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See detailThe path towards high-contrast imaging with the VLTI: the Hi-5 project
Defrere, Denis ULiege; Absil, Olivier ULiege; Berger, J.-P. et al

in Experimental Astronomy: Astrophysical Instrumentation and Methods (in press), 1801

The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10$^{-3}$ in the near-infrared ... [more ▼]

The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10$^{-3}$ in the near-infrared with PIONIER (H band) and GRAVITY (K band). Nulling interferometers in the northern hemisphere and non-redundant aperture masking experiments have, however, demonstrated that contrasts of at least a few 10$^{-4}$ are within reach using specific beam combination and data acquisition techniques. In this paper, we explore the possibility to reach similar or higher contrasts on the VLTI. After reviewing the state-of-the-art in high-contrast infrared interferometry, we discuss key features that made the success of other high-contrast interferometric instruments (e.g., integrated optics, nulling, closure phase, and statistical data reduction) and address possible avenues to improve the contrast of the VLTI by at least one order of magnitude. In particular, we discuss the possibility to use integrated optics, proven in the near-infrared, in the thermal near-infrared (L and M bands, 3-5 $\mu$m), a sweet spot to image and characterize young extra-solar planetary systems. Finally, we address the science cases of a high-contrast VLTI imaging instrument and focus particularly on exoplanet science (young exoplanets, planet formation, and exozodiacal disks), stellar physics (fundamental parameters and multiplicity), and extragalactic astrophysics (active galactic nuclei and fundamental constants). Synergies and scientific preparation for other potential future instruments such as the Planet Formation Imager are also briefly discussed. [less ▲]

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See detailUltrafast double magnetization switching in GdFeCo with two picosecond-delayed femtosecond pump pulses
Atxitia, U; Ostler, Thomas ULiege

in Applied Physics Letters (2018), 113

The recently discovered thermally induced magnetization switching (TIMS) inducedby single femtosecond laser pulses in ferrimagnetic GdFeCo alloys proceeds on the picosecond time-scale. The rate at which ... [more ▼]

The recently discovered thermally induced magnetization switching (TIMS) inducedby single femtosecond laser pulses in ferrimagnetic GdFeCo alloys proceeds on the picosecond time-scale. The rate at which data can be changed for use of TIMS in technological devices is limited by the processes leading to thermal equilibrium. In the present work, we address the question of whether it is possible to further excite switching via TIMS well before thermal equilibrium between subsystems is reached. In particular, we investigate the conditions for double thermally induced magnetic switching by the application of two shortly delayed laser pulses. These conditions become relevant for potential applications as it sets both a limit to rewrite data and demonstrates the importance of spatial confinement of a heat pulse to bit size, as neighboring bits may be accidentally re-switched for spatially extended pulse spots. To demonstrate this effect, we theoretically study the switching behavior in a prototypical ferrimagnetic GdFeCo alloy as a function of composition. We use computer simulations based on thermal atomistic spin dynamics and demonstrate the possibility of inducing a second switching event well before thermal equilibrium is reached and define the conditions under which it can occur. Our theoretical findings could serve as a guidance for further understanding of TIMS as well as to act as a guide for future applications. [less ▲]

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See detailGaia Data Release 2. Processing the spectroscopic data
Sartoretti, P.; Katz, D.; Cropper, M. et al

in Astronomy and Astrophysics (2018), 616(A), 6

Context. The Gaia Data Release 2 (DR2) contains the first release of radial velocities complementing the kinematic data of a sample of about 7 million relatively bright, late-type stars. <BR /> Aims: This ... [more ▼]

