51,141 results on '"Luis, F."'
Search Results
2. On the Regge behaviour of the AdS Virasoro-Shapiro Amplitude
- Author
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Alday, Luis F., Nocchi, Maria, Virally, Clément, and Zhou, Xinan
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High Energy Physics - Theory - Abstract
We compute the AdS Virasoro-Shapiro amplitude in the Regge limit, in terms of the CFT data of the exchanged operators in the leading Regge trajectory. To any order in the small curvature expansion, the result can be written in terms of derivatives of the flat space Virasoro-Shapiro amplitude in the Regge limit. The result also admits an integral representation involving single-valued logarithms, fully consistent with recent proposals for the full AdS Virasoro-Shapiro amplitude., Comment: 20 pages, 1 figure
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- 2024
3. Topological communities in complex networks
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Seoane, Luís F
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Physics - Physics and Society ,Condensed Matter - Disordered Systems and Neural Networks - Abstract
Most complex systems can be captured by graphs or networks. Networks connect nodes (e.g.\ neurons) through edges (synapses), thus summarizing the system's structure. A popular way of interrogating graphs is community detection, which uncovers sets of geometrically related nodes. {\em Geometric communities} consist of nodes ``closer'' to each other than to others in the graph. Some network features do not depend on node proximity -- rather, on them playing similar roles (e.g.\ building bridges) even if located far apart. These features can thus escape proximity-based analyses. We lack a general framework to uncover such features. We introduce {\em topological communities}, an alternative perspective to decomposing graphs. We find clusters that describe a network as much as classical communities, yet are missed by current techniques. In our framework, each graph guides our attention to its relevant features, whether geometric or topological. Our analysis complements existing ones, and could be a default method to study networks confronted without prior knowledge. Classical community detection has bolstered our understanding of biological, neural, or social systems; yet it is only half the story. Topological communities promise deep insights on a wealth of available data. We illustrate this for the global airport network, human connectomes, and others., Comment: 34 pages, 3 main figures, 22 supporting figures
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- 2024
4. Magnetic Fields in Massive Star-forming Regions (MagMaR) IV: Tracing the Magnetic Fields in the O-type protostellar system IRAS 16547$-$4247
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Zapata, Luis A., Fernández-López, Manuel, Sanhueza, Patricio, Girart, Josep M., Rodríguez, Luis F., Cortes, Paulo, Patrick, Koch, Beltrán, María T., Pattle, Kate, Beuther, Henrik, Saha, Piyali, Jiao, Wenyu, Xu, Fengwei, Lu, Xing Walker, Olguin, Fernando, Li, Shanghuo, Stephens, Ian W., Kang, Ji-hyun, Cheng, Yu, Choudhury, Spandan, Morii, Kaho, Chung, Eun Jung, Wang, Jia-Wei, Hwang, Jihye, Lyo, A-Ran, Zhang, Qizhou, and Chen, Huei-Ru Vivien
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
The formation of the massive stars, and in particular, the role that the magnetic fields play in their early evolutionary phase is still far from being completely understood. Here, we present Atacama Large Millimeter/Submillimeter Array (ALMA) 1.2 mm full polarized continuum, and H$^{13}$CO$^+$(3$-$2), CS(5$-$4), and HN$^{13}$C(3$-$2) line observations with a high angular resolution ($\sim$0.4$''$ or 1100 au). In the 1.2 mm continuum emission, we reveal a dusty envelope surrounding the massive protostars, IRAS16547-E and IRAS16547-W, with dimensions of $\sim$10,000 au. This envelope has a bi-conical structure likely carved by the powerful thermal radio jet present in region. The magnetic fields vectors follow very-well the bi-conical envelope. The polarization fraction is $\sim$2.0\% in this region. Some of these vectors seem to converge to IRAS 16547-E, and IRAS 16547-W, the most massive protostars. Moreover, the velocity fields revealed from the spectral lines H$^{13}$CO$^+$(3$-$2), and HN$^{13}$C(3$-$2) show velocity gradients with a good correspondence with the magnetic fields, that maybe are tracing the cavities of molecular outflows or maybe in some parts infall. We derived a magnetic field strength in some filamentary regions that goes from 2 to 6.1\,mG. We also find that the CS(5$-$4) molecular line emission reveals multiple outflow cavities or bow-shocks with different orientations, some of which seem to follow the NW-SE radio thermal jet., Comment: Accepted by the Astrophysical Journal, 13 pages
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- 2024
5. Radio Proper Motions and a Search for the Origin of PSR B1849+00
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Rodriguez, Luis F., Dzib, Sergio A., Zapata, Luis A., and Loinard, Laurent
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
Until now it has not been possible to obtain the proper motions of PSR B1849+00 with timing techniques or VLBI imaging given the enhanced interstellar scattering along its line of sight. We present an analysis of archive Very Large Array observations at epochs from 2012 to 2022 that indicates a total proper motion of 23.9$\pm$5.5 mas yr$^{-1}$ toward the southwest. After correction for the proper motions produced by galactic rotation, we find a peculiar transverse velocity of $\simeq$740 km s$^{-1}$. We searched unsuccessfully along the past trajectory of the pulsar for an associated supernova remnant. In particular, W44 is in this trajectory but its distance is different to that of PSR B1849+00., Comment: 9 pages, 4 figures. To appear in Revista Mexicana de Astronomia y Astrofisica
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- 2024
6. Finding Patterns in Ambiguity: Interpretable Stress Testing in the Decision~Boundary
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Gomes, Inês, Teixeira, Luís F., van Rijn, Jan N., Soares, Carlos, Restivo, André, Cunha, Luís, and Santos, Moisés
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Computer Science - Machine Learning ,Computer Science - Computer Vision and Pattern Recognition - Abstract
The increasing use of deep learning across various domains highlights the importance of understanding the decision-making processes of these black-box models. Recent research focusing on the decision boundaries of deep classifiers, relies on generated synthetic instances in areas of low confidence, uncovering samples that challenge both models and humans. We propose a novel approach to enhance the interpretability of deep binary classifiers by selecting representative samples from the decision boundary - prototypes - and applying post-model explanation algorithms. We evaluate the effectiveness of our approach through 2D visualizations and GradientSHAP analysis. Our experiments demonstrate the potential of the proposed method, revealing distinct and compact clusters and diverse prototypes that capture essential features that lead to low-confidence decisions. By offering a more aggregated view of deep classifiers' decision boundaries, our work contributes to the responsible development and deployment of reliable machine learning systems., Comment: To be published in the Responsible Generative AI workshop at CVPR
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- 2024
7. DeepFace-Attention: Multimodal Face Biometrics for Attention Estimation with Application to e-Learning
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Daza, Roberto, Gomez, Luis F., Fierrez, Julian, Morales, Aythami, Tolosana, Ruben, and Ortega-Garcia, Javier
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Computer Science - Human-Computer Interaction ,Computer Science - Computer Vision and Pattern Recognition - Abstract
This work introduces an innovative method for estimating attention levels (cognitive load) using an ensemble of facial analysis techniques applied to webcam videos. Our method is particularly useful, among others, in e-learning applications, so we trained, evaluated, and compared our approach on the mEBAL2 database, a public multi-modal database acquired in an e-learning environment. mEBAL2 comprises data from 60 users who performed 8 different tasks. These tasks varied in difficulty, leading to changes in their cognitive loads. Our approach adapts state-of-the-art facial analysis technologies to quantify the users' cognitive load in the form of high or low attention. Several behavioral signals and physiological processes related to the cognitive load are used, such as eyeblink, heart rate, facial action units, and head pose, among others. Furthermore, we conduct a study to understand which individual features obtain better results, the most efficient combinations, explore local and global features, and how temporary time intervals affect attention level estimation, among other aspects. We find that global facial features are more appropriate for multimodal systems using score-level fusion, particularly as the temporal window increases. On the other hand, local features are more suitable for fusion through neural network training with score-level fusion approaches. Our method outperforms existing state-of-the-art accuracies using the public mEBAL2 benchmark., Comment: Article accepted in the IEEE Access journal. Accessible at https://ieeexplore.ieee.org/document/10633208
