1,721,000 research outputs found
Role of abiotic stress factors from natural and anthropogenic sources in plant-environment interaction
No full textAbiotic stressors can originate from either nature or humans and affect plants in their open environments. Heat, sunlight, drought, and soil salinity are examples of natural stressors; heavy metals, organic compounds, particulate matter, inorganic gases, and micro and nanoplastics are examples of anthropogenic stressors. Plants may physiologically and biochemically react to these stresses by, for example, producing reactive oxygen species (ROS), altering the pH of their leaves, and changing their shape. At its most severe, it can stunt plant development, harm plant tissues, and even kill plants. Plants, on the other hand, can be useful in phytoremediation as both bioindicators and resilient species. Environmental pollution, contamination, and stress-induced changes to bioactive compounds must be considered whenever plants are considered for their micronutrient content or medicinal properties
Presenza e distribuzione delle Terre Rare nei sedimenti superficiali dell’Alto Adriatico
No full textI sedimenti rappresentano la principale sede di accumulo di specie chimiche organiche ed inorganiche
veicolate dalle acque fluviali alle aree marino-costiere. Svariati sono gli studi incentrati sulla geochimica
dei sedimenti in termini di presenza, distribuzione e mobilità di contaminanti organici ed elementi in tracce
potenzialmente tossici (Covelli et al., 2001). Tuttavia, poche sono le informazioni ad oggi esistenti relativamente
a quelli che vengono definiti contaminanti emergenti, tra cui rientrano gli elementi delle Terre Rare (Rare Earth
Elements, REE).
Le REE comprendono 17 elementi metallici che includono l’intera serie dei lantanidi, unitamente allo
scandio (Sc) e all’ittrio (Y) e vengono generalmente distinte in REE leggere e pesanti (LREE, HREE) in
funzione del peso atomico. Nonostante siano definiti rari, questi elementi sono piuttosto diffusi nella crosta
terrestre e ampiamente utilizzati in attività agricole, ospedaliere e in ambito industriale per la produzione di
svariati dispositivi tecnologici di uso quotidiano.
Per queste ragioni, la loro presenza in diverse matrici ambientali quali sedimenti, acque eparticellato in
sospensione, è spesso oggetto di studio da parte della comunità scientifica internazionale. Infatti, le REE
possono essere utilizzate come traccianti di fenomeni naturali, come processi erosivi, ma anche di attività
antropiche (Viers et al., 2009; Piper and Bau, 2013; da Silva et al., 2018).
Questo studio si pone come obiettivo una valutazione preliminare della presenza e distribuzione delle REE
nei sedimenti superficiali dell’Alto Adriatico, rappresentativi di un’area compresa tra il Golfo di Trieste e il
delta del fiume Po. Questi sedimenti sono stati oggetto di una precedente indagine sulla contaminazione da
metalli pesanti e da idrocarburi nei sedimenti superficiali dei mari italiani (CoNISMa, 2001). Di conseguenza,
il presente studio si propone di ampliare le informazioni già esistenti allo scopo ultimo di valutare l’origine
di questi elementi unitamente alla presenza di eventuali anomalie nelle concentrazioni delle REE dovute a
potenziali contributi antropici
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
Characterization of variability of air particulate matter size profiles recorded by optical particle counters near a complex emissive source by use of Self-Organizing Map algorithm
No full textIn the present study we propose the application of a procedure of data analysis based on the Self-Organizing Map algorithm and k-means clustering in series (1st level and 2nd level abstraction respectively) as a strategy to identify recurrent ambient air particulate matter (PM) size profiles starting from the elaboration of high frequency data recorded by an Optical Particle Counter (OPC). We tested the strategy on data deriving from a three months survey at a residential site in proximity to an integral cycle steel plant in Trieste (NE Italy). We were able to identify four clusters representing recurrent PM class profiles whose meaning has been interpreted and confirmed by correlation to “external data”, i.e. data not used to build the model, registered by other devices (meteorological and pollutant monitoring stations). The four clusters were found to be related to two different plant type of emissions (sources) and to two different site background profiles, respectively. The powerful visualization features of SOM map allowed to describe and characterize the variability of size distribution of PM in a concise form. The clustered SOM being built for one measuring station, proved to be helpful for the analysis of OPC data collected at another location close to the industrial plant. Moreover, occasional episodes of Saharan dusts could be identified as outliers with respect to local particulate and discussed in terms of size distribution. Eventually, by means of an animated graph, we propose a method to visualize the PM experimental data evolution during the day using the PM cluster profiles as a legend. © 201
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
Optical particle counter data collected in two inhabited sites close to an industrial hot spot during a three months survey
Full text linkData on this paper describe the monitoring of different size ranges of particulate matter on dwellings positioned close to an integral cycle steel plant. Data were collected by eight channel (PM0.3, PM0.5, PM0.7, PM1, PM2, PM3, PM5, PM10) optical particle counters positioned in two sites. The data were recorded as counts-per-minute for every size channel in a three months survey from June to September 2015. Basic statistical elaboration and boxplot graphs as well as raw data are included
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