Context. The Gaia Data Release 2 (DR2) contains the first release of radial velocities complementing the kinematic data of a sample of about 7 million relatively bright, late-type stars. <BR /> Aims: This paper provides a detailed description of the Gaia spectroscopic data processing pipeline, and of the approach adopted to derive the radial velocities presented in DR2. <BR /> Methods: The pipeline must perform four main tasks: (i) clean and reduce the spectra observed with the Radial Velocity Spectrometer (RVS); (ii) calibrate the RVS instrument, including wavelength, straylight, line-spread function, bias non- uniformity, and photometric zeropoint; (iii) extract the radial velocities; and (iv) verify the accuracy and precision of the results. The radial velocity of a star is obtained through a fit of the RVS spectrum relative to an appropriate synthetic template spectrum. An additional task of the spectroscopic pipeline was to provide first-order estimates of the stellar atmospheric parameters required to select such template spectra. We describe the pipeline features and present the detailed calibration algorithms and software solutions we used to produce the radial velocities published in DR2. <BR /> Results: The spectroscopic processing pipeline produced median radial velocities for Gaia stars with narrow-band near-IR magnitude G[SUB]RVS[/SUB] ≤ 12 (i.e. brighter than V 13). Stars identified as double-lined spectroscopic binaries were removed from the pipeline, while variable stars, single- lined, and non-detected double-lined spectroscopic binaries were treated as single stars. The scatter in radial velocity among different observations of a same star, also published in Gaia DR2, provides information about radial velocity variability. For the hottest (T[SUB]eff[/SUB] ≥ 7000 K) and coolest (T[SUB]eff[/SUB] ≤ 3500 K) stars, the accuracy and precision of the stellar parameter estimates are not sufficient to allow selection of appropriate templates. The radial velocities obtained for these stars were removed from DR2. The pipeline also provides a first-order estimate of the performance obtained. The overall accuracy of radial velocity measurements is around 200-300 m s[SUP]-1[/SUP], and the overall precision is 1 km s[SUP]-1[/SUP]; it reaches 200 m s[SUP]-1[/SUP] for the brightest stars. [less ▲]

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See detailGaia Data Release 2. Gaia Radial Velocity Spectrometer
Cropper, M.; Katz, D.; Sartoretti, P. et al

in Astronomy and Astrophysics (2018), 616(A), 5

This paper presents the specification, design, and development of the Radial Velocity Spectrometer (RVS) on the European Space Agency's Gaia mission. Starting with the rationale for the full six ... [more ▼]

This paper presents the specification, design, and development of the Radial Velocity Spectrometer (RVS) on the European Space Agency's Gaia mission. Starting with the rationale for the full six dimensions of phase space in the dynamical modelling of the Galaxy, the scientific goals and derived top-level instrument requirements are discussed, leading to a brief description of the initial concepts for the instrument. The main part of the paper is a description of the flight RVS, considering the optical design, the focal plane, the detection and acquisition chain, and the as-built performance drivers and critical technical areas. After presenting the pre-launch performance predictions, the paper concludes with the post-launch developments and mitigation strategies, together with a summary of the in-flight performance at the end of commissioning. [less ▲]

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See detailGaia Data Release 2. Mapping the Milky Way disc kinematics
Gaia Collaboration; Katz, D.; Antoja, T. et al

in Astronomy and Astrophysics (2018), 616(A), 11

Context. The second Gaia data release (Gaia DR2) contains high-precision positions, parallaxes, and proper motions for 1.3 billion sources as well as line-of-sight velocities for 7.2 million stars ... [more ▼]

Context. The second Gaia data release (Gaia DR2) contains high-precision positions, parallaxes, and proper motions for 1.3 billion sources as well as line-of-sight velocities for 7.2 million stars brighter than G[SUB]RVS[/SUB] = 12 mag. Both samples provide a full sky coverage. <BR /> Aims: To illustrate the potential of Gaia DR2, we provide a first look at the kinematics of the Milky Way disc, within a radius of several kiloparsecs around the Sun. <BR /> Methods: We benefit for the first time from a sample of 6.4 million F-G-K stars with full 6D phase-space coordinates, precise parallaxes (σ[SUB]ϖ[/SUB]/ϖ ≤ 20%), and precise Galactic cylindrical velocities (median uncertainties of 0.9-1.4 km s[SUP]-1[/SUP] and 20% of the stars with uncertainties smaller than 1 km s[SUP]-1[/SUP] on all three components). From this sample, we extracted a sub-sample of 3.2 million giant stars to map the velocity field of the Galactic disc from 5 kpc to 13 kpc from the Galactic centre and up to 2 kpc above and below the plane. We also study the distribution of 0.3 million solar neighbourhood stars (r < 200 pc), with median velocity uncertainties of 0.4 km s[SUP]-1[/SUP], in velocity space and use the full sample to examine how the over-densities evolve in more distant regions. <BR /> Results: Gaia DR2 allows us to draw 3D maps of the Galactocentric median velocities and velocity dispersions with unprecedented accuracy, precision, and spatial resolution. The maps show the complexity and richness of the velocity field of the galactic disc. We observe streaming motions in all the components of the velocities as well as patterns in the velocity dispersions. For example, we confirm the previously reported negative and positive galactocentric radial velocity gradients in the inner and outer disc, respectively. Here, we see them as part of a non-axisymmetric kinematic oscillation, and we map its azimuthal and vertical behaviour. We also witness a new global arrangement of stars in the velocity plane of the solar neighbourhood and in distant regions in which stars are organised in thin substructures with the shape of circular arches that are oriented approximately along the horizontal direction in the U - V plane. Moreover, in distant regions, we see variations in the velocity substructures more clearly than ever before, in particular, variations in the velocity of the Hercules stream. <BR /> Conclusions: Gaia DR2 provides the largest existing full 6D phase-space coordinates catalogue. It also vastly increases the number of available distances and transverse velocities with respect to Gaia DR1. Gaia DR2 offers a great wealth of information on the Milky Way and reveals clear non- axisymmetric kinematic signatures within the Galactic disc, for instance. It is now up to the astronomical community to explore its full potential. [less ▲]