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- 2024
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8. Operational range bounding of spectroscopy models with anomaly detection
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Simões, Luís F., Casale, Pierluigi, Felismino, Marília, Yip, Kai Hou, Waldmann, Ingo P., Tinetti, Giovanna, and Lueftinger, Theresa
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Computer Science - Machine Learning ,Astrophysics - Instrumentation and Methods for Astrophysics ,I.2.6 ,I.5.1 ,I.6.4 ,J.2 - Abstract
Safe operation of machine learning models requires architectures that explicitly delimit their operational ranges. We evaluate the ability of anomaly detection algorithms to provide indicators correlated with degraded model performance. By placing acceptance thresholds over such indicators, hard boundaries are formed that define the model's coverage. As a use case, we consider the extraction of exoplanetary spectra from transit light curves, specifically within the context of ESA's upcoming Ariel mission. Isolation Forests are shown to effectively identify contexts where prediction models are likely to fail. Coverage/error trade-offs are evaluated under conditions of data and concept drift. The best performance is seen when Isolation Forests model projections of the prediction model's explainability SHAP values., Comment: To appear in "Proceedings of SPAICE 2024: 1st ESA/IAA conference on AI in and for Space". Conference page at https://spaice.esa.int/
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- 2024
9. Constraints on the $\gamma$-parameter for the vacuum solution of Cotton gravity with geodesics and shadows
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Junior, Ednaldo L. B., Junior, José Tarciso S. S., Lobo, Francisco S. N., Rodrigues, Manuel E., Rubiera-Garcia, Diego, da Silva, Luís F. Dias, and Vieira, Henrique A.
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General Relativity and Quantum Cosmology ,Astrophysics - High Energy Astrophysical Phenomena ,High Energy Physics - Theory - Abstract
We consider a recently introduced extension of General Relativity dubbed as Cotton gravity (CG), based on the use of the Cotton tensor, to estimate the size of a new constant $\gamma$ appearing within a spherically symmetric, vacuum solution of the theory. Taking into account its non-asymptotically flat character, we use the inferred size of the central brightness depression of the supermassive object at the heart of the Milky Way galaxy (Sgr A*) by the Event Horizon Telescope to constrain at $2\sigma$ the CG parameter as $\gamma M \approx 3.5 \times 10^{-12}$. We study the potential observational consequences from the smallness of such a value using exact and numerical expressions for the deflection angle, optical images from optically and geometrically thin accretion disks, isoradials, and instability scales (Lyapunov index) of nearly bound geodesics associated to photon rings. Our results point towards the impossibility to distinguish between these two geometries using current and foreseeable techniques in the field of interferometric detection of optical sources., Comment: 13 pages, 8 figures
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- 2024
10. Black bounces in Cotton gravity
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Junior, Ednaldo L. B., Junior, José Tarciso S. S., Lobo, Francisco S. N., Rodrigues, Manuel E., Rubiera-Garcia, Diego, da Silva, Luís F. Dias, and Vieira, Henrique A.
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General Relativity and Quantum Cosmology ,High Energy Physics - Theory - Abstract
Recently, J. Harada proposed a theory relating gravity to the Cotton tensor, dubbed as ''Cotton gravity'' (CG). This is an extension of General Relativity such that every solution of the latter turns out to be a solution of the former (but the converse is not true) and, furthermore, it is possible to derive the cosmological constant as an integration constant within it. In this work we investigate CG by coupling it to both non-linear electrodynamics (NLED) and scalar fields. We study static and spherically symmetric solutions implementing a bouncing behaviour in the radial function so as to avoid the development of singularities, inspired by the Simpson-Visser black bounce and the Bardeen model, both interpreted as magnetic monopoles. We identify the NLED Lagrangian density and the scalar field potential generating such solutions, and investigate the corresponding gravitational configurations in terms of horizons, behaviour of the metric functions, and regularity of the Kretchsman curvature scalar. Our analysis extends the class of non-singular geometries found in the literature and paves the ground for further analysis of black holes in CG., Comment: 14 pages, 6 figures
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- 2024
11. REMIX SPH -- improving mixing in smoothed particle hydrodynamics simulations using a generalised, material-independent approach
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Sandnes, Thomas D., Eke, Vincent R., Kegerreis, Jacob A., Massey, Richard J., Ruiz-Bonilla, Sergio, Schaller, Matthieu, and Teodoro, Luis F. A.
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Physics - Computational Physics ,Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Instrumentation and Methods for Astrophysics ,Physics - Fluid Dynamics - Abstract
We present REMIX, a smoothed particle hydrodynamics (SPH) scheme designed to alleviate effects that typically suppress mixing and instability growth at density discontinuities in SPH simulations. We approach this problem by directly targeting sources of kernel smoothing error and discretisation error, resulting in a generalised, material-independent formulation that improves the treatment both of discontinuities within a single material, for example in an ideal gas, and of interfaces between dissimilar materials. This approach also leads to improvements in capturing hydrodynamic behaviour unrelated to mixing, such as in shocks. We demonstrate marked improvements in three-dimensional test scenarios, focusing on more challenging cases with particles of equal mass across the simulation. This validates our methods for use-cases relevant across applications spanning astrophysics and engineering, where particles are free to evolve over a large range of density scales, or where emergent and evolving density discontinuities cannot easily be corrected by choosing bespoke particle masses in the initial conditions. We achieve these improvements while maintaining sharp discontinuities; without introducing additional equation of state dependence in, for example, particle volume elements; and without contrived or targeted corrections. Our methods build upon a fully compressible and thermodynamically consistent core-SPH construction, retaining Galilean invariance as well as conservation of mass, momentum, and energy. REMIX is integrated in the open-source, state-of-the-art \swift code and is designed with computational efficiency in mind, which means that its improved hydrodynamic treatment can be used for high-resolution simulations without significant cost to run-speed., Comment: 51 pages, 33 figures, submitted to Journal of Computational Physics
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- 2024
12. A Deep Reinforcement Learning Framework and Methodology for Reducing the Sim-to-Real Gap in ASV Navigation
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Batista, Luis F W, Ro, Junghwan, Richard, Antoine, Schroepfer, Pete, Hutchinson, Seth, and Pradalier, Cedric
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Computer Science - Robotics - Abstract
Despite the increasing adoption of Deep Reinforcement Learning (DRL) for Autonomous Surface Vehicles (ASVs), there still remain challenges limiting real-world deployment. In this paper, we first integrate buoyancy and hydrodynamics models into a modern Reinforcement Learning framework to reduce training time. Next, we show how system identification coupled with domain randomization improves the RL agent performance and narrows the sim-to-real gap. Real-world experiments for the task of capturing floating waste show that our approach lowers energy consumption by 13.1\% while reducing task completion time by 7.4\%. These findings, supported by sharing our open-source implementation, hold the potential to impact the efficiency and versatility of ASVs, contributing to environmental conservation efforts., Comment: IROS 2024, IEEE, Oct 2024, Abu Dhabi, United Arab Emirates
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- 2024
13. The Radio Continuum Source Projected Near HR 8799
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Rodriguez, Luis F. and Zapata, Luis A.
