1,721,067 research outputs found
Forme di collaborazione e coproduzione nel cinema italiano (1930 - 1950)
Full text linkLa ricerca prende in esame le collaborazioni cinematografiche italiane in ambito europeo nell’arco del ventennio dal 1930 al 1950. Come è noto, con l'avvento del sonoro e la nascita di Cinecittà, il cinema italiano visse una nuova fase produttiva, posta sotto lo stretto controllo politico e finanziario del regime fascista. Nonostante il clima autarchico, appariva evidente come la manifestazione della volontà politica fosse orientata all’internazionalizzazione del cinema nazionale. L’Italia cercò di conformarsi alle esigenze
imposte dal mercato attraverso iniziative di collaborazione con le maggiori cinematografie europee e concluse trattative con la Germania, la Francia, l’Inghilterra e la Spagna per garantire alla produzione nazionale una collocazione anche al di fuori dei propri confini geografici.
Alla fine degli anni Quaranta i principali Paesi europei attivarono meccanismi di finanziamento e di sviluppo per la produzione cinematografica con l'idea che l'aiuto al cinema fosse una componente essenziale per la crescita culturale, mentre la collaborazione tra due o più case di produzione auspicava risultati economici promettenti nei rispettivi
mercati. È appunto l’internazionalità europea del film in quanto fondamento di quell’indirizzo industriale del cinema intrapreso in maniera decisiva negli anni Trenta, insieme alla difesa dell’identità culturale nazionale, a rappresentare il tema dominante di questa ricerca
Oscillator synchronisation for arbitrary quasi-periodic forcing
No full textWe study the problem of existence of response solutions for a real-analytic
one-dimensional system, consisting of a rotator subject to a small
quasi-periodic forcing
with Bryuno frequency vector. We prove that at least one response solution always exists,
without any assumption on the forcing besides smallness and analyticity. This strengthens the results available in the literature, where generic
non-degeneracy conditions are
assumed. The proof is based on a diagrammatic formalism and relies on renormalisation group techniques, which exploit the formal analogy with problems of quantum field
theory; a crucial role is played by remarkable identities between classes of diagrams
Resonant motions in the presence of degeneracies for quasi-periodically perturbed systems
No full textWe consider one-dimensional systems in the presence of a quasi-periodic
perturbation, in the analytical setting, and study the problem of existence
of quasi-periodic solutions which are resonant with the frequency vector of
the perturbation. We assume that the unperturbed system is locally integrable
and anisochronous, and that the frequency vector of the perturbation satisfies
the Bryuno condition. Existence of resonant solutions is related to the zeroes of a
suitable function, called the Melnikov function -- by analogy with the periodic case.
We show that, if the Melnikov function has a zero of odd order and under
some further condition on the sign of the perturbation parameter, then
there exists at least one resonant solution which continues an unperturbed
solution. If the Melnikov function is identically zero then one can push
perturbation theory up to the order where a counterpart of Melnikov function
appears and does not vanish identically: if such a function has a zero of odd order
and a suitable positiveness condition is met, again the same persistence result is
obtained. If the system is Hamiltonian, then the procedure can be
indefinitely iterated and no positiveness condition must be required:
as a byproduct, the result follows that at least one resonant quasi-periodic solution
always exists with no assumption on the perturbation.
Such a solution can be interpreted as a (parabolic) lower-dimensional torus
Long Time Behaviour of a Local Perturbation in the Isotropic XY Chain Under Periodic Forcing
No full textWe study the isotropic XY quantum spin chain with a time-periodic transverse magnetic field acting on a single site. The asymptotic dynamics is described by a highly resonant Floquet–Schrödinger equation, for which we show the existence of a periodic solution if the forcing frequency is away from a discrete set of resonances. This in turn implies the state of the quantum spin chain to be asymptotically a periodic function synchronised with the forcing, also at arbitrarily low non-resonant frequencies. The behaviour at the resonances remains a challenging open problem
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Abnormal immunothrombosis and lupus anticoagulant in a catastrophic COVID-19 recalling Asherson’s syndrome
Full text linkBackground: Coronavirus disease 2019 (COVID-19) is a complex disease with many clinicopathological aspects, including abnormal immunothrombosis, and the full comprehension of its pathogenetic mechanisms is urgently required. Methods/Results: By means of a multidisciplinary approach, we here report a catastrophic COVID-19 in a 44-year-old Philippine male patient, discovered lupus anticoagulant (LAC)-positive shortly before death, occurred 8 days after hospitalization in a clinical scenario refractory to standard high acuity care recalling Asherson’s syndrome (catastrophic antiphospholipid syndrome). Conclusion: A parallelism between this severe form of COVID-19 and Asherson’s syndrome can be so drawn. Both the diseases in fact exhibit hypercytokinemia, thrombotic microangiopathy, disseminated intravascular coagulation and multiple organ failure, they show a relationship with viral infections, and they are burdened by a high mortality rate. A genetic predisposition to develop these two overlapping conditions may be supposed
Maximal Tori in Infinite-Dimensional Hamiltonian Systems: a Renormalisation Group Approach
No full textWe study the existence of infinite-dimensional invariant tori in a mechanical system of infinitely many rotators weakly interacting with each other.We consider explicitly interactions depending only on the angles,with the aim of discussing in a simple case the analyticity properties to be required on the perturbation of the integrable systemin order to ensure the persistence of a large measure set of invariant tori with finite energy.The proof we provide of the persistence of the invariant tori implements the renormalisation group scheme based on the tree formalism, i. e., the graphical representation of the solutions of the equations of motion interms of trees, which has been widely used in finite-dimensional problems. The method is very effectual and flexible:it naturally extends, once the functional setting has been fixed, to the infinite-dimensional case with only minor technical-natured adaptations
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