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Publications

2026

The ExoGRAVITY survey: A K-band spectral library of giant exoplanet and brown dwarf companions

Authors
Kammerer,, J; Winterhalder,, TO; Lacour,, S; Stolker,, T; Marleau,, GD; Balmer,, WO; Moore,, AF; Piscarreta,, L; Toci,, C; Mérand,, A; Nowak,, M; Rickman,, EL; Pueyo,, L; Pourre,, N; Nasedkin,, E; Wang,, JJ; Bourdarot,, G; Eisenhauer,, F; Henning,, T; García López,, R; van Dishoeck,, EF; Forveille,, T; Monnier,, JD; Abuter,, R; Amorim,, A; Benisty,, M; Berger,, JP; Beust,, H; Blunt,, S; Boccaletti,, A; Bonnefoy,, M; Bonnet,, H; Sadun Bordoni,, MS; Brandner,, W; Cantalloube,, F; Caselli,, P; Ceva,, W; Charnay,, B; Chauvin,, G; Chavez,, A; Chomez,, A; Choquet,, E; Christiaens,, V; Clénet,, Y; Du Foresto,, V; Cridland,, A; Davies,, R; Dembet,, R; Dexter,, J; Drescher,, A; Duvert,, G; Eckart,, A; Fontanive,, C; Förster Schreiber,, NM; Garcia,, P; Gendron,, E; Genzel,, R; Gillessen,, S; Girard,, JH; Grant,, S; Hagelberg,, J; Haubois,, X; , G; Hinkley,, S; Hippler,, S; Houlle,, M; Hubert,, Z; Jocou,, L; Keppler,, M; Kervella,, P; Kreidberg,, L; Kurtovic,, NT; Lagrange,, AM; Lapeyrère,, V; Le Bouquin,, JB; Lutz,, D; Maire,, AL; Mang,, F; Matthews,, EC; Mollière,, P; Mordasini,, C; Mouillet,, D; Ott,, T; Otten,, GPPL; Paladini,, C; Paumard,, T; Rousselet Perraut,, K; Perrin,, G; Pfuhl,, O; Ribeiro,, DC; Rustamkulov,, Z; Ségransan,, D; Shangguan,, J; Shimizu,, T; Samland,, M; Sing,, D; Stadler,, J; Straub,, O; Straubmeier,, C; Sturm,, E;

Publication
ASTRONOMY & ASTROPHYSICS

Abstract
Context. Direct observations of exoplanet and brown dwarf companions with near-infrared interferometry, first enabled by the dualfield mode of VLTI/GRAVITY, provide unique measurements of the objects' orbital motions and atmospheric compositions. Aims. Here we compile a homogeneous library of all exoplanet and brown dwarf K-band spectra observed by GRAVITY thus far. This ExoGRAVITY Spectral Library is made publicly available online. Methods. We re-reduced all the available GRAVITY dual-field high-contrast data in a uniform and highly automated way and, where companions were detected, extracted their similar to 2.0-2.4 mu m K-band contrast spectra. We then derived stellar model atmospheres for all the employed flux references (either the host star or the swap calibrator), which we used to convert the companion contrast into companion flux spectra. Solely from the resulting GRAVITY K-band flux spectra, we extracted spectral types, spectral indices, and bulk physical properties for all the companions. Finally, and with the help of age constraints from the literature, we also derived isochronal masses for most of the companions using evolutionary models. Results. The resulting library contains R similar to 500 GRAVITY K-band spectra of 39 substellar companions from late M to late T spectral types, including the entire L-T transition. Throughout this transition, a shift from CO-dominated late M- and L-type dwarfs to CH4-dominated T-type dwarfs can be observed in the K-band. The GRAVITY spectra alone constrain the objects' bolometric luminosity to typically within +/- 0.15 dex. The derived isochronal masses agree with dynamical masses from the literature where available, except for HD 4113 c for which we confirm its previously reported potential underluminosity. Conclusions. Medium-resolution spectroscopy of substellar companions with GRAVITY provides insight into the carbon chemistry and the cloudiness of these objects' atmospheres. It also constrains these objects' bolometric luminosities, which can yield measurements of their formation entropy if combined with dynamical masses, for instance from Gaia and GRAVITY astrometry.