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
HR 8799 is an A5/F0 V star where exoplanets were first directly imaged. Four exoplanets were found within $\simeq 2\rlap.{''}0$ from the star. Here we report the VLA detection of a faint (19.1$\pm$2.7 $\mu$Jy) radio continuum (3.0 GHz) source projected at $\simeq 2\rlap.{''}2$ from the star. The \sl a priori \rm probability of finding a background source with this flux density within a radius of $2\rlap.{''}2$ is only 0.0046. However, the astrometry made with the VLA and ALMA images, separated by 5.5 years, indicates no significant proper motions and rules out the association of the radio source with the HR 8799 system and suggests it is a background millimeter galaxy with dust emission in the millimeter and partially thick synchrotron emission in the centimeter., Comment: 8 pages, 2 figures. To appear in Revista Mexicana de Astronomia y Astrofisica
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- 2024
14. Markerless Multi-view 3D Human Pose Estimation: a survey
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Nogueira, Ana Filipa Rodrigues, Oliveira, Hélder P., and Teixeira, Luís F.
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Computer Science - Computer Vision and Pattern Recognition - Abstract
3D human pose estimation aims to reconstruct the human skeleton of all the individuals in a scene by detecting several body joints. The creation of accurate and efficient methods is required for several real-world applications including animation, human-robot interaction, surveillance systems or sports, among many others. However, several obstacles such as occlusions, random camera perspectives, or the scarcity of 3D labelled data, have been hampering the models' performance and limiting their deployment in real-world scenarios. The higher availability of cameras has led researchers to explore multi-view solutions due to the advantage of being able to exploit different perspectives to reconstruct the pose. Thus, the goal of this survey is to present an overview of the methodologies used to estimate the 3D pose in multi-view settings, understand what were the strategies found to address the various challenges and also, identify their limitations. Based on the reviewed articles, it was possible to find that no method is yet capable of solving all the challenges associated with the reconstruction of the 3D pose. Due to the existing trade-off between complexity and performance, the best method depends on the application scenario. Therefore, further research is still required to develop an approach capable of quickly inferring a highly accurate 3D pose with bearable computation cost. To this goal, techniques such as active learning, methods that learn with a low level of supervision, the incorporation of temporal consistency, view selection, estimation of depth information and multi-modal approaches might be interesting strategies to keep in mind when developing a new methodology to solve this task., Comment: 22 pages, 5 figures, submitted to Image and Vision Computing (IMAVIS)
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- 2024
15. How to Sample Dozens of Substitutions per Site with λ Dynamics
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Hayes, Ryan L, Cervantes, Luis F, Santos, Justin Cruz Abad, Samadi, Amirmasoud, Vilseck, Jonah Z, and Brooks, Charles L
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Chemical Sciences ,Physical Chemistry ,Theoretical and Computational Chemistry ,Bioengineering ,Networking and Information Technology R&D (NITRD) ,Biotechnology ,1.1 Normal biological development and functioning ,Generic health relevance ,Biochemistry and Cell Biology ,Computer Software ,Chemical Physics ,Physical chemistry ,Theoretical and computational chemistry - Abstract
Alchemical free energy methods are useful in computer-aided drug design and computational protein design because they provide rigorous statistical mechanics-based estimates of free energy differences from molecular dynamics simulations. λ dynamics is a free energy method with the ability to characterize combinatorial chemical spaces spanning thousands of related systems within a single simulation, which gives it a distinct advantage over other alchemical free energy methods that are mostly limited to pairwise comparisons. Recently developed methods have improved the scalability of λ dynamics to perturbations at many sites; however, the size of chemical space that can be explored at each individual site has previously been limited to fewer than ten substituents. As the number of substituents increases, the volume of alchemical space corresponding to nonphysical alchemical intermediates grows exponentially relative to the size corresponding to the physical states of interest. Beyond nine substituents, λ dynamics simulations become lost in an alchemical morass of intermediate states. In this work, we introduce new biasing potentials that circumvent excessive sampling of intermediate states by favoring sampling of physical end points relative to alchemical intermediates. Additionally, we present a more scalable adaptive landscape flattening algorithm for these larger alchemical spaces. Finally, we show that this potential enables more efficient sampling in both protein and drug design test systems with up to 24 substituents per site, enabling, for the first time, simultaneous simulation of all 20 amino acids.
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- 2024
16. Carrollian Amplitudes from Holographic Correlators
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Alday, Luis F., Nocchi, Maria, Ruzziconi, Romain, and Srikant, Akshay Yelleshpur
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High Energy Physics - Theory ,General Relativity and Quantum Cosmology - Abstract
Carrollian amplitudes are flat space amplitudes written in position space at null infinity which can be re-interpreted as correlators in a putative dual Carrollian CFT. We argue that these amplitudes are the natural objects obtained in the flat space limit of AdS Lorentzian boundary correlators. The flat limit is taken entirely in position space by introducing Bondi coordinates in the bulk. From the bulk perspective, this procedure makes it manifest that the flat limit of any Witten diagram is the corresponding flat space Feynman diagram. It also makes explicit the fact that the flat limit in the bulk is implemented by a Carrollian limit at the boundary. We systematically analyse tree-level two, three and four-point correlators. Familiar features such as the distributional nature of Carrollian amplitudes and the presence of a bulk point singularity arise naturally as a consequence of requiring a finite and non-trivial Carrollian limit., Comment: 48 pages, 9 figures
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- 2024
17. Learning from landmarks, curves, surfaces, and shapes in Geomstats
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Pereira, Luís F., Brigant, Alice Le, Myers, Adele, Hartman, Emmanuel, Khan, Amil, Tuerkoen, Malik, Dold, Trey, Gu, Mengyang, Suárez-Serrato, Pablo, and Miolane, Nina
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Computer Science - Graphics ,Computer Science - Mathematical Software ,Mathematics - Differential Geometry - Abstract
We introduce the shape module of the Python package Geomstats to analyze shapes of objects represented as landmarks, curves and surfaces across fields of natural sciences and engineering. The shape module first implements widely used shape spaces, such as the Kendall shape space, as well as elastic spaces of discrete curves and surfaces. The shape module further implements the abstract mathematical structures of group actions, fiber bundles, quotient spaces and associated Riemannian metrics which allow users to build their own shape spaces. The Riemannian geometry tools enable users to compare, average, interpolate between shapes inside a given shape space. These essential operations can then be leveraged to perform statistics and machine learning on shape data. We present the object-oriented implementation of the shape module along with illustrative examples and show how it can be used to perform statistics and machine learning on shape spaces.
