582 research outputs found

    Superconducting atomic contacts inductively coupled to a microwave resonator

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    We describe and characterize a microwave setup to probe the Andreev levels of a superconducting atomic contact. The contact is part of a superconducting loop inductively coupled to a superconducting coplanar resonator. By monitoring the resonator reflection coefficient close to its resonance frequency as a function of both flux through the loop and frequency of a second tone we perform spectroscopy of the transition between two Andreev levels of highly transmitting channels of the contact. The results indicate how to perform coherent manipulation of these states.Comment: 14 pages, 10 figures, to appear in special issue on break-junctions in JOPC

    Eruption and propagation of twisted flux ropes from the base of the solar corona to 1 au

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    Interplanetary Coronal Mass Ejections (ICMEs) originate from the eruption of complex magnetic structures occurring in our star's atmosphere. Determining the general properties of ICMEs and the physical processes at the heart of their interactions with the solar wind is a hard task, in particular using only unidimensional in situ profiles. Thus, these phenomena are still not well understood. In this study we simulate the propagation of a set of flux ropes in order to understand some of the physical processes occurring during the propagation of an ICME such as their growth or their rotation. We present simulations of the propagation of a set of flux ropes in a simplified solar wind. We consider different magnetic field strengths and sizes at the initiation of the eruption, and characterize their influence on the properties of the flux ropes during their propagation. We use the 3D MHD module of the PLUTO code on an Adaptive Mesh Refinement grid. The evolution of the magnetic field of the flux rope during the propagation matches evolution law deduced from in situ observations. We also simulate in situ profiles that spacecraft would have measured at the Earth, and we compare with the results of statistical studies. We find a good match between simulated in situ profiles and typical profiles obtained in these studies. During their propagation, flux ropes interact with the magnetic field of the wind but still show realistic signatures of ICMEs when analyzed with synthetic satellite crossings. We also show that flux ropes with different shapes and orientations can lead to similar unidimensional crossings. This warrants some care when extracting magnetic topology of ICMEs using unidimensional crossings.Comment: Accepted for publication A&A. 14 pages, 9 figures, 3 table

    What Is the Interest of Klinefelter's Syndrome for (Child) Psychiatrists?

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    peer reviewedÀ partir de la prise en charge psychiatrique et endocrinologique à l'âge de 22 ans d'un patient atteint d'un trouble schizoaffectif et d'un syndrome de Klinefelter (SK), nous présentons les aspects psychopathologiques de ce syndrome qui est fréquent (près d'un garçon sur 500 à la naissance) et dont, le plus souvent, le diagnostic n'est pas posé. Les garçons atteints de ce syndrome ont généralement un retard d'acquisition du langage, un QI verbal inférieur à la moyenne et un QI global dans les limites de la normale. Sans suivi spécifique, le risque de troubles psychiatriques (de tous types) est plus élevé que celui de la population générale, comme le prouvent des études réalisées en milieu psychiatrique. En cas d'hypotestostéronémie (très fréquente), un traitement substitutif par undécanoate de testostérone devrait être instauré (idéalement entre 11 et 15 ans, mais le diagnostic est souvent posé à l'âge adulte) pour ses effets bénéfiques somatiques et psychiques. Jusqu'à présent, aucune donnée fiable dans la littérature ne contre-indique formellement un traitement par androgènes en cas de trouble psychiatrique grave. Cependant, chaque situation devra être évaluée attentivement ; l'éventuelle androgénothérapie doit être intro­ duite progressivement et sera associée à une évaluation psychiatrique très régulière

    Multi-Channel Auto-Calibration for the Atmospheric Imaging Assembly using Machine Learning

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    Solar activity plays a quintessential role in influencing the interplanetary medium and space-weather around the Earth. Remote sensing instruments onboard heliophysics space missions provide a pool of information about the Sun's activity via the measurement of its magnetic field and the emission of light from the multi-layered, multi-thermal, and dynamic solar atmosphere. Extreme UV (EUV) wavelength observations from space help in understanding the subtleties of the outer layers of the Sun, namely the chromosphere and the corona. Unfortunately, such instruments, like the Atmospheric Imaging Assembly (AIA) onboard NASA's Solar Dynamics Observatory (SDO), suffer from time-dependent degradation, reducing their sensitivity. Current state-of-the-art calibration techniques rely on periodic sounding rockets, which can be infrequent and rather unfeasible for deep-space missions. We present an alternative calibration approach based on convolutional neural networks (CNNs). We use SDO-AIA data for our analysis. Our results show that CNN-based models could comprehensively reproduce the sounding rocket experiments' outcomes within a reasonable degree of accuracy, indicating that it performs equally well compared with the current techniques. Furthermore, a comparison with a standard "astronomer's technique" baseline model reveals that the CNN approach significantly outperforms this baseline. Our approach establishes the framework for a novel technique to calibrate EUV instruments and advance our understanding of the cross-channel relation between different EUV channels.Comment: 12 pages, 7 figures, 8 tables. This is a pre-print of an article submitted and accepted by A&A Journa

