Search results for "feature"
showing 10 items of 4091 documents
Search strategies for ensemble feature selection in medical diagnostics
2003
The goal of this paper is to propose, evaluate, and compare four search strategies for ensemble feature selection, and to consider their application to medical diagnostics, with a focus on the problem of the classification of acute abdominal pain. Ensembles of learnt models constitute one of the main current directions in machine learning and data mining. Ensembles allow us to get higher accuracy, sensitivity, and specificity, which are often not achievable with single models. One technique, which proved to be effective for ensemble construction, is feature selection. Lately, several strategies for ensemble feature selection were proposed, including random subspacing, hill-climbing-based se…
Tidal notches, coastal landforms and relative sea-level changes during the Late Quaternary at Ustica Island (Tyrrhenian Sea, Italy)
2017
In this paper we present and discuss data concerning the morphostructural evolution at Ustica Island (Tyrrhenian Sea, Italy) during Late Quaternary. New insights on the relative sea-level changes of Ustica are coming from data collected during a geomorphological field survey around the island, together with the bathymetric analysis of the surrounding seabed and 14C datings on samples of speleothems, flowstones and marine shells found inside three selected sea caves. The survey was mainly accomplished on June 2015 through the first complete snorkel investigation off the about 18 km-long volcanic coast of the island, which allowed to precisely define location, relationship and morphometric fe…
Mount Etna volcano (Italy) as a major “dust” point source in the Mediterranean area
2016
Volcanic emissions represent one of the most relevant natural sources of trace elements to the troposphere. Due to their potential toxicity, they may have important environmental impacts from local to global scale. They can also severely affect the atmospheric and terrestrial environment at timescales ranging from a few to millions of years. Mt. Etna volcano is known as one of the largest global contributors of magmatic gases (CO2, SO2 and halogens) and particulate matter, including some toxic trace elements. The aim of this study is to characterize the chemical composition and the mineralogical features of the volcanogenic aerosol passively emitted from Mt. Etna. Twenty-five samples were c…
Physiography of the Sicilian region (1:250,000 scale)
2015
Physiographic maps summarize and group the landforms of a territory into homogeneous areas in terms of kind and intensity of the main geomorphological process. These maps are often produced at semi-detailed scales, while examples at the regional scale are much less common. However, because the region is the main administrative level in Europe, physiographic maps can be very useful for land planning in many fields, such as ecological studies, risk maps, and soil mapping. This work presents a methodological example of a regional physiographic map, compiled at a 1:250,000 scale, representing the whole Sicilian region, the largest of the Mediterranean islands. The physiographic units were class…
Residence Time Analysis in the Albufera of Valencia, a Mediterranean Coastal Lagoon, Spain
2021
The Albufera of Valencia is a coastal lagoon located in the western area of the Mediterranean Sea, in the Iberian Peninsula. It has an area of 23.1 km2 and an average depth of only 1 m, with a maximum depth of 1.6 m. This lagoon is the remnants of an original and more extensive wetland of about 220 km2 which is now mostly dedicated to rice cultivation. Surface water is supplied through several main and many secondary canals for a total of 64 water entry points and three exit points to the sea. It is difficult to evaluate the residence time due to the lack of reliable measurements of the inflow or outflow, as well as continuous measurements. Between 1988 and 2018, several procedures were use…
Morphometric and hydraulic geometry assessment of a gully in SW Spain
2016
Abstract Gully erosion represents one of the most significant types of land degradation in the Mediterranean areas, giving place to important on- and off-site effects. In this paper, a second-order gully located in SW Spain is analyzed. Along the gully, 28 cross-sections were established and measured with a Leica TCRM1102 laser total station, approximately every 6 months from 2001 to 2007. The sections were located at variable distance, placing them in areas where active erosion was evident. In total, 13 field measurements were carried out, and the geometric characteristics of 28 cross-sections were obtained. Morphometric analyses were carried out in both the main gully and a tributary reac…
Urban growth (1956-2012) and soil sealing in the metropolitan area of Valencia (Eastern Spain)
2019
[EN] The aim of this study is to understand the urban growth dynamics from the mid-1950s to 2012 in the Metropolitan Area of Valencia, eastern Spain, and its impact on soils. The study area is a very interesting example of the many changes in land use and land cover in the landscape of Mediterranean alluvial plains. The analysis of urban growth was based on photo interpretation of aerial photographs and GIS based methodology. At a detailed scale (1:10,000), results show that there has been a highly dynamic process produced by the extent of land developed as urban area. In 1956 only 3,441 hectares (9.3% of the overall study area) were occupied by urban use. In 2012 the total sealed surface w…
Corema album archaeobotanical remains in western Mediterranean basin. Assessing fruit consumption during Upper Palaeolithic in Cova de les Cendres (A…
2019
[EN] Information about plant gathering by Palaeolithic hunter-gatherers in Europe is scarce because of the problems of preservation of plant remains in archaeological sites and due to the lack of application of archaebotanical analysis in many of them. Botanical macroremains wood charcoal, seeds, fruits, leaves, etc. - provide information not only about palaeoeconomy of hunter-gatherers, but also about climate, landscape and vegetation dynamics. In Gravettian and Solutrean levels of Cova de les Cendres (Alicante, Spain), Corema album pyrenes (Empetraceae or crowberries family) have been identified. On the contrary, wood charcoal of this species has not been documented among the remains of f…
Maximum flood area during MIS 1 in the Almenara marshland (Western Mediterranean): Benthic foraminifera and sedimentary record
2018
The sedimentological and micropaleontological analysis of three mechanical cores in the marshland of Almenara (Valencian Community, Spain) has allowed the reconstruction of the Holocene evolution of this wetland. The cold and dry 8.2-ka event might be represented in Almenara by a massive carbonate precipitation bed, upon which mid- and late-Holocene sediments were subsequently deposited. The direct influence of sea-level changes has been recorded in the two cores (S-4 and S-5) located near the marsh barrier, at 400–450 m from the current coastline. The maximum flood area during MIS 1 (last 11,600 years) is represented in these cores by sediments indicative of different littoral subenvironm…
Fruits arriving to the west. Introduction of cultivated fruits in the Iberian Peninsula
2021
Agricultural activities, including practices, crops and techniques have evolved throughout history undergoing tremendous changes. From the early Neolithic farmers in the Mediterranean focused on cereal agriculture and only later, during the 4th/3rd millennium cal. BC in the Eastern basin, other species such as fruit trees were introduced into the agrarian system transforming the model that had been in use for millennia. Fruit tree management required innovation and investment and more importantly multi-year foresight as the new crops entailed a new pace of work with delayed returns and, thus, a greater entanglement with the land. Processes of social complexity and urbanization accompanied t…