1,720,989 research outputs found
Ecologia e Società. Atti del Convegno per la celebrazione del XXV anniversario di fondazione della Società Italiana di Ecologia
No full textModificazioni fissiologiche e proteiche in talli di Evernia prunastri (L.) Ach. esposti a differente intensità di traffico veicolare
No full textI licheni rappresentano un eccellente modello per lo studio della distribuzione
degli elementi in traccia in ambiente urbano, tuttavia sono disponibili
informazioni limitate sui meccanismi molecolari che si verificano nei talli in
seguito ai processi di bioaccumulo. Questo lavoro ha avuto come obiettivo lo
studio della concentrazione degli elementi in traccia e dei cambiamenti nei
parametri fisiologici e nel proteoma in talli di Evernia prunastri (L.) Ach.
esposti per 7 giorni nell’area urbana e peri-urbana di Siena. Le stazioni
campionate sono state sei fisse e una mobile (autobus), oltre a una stazione
di controllo. Gli elementi in traccia considerati sono stati suddivisi in tre
classi, ovvero elementi maggiormente legati al traffico veicolare, elementi la
cui sorgente prevalente è il traffico veicolare e elementi la cui origine è
fondamentalmente litogenica. I risultati hanno mostrato l’influenza
dell’intensità del traffico veicolare sull’accumulo degli elementi in traccia e un
effetto dell’accumulo degli elementi in traccia sul contenuto dei pigmenti
fotosintetici nei talli esposti, mentre non sono stati rilevati danni alle
membrane cellulari. Dall’analisi proteomica dei campioni esposti è emerso
come il quantitativo di proteine strutturali (A-actina e Tubulina), funzionali
(RuBisCo) e di stress (HSP70, CP450 e TGasi) vari in maniera non lineare con
la concentrazione degli elementi in traccia nei talli. Questo lavoro ha
dimostrato come l’approccio proteomico rappresenti una valida integrazione
allo studio dei parametri ecofisiologici degli organismi esposti in studi di
biomonitoraggio ambientale
Influenza della temperatura sulle cinetiche di accumulo di Hg° in tre specie licheniche
No full textLo scopo di questo lavoro è stato quello di definire, utilizzando talli di Evernia prunastri (L.) Ach., Pseudevernia furfuracea (L.) Zopf. e Xanthoria parietina (L.) Th.Fr. i meccanismi di accumulo di Hg° propri delle tre specie, la loro correlazione fra la concentrazione in aria di Hg° e le relative velocità di accumulo a diverse concentrazioni di esposizione a tale metallo e definire gli effetti della temperatura sulla loro velocità di accumulo di Hg°. Sono state condotte quattro cinetiche di accumulo di mercurio alle concentrazioni di esposizione di 9,3, 15,8, 31, 45,1 μg/m3, alla temperatura di 20 °C e due cinetiche di accumulo alle temperature di 10 e 30 °C, alla concentrazione di esposizione di 46 μg/m3. I risultati hanno confermato quanto già osservato in studi precedenti su E. prunastri ed hanno mostrato una differente velocità di accumulo per le altre due specie licheniche. I risultati hanno evidenziato una minore velocità di accumulo per il lichene E. prunastri, una velocità intermedia per il lichene X. parietina ed una velocità nettamente maggiore per il lichene P. furfuracea. Gli esperimenti di cinetica condotti a diverse temperature hanno mostrato un effetto importante di tale parametro sulla velocità di accumulo per le specie E. prunastri e P. furfuracea mentre per X. parietina non si sono avute differenze apprezzabili
Meccanismo d'azione di N-amilxantato di potassio: studi a livello della membrana plasmatica
No full textMapping mercury vapours in an abandoned cinnabar mining area by azalea (Azalea indica) leaf trapping
No full textVapour levels of metallic mercury in the atmosphere of an abandoned mercury mine and distillation plant at Abbadia S. Salvatore (Mount Amiata, Tuscany, Italy) were detected by means of the mercury accumulation rate in leaves of azaleas located in 100 sampling sites. The response of azalea leaves to a constant mercury concentration in the air (30 ng/L) was calibrated in the field, in relation to indoor conditions. No significant methylation of mercury was found to occur in spontaneous vegetation or contaminated azalea samples. The volatilization of mercury at different temperatures and the use of bioconcentrators to detect mercury vapours in contaminated areas is discussed. © 1994
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
Influence of angular exposure and proximity to vehicular traffic on the diversity of epiphytic lichens and the bioaccumulation of traffic-related elements
Full text linkThis study investigated the influence of angular
exposure and distance from vehicular traffic on the diversity
of epiphytic lichens and the bioaccumulation of traffic-
related elements in a town of central Italy. An Index of
Lichen Diversity (ILD) was calculated on the street-facing
and the opposite side of road-lining trees and in a urban park
250 m away, and the content of selected trace elements (Al,
Ba, Ce, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, V, and Zn) was
determined in samples of the lichen Punctelia borreri (Sm.)
Krog growing on tree bark, both on the exposed and opposite
sides. ILD increases with distance from traffic emissions.
However, at the site with vehicle traffic, non-nitrophilous
lichens decreased while nitrophilous ones increased. The con-
centration of the traffic-related elements Ba, Cr, Cu, Mn, Sb,
and Zn accumulated in thalli of P. borreri was higher on
roadside trees than in trees from the urban park. ILD was
not affected by the angular exposure to the road and the
bioaccumulation of traffic-related elements was similar in
lichens from the side of the bole exposed to traffic emissions
and particulate resuspension and from the opposite side. The
angular exposure in respect to the traffic source does not
influence trace element accumulation. These results are im-
portant when using lichens for biomonitoring purposes, both for planning future studies and for the reliability of the inter-
pretation of past surveys that do not report information about
the angular exposure of the collected lichen material
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