8,251 research outputs found

    Microscopic origin of pairing

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    A brief review of recent progress in the ab intio theory of nuclear pairing is given. Nowdays several successful solutions of the ab intio BCS theory gap equation were published which show that it is a promising first step in the problem. However, the role of many-body correlations that go beyond the BCS scheme remains uncertain and requires further investigations. As an alternative, the semi-microscopic model is discussed in which the effective pairing interaction calculated from the first principles is supplemented with a small phenomenological addendum containing one phenomenological parameter universal for all medium and heavy atomic nuclei.Comment: Contribution to the Volume 50 years of Nuclear BCS edited by World Scientifi

    Revisiting Qumran Cave 1Q and its archaeological assemblage

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    Qumran Cave 1Q was the first site of Dead Sea scroll discoveries. Found and partly emptied by local Bedouin, the cave was excavated officially in 1949 and published in the series Discoveries in the Judaean Desert (Volume 1) in 1955. Contents of the cave are found in collections worldwide, and in different institutions in Jerusalem and Amman. While the scrolls are the most highly prized artefacts from this cave, in archaeological terms they are part of an assemblage that needs to be understood holistically in order to make conclusions about its character and dating. This study presents all of the known items retrieved from the cave, including those that are currently lost, in order to consider what we might know about the cave prior to its emptying and the changes to its form. It constitutes preliminary work done as part of the Leverhulme funded International Network for the Study of Dispersed Qumran Caves Artefacts and Archival Sources [IN-2015-067].peer-reviewe

    On the Reliability of the Langevin Pertubative Solution in Stochastic Inflation

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    A method to estimate the reliability of a perturbative expansion of the stochastic inflationary Langevin equation is presented and discussed. The method is applied to various inflationary scenarios, as large field, small field and running mass models. It is demonstrated that the perturbative approach is more reliable than could be naively suspected and, in general, only breaks down at the very end of inflation.Comment: 7 pages, 3 figure

    Is Betelgeuse the Outcome of a Past Merger?

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    We explore the possibility that the star alpha Orionis (Betelgeuse) is the outcome of a merger that occurred in a low mass ratio (q = M2/M1 = 0.07 - 0.25) binary system some time in the past hundreds of thousands of years. To that goal, we present a simple analytical model to approximate the perturbed internal structure of a post-merger object following the coalescence of a secondary in the mass range 1-4 Msun into the envelope of a 15-17 Msun primary. We then compute the long-term evolution of post-merger objects for a grid of initial conditions and make predictions about their surface properties for evolutionary stages that are consistent with the observed location of Betelgeuse in the Hertzsprung-Russell diagram. We find that if a merger occurred after the end of the primary's main-sequence phase, while it was expanding toward becoming a red supergiant star and typically with radius ~200 - 300 Rsun, then it's envelope is spun-up to values which remain in a range consistent with the Betelgeuse observations for thousands of years of evolution. We argue that the best scenario that can explain both the fast rotation of Betelgeuse and its observed large space velocity is one where a binary was dynamically ejected by its parent cluster a few million years ago and then subsequently merged. An alternative scenario in which the progenitor of Betelgeuse was spun up by accretion in a binary and released by the supernova explosion of the companion requires a finely tuned set of conditions but cannot be ruled out.Comment: 20 pages, 8 figures, accepted for publication in the Astrophysical Journa

    Angiola d’Orso y la traducción de 'Con quien vengo, vengo'

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    El trabajo de la profesora Marcello trata sobre la traducción italiana de 'Con quien vengo, vengo', llevada a cabo por la actriz italiana Angiola d’Orso en 1666. El análisis de la traducción busca establecer las diferencias de interpretación desde la perspectiva italiana de un texto español visto como contemporáneo. Professor Marcello’s work treats the Italian translation of 'Con quien vengo, vengo', realized by the Italian actress Angiola d’Orso in 1666.The analysis of the translation seeks to establish the differences of interpretation from the Italian perspective of a Spanish text seen as contemporary

    Il filosofo di campagna goldoniano tradotto da Ramón de la Cruz Note di lingua e riscrittura

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    Il saggio analizza dal punto di vista linguistico-letterario alcuni passi della zarzuela di Ramón de la Cruz El filósofo ldeano,traduzione-adattamento di un dramma giocoso goldoniano, allo scopo di identificare le linee maestre seguite dal drammaturgo spagnolo per la sua rielaborazione drammatica. La campionatura dei testi, che tiene conto sia delle tipologie testuali che della caratterizzazione comica o seria dei personaggi, permette di enucleare la tendenza di Ramón de la Cruz ad accentuare il carattere popolare - con un abbassamento stilistico-linguistico del dettato - delle figure comiche. Se nel caso di Don Alfonso e dello scrivano, lo scopo è quello parodistico, caricaturale; nel caso del contadino-filosofo (e della servetta, qui vista di sfuggita), gli interventi vanno, invece, in direzione opposta.This essay discusses, from a linguistic-literary viewpoint, some movements of the zarzuela El Filósofo Aldeano by Ramón de la Cruz (which is a translation-adaptation of a goldonian "dramma giocoso"), with the aim of identifying the framework followed by the Spanish playwright in order to achieve his dramatic re-elaboration. Our sampling of the texts, which takes into account the textual typologies as much as the characterization (serious or comic) of the characters, allows us to elucidate de la Cruz's tendency to emphasise the popular character of the comic figures (which also involves a stylistic lowering of the dictation). If in the case of Don Alfonso and of the scrivener the purpose is parodic or caricaturesque, in the case of the peasant-philosopher (and of the servant, seen here in passing) the interventions work, on the contrary, in the opposite direction

    Doppler imaging of AR Lacertae at three epochs

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    Observations from IUE were used to study the structure of the lower chromosphere of AR Lacertae in the light of Mg II k. Sequences of LWR/P-HI images distributed around the binary period at three epochs were obtained. Discrete plage-like regions of enhanced Mg II surface flux in this system are identified. There are temporal variations in the Mg II flux on timescales of hours as well as substantial changes in chromospheric morphology on timescales of years. Even with the limited S/N attainable with the IUE, one can map the gross structures of active stellar atmospheres. With such information, one can begin to study the true 3-D structure of the atmospheres of late-type stars

    Ultra-compact modulators based on novel CMOS-compatible plasmonic materials

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    We propose several planar layouts of ultra-compact plasmonic waveguide modulators that utilize alternative CMOS-compatible materials. The modulation is efficiently achieved by tuning the carrier concentration in a transparent conducting oxide layer, thereby tuning the waveguide either in plasmonic resonance or off-resonance. Resonance significantly increases the absorption coefficient of the plasmonic waveguide, which enables larger modulation depth. We show that an extinction ratio of 86 dB/um can be achieved, allowing for a 3-dB modulation depth in less than one micron at the telecommunication wavelength. Our multilayer structures can potentially be integrated with existing plasmonic and photonic waveguides as well as novel semiconductor-based hybrid photonic/electronic circuits
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