1,354,333 research outputs found
Synthesis and stereoselective functionalization of silylated heterocycles as a new class of formyl anion equivalents.
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Morpho-sedimentary evolution of a microtidal meandering channel driven by 130-years of natural and anthropogenic modifications of the Venice Lagoon (Italy)
No full textAbstract Tidal channels form the pathways for tidal currents to propagate and distribute clastic sediments and nutrients, thus providing a primary control on tidal-landscape ecomorphodynamics. Most tidal channels in both estuarine and lagoonal environments have a tendency to meander, yet very few studies exist that investigate the full spectrum of processes controlling tidal meander morpho-sedimentary evolution. The Venice Lagoon (Italy) offers a unique opportunity to shed light on this topic, because a long record of morphological and sedimentary data is available, which allows one to relate tidal channel evolution to the hydrodynamic and morphological changes undergone by the lagoon. In particular, during the last 130 years, feedback between rising relative sea levels and anthropogenic interventions have caused severe modifications of the Lagoon hydro- and morpho-dynamics. Here we investigate how these modifications fed back into the morpho-sedimentary evolution of a meandering tidal channel located in the northern Lagoon. Combining extensive datasets of aerial photographs, topographic and bathymetric surveys, geophysical investigations, sedimentary core analysis, and numerical modeling, we show that enhanced local tidal ranges and water discharges determine adjustments of channel cross-sectional geometries proportional to increasing tidal prisms, while changes in local tidal asymmetries caused modifications of the local sediment transport regime, resulting in the development of bar-pool patterns according to the dominant tidal phase. Such bar-pool patterns eventually determine channel migration through a bar-push mechanism controlled by a fluvial-like, quasi-linear relationship between local channel curvature and lateral migration rates. Critical differences in sediment transport regime are however highlighted between fluvial and tidal meanders, the latter being potentially characterized by high concentrations of suspended sediment during periods of slack waters when wind-driven sediment transport processes are not negligible. This could hamper the formation of high-relief bedforms, with profound implications for the sedimentology of tidal point-bar deposits
Alcide De Gasperi and the problem of reconstruction
No full textStarting with a quick overview of the historiography of Italy from Fascism to the
Republic, this article looks at Alcide De Gasperi’s establishment as a leader
within both the Italian political system and within his Party – the Christian
Democrats – casting new light on three aspects of his political activity: (1) his
relationship with the Church and the Catholics’ new modes of participation in
political life; (2) the reasons inspiring the definition of the Republican State’s
institutional architecture; and (3) alliance strategy in government formation and
in relationships with the other parties. The originality of De Gasperi’s political
activity can be defined in terms of these issues, together with the development of a
distinctive political leadership, for too long overlooked, that would play a critical
role in carrying Italy through its postwar reconstruction
La storiografia del giorno dopo: il dibattito sulla crisi della Democrazia Cristiana negli anni Novanta
No full textIn this review article we try to analize the storiographic debate about political crisis in the Christian Democracy party in the last ten years. Contributions considered follow two interpretative directions. In one hand politological approach estimates this crisis as a general transformation both sor whole political system than institutional one; in the other hand, hinstorical approach try to estimate which kind of change in or out this party, or which original elements have wore away both its identity than its functions
La Democrazia Cristiana e il centro-sinistra: dalle premesse alla collaborazione tra cattolici e socialisti
No full textThe reactivity of a- and b-iodo propenoylsilanes: an alternative access to polyunsaturated acylsilanes
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Democrazia cristiana e mondo cattolico negli anni Ottanta
No full textNel quadro di una analisi, volta a ricostruire il processo di crisi e di delegittimazione dei partiti nella stagione repubblicana, il contributo si propone di affrontare la complessa evoluzione del rapporto tra Democrazia cristiana e mondo cattolico nel corso degli anni Ottanta. In questa prospettiva l'indagine sulle dinamiche interne al partito si interseca con le trasformazioni e le evoluzioni che avrebbero interessato il mondo cattolico e la Santa Sede al fine di valutare quanto la delega politica a lungo concessa alla Democrazia cristiana venisse messa in discussione dall'emergere di una crisi politica e valoriale che investiva il sistema politico e la società civile
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