2,737 research outputs found
Quadri mentali e culture diffuse in Italia tra anni ottanta e novanta. Persistenza o rottura?
No full textrecensione a due voci del volume Elena Bignami (a cura di), L'Italia tra due secoli, Bologna, Pendragon, 2013: In coerenza col suo forte interesse per la promozione di una riflessione storiografica sulla storia dell’Italia repubblicana, in particolare quella degli ultimi decenni, la redazione di “Italia contemporanea” ha affidato ad Alessio Gagliardi e Andrea Sangiovanni la lettura del volume collettaneo curato da Elena Bignami, L’Italia tra due secoli. Al primo e stato chiesto di soffermarsi soprattutto sugli aspetti politici ed economici, mentre il secondo e stato interpellato sulle questioni legate alla cultura e alla comunicazione
Sangiovanni, Giosuè
No full textGiosuè Sangiovanni (Laurino, 15 gennaio 1775 - Pozzuoli, 17 maggio 1849), medico, zoologo, è stato titolare della prima cattedra di Anatomia comparata istituita in Italia. Patriota, prese parte alla Rivoluzione napoletana del 1799 e successivamente ai moti del 1820-21 e del 1848
Informare e educare: gli anni della televisione pedagogica (1954-1975)
No full textIl saggio analizza il rapporto fra televisione italiana e istruzione, con particolare attenzione a quella per gli adulti. Dopo aver delineato il peculiare modello di broadcast italiano, inserendolo nel più ampio contesto europeo di servizio pubblico, viene introdotta una distinzione fra televisione “pedagogica” e televisione “educativa”, sostenuta da un'analisi dei principali programmi della tv educativa, e in particolare di quella dedicata agli adulti. Infine, il saggio ripercorre la crisi di questo modello nel contesto della concorrenza con l'emittenza privata.The essay analyses the relationship between Italian television and education, with particular attention to adult television. After outlining the peculiar Italian broadcasting model, placing it in the broader European public service context, a distinction is introduced between ‘pedagogical’ and ‘educational’ television, supported by an analysis of the main programmes of educational television, and in particular those dedicated to adults. Finally, the essay traces the crisis of this model in the context of competition with commercial television
Mesoscopic disorder and intrinsic charge instability in oxide heterostructures
No full textAfter Ohtomo and Hwang detected a high-mobility two-dimensional electron gas (2DEG) at the interface between the two insulating perovskite oxides Strontium Titanate
(SrTiO) and Lanthanum Aluminate (LaAlO) \cite{Ohtomo2004}, an increasingly intense theoretical and experimental investigation has been devoted to
these systems.
Oxide heterostructures are of great interest for both fundamental and applicative reasons.
In particular, the two-dimensional electron gas at the LaAlO/SrTiO (LAO/STO) interfaces displays
many different properties and functionalities.
It can be made superconducting when its carrier density is tuned by means of a gate voltage \cite{Reyren2007,Caviglia2008}, thus opening the way to voltage-driven
superconducting devices.
Also, it exhibits magnetic properties \cite{Ariando2011,Li2011,Bert2011,Dikin2011,Mehta2012,Bert2012};
displays a strong and tunable \cite{Caviglia2010,Caprara2012} Rashba spin-orbit coupling; it is extremely two-dimensional,
having a lateral extension \approx \SI{5}{\nano\meter}, thereby enhancing the effect of disorder due to extrinsic and/or intrinsic sources.
Similar results hold true also for other oxides such as
LaTiO/SrTiO \cite{Biscaras2010,Biscaras2012}, where the role of Lanthanum Aluminate is taken by
Lanthanum Titanate LaTiO (LTO).
In these kind of systems, superconductivity is possibly related to the presence of high-mobility carriers (HMC) and low-mobility carriers (LMC),
which presence is revealed by
magneto-transport experiments, and seems to develop as soon as high-mobility carriers
appear \cite{Biscaras2012}, when the carrier density is tuned above a threshold value by means of gate voltage, V.
Along with these intriguing physical properties, there are clear experimental indications that the
interface electronic state is strongly inhomogeneous,
as revealed in various magnetic experiments \cite{Ariando2011,Li2011,Bert2011,Bert2012}, in tunneling spectra \cite{Ristic2011},
and possibly in piezoforce microscopy \cite{Feng2013}.
