1,720,955 research outputs found
Técnicas para la remoción de microcontaminantes de aguas residuales farmacéuticas
No full textLas aguas residuales a nivel mundial son alrededor de 1500 km3, seis veces más que el agua que existe en todos los ríos del mundo y solo son tratados el 20%, el resto son vertidos a cuerpos de agua; el creciente consumo de los productos farmacéuticos a nivel mundial es cerca de 300 millones de toneladas. El incremento exponencial de las concentraciones de fármacos en los cuerpos de agua, puede producir impactos negativos al ecosistema acuático y la salud del ser humano; porque son compuestos de ácidos y bases débiles, lo que indica que su comportamiento en el agua está condicionado por el pH, y la constante de acides Ka; por lo cual debe ser eliminado. La entrada de MCs al sistema acuático es a través del vertimiento de las aguas residuales y la ineficiente remoción de microcontaminantes por los sistemas de tratamiento convencional; por ende, se plantean distintas tecnologías avanzadas para la remoción de estos, entre los más resaltantes están las técnicas químicas, biológicas, técnicas combinadas y el uso de absorbentes naturales o biomasa de origen biológico natural
Evaluación del impacto de la acidificación en la calidad del agua de la quebrada Quilcayhuanca, Ancash, Perú
No full textEl retroceso glaciar expone rocas sulfuradas que en contacto con el aire y el agua son los que impulsan la meteorización in situ; en consecuencia, las condiciones de pH ácido y altas concentraciones de metales pueden presentarse en el agua, sedimento y el suelo. La finalidad de la investigación fue evaluar el impacto de la acidificación en la calidad del agua por el retroceso glaciar de la Quebrada Quilcayhuanca (Ancash, Perú). Se determinaron los parámetros físico-químicos y se evaluó la toxicidad del agua superficial (AS) y del elutriado del sedimento (ES) mediante los bioensayos con Lemna minor y Daphnia magna. Los resultados de los análisis físico-químicos fueron pH ≤4, conductividad eléctrica (CE) de 380 µS/cm y turbidez de 113 UNT. Las concentraciones de Cd, Pb, Ni y Zn superaron el Estándar de Calidad Ambiental (ECA) agua; mientras que As, Cd, Cu, Pb y Zn, la normativa canadiense de sedimentos; y Cd y As, el ECA suelo. Asimismo, se cuantificó las concentraciones en los que no se observaron efecto (NOEC) de ≤6,25% y 12,5% en las variables de clorosis, formación de hojas y número de frondas para L. minor; y para el peso seco solo en uno de los puntos. En el ensayo de D. magna se determinó una concentración efectiva media para inmovilidad (CE50-48h) de 43,55% y 51,14%, y una concentración letal media (CL50-48h) de 50% y 57,66% para ensayos con ES y AS. La toxicidad del agua por el retroceso glaciar de la Quebrada Quilcayhuanca (Ancash, Perú) es impulsada por el pH, metales pesados y oligoelementos
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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