27 research outputs found

    Assessing spatial and temporal variability for some edaphic characteristics of Mediterranean rainfed and irrigated soils

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    Mediterranean soils are particularly threatened by salinization and low levels of organic matter content. In order to assess an edaphic sustainable use, we need to study its characteristics and better understand the temporal and spatial evolution. In this study, a total of 14,852 ha located in a western Mediterranean basin were selected as the study site where 1417 and 1451 topsoil samples were analyzed in 2001/2002 and 2011/2012, respectively, for Soil Organic Matter (SOM) content, pH water (pH(w)) and electrical conductivity (EC). Classical statistics and geostatistics techniques were used and the individual soil samples were related with the cultural system (CS) practiced-rainfed/irrigation-and the Reference Soil Group (RSG)-Cambisols, Calcisols, Luvisols, and Fluvisols. Predictive maps were created by interpolation using the Ordinary Kriging algorithm. The main results of this study were that, when transitioning from a rainfed to irrigation CS, SOM content is maintained in Cambisols but decreases in the other RSGs, pH(w) is maintained and EC increases in Fluvisols, Luvisols, and Cambisols. Over time in the rainfed CS all RSGs maintained SOM and pH(w) but EC increased in Fluvisols, Luvisols, and Calcisols and in the irrigation CS SOM decreased in Luvisols, pH(w) increased in Fluvisols and Calcisols and EC increased in all RSGs.info:eu-repo/semantics/publishedVersio

    Surface-induced alignment at model nematic interfaces

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    We have applied the generalized van der Waals theory to a model liquid crystal that includes, explicitly, all of the second-order terms in the spherical harmonic expansion of the anisotropic intermolecular potential. We have investigated the orientational order induced by each one of these terms, as well as the order resulting from the competition of various terms included in the potential. It was shown that, for appropriate choices of the relative strengths of the spherical harmonic coeKcients, the theory is capable of accounting qualitatively for all the orientational e8'ects observed at nematic interfaces, including tilted orientations. In particular, different molecular alignments at the nematic-vapor and nematic-isotropic interfaces of a given nematogen were described as the result of competing terms in the anisotropic interactions. Additionally, we have shown that temperaturedriven orientational transitions may occur in systems characterized by this type of interaction. For a given choice of parameters, we have also found an orientational transition, which is related to a wetting transition at the nematic-vapor interface. Finally, it was shown that complete wetting of the isotropic liquid-vapor interface by the nematic phase may be destroyed as a result of the competition between di8'erent terms in the potential. Similarly, a reentrant wetting transition at the nematic-vapor interface by the isotropic phase was found, as a result of this competition, at the nematic-vapor interface

    Wetting and interfacial order at nematic free surfaces

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    We apply a density-functional theory to the free surface of a model liquid crystal, to investigate the orientational order at the nematic free surface of systems exhibiting orientational wetting at the isotropic liquid-vapour interface. It is shown that the theory accounts for the growth of the surface ordered layer which develops at the nematic-vapour interface, as the temperature increases up to the triple point, as was recently reported for 4-cyano-4′-n-alkyl-biphenyls. We have found a correlation between the growth of this layer and the non-monotonic temperature dependence of the interfacial tension below the triple point. The theoretical results are in excellent agreement with the results for 8CB.Dirección General de Investigación Científica y Técnica (DGICYT) PB91-060

    Prevalence of Radiographic Signs of Osteoarthritis in Lusitano Purebred Horses

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    Radiographic prevalence and correlation of radiographic findings has not been performed in Lusitano Purebred horses. The aim of this study was to (1) evaluate the prevalence of primary osteoarthritis radiographic findings in Lusitano Purebred horses; (2) to assess correlations between radiographic findings in different joints of the same limb and different limbs; and (3) elucidate the effect of age in the radiographic findings. A radiographic protocol of the stifle, tarsi, fetlocks and distal limbs was done in 98 Lusitanos and the classification of the radiographs was performed using a 0-4 scale developed and applied blindly by three veterinarians. The distal interphalangeal, proximal interphalangeal, meta- carpophalangeal, metatarsophalangeal, tarsometatarsal, distal intertarsal, proximal intertarsal/, tibio- tarsal and femorotibial-patellar joints were evaluated. Most joints presented no abnormal findings or minor abnormal radiographic findings (82.86% grade 1). The most affected joint was tarsometatarsal and more severe lesions were found in tarsometatarsal and distal intertarsal. Femorotibial-patellar radiographic changes were rare (2.13%). A strong/moderate correlation was found between contralat- eral joints with exception hindlimb fetlocks. A moderate correlation was found between fore and hin- dlimbs for distal limb joints. When analyzing ipsilateral as well as diagonal distal limbs, a strong/ moderate correlation was also found. The total score progressed in 0.2 score points per each year of age, revealing that age can be a statistically significant predictor for radiographic changes. Overall, Lusitano horses presented a low prevalence of severe radiographic sings of primary osteoarthritis. Findings in contralateral joints tend to be correlated

    Relevance of intermittent rivers and streams in agricultural landscape and their impact on provided ecosystem services—a Mediterranean case study