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See detailGaia Data Release 2. Summary of the contents and survey properties
Gaia Collaboration; Brown, A. G. A.; Vallenari, A. et al

in Astronomy and Astrophysics (2018), 616(A1), 1-22

Context. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than ... [more ▼]

Context. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. <BR /> Aims: A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. <BR /> Methods: The raw data collected with the Gaia instruments during the first 22 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into this second data release, which represents a major advance with respect to Gaia DR1 in terms of completeness, performance, and richness of the data products. <BR /> Results: Gaia DR2 contains celestial positions and the apparent brightness in G for approximately 1.7 billion sources. For 1.3 billion of those sources, parallaxes and proper motions are in addition available. The sample of sources for which variability information is provided is expanded to 0.5 million stars. This data release contains four new elements: broad-band colour information in the form of the apparent brightness in the G[SUB]BP[/SUB] (330-680 nm) and G[SUB]RP[/SUB] (630-1050 nm) bands is available for 1.4 billion sources; median radial velocities for some 7 million sources are presented; for between 77 and 161 million sources estimates are provided of the stellar effective temperature, extinction, reddening, and radius and luminosity; and for a pre-selected list of 14 000 minor planets in the solar system epoch astrometry and photometry are presented. Finally, Gaia DR2 also represents a new materialisation of the celestial reference frame in the optical, the Gaia-CRF2, which is the first optical reference frame based solely on extragalactic sources. There are notable changes in the photometric system and the catalogue source list with respect to Gaia DR1, and we stress the need to consider the two data releases as independent. <BR /> Conclusions: Gaia DR2 represents a major achievement for the Gaia mission, delivering on the long standing promise to provide parallaxes and proper motions for over 1 billion stars, and representing a first step in the availability of complementary radial velocity and source astrophysical information for a sample of stars in the Gaia survey which covers a very substantial fraction of the volume of our galaxy. [less ▲]

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See detailGaia Data Release 2. Observations of solar system objects
Gaia Collaboration; Spoto, F.; Tanga, P. et al

in Astronomy and Astrophysics (2018), 616(A), 13

Context. The Gaia spacecraft of the European Space Agency (ESA) has been securing observations of solar system objects (SSOs) since the beginning of its operations. Data Release 2 (DR2) contains the ... [more ▼]

Context. The Gaia spacecraft of the European Space Agency (ESA) has been securing observations of solar system objects (SSOs) since the beginning of its operations. Data Release 2 (DR2) contains the observations of a selected sample of 14,099 SSOs. These asteroids have been already identified and have been numbered by the Minor Planet Center repository. Positions are provided for each Gaia observation at CCD level. As additional information, complementary to astrometry, the apparent brightness of SSOs in the unfiltered G band is also provided for selected observations. <BR /> Aims: We explain the processing of SSO data, and describe the criteria we used to select the sample published in Gaia DR2. We then explore the data set to assess its quality. <BR /> Methods: To exploit the main data product for the solar system in Gaia DR2, which is the epoch astrometry of asteroids, it is necessary to take into account the unusual properties of the uncertainty, as the position information is nearly one-dimensional. When this aspect is handled appropriately, an orbit fit can be obtained with post-fit residuals that are overall consistent with the a-priori error model that was used to define individual values of the astrometric uncertainty. The role of both random and systematic errors is described. The distribution of residuals allowed us to identify possible contaminants in the data set (such as stars). Photometry in the G band was compared to computed values from reference asteroid shapes and to the flux registered at the corresponding epochs by the red and blue photometers (RP and BP). <BR /> Results: The overall astrometric performance is close to the expectations, with an optimal range of brightness G 12 - 17. In this range, the typical transit-level accuracy is well below 1 mas. For fainter asteroids, the growing photon noise deteriorates the performance. Asteroids brighter than G 12 are affected by a lower performance of the processing of their signals. The dramatic improvement brought by Gaia DR2 astrometry of SSOs is demonstrated by comparisons to the archive data and by preliminary tests on the detection of subtle non-gravitational effects. [less ▲]