    Coherent manipulation of Andreev states in superconducting atomic contacts

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    Coherent control of quantum states has been demonstrated in a variety of superconducting devices. In all these devices, the variables that are manipulated are collective electromagnetic degrees of freedom: charge, superconducting phase, or flux. Here, we demonstrate the coherent manipulation of a quantum system based on Andreev bound states, which are microscopic quasiparticle states inherent to superconducting weak links. Using a circuit quantum electrodynamics setup we perform single-shot readout of this "Andreev qubit". We determine its excited state lifetime and coherence time to be in the microsecond range. Quantum jumps and parity switchings are observed in continuous measurements. In addition to possible quantum information applications, such Andreev qubits are a testbed for the physics of single elementary excitations in superconductors.Comment: Supplementary Materials at the end of the fil

    A multiple spacecraft detection of the 2 April 2022 M-class flare and filament eruption during the first close Solar Orbiter perihelion

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    CONTEXT: The Solar Orbiter mission completed its first remote-sensing observation windows in the spring of 2022. On 2 April 2022, an M-class flare followed by a filament eruption was seen both by the instruments on board the mission and from several observatories in Earth’s orbit, providing an unprecedented view of a flaring region with a large range of observations. AIMS: We aim to understand the nature of the flaring and filament eruption events via the analysis of the available dataset. The complexity of the observed features is compared with the predictions given by the standard flare model in 3D. METHOD: In this paper, we use the observations from a multi-view dataset, which includes extreme ultraviolet (EUV) imaging to spectroscopy and magnetic field measurements. These data come from the Interface Region Imaging Spectrograph, the Solar Dynamics Observatory, Hinode, as well as several instruments on Solar Orbiter. RESULTS: The large temporal coverage of the region allows us to analyse the whole sequence of the filament eruption starting with its pre-eruptive state. Information given by spectropolarimetry from SDO/HMI and Solar Orbiter PHI/HRT shows that a parasitic polarity emerging underneath the filament is responsible for bringing the flux rope to an unstable state. As the flux rope erupts, Hinode EIS captures blue-shifted emission in the transition region and coronal lines in the northern leg of the flux rope prior to the flare peak. This may be revealing the unwinding of one of the flux rope legs. At the same time, Solar Orbiter SPICE captures the whole region, complementing the Doppler diagnostics of the filament eruption. Analyses of the formation and evolution of a complex set of flare ribbons and loops, of the hard and soft X-ray emissions with STIX, show that the parasitic emerging bipole plays an important role in the evolution of the flaring region. CONCLUSIONS: The extensive dataset covering this M-class flare event demonstrates how important multiple viewpoints and varied observations are in order to understand the complexity of flaring regions. While the analysed data are overall consistent with the standard flare model, the present particular magnetic configuration shows that surrounding magnetic activity such as nearby emergence needs to be taken into account to fully understand the processes at work. This filament eruption is the first to be covered from different angles by spectroscopic instruments, and provides an unprecedented diagnostic of the multi-thermal structures present before and during the flare. This complete dataset of an eruptive event showcases the capabilities of coordinated observations with the Solar Orbiter mission

    New data on the Silurian-Devonian paleontology and biostratigraphy of Bolivia

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    P. 269-314In order to precisely establish the bio- and chronostratigraphic position of several levels of the Silurian–Devonian succession of Bolivia, with respect to the International Time Scale, additional Silurian and Devonian localities belonging to the Eastern Cordillera and the Interandean Zone areas have been recently revised and sampled, both for macrofossils and palynomorphs. Specifically, the localities are Ñuñumayani, and Muruhuta from the late Silurian–early Devonian time interval. Correlations with other fossiliferous localities are discussed, namely Huacallani and Rumicorral.S
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