2025
Autores
Winterhalder, TO; Kammerer, J; Lacour, S; Mérand, A; Nowak, M; Stolker, T; Balmer, WO; Marleau, GD; Abuter, R; Amorim, A; Asensio-Torres, R; Berger, JP; Beust, H; Blunt, S; Bonnefoy, M; Bonnet, H; Bordoni, MS; Bourdarot, G; Brandner, W; Cantalloube, F; Caselli, P; Charnay, B; Chauvin, G; Chavez, A; Choquet, E; Christiaens, V; Clénet, Y; du Foresto, VC; Cridland, A; Davies, R; Dembet, R; Dexter, J; Drescher, A; Duvert, G; Eckart, A; Eisenhauer, F; Schreiber, NMF; Garcia, P; Lopez, RG; Gardner, T; Gendron, E; Genzel, R; Gillessen, S; Girard, JH; Grant, S; Haubois, X; el, GH; Henning, T; Hinkley, S; Hippler, S; Houlle, M; Hubert, Z; Jocou, L; Keppler, M; Kervella, P; Kreidberg, L; Kurtovic, NT; Lagrange, AM; Lapeyrere, V; Le Bouquin, JB; Lutz, D; Maire, AL; Mang, F; Molliere, P; Mordasi, C; Mouillet, D; Nasedkin, E; Ott, T; Otten, GPPL; Paladini, C; Paumard, T; Perraut, K; Perrin, G; Pourre, N; Pueyo, L; Ribeiro, D; Rickman, E; Rustamkulov, Z; Shangguan, J; Shimizu, T; Sing, D; Stadler, J; Straub, O; Straubmeier, C; Sturm, E; Tacconi, LJ; van Dishoeck, EF; Vigan, A; Vincent, F; von Fellenberg, SD; Wang, JJ; Widmann, F; Woillez, J; Yazici, S; GRAVITY Collaboration;
Publicação
ASTRONOMY & ASTROPHYSICS
Abstract
Context. Inferring the likely formation channel of giant exoplanets and brown dwarf companions from orbital and atmospheric observables remains a formidable challenge. Further and more precise directly measured dynamical masses of these companions are required to inform and gauge formation, evolutionary, and atmospheric models. We present an updated study of the recently discovered companion to HIP 99770 based on observations conducted with the near-infrared interferometer VLTI/GRAVITY.Aims. Through renewed orbital and spectral analyses based on the GRAVITY data, we characterise HIP 99770 b to better constrain its orbit, dynamical mass, and atmospheric properties, as well as to shed light on its likely formation channel.Methods. Upon inclusion of the new high-precision astrometry epoch, we ran an orbit fit to further constrain the dynamical mass of the companion and the orbit solution. We also analysed the GRAVITY K-band spectrum, placing it into context with literature data, and extracting magnitude, age, spectral type, bulk properties and atmospheric characteristics of HIP 99770 b.Results. We detected the companion at a radial separation of 417 mas from its host. The new orbit fit yields a dynamical mass of 17-5+6 MJup and an eccentricity of 0.31-0.12+0.06. We also find that additional relative astrometry epochs in the future will not enable further constraints on the dynamical mass due to the dominating relative uncertainty on the Hipparcos-Gaia proper motion anomaly that is used in the orbit-fitting routine. The publication of Gaia DR4 will likely ease this predicament. Based on the spectral analysis, we find that the companion is consistent with spectral type L8 and exhibits a potential metal enrichment in its atmosphere. Adopting the AMES-DUSTY model to infer its age, within its dynamical mass constraint the companion conceivably corresponds to either a younger (28-14+15 Myr) object with a mass just below the deuterium-burning limit or an older (119-10+37 Myr) body with a mass just above the deuterium-burning limit.Conclusions. These results do not yet allow for a definite inference of the companion's formation channel. Nevertheless, the new constraints on its bulk properties and the additional GRAVITY spectrum presented here will aid future efforts to determine the formation history of HIP 99770 b.