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See detailGaia Data Release 2. The celestial reference frame (Gaia-CRF2)
Gaia Collaboration; Mignard, F.; Klioner, S. A. et al

in Astronomy and Astrophysics (2018), 616(A), 14

Context. The second release of Gaia data (Gaia DR2) contains the astrometric parameters for more than half a million quasars. This set defines a kinematically non-rotating reference frame in the optical ... [more ▼]

Context. The second release of Gaia data (Gaia DR2) contains the astrometric parameters for more than half a million quasars. This set defines a kinematically non-rotating reference frame in the optical domain. A subset of these quasars have accurate VLBI positions that allow the axes of the reference frame to be aligned with the International Celestial Reference System (ICRF) radio frame. <BR /> Aims: We describe the astrometric and photometric properties of the quasars that were selected to represent the celestial reference frame of Gaia DR2 (Gaia-CRF2), and to compare the optical and radio positions for sources with accurate VLBI positions. <BR /> Methods: Descriptive statistics are used to characterise the overall properties of the quasar sample. Residual rotation and orientation errors and large-scale systematics are quantified by means of expansions in vector spherical harmonics. Positional differences are calculated relative to a prototype version of the forthcoming ICRF3. <BR /> Results: Gaia-CRF2 consists of the positions of a sample of 556 869 sources in Gaia DR2, obtained from a positional cross-match with the ICRF3-prototype and AllWISE AGN catalogues. The sample constitutes a clean, dense, and homogeneous set of extragalactic point sources in the magnitude range G ≃ 16 to 21 mag with accurately known optical positions. The median positional uncertainty is 0.12 mas for G < 18 mag and 0.5 mas at G = mag. Large- scale systematics are estimated to be in the range 20 to 30 μas. The accuracy claims are supported by the parallaxes and proper motions of the quasars in Gaia DR2. The optical positions for a subset of 2820 sources in common with the ICRF3-prototype show very good overall agreement with the radio positions, but several tens of sources have significantly discrepant positions. <BR /> Conclusions: Based on less than 40% of the data expected from the nominal Gaia mission, Gaia-CRF2 is the first realisation of a non-rotating global optical reference frame that meets the ICRS prescriptions, meaning that it is built only on extragalactic sources. Its accuracy matches the current radio frame of the ICRF, but the density of sources in all parts of the sky is much higher, except along the Galactic equator. [less ▲]

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See detailGaia Data Release 2. Observational Hertzsprung-Russell diagrams
Gaia Collaboration; Babusiaux, C.; van Leeuwen, F. et al

in Astronomy and Astrophysics (2018), 616(A), 10

Context. Gaia Data Release 2 provides high-precision astrometry and three-band photometry for about 1.3 billion sources over the full sky. The precision, accuracy, and homogeneity of both astrometry and ... [more ▼]

Context. Gaia Data Release 2 provides high-precision astrometry and three-band photometry for about 1.3 billion sources over the full sky. The precision, accuracy, and homogeneity of both astrometry and photometry are unprecedented. <BR /> Aims: We highlight the power of the Gaia DR2 in studying many fine structures of the Hertzsprung-Russell diagram (HRD). Gaia allows us to present many different HRDs, depending in particular on stellar population selections. We do not aim here for completeness in terms of types of stars or stellar evolutionary aspects. Instead, we have chosen several illustrative examples. <BR /> Methods: We describe some of the selections that can be made in Gaia DR2 to highlight the main structures of the Gaia HRDs. We select both field and cluster (open and globular) stars, compare the observations with previous classifications and with stellar evolutionary tracks, and we present variations of the Gaia HRD with age, metallicity, and kinematics. Late stages of stellar evolution such as hot subdwarfs, post-AGB stars, planetary nebulae, and white dwarfs are also analysed, as well as low-mass brown dwarf objects. <BR /> Results: The Gaia HRDs are unprecedented in both precision and coverage of the various Milky Way stellar populations and stellar evolutionary phases. Many fine structures of the HRDs are presented. The clear split of the white dwarf sequence into hydrogen and helium white dwarfs is presented for the first time in an HRD. The relation between kinematics and the HRD is nicely illustrated. Two different populations in a classical kinematic selection of the halo are unambiguously identified in the HRD. Membership and mean parameters for a selected list of open clusters are provided. They allow drawing very detailed cluster sequences, highlighting fine structures, and providing extremely precise empirical isochrones that will lead to more insight in stellar physics. <BR /> Conclusions: Gaia DR2 demonstrates the potential of combining precise astrometry and photometry for large samples for studies in stellar evolution and stellar population and opens an entire new area for HRD- based studies. The full Table A.1 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://cdsarc.u-strasbg.fr">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/616/A10">http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/616/A10</A> [less ▲]