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    Ecosystem services (ES), as an interconnection of the landscape mosaic pieces, along with temporal rivers (IRES) are an object of research for environmental planners and ecological economists, among other specialists. This study presents (i) a review on the importance of IRES and the services they can provide to agricultural landscapes; (ii) a classification tool to assess the impact of IRES to provide ES by agricultural landscapes; (iii) the application of the proposed classification to the Caia River in order to identify the importance of this intermittent river for its surrounding agricultural landscape. The classification of the ES follows the Common International Classification of Ecosystem (CICES) classification that was adapted for the purposes of this study. Firstly, the list of ES provided by agricultural landscape was elaborated. In the next step, we assessed the potential of IRES to provide ES. Next, IRES impacts to ES within the agricultural landscape were evaluated according to observations from the conducted field monitoring in the study area. This study focuses on the relevance of the intermittent Caia River-a transboundary river in Spain and Portugal-and its ephemeral tributaries in the agricultural landscape. Our study estimates that each hydrological phase of IRES increases the ES provided by the agricultural landscape. However, the dry phase can potentially have negative impacts on several services. The intensification of the agricultural sector is the main provision of the water resource within the Caia River basin, but we were able to identify several other ES that were positively impacted. The present study is in line with the conclusions of other authors who state that IRES constitute a valuable resource which should not be underestimated by society.Agência financiadora COST Action CA15113 Slovak Research and Development Agency APVV-16-0278 UID/SOC/04020/2013info:eu-repo/semantics/publishedVersio

    Parâmetros genéticos para produção de leite no dia do controle de vacas da raça Holandesa utilizando modelos de análises de fatores e componentes principais

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    Objetivou-se comparar um modelo multicaracterística padrão com modelos de análise de fatores (AF) e de componentes principais (CP) para estimar parâmetros genéticos para a produção de leite no dia do controle (PLDC) de vacas da raça Holandesa. O arquivo de trabalho constituiu-se de 4.616 registros mensais de PLDC de primeiras lactações de vacas da raça Holandesa. As PLDC foram agrupadas em dez classes mensais, entre o 5o e 305o dia da lactação (PLDC1 a PLDC10). Foram realizadas análises considerando 11 modelos diferentes, como segue: multi-característica padrão (MC); cinco modelos de posto reduzido, para a matriz de covariância genética, ajustando um a cinco (CP1 ... CP5) componentes principais; e dois modelos utilizando análise de fatores (F1, F2, F3, F4 e F5). Para todos os modelos, foram considerados como aleatórios os efeitos genético aditivo e o residual e como fixos os de grupo de contemporâneos, da idade da vaca ao parto (linear e quadrático) e dias em lactação (linear). Os valores de Log L, AIC e BIC melhoraram com o aumento do número de parâmetros até CP4 e AF4. Comparando CP4 e AF4, observa-se que CP4 resultou em melhores valores de Log L, AIC e BIC. As estimativas de herdabilidade e correlações genéticas utilizando os modelos MC, CP4 e AF4 foram similares, variando de 0,06 (PL6) a 0,65 (PL10) e de 0,05 (PL4xPL10) a 0,94 (PL2xPL3), respectivamente, indicando que a estrutura de covariâncias genéticas entre as produções de leite no dia do controle pode ser ajustada utilizando um modelo de posto reduzido, contendo quatro componentes principais ou quatro fatores.The objective was to compare a standard multi-trait (MT) analysis model with factor (FA) and principal components (PC) analyses models to estimated genetic parameters for Holstein cows test day milk production (TD). The data file was composed by 4.616 TD at first lactation registers. The TD was grouped into ten monthly classes of lactation, from the 5th and the 305th day of lactation (TD1 to TD10). Analyses were performed considering 11 different models: standard multi-traits (MT), five reduced rank models to genetic covariance matrix adjusting one (PC1), two (PC2), three (PC3), four (PC4) and five (PD5) principal components and five models using factor analyses (F1, F2, F3, F4 and F5). To all the models the effects additive genetic and residual were considered as random and the effects of contemporary group, age of cow at parturition (linear and quadratic) and days in lactation (linear) were considered as fixed. The values of Log L, AIC e BIC improved with the augment of the number of parameters until CP4 and AF4. Comparing CP4 and AF4 is possible to verify that CP4 proportioned better values to Log L, AIC e BIC. The heritabilities and genetic correlations estimated to the ten test day milk production using MC, CP4 and AF4 models were similar ranging from 0.06 (PL6) to 0.65 (PL10) and from 0.05 (PL4xPL10) to 0.94 (PL2xPL3), respectively, indicating that the structure of the genetic covariance between the TD milk productions can be adjusted using a reduced rank model with four principal components or four factors

    Computer simulation study of the nematic–vapour interface in the Gay–Berne model

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    We present computer simulations of the vapour–nematic interface of the Gay–Berne model. We considered situations which correspond to either prolate or oblate molecules. We determine the anchoring of the nematic phase and correlate it with the intermolecular potential parameters. On the other hand, we evaluate the surface tension associated to this interface. We find a corresponding states law for the surface tension dependence on the temperature, valid for both prolate and oblate molecules.Fundación Portuguesa para la Ciencia y la Tecnología EXCL / FIS-NAN / 0083/2012Ministerio de Economía y Competitividad FIS2012-32455Junta de Andalucía P09-FQM-493
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