2025
Autores
Kumar, R; Moreira, JM; Chandra, J;
Publicação
DATA MINING AND KNOWLEDGE DISCOVERY
Abstract
Intelligent Transportation Systems aim to alleviate traffic congestion and enhance urban traffic management. Transformer-based methods have shown promise in traffic prediction due to their capability to handle long-range dependencies. However, they disregard local context during parallel processing and can be computationally expensive for large traffic networks. On the other hand, they miss the hierarchical information hidden in regions of large traffic networks. To address these issues, we introduce CSCN, a novel framework that clusters traffic sensors based on data similarity, employs clustered multi-head self-attention for efficient hierarchical pattern learning, and utilizes causal convolutional attention for capturing local temporal trends. In addition to these advancements, we integrate snapshot ensemble learning into CSCN, allowing for the exploitation of diverse snapshots obtained during training to enrich predictive performance. Evaluations of real-world data highlight CSCN's superiority in traffic flow prediction, showcasing its potential for enhancing transportation systems with improved accuracy and efficiency.
2025
Autores
Campos, R; Jorge, A; Jatowt, A; Bhatia, S; Litvak, M;
Publicação
ECIR (5)
Abstract
For seven years, the Text2Story Workshop series has fostered a vibrant community dedicated to understanding narrative structure in text, resulting in significant contributions to the field and developing a shared understanding of the challenges in this domain. While traditional methods have yielded valuable insights, the advent of Transformers and LLMs have ignited a new wave of interest in narrative understanding. The previous iteration of the workshop also witnessed a surge in LLM-based approaches, demonstrating the community’s growing recognition of their potential. In this eighth edition we propose to go deeper into the role of LLMs in narrative understanding. While LLMs have revolutionized the field of NLP and are the go-to tools for any NLP task, the ability to capture, represent and analyze contextual nuances in longer texts is still an elusive goal, let alone the understanding of consistent fine-grained narrative structures in text. Consequently, this iteration of the workshop will explore the issues involved in using LLMs to unravel narrative structures, while also examining the characteristics of narratives generated by LLMs. By fostering dialogue on these emerging areas, we aim to continue the workshop's tradition of driving innovation in narrative understanding research. Text2Story encompasses sessions covering full research papers, work-in-progress, demos, resources, position and dissemination papers, along with one keynote talk.
2025
Autores
de Matos, MA; Patrício, L; Teixeira, JG;
Publicação
JOURNAL OF SERVICE THEORY AND PRACTICE
Abstract
Purpose Citizen engagement plays a crucial role in transitioning to sustainable service ecosystems. While customer engagement has been extensively studied in service research, citizen engagement has received significantly less attention. By synthesizing customer and citizen engagement literatures, this study develops an integrated framework to conceptually clarify the dual role of customer-citizen engagement for sustainability. Design/methodology/approach This study builds on a systematic literature review of customer engagement literature in service research and citizen engagement literature. Following a theory synthesis approach, we qualitatively analyzed 126 articles to develop an integrated conceptual framework of customer-citizen engagement for sustainability through a process of abductive reasoning. Findings The analysis showed that customer engagement and citizen engagement literatures have developed mostly separately but provide complementary views. While the customer engagement literature has traditionally focused on business-related facets, such as engagement with brands, the citizen perspective broadens the engagement scope to other citizens, communities and society in general. The integrated framework highlights the interplay between citizen and customer roles and the impact of their relationships with multiple objects on sustainability. Originality/value This integrated framework contributes to advancing our understanding of customer-citizen engagement, broadening the scope of subject-object engagement by examining the interplay between these roles in how they engage for sustainability and moving beyond the traditional dyadic perspective to a multi-level perspective of service ecosystems. This framework also enables the development of a set of research directions to advance the understanding of engagement in sustainable service ecosystems.