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See detailGaia Data Release 2. Kinematics of globular clusters and dwarf galaxies around the Milky Way
Gaia Collaboration; Helmi, A.; van Leeuwen, F. et al

in Astronomy and Astrophysics (2018), 616(A), 12

Context. <BR /> Aims: The goal of this paper is to demonstrate the outstanding quality of the second data release of the Gaia mission and its power for constraining many different aspects of the dynamics ... [more ▼]

Context. <BR /> Aims: The goal of this paper is to demonstrate the outstanding quality of the second data release of the Gaia mission and its power for constraining many different aspects of the dynamics of the satellites of the Milky Way. We focus here on determining the proper motions of 75 Galactic globular clusters, nine dwarf spheroidal galaxies, one ultra-faint system, and the Large and Small Magellanic Clouds. <BR /> Methods: Using data extracted from the Gaia archive, we derived the proper motions and parallaxes for these systems, as well as their uncertainties. We demonstrate that the errors, statistical and systematic, are relatively well understood. We integrated the orbits of these objects in three different Galactic potentials, and characterised their properties. We present the derived proper motions, space velocities, and characteristic orbital parameters in various tables to facilitate their use by the astronomical community. <BR /> Results: Our limited and straightforward analyses have allowed us for example to (i) determine absolute and very precise proper motions for globular clusters; (ii) detect clear rotation signatures in the proper motions of at least five globular clusters; (iii) show that the satellites of the Milky Way are all on high-inclination orbits, but that they do not share a single plane of motion; (iv) derive a lower limit for the mass of the Milky Way of 9.1[SUB]-2.6[/SUB][SUP]+6.2[/SUP] × 10[SUP]11[/SUP] M[SUB]☉[/SUB] based on the assumption that the Leo I dwarf spheroidal is bound; (v) derive a rotation curve for the Large Magellanic Cloud based solely on proper motions that is competitive with line-of-sight velocity curves, now using many orders of magnitude more sources; and (vi) unveil the dynamical effect of the bar on the motions of stars in the Large Magellanic Cloud. <BR /> Conclusions: All these results highlight the incredible power of the Gaia astrometric mission, and in particular of its second data release. Full Table D.3 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://cdsarc.u-strasbg.fr">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/616/A12">http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/616/A12</A> [less ▲]

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See detailRoles of heating and helicity in ultrafast all-optical magnetization switching in TbFeCo
Lu, X; Zou, X; Hinzke, D et al

in Applied Physics Letters (2018), 113

Using the time-resolved magneto-optical Kerr effect method, helicity-dependent all-optical magnetization switching (HD-AOS) is observed in ferrimagnetic TbFeCo films. Our results reveal the individual ... [more ▼]

Using the time-resolved magneto-optical Kerr effect method, helicity-dependent all-optical magnetization switching (HD-AOS) is observed in ferrimagnetic TbFeCo films. Our results reveal the individual roles of the thermal and nonthermal effects after a single circularly polarized laser pulse. The evolution of this ultrafast switching occurs over different time scales, and a defined magnetization reversal time of 460 fs is shown—the fastest ever observed. Micromagnetic simulations based on a single macro-spin model, taking into account both heating and the inverse Faraday effect, are performed which reproduce HD-AOS demonstrating a linear path for magnetization reversal. Published [less ▲]

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See detailThe THESEUS space mission concept: science case, design and expected performances
Amati, L.; O'Brien, P.; Götz, D. et al

in Advances in Space Research (2018), 62

THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics ... [more ▼]

THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1sr) with 0.5-1 arcmin localization, an energy band extending from several MeV down to 0.3 keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7 m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing the main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift ∼ 10, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, it will provide unprecedented capability to monitor the X-ray variable sky, thus detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which may be routinely detected in the late '20s/early '30s by next generation facilities like aLIGO/ aVirgo, eLISA, KAGRA, and Einstein Telescope. THESEUS will also provide powerful synergies with the next generation of multi-wavelength observatories (e.g., LSST, ELT, SKA, CTA, ATHENA). [less ▲]

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See detailDynamic inter-regional coordination patterns as specific predictors of consciousness
Demertzi, Athina ULiege; Tagliazucchi, Enzo; Dehaene, Stanislas et al

Poster (2018, June 17)

Background and aims: To date, specific signatures of conscious states in humans remain elusive. Contemporary theories concur that such markers can be traced to temporally evolving brain processes instead ... [more ▼]

Background and aims: To date, specific signatures of conscious states in humans remain elusive. Contemporary theories concur that such markers can be traced to temporally evolving brain processes instead of static descriptions of brain activity. Methods: Dynamic fMRI connectivity patterns (states) by means of clustering of phase-based coherence was estimated on 47 healthy and 112 patients diagnosed in vegetative state/unresponsive wakefulness syndrome (VS/UWS) or in a minimally conscious state (MCS). To validate whether the patterns captured properties of awareness, out-of-sample generalization was performed on patients with cognitive-motor dissociation (i.e. lacking overt conscious behaviour yet evidenced using functional neuroimaging), and on anesthetised patients, under the premise that complex signatures would disappear uniformly across all subjects. Results: A pattern of long-range positive/negative coherence had a higher probability of occurring in healthy and MCS patients. A pattern of low inter-areal coordination, mostly similar to anatomy, was more likely to occur in VS/UWS. Inter-state transitioning was flexible for healthy and MCS and more rigid for VS/UWS patients. Unconscious patients were more likely to avoid the exploration of the complex connectivity state. The generalization to cognitive-motor dissociation predicted the occurrence of the complexconnectivity state. The generalization to propofol anaesthesia showed an equalization of occurrence probabilities of all patterns regardless of clinical diagnosis. Conclusion: The dynamics of inter-areal coordination contain information specific to conscious awareness. The rigid and less metastable dynamics in VS/UWS could account for the limited mental capacities in these patients. The minute identification of these patterns and their external manipulation could account for non-invasive restoration of consciousness. [less ▲]

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See detailARGOS at the LBT. Binocular laser guided ground layer adaptive optics
Rabien, S.; Angel, R.; Barl, L. et al

E-print/Working paper (2018)

Having completed its commissioning phase, the ARGOS ground layer adaptive optics facility is coming online for scientific observations at the Large Binocular Telescope, LBT. With six Rayleigh laser guide ... [more ▼]

Having completed its commissioning phase, the ARGOS ground layer adaptive optics facility is coming online for scientific observations at the Large Binocular Telescope, LBT. With six Rayleigh laser guide stars in two constellations and the corresponding wavefront sensing, ARGOS corrects the ground layer distortions for both LBT 8.4 m eyes with its adaptive secondary mirrors. Under regular observing conditions, this setup delivers a PSF size reduction by a factor ~2-3, compared to a seeing limited operation. With the two LUCI infrared imaging and MOS spectroscopy instruments receiving the corrected images, observations in the near infrared can be performed at high spatial and spectral resolution. We will discuss the final ARGOS technical setup and the adaptive optics performances. With first scientific observations being conducted, we will show that imaging cases with GLAO are boosting several science programs from cluster CMD, Milky Way embedded star formation, to nuclei of nearby galaxies or extragalactic deep fields. In the unique combination of ARGOS with the multi-object near infrared spectroscopy available in LUCI over 4x4 arcmin field of view, first scientific observations have been performed on local and high-z objects. Those high spatial and spectral resolution observations demonstrate the capabilities now at hand with ARGOS at the LBT. [less ▲]