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- 2024
18. Unsupervised Contrastive Analysis for Salient Pattern Detection using Conditional Diffusion Models
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Patrício, Cristiano, Barbano, Carlo Alberto, Fiandrotti, Attilio, Renzulli, Riccardo, Grangetto, Marco, Teixeira, Luis F., and Neves, João C.
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Computer Science - Computer Vision and Pattern Recognition - Abstract
Contrastive Analysis (CA) regards the problem of identifying patterns in images that allow distinguishing between a background (BG) dataset (i.e. healthy subjects) and a target (TG) dataset (i.e. unhealthy subjects). Recent works on this topic rely on variational autoencoders (VAE) or contrastive learning strategies to learn the patterns that separate TG samples from BG samples in a supervised manner. However, the dependency on target (unhealthy) samples can be challenging in medical scenarios due to their limited availability. Also, the blurred reconstructions of VAEs lack utility and interpretability. In this work, we redefine the CA task by employing a self-supervised contrastive encoder to learn a latent representation encoding only common patterns from input images, using samples exclusively from the BG dataset during training, and approximating the distribution of the target patterns by leveraging data augmentation techniques. Subsequently, we exploit state-of-the-art generative methods, i.e. diffusion models, conditioned on the learned latent representation to produce a realistic (healthy) version of the input image encoding solely the common patterns. Thorough validation on a facial image dataset and experiments across three brain MRI datasets demonstrate that conditioning the generative process of state-of-the-art generative methods with the latent representation from our self-supervised contrastive encoder yields improvements in the generated image quality and in the accuracy of image classification. The code is available at https://github.com/CristianoPatricio/unsupervised-contrastive-cond-diff., Comment: 18 pages, 11 figures
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- 2024
19. Determining the Possibility of Multistationarity in a Model of the Earth Carbon Cycle with Direct Air Capture
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Fortun, Noel T., Lao, Angelyn R., Mendoza, Eduardo R., and Razon, Luis F.
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Mathematics - Dynamical Systems - Abstract
The existence of steady-state multiplicity or multistationarity in the Earth System raises the possibility that the Earth may reach a "tipping point" and rapidly transition to a warmer steady-state from which recovery may be practically impossible. In detailed Earth models that require extensive computation time, it is difficult to make an a priori prediction of the existence of steady-state multiplicity. In this study, we demonstrate Chemical Reaction Network Theory (CRNT) analysis of a simple heuristic box model of the Earth System carbon cycle with the human intervention of direct air capture. The analysis reveals necessary conditions for the combination of system parameters where steady-state multiplicity may exist. With this method, other negative emissions technologies (NET) may be screened in a relatively simple manner to aid in the priority setting by policymakers., Comment: arXiv admin note: text overlap with arXiv:2209.12143
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- 2024
20. Detecting the spread of valence band Wannier functions by optical sum rules
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Cárdenas-Castillo, Luis F., Zhang, Shuai, Kochan, Denis, Freire Jr., Fernando L., and Chen, Wei
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Condensed Matter - Materials Science - Abstract
The spread of valence band Wannier functions in semiconductors and insulators is a characteristic property that gives a rough estimation of how insulating is the material. We elaborate that the gauge-invariant part of the spread can be extracted experimentally from optical conductivity and absorbance, owing to their equivalence to the quantum metric of the valence band states integrated over momentum. Because the quantum metric enters the matrix element of optical conductivity, the spread of valence band Wannier functions in the gapped 3D materials can be obtained from the frequency-integration of the imaginary part of the dielectric function. We demonstrate this practically for typical semiconductors like Si and Ge, and for topological insulators like Bi$_{2}$Te$_{3}$. In 2D materials, the spread of Wannier functions in the valence bands can be obtained from the absorbance divided by frequency and then integrated over frequency. Applying this method to graphene reveals a finite spread caused by intrinsic spin-orbit coupling, which may be detected by absorbance in the microwave range. The absorbance of twisted bilayer graphene in the millimeter wave range can be used to detect the formation of the flat bands and quantify their quantum metric. Finally, we apply our method to hexagonal transition metal dichalcogenides MX$_{2}$ (M = Mo, W; X = S, Se, Te) and demonstrate how other effects like substrate, excitons, and higher energy bands can affect the spread of Wannier function., Comment: 13 pages, 7 figures
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- 2024
21. Momentum non-conservation in a scalar quantum field theory with a planar $\theta$ interface
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Velázquez, Daniel G., von Dossow, R. Martínez, and Urrutia, Luis F.
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High Energy Physics - Theory ,High Energy Physics - Phenomenology - Abstract
Motivated by the recent interest aroused by non-dynamical axionic electrodynamics in the context of topological insulators and Weyl semimetals, we discuss a simple model of the magnetoelectric effect in terms of a $\theta$-scalar field that interacts through a delta-like potential located at a planar interface. Thus, in the bulk regions the field is constructed by standard free waves with the absence of evanescent components. These waves have to be combined into linear superposition to account for the boundary conditions at the interface in order to yield the corresponding normal modes. Our aim is twofold: first we quantize the $\theta$-scalar field using the normal modes in the canonical approach and then we look for applications emphasizing the effect of momentum non-conservation due to the presence of the interface. To this end we calculate the decay of a standard scalar particle into two $\theta$-scalar particles showing the opening of new decay channels. As a second application we deal with the two body scattering of standard charged scalar particles mediated by a $\theta$-scalar particle, focusing on the momentum non-conserving contribution of the scattering amplitude ${\cal M}^{NC}$. We define a generalization of the usual cross section in order to quantify the emergence of these events. We also study the allowed kinematical region for momentum non-conservation as well as the position of the poles of the amplitude ${\cal M}^{NC}$. Finally, the ratio of the magnitudes between ${\cal M}^{NC}$ and the momentum conserving amplitude is discussed in the appropriate region of momentum space.
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- 2024
22. Spontaneous Lorentz symmetry-breaking constraints in Kalb-Ramond gravity
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Junior, Ednaldo L. B., Junior, José Tarciso S. S., Lobo, Francisco S. N., Rodrigues, Manuel E., Rubiera-Garcia, Diego, da Silva, Luís F. Dias, and Vieira, Henrique A.
