Modificazioni e strategie competitive osservate nella flora dell’isola Rossa di Teulada (Sardegna sud occidentale)

The authors report on the results of their survey on the Isola Rossa near Teulada (South-western Sardinia). The flora found on the island, which consisted of 206 entities, grouped in 59 families and distributed in 157 genera, differs notably from the flora surveyed 50 years ago. In particular, 81 new species have been found, while 44 species listed in the earlier survey have not been confirmed. Comparison of typically mediterranean biological spectra showed an increase in terophytes and a sharp decrease in hemicriptophytes. The application of Grime’s triangular system to this survey and the earlier one showed that floral changes are characterised by a decrease in stress-resistant species and an increase in ruderal species. The vegetation cover has also undergone major changes. The colonising capacity of Brassica insularis is particularly interesting in this regard: this plant, which was previously found only on the northern side of the island, is now scattered throughout the island. All these changes have also been confirmed by the turnover ratio, which is in excess of 60%, and highlights the occurrence of deep environmental changes

Disponibilità idrica e cambiamenti nella composizione floristica osservati in alcune piccole isole della Sardegna

Modifications to climate, occurring frequently and over increasingly short periods, lead to changes in the flora of specific territories. The changes in the composition of several florae originally surveyed in different periods highlight the fact that reduction in the availability of water leads to an increase in therophytes and to a drastic reduction of hemicryptophytes. This phenomenon has been observed on some of the small Sardinian islands which, when compared with studies carried out there in previous years, now show evidence of significant alteration in their floristic composition

Fare apprendistato in Lombardia. Guida pratica per la stesura dei contratti di apprendistato e la gestione dei relativi piani formativi

L’immagine della copertina del volume, realizzata da Lavinia Serrani, è un tentativo di rappresentare la persistente modernità di un contratto “antico” come l’apprendistato. Relegato dalla letteratura, anche specialistica, e dall’immaginario collettivo del nostro Paese alla figura del ragazzo di bottega e a mestieri di bassa manovalanza, l’apprendistato rappresenta oggi, almeno nei Paesi più evoluti, il principale canale di integrazione tra la scuola e il lavoro. Non un semplice quanto banale learning by doing, quanto un più maturo “fare per imparare” e cioè mettere alla prova, in situazioni reali e di compito, le necessarie conoscenze teoriche traducendole in competenze e abilità. Non a caso il vero apprendistato, quello incentrato su una imprescindibile relazione soggettiva tra un Maestro e un allievo, rappresenta ancora oggi la forma più efficace di trasmissione ed evoluzione dei saperi e dei mestieri, secondo uno scambio formativo che non è mai unidirezionale, e costituisce a ben vedere uno dei principali fattori abilitanti dei nuovi processi economici della c.d. “Industria 4.0” contribuendo alla qualità e produttività del lavoro e alla occupabilità della persona generando valore per tutti i soggetti coinvolti (l’apprendista, ma anche l’impresa e il tutor aziendale, così come la scuola e l’università)

Variazioni della flora e del manto vegetale osservate sull'isola di Santo Stefano (Sardegna NE)

Le ricerche floristiche su quest'isola sono state intraprese da diversi studiosi sin dal secolo scorso e negli anni sessanta viene analizzata la vegetazione su basi fisionomiche. Recentemente, nel corso di uno studio realizzato con il contributo della Comunità Europea, è stato riscontrato un notevole cambiamento della componente floristica indicata negli inventari floristici precedenti e in particolare è stato osservato il mancato ritrovamento di 30 specie

Flora vascolare del Capo di Monte Santu (Sardegna centro orientale)