2025
Autores
Figueiredo, A;
Publicação
Springer Proceedings in Mathematics and Statistics
Abstract
We propose an approach to cluster and classify compositional data. We transform the compositional data into directional data using the square root transformation. To cluster the compositional data, we apply the identification of a mixture of Watson distributions on the hypersphere and to classify the compositional data into predefined groups, we apply Bayes rules based on the Watson distribution to the directional data. We then compare our clustering results with those obtained in hierarchical clustering and in the K-means clustering using the log-ratio transformations of the data and compare our classification results with those obtained in linear discriminant analysis using log-ratio transformations of the data. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.
2025
Autores
Stolker, T; Samland, M; Waters, LBFM; van den Ancker, ME; Balmer, WO; Lacour, S; Sitko, ML; Wang, JJ; Nowak, M; Maire, AL; Kammerer, J; Otten, GPPL; Abuter, R; Amorim, A; Benisty, M; Berger, JP; Beust, H; Blunt, S; Boccaletti, A; Bonnefoy, M; Bonnet, H; Bordoni, MS; Bourdarot, G; Brandner, W; Cantalloube, F; Caselli, P; Charnay, B; Chauvin, G; Chavez, A; Chomez, A; Choquet, E; Christiaens, V; Clénet, Y; du Foresto, VC; Cridland, A; Davies, R; Dembet, R; Dexter, J; Dominik, C; Drescher, A; Duvert, G; Eckart, A; Eisenhauer, F; Schreiber, NMF; Garcia, P; Lopez, RG; Gardner, T; Gendron, E; Genzel, R; Gillessen, S; Girard, JH; Grant, S; Haubois, X; Heissel, G; Henning, T; Hinkley, S; Hippler, S; Houllé, M; Hubert, Z; Jocou, L; Keppler, M; Kervella, P; Kreidberg, L; Kurtovic, NT; Lagrange, AM; Lapeyrère, V; Le Bouquin, JB; Lutz, D; Mang, F; Marleau, GD; Merand, A; Min, M; Mollière, P; Monnier, JD; Mordasini, C; Mouillet, D; Nasedkin, E; Ott, T; Paladini, C; Paumard, T; Perraut, K; Perrin, G; Pfuhl, O; Pourré, N; Pueyo, L; Quanz, SP; Ribeiro, DC; Rickman, E; Rustamkulov, Z; Shangguan, J; Shimizu, T; Sing, D; Stadler, J; Straub, O; Straubmeier, C; Sturm, E; Tacconi, LJ; van Dishoeck, EF; Vigan, A; Vincent, F; von Fellenberg, SD; Widmann, F; Winterhalder, TO; Woillez, J; Yazici, S;
Publicação
ASTRONOMY & ASTROPHYSICS
Abstract
Context. HD135344AB is a young visual binary system that is best known for the protoplanetary disk around the secondary star. The circumstellar environment of the A0-type primary star, on the other hand, is already depleted. HD135344A is therefore an ideal target for the exploration of recently formed giant planets because it is not obscured by dust. Aims. We searched for and characterized substellar companions to HD135344A down to separations of about 10 au. Methods. We observed HD135344A with VLT/SPHERE in the H23 and K12 bands and obtained YJ and YJH spectroscopy. In addition, we carried out VLTI/GRAVITY observations for the further astrometric and spectroscopic confirmation of a detected companion. Results. We discovered a close-in young giant planet, HD135344Ab, with a mass of about 10 M-J. The multi-epoch astrometry confirms the bound nature based on common parallax and common proper motion. This firmly rules out the scenario of a non-stationary background star. The semi-major axis of the planetary orbit is approximately 15-20 au, and the photometry is consistent with that of a mid L-type object. The inferred atmospheric and bulk parameters further confirm the young and planetary nature of the companion. Conclusions. HD135344Ab is one of the youngest directly imaged planets that has fully formed and orbits on Solar System scales. It is a valuable target for studying the early evolution and atmosphere of a giant planet that could have formed in the vicinity of the snowline.
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