200 research outputs found

    Fantasy and Censorship: Dino Buzzati’s correspondence from Italian colonies

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    The aim of my contribution is to study the role and influence of Fascist censorship in the journalistic articles that Dino Buzzati wrote from tha Italian colonies for the Corriere della Sera between 1933 and 1940. The articles are collected in the volume L’Africa di Buzzati.By placing Buzzati’s work in a precise historical framework and discussing the problem of his ‘orientalism’, the article demonstrates that Buzzati’s work from Africa can be read as a document of Italian colonialism and that it confirmed, in terms of stereotypes and prejudices, not only the attitude of ‘the West’ towards North African peoples, but also his bias against cultural and social realities which were distant from the ones he was familiar with.In terms of politics and ideology, the texts of Il Buttafuoco are difficult to decipher, especially with reference to the problem of racism. Buzzati’s narrative was determined not only by the influence of Fascist censorship but also by his aesthetic choices. In particular, the role of space played by the desert, the preference for anti-heroic figures and the diffuse use of imagination show the complexity of the relationship between Buzzati and political power, but also the originality in the way Buzzati used these figures to build a symbolism around the represented reality.

    Single and Double Knockouts of the Genes for Photosystem I Subunits G, K, and H of Arabidopsis

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    Photosystem I (PSI) of higher plants contains 18 subunits. Using Arabidopsis En insertion lines, we have isolated knockout alleles of the genes psaG, psaH2, and psaK, which code for PSI-G, -H, and -K. In the mutants psak-1 and psag-1.4, complete loss of PSI-K and -G, respectively, was confirmed, whereas the residual H level in psah2-1.4 is due to a second gene encoding PSI-H, psaH1. Double mutants, lacking PSI-G, and also -K, or a fraction of -H, together with the three single mutants were characterized for their growth phenotypes and PSI polypeptide composition. In general, the loss of each subunit has secondary, in some cases additive, effects on the abundance of other PSI polypeptides, such as D, E, H, L, N, and the light-harvesting complex I proteins Lhca2 and 3. In the G-less mutant psag-1.4, the variation in PSI composition suggests that PSI-G stabilizes the PSI-core. Levels of light-harvesting complex I proteins in plants, which lack simultaneously PSI-G and -K, indicate that PSI subunits other than G and K can also bind Lhca2 and 3. In the same single and double mutants, psag-1.4, psak-1, psah2-1.4, psag-1.4/psah2-1.4, and psag-1.4/psak-1 photosynthetic electron flow and excitation energy quenching were analyzed to address the roles of the various subunits in P700 reduction (mediated by PSI-F and -N) and oxidation (PSI-E), and state transitions (PSI-H). Based on the results, we also suggest for PSI-K a role in state transitions

    Interference at the Single Photon Level Along Satellite-Ground Channels

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    Quantum interference arising from superposition of states is a striking evidence of the validity of Quantum Mechanics, confirmed in many experiments and also exploited in applications. However, as for any scientific theory, Quantum Mechanics is valid within the limits in which it has been experimentally verified. In order to extend such limits, it is necessary to observe quantum interference in unexplored conditions such as moving terminals at large distance in Space. Here we experimentally demonstrate single photon interference at a ground station due to the coherent superposition of two temporal modes reflected by a rapidly moving satellite thousand kilometers away. The relative speed of the satellite induces a varying modulation in the interference pattern. The measurement of the satellite distance in real time by laser ranging allowed us to precisely predict the instantaneous value of the interference phase. We then observed the interference patterns with visibility up to 67%67\% with three different satellites and with path length up to 5000 km. Our results attest the viability of photon temporal modes for fundamental tests of Physics and Quantum Communications in Space.Comment: Version accepted for publication in Phys. Rev. Let

    Proposal for an Optical Test of the Einstein Equivalence Principle

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    The Einstein Equivalence Principle (EEP) underpins all metric theories of gravity. Its key element is the local position invariance of non-gravitational experiments, which entails the gravitational red-shift. Precision measurements of the gravitational red-shift tightly bound violations of the EEP only in the fermionic sector of the Standard Model, however recent developments of satellite optical technologies allow for its investigation in the electromagnetic sector. Proposals exploiting light interferometry traditionally suffer from the first-order Doppler effect, which dominates the weak gravitational signal necessary to test the EEP, making them unfeasible. Here, we propose a novel scheme to test the EEP, which is based on a double large-distance optical interferometric measurement. By manipulating the phase-shifts detected at two locations at different gravitational potentials it is possible to cancel-out the first-order Doppler effect and observe the gravitational red-shift implied by the EEP. We present the detailed analysis of the proposal within the post-Newtonian framework and the simulations of the expected signals obtained by using two realistic satellite orbits. Our proposal to overcome the first-order Doppler effect in optical EEP tests is feasible with current technology.Comment: manuscript improve