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See detailGLUCOSEPANE : A NEW BIOMARKER OF THE SEVERITY OF OSTEOARTHRITIS
Rabbani, N; Ahmed, U; Lambert, Cécile ULiege et al

in Annals of the Rheumatic Diseases (2018, June), 77(supplement 2), 181

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See detailGlycation marker glucosepane increases with the progression of osteoarthritis and correlates with morphological and functional changes of cartilage in vivo
Legrand, Catherine; Ahmed, U.; Anwar, A. et al

in Arthritis Research and Therapy (2018), 20(1), 131

Background: Changes of serum concentrations of glycated, oxidized, and nitrated amino acids and hydroxyproline and anticyclic citrullinated peptide antibody status combined by machine learning techniques ... [more ▼]

Background: Changes of serum concentrations of glycated, oxidized, and nitrated amino acids and hydroxyproline and anticyclic citrullinated peptide antibody status combined by machine learning techniques in algorithms have recently been found to provide improved diagnosis and typing of early-stage arthritis of the knee, including osteoarthritis (OA), in patients. The association of glycated, oxidized, and nitrated amino acids released from the joint with development and progression of knee OA is unknown. We studied this in an OA animal model as well as interleukin-1β-activated human chondrocytes in vitro and translated key findings to patients with OA. Methods: Sixty male 3-week-old Dunkin-Hartley guinea pigs were studied. Separate groups of 12 animals were killed at age 4, 12, 20, 28 and 36 weeks, and histological severity of knee OA was evaluated, and cartilage rheological properties were assessed. Human chondrocytes cultured in multilayers were treated for 10 days with interleukin-1β. Human patients with early and advanced OA and healthy controls were recruited, blood samples were collected, and serum or plasma was prepared. Serum, plasma, and culture medium were analyzed for glycated, oxidized, and nitrated amino acids. Results: Severity of OA increased progressively in guinea pigs with age. Glycated, oxidized, and nitrated amino acids were increased markedly at week 36, with glucosepane and dityrosine increasing progressively from weeks 20 and 28, respectively. Glucosepane correlated positively with OA histological severity (r = 0.58, p < 0.0001) and instantaneous modulus (r = 0.52-0.56; p < 0.0001), oxidation free adducts correlated positively with OA severity (p < 0.0009-0.0062), and hydroxyproline correlated positively with cartilage thickness (p < 0.0003-0.003). Interleukin-1β increased the release of glycated and nitrated amino acids from chondrocytes in vitro. In clinical translation, plasma glucosepane was increased 38% in early-stage OA (p < 0.05) and sixfold in patients with advanced OA (p < 0.001) compared with healthy controls. Conclusions: These studies further advance the prospective role of glycated, oxidized, and nitrated amino acids as serum biomarkers in diagnostic algorithms for early-stage detection of OA and other arthritic disease. Plasma glucosepane, reported here for the first time to our knowledge, may improve early-stage diagnosis and progression of clinical OA. © 2018 The Author(s). [less ▲]

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See detailHuman brain patterns underlying vigilant attention: impact of sleep debt, circadian phase and attentional engagement
Maire, Micheline; Reichert, Carolin Franziska; Gabel, Virginie et al

in Scientific Reports (2018), 8(1), 970

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See detailThe Ionospheric Connection Explorer Mission: Mission Goals and Design
Immel, T. J.; England, S. L.; Mende, S. B. et al

in Space Science Reviews (2018), 214(13),

The Ionospheric Connection Explorer, or ICON, is a new NASA Explorer mission that will explore the boundary between Earth and space to understand the physical connection between our world and our space ... [more ▼]

The Ionospheric Connection Explorer, or ICON, is a new NASA Explorer mission that will explore the boundary between Earth and space to understand the physical connection between our world and our space environment. This connection is made in the ionosphere, which has long been known to exhibit variability associated with the sun and solar wind. However, it has been recognized in the 21st century that equally significant changes in ionospheric conditions are apparently associated with energy and momentum propagating upward from our own atmosphere. ICON's goal is to weigh the competing impacts of these two drivers as they influence our space environment. Here we describe the specific science objectives that address this goal, as well as the means by which they will be achieved. The instruments selected, the overall performance requirements of the science payload and the operational requirements are also described. ICON's development began in 2013 and the mission is on track for launch in 2018. ICON is developed and managed by the Space Sciences Laboratory at the University of California, Berkeley, with key contributions from several partner institutions. [less ▲]

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See detailNew Minerals, Nomenclature and Classification (CNMNC), Newsletter 41. New minerals and nomenclature modifications approved in 2017 and 2018.
Halenius, U; Hatert, Frédéric ULiege; Pasero, M et al

in European Journal of Mineralogy (2018), 30

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