Search results for "Trees"
showing 10 items of 312 documents
Image Segmentation through a Hierarchy of Minimum Spanning Trees
2012
Many approaches have been adopted to solve the problem of image segmentation. Among them a noticeable part is based on graph theory casting the pixels as nodes in a graph. This paper proposes an algorithm to select clusters in the images (corresponding to relevant segments in the image) corresponding to the areas induced in the images through the search of the Minimum Spanning Tree (MST). In particular is is based on a clustering algorithm that extracts clusters computing a hierarchy of Minimum Spanning Trees. The main drawback of this previous algorithm is that the dimension of the cluster is not predictable and a relevant portion of found clusters can be composed by micro-clusters that ar…
Uomini e alberi. Tre indagini storico-religiose. Nota introduttiva
2021
In this introductory note I present three essays on the relationship between trees and rituals in ancient Mediterranean civilisations and in Vedic India.
Dendrolatrie. Miti e pratiche dell'immaginario arboreo
2021
L’avvento dell’Antropoce, epoca in cui l’essere umano è diventato una forza geologica, scompagina la divisione del sapere tra scienze umane e naturali. Per comprenderlo, è necessario costruire nuove forme di alleanza tra discipline. È quanto invita a fare anche il fe- nomeno delle dendrolatrie. Diffuso in ogni luogo e in ogni epoca, il culto degli alberi testimonia come il mondo arboreo abbia plasma- to modi di vivere e di pensare, venendone a sua volta trasformato. Per scavare nella complessità di questo scambio, il volume racco- glie i frutti del dialogo tra un gruppo interdisciplinare di ricercatrici e ricercatori che esplorano l’immaginario arboreo in tre direzioni: quella degli studi s…
[Deciding in conditions of uncertainty: the Delphi method and its use in the formulation of guidelines].
2001
The purpose of this paper is to analyze one of the most powerful tools in the decision-making under conditions of uncertainty, the Delphi method, and to verify the related interest of scientific world, particularly, for formulation of guidelines. The method combines the expert opinion preventing biases due to institutional role, status or dominant personality. In the text we explain the methodology and the steps through which it is possible to realize the consensus; we schematized in a didactic manner all the phases for an operational approach of the reader. The search by the most diffused biomedical database (Medline) individualized 623 citations, 7 of which are guidelines (3 of remarkable…
Evaluation of Risk Parameters in Bone Regeneration Using a Customized Titanium Mesh
2019
PURPOSE The aim of the study was an evaluation of risk factors for an innovative bone regeneration technique using a customized titanium mesh that was tested in a clinical setting. MATERIALS AND METHODS This retrospective study included 65 patients with 70 grafting procedures of osseous defects of the jaws with a customized titanium mesh together with Advanced- and Injectable-Platelet-Rich Fibrin (A- and I-PRF), resorbable membranes, and bone grafting materials. Exposures of the meshes and grafting outcome were analyzed according to a novel classification as (a) punctual and (b) tooth width or complete exposure of the mesh (c). No exposure was stated as (d). RESULTS In 37% of cases, exposur…
Changes in soil microbial community structure influenced by agricultural management practices in a mediterranean agro-ecosystem.
2013
Agricultural practices have proven to be unsuitable in many cases, causing considerable reductions in soil quality. Land management practices can provide solutions to this problem and contribute to get a sustainable agriculture model. The main objective of this work was to assess the effect of different agricultural management practices on soil microbial community structure (evaluated as abundance of phospholipid fatty acids, PLFA). Five different treatments were selected, based on the most common practices used by farmers in the study area (eastern Spain): residual herbicides, tillage, tillage with oats and oats straw mulching; these agricultural practices were evaluated against an abandon…
Pruning Incremental Linear Model Trees with Approximate Lookahead
2014
Incremental linear model trees with approximate lookahead are fast, but produce overly large trees. This is due to non-optimal splitting decisions boosted by a possibly unlimited number of examples obtained from a data source. To keep the processing speed high and the tree complexity low, appropriate incremental pruning techniques are needed. In this paper, we introduce a pruning technique for the class of incremental linear model trees with approximate lookahead on stationary data sources. Experimental results show that the advantage of approximate lookahead in terms of processing speed can be further improved by producing much smaller and consequently more explanatory, less memory consumi…
Networks of equities in financial markets
2004
We review the recent approach of correlation based networks of financial equities. We investigate portfolio of stocks at different time horizons, financial indices and volatility time series and we show that meaningful economic information can be extracted from noise dressed correlation matrices. We show that the method can be used to falsify widespread market models by directly comparing the topological properties of networks of real and artificial markets.
WOODIV, a database of occurrences, functional traits, and phylogenetic data for all Euro-Mediterranean trees
2021
Trees play a key role in the structure and function of many ecosystems worldwide. In the Mediterranean Basin, forests cover approximately 22% of the total land area hosting a large number of endemics (46 species). Despite its particularities and vulnerability, the biodiversity of Mediterranean trees is not well known at the taxonomic, spatial, functional, and genetic levels required for conservation applications. The WOODIV database fills this gap by providing reliable occurrences, four functional traits (plant height, seed mass, wood density, and specific leaf area), and sequences from three DNA-regions (rbcL, matK, and trnH-psbA), together with modelled occurrences and a phylogeny for all…
Weighted distance-based trees for ranking data
2017
Within the framework of preference rankings, the interest can lie in finding which predictors and which interactions are able to explain the observed preference structures, because preference decisions will usually depend on the characteristics of both the judges and the objects being judged. This work proposes the use of a univariate decision tree for ranking data based on the weighted distances for complete and incomplete rankings, and considers the area under the ROC curve both for pruning and model assessment. Two real and well-known datasets, the SUSHI preference data and the University ranking data, are used to display the performance of the methodology.