1,721,326 research outputs found
Phytotoxicity to and uptake of flumequine used in intensive aquaculture on the aquatic weed Lythrum salicaria L.
Full text linkPhytotoxicity of Flumequine on the aquatic weed Lythrum salicaria L. was determined by two laboratory models: a single concentration test, by which the effects of 100 mg l(-1) were evaluated after 10, 20, 30 days and a multiple concentration test, by which the effects of 5000-1000-500-100-50 mu g l(-1) were evaluated after 35-day exposure. 100 mg l(-1) are highly toxic and significantly decrease the growth of plants; this effect increases with time. Concentrations between 5000 and 50 mu g l(-1) induced hormesis in plants, by significantly increasing mean number and dimension of leaves and secondary roots. The effect is the highest at 50 mu g l(-1) and decreases with increase in concentration. Both toxic effect and hormesis can be related to plant drug uptake, quite high, in the order of mu g g(-1). The ecological implication of Flumequine contamination in aquatic environments and the possible use of Lythrum salicaria for bioremediation and/ or monitoring technique are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved
Redox state of magmas and granite-related Mo mineralization: evidences from Late Variscan F- bearing granites from Southern Sardinia (Italy)
No full textRedox state of magmas has been invocated to explain the metallogenic behaviour of intrusive magmatism (Ishihara,
1981). Thus, Sn deposits are linked to low-fO2, ilmenite series, while Mo deposits are better bracketed into high-fO2,
magnetite series. In Variscan Europe Mo deposits are represented in a few districts, including Eastern Erzgebirge,
France and Sardinia. In Sardinia, small Mo deposits are related to a post-collisional F-bearing granite suite dated close
to 290 Ma by Re/Os on molybdenite (Boni et al., 2003) and 40Ar/39Ar on biotite (Dini et al., 2005). This late Variscan
suite is dominated by metaluminous biotite leucogranites grading to hololeucratic microgranitic to granophyric
varieties; amphibole biotite monzogranites are locally observed (Monte Sette Fratelli). They emplaced at shallow crustal
levels and locally (Ogliastra) grade to felsic volcanics. Thermal effects of the intrusions are limited to narrow contact
aureolas (andalusite zone) around the plutons. In SW Sardinia (Sulcis and Monte Linas intrusions), both Mo and Sn
deposits occur. Magmatic bodies show a distinctive magmatic zonation, with medium-grained granites dimembered
upward by thick, flat-lying fine-grained to porphyritic varieties, including fayalite-bearing pegmatite layers. Finegrained
to porphyritic rocks suffered various degrees of greisening, and host Mo ores, related to numerous small endoand
exo- quartz-muscovite greisens (e.g. Perda Lada), grading to quartz vein and stockwork systems (Perd'e Pibera, Su
Seinargiu, Flumini Binu). Ores are commonly dominated by molybdenite, with subordinate pyrite, chalcopyrite and
wolframite. The studied deposits are related to ilmenite rock -series, as evidenced by petrography (opaque contents of
granites <1%; ilmenite>>magnetite), and confirmed by geochemical ratios (Rb/Sr, FeO/Fe2O3, K/Rb). This behavior
seems to contrast with the Mo/magnetite series association, and is more coherent with the presence of Sn vein deposits
in the same areas (Naitza et al. 2015). A possible explanation involve changes of physicochemical parameters (in
particular, fO2 and HF activity) from magmatic processes during magma emplacement to greisening; variation of redox
conditions are confirmed by discontinuous reverse zoning of plagioclase laths in fine-grained facies, indicating a
progressive PH2O increase with magmatic evolution. Mineralization prevalently occurred in close system conditions,
although in some areas (Oridda, Su Seinargiu, Flumini Binu) Mo ores are centered on bodies of porphyritic rocks,
showing features close to porphyry-style mineralization (Fiori et al., 1986).
Boni M., Stein H.J., Zimmerman A. & Villa I.M. 2003. Re-Os age for molybdenite from SW Sardinia (Italy): a
comparison with 40Ar/39Ar dating of Variscan granitoids. In: Eliopulos K. et al., Eds., Mineral exploration and
sustainable development. Millpress, Rotterdam, 247-250.
Dini A., Di Vincenzo G., Ruggieri G., Rayner J. & Lattanzi P. 2005. Monte Ollasteddu, a new gold discovery in the
Variscan basement of Sardinia (Italy): first isotopic (40Ar-39Ar, Pb) and fluid inclusion data. Miner. Deposita, 40,
337-346.
Fiori M., Garbarino C., Padalino G. & Masi U. 1986. Chemical features of wallrocks from Mo-showings of Sardinia
(Italy). Rend. Soc. It. Mineral. Petrol., 41, 25-39.
Ishihara S. 1981. Granitoid series and mineralization. Economic Geology, 75th anniversary volume, 458-484.
Naitza S., Secchi F., Oggiano G. & Cuccuru S. 2015.
Phytotoxicity to and uptake of enrofloxacin in crop plants
No full textPhytotoxicity of enrofloxacin on crop plants Cucumis sativus, Lactuca sativa, Phaseolus vulgaris and Raphanus sativus was determined in a laboratory model: the effect of 50, 100 and 5000 mug 1(-1) were evaluated after 30 days exposure by measuring post-germinative growth of primary root, hypocotyl, cotyledons and leaves. Concentrations between 50 and 5000 mug 1(-1) induced both toxic effect and hormesis in plants, by significantly modifying both length of primary root, hypocotyl, cotyledons and the number/length of leaves. A toxic effect is induced by high concentration (5000 mug1(-1)), while hormesis occurs at low concentrations (50 and 100 mug 1(-1)). A continuum between toxic effect and hormesis is found in the four plant species. Both toxic effect and hormesis can be related to an efficient plant drug uptake, in the order of mug g(-1). Plants are able to metabolize enrofloxacin into ciprofloxacin, as also happens in animals; Cucumis, Lactuca and Phaseolus biologically convert about one quarter of stored enrofloxacin. The ecological implication of enrofloxacin contamination in terrestrial environments is discussed. (C) 2003 Elsevier Science Ltd. All rights reserved
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
- …