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General Relativity and Quantum Cosmology ,Astrophysics - High Energy Astrophysical Phenomena ,High Energy Physics - Theory - Abstract
In this work, we study timelike and lightlike geodesics in Kalb-Ramond (KR) gravity around a black hole with the goal of constraining the Lorentz symmetry-breaking parameter $l$. The analysis involves studying the precession of the S2 star periastron orbiting Sgr A* and geodesic precession around the Earth. The ratio of precession frequencies for General Relativity (GR) and KR gravity is computed, with Event Horizon Telescope (EHT) results providing a parameter range for the spontaneous symmetry-breaking of $-0.185022 \leq l \leq 0.060938$. Utilizing the geodesic precession frequency from the Gravity Probe B (GP-B), the $l$ parameter is further constrained to $-6.30714 \times 10^{-12} \leq l \leq 3.90708 \times 10^{-12}$, which is consistent with the Schwarzschild limits. Moreover, for timelike geodesics, the innermost circular orbit (ICO) and innermost stable circular orbit (ISCO) are determined and analyzed to illustrate the impact of the symmetry breaking term. Zoom-whirl obstructions are compared with the Schwarzschild solution. Lower and upper limits of the photon sphere for lightlike geodesics are established to demonstrate the influence of KR gravity on the photon sphere. Additionally, the shadow radius is determined for two observers, one situated at a finite distance from the KR black hole, and the other located at an infinite distance, to constrain the symmetry-breaking parameter $l$, with comparisons made to EHT results. The bounds for $l$ derived from constraints on the photon sphere radius for lightlike geodesics yield $-0.0700225 \leq l \leq 0.189785$ using EHT data. The findings of this paper align with experimental results in the $l \rightarrow 0$ limit., Comment: 11 pages, 4 figures
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- 2024
23. Gravitational lensing of a Schwarzschild-like black hole in Kalb-Ramond gravity
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Junior, Ednaldo L. B., Junior, José Tarciso S. S., Lobo, Francisco S. N., Rodrigues, Manuel E., Rubiera-Garcia, Diego, da Silva, Luís F. Dias, and Vieira, Henrique A.
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General Relativity and Quantum Cosmology ,Astrophysics - High Energy Astrophysical Phenomena ,High Energy Physics - Theory - Abstract
In this paper, we investigate the gravitational lensing effect for the Schwarzschild-like black hole spacetime in the background of a Kalb-Ramond (KR) field proposed in [K. Yang et. al., Phys. Rev. D 108 (2023) 124004]. The solution is characterized by a single extra parameter $l$, which is associated to the Lorentz symmetry breaking induced by the KR field. First, we calculate the exact deflection angle of massive and massless particles for finite distances using elliptic integrals. Then we study this effect in the weak and strong field regimes, discussing the correction of the KR parameter on the coefficients of the expansions in both limits. We also find that increasing $l$ decreases the deflection angle. Furthermore, we use the available data from the Sagittarius $A^{\star}$ object, which is believed to be a supermassive black hole at the center of our galaxy, to calculate relevant observables, such as, the image position, luminosity, and delay time. The values found could be potentially measured in the weak field regime, though for strong fields one would have to wait for the next generation of interferometers., Comment: 16 pages, 8 figures. V2: references added. arXiv admin note: text overlap with arXiv:2309.02658
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- 2024
- Full Text
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24. Single-valuedness of the AdS Veneziano amplitude
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Alday, Luis F. and Hansen, Tobias
- Subjects
High Energy Physics - Theory - Abstract
We consider the Veneziano amplitude for the scattering of gluons in type IIB string theory on $AdS_5 \times S^5/\mathbb{Z}_2$ in the presence of D7 branes. On general grounds curvature corrections around flat space can be thought of as arising from the extra insertion of soft gravitons. This naturally leads to an open string world-sheet representation with the extra insertion of single-valued functions evaluated on the real line. We check that the recently obtained first curvature correction is of this form and use this new constraint to compute the second curvature correction of the AdS Veneziano amplitude., Comment: 18 pages
- Published
- 2024
25. Waiting time statistics for a double quantum dot coupled with an optical cavity
- Author
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Santos, Luis F. and Landi, Gabriel T.
- Subjects
Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Statistical Mechanics - Abstract
A double quantum dot coupled to an optical cavity is a prototypical example of a non-trivial open quantum system. Recent experimental and theoretical studies show that this system is a candidate for single-photon detection in the microwave domain. This motivates studies that go beyond just the average current, and also take into account the full counting statistics of photon and electron detections. With this in mind, here we provide a detailed analysis of the waiting time statistics of this system within the quantum jump unravelling, which allows us to extract analytical expressions for the success and failure probabilities, as well as for the inter detection times. Furthermore, by comparing single and multi-photon scenarios, we infer a hierarchy of occurrence probabilities for the different events, highlighting the role of photon interference events in the detection probabilities. Our results therefore provide a direct illustration of how waiting time statistics can be used to optimize a timely and relevant metrological task., Comment: 5 pages, 3 figures
- Published
- 2024
26. Grover's algorithm in a four-qubit silicon processor above the fault-tolerant threshold
- Author
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Thorvaldson, Ian, Poulos, Dean, Moehle, Christian M., Misha, Saiful H., Edlbauer, Hermann, Reiner, Jonathan, Geng, Helen, Voisin, Benoit, Jones, Michael T., Donnelly, Matthew B., Pena, Luis F., Hill, Charles D., Myers, Casey R., Keizer, Joris G., Chung, Yousun, Gorman, Samuel K., Kranz, Ludwik, and Simmons, Michelle Y.
