmetrical distributions were added to fit the observations when outliers are excluded, with the Gaussian and beta distributions providing the best fits. As a result, certain skewed functions, such as the lognormal distribution, whose use is frequent for air pollutants, could be questioned in certain applications.Ministerio de Economía y Competitividad y fondos FEDER, (project numbers CGL-2009-11979 and CGL2014-53948-P

Boundaries of air mass trajectory clustering: key points and applications

Calculating air mass trajectories is common in atmospheric analyses. However, if explainable results are to be achieved, several procedures are needed to process the vast amount of information handled. Clustering methods are statistical tools usually considered for such a purpose. Although they are based on rigorous algorithms, certain questions still remain when these methods are applied. The current review is organised in sections according to the sequence followed by such procedures. First, the types of clustering methods are described, with their core being the distance used. One key point is the stopping rule, which determines the final number of clusters. A simple classification based on this number is then suggested. Finally, the graphical presentation of the results is examined and the main drawbacks are commented on. A range of applications and results are considered to illustrate each section, and certain caveats and recommendations are also presented.Ministry of Economy and Competitiveness, Spain and ERDF funds (grant numbers CGL2009-11979 and CGL2014-53948-P

Early environmental and biological influences on preschool motor skills: implications for early childhood care and education

Early motor skills underpin the more complex and specialized movements required for physical activity. Therefore, the design of interventions that enhance higher levels of early motor skills may encourage subsequent participation in physical activity. To do so, it is necessary to determine the influence of certain factors (some of which appear very early) on early motor skills. The objective of this study was to examine the influence of some very early environmental variables (delivery mode, feeding type during the first 4 months of life) and some biological variables (sex and age in months) on preschool motor skills, considered both globally and specifically. The sample was composed by 43 preschool students aged 5–6 years. The participant's parents completed an ad hoc questionnaire, reporting on delivery mode, feeding type, sex, and age in months. The children's motor skills were assessed using observational methodology in the school setting, while the children participated in their regular motor skills sessions. A Nomothetic/Punctual/Multidimensional observational design was used. Results revealed that certain preschool motor skills were specifically influenced by delivery mode, feeding type, sex, and age. Children born by vaginal delivery showed higher scores than children born via C-section in throwing (p = 0.000; d = 0.63); total control of objects (p = 0.004; d = 0.97); total gross motor skills (p = 0.005; d = 0.95); and total motor skills (p = 0.002; d = 1.04). Children who were exclusively breastfed outperformed those who were formula-fed in throwing (p = 0.016; d = 0.75); visual-motor integration (p = 0.005; d = 0.94); total control of objects (p = 0.002; d = 1.02); total gross motor skills (p = 0.023; d = 0.82); and total motor skills (p = 0.042; d = 0.74). Boys outperformed girls in throwing (p = 0.041; d = 0.74) and total control of objects (p = 0.024; d = 0.63); while the opposite occurred in static balance (p = 0.000; d = 1.2); visual-motor coordination (p = 0.020; d = 0.79); and total fine motor skills (p = 0.032; d = 0.72). Older children (aged 69–74 months) obtained higher scores than younger ones (aged 63–68 months) in dynamic balance (p = 0.030; d = 0.66); visual-motor integration (p = 0.034; d = 0.63); and total balance (p = 0.013; d = 0.75). Implications for early childhood care and education are discussed since this is a critical period for motor skill development and learning

SCOPE model applied for rapeseed in Spain

The integrated SCOPE (Soil, Canopy Observation, Photochemistry and Energy balance) model, coupling radiative transfer theory and biochemistry, was applied to a biodiesel crop grown in a Spanish agricultural area. Energy fluxes and CO2 exchange were simulated with this model for the period spanning January 2008 to October 2008. Resultswere compared to experimentalmeasurements performed using eddy covariance and meteorological instrumentation. The reliability of the model was proven by simulating latent (LE) and sensible (H) heat fluxes, soil heat flux (G), and CO2 exchanges (NEE and GPP). LAI data used as input in the model were retrieved from the MODIS and MERIS sensors. SCOPE was able to reproduce similar seasonal trends to those measured for NEE, GPP and LE. When considering H, the modelled values were underestimated for the period covering July 2008 to mid-September 2008. The modelled fluxes reproduced the observed seasonal evolution with determination coefficients of over 0.77 when LE and H were evaluated. The modelled results offered good agreement with observed data for NEE and GPP, regardless of whether LAI data belonged to MODIS or MERIS, showing slopes of 0.87 and 0.91 for NEE-MODIS and NEE-MERIS, and 0.91 and 0.94 for GPP-MODIS and GPP-MERIS, respectively. Moreover, SCOPE was able to reproduce similar seasonal behaviou s to those observed for the experimental carbón fluxes, clearly showing the CO2 sink/source behaviour for the whole period studied

Influence of atmospheric stability and transport on CH4 concentrations in northern Spain

Continuous methane (CH4) concentrations were measured in Northern Spain over two years (2011–2012) by multi-point sampling at 1.8, 3.7 and 8.3 m using a Picarro analyser. The technique is based on cavity ringdown spectroscopy. The contrast in mean concentrations was about 1.2 ppb, with 95th percentiles differing by 2.2 ppb and mean minimum concentrations proving similar. Temporal variations of CH4 were also analysed, with a similar seasonal variability being found for the three heights. The highest CH4 concentrationswere obtained in late autumn andwinter and the lowest in summer, yielding a range of 52 ppb. This variationmay depend on the active photochemical reaction with OH radical during a period of intense solar radiation and changes in soil conditions together with variations in emissions. Peak concentration levels were recorded at night-time, between 5:00–7:00 GMT, with mean values ranging between 1920 and 1923 ppb. The lowest value, around 1884 ppb, was obtained at 16:00 GMT. This diurnal variation was mainly related to vertical mixing and photochemistry. Therefore, CH4 concentrations were also examined using the bulk Richardson number (RB) as a stability indicator. Four groupswere distinguished: unstable cases, situations with pure shear flow, transitional stages and drainage flows. The highest contrast in mean CH4 concentrations between lower and upper heights was obtained for the transition and drainage cases, mainly associated to high concentrations from nearby sources. The impact of long range transport was analysed by means of 3-day isobaric backward air mass trajectories, which were calculated taking into account origins from Europe, Africa, the Atlantic Ocean and Local conditions. Assessment of the results showed the influence of S and SE wind sectors, especially with Local conditions associated with low winds. Finally, an estimation of the background CH4 concentration in the study period provided an average value of about 1892 ppb.Ministry of Economy and Competitiveness (projects CGL2009-11979 and CGL2014-53948-P.