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| 3. |
- Cheetham, A. C., et al.
(författare)
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Spectral and orbital characterisation of the directly imaged giant planet HIP 65426 b
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 622
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Tidskriftsartikel (refereegranskat)abstract
- HIP 65426 b is a recently discovered exoplanet imaged during the course of the SPHERE-SHINE survey. Here we present new L' and M' observations of the planet from the NACO instrument at the VLT from the NACO-ISPY survey, as well as a new Y-H spectrum and K-band photometry from SPHERE-SHINE. Using these data, we confirm the nature of the companion as a warm, dusty planet with a mid-L spectral type. From comparison of its SED with the BT-Settl atmospheric models, we derive a best-fit effective temperature of T-eff = 1618 +/- 7 K, surface gravity log g = 3 : 78(-0.03)(+0.04) and radius R = 1.17 +/- 0.04 R-J (statistical uncertainties only). Using the DUSTY and COND isochrones we estimate a mass of 8 +/- 1 MJ. Combining the astrometric measurements from our new datasets and from the literature, we show the first indications of orbital motion of the companion (2.6 sigma significance) and derive preliminary orbital constraints. We find a highly inclined orbit (i = 107(+13)(-10) deg) with an orbital period of 800(+1200)(-400) yr. We also report SPHERE sparse aperture masking observations that investigate the possibility that HIP 65426 b was scattered onto its current orbit by an additional companion at a smaller orbital separation. From this data we rule out the presence of brown dwarf companions with masses greater than 16 M-J at separations larger than 3AU, significantly narrowing the parameter space for such a companion.
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| 4. |
- Massarotti, D., et al.
(författare)
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What happens in Josephson junctions at high critical current densities
- 2017
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Ingår i: Fizika Nizkih Temperatur. - : AIP Publishing. - 1816-0328 .- 0132-6414. ; 43:7, s. 816-823
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Tidskriftsartikel (refereegranskat)abstract
- The impressive advances in material science and nanotechnology are more and more promoting the use of exotic barriers and/or superconductors, thus paving the way to new families of Josephson junctions. Semiconducting, ferromagnetic, topological insulator and graphene barriers are leading to unconventional and anomalous aspects of the Josephson coupling, which might be useful to respond to some issues on key problems of solid state physics. However, the complexity of the layout and of the competing physical processes occurring in the junctions is posing novel questions on the interpretation of their phenomenology. We classify some significant behaviors of hybrid and unconventional junctions in terms of their first imprinting, i.e. current-voltage curves, and propose a phenomenological approach to describe some features of junctions characterized by relatively high critical current densities Jc. Accurate arguments on the distribution of switching currents will provide quantitative criteria to understand physical processes occurring in high-Jc junctions. These notions are universal and apply to all kinds of junctions. PACS: 74.72.-h Cuprate superconductors; 85.25.Cp Josephson devices; 74.50.+r Tunneling phenomena; Josephson effects.
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- van de Laar, IMBH, et al.
(författare)
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European reference network for rare vascular diseases (VASCERN) consensus statement for the screening and management of patients with pathogenic ACTA2 variants
- 2019
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Ingår i: Orphanet journal of rare diseases. - : Springer Science and Business Media LLC. - 1750-1172. ; 14:1, s. 264-
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Tidskriftsartikel (refereegranskat)abstract
- The ACTA2 gene encodes for smooth muscle specific α-actin, a critical component of the contractile apparatus of the vascular smooth muscle cell. Pathogenic variants in the ACTA2 gene are the most frequently encountered genetic cause of non-syndromic hereditary thoracic aortic disease (HTAD). Although thoracic aortic aneurysm and/or dissection is the main clinical manifestation, a variety of occlusive vascular disease and extravascular manifestations occur in ACTA2-related vasculopathy. Current data suggest possible mutation-specific manifestations of vascular and extra-aortic traits.Despite its relatively high prevalence, comprehensive recommendations on the care of patients and families with pathogenic variants in ACTA2 have not yet been established. We aimed to develop a consensus document to provide medical guidance for health care professionals involved in the diagnosis and treatment of patients and relatives with pathogenic variants in ACTA2.The HTAD Working Group of the European Reference Network for Rare Vascular Diseases (VASCERN) convened to review current literature and discuss expert opinions on clinical management of ACTA2 related vasculopathy. This consensus statement summarizes our recommendations on diagnosis, monitoring, treatment, pregnancy, genetic counselling and testing in patients with ACTA2-related vasculopathy. However, there is a clear need for additional prospective multicenter studies to further define proper guidelines.
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| 6. |
- Marconi, A., et al.