- Subjects
Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Spin qubits in silicon are strong contenders for realizing a practical quantum computer. This technology has made remarkable progress with the demonstration of single and two-qubit gates above the fault-tolerant threshold and entanglement of up to three qubits. However, maintaining high fidelity operations while executing multi-qubit algorithms has remained elusive, only being achieved for two spin qubits to date due to the small qubit size, which makes it difficult to control qubits without creating crosstalk errors. Here, we use a four-qubit silicon processor with every operation above the fault tolerant limit and demonstrate Grover's algorithm with a ~95% probability of finding the marked state, one of the most successful implementations to date. Our four-qubit processor is made of three phosphorus atoms and one electron spin precision-patterned into 1.5 nm${}^2$ isotopically pure silicon. The strong resulting confinement potential, without additional confinement gates that can increase cross-talk, leverages the benefits of having both electron and phosphorus nuclear spins. Significantly, the all-to-all connectivity of the nuclear spins provided by the hyperfine interaction not only allows for efficient multi-qubit operations, but also provides individual qubit addressability. Together with the long coherence times of the nuclear and electron spins, this results in all four single qubit fidelities above 99.9% and controlled-Z gates between all pairs of nuclear spins above 99% fidelity. The high control fidelities, combined with >99% fidelity readout of all nuclear spins, allows for the creation of a three-qubit Greenberger-Horne-Zeilinger (GHZ) state with 96.2% fidelity, the highest reported for semiconductor spin qubits so far. Such nuclear spin registers can be coupled via electron exchange, establishing a path for larger scale fault-tolerant quantum processors., Comment: 16 pages, 9 figures, 3 tables
- Published
- 2024
27. School and Family Ecosystem: Incentives and Barriers to School-Family Communication
- Author
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Fábio Botelho Guedes, Ana Cerqueira, Alexandra Marques-Pinto, Amélia Branco, Cecília Galvão, Joana Sousa, Luis F. Goulao, Rosário Bronze, Wanda Viegas, Tania Gaspar, Carmen Moreno, and Margarida Gaspar de Matos
- Abstract
The aim of the study was to explore the factors and barriers related to the incentive and opportunity of school-family communication. This work is part of the HOUSE-Colégio F3 Project, ULisbon, which included 1,143 first-year university students from the University of Lisbon, with average age of 19.61 ± 3.96 years. The young people who had better communication with their parents, greater family support and better family relationship were the ones who reported greater incentives for school-family communication. School--family communication and relationship were associated with the incentives for school-family communication and greater parental monitoring. These results align with the literature stating that parents' communication and presence in all areas of young people's lives, including the school context, foster better social and family relationships and academic results. This result should not be read as a call for non-autonomy. Instead, it highlights that monitoring and supporting family presence promotes that autonomy.
- Published
- 2024
- Full Text
- View/download PDF
28. The AdS Veneziano amplitude at small curvature
- Author
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Alday, Luis F., Chester, Shai M., Hansen, Tobias, and Zhong, De-liang
- Subjects
High Energy Physics - Theory - Abstract
We compute the AdS Veneziano amplitude for type IIB gluon scattering in $AdS_5 \times S^3$ to all orders in $\alpha'$ in a small curvature expansion. This is achieved by combining a dispersion relation in the dual $4d$ $\mathcal{N}=2$ SCFT with an ansatz for the amplitude as a worldsheet integral in terms of multiple polylogarithms. The first curvature correction is fully fixed in this way and satisfies consistency checks in the high energy limit, the low energy expansion as previously fixed using supersymmetric localisation, and for the energy of massive string operators, which we independently compute using a semiclassical expansion. We also combine localisation with this first curvature correction to fix the unprotected $D^4F^4$ correction to the amplitude at finite curvature., Comment: 45 pages, 7 figures
- Published
- 2024
29. Smooth real-time motion planning based on a cascade dual-quaternion screw-geometry MPC
- Author
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Teimoorzadeh, Ainoor, Silva, Frederico Fernandes Afonso, Figueredo, Luis F. C., and Haddadin, Sami
- Subjects
Computer Science - Robotics ,Electrical Engineering and Systems Science - Systems and Control - Abstract
This paper investigates the tracking problem of a smooth coordinate-invariant trajectory using dual quaternion algebra. The proposed architecture consists of a cascade structure in which the outer-loop MPC performs real-time smoothing of the manipulator's end-effector twist while an inner-loop kinematic controller ensures tracking of the instantaneous desired end-effector pose. Experiments on a $7$-DoF Franka Emika Panda robotic manipulator validate the proposed method demonstrating its application to constraint the robot twists, accelerations and jerks within prescribed bounds.
- Published
- 2024
30. Degradation Analysis of Perovskite Solar Cells via Short-Circuit Impedance Spectroscopy: A case study on NiOx passivation
- Author
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Almora, Osbel, López-Varo, Pilar, Escalante, Renán, Mohanraj, John, Marsal, Luis F, Olthof, Selina, and Anta, Juan A.
- Subjects
Physics - Applied Physics ,Condensed Matter - Materials Science - Abstract
Perovskite solar cells (PSCs) continue to be the front runner technology among emerging photovoltaic devices in terms of power conversion efficiency and application versatility. However, not only the stability but also the understanding of their ionic-electronic transport mechanisms continues to be challenging. In this work, the case study of NiOx-based inverted PSCs and the effect of different interface passivating treatments on the device performance are approached. Our experiments include impedance spectroscopy (IS) measurements in short-circuit under different illumination intensities and operational stability tests under constant illumination intensity. It is found that certain surface treatments lead to more stable performance. However, protic anion donors can induce, both, an initial performance decrease and a subsequent reactivity during light exposure which apparently improves the cells performance. Our drift-diffusion simulations suggest that the modification of the interface with the hole transport material may have decrease the conductivity, as well as the ion and electron mobilities at the perovskite and the NiOx, respectively. Importantly, capacitance and resistance are shown to peak maximum and minimum values, respectively, around specific ranges of mobile ion concentration. Our results introduce a general route for characterization of degradation paths in PSCs via IS in short-circuit.
- Published
- 2024
31. A Radio Counterpart to a Jupiter-Mass Binary Object in Orion
- Author
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Rodriguez, Luis F., Loinard, Laurent, and Zapata, Luis A.
- Subjects
Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Using James Webb Space Telescope near-infrared data of the inner Orion Nebula, \citet{Pearson_McCaughrean_2023} detected 40 Jupiter-Mass Binary Objects (JuMBOS). These systems are not associated with stars and their components have masses of giant Jupiter-like planets and separations in the plane of the sky of order $\sim$100 au. The existence of these wide free-floating planetary mass binaries was unexpected in our current theories of star and planet formation. Here we report the radio continuum (6.1 and 10.0 GHz) Karl G.\ Jansky Very Large Array detection of a counterpart to JuMBO\,24. The radio emission appears to be steady at a level of $\sim$50 $\mu$Jy over timescales of days and years. We set an upper limit of $\simeq15$~km~s$^{-1}$ to the velocity of the radio source in the plane of the sky. As in the near-infrared, the radio emission seems to be coming from both components of the binary., Comment: To appear in The Astrophysical Journal Letters, 7 pages, 1 figure
- Published
- 2024
32. Dynamical mass of the Ophiuchus intermediate-mass stellar system S1 with DYNAMO-VLBA
- Author
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Ordóñez-Toro, Jazmín, Dzib, Sergio A., Loinard, Laurent, Ortiz-León, Gisela, Kounkel, Marina A., Masqué, Josep M., Medina, S. -N. X., Galli, Phillip A. B., Dupuy, Trent J., Rodríguez, Luis F., and Quiroga-Nuñez, Luis H.