    UV Properties of Galactic Globular Clusters with GALEX II. Integrated colors

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    We present ultraviolet (UV) integrated colors of 44 Galactic globular clusters (GGCs) observed with the Galaxy Evolution Explorer (GALEX) in both FUV and NUV bands. This data-base is the largest homogeneous catalog of UV colors ever published for stellar systems in our Galaxy. The proximity of GGCs makes it possible to resolve many individual stars even with the somewhat low spatial resolution of GALEX. This allows us to determine how the integrated UV colors are driven by hot stellar populations, primarily horizontal branch stars and their progeny. The UV colors are found to be correlated with various parameters commonly used to define the horizontal branch morphology. We also investigate how the UV colors vary with parameters like metallicity, age, helium abundance and concentration. We find for the first time that GCs associated with the Sagittarius dwarf galaxy have (FUV-V) colors systematically redder than GGCs with the same metallicity. Finally, we speculate about the presence of an interesting trend, suggesting that the UV color of GCs may be correlated with the mass of the host galaxy, in the sense that more massive galaxies possess bluer clusters.Comment: Accepted for publication by The Astronomical Journal. 36 pages, 9 figures, 1 tabl

    Towards Quantum Communication from Global Navigation Satellite System

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    Satellite-based quantum communication is an invaluable resource for the realization of a quantum network at the global scale. In this regard, the use of satellites well beyond the low Earth orbits gives the advantage of long communication time with a ground station. However, high-orbit satellites pose a great technological challenge due to the high diffraction losses of the optical channel, and the experimental investigation of such quantum channels is still lacking. Here, we report on the first experimental exchange of single photons from Global Navigation Satellite System at a slant distance of 20000 kilometers, by exploiting the retroreflector array mounted on GLONASS satellites. We also observed the predicted temporal spread of the reflected pulses due to the geometrical shape of array. Finally, we estimated the requirements needed for an active source on a satellite, aiming towards quantum communication from GNSS with state-of-the-art technology.Comment: Revte

    Extending Wheeler's delayed-choice experiment to Space

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    Gedankenexperiments have consistently played a major role in the development of quantum theory. A paradigmatic example is Wheeler's delayed-choice experiment, a wave-particle duality test that cannot be fully understood using only classical concepts. Here, we implement Wheeler's idea along a satellite-ground interferometer which extends for thousands of kilometers in Space. We exploit temporal and polarization degrees of freedom of photons reflected by a fast moving satellite equipped with retro-reflecting mirrors. We observed the complementary wave-like or particle-like behaviors at the ground station by choosing the measurement apparatus while the photons are propagating from the satellite to the ground. Our results confirm quantum mechanical predictions, demonstrating the need of the dual wave-particle interpretation, at this unprecedented scale. Our work paves the way for novel applications of quantum mechanics in Space links involving multiple photon degrees of freedom.Comment: 4 figure

    A review of the molecular mechanisms underlying the development and progression of cardiac remodeling

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    Pathological molecular mechanisms involved in myocardial remodeling contribute to alter the existing structure of the heart, leading to cardiac dysfunction. Among the complex signaling network that characterizes myocardial remodeling, the distinct processes are myocyte loss, cardiac hypertrophy, alteration of extracellular matrix homeostasis, fibrosis, defective autophagy, metabolic abnormalities, and mitochondrial dysfunction. Several pathophysiological stimuli, such as pressure and volume overload, trigger the remodeling cascade, a process that initially confers protection to the heart as a compensatory mechanism. Yet chronic inflammation after myocardial infarction also leads to cardiac remodeling that, when prolonged, leads to heart failure progression. Here we review the molecular pathways involved in cardiac remodeling, with particular emphasis on those associated with myocardial infarction. A better understanding of cell signaling involved in cardiac remodeling may support the development of new therapeutic strategies towards the treatment of heart failure and reduction of cardiac complications. We will also discuss data derived from gene therapy approaches for modulating key mediators of cardiac remodeling
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