2026

Explainable Artificial Intelligence in Rehabilitation Nursing: A Sociotechnical Framework for Human-Centered Clinical Decision Support

Authors
Ramos, FP; Santos, A; Rocha, T; Petronilho, F; Pereira, R;

Publication
SYSTEMS

Abstract
Healthcare systems are complex adaptive environments in which clinical work, digital technologies, and organizational routines interact continuously, often challenging the integration of artificial intelligence (AI) into everyday practice. Although explainable AI (xAI) has been proposed to address concerns related to algorithmic opacity and professional trust, explainability is still frequently approached. Grounded in General Systems Theory, sociotechnical systems theory, and complexity science, this study conceptualizes explainability as an emergent system-level property of healthcare systems. Using Design Science Research as a systems-oriented inquiry methodology, a human-centered conceptual framework for AI-supported clinical decision-making was developed through iterative cycles of problem framing, design, demonstration, and evaluation. The framework was explored in rehabilitation nursing, a domain characterized by multidimensional patient data, longitudinal decision processes, and close professional-patient interaction. Iterative engagement with Rehabilitation Nursing Specialists informed design principles related to user participation, contextualized explanations, and workflow alignment. An exploratory evaluation with 144 Specialists assessed perceived usefulness, comprehensibility of explanations, and acceptance of AI-supported recommendations in realistic scenarios. The findings indicate that explainability is experienced not as a property of the algorithm alone, but as an outcome emerging from interactions between AI behavior, human interpretation, and organizational context. The framework shows potential to meaningfully support clinical decision-making in Rehabilitation Nursing by providing contextually aligned, human-centered explanatory outputs.

2026

Mimic Grasping: A Modular and Flexible Programming-by-Demonstration Robotic Grasping Solution

Authors
de Souza, JPC; Rocha, LF; Moreira, AP; Boaventura Cunha, J;

Publication
JOURNAL OF FIELD ROBOTICS

Abstract
The Industry 5.0 concept guides the industry to the premise of sustainability, resilience and human-centric solutions. The last related pillar tries to create solutions to empower the people in production line processes since solutions should be designed to be easy to use and easy to learn without discarding the working people. In this regard, it's natural that robots become closer to humans in industrial applications where it is possible to absorb human-machine qualities. Robotic grasping has widespread application with a wide range of applicability. However, engineers and shop-floor operators spend time finding a fast response solution when the production demand changes. Aiming to create a tool to help this procedure in a human-centred fashion, the current paper proposes a programming-by-demonstration solution that is easy to use, reuse, adapt, and increment with its modular design.

2026

Sagittarius A* near-infrared flare polarization as a probe of space-time I. Nonrotating exotic compact objects

Authors
Aimar, N; Rosa, JL; Tamm, HL; Garcia, P;

Publication
ASTRONOMY & ASTROPHYSICS

Abstract
Context. The center of our Galaxy hosts Sagittarius A*, which is a supermassive compact object of similar to 4.3 & times; 10(6) solar masses and is usually associated with a black hole. Nevertheless, black holes possess a central singularity that is considered unphysical, and an event horizon that leads to loss of unitarity in a quantum description of the system. To address these theoretical inconsistencies, alternative models, collectively known as exotic compact objects, have been proposed. Aims. We investigate the potential detectability of signatures associated with nonrotating exotic compact objects (ECOs) within the dataset of Sgr A* polarized flares as observed through GRAVITY and the upcoming GRAVITY+. Methods. We examined a total of eight distinct metrics that originate from four different categories of static and spherically symmetric compact objects: black holes, boson stars, fluid spheres, and gravastars. Our approach involved using a toy model that orbits the compact object in the equatorial plane at the Schwarzschild-Keplerian velocity. Using simulated astrometric and polarimetric data with current GRAVITY uncertainties as well as improved flux uncertainties expected for the GRAVITY+ upgrade, we fit the datasets across all metrics we examined. We evaluated the detectability of the metric for each dataset based on the resulting chi(2)(red) and Bayesian information criteria-based Bayes factors. Results. Plunge-through images of ECOs affect polarization and astrometry in a distinguishable way from the spin of a Kerr black hole. With GRAVITY's current uncertainties, none of the metrics models are discernible. However, when the data are modeled within a compact boson star background, the corresponding best fit is sufficiently superior to the Kerr fit to rule out the latter. We examined the best expected enhanced flux uncertainties and discovered that a fourfold increase in flux sensitivity enables the detection of some of the exotic compact object models we investigated. The signals of the others are too close to each other to be distinguishable. However, with the GRAVITY+ flux uncertainties, when the data are produced using an ECO model, the best-fit ECO model is significantly preferred (with a BIC-based Bayes factor exceeding two) over the best fit in the Kerr metric, such that the latter can be ruled out. Nevertheless, enhancing the astrophysical complexity of the hot-spot model might diminishes these outcomes. Conclusions. With the improved sensitivity of GRAVITY+, we expect to be able to determine whether Sgr A* is a Kerr black hole or some form of exotic compact object, although we will not be able to identify the specific ECO models that describe Sgr A* best.