The vascular flora of Capo di Monte Santu (Central-Eastern Sardinia) – The Authors present their study on the flora of Capo di Monte Santu, a calcareous area forming the southern tip of the Gulf of Orosei. Investigation allowed us to identify 381 taxa, belonging to 62 families and comprising 228 genera. Data regarding the biological spectrum show a prevalence of therophytes (49.2%), typical of the regions of the Mediterranean area, followed by hemicryptophytes (21.8%) and geophytes (10.8%). An overview of the chorological spectrum of the flora highlights dominance of the Mediterranean component (78.5%). Amongst the Mediterranean species s.s. (47.2%) we noted greater presence of entities of the Steno-Mediterranean distribution area (25.7%), followed by endemics which with 43 entities constitute 11.3% of total flora. From the chorological point of view, the prevailing element amongst the endemics is the Sardinian (11 taxa) including 5 taxa which are exclusive to the calcareous massif of central-eastern Sardinia. The analysis of rarities, performed by applying Rabinowitz’ categories, shows as being most numerous (86 taxa) species spread over the territory with a restricted ecology and scarce, non-dominant populations (WRS), whereas the least consistent (9 taxa) is that of the species with limited spread over the territory, a wide ecology and scarce and non dominant populations (NBS). Those entities considered worthy of protection based on the IUCN red lists are four in number (Lactuca longidentata, Orchis brancifortii, Polygala saxatilis and Sedum villosum subsp. glandulosum), one entity (Ruscus aculeatus) is listed in Annex V of the Habitat Directive while Annex II of CITES includes all the Orchidaceae (10) and Cyclamen repandum subsp. repandum

Variazione di alcuni indici fitoclimatici osservati a Cagliari dal 1892 al 2002

Analyzing the thermopluviometric data of Cagliari from 1892 to 2002, have been processed the most important phytoclimatic indices reported both to whole time and to five equivalent periods. The achieved results, confirmed by the all calculated indices, point out a shifting towards conditions of greater dryness, more obvious in the last years, determining in the local floras an increase of annual species

Riferimenti bibliografici sulla flora vascolare sarda riportati nell'Informatore Botanico Italiano dal 1969 al 2004

The authors have been referring to works about Sardinian flora published in Informatore Botanico Italiano. The works date back to establishment of review to 2004. A flora list has been drown up on a database where there is a lot of information on every single entity: the places where they have been found, the relative bibliographical references and when it is necessary the nomenclatural updating. 1334 records which were studied in 136 works have been analysed. There are totally 610 entities of Sardinian flora like the list shows

The foundations of statistical mechanics from entanglement: Individual states vs. averages

We consider an alternative approach to the foundations of statistical mechanics, in which subjective randomness, ensemble-averaging or time-averaging are not required. Instead, the universe (i.e. the system together with a sufficiently large environment) is in a quantum pure state subject to a global constraint, and thermalisation results from entanglement between system and environment. We formulate and prove a "General Canonical Principle", which states that the system will be thermalised for almost all pure states of the universe, and provide rigorous quantitative bounds using Levy's Lemma.Comment: 12 pages, v3 title changed, v2 minor change

Geometric dynamical observables in rare gas crystals

We present a detailed description of how a differential geometric approach to Hamiltonian dynamics can be used for determining the existence of a crossover between different dynamical regimes in a realistic system, a model of a rare gas solid. Such a geometric approach allows to locate the energy threshold between weakly and strongly chaotic regimes, and to estimate the largest Lyapunov exponent. We show how standard mehods of classical statistical mechanics, i.e. Monte Carlo simulations, can be used for our computational purposes. Finally we consider a Lennard Jones crystal modeling solid Xenon. The value of the energy threshold turns out to be in excellent agreement with the numerical estimate based on the crossover between slow and fast relaxation to equilibrium obtained in a previous work by molecular dynamics simulations.Comment: RevTeX, 19 pages, 6 PostScript figures, submitted to Phys. Rev.

Origin of the Canonical Ensemble: Thermalization with Decoherence

We solve the time-dependent Schrodinger equation for the combination of a spin system interacting with a spin bath environment. In particular, we focus on the time development of the reduced density matrix of the spin system. Under normal circumstances we show that the environment drives the reduced density matrix to a fully decoherent state, and furthermore the diagonal elements of the reduced density matrix approach those expected for the system in the canonical ensemble. We show one exception to the normal case is if the spin system cannot exchange energy with the spin bath. Our demonstration does not rely on time-averaging of observables nor does it assume that the coupling between system and bath is weak. Our findings show that the canonical ensemble is a state that may result from pure quantum dynamics, suggesting that quantum mechanics may be regarded as the foundation of quantum statistical mechanics.Comment: 12 pages, 4 figures, accepted for publication by J. Phys. Soc. Jp