The ESPRI project: astrometric exoplanet search with PRIMA I. Instrument description and performance of first light observations

The ESPRI project relies on the astrometric capabilities offered by the PRIMA facility of the Very Large Telescope Interferometer for the discovery and study of planetary systems. Our survey consists of obtaining high-precision astrometry for a large sample of stars over several years and to detect their barycentric motions due to orbiting planets. We present the operation principle, the instrument's implementation, and the results of a first series of test observations. A comprehensive overview of the instrument infrastructure is given and the observation strategy for dual-field relative astrometry is presented. The differential delay lines, a key component of the PRIMA facility which was delivered by the ESPRI consortium, are described and their performance within the facility is discussed. Observations of bright visual binaries are used to test the observation procedures and to establish the instrument's astrometric precision and accuracy. The data reduction strategy for astrometry and the necessary corrections to the raw data are presented. Adaptive optics observations with NACO are used as an independent verification of PRIMA astrometric observations. The PRIMA facility was used to carry out tests of astrometric observations. The astrometric performance in terms of precision is limited by the atmospheric turbulence at a level close to the theoretical expectations and a precision of 30 micro-arcseconds was achieved. In contrast, the astrometric accuracy is insufficient for the goals of the ESPRI project and is currently limited by systematic errors that originate in the part of the interferometer beamtrain which is not monitored by the internal metrology system. Our observations led to the definition of corrective actions required to make the facility ready for carrying out the ESPRI search for extrasolar planets.Comment: 32 pages, 39 figures, Accepted for publication in Astronomy and Astrophysic

The European Solar Telescope

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems

The European Solar Telescope

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l’Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems

Impact of the vagus nerve stimulation on sleep- related breathing disorders in patients with epilepsy

Abstract Background Vagus nerve stimulation (VNS) is a palliative treatment for refractory epilepsy that can induce a sleep apnea syndrome (SAS). Until now, prevalence of VNS-induced SAS and risk factors for developing it have barely been studied. The purpose of this study is to estimate the prevalence of a VNS-induced SAS and to identify if any clinical variable correlates with development of SAS after VNS implantation. Methods We analyzed the computerized medical records of 18 adults treated for refractory epilepsy who were implanted with a VNS at the University Hospital of Lausanne (CHUV), Switzerland between May 2008 and May 2017. The patients underwent a polygraphy (PG) or a polysomnography (PSG) before and after VNS implantation to screen for SAS. We compared retrospectively demographic variables, variables related to the epilepsy, and to the device’s parameters between the patient with and without SAS. Results In out cohort the prevalence of VNS-induced SAS was 27.8%. We did not find any statistically significant difference between the variables in the two groups but we found some trends in terms of medication, intensity of the stimulation and OFF time of the device. Conclusion The relatively high SAS prevalence that we observed and the lack of identified risk factors for developing SAS suggest that a screening for SAS before and after VNS implantation may represent a reasonable practice for every adult patient

Rivoluzione e purismo. Ricezione italiana e fortuna editoriale della “Storia della guerra dell’independenza”

Il contributo prende in considerazione la fortuna di uno dei principali libri di lettura della generazione risorgimentale, che, stampato per la prima volta nel 1809 a Parigi, inizialmente non ha successo per la scelta del purismo (scelta che Botta prende tuttavia consapevolmente per ribadire il primato culturale italiano contro il soffocante abbraccio francese). Il successo inizia con la stampa Ferrario (1819, con più di 400 luoghi emendati), intrecciandosi non solo alla nascita del movimento nazionale ma anche ai successi della "Storia d’Italia" per cui Botta nel 1830 aveva ottenuto il premio (a scapito di Leopardi) nel concorso quinquennale bandito dall’Accademia della Crusca

Algarotti e Federico il Grande: un doppio omaggio in versi

In the summer of 1739, Francesco Algarotti returned from St. Petersburg where he had been a member of an English delegation charged with representing the King George II at the wedding celebrations of the crown prince of Russia. At Rheinsberg he met Frederick of Hohenzollern, soon to become King of Prussia, and immediately wrote an epistle in verse to celebrate his magnificence and humanity. Through appropriate comparison between this first unpublished draft and its derivative (printed in 1755), and another laudatory later poem whose detached tone reflects the disappointments that led the author to spend a long time away from his patron, the article investigates the complexity of his relations with Frederick, noting that, following a clear Horatian line, Algarotti wrote a persuasive Oratio based on the principle that sovereignty can be recognized by the poet-philosopher only when he knows that support is guaranteed for letters and the arts

Lo scienziato sul vulcano: Spallanzani, Mascheroni, Galiani

Soprattutto dopo l’eruzione vesuviana del 1631, l’interesse per i vulcani diviene preponderante, fino ad assumere i caratteri di un vero e proprio topos letterario. Nel Settecento il nuovo atteggiamento sperimentale della filosofia naturale guida sui crateri dell’Italia meridionale un numero sempre maggiore di studiosi che affrontano l’ascesa a scopi scientifici. Il contributo si sofferma sulle rappresentazioni dei vulcani fornite nella seconda metà del secolo da Lazzaro Spallanzani, Lorenzo Mascheroni e Ferdinando Galiani. Mentre nei primi due esattezza e precisione dell’osservazione si accompagnano alla meraviglia provata di fronte a panorami suggestivi e all’entusiasmo per la forza potenzialmente distruttiva della natura, Galiani affianca a scrupolosi studi vulcanologici una lettura parodica volta a prendere le distanze da una folta e incontrollata trattatistica.

Il Parnaso degli uomini illustri: gli "Elogj italiani" di Andrea Rubbi

Il contributo prende in considerazione i 12 voll. degli "Elogi" di Andrea Rubbi (1782-1783), fra le ultime enciclopedie biografiche di ampio respiro del XVIII secolo, da collocare nel segno di un patriottismo letterario italiano, nella strenua volontà di difesa della gloria nazionale dalla concorrenza letteraria straniera. Si osserva la tendenza a privilegiare l’elogio dei moderni, come sarà palese nell’impresa successiva, ovvero i 56 volumi del "Parnaso italiano", chiaramente sbilanciati sul versante settecentesco

«Frigio-Vandala stirpe»: precettori e discepoli nella "Vita" e nelle "Satire"

L’intervento presenta un quadro delle consuetudini pedagogiche dell’aristocrazia piemontese delineato da Alfieri nella "Vita" e nella sesta satira sull’"Educazione", trasposizione caricaturale di una situazione personalmente vissuta e patita, e intermedia tra le due redazioni dell’autobiografia, che condanna senza appello i cattivi maestri. Costruite sulle brevi battute di dialogo fra il borioso aristocratico e il modesto precettore, le terzine mettono in luce la scarsa rilevanza dell’educazione in sé e la bassa collocazione dei docenti nella scala sociale. Né è da escludere che la sesta satira di Ariosto "A Messer Pietro Bembo" sull’educazione, pur nella diversità di un registro esplicitamente oraziano, abbia lasciato traccia nella memoria letteraria di Alfieri