130,388 research outputs found
Using remote sensing indicators to investigate the association of landings with fronts: Application to the Alboran Sea (western Mediterranean Sea)
No full textThis study examined links between the variability of coastal front features and composition of fishery landings. Satellite-derived sea surface temperature data allowed the detection of thermal fronts and calculation of front metrics that account for gradient, persistency, and vicinity. Landings data were clustered by functional group (according to habitat use, size, morphology), and trophic level (TL). Three independent time series analyses, based on two different classes of statistical methodologies, were carried out: (i) correlation analysis performed on species aggregated by functional groups, and (ii) compositional analysis performed on the top five species landed and on species aggregated by trophic level. Analyses were carried out for the Moroccan coast of the Alboran Sea (western Mediterranean Sea). Results of the proposed type of application were discussed with respect to their potential for improving scientific knowledge and management of fisheries in data-poor areas. Pelagic landings were associated with front indicators in two-thirds of tested cases. The results demonstrated a markedly different association between landings and front features in the Nador fishing zone, relative to M'diq and Al Hoceima. Improved performance of the front gradient and persistence indicator was detected, with respect to the front gradient only for flatfish and demersal landings. Compositional data regression outlined a different role for Sardina pilchardus and Trachurus trachurus in the Al Hoceima and M'diq landings, and in the latter case the dominance of these two species in the landings seemed to respond to the front density indicator. A decreasing trend in TL > 3.5 landings was detected with increasing front distance
An Ecosystem Approach for understanding status and changes of Nador lagoon (Morocco): application of food web models and ecosystem indices
No full textThe work applies food web models to the Lagoon of Nador (Morocco) and subsequently estimates ecosystem indices. This effort supports the evaluation of the ecosystem status and the implementation of the Ecosystem Approach (EcAp), endorsed by the contracting parties of the Barcelona Convention for the Mediterranean Sea. The Lagoon of Nador, on the Mediterranean coast of Morocco, suffered from eutrophication during recent decades. We used indices derived from Ecological Network Analysis for investigating the most relevant features of ecosystem functioning in the decade 2000-2010 (present scenario), and comparing them with those of the 1980s (past scenario). As the Lagoon includes different habitats, the methodology was applied to each of them, in order to assess their contribution to the functioning of the whole ecosystem. Results highlighted an increase in Total System Throughput (TST) in the present scenario when compared with the past one, also associated to an increase of Total Respiration (TR) and of the ratio between Total Primary Production and Total Respiration (TPP/TR). Under the present scenario Nador lagoon shows a decreased cycling efficiency. The sensitivity analysis highlighted the capability of TST and Comprehensive Cycling Index (CCI) in detecting changes, in agreement with other recent studies on responses of food web functioning to eutrophication. The results are discussed in respect to three specific aspects, related with the application of food Web Models and Ecological Network Analysis in the EcAp context: i) data availability; ii) spatialization of indicators; iii) selected set of indicators. The results also highlight the important role of sensitivity/uncertainty analysis when implementing food web models in data-scarce systems. (C) 2016 Elsevier Ltd. All rights reserved
An overview of Neogene brackish leptocytherids from Italy and Spain: Biochronological and palaeogeographical implications
No full textAn overview of the Neogene euryhaline leptocytherids from Italian and Spanish basins is reported, together with their
chronological and geographical distributions. Eight genera (or subgenera) have been considered: Mediocytherideis s.s., M.
(Sylvestra), Chartocythere, Leptocythere, Tavanicythere, Amnicythere, Euxinocythere s.s. and E. (Maeotocythere). The study
has shown that these leptocytherids could be a valuable biochronological tool in both marginal marine and the athalassic saline
environments, since, even at generic level, they show separate temporal distributions. For example, the presence of Chartocythere
and Euxinocythere s.s. in the Mediterranean seems to be limited to the Late Serravallian; Tavanicythere seems to have
been exclusively distributed during the Late Miocene, with different species spanning the Late Tortonian and Early Messinian;
M. (Sylvestra) seems to attain its maximum diversity in the same time-interval; the widespreading of Amnicythere and E.
(Maeotocythere) in the Mediterranean marks the Latest Messinian lago-mare event (about 5.5–5.3 Ma); the important radiation
of Leptocythere characterises the Pliocene. Moreover, a comparative analysis between Neogene Mediterranean and Paratethyan
leptocytherids has shown that the geographical and stratigraphical distribution of the eight genera analysed matches the
palaeogeographic events that affected the Peri-Tethyan realm during Neogene
Geoquímica de los sedimentos de playas entre Fnideq y M'diq (Tetuán, NE de Marruecos).
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MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Coastal risk modelling for oil spill in the mediterranean sea
No full textThe accident probability estimation and the consequence analysis are based on statistical data about oil spill accident occurrence in the Mediterranean area, on the probability of different release sizes, and on the joint probability of wind speed and directions. The risk model and its evaluation have been assessed for the Mediterranean littoral considering the time required by the oil slick to hit the coast in specific sensible target points assuming that an oil release accident potentially occurred in an accident sites located along the ship routes. This approach has been applied on the area of the Strait of Gibraltar, which supports a significant volume of maritime traffic because it represents the navigational connection channel between the Atlantic Ocean and the Mediterranean Sea
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
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