1,721,029 research outputs found
Heavy metal modelling study over Italy: Effects of grid resolution, lateral boundary conditions and foreign emissions on air concentrations
No full textHeavy metals (HMs) are pollutants that have both anthropogenic and natural sources. In the last decade, the European Commission (EC) has imposed limit and target values for some of them that are toxic both for humans and for the environment. This study aims to assess the HM concentrations over Italy by means of the atmospheric modelling system (AMS) of the MINNI project. The AMS is based on the chemical transport model (CTM) FARM. The sensitivity of model simulations to horizontal grid resolution, lateral boundary conditions and the contribution of emissions from neighbouring countries has been also evaluated. The simulations have been carried out for the year 2005 considering a spatial resolution of 20 km over the Italian domain and 4 km over northern Italy (Po Valley). The CTM has been extended to take into account the HMs considered by EC directives such as arsenic (As), cadmium (Cd), nickel (Ni) and lead (Pb). Both anthropogenic and natural emissions have been considered in this study. Model results have been compared with available observations. Results show realistic concentration of HMs and suggest the importance of using boundary conditions, while foreign emissions have less impact. In addition, the present work highlights the necessity of more observations in space and time for a comprehensive validation of the model. High-resolution simulation gives more realistic pattern with respect to the low-resolution one for the highly polluted areas. However, future improvements require a better knowledge of the space/time distribution of the emissions, currently not available. © 2015 Springer International Publishing Switzerland
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
The termophilous species Echinolittorina punctata as a new descriptor of tropicalization in the Mediterranean Sea - first data.
No full textThe termophilous species Echinolittorina punctata as a new descriptor of tropicalization in the Mediterranean Sea - first data.
No full textData suggest that the prosobranch gastropod Echinolittorina punctata (Gmelin, 1791) (Mollusca, Gastropoda) has extended its range northwards along the Italian coastline due to climate variability in marine conditions. Its ease of identification and mesolittoral habitat suggest this species may be a new practical indicator of Mediterranean Sea changing conditions, easy to monitor
The thermophilous species Echinolittorina punctata as a new descriptor of tropicalization in the Mediterranean Sea - first data
No full textData that suggest that the prosobranch gastropod Echinolittorina punctata (Gmelin, 1791) (Mollusca, Gastropoda) has extended its range northwards along the Italian coastline due to climate variability in marine conditions. Its ease of identification meolittoral habitat suggest this species may be a new practical indicator of Mediterranean Sea changing conditions, easy to monitor
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
Impact of Multi-altimeter Sea Level Assimilation in the Mediterranean Forecasting Model
No full textIn this article the impact of multisatellite altimeter observations assimilation in a high-resolution Mediterranean model are analyzed. Four different altimeter missions [Jason-1, Envisat, Ocean Topography Experiment (TOPEX)/Poseidon interleaved and Geosat Follow-On] are used over a 7-month period (from September 2004 to March 2005) to study the impact of the assimilation of one to four satellites on the analyses quality. The study highlights three important results. First, it shows the positive impact of the altimeter data on the analyses. The corrected fields capture missing structures of the circulation, and eddies are modified in shape, position, and intensity with respect to the model simulation. Second, the study demonstrates the improvement in the analyses induced by each satellite. The impact of the addition of a second satellite is almost equivalent to the improvement given by the introduction of the first satellite: the second satellite’s data bring a 12% reduction of the root-mean-square of the differences between the analyses and observations for the sea level anomaly (SLA). The third and fourth satellites also improve the rms, with a more than 3% reduction for each of them. Finally, it is shown that Envisat and Geosat Follow-On additions to Jason-1 impact the analyses more than the addition of TOPEX/Poseidon, suggesting that the across-track spatial resolution is still one of the important aspects of a multimission satellite observing system. This result could support the concept of multimission altimetric monitoring done by complementary horizontal resolution satellite orbits
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
Micro-scale dispersion modelling with background correction to simulate air quality in Milan
Full text linkLa qualità dell'aria in ambiente urbano sta sollevando grande interesse negli ultimi anni, per lo studio sia dell'impatto dell'inquinamento sulla salute umana che delle le cause dei superamenti periodici dei limiti di legge nelle zone urbane. Questo è un problema ad alta risoluzione che deve quindi essere affrontato con modelli di dispersione ad alta risoluzione. Purtroppo con gli strumenti di calcolo di cui disponiamo oggi, questi modelli non possono tener conto di aree molto estese (non più di pochi chilometri) o di lunghi periodi di tempo (non più di pochi giorni) e della reale complessità delle reazioni
chimiche in atmosfera a causa del loro approccio lagrangiano. In questo studio abbiamo esaminato la possibilità di introdurre il modello Micro-Swift-Spray (MSS) nella catena modellistica AMS-MINNI, realizzando un esperimento per studiare l'idoneità del modello di dispersione chimica regionale di AMSMINNI (FARM) come fornitore delle concentrazioni di fondo necessarie ad MSS. I risultati di questo esperimento indicano che su una media giornaliera la correzione del fondo fornita da FARM migliora notevolmente le prestazioni del MSS rispetto alle misure di una stazione di traffico. Nonostante questo
le prestazioni orarie di tale correzione non sono altrettanto incoraggianti, e la causa è probabilmente da ricercare nelle ipotesi comunemente fatte in sede di preparazione dei dati di emissione che alimentano il modello MSS.Urban air quality is raising great interest in recent years, for studying both the impact of pollution on human health and the causes of periodic pollution exceedances in urban areas. This is a “high resolution” problem that has to be treated with high resolution dispersion models. Unfortunately with the present day computational facilities, these models cannot take into account large areas (more than few kilometers) or long periods (more than few days) and the real complexity of atmospheric chemical reactions due to their Lagrangian approach. Here we studied the feasibility of introducing the model
Micro-Swift-Spray (MSS) in the AMS-MINNI air quality chain, setting up an experiment to study the suitability of the regional component of AMS-MINNI (FARM) as a background provider for MSS. The results of this experiment indicate that on a daily average the background correction provided by FARM greatly improves the performance of MSS compared to traffic air quality station measurements. On the other hand the hourly performance of this correction is not as encouraging, but it is probably due to some common assumptions made in the preparation of the emission data that feed the MSS
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