(författare)
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ELT-HIRES, the high resolution spectrograph for the ELT : results from the Phase A study
- 2018
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY VII. - : SPIE-INT SOC OPTICAL ENGINEERING. - 9781510619586
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Konferensbidrag (refereegranskat)abstract
- We present the results from the phase A study of ELT-HIRES, an optical-infrared High Resolution Spectrograph for ELT, which has just been completed by a consortium of 30 institutes from 12 countries forming a team of about 200 scientists and engineers. The top science cases of ELT-HIRES will be the detection of life signatures from exoplanet atmospheres, tests on the stability of Nature's fundamental couplings, the direct detection of the cosmic acceleration. However, the science requirements of these science cases enable many other groundbreaking science cases. The baseline design, which allows to fulfil the top science cases, consists in a modular fiber fed cross-dispersed echelle spectrograph with two ultra-stable spectral arms providing a simultaneous spectral range of 0.4-1.8 pm at a spectral resolution of 100, 000. The fiber-feeding allows ELT-HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU.
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| 7. |
- Massarotti, D., et al.
(författare)
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Hysteretic Critical State in Coplanar Josephson Junction with Monolayer Graphene Barrier
- 2017
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1947 .- 1557-1939. ; 30:1, s. 5-14
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Tidskriftsartikel (refereegranskat)abstract
- Coplanar Al/graphene/Al junctions fabricated on the same graphene sheet deposited on silicon carbide (SiC), show robust Josephson coupling at subKelvin temperature, when the separations between the electrodes is below 400 nm. Remarkably, a hysteretic Critical State sets in when ramping an orthogonal magnetic field, with a sudden collapse of the Josephson critical current I (c) when turning the field on, and a revival of I (c) when inverting the sweep. Similar hysteresis can be found in granular superconducting films which may undergo the Berezinskii-Kosterlitz-Thouless transition. Here, we give quantitative arguments to prove that this odd behavior of the magnetoconductance gives evidence for an incipient Berezinskii-Kosterlitz-Thouless transition with drift and pinning of fluctuating free vortices induced by the current bias.
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| 8. |
- Arpaia, Riccardo, 1985, et al.
(författare)
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High-temperature superconducting nanowires for photon detection
- 2015
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Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 509, s. 16-21
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Tidskriftsartikel (refereegranskat)abstract
- The possible use of high-temperature superconductors (HTS) for realizing superconducting nanowire single-photon detectors is a challenging, but also promising, aim because of their ultrafast electron relaxation times and high operating temperatures. The state-of-the-art HTS nanowires with a 50-nm thickness and widths down to 130 nm have been fabricated and tested under a 1550-nm wavelength laser irradiation. Experimental results presenting both the amplitude and rise times of the photoresponse signals as a function of the normalized detector bias current, measured in a wide temperature range, are discussed. The presence of two distinct regimes in the photoresponse temperature dependence is clearly evidenced, indicating that there are two different response mechanisms responsible for the HTS photoresponse mechanisms.
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| 9. |
- Ejrnaes, M., et al.
(författare)
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Observation of dark pulses in 10nm thick YBCO nanostrips presenting hysteretic current voltage characteristics
- 2017
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Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 30:12
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Tidskriftsartikel (refereegranskat)abstract
- We have fabricated several 10 nm thick and 65 nm wide YBa2Cu3O7-? (YBCO) nanostrips. The nanostrips with the highest critical current densities are characterized by hysteretic current voltage characteristics (IVCs) with a direct bistable switch from the zero-voltage to the finite voltage state. The presence of hysteretic IVCs allowed the observation of dark pulses due to fluctuations phenomena. The key role of the bistable behavior is its ability to transform a small disturbance (e.g. an intrinsic fluctuation) into a measurable transient signal, i.e. a dark pulse. On the contrary, in devices characterized by lower critical current density values, the IVCs are nonhysteretic and dark pulses have not been observed. To investigate the physical origin of the dark pulses, we have measured the bias current dependence of the dark pulse rate: The observed exponential increase with the bias current is compatible with mechanisms based on thermal activation of magnetic vortices in the nanostrip. We believe that the successful amplification of small fluctuation events into measurable signals in nanostrips of ultrathin YBCO is a milestone for further investigation of YBCO nanostrips for superconducting nanostrip single photon detectors and other quantum detectors for operation at higher temperatures.
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| 10. |
- Marconi, A., et al.
(författare)
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EELT-HIRES the high-resolution spectrograph for the E-ELT
- 2016
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY VI. - : SPIE. - 9781510601963
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Konferensbidrag (refereegranskat)abstract
- The first generation of E-ELT instruments will include an optical infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study.
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