2026

Direct Spectroscopic Confirmation of the Young Embedded Protoplanet WISPIT 2c

Authors
Lawlor, C; van Capelleveen, F; Bourdarot, G; Ginski, C; Kenworthy, A; Stolker, T; Close, L; Bohn, J; Eisenhauer, F; Garcia, P; Hönig, F; Kammerer, J; Kreidberg, L; Lacour, S; Le Bouquin, J; Mamajek, E; Nowak, M; Paumard, T; Straubmeier, C; van der Marel, N;

Publication
ASTROPHYSICAL JOURNAL LETTERS

Abstract
WISPIT 2 is a nearby young star with a multiringed disk that was recently confirmed to host a similar to 4.9 MJup gas giant planet embedded in a large (60 au) gap at a radial separation of 57 au from the host star. We confirm and characterize a second, close-in planet in the WISPIT 2 system using a combination of new Very Large Telescope/SPHERE H-band dual-polarization imaging and VLTI/GRAVITY K-band interferometric observations of the WISPIT 2 system. The GRAVITY detection is consistent with a point-like source while its extracted K-band spectrum shows CO band-head absorption at 2.3 mu m and a continuum shape consistent with a young giant planet. From the GRAVITY data, we extract a medium resolution K-band spectrum of the companion and fit atmospheric model grids using the species tool with nested sampling to constrain its effective temperature, radius, and luminosity. We infer Teff of 1500-2600 K, a radius of 0.91-2.2 RJup, and a luminosity of (-3.47)-(-3.63). Comparison with evolutionary tracks implies a mass range of 8-12 MJup, approximately twice as massive as the previously confirmed WISPIT 2b. The astrometry rules out a background source and marginally detects orbital motion of WISPIT 2 c, which needs further follow-up observations for confirmation. WISPIT 2 now becomes an analog to PDS 70, offering a second laboratory for studying the formation and early evolution of a multiplanet system within its natal disk.

2026

A Human-Centered Study of an Upper-Limb Rehabilitation Exoskeleton with Healthy Participants

Authors
Gonçalves, A; Dias, N; Mendonça, H; Silva, MF; Rocha, CD;

Publication
APPLIED SCIENCES-BASEL

Abstract
Upper-limb impairments affect a substantial portion of the global population, often limiting the ability to perform daily activities. Robotic rehabilitation systems offer a promising solution by enabling high-dose, task-oriented therapy with consistent and objective feedback. However, user acceptance and perceived comfort are critical for their successful adoption. This work presents a feasibility, performance, and comfort evaluation of a 2-degree-of-freedom upper-limb rehabilitation exoskeleton capable of performing elbow flexion/extension and forearm pronation/supination. A total of 47 healthy participants were enrolled and tested across three rehabilitation modalities: passive assist, active assist, and active resist. Passive assist enabled full range-of-motion execution, active assist supported movement, and active resist provided variable resistance via a sliding bar (0-100%). Objective performance metrics, including position, current, and temperature, were recorded and analyzed, revealing trajectory-tracking errors during passive assistance of 4.82 degrees +/- 0.02 degrees for forearm movement and 1.20 degrees +/- 0.04 degrees for elbow movement, with actuator temperatures remaining below their rated limits throughout the study. The active assist mode did not achieve a true assist-as-needed performance, indicating a need for further refinement. Subjective evaluation included the System Usability Scale, yielding a score of 87.1 +/- 9.6, indicating excellent usability, and a safety and comfort assessment averaging 4.4 +/- 0.4 out of 5. Perceived effort was assessed using the Borg CR-10 scale and generally scaled appropriately across modalities, although some variability suggests the need for further investigation. Qualitative feedback identified areas for improvement, particularly in ergonomics and control behavior. Overall, the results support the feasibility, usability, and safe operation of the proposed exoskeleton and provide insights for future device refinement and evaluation with target user populations.

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