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
We report dynamical mass measurements of the individual stars in the most luminous and massive stellar member of the nearby Ophiuchus star-forming region, the young tight binary system S1. We combine 28 archival datasets with seven recent, proprietary VLBA observations obtained as part of the \textit{Dynamical Masses of Young Stellar Multiple Systems with the VLBA} project (DYNAMO--VLBA), to constrain the astrometric and orbital parameters of the system, and recover high accuracy dynamical masses. The primary component, S1A, is found to have a mass of 4.11$\pm$0.10~M$_\odot$, significantly less than the typical value, $\sim$~6~M$_\odot$ previously reported in the literature. We show that the spectral energy distribution of S1A can be reproduced by a reddened blackbody with a temperature between roughly 14,000~K and 17,000~K. According to evolutionary models, this temperature range corresponds to stellar masses between 4~M$_\odot$ and 6~M$_\odot$ so the SED is not a priori inconsistent with the dynamical mass of S1A. The luminosity of S1 derived from SED-fitting, however, is only consistent with models for stellar masses above 5~M$_\odot$. Thus, we cannot reconcile the evolutionary models with the dynamical mass measurement of S1A: the models consistent with the location of S1A in the HR diagram correspond to masses at least 25\% higher than the dynamical mass. For the secondary component, S1B, a mass of 0.831~$\pm$~0.014~M$_\odot $ is determined, consistent with a low-mass young star. While the radio flux of S1A remains roughly constant throughout the orbit, the flux of S1B is found to be higher near the apastron.
- Published
- 2024
33. Physio: An LLM-Based Physiotherapy Advisor
- Author
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Almeida, Rúben, Sousa, Hugo, Cunha, Luís F., Guimarães, Nuno, Campos, Ricardo, and Jorge, Alípio
- Subjects
Computer Science - Computation and Language ,Computer Science - Information Retrieval ,68T07 ,I.2 ,J.3 - Abstract
The capabilities of the most recent language models have increased the interest in integrating them into real-world applications. However, the fact that these models generate plausible, yet incorrect text poses a constraint when considering their use in several domains. Healthcare is a prime example of a domain where text-generative trustworthiness is a hard requirement to safeguard patient well-being. In this paper, we present Physio, a chat-based application for physical rehabilitation. Physio is capable of making an initial diagnosis while citing reliable health sources to support the information provided. Furthermore, drawing upon external knowledge databases, Physio can recommend rehabilitation exercises and over-the-counter medication for symptom relief. By combining these features, Physio can leverage the power of generative models for language processing while also conditioning its response on dependable and verifiable sources. A live demo of Physio is available at https://physio.inesctec.pt., Comment: Demo, ECIR 2024, 3rd Sword AI challenge 2023
- Published
- 2024
- Full Text
- View/download PDF
34. Observations on the massive particle surface method
- Author
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Junior, Ednaldo L. B., Junior, José Tarciso S. S., Lobo, Francisco S. N., Rodrigues, Manuel E., da Silva, Luís F. Dias, and Vieira, Henrique A.
- Subjects
General Relativity and Quantum Cosmology ,Astrophysics - High Energy Astrophysical Phenomena ,High Energy Physics - Theory - Abstract
The geodesic method has played a crucial role in understanding the circular orbits generated by compact objects, culminating in the definition of the photon sphere, which was later generalized to a photon surface in arbitrary spacetimes. This new formulation extends the concept of the photon sphere in a broader sense, including dynamical spacetimes, as shown by the Vaidya solution. The photon surface essentially defines the null geodesics, which are originally tangent to the temporal surface, and keeps them confined to this surface. However, this formalism does not cover all classes of particles, and to overcome this limitation, a more comprehensive approach, denoted as the "massive particle surface", has been proposed that also accounts for charged massive particles. Indeed, the photon surface concept is recovered when the charge and mass of the particles are zero. In this work, we use these three formalisms to check the consistency of the results for the values of the radius of the photon sphere ($r_{ps}$) and the radius of the "innermost stable circular orbit" (ISCO) ($r_{\rm ISCO}$) for some gravitational models. In our results, the first model is described by conformal gravity, with the peculiarity that $g_{00}\neq-g_{11}^{-1}$. The second model, i.e. the Culetu solution, is developed by coupling General Relativity with nonlinear electrodynamics, which requires the consideration of the effective metric ($g_{\rm eff}^{\mu\nu}$) for geodesic approaches. Furthermore, we have also analysed the expressions for $r_{ps}$ and $r_{\rm ISCO}$ in a general static and spherically symmetric metric. Under these circumstances, we have found a discrepancy of $r_{ps}$ and $r_{\rm ISCO}$ obtained by the massive particle surface formalism as compared to the geodesic and photon surface formalisms., Comment: 15 pages, 1 figure; comments are welcome
- Published
- 2024
35. Survival at 3, 6 and 12 months in patients diagnosed with community-acquired pneumonia in Colombia: a retrospective cohort study
- Author
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Tuta-Quintero, Eduardo, Torres-Arevalo, Daniela, Bastidas-Goyes, Alirio Rodrigo, Aponte-Murcia, Hermencia C., Guerrero, Manuela, Giraldo, Andrea, Villarraga, Laura, Orjuela, Laura, Hernandez, Juan, and Giraldo-Cadavid, Luis F.
- Published
- 2024
- Full Text
- View/download PDF
36. Removal of Metal(Loids) from Acid Mine Drainage Using Manganese Oxide Wastes from a Mining-Metallurgical Process
- Author
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Piñon-Flores, Luis F., Gutiérrez-Ruiz, Margarita E., González-Chávez, José L., Amaro-Ramírez, Daniel E., Aguirre-Gómez, Arturo, and Molina-Reyes, Marco A.
- Published
- 2024
- Full Text
- View/download PDF
37. Navigating the landscape of e-commerce: thematic clusters, intellectual turning points, and burst patterns in online reputation management
- Author
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Lopez-Lopez, David, Plaza-Navas, Miquel Angel, Torres-Pruñonosa, Jose, and Martinez, Luis F.
- Published
- 2024
- Full Text
- View/download PDF
38. Systematic Review of Technological Aids to Social Interaction in Autistic Spectrum Disorders from Transversal Perspectives: Psychology, Technology and Therapy
- Author
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Guerrero-Vásquez, Luis F., López-Nores, Martín, Pazos-Arias, José J., Robles-Bykbaev, Vladimir E., Bustamante-Cacao, Katherine C., Jara-Quito, Henry J., Bravo-Torres, Jack F., and Campoverde-Jara, Pablo X.
- Published
- 2024
- Full Text
- View/download PDF
39. Expert Consensus on the Management of Adverse Events of Lorlatinib in the Treatment of ALK+ Advanced Non-small Cell Lung Cancer
- Author
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Arriola, Edurne, de Castro, Javier, García-Campelo, Rosario, Bernárdez, Beatriz, Bernabé, Reyes, Bruna, Jordi, Dómine, Manuel, Isla, Dolores, Juan-Vidal, Óscar, López-Fernández, Teresa, Nadal, Ernest, Rodríguez-Abreu, Delvys, Vares, María, Asensio, Úrsula, García, Luis F., and Felip, Enriqueta
- Published
- 2024
- Full Text
- View/download PDF
40. Design and Evaluation of a Mobile Robotic Assistant for Emotional Learning in Individuals with ASD: Expert Evaluation Stage
- Author
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Guerrero-Vásquez, Luis F., Robles-Bykbaev, Vladimir E., Cordero-Jara, Pedro A., and Jara-Jimbo, Pablo S.
