144 research outputs found

    Wind loads analysis at the anchorages of the Talavera de la Reina cable stayed bridge

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    This paper describes wind tunnel tests performed on wind tunnel models of the Talavera de la Reina cable stayed bridge. The work describes the aeroelastic model construction and it is focused on the evaluation and analysis of the mean and peak wind loads at the tower foundation and the cable anchorages since these data can be very useful by the bridge manufacturer as a support for the bridge design. The work is part of a complete wind tunnel study carried out to analyze the aeroelastic stability of the bridge

    Learning to Teach through Self-Awareness and Acceptance

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    This article is an account of my first teaching experience as a PhD student. It is the story of my personal journey toward self-discovery in which I learned to integrate my clinical social work skills into my teaching. This article details a variety of emotions and struggles experienced both by my students and myself. This narrative describes how I came to be a more conscientious instructor, how I learned to link lessons from the clinical world to my teaching, and how my learning process included significant advances of self-discovery and personal growth. Through this experience, I came to understand that pedagogy and clinical techniques can dovetail, demonstrating the need to individualize interventions, build community with stakeholders, and foster trusting relationships

    Dealing with adversity: religiosity or science? Evidence from the great influenza pandemic

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    How do societies respond to adversity? After a negative shock, separate strands of research document either an increase in religiosity or a boost in innovation efforts. In this paper, we show that both reactions can occur at the same time, driven by different individuals within society. The setting of our study is the 1918-1919 influenza pandemic in the United States. To measure religiosity, we construct a novel indicator based on naming patterns of newborns. We measure innovation through the universe of granted patents. Exploiting plausibly exogenous county-level variation in exposure to the pandemic, we provide evidence that more-affected counties become both more religious and more innovative. Looking within counties, we uncover heterogeneous responses: individuals from more religious backgrounds further embrace religion, while those from less religious backgrounds become more likely to choose a scientific occupation. Facing adversity widens the distance in religiosity between science-oriented individuals and the rest of the population, and it increases the polarization of religious beliefs

    An imaged 15Mjup companion within a hierarchical quadruple system

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    Since 2019, the direct imaging B-star Exoplanet Abundance Study (BEAST) at SPHERE@VLT has been scanning the surroundings of young B-type stars in order to ascertain the ultimate frontiers of giant planet formation. Recently, the 174+317^{+3}_{-4} Myr HIP 81208 was found to host a close-in (~50 au) brown dwarf and a wider (~230 au) late M star around the central 2.6Msun primary. Alongside the continuation of the survey, we are undertaking a complete reanalysis of archival data aimed at improving detection performances so as to uncover additional low-mass companions. We present here a new reduction of the observations of HIP 81208 using PACO ASDI, a recent and powerful algorithm dedicated to processing high-contrast imaging datasets, as well as more classical algorithms and a dedicated PSF-subtraction approach. The combination of different techniques allowed for a reliable extraction of astrometric and photometric parameters. A previously undetected source was recovered at a short separation from the C component of the system. Proper motion analysis provided robust evidence for the gravitational bond of the object to HIP 81208 C. Orbiting C at a distance of ~20 au, this 15Mjup brown dwarf becomes the fourth object of the hierarchical HIP 81208 system. Among the several BEAST stars which are being found to host substellar companions, HIP 81208 stands out as a particularly striking system. As the first stellar binary system with substellar companions around each component ever found by direct imaging, it yields exquisite opportunities for thorough formation and dynamical follow-up studies.Comment: 12 pages, 9 figures, 5 tables. Accepted for publication as a Letter in Astronomy and Astrophysics, section 1. Letters to the Edito

    Implications of the discovery of AF Lep b. The mass-luminosity relation for planets in the β Pic Moving Group and the L–T transition for young companions and free-floating planets

