1,720,987 research outputs found
Numerical simulation and decomposition of kinetic energy in the Central Mediterranean: Insight on mesoscale circulation and energy conversion
No full textThe spatial and temporal variability of eddy and mean kinetic energy of the Central Mediterranean region has been investigated, from January 2008 to December 2010, by mean of a numerical simulation mainly to quantify the mesoscale dynamics and their relationships with physical forcing. In order to understand the energy redistribution processes, the baroclinic energy conversion has been analysed, suggesting hypotheses about the drivers of the mesoscale activity in this area. The ocean model used is based on the Princeton Ocean Model implemented at 1/32° horizontal resolution. Surface momentum and buoyancy fluxes are interactively computed by mean of standard bulk formulae using predicted model Sea Surface Temperature and atmospheric variables provided by the European Centre for Medium Range Weather Forecast operational analyses. At its lateral boundaries the model is one-way nested within the Mediterranean Forecasting System operational products. The model domain has been subdivided in four sub-regions: Sardinia channel and southern Tyrrhenian Sea, Sicily channel, eastern Tunisian shelf and Libyan Sea. Temporal evolution of eddy and mean kinetic energy has been analysed, on each of the four sub-regions, showing different behaviours. On annual scales and within the first 5 m depth, the eddy kinetic energy represents approximately the 60 % of the total kinetic energy over the whole domain, confirming the strong mesoscale nature of the surface current flows in this area. The analyses show that the model well reproduces the path and the temporal behaviour of the main known sub-basin circulation features. New mesoscale structures have been also identified, from numerical results and direct observations, for the first time as the Pantelleria Vortex and the Medina Gyre. The classical kinetic energy decomposition (eddy and mean) allowed to depict and to quantify the permanent and fluctuating parts of the circulation in the region, and to differentiate the four sub-regions as function of relative and absolute strength of the mesoscale activity. Furthermore the Baroclinic Energy Conversion term shows that in the Sardinia Channel the mesoscale activity, due to baroclinic instabilities, is significantly larger than in the other sub-regions, while a negative sign of the energy conversion, meaning a transfer of energy from the Eddy Kinetic Energy to the Eddy Available Potential Energy, has been recorded only for the surface layers of the Sicily Channel during summer. © Author(s) 2011. CC Attribution 3.0 License
Life history of an anticyclonic eddy in the Algerian basin from altimetry data, tracking algorithm and in situ observations
No full textFrequently-forming long-life mesoscale eddies are observed in the Algerian Basin that influence the circulation of the wider Western Mediterranean Sea. Most of these structures store and transport water masses including associated physical and biological properties throughout the entire basin. In order to study the evolution of a long-life anticyclonic eddy, we use a multiplatform approach based on remote sensing data analysis and in situ measurements. We present a case study of an anticyclonic eddy that persisted for 17 months within the basin. The feature was identified through a hybrid method of eddy detection and tracking applied to altimetry data, and sampled twice during two different oceanographic cruises in autumn 2004 and late spring 2005. Transect observations of potential temperature, salinity, density and the dissolved oxygen concentration were utilised to infer water mass properties and eddy characteristics. In situ data show that water of Atlantic origin, initially trapped by the eddy during its formation, was modified during the eddy lifetime. The time evolution of radius, kinetic energy and vorticity suggests dividing the eddy lifetime into three phases: the eddy formation, an intermediate period of high variability and a final, lower energy phase. The track followed by the eddy confirms the hypothesis of an interaction with the North Balearic Front and a consequent change of the eddy's physical properties. Decomposing the eddy's kinetic energy into mean and fluctuating terms allows us to describe its interaction with the mean circulation of the basin. In particular during formation, the southern part of the eddy absorbs energy from the mean circulation, while it provides energy to the mean flow in its northern part. In the second phase, when the eddy is far from the coast, it receives energy from the mean flow. Combining in situ data analysis with the results of the satellite-imagery-based detection and tracking method has proven to be a very useful method in assessing the evolution of a mesoscale structure in the Algerian Basin and its interaction with the large scale ocean dynamics of the Western Mediterranean Sea
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
RELATIONSHIPS BETWEEN CARBONATE SEDIMENTATION AND HYDRODYNAMICS ON THE TEMPERATE SHELF OF THE STRAIT OF BONIFACIO (WESTERN MEDITERRANEAN)
No full textThe sedimentary features of the inner-middle shelf of the strait of Bonifacio (western
Mediterranean) were analyzed to evaluate the relationship between the production and
transport of biogenic carbonate sediments and the basin morphology and hydrodynamics. A
three-dimensional hydrodynamic modeling was performed in order to simulate the influence
of waves and currents at the seabed level. Superficial sediments were collected at depths
ranging from 5 to 80 m and were analyzed for grain size, mineralogical composition and
skeletal carbonate composition. Shallow seismic data (3.5 kHz) were acquired to evaluate the
spatial distribution and architecture of sedimentary facies. Posidonia oceanica seagrass
meadows border the coasts in a narrow strip at both sides of the strait down to a depth of 40
m. In greater depths, the seabed is characterized by the presence of plateaus and ridges which
are controlled by outcropping bedrock morphology.
Waves and seabed currents are driven by the prevailing northwest and northeast winds. For
both wind directions, higher values for the seabed current velocity, associated with windstorm
events, were detected in shallower sectors and along an east–west-oriented belt that
connects the western Mediterranean and the Tyrrhenian Seas.
The sediments range from sand to gravel and show a mixed biogenic carbonate /siliciclastic
composition. This is due to the carbonate production associated with benthic ecosystems and
the mixing of modern carbonate with relict sediments.
Biogenic gravelly sands were found in association with P. oceanica seagrass meadows and
extended down to the circalittoral zone outside the deeper limit of the meadows. This
sedimentary facies was derived from the modern carbonate production associated with the P.
oceanica ecosystem. Sediments collected outside the deeper limit of the meadows were
identified as relict sediments deposited during the stand of the meadows at a deeper level
during lower sea-level conditions.
Maërl (free-living calcareous red algae) beds are the main carbonate factory and are mainly
located at the top of the rocky plateaus (at ~50-55 m) formed by the outcropping of the
bedrock. Downward, the increased currents at the seabed level in the east–west-oriented belt,
which connects the western Mediterranean and the Tyrrhenian Seas, limit the extension of this
carbonate factory. This results in a mixed sedimentary facies composed of biogenic carbonate
and relict siliciclastic sandy gravel.
Compared to other Mediterranean shelves, the strait of Bonifacio is characterized by a distinct
oceanographic setting. This is due to the connection between two basins. The currents at the
seabed play a crucial role in controlling the distribution of the carbonate factories
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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