- Published
- 2024
- Full Text
- View/download PDF
41. Mosquito (Diptera: Culicidae) species diversity and abundance patterns across tree height and microclimatic gradients in Indiana, USA
- Author
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Khan, Sajjad, Abel, Madison G., Bibbs, Christopher S., Faraji, Ary, and Chaves, Luis F.
- Published
- 2024
- Full Text
- View/download PDF
42. Electroencephalographic guided propofol-remifentanil TCI anesthesia with and without dexmedetomidine in a geriatric population: electroencephalographic signatures and clinical evaluation
- Author
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Mehler, Dominik M., Kreuzer, Matthias, Obert, David P., Cardenas, Luis F., Barra, Ignacio, Zurita, Fernando, Lobo, Francisco A, Kratzer, Stephan, Schneider, Gerhard, and Sepúlveda, Pablo O.
- Published
- 2024
- Full Text
- View/download PDF
43. Fiberoptic Endoscopy Evaluation of Swallowing (FEES) Findings Associated with High Pneumonia Risk in a Cohort of Patients at Risk of Dysphagia
- Author
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Giraldo-Cadavid, Luis F., Insignares, Diego, Velasco, Valentina, Londoño, Natalia, Galvis, Ana María, Rengifo, María Leonor, and Bastidas-Goyes, Alirio R.
- Published
- 2024
- Full Text
- View/download PDF
44. Landslide displacement prediction by using Bayesian optimization–temporal convolutional networks
- Author
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Yang, Jian, Huang, Zhijie, Jian, Wenbin, and Robledo, Luis F.
- Published
- 2024
- Full Text
- View/download PDF
45. Management and Long-Term Outcomes of Drug Reaction with Eosinophilia and Systemic Symptoms (DReSS) in Children: A Scoping Review
- Author
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Cherepacha, Nicole, St George-Hyslop, Frances, Chugani, Bindiya, Alabdeen, Yousef, Sanchez-Espino, Luis F., Mahood, Quenby, Sibbald, Cathryn, and Verstegen, Ruud H. J.
- Published
- 2024
- Full Text
- View/download PDF
46. Protecting breeding sites: a critical goal for the conservation of the golden eagle in Mexico under global change scenarios
- Author
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Gama-Rodríguez, Andrea M., García, Juan A., Lozano, Luis F., and Prieto-Torres, David A.
- Published
- 2024
- Full Text
- View/download PDF
47. Duality of Hoffman constants
- Author
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Pena, Javier F., Vera, Juan C., and Zuluaga, Luis F.
- Subjects
Mathematics - Optimization and Control ,90C05, 90C25, 90C57 - Abstract
Suppose $A\in \mathbb{R}^{m\times n}$ and consider the following canonical systems of inequalities defined by $A$: $$ \begin{array}{l} Ax=b\\ x \ge 0 \end{array} \qquad \text{ and }\qquad A^T y - c \le 0. $$ We establish some novel duality relationships between the Hoffman constants for the above constraint systems of linear inequalities provided some suitable Slater condition holds. The crux of our approach is a Hoffman duality inequality for polyhedral systems of constraints. The latter in turn yields an interesting duality identity between the Hoffman constants of the following box-constrained systems of inequalities: $$ \begin{array}{l} Ax=b\\ \ell \le x \le u \end{array}\qquad \text{ and }\qquad \ell \le A^T y - c \le u $$ for $\ell, u\in \mathbb{R}^n$ with $\ell < u.$, Comment: 21 pages
- Published
- 2023
48. Lorentz invariance violation and the CPT-odd electromagnetic response of a tilted anisotropic Weyl semimetal
- Author
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Gómez, Andrés, von Dossow, R. Martínez, Martín-Ruiz, A., and Urrutia, Luis F.
- Subjects
High Energy Physics - Theory ,Condensed Matter - Mesoscale and Nanoscale Physics ,High Energy Physics - Phenomenology - Abstract
We derive the electromagnetic response of a particular fermionic sector in the minimal QED contribution to the Standard Model Extension (SME), which can be physically realized in terms of a model describing a tilted and anisotropic Weyl semimetal (WSM). The contact is made through the identification of the Dirac-like Hamiltonian resulting from the SME with that corresponding to the WSM in the linearized tight-binding approximation. We first calculate the effective action by computing the non-perturbative vacuum polarization tensor using thermal field theory techniques, focusing upon the corrections at finite chemical potential and zero temperature. Next, we confirm our results by a direct calculation of the anomalous Hall current within a chiral kinetic theory approach. In an ideal Dirac cone picture of the WSM (isotropic and non-tilted) such response is known to be governed by axion electrodynamics, with the space-time dependent axion angle $\Theta (\mathbf{r},t) = 2 (\mathbf{b} \cdot \mathbf{r} - b _{0} t)$, being $2 \mathbf{b}$ and $2b _{0}$ the separation of the Weyl nodes in momentum and energy, respectively. In this paper we demonstrate that the node tilting and the anisotropies induce novel corrections at a finite density which however preserve the structure of the axionic field theory. We apply our results to the ideal Weyl semimetal $\mathrm{EuCd}_{2}\mathrm{As}_{2}$ and to the highly anisotropic and tilted monopnictide $\mathrm{TaAs}$.
- Published
- 2023
- Full Text
- View/download PDF
49. High Energy String Scattering in AdS
- Author
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Alday, Luis F., Hansen, Tobias, and Nocchi, Maria
- Subjects
High Energy Physics - Theory - Abstract
We study the AdS Virasoro-Shapiro amplitude in the limit of fixed-angle high energy scattering. A recent representation as a world-sheet integral allows to compute the amplitude in this regime by saddle point techniques, very much as in flat space. This result is then compared to a classical scattering computation in AdS and agreement is found. As a byproduct of this comparison we show that AdS curvature corrections exponentiate in the high energy limit., Comment: 18 pages, v2: JHEP version
- Published
- 2023
- Full Text
- View/download PDF
50. Towards Concept-based Interpretability of Skin Lesion Diagnosis using Vision-Language Models
- Author
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Patrício, Cristiano, Teixeira, Luís F., and Neves, João C.
- Subjects
Computer Science - Computer Vision and Pattern Recognition - Abstract
Concept-based models naturally lend themselves to the development of inherently interpretable skin lesion diagnosis, as medical experts make decisions based on a set of visual patterns of the lesion. Nevertheless, the development of these models depends on the existence of concept-annotated datasets, whose availability is scarce due to the specialized knowledge and expertise required in the annotation process. In this work, we show that vision-language models can be used to alleviate the dependence on a large number of concept-annotated samples. In particular, we propose an embedding learning strategy to adapt CLIP to the downstream task of skin lesion classification using concept-based descriptions as textual embeddings. Our experiments reveal that vision-language models not only attain better accuracy when using concepts as textual embeddings, but also require a smaller number of concept-annotated samples to attain comparable performance to approaches specifically devised for automatic concept generation., Comment: Accepted for publication in IEEE ISBI 2024
- Published
- 2023
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