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    This is the final version. Available on open access from EDP Sciences via the DOI in this recordContext. Dynamical masses of young planets aged between 10 and 200 Myr detected in imaging play a crucial role in shaping models of giant planet formation. Regrettably, only a few such objects possess these characteristics. Furthermore, the evolutionary pattern of young sub-stellar companions in near-infrared colour-magnitude diagrams might diverge from free-floating objects, possibly due to differing formation processes. Aims. The recent identification of a giant planet around AF Lep, part of the β Pic moving group (BPMG), encouraged us to re-examine these points. Methods. We considered updated dynamical masses and luminosities for the sub-stellar objects in the BPMG. In addition, we compared the properties of sub-stellar companions and free-floating objects in the BPMG and other young associations remapping the positions of the objects in the colour-magnitude diagram into a dustiness-temperature plane. Results. We found that cold-start evolutionary models do not reproduce the mass-luminosity relation for sub-stellar companions in the BPMG. This aligns rather closely with predictions from “hot start” scenarios and is consistent with recent planet formation models. We obtain rather good agreement with masses from photometry and the remapping approach compared to actual dynamical masses. We also found a strong suggestion that the near-infrared colour-magnitude diagram for young companions is different from that of free-floating objects belonging to the same young associations. Conclusions. If confirmed by further data, this last result would imply that cloud settling – which likely causes the transition between L and T spectral type – occurs at a lower effective temperature in young companions than in free-floating objects. This might tentatively be explained with a different chemical composition.Royal Societ

    TOI-179: a young system with a transiting compact Neptune-mass planet and a low-mass companion in outer orbit

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    Transiting planets around young stars are key benchmarks for our understanding of planetary systems. One of such candidates was identified around the K dwarf HD 18599 by TESS, labeled as TOI-179. We present the confirmation of the transiting planet and the characterization of the host star and of the TOI-179 system over a broad range of angular separations. To this aim, we exploited the TESS photometric time series, intensive radial velocity monitoring performed with HARPS, and deep high-contrast imaging observations obtained with SPHERE and NACO at VLT. The inclusion of Gaussian processes regression analysis is effective to properly model the magnetic activity of the star and identify the Keplerian signature of the transiting planet. The star, with an age of 400+-100 Myr, is orbited by a transiting planet with period 4.137436 days, mass 24+-7 Mearth, radius 2.62 (+0.15-0.12) Rearth, and significant eccentricity (0.34 (+0.07-0.09)). Adaptive optics observations identified a low-mass companion at the boundary between brown dwarfs and very low mass stars (mass derived from luminosity 83 (+4-6) Mjup) at a very small projected separation (84.5 mas, 3.3 au at the distance of the star). Coupling the imaging detection with the long-term radial velocity trend and the astrometric signature, we constrained the orbit of the low mass companion, identifying two families of possible orbital solutions. The TOI-179 system represents a high-merit laboratory for our understanding of the physical evolution of planets and other low-mass objects and of how the planet properties are influenced by dynamical effects and interactions with the parent star.Comment: 25 pages, 24 figures, A&A, in pres

    The high-albedo, low polarization disk around HD 114082 harbouring a Jupiter-sized transiting planet

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    We present new optical and near-IR images of debris disk around the F-type star HD 114082. We obtained direct imaging observations and analysed the TESS photometric time series data of this target with a goal to search for planetary companions and to characterise the morphology of the debris disk and the scattering properties of dust particles. HD 114082 was observed with the VLT/SPHERE instrument: the IRDIS camera in the K band together with the IFS in the Y, J and H band using the ADI technique as well as IRDIS in the H band and ZIMPOL in the I_PRIME band using the PDI technique. The scattered light images were fitted with a 3D model for single scattering in an optically thin dust disk. We performed aperture photometry in order to derive the scattering and polarized phase functions, polarization fraction and spectral scattering albedo for the dust particles in the disk. This method was also used to obtain the reflectance spectrum of the disk to retrieve the disk color and study the dust reflectivity in comparison to the debris disk HD 117214. We also performed the modeling of the HD 114082 light curve measured by TESS using the models for planet transit and stellar activity to put constraints on radius of the detected planet and its orbit. The debris disk appears as an axisymmetric debris belt with a radius of ~0.37"" (35 au), inclination of ~83^\circ and a wide inner cavity. Dust particles in HD 114082 have a maximum polarization fraction of ~17% and a high reflectivity which results in a spectral scattering albedo of 0.65. The analysis of TESS photometric data reveals a transiting planetary companion to HD 114082 with a radius of \sim1~RJ\rm R_{J} on an orbit with a semi-major axis of 0.7±0.40.7 \pm 0.4 au. Combining different data, we reach deep sensitivity limits in terms of companion masses down to ~5MJupM_{\rm Jup} at 50 au, and ~10 MJupM_{\rm Jup} at 30 au from the central star.Comment: 27 page
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