Search results for " sistema."
showing 10 items of 1920 documents
Insular endemism in the Mediterranean vascular flora: the case of the Aeolian Islands (Sicily, Italy)
2012
The present paper briefly provides the state of the art of the knowledge on vascular plant endemism in the oceanic (“thalassogenous”) Aeolian Archipelago (Sicily). Preliminary analysis of distribution areas and review of recent literature on biosystematics of endemic species revealed that: (a) Aeolian strictly endemic taxa are just 6, i.e. about the 0.7 % of the local vascular flora; among them, just 4 can be considered (with doubt) derived from in situ evolution. (b) The other 18 endemics are taxa occurring in wider areas, so they cannot be generally considered “locally evolved” but relicts. This preliminary analysis confirms that not only continental (“chersogenous”) but all Mediterranean…
Lycopodiidae for the “Flora Critica d’Italia”: material and methods
2015
Procedures are presented that were followed during the preparation of the first pteridophyte family treatments for the “Flora Critica d’Italia”: Lycopodiaceae, Isoetaceae, Selaginellaceae. The work was mainly based on the study of literature and herbarium specimens. In some cases SEM observation of spores has proved useful. Data collected from herbarium specimens and other verified sources were loaded into a database, from which a distribution map was prepared for each taxon. Several preliminary papers have been published, and for each family a taxonomic conspectus, with type designations, maps and an identification key, has been prepared. The treatment of these three families for the “Flor…
Testing flow resistance equation for rill flow
2018
At first, in this paper a flow resistance equation for rill flow, deduced applying dimensional analysis and self-similarity theory, is presented. The incomplete self-similarity hypothesis is used for establishing the flow velocity distribution whose integration gives the theoretical expression of the Darcy-Weisbach friction factor. Then the deduced theoretical resistance equation, which is calibrated by some measurements of flow velocity, water depth, cross section area, wetted perimeter and bed slope carried out in 106 reaches of some rills modelled on an experimental plot, is tested using the literature data by Abrahams et al. (1996), Strohmeier et al. (2014) and Peng et al. (2015) for ri…
Effects of Boulder Arrangement on Flow Resistance Due to Macro-Scale Bed Roughness
2023
Flow resistance in gravel-bed channels is not only affected by the shape and size of the roughness elements, but also by their arrangement on the channel bed surface (position to flow streamlines, spacing between elements, and their protrusion from the channel bed). Many investigations proved that open channel flow resistance can be obtained by integrating the power velocity profile. For a macro-scale roughness condition, this study aims to investigate the effect of different boulder arrangements on flow resistance. First, for each arrangement, the equation relating Γ function of the power velocity profile, the Froude number, and the channel slope was calibrated using available measur…
Experimental investigation of flow characteristics in vegetated channels
2006
Classificazione sistematica e distribuzione dei foraminiferi bentonici recenti nei sedimenti marini delle coste siciliane.
2012
The Italian endemic forest plants: an annotated inventory and synthesis of knowledge
2023
Background and aims – Forests are among the most threatened ecosystems worldwide, and endemic plants are often a vulnerable component of the flora of a given territory. So far, however, understory forest endemics of southern Europe have received little attention and are poorly known for several aspects. Material and methods – We developed the first list of native vascular plants that are restricted to Italian forests. Available information on taxonomy, regional distribution, ecology, biology, functional traits, and conservation status was collected for each taxon, allowing to identify major knowledge gaps and calculate baseline statistics. Key results – The list includes 134 taxa, most of w…
La revisione costituzionale tra processi riformatori e crisi della rappresentanza politica. Spunti di riflessione
2016
La legge di revisione costituzionale approvata dalle Camere, ma sottoposta al referendum costituzionale, presenta notevoli elementi di criticità: incide sugli assetti degli istituti fondamentali del sistema costituzionale repubblicano, ma non sembra rispondere alle istanze che premono per un rinnovamento più profondo della rappresentanza politica.
Consideraciones sobre la formación inicial del profesorado en educación para la salud
1993
Expone como elaborar y poner en práctica un programa de educación para la salud. Se debe saber adaptar el currículo oficial, y desarrollar una programación concreta de aula. Todo ello significa conocer la naturaleza del proceso de enseñanza-aprendizaje: conocimientos, creencias actitudes, escalas del alumnado. Nos habla del concepto de salud y sus determinantes, de la educación para la salud, de los objetivos de la educación para la salud en la escuela y una propuesta de formación inicial en educación para la salud. Estos aspectos deben de contemplar: los contenidos que desarrollen los conceptos de salud, la metodología de trabajo, los problemas que presenta la interiorización de los temas …
ESPERIMENTO DI SIMULAZIONE DELLA FORMAZIONE DEI RILL A SCALA DI PARCELLA
2016
Nella memoria sono riportati i risultati di un esperimento di simulazione della formazione del canale di un rill condotto in una parcella avente una dimensione 2x7 m2 ed una pendenza del 14% realizzata dal Dipartimento di Scienze Agrarie e Forestali dell’Università di Palermo. Una rete di solchi, costituita da due canali principali, è stata, dapprima incisa sul suolo manualmente e successivamente modellata utilizzando una corrente idrica limpida. Sui solchi modellati è stato effettuato, in corrispondenza di 11 sezioni trasversali della parcella, il rilievo delle caratteristiche geometriche e idrauliche utilizzando un profilometro. L’indagine ha inoltre previsto la realizzazione sia di un mo…