It seems that inhomogeneities at nanometric scale coexist with larger (e.g., micrometric) scale inhomogeneities, revealed by the occurrence of striped
textures in the current distribution \cite{Kalisky2013} and in the surface potential \cite{Ilani2013}.
The inhomogeneous character of the 2DEG may be responsible of the anomalously large width of the superconducting transition, which is not compatible
with any reasonable superconducting fluctuations (e.g., Aslamazov-Larkin contribution to the paraconductivity) \cite{Caprara2011}, but instead
it is well accounted for assuming that the 2DEG consists of superconducting ``puddles '' embedded in weakly localizing metallic background.
This scenario could also help to explain the measurements carried out at low carrier density, showing a saturation plateau with finite resistance,
a clear signature of the percolating character of the metal-to-superconductor transition.
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The aim of the present thesis is to assemble all these experimental evidences into a coherent overall theoretical framework.
The outline is as follows.
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In chapter \ref{ch:overview} we review some of the experimental facts about LAO/STO and LTO/STO interface, stressing our attention
on the peculiar transport properties, both in the normal and in the superconducting state.
\\
In chapter \ref{ch:sust} we first provide new,
compelling evidences of the inhomogeneous character of the 2DEG.
We consider the phenomenological assumption that the electron gas consists of a metallic sea, where only LMC are present, hosting metallic islands, where LMC and HMC
coexist and become superconducting below a randomly distributed
critical temperature.
Basing on this idea, we extend previous multicarrier analyses of magneto-transport measurements to deal with inhomogeneous
systems and show how Hall resistivity, superfluid density and tunneling spectra measurements can be explained within this scenario.
The connection between superconductivity and the appearing of the high-mobility carriers is also investigated.
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Chapter \ref{ch:QW} is devoted to formulate a possible justification of the inhomogeneous scenario and the appearing of two type of carriers whose distribution
is not uniform in space. The mechanism that we propose is based on the quantum confinement experienced
by the 2DEG because of the strong electric field perpendicular to the interface.
We will show that such an \emph{intrinsic} mechanism is due to the fact that the confining potential well depends on the electron density,
therefore giving rise to a non-rigid band structure which
evolves as a function of the electron density too. In a wide range of reasonable parameters, compatible with the experiments,
the non-rigidity determines a negative compressibility in the uniform system, which it avoids by phase separation.
The densities of the phase separated regions are thus found by Maxwell construction and depend on the doping level.
The phase separation scenario also naturally explains the inhomogeneous distribution of low- and high-mobility carriers, and their behavior as a function
of the doping level.
In chapter \ref{ch:dds} we explore the fluctuations of the superconducting order parameter in the vicinity of the metal-to-superconductor phase transition,
that is reached as the gate voltage is changed.
In the case of superconductivity, the order parameter has an amplitude and a phase, which can both fluctuate according to well identified scenarios. We address the
possibility that a new type of fluctuations occurs in the superconducting 2DEG at LAO/STO and LTO/STO interfaces, with an anomalous dynamics. In particular,
we show that the superconducting-to-metal quantum phase transition displays anomalous scaling properties, which can be explained by density driven
superconducting critical fluctuations.
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Finally, the concluding remarks will be given in chapter \ref{ch:conclusion}. We will critically discuss the merits
and limitations of our approach and provide a brief outlook on future work
La rinascita della stampa libera a Roma e le condizioni della città (1944-1945)
No full textL'articolo ricostruisce le condizioni della stampa quotidiana e periodica a Roma subito dopo la liberazione della città il 4 giugno 1944 e nei mesi successivi, dedicando ampio spazio alla descrizione delle condizioni della città
An Interview with Paola Sangiovanni
No full textThis video interview with Paola Sangiovanni, a leading female Italian film director, accompanies the 2013 book Reframing Italy: New Trends in Italian Women\u27s Filmmaking, by Bernardette Luciano and Susanna Scarparo, and is published in the series Purdue Studies in Romance Literatures by Purdue University Press
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