1,720,956 research outputs found
Agronomic and Environmental Management of Phosphorus
No full text4 pagesThis archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu.Rehm, George; Lamb, John; Schmitt, Michael; Randall, Gyles; Busman, Lowell. (1998). Agronomic and Environmental Management of Phosphorus. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/94048
Proceedings of the 1st Agricultural Drainage and Water Quality Field Day
No full textStrock, Jeffrey S.; Baker, Jim; Busman, Lowell; Gupta, Satish; Moncrief, John; Randall, Gyles; Russelle, Michael; Taylor, Elwynn. (2002). Proceedings of the 1st Agricultural Drainage and Water Quality Field Day. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/208720
Phosphorus Transport to and Availability in Surface Waters
No full text4 pagesThis archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu.Randall, Gyles; Mulla, Dave; Rehm, George; Busman, Lowell; Lamb, John; Schmitt, Michael. (1998). Phosphorus Transport to and Availability in Surface Waters. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/94047
Behavior of polyphosphates in soils
No full textPolyphosphates differ significantly from orthophosphate with respect to their chemical properties. The adsorption by soils and clay minerals of a series of polyphosphates containing from 2 to 65 phosphate units was examined. The affinity coefficients of the Langmuir model and the intercepts of the Freundlich model indicated that soils have greater affinities for polyphosphates than for orthophosphate and generally greater affinities for pyrophosphate than other polyphosphates. The affinities of soils for ortho-, pyro-, and tri-phosphate were significantly correlated with the clay content, while the affinities of soils for longer polyphosphates were significantly correlated with dithionite-extractable Fe and Al contents. Increasing the temperature of equilibration from 15(DEGREES) to 45(DEGREES)C increased the adsorption of ortho-, pyro-, and tri-phosphate, but decreased the adsorption of long chain polyphosphate (P(,35)). Trimetaphosphate (TMP) was not adsorbed by soils;A method was developed for determination of TMP in the presence of other inorganic P compounds added to soils. Use of this method in studies of enzymic and nonenzymic hydrolysis of TMP in soils showed that the optimum buffer pH (0.1 M Tris) for trimetaphosphatase activity in soils occurred at pH 8, whereas the nonenzymic hydrolysis of TMP generally increased with pH. Maximum trimetaphosphatase activity occurred in soils at an incubation temperature of 40(DEGREES)C. The nonenzymic hydrolysis of TMP increased with temperature up to 80(DEGREES)C, and with addition of Ca and Mg. Studies of the kinetic parameters of trimetaphosphatase activity in 3 soils showed that the K(,m) values of this enzyme ranged from 6.3 to 7.2 mM TMP. The average energy of activation for the enzymic hydrolysis of trimetaphosphatase in soils was 21 kJ/mole as compared with 32 kJ/mole for the nonenzymic hydrolysis. The inhibition of this enzyme by phosphate and its analogs and by EDTA showed noncompetitive kinetics. The enzyme was stable up to 3 months when soil samples were stored at 5(DEGREES)C;Trimetaphosphatase activity of soils was significantly correlated with the organic C and clay contents of 28 Iowa surface soil samples. It decreased with depth in four soil profiles examined. The nonenzymic hydrolysis of TMP was significantly correlated with soil pH, organic C, water-extractable Ca and Mg contents of soils.</p
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
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