1,720,974 research outputs found
Structure of a protozoan community in a percolating filter
No full textStructural factors of the microbial community of a percolating filter have been investigated. The presence of some ciliate species has been related to physico-chemical and plant operational variables by means of ordination procedures. In an 87-d study period, large variations in density of some species were observed. A limited number of environmental parameters strongly affect ciliate community composition. Major structural factors are sloughed biofilm wasting and nitrogen loading: both induce disturbance and make the community revert to a less mature phase. Moderate disturbance episodes reduce the effectiveness of competitive mechanisms. © 1994 Taylor & Francis Group, LLC
Ion Chromatographic Determination of Sulfide and Cyanide in Real Matrices by Using Pulsed Amperometric Detection on Ag Electrode
No full textThe determination of free sulfide and cyanide by pulsed amperometric detection (PAD) at a silver-working electrode was improved through a deep de-oxygenation (at least 10 min) of both standard and real solutions containing the two analytes and adopting a two-potential waveform
able to eliminate Ag working electrode fouling. The waveform stepped around the oxidation of Ag in the presence of 0.1–0.4 M hydroxyl ion,
from −0.1 to 0.1 V versus saturated calomel electrode (SCE). The eluent composition (0.4M NaOH plus 7.5mM oxalate solution) allowed a very good column efficiency and selectivity. The presence of a polysulfide species was hypothesized in sulfide solutions that had not been
de-oxygenated and aged. The polysulfide eluted just before sulfide and was confirmed by a chemical test with SO3 2− producing the elimination of the polysulfide peak. Detection limits, according to the Hubaux–Vos method, were 1.0 and 2.0 μg/l for S2− and CN−, respectively. We demonstrated good performance of the optimized method by repeatedly injecting standard solutions and by analyzing different real matrices. The method exhibited very good accuracy and repeatability (10 μg/l and a 500 μl injection loop, had a repeatability better than 3% for sulfide and 100 μg/l had a repeatability better than 1% for cyanide). The two-potential waveform ensured long-term stability of the electrode surface
that required no manual polishing procedure for at least 1 month (20 analysis per day)
Controllo di aria ambiente nei laboratori fotografici: valutazione di alcuni composti mediante microHPLC
No full text
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
- …
