1,720,964 research outputs found
Aplicación de la fitorremediación a suelos contaminados por metales pesados
Get PDFLos metales pesados constituyen uno de los grupos de contaminantes ambientales sujetos a una mayor investigación y preocupación, fundamentalmente debido a su persistencia, a las bajas concentraciones a las que pueden manifestar sus efectos tóxicos. Todo esto, junto con su acumulación progresiva y/o su transferencia a otros medios naturales (como las aguas subterráneas), su entrada en la cadena trófica, etc., suponen una amenaza para la salud humana y la de los ecosistemas. Por todo esto, la legislación europea obliga a restaurar de dichos suelos mediante acciones de remediación que permitan extraer, controlar, contener o reducir los contaminantes de un área determinada. Dentro del amplio abanico de tecnologías existentes para ello, la fitorremediación, que implica la utilización de plantas, y en especial la fitoextracción, se presenta como una técnica emergente que supone, generalmente, unos menores costes y una menor destrucción y alteración del medio. Sin embargo, se encuentra todavía en fase experimental y presenta grandes limitaciones que la convierten en un proceso lento y difícil de llevar a la práctica, dada la competencia con otras técnicas usualmente empleadas. Esto se advierte por el escaso número de artículos, aunque se percibe en aumento en las bases de datos ISI Web of Science y Science Direct. Las últimas tendencias se dirigen a la identificación de los genes que codifican la hiperacumulación de metales pesados específicos. Es de vital importancia, ya que nos daría la posibilidad de crear plantas transgénicas combinando las características deseables en una sola especie vegetal, sin embargo existe una carencia de estudios de campo que permitan comprobar su viabilidad.Fac. de FarmaciaTRUEunpu
Soil degradation due to agricultural activities. Case study in Navas del Rey
Get PDFEl abandono agrícola es un problema creciente en Europa relacionado con un cambio en el uso del suelo. El correcto manejo agrícola del terreno es necesario a fin de permitir su correcta recuperación y facilitar la sucesión secundaria propia de un proceso de abandono. España es uno de los principales productores de vino a nivel mundial pero aun así sus viñedos sufren también este proceso de abandono, en especial aquellos con difícil acceso, situados en laderas empinadas y alejados de los núcleos rurales. En este trabajo se pretenden analizar tres parcelas de viñedos abandonados (con distintas edades de abandono) cuya recuperación mediante restauración pasiva es extremadamente lenta, posiblemente por un manejo inadecuado. Se plantea como causas la contaminación por distintas sustancias presentes en fertilizantes y pesticidas utilizados históricamente en estos cultivos (como el arsénico (As) o el cobre (Cu)), además de la intensidad del manejo agrícola llevado a cabo en estos suelos. Los resultados muestran una variación en determinadas propiedades de los suelos analizados. La actividad enzimática en las parcelas afectadas desciende notablemente en comparación con aquellas parcelas empleadas como controles. En las propiedades físico-químicas destaca el descenso en el contenido de carbono orgánico total y aquellas propiedades relacionadas con el mismo. El contenido metálico resultó significativo para antimonio, arsénico, berilio, cobalto y vanadio en alguna de las parcelas. Los resultados ponen de manifiesto la existencia de una degradación asociada principalmente al manejo del suelo durante sus años de actividad, más que a la contaminación del mismo, si bien es cierto que no se puede obviar la existencia de esta.Agricultural abandonment is a growing problem in Europe related to a land use change. The correct agricultural management of the land is necessary in order to allow its correct recovery and to facilitate the secondary succession inherent to a process of abandonment. Spain is one of the main wine producers in the world, but its vineyards also suffer from this process of abandonment, especially those with difficult access, located on steep slopes and far from rural areas. This paper aims to analyse three plots of abandoned vineyards (with different ages of abandonment) whose recovery through passive restoration is extremely slow, possibly due to inadequate management. Contamination by different substances present in fertilisers and pesticides historically
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used on these crops (such as arsenic (As) or copper (Cu)), as well as the intensity of the agricultural management carried out on these soils, are proposed as causes. The results show a variation in certain properties of the soils analysed. Enzyme activity in the affected plots decreases significantly compared to the plots used as controls. In the physico-chemical properties, the decrease in total organic carbon content and related properties is noteworthy. The metal content was significant for antimony, arsenic, beryllium, cobalt and vanadium in some of the plots. The results show the existence of degradation associated mainly with soil management during the years of activity, rather than with soil contamination, although it is true that this cannot be ignored.Máster Universitario en Restauración de Ecosistemas (M194
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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